JP2008084910A - Organic el display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic EL display in which light extraction efficiency of an organic EL element developing each luminescent color can be enhanced without causing elevation in voltage or deterioration in emission efficiency. <P>SOLUTION: In the organic EL display where a plurality of organic EL elements developing different luminescent colors are arranged, the organic EL element having a peak wavelength of EL emission not less than 500 nm includes an electron injection layer consisting of a mixture layer of an organic compound and a metal or a metal compound, and the organic EL element having a peak wavelength of EL emission less than 500 nm includes an electron injection layer consisting of a thin film of an alkali metal, an alkaline earth metal, an alkali metal compound, or an alkaline earth metal compound. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an organic EL display device used for a flat panel display, a projection display, a printer, and the like.

  Organic EL elements (organic electroluminescence elements) are currently being actively researched and developed. In such an organic EL element, it is known to use an aluminum / lithium alloy or a magnesium / silver alloy for the cathode in order to improve the electron injection efficiency. It is also known that a dielectric such as lithium, lithium fluoride, magnesium oxide, or potassium fluoride is inserted very thinly (5 to 10 mm) into the electron injection layer in contact with the cathode.

  Patent Document 1 discloses a configuration in which an electron injection layer (10 to 3000 mm) having a metal that functions as a donor (electron donating) dopant is provided in contact with the cathode. As the metal used as the donor dopant, alkali metals, alkaline earth metals, transition metals including rare earths, and the like are disclosed.

  Patent Document 2 discloses a configuration in which an electron injection layer (10 to 2000 mm) having a metal oxide or metal salt as a dopant is provided in contact with a cathode.

  On the other hand, efforts are being made to improve the light extraction efficiency of organic EL elements. In Patent Document 3, an organic compound layer from the light emitting layer to the metal electrode is formed in such a film thickness that the optical distance from the light emitting interface to the metal electrode interface is substantially equal to an odd multiple of 1/4 of the wavelength. A filmed configuration is disclosed. With such a configuration, the light extraction efficiency is improved by maximizing the optical interference between the emitted light and the light reflected and returned by the metal electrode.

  Patent Document 4 discloses a configuration in which the organic compound layer is formed with a film thickness such that the optical distance between the anode and the cathode is equal to an integral multiple of ½ of the wavelength. With such a configuration, a resonator structure in which the light reflected between the anode and the cathode strengthens each other is obtained, and the light extraction efficiency is improved.

JP-A-10-270171 JP-A-10-270172 JP 2000-323277 A JP-A-4-132189

  When the light extraction efficiency is improved using the interference effect, the optimum film thickness is different for each organic EL element of RBG having a different emission wavelength. Generally, the light extraction efficiency of each color is improved by coating the film thicknesses of the hole transport layer, the light emitting layer, and the electron transport layer.

  However, in general, as the film thickness increases, the electron / hole transportability tends to decrease. In particular, in a red organic EL element having a longer peak wavelength than other colors, the voltage increases as the film thickness increases. Furthermore, there is a problem that the optimal carrier balance is lost and the luminous efficiency is lowered.

  An object of the present invention is to provide an organic EL display device capable of improving the light extraction efficiency of an organic EL element exhibiting each emission color without causing an increase in voltage or a decrease in light emission efficiency.

As means for solving the problems of the background art, an organic EL display device according to the invention described in claim 1 is:
In an organic EL display device in which a plurality of organic EL elements exhibiting different emission colors are arranged,
In the organic EL device having a peak wavelength of EL emission of 500 nm or more, the electron injection layer is a mixed layer of an organic compound and a metal or a metal compound,
An organic EL device having an EL emission peak wavelength of 500 nm or less is characterized in that the electron injection layer is made of a thin film of an alkali metal, an alkaline earth metal, an alkali metal compound, or an alkaline earth metal compound.

  According to the present invention, the electron injection layer of the organic EL device having a peak wavelength of EL emission of 500 nm or more is composed of a mixed layer of an organic compound and a metal or a metal compound. Therefore, by controlling the doping concentration, the film thickness can be set freely to some extent without increasing the voltage. In particular, in a red organic EL element having an optically optimum film thickness, the light extraction efficiency can be improved without causing a high voltage or a decrease in light emission efficiency.

  In addition, the electron injection layer of the organic EL element having a peak wavelength of EL emission of 500 nm or less is made of a thin film of an alkali (earth) metal or an alkali (earth) metal compound. Therefore, since it can be made extremely thin (5 to 10 mm), it is not necessary to make the film thickness of the other organic compound layers unnecessarily thin. In particular, in a blue organic EL element having a thin optically optimum film thickness, the light extraction efficiency can be improved without causing an increase in voltage or a decrease in light emission efficiency.

  First, the background of the inventor's achievement of the invention will be described.

  An electron injection layer composed of a mixed layer of an organic compound and a metal or a metal compound can inject electrons in the range of 10 to 3000 mm. A more practical film thickness is preferably 100 to 1000 mm. If the film thickness is within this range, the film thickness can be freely set to some extent by controlling the doping concentration without increasing the voltage. From this, as a result of the study by the present inventors, in an organic EL device having a peak wavelength of 500 nm or more, an electron injection layer composed of a mixed layer of an organic compound and a metal or a metal compound has an optically optimum film thickness. It has been found that adjustment is preferable. When film thickness control is performed only with a hole transport layer, a light emitting layer, and an electron transport layer as in the past, when the film thickness is increased, the electron / hole transportability is reduced by that amount, which may increase the voltage. is there. In particular, a red organic EL element having an optically optimum film thickness may increase the voltage. Furthermore, the optimal carrier balance may be lost, leading to a decrease in luminous efficiency.

  However, on the other hand, in an organic EL element having a peak wavelength of 500 nm or less, since the optically optimal film thickness is thin, an electron injection layer made of a thin film of an alkali (earth) metal or an alkali (earth) metal compound is provided. It is preferable to use it. Since the electron injection layer can be made extremely thin (5 to 10 mm), it is not necessary to reduce the film thickness of other organic compound layers (hole transport layer, light-emitting layer, electron transport layer) more than necessary, and freedom of material selection The degree becomes higher. When each organic material becomes thinner than the optimum film thickness, the electrical characteristics and film properties may change, resulting in a reduction in efficiency and a decrease in life.

  Further, as a result of investigation by the present inventors, an electron injection layer composed of a mixed layer of an organic compound and a metal or a metal compound sometimes exhibits a color that absorbs a spectrum of 500 nm or less depending on the combination of materials. It is thought that coloring may be exhibited by forming a metal complex between an organic compound and a metal. In order to avoid a decrease in luminance due to spectral absorption of the electron injection layer, in an organic EL device having a peak wavelength of 500 nm or less, an electron injection layer of a thin film of an alkali (earth) metal or an alkali (earth) metal compound is provided. It has been found that it is preferable to form.

<Embodiment 1>
Hereinafter, a first embodiment of the organic EL display device of the present invention will be described with reference to FIG.

  The organic EL display device shown in FIG. 1 has a transparent anode 22, a hole transport layer 3, a light emitting layer 4, an electron transport layer 5, an electron injection layer 6 (61 A, 62 A, 63 B), a reflective cathode 71 on a substrate 1. The organic EL elements of red (R), green (G), and blue (B) are provided. The light emitting layer 4 is separately applied to the R light emitting layer 41, the G light emitting layer 42, and the B light emitting layer 43 corresponding to the light emission color of each organic EL element. By passing a current through the organic EL element, the holes injected from the transparent anode 22 and the electrons injected from the reflective cathode 71 are recombined in the light emitting layer 4 to emit light.

  In the organic EL display device of the present invention, the electron injection layer of the organic EL element having a peak wavelength of 500 nm or more is composed of a mixed layer of an organic compound and a metal or a metal compound. The electron injection layer of the organic EL element having a peak wavelength of 500 nm or less is characterized by comprising a thin film of an alkali metal, an alkaline earth metal, an alkali metal compound, or an alkaline earth metal compound.

  In this embodiment, the electron injection layer 61A of the R organic EL element and the electron injection layer 62A of the G organic EL element are composed of a mixed layer of an organic compound and a metal or a metal compound. Therefore, by controlling the doping concentration, the film thickness can be set freely to some extent without increasing the voltage. In particular, in an R organic EL element (peak wavelength is 500 nm or more) in which an optically optimum film thickness is increased as in this embodiment, the light extraction efficiency can be improved without causing a high voltage or a decrease in light emission efficiency. I can do it.

  In order to improve the electron injection efficiency, the electron injection layers 61A and 62A preferably use a metal having a low work function or a compound thereof as a dopant, and the metal having a low work function may be an alkali metal, an alkaline earth metal, or a rare earth. preferable. Alkali metal compounds are preferred because they are relatively easy to handle in the atmosphere. For example, a cesium compound is preferable as the alkali metal compound, and cesium carbonate is stable in the air and easy to handle. The organic compound for the electron injection layer is preferably an electron transporting material, and a known material such as an aluminum quinolinol complex or a phenanthroline compound can be used.

  The electron injection layer 63B of the B organic EL element is made of a thin film of an alkali metal, an alkaline earth metal, an alkali metal compound, or an alkaline earth metal compound. Since the electron injection layer 63B can be made extremely thin (5 to 10 mm), it is not necessary to reduce the film thickness of other organic compound layers (hole transport layer, light emitting layer, electron transport layer) more than necessary. In particular, in the B organic EL element (peak wavelength is 500 nm or less) in which the optimum film thickness is optically thin as in this embodiment, the light extraction efficiency can be improved without causing a high voltage or a decrease in light emission efficiency. .

  The electron injection layer 63B is preferably made of lithium fluoride (LiF), potassium fluoride (KF), or magnesium oxide (MgO).

  In the organic EL display device of this embodiment, the light extraction efficiency is improved by using either one or both of the following two methods.

(1) The optical distance d between the light emitting surface of the light emitting layer 4 and the reflective cathode 71, the EL emission wavelength λ, and the phase shift amount φ (radian) at the reflective cathode 71 satisfy the following <Formula 1>. Thus, an organic compound layer is formed.
<Formula 1>
2d / λ + φ / 2π = N (integer)

  With such a configuration, the light interference between the emitted light and the light reflected and returned by the reflective cathode 71 is maximized, and the light extraction efficiency is improved.

(2) The optical distance D between the transparent anode 22 and the reflective cathode 71, the EL emission wavelength λ, the phase shift amount φ1 (radian) at the transparent anode 22, and the phase shift amount φ2 at the reflective cathode 71 The organic compound layer is formed so that (radian) satisfies the following <formula 2>.
<Formula 2>
2D / λ + (φ1 + φ2) / 2π = N (integer)

  Specifically, in the R organic EL element and the G organic EL element, the optical distance from the light emitting interface of the light emitting layers 41 and 42 to the reflective cathode 71 is substantially equal to an odd multiple of 1/4 of each RG emission wavelength. The electron injection layers 61A and 62A are formed in such a film thickness. In this case, the peak wavelength of the R organic EL element is 630 nm, and the peak wavelength of the G organic EL element is 530 nm.

  On the other hand, in the B organic EL element, the electron transport layer 5 is formed with such a film thickness that the optical distance from the light emitting interface of the light emitting layer 43 to the reflective cathode 71 is substantially equal to an odd multiple of 1/4 of the B light emission wavelength. It is a membrane. In this case, the peak wavelength of the B organic EL element is 460 nm.

  With such a configuration, a resonator structure in which the light reflected between the transparent anode 22 and the reflective cathode 71 intensifies each other is formed, and the light extraction efficiency is improved.

  In an actual organic EL display device, it is not always necessary to match the above film thickness in consideration of a viewing angle characteristic that is in a trade-off relationship with the front light extraction efficiency.

<Embodiment 2>
Next, a second embodiment of the organic EL display device of the present invention will be described with reference to FIG.

  The organic EL display device shown in FIG. 2 has substantially the same configuration as the organic EL display device of the first embodiment. However, a thin electron injection layer 63B of an alkali (earth) metal or alkali (earth) metal compound is formed so as to be in electrical contact with the reflective cathode 71 as a common film for all organic EL elements. . With such a configuration, it is not necessary to use a shadow mask when forming the electron injection layer 63B, and a process such as mask alignment can be simplified, so that throughput is improved and a manufacturing apparatus is simplified. Can do.

  In the first and second embodiments, an example of the configuration in which the transparent anode 22 is formed on the substrate 1 is shown, but the present invention is not limited to this embodiment. The cathode, organic compound layer (electron transport layer, electron injection layer, light-emitting layer, hole transport layer), and anode may be configured in this order from the substrate side. The selection of electrodes and the stacking order of organic EL elements are particularly limited. There is no. In this embodiment, a bottom emission type display device in which light emission is extracted from the substrate side is shown. However, the present invention can also be applied to a top emission type display device in which light emission is extracted from the upper electrode on the side opposite to the substrate.

  In addition, the electrode of the present invention is not particularly limited, and as a transparent electrode, a reflective electrode, a translucent electrode, an oxide conductive film such as ITO or IZO, gold, platinum, silver, aluminum, magnesium, or the like These metals, their alloys, etc., or a multilayer structure thereof. For example, in the organic EL display device shown in FIG. 1, ITO (film thickness 120 nm) is used as the transparent anode 22, and aluminum (film thickness 150 nm) is used as the reflective cathode 71.

  Hereinafter, the present invention will be described according to examples, but the present invention is not limited thereto.

<Example 1>
The configuration of the organic EL display device having three colors RGB shown in FIG. 2 will be described along the manufacturing steps. The chemical formula of the organic compound used in this example is shown in <Chemical Formula 1>. Each film thickness is shown in <Table 1>.

  On the glass substrate 1 as a support, ITO is formed to a thickness of 120 nm by a sputtering method and patterned to form the transparent anode 22. Next, an element isolation film (not shown) is formed with acrylic resin. This is subjected to ultrasonic cleaning with isopropyl alcohol (IPA) and then dried after boiling and drying. Further, after UV / ozone cleaning, an organic compound is deposited by vacuum deposition.

First, α-NPD is formed as a common hole transport layer 3 to a thickness of 40 nm by vacuum deposition. The degree of vacuum during vapor deposition is 1 × 10 ⁻⁴ Pa and the film formation rate is 0.3 nm / sec.

Next, the RGB light emitting layers 41, 42, and 43 are formed using a shadow mask. As the R light emitting layer, a light emitting layer 41 having a thickness of 30 nm is provided by co-evaporating Alq3 and a light emitting compound Ir (piq) 3 as a host (weight ratio 91: 9). As the G light emitting layer, a light emitting layer 42 having a film thickness of 30 nm is provided by co-evaporating Alq3 and a light emitting compound coumarin 6 (weight ratio 99: 1) as a host. As the B light emitting layer, a light emitting layer 43 having a thickness of 30 nm is provided by co-evaporating Balq and a light emitting compound Perylene as a host (weight ratio 90:10). The degree of vacuum during vapor deposition is 1 × 10 ⁻⁴ Pa, and the film formation rate is 0.01 to 0.1 nm / sec.

Further, bathophenanthroline (Bphen) is formed as a common electron transport layer 5 to a thickness of 10 nm by vacuum deposition. The degree of vacuum during vapor deposition is 1 × 10 ⁻⁴ Pa and the film formation rate is 0.3 nm / sec.

RG electron injection layers 61A and 62A are formed using a shadow mask. As the R electron injection layer 61A, Bphen as a host and cesium carbonate as a dopant of an alkali metal compound are formed to a thickness of 40 nm. As the G electron injection layer 62A, Bphen as a host and cesium carbonate as a dopant of an alkali metal compound are formed to a thickness of 20 nm. The degree of vacuum during the deposition of the electron injection layers 61A and 62A is 1 × 10 ⁻⁴ Pa, the film formation rate is 0.009 nm / sec for cesium carbonate, and 0.3 nm / sec for Bphen.

As the B electron injection layer 63B, a thin film of lithium fluoride (LiF) is formed to a thickness of 0.5 nm as a common film for all organic EL elements. The degree of vacuum during the deposition of the electron injection layer 63B is 1 × 10 ⁻⁴ Pa, and the film formation rate is 0.01 nm / sec.

  A reflective cathode 71 is formed by depositing aluminum (Al) having a thickness of 150 nm on the electron injection layer 63B. After forming up to the reflective cathode 71, the glove box in a nitrogen atmosphere is sealed with a glass cap (not shown) containing a desiccant to produce an organic EL display device.

A direct current voltage is applied to the organic EL display device thus obtained to measure the light emission characteristics of each color of RGB. The R organic EL element exhibits a light emission characteristic with a current density of 20.4 mA / cm ² , a luminance of 1891 cd / m ² , and a light emission efficiency of 9.4 cd / A at an applied voltage of 4.0 V. The G organic EL element exhibits light emission characteristics with a current density of 23.2 mA / cm ² , a luminance of 2560 cd / m ² , and a light emission efficiency of 11.0 cd / A at an applied voltage of 3.6 V. The B organic EL element exhibits light emission characteristics with a current density of 42.0 mA / cm ² , a luminance of 742 cd / m ² , and a light emission efficiency of 1.8 cd / A at an applied voltage of 4.3 V.

<Comparative Example 1>
In this comparative example, the film thicknesses of the electron transport layers of RGB colors are separately applied. The configuration of this comparative example is shown in FIG. Each film thickness is shown in <Table 2>.

  Organic EL display is performed in the same manner as in Example 1 except that the electron transport layers 51, 52, and 53 of RGB colors have the same electron injection layer 6B with R: 50 nm, G: 30 nm, and B: 10 nm, respectively. Make the device. As the electron injection layer 6B, a thin film of lithium fluoride (LiF) is formed to a thickness of 0.5 nm.

In the same manner as in Example 1, a direct current voltage is applied to measure the light emission characteristics of each color of RGB. The R organic EL element exhibits light emission characteristics with an applied voltage of 5.4 V, a current density of 20.1 mA / cm ² , a luminance of 998 cd / m ² , and a light emission efficiency of 5.0 cd / A. The G organic EL element exhibits light emission characteristics with an applied voltage of 4.6 V, a current density of 23.1 mA / cm ² , a luminance of 2260 cd / m ² , and a light emission efficiency of 9.8 cd / A. The B organic EL element exhibits light emission characteristics with a current density of 42.0 mA / cm ² , a luminance of 742 cd / m ² , and a light emission efficiency of 1.8 cd / A at an applied voltage of 4.3 V.

  When only the film thickness of the electron transport layer is applied, higher voltage and lower efficiency can be seen compared to Example 1.

<Example 2>
The structure of the organic EL display device having three colors RGB shown in FIG. 3 will be described along the manufacturing process. The chemical formula of the organic compound used in this example is shown in the above <Chemical Formula 1>. Each film thickness is shown in <Table 3>.

  On a glass substrate 1 as a support, an aluminum alloy (AlNiNd) as a reflective anode 21 is formed to a thickness of 100 nm by sputtering and patterned. Further, IZO as the transparent anode 22 is formed to a thickness of 20 nm by sputtering and patterned to form an anode. Next, an element isolation film (not shown) is formed from polyimide resin. This is subjected to ultrasonic cleaning with isopropyl alcohol (IPA) and then dried after boiling and drying. Further, after UV / ozone cleaning, an organic compound is deposited by vacuum deposition.

First, FL03 is formed as a common hole transport layer 3 to a thickness of 30 nm by a vacuum deposition method. The degree of vacuum during vapor deposition is 1 × 10 ⁻⁴ Pa and the film formation rate is 0.3 nm / sec.

Next, the RGB light emitting layers 41, 42, and 43 are formed using a shadow mask. As the R light emitting layer, a light emitting layer 41 having a film thickness of 40 nm is provided by co-evaporating Alq3 and a light emitting compound Ir (piq) 3 as a host (weight ratio 91: 9). As the G light emitting layer, a light emitting layer 42 having a film thickness of 30 nm is provided by co-evaporating Alq3 and a light emitting compound coumarin 6 (weight ratio 99: 1) as a host. As the B light emitting layer, a light emitting layer 43 having a thickness of 30 nm is provided by co-evaporating Balq and a light emitting compound Perylene as a host (weight ratio 90:10). The degree of vacuum during vapor deposition is 1 × 10 ⁻⁴ Pa, and the film formation rate is 0.01 to 0.1 nm / sec.

Further, bathophenanthroline (Bphen) is formed as a common electron transport layer 5 to a thickness of 10 nm by vacuum deposition. The degree of vacuum during vapor deposition is 1 × 10 ⁻⁴ Pa and the film formation rate is 0.3 nm / sec.

RG electron injection layers 61A and 62A are formed using a shadow mask. As the R electron injection layer 61A, Bphen as a host and cesium carbonate as a dopant of an alkali metal compound are formed to a thickness of 40 nm. As the G electron injection layer 62A, Bphen as a host and cesium carbonate as a dopant of an alkali metal compound are formed to a thickness of 20 nm. The degree of vacuum during the deposition of the electron injection layers 61A and 62A is 1 × 10 ⁻⁴ Pa, the film formation rate is 0.009 nm / sec for cesium carbonate, and 0.3 nm / sec for Bphen.

As the B electron injection layer 63B, a thin film of lithium fluoride (LiF) is formed to a thickness of 0.5 nm as a common film for all organic EL elements. The degree of vacuum during the deposition of the electron injection layer 63B is 1 × 10 ⁻⁴ Pa, and the film formation rate is 0.01 nm / sec.

  A 10 mg-thick silver magnesium alloy (Ag: Mg) is formed on the electron injection layer 63 to form a translucent (reflective) cathode 71. Further, the cathode is formed by forming IZO as the transparent cathode 72 to a film thickness of 60 nm by a sputtering method. After forming up to the cathode, a silicon nitride film is formed to a thickness of 1200 nm as the PV layer 8. Subsequently, an acrylic resin having a thickness of 500 μm is laminated as a resin layer 9 on the PV layer 8, and a glass plate 10 having a thickness of 700 μm is further laminated on the resin layer 9 to produce an organic EL display device.

A direct current voltage is applied to the organic EL display device thus obtained to measure the light emission characteristics of each color of RGB. The R organic EL element exhibits a light emission characteristic with a current density of 20.6 mA / cm ² , a luminance of 2023 cd / m ² , and a light emission efficiency of 9.8 cd / A at an applied voltage of 4.5V. The G organic EL element exhibits light emission characteristics with a current density of 24.0 mA / cm ² , a luminance of 2704 cd / m ² , and a light emission efficiency of 11.3 cd / A at an applied voltage of 3.6 V. The B organic EL element exhibits light emission characteristics with a current density of 40.0 mA / cm ² , a luminance of 794 cd / m ² , and a light emission efficiency of 2.0 cd / A at an applied voltage of 4.6 V.

<Comparative example 2>
In this comparative example, the film thicknesses of the electron transport layers of RGB colors are separately applied. The structure of this comparative example is shown in FIG. Each film thickness is shown in <Table 4>.

  The display device was fabricated in the same manner as in Example 2 except that the electron transport layers 51, 52, and 53 for each color of RGB had the same electron injection layer 6B with R: 50 nm, G: 30 nm, and B: 10 nm, respectively. Make it. As the electron injection layer 6B, a thin film of lithium fluoride (LiF) is formed to a thickness of 0.5 nm.

In the same manner as in Example 2, a direct current voltage is applied to measure light emission characteristics of each color of RGB. The R organic EL element exhibits light emission characteristics with a current density of 20.1 mA / cm ² , a luminance of 1048 cd / m ² , and a light emission efficiency of 5.2 cd / A at an applied voltage of 6.0 V. The G organic EL element exhibits light emission characteristics with a current density of 23.8 mA / cm ² , a luminance of 2234 cd / m ² , and a light emission efficiency of 9.4 cd / A at an applied voltage of 4.7 V. The B organic EL element exhibits light emission characteristics with a current density of 40.0 mA / cm ² , a luminance of 794 cd / m ² , and a light emission efficiency of 2.0 cd / A at an applied voltage of 4.6 V.

  In the case of coating only by the film thickness of the electron transport layer, higher voltage and lower efficiency can be seen as compared with Example 2.

  The organic EL display device of the present invention may be used for televisions, personal digital assistants, mobile phones, digital camera / digital video camera monitors, and the like.

1 is a cross-sectional view of an organic EL display device according to Embodiment 1 of the present invention. It is sectional drawing of the organic electroluminescence display which concerns on Embodiment 2 and Example 1 of this invention. It is sectional drawing of the organic electroluminescence display which concerns on Example 2 of this invention. It is sectional drawing of the organic electroluminescence display which concerns on the comparative example 1 of this invention. It is sectional drawing of the organic electroluminescence display which concerns on the comparative example 2 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 3 Hole transport layer 4 Light emitting layer 5 Electron transport layer 6 Electron injection layer 8 PV layer 9 Resin layer 10 Glass plate 21 Reflective anode 22 Transparent anode 41 Light emitting layer of red organic EL element 42 Light emitting layer of green organic EL element 43 Light-Emitting Layer 51 of Blue Organic EL Element Electron Transport Layer 52 of Red Organic EL Element Electron Transport Layer 53 of Green Organic EL Element Electron Transport Layer 61A of Blue Organic EL Element Electron Injection Layer 62A of Red Organic EL Element Electron injection layer 63B Electron injection layer 71 of blue organic EL element Reflective (semi-transparent) cathode 72 Transparent cathode

Claims (9)

In an organic EL display device in which a plurality of organic EL elements exhibiting different emission colors are arranged,
In the organic EL device having a peak wavelength of EL emission of 500 nm or more, the electron injection layer is a mixed layer of an organic compound and a metal or a metal compound,
An organic EL device having an EL emission peak wavelength of 500 nm or less is characterized in that the electron injection layer is made of a thin film of an alkali metal, an alkaline earth metal, an alkali metal compound, or an alkaline earth metal compound. Display device.   2. The organic EL display device according to claim 1, wherein the metal of the mixed layer is an alkali metal, an alkaline earth metal, or a rare earth.   The organic EL display device according to claim 1, wherein the metal compound in the mixed layer is an alkali metal compound, an alkaline earth metal compound, or a rare earth metal compound.   The organic EL display device according to claim 3, wherein the alkali metal compound is a cesium compound.   The organic EL display device according to claim 4, wherein the cesium compound is cesium carbonate.   The organic EL display device according to claim 1, wherein the thin film is lithium fluoride, potassium fluoride, or magnesium oxide.   The organic EL display device according to claim 1, wherein the thin film is formed so as to be in electrical contact with the cathode as a common film of all organic EL elements. At least one of the anode and the cathode of the organic EL element has reflectivity, and the optical distance between the reflective electrode and the light emitting surface in the light emitting layer, the EL emission wavelength, and the phase shift amount at the reflective electrode ,
<Formula 1>
2d / λ + φ / 2π = N (integer)
2. The organic EL display device according to claim 1, wherein d: optical distance, λ: EL emission wavelength, and φ (radian): phase shift amount are satisfied. At least one of the anode and the cathode of the organic EL element has translucency, the optical distance between the anode and the cathode, the EL emission wavelength, the phase shift amount at the anode, and the phase shift amount at the cathode Is
<Formula 2>
2D / λ + (φ1 + φ2) / 2π = N (integer)
Wherein D: optical distance, λ: EL emission wavelength, φ1 (radian): phase shift amount at the anode, φ2 (radian): phase shift amount at the cathode are satisfied. 8. The organic EL display device according to 8.

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