WO2017212852A1

WO2017212852A1 - Organic electroluminescent element and lighting fixture for vehicles

Info

Publication number: WO2017212852A1
Application number: PCT/JP2017/017675
Authority: WO
Inventors: 一樹加藤; 松村　智之
Original assignee: コニカミノルタ株式会社
Priority date: 2016-06-06
Filing date: 2017-05-10
Publication date: 2017-12-14
Also published as: JPWO2017212852A1; JP6913088B2

Abstract

An organic electroluminescent element which is provided with: a flexible substrate; a first electrode layer that is arranged on the flexible substrate; a second electrode layer that is arranged above the first electrode layer; at least two light emitting units which are laminated and arranged between the first electrode layer and the second electrode layer, and each of which has a light emitting layer configured using an organic material; and an intermediate electrode layer that is arranged between the light emitting units. The at least two light emitting units are different from each other in the chromaticity of emitted light; and with respect to the light distribution characteristics of emitted light extracted from at least one light emitting unit among the at least two light emitting units toward the flexible substrate side or the second electrode layer side, if [L1] is the front luminance, [L2] is the luminance at the viewing angle of 20° and [L3] is the luminance at the viewing angle of 60°, 0.85 ≤ [L2]/[L1] ≤ 1.20 and [L3]/[L1] ≤ 0.50 are satisfied.

Description

Organic electroluminescence device and vehicle lamp

The present invention relates to an organic electroluminescence element and a vehicular lamp using the organic electroluminescence element.

Conventionally, an organic EL element using a light emitting material that realizes high luminous efficiency by using all of singlet excitons and triplet excitons for electroluminescence (hereinafter also referred to as EL) has been proposed. In the organic EL element, a material in a practical range has been developed with both high light emission efficiency and light emission lifetime, and is used for display and illumination.

In recent years, it has been proposed to apply characteristics such as surface light emission and flexibility of an organic EL element to a vehicular lamp (for example, a tail lamp) having high design (see, for example, Patent Document 1). ).

However, when a conventional organic EL element is used for a vehicle lamp, there is a problem that visibility from a rear vehicle is low. Therefore, an organic EL element having high visibility from the rear vehicle is required.

Japanese Patent Laying-Open No. 2015-5552

As a result of diligent efforts by the inventor with respect to the above problems, the following was found.

When mounting an organic EL element, which is a surface light source, on a vehicle in a curved state, strong light emission from the curved portion is required to ensure visibility to the following vehicle and uniformity of brightness. Become. For this reason, it has been found that not only the front surface but also the emitted light intensity up to a viewing angle of about 20 ° is required. On the other hand, it was found that the intensity of emitted light from a viewing angle of 60 ° to 90 ° is not required from the viewpoint of visibility to the following vehicle and uniformity of brightness. Conventionally known organic EL elements can obtain a certain level of visibility even when the emitted light is viewed from any direction, but there is a lot of emitted light near a viewing angle of 60 ° to 90 °, which is useless. There was also a lot of emitted light.

The present invention has been made in view of the above problems and situations, and provides an organic electroluminescence element having high visibility suitable for a vehicle lamp, and visibility by using this organic electroluminescence element. An object of the present invention is to provide an improved vehicular lamp.

To achieve the above object, the present invention includes a flexible substrate, a first electrode layer provided on the flexible substrate, a second electrode layer provided above the first electrode layer, an organic At least two light emitting units having a light emitting layer made of a material and disposed so as to overlap each other between the first electrode layer and the second electrode layer, and an intermediate electrode layer disposed between the light emitting units And the at least two light emitting units have different chromaticities of the respective emitted light, and at least one of the at least two light emitting units is connected to the flexible substrate side or the second light emitting unit. When the light distribution characteristic of the emitted light extracted to the electrode layer side is [L1] for the front luminance, [L2] for the luminance at a viewing angle of 20 °, and [L3] for the luminance at a viewing angle of 60 °. 85 ≦ [L2 ] / [L1] ≦ 1.20 and [L3] / [L1] ≦ 0.50. Moreover, this invention is also a vehicle lamp using such an organic electroluminescent element.

According to the present invention having such a configuration, it is possible to obtain an organic electroluminescence element having high visibility suitable for a vehicle lamp, and the use of this organic electroluminescence element improves visibility. The obtained vehicle lamp can be obtained.

It is sectional drawing which shows the outline of the organic electroluminescent element which concerns on embodiment. It is a schematic diagram for demonstrating the light distribution characteristic of the organic electroluminescent element which concerns on embodiment. It is a top view of the vehicle for demonstrating schematic structure of the vehicle lamp which concerns on embodiment.

Hereinafter, embodiments of the present invention will be described in the order of an organic electroluminescence element and a vehicular lamp using the organic electroluminescence element. In the embodiments described below, “˜” is used in the sense of including numerical values described before and after it as lower and upper limits.

≪Organic electroluminescence element≫
FIG. 1 is a cross-sectional view schematically showing an organic electroluminescence element 1 according to the embodiment. As shown in this figure, the organic electroluminescence element 1 includes a flexible substrate 10, a first electrode layer 11, a first light emitting unit 21, an intermediate electrode layer 30, a second light emitting unit 22, and a second electrode layer 12 in this order. It is a laminated tandem structure. Is this organic electroluminescence device 1 of the bottom emission type that extracts the emitted light h1 and the emitted light h2 generated by the first light emitting unit 21 and the second light emitting unit 22 from the flexible substrate 10 side as shown in the figure? Alternatively, the top emission type may be taken out from the reverse.

Here, a bottom emission type organic electroluminescence element 1 as illustrated as an example will be described. In this case, the first electrode layer 11 and the intermediate electrode layer 30 on the light extraction side are configured as transparent electrodes having optical transparency. If the emitted light h1 and h2 are extracted by interference due to the microcavity effect, the first electrode layer 11 and the intermediate electrode layer 30 are configured as electrodes having transflective properties. On the other hand, the second electrode layer 12 is configured as a reflective electrode.

In the organic electroluminescence element 1 according to the embodiment, a voltage is applied from the external power source to the first electrode layer 11 and the intermediate electrode layer 30, and thereby, emitted light h 1 is generated in the first light emitting unit 21. In addition, a voltage is applied from the external power source to the intermediate electrode layer 30 and the second electrode layer 12, whereby emitted light h 2 is generated in the second light emitting unit 22. Generation of the emitted light h 1 and the emitted light h 2 is individually controlled by adjusting voltage application to the first electrode layer 11, the intermediate electrode layer 30, and the second electrode layer 12.

Here, as described above, the first electrode layer 11, the second electrode layer 12, and the intermediate electrode layer 30 to which a voltage is applied by being connected to an external power source needs to suppress sheet resistance to some extent. Therefore, the first electrode layer 11 and the intermediate electrode layer 30 configured to have light transmittance need to have a certain thickness, and thus are configured as semi-transmissive and semi-reflective electrodes.

In the organic electroluminescence element 1 having such a configuration, the emitted light h1 generated by the first light emitting unit 21 and the emitted light h2 generated by the second light emitting unit 22 have different chromaticities. The emitted light h1 and the emitted light h2 are also different in maximum peak wavelength. The difference between the emitted light h1 and the emitted light h2 is due to the difference in the configuration of the first light emitting unit 21 and the second light emitting unit 22, and will be described in detail later.

The organic electroluminescent element 1 including the first light emitting unit 21 and the second light emitting unit 22 as described above emits light extracted from the light extraction surface S when the outermost surface on the flexible substrate 10 side is the light extraction surface S. The light distribution characteristics of the lights h1 and h2 are characteristic. Further, the chromaticity of the emitted lights h1 and h2 is also characteristic. Hereinafter, the light distribution characteristics of the emitted lights h1 and h2, the chromaticity of the emitted lights h1 and h2, and the details of the components constituting the organic electroluminescent element 1 will be described in this order.

<Light distribution characteristics of emitted light h1 and h2>
At least one of the emitted light h1 and the emitted light h2 has the following light distribution characteristics. That is, the normal N direction of the light extraction surface S is the front, the front luminance is [L1], the luminance at a viewing angle of 20 ° with respect to the normal N is [L2], and the luminance at a viewing angle of 60 ° with respect to the normal [N]. Let [L3]. In this case, the light distribution characteristics of at least one of the emitted light h1 and the emitted light h2 are 0.85 ≦ [L2] / [L1] ≦ 1.20 and [L3] / [L1] ≦ 0.50. It is.

The above is the same even when the light extraction surface S is curved as shown in FIG. 2, and at each part of the light extraction surface S curved in the convex direction, at least the emitted light h1 and the emitted light h2 One light distribution characteristic is assumed to hold the above-described relationship.

When this relationship is established, for example, when the organic electroluminescence element 1 is provided as a vehicular lamp at the rear corner portion of the vehicle, for example, with the light extraction surface S curved in a convex direction, the vehicle is moved backward. It is possible to make uniform the extraction intensity of the emitted lights h1 and h2 on the light extraction surface S when viewed from the vehicle. This also makes it possible to improve the visibility of the emitted lights h1 and h2 when the vehicle is viewed from the rear vehicle. More specifically, if the emitted light h1 satisfies the above relationship, such an effect can be obtained for the emitted light h1, and if the emitted light h2 satisfies the above relationship, the emitted light h2 can be obtained. Such an effect can be obtained.

The light distribution characteristics as described above are preferably 0.90 ≦ [L2] / [L1] ≦ 1.10 and [L3] / [L1] ≦ 0.45. The effect of can be further enhanced. Moreover, it is preferable that the above light distribution characteristics are provided for both the emitted light h1 and the emitted light h2.

The light distribution characteristic of the organic electroluminescence element 1 according to the embodiment is a light distribution shape having a light distribution degree in the normal N direction stronger than Lambertian which is the intensity of light from the uniform diffusion light source. Alternatively, the light distribution shape may be weak. Table 1 below shows, as an example of the light distribution characteristics of the organic electroluminescence element 1 according to the embodiment, the light distribution shapes 1 and 2 and the distribution in the normal N direction when the degree of light distribution in the normal N direction is strong. Examples of [L2] / [L1] and [L3] / [L1] for the light distribution shapes 3 and 4 when the degree of light is weak are shown. However, the light distribution shape 1 has a strong light distribution degree in the normal N direction, and the value of [L2] / [L1] is out of the range of 0.85 ≦ [L2] / [L1] ≦ 1.20.

[Brightness measurement method]
As a method for measuring the luminance [L1] to [L3] for obtaining the above-mentioned light distribution characteristics, the following method can be used.

Luminance [L1] to [L3] is set by setting the organic electroluminescence device 1 on a rotating stage that automatically rotates and measuring the light intensity distribution and spectrum using a spectral luminance meter (CS-2000, manufactured by Konica Minolta). Can be requested. These measurements are performed with respect to the normal line N in a state in which each of the first light emitting unit 21 and the second light emitting unit 22 is caused to emit light by individually flowing a constant current amount (5 mA / cm ² ). It is carried out in the range of 80 °. Among the measurement results, the luminance values [L1] to [L3] are measured from the measured value in the normal [N] direction, the measured value at a viewing angle of 20 ° with respect to the normal N, and the measured value at a viewing angle of 60 ° with respect to the normal N. ].

[Brightness adjustment method]
Examples of a method for adjusting the luminance [L1] to [L3] of the emitted lights h1 and h2 within the range of the above light distribution characteristics include the following two methods.

The first method uses a microcavity effect between the first electrode layer 11, the intermediate electrode layer 30, and the second electrode layer 12. In this case, from the light emitting points D1 and D2 in the first light emitting unit 21 and the second light emitting unit 22, depending on the film thickness design of each layer constituting the first light emitting unit 21 and the second light emitting unit 22, and further the intermediate electrode layer 30. The distances to the first electrode layer 11, the intermediate electrode layer 30, and the second electrode layer 12 are adjusted. Thereby, the emitted lights h1 and h2 of each emission wavelength are taken out from the light extraction surface S by causing interference between the first electrode layer 11, the intermediate electrode layer 30, and the second electrode layer 12.

At this time, the directivity in the light extraction direction is adjusted by adjusting the degree of interference between the emitted lights h1 and h2 according to the thickness design of each layer constituting the first light emitting unit 21 and the second light emitting unit 22 and the intermediate electrode layer 30. Is controlled. Thereby, the luminances [L1] to [L3] of the emitted lights h1 and h2 are adjusted so as to satisfy the above-described light distribution characteristics.

The second method is a method of providing an optical film, not shown here, on the light extraction surface S side of the organic electroluminescence element 1. The optical film is made of a translucent resin material, for example, a microlens array or dot pattern having a plurality of convex portions, or a sheet-like optical film or optical sheet having a diffraction grating or an uneven structure, or an optical multilayer having different refractive indexes. An optical film made of a film can be used.

However, when an optical film having sufficient transmittance cannot be prepared, the luminance [L1] to [L3] of the emitted lights h1 and h2 is obtained by applying the first method described above to the above light distribution characteristics. It is preferable to adjust within the range.

<Chromaticity of emitted light h1, h2>
Regarding the chromaticity of the emitted light h1 and the emitted light h2, it is preferable that one of them is red and the other is amber. More preferably, the emitted light h1 from the first light emitting unit 21 disposed on the light extraction side is set to the longer wavelength red emitted light, while the second light emitting unit 22 disposed on the second electrode layer 12 side. The emitted light h 2 from the light is preferably amber-colored light having a shorter wavelength. As a result, it is possible to suppress the attenuation due to plasmon absorption of red having a long wavelength, so that high efficiency is expected as an organic electroluminescence element.

The chromaticity of the organic electroluminescence element of the present invention is not particularly limited, and various ranges of chromaticity can be applied. When applied as a vehicular lamp, red and amber are preferred. Here, the red emitted light preferably has a front chromaticity of 0.29 ≦ y ≦ 0.34 and y + x ≧ 0.98 in the CIE-xy chromaticity diagram. The amber-colored emitted light preferably satisfies y ≧ 0.39, y ≧ 0.79−0.67x, and y ≦ x−0.12 in the CIE-xy chromaticity diagram. Note that x and y in the chromaticity range are chromaticity x and y in the CIE 1931 color system.

[Measurement method of chromaticity]
The chromaticity of the emitted lights h1 and h2 can be measured using, for example, a spectral radiance meter CS-2000 (manufactured by Konica Minolta). At this time, each of the first light emitting unit 21 and the second light emitting unit 22 is individually given a predetermined current density, and the chromaticities of the generated emitted lights h1 and h2 are measured.

The front luminance [L1] of the organic electroluminescent device of the present invention can be arbitrarily adjusted depending on the area to be used and is not particularly limited, but can be applied in the range of 100 to 50000 cd / m ² , for example.

<Details of each component of organic electroluminescence element 1>
Next, the detail of each component of the organic electroluminescent element 1 which has the above light distribution characteristics is demonstrated. In addition, each component of the organic electroluminescence element 1 described below is an example for describing the embodiment, and any one of the emitted light h1 and the emitted light h2 having the above-described light distribution characteristics and chromaticity is included. Other configurations can be applied as appropriate within the range obtained.

[First electrode layer 11 and second electrode layer 12]
Each of the first electrode layer 11 and the second electrode layer 12 serves as an anode for supplying holes to the first light emitting unit 21 or the second light emitting unit 22 sandwiched between the first electrode layer 11 and the intermediate electrode layer 30. It functions as a cathode for supplying electrons.

Taking the first electrode layer 11 as an example, one of the first electrode layer 11 and the intermediate electrode layer 30 functions as an anode for supplying holes to the first light emitting unit 21, and the other is the first. It functions as a cathode for supplying electrons to one light emitting unit 21. Here, as an example, the case where the first electrode layer 11 is used as an anode and the intermediate electrode layer 30 is used as a cathode for the first light emitting unit 21 is illustrated.

Taking the second electrode layer 12 as an example, one of the second electrode layer 12 and the intermediate electrode layer 30 functions as an anode for supplying holes to the second light emitting unit 22, and the other is It functions as a cathode for supplying electrons to the second light emitting unit 22. Here, as an example, the case where the second light emitting unit 22 is used with the second electrode layer 12 as a cathode and the intermediate electrode layer 30 as an anode is illustrated.

The first electrode layer 11 and the second electrode layer 12 as described above are configured using materials suitable for each as shown below, depending on whether they are used as an anode or a cathode. Further, the first electrode layer 11 and the second electrode layer 12 are selected from materials having excellent light transmittance or light reflectivity from the following materials depending on whether or not the electrodes are arranged on the light extraction side. Used. Below, the anode and cathode which comprise the 1st electrode layer 11 or the 2nd electrode layer 12 are demonstrated.

(anode)
As an anode material used for the organic electroluminescent element 1, an electrode material made of a metal, an alloy, an electrically conductive compound, and a mixture thereof having a high work function (4 eV or more, preferably 4.3 V or more) is used. Specific examples of such an electrode substance include metals such as Au and Ag, alloys thereof, and conductive transparent materials such as CuI, indium titanium oxide (ITO), SnO ₂ , and ZnO. Alternatively, an amorphous material such as IDIXO (registered trademark: In ₂ O ₃ —ZnO) that can form a transparent conductive film may be used.

The anode can be produced by depositing the anode material on a substrate using a method such as vapor deposition or sputtering. In the case where the emitted light is extracted from the anode side, the transmittance of the anode is set to be greater than 10%, or a semi-transmissive / semi-reflective electrode is formed. The sheet resistance of the anode is several hundred Ω / sq. The following is preferred. The thickness of the anode is usually selected in the range of 10 nm to 1 μm, preferably 10 to 200 nm, although it depends on the material.

(cathode)
As a cathode material used for the organic electroluminescence element 1, an electrode substance made of a metal, an alloy, an electrically conductive compound, and a mixture thereof having a small work function (4 eV or less) is used. Specific examples of such electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al ₂ O ₃ ) Mixtures, indium, lithium / aluminum mixtures, aluminum, silver, silver-based alloys, aluminum / silver mixtures, rare earth metals, and the like.

The cathode can be produced by depositing the cathode material on a substrate using a method such as vapor deposition or sputtering. In the case where emitted light is extracted from the cathode side, the transmittance of the cathode is made larger than 10%, or a semi-transmissive and semi-reflective electrode is used. The sheet resistance of the cathode is several hundred Ω / sq. The following is preferred. The thickness of the cathode is usually selected in the range of 10 nm to 5 μm, preferably 50 to 200 nm.

[First light emitting unit 21, second light emitting unit 22]
The first light emitting unit 21 includes at least one light emitting layer that is provided between the first electrode layer 11 and the intermediate electrode layer 30 and contains a light emitting organic material. The second light emitting unit 22 includes at least one light emitting layer that is provided between the intermediate electrode layer 30 and the second electrode layer 12 and contains an organic material having a light emitting property.

Hereinafter, the first light emitting unit 21 and the second light emitting unit 22 will be collectively described as a light emitting unit.

Typical layer configurations of the light emitting unit include the following configurations, but are not limited thereto.
(1) Hole injection transport layer / light emitting layer / electron injection transport layer (2) Hole injection transport layer / light emitting layer / hole blocking layer / electron injection transport layer (3) Hole injection transport layer / electron blocking layer / Light emitting layer / hole blocking layer / electron injecting and transporting layer (4) hole injecting layer / hole transporting layer / light emitting layer / electron transporting layer / electron injecting layer (5) hole injecting layer / hole transporting layer / light emitting layer / Hole blocking layer / electron transport layer / electron injection layer (6) hole injection layer / hole transport layer / electron blocking layer / light emitting layer / hole blocking layer / electron transport layer / electron injection layer

Of these, the light emitting layer is composed of a single layer or a plurality of layers. When the light emitting layer is composed of a plurality of layers, an intermediate layer may be provided between these light emitting layers. This intermediate layer may be a layer having the same configuration as the intermediate electrode layer described below, but is a layer that is not connected to an external power source.

The electron transport layer is a layer having a function of transporting electrons. The electron transport layer includes an electron injection layer and a hole blocking layer in a broad sense. Further, the electron transport layer may be composed of a plurality of layers.

The hole transport layer is a layer having a function of transporting holes. The hole transport layer includes a hole injection layer and an electron blocking layer in a broad sense. The hole transport layer may be composed of a plurality of layers.

For each layer constituting these light emitting units, conventionally known materials and forming methods can be used.

In addition, it is preferable that at least two light emitting units provided in the organic electroluminescence element 1 are light emitting units having a configuration using the same layers and materials except the light emitting layer. Further, each light emitting unit preferably has the same number of light emitting layers. Thereby, the number of materials used can be reduced, and there are advantages in production such as cost and quality control. Furthermore, the vapor deposition process has an advantage in terms of production efficiency such that the film forming chamber can be easily shared by the light emitting units.

Here, when the luminance [L1] to [L3] of the emitted light h1 and h2 is adjusted using the microcavity effect, each layer constituting each light emitting unit has a degree of interference between the emitted lights h1 and h2. It is assumed that a combined film thickness design is made.

In addition, each layer constituting each light emitting unit includes the first electrode layer 11 of external light incident on the organic electroluminescence element 1 in combination with the thickness design as described above or separately from the thickness design as described above. It is preferable that the film thickness is designed so that interference with the second electrode layer 12 is suppressed. Thereby, the coloring by interference of external light at the time of making the organic electroluminescent element 1 non-light-emission is prevented.

The film thickness of each layer can be derived using conventionally known light extraction calculation software. As the light extraction calculation software, for example, setfos (registered trademark) (manufactured by Fluxim AG) can be used, and the film thickness of each layer is set to a value derived therefrom.

Specifically, it is preferable that the film thickness of the electron transport layer constituting the first light emitting unit 21 and the second light emitting unit 22 is appropriately adjusted between several nm and 200 nm. In the case where the adjusted film thickness of the electron transport layer is thick within the above range, the electron mobility of the electron transport layer is preferably 10 ⁻⁵ cm ² / Vs or more.

On the other hand, when the luminances [L1] to [L3] of the emitted light h1 and h2 are adjusted by the optical film provided on the light extraction surface S side of the organic electroluminescence element 1, the film thickness of each layer constituting the light emitting unit Is not particularly limited. However, in this case, the entire film thickness of each light emitting unit is within the range of 5 to 200 nm from the viewpoint of ensuring the uniformity of the film to be formed, lowering the driving voltage, and improving the stability of the emission color with respect to the driving current. It is preferable to adjust, and it is more preferable to adjust in the range of 10 to 100 nm or less.

Next, the light emitting layer that is essential as a constituent layer of the light emitting unit will be described.

[Light emitting layer]
The light emitting layer provides a field in which electrons and holes injected from the first electrode layer 11, the second electrode layer 12, the intermediate electrode layer 30, or an adjacent layer are recombined to emit light via excitons. And a layer including a light-emitting organic semiconductor thin film. The light emitting layer preferably contains a light emitting dopant and a host compound. The light-emitting dopant is also referred to as a light-emitting dopant compound, a dopant compound, or simply a dopant. The host compound is also called a matrix material, a light emitting host compound, or simply a host.

The formation method of the light emitting layer is not particularly limited, and can be formed by a conventionally known method such as a vacuum deposition method or a wet method. It is preferable to form by the wet method from the manufacturing cost of the organic electroluminescent element 1. FIG. Details of each compound constituting the light emitting layer are as follows.

(1. Luminescent dopant)
As the luminescent dopant, a fluorescent luminescent dopant (also referred to as a fluorescent dopant or a fluorescent compound) and a phosphorescent dopant (also referred to as a phosphorescent dopant or a phosphorescent compound) are preferably used. The concentration of the light-emitting dopant in the light-emitting layer can be arbitrarily determined based on the specific dopant used and the device requirements. The concentration of the light emitting dopant may be contained at a uniform concentration in the film thickness direction of the light emitting layer, or may have an arbitrary concentration distribution.

Further, the light emitting layer may contain a plurality of kinds of light emitting dopants. For example, dopants having different structures may be used in combination, or a fluorescent luminescent dopant and a phosphorescent dopant may be used in combination. Thereby, arbitrary luminescent colors can be obtained.

In the organic electroluminescence element 1, it is preferable that one of the emitted lights h1 and h2 is red emitted light and the other is amber emitted light as described above. For example, when the emitted light h1 from the first light emitting unit 21 arranged on the flexible substrate 10 side is red emitted light, this is achieved by including a red emitting dopant in the light emitting layer. Further, when the emitted light h2 from the second light emitting unit 22 arranged on the second electrode layer 12 side is amber-colored emitted light, a red or green light-emitting dopant having emitted light close to amber is added to the light-emitting layer. It is achieved by containing alone or a combination of two or three red and green light emitting dopants. When a red or green light emitting dopant having emission light close to amber color is contained alone, the light emitting unit is optically designed so that only the emission spectrum near the amber color is taken out. Further, when amber light emission is obtained by combining red and green light-emitting dopants, two kinds of red and green light-emitting dopants are often combined.

Moreover, when the organic electroluminescent element 1 has a 3rd light emission unit further, a 3rd light emission unit may generate | occur | produce white light as emitted light. In this case, white light emission can be obtained by including a plurality of light emission dopants having different light emission colors in the light emitting layer. There are no particular limitations on the combination of light-emitting dopants that exhibit white, but examples include a combination of blue and orange, a combination of blue, green, and red. In addition, white here means that the chromaticity in the CIE 1931 color system at 1000 cd / m ² is x = 0.39 ± 0.09 when the 2 ° viewing angle front luminance is measured by the above-described method. = 0.38 ± 0.08 is preferable.

(1-1. Phosphorescent dopant)
The phosphorescent dopant is a compound in which light emission from an excited triplet is observed. Specifically, the phosphorescent dopant is a compound that emits phosphorescence at room temperature (25 ° C.), and has a phosphorescence quantum yield of 0 at 25 ° C. .01 or more compounds. In the phosphorescent dopant used for a light emitting layer, a preferable phosphorescence quantum yield is 0.1 or more.

The phosphorescent quantum yield can be measured by the method described in Spectroscopic II, page 398 (1992 edition, Maruzen) of Experimental Chemistry Course 4 of the 4th edition. The phosphorescence quantum yield in a solution can be measured using various solvents. The phosphorescence emitting dopant used for the light emitting layer should just achieve the said phosphorescence quantum yield (0.01 or more) in any solvent.

The phosphorescent dopant can be appropriately selected from known materials used for the light emitting layer of the organic electroluminescence element 1.

Among them, preferable phosphorescent dopants include organometallic complexes having iridium (Ir) as a central metal. More preferably, a complex containing at least one coordination mode of metal-carbon bond, metal-nitrogen bond, metal-oxygen bond, and metal-sulfur bond is preferable.

(1-2. Fluorescent luminescent dopant)
The fluorescent light-emitting dopant is a compound that can emit light from an excited singlet, and is not particularly limited as long as light emission from the excited singlet is observed.

Examples of the fluorescent light-emitting dopant include anthracene derivatives, pyrene derivatives, chrysene derivatives, fluoranthene derivatives, perylene derivatives, fluorene derivatives, arylacetylene derivatives, styrylarylene derivatives, styrylamine derivatives, arylamine derivatives, boron complexes, coumarin derivatives, Examples include pyran derivatives, cyanine derivatives, croconium derivatives, squalium derivatives, oxobenzanthracene derivatives, fluorescein derivatives, rhodamine derivatives, pyrylium derivatives, perylene derivatives, polythiophene derivatives, rare earth complex compounds, and the like.

Further, a light emitting dopant using delayed fluorescence may be used as the fluorescent light emitting dopant. Specific examples of the luminescent dopant using delayed fluorescence include compounds described in, for example, International Publication No. 2011/156793, Japanese Patent Application Laid-Open No. 2011-213643, Japanese Patent Application Laid-Open No. 2010-93181, and the like.

(2. Host compound)
The host compound is a compound mainly responsible for charge injection and transport in the light emitting layer, and light emission of itself is not substantially observed in the organic electroluminescence device 1.
Preferably, it is a compound having a phosphorescence quantum yield of phosphorescence of less than 0.1 at room temperature (25 ° C.), more preferably a compound having a phosphorescence quantum yield of less than 0.01. Moreover, it is preferable that the mass ratio in the layer is 20% or more among the compounds contained in a light emitting layer.

Moreover, it is preferable that the excited state energy of a host compound is higher than the excited state energy of the light emission dopant contained in the same layer.
A host compound may be used independently or may be used in combination of multiple types. By using a plurality of types of host compounds, it is possible to adjust the movement of charges, and it is possible to increase the efficiency of the organic electroluminescence element 1.

There is no restriction | limiting in particular as a host compound used for a light emitting layer, The compound used for a normal organic electroluminescent element can be mentioned. For example, a low molecular compound, a high molecular compound having a repeating unit, or a compound having a reactive group such as a vinyl group or an epoxy group may be used.

As a known host compound, while having a hole transport ability or an electron transport ability, it prevents the light emission from becoming longer wavelength, and further, from the viewpoint of stability against heat generation during driving of the organic electroluminescence element at a high temperature or during element driving, It is preferable to have a high glass transition temperature (Tg). As a host compound, it is preferable that Tg is 90 degreeC or more, More preferably, it is 120 degreeC or more.
Here, the glass transition point (Tg) is a value determined by a method based on JIS-K-7121 using DSC (Differential Scanning Colorimetry).

[Intermediate electrode layer 30]
The intermediate electrode layer 30 functions as an anode for supplying holes to the first light emitting unit 21 and the second light emitting unit 22, or functions as a cathode for supplying electrons.

For example, as illustrated, if the first electrode layer 11 functions as an anode for the first light emitting unit 21, the intermediate electrode layer 30 functions as a cathode for the first light emitting unit 21. On the other hand, if the first electrode layer 11 functions as a cathode with respect to the first light emitting unit 21, the intermediate electrode layer 30 functions as an anode with respect to the first light emitting unit 21.

As shown in the figure, if the second electrode layer 12 functions as a cathode for the second light emitting unit 22, the intermediate electrode layer 30 functions as an anode for the second light emitting unit 22. On the other hand, if the second electrode layer 12 functions as an anode for the second light emitting unit 22, the intermediate electrode layer 30 functions as a cathode for the second light emitting unit 22.

Further, the intermediate electrode 30 is electrically connected to the first electrode layer 11 via a power source, and is electrically connected to the second electrode layer 12 via a power source.

Further, it is assumed that such an intermediate electrode layer 30 is made of a transparent conductive material having optical transparency. In particular, when the luminances [L1] to [L3] of the emitted light h1 and h2 are adjusted using the microcavity effect, the film thickness of the intermediate electrode layer 30 is as well as the film thickness of each layer constituting the light emitting unit. Also, it is assumed that the film thickness is designed in accordance with the degree of interference of each light emitted from each light emitting unit.

Further, the intermediate electrode layer 30 is designed so that interference with external light incident on the organic electroluminescence element 1 can be suppressed in combination with the above-described thickness design or separately from the above-described thickness design. It is preferable that Thereby, the coloring by interference of external light at the time of making the organic electroluminescent element 1 non-light-emission is prevented.

As described above, the thickness of the intermediate electrode layer 30 is preferably 10 nm or more, more preferably 15 nm or more.

[Flexible substrate 10]
The flexible substrate 10 is not particularly limited as long as it is a flexible plastic or glass material, and a resin film or the like can be preferably used. Moreover, when the organic electroluminescent element 1 is a bottom emission structure which takes out emitted light h1, h2 from the flexible substrate 10 side, the flexible substrate 10 shall have a light transmittance.

Examples of the resin film include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyethylene, polypropylene, cellophane, cellulose diacetate, cellulose triacetate (TAC), cellulose acetate butyrate, cellulose acetate propionate ( CAP), cellulose esters such as cellulose acetate phthalate, cellulose nitrate or derivatives thereof, polyvinylidene chloride, polyvinyl alcohol, polyethylene vinyl alcohol, syndiotactic polystyrene, polycarbonate, norbornene resin, polymethylpentene, polyether ketone, polyimide , Polyethersulfone (PES), polyphenylene sulfide, polysulfones Cycloolefins such as polyetherimide, polyetherketoneimide, polyamide, fluororesin, nylon, polymethylmethacrylate, acrylic or polyarylate, arton (trade name, manufactured by JSR) or appel (trade name, manufactured by Mitsui Chemicals) Resin etc. are mentioned.

A gas barrier film may be formed on the surface of the resin film by using an inorganic film, an organic film, or a hybrid film of both. The gas barrier film has a water vapor permeability (25 ± 0.5 ° C., humidity 90 ± 2% RH) measured by a method according to JIS K 7129-1992, of 0.01 g / (m ² · 24 h) or less. A gas barrier film is preferred. Furthermore, the oxygen permeability measured by a method according to JIS K 7126-1987 is 10 ⁻³ mL / (m ² · 24 h · atm) or less, and the water vapor permeability is 10 ⁻⁵ g / (m ² · 24h) The following high gas barrier films are preferred.

As the material for forming the gas barrier film, any material may be used as long as it has a function of suppressing intrusion of elements that cause deterioration of elements such as moisture and oxygen. For example, silicon oxide, silicon dioxide, silicon nitride, or the like can be used. Furthermore, in order to improve the brittleness of the gas barrier film, it is more preferable to have a laminated structure of these inorganic layers and layers made of organic materials. Although there is no restriction | limiting in particular about the lamination | stacking order of an inorganic layer and an organic layer, It is preferable to laminate | stack both alternately several times. There is no limitation in particular about the formation method of a gas barrier film | membrane, A conventionally well-known method can be used.

[Other components]
The organic electroluminescence element 1 has a sealing unit for sealing a light emitting unit configured using an organic material. As a sealing means, a well-known material and a formation method can be employ | adopted within the range which does not impair the flexibility of the organic electroluminescent element 1. FIG. Further, in order to increase the mechanical strength of the organic electroluminescence element 1, a known protective film or protective plate may be provided outside the sealing means within a range that does not impair flexibility.

In the above-described embodiment, from the flexible substrate 10 side, the anode to be the transparent first electrode layer 11, the first light emitting unit 21, the intermediate electrode layer 30, the second light emitting unit 22, and the second light-reflecting second. The bottom emission type organic electroluminescence element 1 in which the cathode to be the electrode layer 12 was laminated in this order was illustrated. However, the organic electroluminescence of the present invention is not limited to such a configuration. For example, the stacking order of the layers may be reversed, or the anode and the cathode may be reversed, that is, the first electrode layer 11 may be a cathode and the second electrode layer 12 may be an anode. In this case, the cathode is a transparent electrode and the anode is a reflective electrode.
Further, the configuration of the light emitting unit, the number of stacked layers, and the number of stacked light emitting layers are not particularly limited, and a configuration capable of realizing a desired organic electroluminescence element can be obtained. For example, the organic electroluminescence element may have a configuration in which three or more light emitting units are stacked.

≪Vehicle lamp≫
FIG. 3 is a top view of the vehicle for explaining a schematic configuration of the vehicular lamp according to the embodiment. The vehicular lamp 2 according to the embodiment described with reference to this figure is configured to include the organic electroluminescence element 1 according to the above-described embodiment. For example, a tail lamp, a stop lamp, a back lamp, a turn of the vehicle 200 are provided. It can be applied to any lamp. In particular, when the emitted light h1 and h2 of the first light emitting unit and the second light emitting unit in the organic electroluminescent element 1 are red emitted light and amber colored emitted light, the organic electroluminescent element 1 is It is suitably used as a tail lamp, a stop lamp, and a turn lamp.

Next, an application example of the vehicular lamp 2 will be described with reference to FIG. As shown in FIG. 3, a headlamp 201 is provided at the front portion of the vehicle 200, and a vehicle lamp 2 is provided at the rear corner portion of the vehicle 200. The vehicular lamp 2 is configured to distribute emitted light to the rear of the vehicle 200. In FIG. 3, the directions viewed from the driver of the vehicle 200 are described as front, rear, left, and right.

The vehicular lamp 2 includes a housing 203 that is attached to a recess formed in a rear corner portion of the vehicle 200, a translucent cover 204 that is formed in accordance with the shape of the vehicle body of the vehicle 200 and covers the housing 203, and the housing 203 and the translucent cover 204. And the organic electroluminescence element 1 as a light source provided in the lamp chamber 205 formed between the two.

The organic electroluminescence element 1 is formed in a belt shape extending in the left-right direction of the vehicle 200, and is held by the housing 203 in a state where a part thereof is curved in a convex shape according to the shape of the vehicle body of the vehicle 200.

In addition, the material of the light emitting layer of the organic electroluminescence element 1 is appropriately selected, so that red light h1 for tail lamps and stop lamps and amber light h2 for turn lamps are generated. Has been. In addition, it is good also as what emits the emitted light of said each color by using what shows white light as the organic electroluminescent element 1, and providing a color filter.

As described above, the organic electroluminescence element 1 provided as the vehicular lamp 2 may have different light emitting areas of the first light emitting unit 21 and the second light emitting unit 22. That is, the light emitting region of the first light emitting unit 21 is a portion where the first light emitting unit 21 is sandwiched between the first electrode layer 11 and the intermediate electrode layer 30. The light emitting region of the second light emitting unit 22 is a portion where the second light emitting unit 22 is sandwiched between the intermediate electrode layer 30 and the second electrode layer 12. And these two light emission area | regions may be shifted and arrange | positioned in the upper part of the flexible substrate 10 with a partial overlap.

<< Effects of Embodiment >>
According to the organic electroluminescent element 1 of the embodiment described above, since the light extraction surface S can be used by being curved by using the flexible substrate 10, the design characteristics according to the vehicle body design can be improved. A high vehicle lamp 2 can be configured. In addition, the light distribution characteristics of the emitted lights h1 and h2 from the first light emitting unit 21 and the second light emitting unit 22 stacked on the flexible substrate 10 are limited as described above. Thereby, for example, when the light extraction surface S of the organic electroluminescence element 1 is curved in a convex direction and provided at the rear corner portion of the vehicle as a vehicle lamp, the visibility of the emitted light h1 and h2 is improved. be able to.

In addition, by providing an intermediate electrode layer 30 connected to the external electrode between the first light emitting unit 21 and the second light emitting unit 22, the emitted light is individually emitted from the first light emitting unit 21 and the second light emitting unit 22. h1 and h2 were taken out and the toned light was emitted. As a result, red light for the tail lamp and amber light for the turn lamp can be emitted from the same lamp, and the design of the vehicular lamp 2 can also be improved.

Further, by making the intermediate electrode layer 30 semi-transparent and semi-reflective, each layer constituting the first light emitting unit 21 and the second light emitting unit 22 in designing the film thickness to make the emitted light h1 and h2 have specific light distribution characteristics. The film thickness of the intermediate electrode layer 30 can be changed, and the degree of freedom in designing the film thickness is improved. In addition, since the degree of freedom in designing the film thickness is improved, it is possible to adopt a configuration that suppresses interference of external light incident on the organic electroluminescence element 1, thereby preventing coloring of the vehicular lamp 2 due to interference of external light. Is also possible.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "mass part" or "mass%" is represented.

<< Production of Organic Electroluminescence Element 101 >>
According to the following method, the organic electroluminescent element 101 having the configuration shown in FIG. 1 was produced.

(Preparation of flexible base material with gas barrier layer)
A polyethylene naphthalate film (a film made by Teijin DuPont Co., Ltd., hereinafter referred to as a PEN film) was prepared. An inorganic gas barrier layer made of silicon oxide (SiOx) is formed on one main surface of the PEN film using an atmospheric pressure plasma discharge treatment apparatus having a configuration described in Japanese Patent Application Laid-Open No. 2004-68143. A flexible substrate 10 with a gas barrier layer was formed to a thickness of 500 nm.

(Formation of underlayer)
The flexible substrate 10 with a gas barrier layer was fixed to a base material holder of a commercially available vacuum deposition apparatus, and the substrate holder was attached to a vacuum chamber of the vacuum deposition apparatus. Next, after reducing the pressure in the vacuum chamber to 4 × 10 ⁻⁴ Pa, a heating boat containing the following compound 1 which is a nitrogen-containing compound was energized and heated. Thus, Compound 1 was deposited on the gas barrier layer of the flexible substrate 10 at a deposition rate of 0.1 to 0.2 nm / second to form a base layer having a thickness of 15 nm.

(Formation of the first electrode layer 11)
The flexible substrate 10 on which the base layer was formed was mounted in a vacuum chamber of a vacuum deposition apparatus. Next, after reducing the pressure in the vacuum chamber to 4 × 10 ⁻⁴ Pa, the heating boat containing silver (Ag) was energized and heated. Thus, the first electrode layer 11 made of silver (Ag) having a film thickness of 13 nm was formed at a deposition rate of 0.1 to 0.2 nm / second. The first electrode layer 11 was a transparent electrode and formed as an anode.

(Formation of the first light emitting unit 21)
On the 1st electrode layer 11 as an anode, the 1st light emission unit 21 was formed in accordance with the procedure shown below. The flexible substrate 10 formed up to the first electrode layer 11 is dried in a glove box having a dew point of −80 ° C. or less and an oxygen concentration of 1 ppm or less, and then the first light emitting unit 21 is formed without being exposed to the atmosphere from the glove box. It transferred to the vacuum chamber of a vacuum evaporation system.

In the vacuum chamber of the vacuum deposition apparatus, a resistance heating boat filled with the optimum amount of the constituent materials of each layer was attached. The resistance heating boat used was made of a resistance heating material made of molybdenum or tungsten.

Subsequently, the inside of the vacuum chamber of the vacuum evaporation apparatus was depressurized to 1 × 10 ⁻⁴ Pa, and first, a resistance heating boat containing a compound M-1 (MTDATA) represented by the following chemical formula was energized and heated. As a result, Compound M-1 (MTDATA) was deposited on the first electrode layer 11 at a deposition rate of 0.1 nm / second to form a 17 nm-thick hole injection layer.

Next, a resistance heating boat containing a compound M-2 (α-NPD) represented by the following chemical formula was heated by energization. Thereby, the compound M-2 (α-NPD) was vapor-deposited on the hole injection layer to form a 20 nm-thick hole transport layer (HTL).

Next, the compound GD-1, the compound RD-1, and the compound H-2 represented by the following chemical formula have a concentration of 10% by volume for the compound GD-1 and 10% by volume for the compound RD-1. As described above, co-evaporation was performed at a deposition rate of 0.1 nm / second to form a phosphorescent light emitting layer having a thickness of 35 nm on the hole transport layer (HTL). Compound RD-1 has a maximum peak wavelength of 620 nm.

Thereafter, the resistance heating boat containing the compound 1 was energized and heated. Thereby, Compound 1 was deposited on the phosphorescent light emitting layer at a deposition rate of 0.1 nm / second to form an electron transport layer (ETL) having a film thickness of 22 nm.

Next, a resistance heating boat containing lithium fluoride (LiF) was energized and heated. Thereby, lithium fluoride (LiF) was deposited on the electron transport layer (ETL) at a deposition rate of 0.1 nm / second to form an electron injection layer having a thickness of 1 nm.
Thus, the first light emitting unit 21 having a red phosphorescent light emitting layer was formed.

(Formation of the intermediate electrode layer 30)
Next, the intermediate electrode layer 30 was formed on the first light emitting unit 21 as follows. First, aluminum (Al) and silver (Ag) are put in each resistance heating boat made of tungsten, and these resistance heating boats and the flexible substrate 10 on which the first light emitting unit 21 is formed are vacuum-deposited. In a vacuum chamber. The inside of the vacuum chamber was depressurized to 4 × 10 ⁻⁴ Pa, and then each resistance heating boat was independently energized and heated. Thereby, aluminum (Al) and silver (Ag) are vapor-deposited in this order on the 1st light emission unit 21, and the intermediate electrode layer 30 which consists of a film thickness ratio of aluminum (Al) 1nm and silver (Ag) 15nm is formed. did.

(Formation of the second light emitting unit 22)
Next, the second light emitting unit 22 was formed on the intermediate electrode layer 30 as follows. The above compound M-1 was deposited on the intermediate electrode layer 30 at a deposition rate of 0.1 nm / second to form a hole injection layer having a thickness of 18 nm.

Next, the above-described compound M-2 was deposited on the hole injection layer to form a 95 nm-thick hole transport layer.

Next, the above-mentioned compound GD-1, the following compound RD-2, and the above-mentioned compound H-2 are adjusted so that the compound GD-1 has a volume ratio of 10% and the compound RD-2 has a volume ratio of 10%. Were co-evaporated at a deposition rate of 0.1 nm / second to form a phosphorescent light emitting layer having an amber color with a film thickness of 35 nm. Compound RD-2 has a maximum peak wavelength of 605 nm.

Thereafter, the above-described compound 1 was deposited at a deposition rate of 0.1 nm / second to form an electron transport layer having a thickness of 55 nm.

Further, lithium fluoride (LiF) was deposited at a deposition rate of 0.1 nm / second to form an electron injection layer having a thickness of 1 nm.
Thus, the second light emitting unit 22 having an amber phosphorescent light emitting layer was formed.

(Formation of the second electrode layer 12)
Next, on the 2nd light emission unit 22, aluminum (Al) was vapor-deposited with the film thickness of 100 nm, and the 2nd electrode layer 12 was formed. The second electrode layer 12 is a light impermeable reflective electrode, and was formed as a cathode.

(Production of sealing structure)
In the following manner, a sealing film was bonded to the flexible substrate 10 and sealed so as to cover the laminated body from the first electrode layer 11 to the second electrode layer 12.

An adhesive was applied to a non-alkali glass substrate having a thickness of 0.7 mm and dried at 120 ° C. for 2 minutes to form an adhesive layer having a thickness of 20 μm. Also, an aluminum laminate film was prepared in which a polyethylene terephthalate film having a thickness of 50 μm was bonded to an aluminum foil having a thickness of 100 μm. The polyethylene terephthalate film side of the aluminum laminate film was bonded to the previous adhesive layer to obtain a sealing film. Thereafter, the laminate of the aluminum foil, the polyethylene terephthalate film, and the adhesive layer was peeled off from the alkali-free glass substrate, and the adhesive layer side was covered with a release sheet to obtain a sealing film.

After leaving this sealing film in a nitrogen atmosphere for 24 hours or more, the release sheet is removed, the adhesive film side of the sealing film is disposed so as to face the second electrode layer 12, and a vacuum heated to 80 ° C. It bonded to the flexible substrate 10 with the laminator. Furthermore, it sealed by heating for 30 minutes at 120 degreeC. Thereby, the organic electroluminescent element 101 which sealed the laminated body from the 1st electrode layer 11 to the 2nd electrode layer 12 between the flexible substrate 10 and the sealing film was produced. The produced organic electroluminescence element 101 has a light emitting region of 200 mm × 40 mm.

<< Production of organic electroluminescence elements 102 to 108 >>
In the production of the organic electroluminescent element 101, as shown in Table 2 below, the film thicknesses of the hole transport layer (HTL) and the electron transport layer (ETL) of the first light emitting unit 21 and the second light emitting unit 22 are shown. Each of the organic electroluminescent elements 102 to 108 was produced in the same manner except that the above was changed.

<< Production of organic electroluminescence elements 109-111 >>
In the production of the organic electroluminescent element 101, as shown in Table 2 below, each of the organic electroluminescence elements was similarly made except that the film thicknesses of aluminum (Al) and silver (Ag) constituting the intermediate electrode layer 30 were changed. Luminescence elements 109 to 111 were produced.

<< Production of Organic Electroluminescence Element 112 (Comparative Example) >>
In preparation of the said organic electroluminescent element 101, as shown in following Table 2, except having changed the film thickness of the positive hole transport layer (HTL) in the 1st light emission unit 21, and the film thickness of the electron transport layer (ETL). In the same manner, each organic electroluminescence element 112 was produced.

<< Evaluation of organic electroluminescence elements 101-112 >>
The organic EL elements 101 to 112 produced as described above were evaluated as follows. The evaluation results are shown in Table 2 below.

(1) Measurement of light distribution characteristics The organic electroluminescence elements 101 to 112 produced as described above are set on a rotating stage that automatically rotates, and a light intensity distribution and spectrum are measured using a spectral luminance meter (CS-2000, manufactured by Konica Minolta). Was measured. In the measurement, a constant amount of current (5 mA / cm ² ) is separately supplied between the first electrode layer 11 and the intermediate electrode layer 30 and between the intermediate electrode layer 30 and the second electrode layer 12 to thereby generate the first light emission. The unit 21 and the second light emitting unit 22 were made to emit light individually, and the normal N direction with respect to the light extraction surface S of each of the organic electroluminescence elements 101 to 112 was set to 0 °, and the measurement was performed a plurality of times within a range of ± 80 °. The rotation stage used was a handmade one. The front luminance [L1] at this time was adjusted to 1000 cd / m ² and evaluated.

From the light distribution characteristics of the organic electroluminescence elements 101 to 112 obtained as described above, the values of [L2] / [L1] and [L3] / [L1] are determined for each of the organic electroluminescence elements 101 to 112. Asked.

(2) Brightness Uniformity Evaluation The organic electroluminescence elements 101 to 112 produced as described above were fixed in a curved state so that the light extraction surface S was convex with a curvature of 50 mm. In this state, a constant amount of current (5 mA / cm ² ) is separately supplied between the first electrode layer 11 and the intermediate electrode layer 30 and between the intermediate electrode layer 30 and the second electrode layer 12 to thereby generate the first light emission. The unit 21 and the second light emitting unit 22 emit light individually, and the center position of the light extraction surface S was visually observed from the front (normal N direction) from an observation position 1 m away. The uniformity of the brightness of the entire light extraction surface S of each of the organic electroluminescence elements 101 to 112 was evaluated by 10 general monitors according to the following criteria. In addition, if it was (circle) or (triangle | delta), it was judged that the uniformity of brightness was practically possible.
○: Nine or more monitors determined that the brightness of the light emitting area was uniform. Δ: Five to eight monitors determined that the brightness of the light emitting area was uniform. However, the brightness of the light-emitting area was determined to be uniform

(3) Evaluation of appearance when not emitting light With respect to the organic electroluminescent elements 101 to 112 produced as described above, light is emitted from an observation position 1 m away with both the first light emitting unit 21 and the second light emitting unit 22 not emitting light. The center position of the extraction surface S was visually observed from the front (normal N direction). The appearance of each of the organic electroluminescent elements 101 to 112 when not emitting light was evaluated by 10 general monitors according to the following criteria. In addition, if it was (circle) or (triangle | delta), it judged that there was no coloring by interference of external light reflection.
○: Nine or more monitors determined that the color of the aluminum of the second electrode layer Δ: Five to eight monitors determined that the color of the aluminum of the second electrode layer ×: Four or less However, even if it is x, there is no problem in use.

Here, the chromaticity of the front surface of the light emitted from the first light emitting unit of the organic electroluminescence element 101 was x = 0.70 and y = 0.30 in the CIE-xy chromaticity diagram. Further, the chromaticity of the front surface of the emitted light of the first light emitting units of the organic electroluminescent elements 102 to 112 was in the range of x = ± 0.02 and y = ± 0.02 with respect to the organic electroluminescent element 101. .
Further, the chromaticity of the front surface of the light emitted from the second light emitting unit of the organic electroluminescence element 101 was x = 0.58 and y = 0.41 in the CIE-xy chromaticity diagram. Further, the chromaticity of the front surface of the emitted light of the second light emitting units of the organic electroluminescent elements 102 to 112 was in the range of x = ± 0.02 and y = ± 0.02 with respect to the organic electroluminescent element 101. .

As shown in Table 2, the light distribution characteristics of the emitted light satisfy the relationship of 0.85 ≦ [L2] / [L1] ≦ 1.20 and [L3] / [L1] ≦ 0.50. It was confirmed that the light emitting unit is superior in brightness uniformity when the light extraction surface S curved in the convex direction is observed from the center position, as compared with the light emitting unit that does not satisfy this relationship.

Specifically, the first light emitting unit of the organic electroluminescent element 105, the second light emitting unit of the organic electroluminescent element 106, the second light emitting unit of the organic electroluminescent element 107, the first light emitting unit of the organic electroluminescent element 108, the organic The first light emitting unit and the second light emitting unit of the electroluminescence element 112 did not satisfy the above relationship, and were inferior in brightness uniformity as compared with other light emitting units satisfying the above relationship.

Furthermore, a light emitting unit satisfying a relationship in which the light distribution characteristics of the emitted light satisfy 0.90 ≦ [L2] / [L1] ≦ 1.10 and [L3] / [L1] ≦ 0.45, It was confirmed that the uniformity of brightness when the light extraction surface S curved in the convex direction was observed from the center position was further excellent.

Moreover, from the brightness uniformity evaluation results shown in Table 2, the light distribution characteristics of the emitted light from both the first light emitting unit and the second light emitting unit are 0.85 ≦ [L2] / [L1] ≦ 1.06. And satisfying the relationship of 0.15 ≦ [L3] / [L1] ≦ 0.47, the red emission light from the first light emission unit and the amber emission light from the second light emission unit It was confirmed that both were more reliably extracted from the light extraction surface S curved in the convex direction while maintaining uniformity.

As a result, if all of the at least two light emitting units are organic electroluminescence having a configuration satisfying the above relationship, the vehicle tail lamp and the stop lamp that emit red light, and the vehicle turn lamp that emits amber light can be used. By using the organic electroluminescence element 1, it is possible to visually recognize both red light emission and amber light emission when the vehicle is viewed from the rear vehicle with uniform brightness. For this reason, it was confirmed that the visibility of the tail lamp, the stop lamp, and further the turn lamp can be improved.

Further, from the evaluation results of the electrode colors at the time of non-light emission shown in Table 2, by having the intermediate electrode layer 30 having a film thickness that is thick enough to be connected to an external power source, the light distribution characteristics of the emitted light satisfy a specific relationship. It was confirmed that such a film thickness design can be compatible with a film thickness design that suppresses coloring during non-light emission due to external light interference.

1 ... Organic electroluminescence element.
DESCRIPTION OF SYMBOLS 10 ... Flexible substrate 11 ... 1st electrode layer 12 ... 2nd electrode layer 21 ... 1st light emission unit (light emission unit)
22 ... Second light emitting unit (light emitting unit)
30 ... Intermediate electrode layer [L1] ... Front luminance [L2] ... Luminance with a viewing angle of 20 ° [L3] ... Luminance with a viewing angle of 60 ° 2 ... Vehicle lamp

Claims

A flexible substrate;
A first electrode layer provided on the flexible substrate;
A second electrode layer provided above the first electrode layer;
At least two light emitting units having a light emitting layer configured using an organic material and disposed between the first electrode layer and the second electrode layer;
An intermediate electrode layer disposed between the light emitting units,
The two light emitting units are different from each other in chromaticity of emitted light,
The light distribution characteristics of the emitted light extracted from at least one of the two light emitting units to the flexible substrate side or the second electrode layer side has a front luminance of [L1] and a luminance of a viewing angle of 20 ° [ L2] and the luminance at a viewing angle of 60 ° are [L3], 0.85 ≦ [L2] / [L1] ≦ 1.20 and [L3] / [L1] ≦ 0.50 There is an organic electroluminescence device.
The organic electroluminescence device according to claim 1, wherein the at least two light emitting units have different maximum peak wavelengths of emitted light.
3. The organic electroluminescence device according to claim 1, wherein the light distribution characteristics are 0.90 ≦ [L2] / [L1] ≦ 1.10 and [L3] / [L1] ≦ 0.45. .
The light distribution characteristics in all of the at least two light emitting units are 0.85 ≦ [L2] / [L1] ≦ 1.20 and [L3] / [L1] ≦ 0.50. Item 3. The organic electroluminescence device according to Item 1 or 2.
2. The light distribution characteristics in all of the at least two light emitting units are 0.90 ≦ [L2] / [L1] ≦ 1.10 and [L3] / [L1] ≦ 0.45. 5. The organic electroluminescence device according to any one of 1 to 4.
One of the at least two light emitting units has a front chromaticity of emitted light such that 0.29 ≦ y ≦ 0.34 and y + x ≧ 0.98 in the CIE-xy chromaticity diagram. 6. The organic electroluminescence device according to any one of 5 above.
One of the at least two light emitting units has a front chromaticity of emitted light such that y ≧ 0.39, y ≧ 0.79-0.67x, y ≦ x-0 in the CIE-xy chromaticity diagram. The organic electroluminescence device according to any one of claims 1 to 5, wherein the organic electroluminescence device is .12.
An external power source is connected to the first electrode layer, the second electrode layer, and the intermediate electrode layer,
The thickness of the at least two light emitting units and the intermediate electrode layer is designed so that interference of external light between the first electrode layer and the second electrode layer is prevented. An organic electroluminescence device according to any one of the above.
A vehicular lamp using the organic electroluminescence element according to any one of claims 1 to 8.