JP2010182633A - Organic electroluminescent device, manufacturing method for same, and electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic EL device which can attain suitable electron impregnation to a light-emitting material and has no variations of light-emission. <P>SOLUTION: In the organic EL device having a first light-emitting element for light-emitting a first color and a second light-emitting element for light-emitting a second color different from the first color, a negative electrode has an electron impregnating layer 52A arranged by coming in contact with an organic light-emitting layer 46, and a negative electrode layer 56 arranged at an opposite side to the organic light-emitting layer of the electron impregnating layer 52A. The electron impregnating layer 52A is formed by laminating a first impregnating layer 52a including a formation material selected from a first metal material which is alkali metal or alkaline earth metal wherein a work function is 2.9 eV or less, and a second impregnation layer 52b including a formation material selected from the first metal material and different from the first impregnating layer 52a. The first impregnating layer 52a comes in contact with the organic light-emitting layer 46, and is arranged by having a plurality of openings 52x for exposing the organic light-emitting layer 46, and the second impregnating layer 52b comes in contact with the organic light-emitting layer 46 via the plurality of openings 52x. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an organic electroluminescence device, a method for manufacturing an organic electroluminescence device, and an electronic apparatus.

  With the diversification of information equipment, the need for flat display devices that consume less power and are lighter is increasing. As one of such flat display devices, an organic electroluminescence device (hereinafter referred to as “organic EL device”) having an organic light emitting layer is known.

  In order to cause the organic EL device to emit light satisfactorily and stably drive, it is known that the structure of the cathode for injecting electrons into the organic light emitting layer has a great influence. The quality of electron injection is mainly due to the large energy level difference between the cathode and the organic light emitting layer (energy barrier), and various cathode structures have been studied to improve the electron injection. ing.

  For example, in Patent Document 1, in order to improve the electron injection property from the cathode, a base metal electrode that is in contact with the organic light emitting layer and has a low work function that facilitates electron injection into the organic light emitting layer is used. A structure in which a metal having a large function is covered and laminated is proposed.

Japanese Patent No. 2760347

  By the way, in a display device, in order to enable rich expression, it is often desired to perform full color display. The organic EL device can emit red, green, and blue light by selecting the light emitting material used for the organic light emitting layer. It has the features that it can be used efficiently and that full color display is possible with low power consumption.

  In the light emitting element provided in the organic EL device, injected holes and electrons are recombined in the light emitting material, and the HOMO (Highest Occupied Molecular Orbital) and LUMO (Lowest Unoccupied Molecular Orbital) of the light emitting material. ) According to the energy level difference. In the above-described three colors of light, the light energy decreases in the order of blue light, green light, and red light, and therefore the required energy level difference decreases in the same order. Such an energy level difference usually appears as a difference in LUMO level between light emitting materials. Therefore, in an organic EL device that emits light of a plurality of colors, a light emitting material having a plurality of LUMO levels is used at the same time. .

  However, the cathode for injecting electrons into the light emitting materials having such different LUMO levels is usually common to the entire light emitting element. Therefore, the work function of the cathode is not optimal for a plurality of light emitting materials having different LUMO levels. Therefore, an energy barrier difference occurs between the light emitting materials, and light emission unevenness occurs between the light emitting elements when the light emitting elements of a plurality of colors are driven with one driving voltage.

  The above-mentioned Patent Document 1 does not mention the problem caused by the LUMO level difference of the light emitting material used in such an organic EL device for full color display, and therefore does not disclose a solution.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide an organic electroluminescent device that realizes good electron injection into a light emitting material and has no light emission unevenness. Another object of the present invention is to provide a method for manufacturing such an organic electroluminescence device. Furthermore, it aims at providing the electronic device provided with such an organic electroluminescent apparatus together.

  In order to solve the above-described problems, the organic electroluminescence device of the present invention includes a plurality of light-emitting elements each having an organic light-emitting layer sandwiched between an anode and a cathode, and the plurality of light-emitting elements have a first color. A first light emitting element that emits light and a second light emitting element that emits a second color different from the first color, wherein the cathode is in contact with the organic light emitting layer An electron injection layer disposed on the opposite side of the electron injection layer from the organic light emitting layer, and the electron injection layer comprises an alkali metal or an alkali having a work function of 2.9 eV or less. A first injection layer including a formation material selected from a first metal material that is an earth metal and a second injection layer selected from the first metal material and including a formation material different from the first injection layer are stacked. The first injection layer has the presence It is provided with a plurality of openings exposing the organic light emitting layer while being in contact with the light emitting layer, and the second injection layer is in contact with the organic light emitting layer through the plurality of openings. To do.

  According to this configuration, the energy barrier from the cathode provided in common to the different organic light emitting layers to the LUMO level of the organic light emitting layer among the first injection layer and the second injection layer in contact with the organic light emitting layer. Good electron injection can be performed through a small injection layer. Therefore, it is possible to provide an organic electroluminescence device that reduces light emission unevenness due to an energy barrier difference between the materials for forming the organic light emitting layer and realizes high-quality display.

In the present invention, it is desirable that the material for forming the second injection layer has a work function larger than that for the material for forming the first injection layer.
According to this configuration, the first injection layer is protected by the second injection layer, the deterioration of the first injection layer is suppressed, and the life characteristics are improved.

In the present invention, a third injection layer which is an alloy layer containing two kinds of forming materials selected from the first metal material is provided between the first injection layer and the second injection layer, The material for forming the three injection layers preferably has a work function between the work function of the material for forming the first injection layer and the work function of the material for forming the second injection layer.
According to this configuration, it is possible to alleviate the energy barrier due to the work function difference between the first injection layer and the second injection layer and perform good electron injection.

  Here, in the present invention, the “alloy layer” refers to a layer formed using two or more kinds of metal materials, and the metal materials used are metal-bonded to each other. In addition, even if a clear metal bond cannot be confirmed, a layer in which an interaction between metal materials occurs and a physical property of the metal material alone is not expressed, or a layer that exhibits a physical property different from that of the metal material alone Including. In this sense, the first injection layer and the second injection layer of the electron injection layer are not alloy layers.

In the present invention, the material for forming the third injection layer preferably includes the material for forming the first injection layer and / or the second injection layer.
According to this configuration, since the materials are the same, the affinity between the first injection layer and the second injection layer is good, and it is possible to realize good electron injection between the layers. In addition, since a layer structure is formed using a common forming material, it is possible to share a manufacturing apparatus and a process, and an organic electroluminescence device having good display characteristics can be easily obtained.

In the present invention, the material for forming the first injection layer and / or the second injection layer preferably contains an inorganic salt having the first metal material as a cation.
According to this configuration, the electron injecting layer becomes more stable, and the device life is extended.

  In the present invention, the cathode layer is selected from a forming material selected from a second metal material having a work function of 3.5 eV or more and less than 4.2 eV, and a third metal material having a work function of 4.2 eV or more. And a forming material selected from the first metal material and a forming material selected from the second metal material between the second injection layer and the cathode layer. It is desirable to have a fourth injection layer that is an alloy layer.

  In the present invention, the fourth injection layer may be an alloy layer containing a forming material selected from the third metal material.

  According to these configurations, the material for forming the fourth injection layer has a work function between the work function of the material for forming the second injection layer and the work function of the material for forming the cathode layer. Therefore, by disposing the fourth injection layer, the energy barrier due to the work function difference between the second injection layer and the cathode layer can be relaxed, and good electron injection can be performed.

In the present invention, it is preferable that the metal material constituting the fourth injection layer includes a metal material constituting the second injection layer and / or the cathode layer.
According to this configuration, since the materials are common, the affinity between the second injection layer and the cathode layer is good, and it is possible to realize good electron injection between the layers. In addition, since a layer structure is formed using a common forming material, it is possible to share a manufacturing apparatus and a process, and an organic electroluminescence device having good display characteristics can be easily obtained.

In the present invention, the cathode has a resonance layer made of a formation material selected from a third metal material having a work function of 4.2 eV or more on the opposite side of the cathode layer from the electron injection layer, The anode has light transmissivity, the cathode has transflective properties, a light reflecting layer is disposed on the opposite side of the organic light emitting layer across the anode, and the light reflecting layer and the cathode It is desirable that an optical resonator structure that resonates light emitted from the organic light emitting layer is formed.
According to this configuration, by configuring an optical resonant structure that resonates light emitted from the organic light emitting layer, each organic EL element has a resonant wavelength corresponding to the optical distance between the light reflecting layer and the cathode. Only light that satisfies the condition is amplified and extracted. Therefore, for example, an organic EL device capable of high-quality full-color display is provided by forming organic EL elements having resonance wavelengths corresponding to red (R), green (G), and blue (B) colors. be able to.

In the present invention, the second metal material is preferably selected from Mg, Sc, Mn, In, Zr, and As.
According to this configuration, the energy barrier caused by the work function difference can be relaxed and good electron injection can be promoted.

In the present invention, the third metal material is preferably selected from Al, Ag, Cu, Ni, and Au.
According to this configuration, an excellent electron injection can be realized, and an alloy layer or a resonance layer that is stable against moisture and oxygen can be obtained.

In the present invention, the first metal material is preferably selected from Li, Na, K, Rb, Cs, Ca, Sr, and Ba.
According to this structure, it can be set as the electron injection layer excellent in the hole injection ability with respect to the organic light emitting layer, and can make the light emission characteristic of the organic EL device excellent.

  The method for manufacturing an organic electroluminescence device of the present invention includes a plurality of light emitting elements each having an organic light emitting layer sandwiched between an anode and a cathode, and the plurality of light emitting elements emit a first color. An electron injection layer having a first light-emitting element and a second light-emitting element that emits a second color different from the first color, and being disposed in contact with the organic light-emitting layer as the cathode; A cathode layer disposed on the side opposite to the organic light emitting layer of the electron injection layer, wherein the electron injection layer has an alkali metal or a work function of 2.9 eV or less. It has a first injection layer and a second injection layer containing a metal material that is an alkaline earth metal or an inorganic salt of the metal material as a forming material, and the metal material or the inorganic salt of the metal material has a thickness of 0.1 nm. Above 5nm Depositing a forming material different from the first injection layer on the first injection layer, and forming a second injection layer. And a step of forming.

  The first injection layer having a thin film thickness of 0.1 nm or more and 5 nm or less cannot be formed by completely covering the surface of the organic light emitting layer, and is formed by forming openings in places. Therefore, when the second injection layer is formed over the first injection layer, the second injection layer naturally comes into contact with the organic light emitting layer through the opening. Therefore, according to this method, the electron injection layer in which the first injection layer and the second injection layer are in contact with the organic light emitting layer can be easily formed.

In the present invention, it is desirable that the material for forming the first injection layer and / or the material for forming the second injection layer is an inorganic salt of Cs.
According to this method, the metal salt that is stable in the atmosphere is used as the vapor deposition material without directly handling the low work function metal material that is difficult to handle in the atmosphere, and the workability is improved. To do.

An electronic apparatus according to the present invention includes the above-described organic electroluminescence device.
According to this configuration, it is possible to provide an electronic device that includes an organic EL device that has no unevenness in light emission and can display a high-quality image.

1 is a cross-sectional view schematically showing an organic EL device according to a first embodiment of the present invention. It is explanatory drawing which shows typically the cathode structure of the organic electroluminescent apparatus which concerns on 1st Embodiment. It is process drawing which shows the manufacturing process of the organic electroluminescent apparatus of 1st Embodiment. It is explanatory drawing which shows typically the cathode structure of the organic electroluminescent apparatus which concerns on 2nd Embodiment. It is explanatory drawing which shows typically the cathode structure of the organic electroluminescent apparatus which concerns on 3rd Embodiment. It is a perspective view which shows an example of the electronic device which concerns on this invention.

[First Embodiment]
Hereinafter, an organic electroluminescence device (organic EL device) according to a first embodiment of the present invention will be described with reference to FIG. In all the drawings below, the film thicknesses and dimensional ratios of the constituent elements are appropriately changed in order to make the drawings easy to see.

  Further, as the value of the work function of the metal in the description of the present invention, values known in the literature can be used (for example, Herbert B. Michaelson, “The work function of the elements and its periodicity”, Journal of Applied Physics, November 1977, Vol.48, No.11, p.4729-p.4733).

  FIG. 1 is a cross-sectional view schematically showing the organic EL device 1. As shown in the figure, an organic EL device 1 includes a substrate 10A including a substrate body 10, and a light reflection layer 20 formed on the substrate body 10, an element layer 11 including a drive element (not shown), and the like. And a plurality of light emitting elements 60 formed on 10A. The plurality of light emitting elements 60 are formed so as to be capable of emitting red, green, and blue color lights as described later.

  On the substrate 10 </ b> A, a pixel electrode (anode) 30 that constitutes a part of the light emitting element 60, a pixel partition layer 12 that divides the plurality of light emitting elements 60, and a common partition layer 14 are formed. In a region surrounded by the common partition layer 14, a light emitting unit 40 is formed in contact with the side wall of the common partition layer 14, and a cathode 50 covering the entire upper surface of the light emitting unit 40 is formed. The pixel electrode 30, the light emitting unit 40, and the cathode 50 form an organic EL element (light emitting element) 60.

  The organic EL device 1 of the present embodiment employs a top emission method in which light generated in the organic light emitting layer 46 is emitted to the cathode 50 side. Therefore, the cathode 50 needs to be formed thin enough to have translucency, and in this embodiment, the thickness is 20 nm or less. Hereinafter, each component will be described in order.

  As the substrate body 10, either a transparent substrate or an opaque substrate can be used. Examples of opaque substrates include ceramics such as alumina, metal sheets such as stainless steel that have been subjected to insulation treatment such as surface oxidation, thermosetting resins and thermoplastic resins, and films thereof (plastic films). It is done. As the transparent substrate, for example, an inorganic substance such as glass, quartz glass, or silicon nitride, or an organic polymer (resin) such as an acrylic resin or a polycarbonate resin can be used. In addition, a composite material formed by laminating or mixing the above materials can be used as long as it has optical transparency. In the present embodiment, glass is used as the material of the substrate body 10.

  The element layer 11 includes various wirings and driving elements for driving the organic EL device 1, and an inorganic or organic insulating film formed so as to cover them. Various wirings and driving elements can be appropriately formed by patterning by photolithography and then etching, and the insulating film can be appropriately formed by a generally known method such as vapor deposition or sputtering.

  Further, a light reflection layer 20 is formed on the substrate body 10 in the element layer 11 so as to overlap the pixel electrode 30 in a plan view. The reflective layer is made of an AlNd alloy, and is formed by a generally known method such as mask patterning. In the present embodiment, the light reflecting layer 20 is formed on the substrate body 10, but may be in the element layer 11 or on the surface of the element layer 11.

  A pixel electrode 30 is formed on the element layer 11. As a material for forming the pixel electrode 30, a material having a work function of 5 eV or more can be used. Such a material is preferable as a material for forming the pixel electrode 30 because of its high hole injection effect. Examples of such a material include metal oxides such as ITO (Indium Tin Oxide). In this embodiment, ITO is used.

  Further, the pixel partition layer 12 is formed on the element layer 11 so that a part of the pixel electrode 30 runs over the end portion of the pixel electrode 30. The pixel partition layer 12 has an opening having a rectangular shape or an oval shape (track shape) in plan view, and the pixel electrode 30 is exposed in the opening. The pixel partition layer 12 is made of an inorganic insulating material such as silicon oxide or silicon nitride, and can be formed by a known method such as etching through a mask corresponding to the position of the opening.

  On the pixel partition layer 12, a common partition layer 14 is formed so as to surround the periphery of the pixel electrode 30. The common partition wall layer 14 is formed in a forward tapered shape in cross section, and the space surrounded by the common partition wall layer 14 is wider at the top than at the bottom. The common partition wall layer 14 is formed of, for example, a photocurable acrylic resin or polyimide resin.

  A light emitting section 40 is formed on the surface exposed in the bottom surface of the region surrounded by the common partition wall layer 14 (here, part of the pixel electrode 30 and the pixel partition wall layer 12). The light emitting unit 40 includes a hole injection layer 42 that facilitates injection of holes from the pixel electrode 30, a hole transport layer 44 that promotes movement of holes from the hole injection layer 42, and an organic light emitting layer 46. Are stacked on the pixel electrode 30 in this order.

  The hole injection layer 42 functions as a charge transfer layer that facilitates injection of holes from the pixel electrode 30. As a material for forming the hole injection layer 42, a generally known material can be used. In this embodiment, PEDOT / PSS is used.

  On the hole injection layer 42, a hole transport layer 44 is formed in contact with the side wall of the common partition wall layer 14. As a material for forming the hole transport layer 44, for example, ADS259BE (trade name, manufactured by American Dye Source) represented by the following chemical formula 1 can be used.

  On the hole transport layer 44, an organic light emitting layer 46 is formed in contact with the side wall of the common partition layer 14. As a forming material of the organic light emitting layer 46, a generally known material can be used. By using a forming material that develops color light as required, a light emitting element that emits different color light can be obtained.

  In the present embodiment, the organic light emitting layer 46R that emits red color light by using a red light emitting polymer material ADS111RE (product name, manufactured by American Dye Source) represented by Chemical Formula 2 as a material for forming the organic light emitting layer 46. Form. Similarly, by using the green light emitting polymer material ADS109GE (trade name, manufactured by the same company) represented by Chemical Formula 3, the organic light emitting layer 46G that emits green color light is converted into the blue light emitting polymer material ADS136BE (Formula 4). By using the company's product name), an organic light emitting layer 46B that emits blue color light is formed to enable full color display.

  A cathode 50 is formed on the organic light emitting layer 46 so as to cover the top surface and the side wall of the common partition wall layer 14. The cathode 50 includes an electron injection layer 52A that covers the top surface and side walls of the common partition wall layer 14 and covers the entire upper surface of the organic light emitting layer 46; a cathode layer 56 that covers the entire surface of the electron injection layer 52A; And a resonance layer 58 provided on the substrate.

  The electron injection layer 52 </ b> A is provided in order to perform good electron injection from the cathode layer 56 to the organic light emitting layer 46. The thickness of the electron injection layer 52A is preferably 10 nm or less in consideration of ensuring transparency and realizing good electron injection properties. The thickness of the electron injection layer 52A of this embodiment is 5 nm. The configuration of the electron injection layer 52A will be described in detail later.

  A cathode layer 56 is formed on the electron injection layer 52A so as to cover the entire surface of the electron injection layer 52A. The cathode layer 56 is an alloy formed by vacuum co-evaporation using a second metal material having a work function of 3.5 eV or more and less than 4.2 eV and a third metal material having a work function of 4.2 eV or more. Is a layer. Examples of the second metal material include Mg, Sc, Mn, In, Zr, and As, and examples of the third metal material include Al, Ag, Cu, Ni, and Au. The cathode layer 56 is connected to a cathode contact portion connected to a cathode take-out terminal (not shown). In the present embodiment, Mg is used as the second metal material, and Ag is used as the third metal material.

  The film thickness of the cathode layer 56 is preferably about 5 nm or more and 15 nm or less in consideration of ensuring transparency and ensuring good conductivity in the plane direction (low sheet resistance value), and the film thickness of the cathode 50 is 20 nm. Select a thickness such that: The cathode layer 56 of this embodiment has a thickness of 5 nm. In the present embodiment, the co-evaporation ratio of Mg and Ag is formed at a volume ratio of 10: 1.

  Further, the cathode layer 56 is an alloy layer of the second metal material and the third metal material, so that the work function lower than that of the third metal material alone, the moisture derived from the properties of the third metal material, It is a layer that combines high stability against oxygen.

  On the cathode layer 56, a resonance layer 58 made of a third metal material is provided. In this embodiment, it is formed using Ag. The resonant layer 58 is a semi-transmissive film that reflects a part of the light emitted from the organic light emitting layer 46. By forming an optical resonance structure in which the resonance layer 58 resonates light with the light reflection layer 20, the organic EL element 60 corresponds to the optical distance between the light reflection layer 20 and the resonance layer 58. Only light satisfying the resonance wavelength condition is amplified and extracted, and a good display is possible. The resonance layer 58 constitutes a part of the cathode 50 and has a function of reducing the sheet resistance value of the cathode 50. The resonance layer 58 of this embodiment has a thickness of 5 nm.

  Since the cathode 50 has the above-described laminated structure of the electron injection layer 52A, the cathode layer 56, and the resonance layer 58, satisfactory electron injection into the organic light emitting layer 46 and sufficient light transmittance of the cathode 50 necessary for top emission are achieved. And protection of the electron injection layer 52A active against moisture and oxygen can be realized at the same time. Moreover, since the sheet resistance of the cathode 50 can be made sufficiently low, light emission unevenness can also be reduced.

An inorganic film such as SiO _x N _y (not shown) is formed on the cathode 50, and a glass substrate is bonded on the inorganic film via an epoxy resin. Good.

  FIG. 2 is a schematic diagram for explaining the configuration of the electron injection layer 52A. 2A is a schematic cross-sectional view showing a laminated structure from the organic light emitting layer 46 to the resonance layer 58, and FIG. 2B is a view showing the organic light emitting layer 46 from the organic light emitting layer 46 side shown in FIG. FIG. 5 is a schematic view of the electron injection layer 52A at the interface between the electron injection layer 52A and the electron injection layer 52A.

  As shown in FIG. 2A, the electron injection layer 52A includes a first injection layer 52a formed on the organic light emitting layer 46 side and a second injection layer 52b formed on the first injection layer 52a. Have. The first injection layer 52a and the second injection layer 52b are formed by vacuum deposition using an alkali metal or an alkaline earth metal (first metal material) having a work function of 2.9 eV or less. Examples of the first metal material include Li, Na, K, Rb, Cs, Ca, Sr, and Ba. In the case where the LUMO levels of the three organic light emitting layers, ie, an organic light emitting layer capable of emitting red color light, an organic light emitting layer capable of emitting green color light, and an organic light emitting layer capable of emitting blue color light are greatly different from each other, A fifth injection layer selected from the first metal materials may be disposed on the second injection layer 52b.

  In the present embodiment, Ba (work function: 2.7) is used as the forming material of the first injection layer 52a, and Ca (work function: 2.87) is used as the forming material of the second injection layer 52b. As described above, Ba having a relatively small work function (that is, active against oxygen and moisture) is used as a material for forming the first injection layer 52a formed in the lower layer, and the second layer formed in the upper layer. By using Ca having a relatively large work function as a material for forming the injection layer 52b, the first injection layer 52a is protected by the second injection layer 52b, and the deterioration of the first injection layer 52a is suppressed, thereby reducing the lifetime. Improved characteristics.

  The film thicknesses of the first injection layer 52a and the second injection layer 52b are preferably 0.1 nm or more and 5 nm or less in consideration of ensuring transparency and realizing good electron injection properties. The film thicknesses of the first injection layer 52a and the second injection layer 52b in this embodiment are each 5 nm.

As shown in FIG. 2B, the first injection layer 52a having a very thin film thickness as described above cannot be formed to completely cover the surface of the organic light emitting layer, and the opening 52x is formed. To form a film. An organic light emitting layer (not shown) that is a base surface is exposed from the opening 52x, and the second injection layer 52b formed on the first injection layer 52a is in contact with the organic light emitting layer through the opening 52x. That is, the first injection layer 52a and the second injection layer 52b are in contact with the organic light emitting layer, and electrons are injected into the organic light emitting layer through any one of the injection layers. As described above, when the fifth injection layer is disposed on the second injection layer 52b, the second injection layer 52b has a very thin film thickness so as to have the opening 52x in the same manner as the first injection layer 52a. It is good to do. According to this, the fifth injection layer can come into contact with the organic light emitting layer which is the base surface through the opening 52x formed in each of the first and second injection layers.
The organic EL device of the present embodiment has the above configuration.

  Next, the manufacturing method of the organic EL device 1 of the present embodiment will be described with reference to FIG. In the figure, a state in which a stacked structure of the electron injection electrode 52 is formed using the vapor deposition apparatus 100A is shown. As the vapor deposition apparatus 100A, a commonly known apparatus can be used. The chamber 100 is formed to be hermetically sealed and the inside can be decompressed, the first crucible 101 containing the first vapor deposition material 111, and the second vapor deposition material 112. Has a second crucible 102 containing. In the present embodiment, Ba is used as the first vapor deposition material 111, and Ca is used as the second vapor deposition material 112.

  As shown in FIG. 3A, the organic EL device being manufactured formed up to the organic light emitting layer 46 is disposed inside the chamber 100. Then, the pressure in the chamber 100 is reduced, and the first crucible 101 containing the first vapor deposition material 111 and the second crucible 102 containing the second vapor deposition material 112 are heated by a heating device (not shown) to evaporate. A first injection layer 52a covering the organic light emitting layer 46 is formed using the first and second vapor deposition materials.

  At this time, the film thickness of the first injection layer 52a is 5 nm. As described above, the first injection layer 52a having such a very thin film thickness cannot be formed by completely covering the surface of the organic light emitting layer 46, and is formed by forming openings 52x in some places. Be filmed.

Next, as shown in FIG. 3B, when the film thickness of the first injection layer 52a reaches a predetermined film thickness, the shutter of the first crucible 101 is closed and the vapor deposition of the first vapor deposition material 111 is stopped. Then, the second deposition material 112 is deposited to form the second injection layer 52b. The second injection layer 52b is formed in contact with the organic light emitting layer 46 through the opening 52x. In this way, the electron injection electrode 52 provided in the organic EL device of this embodiment is formed.
Thereafter, a cathode structure is formed by a generally known method, and the organic EL device 1 of this embodiment is manufactured.

  According to the organic EL device 1 configured as described above, the energy of the organic light emitting layer with respect to the LUMO level of the first injection layer 52a and the second injection layer 52b in contact with the different organic light emitting layers 46R, 46G, and 46B. Electron injection can be satisfactorily performed through the injection layer having a small barrier. Therefore, it is possible to reduce the light emission unevenness due to the energy barrier difference between the materials for forming the organic light emitting layer, and to achieve the organic EL device 1 that realizes high quality display.

  In the present embodiment, the resonance layer 58 common to the plurality of organic EL elements 60 is provided. However, the resonance layer 58 is provided by patterning for each organic EL element 60 so that the organic EL element 60 emits a color. Accordingly, the thickness of the resonance layer 58 may be changed to configure the optical resonance structure. Similarly, it is also possible to configure the optical resonance structure by changing the thickness of the light reflecting layer 20 in accordance with the color emitted by the organic EL element 60.

  In the present embodiment, the electron injection layer 52A is provided with one each of the first injection layer 52a and the second injection layer 52b. However, the first injection layer 52a and the second injection layer 52b include A plurality of layers may be laminated. For example, when the first injection layer 52a and the second injection layer 52b are very thin and do not cover the surface of the organic light emitting layer 46 by simply laminating each one, the first injection layer 52a and the second injection layer 52b are alternately and repeatedly formed. The electron injection layer 52A in which a plurality of layers are alternately stacked may be used.

  In the present embodiment, Ba and Ca, which are first metal materials, are used as the forming materials for the first injection layer 52a and the second injection layer 52b, respectively, but by using an inorganic salt of the first metal material. Further, the electron injection layer can be made more stable, and the device life can be extended. When an inorganic salt of a low work function metal material that is difficult to handle in the atmosphere, such as cesium (Cs), is easy to handle because the metal salt used as a vapor deposition material is stable in the air, and high Realization of electron injection property and improvement of workability can be achieved at the same time.

  In the present embodiment, the organic EL device 1 is a top emission method, but a bottom emission method in which light generated in the organic light emitting layer 46 is emitted to the substrate 10A side may be adopted. . In that case, a design change according to the bottom emission method is performed such that the light reflection layer 20 is removed and the light-transmitting substrate 10A is used.

[Second Embodiment]
FIG. 4 is an explanatory diagram of the organic EL device 2 according to the second embodiment of the present invention, and corresponds to FIG. The organic EL device 2 of the present embodiment is partially in common with the organic EL device 1 of the first embodiment. The difference is that a third injection layer 52c, which is an alloy layer of two kinds of first metal materials, is provided between the first injection layer 52a and the second injection layer 52b of the electron injection layer 52B. Therefore, in this embodiment, the same code | symbol is attached | subjected about the component which is common in 1st Embodiment, and detailed description is abbreviate | omitted.

  The third injection layer 52c shown in FIG. 4A is an alloy layer formed by vacuum co-evaporation using two types of first metal materials. In the present embodiment, Ba, which is the same as the formation material of the first injection layer 52a, and Ca, which is the same as the formation material of the second injection layer 52b, are used as the formation material of the third injection layer 52c.

  The co-evaporation ratio of Ba and Ca constituting the third injection layer 52c is not particularly limited, but the value of the work function of the third injection layer 52c is that of the first injection layer 52a and the second injection layer 52b. It is desirable that the co-evaporation ratio shows a work function value between. In this embodiment, the volume ratio is set to 1: 1 in order to realize good electron injection from the second injection layer 52b to the first injection layer 52a. By disposing the third injection layer 52c having such a co-evaporation ratio, the work function difference between the first injection layer 52a and the second injection layer 52b is alleviated, and the second injection layer 52b to the first injection layer 52a. Good electron injection can be performed.

As shown in FIG. 4B, the first injection layer 52a has an opening 52x in which the organic light emitting layer 46 as a base surface is exposed, and a third injection layer 52a is formed on the first injection layer 52a. The injection layer 52c comes into contact with the organic light emitting layer 46 through the opening 52x. That is, the organic light emitting layer 46 is in contact with the first injection layer 52a and the third injection layer 52c, and electrons are injected into the organic light emitting layer 46 through any one of the injection layers.
The organic EL device 2 of the present embodiment has the above configuration.

  In the organic EL device 2 having the above-described configuration, the third injection layer 52c relaxes the energy barrier due to the work function difference between the first injection layer 52a and the second injection layer 52b. Can be achieved, and good luminous efficiency can be realized.

  In the present embodiment, since the metal material common to the first injection layer 52a and the second injection layer 52b is used as the material for forming the third injection layer 52c, the affinity between the layers is good and good electrons are obtained. It can be set as the cathode 50 provided with the layer structure which implement | achieves injection | pouring. Moreover, since the formation material of each layer of the electron injection layer 52B is common, the formation material to be used can be reduced.

  In the present embodiment, the material used to form the third injection layer 52c is the same metal material as the material used to form the first injection layer 52a and the second injection layer 52b, but is not limited thereto. For example, the forming material may be shared only with one of the injection layers, or a first metal material different from any of the injection layers may be used.

  In the present embodiment, the third injection layer 52c is provided between the first injection layer 52a and the second injection layer 52b. However, when the fifth injection layer is formed on the second injection layer 52b. May include a sixth injection layer that is an alloy layer of two kinds of first metal materials between the second injection layer 52b and the fifth injection layer. At this time, as the material of the sixth injection layer, two kinds of metal materials, that is, the same material as the formation material of the second injection layer 52b and the same material as the formation material of the fifth injection layer may be used.

[Third Embodiment]
FIG. 5 is an explanatory diagram of the organic EL device 3 according to the third embodiment of the present invention, and corresponds to FIG. The organic EL device 3 of the present embodiment is partially in common with the organic EL device 1 of the first embodiment. The difference is that a fourth injection layer 52d, which is an alloy layer of the first metal material and the second metal material, is provided between the second injection layer 52b and the cathode layer 56 of the electron injection layer 52C. Therefore, in this embodiment, the same code | symbol is attached | subjected about the component which is common in 1st Embodiment, and detailed description is abbreviate | omitted.

  The fourth injection layer 52d is an alloy layer formed by vacuum co-evaporation using the first metal material and the second metal material. In the present embodiment, the first metal material used for the material for forming the fourth injection layer 52d is Ca, as is the first metal material for forming the second injection layer 52b, and the second metal material is the cathode layer 56. It is Mg similarly to the 2nd metal material which is a formation material of this.

  The co-evaporation ratio of Ca and Mg in the fourth injection layer 52d is not particularly limited, but in order to achieve good electron injection from the cathode layer 56 to the second injection layer 52b, the fourth injection layer 52d It is desirable that the work function value is a co-evaporation ratio indicating the work function value between the second injection layer 52 b and the cathode layer 56. In this embodiment, the volume ratio is Ca: Mg = 1: 10. By disposing the fourth injection layer 52d having such a co-evaporation ratio, the work function difference between the second injection layer 52b and the cathode layer 56 can be relaxed, and good electron injection can be performed.

  In the organic EL device 3 configured as described above, the work function difference between the second injection layer 52d and the cathode layer 56 is obtained by disposing the fourth injection layer 52d between the second injection layer 52d and the cathode layer 56. Can be relaxed and good electron injection can be performed.

  In the present embodiment, since the metal material constituting the fourth injection layer 52d is formed of the same material as the metal material constituting the second injection layer 52b and the cathode layer 56, the affinity between the layers is good. Thus, the cathode 50 having a layer structure that realizes good electron injection can be obtained. Moreover, the required forming material can be reduced and each layer can be formed continuously.

  In the present embodiment, the fourth injection layer 52d is formed using the same metal material as the second injection layer 52b and the cathode layer 56, but is not limited thereto. For example, the forming material may be shared only with one of the cathode layers, or a metal material different from any of the cathode layers may be used.

  In the present embodiment, the fourth injection layer 52d is an alloy layer of the first metal material and the second metal material. However, the fourth injection layer 52d includes the first metal material and the second metal material. It may be an alloy layer with a third metal material.

  For example, the first metal material used for the material for forming the fourth injection layer 52d is Ca, similar to the material for forming the second injection layer 52b, and the second metal material used for the material for forming the fourth injection layer 52d is The material for forming the cathode layer 56 is Mg, and the third metal material is Ag, the same as the material for forming the cathode layer 56. The co-evaporation ratio of the fourth injection layer 52d can be exemplified by a volume ratio of Ca: Mg: Ag = 1: 10: 1.

  The fourth injection layer 52d is an alloy layer with a third metal material that is stable against moisture and oxygen, and is stable against moisture and oxygen. Therefore, the organic EL device 3 having high stability and high reliability can be obtained.

[Electronics]
Next, an embodiment of the electronic device of the present invention will be described. FIG. 6 is a perspective view showing an example of an electronic apparatus using the organic EL device of the present invention. A cellular phone (electronic device) 1300 illustrated in FIG. 6 includes the organic EL device of the present invention as a small-sized display unit 1301 and includes a plurality of operation buttons 1302, an earpiece 1303, and a mouthpiece 1304. Yes. Thereby, the mobile phone 1300 provided with the display part without the light emission nonuniformity comprised by the organic electroluminescent apparatus of this invention can be provided.

  The organic EL device of each of the above embodiments is not limited to the mobile phone, but is an electronic book, a projector, a personal computer, a digital still camera, a television receiver, a viewfinder type or a monitor direct view type video tape recorder, and a car navigation device. , Pagers, electronic notebooks, calculators, word processors, workstations, videophones, POS terminals, devices equipped with touch panels, and the like. With this configuration, an electronic device including a display portion with high display quality and excellent reliability can be provided.

  Furthermore, the organic EL device of each of the above embodiments can be used as a line head, and can be suitably used as an image forming apparatus (optical printer) including the line head as a light source. In this way, it is possible to obtain an optical printer having no light emission unevenness and excellent reliability.

  The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, but it goes without saying that the present invention is not limited to such examples. Various shapes, combinations, and the like of the constituent members shown in the above-described examples are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

1, 2, 3 ... Organic EL device (organic electroluminescence device), 20 ... Light reflecting layer, 30 ... Pixel electrode (anode), 46, 46R, 46G, 46B ... Organic light emitting layer, 50 ... Cathode, 52, 52A, 52B, 52C ... electron injection layer, 52a ... first injection layer, 52b ... second injection layer, 52c ... third injection layer, 52d ... fourth injection layer, 52x ... opening, 56 ... cathode layer, 58 ... resonance layer , 60, 60R, 60G, 60B ... organic EL element (light emitting element), 1300 ... mobile phone (electronic device),

Claims (15)

A plurality of light-emitting elements each having an organic light-emitting layer sandwiched between an anode and a cathode, wherein the plurality of light-emitting elements are different from the first light-emitting element that emits a first color and the first color; An organic electroluminescence device having a second light emitting element that emits two colors,
The cathode comprises an electron injection layer disposed in contact with the organic light emitting layer, and a cathode layer disposed on the opposite side of the electron injection layer from the organic light emitting layer,
The electron injection layer is selected from a first injection layer including a forming material selected from a first metal material which is an alkali metal or an alkaline earth metal having a work function of 2.9 eV or less, and the first metal material is selected from the first metal material. A second injection layer containing a different formation material from the one injection layer, and
The first injection layer is provided with a plurality of openings that are in contact with the organic light emitting layer and expose the organic light emitting layer, and the second injection layer is provided with the organic light emission through the openings. An organic electroluminescence device characterized by being in contact with a layer.   The organic electroluminescence device according to claim 1, wherein the forming material of the second injection layer has a work function larger than that of the forming material of the first injection layer. Between the first injection layer and the second injection layer, there is a third injection layer that is an alloy layer containing two kinds of forming materials selected from the first metal material,
The material for forming the third injection layer has a work function between a work function of the material for forming the first injection layer and a work function of the material for forming the second injection layer. 3. The organic electroluminescence device according to any one of 1 and 2.   4. The organic electroluminescence device according to claim 3, wherein the material for forming the third injection layer includes the material for forming the first injection layer and / or the second injection layer.   The organic material according to any one of claims 1 to 4, wherein a material for forming the first injection layer and / or the second injection layer includes an inorganic salt having the first metal material as a cation. Electroluminescence device. The cathode layer includes a forming material selected from a second metal material having a work function of 3.5 eV or more and less than 4.2 eV, and a forming material selected from a third metal material having a work function of 4.2 eV or more. An alloy layer,
Between the 2nd injection layer and the cathode layer, it has the 4th injection layer which is an alloy layer containing the formation material chosen from the 1st metal material, and the formation material chosen from the 2nd metal material The organic electroluminescence device according to any one of claims 1 to 5, wherein   The organic electroluminescence device according to claim 6, wherein the fourth injection layer is an alloy layer containing a forming material selected from the third metal material.   8. The organic electroluminescence device according to claim 6, wherein the metal material forming the fourth injection layer includes a metal material forming the second injection layer and / or the cathode layer. 9. The cathode has a resonance layer made of a forming material selected from a third metal material having a work function of 4.2 eV or more on the opposite side of the cathode layer from the electron injection layer,
The anode has light transmissivity, the cathode has transflective properties, a light reflecting layer is disposed on the opposite side of the organic light emitting layer across the anode, and the light reflecting layer, the cathode, The organic electroluminescent device according to claim 1, wherein an optical resonator structure that resonates light emitted from the organic light emitting layer is formed.   The organic electroluminescence device according to any one of claims 6 to 8, wherein the second metal material is selected from Mg, Sc, Mn, In, Zr, and As.   11. The organic electroluminescence device according to claim 6, wherein the third metal material is selected from Al, Ag, Cu, Ni, and Au.   The organic electroluminescence device according to any one of claims 1 to 11, wherein the first metal material is selected from Li, Na, K, Rb, Cs, Ca, Sr, and Ba. A plurality of light emitting elements each having an organic light emitting layer sandwiched between an anode and a cathode, wherein the plurality of light emitting elements are different from the first light emitting element that emits a first color and the first color. A second light-emitting element that emits a second color, the electron injection layer disposed in contact with the organic light-emitting layer as the cathode, and disposed on the opposite side of the organic light-emitting layer of the electron injection layer A cathode layer, and a method for producing an organic electroluminescence device comprising:
The electron injection layer has a first injection layer and a second injection layer containing a metal material which is an alkali metal or an alkaline earth metal having a work function of 2.9 eV or less, or an inorganic salt of the metal material as a forming material. ,
Depositing the metal material or an inorganic salt of the metal material with a film thickness of 0.1 nm or more and 5 nm or less to form a first injection layer;
Depositing a forming material different from the first injection layer on the first injection layer to form a second injection layer, wherein the metal material or an inorganic salt of the metal material is formed. A method for manufacturing an organic electroluminescence device.   The method for manufacturing an organic electroluminescence device according to claim 13, wherein the forming material of the first injection layer and / or the forming material of the second injection layer is an inorganic salt of Cs.   An electronic apparatus comprising the organic electroluminescence device according to claim 1.

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