WO2018083974A1

WO2018083974A1 - Organic electroluminescent element and light emitting device

Info

Publication number: WO2018083974A1
Application number: PCT/JP2017/037523
Authority: WO
Inventors: 岡本　健; 中山　知是
Original assignee: コニカミノルタ株式会社
Priority date: 2016-11-04
Filing date: 2017-10-17
Publication date: 2018-05-11

Abstract

An organic electroluminescent element which comprises n light emitting units and (n + 1) or more electrodes on a supporting substrate, while comprising a transparent electrode, the first light emitting unit, -omitted-, the n-th electrode, the n-th light emitting unit and the (n + 1)th electrode sequentially from the supporting substrate side. A light emitting unit that has a peak wavelength of the emission spectrum closest to 555 nm has the smallest half-value width of the emission spectrum among all the light emitting units.

Description

ORGANIC ELECTROLUMINESCENT ELEMENT AND LIGHT EMITTING DEVICE

The present invention relates to an organic electroluminescence element and a light-emitting device provided with the organic electroluminescence element.

An organic electroluminescence (EL) element is self-luminous and can be reduced in thickness, power consumption is reduced, and response speed is high.
In lighting applications, if the light emission color of the organic EL element can be changed, a color effect can be obtained effectively. For this reason, the toning function capable of changing the emission color in the organic EL element is an important function. As one form of such a toning function, an element in which a toning (dimming) unit is provided in an organic EL element has been proposed (see, for example, Patent Document 1 and Patent Document 2).

Further, in the configuration organic EL element in which a plurality of electrodes and light emitting units are laminated, when toning, each light emitting unit cannot be driven at the same time. A method of driving a light emitting unit and a method of using an intermediate electrode as a common anode are common. By performing such driving, it is possible to freely combine colors and luminances of the respective light emitting units to express various colors (for example, see Non-Patent Document 1 and Non-Patent Document 2).

JP 2009-99400 A JP 2014-120334 A

In the above-described organic EL element, the half width of the emission spectrum is large in the light emitting unit that emits light with high relative visibility. For this reason, various wavelengths are included in the emission spectrum. However, in the manufacture of an organic EL element, when the film thickness of the light emitting unit varies due to film formation variation or the like, the wavelength emphasized by the microcavity effect deviates from the design value. When such a film thickness variation occurs, a light emitting unit that emits light with high relative visibility like the above-described organic EL element includes a large amount of light having a wavelength that deviates from the design value emphasized by the microcavity effect. Therefore, the light emission performance such as chromaticity and luminance of the organic EL element greatly varies.

As described above, when the light emitting performance of the organic EL element greatly varies due to the variation in film thickness, productivity, yield, and the like decrease. Accordingly, there is a demand for an organic EL element that can suppress fluctuations in light emission performance even in film thickness fluctuations when forming each layer.

In order to solve the above-described problems, in the present invention, an organic electroluminescence element and a light-emitting device that can suppress fluctuations in light emission performance with respect to film thickness fluctuations of each layer constituting the organic electroluminescence element are provided. provide.

The organic electroluminescent element of the present invention includes n light emitting units and n + 1 or more electrodes provided on a support substrate, and from the support substrate side, a transparent electrode, a first light emitting unit, ... n An organic electroluminescence element having an electrode, an nth light emitting unit, and an (n + 1) th electrode, and a light emitting unit having a peak wavelength of the emission spectrum closest to 555 nm has the smallest half-value width of the emission spectrum among all the light emitting units.
Moreover, the light-emitting device of this invention is equipped with the said organic electroluminescent element.

According to the present invention, it is possible to provide an organic electroluminescence element and a light emitting device capable of suppressing fluctuations in light emission performance with respect to film thickness fluctuations of each layer constituting the organic electroluminescence element.

It is a figure which shows the structure of an organic EL element. It is a figure which shows the emission spectrum of each light emission unit of an organic EL element. It is a graph of photopic standard relative luminous sensitivity. It is a figure which shows the structure of an organic EL element. It is a figure which shows the emission spectrum of each light emission unit of the organic EL element of the sample 101 of an Example.

Hereinafter, although the example of the form for implementing this invention is demonstrated, this invention is not limited to the following examples.
The description will be given in the following order.
1. 1. Outline of organic electroluminescence device 2. Embodiment of organic electroluminescence device Embodiment of light emitting device

<1. Outline of Organic Electroluminescence Device>
Prior to description of specific embodiments of the organic electroluminescence (EL) element, an outline of the organic EL element of the present invention will be described.

FIG. 1 shows an element configuration of a general organic EL element. The organic EL element shown in FIG. 1 includes a transparent electrode 11, a first light emitting unit 12, a first intermediate electrode 13, a second light emitting unit 14, a second intermediate electrode 15, a third light emitting unit 16, and a reflective electrode 17 laminated. It has the structure made. That is, the organic EL element has a configuration in which three layers of light emitting units are stacked via the first intermediate electrode 13 and the second intermediate electrode 15. In FIG. 1, only the configuration related to the design method of the organic EL element is shown, and the configuration of the substrate and the like is omitted.

The organic EL element shown in FIG. 1 has a configuration in which the first light emitting unit 12 arranged closest to the transparent electrode 11 emits light (L1). The second light emitting unit 14 emits light (L2), and the third light emitting unit 16 emits light (L3).

As shown in FIG. 1, in an organic EL element, a plurality of light emitting units are provided, and white light is obtained by synthesizing light from each light emitting unit. Further, by using time-division driving of each light-emitting unit and using the intermediate electrode as a common anode, it is possible to express various colors by freely combining the colors and luminance of each light-emitting unit.

In the organic EL element having such a configuration, a microcavity (microresonator) structure is incorporated in the organic EL element. The microcavity structure adjusts the thickness of the light emitting unit to resonate and emphasize light of a specific wavelength between the electrodes (cathode / anode), weaken the light of other wavelengths, and extract light to the outside The spectrum can be steep and high intensity. Thereby, in an organic EL element, the brightness | luminance and color purity of the light of a specific wavelength can be improved.

FIG. 2 shows an example of emission spectra of the light L1, L2, and L3 emitted from each light emitting unit of the organic EL element having the configuration shown in FIG. In each emission spectrum shown in FIG. 2, the light L1 from the first light emitting unit 12 has a peak at a wavelength of 475 nm, the light L2 from the second light emitting unit 14 has a peak at a wavelength of 560 nm, and the third light emitting unit 16 This is an example in which the light L3 from the light has a peak at a wavelength of 594 nm. In addition, the emission spectrum shown in FIG. 2 is an emission spectrum at the time of making the element which formed each light emission unit independently emit light. The total emission spectrum of the organic EL element is a spectrum obtained by combining the emission spectra of the respective light emitting units.

As shown in FIG. 2, the emission spectra of the light emitting units of three colors, red, green, and blue, each have their own peak and spread in a predetermined range, thereby extracting white light from the organic EL element. It is. Further, various colors can be expressed by freely combining the luminances of the emission spectra of the light emitting units of three colors of red, green, and blue.

Next, a graph of photopic standard relative luminous sensitivity is shown in FIG. Visibility represents the degree to which the human eye perceives light at each wavelength. As shown in FIG. 3, in a bright place, the light with a wavelength of 555 nm has the highest visibility, and the light with a wavelength closer to 555 nm has a higher visibility.

As shown in FIG. 2, in the organic EL element described above, the light L2 from the second light emitting unit 14 having a peak at a wavelength of 560 nm has a peak at a position closest to the wavelength of 555 nm. Therefore, in the organic EL element, the light L2 from the second light emitting unit 14 has the highest visibility. Further, as shown in FIG. 2, the light L2 from the second light emitting unit 14 has a half-value width of the emission spectrum, compared to the light L1 from the first light emitting unit 12 and the light L3 from the third light emitting unit 16. Large and wide spectrum distribution. For this reason, the light L2 from the second light-emitting unit 14 is contained in a large amount at a wavelength with relatively high visibility.

In designing the organic EL element, the organic EL element is set so that a specific wavelength is amplified by the microcavity effect by adjusting the thickness of each layer constituting the organic EL element. For example, in the light L1 from the first light emitting unit 12, the thickness of each layer of the organic EL element is set so that light with a wavelength of 475 nm is amplified. Similarly, in the light L2 from the second light emitting unit 14, the thickness of each layer of the organic EL element is set so that light with a wavelength of 560 nm is amplified, and in the light L3 from the third light emitting unit 16, the wavelength of 594 nm is set. The thickness of each layer of the organic EL element is set so that light is amplified.

However, when manufacturing an organic EL element, the thickness of each layer constituting the organic EL element varies during film formation. In this case, when the thickness of each layer constituting the organic EL element deviates from the design value, the wavelength amplified by the microcavity effect also deviates from the design value for the light emitted from each light emitting unit. For example, the peak wavelength of the light emitted from each light emitting unit is shifted and an amplified wavelength other than the peak wavelength is generated.

At this time, the light L1 from the first light-emitting unit 12 and the light L3 from the third light-emitting unit 16 have lower relative visibility than the light L2 from the second light-emitting unit 14, and therefore the half-value width is further reduced. Since the relative intensity of the wavelength that is small and deviated from the peak wavelength is low, even if a wavelength amplified by the microcavity effect other than the peak wavelength is generated, the influence on the light emitted from the organic EL element is small. For this reason, in the light emission of an organic EL element, a color shift and a luminance change are hardly visually recognized.

However, since the light L2 from the second light emitting unit 14 has high specific visibility, the half-value width is large, and the wavelength deviated from the peak wavelength has high relative intensity. Therefore, the light L2 is amplified by the microcavity effect in addition to the peak wavelength. When a wavelength is generated, a color shift or luminance change of the light L2 due to an amplified wavelength other than the peak wavelength is easily recognized. For this reason, the color shift and the luminance change of the light L2 due to the amplified wavelength other than the peak wavelength are easily visible in the light emitted from the organic EL element.

Therefore, if the half-value width of the light emitting unit that emits light with the highest relative visibility among the light emitting units that constitute the organic EL element, such as the light L2 from the second light emitting unit 14, is large, Due to the variation in thickness, the light emission performance such as chromaticity and luminance of the organic EL element greatly varies. When the light emission performance of the organic EL element greatly varies due to such a film thickness variation, the productivity and yield of the organic EL element are greatly decreased.

In order to improve the productivity and the yield of the organic EL element in response to this problem, the light emission of the organic EL element can also be applied to the thickness variation during the formation of the organic EL element. It is necessary to suppress fluctuations in performance. For this purpose, in the organic EL element, it is necessary to reduce the half-value width of the emission spectrum of the light emitted from the light emitting unit having high specific visibility, and to reduce the relative intensity of the wavelength shifted from the peak.

By reducing the half-value width of the emission spectrum of a light emitting unit with high specific visibility, the relative intensity of wavelengths other than the peak wavelength is reduced. Can be small. For this reason, even when light having a wavelength that is amplified by a microcavity effect other than the peak wavelength is generated in a light emitting unit with high specific luminous efficiency, the color shift or luminance of light emitted from the light emitting unit with high specific visual sensitivity. Changes are less likely to be recognized. Furthermore, it is possible to reduce the influence of the color shift or luminance change of the light emitted from the light emitting unit having a high specific visibility on the light emitted from the organic EL element.

Therefore, in the organic EL element, by reducing the half width of the emission spectrum of the light emitting unit having the highest specific luminous efficiency, even if the thickness of each layer varies during film formation, the variation in the light emitting performance is reduced. Is possible. That is, for a light emitting unit whose peak wavelength of the emission spectrum is closest to 555 nm, the light emitted from the light emitting unit is reduced by making the half width of the emission spectrum smaller than the half width of the emission spectra of all other light emitting units. The color shift and the luminance change are less visible even in the light emitted from the organic EL element. As a result, even in the film thickness fluctuation when forming each layer constituting the organic electroluminescence element, it becomes possible to suppress the fluctuation of the light emission performance, and to suppress the decrease in the productivity and the yield of the organic EL element. Can do.

In the organic EL element, the method for adjusting the half-value width of the emission spectrum is not limited. Any method may be used as long as the half-value width of the emission spectrum of the light emitting unit having high specific visibility can be made smaller than that of other light emitting units. For example, a method for adjusting the half width of the emission spectrum includes a method of selecting a light emitting material to be used in the light emitting layer constituting the light emitting unit. Specifically, the half width of the emission spectrum tends to be smaller when a fluorescent light emitting material is used than when a phosphorescent light emitting material is used as the light emitting material. For this reason, it is preferable that the light emitting unit having the peak wavelength of the emission spectrum closest to 555 nm includes a fluorescent light emitting material as the light emitting material. Furthermore, it is preferable that this light emitting unit contains only a fluorescent light emitting material as a light emitting material.

Also, color shift and luminance fluctuation due to film thickness fluctuation and microcavity effect are likely to occur in a configuration in which the organic EL element has an intermediate electrode, particularly in a configuration in which a metal having a high reflectance is used for the intermediate electrode. This is because reflection at the intermediate electrode is added, and for example, it is more likely to occur more significantly in an organic EL element configured to perform color adjustment using the intermediate electrode.

For this reason, in the structure having an intermediate electrode, in particular, in an organic EL element having a metal material having a high reflectance such as silver or aluminum as the intermediate electrode, as described above, the light emitting unit having the peak wavelength of the emission spectrum closest to 555 nm Is preferably designed so that the half-value width of the emission spectrum is smaller than the half-value widths of the emission spectra of all other light-emitting units.

In the above description, an organic EL element having three layers of light emitting units and capable of emitting three colors is used. However, for a light emitting unit whose peak wavelength of the emission spectrum is closest to 555 nm, the half width of the emission spectrum. The organic EL element to which the configuration in which the light emission spectrum is smaller than the half-value width of the emission spectrum of all other light emitting units is not limited to the above-described configuration. The above structure can also be applied to an organic EL element having two or four or more light emitting units and capable of emitting light of two colors or four colors. For example, when the organic EL element has two layers of light emitting units, and each light emitting unit has two emission colors of blue or yellow, the light emitting unit having a yellow emission color has a peak wavelength of the emission spectrum. It approaches 555 nm. For this reason, the half width of the emission spectrum of the light emitting unit having the yellow emission color is made smaller than the half width of the emission spectrum of the light emitting unit having the blue emission color. As a result, even in an organic EL element having a two-layer light emitting unit, it is possible to suppress variation in light emission performance due to film thickness variation. Thus, for the light emitting unit whose emission spectrum peak wavelength is closest to 555 nm, the configuration in which the half width of the emission spectrum is smaller than the half width of the emission spectra of all other light emitting units is the number of stacked light emitting units. Can be applied regardless.

<2. Embodiment of Organic Electroluminescence Device>
Hereinafter, a configuration of the organic EL element capable of suppressing the variation in the light emission performance due to the above-described film thickness variation will be described. In addition, the following description is an example of the component which can comprise the organic electroluminescent light emitting device of embodiment, and it is also possible to apply another structure.

[Organic EL device]
FIG. 1 shows an element configuration of an organic EL element having three layers of light emitting units. The organic EL element shown in FIG. 1 is provided on one main surface of a support substrate (unknown), and in order from the support substrate side, a transparent electrode 11 (first electrode), a first light emitting unit 12, and a first intermediate. The electrode 13 (second electrode), the second light emitting unit 14, the second intermediate electrode 15 (third electrode), the third light emitting unit 16, and the reflective electrode 17 (fourth electrode) are stacked. That is, the organic EL element has a configuration in which three layers of light emitting units are stacked via the first intermediate electrode 13 and the second intermediate electrode 15.

FIG. 4 shows an element configuration of an organic EL element having two layers of light emitting units. The organic EL element shown in FIG. 4 is provided on one main surface of a support substrate (unknown), and in order from the support substrate side, the transparent electrode 11 (first electrode), the first light emitting unit 12, and the first intermediate. The electrode 13 (second electrode), the second light emitting unit 14, and the reflective electrode 17 (third electrode) are stacked. In the organic EL element shown in FIG. 4, a power source 18, a power source 19, and a control unit 20 for driving the organic EL element are also shown along with the configuration of the organic EL element.

In the organic EL element, each light emitting unit (the first light emitting unit 12, the second light emitting unit 14, and the third light emitting unit 16) is configured using a material having individual optical characteristics. For this reason, each light emitting unit emits light having a different wavelength. The organic EL element is configured as a bottom emission type in which emitted light obtained by each light emitting unit is extracted from the support substrate side.

In the organic EL element shown in FIG. 4, a power source 18 is connected to the transparent electrode 11 and the first intermediate electrode 13 from the outside, and a power source 19 is connected to the first intermediate electrode 13 and the reflective electrode 17 from the outside. ing. The transparent electrode 11, the first intermediate electrode 13, and the reflective electrode 17 can be independently controlled by the control unit 20 via the power supplies 18 and 19.

[Support substrate]
The support substrate has light transmittance with respect to the emitted light generated by each light emitting unit in the visible light. Examples of the transparent substrate material constituting the support substrate include glass, quartz, and a resin substrate. A particularly preferable support substrate is a resin substrate that can give flexibility to the organic EL element. The resin substrate may be configured to have a gas barrier layer as necessary.

A conventionally known resin material is used as the resin material constituting the resin substrate. For example, acrylic resin such as acrylic acid ester, methacrylic acid ester, polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene naphthalate (PEN), polycarbonate (PC), polyarylate, polyvinyl chloride ( PVC), polyethylene (PE), polypropylene (PP), polystyrene (PS), nylon (Ny), aromatic polyamide, polyether ether ketone, polysulfone, polyether sulfonate, polyimide, polyether imide, polyolefin, epoxy resin, etc. Examples of the resin film include cycloolefin resins and cellulose ester resins. In addition, a heat-resistant transparent film (product name: Sila-DEC, manufactured by Chisso Corporation) having silsesquioxane having an organic-inorganic hybrid structure as a basic skeleton, and a resin film formed by laminating two or more layers of resin materials, etc. It is done.

[Transparent electrode]
The transparent electrode 11 is in a state of being electrically connected to the first intermediate electrode 13 via the power source 18. The transparent electrode 11 is provided as an anode or a cathode for the first light emitting unit 12. The transparent electrode 11 is used as an anode when the first intermediate electrode 13 is a cathode, and is used as a cathode when the first intermediate electrode 13 is an anode. Moreover, the transparent electrode 11 has a light transmittance with respect to the emitted light especially generated in each light emitting unit among visible light.

The transparent electrode 11 is composed of a conductive material suitable for an anode or a cathode, respectively, using the above-described conductive material having excellent light transmittance. Examples of the conductive material suitably used for the transparent electrode 11 include transparent conductive materials such as oxide semiconductors such as ITO, ZnO, TiO ₂ , and SnO ₂ .

Further, the transparent electrode 11 may be composed of a metal thin film mainly composed of metal. The metal thin film is a metal film having a thickness in the range of 8 to 30 nm. The metal contained in the metal thin film is not particularly limited as long as it is a highly conductive metal, and examples thereof include silver, copper, gold, platinum group, titanium, and chromium. The transparent electrode 11 may contain only one kind of these metals or two or more kinds.

From the viewpoint of high conductivity, the transparent electrode 11 is preferably composed of silver as a main component, and is preferably composed of silver or an alloy containing silver as a main component. Examples of the alloy mainly composed of silver (Ag) constituting the transparent electrode 11 include silver magnesium (AgMg), silver copper (AgCu), silver palladium (AgPd), silver palladium copper (AgPdCu), and silver indium (AgIn). ) And the like.

Further, when the transparent electrode 11 is composed of a metal thin film, the transparent electrode 11 is preferably provided in contact with the underlayer. The foundation layer is a layer provided on the support substrate side of the transparent electrode 11. The material constituting the underlayer is not particularly limited. For example, it preferably has an action of suppressing aggregation of silver when forming the transparent electrode 11 made of silver or an alloy containing silver as a main component. As an example, a nitrogen-containing compound or a sulfur-containing compound may be mentioned.

The transparent electrode 11 has a sheet resistance of 30Ω / sq. Or less, preferably 10 Ω / sq. The following is more preferable. Further, the transparent electrode 11 preferably has a light transmittance of 30% or more at a wavelength of 550 nm, and more preferably 50% or more.

[Light emitting unit]
The light emitting units (the first light emitting unit 12, the second light emitting unit 14, and the third light emitting unit 16) have a light emitting layer configured using an organic material. The 1st light emission unit 12 is provided in the transparent electrode 11 side among several light emission units. Each light emitting unit is a laminate including at least a light emitting layer made of an organic material. Further, the laminated structure of each light emitting unit is not limited, and may be any of the common laminated structures as shown in the following examples (i) to (vi), and further, if necessary, a layer is formed. You may have. In addition, the detail of each layer which comprises a light emission unit is mentioned later.

(I) (anode) / hole injection transport layer / light emitting layer / electron injection transport layer / (cathode)
(Ii) (anode) / hole injection transport layer / light emitting layer / hole blocking layer / electron injection transport layer / (cathode)
(Iii) (anode) / hole injection / transport layer / electron blocking layer / light emitting layer / hole blocking layer / electron injection / transport layer / (cathode)
(Iv) (anode) / hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer / (cathode)
(V) (anode) / hole injection layer / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / electron injection layer / (cathode)
(Vi) (anode) / hole injection layer / hole transport layer / electron blocking layer / light emitting layer / hole blocking layer / electron transport layer / electron injection layer / (cathode)

[Intermediate electrode]
The intermediate electrode is an electrode provided between the light emitting units, and is provided between the first light emitting unit and the nth light emitting unit. The intermediate electrode is provided as an anode or a cathode for each light emitting unit, and is used as a cathode when the transparent electrode 11 is an anode. Further, when the reflective electrode 17 is an anode, it is used as a cathode, and when the reflective electrode is a cathode, it is used as an anode. Each intermediate electrode is electrically connected to the transparent electrode 11 via

power sources

18 and 19 and is electrically connected to the reflective electrode 17 via a power source 19.

The intermediate electrode is composed of a material suitable for the transparent electrode 11 described above using a conductive material having excellent light transmittance. In particular, the intermediate electrode is preferably composed mainly of silver or aluminum. Further, the second intermediate electrode 15 may include a metal oxide such as IZO. The intermediate electrode preferably has the same sheet resistance and light transmittance as the transparent electrode 11.

The thickness of the intermediate electrode is preferably 6 nm or more and 25 nm or less. By setting the thickness of the intermediate electrode to 6 nm or more, the intermediate electrode can have sufficient conductivity required for the electrode. Further, by setting the thickness to 25 nm or less, sufficient light transmittance can be ensured.

[Reflective electrode]
The reflective electrode 17 is provided as an anode or a cathode for the second light emitting unit 14, and is used as an anode when the first intermediate electrode 13 is a cathode, and as a cathode when the first intermediate electrode 13 is an anode. The reflective electrode 17 is in a state of being electrically connected to the first intermediate electrode 13 via the power source 19.

The reflective electrode 17 preferably has good reflection characteristics with respect to the emitted light generated by each light emitting unit in the visible light. Such a reflective electrode 17 is comprised using the metal material excellent in the reflective characteristic from the electroconductive material suitable as a cathode or an anode. For example, the reflective electrode 17 is made of gold, platinum, silver, copper, aluminum or the like.

[Power supply]
The power source is connected to each electrode of the organic EL element. For example, in the organic EL element shown in FIG. 4, one power source 18 is connected to the transparent electrode 11 and the first intermediate electrode 13. The power source 18 has a positive electrode connected to the anode side of the first light emitting unit 12 and a negative electrode connected to the cathode side of the transparent electrode 11 and the first intermediate electrode 13. The other power source 19 is connected to the first intermediate electrode 13 and the reflective electrode 17. The power source 19 has a positive electrode connected to the anode side of the second light emitting unit 14 and a negative electrode connected to the cathode side of the first intermediate electrode 13 and the reflective electrode 17.

In the configuration of the organic EL element shown in FIG. 4, the transparent electrode 11 is connected to the positive electrode of the power source 18 as the anode of the first light emitting unit 12, and the first intermediate electrode 13 is the negative electrode of the power source 18 as the cathode of the first light emitting unit 12. Connected to the pole. The first intermediate electrode 13 is connected to the positive electrode of the power source 19 as the anode of the second light emitting unit 14, and the reflective electrode 17 is connected to the negative electrode of the power source 19 as the cathode of the second light emitting unit 14. In addition, what is necessary is just to reverse the connection with the power supplies 18 and 19 when the laminated structure of the 1st light emission unit 12 and the 2nd light emission unit 14 is reverse.

The

power sources

18 and 19 are configured such that the voltage and current applied to the transparent electrode 11, the first intermediate electrode 13, and the reflective electrode 17 are controlled by the control unit 20. The control unit 20 can be configured by a computer or the like, for example. Thereby, the light emission ratio and the light emission amount of each light emitting unit can be controlled, and the light control property and the color control property can be improved. It is also possible to individually control the light emission of each light emitting unit. In addition, the control unit 20 performs control to make the total current supplied to each light emitting unit constant, and control to make the current of the light emitting unit with high visibility constant. By such control, it is possible to perform effective light adjustment and color adjustment of the organic EL element.

It should be noted that the organic EL element only needs to have at least two power supplies, but may have a larger number of power supplies. However, in order not to complicate the apparatus, it is preferable that the number of power sources is smaller than the number of electrodes.

[Other configurations]
The organic EL element preferably has a sealing material that covers from the transparent electrode 11 to the reflective electrode 17 on the support substrate. Furthermore, you may provide the protective member which covers this sealing material. The protective member is for mechanically protecting the organic EL element, and in particular, when the sealing material is a sealing film, mechanical protection for the organic EL element is not sufficient. It is preferable to provide it. As the protective member, a glass plate, a polymer plate, a polymer film, a metal plate, a metal film, or a polymer material film or a metal material film is applied. Among these, it is preferable to use a polymer film from the viewpoint of light weight and thinning.

In addition, the organic EL element may have a light extraction layer for efficiently extracting emitted light generated by each light emitting unit in a necessary portion as necessary. Further, the organic EL element may have an auxiliary electrode with good conductivity connected to the transparent electrode 11, the first intermediate electrode 13, and the second intermediate electrode 15 at a position that does not overlap the light emitting region. Good. The material constituting the auxiliary electrode is preferably a metal having low resistance such as gold, platinum, silver, copper, or aluminum.

[Drive of organic EL element]
The organic EL element configured as described above generates emitted light in the light emitting region of each light emitting unit by applying a voltage in a predetermined state between the electrodes. The emitted light passes through the transparent electrode 11 and the support substrate, and is observed as a light emitting region on the light extraction surface side of the support substrate. The organic EL element may be driven by applying an AC voltage, and the AC waveform to be applied may be arbitrary.

[Other modified configurations]
The organic EL element described above has a configuration in which three layers of light emitting units of the first light emitting unit 12, the second light emitting unit 14, and the third light emitting unit 16 are stacked, or the first light emitting unit 12 and the first light emitting unit 12. The two light emitting units of the two light emitting units 14 are stacked. However, the organic EL element may have a configuration in which a plurality of light emitting units are further stacked. Even in this case, for the light emitting unit whose peak wavelength of the emission spectrum is closest to 555 nm, it is sufficient that the half width of the emission spectrum is smaller than the half widths of the emission spectra of all other light emitting units.

[Material of each layer constituting light emitting unit]
Details of the constituent materials of each layer constituting each light emitting unit are shown below. Each light emitting unit is made of a material suitable for the configuration of the organic EL element from the following materials.

[Light emitting layer]
The light-emitting layer is a layer that emits light by recombination of electrons injected from the cathode side and holes injected from the anode side, and the light-emitting portion is adjacent to the light-emitting layer even in the layer of the light-emitting layer. It may be an interface with the layer to be used. In the light emitting layer, a phosphorescent light emitting material or a fluorescent light emitting material may be used as a light emitting material, or a phosphorescent light emitting material and a fluorescent light emitting material may be used in combination. The light emitting layer may contain a plurality of light emitting materials.

In addition, as described above, in the light emitting unit whose peak wavelength of the emission spectrum is closest to 555 nm, it is preferable to use a light emitting material having a smaller half width of the emission spectrum than the light emitting materials used in other light emitting units. For example, a fluorescent light emitting material having a small half width of the light emission spectrum is used for the light emitting unit whose emission spectrum peak wavelength is closest to 555 nm, and a fluorescent light emitting material having a large full width at half maximum of the light emission spectrum or phosphorescence emission is used for the other light emitting units. It is preferable to use a material.

Further, as the luminescent material, a thermally activated delayed fluorescence (TADF) material can also be used. As the TADF material, the following compounds can be exemplified.

The light emitting layer is not particularly limited in its configuration as long as the light emitting material included satisfies the light emission requirements. Moreover, there may be a plurality of layers having the same emission spectrum and emission maximum wavelength. In this case, it is preferable to have a non-light emitting intermediate layer (not shown) between the light emitting layers.

The total film thickness of the light emitting layer is preferably in the range of 1 to 100 nm, and more preferably in the range of 1 to 40 nm because a lower driving voltage can be obtained. The total film thickness of the light emitting layer includes the intermediate layer when a non-light emitting intermediate layer exists between the light emitting layers. However, in the case of a so-called tandem element in which a plurality of light emitting layer units are stacked via an intermediate connector, the light emitting layer here is the sum of the light emitting layers in each light emitting unit not including the intermediate connector portion.

In the case of a light emitting layer having a structure in which a plurality of layers are laminated, the thickness of each light emitting layer is preferably adjusted within a range of 1 to 50 nm, and more preferably adjusted within a range of 1 to 20 nm. preferable. When the plurality of stacked light emitting layers correspond to blue, green, and red light emitting colors, there is no particular limitation on the relationship between the film thicknesses of the blue, green, and red light emitting layers.

The light emitting layer as described above is formed by forming a known light emitting material or host compound by a known thin film forming method such as a vacuum deposition method, a spin coating method, a casting method, an LB method, or an ink jet method. Can do.

The structure of the light-emitting layer preferably contains a host compound (also referred to as a light-emitting host) and a light-emitting material (also referred to as a light-emitting dopant), and emits light from the light-emitting material. Examples of applicable light emitting materials include International Publication No. 2005/076380, International Publication No. 2010/032663, International Publication No. 2008/140115, International Publication No. 2007/052431, International Publication No. 2011/134013, International Publication No. 2011/157339, International Publication No. 2010/086089, International Publication No. 2009/113646, International Publication No. 2012/020327, International Publication No. 20111051404, International Publication No. 2011/004639, International Publication No. 2011073149. And JP-A-2012-069737, JP-A-2009-114086, JP-A-2003-81988, JP-A-2002-302671, JP-A-2002-363552, and the like. it can

Examples of the host compound include, for example, Japanese Patent Application Laid-Open Nos. 2001-257076, 2002-308855, 2001-313179, 2002-319491, 2001-357777, JP 2002-334786, JP 2002-8860, JP 2002-334787, JP 2002-15871, 2002-334788, 2002-43056, 2002 -334789, JP 2002-75645, JP 2002-338579, JP 2002-105445, JP 2002-343568, JP 2002-141173, JP 2002-352957. No. 2002-203683 JP, JP 2002-363227, JP 2002-231453, JP 2003-3165, JP 2002-234888, JP 2003-27048, JP 2002-255934, JP 2002-260861, JP 2002-280183, JP 2002-299060, JP 2002-302516, JP 2002-305083, JP 2002-305084, JP 2002-308837, U.S. Patent Publication No. 2003/0175553, U.S. Patent Publication No. 2006/0280965, U.S. Patent Publication No. 2005/0112407, U.S. Patent Publication No. 2009/0017330, US Patent Publication No. 2009/003 202, U.S. Patent Publication No. 2005/238919, International Publication No. WO2001039234, International Publication No. 2009/021126, International Publication No. 2008/056746, International Publication No. 2004/093207, International Publication No. 2005. No. 089025, International Publication No. 2007/063796, International Publication No. 2007/063754, International Publication No. 2004/107822, International Publication No. 2005/030900, International Publication No. 2006/114966, International Publication No. 2009/086028. No., International Publication No. 2009/003898, International Publication No. 2012/023947, Japanese Unexamined Patent Application Publication No. 2008-074939, Japanese Unexamined Patent Application Publication No. 2007-254297, EP No. 2034538, and the like. Can The

[Hole injection layer / electron injection layer]
The injection layer is a layer provided between the electrode and the light emitting layer in order to lower the driving voltage and improve the light emission luminance. “The organic EL element and its industrialization front line (issued by NTS, November 30, 1998) The details are described in Part 2, Chapter 2, “Electrode Materials” (pages 123 to 166) of the second edition. In the organic EL element, the injection layer includes a hole injection layer and an electron injection layer.

The injection layer is a layer that can be provided as necessary. In the case of a hole injection layer, it is disposed between the anode and the light emitting layer or the hole transport layer, and in the case of an electron injection layer, it is disposed between the cathode and the light emitting layer or the electron transport layer.

The details of the hole injection layer are described in JP-A-9-45479, JP-A-9-260062, JP-A-8-288069 and the like. As a specific example, a phthalocyanine layer represented by copper phthalocyanine And an oxide layer typified by vanadium oxide, an amorphous carbon layer, and a polymer layer using a conductive polymer such as polyaniline (emeraldine) or polythiophene. In addition, the materials described in JP-T-2003-519432 can be used.

The details of the electron injection layer are described in JP-A-6-325871, JP-A-9-17574, JP1074586, and the like. Specifically, a metal layer typified by strontium, aluminum, etc. Examples thereof include an alkali metal halide layer typified by potassium fluoride, an alkaline earth metal compound layer typified by magnesium fluoride, and an oxide layer typified by molybdenum oxide. The electron injection layer is preferably a very thin film, and the film thickness is preferably in the range of 1 nm to 10 μm although it depends on the material.

[Hole transport layer]
The hole transport layer is made of a hole transport material having a function of transporting holes, and in a broad sense, a hole injection layer and an electron blocking layer are also included in the hole transport layer. The hole transport layer can be provided as a single layer or a plurality of layers. The hole transport material has any of the characteristics of hole injection or transport and electron barrier properties.

The hole transport material may be either organic or inorganic. For example, triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives and pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, Examples thereof include stilbene derivatives, silazane derivatives, aniline copolymers, conductive polymer oligomers, and thiophene oligomers. Furthermore, porphyrin compounds, aromatic tertiary amine compounds and styrylamine compounds, and aromatic tertiary amine compounds can be used.

Representative examples of aromatic tertiary amine compounds and styrylamine compounds include, for example, N, N, N ′, N′-tetraphenyl-4,4′-diaminophenyl, N, N′-diphenyl-N, N '-Bis (3-methylphenyl)-[1,1'-biphenyl] -4,4'-diamine (abbreviation: TPD), 2,2-bis (4-di-p-tolylaminophenyl) propane, , 1-bis (4-di-p-tolylaminophenyl) cyclohexane, N, N, N ′, N′-tetra-p-tolyl-4,4′-diaminobiphenyl, 1,1-bis (4-di -P-tolylaminophenyl) -4-phenylcyclohexane, bis (4-dimethylamino-2-methylphenyl) phenylmethane, bis (4-di-p-tolylaminophenyl) phenylmethane, N, N'-diphe Lu-N, N'-di (4-methoxyphenyl) -4,4'-diaminobiphenyl, N, N, N ', N'-tetraphenyl-4,4'-diaminodiphenyl ether, 4,4'-bis (Diphenylamino) quadriphenyl, N, N, N-tri (p-tolyl) amine, 4- (di-p-tolylamino) -4 '-[4- (di-p-tolylamino) styryl] stilbene, 4 -N, N-diphenylamino- (2-diphenylvinyl) benzene, 3-methoxy-4'-N, N-diphenylaminostilbenzene, N-phenylcarbazole, and further described in US Pat. No. 5,061,569 For example, 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (abbreviation: NPD), 4,4 ', 4 "-tris [N- (3-methylphenyl) -N-phenylamino] trimethyl triamine units described in JP-A-4-308688 are linked in a starburst type. And phenylamine (abbreviation: MTDATA).

Furthermore, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used. In addition, inorganic compounds such as p-type-Si and p-type-SiC can also be used as the hole injection material and the hole transport material. JP-A-11-251067, J. Org. Huang et. al. , Applied Physics Letters, 80 (2002), p. A so-called p-type hole transport material as described in 139 can also be used. These materials are preferably used because a light emitting element with higher efficiency can be obtained.

The hole transport layer is formed by forming a thin film from the hole transport material by using a known method such as a vacuum deposition method, a spin coating method, a casting method, a printing method including an ink jet method, or an LB method. Can be produced. The thickness of the hole transport layer is not particularly limited, but is usually about 5 nm to 5 μm, preferably 5 to 200 nm. The hole transport layer may have a single layer structure composed of one or more of the above materials.

Also, the hole transport layer material can be doped with impurities to increase transportability. Examples thereof include JP-A-4-297076, JP-A-2000-196140, JP-A-2001-102175, J. Pat. Appl. Phys. , 95, 5773 (2004), etc. can be applied.

[Electron transport layer]
The electron transport layer is made of a material having a function of transporting electrons, and in a broad sense, an electron injection layer and a hole blocking layer are also included in the electron transport layer. The electron transport layer can be provided as a single-layer structure or a multi-layer structure.

In the electron transport layer having a single-layer structure and the electron transport layer having a multilayer structure, an electron transport material (also serving as a hole blocking material) constituting a portion adjacent to the light-emitting layer is formed by using electrons injected from the cathode as the light-emitting layer. It suffices to have a function of transmitting to the network. As such a material, any one of conventionally known compounds can be selected and used. Examples include nitro-substituted fluorene derivatives, diphenylquinone derivatives, thiopyran dioxide derivatives, carbodiimides, fluorenylidenemethane derivatives, anthraquinodimethane, anthrone derivatives, and oxadiazole derivatives. Furthermore, in the above oxadiazole derivative, a thiadiazole derivative in which the oxygen atom of the oxadiazole ring is substituted with a sulfur atom, and a quinoxaline derivative having a quinoxaline ring known as an electron-withdrawing group can also be used as a material for the electron transport layer. it can. Furthermore, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used.

In addition, metal complexes of 8-quinolinol derivatives such as tris (8-quinolinol) aluminum (abbreviation: Alq3), tris (5,7-dichloro-8-quinolinol) aluminum, tris (5,7-dibromo-8-quinolinol) ) Aluminum, tris (2-methyl-8-quinolinol) aluminum, tris (5-methyl-8-quinolinol) aluminum, bis (8-quinolinol) zinc (abbreviation: Znq), etc., and the central metal of these metal complexes A metal complex in which In, Mg, Cu, Ca, Sn, Ga, or Pb is replaced can also be used as the material for the electron transport layer.

In addition, metal-free or metal phthalocyanine, or those whose terminal is substituted with an alkyl group or a sulfonic acid group can be preferably used as the material for the electron transport layer. Further, distyrylpyrazine derivatives exemplified as the material for the light emitting layer can also be used as the material for the electron transport layer, and n-type-Si, n-type-SiC, etc. as well as the hole injection layer and the hole transport layer. These inorganic semiconductors can also be used as a material for the electron transport layer.

The electron transport layer can be prepared by forming a thin film using the above-described material by a known method such as a vacuum deposition method, a spin coating method, a casting method, a printing method including an inkjet method, or an LB method. it can. The thickness of the electron transport layer is not particularly limited, but is usually about 5 nm to 5 μm, preferably 5 to 200 nm. The electron transport layer may have a single layer structure composed of one or more of the above materials.

Also, the electron transport layer can be doped with impurities to increase transportability. Examples thereof include JP-A-4-297076, JP-A-10-270172, JP-A-2000-196140, JP-A-2001-102175, J. Pat. Appl. Phys. 95, 5773 (2004), and the like. Further, the electron transport layer preferably contains potassium, a potassium compound, or the like. As the potassium compound, for example, potassium fluoride can be used. Thus, when the n property of the electron transport layer is increased, an element with lower power consumption can be manufactured.

Further, as the material for the electron transport layer (electron transport compound), the same material as that for the above-described underlayer may be used. This is the same for the electron transport layer that also serves as the electron injection layer, and the same material as that for the above-described underlayer may be used.

[Electron blocking layer / hole blocking layer]
Examples of the hole blocking layer include, for example, Japanese Patent Application Laid-Open No. 11-204258, Japanese Patent Application Laid-Open No. 11-204359, and “The Forefront of Organic EL Devices and Their Industrialization (issued by NTT Corporation on November 30, 1998). ”Page 237 and the like, there is a hole blocking (hole blocking) layer.

The hole blocking layer has a function of an electron transport layer in a broad sense. The hole blocking layer is made of a hole blocking material that has a function of transporting electrons but has a very small ability to transport holes, and recombines electrons and holes by blocking holes while transporting electrons. Probability can be improved. Moreover, the structure of an electron carrying layer can be used as a hole-blocking layer as needed. The hole blocking layer is preferably provided adjacent to the light emitting layer.

On the other hand, the electron blocking layer has a function of a hole transport layer in a broad sense. The electron blocking layer is made of a material that has a function of transporting holes but has a very small ability to transport electrons, and improves the probability of recombination of electrons and holes by blocking electrons while transporting holes. be able to. Moreover, the structure of a positive hole transport layer can be used as an electron blocking layer as needed. The thickness of the hole blocking layer or electron blocking layer is preferably in the range of 3 to 100 nm, more preferably in the range of 5 to 30 nm.

[Method of manufacturing organic EL element]
Next, a method for manufacturing the organic EL element having the above configuration will be described. In the following description, an example of a method for manufacturing the organic EL element having the configuration shown in FIG. 4 will be described.

(Lamination process)
In the manufacture of the organic EL element, the transparent electrode 11, the first light emitting unit 12, the first intermediate electrode 13, the second light emitting unit 14, and the reflective electrode 17 are formed in this order on the support substrate. In addition, before the transparent electrode 11 and the first intermediate electrode 13 are formed, a base layer is formed as necessary.

In the film formation of each of these members, a film formation method suitable for each member may be applied. Examples of film formation methods include vacuum deposition, sputtering, reactive sputtering, molecular beam epitaxy, cluster ion beam, ion plating, plasma polymerization, atmospheric pressure plasma polymerization, plasma CVD, and laser. Examples thereof include a CVD method, a thermal CVD method, and a coating method.

In film formation of each member, each member can be patterned into a predetermined shape by performing film formation using a mask as necessary. Each member may be patterned into a predetermined shape after each layer is formed. In addition, before and after the formation of the transparent electrode 11 and the first intermediate electrode 13, an auxiliary electrode pattern may be formed as necessary. The laminating step is preferably performed by a procedure of forming a film from the transparent electrode 11 to the reflective electrode 17 consistently by a single vacuum drawing.

(Sealing process)
Next, although not shown, sealing is performed from the reflective electrode 17 side. Here, the transparent electrode 11, the first intermediate electrode 13, and the terminal portions of the reflective electrode 17 are exposed so that the laminate from the transparent electrode 11 to the reflective electrode 17 is covered with the support substrate. A stop material is provided, and a protective member is further bonded through a sealing material as necessary.

<3. Embodiment of Light Emitting Device>
Next, an embodiment of a light emitting device using the above-described organic EL element will be described.

[Light emitting device]
The organic EL element described above can be used as a planar light emitting device. The light emitting device can increase the light emitting surface area by using a plurality of organic EL elements. In this case, the light emitting surface is enlarged by arranging (that is, tiling) a plurality of organic EL elements on the substrate of the light emitting device. The substrate of the light emitting device may also serve as a sealing material, and the organic EL device is sandwiched between the transparent electrode 11 and the reflective electrode 17 between the substrate of the light emitting device and the support substrate of the organic EL element. Tile the element. An adhesive may be filled between the base of the light emitting device and the support substrate of the organic EL element, thereby sealing the transparent electrode 11 to the reflective electrode 17 of the organic EL element. A terminal connected to each electrode of the organic EL element is exposed around the base of the light emitting device.

In the light-emitting device having such a configuration, a large-area light-emitting region obtained by connecting light-emitting regions formed in a plurality of organic EL elements can be displayed in a pattern. In such a configuration, a non-light emitting region is generated at the joint of each organic EL element. For this reason, you may provide the light extraction member for increasing the amount of light extraction especially in the non-light-emission area | region used as the connection of a light emission area | region between organic EL elements. As the light extraction member, a light collecting sheet or a light diffusion sheet can be used.

The present invention will be specifically described by way of examples, but the present invention is not limited thereto. In addition, although the display of "%" is used in an Example, unless otherwise indicated, "mass%" is represented.

<Preparation of Sample 101 Organic EL Element>
As Sample 101, an organic EL element having the configuration shown in FIG. As Sample 101, an organic EL element having an element area of 1 cm × 1 cm was produced as follows.

[Formation of transparent electrode]
First, a glass substrate having a thickness of 0.7 mm was prepared as a support substrate. This support substrate was subjected to ultrasonic cleaning with isopropyl alcohol, dried with dry nitrogen gas, and UV ozone cleaning was performed for 5 minutes. Then, Ag (silver) was mask-deposited with a thickness of 15 nm on this support substrate to form a transparent electrode serving as an anode.

[Formation of first light emitting unit: EMU1]
Next, the support substrate on which the transparent electrode was formed was fixed to a substrate holder of a commercially available vacuum deposition apparatus. And the material of each layer which comprises a 1st light emission unit (EMU1) was filled with the optimal quantity for element manufacture to each crucible for vapor deposition in a vacuum evaporation system. As each evaporation crucible, an evaporation crucible made of a resistance heating material made of molybdenum or tungsten was used.

(Formation of hole injection layer)
After reducing the vacuum to 1 × 10 ⁴ Pa, energize and heat the evaporation crucible containing HAT-CN (hexaazatriphenylenehexacarbonitrile), and deposit on the transparent electrode at a deposition rate of 0.1 nm / second. A 5 nm thick hole injection layer was formed.

(Hole transport layer: formation of HTL1)
Next, the following compound 1-A (glass transition point (Tg) = 140 ° C.) was deposited to a thickness of 27 nm to form a hole transport layer (HTL1).

(Formation of electron blocking layer)
Next, the following compound 1-B was deposited on the hole transport layer (HTL1) so as to have a thickness of 10 nm to form an electron blocking layer.

(Light emitting layer: formation of EMT1)
Next, the following compound 2-A (Tg = 189 ° C.) is deposited as 98 vol% as a host compound, and the following compound 2-B is deposited as 2 vol% as a blue fluorescent light-emitting dopant. A layer (EMT1) was formed.

(Electron transport layer: formation of ETL1)
Next, it vapor-deposited on the light emitting layer so that the following compound 3 might be 86 vol%, and LiF might be 14 vol%, and the layer of thickness 10nm was formed. Furthermore, it vapor-deposited so that the compound 3 might be 98 vol% and Li might be 2 vol%, and the layer of thickness 12nm was formed. As a result, an electron transport layer (ETL1) also serving as an electron injection layer composed of two layers of the compound 3 and LiF and the compound 3 and Li is formed, and the first stacked structure from the hole injection layer to the electron transport layer is formed. A light emitting unit (EMU1) was formed.

[Formation of first intermediate electrode]
Next, Al was formed into a film with a thickness of 10 nm on the first light emitting unit (EMU1) to form a first intermediate electrode.

[Formation of second light emitting unit: EMU2]
Except for the light emitting layer, the film thickness was set to the following thickness in the same procedure using the same material as the first light emitting unit (EMU1), and the second light emitting unit (EMU2) was formed on the first intermediate electrode. Formed.

(Formation of hole injection layer)
HAT-CN was deposited to a thickness of 5 nm to form a hole injection layer.

(Hole transport layer: formation of HTL2)
Next, Compound 1-A was deposited to a thickness of 55 nm to form a hole transport layer (HTL2).

(Formation of electron blocking layer)
Next, Compound 1-B was deposited to a thickness of 10 nm to form an electron blocking layer.

(Light emitting layer: formation of EMT2)
Next, the following compound 4-A (Tg = 143 ° C.) is 80 vol% as the host compound, the compound (Ir (ppy) 3) is 10 vol% as the green phosphorescent dopant, and the compound (btp2Ir ( The acac)) was vapor-deposited so that it might become 10 vol%, and the 25-nm-thick phosphorescence-emitting layer (EMT2) which exhibits red light emission was formed.

(Electron transporting layer: formation of ETL2)
Next, it vapor-deposited on the light emitting layer so that the compound 3 might be 86 vol% and LiF might be 14 vol%, and the 15-nm-thick layer was formed. Furthermore, it vapor-deposited so that the compound 3 might be 98 vol% and Li might be 2 vol%, and the layer of thickness 10nm was formed. As a result, an electron transport layer (ETL2) that also serves as an electron injection layer composed of two layers of the compound 3 and LiF and the compound 3 and Li is formed, and the second layered structure from the hole injection layer to the electron transport layer is formed. A light emitting unit (EMU2) was formed.

[Formation of second intermediate electrode]
Next, Al was deposited to a thickness of 10 nm on the second light emitting unit (EMU2) to form a second intermediate electrode.

[Formation of third light emitting unit: EMU3]
Except for the light emitting layer, the film thickness was set to the following thickness in the same procedure using the same material as the first light emitting unit (EMU1) and the second light emitting unit (EMU2), and the second intermediate electrode was A third light emitting unit (EMU3) was formed.

(Hole transport layer: formation of HTL3)
Next, Compound 1-A was deposited to a thickness of 40 nm to form a hole transport layer (HTL3).

(Light emitting layer: formation of EMT3)
Next, the following compound 4-A (Tg = 143 ° C.) as a host compound is vapor-deposited so that 85 vol% and the compound (Ir (ppy) 3) as a green phosphorescent light emitting dopant is 15 vol%, and a thickness exhibiting green light emission is obtained. A phosphorescent layer (EMT3) having a thickness of 25 nm was formed.

(Electron transporting layer: formation of ETL3)
Next, it vapor-deposited on the light emitting layer so that the compound 3 might be 86 vol% and LiF might be 14 vol%, and the 20-nm-thick layer was formed. Furthermore, it vapor-deposited so that the compound 3 might be 98 vol% and Li might be 2 vol%, and the 22-nm-thick layer was formed. As a result, an electron transport layer (ETL3) that also serves as an electron injection layer composed of two layers of the compound 3 and LiF and the compound 3 and Li is formed, and the third layered structure from the hole injection layer to the electron transport layer is formed. A light emitting unit (EMU3) was formed.

[Formation of reflective electrode]
Next, on the third light emitting unit (EMU3), Al was evaporated to a thickness of 150 nm to form a reflective electrode serving as a cathode.

[Sealing and power connection]
Next, the laminated body formed from the transparent electrode to the reflective electrode is covered with a glass case from the reflective electrode side, and a sealant with an epoxy-based photocurable adhesive (Luxtrac LC0629B manufactured by Toagosei Co., Ltd.) is applied to the periphery of the glass case. Provided. The glass case and the support substrate were brought into close contact with each other through this sealing agent. Then, the laminated body from a transparent electrode to a reflective electrode was sealed by irradiating UV light from the glass case side, and the sealing agent was hardened, and the organic EL element of the sample 101 was produced. However, the terminal of each electrode was made into the state pulled out from the glass case, and the power supply was connected to these electrodes. The glass case is sealed with a glove box in a nitrogen atmosphere (in an atmosphere of high-purity nitrogen gas having a purity of 99.999% or more) without bringing the laminate from the transparent electrode to the reflective electrode into contact with the atmosphere. went.

<Preparation of organic EL elements of samples 102 to 107>
In the method for manufacturing the organic EL element of Sample 101 described above, the light emitting material, the thickness of the hole transport layer (HTL1, HTL2, HTL3), and the thickness of the electron transport layer (ETL1, ETL2, ETL3) are shown in the following table. The organic EL elements of Samples 102 to 107 were produced in the same manner as Sample 101, except for the changes shown in 1. Samples 105 to 107 have only the first light emitting unit (EMU1) and the second light emitting unit (EMU2) shown in FIG. 4 described above.

<Evaluation>
[Luminescent peak wavelength and half-value width]
In the organic EL elements of Samples 101 to 107, the peak wavelength and the half value width of the emission spectrum when each light emitting unit (EMU1 to EMU3) was caused to emit light individually were measured. The emission spectrum of each light emitting unit was measured using a CS-2000 luminance meter manufactured by Konica Minolta under an application condition of 5 mA / cm ² . Specifically, four or more extraction electrode portions are provided for each light emitting unit (EMU1 to EMU3) of the organic EL element, and current is applied under the above conditions from each extraction electrode portion to the electrode pair sandwiching the light emitting unit. Thus, emission spectra of the respective light emitting units (EMU1 to EMU3) were obtained. In the emission spectrum of each of the obtained light emitting units (EMU1 to EMU3), the wavelength that gives the maximum light emission intensity was taken as the peak wavelength. Further, a numerical value was obtained by setting the wavelength difference between the minimum wavelength and the maximum wavelength, which is half the intensity from the emission intensity of the peak wavelength, as a half width (full width at half maximum: FWHM).
Table 1 shows the measured peak wavelength and full width at half maximum for the light emitting units (EMU1 to EMU3) of each sample. Further, FIG. 5 shows an emission spectrum when each light emitting unit (EMU1 to EMU3) emits light individually in the organic EL element of the sample 101.

[Brightness fluctuation / chromaticity fluctuation]
From the measured peak wavelength and half width, in the organic EL elements of Samples 101 to 107, among the light emitting units (EMU1 to 3), the light emitting unit (EMUNo.) Having the peak wavelength closest to 555 nm was obtained. Furthermore, the luminance variation and the chromaticity variation (the sum of squares of x and y) were obtained for the light emitting unit whose peak wavelength was closest to 555 nm. As for the luminance variation and chromaticity variation (the sum of squares of x and y), 50 panels of organic EL elements were produced by the above-described manufacturing method, and the standard deviation σ was obtained from the variation in the 50 panels. Note that the standard deviation σ of the luminance fluctuation and chromaticity fluctuation (the sum of squares of x and y) of the samples 101 to 107 was obtained as a relative value based on the standard deviation σ of the sample 107.

The result (relative value) of the standard deviation σ of the emission peak wavelength, the half width, the light emitting unit (EMU No.) whose peak wavelength is closest to 555 nm, the luminance fluctuation, and the chromaticity fluctuation (the sum of squares of x and y), It is shown in Table 2 below.

As shown in Table 2, in the organic EL element of Sample 101, the peak wavelength of the third light emitting unit is closer to 555 nm than the peak wavelength of the first light emitting unit and the peak wavelength of the second light emitting unit. For this reason, the light emitting unit whose peak wavelength is closest to 555 nm is the third light emitting unit. And the half value width of the emission spectrum of the 3rd light emission unit whose peak wavelength is the closest to 555 nm is smaller than the half value width of the emission spectrum of the 1st light emission unit and the 2nd light emission unit. Therefore, the organic EL element of the sample 101 has a configuration in which the half width of the emission spectrum of the light emitting unit whose peak wavelength is closest to 555 nm is the smallest among all the light emitting units.

Similarly, the organic EL elements of Samples 102 to 106 have a configuration in which the half width of the emission spectrum of the light emitting unit having the peak wavelength closest to 555 nm is the smallest among all the light emitting units.

In the organic EL element of sample 107, the peak wavelength of the first light emitting unit is closer to 555 nm than the peak wavelength of the second light emitting unit. For this reason, the light emitting unit whose peak wavelength is closest to 555 nm is the first light emitting unit. However, in the organic EL element of the sample 107, the half width of the second light emitting unit is smaller than the half width of the first light emitting unit. Therefore, unlike the samples 101 to 106, the organic EL element of the sample 107 does not have the smallest half-width of the emission spectrum of the light emitting unit whose peak wavelength is closest to 555 nm among all the light emitting units.

As in the organic EL elements of Samples 101 to 106, in the configuration in which the half-value width of the emission spectrum of the light emitting unit whose peak wavelength is closest to 555 nm is the smallest among all the light emitting units, compared to the sample 107 that does not have this configuration. The standard deviation σ of luminance variation and chromaticity variation (the sum of squares of x and y) is small. That is, in the organic EL elements of Samples 101 to 106, luminance variations and color variations are suppressed to be smaller than those of Sample 107 even when variations occur in the thickness of each layer in manufacturing 50 panels.

In addition, the organic EL elements of the samples 104 to 106 in which the light emitting unit having the peak wavelength closest to 555 nm includes the fluorescent light emitting material as the light emitting material are compared with the organic EL elements of the samples 101 to 103 including the phosphorescent light emitting material as the light emitting material. , Luminance fluctuation and color fluctuation are small. In this way, by using a fluorescent material as the light emitting material, even when variations occur in the thickness of each layer during manufacturing, luminance variations and color variations are suppressed. Therefore, in a light emitting unit having a peak wavelength closest to 555 nm, it is preferable to use a fluorescent light emitting material as the light emitting material.

As described above, in the configuration in which the half width of the emission spectrum of the light emitting unit having a high specific visibility is smaller than the half width of the emission spectrum of the other light emitting units, even when thickness variation occurs during film formation, With respect to the light emitted from the organic EL element, it is possible to reduce the influence of the color shift and the luminance change of the light emitted from the light emitting unit having a high specific visibility. That is, the color shift and the luminance change of the light emitted from the light emitting unit having high specific visibility are not easily recognized even in the light emitted from the organic EL element. As a result, even in the film thickness fluctuation when forming each layer constituting the organic electroluminescence element, it becomes possible to suppress the fluctuation of the light emission performance, and to suppress the decrease in the productivity and the yield of the organic EL element. Can do.

The present invention is not limited to the configuration described in the above embodiment, and various modifications and changes can be made without departing from the configuration of the present invention.

DESCRIPTION OF SYMBOLS 11 ... Transparent electrode, 12 ... 1st light emission unit, 13 ... 1st intermediate electrode, 14 ... 2nd light emission unit, 15 ... 2nd intermediate electrode, 16 ... 3rd light emission Unit, 17 ... reflective electrode, 18, 19 ... power supply, 20 ... control unit

Claims

Provided with n light emitting units and n + 1 or more electrodes provided on the support substrate, from the support substrate side, transparent electrode, first light emitting unit ... nth electrode, nth light emitting unit, An organic electroluminescence device having n + 1 electrodes,
A light emitting unit having a peak wavelength of the emission spectrum closest to 555 nm is an organic electroluminescence device in which the half width of the emission spectrum is the smallest among all the light emitting units.
The organic electroluminescence device according to claim 1, wherein at least one of the intermediate electrodes provided between the first light emitting unit and the nth light emitting unit contains silver or aluminum as a main component.
The organic electroluminescence device according to claim 2, wherein the thickness of the intermediate electrode containing silver or aluminum as a main component is 6 nm or more and 25 nm or less.
The organic electroluminescence device according to claim 1, wherein the light emitting unit having a peak wavelength of the emission spectrum closest to 555 nm contains a fluorescent light emitting material.
A light emitting device comprising the organic electroluminescence element according to claim 1.