JP6913088B2 - Organic electroluminescence elements and vehicle lamps - Google Patents

Description

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

Conventionally, an organic EL element using a light emitting material that realizes high light emission efficiency by utilizing all of singlet excitons and triplet excitons for electroluminescence (hereinafter, also referred to as EL) has been proposed. In organic EL devices, materials in the practical range have been developed with both high luminous efficiency and luminous life, and are used for displays and lighting.

Further, in recent years, it has been proposed to utilize the characteristics such as surface emission and flexibility of an organic EL element to apply it to a vehicle lamp (for example, a tail lamp) having a 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 a vehicle behind is required.

Japanese Unexamined Patent Publication No. 2015-5552

As a result of the inventor's diligent efforts to address the above problems, the following was found.

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

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

The present invention for achieving the above object includes a flexible substrate, a first electrode layer provided on the flexible substrate, a second electrode layer provided above the first electrode layer, and an organic substance. At least two light emitting units having a light emitting layer made of a material and arranged so as to be overlapped between the first electrode layer and the second electrode layer, and an intermediate electrode layer arranged between the light emitting units. with the door, the at least two light emitting units, which the chromaticity of each of the emitted light are different, at least two of the at least one of the flexible substrate side or the second electrode layer side from the light-emitting unit of the light-emitting unit When the front brightness is [L1], the brightness with a viewing angle of 20 ° is [L2], and the brightness with a viewing angle of 60 ° is [L3], the light distribution characteristics of the emitted light extracted from the above are 0.85 ≦ [ L2] / [L1] ≤ 1.20 and [L3] / [L1] ≤ 0.50 , and an external power source is supplied to the first electrode layer, the second electrode layer, and the intermediate electrode layer. The organic electro is connected, and the film thickness of the at least two light emitting units and the intermediate electrode layer is designed so as to prevent interference of external light between the first electrode layer and the second electrode layer. It is a luminescence element. The present invention is also a vehicle lamp using such an organic electroluminescence 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 visibility is improved by using this organic electroluminescence element. It is possible to obtain the electroluminescence for vehicles.

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

Hereinafter, embodiments of the present invention will be described in the order of an organic electroluminescence element and a vehicle lamp using the organic electroluminescence element. In the embodiments described below, "~" is used to mean that the numerical values described before and after the "~" are included as the lower limit value and the upper limit value.

≪Organic electroluminescence element≫
FIG. 1 is a cross-sectional view showing an outline of the organic electroluminescence device 1 according to the embodiment. As shown in this figure, in the organic electroluminescence element 1, the flexible substrate 10, the first electrode layer 11, the first light emitting unit 21, the intermediate electrode layer 30, the second light emitting unit 22, and the second electrode layer 12 are arranged in this order. It has a laminated tandem structure. Is the organic electroluminescence element 1 a bottom emission type that takes out 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? , Or vice versa, it may be a top emission type.

Here, the bottom emission type organic electroluminescence element 1 as shown 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 light transmission. Further, when the emitted light h1 and h2 are interfered with each other and taken out by the microcavity effect, the first electrode layer 11 and the intermediate electrode layer 30 are configured as electrodes having semitransmissive semireflective property. 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 to the first electrode layer 11 and the intermediate electrode layer 30 from an external power source, whereby light emitting light h1 is generated in the first light emitting unit 21. Further, a voltage is applied to the intermediate electrode layer 30 and the second electrode layer 12 from an external power source, whereby light emitting light h2 is generated in the second light emitting unit 22. The generation of the luminescent light h1 and the luminescent light h2 is individually controlled by adjusting the voltage application to the first electrode layer 11, the intermediate electrode layer 30, and the second electrode layer 12.

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

In the organic electroluminescence element 1 having such a configuration, the luminescent light h1 generated by the first light emitting unit 21 and the luminescent light h2 generated by the second light emitting unit 22 have different chromaticities. Further, the emission light h1 and the emission light h2 also have different maximum peak wavelengths. Such a difference between the emitted light h1 and the emitted light h2 is due to a difference in the configurations of the first light emitting unit 21 and the second light emitting unit 22, and will be described in detail below.

In the organic electroluminescence element 1 provided with the first light emitting unit 21 and the second light emitting unit 22 as described above, when the outermost surface on the flexible substrate 10 side is the light extraction surface S, the light emitted from the light extraction surface S is taken out. 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 electroluminescence element 1 will be described in this order.

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

The above is the same even when the light extraction surface S is curved as shown in FIG. 2, and at least of the emission light h1 and the emission light h2 in each part of the light extraction surface S curved in the convex direction. On the other hand, it is assumed that the above-mentioned relationship holds for the light distribution characteristics.

By establishing such a relationship, for example, when the organic electroluminescence element 1 is provided at the rear corner portion of the vehicle as a vehicle lamp, for example, the light extraction surface S is curved in a convex direction, the vehicle is rearward. It is possible to make the extraction intensity of the emitted lights h1 and h2 on the light extraction surface S when viewed from the vehicle uniform. Further, this 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-mentioned relationship, such an effect can be obtained for the emitted light h1, and if the emitted light h2 satisfies the above-mentioned relationship, the emitted light h2 can be obtained. Such an effect can be obtained.

Further, 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. Further, it is preferable that the above light distribution characteristics are combined with 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 in which the degree of light distribution in the normal N direction is stronger than that of Lambersian, which is the intensity of light from a uniformly diffused light source. However, it may have a weak light distribution shape. Table 1 below shows, as an example of the light distribution characteristics of the organic electroluminescence device 1 according to the embodiment, the light distribution shapes 1 and 2 and the arrangement 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 degree of light distribution 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]
The following method can be used as a method for measuring the brightness [L1] to [L3] for obtaining the above-mentioned light distribution characteristics.

Luminance [L1] to [L3] by setting the organic electroluminescence element 1 on a rotating stage that automatically rotates and measuring the light intensity distribution and spectrum using a spectroluminance meter (manufactured by Konica Minolta, CS-2000). Can be sought. ^{In these measurements, a constant current amount (5 mA / cm 2} ) was individually applied to each of the first light emitting unit 21 and the second light emitting unit 22 to emit light, and ± with respect to the normal N. It is carried out in the range of 80 °. Among the measurement results, the measured values in the normal [N] direction, the measured value with a viewing angle of 20 ° with respect to the normal N, and the measured values with a viewing angle of 60 ° with respect to the normal N are used to obtain the respective brightnesses [L1] to [L3]. ] Is asked.

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

The first method is a method of utilizing the microcavity effect between the first electrode layer 11, the intermediate electrode layer 30, and the second electrode layer 12. In this case, depending on 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, from the light emitting points D1 and D2 in the first light emitting unit 21 and the second light emitting unit 22. , The distances to the first electrode layer 11, the intermediate electrode layer 30, and the second electrode layer 12 are adjusted. As a result, the emitted lights h1 and h2 of each emission wavelength are interfered with each other between the first electrode layer 11, the intermediate electrode layer 30, and the second electrode layer 12 and taken out from the light extraction surface S.

At this time, the directivity in the light extraction direction is achieved by adjusting the degree of interference between the emitted lights h1 and h2 by adjusting the film thickness 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. As a result, the brightness [L1] to [L3] of the emitted light h1 and h2 are adjusted so as to satisfy the above-mentioned light distribution characteristics.

The second method is a method in which an optical film (not shown here) is provided on the light extraction surface S side of the organic electroluminescence element 1. The optical film is, for example, a microlens array or dot pattern composed of a plurality of convex portions, a sheet-shaped optical film or optical sheet having a diffraction grating or a concavo-convex structure, or an optical multilayer having different refractive indexes. An optical film made of a film or the like can be used.

However, if a film having sufficient transmittance cannot be prepared as the optical film, the brightness [L1] to [L3] of the emitted lights h1 and h2 can be adjusted to the above-mentioned light distribution characteristics by applying the first method described above. It is preferable that the adjustment is made within the range of.

<Color of emitted light h1 and h2>
As for 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 arranged on the light extraction side is a red emitted light having a longer wavelength, while the second light emitting unit 22 arranged on the second electrode layer 12 side. It is better to use the light emitted from the light h2 as an amber-colored light having a shorter wavelength. As a result, the long-wavelength red color can be suppressed from being weakened by plasmon absorption, and thus high efficiency is expected as an organic electroluminescence device.

The chromaticity of the organic electroluminescence device of the present invention is not particularly limited, and various chromaticities can be applied. When applied as a vehicle lamp, red and amber colors are preferable. Here, it is preferable that the chromaticity of the front surface of the red emitted light is 0.29 ≦ y ≦ 0.34 and y + x ≧ 0.98 in the CIE-xy chromaticity diagram. The amber-colored emitted light is preferably 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, a predetermined value of current density is individually applied to each of the first light emitting unit 21 and the second light emitting unit 22, and the chromaticity of the generated light emitting lights h1 and h2 is measured.

The front luminance [L1] of the organic electroluminescence device of the present invention can be arbitrarily adjusted depending on the area used and is not particularly limited, but can be applied in the range of ^{, for example, 100 to 50,000 cd / m 2.}

<Details of each component of the organic electroluminescence element 1>
Next, the details of each component of the organic electroluminescence element 1 having the above light distribution characteristics will be described. Each component of the organic electroluminescence element 1 described below is an example for explaining an embodiment, and either one of the emitted light h1 and the emitted light h2 having the above-mentioned light distribution characteristics and chromaticity is used. Other configurations can be applied as appropriate within the obtained range.

[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 second electrode layer 30. It either functions or acts 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 one of the other is the first. 1 Functions as a cathode for supplying electrons to the light emitting unit 21. Here, as an example, a case where the first electrode layer 11 is used as an anode and the intermediate electrode layer 30 is used as a cathode is shown with respect to the first light emitting unit 21.

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

The first electrode layer 11 and the second electrode layer 12 as described above are configured by 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 the materials shown below, which are excellent in light transmission or light reflection, depending on whether or not the first electrode layer 11 and the second electrode layer 12 are electrodes arranged on the light extraction side. Is used. The anode and cathode constituting the first electrode layer 11 or the second electrode layer 12 will be described below.

(anode)
As the anode material used in the organic electroluminescence element 1, an electrode material composed of a metal having a large work function (4 eV or more, preferably 4.3 V or more), an alloy, an electrically conductive compound, and a mixture thereof is used. Specific examples of such an electrode material include metals such as Au and Ag, alloys thereof, and conductive transparent materials such as _{CuI, indium titanium oxide (ITO), SnO 2, and ZnO.} Further, IDIXO _(R: In ₂ O 3 -ZnO) may be a material capable of producing a transparent conductive film in amorphous such.

The anode can be produced by forming the anode material on a substrate by using a method such as thin film deposition or sputtering. In the case of a configuration in which the emitted light is taken out from the anode side, the transmittance of the anode is made larger than 10%, or a semi-transmissive semi-reflective electrode is used. The sheet resistance of the anode is several hundred Ω / sq. The following is preferable. The thickness of the anode depends on the material, but is usually selected in the range of 10 nm to 1 μm, preferably 10 to 200 nm.

(cathode)
As the cathode material used for the organic electroluminescence element 1, an electrode material composed of a metal having a small work function (4 eV or less), an alloy, an electrically conductive compound, and a mixture thereof 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 ) Examples thereof include a mixture, an indium, a lithium / aluminum mixture, an aluminum, silver, an alloy containing silver as a main component, an aluminum / silver mixture, and a rare earth metal.

The cathode can be produced by forming the cathode material on a substrate by using a method such as thin film deposition or sputtering. When the emitted light is taken out from the cathode side, the transmittance of the cathode is made larger than 10%, or a semi-transmissive semi-reflective electrode is used. The sheet resistance of the cathode is several hundred Ω / sq. The following is preferable. 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 is provided between the first electrode layer 11 and the intermediate electrode layer 30, and includes at least one light emitting layer containing an organic material having light emitting property. Further, the second light emitting unit 22 is provided between the intermediate electrode layer 30 and the second electrode layer 12, and includes at least one light emitting layer containing an organic material having light emitting property.

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

Typical layer configurations of the light emitting unit include, but are not limited to, the following configurations.
(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 injection transport layer (4) hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer (5) hole injection layer / hole transport layer / light emitting layer / Hole blocking layer / Electron transporting layer / Electron injection layer (6) Hole injection layer / Hole transporting layer / Electron blocking layer / Light emitting layer / Hole blocking layer / Electron transporting 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 have 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 also 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 also includes a hole injection layer and an electron blocking layer in a broad sense. Further, the hole transport layer may be composed of a plurality of layers.

Conventionally known materials and forming methods can be used for each layer constituting these light emitting units.

It is preferable that at least two light emitting units provided in the organic electroluminescence element 1 are light emitting units having the same layer and material except for the light emitting layer. Further, it is preferable that each light emitting unit has the same number of light emitting layers. As a result, the number of materials used can be reduced, and there are advantages in terms of production such as cost and quality control. Further, in the case of the vapor deposition process, there is an advantage in terms of production efficiency such that the film formation chamber can be easily shared by each light emitting unit.

Here, each layer constituting each light emitting unit has an interference degree of each light emitting light h1 and h2 when the brightness [L1] to [L3] of the light emitting light h1 and h2 are adjusted by utilizing the microcavity effect. It is assumed that the film thickness is designed according to the matching.

Further, each layer constituting each light emitting unit is combined with the above-mentioned film thickness design, or separately from the above-mentioned film thickness design, with the first electrode layer 11 of the external light incident on the organic electroluminescence element 1. It is preferable that the film thickness is designed so as to suppress interference with the second electrode layer 12. As a result, when the organic electroluminescence element 1 is set to non-emission, coloring due to interference of external light is prevented.

The film thickness of each of these layers 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 the value derived thereby.

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. When the adjusted electron transport layer has a thick film thickness 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 brightness [L1] to [L3] of the emitted lights h1 and h2 are adjusted by an optical film provided on the light extraction surface S side of the organic electroluminescence element 1, the thickness of each layer constituting the light emitting unit is adjusted. Is not particularly limited. However, in this case, from the viewpoint of ensuring the homogeneity of the film to be formed, lowering the drive voltage, and improving the stability of the emission color with respect to the drive current, the overall film thickness of each light emission unit should be within the range of 5 to 200 nm. It is preferable to adjust it, and further it is preferable to adjust it in the range of 10 to 100 nm or less.

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

[Light emitting layer]
The light emitting layer provides a place where electrons and holes injected from the first electrode layer 11, the second electrode layer 12, the intermediate electrode layer 30, or an adjacent layer recombine and emit light via excitons. It is a layer containing a light emitting organic semiconductor thin film. The light emitting layer preferably contains a light emitting dopant and a host compound. The luminescent dopant is also referred to as a luminescent dopant compound, a dopant compound, or simply a dopant. The host compound is also referred to as a matrix material, a luminescent host compound, or simply a host.

The method for forming the light emitting layer is not particularly limited, and the light emitting layer can be formed by, for example, a conventionally known vacuum vapor deposition method, a wet method, or the like. From the manufacturing cost of the organic electroluminescence device 1, it is preferable to form the organic electroluminescence device 1 by a wet method. The details of each compound constituting the light emitting layer are as follows.

(1. Luminous dopant)
As the light emitting dopant, a fluorescent 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 and device requirements used. The concentration of the light emitting dopant may be contained at a uniform concentration with respect to 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 types of light emitting dopants. For example, dopants having different structures may be used in combination, or a fluorescent dopant and a phosphorescent dopant may be used in combination. Thereby, an arbitrary emission color can be obtained.

As described above, in the organic electroluminescence element 1, it is preferable that one of the emission lights h1 and h2 is red emission light and the other is amber emission light. 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, it is achieved by including a red emitting dopant in the light emitting layer. When the emission light h2 from the second light emitting unit 22 arranged on the second electrode layer 12 side is amber-colored emission light, a red or green emission dopant having an emission light close to amber color is applied to the light-emitting layer. It is achieved by containing it alone or by containing a few kinds of red and green light emitting dopants in combination. When a red or green emission dopant having an emission light close to the amber color is contained alone, the optical design of the emission unit is performed so that only the emission spectrum near the amber color is extracted to the outside. Further, when amber color emission is obtained by combining red and green light emitting dopants, it is often the case that two kinds of the red and green light emitting dopants are combined.

When the organic electroluminescence element 1 further has a third light emitting unit, the third light emitting unit may generate white light as the light emitted. In this case, white emission light can be obtained by containing a plurality of emission dopants having different emission colors in the emission layer. The combination of luminescent dopants showing white color is not particularly limited, and examples thereof include a combination of blue and orange, a combination of blue, green, and red. The white color here means that the chromaticity in the CIE 1931 color system at ^{1000 cd / m 2} is x = 0.39 ± 0.09, y when the 2 ° viewing angle front luminance is measured by the above method. It is preferably within the region of = 0.38 ± 0.08.

(1-1. Phosphorescent dopant)
The phosphorescent dopant is a compound in which light emission from the excited triplet is observed. Specifically, it is a compound that emits phosphorescence at room temperature (25 ° C.), and the phosphorescence quantum yield is 0 at 25 ° C. It is a compound of 0.01 or more. The phosphorescent dopant used in the light emitting layer has a preferable phosphorescent quantum yield of 0.1 or more.

The phosphorus photon yield can be measured by the method described on page 398 (1992 edition, Maruzen) of Spectroscopy II of the 4th edition Experimental Chemistry Course 7. Phosphorus photon yield in solution can be measured using various solvents. As the phosphorescent dopant used in the light emitting layer, the phosphorescent quantum yield (0.01 or more) may be achieved in any of any solvents.

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

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

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

Fluorescent dopants include, for example, anthracene derivatives, pyrene derivatives, chrysene derivatives, fluorantene derivatives, perylene derivatives, fluorene derivatives, arylacetylene derivatives, styrylarylene derivatives, styrylamine derivatives, arylamine derivatives, boron complexes, coumarin derivatives, etc. Examples thereof include pyran derivatives, cyanine derivatives, croconium derivatives, squalium derivatives, oxobenzanthracene derivatives, fluorescein derivatives, rhodamine derivatives, pyrylium derivatives, perylene derivatives, polythiophene derivatives, and rare earth complex compounds.

Further, as the fluorescent dopant, a light emitting dopant using delayed fluorescence or the like may be used. Specific examples of the light emitting dopant using delayed fluorescence include the compounds described in International Publication No. 2011/156793, JP-A-2011-21364, and JP-A-2010-93181.

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

Further, the excited state energy of the host compound is preferably higher than the excited state energy of the light emitting dopant contained in the same layer.
The host compound may be used alone or in combination of two or more. By using a plurality of types of host compounds, it is possible to adjust the movement of electric charges, and it is possible to improve the efficiency of the organic electroluminescence device 1.

The host compound used in the light emitting layer is not particularly limited, and examples thereof include compounds used in ordinary organic electroluminescence devices. For example, it may be a small molecule compound, a polymer compound having a repeating unit, or a compound having a reactive group such as a vinyl group or an epoxy group.

As a known host compound, it has a hole transporting ability or an electron transporting ability, prevents the wavelength of light emission from being lengthened, and further, from the viewpoint of stability against heat generation when the organic electroluminescence device is driven at a high temperature or while the device is driven, from the viewpoint of stability. It is preferable to have a high glass transition temperature (Tg). As the host compound, Tg is preferably 90 ° C. or higher, more preferably 120 ° C. or higher.
Here, the glass transition point (Tg) is a value obtained 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 shown in the figure, when the first electrode layer 11 functions as an anode with respect to the first light emitting unit 21, the intermediate electrode layer 30 functions as a cathode with respect to the first light emitting unit 21. On the other hand, when 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.

Further, as shown in the drawing, when the second electrode layer 12 functions as a cathode with respect to the second light emitting unit 22, the intermediate electrode layer 30 functions as an anode with respect to the second light emitting unit 22. On the other hand, when the second electrode layer 12 functions as an anode with respect to the second light emitting unit 22, the intermediate electrode layer 30 functions as a cathode with respect to 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 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 light transmittance. In particular, when the brightness [L1] to [L3] of the emitted lights h1 and h2 are adjusted by utilizing the microcavity effect, the film thickness of the intermediate electrode layer 30 is adjusted together with the film thickness of each layer constituting the light emitting unit. However, it is assumed that the film thickness is designed according to the degree of interference of each emitted light of each light emitting unit.

Further, the intermediate electrode layer 30 is designed to have a film thickness so as to suppress the interference of the incident external light of the organic electroluminescence element 1 in combination with the film thickness design as described above or separately from the film thickness design as described above. It is preferable that it is. As a result, when the organic electroluminescence element 1 is set to non-emission, coloring due to interference of external light is prevented.

Based on the above, the film 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 material such as plastic or glass, and preferably a resin film or the like can be mentioned. Further, when the organic electroluminescence element 1 has a bottom emission structure that extracts emitted light h1 and h2 from the flexible substrate 10 side, the flexible substrate 10 is assumed to have light transmission.

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, and cellulose acetate propionate. CAP), cellulose acetate phthalate, cellulose esters such as cellulose nitrate or derivatives thereof, polyvinylidene chloride, polyvinyl alcohol, polyethylene vinyl alcohol, syndiotactic polystyrene, polycarbonate, norbornene resin, polymethylpentene, polyether ketone, polyimide , Polyether sulfone (PES), polyphenylene sulfide, polysulfones, polyetherimide, polyetherketoneimide, polyamide, fluororesin, nylon, polymethylmethacrylate, acrylic or polyarylates, Arton (trade name, manufactured by JSR) or Cycloolefin resins such as Apel (trade name, manufactured by Mitsui Kagaku Co., Ltd.) can be mentioned.

A gas barrier film may be formed on the surface of the resin film by a film of an inorganic substance, an organic substance, or a hybrid film of both of them. Gas barrier film was measured by the method based on JIS K 7129-1992, the water vapor transmission rate (25 ± 0.5 ° C., humidity of 90 ± 2% RH) is 0.01g ^/ (m 2 · 24h) following It is preferably a gas barrier film. Furthermore, the oxygen permeability was measured by the method based on JIS K 7126-1987 ^{is, 10 -3 mL / (m 2} · 24h · atm) or less, the water vapor ^{permeability, 10 -5 g / (m 2} · 24h) It is preferable that the film has a high gas barrier property of the following.

The material for forming the gas barrier film may be any material that has a function of suppressing infiltration of a material that causes deterioration of the element such as moisture and oxygen. For example, silicon oxide, silicon dioxide, silicon nitride and the like can be used. Further, in order to improve the vulnerability of the gas barrier film, it is more preferable to have a laminated structure of these inorganic layers and a layer made of an organic material. The stacking order of the inorganic layer and the organic layer is not particularly limited, but it is preferable to stack the inorganic layer and the organic layer alternately a plurality of times. The method for forming the gas barrier film is not particularly limited, and a conventionally known method can be used.

[Other components]
The organic electroluminescence element 1 has a sealing means for sealing a light emitting unit constructed by using an organic material. As the sealing means, known materials and forming methods can be adopted as long as the flexibility of the organic electroluminescence element 1 is not impaired. Further, in order to increase the mechanical strength of the organic electroluminescence element 1, a known protective film or protective plate may be provided on the outside of the sealing means within a range that does not impair the flexibility.

In the above embodiment, from the flexible substrate 10 side, the anode that becomes 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. An example shows a bottom emission type organic electroluminescence element 1 in which cathodes to be electrode layers 12 are laminated in this order. 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 the cathode and the second electrode layer 12 may be the 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 layers, and the number of layers of the light emitting layer are not particularly limited, and a desired organic electroluminescence element can be realized. For example, the organic electroluminescence element may have a configuration in which three or more light emitting units are laminated.

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

Next, an application example of the vehicle 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 vehicle lamp 2 is configured to distribute the emitted light to the rear of the vehicle 200. In FIG. 3, the directions seen from the driver of the vehicle 200 will be described as front, rear, left, and right.

The vehicle lighting fixture 2 includes a housing 203 attached to a recess formed in a rear corner of the vehicle 200, a translucent cover 204 formed according to the shape of the vehicle body of the vehicle 200 and covering the housing 203, and the housing 203 and the translucent cover 204. It is configured to include an organic electroluminescence element 1 as a light source provided in the lamp chamber 205 formed between the lamp chamber 205 and the lamp chamber 205.

The organic electroluminescence element 1 is formed in a band shape extending in the left-right direction of the vehicle 200, and is held in the housing 203 in a state of being partially curved in a convex shape according to the shape of the vehicle body of the vehicle 200.

Further, by appropriately selecting the material of the light emitting layer of the organic electroluminescence element 1, it is configured to generate red light emitting light h1 for the tail lamp and the stop lamp and amber light emitting light h2 for the turn lamp. Has been done. It should be noted that the organic electroluminescence element 1 which further exhibits white light may be used, and by providing a color filter, the emitted light of each of the above colors may be generated.

As described above, the organic electroluminescence element 1 provided as the vehicle lamp 2 may have different light emitting regions 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. Then, these two light emitting regions may be arranged so as to be staggered with a part of overlap on the upper part of the flexible substrate 10.

<< Effect of the embodiment >>
According to the organic electroluminescence element 1 of the embodiment described above, since the flexible substrate 10 is used, the light extraction surface S can be curved and used, so that the design can be matched to the body design of the car. A tall vehicle lighting fixture 2 can be constructed. Moreover, the light distribution characteristics of the light emitting lights h1 and h2 from the first light emitting unit 21 and the second light emitting unit 22 laminated 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 the convex direction and provided at the rear corner portion of the vehicle as a vehicle lamp, the visibility of the emitted lights h1 and h2 is improved. be able to.

Further, by providing an intermediate electrode layer 30 connected to an external electrode between the first light emitting unit 21 and the second light emitting unit 22, the first light emitting unit 21 and the second light emitting unit 22 individually emit light. The h1 and h2 were taken out and toned and emitted. As a result, the red light emission for the tail lamp and the amber light emission for the turn lamp can be emitted from the same lamp, which also makes it possible to improve the design of the vehicle lamp 2.

Further, by making the intermediate electrode layer 30 semitransparent and semi-reflective, each layer constituting the first light emitting unit 21 and the second light emitting unit 22 is used when designing the film thickness to make the emitted lights h1 and h2 have specific light distribution characteristics. The film thickness of the intermediate electrode layer 30 and the film thickness of the intermediate electrode layer 30 can be changed, and the degree of freedom in film thickness design is improved. Further, since the degree of freedom in designing the film thickness is improved, it is possible to suppress the interference of the external light incident on the organic electroluminescence element 1, so that the coloring of the vehicle lamp 2 due to the interference of the external light can be prevented. Will also be possible.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In the examples, the indication of "parts" or "%" is used, but unless otherwise specified, it indicates "parts by mass" or "% by mass".

<< Fabrication of Organic Electroluminescence Element 101 >>
An organic electroluminescence device 101 having the configuration shown in FIG. 1 was produced according to the following method.

(Preparation of flexible base material with gas barrier layer)
A polyethylene naphthalate film (a film manufactured by Teijin DuPont, hereinafter referred to as PEN film) was prepared. An inorganic gas barrier layer made of silicon oxide (SiOx) is formed on one main surface of this PEN film by using an atmospheric pressure plasma discharge processing apparatus having the structure described in JP-A-2004-68143. A flexible substrate 10 was formed so as to have a diameter of 500 nm and had a gas barrier layer.

(Formation of base layer)
The flexible substrate 10 with the gas barrier layer was fixed to the base material holder of a commercially available vacuum vapor deposition apparatus, and the substrate holder was attached to the vacuum chamber of the vacuum vapor deposition apparatus. Next, the inside of the vacuum chamber ^{was depressurized to 4 × 10 -4} Pa, and then a heating boat containing the following compound 1 which is a nitrogen-containing compound was energized and heated. As a result, compound 1 was vapor-deposited on the gas barrier layer of the flexible substrate 10 at a vapor deposition rate of 0.1 to 0.2 nm / sec to form a base layer having a film 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 the vacuum chamber of the vacuum vapor deposition apparatus. Next, after depressurizing the inside of the vacuum chamber to 4 × 10 ^-4 Pa, a heating boat containing silver (Ag) was energized and heated. As a result, the first electrode layer 11 made of silver (Ag) having a film thickness of 13 nm was formed at a vapor deposition rate of 0.1 to 0.2 nm / sec. The first electrode layer 11 is a transparent electrode and is formed as an anode.

(Formation of the first light emitting unit 21)
The first light emitting unit 21 was formed on the first electrode layer 11 as an anode according to 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 lower and an oxygen concentration of 1 ppm or less, and then forms the first light emitting unit 21 without being exposed to the atmosphere from the glove box. It was transferred into the vacuum chamber of the vacuum vapor deposition apparatus.

A resistance heating boat filled with the constituent materials of each layer in the optimum amount was installed in the vacuum chamber of the vacuum deposition apparatus. As the resistance heating boat, one made of a material for resistance heating made of molybdenum or tungsten was used.

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

Next, a resistance heating boat containing the compound M-2 (α-NPD) represented by the following chemical formula was energized and heated. As a result, compound M-2 (α-NPD) was deposited on the hole injection layer to form a hole transport layer (HTL) having a film thickness of 20 nm.

Next, the concentrations of compound GD-1, compound RD-1, and compound H-2 represented by the following chemical formulas are such that compound GD-1 has a volume ratio of 10% and compound RD-1 has a volume ratio of 10%. As described above, co-depositing was carried out at a vapor deposition rate of 0.1 nm / sec to form a phosphorus light emitting layer having a film thickness of 35 nm and exhibiting red color on the hole transport layer (HTL). The compound RD-1 has a maximum peak wavelength of 620 nm.

Then, the resistance heating boat containing the compound 1 was energized and heated. As a result, compound 1 was vapor-deposited on the phosphorescent layer at a vapor deposition rate of 0.1 nm / sec 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. As a result, lithium fluoride (LiF) was vapor-deposited on the electron transport layer (ETL) at a vapor deposition rate of 0.1 nm / sec to form an electron-injected layer having a film thickness of 1 nm.
As described above, the first light emitting unit 21 having a red phosphorescent light emitting layer was formed.

(Formation of 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 into each of the tungsten resistance heating boats, and these resistance heating boats and the flexible substrate 10 on which the first light emitting unit 21 is formed are vacuum-deposited. It was installed in the vacuum chamber of. After depressurizing the inside of this vacuum chamber to 4 × 10 ^-4 Pa, the resistance heating boats were independently energized and heated. As a result, aluminum (Al) and silver (Ag) are vapor-deposited on the first light emitting unit 21 in this order to form an intermediate electrode layer 30 having a film thickness ratio of aluminum (Al) 1 nm and silver (Ag) 15 nm. 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-mentioned compound M-1 was vapor-deposited on the intermediate electrode layer 30 at a vapor deposition rate of 0.1 nm / sec to form a hole injection layer having a film thickness of 18 nm.

Next, the above-mentioned compound M-2 was deposited on the hole injection layer to form a hole transport layer having a film thickness of 95 nm.

Next, the above-mentioned compound GD-1, the following compound RD-2, and the above-mentioned compound H-2 are adjusted so that the concentration of the compound GD-1 is 10% by volume and the concentration of the compound RD-2 is 10% by volume. Was co-deposited at a vapor deposition rate of 0.1 nm / sec 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.

Then, the above-mentioned compound 1 was vapor-deposited at a vapor deposition rate of 0.1 nm / sec to form an electron transport layer having a film thickness of 55 nm.

Further, lithium fluoride (LiF) was vapor-deposited at a vapor deposition rate of 0.1 nm / sec to form an electron-injected layer having a film thickness of 1 nm.
As described above, the second light emitting unit 22 having the amber-colored phosphorescent light emitting layer was formed.

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

(Preparation of sealing structure)
A sealing film was attached 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 as follows.

An adhesive was applied to a 0.7 mm thick non-alkali glass substrate and dried at 120 ° C. for 2 minutes to form an adhesive layer having a thickness of 20 μm. Further, an aluminum laminate film in which a polyethylene terephthalate film having a thickness of 50 μm was bonded to an aluminum foil having a thickness of 100 μm was prepared. The polyethylene terephthalate film side of the aluminum laminate film was bonded to the adhesive layer to form a sealing film. Then, the aluminum foil, the polyethylene terephthalate film, and the laminated body of the adhesive layer were peeled off from the non-alkali 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 was removed, the adhesive layer side of the sealing film was arranged so as to face the second electrode layer 12, and the vacuum was heated to 80 ° C. It was attached to the flexible substrate 10 by a laminator. Further, it was sealed by heating at 120 ° C. for 30 minutes. As a result, an organic electroluminescence device 101 in which a laminate from the first electrode layer 11 to the second electrode layer 12 is sealed between the flexible substrate 10 and the sealing film is produced. The produced organic electroluminescence device 101 has a light emitting region of 200 mm × 40 mm.

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

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

<< Fabrication of Organic Electroluminescence Element 112 (Comparative Example) >>
In the production of the organic electroluminescence device 101, except that the film thickness of the hole transport layer (HTL) and the film thickness of the electron transport layer (ETL) in the first light emitting unit 21 were changed as shown in Table 2 below. , Each organic electroluminescence element 112 was produced in the same manner.

<< Evaluation of Organic Electroluminescence Elements 101-112 >>
The organic electroluminescence devices 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 above are set on a rotating stage that automatically rotates, and the light intensity distribution and spectrum are used using a spectroluminance meter (manufactured by Konica Minolta, CS-2000). Was measured. ^{In the measurement, a constant current amount (5 mA / cm 2} ) is individually passed 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, and the first emission is emitted. 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 organic electroluminescence element 101 to 112 was set to 0 °, and measurement was performed a plurality of times within a range of ± 80 °. The rotary 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 electroluminescent devices 101 to 112 obtained as described above, the values of [L2] / [L1] and [L3] / [L1] are obtained for each organic electroluminescent device 101 to 112. I asked.

(2) Evaluation of Brightness Uniformity The organic electroluminescence elements 101 to 112 produced above were fixed in a state of being curved 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 individually passed 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, and the first light emission is performed. The unit 21 and the second light emitting unit 22 were made to emit light individually, and the central position of the light extraction surface S was visually observed from the front (normal line N direction) from an observation position 1 m away. The uniformity of the brightness of the entire light extraction surface S of each organic electroluminescence element 101 to 112 was evaluated by 10 general monitors according to the following criteria. If it is ◯ or Δ, it is judged that the uniformity of brightness is practically possible.
◯: Monitors of 9 or more people judged that the brightness of the light emitting area was uniform Δ: Monitors of 5 to 8 people judged that the brightness of the light emitting area was uniform ×: Monitors of 4 people or less However, it was determined that the brightness of the light emitting region was uniform.

(3) Evaluation of Appearance at Non-Light Emitting With respect to the organic electroluminescence elements 101 to 112 produced 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 being non-light emitting. The center position of the take-out surface S was visually observed from the front (normal line N direction). The appearance of each organic electroluminescence element 101 to 112 when not emitting light was evaluated by 10 general monitors according to the following criteria. If it is ◯ or Δ, it is judged that there is no coloring due to the interference of external light reflection.
◯: Monitors of 9 or more people judged to be the color of aluminum in the second electrode layer Δ: Monitors of 5 to 8 people judged to be the color of aluminum in the second electrode layer ×: 4 people or less However, even if it is ×, there is no problem in use.

Here, the chromaticity of the front surface of the emitted light of 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 unit of the organic electroluminescence elements 102 to 112 was in the range of x = ± 0.02 and y = ± 0.02 with respect to the organic electroluminescence element 101. ..
The chromaticity of the front surface of the emitted light of 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 unit of the organic electroluminescence elements 102 to 112 was in the range of x = ± 0.02 and y = ± 0.02 with respect to the organic electroluminescence element 101. ..

As shown in Table 2, the light distribution characteristics of the emitted light satisfy the relationship that 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 central position as compared with the light emitting unit that does not satisfy this relationship.

Specifically, the first light emitting unit of the organic electroluminescence element 105, the second light emitting unit of the organic electroluminescence element 106, the second light emitting unit of the organic electroluminescence element 107, the first light emitting unit of the organic electroluminescence element 108, and 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.

Further, a light emitting unit satisfying the relationship that the light distribution characteristics of the emitted light are 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 central position was further excellent.

Further, from the evaluation results of brightness uniformity 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 if the relationship of 0.15 ≦ [L3] / [L1] ≦ 0.47 is satisfied, the red light emitted from the first light emitting unit and the amber light emitted from the second light emitting unit It was confirmed that both of them were more reliably and uniformly extracted from the light extraction surface S curved in the convex direction.

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

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

1 ... Organic electroluminescence element.
10 ... Flexible substrate 11 ... First electrode layer 12 ... Second electrode layer 21 ... First light emitting unit (light emitting unit)
22 ... Second light emitting unit (light emitting unit)
30 ... Intermediate electrode layer [L1] ... Front brightness [L2] ... Brightness with a viewing angle of 20 ° [L3] ... Brightness with a viewing angle of 60 ° 2 ... Vehicle lighting fixtures

Claims (8)

Flexible substrate and
The first electrode layer provided on the flexible substrate and
A second electrode layer provided above the first electrode layer and
At least two light emitting units having a light emitting layer constructed by using an organic material and arranged so as to be overlapped between the first electrode layer and the second electrode layer.
An intermediate electrode layer arranged between the light emitting units is provided.
The at least two light emitting units have different chromaticities of the light emitted from each other.
Wherein at least one of the light distribution characteristics from the light emitting unit and the flexible substrate side or the light-emitting light is taken out to the second electrode layer side of the at least two light emitting units, the front luminance [L1], the luminance of the viewing angle 20 ° When the brightness of [L2] and the viewing angle of 60 ° is [L3], 0.85 ≦ [L2] / [L1] ≦ 1.20 and [L3] / [L1] ≦ 0.50. And
An external power source is connected to the first electrode layer, the second electrode layer, and the intermediate electrode layer.
The at least two light emitting units and the intermediate electrode layer are organic electroluminescence elements whose film thickness is designed so as to prevent interference of external light between the first electrode layer and the second electrode layer. The organic electroluminescence device according to claim 1, wherein the at least two light emitting units have different maximum peak wavelengths of the light emitted from each other. The organic electroluminescence device according to claim 1 or 2, 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, 0.85 ≦ [L2] / [ L1] is ≦ 1.20, and [L3] / [L1] a ≦ 0.50 is claim 1 Or the organic electroluminescence device according to 2. Claim 1 in which the light distribution characteristics of all of the at least two light emitting units are 0.90 ≦ [L2] / [L1] ≦ 1.10 and [L3] / [L1] ≦ 0.45. 4. The organic electroluminescence device according to any one of 4. One of the at least two light emitting units has the chromaticity of the front surface of the emitted light of 0.29 ≦ y ≦ 0.34 and y + x ≧ 0.98 in the CIE-xy chromaticity diagram. 5. The organic electroluminescence element according to any one of 5. In one of the at least two light emitting units, the chromaticity of the front surface of the emitted light is y ≧ 0.39, y ≧ 0.79-0.67x, y ≦ x-0 in the CIE-xy chromaticity diagram. The organic electroluminescence element according to any one of claims 1 to 5, which is .12. A vehicle lamp using the organic electroluminescence element according to any one of claims 1 to 7.

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