KR102171425B1 - Organic electroluminescent element and method for manufacturing same - Google Patents

Abstract

(1) To provide an organic-inorganic hybrid-type organic electroluminescent device that suppresses crystallization of a low-molecular compound and exhibits excellent luminescence properties even when a low-molecular compound layer is used as a layer constituting an organic electroluminescent device, (2) conventional organic To provide an organic-inorganic hybrid-type organic electroluminescent device having more excellent luminescence properties than an inorganic hybrid-type organic electroluminescent device, and (3) an organic electroluminescent device that is easy to manufacture and has excellent luminous efficiency and lifetime. to provide. The present invention is an organic electroluminescent device having a structure in which a plurality of layers are stacked, the organic electroluminescent device having a metal oxide layer between a first electrode and a second electrode, on the metal oxide layer, and in an organic compound. It is an organic electroluminescent device, characterized in that it has a buffer layer formed by.

Description

Organic electroluminescent device and its manufacturing method {ORGANIC ELECTROLUMINESCENT ELEMENT AND METHOD FOR MANUFACTURING SAME}

The present invention relates to an organic electroluminescent device and a method of manufacturing the same. More specifically, it relates to an organic electroluminescent element that can be used as a display device such as a display unit of an electronic device or a lighting device, and a method of manufacturing the same.

Organic electroluminescent elements (organic EL elements) are expected as new light-emitting elements applicable to display devices and lighting.

Organic electroluminescent devices are thin, flexible, and flexible. In addition, when used as a display device, high luminance and high-precision display are possible compared to the current mainstream liquid crystal or plasma display devices. Compared to this, since it has excellent features such as a wide viewing angle, it is an element that is expected to expand its use as a display for televisions and mobile phones in the future, or as a lighting device.

The organic EL device has a structure in which one or more layers including a light-emitting layer formed of a light-emitting organic compound is interposed between an anode and a cathode, and holes injected from the anode and electrons injected from the cathode are recombined. The energy at the time of doing so is used to excite the light-emitting organic compound to obtain light emission. The organic EL device is a current-driven device, and in order to utilize the flowing current more efficiently, the device structure has been improved in various ways, and various studies are being conducted on the material of the layer constituting the device.

The organic electroluminescent device has a structure in which a plurality of layers, such as an electron transport layer, a light emitting layer, and a hole transport layer, are stacked between a cathode and an anode, and research and development are being made on materials suitable for constituting each layer. . For example, a light emitting material containing a compound having a specific structure having a boron atom is disclosed (see Patent Document 1). Further, it is disclosed that a compound having a specific structure having a boron atom is preferable as a hole blocking layer of an organic electroluminescent device (refer to Patent Document 2).

In addition, in an organic electroluminescent device that excites a light-emitting organic compound by using energy at the time of recombination with a hole injected from the anode and electrons injected into the cathode, and emits light, injection of holes from the anode and injection of electrons from the cathode are performed. Since it is important that all of them be smoothly performed, various studies have been conducted on the materials of the hole injection layer and the electron injection layer so that the hole injection and electron injection can be performed more smoothly. Recently, as a material for the electron injection layer that can be applied, polyethylene Organic electroluminescent devices having a pure structure using a compound modified with imine or polyethyleneimine have been reported (see Non-Patent Documents 1 to 3).

However, organic electroluminescent devices in which the layers between the cathode and the anode are all formed of an organic compound are likely to be deteriorated by oxygen or water as a result, and strict sealing is indispensable to prevent their invasion. This is a cause of making the manufacturing process of the organic electroluminescent element complicated. On the other hand, an organic-inorganic hybrid type electroluminescent device (HOILED device) in which a part of the layer between the cathode and the anode is made of inorganic oxide has been proposed (see Patent Document 3). In this device, by changing the hole transport layer and the electron transport layer to inorganic oxide, it has become possible to use FTO or ITO as a conductive oxide electrode as a cathode, and gold as an anode. This means that there are no restrictions on the electrodes from the viewpoint of device driving. As a result, it is not necessary to use a metal having a small work function, such as an alkali metal or an alkali metal compound, and it is possible to emit light without strict sealing. In addition, this HOILED device has the characteristic that the cathode is directly on the substrate, and the anode is inverted structure. With the development of oxide TFTs, while application to large-sized organic EL displays is being studied, organic ELs with an inverted structure are attracting attention from the characteristics of n-type oxide TFTs. This HOILED device is expected to develop as a candidate for an inverted structure organic EL device.

As a conventional organic-inorganic hybrid type organic electroluminescent device, an anode and a cathode, one or more organic compound layers sandwiched between the anode and the cathode, and between the anode and the organic compound layer, and the cathode and the organic compound layer In the meantime, an organic thin film light-emitting device having at least one or more types of metal oxide thin films is disclosed (see Patent Document 4). In addition, an anode, a cathode, and one or more layers of an organic compound layer sandwiched between the anode and the cathode, and between the anode and the organic compound layer or between the cathode and the organic compound layer, have at least one metal oxide thin film, and between each of the layers An organic thin-film electroluminescent device having a single layer or a plurality of layers, a self-assembled monomolecular film that serves as an energy barrier in the main carrier and does not become an energy barrier in the opposite carrier is disclosed (see Patent Document 5). In addition, an organic-inorganic hybrid type organic electroluminescent device having a structure in which an iridium compound is added as a dopant to a polyvinylcarbazole polymer is laminated on a metal oxide layer (refer to Non-Patent Document 4) B, poly(9,9) -An organic-inorganic hybrid type organic electroluminescent device (see Non-Patent Document 5) in which an iridium compound is added to -dioctylfluorenyl-2,7-diyl) as a light emitting layer is disclosed.

Japanese Laid-Open Patent Publication No. 2011-184430 International Publication No. 2005/062676 Japanese Patent Application Publication No. 2009-70954 Japanese Unexamined Patent Publication No. 2007-53286 Japanese Patent Application Publication No. 2012-4492

Tao Xiong and 3 others 「Applied Physics Letters」 93, 2008, pp123310-1 Yinhua Zhou and 21 others 「Science」 No.336, 2012, pp327 Jianshan Chen and 6 others 「Journal or Materials Chemistry」 2012, Vol. 22, pp5164 Henk J. Bolink and 3 others 「Advanced Materials」, 2010, Vol. 22, p. 2198-2201 Henk J. Bolink and 2 others 「The Chemistry of Materials」, 2009, Vol. 21, p. 439-441

As described above, research and development have been made on organic electroluminescent devices of organic-inorganic hybrid type together with organic electroluminescent devices in which each layer constituting the organic electroluminescent device is composed of an organic material.

It is believed that the organic-inorganic hybrid type organic electroluminescent device can have both the flexibility and moldability of the organic component and the strength and durability of the inorganic component, and compared to the organic electroluminescent device in which each layer is composed of only organic compounds. Due to the high resistance to oxygen and water, the necessity of strictly sealing each layer inside the device is reduced, and it has advantages such as less labor during manufacturing, and thus, practical use is expected. On the other hand, in the organic-inorganic hybrid type organic electroluminescent device, there is still room for improvement in various characteristics such as light emission characteristics compared to the organic electroluminescent device in which each layer constituting the organic electroluminescent device is composed of an organic material. There is a demand for the development of an organic-inorganic hybrid type organic electroluminescent device having improved properties such as characteristics.

In general, in an organic electroluminescent device in which each layer constituting the organic electroluminescent device is composed of an organic material, a method of laminating a plurality of types of low molecular compound layers by a method such as vacuum evaporation, or doping a guest molecule in the host molecule. It is known that an element having high light emission characteristics can be obtained by a method or the like. On the other hand, the structure of an organic-inorganic hybrid type organic electroluminescent device that has been studied in the past has been mainly formed by coating a polymer compound as a light emitting layer. On the other hand, the present inventor uses a low molecular weight compound as a material for forming a light emitting layer or a hole transport layer, etc., in order to improve the light emission characteristics of an organic-inorganic hybrid type organic electroluminescent device, Various studies have been made on the form of laminating the low molecular weight compound layer and the form of doping guest molecules in host molecules. As a result of doing so, if the oxide layer formed on the cathode and the low molecular compound layer are in contact, crystallization of the low molecular compound layer in contact with the oxide layer occurs, thereby increasing the leakage current and lowering the current efficiency, and in a remarkable case, uniformity due to crystallization occurs. It was found that a new problem arises that a problem that surface light emission cannot be obtained occurs. Although this is not observed, it is thought that there is an adverse effect even in a device having a coating-type polymer organic layer, and solving this problem is considered to be important for extending the life of an organic-inorganic hybrid-type organic electroluminescent device.

In addition, in the organic-inorganic hybrid type organic electroluminescent device, there is a problem that the injection of electrons from the cathode is less than that from the anode, and the holes injected from the anode are not sufficiently utilized for light emission. In addition, originally, good physical and electrical contact over a long period of time between the inorganic layer and the organic layer is difficult, which leads to a short life of the device, which is a big problem.

An organic electroluminescent device that is expected to expand its use in applications such as display devices and lighting devices is an important factor because it is also an important factor to be easy to manufacture, so expectation for organic-inorganic hybrid organic electroluminescent devices that do not require strict sealing. Is high, and there is a need for a method of further increasing the luminous efficiency and lifetime of the organic-inorganic hybrid type organic electroluminescent device. In addition, in a display application, a HOILED device having an inverse structure is useful in a circuit, and its development is desired.

The present invention has been made in view of the above conditions, and (1) even when a low molecular weight compound layer is used as a layer constituting an organic electroluminescent device, crystallization of a low molecular weight compound is suppressed, and an organic-inorganic hybrid type organic electroluminescent device having excellent light emission characteristics To provide, (2) to provide an organic-inorganic hybrid-type organic electroluminescent device having more excellent luminescence properties than a conventional organic-inorganic hybrid-type organic electroluminescent device, and, (3) easy to manufacture, and An object of the present invention is to provide an organic electroluminescent device having excellent luminous efficiency and lifetime.

In the organic-inorganic hybrid type organic electroluminescent device having a metal oxide layer between a first electrode and a second electrode, the inventors of the present invention have a buffer layer formed of an organic compound on the metal oxide layer. I figured out that I could solve the task. The buffer layer referred to herein is a layer that solves the problem of the organic-inorganic hybrid type organic electroluminescent device, crystallization of an organic layer such as a light-emitting layer, low electron injection ability, and long-term physical and chemical stability of the interface. Specifically, in order to prevent crystallization caused by irregularities on the oxide surface, an organic material having a higher molecular weight is preferable, and in addition, in order to improve the electron injection ability, it is preferable to form the energy level up to the light emitting layer in a stepwise shape. Furthermore, it is more preferable to increase the number of carriers by a technique such as doping so as to smoothly pump the existing energy as a problem peculiar to the inverse structure (to increase energy stairs (uphill)). In order to improve the electron injection ability, there is also a method of generating an interfacial dipole by arranging a large number of nitrogen elements on the surface, and this is also preferable. And, in order to stably exist for a long period of time, it is desirable to prevent the presence of a local electric field or to prepare a chemical bond that can withstand it. The former is a wide energy level change due to an increase in the number of carriers realized by a method such as doping and the formation of an electron level with a good balance in a stepwise shape. The latter is a chemical bond of an organic material in the buffer layer with a metal element on the oxide surface. A specific example is described below.

The inventors of the present invention investigated a means to solve a new problem of crystallization of a low-molecular compound layer, which was discovered during various studies on a method of improving the luminescence characteristics of an organic-inorganic hybrid type organic electroluminescent device. As a result, oxides formed on the cathode When a buffer layer of a predetermined film thickness is disposed between the layer and a low molecular compound layer such as a light-emitting layer, and a buffer layer of a predetermined film thickness is formed by applying an organic compound, and a low-molecular compound layer such as a light-emitting layer is laminated on the buffer layer, the low-molecular compound in the low-molecular compound layer The crystallization of is suppressed, and thus it was found that even when the organic-inorganic hybrid type organic electroluminescent device has a layer formed from a low molecular weight compound as a light emitting layer or the like, it is possible to suppress the leakage current and obtain uniform surface light emission. In addition, the present inventors have found that when a boron-containing compound or a boron-containing polymer having a specific structure is used as the organic compound forming the buffer layer, the buffer layer formed from the organic compound also exhibits an excellent function as an electron transport layer.

In addition, as a result of various studies on a method for improving the light emission characteristics of an organic-inorganic hybrid type organic electroluminescent device, the present inventor has a metal oxide layer between the first electrode and the second electrode, and is formed on the metal oxide layer. For example, if an organic electroluminescent device having a buffer layer formed by an organic compound is used, and a reducing agent is included in the buffer layer of the organic electroluminescent device, the reducing agent functions as an n-dopant for supplying electrons, and conventional organic inorganic It has been found that the organic electroluminescent device has superior light emission characteristics compared to the hybrid type organic electroluminescent device. In addition, organic electroluminescence having a structure having a first metal oxide layer, a buffer layer, a low molecular weight compound layer including a light emitting layer stacked on the buffer layer, and a second metal oxide layer in this order between the first electrode and the second electrode. It has also been found that an organic electroluminescent device in a form in which a reducing agent is included in the buffer layer of this organic electroluminescent device is preferable.

In addition, the present inventors have studied a number of ways to further increase the luminous efficiency and life of an organic-inorganic hybrid type organic electroluminescent device that does not require strict sealing. As a result, on the metal oxide layer between the anode and the cathode, It was found that when a nitrogen-containing film of a predetermined thickness was formed, electron injection characteristics were improved and the life of the device was extended. Among them, it was found that it is more preferable to have a nitrogen-containing film formed by a method of forming a nitrogen-containing film by decomposing a nitrogen-containing film or a nitrogen-containing compound having a high ratio of nitrogen atoms in the atoms constituting the nitrogen-containing film. It was found that it was formed by decomposition of the compound, and it was more preferable that the nitrogen atom ratio in the atoms constituting the nitrogen-containing film was high. The present inventors have found that using such a nitrogen-containing film as a layer constituting an organic-inorganic hybrid type organic electroluminescent device provides an organic electroluminescent device having excellent luminous efficiency, high driving stability, and long driving life. It found out, conceived that the said subject can be solved wonderfully, and arrived at this invention.

That is, the present invention is an organic electroluminescent device having a structure in which a plurality of layers are stacked, the organic electroluminescent device has a metal oxide layer between the first electrode and the second electrode, on the metal oxide layer, organic It is an organic electroluminescent device, characterized in that it has a buffer layer formed of a compound.

Further, as an organic electroluminescent device having a structure in which a plurality of layers are stacked, the organic electroluminescent device includes a first metal oxide layer, a buffer layer, and an emission layer stacked on the buffer layer between a first electrode and a second electrode. An organic electroluminescent device comprising a low molecular weight compound layer comprising a, and a second metal oxide layer in this order, wherein the buffer layer is a layer having an average thickness of 5 to 50 nm formed by applying a solution containing the organic compound Is the first preferred embodiment of the organic electroluminescent device of the present invention.

Further, as an organic electroluminescent device having a structure in which a plurality of layers are stacked, the organic electroluminescent device includes a first metal oxide layer, a buffer layer, and an emission layer stacked on the buffer layer between a first electrode and a second electrode. An organic electroluminescent device comprising a low molecular weight compound layer and a second metal oxide layer in this order, wherein the buffer layer contains a reducing agent is a second preferred form of the organic electroluminescent device of the present invention.

Further, as an organic electroluminescent device having a structure in which a plurality of layers are stacked between an anode and a cathode formed on a substrate, the organic electroluminescent device has a metal oxide layer between an anode and a cathode, and In addition, an organic electroluminescent device comprising a nitrogen-containing film and having a layer having an average thickness of 3 to 150 nm is a third preferred embodiment of the organic electroluminescent device of the present invention.

The present invention is described in detail below.

Further, a combination of two or more individual preferred embodiments of the present invention described below is another preferred embodiment of the present invention.

The organic electroluminescent device of the present invention is an organic electroluminescent device having a structure in which a plurality of layers are stacked, and has a metal oxide layer between the first electrode and the second electrode, and on the metal oxide layer, by an organic compound. It has a buffer layer to be formed.

It is a preferred embodiment of the organic electroluminescent device of the present invention that the first electrode is a cathode formed on a substrate, and a metal oxide layer and a buffer layer formed of an organic compound are in this order between the anode, which is the second electrode.

Further, the buffer layer is a layer having an average thickness of 3 nm or more formed by applying a solution containing an organic compound, and the buffer layer is formed adjacent to the metal oxide layer is also a preferred embodiment of the organic electroluminescent device of the present invention.

In the organic electroluminescent device of the present invention, there are three different preferred forms of the device layer structure and buffer layer. In the following, these three preferred embodiments will be described in order. Further, those corresponding to two or more of these three preferred forms are also preferred forms of the organic electroluminescent device of the present invention.

[Organic EL device of the first preferred embodiment of the present invention]

The organic electroluminescent device of the first preferred form of the present invention (hereinafter, also referred to as the first organic electroluminescent device of the present invention) is a first metal oxide layer, a buffer layer, and a buffer layer between the first electrode and the second electrode. A low molecular weight compound layer including a light emitting layer stacked thereon, and a second metal oxide layer are in this order, and the average thickness of the buffer layer is 3 nm. Further, it is preferable that the average thickness of the buffer layer is 5 to 50 nm. In addition, it is also preferable that the buffer layer has an electron level in which the order of the heights of the electron levels of each layer from the electrode formed on the substrate to the light emitting layer is the stacking order of these layers.

The first organic electroluminescent device of the present invention has such a configuration, so that even when a layer constituting an organic electroluminescent device such as a light-emitting layer is a low-molecular compound layer, crystallization of the low-molecular compound layer can be suppressed, and leakage current is reduced. By suppressing, uniform surface light emission can be obtained.

In the organic-inorganic hybrid type organic electroluminescent device, the cause of crystallization of the low molecular weight compound layer is considered as follows.

In an organic-inorganic hybrid type organic electroluminescent device, a first electrode disposed on a substrate such as glass and a first metal oxide layer are present, and a low molecular weight compound layer including a light emitting layer is formed thereon. Here, according to the conventional method, the first metal oxide layer is formed by a method such as a spray pyrolysis method, a sol gel method, or a sputtering method, and the surface is not smooth and has irregularities. When a low molecular weight compound layer including a light emitting layer is formed on the first metal oxide layer by a method such as vacuum deposition, the irregularities on the surface of the first metal oxide layer become crystal nuclei, and the low molecular weight compound layer in contact with the first metal oxide layer Crystallization is promoted. For this reason, even if the organic electroluminescent element is completed, a large leakage current flows, the light-emitting surface becomes uneven, and an element that can withstand practical use cannot be obtained.

On the other hand, in an organic electroluminescent device having a so-called conventional structure that does not have a first metal oxide layer on the first electrode, it is available that the first electrode surface is polished sufficiently smoothly, for example, on the first electrode surface. Even if the low molecular weight compound layer including the light emitting layer is directly formed into a film, the problem of crystallization is unlikely to occur. Therefore, such crystallization is a problem peculiar to an organic-inorganic hybrid-type organic electroluminescent device, and the first organic electroluminescent device of the present invention has the above-described configuration, so that such organic-inorganic hybrid type organic electroluminescence It is possible to solve the problem specific to the device.

When the first organic electroluminescent device of the present invention has the above-described preferred structure, a buffer layer having an average thickness of 5 to 50 nm formed from the first metal oxide layer and the organic compound between the first electrode and the second electrode, As long as it has a low molecular weight compound layer including a light emitting layer laminated on the buffer layer and a second metal oxide layer in this order, other layers may be provided.

In addition, in this invention, a low molecular compound means a compound which is not a high molecular compound (polymer), and does not necessarily mean a compound with a low molecular weight.

The low-molecular compound layer including the light-emitting layer is one layer formed of a low-molecular compound or a plurality of layers formed of a low-molecular compound are stacked, and one of the layers is a light-emitting layer. That is, the low-molecular compound layer including the light-emitting layer is either a light-emitting layer formed of a low-molecular compound, or a stack of a light-emitting layer formed of a low-molecular compound and other layers formed of a low-molecular compound. The other layers formed of the low molecular weight compound may be one layer or two or more layers. Further, the order in which the light emitting layer and other layers are stacked is not particularly limited.

It is preferable that the other layer formed of the low molecular compound is a hole transport layer or an electron transport layer. That is, when the low molecular weight compound layer is made of a plurality of layers, it is preferable to have a hole transport layer and/or an electron transport layer as other layers other than the light emitting layer. As described above, it is one of the preferred embodiments of the first organic electroluminescent device of the present invention that the organic electroluminescent device has a hole transport layer and/or an electron transport layer as independent layers different from the emission layer.

When the first organic electroluminescent device of the present invention has a hole transport layer as an independent layer, it is preferable to have a hole transport layer between the light emitting layer and the second metal oxide layer. When the first organic electroluminescent device of the present invention has an electron transport layer as an independent layer, it is preferable to have an electron transport layer between the light emitting layer and the buffer layer formed from the organic compound.

When the first organic electroluminescent device of the present invention does not have a hole transport layer or an electron transport layer as an independent layer, any of the layers having as an essential configuration of the first organic electroluminescent device of the present invention also functions as these layers. .

One of the preferred forms of the first organic electroluminescent device of the present invention is that the organic electroluminescent device comprises a first electrode, a first metal oxide layer, a buffer layer formed from an organic compound, an emission layer, a hole transport layer, a second metal oxide layer, and a second It consists only of an electrode, and any of these layers is a form that also functions as an electron transport layer.

In addition, the organic electroluminescent device comprises only a first electrode, a first metal oxide layer, a buffer layer formed from an organic compound, a light-emitting layer, a second metal oxide layer, and a second electrode, and any of these layers is a hole transport layer and an electron transport layer. Another preferred form of the first organic electroluminescent device of the present invention is also a form that serves as a function.

In the first organic electroluminescent device of the present invention, the first electrode is a cathode, and the second electrode is an anode. In the organic electroluminescent device of the present invention, a known conductive material can be suitably used as the anode and the cathode, but at least one of them is preferably transparent for light extraction. Examples of known transparent conductive materials include ITO (tin-doped indium oxide), ATO (antimony-doped indium oxide), IZO (indium-doped zinc oxide), AZO (aluminum-doped zinc oxide), FTO (fluorine-doped indium oxide), In ₃ O Oxides, such as ₃ , SnO ₂ , Sb-containing SnO ₂ , and Al-containing ZnO, etc. are mentioned. Examples of the opaque conductive material include calcium, magnesium, aluminum, tin, indium, copper, silver, gold, platinum, and alloys thereof.

As the cathode, among these, ITO, IZO, and FTO are preferable.

Examples of the anode include Au, Pt, Ag, Cu, Al, or an alloy containing these. Among these, Au, Ag, and Al are preferable.

As described above, since the metal generally used for the positive electrode can be used for the negative electrode and the positive electrode, it is also possible to easily realize the case where light extraction from the upper electrode is assumed (in the case of a top emission structure), and the electrode is Various selections can be used for each electrode. For example, Al as the lower electrode and ITO as the upper electrode.

The average thickness of the first electrode is not particularly limited, but is preferably 10 to 500 nm. More preferably, it is 100 to 200 nm. The average thickness of the first electrode can be measured by a stylus type step meter or a spectral ellipsometry.

The average thickness of the second electrode is not particularly limited, but is preferably 10 to 1000 nm. More preferably, it is 30 to 150 nm. Moreover, even in the case of using an impermeable material, it can be used as a top emission type and a transparent type anode, for example, by setting the average thickness to about 10 to 30 nm.

The average thickness of the second electrode can be measured at the time of film formation using a crystal oscillator film thickness meter.

The first metal oxide layer functions as an electron injection layer or an electrode (cathode), and the second metal oxide layer functions as a hole injection layer.

The first metal oxide layer is a layer consisting of one layer of a single metal oxide film, or a layer of a semiconductor or insulating bulk layer thin film, which is a single layer or a layer obtained by laminating and/or mixing two or more types of metal oxides. Metal elements constituting the metal oxide include magnesium, calcium, strontium, barium, titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, manganese, indium, gallium, iron, cobalt, nickel, copper, and zinc. , Cadmium, aluminum, silicon, and tin are selected from the group consisting of. Among these, it is preferable that at least one of the metal elements constituting the laminated or mixed metal oxide layer is a layer made of magnesium, aluminum, calcium, zirconium, hafnium, silicon, titanium, zinc, and tin, and among them, a single metal oxide, It is preferable to contain a metal oxide selected from the group consisting of magnesium oxide, tungsten oxide, niobium oxide, iron oxide, aluminum oxide, zirconium oxide, hafnium oxide, silicon oxide, titanium oxide, zinc oxide, and tin oxide.

Examples of the above-described single layer or a layer in which two or more kinds of metal oxides are laminated and/or mixed include titanium oxide/zinc oxide, titanium oxide/magnesium oxide, titanium oxide/zirconium oxide, titanium oxide/aluminum oxide, titanium oxide/hafnium oxide, and oxidation. Stacked and/or mixed with a combination of metal oxides such as titanium/silicon oxide, zinc oxide/magnesium oxide, zinc oxide/zirconium oxide, zinc oxide/hafnium oxide, zinc oxide/silicon oxide, calcium oxide/aluminum oxide, or oxidation Titanium/zinc oxide/magnesium oxide, titanium oxide/zinc oxide/zirconium oxide, titanium oxide/zinc oxide/aluminum oxide, titanium oxide/zinc oxide/hafnium oxide, titanium oxide/zinc oxide/silicon oxide, indium oxide/gallium oxide/ And laminated and/or mixed combinations of three types of metal oxides such as zinc oxide. Among these, IGZO as an oxide semiconductor exhibiting good properties as a special composition and 12CaO·7Al ₂ O ₃ as an electride are also included.

Further, in the present invention, those having a sheet resistance lower than 100 Ω/□ are classified as conductors, and those having a sheet resistance higher than 100 Ω/□ are classified as semiconductors or insulators. Therefore, thin films such as ITO (tin-doped indium oxide), ATO (antimony-doped indium oxide), IZO (indium-doped zinc oxide), AZO (aluminum-doped zinc oxide), and FTO (fluorine-doped indium oxide) known as transparent electrodes are It does not correspond to one layer constituting the first metal oxide layer of the present invention in that it has high conductivity and is not included in the category of a semiconductor or an insulator.

The second metal oxide layer is not particularly limited, but one or two or more of vanadium oxide (V ₂ O ₅ ), molybdenum oxide (MoO ₃ ), tungsten oxide (WO ₃ ), ruthenium oxide (RuO ₂ ), etc. You can use Among these, it is preferable to use vanadium oxide or molybdenum oxide as a main component. When the second metal oxide layer is composed of vanadium oxide or molybdenum oxide as a main component, the second metal oxide layer injects holes from the second electrode and transports them to the light emitting layer or the hole transport layer. do. In addition, since vanadium oxide or molybdenum oxide itself has high hole transport properties, there is an advantage in that it is also possible to preferably prevent a decrease in the injection efficiency of holes from the second electrode to the light emitting layer or the hole transport layer. More preferably, it is composed of vanadium oxide and/or molybdenum oxide.

The average thickness of the first metal oxide layer may be from 1 nm to several µm, and is not particularly limited, but is preferably 1 to 1000 nm from the viewpoint of making an organic electroluminescent device capable of driving at a low voltage. . More preferably, it is 2-100 nm.

The average thickness of the second metal oxide layer is not particularly limited, but is preferably 1 to 1000 nm. More preferably, it is 5 to 50 nm.

The average thickness of the first metal oxide layer can be measured by a stylus type step meter or spectroscopic ellipsometry.

The average thickness of the second metal oxide layer can be measured at the time of film formation using a crystal oscillator film thickness meter.

As the material for the light-emitting layer, any low-molecular compound that can be used normally as a material for the light-emitting layer may be used, and these may be mixed and used.

As a low molecular weight one, a tri-coordinated iridium complex having 2,2'-bipyridin-4,4'-dicarboxylic acid in the ligand, pactris (2-phenylpyridine) iridium (Ir(ppy) ₃ ), 8-hydroxyquinoline aluminum (Alq ₃ ), tris (4-methyl-8 quinolinolate) aluminum (III) (Almq ₃ ), 8-hydroxyquinoline zinc (Znq ₂ ), (1,10-phenanthrol Lin)-tris(4,4,4-trifluoro-1-(2-thienyl)-butane-1,3-dionate) europium (III) (Eu(TTA) ₃ (phen)), 2, Various metal complexes such as 3,7,8,12,13,17,18-octaethyl-21H,23H-porphine platinum (II); distyrylbenzene (DSB), diaminodistyrylbenzene (DADSB) and Same benzene compounds, naphthalene compounds, phenanthrene compounds, chrysene compounds, perylene compounds, coronene compounds, anthracene compounds, pyrene compounds, pyran compounds, acridine compounds, stilbene compounds, carbazole compounds Compounds, thiophene compounds, benzoxazole compounds, benzoimidazole compounds, benzothiazole compounds, butadiene compounds, naphthalimide compounds, coumarin compounds, perinone compounds, oxadiazole compounds, aldazine compounds , A cyclopentadiene compound, a quinacridone compound, a pyridine compound, a spiro compound such as 2,2',7,7'-tetraphenyl-9,9'-spirobifluorene, a metal or non-metal phthalocyanine Compounds, and further, boron compound materials described in Japanese Patent Application Laid-Open No. 2009-155325, Japanese Patent Application 2010-28273, Japanese Patent Application 2010-230995, and Japanese Patent Application 2011-6458. One or two or more types can be used.

The light emitting layer may contain a dopant. As the dopant, any compound commonly used as a dopant can be used. Examples of compounds that can be used as dopants include iridium compounds; 4,4'-bis(9-ethyl-3-carbazovinylene)-1,1'-biphenyl (BCzVBi), and other low-molecular organic compounds. And one or two or more of these can be used.

When the light emitting layer contains a dopant, the content of the dopant is preferably 0.5 to 20 mass% with respect to 100 mass% of the material forming the light emitting layer. If it is such a content, the light emission characteristic can be made more favorable. More preferably, it is 0.5-10 mass %, More preferably, it is 1-6 mass %.

The average thickness of the light emitting layer is not particularly limited, but is preferably 10 to 150 nm. More preferably, it is 20-100 nm. More preferably, it is 40-100 nm.

The average thickness of the light emitting layer can be measured by a crystal oscillator film thickness meter in the case of a low molecular weight compound, and by a contact-type step meter in the case of a polymer compound.

As the material for the hole transport layer, any low-molecular compound commonly used as a material for the hole transport layer may be used, and these may be mixed and used.

Examples of the low molecular weight compound include rilcycloalkane compounds, arylamine compounds, phenylenediamine compounds, carbazole compounds, stilbene compounds, oxazole compounds, triphenylmethane compounds, pyrazoline compounds, and benzine (cyclohexadiene )-Based compound, triazole-based compound, imidazole-based compound, oxadiazole-based compound, anthracene-based compound, fluorenone-based compound, aniline-based compound, silane-based compound, pyrrole-based compound, florene-based compound, porphyrin-based compound, quinacry A pig-based compound, a metal or metal-free phthalocyanine-based compound, a metal or metal-free naphthalocyanine-based compound, and a benzidine-based compound, and one or two or more of these may be used.

Among these, N,N'-di(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine (α-NPD), arylamines such as TPTE Compounds are preferred.

When the first organic electroluminescent device of the present invention has a hole transport layer as an independent layer, the average thickness of the hole transport layer is not particularly limited, but it is preferably 10 to 150 nm. More preferably, it is 20-100 nm, More preferably, it is 40-100 nm.

The average thickness of the hole transport layer can be measured at the time of film formation with a crystal oscillator film thickness meter.

As the material for the electron transport layer, any low-molecular compound commonly used as the material for the electron transport layer may be used, and these may be mixed and used.

Examples of low molecular weight compounds that can be used as the material for the electron transport layer include boron-containing compounds represented by formula (1) described below, as well as pyridine derivatives, quinoline derivatives, pyrimidine derivatives, pyrazine derivatives, phenanthroline derivatives, triazine derivatives, and triazoles. Derivatives, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, aromatic cyclic tetracarboxylic anhydrides, bis[2-(2-hydroxyphenyl)benzothiazolato]zinc (Zn(BTZ) ₂ ), tris( Various metal complexes such as 8-hydroxyquinolinato) aluminum (Alq ₃ ), and organosilane derivatives such as silol derivatives, and one or two or more of these may be used.

Among these, metal complexes such as Alq ₃ and pyridine derivatives such as tris-1,3,5-(3'-(pyridin-3''-yl)phenyl)benzene (TmPyPhB) are preferable.

When the first organic electroluminescent device of the present invention has an electron transport layer as an independent layer, the average thickness of the electron transport layer is not particularly limited, but is preferably 10 to 150 nm. More preferably, it is 20-100 nm, More preferably, it is 40-100 nm.

The average thickness of the electron transport layer can be measured at the time of film formation with a crystal oscillator film thickness meter.

In the first organic electroluminescent device of the present invention, the method of forming the first and second metal oxide layers, the second electrode, the light-emitting layer, the hole transport layer, and the electron transport layer is not particularly limited. Chemical vapor deposition (CVD) such as CVD and laser CVD, dry plating methods such as vacuum deposition, sputtering, and ion plating, thermal spraying methods, and wet plating methods such as electrolytic plating, immersion plating, and electroless plating, sol-gel method, MOD method, spray pyrolysis method, doctor blade method using fine particle dispersion, printing technology such as spin coat method, inkjet method, screen printing method, atomic layer deposition (ALD) method, etc. can be used, and an appropriate method can be selected according to the material. Can be used.

The buffer layer included in the first organic electroluminescent device of the present invention is a layer formed by applying a solution containing an organic compound. By forming a buffer layer having a predetermined thickness by application, it becomes possible to effectively suppress the crystallization of the low molecular weight compound to be formed on the buffer layer.

The method of applying the solution containing the organic compound is not particularly limited, and the spin coating method, casting method, microgravure coating method, gravure coating method, bar coating method, roll coating method, wire bar coating method, slit coating method, Various coating methods, such as a dip coating method, a spray coating method, a screen printing method, a flexo printing method, an offset printing method, and an inkjet printing method, can be used. Among these, the spin coating method is preferable.

Since the unevenness existing on the surface of the first metal oxide layer is smoothed by forming the buffer layer as a coating film, crystallization of the low-molecular compound formed on the buffer layer next is suppressed.

The solvent used to prepare a solution containing the organic compound is not particularly limited as long as it can dissolve the organic compound, but examples include nitric acid, sulfuric acid, ammonia, hydrogen peroxide, water, carbon disulfide, carbon tetrachloride, Inorganic solvents such as ethylene carbonate, ketone solvents, alcohol solvents, ether solvents, cellosolve solvents, aliphatic hydrocarbon solvents such as hexane, pentane, heptane, and cyclohexane, aromatic hydrocarbons such as toluene, xylene and benzene Various organic solvents such as solvents, aromatic heterocyclic solvents, amide solvents, halogen compound solvents, ester solvents, sulfur compound solvents, nitrile solvents, organic acid solvents, or mixed solvents containing these. I can. Among these, THF, toluene, and chloroform are preferable.

The solution containing the organic compound preferably has a concentration of the organic compound in the solvent of 0.05 to 10% by mass. If it is such a concentration, it is possible to suppress the occurrence of uneven coating and irregularities when applied. The concentration of the organic compound in the solvent is more preferably 0.1 to 5% by mass, and still more preferably 0.1 to 3% by mass.

It is preferable that the buffer layer has an electron level in which the order of the heights of the electron levels of each layer from the electrode formed on the substrate to the light emitting layer is the order of stacking these layers. The order of the height of the electron level of each layer from the electrode (cathode) formed on the substrate to the light emitting layer is the same as that of the stacking order, and the height of the electron level from the electrode (cathode) toward the light emitting layer is increased stepwise from the electrode (cathode) to the light emitting layer. Electron movement to the light emitting layer is relatively smooth during the uphill.

It is preferable that the buffer layer has an average thickness of 5 to 50 nm. When the average thickness is in such a range, the effect of suppressing crystallization of the low molecular weight compound layer including the light emitting layer can be sufficiently exhibited. If the average thickness of the buffer layer is less than 5 nm, there is a fear that the unevenness present on the first metal oxide surface cannot be sufficiently smoothed, the leakage current becomes large, and the effects of the present invention cannot be sufficiently exhibited. Moreover, if the average thickness of the buffer layer is thicker than 50 nm, the driving voltage increases, which is not preferable for practical purposes. In addition, when a compound having a preferable structure in the present invention described later is used as the organic compound, the buffer layer can sufficiently exhibit the function as an electron transport layer. The average thickness of the buffer layer is more preferably 10 to 30 nm.

The average thickness of the buffer layer can be measured by a stylus type step meter or spectral ellipsometry.

By the way, in Japanese Laid-Open Patent Publication No. 2012-4492 (Patent Document 5) described above, an anode, a cathode, a single layer or a plurality of layers of an organic compound layer sandwiched between the anode and the cathode, and between the anode and the organic compound layer or between the cathode and the organic compound layer. A self-organizing monomolecular film having at least one or more metal oxide thin films between the compound layers, and one or more layers between each of them, which is an energy barrier in the main carrier and does not become an energy barrier in the opposite carrier. An organic thin film electroluminescent device is disclosed. The patent document discloses that in an organic-inorganic hybrid electroluminescent device, by forming a self-organizing monomolecular film having a specific energy level on an oxide substrate (by a film forming method including coating), the carrier opposite to the main carrier is It has been described for the device configuration that carrier is injected by tunneling. In addition, it is described that carrier injection by tunneling functions preferably when the self-assembled monomolecular film is a thin film of 2 nm or less (from the description of Patent Document 5, the average thickness of the organic compound layer is estimated to be 2 nm or less). On the other hand, as described in Examples to be described later, in order to obtain a sufficient effect for the problem to be solved in the present invention, it is necessary that the average thickness of the organic compound layer is 5 nm or more.

In this way, the present invention and the invention disclosed in Patent Document 5 are essentially different in the subject to be solved and the means for solving, and should be clearly distinguished.

The first organic electroluminescent device of the present invention may be formed by stacking layers constituting the organic electroluminescent device on a substrate. When each layer is stacked on a substrate, it is preferable that each layer is formed on the first electrode formed on the substrate. In this case, the first organic electroluminescent device of the present invention may be of a top emission type that extracts light to the side opposite to the side with the substrate, or may be of a bottom emission type that extracts light to the side of the substrate.

As the material for the substrate, resin materials such as polyethylene terephthalate, polyethylene naphthalate, polypropylene, cycloolefin polymer, polyamide, polyether sulfone, polymethyl methacrylate, polycarbonate, and polyarylate, quartz glass, soda And glass materials such as glass, and one or two or more of these can be used.

In the case of the top emission type, an opaque substrate can also be used. For example, a substrate made of a ceramic material such as alumina, an oxide film (insulation film) formed on the surface of a metal substrate such as stainless steel, and a substrate made of resin material Etc. can also be used.

It is preferable that the average thickness of the substrate is 0.1 to 30 mm. More preferably, it is 0.1-10 mm.

The average thickness of the substrate can be measured with a digital multimeter or a vernier.

The first organic electroluminescent device of the present invention has a configuration in which a buffer layer is formed by applying a solution containing an organic compound, and a low molecular compound layer such as a light emitting layer is laminated thereon, whereby the organic-inorganic hybrid type of crystallization of a low molecular compound is formed. The problem peculiar to electroluminescent devices can be solved. As a method of manufacturing an organic-inorganic hybrid type organic electroluminescent device of the first preferred embodiment of the present invention, that is, an organic electroluminescent device having a structure in which a plurality of layers are stacked, the manufacturing method is an organic electric field So that the light-emitting element has a first metal oxide layer, a buffer layer, a low-molecular compound layer including a light-emitting layer stacked on the buffer layer, and a second metal oxide layer in this order between the first electrode and the second electrode. The present invention, characterized in that it includes a step of laminating each layer constituting an organic electroluminescent device, and the laminating step includes a step of forming a buffer layer having an average thickness of 3 nm or more by applying a solution containing an organic compound. Another aspect of the present invention is a method of manufacturing an organic electroluminescent device of the first preferred embodiment.

In the method for manufacturing an organic electroluminescent device of the present invention, the step of forming a buffer layer by applying a solution containing an organic compound is preferably a step of forming a buffer layer having an average thickness of 5 to 50 nm.

The method for manufacturing an organic electroluminescent device of the first preferred embodiment of the present invention may include other steps as long as it includes the steps described above, and includes first and second metal oxide layers, buffer layers, and light-emitting layers. The step of forming a layer other than the low molecular compound layer to be described may be included. In addition, the material for forming each layer of the organic electroluminescent device, the formation method, the organic compound, the solvent used to prepare a solution containing the organic compound, and the thickness of each layer are the first organic electroluminescent device of the present invention It is the same as and preferred is the same.

In the first organic electroluminescent device of the present invention, the organic compound forming the buffer layer is not particularly limited as long as it is capable of forming a layer of the organic compound by coating, but examples of the organic compound include trans polyacetylene and cis polyacetylene. , Poly(diphenylacetylene) (PDPA), poly(alkyl, phenylacetylene) (PAPA), such as polyacetylene compounds; polyparaphenylenevinylene compounds; polythiophene compounds; polyfluorene compounds; polypara A phenylene-based compound; a polycarbazole-based compound; a polysilane-based compound, a polyethyleneimine (PEI), a boron-containing compound represented by the following formula (1), or a monomer component containing a boron-containing compound represented by the following formula (2) is polymerized. Boron-containing compounds such as boron-containing polymers obtained by doing so, or boron-containing electron transport materials such as 3TPYMB:Tris(2,4,6-triMethyl-3-(pyridin-3-yl)phenyl)borane. These may use 1 type, and may use 2 or more types.

In the first organic electroluminescent device of the present invention, it is preferable that the organic compound forming the buffer layer is an organic compound having a boron atom. More preferably, the organic compound having a boron atom is a compound having a structure represented by the following formula (1), or a boron-containing polymer obtained by polymerizing a monomer component containing a boron-containing compound represented by the following formula (2).

That is, in the first organic electroluminescent device of the present invention, the organic compound having a boron atom forming the buffer layer is the following formula (1);

[Formula 1]

(In the formula, the dotted circular arc indicates that a ring structure is formed together with the skeleton portion indicated by the solid line. The dotted line portion in the skeleton portion indicated by the solid line indicates that a pair of atoms connected by a dotted line may be connected by a double bond. The arrow from the nitrogen atom to the boron atom indicates that the nitrogen atom is coordinated with the boron atom, Q ¹ and Q ² are the same or different, and are a linking group in the skeletal part represented by a solid line, at least a part of which is a dotted circular arc A ring structure is formed together with a moiety, and may have a substituent X ¹ , X ² , X ³ and X ⁴ are the same or different, and represent a hydrogen atom or a monovalent substituent that becomes a substituent of the ring structure, A plurality of rings may be bonded to the ring structure forming the circular arc portion of the dotted line. n ¹ represents an integer of 2 to 10. Y ¹ is a direct bond or n ¹ valent linking group, and a structure other than Y ^{1 having} n ¹ It shows that the ring structure which forms the circular arc part of the dotted line independently of the moiety, and bonded at any one point in Q ¹ , Q ² , X ¹ , X ² , X ³ and X ⁴ ). It is a compound, or the following formula (2);

[Formula 2]

(In the formula, the dotted circular arc indicates that a ring structure is formed together with a part of the skeletal part connecting the boron atom and the nitrogen atom. The dotted line part in the skeletal part connecting the boron atom and the nitrogen atom is at least one pair The atom of is connected by a double bond, and the double bond may be conjugated with the ring structure The arrow from the nitrogen atom to the boron atom indicates that the nitrogen atom is coordinated with the boron atom X ⁵ and X ⁶ are the same or different. And a hydrogen atom or a monovalent substituent serving as a substituent of a ring structure, and may be bonded to a plurality of ring structures forming a dotted circular arc portion R ¹ and R ² are the same or different, and a hydrogen atom or a monovalent substituent It represents a substituent At least one of X ⁵ , X ⁶ , R ¹ and R ² is a substituent having a reactive group.) It is preferably a boron-containing polymer obtained by polymerizing a monomer component containing a boron-containing compound represented by).

It is known that in the organic-inorganic hybrid electroluminescent device, hole injection from the anode occurs more efficiently than electron injection from the cathode, and the emission position is near the interface of the cathode-side oxide (corresponding to the first metal oxide in the present invention). have. In order to avoid light emission from the buffer layer in contact with the first metal oxide layer, as the organic compound forming the buffer layer, it is preferable to select a compound having a HOMO level deeper than the HOMO level of the light-emitting compound contained in the emission layer. In addition, it is more preferable to select a compound having a wider HOMO-LUMO energy gap than the HOMO-LUMO energy gap of the light-emitting compound included in the light-emitting layer in order to prevent the energy of excitons generated in the light-emitting layer from moving to the compound in the buffer layer to emit light. Do. The boron-containing polymer obtained by polymerizing the boron-containing compound represented by the above formula (1) or the monomer component containing the boron-containing compound represented by formula (2) has a very deep HOMO and a wide HOMO-LUMO energy gap, and is applied. Since it is a possible compound, it can function effectively for various types of light-emitting layers.

Further, if the organic compound having a boron atom is a compound having such a structure, the buffer layer formed from the organic compound is also excellent in function as an electron transport layer, and there is no need to form an electron transport layer separate from the buffer layer. In the following, first, a boron-containing compound represented by the above formula (1) is described, and then, a boron-containing polymer obtained by polymerization of a monomer component containing a boron-containing compound represented by the above formula (2) is described.

The boron-containing compound represented by the above formula (1) has various properties such as (i) a thermally stable compound, (ii) low energy levels of HOMO and LUMO, and (iii) it is possible to produce a good coating film. It can be used preferably as a material for the first organic electroluminescent device of the present invention.

In the above formula (1), the circular arc of the dotted line is a skeletal part represented by a solid line, that is, a part of the skeletal part connecting the boron atom and Q ¹ and the nitrogen atom or a part of the skeletal part connecting the boron atom and Q ² together with a ring It shows that a structure is formed. This is because the compound represented by the above formula (1) has at least four ring structures in the structure, and in the formula (1), a skeletal moiety connecting a boron atom and Q ¹ and a nitrogen atom and a boron atom and Q ² It shows that the skeleton part is contained as part of the ring structure. In addition, the ring structure to which X ¹ is bonded is one whose ring structure skeleton does not contain atoms other than carbon atoms and is made of carbon atoms.

In the formula (1), the skeletal part represented by a solid line, that is, a skeletal part connecting a boron atom and Q ¹ and a nitrogen atom, and a skeletal part connecting a boron atom and Q ² , and dotted line parts in each of the skeletal parts It shows that a pair of atoms connected by a dotted line in may be connected by a double bond.

In the formula (1), an arrow from a nitrogen atom to a boron atom indicates that a nitrogen atom is coordinated with a boron atom. Here, coordination means that the nitrogen atom acts on the boron atom in the same manner as the ligand and has a chemical effect, and may be a coordination bond (covalent bond), or a coordination bond may not be formed. Preferably, it is a coordination bond.

In the above formula (1), Q ¹ and Q ² are the same or different, and are linking groups in the skeletal moiety indicated by a solid line, at least a part forming a ring structure together with the dotted circular arc moiety, and having a substituent You may have it. This shows that Q ¹ and Q ² are each contained as part of the ring structure.

In the formula (1), X ¹ , X ² , X ³ and X ⁴ are the same or different, and represent a hydrogen atom or a monovalent substituent serving as a substituent of a ring structure, and a ring forming a dotted circular arc portion A plurality of structures may be combined. That is, when X ¹ , X ² , X ³ and X ⁴ are hydrogen atoms, in the structure of the compound represented by Formula (1), four ring structures having X ¹ , X ² , X ³ and X ⁴ are It represents that it does not have a substituent, and when any of X ¹ , X ² , X ³ and X ⁴ , or all of them are monovalent substituents, any or all of the four ring structures have a substituent. do. In that case, the number of substituents which one ring structure has may be one or two or more.

In addition, in this specification, a substituent means a group containing an organic group containing carbon, and a group which does not contain carbon, such as a halogen atom and a hydroxy group.

In the formula (1), n ¹ represents an integer of 2 to 10, and Y ¹ is a direct bond or an n ¹ valent linking group. That is, in the compound represented by the above formula (1), Y ¹ is a direct bond, and two structural moieties other than Y ¹ each independently form a dotted circular arc portion, Q ¹ , Q ² , X ¹ , X ² , X ³ , X ⁴ are bonded at any one point, or Y ¹ is an n ¹ valent linking group, and a plurality of structural moieties other than Y ¹ in the formula (1) are Exist, and they are bonded through the linking group Y ¹ .

In the formula (1), when Y ¹ is a direct bond, the formula (1) is a ring structure forming a dotted circular arc part of one of the structural parts other than Y ¹ , Q ¹ , Q ² , X ¹ , X ² , X ³ , A ring structure forming an arc portion of a dotted line with one point in X ⁴ and the other one, Q ¹ , Q ² , X ¹ , X ² , X ³ , It shows that any 1 point in X ⁴ is directly bonded. The bonding position is not particularly limited, but the ring to which one X ¹ of the structural moiety other than Y ¹ is bonded or the ring to which X ² is bonded, and the ring to which the other X ¹ is bonded or X ² are bonded. It is preferable that the ring being bonded is directly bonded. More preferably, the ring to which one X ² of the structural moiety other than Y ¹ is bound and the ring to which the other X ² is bound are directly bound.

In this case, the structure of the structural parts other than Y ^{1 which} exist two may be the same or different.

In the formula (1), when Y ¹ is an n ¹ valent linking group, and a plurality of structural moieties other than Y ¹ in the formula (1) are present, and they are bonded via Y ¹ as a linking group, this The structure in which structural parts other than Y ¹ in the above formula (1), which are present in a plurality, are bonded through Y ¹ which is a linking group, is more resistant to oxidation than a structure in which structural parts other than Y ¹ are directly bonded. Since manufacturability is also improved, it is more preferable.

In addition, when Y ¹ is an n ¹ valent linking group, Y ¹ is a ring structure forming an arc portion of a dotted line independently of each of the structural portions other than Y ^{1 in} which n ¹ exist, Q ¹ , Q ² , X ¹ , It is bonded at any one point in X ² , X ³ , X ⁴ , but this is a ring structure in which structural parts other than Y ¹ form a dotted arc part, Q ¹ , Q ² , X ¹ , X ² , X ^3, if the binding and Y ¹ in which the first point in the X ⁴ is, the binding site with Y ¹ of the structural parts other than Y ¹ are n independent and the structural parts each other than Y ¹ present ^one, It means that all may be the same site|part, a part may be the same site|part, and all may be different sites. Although the said bonding position is not specifically limited, It is preferable that all of the structural moieties other than Y ^{1 in} which n ¹ exists are bonded to Y ¹ by a ring to which X ¹ is bonded or a ring to which X ² is bonded. More preferably, all of the structural moieties other than Y ¹ present in n ¹ are bonded to Y ¹ by a ring to which X ² is bonded.

Moreover, the structure of the structural part other than Y ^{1 in} which n ¹ pieces exist may be all the same, some may be the same, or all may be different.

When Y ¹ in the formula (1) is an n ¹ valent linking group, the linking group is, for example, a chain, branched or cyclic hydrocarbon group which may have a substituent, or a hetero The group containing an element, the aryl group which may have a substituent, and the heterocyclic group which may have a substituent are mentioned. Among these, a group having an aromatic ring such as an aryl group which may have a substituent or a heterocyclic group which may have a substituent is preferable. That is, it is also one of the preferred embodiments of the present invention that Y ¹ in the formula (1) is a group having an aromatic ring.

In addition, Y ¹ may be a linking group having a structure in which a plurality of the linking groups described above are combined.

As the chain, branched chain or cyclic hydrocarbon group, a group represented by any of the following formulas (3-1) to (3-8) is preferable. Among these, the following formulas (3-1) and (3-7) are more preferable.

As the group containing the hetero element, a group represented by any of the following formulas (3-9) to (3-13) is preferable. Among these, the following formulas (3-12) and (3-13) are more preferable.

As the aryl group, a group represented by any of the following formulas (3-14) to (3-20) is preferable. Among these, the following formulas (3-14) and (3-20) are more preferable.

The heterocyclic group is preferably a group represented by any of the following formulas (3-21) to (3-27). Among these, the following formulas (3-23) and (3-24) are more preferable.

[Formula 3]

As the substituents of the chain, branched or cyclic hydrocarbon group, hetero element-containing group, aryl group, and heterocyclic group, halogen atom; haloalkyl group; linear or branched chain alkyl group having 1 to 20 carbon atoms ; C5-C7 cyclic alkyl group; C1-C20 linear or branched alkoxy group; Nitro group; Cyano group; C1-C10 alkyl group-containing dialkylamino group; Diphenylamino group, carbazolyl A diarylamino group such as a group; an acyl group; an alkenyl group having 2 to 30 carbon atoms; an alkynyl group having 2 to 30 carbon atoms; an aryl group which may be substituted with a halogen atom, an alkyl group, an alkoxy group, an alkenyl group, an alkynyl group, etc.; a halogen source Xana alkyl group, alkoxy group, alkenyl group, heterocyclic group which may be substituted with alkynyl group; N,N-dialkylcarbamoyl group; dioxabororanyl group, stanyl group, silyl group, ester group, formyl group, thio An ether group, an epoxy group, an isocyanate group, etc. are mentioned. In addition, these groups may be substituted with a halogen atom, a hetero element, an alkyl group, an aromatic ring, or the like.

Among these, as a substituent having a chain, branched or cyclic hydrocarbon group for Y ¹ , a group containing a hetero element, an aryl group or a heterocyclic group, a halogen atom, a linear chain having 1 to 20 carbon atoms, or A branched-chain alkyl group, a linear or branched-chain alkoxy group having 1 to 20 carbon atoms, an aryl group, a heterocyclic group, and a diarylamino group are preferable. More preferably, they are an alkyl group, an aryl group, an alkoxy group, and a diarylamino group.

When a chain, branched or cyclic hydrocarbon group, a hetero element-containing group, an aryl group, or a heterocyclic group in Y ¹ has a substituent, the position or number of the substituent bonded to each other is not particularly limited.

Although n ¹ in said formula (1) represents the integer of 2-10, Preferably, it is 2-6. More preferably, it is an integer of 2-5, More preferably, it is an integer of 2-4, Especially preferably, it is 2 or 3 from a viewpoint of solubility in a solvent. Most preferably it is 2. That is, the boron-containing compound represented by the above formula (1) is most preferably a dimer.

As Q ¹ and Q ² in the above formula (1), the following formulas (4-1) to (4-8);

[Formula 4]

The structure represented by is mentioned. In addition, the formula (4-2) is a structure in which two hydrogen atoms are bonded to a carbon atom and three additional atoms are bonded to each other, but all three atoms bonded to a carbon atom other than the hydrogen atom are all other than a hydrogen atom. It is an atom. Among the formulas (4-1) to (4-8), any of (4-1), (4-7), and (4-8) is preferable. More preferably, it is (4-1). That is, Q ¹ and Q ² are the same or different, and it is also one of the preferred embodiments of the present invention to represent a linking group having 1 carbon number.

In the formula (1), the cyclic structure formed by a part of the skeletal part represented by the dotted arc and the solid line is not particularly limited as long as the cyclic structure of the cyclic structure to which X ¹ is bonded is made of carbon atoms. Does not.

In the formula (1), when Y ¹ is a direct bond and n ¹ is 2, examples of the ring to which X ¹ is bonded include a benzene ring, a naphthalene ring, an anthracene ring, a tetracene ring, and a pentacene. Ring, triphenylene ring, pyrene ring, fluorene ring, indene ring, thiophene ring, furan ring, pyrrole ring, benzothiophene ring, benzofuran ring, indole ring, dibenzothiophene ring, dibenzofuran ring, Carbazole ring, thiazole ring, benzothiazole ring, oxazole ring, benzoxazole ring, imidazole ring, pyrazole ring, benzoimidazole ring, pyridine ring, pyrimidine ring, pyrazine ring, pyridazine ring, quinoline Rings, isoquinoline rings, quinoxaline rings, and benzothiadiazole rings.

Among these, it is preferable that the ring structure skeleton consists of only carbon atoms, and a benzene ring, a naphthalene ring, an anthracene ring, a tetracene ring, a pentacene ring, a triphenylene ring, a pyrene ring, a fluorene ring, and an indene ring are preferable. More preferably, they are a benzene ring, a naphthalene ring, and a fluorene ring, More preferably, they are a benzene ring.

In the above formula (1), when Y ¹ is a direct bond and n ¹ is 2, as a ring to which X ² is bonded, for example, represented by the following formulas (5-1) to (5-17) Rings. In addition, the * table in the following formulas (5-1) to (5-17) constitutes the ring to which X ¹ is bonded, and also connects the boron atom in the formula (1), Q ¹ and the nitrogen atom. It shows that the carbon atom constituting the skeletal part is bonded to any one of the carbon atoms to which the * mark is given. In addition, it may be condensed with another ring structure at the position where the carbon atom to which the * mark is given is removed. Among these, a pyridine ring, a pyrimidine ring, a quinoline ring, and a phenanthridine ring are preferable. More preferably, they are a pyridine ring, a pyrimidine ring, and a quinoline ring. More preferably, it is a pyridine ring.

[Formula 5]

In the formula (1), when Y ¹ is a direct bond and n ¹ is 2, as the ring to which X ³ is bonded and the ring to which X ⁴ is bonded, Y ¹ is a direct bond, n ^{When 1} is 2, the same ring as the ring to which X ¹ is bonded is exemplified. Among these, a benzene ring, a naphthalene ring, and a benzothiophene ring are preferable. More preferably, it is a benzene ring.

In the formula (1), X ¹ , X ² , X ³ and X ⁴ are the same or different, and represent a hydrogen atom or a monovalent substituent serving as a substituent of a ring structure. The monovalent substituent is not particularly limited, but examples of X ¹ , X ² , X ³ and X ⁴ include a hydrogen atom, an aryl group which may have a substituent, a heterocyclic group, an alkyl group, an alkenyl group, an alkynyl group, Alkoxy group, aryloxy group, arylalkoxy group, silyl group, hydroxy group, amino group, halogen atom, carboxyl group, thiol group, epoxy group, acyl group, oligoaryl group which may have a substituent, monovalent oligoheterocyclic group, alkyl Thi group, arylthio group, arylalkyl group, arylalkoxy group, arylalkylthio group, azo group, stanyl group, phosphino group, silyloxy group, aryloxycarbonyl group which may have a substituent, alkoxycarbonyl group which may have a substituent, substituent A carbamoyl group which may have a substituent, an arylcarbonyl group which may have a substituent, an alkylcarbonyl group which may have a substituent, an arylsulfonyl group which may have a substituent, an alkylsulfonyl group which may have a substituent, and an arylsulfinyl group which may have a substituent , Alkylsulfinyl group, formyl group, cyano group, nitro group, arylsulfonyloxy group, alkylsulfonyloxy group, which may have a substituent; alkyl sulfonate such as methanesulfonate group, ethanesulfonate group, trifluoromethanesulfonate group, etc. Nate group; Aryl sulfonate group such as benzenesulfonate group and p-toluenesulfonate group; Arylalkylsulfonate group such as benzylsulfonate group, boryl group, sulfonium methyl group, phosphonium methyl group, phosphonate methyl group, aryl A sulfonate group, an aldehyde group, an acetonitrile group, etc. are mentioned.

As the substituent in X ¹ , X ² , X ³ and X ⁴ , a halogen atom; a haloalkyl group; a linear or branched alkyl group having 1 to 20 carbon atoms; a cyclic alkyl group having 5 to 7 carbon atoms; 20 linear or branched alkoxy group; hydroxy group; thiol group; nitro group; cyano group; amino group; azo group; mono or dialkylamino group having an alkyl group having 1 to 40 carbon atoms; diphenylamino group, carbazolyl Amino groups such as groups; acyl groups; alkenyl groups having 2 to 20 carbon atoms; alkynyl groups having 2 to 20 carbon atoms; alkenyloxy groups; alkynyloxy groups; aryls such as phenoxy groups, naphthoxy groups, biphenyloxy groups, and pyrenyloxy groups Oxy group; perfluoro group and further long chain perfluoro group; boryl group; carbonyl group; carbonyloxy group; alkoxycarbonyl group; sulfinyl group; alkylsulfonyloxy group; arylsulfonyloxy group; phosphino group; silyl group Silyloxy group; Stanyl group; Phenyl group, 2,6-xylyl group, mesityl group, duryl group, biphenyl group, terphenyl group, naphthyl group, anthryl group, pyre which may be substituted with halogen atom, alkyl group, alkoxy group, etc. Aryl groups such as nil group, toluyl group, anicyl group, fluorophenyl group, diphenylaminophenyl group, dimethylaminophenyl group, diethylaminophenyl group, and phenanthrenyl group; thienyl group, furyl group, cyclopentadienyl group, oxazolyl group, Oxadiazolyl group, thiazolyl group, thiadiazolyl group, acridinyl group, quinolyl group, quinoxaroyl group, phenanthrolyl group, benzothienyl group, benzothiazolyl group, indolyl group, carbazolyl group, pyridyl group , A pyrrolyl group, a benzoxazolyl group, a pyrimidyl group, an imidazolyl group, and other heterocyclic groups; a carboxyl group; a carboxylic acid ester; an epoxy group; an isocyanate group; a cyanate group; an isocyanate group; a thiocyanate group; isothio Cyanate group; Carbamoyl group; N,N-dialkylcarbamoyl group; Formyl group; Nitroso group; Formyloxy group, etc. are mentioned. In addition, these groups may be substituted with a halogen atom, an alkyl group, an aryl group, or the like, and further, these groups may be bonded to each other at arbitrary places to form a ring.

Among these, as X ¹ , X ² , X ³ and X ⁴ , hydrogen atom; halogen atom, carboxyl group, hydroxy group, thiol group, epoxy group, amino group, azo group, acyl group, allyl group, nitro group, alkoxycarbonyl group, for Reactive groups such as wheat group, cyano group, silyl group, stanyl group, boryl group, phosphino group, silyloxy group, arylsulfonyloxy group, and alkylsulfonyloxy group; a linear or branched chain alkyl group having 1 to 20 carbon atoms; A linear or branched alkyl group having 1 to 8 carbon atoms, a linear or branched chain alkoxy group having 1 to 8 carbon atoms, an aryl group, an alkenyl group having 2 to 8 carbon atoms, an alkynyl group having 2 to 8 carbon atoms or its reactivity A linear or branched alkyl group having 1 to 20 carbon atoms substituted by a group; a linear or branched chain alkoxy group having 1 to 20 carbon atoms; a linear or branched chain alkyl group having 1 to 8 carbon atoms, 8 linear or branched alkoxy group, aryl group, C 2 to C 8 alkenyl group, C 2 to C 8 alkynyl group, or a C 1 to C 20 linear or branched alkoxy substituted with its reactive group Group; Aryl group; C 1 to C 8 linear or branched alkyl group, C 1 to C 8 linear or branched alkoxy group, aryl group, C 2 to C 8 alkenyl group, C 2 to C 8 An alkynyl group or an aryl group substituted with its reactive group; an oligoaryl group; a linear or branched alkyl group having 1 to 8 carbon atoms, a linear or branched chain alkoxy group having 1 to 8 carbon atoms, an aryl group, and 2 carbon atoms An oligoaryl group substituted with an alkenyl group of to 8, an alkynyl group of 2 to 8 or a reactive group thereof; a monovalent heterocyclic group; a linear or branched alkyl group of 1 to 8 carbon atoms, a straight chain having 1 to 8 carbon atoms A monovalent heterocyclic group substituted with a chain or branched alkoxy group, an aryl group, an alkenyl group having 2 to 8 carbon atoms, an alkynyl group having 2 to 8 carbon atoms, or a reactive group thereof; Li group; a C1-C8 linear or branched alkyl group, a C1-C8 linear or branched alkoxy group, an aryl group, a C2-C8 alkenyl group, a C2-C8 alkynyl group, or A monovalent oligoheterocyclic group substituted with the reactive group; alkylthio group; aryloxy group; arylthio group; arylalkyl group; arylalkoxy group; arylalkylthio group; alkenyl group; C1-C8 linear or branched A chain alkyl group, a linear or branched chain alkoxy group having 1 to 8 carbon atoms, an aryl group, an alkenyl group having 2 to 8 carbon atoms, an alkynyl group having 2 to 8 carbon atoms or an alkenyl group substituted with a reactive group thereof; an alkynyl group; A linear or branched alkyl group having 1 to 8 carbon atoms, a linear or branched chain alkoxy group having 1 to 8 carbon atoms, an aryl group, an alkenyl group having 2 to 8 carbon atoms, an alkynyl group having 2 to 8 carbon atoms or its reactivity An alkynyl group substituted with a group is preferred.

More preferably, hydrogen atom, bromine atom, iodine atom, amino group, boryl group, alkynyl group, alkenyl group, formyl group, silyl group, stanyl group, phosphino group, aryl group substituted with the reactive group, substituted with the reactive group Oligoaryl group, monovalent heterocyclic group or a monovalent heterocyclic group substituted with its reactive group, monovalent oligoheterocyclic group substituted with the reactive group, alkenyl group or alkenyl group substituted with its reactive group, alkynyl group or its reactivity It is an alkynyl group substituted with a group. Especially, as X ¹ and X ² , more preferably, they are a hydrogen atom, an alkyl group, an aryl group, a nitrogen-containing heteroaromatic group, an alkenyl group, an alkoxy group, an aryloxy group, a silyl group, and other functional groups resistant to reduction. Particularly preferably, they are a hydrogen atom, an aryl group, and a nitrogen-containing heteroaromatic group. Further, as X ³ and X ⁴ , more preferably a hydrogen atom, a carbazolyl group, a triphenylamino group, a thienyl group, a furanyl group, an alkyl group, an aryl group, an indolyl group, and other functional groups resistant to oxidation. Particularly preferably, they are a hydrogen atom, a carbazolyl group, a triphenylamino group, and a thienyl group. As described above, if X ¹ and X ² have a functional group resistant to reduction, and X ³ and X ⁴ have a functional group resistant to oxidation, it is considered that the boron-containing compound as a whole is further resistant to reduction and oxidation.

In addition, in the above formula (1), when X ¹ , X ² , X ³ and X ⁴ are monovalent substituents, the bonding positions or bonding positions of X ¹ , X ² , X ³ and X ^{4 to} the ring structure Is not particularly limited.

In the formula (1), when Y ¹ is an n ¹ valent linking group and n ¹ is 2 to 10, as the ring to which X ¹ is bonded, in the formula (1), Y ¹ is a direct bond, When n ¹ is 2, it is the same as the ring to which X ¹ is bonded. Among these rings, a benzene ring, a naphthalene ring, and a benzothiophene ring are preferable. More preferably, it is a benzene ring.

In the above formula (1), when Y ¹ is an n ¹ valent linking group and n ¹ is 2 to 10, the ring to which X ² is bonded, the ring to which X ³ is bonded, and X ⁴ are bonded. As a ring, in the formula (1), Y ¹ is a direct bond, and when n ¹ is 2, a ring to which X ² is bonded, a ring to which X ³ is bonded, and a ring to which X ⁴ is bonded. It is the same as the ring exemplified as, and the preferred structure is also the same.

That is, in any case where Y ¹ in the formula (1) is a direct bond, when n ¹ is 2, and when Y ¹ is an n ¹ valent linking group, and n ¹ is 2 to 10, the The boron-containing compound represented by formula (1) is the following formula (6);

[Formula 6]

(In the formula, the arrow from the nitrogen atom to the boron atom, X ¹ , X ² , X ³ , X ⁴ , n ¹ and Y ¹ are the same as those of the formula (1).) It is also a boron-containing compound represented by the present invention. It is one of the preferred embodiments.

The boron-containing compound represented by the above formula (1) can be synthesized by using various commonly used reactions such as Suzuki coupling reaction. It can also be synthesized by the method described in Journal of the American Chemical Society, 2009, Vol. 131, No. 40, and pages 14549-14559.

An example of the synthesis scheme of the boron-containing compound represented by the above formula (1) is shown in the following reaction formula. The following reaction formula (I) is a boron-containing compound represented by the above formula (1), wherein Y ¹ is a direct bond, and n ¹ is 2 .An example of a synthesis scheme is shown, and the following reaction formula (II) is represented by the above formula (1). As the shown boron-containing compound, an example of a synthesis scheme in which Y ¹ is an n ¹ valent linking group and n ¹ is 2 to 10 is shown. However, the method for producing the boron-containing compound represented by the formula (1) is not limited to this.

In the following scheme, the compound of (a) as a raw material is, for example, Journal of Organic Chemistry, 2010, Vol. 75, No. 24, pages 8709-8712. It can be synthesized by the method described in. Further, the compound of (b) serving as a raw material can be synthesized by a boronation reaction represented by the following reaction formula (III) with respect to the compound of (a).

[Formula 7]

[Formula 8]

[Formula 9]

Next, the boron-containing polymer obtained by polymerizing the monomer component containing the boron-containing compound represented by the above formula (2) is described.

In the above formula (2), the dotted circular arc indicates that a ring structure is formed together with a part of the skeleton portion connecting the boron atom and the nitrogen atom. That is, the boron-containing compound represented by the formula (2) has at least two ring structures in the structure, and in the formula (2), a skeletal moiety connecting the boron atom and the nitrogen atom is included as part of the ring structure. It shows that there is.

In the formula (2), the dotted line portion in the skeleton portion connecting the boron atom and the nitrogen atom indicates that at least one pair of atoms is connected by a double bond, and that the double bond may be conjugated with the ring structure. . Among the compounds represented by the formula (1), examples of the double bond conjugated with the cyclic structure include those having structures such as the following formulas (7-1) to (7-4).

[Formula 10]

In the formula (2), an arrow from a nitrogen atom to a boron atom indicates that a nitrogen atom is coordinated with a boron atom. Coordination has the same meaning as the coordination of the nitrogen atom to the boron atom in the formula (1).

In the above formula (2), X ⁵ and X ⁶ are the same or different, and represent a hydrogen atom or a monovalent substituent serving as a substituent of the ring structure, and may be bonded to a plurality of ring structures forming the circular arc portion of the dotted line. . That is, when X ⁵ and X ⁶ are hydrogen atoms, in the structure of the boron-containing compound represented by formula (2), two ring structures having X ⁵ and X ⁶ represent that they do not have a substituent, and X ⁵ and/ Or when X ⁶ is a monovalent substituent, either or both of the two ring structures has a substituent. In that case, the number of substituents which one ring structure has may be one or two or more.

In the above formula (2), R ¹ and R ² are the same or different, and represent a hydrogen atom or a monovalent substituent. The R ¹ and R ² may be the same or different, but the same is preferable. The R ¹ and R ² are not particularly limited, but for example, a hydrogen atom, an aryl group which may have a substituent, a heterocyclic group, an alkyl group, an alkoxy group, an arylalkoxy group, a silyl group, a hydroxy group, a boryl oxide Group, amino group, halogen atom, 2,2'-biphenyl group formed by bonding of R ¹ and R ² , oligoaryl group which may have a substituent, monovalent oligoheterocyclic group, alkylthio group, arylthio group, arylalkyl group , Arylalkoxy group, arylalkylthio group, azo group, stanyl group, phosphino group, silyloxy group, arylsulfonyloxy group, alkylsulfonyloxy group; alkylsulfonate group; arylsulfonate group; arylalkylsulfonate group; Boryl groups, such as a group represented by formula (8-1)-(8-4); Sulfonium methyl groups, such as a group represented by following formula (8-5)-(8-6); With following formula (8-7) Phosphonium methyl groups, such as a group represented; Phosphonate methyl groups, such as a group represented by following formula (8-8); Arylsulfonate group; Aldehyde group; Acetonitrile group; Magnesium halide represented by following formula (8-9), etc. are mentioned. I can.

In addition, in the formula, Me represents a methyl group. Et represents an ethyl group. X represents a halogen atom. R'represents an alkyl group, an aryl group, or an arylalkyl group.

[Formula 11]

Examples of the aryl group include a phenyl group, a biphenyl group, a naphthyl group, a tetrahydronaphthyl group, an indenyl group, and an indanyl group. Among these, a phenyl group, a biphenyl group, and a naphthyl group are preferable.

Examples of the heterocyclic group include a pyrrolyl group, a pyridyl group, a quinolyl group, a piperidinyl group, a pipezino group, a furyl group, and a thienyl group. Among these, a pyridyl group and a thienyl group are preferable.

Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Among these, a bromine atom and an iodine atom are preferable.

Examples of the alkyl group include a linear or branched hydrocarbon group having 1 to 30 carbon atoms and an alicyclic hydrocarbon group having 3 to 30 carbon atoms. That is, in the first organic electroluminescent device of the present invention, the buffer layer is formed from a boron-containing polymer obtained by polymerizing a monomer component containing a boron-containing compound represented by formula (2), and contains boron represented by formula (2). It is also one of the preferred embodiments of the present invention that R ¹ and R ² in the compound are the same or different and are a linear or branched hydrocarbon group having 1 to 30 carbon atoms, or an alicyclic hydrocarbon group having 3 to 30 carbon atoms. .

As the alkyl group, among these, a methyl group, an ethyl group, an isopropyl group, an isobutyl group, and an octyl group are preferable. More preferably, they are a methyl group, an ethyl group, an isobutyl group, and an octyl group.

Examples of the substituents for R ¹ and R ² include the same substituents as those for X ¹ to X ⁴ in the formula (1).

Among these, examples of the substituents which the monovalent substituents for R ¹ and R ² have include halogen atoms, linear or branched alkyl groups having 1 to 4 carbon atoms, linear or branched chain alkoxy having 1 to 8 carbon atoms. A group, an aryl group, and a haloalkyl group are preferable. More preferably, they are ethyl group, isopropyl group, octyl group, fluorine atom, bromine atom, vinyl group, ethynyl group, diphenylamino group, diphenylaminophenyl group, and trifluoromethyl group.

As the R ¹ and R ² , among those described above, a hydrogen atom, a bromine atom, a methyl group, an ethyl group, an isopropyl group, an isobutyl group, an n-octyl group, a phenyl group, a 4-methoxyphenyl group, and a 4-trifluoro Methylphenyl group, pentafluorophenyl group, 4-bromophenyl group, 2,2'-biphenyl group, styryl group, and diphenylaminophenyl group are more preferable. More preferably, bromine atom, methyl group, ethyl group, isopropyl group, isobutyl group, n-octyl group, phenyl group, 4-methoxyphenyl group, 4-trifluoromethylphenyl group, pentafluorophenyl group, 4-bromo Phenyl group, 2,2'-biphenyl group, styryl group, diphenylaminophenyl group, particularly preferably bromine atom, isopropyl group, isobutyl group, n-octyl group, phenyl group, 4-trifluoromethylphenyl group, They are pentafluorophenyl group, 4-bromophenyl group, 2,2'-biphenyl group, styryl group, and diphenylaminophenyl group.

In the formula (2), X ⁵ and X ⁶ are the same or different, and represent a hydrogen atom or a monovalent substituent serving as a substituent of a ring structure. Although it does not specifically limit as this monovalent substituent, The thing similar to the said R<^1> and R<^{2> is} mentioned.

Among these, X ⁵ and X ^{6 are} hydrogen atoms; halogen atoms, carboxyl groups, hydroxyl groups, thiol groups, epoxy groups, isocyanate groups, amino groups, azo groups, acyl groups, allyl groups, nitro groups, alkoxycarbonyl groups, formyl groups, and cyanide groups. Reactive groups such as no group, silyl group, stanyl group, boryl group, phosphino group, silyloxy group, arylsulfonyloxy group, and alkylsulfonyloxy group; a linear or branched alkyl group having 1 to 4 carbon atoms or a reactive group thereof A substituted linear or branched alkyl group having 1 to 4 carbon atoms; a linear or branched chain alkoxy group having 1 to 8 carbon atoms or a linear or branched alkoxy group having 1 to 8 carbon atoms substituted with its reactive group An aryl group or an aryl group substituted with its reactive group; an oligoaryl group or an oligoaryl group substituted with its reactive group; a monovalent heterocyclic group or a monovalent heterocyclic group substituted with its reactive group; a monovalent oligo-heterocyclic group or its Monovalent oligoheterocyclic group substituted with a reactive group; alkylthio group; aryloxy group; arylthio group; arylalkyl group; arylalkoxy group; arylalkylthio group; alkenyl group or alkenyl group substituted with its reactive group; alkynyl group or its An alkynyl group substituted with a reactive group is preferred. More preferably, a hydrogen atom, a bromine atom, an iodine atom, a boryl group, an alkynyl group, an alkenyl group, a formyl group, a stanyl group, a phosphino group, an aryl group or an aryl group substituted with its reactive group, an oligo substituted with the reactive group Amino groups such as aryl groups and diphenylamino groups, monovalent heterocyclic groups such as groups represented by the following formula (8-10), monovalent heterocyclic groups substituted with their reactive groups, monovalent oligoheterocyclic groups substituted with their reactive groups , An alkenyl group or an alkenyl group substituted with its reactive group, an alkynyl group, or an alkynyl group substituted with its reactive group.

[Formula 12]

At least one of X ⁵ , X ⁶ , R ¹ and R ² in the formula (2) is a substituent having a reactive group. As a substituent having a reactive group, halogen atom, carboxyl group, hydroxyl group, thiol group, epoxy group, isocyanate group, amino group, azo group, acyl group, allyl group, nitro group, alkoxycarbonyl group, formyl group, cyano group, silyl group, stanyl group , A reactive group such as a boryl group, a phosphino group, a silyloxy group, an arylsulfonyloxy group, or an alkylsulfonyloxy group; a linear or branched alkyl group having 1 to 4 carbon atoms substituted with the reactive group; A linear or branched alkoxy group having 1 to 8 carbon atoms; aryl group substituted with the reactive group; oligoaryl group substituted with the reactive group; monovalent heterocyclic group substituted with the reactive group; monovalent substituted with the reactive group An oligo-heterocyclic group; an alkenyl group or an alkenyl group substituted with its reactive group; an alkynyl group or an alkynyl group substituted with its reactive group is preferable. More preferably, bromine atom, iodine atom, boryl group, formyl group, stanyl group, phosphino group, aryl group substituted with the reactive group, oligoaryl group substituted with the reactive group, monovalent heterocyclic ring substituted with the reactive group A group, a monovalent oligo-heterocyclic group substituted with the reactive group, an alkenyl group, or an alkenyl group substituted with the reactive group, an alkynyl group, or an alkynyl group substituted with the reactive group. More preferably, a bromine atom, a boryl group, a formyl group, a stanyl group, a phosphino group, an aryl group substituted with the reactive group, an oligoaryl group substituted with the reactive group, a monovalent heterocyclic group substituted with the reactive group, and It is a monovalent oligo-heterocyclic group substituted with a reactive group, an alkenyl group, or an alkenyl group substituted with a reactive group, an alkynyl group, or an alkynyl group substituted with the reactive group.

In the case where two of X ⁵ , X ⁶ , R ¹ and R ² are substituents having a reactive group, the reactive groups of these two substituents are different, and a reactive group capable of polycondensation of one boron-containing compound alone A combination of, or containing two or more boron-containing compounds represented by formula (2), and having a combination of reactive groups capable of copolymerizing these boron-containing compounds, or represented by formula (2) The boron-containing compound can be preferably used as a raw material for a polymer by making it a combination of a reactive group capable of copolymerizing one or two or more types of boron-containing compounds and another compound having at least one reactive group.

As the ring to which X ⁵ is bonded in the formula (2), for example, a benzene ring, a thiophene ring, a benzothiophene ring, a thiazole ring, an oxazole ring, a naphthalene ring, an anthracene ring, a tetracene ring, A pentacene ring, an imidazole ring, a pyrazole ring, a pyridine ring, a pyridazine ring, a pyrazine ring, a pyrimidine ring, a quinoline ring, and an isoquinoline ring, each of the following formulas (9-1) to (9- 17). Among these, a benzene ring, a naphthalene ring, and a benzothiophene ring are preferable.

[Formula 13]

In addition, as the ring to which X ⁶ is bonded in the formula (2), for example, a pyrrole ring, a pyrazole ring, an imidazole ring, a pyridine ring, a pyridazine ring, a pyrazine ring, a pyrimidine ring, an indole ring, Isoindole ring, quinoline ring, isoquinoline ring, phenanthridine ring, thiazole ring, and oxazole ring. These are each represented by the following formulas (10-1) to (10-14). Among these, a pyridine ring, a pyrimidine ring, a quinoline ring, and a phenanthridine ring are preferable. More preferably, they are a pyridine ring, a pyrimidine ring, and a quinoline ring.

[Formula 14]

In the boron-containing compound represented by the above formula (2), when X ⁵ and/or X ⁶ is a monovalent substituent, the bonding position of X ⁵ and/or X ⁶ with respect to the ring structure and the number of bonds are not particularly limited. .

In addition, as X ⁵ , at least two monovalent substituents are bonded to the ring structure, one of the monovalent substituents is a boryl group which may have a substituent, and the other one of the monovalent substituents is a pyridyl group which may have a substituent. As an example, the form in which the nitrogen atom of the pyridyl group is coordinated with the boron atom of the boryl group is also one of the preferred embodiments of the present invention. That is, it is also one of the preferred embodiments of the present invention that the boron-containing compound represented by the above formula (2) has two or more portions in the structure in which the nitrogen atom is coordinated with the boron atom.

In the present invention, in the above formula (2), at least one of X ⁵ and X ⁶ has a structure in which two atoms are connected to a terminal portion by a double bond, and one of the two atoms forms a dotted arc portion. Another preferred embodiment of the present invention is that it is a substituent having a structure bonded to a ring structure. That is, the organic compound having a boron atom forming the buffer layer of the organic electroluminescent device is a boron-containing polymer, and the boron-containing compound included in the monomer component used as the raw material of the boron-containing polymer is a boron-containing compound having a boron atom and a double bond. As, the boron-containing compound is the following formula (2);

[Formula 15]

(In the formula, the dotted circular arc indicates that a ring structure is formed together with a part of the skeletal part connecting the boron atom and the nitrogen atom. The dotted line part in the skeletal part connecting the boron atom and the nitrogen atom is at least one pair The atom of is connected by a double bond, and the double bond may be conjugated with the ring structure The arrow from the nitrogen atom to the boron atom indicates that the nitrogen atom is coordinated with the boron atom X ⁵ and X ⁶ are the same or different. And a hydrogen atom or a monovalent substituent serving as a substituent of a ring structure, and may be bonded to a plurality of ring structures forming a dotted circular arc portion R ¹ and R ² are the same or different, and a hydrogen atom or a monovalent substituent A substituent.), and at least one of X ⁵ and X ⁶ has a structure in which two atoms are connected at the terminal portion by a double bond, and a ring structure forming a dotted circular arc portion at one atom of the two atoms and Another preferred embodiment of the present invention is that it is a boron-containing compound characterized by having a bonded structure.

A structure in which two atoms are connected to the terminal portion by a double bond, and a structure in which one of the two atoms is combined with a ring structure forming a dotted arc portion, that is, an atomic group constituting X ⁵ and/or X ⁶ In the case, there are at least two end portions of each structure, but of the end portions, the end portion that is bonded to the ring structure forming the dotted arc portion in the formula (2) is combined with the ring structure forming the dotted arc portion. It means that the atom and the atom next to the atom have a structure connected by a double bond. Examples of such a substituent include structures represented by the following formulas (11-1) to (11-2).

In addition, in formulas (11-1) to (11-2), * represents an atom bonded to a ring structure forming a dotted circular arc portion in formula (2). r ¹ , r ² , r ³ and r ⁴ are the same or different, and between r ¹ and r ² , and between r ³ and r ⁴ , each represents an atom capable of forming a double bond. Equation (11-1) of, q ¹ shows that, even if the plurality of binding to r ² in accordance with the valence of the monovalent organic hydrogen atom or a monovalent, r ^2. In formula (11-2), the circular arc of the dotted line indicates that a ring structure is formed together with the double bond moiety formed by r ³ and r ⁴ . q ² represents a hydrogen atom or a monovalent substituent serving as a substituent of a ring structure, and indicates that a plurality of ring structures may be bonded to the ring structure forming the dotted circular arc portion in the formula (11-2).

[Formula 16]

In the formulas (11-1) to (11-2), r ¹ , r ² , r ³ and r ⁴ are the same or different, and between r ¹ and r ² , and between r ³ and r ⁴ In each, an atom capable of forming a double bond is shown, but it is preferably a carbon atom, a nitrogen atom, a phosphorus atom, and a sulfur atom. More preferably, they are a carbon atom and a nitrogen atom.

In the formula (11-1), q ^1, but illustrate that the even and plurality of binding to r ² in accordance with the valence of the monovalent organic hydrogen atom or a monovalent, r ^2, which, for example, r ² is If the nitrogen atoms, q is ¹ in the case of being the one coupled to the r ^2, r ² is the carbon atom, q is ¹ indicates that the two binding to r ^2. When a plurality of q ¹ is bonded to r ² , all of q ¹ may be the same or different. It does not specifically limit as said monovalent organic group, The thing similar to R<^1> and R<^2> in said Formula (2) is mentioned.

Among these, q ^{1 is a} hydrogen atom; halogen atom, carboxyl group, hydroxyl group, thiol group, epoxy group, isocyanate group, amino group, azo group, acyl group, allyl group, nitro group, alkoxycarbonyl group, formyl group, cyano group, silyl Reactive groups such as groups, stanyl groups, boryl groups, phosphino groups, silyloxy groups, arylsulfonyloxy groups, alkylsulfonyloxy groups, etc.; a linear or branched chain alkyl group having 1 to 4 carbon atoms, or a carbon number substituted with the reactive group 1 to 4 linear or branched alkyl group; a C 1 to C 8 linear or branched alkoxy group or a C 1 to C 8 linear or branched alkoxy group substituted with the reactive group; aryl group Or an aryl group substituted with its reactive group; an oligoaryl group or an oligoaryl group substituted with its reactive group; a monovalent heterocyclic group or a monovalent heterocyclic group substituted with its reactive group; a monovalent oligo-heterocyclic group or substituted with its reactive group Monovalent oligoheterocyclic group; alkylthio group; aryloxy group; arylthio group; arylalkyl group; arylalkoxy group; arylalkylthio group; alkenyl group or an alkenyl group substituted with its reactive group; substituted with an alkynyl group or its reactive group The resulting alkynyl group is preferred. More preferably, a hydrogen atom, a bromine atom, an iodine atom, a boryl group, an alkynyl group, an alkenyl group, a formyl group, a stanyl group, a phosphino group, an aryl group or an aryl group substituted with its reactive group, an oligo substituted with the reactive group An aryl group, a monovalent heterocyclic group substituted with its reactive group, a monovalent oligo heterocyclic group substituted with the reactive group, an alkenyl group or an alkenyl group substituted with its reactive group, an alkynyl group, or an alkynyl group substituted with its reactive group.

In the above formula (11-2), q ² represents a hydrogen atom or a monovalent substituent serving as a substituent of a ring structure, and a plurality of bonds to the ring structure forming a dotted circular arc portion in the formula (11-2) It shows that you may do it.

That is, in the case of when q ² is a hydrogen atom, the ring structure having a, q ² of the structure shown by the formula (11-2) shows that that do not have a substituent, and q ² is a monovalent substituent, the ring structure is It becomes what has a substituent. In that case, the number of substituents that the ring structure has may be one or two or more.

Examples of the monovalent substituent include those similar to X ⁵ and X ⁶ in the above formula (2), but among these, a group represented by the above formula (8-10), a naphthyl group, and a phenyl group are particularly preferable.

In the present invention, furthermore, both of X ⁵ and X ⁶ in the above formula (2) have a structure in which two atoms are connected to the terminal portion by a double bond, and one of the two atoms forms a dotted arc portion. Another preferred embodiment of the present invention is that it is a substituent having a structure bonded to a ring structure. That is, the organic compound having a boron atom forming the buffer layer of the organic electroluminescent device is a boron-containing polymer, and the boron-containing compound included in the monomer component that is a raw material of the boron-containing polymer is a boron-containing compound having a boron atom and a double bond. As, the boron-containing compound is the following formula (2);

[Formula 17]

(In the formula, the dotted circular arc indicates that a ring structure is formed together with a part of the skeletal part connecting the boron atom and the nitrogen atom. The dotted line part in the skeletal part connecting the boron atom and the nitrogen atom is at least one pair The atom of is connected by a double bond, and the double bond may be conjugated with the ring structure The arrow from the nitrogen atom to the boron atom indicates that the nitrogen atom is coordinated with the boron atom X ⁵ and X ⁶ are the same or different. And a monovalent substituent which becomes a substituent of the ring structure, and may be bonded to a plurality of ring structures forming the circular arc portion of the dotted line. R ¹ and R ² are the same or different, and represent a hydrogen atom or a monovalent substituent. .), and both of X ⁵ and X ⁶ have a structure in which two atoms are connected by a double bond at the terminal portion, and one of the two atoms has a structure bonded to a ring structure forming a dotted arc portion. It is also one of preferred embodiments of the present invention that it is a characterized boron-containing compound.

In the above formula (2), both of X ⁵ and X ⁶ have a structure in which two atoms are connected to the terminal portion by a double bond, and one of the two atoms has a structure bonded to a ring structure forming a dotted arc portion. As the boron-containing compound, largely, a ring structure forming a dotted circular arc portion in the formula (2) and a form in which the double bond portion constituted by an atom bonded to each other does not constitute a ring structure, and a portion of the ring structure The form constituting the is mentioned, and specifically, the form of following formula (2'-1)-(2'-4) is mentioned.

In addition, in formulas (2'-1) to (2'-4), a dotted line portion in a skeleton portion connecting a boron atom and a nitrogen atom, an arrow from a nitrogen atom to a boron atom, and R ¹ and R ² are It is the same as Equation (1). In Equation (2'-1), the circular arc of the dotted line is the same as Equation (2). In formulas (2′- 2) ∼ (2′- 4), the circular arc of the dotted line in contact with a part of the skeleton connecting the boron atom and the nitrogen atom is the skeleton connecting the boron atom and the nitrogen atom as in equation (2). It indicates that a ring structure is formed with a part of the portion, and the circular arc of the dotted line in contact with the double bond portion formed by r ⁵ and r ⁶ and/or the double bond portion formed by r ⁷ and r ⁸ corresponds to the corresponding It indicates that a ring structure is formed with the double bond moiety. r ⁵ to r ⁸ are the same or different, and are the same as r ¹ to r ^{4 in} the formulas (11-1) to (11-2). q ³ and q ⁴ are the same or different, and are the same as q ¹ in the formula (11-1). q ⁵ and q ⁶ are the same or different, and they are the same as q ² in the formula (11-2). However, when the boron-containing compound is of the form of formula (2'-4), at least one of q ⁵ and q ⁶ is a substituent having a reactive group.

[Formula 18]

Among these forms, both the ring structure forming the circular arc portion of the dotted line in the formula (2) and the double bond portion composed of the atoms bonded to each other do not form a ring structure, or a part of the ring structure. It is preferable that it is any one of the form of constituting. That is, it is preferably in the form of the above formulas (2'-1) and (2'-4).

Such an organic compound having a boron atom forming a buffer layer of an organic electroluminescent device includes a boron-containing compound represented by the above formula (2′-1) or a boron-containing compound represented by the above formula (2′-4) It is also one of the preferred embodiments of the present invention that it is a boron-containing polymer obtained by polymerizing the monomer component described above.

In the above formula (2′-1), the dotted circular arc indicates that a ring structure is formed together with a part of the skeletal moiety connecting the boron atom and the nitrogen atom, as in the formula (1). In 2′-1), the ring structure formed by the dotted circular arc and a part of the skeleton portion connecting the boron atom and the nitrogen atom is not particularly limited as long as it is a cyclic structure, and in the formula (2′-1) Examples of the ring to which the group having q ³ is bonded include the same ring as the ring to which X ⁵ is bonded in the formula (2). Moreover, as the ring to which the group which has q ⁴ in formula (2'-1) is bonded, the same thing as the ring to which X ⁶ in formula (2) is bonded is mentioned.

In the above formulas (2′- 2) to (2′- 4), the dotted circular arc in contact with a part of the skeletal portion connecting the boron atom and the nitrogen atom is a boron atom and a nitrogen atom, as in formula (2). It indicates that a ring structure is formed together with a part of the skeletal part connecting to, and the double bond part formed by r ⁵ and r ⁶ and/or the dotted line in contact with the double bond part formed by r ⁷ and r ⁸ The circular arc indicates that a ring structure is formed with the corresponding double bond moiety. That is, the boron-containing compound represented by the above formulas (2′- 2) to (2′- 3) has at least 3 ring structures in the structure, a skeletal moiety connecting a boron atom and a nitrogen atom, and one double bond It shows that a moiety is included as part of the ring structure. In addition, the boron-containing compound represented by the above formula (2′-4) has at least 4 ring structures in the structure, and the skeletal moiety connecting the boron atom and the nitrogen atom, and two double bond moieties are part of the ring structure It shows what is included as.

In the above formulas (2'-2) to (2'-4), a dotted arc in contact with a portion of the skeleton portion connecting the boron atom and the nitrogen atom, and a portion of the skeleton portion connecting the boron atom and the nitrogen atom The ring structure formed by is not particularly limited as long as it is a cyclic structure, but as a ring to which a group including a double bond moiety formed by r ⁵ and r ⁶ is bonded, X ⁵ in formula (2) is bonded. The same thing as the ring can be mentioned. Moreover, as the ring to which the group containing the double bond moiety formed by r ⁷ and r ⁸ is bonded, the same ring as the ring to which X ⁶ in formula (2) is bonded can be mentioned.

In addition, in the above formulas (2′- 2) to (2′- 4), the dotted line in contact with the double bond portion formed by r ⁵ and r ⁶ and/or the double bond portion formed by r ⁷ and r ⁸ As a ring structure formed by an arc and a corresponding double bond moiety, for example, a ring to which X ⁵ in formula (2) is bonded, and a ring in which X ⁶ in formula (2) is bonded. The same thing as the ring can be mentioned. In addition, in the above formula (2'-4), the double bond portion formed by r ⁵ and r ⁶ and the circular arc of the dotted line in contact with the double bond portion formed by r ⁷ and r ⁸ , and the double bond portion At least two ring structures to be formed exist, but they may be the same or different.

The method for producing the boron-containing compound represented by the above formula (2) is not particularly limited, but it can be produced, for example, by the method described in JP2011-184430A.

The boron-containing polymer obtained by polymerizing a monomer component containing a boron-containing compound represented by the above formula (2) is polycondensed with at least two groups of X ⁵ , X ⁶ , R ¹ and R ² in formula (2), or, It has a repeating unit formed by polymerization of at least one group. That is, the following formula (12);

[Formula 19]

(In the formula, the circular arc of the dotted line, the dotted line portion in the skeleton portion connecting the boron atom and the nitrogen atom, and the arrow from the nitrogen atom to the boron atom are the same as those of the formula (2). X ^5' , X ^6' , R ^{1 ′} And R ^{2 ′} each represent the same group as X ⁵ , X ⁶ , R ¹ and R ^{2 in the} formula (2), a divalent group, a trivalent group, or a direct bond.) It is a boron-containing polymer having. The above equation (12), means of ^{X 5 ', X 6',} R 1 ' and R ^2', which at least one is formed as a coupling part of the main chain of the polymer. When at least two groups of X ⁵ , X ⁶ , R ¹ and R ² in the formula (2) are polycondensed to form a boron-containing polymer, X ^{5 ′} , X ^{6 ′} and R ^{1 ′ in} the formula (12) and R ^{2 ',} at least two are a divalent group, or of a direct bond. When at least one group of X ⁵ , X ⁶ , R ¹ and R ² in the formula (2) is independently polymerized to form a boron-containing polymer, X ^{5 ′} , X ^{6 ′} and R in the formula (12) ^{1 'and} R ^2', at least one is the trivalent group, or of a direct bond.

The boron-containing polymer having a repeating unit represented by the above formula (12) may consist of one type of structure represented by the above formula (12), or may contain two or more types of structures represented by the above formula (12). When it contains two or more types of structures represented by the above formula (12), the two or more types of structures may be a random polymer, a block polymer, or a graft polymer. In addition, a dendrimer may be used or a case where there is a branch in the polymer main chain and has three or more terminal portions.

Among the boron-containing polymers having the structure of the repeating unit represented by the formula (12), it is preferable that R ^{1 ′} and R ^{2 ′} in the formula (12) are the same groups as R ¹ and R ² in the formula (2), respectively. Further, it is more preferable that R ^{1 ′} and R ^{2 ′} in the above formula (12) are a C 1 to C 30 linear or branched hydrocarbon group or a C 3 to C 30 alicyclic hydrocarbon group.

That is, as a boron-containing polymer obtained by polymerizing a monomer component containing a boron-containing compound represented by the formula (2) wherein the organic compound having a boron atom forming the buffer layer of the organic electroluminescent device, R ¹ in formula (2) And R ² are the same or different, and a C 1 to C 30 linear or branched hydrocarbon group or a C 3 to C 30 alicyclic hydrocarbon group is another preferred embodiment of the present invention.

Among specific examples of the structure of the repeating unit represented by the above formula (12), as a structure obtained by polycondensation, there are structures such as the following formulas (13-1) to (13-6). Among these, it is preferable that it is the structure of (13-1) and (13-6). More preferably, it is the structure of (13-1). That is, a boron-containing polymer obtained from a boron-containing compound having a structure represented by the formula (2) and which is a substituent having a reactive group in which X ⁵ and X ⁶ in the formula (2) is also one of the present invention.

[Chemical Formula 20-1]

[Chemical Formula 20-2]

[Chemical Formula 20-3]

The combination of the reactive group capable of polycondensation is not particularly limited as long as it can be polymerized, but for example, a carboxyl group and a hydroxy group, a carboxyl group and a thiol group, a carboxyl group and an amino group, a carboxylic acid ester and an amino group, a carboxyl group and an epoxy group , Hydroxy group and epoxy group, thiol group and epoxy group, amino group and epoxy group, isocyanate group and hydroxy group, isocyanate group and thiol group, isocyanate group and amino group, hydroxy group and halogen atom, thiol group and halogen atom, boryl group and halogen atom, stanyl group and halogen atom , Aldehyde group and phosphonium methyl group, vinyl group and halogen atom, aldehyde group and phosphonate methyl group, haloalkyl group and haloalkyl group, sulfonium methyl group and sulfonium methyl group, aldehyde group and acetonitrile group, aldehyde group and aldehyde group, halogen atom and boryl group, halogen Atom and magnesium halide, halogen atom and halogen atom, and the like.

Among these, a combination of a halogen atom and a boryl group, and a combination of a halogen atom and a halogen atom are preferable.

When at least two groups of X ⁵ , X ⁶ , R ¹ and R ² in the formula (2) are polycondensed to form a boron-containing polymer, X ^{5 ′} , X ^{6 ′} and R ^{1 in} the formula (12) At least two of ^′ and R ^{2 ′} represent a divalent group or a direct bond, but the divalent group represents a residue that is not desorbed by the polycondensation reaction of the substitution period having a reactive group. When a substituent having a reactive group that is a combination of polycondensable reactive groups undergoes a polycondensation reaction, a residue may or may not remain in the polymer, and in the former case, X ^5′ , X ^6′ , At least one of R ^1′ and R ^2′ represents a residue that is not desorbed by the polycondensation reaction of the substitution period having a reactive group, and in the latter case, among X ^5′ , X ^6′ , R ^1′ and R ^2′ At least one represents a direct bond.

In the case where the amount of the repeating unit represented by the formula (12) continuing at least two, between the two repeating units, for example, -X ^{5 '-X 6'} - and the like, X ^{5 ',} X ^6' , R ^{1 ′} and R ^{2 ′} , two of which are continuous bonds are formed, but in this case, either one of the two is a direct bond.

Specific examples of the case where the substituent having a reactive group, which is a combination of the reactive groups capable of polycondensation, remains in the polymer due to a polycondensation reaction, a combination of a substituent having a carboxyl group and a substituent having a hydroxy group. For example, when a -CH ₂ COOH group and a -CH ₂ CH ₂ OH group undergo a polycondensation reaction, a residue remaining in the polymer becomes a -CH ₂ (CO)-O-CH ₂ CH ₂ -group. Further, for example, when a substituent having a reactive group is composed of only a reactive group, such as a reaction between a -COOH group and a -OH group, the residue remaining in the polymer becomes a -(CO)-O- group.

Further, specific examples of the case where the combination of the reactive groups capable of polycondensation is polycondensed and no residue remains in the polymer include a boryl group, a halogen atom, and a combination of a halogen atom and a halogen atom.

Among the specific examples of the structure of the repeating unit represented by the formula (12), as a structure obtained by polymerization of at least one group of X ⁵ , X ⁶ , R ¹ and R ² in the formula (2) alone, for example, The structure obtained by polymerization of X ⁶ is as shown in the following formula (14). Thus, equation (2) when the substituent having a reactive group capable of homopolymerization during the structure of X ^6, X ^{6 'is} the repeating unit of a trivalent group or a direct bond structure. Similarly, when any of X ⁵ , X ⁶ , R ^1, or R ² in formula (2) is a substituent having a reactive group capable of polymerization alone in the structure, X ^5′ , X ^6′ , R ^1′ , the R ^{2 'is} the repeating unit of a trivalent group or a direct bond structure.

[Formula 21]

Examples of the independently polymerizable reactive group include 3,5-dibromophenyl group, alkenyl group, alkynyl group, epoxy group, and halogen atom. When the boron-containing compound of the formula (2) has at least one of these groups, the boron-containing compound of the formula (2) can be independently polymerized. Among these, an alkenyl group, an epoxy group, and a 3,5-dibromophenyl group are preferable.

In X ⁵ , X ⁶ , R ¹ and R ² in the above formula (2), the group to be polycondensed may be a substituent having a reactive group capable of polycondensation in the structure. Similarly, the group to be homopolymerized may be a substituent having the above-described independently polymerizable reactive group in the structure. As such a substituent, any group such as a linear or branched alkyl group having 1 to 4 carbon atoms, a cyclic alkyl group having 3 to 7 carbon atoms, a linear or branched alkoxy group having 1 to 8 carbon atoms, an aryl group or a heterocyclic group And a group in which the hydrogen atom of is substituted with a reactive group capable of polycondensation or a reactive group capable of polymerization alone. Among these, a styryl group and a 3,5-dibromophenyl group are preferable.

Other monomers may be contained in the monomer component as long as the boron-containing polymer of the present invention is obtained from a monomer component containing a boron-containing compound represented by the above formula (2).

That is, the boron-containing compound represented by formula (2) and the following formula (15);

[Formula 22]

(In the formula, A represents a divalent group. X ⁷ and X ⁸ are the same or different, represent a hydrogen atom or a monovalent substituent, and at least one of X ⁷ and X ⁸ is a substituent having a reactive group.) The boron-containing polymer formed by polymerizing other monomers is also included in the boron-containing polymer in the present invention.

A in the formula (15) is not particularly limited as long as it is a divalent group, but examples of the name of the compound corresponding to the structure include benzene, naphthalene, anthracene, phenanthrene, chrysene, rubrene, pyrene, Perylene, indene, azulene, adamantane, fluorene, fluorenone, dibenzofuran, carbazole, dibenzothiophene, furan, pyrrole, pyrroline, pyrrolidine, thiophene, dioxolane, pyrazole , Pyrazoline, pyrazolidine, imidazole, oxazole, thiazole, oxadiazole, triazole, thiadiazole, pyran, pyridine, piperidine, dioxane, morpholine, pyridazine, pyrimidine, pyrazine, Piperazine, triazine, tritian, norbornene, benzofuran, indole, benzothiophene, benzimidazole, benzoxazole, benzothiazole, benzothiadiazole, benzoxadiazole, purine, quinoline, isoquinoline , Coumarin, cinnoline, quinoxaline, acridine, phenanthroline, phenothiazine, flavone, triphenylamine, acetylacetone, dibenzoylmethane, picolinic acid, silol, porphyrin, metal coordination compounds such as iridium, or , Derivatives in which they have a substituent, polymers or oligomers including the structure of these derivatives.

Further, as the substituent, the same substituents for R ¹ and R ² can be used.

As said A, in addition to the thing mentioned above, the structure of following formula (16-1)-(16-4) is mentioned, for example.

[Formula 23]

(In the formula, Ar1, Ar2, Ar3 are the same or different, and represent an arylene group, a divalent heterocyclic group, or a divalent group having a metal complex structure. Z1 is -C≡C-, -N(Q3)-,- (SiQ4Q5)b-, or represents a direct bond, Z2 represents -CQ1=CQ2-, -C≡C-, -N(Q3)-, -(SiQ4Q5)b-, or a direct bond, Q1 and Q2 is the same or different, and represents a hydrogen atom, an alkyl group, an aryl group, a monovalent heterocyclic group, a carboxyl group, an alkyloxycarbonyl group, an aryloxycarbonyl group, an arylalkyloxycarbonyl group, a heteroaryloxycarbonyl group, or a cyano group. Q4 and Q5 are the same or different, and represent a hydrogen atom, an alkyl group, an aryl group, a monovalent heterocyclic group, or an arylalkyl group, a represents an integer of 0 to 1. b represents an integer of 1 to 12. )

The arylene group is an atomic group in which two hydrogen atoms have been removed from an aromatic hydrocarbon, and the number of carbon atoms constituting the ring is usually about 6 to 60, preferably 6 to 20. Examples of the aromatic hydrocarbon include those having a condensed ring, and those in which two or more independent benzene rings or condensed rings are bonded directly or via a group such as vinylene.

Examples of the arylene group include groups represented by the following formulas (17-1) to (17-23). Among these, a phenylene group, a biphenylene group, a fluorene-diyl group, and a stilbene-diyl group are preferable.

In addition, in formulas (17-1) to (17-23), R is the same or different, and hydrogen atom, halogen atom, alkyl group, alkyloxy group, alkylthio group, aryl group, aryloxy group, arylthio group , Arylalkyl group, arylalkyloxy group, arylalkylthio group, acyl group, acyloxy group, amide group, imide group, imine residue, amino group, substituted amino group, substituted silyl group, substituted silyloxy group, substituted silylthio group, substituted Silylamino group, monovalent heterocyclic group, heteroaryloxy group, heteroarylthio group, arylalkenyl group, arylethynyl group, carboxyl group, alkyloxycarbonyl group, aryloxycarbonyl group, arylalkyloxycarbonyl group, heteroaryloxycarbonyl group or cyano group Represents.

Like the line represented by x-y in formula (17-1), the line applied across the ring structure means that the ring structure is directly bonded to the atom in the portion to be bonded. That is, in formula (17-1), it means directly bonding with any of the carbon atoms constituting the ring to which the line represented by x-y is given, and the bonding position in the ring structure is not limited. Like the line represented by z- in Formula (17-10), the line given to the vertex of the ring structure means that the ring structure is directly bonded to the atom in the portion to be bonded at that position. In addition, the line to which R is given by crossing the ring structure means that one R may be bonded to the ring structure, or a plurality of R may be bonded, and the bonding position thereof is also not limited.

In addition, in formulas (17-1) to (17-10) and (17-15) to (17-20), the carbon atom may be substituted with a nitrogen atom, an oxygen atom or a sulfur atom, and the hydrogen atom is fluorine It may be substituted with an atom.

[Formula 24-1]

[Formula 24-2]

The divalent heterocyclic group refers to the remaining atomic group from which two hydrogen atoms have been removed from the heterocyclic compound, and the number of carbon atoms constituting the ring is usually about 3 to 60. As the heterocyclic compound, among organic compounds having a cyclic structure, the elements constituting the ring include not only carbon atoms but also heteroatoms such as oxygen, sulfur, nitrogen, phosphorus, boron, and arsenic in the ring.

As said divalent heterocyclic group, the heterocyclic group etc. which are represented by following formula (18-1)-(18-38) are mentioned, for example.

In addition, in formulas (18-1) to (18-38), R is the same as R that the arylene group has. Y represents O, S, SO, SO ₂ , Se, or Te. The lines given by crossing the cyclic structure, the lines given to the vertices of the cyclic structure, and the lines with the R given by crossing the cyclic structure are the same as those in Formulas (17-1) to (17-23).

In addition, in formulas (18-1) to (18-38), a carbon atom may be substituted with a nitrogen atom, an oxygen atom, or a sulfur atom, and a hydrogen atom may be substituted with a fluorine atom.

[Chemical Formula 25-1]

[Chemical Formula 25-2]

The divalent group having the metal complex structure is the remaining divalent group from which two hydrogen atoms have been removed from the organic ligand of the metal complex having the organic ligand. The carbon number of the organic ligand is usually about 4 to 60, for example, 8-quinolinol and its derivatives, benzoquinolinol and its derivatives, 2-phenyl-pyridine and its derivatives, and 2-phenyl-benzothia Sol and its derivatives, 2-phenyl-benzoxazole and its derivatives, porphyrin and its derivatives, and the like.

Examples of the central metal of the metal complex include aluminum, zinc, beryllium, iridium, platinum, gold, europium, terbium, and the like, and the metal complex having the organic ligand is a low-molecular fluorescent material or a phosphorescent material. And known metal complexes, triplet light-emitting complexes, and the like.

Specific examples of the divalent group having the metal complex structure include groups represented by the following formulas (19-1) to (19-7).

In addition, in formulas (19-1) to (19-7), R is the same as R that the arylene group has. About the line given to the vertex of the ring structure, it means a direct bond similarly to Formulas (17-1) to (17-23).

In addition, in formulas (19-1) to (19-7), a carbon atom may be substituted with a nitrogen atom, an oxygen atom or a sulfur atom, and a hydrogen atom may be substituted with a fluorine atom.

[Chemical Formula 26-1]

[Chemical Formula 26-2]

Moreover, as the structure of A, a structure similar to the following formula (16-5) is also mentioned.

[Formula 27]

(In the formula, Ar4, Ar5, Ar6 and Ar7 are the same or different and represent an arylene group or a divalent heterocyclic group. Ar8, Ar9 and Ar10 are the same or different and represent an aryl group or a monovalent heterocyclic group. o and p is the same or different, represents 0 or 1, and is 0≦o+p≦1.)

As a specific example of the structure represented by the said formula (16-5), the structure represented by following formula (20-1)-(20-8) is mentioned.

[Chemical Formula 28-1]

[Chemical Formula 28-2]

In addition, in formulas (20-1) to (20-8), R is the same as R that the arylene group has. About the line given to the vertex of the ring structure, it means a direct bond similarly to Formulas (17-1) to (17-23). In the above formulas (20-1) to (20-8), although a plurality of R is included in one structural formula, they may be the same or different groups. In order to increase the solubility in a solvent, it is preferable to have one or more other than a hydrogen atom, and it is preferable to have less symmetry of the shape of the structure including a substituent. In addition, in the above formulas (20-1) to (20-8), when R contains an aryl group or a heterocyclic group in a part thereof, they may further have one or more substituents. In addition, when R is a substituent containing an alkyl chain, they may be linear, branched, or cyclic, or a combination thereof, and when not linear, for example, isoamyl group, 2-ethylhexyl group , A 3,7-dimethyloctyl group, a cyclohexyl group, and a 4-C1 to C12 alkylcyclohexyl group. In order to increase the solubility of the boron-containing copolymer of the present invention in a solvent, it is preferable that one or more cyclic or branched alkyl chains are included.

Moreover, a plurality of R may be connected to form a ring. In the case where R is a group containing an alkyl chain, the alkyl chain may be interrupted by a group containing a hetero atom. Examples of the hetero atom include an oxygen atom, a sulfur atom, and a nitrogen atom.

The structure of A is preferably a formula (16-5), a formula (17-9), a formula (18-16), or a formula (18-28), among the above.

The boron-containing polymer has a repeating unit formed by polymerization of at least one group of X ⁵ , X ⁶ , R ¹ and R ² in formula (2) and at least one group of X ⁷ and X ⁸ in formula (15). . That is, the following formula (21);

[Chemical Formula 29]

(In the formula, the circular arc of the dotted line, the dotted line portion in the skeleton portion connecting the boron atom and the nitrogen atom, and the arrow from the nitrogen atom to the boron atom are the same as those of the formula (2). X ^5' , X ^6' , R ^{1 ′} And R ^{2 ′} are the same as in formula (12), A is the same or different, and represents a divalent group, X ^{7 ′} and X ^{8 ′} are the same groups as X ⁷ and X ^{8 in} formula (15), 2 A boron-containing polymer having a structure of a repeating unit represented by a valent group, a trivalent group, or a direct bond is also included in the boron-containing polymer in the present invention.

In the formula (21), any one or more of X ^{5 ′} , X ^{6 ′} , R ^{1 ′} and R ^{2 ′} , and any one or more of X ^{7 ′} and X ^{8 ′} are the main chains of the polymer. It means forming a bond as part.

In the boron-containing polymer having a repeating unit represented by the formula (21), the repeating unit derived from the formula (2) and the repeating unit derived from the formula (15) may be a random polymer, a block polymer, or a graft polymer. In addition, a dendrimer may be used or a case where there is a branch in the polymer main chain and has three or more terminal portions. Moreover, it may be a polymer formed by polycondensation of the boron-containing compound represented by the formula (2) and the compound represented by the formula (15).

In addition, the boron-containing polymer having a repeating unit represented by the above formula (21) may contain one repeating unit derived from the above formula (2) and one repeating unit derived from the above formula (15), or two or more. It can be done. When two or more types of repeating units are included, the two or more types of structures may be a random polymer, a block polymer, or a graft polymer. In addition, a dendrimer may be used or a case where there is a branch in the polymer main chain and has three or more terminal portions.

As the boron-containing polymer represented by the formula (21), (i) any two of X ⁵ , X ⁶ , R ¹ and R ² in the formula (2) and X ⁷ and X ⁸ in the formula (15) are In the case of forming a bond as a part of the main chain of the polymer, (ii) any one of X ⁵ , X ⁶ , R ¹ and R ² in the above formula (2), and among X ⁷ and X ⁸ in the above formula (15) In some cases, any one group forms a bond as part of the main chain of the polymer. As a specific example of the structure of the repeating unit in these cases, there are structures such as the following formulas (22) and (23).

[Formula 30]

(i) When any two of X ⁵ , X ⁶ , R ¹ and R ² in the formula (2) and X ⁷ and X ⁸ in the formula (15) form a bond as a part of the main chain of the polymer, The repeating unit derived from the formula (2) and the repeating unit derived from the formula (15) may be randomly added or block-added, and X ⁵ , X ⁶ , R ¹ and R in the formula (2) Any group in ² and X ⁷ and/or X ⁸ in the formula (15) may be polycondensed, but among these, any two groups of X ⁵ , X ⁶ , R ¹ and R ² in the formula (2) and the above As an example of a polymer in which X ⁷ and/or X ⁸ in formula (15) is polycondensed, the polycondensation of X ⁵ and X ⁶ in formula (2) and X ⁷ and X ⁸ in formula (15) is the following formula (24 It becomes a polymer which has the structure represented by) as a repeating unit.

[Formula 31]

In the case of the structure of the above (i), as a specific example of the structural moiety derived from the above formula (2) among the repeating units represented by the above formula (21), structures such as the above formulas (13-1) to (13-6) have. Among these, it is preferable that it is the structure of (13-1) and (13-6). More preferably, it is the structure of (13-1).

The combination of a reactive group in the case of polycondensation of any group of X ⁵ , X ⁶ , R ¹ and R ² in the formula (2) and any group of X ⁷ and X ⁸ in the formula (15) is the same as described above. Can be mentioned. That is, when any group of X ⁵ , X ⁶ , R ¹ and R ² in the formula (2) and any group of X ⁷ and X ⁸ in the formula (15) polycondensate, X ⁷ in the formula (15) and Among X ⁸ , as the group to be polycondensed, any of the substituents having the above-described polycondensable reactive group in the structure is preferable.

In addition, when any of X ⁷ and X ⁸ in the above formula (15) is a substituent having a reactive group capable of independently polymerizing in the structure, the substituent is among the substituents having a reactive group capable of polymerizing independently as described above. Which is preferred.

The group bonded to both ends of the boron-containing polymer of the present invention is not particularly limited, and may be the same or different. Examples of the groups bonded to both ends include a hydrogen atom, a halogen atom, an aryl group, an oligoaryl group, a monovalent heterocyclic group, a monovalent oligoheterocyclic group, an alkyl group, an alkoxy group, Alkylthio group, aryloxy group, arylthio group, arylalkyl group, arylalkoxy group, arylalkylthio group, alkenyl group, alkynyl group, allyl group, amino group, azo group, carboxyl group, acyl group, alkoxycarbonyl group, formyl group, nitro group , A cyano group, a silyl group, a stanyl group, a boryl group, a phosphino group, a silyloxy group, an arylsulfonyloxy group, and an alkylsulfonyloxy group.

The boron-containing polymer in the present invention preferably has a weight average molecular weight of 10 ³ to 10 ⁸ . When the weight average molecular weight is such a range, it can be formed into a thin film favorably. More preferably, they are 10 ³ to 10 ⁷ , and still more preferably 10 ⁴ to 10 ⁶ .

The weight average molecular weight can be measured by the following apparatus and measurement conditions by gel permeation chromatography (GPC apparatus, developing solvent; chloroform) in terms of polystyrene.

High-speed GPC device: HLC-8220GPC (manufactured by Tosoh Corporation)

Developing solvent chloroform

Column TSK-gel GMHXL x 2

Eluent flow rate 1 ml/min

Column temperature 40°C

The boron-containing polymer in the present invention is produced by polymerizing a monomer component containing a boron-containing compound represented by the above formula (2). The monomer component may contain other monomers as long as it contains the boron-containing compound represented by the above formula (2), but the boron-containing compound represented by the above formula (2) is 0.1 It is preferable to contain-99.9 mass%. More preferably, it is 10 to 90 mass %.

In addition, during the polymerization reaction, the solid content concentration of the monomer component can be appropriately set in the range of 0.01% by mass to the maximum dissolved concentration, but if it is too lean, the reaction efficiency is poor, and if it is too thick, the control of the reaction may become difficult. In, Preferably, it is 0.1-20 mass %.

It is preferable that the other monomers have a structure represented by the formula (15). In addition, the said monomer component may contain 1 type, or 2 or more types of a boron-containing compound represented by said Formula (2), and a compound represented by Formula (15).

In the case of containing a compound having a structure represented by the formula (15) as the other monomer, the structure represented by the formula (15) with respect to 1 mole of the boron-containing compound represented by the formula (2) contained in the monomer component It is preferable to contain the compound having from 0.3 to 3 mole ratio. More preferably, it is the ratio of 0.2-2 mol with respect to 1 mol of the boron-containing compound represented by said formula (2).

In the compound represented by the above formula (15), X ⁷ and X ⁸ may be the same as the substituent having a reactive group in X ⁵ and X ⁶ described above.

When the boron-containing polymer in the present invention is formed by a polycondensation reaction, the method for producing the boron-containing polymer is not particularly limited, but, for example, it can be prepared by the production method described in Japanese Unexamined Patent Application Publication No. 2011-184430. I can.

Both the boron-containing compound represented by the above formula (1) or the boron-containing polymer obtained by polymerizing the monomer component containing the boron-containing compound represented by the above formula (2) can form a uniform film by coating, and have low HOMO, Since it has an LUMO level, it can be preferably used as a material for the first organic electroluminescent device of the present invention.

[Organic EL device of the second preferred embodiment of the present invention]

In the organic electroluminescent device of the second preferred embodiment of the present invention (hereinafter, also referred to as the second organic electroluminescent device of the present invention), the buffer layer contains a reducing agent. In the organic electroluminescent device of the present invention, as will be described later, the first electrode is a cathode, the second electrode is an anode, and the buffer layer is a layer capable of functioning as an electron transport layer by selection of a material forming the buffer layer. to be.

In an organic electroluminescent device, holes are supplied from the anode and electrons are supplied from the cathode, and they recombine in the emission layer to emit light, but some of the holes supplied from the anode pass through the second metal oxide layer, the emission layer, the buffer layer, and the first metal oxide layer. Thus, it reaches the cathode, and this is considered to be one factor that lowers the efficiency of the organic electroluminescent device. By forming the buffer layer having a predetermined thickness, it is possible to suppress the holes from reaching the cathode, thereby increasing the efficiency of the device. On the other hand, if the thickness of the buffer layer is increased, the movement of electrons from the cathode to the light emitting layer is hindered, and there is a difference in the ratio of electrons reaching the light emitting layer from the edge portion and the portion other than the edge portion where the influence of the thickness of the buffer layer is relatively small. , A phenomenon in which only the edge portion emit light occurs. On the other hand, if a reducing agent having a function of supplying electrons is included in the buffer layer, sufficient electrons are supplied to the light-emitting layer, the recombination of electrons and holes is effectively performed, and the driving voltage required for light emission is lowered. Accordingly, an organic electroluminescent device having remarkably excellent luminous efficiency can be obtained.

The second organic electroluminescent device of the present invention includes a first metal oxide layer, a buffer layer, a low-molecular compound layer including an emission layer stacked on the buffer layer, and a second metal oxide layer between the first electrode and the second electrode. In this order, it is preferred that the buffer layer contains a reducing agent.

The second organic electroluminescent device of the present invention includes a first metal oxide layer, a buffer layer, a low-molecular compound layer including an emission layer stacked on the buffer layer, and a second metal oxide layer between the first electrode and the second electrode. As long as it has in this order, you may have layers other than these. The meaning of the low molecular weight compound in the present invention is as described above.

In the second organic electroluminescent device of the present invention, the buffer layer is preferably a layer having an average thickness of 5 to 100 nm formed by applying a solution containing an organic compound.

In the second organic electroluminescent device of the present invention, in the case of laminating a low molecular weight compound layer including a light emitting layer on the first metal oxide layer, crystallization of the low molecular weight compound layer in contact with the metal oxide layer occurs, thereby increasing the leakage current. The current efficiency decreases, and in a remarkable case, there is a concern that a problem that uniform surface light emission cannot be obtained due to crystallization may occur. In the organic-inorganic hybrid type organic electroluminescent device, the cause of crystallization of the low molecular weight compound layer is as described above. Such crystallization is a problem peculiar to an organic-inorganic hybrid type organic electroluminescent device, and is a problem newly created when a low-molecular compound is used as a host of the light emitting layer.

For this problem, if a buffer layer having an average thickness of 5 to 100 nm formed by applying a solution containing an organic compound between the first metal oxide layer and the low molecular compound layer including the light emitting layer is formed, the low molecular weight in the low molecular compound layer Crystallization of the compound is suppressed, whereby the leakage current can be suppressed even when the organic-inorganic hybrid type organic electroluminescent device has a layer formed from a low-molecular compound as a light emitting layer or the like, and non-uniformity caused by the leakage current Surface light emission can be suppressed.

As described above, when the thickness of the buffer layer is increased, it is observed that only the edge portion of the light emitting layer emit light more strongly than other portions, but for this, by including a reducing agent in the buffer layer, only the edge portion can emit light. Suppression, and uniform surface light emission can be obtained. Therefore, when the present invention is used, good device characteristics are obtained even if the average thickness of the buffer layer is 5 to 100 nm.

In the second organic electroluminescent device of the present invention, as described above, a buffer layer capable of functioning as an electron transport layer is formed by coating, and a reducing agent, which is an n-dopant, is included in the buffer layer. It is also possible to form a low-molecular compound, and it is also excellent in luminous efficiency.

The method, material, and preferred thickness of the buffer layer will be described later.

The reducing agent contained in the buffer layer is not particularly limited as long as it is an electron donating compound, but is preferably a hydride reducing agent capable of performing hydride reduction.

As a hydride reducing agent, 2,3-dihydrobenzo[d]imidazole compound; 2,3-dihydrobenzo[d]thiazole compound; 2,3-dihydrobenzo[d]oxazole compound; triphenylmethane Compound; One type or two or more types, such as a dihydropyridine compound, can be used.

Thus, the hydride reducing agent is 2,3-dihydrobenzo [d] imidazole compound, 2,3-dihydrobenzo [d] thiazole compound, 2,3-dihydrobenzo [d] oxazole compound, tri It is one of the preferred embodiments of the present invention that it is at least one compound selected from the group consisting of a phenylmethane compound and a dihydropyridine compound.

As a hydride reducing agent, 2,3-dihydrobenzo[d]imidazole compound and a dihydropyridine compound are preferable among these. More preferably, (4-(1,3-dimethyl-2,3-dihydro-1H-benzoimidazol-2-yl)phenyl)dimethylamine (N-DMBI), or 2,6-dimethyl-1 ,4-dihydropyridine-3,5-dicarboxylic acid diethyl (hanchi ester).

The amount of the reducing agent contained in the buffer layer is preferably 0.1 to 15% by mass based on 100% by mass of the organic compound forming the buffer layer. When the reducing agent is included in such a ratio, the luminous efficiency of the organic electroluminescent device can be sufficiently high. More preferably, it is 0.5-10 mass% with respect to 100 mass% of the organic compound which forms a buffer layer, More preferably, it is 1-5 mass%.

The second organic electroluminescent device of the present invention includes a low-molecular compound layer including an emission layer stacked on a buffer layer, but the low-molecular compound layer including the emission layer means one layer formed of a low molecular compound or a plurality of low molecular compounds. The layers of are stacked, and one of them is a light emitting layer. That is, the low-molecular compound layer including the light-emitting layer is either a light-emitting layer formed of a low-molecular compound, or a stack of a light-emitting layer formed of a low-molecular compound and other layers formed of a low-molecular compound. The other layers formed of the low molecular weight compound may be one layer or two or more layers. Further, the order in which the light emitting layer and other layers are stacked is not particularly limited.

It is preferable that the other layer formed of the low molecular compound is a hole transport layer or an electron transport layer. That is, when the low molecular weight compound layer is made of a plurality of layers, it is preferable to have a hole transport layer and/or an electron transport layer as other layers other than the light emitting layer. As described above, it is one of preferred embodiments of the second organic electroluminescent device of the present invention that the organic electroluminescent device has a hole transport layer and/or an electron transport layer as independent layers different from the emission layer.

When the second organic electroluminescent device of the present invention has a hole transport layer as an independent layer, it is preferable to have a hole transport layer between the light emitting layer and the second metal oxide layer. When the second organic electroluminescent device of the present invention has an electron transport layer as an independent layer, it is preferable to have an electron transport layer between the buffer layer and the light emitting layer.

When the second organic electroluminescent element of the present invention does not have a hole transport layer or an electron transport layer as an independent layer, any of the layers having as an essential configuration of the second organic electroluminescent element of the present invention also functions as these layers.

One of the preferred forms of the second organic electroluminescent device of the present invention is that the organic electroluminescent device comprises only a first electrode, a first metal oxide layer, a buffer layer, a light emitting layer, a hole transport layer, a second metal oxide layer, and a second electrode, Any of these layers is a type that also functions as an electron transport layer.

In addition, the organic electroluminescent device is composed of only a first electrode, a first metal oxide layer, a buffer layer, a light emitting layer, a second metal oxide layer, and a second electrode, and any of these layers also functions as a hole transport layer and an electron transport layer. It is also one of the preferred embodiments of the second organic electroluminescent device of the present invention.

In the second organic electroluminescent device of the present invention, the first electrode is a cathode, and the second electrode is an anode. The compounds usable as the first electrode and the second electrode, and among them, preferred are the same as those of the first organic electroluminescent device of the present invention described above.

Moreover, the preferable value of the average thickness of a 1st electrode and a 2nd electrode is also the same as the 1st organic electroluminescent element of this invention mentioned above.

The first metal oxide layer functions as an electron injection layer, and the second metal oxide layer functions as a hole injection layer.

Specific examples of the compound for forming the first metal oxide layer and the second metal oxide layer, and preferred among them are the same as those of the first organic electroluminescent device of the present invention described above.

The average thickness of the first metal oxide layer is not particularly limited, but is preferably 1 to 1000 nm. More preferably, it is 2-100 nm.

The average thickness of the second metal oxide layer is not particularly limited, but is preferably 1 to 1000 nm. More preferably, it is 5 to 50 nm.

The average thickness of the first metal oxide layer can be measured by a stylus type step meter or spectroscopic ellipsometry.

The average thickness of the second metal oxide layer can be measured at the time of film formation using a crystal oscillator film thickness meter.

As the material for the light-emitting layer, any low-molecular compound that can be used normally as a material for the light-emitting layer may be used, and these may be mixed and used.

As the low molecular weight one, the same ones as those in the first organic electroluminescent element of the present invention described above can be used.

The light emitting layer may contain a dopant. As the dopant, the same ones as those in the first organic electroluminescent device of the present invention can be used, and the preferred range of the content of the dopant in the case where the light-emitting layer contains a dopant is also the first organic electric field of the present invention described above. It is the same as in the case of a light emitting device.

It is preferable that the light emitting layer of the second organic electroluminescent device of the present invention contains a phosphorescent material among the above. When the light-emitting layer contains a phosphorescent light-emitting material, the organic electroluminescent device becomes more excellent in light-emitting efficiency.

When the light-emitting layer contains a phosphorescent material, it is preferable that the light-emitting layer is formed of a material containing a phosphorescent material as a guest material (dopant) in the host material. When the light emitting layer is formed of such a material, the content of the phosphorescent light emitting material to the material forming the light emitting layer is preferably the same as the content of the dopant to the material forming the light emitting layer when the light emitting layer contains a dopant.

As the phosphorescent material, a compound represented by any of the following formulas (25) and (26) can be preferably used as the phosphorescent material.

[Formula 32]

(In formula (25), the circular arc of the dotted line indicates that a ring structure is formed together with a part of the skeleton part composed of an oxygen atom and three carbon atoms, and the ring structure formed including a nitrogen atom is a heterocyclic structure. X ', X'is the same or different, represents a hydrogen atom or a monovalent substituent serving as a substituent of a ring structure, and may be bonded to a plurality of ring structures forming a dotted circular arc portion. X', X''May combine to form a new ring structure with some of the two ring structures indicated by the dotted arcs. In addition, when n ² is 2 or more, a plurality of X's or X's may be combined to form one The dotted line in the skeleton portion composed of a nitrogen atom and three carbon atoms indicates that the two atoms connected by the dotted line are bonded by a single bond or a double bond, M'represents a metal atom. The arrow from atom to M'indicates that the nitrogen atom is coordinated with the M'atom, n ² represents the valence of the metal atom M'.)

[Formula 33]

(In formula (26), the circular arc of the dotted line indicates that a ring structure is formed together with a part of the skeleton part composed of an oxygen atom and three carbon atoms, and the ring structure formed including a nitrogen atom is a heterocyclic structure. X ', X'is the same or different, represents a hydrogen atom or a monovalent substituent serving as a substituent of a ring structure, and may be bonded to a plurality of ring structures forming a dotted circular arc portion. X', X''May combine to form a new ring structure with a portion of the two ring structures indicated by the dotted circular arcs. The dotted line in the skeletal part consisting of a nitrogen atom and three carbon atoms is a single bond or a single bond of two atoms connected by a dotted line. M'represents a metal atom, the arrow from the nitrogen atom to M'indicates that the nitrogen atom is coordinated with the M'atom, n ² represents the valence of the metal atom M'X arc of the solid line connecting the ^a and X ^b may form a ring structure with the indicates that the bond to the X ^a and X ^b via the at least one other atom, X ^a and X ^b. X ^a, X ^b represents any of the same or different, an oxygen atom, a nitrogen atom, a carbon atom. from X ^b M 'arrow to have a X ^b M' indicates that they are coordinated to atoms. m 'is a number from 1 to 3 .)

Examples of the ring structure represented by the dotted circular arc in the formulas (25) and (26) include aromatic rings and heterocycles having 2 to 20 carbon atoms, and aromatic hydrocarbon rings such as benzene rings, naphthalene rings, and anthracene rings. Pyridine ring, pyrimidine ring, pyrazine ring, triazine ring, benzothiazole ring, benzothiol ring, benzoxazole ring, benzoxole ring, benzoimidazole ring, quinoline ring, isoquinoline ring, quinoxaline ring, and And hetero rings such as a phenanthridine ring, a thiophene ring, a furan ring, a benzothiophene ring, and a benzofuran ring.

In the formulas (25) and (26), examples of the substituent in the ring structure represented by X'and X'' include a halogen atom, 1 to 20 carbon atoms, preferably an alkyl group having 1 to 10 carbon atoms, and 1 to 20 carbon atoms, Preferably a C1-C10 aralkyl group, a C1-C20, preferably a C1-C10 alkenyl group, a C1-C20 aryl group, preferably a C1-C10 aryl group, an arylamino group, a cyano group, an amino group , An acyl group, a C1-C20, preferably a C1-C10 alkoxycarbonyl group, a carboxyl group, a C1-C20, preferably a C1-C10 alkoxy group, a C1-C20, preferably a C1-C10 Alkylamino group, C1-C20, preferably C1-C10 dialkylamino group, C1-C20, preferably C1-C10 aralkylamino group, C1-C20, Preferably C1-C10 A haloalkyl group, a hydroxyl group, an aryloxy group, a carbazole group, and the like.

In addition, when the substituent of the ring structure represented by X'and X'' is an aryl group or an arylamino group, the aromatic ring contained in the aryl group or arylamino group may further have a substituent. The same thing as the specific example of the substituent represented by X'and X'' is mentioned.

In the above formulas (25) and (26), when substituents represented by X'and X'' are bonded to form a new ring structure together with some of the two ring structures represented by dotted circular arcs, the dotted line As a ring structure in which two ring structures represented by an arc and a new ring structure are combined, structures such as the following (27-1) and (27-2) are exemplified.

[Formula 34]

In the above formulas (25) and (26), examples of the metal atom represented by M'include ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum, and gold.

Examples of the structure represented by the above formula (26) include structures of the following formulas (28-1) and (28-2).

[Formula 35]

(In formulas (28-1) and (28-2), R ³ to R ⁵ are the same or different, and represent a hydrogen atom or a monovalent substituent. In formula (28-2), R ³ to R ⁵ are In the case of a monovalent substituent, the ring structure may have a plurality of monovalent substituents Arrows from a nitrogen atom to M'and an arrow from an oxygen atom to M'indicate that a nitrogen atom and an oxygen atom are coordinated with the M'atom. The dotted arc, the dotted line in the skeletal part composed of a nitrogen atom and 3 carbon atoms, X', X'', M', n ² and m'are the same as in formula (26).)

Examples of the monovalent substituent of R ³ to R ⁵ include the same substituents of the ring structures represented by X'and X'' in the formulas (25) and (26).

As a specific example of the compound represented by said formula (25) or formula (26), the compound etc. represented by following formula (29-1)-(29-30) are mentioned.

[Chemical Formula 36-1]

[Chemical Formula 36-2]

[Chemical Formula 36-3]

[Chemical Formula 36-4]

As the phosphorescent material in the present invention, one or two or more of those described above can be used, but among these, iridium tris (2-phenylpyridine) represented by the formula (29-1) (Ir (ppy ) ₃ ), iridium tris (1-phenylisoquinoline) (Ir (piq) ₃ ) represented by the formula (29-19), iridium bis (2-methyldibenzo-[f) represented by the formula (29-27) ,h] Quinoxaline) (acetylacetonate) (Ir(MDQ) ₂ (acac)), iridium tris [3-methyl-2-phenylpyridine] (Ir(mpy) ₃ ) represented by the above formula (29-28) And the like are preferred.

As the host material, the following formula (30);

[Formula 37]

(In formula (30), the circular arc of the dotted line indicates that a ring structure is formed with a part of the skeleton connecting the oxygen atom and the nitrogen atom, and the ring structure formed including Z ¹ and the nitrogen atom is a heterocyclic structure. X'and X'' are the same or different, represent a hydrogen atom, or a monovalent substituent serving as a substituent of the ring structure, and may be bonded to a plurality of ring structures forming the circular arc portion of the dotted line. , X'' may be combined to form a new ring structure together with some of the two ring structures indicated by the dotted circular arc. The dotted line in the skeletal part connecting the oxygen atom and the nitrogen atom is the two valences connected by the dotted line. It represents bonded by a single bond or a double bond M represents a metal atom Z ¹ represents a carbon atom or a nitrogen atom The arrow from the nitrogen atom to M represents that the nitrogen atom is coordinated with the M atom R ⁰ represents a monovalent substituent or a divalent linking group, m represents the number of R ^{0 and} is a number of 0 or 1. n ³ represents the valence of the metal atom M. r is a number of 1 or 2.) Representing metal complexes,

The following formula (31);

[Formula 38]

(In the formula, X'and X'' are the same or different and represent a hydrogen atom or a monovalent substituent serving as a substituent of the quinoline ring structure, and may be bonded to the quinoline ring structure in a plurality. M represents a metal atom. The arrow from the nitrogen atom to M indicates that the nitrogen atom is coordinated with the M atom, R ⁰ represents a monovalent substituent or a divalent linking group, m represents the number of R ^{0 and} is the number of 0 or 1. n ³ represents the valence of the metal atom M. r is a number of 1 or 2.)

The following formula (32);

[Formula 39]

(In the formula, the circular arc of the dotted line indicates that a ring structure is formed together with a part of the skeleton that connects the oxygen atom and the nitrogen atom, and the ring structure formed including Z ¹ and the nitrogen atom is a heterocyclic structure. X ', X'is the same or different, represents a hydrogen atom or a monovalent substituent serving as a substituent of a ring structure, and may be bonded to a plurality of ring structures forming a dotted circular arc portion. X', X''May combine to form a new ring structure together with a part of the two ring structures indicated by the dotted circular arc. The dotted line in the skeletal part connecting the oxygen atom and the nitrogen atom is a single bond or It represents bonded by a double bond M represents a metal atom Z ¹ represents a carbon atom or a nitrogen atom The arrow from the nitrogen atom to M represents that the nitrogen atom is coordinated with the M atom n ³ represents a metal represents the valence of the atom M. arc of the solid line connecting the X ^a and X ^b represents that the bond to the X ^a and X ^b via the at least one other atom, form a ring structure together with X ^a and X ^b In addition, a coordination bond may be included in the bond between X ^a and X ^b through at least one other atom, and X ^a and X ^b are the same or different, and any of an oxygen atom, a nitrogen atom, and a carbon atom indicates that. from X ^b arrow to the M indicates a X ^b that is coordinated to the M atom. m 'is a number from 1 to 3.) include metal complexes represented by, and these one or two of You can use the above.

In the above formula (30), when r is 1, it becomes a metal complex represented by the following formula (33-1) having one M atom in the structure, and when r is 2, it has two M atoms in the structure. It becomes a metal complex represented by the following formula (33-2).

[Formula 40]

In the above formulas (30) and (32), the ring structure represented by the dotted circular arc may be a ring structure consisting of one ring or a ring structure consisting of two or more rings. Examples of such a cyclic structure include aromatic rings and heterocycles having 2 to 20 carbon atoms, and aromatic rings such as benzene rings, naphthalene rings and anthracene rings; diazole rings, thiazole rings, isothiazole rings, oxazole rings , Isoxazole ring, thiadiazole ring, oxadiazole ring, triazole ring, imidazole ring, imidazoline ring, pyridine ring, pyrazine ring, pyridazine ring, pyrimidine ring, diazine ring, triazine ring And heterocycles such as a benzoimidazole ring, a benzothiazole ring, a benzoxazole ring, and a benzotriazole ring.

Among these, benzene ring, thiazole ring, isothiazole ring, oxazole ring, isoxazole ring, thiadiazole ring, oxadiazole ring, triazole ring, imidazole ring, imidazoline ring, pyridine ring, A pyridazine ring, a pyrimidine ring, a benzoimidazole ring, a benzothiazole ring, a benzoxazole ring, and a benzotriazole ring are preferred.

As a substituent in the ring structure represented by X'and X'' in the formulas (30) to (32), the ring structure represented by X'and X'' in the formulas (25) and (26) The same thing as a substituent is mentioned.

In the above formulas (30) and (32), substituents of the ring structure represented by X'and X'' are bonded to each other to form a new ring structure together with some of the two ring structures represented by dotted circular arcs. In the case, as a ring structure in which two ring structures represented by dotted circular arcs and a new ring structure are combined, structures such as (27-1) and (27-2) are mentioned, for example.

In the formulas (30) to (32), the metal atom represented by M is preferably a metal atom from Groups 1 to 3, 9, 10, 12, or 13 of the periodic table, and zinc, aluminum, gallium, Any of platinum, rhodium, iridium, beryllium, and magnesium is preferable.

In the above formulas (30) and (31), when R ⁰ is a monovalent substituent, the monovalent substituent is preferably any one of the following formulas (34-1) to (34-3).

[Formula 41]

(In the formula, Ar ¹ to Ar ⁵ represents a structure in which two or more aromatic rings, hetero rings, or two or more aromatic rings or heterocycles which may have a substituent are directly bonded, and Ar ³ to Ar ⁵ may have the same structure or different structures. Q ⁰ represents a silicon atom or a germanium atom.)

Specific examples of the aromatic ring or heterocycle of Ar ¹ to Ar ⁵ include the same as the specific examples of the aromatic ring or heterocyclic ring of the ring structure represented by the dotted circular arc in the formula (30), and the aromatic ring or the hetero ring Examples of the structure in which two or more A are directly bonded include a structure in which two or more ring structures exemplified as specific examples of these aromatic rings or heterocycles are directly bonded. In this case, the two or more aromatic rings or heterocycles directly bonded may have the same ring structure or different ring structures.

As a specific example of the substituent of an aromatic ring or a heterocyclic ring, the thing similar to the specific example of the substituent of the aromatic ring or the heterocyclic ring of the ring structure represented by the dotted circular arc in said formula (30) is mentioned.

In the above formulas (30) and (31), when R ⁰ is a divalent linking group, it is preferable that R ⁰ is either -O- or -CO-.

In the formula (32), X ^a, the structure is formed in a circular arc of a solid line connecting the X and ^b, X ^a and X ^b is a ring structure may contain one or a plurality. The ring structure may be formed including X ^a and X ^b , and the ring structure in that case is the same as the ring structure represented by the dotted circular arc in the above formulas (30) and (32), or a pyrazole ring. Can be lifted. Preferably, it is a structure in which a pyrazole ring is formed including X ^a and X ^b .

In the formula (32), the circular arc of the solid line connecting X ^a and X ^b may consist of only carbon atoms or may contain other atoms. As another atom, a boron atom, a nitrogen atom, a sulfur atom, etc. are mentioned.

Also as the arc of the solid line connecting the X ^a and X ^b is may contain a ring structure other than the ring structure formed including X ^a, X ^b or 2 greater than or equal to 1, the ring structure in that case, the formula In (30) and formula (32), the same thing as the ring structure represented by the dotted circular arc, and a pyrazole ring are mentioned.

As a structure represented by said formula (32), the structure etc. of following formula (35) are mentioned.

[Formula 42]

(In formula (35), R ³ to R ⁵ are the same or different and represent a hydrogen atom or a monovalent substituent. The arrow from nitrogen atom to M and the arrow from oxygen atom to M are nitrogen atom, oxygen atom is M atom. The circular arc of the dotted line, the dotted line in the skeletal part connecting the oxygen atom and the nitrogen atom, X', X'', M, Z ¹ , n ³ and m'are the same as in Equation (32). Do.)

Examples of the monovalent substituent of R ³ to R ^{5 in} the formula (35) include the same substituents of the ring structures represented by X'and X'' in the formulas (25) and (26).

As a specific example of the compound represented by the said formula (30), the compound etc. of the structure represented by following formula (36-1)-(36-40) are mentioned.

[Chemical Formula 43-1]

[Chemical Formula 43-2]

[Chemical Formula 43-3]

[Formula 43-4]

As a specific example of the compound represented by the said formula (31), the compound etc. of the structure represented by following formula (37-1)-(37-3) are mentioned.

[Formula 44]

As a specific example of the compound represented by the said formula (32), the compound etc. of the structure represented by the following formula (38-1)-(38-8) are mentioned.

[Formula 45]

As the host material in the present invention, one or two or more of those described above can be used, but among these, bis[2-(2-benzothiazolyl)phenolato] represented by the above formula (36-11) Zinc, bis(10-hydroxybenzo[h]quinolinate)beryllium (Bebq ₂ ) represented by the above formula (36-34), bis[2-(2-hydroxyphenyl) represented by the above formula (36-35) )-Pyridine] beryllium (Bepp ₂ ) is preferred.

The average thickness of the light emitting layer is not particularly limited, but is preferably 10 to 150 nm. More preferably, it is 20-100 nm.

The average thickness of the light emitting layer can be measured at the time of film formation using a crystal oscillator film thickness meter.

As the material for the hole transport layer, the same material as the material for the hole transport layer in the first organic electroluminescent device of the present invention described above can be used.

Further, the preferable value of the average thickness of the hole transport layer is also the same as in the case of the first organic electroluminescent device of the present invention described above.

As the material for the electron transport layer, the same material as the material for the electron transport layer in the first organic electroluminescent device of the present invention described above can be used.

Further, the preferable value of the average thickness of the electron transport layer is also the same as in the case of the first organic electroluminescent device of the present invention described above.

In the organic electroluminescent device of the present invention, the method of forming the first and second metal oxide layers, the second electrode, the light-emitting layer, the hole transport layer, and the electron transport layer is also in the first organic electroluminescent device of the present invention described above. Is the same as the method of forming these layers.

It is preferable that the buffer layer included in the organic electroluminescent device of the present invention is a layer formed by applying a solution containing an organic compound as described above. By forming a buffer layer having a predetermined thickness by application, it becomes possible to effectively suppress the crystallization of the low molecular weight compound to be formed on the buffer layer.

The method of applying the solution containing the organic compound, the solvent used to prepare the solution containing the organic compound, and the concentration of the organic compound in the solvent are also added to the first organic electroluminescent device of the present invention described above. In the case of applying a solution containing an organic compound to form a buffer layer, it is the same as the method, the solvent, and the concentration. Since the unevenness existing on the surface of the first metal oxide layer is smoothed by forming the buffer layer as a coating film, crystallization of the low-molecular compound formed on the buffer layer next is suppressed.

The difference between such a buffer layer and the invention disclosed in Japanese Laid-Open Patent Publication No. 2012-4492 (Patent Document 5) is as described above.

It is preferable that the buffer layer has an average thickness of 5 to 100 nm. When the average thickness is in such a range, the effect of suppressing crystallization of the low molecular weight compound layer including the light emitting layer can be sufficiently exhibited. If the average thickness of the buffer layer is less than 5 nm, there is a fear that the unevenness present on the first metal oxide surface cannot be sufficiently smoothed, the leakage current becomes large, and the effect of forming the buffer layer cannot be sufficiently exhibited. In addition, if the average thickness of the buffer layer is larger than 100 nm, the driving voltage increases, which is not preferable in practical use. In addition, when a compound having a preferable structure in the present invention described later is used as the organic compound, the buffer layer can sufficiently exhibit the function as an electron transport layer. The average thickness of the buffer layer is more preferably 10 to 60 nm.

The average thickness of the buffer layer can be measured by a stylus type step meter or spectral ellipsometry.

The second organic electroluminescent device of the present invention may be formed by stacking layers constituting the organic electroluminescent device on a substrate. When each layer is stacked on the substrate, it is preferable that each layer is formed on the first electrode formed on the substrate. In this case, the organic electroluminescent device of the present invention may be of a top emission type in which light is extracted on the side opposite to the side with the substrate, or may be of a bottom emission type in which light is extracted on the side with the substrate.

The material of the substrate and the average thickness of the substrate are the same as the material of the substrate and the average thickness of the substrate in the first organic electroluminescent device of the present invention described above.

In the second organic electroluminescent device of the present invention, examples of the organic compound forming the buffer layer include the same organic compound as the organic compound forming the buffer layer in the first organic electroluminescent device of the present invention described above.

Further, in the second organic electroluminescent device of the present invention, the organic compound forming the buffer layer is preferably an organic compound having a boron atom, and more preferably a boron-containing compound represented by the above-described formula (1). The reason why a boron-containing compound having such a structure is preferable is as described above.

In addition, the preferred structure in the boron-containing compound represented by formula (1) is also the same as in the case of the first organic electroluminescent device of the present invention.

The boron-containing compound represented by the above formula (1) is capable of forming a uniform film by application and has low HOMO and LUMO levels, so it can be preferably used as a material for the second organic electroluminescent device of the present invention. .

The second organic electroluminescent device of the present invention is the organic electroluminescent device of the present invention, and the buffer layer contains a reducing agent, whereby it becomes possible to make the organic electroluminescent device excellent in light emission characteristics. Among the second organic electroluminescent devices of the present invention, a low molecular weight compound layer including a first metal oxide layer, a buffer layer, a light emitting layer stacked on the buffer layer, and a second metal between the first electrode and the second electrode It is preferable that the oxide layer is provided in this order, and the buffer layer contains a reducing agent.

As a method of manufacturing an organic-inorganic hybrid type organic electroluminescent device of the second preferred embodiment of the present invention, that is, an organic electroluminescent device having a structure in which a plurality of layers are stacked, the manufacturing method is organic electroluminescent The device has a first metal oxide layer between the first electrode and the second electrode, a buffer layer containing a reducing agent, a low molecular compound layer including a light emitting layer stacked on the buffer layer, and a second metal oxide layer in this order. Another aspect of the present invention is a method of manufacturing an organic electroluminescent device according to the second preferred embodiment of the present invention, which includes the step of laminating each layer constituting the organic electroluminescent device.

The method of manufacturing an organic electroluminescent device of a second preferred embodiment of the present invention preferably includes a step of forming a buffer layer having an average thickness of 5 to 100 nm by applying a solution containing an organic compound.

The method for manufacturing an organic electroluminescent device of the second preferred embodiment of the present invention may include other steps as long as it includes the steps described above, and includes first and second metal oxide layers, buffer layers, and emission layers. The step of forming a layer other than the low molecular compound layer to be described may be included. In addition, the material for forming each layer of the organic EL device, the formation method, the organic compound, the solvent used to prepare a solution containing the organic compound, and the thickness of each layer are the second organic EL device of the present invention. It is the same as and preferred is the same.

[Organic EL device of the third preferred embodiment of the present invention]

The organic light-emitting device of the third preferred embodiment of the present invention (hereinafter, also referred to as the third organic electroluminescent device of the present invention) is, in the organic light-emitting device of the present invention, the buffer layer is made of a nitrogen-containing film, and the average thickness is It is a layer of 3 to 150 nm.

The third organic electroluminescent device of the present invention is, in other words, an organic electroluminescent device having a structure in which a plurality of layers are stacked between an anode and a cathode formed on a substrate, wherein the organic electroluminescent device includes an anode and a cathode. It has a metal oxide layer between, and on the metal oxide layer, it is made of a nitrogen-containing film, and has a layer with an average thickness of 3 to 150 nm.

It is preferable that the nitrogen-containing film does not have electron transport properties. In addition, not having the electron transport property mentioned here indicates that the electron mobility is extremely low. Specifically, the electron mobility is less than about 10 ^-6 cm 2 /Vs, or the electrical conductivity is less than about 10 ^-6 S/m.

The third organic electroluminescent device of the present invention is an inverted organic electroluminescent device having a structure in which a plurality of layers are stacked between an anode and a cathode formed on a substrate, wherein a metal oxide layer is formed between the anode and the cathode. And, as long as the metal oxide layer is formed of a nitrogen-containing film and has an average thickness of 3 to 150 nm, the number of different layers, materials constituting the other layers, or the order of lamination are not particularly limited. However, it is preferable that the metal oxide layer and the nitrogen-containing compound layer are between the cathode and the light emitting layer. The nitrogen-containing compound is excellent in electron injection characteristics, and an organic electroluminescent device having such a layered structure has high electron injection characteristics and becomes a device having excellent luminous efficiency.

The nitrogen-containing film used in the third organic electroluminescent device of the present invention includes (1) a nitrogen-containing film formed by a nitrogen-containing compound on a metal oxide layer, and (2) a high nitrogen-containing film formed by a nitrogen-containing compound on the metal oxide layer. There are four types in total: a film, (3) a nitrogen-containing film formed by decomposing a nitrogen-containing compound on a metal oxide layer, and (4) a high nitrogen-containing film formed by decomposing a nitrogen-containing compound on a metal oxide layer.

The reason why the performance of the organic electroluminescent element is improved by forming such a film is estimated as follows.

Firstly, when a nitrogen atom is included, the lone electron pair tends to form a bond with the metal atom in the substrate. The polarization between the metal-nitrogen bonds exhibits strong electron injection characteristics. In all the nitrogen-containing films (1) to (4) above, this is satisfied. More preferably, the above (2) having a high ratio of nitrogen atoms having a lone electron pair is suitable.

In the above (3) and (4), it is expected to become a film in which nitrogen atoms exist on the substrate at high density due to the phenomenon of decomposition related to film formation, and as a result, it is expected that various metal-nitrogen bonds appear. And among them, it is thought that there is also a metal-nitrogen bond that is stronger than the conventional one. In addition, depending on the decomposition situation, other components such as unnecessary carbon are lost, thereby relatively increasing the nitrogen atom fraction, and as a result, a more preferable environment may be realized (4). In these nitrogen-containing films, since the main source of nitrogen is a metal-nitrogen bond, it is expected that nitrogen atoms are accumulated at a higher density than normal molecular physical adsorption. Due to these factors, it is considered that by having such a nitrogen-containing film, the organic electroluminescent device is excellent in luminous efficiency, device driving stability and device lifetime are excellent. In fact, the phenomenon resulting from the decomposition of the nitrogen-containing compound can be verified by X-ray photoelectron spectroscopy, which is one of the surface analysis techniques. Although specific results are shown in the examples, by using a compound containing nitrogen and carbon as constituent elements as the nitrogen-containing compound and decomposing the compound, the carbon: nitrogen ratio (CN ratio) is from 2:1 to 1 It is observed that the ratio of high nitrogen is up to :1. At the same time, by the above treatment, an increase in the half-width of the nitrogen spectrum is observed, indicating diffusion of the chemical environment, and the appearance of a stronger metal-nitrogen bond is also suggested.

Accordingly, it is considered that the underlying layer of the nitrogen-containing film is a film containing a metal element, which greatly contributes to the expression of the effects exhibited by the third organic electroluminescent device of the present invention as described above.

The nitrogen-containing film of the above (1) and (2) is a film made of a nitrogen-containing compound formed on a metal oxide layer, that is, a film formed without decomposition of the nitrogen-containing compound. The nitrogen-containing film of the above (2) is formed by using a nitrogen-containing compound having a high ratio of the number of nitrogen atoms to the total number of atoms constituting the nitrogen-containing compound.

The method of forming the nitrogen-containing film of the above (1) and (2) is not particularly limited, but a method of volatilizing the solvent after applying a solution of the nitrogen-containing compound onto the metal oxide layer is preferably used.

The nitrogen-containing films of the above (3) and (4) are films formed by decomposing a nitrogen-containing compound on a metal oxide layer, but some of the nitrogen-containing compounds may remain undissolved. Preferably, all of the nitrogen-containing compounds are decomposed.

The method of forming the nitrogen-containing film of the above (3) and (4) is not particularly limited, but a method of decomposing and forming the nitrogen-containing compound after applying a solution of the nitrogen-containing compound onto the metal oxide layer is preferably used.

It is preferable that the nitrogen-containing film is formed by a method including a step of applying a solution containing a nitrogen-containing compound on the metal oxide layer. By forming the nitrogen-containing film by a method including such a process, the organic electroluminescent device having a metal oxide layer can suppress leakage current and obtain uniform surface light emission.

This reason is the same as the reason for suppressing leakage current and obtaining uniform surface light emission by having a buffer layer formed by applying a solution containing an organic compound in the first organic light-emitting device of the present invention described above. Do.

The nitrogen-containing film contains a nitrogen element and a carbon element as elements constituting the film,

The ratio of nitrogen and carbon atoms constituting the film

Number of nitrogen atoms/(number of nitrogen atoms + number of carbon atoms)> 1/8

It is desirable to satisfy the relationship of.

As described above, when the ratio of the number of nitrogen atoms in the nitrogen-containing film is high, the total number of metal-nitrogen bonds increases, and as a result, the electron injection characteristics become higher due to stronger polarization. The number of nitrogen atoms/(number of nitrogen atoms + number of carbon atoms) in the nitrogen-containing film is more preferably greater than 1/5.

The ratio of the nitrogen element and the carbon element in the nitrogen-containing film can be measured by photoelectron spectroscopy (XPS).

The method of decomposing the nitrogen-containing compound is not particularly limited as long as the nitrogen-containing film of the above (3) and (4) is formed by decomposing the nitrogen-containing compound on the metal oxide layer, but the nitrogen-containing compound is decomposed by heating. It is preferably formed by doing.

When the nitrogen-containing compound is decomposed by heating, the bond between the metal atom and the nitrogen atom in the metal oxide layer is strengthened, whereby the organic electroluminescent device exhibits high driving stability over a longer period of time.

Therefore, the nitrogen-containing film is most preferably formed by a method of forming by applying a solution containing a nitrogen-containing compound on a metal oxide layer and then decomposing the nitrogen-containing compound by heating, and is formed by such a method. By doing so, the effect of suppressing the leakage current, obtaining uniform surface light emission, and the effect of exhibiting high driving stability of the organic electroluminescent element over a longer period of time can be obtained.

As a method of manufacturing such a HOILED device, that is, a method of manufacturing an organic electroluminescent device having a structure in which a plurality of layers are stacked between an anode and a cathode formed on a substrate, the manufacturing method includes: , A process of applying a solution containing a nitrogen-containing compound, and heating at a temperature at which the nitrogen-containing compound is decomposed to produce a layer made of the nitrogen-containing film of the present invention. It is also one of the present invention.

It is preferable to perform heat treatment for decomposing the nitrogen-containing compound in the atmosphere. By carrying out in the atmosphere, the decomposition of the nitrogen-containing compound can be sufficiently promoted, and the organic electroluminescent device can exhibit higher driving stability over a long period of time.

The temperature of the heat treatment for decomposing the nitrogen-containing compound is preferably 80 to 200°C, and the time is preferably 1 to 30 minutes.

The temperature and time of the heat treatment may be appropriately set in the above range according to the kind of the nitrogen-containing compound. For example, in the case of using a polymer having the following polyalkyleneimine structure in the main chain skeleton as the nitrogen-containing compound, the higher the molecular weight of the polymer, the higher the decomposition temperature, so in consideration of the molecular weight of the polymer, in the examples described later With reference to the heat treatment conditions of, the temperature and time of the heat treatment can be appropriately set.

Whether or not the nitrogen-containing compound is decomposing can be confirmed by X-ray photoelectron spectroscopy (XPS) measurement.

The nitrogen-containing film may be formed by performing a step of decomposing a nitrogen-containing compound on the metal oxide layer, followed by washing the surface of the film with an organic solvent such as ethanol or methoxyethanol.

As the nitrogen-containing compound, for example, pyrrolidones such as polyvinylpyrrolidone, pyrrols such as polypyrrole, or anilines such as polyaniline, or pyridines such as polyvinylpyridine, similarly, pyrrolidines, already Compounds having a nitrogen-containing heterocycle, such as dazoles, piperidines, pyrimidines, and triazines, and amine compounds are mentioned. Among them, compounds with a large nitrogen content are preferred, and polyamines or triazine ring-containing compounds are preferred.

Since the ratio of the number of nitrogen atoms to the total number of atoms constituting the compound is high, polyamines are suitable in that the organic electroluminescent device has high electron injection properties and driving stability.

As polyamines, those capable of forming a layer by application are preferable, and a low molecular weight compound or a high molecular compound may be used. As the low molecular weight compound, a polyalkylene polyamine such as diethylenetriamine is preferably used, and as a polymer compound, a polymer having a polyalkyleneimine structure is preferably used. Polyethyleneimine is particularly preferred.

In addition, the low molecular weight compound here means a compound which is not a high molecular compound (polymer), and does not necessarily mean a low molecular weight compound.

Among the polyamines, it is one of the preferred embodiments of the present invention to use a polymer having a linear structure having a polyalkyleneimine structure in the main chain skeleton.

Among polyamines, by using a polymer having such a structure, the device driving stability and device life are more excellent. This is presumed to be due to the fact that the polymer having such a polyalkyleneimine structure in the main chain skeleton is solid in that it has a linear structure, and thus stably exists in the device.

The nitrogen-containing film formed on the metal oxide layer from a polymer of a linear structure having such a polyalkyleneimine structure in the main chain skeleton becomes the nitrogen-containing film of the above (1).

In addition, polymers of a linear structure having a polyalkyleneimine structure in the main chain skeleton may be those in which most of the polyalkyleneimine structures forming the main chain skeleton are linearly connected, even if they have a branched structure in some parts. do. Preferably, 80% or more of the polyalkyleneimine structures forming the main chain skeleton are linearly linked, more preferably, 90% or more are linearly linked, and still more preferably 95%. The above is a linear connection, and most preferably, 100% of the polyalkyleneimine structure forming the main chain skeleton is linearly connected.

It is preferable that the polyalkyleneimine structure of the polymer having a polyalkyleneimine structure is a structure formed by an alkyleneimine having 2 to 4 carbon atoms. More preferably, it is a structure formed of an alkyleneimine having 2 or 3 carbon atoms.

The polymer having a polyalkyleneimine structure may be one having a polyalkyleneimine structure in the main chain skeleton, or may be a copolymer having a structure other than a polyalkyleneimine structure.

When the polymer having a polyalkyleneimine structure has a structure other than a polyalkyleneimine structure, as a monomer that becomes a raw material for a structure other than the polyalkyleneimine structure, for example, ethylene, propylene, butene, acetylene, acrylic acid , Styrene, or vinyl carbazole, and one or two or more of these may be used. Further, those having a structure in which a hydrogen atom bonded to a carbon atom of these monomers is substituted with another organic group can be preferably used. As another organic group substituted with a hydrogen atom, a C1-C10 hydrocarbon group etc. which may contain at least 1 type of atom selected from the group consisting of an oxygen atom, a nitrogen atom, and a sulfur atom, etc. are mentioned, for example.

The polymer having the polyalkyleneimine structure preferably contains 50% by mass or more of the monomer forming the polyalkyleneimine structure in 100% by mass of the monomer component forming the main chain skeleton of the polymer. More preferably, it is 66 mass% or more, More preferably, it is 80 mass% or more. Most preferably, the monomer forming the polyalkyleneimine structure is 100% by mass, that is, the polymer having the polyalkyleneimine structure is a homopolymer of polyalkyleneimine.

It is preferable that the polymer having a polyalkyleneimine structure has a weight average molecular weight of 100000 or less. By forming a layer by performing heat treatment at a temperature at which the polymer decomposes using such a weight average molecular weight, the organic electroluminescent device can be made more excellent in driving stability. More preferably, it is 10000 or less, and still more preferably, it is 100-1000. Moreover, when the polymer having a polyalkyleneimine structure is a polymer having the above-described linear structure, the weight average molecular weight of the polymer is more preferably 250000 or less, and still more preferably 10000 to 50000.

The weight average molecular weight can be determined by GPC (gel permeation chromatography) measurement under the following conditions.

Measuring equipment: Waters Alliance (2695) (brand name, manufactured by Waters)

Molecular weight column: TSKguard column α, TSKgel α-3000, TSKgel α-4000, TSKgel α-5000 (all manufactured by Tosoh Corporation) are connected in series.

Eluent: A solution of 14304 g of 100 mM boric acid aqueous solution, 96 g of 50 mM sodium hydroxide aqueous solution and 3600 g of acetonitrile

Standard substance for calibration curve: Polyethylene glycol (manufactured by Tosoh Corporation)

Measurement method: The object to be measured is dissolved in an eluent so that the solid content is about 0.2% by mass, filtered through a filter as a measurement sample, and the molecular weight is measured.

As the triazine ring-containing compound, melamine or guanamine is suitable as a nitrogen-containing cyclic compound, in which the ratio of the number of nitrogen atoms to the total number of atoms constituting the compound is high and rigid. When a film made of melamine or guanamine is formed on the metal oxide layer, it becomes the high nitrogen-containing film of the above (2).

Examples of the triazine ring-containing compound include guanamines such as melamine and benzoguanamine/acetoguanamine, as well as compounds having a melamine/guanamine skeleton such as methylolated melamine and guanamine, and melamine resin/guanamine resin One type or two or more types can be used, but among these, melamine is preferable because the ratio of nitrogen atoms to all atoms constituting the compound is high.

In addition, as the compound or amine compound having a nitrogen-containing heterocycle, a polymer having a repeating unit of a structure represented by the following formulas (39) to (47), triethylamine of formula (48), ethylenediamine of formula (49) Also can be used preferably.

[Chemical Formula 46-1]

[Chemical Formula 46-2]

Further, when these nitrogen-containing compounds are decomposed on the metal oxide layer, the nitrogen-containing film of (3) or the high nitrogen-containing film of (4) is obtained. As the nitrogen-containing compound, it is considered that by using a compound having a high nitrogen-containing ratio such as polyamines or triazine ring-containing compounds, the decomposition product of the nitrogen-containing compound can be more densely deposited on the metal oxide layer. Such a nitrogen-containing thin film on a metal oxide is also one of the inventions of this patent. The nitrogen-containing thin film will be described later.

The average thickness of the nitrogen-containing film in the present invention is 3 to 150 nm. If the nitrogen-containing film has such an average thickness, the effect of having the nitrogen-containing film described above can be satisfactorily exhibited. It is preferable that the average thickness of the nitrogen-containing film is 5 to 100 nm. More preferably, it is 5-50 nm. In particular, in the case of a nitrogen-containing film formed by decomposition of a nitrogen-containing compound, it is preferably 5 to 100 nm, more preferably 5 to 50 nm.

The average thickness of the nitrogen-containing film can be measured at the time of film formation using a contact step gauge. When measuring an ultra-thin film, the contact-type step meter greatly depends on the measurement environment, and the deviation of the measured value increases. Therefore, when measuring the average thickness in this patent, it is determined by the average value of a plurality of measurements.

The third organic electroluminescent device of the present invention has an anode and a cathode, one layer or a plurality of organic compound layers sandwiched between the anode and the cathode, and a metal oxide layer between the cathode and the organic compound layer, and It is preferable to have a layer made of the nitrogen-containing film of the present invention between the metal oxide layer and the organic compound layer. Here, the organic compound layer is a layer including a light emitting layer and, if necessary, an electron transport layer or a hole transport layer.

Among them, the third organic electroluminescent device of the present invention is an organic-inorganic hybrid type organic electroluminescent device having a cathode formed adjacent to a substrate and having a metal oxide layer between the anode and the cathode, and has a light emitting layer and an anode. , It is preferable that the device has an electron injection layer between the cathode and the light emitting layer, and an electron transport layer, if necessary, and a hole transport layer and/or a hole injection layer between the anode and the light emitting layer. The third organic electroluminescent device of the present invention may have another layer between each of these layers, but it is preferable that it is an element composed of only each of these layers. That is, it is preferable that each layer of a cathode, an electron injection layer, an electron transport layer, a light emitting layer, a hole transport layer and/or a hole injection layer, and an anode is stacked adjacent to each other in this order, if necessary. In addition, each of these layers may consist of one layer or may consist of two or more layers.

As described above, since the nitrogen-containing film is excellent in electron injection properties, it is preferably used on the electron injection side, that is, the cathode side. In addition, the metal oxide layer is preferably laminated as a part of the cathode or one layer of the electron injection layer, and/or a part of the anode or one layer of the hole injection layer, as described later.

In the organic electric field device of the above configuration, when the device does not have an electron transport layer, the electron injection layer and the light emitting layer are adjacent. In addition, when the device has only one of the hole transport layer and the hole injection layer, the one layer is stacked adjacent to the light emitting layer and the anode, and when the device has both a hole transport layer and a hole injection layer, the light emitting layer, These layers are adjacent to each other in the order of a hole transport layer, a hole injection layer, and an anode.

In the third organic electroluminescent device of the present invention, as a material for forming the light-emitting layer, any compound commonly used as a material for the light-emitting layer may be used, a low-molecular compound or a high-molecular compound may be used, or a mixture of these may be used.

In addition, in the present invention, the low molecular weight material means a material other than a polymer material (polymer), and does not necessarily mean an organic compound having a low molecular weight.

As a polymer material for forming the light emitting layer, for example, in the first organic light emitting device of the present invention described above, among the compounds described as examples of the organic compound forming the buffer layer, other than polyethyleneimine (PEI) Compounds, and further, the boron compound-based polymer materials described in Japanese Patent Application No. 2010-230995 and Japanese Patent Application No. 2011-6457, etc. are mentioned.

As the low molecular weight material for forming the light emitting layer, for example, in the first organic light emitting device of the present invention described above, the same low molecular weight compound that can be used as a material for the light emitting layer can be used.

The average thickness of the light-emitting layer is not particularly limited, but it is preferably the same as the average thickness of the light-emitting layer of the first organic light-emitting device of the present invention described above.

When the third organic electroluminescent device of the present invention has an electron transport layer, as the material, any compound commonly used as a material for the electron transport layer may be used, and these may be mixed and used.

Examples of the compound that can be used as the material for the electron transport layer include the same compound as the low molecular compound that can be used as the material for the electron transport layer in the first organic light-emitting device of the present invention described above, and the preferred compounds are also the same.

When the third organic electroluminescent device of the present invention has a hole transport layer, various p-type polymer materials and various p-type low molecular materials may be used alone or in combination as the hole-transporting organic material used as the hole transport layer.

As a p-type polymer material (organic polymer), for example, polyarylamine, fluorene-arylamine copolymer, fluorene-bithiophene copolymer, poly(N-vinylcarbazole), polyvinylpyrene, polyvinyl Anthracene, polythiophene, polyalkylthiophene, polyhexylthiophene, poly(p-phenylenevinylene), polytinylenevinylene, pyreneformaldehyde resin, ethylcarbazole formaldehyde resin, or derivatives thereof, and the like. have.

Moreover, these compounds can also be used as a mixture with another compound. As an example, as a mixture containing polythiophene, poly(3,4-ethylenedioxythiophene/styrenesulfonic acid) (PEDOT/PSS) etc. are mentioned.

Examples of the p-type low molecular weight material include compounds similar to those of the low molecular weight compound used as the material for the hole transport layer in the first organic light emitting device of the present invention described above.

When the third organic electroluminescent device of the present invention has an electron transport layer or a hole transport layer, the average thickness of these layers is not particularly limited, but the electron transport layer or hole transport layer in the first organic light emitting device of the present invention described above. It is preferably the same as the average thickness of.

The average thickness of the electron transporting layer and the hole transporting layer can be measured by a crystal oscillator film thickness meter in the case of a low molecular weight compound and by a contact-type step meter in the case of a high molecular compound.

The third organic electroluminescent device of the present invention has a metal oxide layer between the cathode and the light emitting layer, the anode to the light emitting layer, or both, but the light emitting layer to the anode between the cathode and the light emitting layer. It is preferable to have a metal oxide layer in both sides. A preferred device configuration of the third organic electroluminescent device of the present invention, wherein the metal oxide layer between the cathode and the light-emitting layer is a first metal oxide layer, and the metal oxide layer between the anode and the light-emitting layer is the second metal oxide layer To illustrate an example, a cathode, a first metal oxide layer, a layer comprising a nitrogen-containing film, a light emitting layer, a hole transport layer, a second metal oxide layer, and an anode are stacked adjacent to each other in this order. Further, an electron transport layer may be provided between the layer made of the nitrogen-containing film and the light-emitting layer as necessary. The importance of the metal oxide layer is that the first metal oxide layer is high, and the second metal oxide layer can be substituted with an extremely deep organic material such as HATCN or F ₄ TCNQ.

In the first metal oxide layer, the material of the second metal oxide layer, the structure of the layer, and the average thickness of the layer are the same as those in the first organic light-emitting device of the present invention described above.

In the third organic light-emitting device of the present invention, the material and average thickness of the anode and the cathode are the same as those in the first organic light-emitting device of the present invention described above.

The third organic electroluminescent device of the present invention is the organic electroluminescent device of the present invention, wherein the buffer layer is made of a nitrogen-containing film and has an average thickness of 3 to 150 nm, whereby the organic electroluminescent device has luminous efficiency and It becomes possible to make it excellent in life.

As a method of manufacturing an organic-inorganic hybrid type organic electroluminescent device of the third preferred embodiment of the present invention, that is, an organic electroluminescent device having a structure in which a plurality of layers are stacked, the manufacturing method is organic electroluminescence A step of laminating each layer constituting an organic electroluminescent element so that the element has a layer consisting of a metal oxide layer between the first electrode and the second electrode, and a nitrogen-containing film stacked on the metal oxide layer in this order Including, and the lamination process comprises a step of forming a nitrogen-containing film having an average thickness of 3 to 150 nm, the method for manufacturing an organic electroluminescent device of the third preferred embodiment of the present invention is also one of the present invention. .

The method for manufacturing an organic electroluminescent device of the third preferred embodiment of the present invention may include other steps as long as it includes the steps described above, and a layer other than a layer consisting of a metal oxide layer and a nitrogen-containing film is formed. The forming process may be included. In addition, the material for forming each layer of the organic electroluminescent device, the formation method, the organic compound, the solvent used to prepare a solution containing the organic compound, and the thickness of each layer are the third organic electroluminescent device of the present invention. It is the same as and preferred is the same.

In the organic electroluminescent device of the present invention, a method for forming a film of a layer formed from an organic compound is not particularly limited, and various methods can be appropriately used according to the characteristics of the material, but when it can be applied as a solution In the first organic light-emitting device of the present invention described above, a film can be formed using various coating methods for forming the buffer layer. Among these, the spin coating method and the slit coating method are preferable in that the film thickness can be more easily controlled. When not coated or the solvent solubility is low, a vacuum evaporation method, an ESDUS (Evaporative Spray Deposition from Ultra-dilute Solution) method, etc. are mentioned as preferable examples.

When the layer formed from the organic compound is formed by applying an organic compound solution, as a solvent used to dissolve the organic compound, a solution containing an organic compound in the first organic light emitting device of the present invention described above is used. The same solvent as the solvent used for preparation can be used, but among them, a non-polar solvent is preferable as a solvent, for example, xylene, toluene, cyclohexylbenzene, dihydrobenzofuran, trimethylbenzene, tetramethylbenzene, etc. Aromatic hydrocarbon solvents, aromatic heterocyclic compound solvents such as pyridine, pyrazine, furan, pyrrole, thiophene, methylpyrrolidone, and aliphatic hydrocarbon solvents such as hexane, pentane, heptane, and cyclohexane. These can be used alone or in combination.

When polyamines are used as the nitrogen-containing compound, water or lower alcohol can be used as a solvent for a solution containing the nitrogen-containing compound. As the lower alcohol, it is preferable to use an alcohol having 1 to 4 carbon atoms, and methanol, ethanol, propanol, ethoxyethanol, methoxyethanol, and the like can be used alone or in combination.

The cathode, anode, and oxide layer are the same as the method of forming the first, second metal oxide layer, second electrode, light emitting layer, hole transport layer, and electron transport layer in the first organic electroluminescent device described above. It can be formed by Bonding of metal foil can also be used for formation of an anode and a cathode. It is preferable to select these methods according to the characteristics of the material of each layer, and the manufacturing method may be different for each layer. Among these, the second metal oxide layer is more preferably formed using a vapor phase film production method. According to the vapor phase film production method, the organic compound layer can be formed cleanly and in good contact with the anode without damaging the surface, and as a result, the effect of having the second metal oxide layer as described above becomes more remarkable.

For reasons of further improving the characteristics of the third organic electroluminescent device of the present invention, for example, a hole blocking layer, an electronic device layer, or the like may be provided as necessary. As a material for forming these layers, a material commonly used for forming these layers can be used, and a layer can be formed by a method commonly used for forming these layers.

The third organic electroluminescent device of the present invention does not require strict sealing compared to an organic electroluminescent device in which all layers constituting the device are made of an organic compound, but may be sealed if necessary. As a sealing process, a conventional method can be used suitably. For example, a method of bonding a sealing container in an inert gas, a method of directly forming a sealing film on an organic EL element, or the like can be mentioned. In addition to these, a method of sealing a moisture absorbing material may be used in combination.

The third organic electroluminescent device of the present invention is an organic electroluminescent device having an inverted structure formed by adjacent cathodes on a substrate. The third organic electroluminescent device of the present invention may be of a top emission type in which light is extracted on the side opposite to the side with the substrate, or may be of a bottom emission type in which light is extracted on the side with the substrate.

The material of the substrate and the average thickness are the same as those of the first organic electroluminescent element described above.

The organic electroluminescent device of the present invention, as described above, has a layer made of a nitrogen-containing film on the metal oxide layer, thereby improving electron injection characteristics, resulting in excellent luminous efficiency, and driving stability and device life of the device. It is also excellent.

Such an effect of improving the electron injection characteristics is not limited to the organic electroluminescent element, but also in other optoelectronic devices such as solar cells and organic semiconductors, which is beneficial for contributing to performance improvement. A nitrogen-containing film that contributes to improving the performance of such an optoelectronic device, that is,

As a nitrogen-containing film, the film is formed on a substrate containing a metal and is formed of a solid nitrogen-containing compound, or contains a nitrogen element and a carbon element as elements constituting the film, and a nitrogen atom constituting the film The abundance ratio of and carbon atoms is the number of nitrogen atoms/(number of nitrogen atoms + number of carbon atoms)> 1/8

Another aspect of the present invention is a nitrogen-containing film which satisfies the relationship of.

The preferred form and manufacturing method of the nitrogen-containing film of the present invention are the same as the layer made of the nitrogen-containing film in the organic electroluminescent device of the present invention described above.

The electroluminescent device of the present invention can emit light by applying a voltage (usually 15 volts or less) between the anode and the cathode. Usually, a DC voltage is applied, but an AC component may be included.

The organic electroluminescent device of the present invention is an organic-inorganic hybrid-type device, and is capable of suppressing crystallization of a low-molecular compound peculiar to an organic-inorganic hybrid-type device, suppressing leakage current, and achieving uniform surface light emission. It can be preferably used as a material for a display device or a lighting device.

The organic electroluminescent device of the present invention can change the luminous color by appropriately selecting the material for the organic compound layer, and it is also possible to obtain a desired luminous color by using a color filter or the like together. Therefore, it can be suitably used as a light emitting portion of a display device or a lighting device. In particular, a display device in combination with an oxide TFT is preferable from the characteristic of an inverse structure.

Such a display device formed using the organic electroluminescent device of the present invention is another aspect of the present invention. In addition, a lighting device formed by using the organic electroluminescent device of the present invention is another aspect of the present invention.

The first organic electroluminescent device of the present invention has the above-described configuration, and can achieve suppression of leakage current and uniform surface light emission.

Further, since the second organic electroluminescent device of the present invention has a buffer layer, it has a longer luminous life than that of the conventional organic-inorganic hybrid organic electroluminescent device, and the buffer layer contains a reducing agent, so that luminous efficiency is excellent. The organic-inorganic hybrid type organic electroluminescent device has manufacturing advantages such as reducing the need to strictly seal each layer like an organic electroluminescent device in which each layer constituting the organic electroluminescent device is composed of organic materials. , It has such advantages, excellent light-emitting lifetime, light-emitting characteristics such as light-emitting efficiency.

In addition, the third organic electroluminescent device of the present invention is an organic electroluminescent device having an inverted structure of an organic-inorganic hybrid type that has the above-described configuration and does not require strict sealing. It has high driving stability with excellent repetition stability and uniformity of light emission, and the life of the device is long.

The organic electroluminescent device of the present invention has such excellent properties, and can be preferably used as a material for a display device or a lighting device.

1 is a SEM photograph when a solution obtained by dissolving a boron-containing compound 1 in THF is applied to a transparent glass substrate with ITO.
2 is a graph showing voltage-current efficiency characteristics of organic electroluminescent devices prepared in Example 1 and Comparative Example 1. FIG.
3 is a graph showing voltage-current efficiency characteristics of organic electroluminescent devices manufactured in Examples 2 to 4 and Comparative Example 2. FIG.
4 is a graph showing voltage-current efficiency characteristics of organic electroluminescent devices prepared in Example 5 and Comparative Example 2. FIG.
5 is a graph showing voltage-current efficiency characteristics of organic electroluminescent devices prepared in Example 6 and Comparative Example 3. FIG.
6 is a graph showing voltage-luminance characteristics of organic electroluminescent devices manufactured in Example 7 and Comparative Example 4. FIG.
7 is a graph showing current density-current efficiency characteristics of organic electroluminescent devices manufactured in Example 7 and Comparative Example 4. FIG.
8 is a graph showing voltage-luminance characteristics of organic electroluminescent devices manufactured in Example 8 and Comparative Example 5. FIG.
9 is a graph showing current density-current efficiency characteristics of organic electroluminescent devices manufactured in Example 8 and Comparative Example 5. FIG.
10 is a graph showing voltage-luminance characteristics of organic electroluminescent devices prepared in Examples 9 and 10 and Comparative Example 6. FIG.
11 is a graph showing current density-current efficiency characteristics of organic electroluminescent devices prepared in Examples 9 and 10 and Comparative Example 6. FIG.
12 is a graph showing voltage-luminance characteristics of organic electroluminescent devices prepared in Example 11 and Comparative Example 7. FIG.
13 is a graph showing current density-current efficiency characteristics of organic electroluminescent devices prepared in Example 11 and Comparative Example 7. FIG.
14 is a graph showing voltage-luminance characteristics of organic electroluminescent devices manufactured in Example 12 and Comparative Example 8. FIG.
15 is a graph showing current density-current efficiency characteristics of organic electroluminescent devices prepared in Examples 12 and 13 and Comparative Example 8. FIG.
16 is a schematic diagram showing an example of a stacked structure of a third organic electroluminescent device according to the present invention.
17A is a view showing measurement results of (a) voltage-current density/luminance characteristics, and (b) current density-current efficiency characteristics of the organic electroluminescent device prepared in Example 14;
17B shows the continuous driving characteristics of the organic electroluminescent device prepared in Example 14 under (c-1) constant current density (equivalent to 100 cd/m 2 ), and (c-2) constant current density (1000 cd/m 2 ). It is a figure showing the measurement result of the continuous drive characteristic in (equivalent).
18 is a diagram showing measurement results of (a) voltage-current density/luminance characteristics, and (b) current density-current efficiency characteristics of the organic electroluminescent device prepared in Comparative Example 9. FIG.
19A is a view showing measurement results of (a) voltage-current density/luminance characteristics, and (b) current density-current efficiency characteristics of the organic electroluminescent device prepared in Example 15;
19B is a diagram showing the measurement results of the continuous driving characteristics under (c-2) constant current density (equivalent to 1000 cd/m 2) of the organic electroluminescent device prepared in Example 15. FIG.
20A is a diagram showing measurement results of (a) voltage-current density/luminance characteristics, and (b) current density-current efficiency characteristics of the organic electroluminescent device prepared in Example 16;
20B is a diagram showing the measurement results of the continuous driving characteristic under (c-2) constant current density (equivalent to 1000 cd/m 2) of the organic electroluminescent device prepared in Example 16. FIG.
Fig. 21 is a measurement result of (a) voltage-current density/luminance characteristics, and (c-1) continuous driving characteristics under a constant current density (equivalent to 100 cd/m2) of the organic electroluminescent device prepared in Example 17. It is a view showing.
22A is a diagram showing measurement results of (a) voltage-current density/luminance characteristics, and (b) current density-current efficiency characteristics of the organic electroluminescent device prepared in Example 18;
22B is a diagram showing the measurement results of the continuous driving characteristics under a constant current density (equivalent to 100 cd/m 2) of the organic electroluminescent element (c-1) fabricated in Example 18. FIG.
23A is a diagram showing measurement results of (a) voltage-current density/luminance characteristics, and (b) current density-current efficiency characteristics of the organic electroluminescent device prepared in Example 19;
23B is a diagram showing the measurement results of the continuous driving characteristics under (c-1) constant current density (equivalent to 100 cd/m2) of the organic electroluminescent device prepared in Example 19;
24A is a view showing measurement results of (a) voltage-current density/luminance characteristics, and (b) current density-current efficiency characteristics of the organic electroluminescent device prepared in Example 20;
24B is a diagram showing the measurement results of the continuous driving characteristics under (c-2) constant current density (equivalent to 1000 cd/m2) of the organic electroluminescent device prepared in Example 20;
25A is a view showing measurement results of (a) voltage-current density/luminance characteristics, and (b) current density-current efficiency characteristics of the organic electroluminescent device prepared in Example 21. FIG.
Fig. 25B is a diagram showing the measurement results of the continuous driving characteristics under (c-2) constant current density (equivalent to 1000 cd/m2) of the organic electroluminescent device prepared in Example 21.
26A is a diagram showing measurement results of (a) voltage-current density/luminance characteristics, and (b) current density-current efficiency characteristics of the organic electroluminescent device prepared in Example 22;
26B is a diagram showing the measurement results of the continuous driving characteristics under (c-1) constant current density (equivalent to 100 cd/m 2) of the organic electroluminescent device prepared in Example 22. FIG.
27A is a view showing measurement results of (a) voltage-current density/luminance characteristics, and (b) current density-current efficiency characteristics of the organic electroluminescent device prepared in Example 23;
Fig. 27B is a diagram showing the measurement results of the continuous driving characteristics under (c-2) constant current density (equivalent to 1000 cd/m2) of the organic electroluminescent device prepared in Example 23.
28 is a diagram showing the results of photoelectron spectroscopy measurement of the nitrogen-containing film produced in Production Example 1. FIG.
29 is a diagram showing the result of photoelectron spectroscopy measurement of the nitrogen-containing film produced in Production Example 2. FIG.
FIG. 30 is a diagram showing the results of photoelectron spectroscopy measurement of the nitrogen-containing film produced in Production Example 3. FIG.
31 is a diagram showing the result of photoelectron spectroscopy measurement of the nitrogen-containing film produced in Production Example 4. FIG.
Fig. 32 is a diagram showing measurement results of (a) voltage-current density/luminance characteristics, and (b) current density-current efficiency characteristics of the organic electroluminescent device prepared in Example 24-1.
33 is a diagram showing measurement results of (a) voltage-current density/luminance characteristics, and (b) current density-current efficiency characteristics of the organic electroluminescent device prepared in Example 24-2.
34 is a diagram showing measurement results of (a) voltage-current density/luminance characteristics, and (b) current density-current efficiency characteristics of the organic electroluminescent device prepared in Example 25;
FIG. 35 is a diagram showing measurement results of (a) voltage-current density/luminance characteristics, and (b) current density-current efficiency characteristics of the organic electroluminescent device prepared in Comparative Example 10. FIG.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In addition, unless otherwise specified, "part" shall mean "part by weight" and "%" shall mean "mass%".

In the following examples, various physical properties were measured as follows.

< ¹ H-NMR>

The obtained boron-containing compound was used as a solution of deuterated chloroform, and was measured using a high-resolution nuclear magnetic resonance apparatus (product name "Gemini 2000"; 300 MHz, manufactured by Varian, Inc.). The chemical shift was recorded as one millionth (ppm; δ scale) on the low-length side from tetramethylsilane, and the hydrogen nuclei (δ0.00) of tetramethylsilane was referred to.

< ¹³ C-NMR>

The obtained boron-containing compound was used as a solution of deuterated chloroform, and was measured using a high-resolution nuclear magnetic resonance apparatus (product name "Gemini 2000"; 75 MHz, manufactured by Varian, Inc.). The chemical shift was recorded as 1 millionth (ppm; δ scale) on the low-length side from tetramethylsilane, and carbon nuclei (CDCl ₃ : δ = 77.0, CD ₂ Cl ₂ : δ = 53.1, CD _{3 in the} NMR solvent) CN: δ = 1.32, DMSO-d ₆ : δ = 39.52) were referred to.

< ¹¹ B-NMR>

The obtained boron-containing compound was used as a solution of deuterated chloroform, and was measured using a high-resolution nuclear magnetic resonance apparatus (product name "Mercury-400"; 128 MHz, manufactured by Varian, Inc.). The chemical shift was recorded as one millionth (ppm; δ scale) based on the boron nuclei (δ = 0.00) of the boron trifluoride-diethyl ether complex.

<High-resolution mass spectrometry>

It was measured by an electron ionization method (EI) or a high-speed electron bombardment method (FAB) using a high-resolution mass spectrometer (product names "JMS-SX101A", "JMS-MS700", "JMS-BU250", manufactured by Nippon Electronics Co., Ltd.) .

<weight average molecular weight>

The weight average molecular weight was measured by the following apparatus and measurement conditions by gel permeation chromatography (GPC apparatus, developing solvent; chloroform) in terms of polystyrene.

High-speed GPC device: HLC-8220GPC (manufactured by Tosoh Corporation)

Measuring conditions:

Developing solvent chloroform

Column TSK-gel GMHXL x 2

Eluent flow rate 1 ml/min

Column temperature 40°C

<The first organic electroluminescent device of the present invention>

(Synthesis Example 1)

(Synthesis of 2,7-bis(3-dibenzoboroyl-4-pyridylphenyl)-9,9'-spirofluorene)

In a 100 ml two-necked flask, 2-(dibenzoboroylphenyl)-5-bromopyridine (2.6 g, 6.5 mmol), 2,7-bis(4,4,5,5-tetramethyl- 1,3,2-dioxabororanyl)-9,9'-spirofluorene (1.5 g, 2.7 mmol), Pd(P ^t Bu ₃ ) ₂ (170 mg, 0.32 mmol) was added. The inside of the flask was placed under a nitrogen atmosphere, and THF (65 ml) was added and stirred.

To this, a 2M aqueous tripotassium phosphate solution (11 ml, 22 mmol) was added, followed by heating and stirring at 70°C while refluxing. After 12 hours, it was cooled to room temperature, the reaction solution was transferred to a separatory funnel, water was added, and the mixture was extracted with ethyl acetate. The organic layer was washed with 3N hydrochloric acid, water and saturated brine, and then dried over magnesium sulfate. The filtered filtrate was concentrated, and the obtained solid was washed with methanol, and 2,7-bis(3-dibenzoboroyl-4-pyridylphenyl)-9,9'-spirofluorene (boron-containing compound 1) ) Was obtained in a yield of 47% (1.2 g, 1.3 mmol).

Its properties were as follows.

In addition, the reaction of Synthesis Example 1 is represented by the following reaction formula.

[Chemical Formula 47]

About the boron-containing compound 1 synthesized in Synthesis Example 1, the device physical properties shown below were evaluated.

<Application film composition>

When the solution obtained by dissolving the boron-containing compound 1 in THF was applied to a transparent glass substrate with ITO, a smooth thin film was obtained. The SEM (scanning electron microscope) photograph (magnification: 10000 times) is shown in FIG. 1. From this result, it was demonstrated that the boron-containing compound 1 is a compound capable of producing a coating film from a solution while having a low molecular weight.

(Synthesis Example 2)

In an argon atmosphere, to a dichloromethane solution (0.3 ml) containing 5-bromo-2-(4-bromophenyl)pyridine (94 mg, 0.30 mmol), ethyldiisopropylamine (39 mg, 0.30 mmol) After adding, boron bromide (1.0 M, 0.9 mL, 0.9 mmol) was added at 0°C, followed by stirring at room temperature for 9 hours. After cooling the reaction solution to 0°C, a saturated aqueous potassium carbonate solution was added, followed by extraction with chloroform. The organic layer was washed with saturated brine, dried over magnesium sulfate, and filtered. After concentrating the filtrate with a rotary evaporator, the produced white solid was collected by filtration and washed with hexane to obtain the following formula (50);

[Formula 48]

The boron-containing compound 2 (40 mg, 0.082 mmol) represented by was obtained in a yield of 28%.

Its properties were as follows.

(Synthesis Example 3)

In a nitrogen atmosphere, a diethyl ether solution of pentafluorophenylmagnesium bromide (1 M, 61.2 ml, 70.4 mmol) was cooled to 0°C, and a diethyl ether solution of zinc chloride (1 M, 17 ml, 17 mmol) ) While stirring. After completion of the dropping, it is stirred at room temperature for 1 hour. Toluene solution (80 ml) containing 5-bromo-2-(4-bromo-2-dibromoborylphenyl)pyridine (3.8 g, 8 mmol) represented by the above formula (26) was added thereto, It heated and stirred at 80 degreeC for 15 hours. After cooling to room temperature, the reaction solution was added to ice water, followed by extraction with chloroform. The organic layer was washed with saturated brine, dried over sodium sulfate and filtered. The filtrate was concentrated by a rotary evaporator and then purified by silica gel chromatography (hexane:dichloromethane = 1:1) to obtain the following formula (51);

[Chemical Formula 49]

The boron-containing compound 3 (2.2 g, 4.61 mmol) represented by was obtained in a yield of 58%.

Its properties were as follows.

(Synthesis Example 4)

BC6F5 dibromide (boron-containing compound 3) (337 mg, 0.51 mmol) represented by the above formula (51) and F8 boronic acid diester (292 mg, 0.52 mmol) represented by the following formula (52) were added to toluene (3 mL) and THF. It dissolved in (3 ml) and stirred at room temperature for 10 minutes under an argon atmosphere. A mixed aqueous solution of Aliquat 336 (21 mg), 25% by mass Et ₄ NOH aqueous solution (0.86 ml) and distilled water (0.75 ml) was added thereto, followed by stirring for another 20 minutes at room temperature under an argon atmosphere to complete deaeration. After tetrakistriphenylphosphine palladium (8.9 mg, 0.007 mmol) was added thereto, the mixture was heated and stirred for 48 hours while refluxing at 115°C. For terminal sealing, bromobenzene (105 mg, 0.67 mmol) was added and stirred for 5 hours, and phenylboronic acid (294 mg, 2.41 mmol) was further added and stirred for 5 hours. After standing to cool to room temperature, the reaction solution diluted with toluene was separated and washed once with hydrochloric acid and twice with pure water, and the organic layer was concentrated to about several ml. The concentrated solution was dropped into 300 ml of methanol, stirred for 10 minutes as it was, and the obtained precipitate was collected by filtration. The same purification process was repeated three times in total, and the solid was dried under reduced pressure to obtain a boron-containing polymer F8BC6F5 represented by the following formula (53). The weight average molecular weight of the boron-containing polymer F8BC6F5 was 126000.

[Formula 50]

[Formula 51]

(Production of organic electroluminescent device)

In the following examples, the average thickness of the buffer layer was measured using a stylus-type step meter (product name "Alpha Step IQ", manufactured by KLA Tencor).

(Example 1)

[1] A transparent glass substrate on which a commercially available ITO electrode layer having an average thickness of 0.7 mm was formed was prepared. At this time, the ITO electrode (first electrode) of the substrate was patterned to a width of 2 mm. The substrate was ultrasonically cleaned for 10 minutes each in acetone and isopropanol, and then boiled for 5 minutes in isopropanol. This substrate was taken out in isopropanol, dried by nitrogen blowing, and UV ozone cleaning was performed for 20 minutes.

[2] This substrate was fixed to the substrate holder of a Miratron sputtering apparatus having a zinc metal target. After reducing the pressure to about 1 × 10 ^-4 Pa, it was sputtered while introducing argon and oxygen to prepare a zinc oxide layer having a thickness of about 2 nm. At this time, a metal mask was used in combination to prevent zinc oxide from forming on a part of the ITO electrode for electrode extraction.

[3] A 1% water-ethanol (1:3 by volume ratio) mixed solution of magnesium acetate was prepared. The substrate produced in step [2] was washed again in the same manner as in step [1]. The substrate on which the cleaned zinc oxide thin film was formed was set on a spin coater. A magnesium acetate solution was dripped on this substrate, and it rotated for 60 seconds at 1300 revolutions per minute. A zinc oxide/magnesium oxide layer (first metal oxide layer) was formed by firing this in air with a hot plate set at 400°C for 2 hours.

[4] A 0.2% tetrahydrofuran solution of the boron-containing compound 1 was prepared. The substrate on which the zinc oxide/magnesium oxide thin film produced in step [3] was formed was set on a spin coater. The boron-containing compound 1 solution was dripped on the substrate, and rotated for 30 seconds at 2000 rotations per minute to form a buffer layer made of a boron-containing organic compound. The average thickness of the buffer layer was 5 nm.

[5] The substrate formed up to the layer of the boron-containing organic compound was fixed to the substrate holder of the vacuum vapor deposition apparatus. 4,4'-bis[9-dicarbazolyl]-2,2'-biphenyl (CBP), iridium tris (1-phenylisoquinoline) (Ir(piq) ₃ ), N,N'-di(1 -Naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine (?-NPD) was placed in an alumina crucible, respectively, and set as an evaporation source. The inside of the vacuum evaporation apparatus was reduced to about 1×10 ^-5 Pa, CBP was co-deposited as a host and Ir(piq) ₃ as a dopant at 35 nm to form a light emitting layer. At this time, the dope concentration was set so that Ir(piq) ₃ was 6% by weight with respect to the entire light emitting layer. Next, α-NPD was deposited at 60 nm to form a hole transport layer. Next, after purging with nitrogen once, molybdenum trioxide and gold were put into an alumina crucible and set as an evaporation source. The inside of the vacuum vapor deposition apparatus was reduced to about 1×10 ⁻⁵ Pa, and molybdenum trioxide (second metal oxide layer) was vapor-deposited so as to have a film thickness of 10 nm. Next, gold (second electrode) was vapor-deposited so as to have a film thickness of 50 nm, and an organic electroluminescent element 1-1 was produced. When depositing the second electrode, a vapor deposition mask made of stainless steel was used so that the vapor deposition surface became a band shape having a width of 2 mm. That is, the light emission area of the produced organic electroluminescent element was set to 4 mm 2.

(Comparative Example 1)

Except having omitted the step [4], it carried out similarly to Example 1, and produced the organic electroluminescent element 1-2.

(Example 2)

[1] A transparent glass substrate on which a commercially available ITO electrode layer having an average thickness of 0.7 mm was formed was prepared. At this time, the ITO electrode (first electrode) of the substrate was patterned to a width of 2 mm. The substrate was ultrasonically cleaned for 10 minutes each in acetone and isopropanol, and then boiled for 5 minutes in isopropanol. This substrate was taken out in isopropanol, dried by nitrogen blowing, and UV ozone cleaning was performed for 20 minutes.

[2] This substrate was fixed to the substrate holder of a Miratron sputtering apparatus having a zinc metal target. After reducing the pressure to about 1 × 10 ^-4 Pa, it was sputtered while introducing argon and oxygen to prepare a zinc oxide layer (first metal oxide layer) having a thickness of about 2 nm. At this time, a metal mask was used in combination to prevent zinc oxide from forming on a part of the ITO electrode for electrode extraction.

[3] A 0.2% tetrahydrofuran solution of the boron-containing polymer F8BC6F5 was prepared. The substrate on which the zinc oxide thin film prepared in step [2] was formed was set on a spin coater. A boron-containing polymer F8BC6F5 solution was dripped on this substrate, and rotated for 30 seconds at 2,000 rotations per minute to form a buffer layer made of a boron-containing organic compound. The average thickness of the buffer layer was 10 nm.

[4] The substrate formed up to the layer of the boron-containing organic compound was fixed to the substrate holder of the vacuum vapor deposition apparatus. Tris(8-hydroxyquinolinato)aluminum (Alq ₃ ), N,N'-di(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4,4'- Diamine (?-NPD) was placed in an alumina crucible, respectively, and set as an evaporation source. The inside of the vacuum vapor deposition apparatus was reduced to about 1 × 10 ^-4 Pa, and Alq ₃ was co-deposited at 65 nm to form a light emitting layer. Next, α-NPD was deposited at 60 nm to form a hole transport layer. Next, after purging with nitrogen once, molybdenum trioxide and gold were put into an alumina crucible and set as an evaporation source. The inside of the vacuum vapor deposition apparatus was reduced to about 1×10 ⁻⁴ Pa, and molybdenum trioxide (second metal oxide layer) was vapor-deposited so as to have a film thickness of 10 nm. Next, gold (second electrode) was vapor-deposited so that a film thickness might be 30 nm, and an organic electroluminescent element 1-3 was produced. When depositing the second electrode, a vapor deposition mask made of stainless steel was used so that the vapor deposition surface became a band shape having a width of 2 mm. That is, the light emission area of the produced organic electroluminescent element was set to 4 mm 2.

(Example 3)

A 0.2% tetrahydrofuran solution of the boron-containing polymer F8BC6F5 used in step [3] in Example 2 was a 0.2% xylene solution of commercially available poly(dioctylfluorene-alt-benzothiadiazole) (F8BT) Except having changed to, it carried out similarly, and produced the organic electroluminescent element 1-4. The average thickness of the buffer layer was 10 nm.

(Example 4)

In the same manner as in Example 2 except having changed the 0.2% tetrahydrofuran solution of the boron-containing polymer F8BC6F5 used in step [3] to a commercially available 0.2% xylene solution of poly(dioctylfluorene) (PFO). Thus, an organic electroluminescent element 1-5 was produced. The average thickness of the buffer layer was 10 nm.

(Comparative Example 2)

Except having omitted the step [3], it carried out similarly to Example 2, and produced the organic electroluminescent element 1-6.

(Example 5)

Organic electroluminescent device in the same manner as in Example 2 except that the 0.2% tetrahydrofuran solution of the boron-containing polymer F8BC6F5 used in step [3] was changed to a 1% ethanol solution of polyethyleneimine SP-200 manufactured by Nippon Catalyst Made 1-7. The average thickness of the buffer layer was 10 nm.

(Example 6)

[1] A transparent glass substrate on which a commercially available ITO electrode layer having an average thickness of 0.7 mm was formed was prepared. At this time, the ITO electrode (first electrode) of the substrate was patterned to a width of 2 mm. The substrate was ultrasonically cleaned for 10 minutes each in acetone and isopropanol, and then boiled for 5 minutes in isopropanol. This substrate was taken out in isopropanol, dried by nitrogen blowing, and UV ozone cleaning was performed for 20 minutes.

[2] This substrate was fixed to the substrate holder of a Miratron sputtering apparatus having a titanium metal target. After reducing the pressure to about 1 × 10 ^-4 Pa, it was sputtered while introducing argon and oxygen to prepare a titanium oxide layer (first metal oxide layer) having a thickness of about 2 nm. At this time, a metal mask was used in combination to prevent a titanium oxide film from being formed on a part of the ITO electrode for electrode extraction.

[3] A 0.2% tetrahydrofuran solution of the boron-containing polymer F8BC6F5 was prepared. The substrate on which the titanium oxide thin film produced in step [2] was formed was set on a spin coater. A boron-containing polymer F8BC6F5 solution was dripped on this substrate, and rotated for 30 seconds at 2,000 rotations per minute to form a buffer layer made of a boron-containing organic compound. The average thickness of the buffer layer was 10 nm.

[4] The substrate formed up to the layer of the boron-containing organic compound was fixed to the substrate holder of the vacuum vapor deposition apparatus. Tris(8-hydroxyquinolinato)aluminum (Alq ₃ ), N,N'-di(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4,4'- Diamine (?-NPD) was placed in an alumina crucible, respectively, and set as an evaporation source. The inside of the vacuum vapor deposition apparatus was reduced to about 1 × 10 ^-4 Pa, and Alq ₃ was co-deposited at 65 nm to form a light emitting layer. Next, α-NPD was vapor-deposited at 60 nm to form a hole transport layer. Next, after purging with nitrogen once, molybdenum trioxide and gold were put into an alumina crucible and set as an evaporation source. The inside of the vacuum vapor deposition apparatus was reduced to about 1×10 ⁻⁴ Pa, and molybdenum trioxide (second metal oxide layer) was vapor-deposited so as to have a film thickness of 10 nm. Next, gold (2nd electrode) was vapor-deposited so that the film thickness might be 30 nm, and the organic electroluminescent element 1-8 was produced. When depositing the second electrode, a vapor deposition mask made of stainless steel was used so that the vapor deposition surface became a band shape having a width of 2 mm. That is, the light emission area of the produced organic electroluminescent element was set to 4 mm 2.

(Comparative Example 3)

It carried out similarly to Example 6 except having implemented the process [3b] instead of the process [3], and produced the organic electroluminescent element 1-9.

[3b] A solution obtained by diluting the material F8TES for self-organizing monolayers described in paragraphs [0064] to [0066] of JP 2012-4492 A (Patent Document 5) to 1% with ethanol was prepared. The substrate on which the titanium oxide thin film produced in step [2] was formed was set on a spin coater. A self-organizing monomolecular film material F8TES solution was dripped on this substrate, and it was rotated for 30 seconds at 2000 rotations per minute. Immediately after, it rinsed with ethanol, and ultrasonically cleaned with ethanol for 10 minutes further. After rinsing, immobilization was performed at 90° C. for 10 minutes on a hot plate to form a self-assembled monolayer. The average thickness of the buffer layer was 2 nm. F8TES is a compound of the following formula (54).

[Formula 52]

(Measurement of luminescence characteristics of organic electroluminescent devices)

Voltage application and current measurement were performed to the device using a "2400 type source meter" manufactured by Caseray. The light emission luminance was measured by "LS-100" manufactured by Konica Minolta. Moreover, the uniformity of the light emitting surface was confirmed visually.

The voltage-current efficiency characteristics of the organic electroluminescent devices fabricated in Example 1 and Comparative Example 1 when a DC voltage of 4 V to 10 V is applied in an argon atmosphere is shown in FIG. 2. It can be seen that the device manufactured in Comparative Example 1 has a low current efficiency and a large leakage current. On the other hand, it can be seen that the device fabricated in Example 1 has high current efficiency and suppresses leakage current. In addition, by visual observation, the device fabricated in Example 1 was able to confirm very uniform light emission.

The voltage-current efficiency characteristics of the organic electroluminescent devices fabricated in Examples 2 to 4 and Comparative Example 2 when a DC voltage of 4 V to 15 V is applied in an argon atmosphere is shown in FIG. 3. In addition, the voltage-current efficiency characteristics of the organic electroluminescent devices fabricated in Example 5 and Comparative Example 2 when a DC voltage of 4 V to 15 V is applied in an argon atmosphere is shown in FIG. 4. The device fabricated in Comparative Example 2 had a very large leakage current and did not emit light at all. On the other hand, it can be seen that the devices fabricated in Examples 2 to 5 have high current efficiency and suppress leakage current. Further, by visual observation, the devices fabricated in Examples 2 to 5 were able to confirm very uniform light emission.

Fig. 5 shows the voltage-current efficiency characteristics when a DC voltage of 4 V to 15 V is applied to the organic electroluminescent devices produced in Example 6 and Comparative Example 3 in an argon atmosphere. The device fabricated in Comparative Example 3 had a very large leakage current, and immediately did not emit light at all after emitting light for an instant. On the other hand, it can be seen that the device fabricated in Example 6 has high current efficiency and suppresses leakage current. In addition, by visual observation, the device fabricated in Example 6 was able to confirm very uniform light emission.

From the above, it was confirmed that in the organic-inorganic hybrid type organic electroluminescent device, the leakage current can be suppressed and uniform surface light emission can be achieved by the layer on which the organic compound is coated.

<The second organic electroluminescent device of the present invention>

In the following examples, the average thickness of each layer constituting the organic electroluminescent element was measured using a stylus type step meter (product name "Alpha Step IQ", manufactured by KLA Tencor).

(Production of organic electroluminescent device)

(Example 7)

[1] A transparent glass substrate on which a commercially available ITO electrode layer having an average thickness of 0.7 mm was formed was prepared. At this time, the ITO electrode (first electrode) of the substrate was patterned to a width of 2 mm. The substrate was ultrasonically cleaned for 10 minutes each in acetone and isopropanol, and then boiled for 5 minutes in isopropanol. This substrate was taken out in isopropanol, dried by nitrogen blowing, and UV ozone cleaning was performed for 20 minutes.

[2] This substrate was fixed to the substrate holder of a Miratron sputtering apparatus having a zinc metal target. After reducing the pressure to about 1 × 10 ^-4 Pa, it was sputtered while introducing argon and oxygen to prepare a zinc oxide layer having a thickness of about 2 nm. At this time, a metal mask was used in combination to prevent zinc oxide from forming on a part of the ITO electrode for electrode extraction. A zinc oxide layer (first metal oxide layer) was formed by firing this in air with a hot plate set at 400°C for 1 hour.

[3] 0.2% of the boron-containing compound 1 synthesized in Synthesis Example 1, (4-(1,3-dimethyl-2,3-dihydro-1H-benzoimidazol-2-yl)phenyl)dimethylamine ( A 0.002% 1,2-dichloroethane mixed solution of N-DMBI) was prepared. The substrate on which the zinc oxide thin film prepared in step [2] was formed was set on a spin coater. A mixed solution of boron-containing compound 1 and N-DMBI was dripped on this substrate, and rotated for 30 seconds at 2000 rotations per minute to form a buffer layer containing a boron-containing organic compound. Further, this was annealed for 1 hour with a hot plate set at 100°C in a nitrogen atmosphere. The average thickness of the buffer layer was 10 nm.

[4] The substrate formed up to the layer of the boron-containing organic compound was fixed to the substrate holder of the vacuum vapor deposition apparatus. Bis(10-hydroxybenzo[h]quinolinato)beryllium (Bebq ₂ ), iridium tris (1-phenylisoquinoline) (Ir(piq) ₃ ), N,N'-di(1-naphthyl)- N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine (?-NPD) was placed in an alumina crucible, respectively, and set as a vapor deposition source. The inside of the vacuum vapor deposition apparatus was reduced to about 1×10 ^-5 Pa, Bebq ₂ was co-deposited as a host and Ir(piq) ₃ as a dopant at 35 nm to form a light emitting layer. At this time, the dope concentration was set so that Ir(piq) ₃ was 6% by weight with respect to the entire light emitting layer. Next, α-NPD was vapor-deposited at 60 nm to form a hole transport layer.

[5] Next, after purging with nitrogen once, molybdenum trioxide and gold were put into an alumina crucible and set as an evaporation source. The inside of the vacuum vapor deposition apparatus was reduced to about 1×10 ⁻⁵ Pa, and molybdenum trioxide (second metal oxide layer) was vapor-deposited so as to have a film thickness of 10 nm. Next, gold (2nd electrode) was vapor-deposited so that the film thickness might be 50 nm, and the organic electroluminescent element 2-1 was produced. When depositing the second electrode, a vapor deposition mask made of stainless steel was used so that the vapor deposition surface became a band shape having a width of 2 mm. That is, the light emission area of the produced organic electroluminescent element was set to 4 mm 2.

(Comparative Example 4)

In step [3], in place of the 1,2-dichloroethane mixed solution of 0.2% of boron-containing compound 1 and 0.002% of N-DMBI, a 0.2% 1,2-dichloroethane solution of boron-containing compound 1 was used. Except for that, it carried out similarly to Example 7, and produced the organic electroluminescent element 2-2.

(Example 8)

In step [3], instead of 0.2% of boron-containing compound 1 and 0.002% of 1,2-dichloroethane mixed solution of N-DMBI, 1% of boron-containing compound 1, 1 of 0.01% of N-DMBI, An organic electroluminescent element 2-3 was produced in the same manner as in Example 7 except that the 2-dichloroethane mixed solution was used. The average thickness of the buffer layer was 60 nm.

(Comparative Example 5)

In step [3], 1% of boron-containing compound 1, 1,2-dichloroethane solution was used instead of 1% of boron-containing compound 1 and 0.01% of 0.01% 1,2-dichloroethane mixed solution of N-DMBI Except that, it carried out similarly to Example 8, and produced the organic electroluminescent element 2-4.

(Example 9)

In place of the step [4], an organic electroluminescent element 2-5 was produced in the same manner as in Example 8 except that the step [4b] was performed.

[4b] The substrate formed up to the layer of the boron-containing organic compound was fixed to the substrate holder of the vacuum vapor deposition apparatus. Tris(8-hydroxyquinolinato)aluminum (Alq ₃ ), N,N'-di(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4,4'- Diamine (?-NPD) was placed in an alumina crucible, respectively, and set as an evaporation source. The inside of the vacuum vapor deposition apparatus was reduced to about 1 × 10 ^-4 Pa, and Alq ₃ was deposited at 35 nm to form a light emitting layer. Next, α-NPD was vapor-deposited at 60 nm to form a hole transport layer.

(Example 10)

In step [3], 1% of boron-containing compound 1, 1% of 0.05% of N-DMBI, instead of 1% of boron-containing compound 1 and 0.01% 1,2-dichloroethane mixed solution of N-DMBI, An organic electroluminescent element 2-6 was produced in the same manner as in Example 7 except that a 2-dichloroethane mixed solution was used. The average thickness of the buffer layer was 60 nm.

(Comparative Example 6)

An organic electroluminescent element 2-7 was produced in the same manner as in Comparative Example 5 except that the process [4b] was performed instead of the process [4].

(Example 11)

In step [3], instead of 1% of boron-containing compound 1 and 0.01% of 0.01% 1,2-dichloroethane mixed solution of N-DMBI, commercially available poly(dioctylfluorene-alt-benzothiadiazole) An organic electroluminescent element 2-8 was produced in the same manner as in Example 9 except that 1% of (F8BT) and 0.01% of N-DMBI mixed solution of tetrahydrofuran were used.

(Comparative Example 7)

In step [3], it carried out similarly to Example 10 except having used 1% tetrahydrofuran solution of F8BT in place of 1% of F8BT and 0.01% tetrahydrofuran mixed solution of N-DMBI, and organic electric field Light-emitting element 2-9 was produced.

(Example 12)

It carried out similarly to Example 9 except having implemented the process [3b] instead of the process [3], and produced the organic electroluminescent element 2-10.

[3b] A 1,2-dichloroethane mixed solution of 1% of the boron-containing compound 1 and 0.01% of Roycocrystal violet were prepared. The substrate on which the zinc oxide thin film prepared in step [2] was formed was set on a spin coater. On this substrate, a boron-containing compound 1 and a mixed solution of Royco Crystal Violet were dripped, and rotated for 30 seconds at 2000 rotations per minute to form a buffer layer containing a boron-containing organic compound. Moreover, this was annealed for 1 hour with a hot plate set at 200°C in a nitrogen atmosphere. The average thickness of the buffer layer was 60 nm.

(Comparative Example 8)

In step [3b], 1% 1,2-dichloroethane solution of boron-containing compound 1 was used instead of 1% of boron-containing compound 1 and 0.01% of 0.01% 1,2-dichloroethane solution of Royco Crystal Violet. Except that, it carried out similarly to Example 11, and produced the organic electroluminescent element 2-11.

(Example 13)

In step [3b], in place of Roycocrystal violet, except for using hanchi ester (= 2,6-dimethyl-1,4-dihydropyridine-3,5-diethyldicarboxylic acid), as in Example 12 In the same way, an organic electroluminescent element 2-12 was produced.

Table 1 shows the summary of the organic electroluminescent elements produced in Examples 7 to 13 and Comparative Examples 4 to 8. The wt% of the reducing agent is the ratio to the amount of the organic compound used in the buffer layer.

(Measurement of luminescence characteristics of organic electroluminescent devices)

Voltage application and current measurement were performed to the device by a "2400 type source meter" manufactured by Caseray Corporation. The light emission luminance was measured by "LS-100" manufactured by Konica Minolta.

The voltage-luminance characteristics and current density-current efficiency characteristics of the organic electroluminescent devices produced in Examples 7 to 13 and Comparative Examples 4 to 8 when DC voltage was applied under an argon atmosphere are shown in FIGS. 6 to 15. In either case, it was found that the doped device fabricated in Example has higher luminance and current efficiency than that of the non-doped device fabricated in Comparative Example, resulting in excellent characteristics.

<The third organic electroluminescent device of the present invention>

(Production of organic electroluminescent device)

(Example 14)

[1] A commercially available transparent glass substrate 1 with an ITO electrode layer having an average thickness of 0.7 mm was prepared. At this time, the ITO electrode 2 of the substrate was patterned to have a width of 2 mm. The substrate was ultrasonically cleaned for 10 minutes each in acetone and isopropanol, and then boiled for 5 minutes in isopropanol. This substrate was taken out in isopropanol, dried by nitrogen blowing, and UV ozone cleaning was performed for 20 minutes.

[2] This substrate was fixed again to the substrate holder of the Miratron sputtering apparatus having a zinc metal target. After reducing the pressure to about 1 × 10 ^-4 Pa, it was sputtered while introducing argon and oxygen to prepare a zinc oxide layer having a thickness of about 2 nm as the first metal oxide layer 3. At this time, a metal mask was used in combination to prevent zinc oxide from forming on a part of the ITO electrode for electrode extraction.

[3] This substrate is again cleaned in the cleaning step of [1] (after ultrasonic cleaning in acetone and isopropanol for 10 minutes each, boiling in isopropanol for 5 minutes, then drying by nitrogen blowing, and UV ozone cleaning for 20 minutes. ) Then, annealing was performed on a 400°C hot plate for 1 hour.

[4] Next, in order to form the layer (4) of the nitrogen-containing film, a product obtained by diluting polyethyleneimine (registered trademark: Eformin) manufactured by Nippon Catalyst to 0.5% by weight with ethanol was spin-coated under conditions of 2000 rpm and 30 seconds. did.

Eformin used here was sp003 with a molecular weight of 300.

[5] The thin film (substrate) produced in [4] was annealed at 150°C for 5 minutes on a hot plate under air. The average thickness of the layer of the nitrogen-containing film measured after annealing was 5 nm.

[6] Next, the substrate subjected to the treatment of [5] is introduced into a vacuum apparatus, and the pressure is reduced to 1 × 10 ^-4 Pa or less. As the organic compound layer (5), Alq ₃ as the light emitting layer and α-NPD as the hole transport layer were sequentially stacked by 32.5 nm and 60 nm vacuum evaporation methods.

[7] Next, on the organic compound layer 5, the 2nd metal oxide layer 6 was formed. Here, molybdenum oxide was formed by a vacuum evaporation method, which is a 10 nm vapor phase film production method.

[8] Next, the anode 7 was formed on the second metal oxide layer 6 as a final step. Here, aluminum was formed into a film by a 150 nm vacuum evaporation method.

[9] Organic EL device characteristics (voltage-current density/luminance characteristics, current density-current efficiency characteristics, constant current density) according to the following (Measurement of luminescence characteristics of organic EL devices) and (Measurement of lifetime characteristics of organic EL devices) (Continuous drive characteristic under 100 cd/m2 equivalent, 1000 cd/m2 equivalent) was measured. The measurement results are shown in (a), (b), (c-1) and (c-2) of FIGS. 17A and 17B, respectively.

(Measurement of luminescence characteristics of organic electroluminescent devices)

Voltage application and current measurement were performed to the device by a "2400 type source meter" manufactured by Caseray Corporation. Light emission luminance was measured by "BM-7" manufactured by Topcon Corporation. The measurement was carried out under an argon atmosphere.

(Measurement of life characteristics of organic electroluminescent devices)

The voltage application and the relative luminance measurement were performed to the element by the "organic EL lifetime measuring apparatus" manufactured by System Technology Research Institute. In this device, the relative luminance can be measured using a photodiode while automatically adjusting the voltage so that a constant current flows through the element.

Current values were set for each element so that the luminance at the start of the measurement was 100 cd/m 2 and 1000 cd/m 2. These results are shown in (c-1) and (c-2) in each of the Examples and Comparative Examples.

In addition, for examples other than those of Figs. (c-1) and (c-2), descriptions such as "t _1/2 = 200 h @ 1000 cd/m 2" indicate half-life, and in the above case, initial 1000 It means that the luminance half life is 200 hours when the current density equivalent to cd/m2 is continuously applied with a constant current.

(Comparative Example 9)

An organic electroluminescent device was fabricated in the same manner as in Example 14 except for omitting steps [4] [5], and voltage-current density/luminance characteristics of the organic electroluminescent device, and current density, similarly to Example 14. -The current efficiency characteristics were measured. These results are shown in Figs. 18(a) and (b), respectively.

(Example 15)

An organic electroluminescent device was prepared in the same manner as in Example 14 except that the step of the step [4] of Example 14 was changed to the following [4-2], and the voltage-current density/luminance of the organic electroluminescent device was Characteristics, current density-current efficiency characteristics, and continuous driving characteristics under a constant current density (equivalent to 1000 cd/m 2) were measured. These results are shown in (a), (b) and (c-2) of FIGS. 19A and 19B, respectively. In addition, the average film thickness of the layer of the nitrogen-containing film was 6 nm.

[4-2] Next, in order to form the layer (4) of the nitrogen-containing film, polyethyleneimine (registered trademark: Eformin) manufactured by Nippon Catalyst was diluted to 0.5% by weight with ethanol under conditions of 2000 rpm and 30 seconds. Spin coat. Eformin used here is P1000 with a molecular weight of 70000.

(Example 16)

An organic electroluminescent device was prepared in the same manner as in Example 14 except that the steps of the steps [4] and [5] of Example 14 were changed to the following [4-3] [5-3], and organic electroluminescence was performed in the same manner as in Example 14. The voltage-current density/luminance characteristics, current density-current efficiency characteristics, and continuous driving characteristics under a constant current density (equivalent to 1000 cd/m 2) of the device were measured. These results are shown in (a), (b) and (c-2) of FIGS. 20A and 20B, respectively. In addition, the average film thickness of the layer of the nitrogen-containing film was 5 nm.

[4-3] Next, in order to form the layer (4) of the nitrogen-containing film, the diethylenetriamine diluted to 1.0% by weight with ethanol is spin-coated under conditions of 2000 rpm for 30 seconds.

[5-3] The thin film (substrate) produced in [4-3] was annealed at 100°C for 2 minutes on a hot plate under air.

(Example 17)

An organic electroluminescent device was produced in the same manner as in Example 14 except for omitting the step [5], and in the same manner as in Example 14, the voltage-current density and luminance characteristics of the organic electroluminescent device, and the constant current density (100 cd/m&lt;2&gt; These results are shown in Figs. 21(a) and (c-1), respectively. In addition, since the layer of the nitrogen-containing film was not annealed, the thin film was not solidified and could not be measured. However, the film thickness of the layer of the nitrogen-containing film after annealing in Example 14 and the annealing under the atmosphere were determined. As a result, it can be seen that the film thickness decreases, so it is estimated to be about 10 nm.

(Example 18)

An organic electroluminescent device was produced in the same manner as in Example 14 except that the step of step [4] was changed to the above [4-2], and the step of [5] was changed to the following [5-5], In the same manner as in Example 14, the voltage-current density/luminance characteristics, current density-current efficiency characteristics, and continuous driving characteristics under a constant current density (equivalent to 100 cd/m2) of the organic electroluminescent device were measured. These results are shown in (a), (b) and (c-1) in Figs. 22A and 22B, respectively. In addition, the average film thickness of the layer of the nitrogen-containing film was 8 nm.

[5-5] The thin film (substrate) produced in [4-2] was annealed at 100°C for 10 minutes on a hot plate under air.

(Example 19)

An organic electroluminescent device was produced in the same manner as in Example 14 except that the step of step [4] was changed to the above [4-2], and the step of [5] was changed to the following [5-6], In the same manner as in Example 14, the voltage-current density/luminance characteristics, current density-current efficiency characteristics, and continuous driving characteristics under a constant current density (equivalent to 100 cd/m2) of the organic electroluminescent device were measured. These results are shown in (a), (b) and (c-1) in Figs. 23A and 23B, respectively. In addition, the average film thickness of the layer of the nitrogen-containing film was 7 nm.

[5-6] The thin film (substrate) produced in [4-2] was annealed at 150°C for 10 minutes on a hot plate under air.

(Example 20)

An organic electroluminescent device was produced in the same manner as in Example 14 except that the step of step [4] was changed to the above [4-2], and the step of [5] was changed to the following [5-7], In the same manner as in Example 14, the voltage-current density/luminance characteristics, current density-current efficiency characteristics, and continuous driving characteristics under a constant current density (equivalent to 1000 cd/m2) of the organic electroluminescent element were measured. These results are shown in (a), (b) and (c-2) of FIGS. 24A and 24B, respectively. In addition, the average film thickness of the layer of the nitrogen-containing film was 5 nm.

[5-7] The thin film (substrate) produced in [4-2] was annealed at 150°C for 30 minutes on a hot plate under air.

(Example 21)

An organic electroluminescent device was prepared in the same manner as in Example 14 except that the step of the step [5] of Example 14 was changed to the following [5-8], and the voltage-current density/luminance of the organic electroluminescent device was Characteristics, current density-current efficiency characteristics, and continuous driving characteristics under a constant current density (equivalent to 1000 cd/m 2) were measured. These results are shown in (a), (b) and (c-2) of FIGS. 25A and 25B, respectively. In addition, the average film thickness of the layer of the nitrogen-containing film was 5 nm.

[5-8] The thin film (substrate) produced in [4] was annealed at 100°C for 30 minutes on a hot plate under air.

(Example 22)

An organic electroluminescent device was produced in the same manner as in Example 14 except that the step of step [4] was changed to the above [4-2], and the step of [5] was changed to the following [5-9], In the same manner as in Example 14, the voltage-current density/luminance characteristics, current density-current efficiency characteristics, and continuous driving characteristics under a constant current density (equivalent to 100 cd/m2) of the organic electroluminescent device were measured. These results are shown in (a), (b) and (c-1) in Figs. 26A and 26B, respectively. In addition, the average film thickness of the layer of the nitrogen-containing film was 8 nm.

[5-9] The thin film (substrate) produced in [4-2] was annealed for 10 minutes at 150°C on a hot plate under nitrogen.

(Example 23)

An organic electroluminescent device was prepared in the same manner as in Example 14 except that the step of step [5] of Example 14 was changed to the following [5-11], and voltage-current density and luminance of the organic electroluminescent device Characteristics, current density-current efficiency characteristics, and continuous driving characteristics under a constant current density (equivalent to 1000 cd/m 2) were measured. These results are shown in (a), (b) and (c-2) of FIGS. 27A and 27B, respectively. In addition, the average film thickness of the layer of the nitrogen-containing film was 5 nm.

[5-11] The thin film (substrate) produced in [4] was annealed at 150°C for 5 minutes on a hot plate under air. Then, it rinsed with ethanol.

(Production Example 1)

The following photoelectron spectroscopy measurement was performed about the nitrogen-containing film obtained by the operation from [1] to [5] of Example 14.

Quantitative analysis was performed by simultaneously measuring the carbon 1S orbital and the nitrogen 1S orbital.

These are shown in Figs. 28(d) and (e).

(Measurement by X-ray photoelectron spectroscopy)

Measurement was performed under the following conditions using the photoelectron spectroscopic measuring device manufactured by Nippon Electronics Co., Ltd. (JPS-9000MX).

X-ray source: MgKα

Beam output (accelerated voltage-current amount): 10 kV-10 mA

PassEnergy：10 eV

Step：0.1 eV

(Production Example 2)

The photoelectron spectroscopy measurement was performed on the nitrogen-containing film obtained in the operations [1] to [4] of Example 14.

Quantitative analysis was performed by simultaneously measuring the carbon 1S orbital and the nitrogen 1S orbital.

These are shown in Figs. 29(d) and (e).

(Production Example 3)

The photoelectron spectroscopy measurement was performed on the nitrogen-containing film produced by the steps [1] to [3] of Example 14 and the steps of [4-12] and [5-12] below. In addition, the average film thickness of the layer of the nitrogen-containing film was 10 nm.

[4-12] Next, in order to form the layer (4) of the nitrogen-containing film, Aldrich polyethyleneimine ethoxylate (molecular weight: 70000) was diluted to 0.4% by weight with ethoxyethanol at 5000 rpm for 60 seconds. To spin coat.

[5-12] The thin film (substrate) produced in [4-12] was annealed at 100°C for 10 minutes on a hot plate under air.

Quantitative analysis was performed by simultaneously measuring the carbon 1S orbital and the nitrogen 1S orbital.

These are shown in Figs. 30(d) and (e).

(Production Example 4)

Operations to [1] to [3] of Example 14, [4-13] and [5] shown below were sequentially performed, and the photoelectron spectroscopic measurement was performed on the obtained nitrogen-containing film. In addition, the film thickness of the layer of the nitrogen-containing film was such that the average film thickness could not be estimated even by multiple measurements. In this respect, it is assumed to be less than 3 nm.

[4-13] Next, in order to form the layer (4) of the nitrogen-containing film, polyethyleneimine (registered trademark: Eformin) manufactured by Nippon Catalyst was diluted to 0.125% by weight with ethanol under conditions of 2000 rpm and 30 seconds. Spin coat. Eformin used here is P1000 with a molecular weight of 70000.

Quantitative analysis was performed by simultaneously measuring the carbon 1S orbital and the nitrogen 1S orbital.

These are shown in Figs. 31(d) and (e).

(Example 24-1)

An organic electroluminescent device was produced in the same manner as in Example 14 except that the steps [4] and [5] of Example 14 were changed to the following [4-18] [5-18]. The voltage-current density/luminance characteristics, and current density-current efficiency characteristics of the light-emitting element were measured. These results are shown in Figs. 32(a) and (b), respectively. In addition, the average film thickness of the layer of the nitrogen-containing film was 10 nm.

[4-18] Next, in order to form the layer (4) of the nitrogen-containing film, linear polyethyleneimine (purchased by Polyscience, molecular weight: 25000) was diluted to 0.1% by weight with ethanol under conditions of 2000 rpm for 30 seconds. To spin coat.

[5-18] The thin film (substrate) produced in [4-18] was annealed at 150°C for 5 minutes on a hot plate under air.

(Example 24-2)

An organic electroluminescent device was fabricated in the same manner as in Example 24-1 except for omitting the step [5-18], and the voltage-current density/luminance characteristics and current density of the organic electroluminescent device were similar to those of Example 14. -The current efficiency characteristics were measured. These results are shown in Figs. 33(a) and (b), respectively. In addition, the average film thickness of the layer of the nitrogen-containing film was 12 nm.

(Example 25)

An organic electroluminescent device was produced in the same manner as in Example 14 except that the steps [4] and [5] of Example 14 were changed to the following [4-20] [5-20]. The voltage-current density/luminance characteristics, and current density-current efficiency characteristics of the light-emitting element were measured. These results are shown in Figs. 34(a) and (b), respectively. In addition, the average film thickness of the layer of the nitrogen-containing film was 10 nm.

[4-20] Next, to apply melamine resin as a nitrogen-containing compound for forming the layer (4) of the nitrogen-containing film, melamine and formaldehyde are mixed in a ratio of 1:3, and methanol:water = 1:1. What was dissolved in a solvent at 0.1% by weight was spin-coated under conditions of 2000 rpm for 30 seconds.

[5-20] The thin film (substrate) produced in [4-20] was annealed at 80°C for 60 minutes on a hot plate under air.

(Comparative Example 10)

An organic electroluminescent device was produced in the same manner as in Example 14 except that the steps [4] and [5] of Example 14 were changed to the following [4-21] [5-21]. The voltage-current density/luminance characteristics, and current density-current efficiency characteristics of the light-emitting element were measured. These results are shown in Figs. 35(a) and (b), respectively.

[4-21] Next, instead of the layer (4) of the nitrogen-containing film, a polystyrene film (10 nm) as an organic film containing no nitrogen was prepared by spin coating using toluene.

[5-21] The thin film (substrate) produced in [4-21] was annealed at 150° C. for 5 minutes on a hot plate under air.

17 to 27 and 32 to 35, (a) to (c) each show the following contents.

(a) Voltage-current density (black circle) and luminance (white circle) characteristics. First, it is good to have high luminance. Second, it is better to be able to express high luminance with a lower voltage.

(b) Current density-current efficiency (black diamond shape) characteristics. First, it is good to have high current efficiency (hereinafter referred to as "efficiency"). Second, it's good to be consistent. Particularly in a high current density region (high luminance region), a high and constant one is good.

(c) It shows the change of voltage over time and the change over time of relative brightness under a constant current (here, the current value becomes 1000 cd/m2 of initial luminance). First, it is preferable that the relative luminance has a small change over time (which can maintain the luminance at the initial stage of a long time) (hereinafter, expressed as "long life"). It is related to this, but secondly, it is better that the voltage rise between them is small.

All three elements of luminance, efficiency, and life are important, but practically, life should be the first priority.

On the premise of the above, the results of Figs. 17 to 27 and 32 to 34 will be described.

Fig. 17: It emits light at a low voltage (about 2 V), and reaches a high luminance of 3000 cd/m 2 at 6 V. The efficiency is also generally high and is above 4 cd/A. In addition, even with regard to long-term changes, reliability as high as 200 hours was achieved until the luminance was halved. In other driving conditions with an initial luminance of 100 cd/m 2, it has become clear that the reproducibility is also high since it is estimated to have a half life of several thousand hours.

Fig. 18: Fig. 18 is a measurement result in an element having no layer between a metal oxide layer and a light emitting layer. It can be seen that both luminance and efficiency are 1/10 or less in FIG. 17. In the measurement results shown in Fig. 19 and below, it is shown that having a layer of a nitrogen-containing film is effective because it is always superior to the value of Fig. 18.

Fig. 19: The efficiency is better than that of Fig. 17 (element of Example 14), but the decrease in luminance in the initial few hours was severe, and in terms of life, the result of Fig. 17 was superior. From this result, it is speculated that the device of Example 14 is superior in stability under redox as a film.

Fig. 20: Both luminance and efficiency are comparable to Fig. 17 (element of Example 14). Also in the lifespan, the transition up to the initial 10 hours is equivalent to that of FIG. 17. However, there is a result of rapid deterioration after that.

From the results of Figs. 19 and 20, even when polyethyleneimines having different molecular weights are used, there is no significant difference in the initial properties, and all of them are superior results compared to having no nitrogen-containing film. However, there is a difference in long-term stability.

In Figs. 21 to 27 (Examples 17 to 23), the effect (process dependence) of the process (annealing conditions (temperature, time, atmosphere) and rinsing) after film production by applying a nitrogen-containing compound to the device characteristics was confirmed. did. In addition, the molecular weight dependence on them was shown.

Fig. 21: Measurement results of device characteristics when liquid branched polyethyleneimine (low molecular weight) is used without annealing. There is hardly any luminescence, so it is not at a level that can be called a characteristic.

22 and 23: It is the result of measuring the characteristic of the element obtained by using the liquid branched polyethyleneimine (high molecular weight) and changing the annealing temperature. Higher temperatures have obtained good results in both luminance and efficiency. The influence of the annealing temperature is slightly remarkable in the life, and the annealing at a high temperature of two or more times as a half-life has obtained good results. The difference seems to be due to the small initial luminance drop in the annealing at high temperature. Including Fig. 21, this suggests that annealing has an effect on long-term life-span, namely, long-term stability of redox. Although not described here, when annealing was performed at 200° C., the element was not measured because it turned brown. From this point, it is speculated that an optimum value exists as to the temperature of the annealing.

Fig. 24: Example 20 is the result of producing a nitrogen-containing film by changing the annealing time at 150°C, which is the best value of the annealing temperature obtained from the results of Examples 17 to 19 (Figs. 21 to 23). Both luminance and efficiency are slightly lowered compared to Fig. 23 (Example 19). In addition, it can be seen that the deterioration at the initial stage is starting to appear strong even with respect to the life curve. From these points, it is inferred that an optimum value also exists for the annealing time.

Fig. 26: Finally, it is the result of adding examination in the said best condition about the atmosphere for annealing. In the case where the nitrogen-containing film was produced under the conditions of FIG. 23 (Example 19) under nitrogen, there was no significant difference from FIG. 23 in the initial characteristics (brightness/efficiency). From this point of view, the effect of having a nitrogen-containing film here is assumed to be an electron attraction effect due to metal-nitrogen polarization in physical adsorption, not chemical adsorption, and carbon-nitrogen polarization in a molecule. It should be noted that the lifespan is extremely short in FIG. 26. From this point of view, it is considered that the annealing process in the present invention causing a longer life is likely to be accompanied by a chemical change, not only a solvent removal or a change in morphology. (The chemical change will be described later)

Fig. 25: From the results of the above discussion, the annealing conditions are the results of examining it, since it is speculated that it depends not only on the material but also on the molecular weight.

For the liquid branched polyethyleneimine (low molecular weight), as a result of annealing for a long time at a temperature lower than the maximum temperature, in terms of initial characteristics, both luminance and efficiency were obtained close to those of FIG. 17, but at the voltage before light emission, Moreover, it was observed that the current density value was high in reverse bias. This means that there is an unnecessary current flow that does not contribute to light emission (hereinafter, referred to as "leak current"), and in many cases, there is a problem with long-term stability. Also this time, the lifespan is short, such as a severe drop in luminance from the beginning, and it is considered that the leakage current is the cause.

From this result, it became clear that the best value of an annealing condition depends not only on the material but also on the molecular weight. In addition, it was suggested that a critical value of a temperature depending on a material or molecular weight also exists, since it is not possible to obtain properties that may be subjected to annealing for a long time below the maximum temperature.

Fig. 27: When the rinsing effect under the best conditions (condition of Example 14) is confirmed, the initial characteristics (luminance/efficiency) are substantially equal to those of Fig. 17 (Example 14), but the leakage current is slightly large. It is considered that this is a factor that makes the life characteristics worse than that in Fig. 17 (Example 14). However, although not shown in this figure, the variation in characteristics between fabrication elements is small, and it is improved in terms of reproducibility. This is considered to be an important process from the viewpoint of practical use. Also in the lifespan, it is thought that improvement is improved by finding out better rinse conditions.

32 and 33: Results of using linear polyethyleneimine as a nitrogen-containing compound. Regardless of the presence or absence of an annealing treatment, all of them exhibit good initial characteristics (luminance/efficiency). Unlike branched polyethyleneimine, this is considered to be a solid factor. In short, the effect of annealing is inferred as the following three points. (i) Solidify. (ii) By diversifying metal-nitrogen bonds, a strong bonded species is prepared. (iii) The carbon element: nitrogen element ratio is changed, and the nitrogen element existence ratio is improved relatively.

The effect of these annealing will be described later again.

Fig. 34: Results of examining application of melamine resin as a material having a high nitrogen ratio. Compared with FIG. 18, favorable results were obtained, and it was confirmed that there is an effect. Since there is also a non-uniformity in light emission, it is thought that better results can be obtained if detailed favorable conditions can be found.

Fig. 35: Results of applying an organic film containing no nitrogen. It can be seen that both luminance and efficiency are inferior to those of FIG. 19 in the initial characteristics. In this respect, it is thought that this organic film functioned as a simple insulating layer. In addition, the lifetime of this device is extremely short, a few minutes, and it is expected that the mechanism of electron injection is due to bending of the bands of the light-emitting layer due to charge accumulation in the light-emitting layer. By detailed examination of the conditions, it is considered that the initial characteristics can be improved even in polystyrene, but since the drive mechanism is as shown above, it is considered that long-term reliability cannot be expected as in the device of the present invention.

Next, Figs. 28 to 31 (Production Examples 1 to 4) will be described.

In Production Examples 1 to 4, before annealing of the nitrogen-containing film, in all cases of liquid branched polyethyleneimine, measurement was impossible. On the other hand, measurement became possible by annealing. In this regard, it was suggested that the annealing was solidified by some effect (the conclusion of decomposition cannot be reached from this result alone) (the above effect (i)).

The results (d) of the X-ray photoelectron spectroscopy measurement of the carbon 1s orbital in FIGS. 28 to 31 and (e) of the X-ray photoelectron spectroscopy measurement of the nitrogen 1s orbital are both measurement results after annealing. Before annealing, it is confirmed that all are C:N ≒ 2:1 except for FIG. 30. 30 shows C:N ≒ 4:1 before annealing. These ratios are values consistent with the stoichiometric ratios estimated from the chemical structure. The ratio of the existence of this element is estimated from the ratio of the peak area of each orbit. In the comparison of Figs. 28 and 29, it was confirmed that there is a change in the ratio or not depending on the presence or absence of an annealing. By annealing, the peak areas of both carbon and nitrogen are decreasing, but the decrease of the carbon peak is large, leading to an improvement of the nitrogen element ratio relatively. In Fig. 30, it can be seen that there is no significant chemical change since there is no change (with stoichiometric ratio) before annealing even after annealing. This means that the thin film formed from polyethyleneimine or a compound modified with polyethyleneimine described in Non-Patent Documents 1 to 3 is a thin film obtained by annealing the liquid branched polyethyleneimine (low molecular weight) implemented in the present invention. It was suggested that it is not equivalent to the effect of Fig. 31 is a result of performing the same annealing treatment by thinning a liquid branched polyethyleneimine (high molecular weight) to be equal to or greater than that of a low molecular weight.

Also in this result, the high molecular weight polyethyleneimine does not change the ratio of the element present. From this point, it was suggested that the abundance ratio of a carbon element: a nitrogen element does not occur under certain conditions, for example, under a low molecular weight (the above effect (iii)).

28 to 30 (f) are diagrams showing the results of performing peak division on the results of the X-ray photoelectron spectroscopy measurement of the nitrogen 1s orbit. In the present system, two types of bonds of nitrogen atoms are assumed: a carbon-nitrogen bond and a metal-nitrogen bond. In the past literature, the lowest energy peak is attributed to the metal-nitrogen bond. Further, next, when another peak is attributed to a carbon-nitrogen bond, the energy difference between all two peaks is almost equal to 0.6 eV to 0.7 eV, suggesting that the peak division and attribution of these peaks are correct.

In addition, although not shown here, in all the examples of Figs. 28 to 30 before annealing, the half widths are all 1.2 eV. In this respect, in the case of Figs. 28 and 30, the half width is increasing, and it is considered that this leads to a longer life (the effect (ii)).

From the above, in the case of Fig. 28, it is considered that all the effects (i) to (iii) are exhibited, and initial characteristics (luminance/efficiency) and long-term reliability (lifetime) can be realized. In Fig. 30, it is speculated that the initial characteristics and a certain amount of life can be realized in (i) and (ii), and similarly, in Fig. 29, in the effect of (i), the initial characteristics and a certain amount of life can be realized. . These points are not the results of the X-ray photoelectron spectroscopy measurement, but the solid linear polyethyleneimine used in Figs. 32 and 33 is a point in which (i) is realized, even if there is no effect of annealing, to some extent It is thought that life can be realized. The same is the case in FIG. 34.

The following points became clear from the above results.

In a comparison between FIG. 18 and other drawings, it was confirmed that when the nitrogen-containing thin film is disposed on the oxide on the lower cathode, it leads to improvement of characteristics of the organic electroluminescent device such as brightness and efficiency. As for the annealing treatment, it was confirmed from Fig. 33 that annealing is not required depending on the material, and is not necessarily required. However, it was confirmed that by performing annealing, the life characteristics corresponding to long-term reliability are improved in many cases. Moreover, it was confirmed that various nitrogen-containing compounds such as polyethyleneimine (<linear and branched> having different molecular weights or different shapes), diethylenetriamine, and melamine resins can be used for the materials to be used. In addition, it was also confirmed that they needed to select a process depending not only on the material but also on the molecular weight and shape. In particular, since linear polyethyleneimine is solid, unlike other polyethyleneimines, it is considered that the effect is expressed even without annealing. In addition, it has also been confirmed that rinse after film production is also effective.

1: Substrate
2: negative electrode
3: First metal oxide layer
4: layer of nitrogen-containing film
5: Organic compound layer
6: second metal oxide layer
7: positive pole

Claims (17)

An organic electroluminescent device having a structure in which a plurality of layers are stacked,
The organic electroluminescent device has a metal oxide layer between the first electrode and the second electrode,
It has a buffer layer formed on the metal oxide layer by an organic compound and smoothes the irregularities present on the metal oxide surface,
The organic electroluminescent device, wherein the first electrode is a cathode formed on a substrate, and the buffer layer is a layer formed between the cathode and the emission layer. The method of claim 1,
The organic electroluminescent device, wherein the buffer layer is a layer having an average thickness of 3 nm or more formed by applying a solution containing an organic compound, and the buffer layer is formed adjacent to the metal oxide layer. The method of claim 1,
The buffer layer is an organic electroluminescent device, characterized in that the layer having an average thickness of 5 to 50 nm. The method of claim 1,
The organic compound is an organic electroluminescent device, characterized in that the organic compound having a boron atom. The method of claim 4,
The organic compound having the boron atom is the following formula (1);
[Formula 1]

(In the formula, the dotted circular arc indicates that a ring structure is formed together with the skeleton portion indicated by the solid line. The dotted line portion in the skeleton portion indicated by the solid line indicates that a pair of atoms connected by a dotted line may be connected by a double bond. The arrow from the nitrogen atom to the boron atom indicates that the nitrogen atom is coordinated with the boron atom, Q ¹ and Q ² are the same or different, and are a linking group in the skeletal part represented by a solid line, at least a part of which is a dotted circular arc A ring structure is formed together with a moiety, and may have a substituent X ¹ , X ² , X ³ and X ⁴ are the same or different, and represent a hydrogen atom or a monovalent substituent that becomes a substituent of the ring structure, A plurality of rings may be bonded to the ring structure forming the circular arc portion of the dotted line. n ¹ represents an integer of 2 to 10. Y ¹ is a direct bond or n ¹ valent linking group, and a structure other than Y ^{1 having} n ¹ Each independently of the moiety represents a ring structure forming a dotted circular arc moiety, which is bonded at any one point in Q ¹ , Q ² , X ¹ , X ² , X ³ and X ⁴ .) It is a containing compound, or the following formula (2);
[Formula 2]

(In the formula, the dotted circular arc indicates that a ring structure is formed together with a part of the skeletal part connecting the boron atom and the nitrogen atom. The dotted line part in the skeletal part connecting the boron atom and the nitrogen atom is at least one pair The atom of is connected by a double bond, and the double bond may be conjugated with the ring structure The arrow from the nitrogen atom to the boron atom indicates that the nitrogen atom is coordinated with the boron atom X ⁵ and X ⁶ are the same or different. And a hydrogen atom or a monovalent substituent serving as a substituent of a ring structure, and may be bonded to a plurality of ring structures forming a dotted circular arc portion R ¹ and R ² are the same or different, and a hydrogen atom or a monovalent substituent At least one of X ⁵ , X ⁶ , R ^1, and R ² is a substituent having a reactive group.) An organic electric field characterized in that it is a boron-containing polymer obtained by polymerizing a monomer component containing a boron-containing compound represented by Light-emitting element. The method of claim 1,
The buffer layer is an organic electroluminescent device comprising a reducing agent. The method of claim 6,
The organic electroluminescent device, wherein the buffer layer is a layer having an average thickness of 5 to 100 nm formed by applying a solution containing an organic compound. The method of claim 6,
The reducing agent is an organic electroluminescent device, characterized in that the hydride reducing agent. The method of claim 8,
The hydride reducing agent is 2,3-dihydrobenzo[d]imidazole compound, 2,3-dihydrobenzo[d]thiazole compound, 2,3-dihydrobenzo[d]oxazole compound, triphenylmethane An organic electroluminescent device comprising at least one compound selected from the group consisting of a compound and a dihydropyridine compound. The method of claim 1,
The organic electroluminescent device, characterized in that the buffer layer is made of a nitrogen-containing film. The method of claim 10,
The buffer layer is an organic electroluminescent device, characterized in that the layer having an average thickness of 3 ~ 150 nm. The method of claim 10,
The nitrogen-containing film is formed of a nitrogen-containing compound, or contains a nitrogen element and a carbon element as elements constituting the film, and the abundance ratio of the nitrogen atom and the carbon atom constituting the film is
Number of nitrogen atoms/(number of nitrogen atoms + number of carbon atoms)> 1/8
An organic electroluminescent device, characterized in that satisfying the relationship of. The method of claim 10,
The nitrogen-containing film is formed by decomposing a nitrogen-containing compound by heating. The method of claim 12,
The nitrogen-containing compound is an organic electroluminescent device, characterized in that the polyamines or triazine ring-containing compound. A display device formed by using the organic electroluminescent device according to any one of claims 1 to 14. A lighting device formed using the organic electroluminescent element according to any one of claims 1 to 14. A method of manufacturing an organic electroluminescent device having a structure in which a plurality of layers are stacked,
The manufacturing method is a low molecular weight organic electroluminescent device comprising a first metal oxide layer between a first electrode and a second electrode, a buffer layer for smoothing irregularities existing on the metal oxide surface, and a light emitting layer stacked on the buffer layer. A step of laminating each layer constituting an organic electroluminescent device to have a compound layer and a second metal oxide layer in this order, wherein the first electrode is a cathode formed on a substrate,
The lamination step includes a step of forming a buffer layer having an average thickness of 3 nm or more by applying a solution containing an organic compound.

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