JP2007317980A - Organic el element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic EL element which has sufficient color conversion ability to attain desired wavelength distribution, and by which high electronic characteristics (carrier transfer characteristics) can be obtained at the same time. <P>SOLUTION: The organic EL element is provided with an organic EL layer which is sandwiched between a pair of electrodes. The organic EL layer includes at least a carrier recombination layer and one or several carrier uncombined layers. The carrier recombination layer emits EL light by recombination of carriers which are implanted into the organic EL layer. The carrier uncombined layer is composed of one host material, one or several kinds of PL emitting dye materials which emit PL light at lower energy than EL light and a carrier transport material. In this case, the carrier transport material exhibits higher carrier transport properties than those of the host material, and the distance is 15 nm or more between the carrier recombination layer and the carrier uncombined layer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a configuration of an organic EL element used in an organic electroluminescence (hereinafter referred to as organic EL) display capable of high-definition and excellent visibility and capable of multicolor display, a backlight of a color liquid crystal display, and other lighting devices. .

As an example of a light-emitting element applied to a display device, an organic EL element having a thin film laminated structure of an organic compound is known. Organic EL elements are thin-film self-luminous elements and have excellent characteristics such as low drive voltage, high resolution, and high viewing angle. Therefore, various studies have been made for their practical application.
In a conventional white organic EL device, a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, and an electron injection layer are sequentially formed on a glass substrate on which an anode is formed, and a cathode is formed on the electron injection layer. It has a formed structure. In such a conventional white organic EL device, the light-emitting layer serving as the carrier recombination center is either a single light-emitting layer in which a plurality of light-emitting dyes are mixed or a laminate of layers containing a plurality of different light-emitting dyes. .

  In the conventional white organic EL device, carriers are injected from the cathode and the anode, and by properly balancing the carriers, negative carriers (electrons) and positive carriers (holes) are recombined in the light emitting layer, thereby forming the light emitting layer. A plurality of dye light-emitting materials included are excited simultaneously to obtain white color from the substrate surface (see, for example, Non-Patent Documents 1 and 2 and Patent Documents 1 and 2).

  According to the organic EL element having such a light emitting mechanism, it is difficult to realize a simple white organic EL element with high efficiency and long life. For example, in a white organic EL element including a single light-emitting layer in which a plurality of light-emitting pigment materials (light-emitting dopants) are mixed (see, for example, Patent Document 3), the following process from generation of carriers to emission of white light: 1) transfer of carriers (electrons and holes) to the carrier recombination layer, (2) generation of host luminescent material excitons, (3) transfer of excitation energy between host luminescent material molecules, (4) host luminescent material to guest By excitation energy transfer to the luminescent material, (5) generation of guest luminescent material excitons, (6) via energy transfer between different guest luminescent materials, and (7) relaxation of the guest luminescent material excitons to the ground state Emits light.

Each energy transfer process ((3) to (6)) is a competitive reaction with various energy deactivation processes. In order to obtain pure white EL light emission in this configuration, the energy transfer process between the different guest light-emitting materials (6) is very important.
Therefore, if the doping concentration of these dye light-emitting materials is not optimized, energy transfer from a dye material having a high excitation energy to a dye material having a low excitation energy may occur, and a pure white color may not be obtained. There is. In addition, when using a red light emitting dopant and a blue light emitting dopant, the concentration of the red light emitting dopant and the blue light emitting dopant necessary for exhibiting good electroluminescent characteristics is extremely low, for example, 0.12% and 0.25% of the host material. The concentration is low and difficult to control in mass production (see, for example, Patent Document 4). In addition, even if the initial emission is pure white, the balance of energy transfer between the light-emitting dye materials in the light-emitting layer (carrier recombination layer) may be disrupted due to the magnitude of the energization current or the energization time, and the emission color may change. There are many.

In a white organic EL device configured by stacking a plurality of different light-emitting layers, carriers are injected from the electrodes, and carriers are recombined in the plurality of light-emitting layers to simultaneously excite a plurality of dye light-emitting materials, and white from the device surface. Get EL emission.
In the white organic EL element configured as described above, it is necessary to recombine carriers in a plurality of light emitting layers in a balanced manner. However, in many cases, the carrier recombination region changes depending on the driving voltage of the element, the emission of one dye becomes stronger, the emission of the other dye becomes weaker, and the emission color obtained from the substrate surface changes.

In a white organic EL device that is formed by laminating a plurality of light-emitting layers containing different light-emitting dyes, carriers are injected from the electrodes, and carriers are recombined in the light-emitting layers to simultaneously excite a plurality of dye light-emitting materials. White EL emission is obtained from the element surface.
For example, from Eastman Kodak, USA, the carrier recombination region of the organic EL device is adjusted to the interface between the light emitting layer and the carrier transport layer, and the carrier recombination center is the interface between the light emitting layer and the carrier transport layer doped with the yellow light emitting dopant. The blue light emitting material in the light emitting layer is excited, part of the excitation energy is transferred to the adjacent carrier transport layer, and the yellow light emitting dopant is also emitted, so that the blue and yellow light emission spectra are emitted from the substrate surface. A white EL light-emitting element that obtains a mixed white color has been announced (see Patent Documents 5 and 6).

According to the above prior art, the carrier recombination center is the interface between the blue light-emitting layer and the yellow dye-doped electron transport layer, and the carrier recombination portion becomes wider as the driving current increases, and the yellow light-doped carrier from the blue light-emitting layer It is considered that energy is transferred to the transport layer, and blue light and yellow light from each layer are mixed to obtain white color from the element surface.
In the method of emitting light of a different material by the energy transfer, the potential radius of ionized molecules, which is a distance requirement when performing energy transfer, is theoretically about 15 nm or less. It is considered that the film thickness of the light emitting layer and the light emitting layer adjacent to the light emitting layer having a thickness of 15 nm or less from the adjacent interface are particularly effective for energy transfer.

However, in the white organic EL element configured as described above, it is necessary to recombine carriers in a plurality of light emitting layers in a balanced manner. In many cases, the carrier recombination region changes depending on the driving voltage of the element, the emission of one dye becomes stronger, the emission of the other dye becomes weaker, and the emission color obtained from the substrate surface changes.
In recent years, as an example of a multi-color or full-color display method for a display composed of organic EL elements, it absorbs near-ultraviolet light, blue light, blue-green light, or white light emitted from the organic EL elements. A color conversion (CCM) method using a color conversion layer including a color conversion dye that emits light in the visible light region by performing wavelength distribution conversion has been studied. When the color conversion method is used, the light emission color of the light source is not limited to white, so that the degree of freedom in selecting the light source can be increased. For example, green and red light can be obtained by wavelength distribution conversion using an organic EL element that emits blue to blue green light. Recently, in addition to a method of using a color conversion layer provided on a substrate independent of an organic EL element, an organic EL element in which a color conversion function is imparted to a constituent layer of the organic EL element has been proposed (for example, (See Patent Documents 7 to 9.)
Japanese Patent No. 2991450 JP 2000-243563 A US Pat. No. 5,683,823 JP 2001-250690 A JP 2002-93583 A JP 2003-86380 A JP-A-6-215874 JP-A-6-203963 JP 2001-279238 A J. Kido et al., Science 267, 1332 (1995) J. Kido et al., Appl, Phys. Lett. 67 (16) 2281-2283,1995

  In the case where the constituent layer of the organic EL element is provided with a color conversion function, it is common to dope the constituent layer with a color conversion dye. However, since color conversion dyes are generally insulating, increasing the amount of color conversion dye dope to achieve the desired wavelength distribution reduces the electronic properties of the constituent layers, ie carriers (electrons or electrons). This causes a problem that the driving voltage increases due to the hindrance to the movement of the holes. In order to prevent the deterioration of the electronic characteristics, it is conceivable to take measures such as a reduction in the doping amount of the color conversion dye or a reduction in the thickness of the constituent layer. In that case, sufficient color conversion is not achieved, There is a possibility that light from the light emitting layer may pass through the constituent layer.

  An object of the present invention is to provide an organic EL device that has sufficient color conversion ability to achieve a desired wavelength distribution and at the same time can obtain high electronic characteristics (carrier movement characteristics). In addition, it is a further object of the present invention to provide an organic EL element that does not change greatly in light emission efficiency, can be adapted to the manufacturing process of a conventional organic EL element, and whose emission color is less likely to change depending on the energization time and the energization current. Is the purpose.

  The organic EL device of the present invention includes an organic EL layer sandwiched between a pair of electrodes, and the organic EL layer includes at least a carrier recombination layer and one or more carrier non-bonding layers, and the carrier recombination The layer emits EL light by recombination of carriers injected into the organic EL element, and the carrier non-bonding layer emits PL (photoluminescence) light having a lower energy than the host material and the EL light. Or a plurality of kinds of PL luminescent dye materials and a carrier transport material, wherein the carrier transport material has a carrier mobility larger than that of the host material, and the distance between the carrier recombination layer and the carrier non-bonding layer is 15 nm or more. It is characterized by being. Here, the carrier non-bonding layer is desirably a hole injection layer, and the EL light is preferably blue to blue-green light having a peak wavelength of 400 to 500 nm.

By adopting the above configuration, the PL light-emitting carrier non-bonding layer can be obtained even if the amount of the PL light-emitting dye material added to the color conversion layer is increased by doping the carrier transport material having excellent carrier mobility. It is possible to achieve both high-efficiency color conversion and drive voltage reduction without adversely affecting the electronic characteristics of the entire light-emitting carrier non-bonding layer.
Further, in the organic EL device of the present invention, blue light emission by EL (electroluminescence) that requires carrier recombination occurs only in the light emitting layer, and other colors absorb a part of this blue light emission and PL. Light is emitted by (photoluminescence). Therefore, when multiple types of EL light emitting dyes are added as a dopant to one light emitting layer, energy transfer between the dyes occurs, and the emission of higher energy blue light is disturbed. In the organic EL device of the present invention, by setting the distance between the carrier recombination layer and the carrier non-bonding layer to 15 nm or more, such energy transfer does not occur and a layer having a fluorescent dopant (carrier non-bonding). The luminous efficiency is not lowered by placing the color conversion function on the host material of the layer.

  Furthermore, in the organic EL device of the present invention, light emission by EL (electroluminescence) that requires carrier recombination occurs only in the organic light emitting layer, and other colors absorb a part of this EL light to cause PL. Light is emitted by (photoluminescence). For a specific PL luminescent dye material, the quantum yield of absorption of specific excitation light (EL light) is constant, and the PL luminescence intensity of the PL luminescent dye material changes in proportion to the intensity of EL light.

  Therefore, the organic EL device of the present invention is less likely to change its emission spectrum due to changes in driving voltage and current, and can emit light stably in a desired wavelength distribution (hue). Furthermore, even if the intensity of the EL light from the organic light emitting layer changes as the cumulative energization time for the organic EL element increases, the emission intensity of the PL light also changes in accordance with the change. It is possible to stably emit light having a desired wavelength distribution (hue).

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic cross-sectional view showing an example of the organic EL element of the present invention. The organic EL element has an organic EL layer (specifically, a hole injection layer 3, a hole transport layer 4, a light emitting layer 5, an electron transport layer 6 and an electron injection layer 7) on the transparent substrate 1 on which the anode 2 is formed. And the cathode 8 has a structure formed sequentially. The anode 2 and the cathode 8 can be light transmissive or light reflective, respectively, but preferably one of them is light transmissive and the other is light reflective.

  The transparent substrate 1 is preferably transparent to visible light (wavelength 400 to 700 nm). Moreover, the transparent substrate 1 should be able to withstand the conditions used for forming a layer (described later) laminated thereon, and is preferably excellent in dimensional stability. Preferably, a resin film or sheet made of quartz, glass plate, polyester, polymethyl methacrylate, polycarbonate, polysulfone, or the like can be used as the transparent substrate 1.

The anode 2 is selected from a material having a high work function having a work function of 4.7 eV or more in order to reduce the energy barrier for hole injection. The anode 2 may be light transmissive or light reflective. When light from the organic EL element is taken out from the transparent substrate 1 side, the anode 2 is preferably light transmissive (having a transmittance of 80% or more with respect to visible light). The light-transmitting anode 2 is, for example, ITO (indium tin oxide), IZO (indium zinc oxide), SnO ₂ , ZnO, TiN, which are transparent conductive materials generally known as transparent electrodes. It can be formed using a conductive inorganic compound such as ZrN or TiO _x . These substances are formed on the transparent substrate 1 by vacuum deposition or sputtering.

  When the light of the organic EL element is taken out from the cathode 8 side, the anode 2 is preferably light reflective. The light-reflective anode 2 preferably has a light reflectivity of 80% or more with respect to visible light, and is formed by laminating a highly reflective metal, amorphous alloy or microcrystalline alloy and the above-described transparent conductive material. Can be formed. High reflectivity metals that can be used include Al, Ag, Mo, W, Ni, Cr, and the like. High reflectivity amorphous alloys that can be used include NiP, NiB, CrP, CrB, and the like. High reflectivity microcrystalline alloys that can be used include NiAl and the like.

  The cathode 8 is often selected from a material having a work function of 4.3 eV or less and a small work function in order to reduce the energy barrier for electron injection. The cathode 8 may be light transmissive or light reflective. When light from the organic EL element is extracted from the transparent substrate 1 side, the cathode 8 is preferably light reflective (preferably having a visible light reflectance of 90% or more). Specifically, the light-reflective cathode 8 is composed of a single metal made of an alkali metal such as Li, Na, or K, an alkaline earth metal such as Mg or Ca, or these metals and Al, Ag, In, or the like. It can be formed from such an alloy. Alternatively, metals such as Al, In, Ti, or alloys containing these metals can be used as the cathode material.

When the light of the organic EL element is extracted from the cathode 8 side, the cathode 8 is preferably light transmissive. The light transmissive cathode can be formed using the above-described transparent conductive material.
In particular, when a cathode is manufactured using a transparent conductive material, it is possible to improve the electron injection efficiency by providing an electron injection buffer layer at the interface between the cathode and the organic EL layer as the electron injection layer. It is. As a material for the buffer layer, an alkali metal such as Li, Na, K, or Cs, an alkaline earth metal such as Ba or Sr, an alloy containing them, a rare earth metal, or a fluoride of these metals may be used. Yes, but not limited to them. The film thickness of the buffer layer can be appropriately selected in consideration of the driving voltage, transparency, and the like, but in a normal case, it is preferably 10 nm or less.

Here, a case where the PL light-emitting carrier non-bonding layer of the organic EL element is a hole injection layer will be described.
The PL light-emitting carrier non-bonding layer includes a hole injecting host material, a color conversion dye material, and a carrier transport material having a carrier mobility larger than that of the hole injecting host material and excellent in carrier transport characteristics. .

  The PL light-emitting carrier non-bonding layer absorbs a part of incident light (light emission from the organic EL element) and performs wavelength distribution conversion, and has different wavelength distributions including non-absorption of incident light and converted light. It is a layer for emitting light. Preferably, blue to blue-green light from the organic EL element is converted into white light. The white light in the present invention includes not only light that uniformly contains a wavelength component in the visible region (400 to 700 nm) but also light that does not contain the wavelength component uniformly but appears white to the naked eye.

  The color conversion dye is a dye that absorbs incident light and emits light in different wavelength ranges, and preferably absorbs blue to blue-green light emitted from a light source to emit light in a desired wavelength range (for example, green (Or red). As the color conversion dye, represented by (Chemical Formula 1), DCM-1 (I), DCM-2 (II), DCJTB (III), 4,4-difluoro-1,3,5,7-tetraphenyl- 4-Bora-3a, 4a-diaza-s-indacene (IV), dyes for red light emitting materials such as Nile Red (V), rhodamine dyes that emit red light, cyanine dyes, pyridine dyes, oxazines Any dye known in the art such as a coumarin dye or naphthalimide dye emitting green light can be used.

ホール注入ホスト材料としては、フタロシアニン類（銅フタロシアニンなど）またはインダンスレン系化合物、ＢＡＰＰ，ＢＡＢＰ，ＣｚＰＰ，ＣｚＢＰなどの高分子ペリレン系材料などを用いることができる。また、注入性ホスト材料よりもキャリア移動特性に優れるキャリア輸送材料はホール輸送材料を用いることができ、ＴＰＤ、Ｎ，Ｎ’−ビス（１−ナフチル）−Ｎ，Ｎ’−ジフェニルビフェニルアミン（α−ＮＰＤ）、４，４’，４”−トリス（Ｎ−３−トリル−Ｎ−フェニルアミノ）トリフェニルアミン（ｍ−ＭＴＤＡＴＡ）、Ｎ，Ｎ，Ｎ’，Ｎ’−テトラビフェニル−４，４’−ビフェニレンジアミン（ＴＢＰＢ）などのトリアリールアミン系材料を含む公知の材料を用いることができる。

As the hole injection host material, phthalocyanines (such as copper phthalocyanine) or indanthrene compounds, polymer perylene materials such as BAPP, BABP, CzPP, and CzBP can be used. In addition, a hole transport material can be used as a carrier transport material that is superior in carrier transfer characteristics to an injectable host material, and TPD, N, N′-bis (1-naphthyl) -N, N′-diphenylbiphenylamine (α -NPD), 4,4 ', 4 "-tris (N-3-tolyl-N-phenylamino) triphenylamine (m-MTDATA), N, N, N', N'-tetrabiphenyl-4,4 Known materials including triarylamine-based materials such as' -biphenylenediamine (TBPB) can be used.

  The hole transport layer 4 in the embodiment of the present invention is a layer that defines the distance between the carrier non-bonding layer (the luminescent hole injection layer 3) and the luminescent layer 5, and preferably has a thickness of 15 nm or more. . The hole transport layer 4 can be formed from a compound having the ability to transport holes and having an excellent thin film forming ability. These layers of materials can achieve an excellent hole transport effect of transporting holes smoothly and efficiently by the light emitting layer 5 and can prevent electrons from moving into the hole transport layer 4.

  Specifically, the material includes TPD, N, N′-bis (1-naphthyl) -N, N′-diphenylbiphenylamine (α-NPD), 4,4 ′, 4 ″ -tris (N-3- Known to include triarylamine-based materials such as tolyl-N-phenylamino) triphenylamine (m-MTDATA), N, N, N ′, N′-tetrabiphenyl-4,4′-biphenylenediamine (TBPB) Alternatively, the known phenylamine multimeric material system N, N′-bis (3-methylphenyl)-(1,1′-biphenyl) -4,4′-diamine, N, N-diphenyl-N, N ′-(3-methylphenyl) -1,1′-biphenyl-4,4′-diamine, 1,1-bis (4-di-p-tolylaminophenyl) cyclohexane, 4, 4 ' An organic material such as bis (N-(1-naphthyl) -N- phenylamino) compounds such as biphenyl, or may be used as a hole-injecting property and a hole-transporting material.

  These materials can be formed on the substrate by a conventional vacuum deposition method. In addition, polymer materials such as polyvinyl carbazole and polysilane can be used as the hole injection layer material. These polymeric materials are formed by coating and drying after dissolving in an organic solvent together with a binder such as polycarbonate, polyacrylate, or polyester. Organic materials other than the polymer material may be formed by a vacuum deposition method. Further, the film forming method is not limited to these.

The light-emitting layer 5 includes holes transported from the anode 2 through the PL light-emitting hole injection layer 3 and the hole transport layer 4, and electrons injected from the cathode 8 through the electron injection layer 7 and the electron transport layer 6. The light emitting layer 5 emits energy released by recombination, and the material of the light emitting layer 5 can be selected according to a desired color tone.
For example, in order to obtain blue to blue-green light emission, fluorescent whitening agents such as benzothiazole, benzimidazole, and benzoxazole, metal chelated oxonium compounds, styrylbenzene compounds, and aromatic dimethylidin compounds are used. can do. More specifically, 4,4′-bis (2,2-diphenylvinyl) biphenyl (DPVBi) can be mentioned.

  In addition, in order to obtain light emission of various wavelengths, a host compound (distyrylarylene compound, 4,4′-bis [N- (3-tolyl) -N-phenylamino] biphenyl (TPD), aluminum complex (for example, tris A material obtained by adding a dopant (perylene, quinacridones, rubrene, etc.) to (8-hydroxyquinolinato) aluminum complex (Alq3) or the like) can also be used.

  Examples of materials that can be used in the present invention and that constitute the electron transport layer 6 and the electron injection layer 7 include compounds having an ability to transport and inject electrons and an excellent thin film forming ability. The layers of these materials can achieve an excellent electron transport effect of transporting electrons from the cathode 8 to the light emitting layer 5 smoothly and efficiently, and can prevent electrons from moving to the hole transport layer 4.

  The electron transport layer and electron injection layer materials that can be used in the present invention are not particularly limited, and known materials can be used. For example, the electron transport layer may be an oxadiazole derivative such as 2- (4-biphenyl) -5- (pt-butylphenyl) -1,3,4-oxadiazole (PBD), a triazole derivative, or a triazine derivative. , Phenylquinoxalines, quinolinol complexes of aluminum (eg, Alq3), and the like. The electron injection layer can be formed using an alkali metal or alkaline earth metal such as Li, Ca, Cs, or Mg, or a fluoride or oxide of these metals.

  In the configuration as described above, when the anode 2 is light transmissive and the cathode 8 is light reflective, EL light emitted from the light emitting layer 5 toward the anode side is emitted from the PL light emitting hole injection layer 3 or the like. The light passes through the layers and exits from the transparent substrate 1. The EL light emitted from the light emitting layer 5 toward the cathode side is reflected by the cathode 8 and similarly passes through the layers such as the PL light emitting hole injection layer 3 and is emitted from the transparent substrate 1. At that time, in the PL light-emitting hole injection layer 3, part of the EL light undergoes wavelength distribution conversion to become yellow to red PL light. By mixing the emitted EL light and PL light, light having white color is obtained as light emission of the entire element.

  On the contrary, when the anode 2 is light reflective and the cathode 8 is light transmissive, the EL light emitted from the light emitting layer 5 toward the anode side passes through a layer such as the PL light emitting hole injection layer 3. After receiving the wavelength distribution conversion, the light is reflected by the anode 2 and again passes through the PL light-emitting hole injection layer 3 and is emitted from the cathode 8. At this time, when the light passes through the PL light emitting hole injection layer 3 twice, part of the EL light undergoes wavelength distribution conversion to become yellow to red PL light. The EL light emitted from the light emitting layer 5 toward the cathode side is emitted from the cathode 8 without undergoing wavelength distribution conversion. Also in this case, by mixing the emitted EL light and PL light, light having white color can be obtained as light emission of the entire element. In this embodiment, the transparent electrode (anode 2) does not exist in the path from the emission of EL light to the conversion of PL light, and therefore the EL light is scattered in the substrate edge direction due to total reflection at the transparent electrode interface. Since it is used for wavelength distribution conversion without any problem, it is possible to obtain white light with higher efficiency.

Hereinafter, the present invention will be described in more detail with reference to specific examples, but the present invention is not limited thereto. Note that a source meter 2400 (manufactured by Keithley Instruments Co., Ltd.) and a Topcon BM-8 luminance meter were used for element characteristic evaluation. The devices manufactured in the following examples were evaluated by evaluating the light emission luminance, the light emission efficiency, and the maximum light emission luminance by applying a DC voltage and measuring. Also, elements, and a constant current DC driven by the driving current density of ^{0.1A / cm 2, 1A / cm} 2, was evaluated EL emission spectrum and the driving voltage. The EL spectrum was measured using a PMA-11 optical multichannel analyzer (manufactured by Hamamatsu Photonics Co., Ltd.).

  Examples of the organic EL element having the above-described configuration will be described along the procedure.

  The organic EL element of this example has a layer structure as shown in FIG. The glass transparent substrate 11 having a thickness of 0.7 mm was subjected to ultrasonic cleaning in pure water and dried, and then further subjected to UV ozone cleaning. Color mosaic CK-7800 (manufactured by Fuji Film Electronics Materials Co., Ltd.) is applied to the cleaned glass transparent substrate 11 using a spin coating method, patterned using a photolithographic method, and a width of 0.03 mm. A black matrix 12 was formed in which a plurality of stripe-shaped portions having a thickness of 1 μm were arranged at a pitch of 0.11 mm.

Subsequently, a color mosaic CB-7001 (manufactured by Fuji Film Electronics Materials Co., Ltd.) is applied and patterned using a photolithographic method to form a plurality of stripes extending in the first direction with a width of 0.1 mm and a thickness of 1 μm. The blue color filter layer 13 in which the portion is arranged at a pitch of 0.33 mm was formed.
Subsequently, using a color mosaic CG and CR-7001 (manufactured by Fuji Film Electronics Materials Co., Ltd.), a plurality of patterns extending in the first direction having a width of 0.1 mm and a film thickness of 1 μm by patterning using a photolithographic method. A green color filter layer 14 and a red color filter layer 15 in which stripe portions are arranged at a pitch of 0.33 were sequentially formed.

Photoresist V259PA / P5 (manufactured by Nippon Steel Chemical Co., Ltd.) is applied to the transparent substrate on which the color filter layers 13, 14, 15 are formed, and irradiated with light from a high-pressure mercury lamp. A planarizing layer 16 was formed. At this time, the stripe shape of the color filter layer was not deformed, and the upper surface of the planarizing layer was flat.
A passivation layer 17 made of a 300 nm-thickness SiOx film was formed on the planarizing layer 16 by sputtering. The sputtering apparatus used was an RF-planar magnetron, and the target used Si. As a sputtering gas during film formation, a mixed gas of Ar and oxygen was used.

On the upper surface of the passivation layer 17, an anode 2 made of IZO (indium / zinc oxide) was formed on the entire surface by sputtering. Using a DC sputtering apparatus, 100 W of electric power was applied using In ₂ O ₃ -10% ZnO as a target in an Ar atmosphere at a pressure of 0.3 Pa. The film formation speed at this time was 0.33 nm / s. Subsequently, patterning is performed by a photolithography method, and further, drying processing (150 ° C.) and UV processing (mercury lamp, room temperature and 150 ° C.) are performed. A transparent electrode (anode) 2 composed of a plurality of stripe-shaped partial electrodes extending in the first direction with a film thickness of 100 nm was obtained.

Next, the substrate on which the transparent electrode is formed is mounted in a resistance heating vapor deposition apparatus, and the organic EL layer 9 composed of the hole injection layer 3, the hole transport layer 4, the light emitting layer 5 and the electron transport layer 6 is not broken. Were sequentially formed. During film formation, the internal pressure of the vacuum chamber was reduced to 1 × 10 ⁻⁴ Pa. As the hole injection layer 3, CzPP, DCJTB (5 mass%), and TBPB (25 mass%) were laminated to 200 nm. Therefore, in this embodiment, the hole injection layer 3 is a PL light-emitting carrier non-bonding layer, and TBPB is a carrier transport material having excellent carrier transfer characteristics added to the carrier non-bonding layer. As the hole transport layer 4, 20 nm of TBPB was laminated, and as the light emitting layer 5, 40 nm of DPVBi was laminated. Subsequently, an Alq3 film having a thickness of 20 nm was formed as the electron transport layer 6.

  Thereafter, LiF (as the electron injection layer 7 is used as a mask for obtaining a stripe pattern having a width of 0.3 mm and a pitch of 0.33 mm extending in the second direction orthogonal to the first direction without breaking the vacuum. Then, Al (100 nm thickness) was deposited as the cathode 8 to form a reflective electrode composed of a plurality of stripe-shaped partial electrodes, whereby an organic EL device was obtained.

The organic EL device thus obtained was moved to a dry nitrogen atmosphere (moisture concentration of 10 ppm or less) in the glove box, and sealed using a sealing glass coated with a getter agent and a UV curable adhesive.
In the organic EL device of this example, the layer structure between the anode and cathode corresponding to FIG. 1 is as follows: anode 2 / hole injection layer 3 / hole transport layer 4 / light emitting layer 5 / electron transport layer 6 / electron injection layer. 7 / cathode 8, IZO (100 nm) / CzPP, DCJTB [5 mass%], TBPB [25 mass%] (200 nm) / TBPB (20 nm) / DPVBi (40 nm) / Alq ₃ (20 nm) / LiF (1 nm ) / Al (100 nm). In this embodiment, the hole injection layer 3 is a PL light-emitting carrier non-bonding layer, and TBPB is a carrier transport material having excellent carrier transfer characteristics added to the carrier non-bonding layer.

  Table 1 shows the results of evaluating the white light emission characteristics and current efficiency of the obtained organic EL elements and evaluating the drive voltage.

The organic EL device of this example is an organic EL device according to Example 1, and the addition amount of TBPB, which is a carrier transport material with excellent carrier mobility added to the hole injection layer 3, is 5% by mass. This is an example. That is, the layer structure between the anode and cathode is anode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode, and IZO (100 nm) / CzPP, DCJTB [5 mass%. ], TBPB [5% by mass] (200 nm) / TBPB (20 nm) / DPVBi (40 nm) / Alq ₃ (20 nm) / LiF (1 nm) / Al (100 nm). The evaluation results of the obtained organic EL element are shown in Table 1.

The organic EL device of this example is an organic EL device according to Example 1, and the addition amount of TBPB, which is a carrier transport material excellent in carrier mobility added to the hole injection layer 3, is 15% by mass. This is an example. That is, the layer structure between the anode and cathode is anode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode, and IZO (100 nm) / CzPP, DCJTB [5 mass%. ], TBPB [15% by mass] (200 nm) / TBPB (20 nm) / DPVBi (40 nm) / Alq ₃ (20 nm) / LiF (1 nm) / Al (100 nm). The evaluation results of the obtained organic EL element are shown in Table 1.

The organic EL device of this example is an organic EL device according to Example 1, and the addition amount of TBPB, which is a carrier transporting material with excellent carrier mobility added to the hole injection layer 3, is 40% by mass. This is an example. That is, the layer structure of the portion between the anode and cathode is anode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode, and IZO (100 nm)) / CzPP, DCJTB [5 mass. %], TBPB [40 mass%] (200 nm) / TBPB (20 nm) / DPVBi (40 nm) / Alq ₃ (20 nm) / LiF (1 nm) / Al (100 nm). The evaluation results of the obtained organic EL element are shown in Table 1.

The organic EL device of this example is an organic EL device according to Example 1, and the addition amount of TBPB, which is a carrier transport material excellent in carrier mobility added to the hole injection layer 3, is 50% by mass. This is an example. That is, the layer structure between the anode and cathode is anode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode, and IZO (100 nm) / CzPP, DCJTB [5 mass%. ], TBPB [50% by mass] (200 nm) / TBPB (20 nm) / DPVBi (40 nm) / Alq ₃ (20 nm) / LiF (1 nm) / Al (100 nm). The evaluation results of the obtained organic EL element are shown in Table 1.
(Comparative Example 1)
The organic EL device of this example is an organic EL device according to Example 1, and the addition amount of TBPB, which is a carrier transport material excellent in carrier mobility added to the hole injection layer 3, is 2% by mass. This is an example. That is, the layer structure between the anode and cathode is anode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode, and IZO (100 nm) / CzPP, DCJTB [5 mass%. ], TBPB [2% by mass] (200 nm) / TBPB (20 nm) / DPVBi (40 nm) / Alq ₃ (20 nm) / LiF (1 nm) / Al (100 nm). The evaluation results of the obtained organic EL element are shown in Table 1.
(Comparative Example 2)
The organic EL device of this example is an organic EL device according to Example 1, and the amount of TBPB, which is a carrier transport material with excellent carrier mobility added to the hole injection layer 3, is 60% by mass. This is an example. That is, the layer structure between the anode and cathode is anode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode, and IZO (100 nm) / CzPP, DCJTB [5 mass%. ], TBPB [60% by mass] (200 nm) / TBPB (20 nm) / DPVBi (40 nm) / Alq ₃ (20 nm) / LiF (1 nm) / Al (100 nm). The evaluation results of the obtained organic EL element are shown in Table 1.

  When the organic EL elements of Examples 1 to 5 and Comparative Examples 1 and 2 were caused to emit light, each element emitted white light of CIE-xy color coordinates (x = 0.29, y = 0.31). (FIG. 2). The current efficiency at a current density of 0.1 A / cm 2 was 14 cd / A, and the spectrum did not change with the current density. Next, the voltage when a current density of 1 A / cm 2 was passed through each organic EL element was measured. The evaluation results are shown in Table 1.

表１から分るように、比較例１、２の素子は、実施例１〜５の素子よりも３Ｖ高い駆動電圧を示した。この駆動電圧の上昇はキャリア移動が円滑に行なえないためと考えられ、実施例１〜５において駆動電圧の上昇が抑えられているのは、ホール注入層がＰＬ発光性キャリア非結合層であり、該キャリア非結合層にキャリア移動特性に優れるキャリア輸送材料を特定量添加された効果であることは明らかである。

As can be seen from Table 1, the devices of Comparative Examples 1 and 2 showed a driving voltage 3 V higher than the devices of Examples 1 to 5. This increase in drive voltage is thought to be because carrier movement cannot be performed smoothly. In Examples 1 to 5, the increase in drive voltage is suppressed because the hole injection layer is a PL light-emitting carrier non-bonding layer. It is clear that this is an effect obtained by adding a specific amount of a carrier transport material having excellent carrier transfer characteristics to the carrier non-bonding layer.

It is typical sectional drawing which shows the structure of the organic EL element of this invention. It is typical sectional drawing which shows the structure of Example 1 of this invention, and an organic EL element. The EL element spectrum of Examples 1-5 and Comparative Examples 1 and 2. FIG.

Explanation of symbols

1 transparent substrate 2 anode 3 hole injection layer (hole injection host material + color conversion dye + hole transport material)
4 hole transport layer 5 light emitting layer 6 electron transport layer 7 electron injection layer 8 cathode 9 organic EL layer 11 glass transparent substrate 12 black matrix 13 blue color filter 14 green color filter 15 red color filter 16 flattening layer 17 passivation layer

Claims (4)

  An organic EL element including an organic EL layer sandwiched between a pair of electrodes, wherein the organic EL layer includes at least a carrier recombination layer and one or more carrier non-bonding layers, and the carrier recombination layer includes: One or a plurality of PL light emitting dyes that emit EL light by recombination of carriers injected into the organic EL element, and the carrier non-bonding layer emits PL light having lower energy than the host material and the EL light. An organic material, wherein the carrier transport material has a carrier mobility higher than that of the host material, and a distance between the carrier recombination layer and the carrier non-bonding layer is 15 nm or more. EL element.   The organic EL device according to claim 1, wherein the carrier non-bonding layer is a hole injection layer.   3. The organic EL element according to claim 1, wherein the EL light is blue or blue-green light having a peak wavelength of 400 nm to 500 nm.   The organic EL element according to claim 1, wherein the carrier transporting material is 5 to 50% by mass.

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