Organic light-emitting devices, display devices, in-vehicle displays, electronic devices and vehicles

Abstract

The present invention provides organic light-emitting devices, display devices, electronic devices, and in-vehicle displays with improved luminous efficiency, as well as vehicles using these in-vehicle displays. [Solution] Between the anode electrode 11 and cathode electrode 12, which are provided opposite each other, there is an interference reflection section 30 together with a light-emitting structure section 20 including a light-emitting layer 24. The interference reflection section 30 is formed in contact with the anode electrode 11 and includes a plurality of p-type low refractive index layers 31 having p-type conductivity and a low refractive index as a first charge generation layer having a first conductivity type and a first refractive index, and a plurality of n-type high refractive index layers 32 having n-type conductivity and a high refractive index as a second charge generation layer having a second conductivity type and a second refractive index. In the interference reflection section 30, the plurality of p-type low refractive index layers 31 and the plurality of n-type high refractive index layers 32 are alternately stacked.

Description

Technical Field

[0001] The present disclosure relates to an organic light-emitting device, a display device, an in-vehicle display, an electronic device, and a vehicle.

Background Art

[0002] As an organic light-emitting device using an organic light-emitting material, there is known one in which the light-emitting efficiency and monochromaticity are improved by the microcavity effect. In an organic light-emitting device 501 having the element structure shown in Fig. 30(A), a microcavity is formed by an anode electrode 511 and a cathode electrode 512 provided to face each other on a circuit board 510. When the anode electrode 511 is a reflective electrode using a metal electrode and the cathode electrode 512 is a semi-transparent electrode, the emission intensity depends on the distance DA between the anode electrode 511 and the center of the light-emitting layer 513, and the distance DB between the cathode electrode 512 and the center of the light-emitting layer 513. Zones Z01, Z02, Z03 shown in Fig. 30(B) represent zones where a high microcavity effect can be obtained depending on the distance DA and the distance DB based on optical simulation. Fig. 30(B) shows the optical simulation result when the main emission wavelength is 460 nm. When only the microcavity effect is considered, the highest first peak appears in zone Z01, and the next highest second peaks of the same degree appear in zones Z02 and Z03. On the other hand, in the experimental results shown in Fig. 31, the emission intensity has peaks that appear in zone Z01 indicated by curve CU11, peaks that appear in zone Z02 indicated by curve CU12, and peaks that appear in zone Z03 indicated by curve CU13.

[0003] The peak of the emission intensity indicated by curve CU12 is higher than the peak of the emission intensity indicated by curve CU11 shown in Fig. 31. The peak of the emission intensity indicated by curve CU13 is higher than the peak of the emission intensity indicated by curve CU12. Therefore, the simulation result considering only the microcavity effect does not match the experimental result.

[0004] In the organic light-emitting device 501, when the anode electrode 511 is constructed using a metal electrode containing silver (Ag) or the like as the reflective electrode, it is necessary to consider optical loss known as surface plasmon loss. When an optical simulation considering optical loss along with the microcavity effect is performed on the results shown in Figure 30(B), the peak of emission intensity appearing in zone Z03 is higher than the peak of emission intensity appearing in zone Z02. Also, the peak of emission intensity appearing in zone Z02 is higher than the peak of emission intensity appearing in zone Z01. In this case, the optical simulation results are consistent with the experimental results in Figure 31.

[0005] Surface plasmons are waves of electrons vibrating on the surface of a conductor. In an organic light-emitting device 501 that includes an anode electrode 511 using a metal electrode, light emission from radiant dipoles produced by molecular excitons in the light-emitting layer is coupled to the electron vibrations of the reflective electrode, causing optical loss. External quantum efficiency obtained by optical simulation is calculated by multiplying carrier balance, exciton generation rate, radiant quantum efficiency, and light extraction efficiency. By incorporating a parcel factor into the radiant quantum efficiency, it becomes possible to perform calculations that take optical loss into account.

[0006] Top-emission type organic light-emitting diode (OLED) displays using an organic light-emitting device 501 that extracts light from the cathode electrode 512 side suppress light loss by increasing the distance DA from the anode electrode 511 to the center of the light-emitting layer 513. Furthermore, to increase brightness and extend lifespan, a tandem structure is used in which multiple light-emitting layers, such as the two light-emitting layers 513A and 513B shown in Figure 32, are provided between the opposing anode electrode 511 and cathode electrode 512. However, if the tandem structure has the same overall film thickness as the single structure, the distance between the lower light-emitting layer 513A and the reflective anode electrode 511 becomes shorter. Therefore, when the emission color is green or blue, the luminous efficiency of the tandem structure does not reach twice that of the single structure. Thus, improving luminous efficiency by replacing the reflective electrode using the anode electrode 511 is being considered.

[0007] Patent Document 1 discloses a dielectric mirror that acts as an optical resonator that enhances light having a specific wavelength. Patent Document 2 discloses a light-emitting device having a low refractive index layer containing an organic compound along with a light-emitting layer. Patent Document 3 discloses an optical member in which high refractive index layers and low refractive index layers are alternately and repeatedly laminated. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2007-317591 [Patent Document 2] Japanese Patent Publication No. 2023-4940 [Patent Document 3] U.S. Patent Application Publication No. 2015 / 0041768 [Overview of the project] [Problems that the invention aims to solve]

[0009] The technologies described in Patent Documents 1 and 3 involve providing a reflective structure beneath the transparent anode electrode, which may affect display characteristics due to the relatively high sheet resistance of the transparent conductive film. Furthermore, if the film thickness is increased to reduce the resistance of the transparent conductive film electrode, absorption at short wavelengths increases, potentially reducing the efficiency of blue light emission. The technology described in Patent Document 2 aims to improve monochromaticity by utilizing interference, but increasing reflectivity requires stacking multiple charge transport layers, which may increase the driving voltage or make it difficult to adjust the carrier balance due to carrier deficiency.

[0010] This disclosure is made in view of the above circumstances and aims to provide an organic light-emitting device, display device, in-vehicle display and electronic device with improved luminous efficiency, and a vehicle using the in-vehicle display. [Means for solving the problem]

[0011] To achieve the above objective, an organic light-emitting apparatus according to a first embodiment of the present disclosure comprises a first electrode and a second electrode provided opposite to each other, and an organic compound layer provided between the first electrode and the second electrode, having at least a light-emitting layer and an interference reflective portion, wherein the interference reflective portion is formed by alternately stacking a plurality of first charge-generating layers having a first conductivity type and a first refractive index, and a plurality of second charge-generating layers having a second conductivity type and a second refractive index, and is in contact with either the first electrode or the second electrode.

[0012] A display device according to a second embodiment of the present disclosure comprises an organic light-emitting device according to a first embodiment.

[0013] An in-vehicle display according to a third embodiment of this disclosure comprises a display device according to a second embodiment.

[0014] The electronic device according to the fourth embodiment of this disclosure comprises a display device according to the second embodiment.

[0015] The vehicle according to the fifth embodiment of the present disclosure includes the in-vehicle display according to the third embodiment.

Advantages of the Invention

[0016] According to the present disclosure, it is possible to provide an organic light-emitting device, a display device, an in-vehicle display, and an electronic device with improved luminous efficiency, and a vehicle using the in-vehicle display.

Brief Description of the Drawings

[0017] [Figure 1] It is a schematic diagram showing a first configuration example of an organic light-emitting device according to the first embodiment. [Figure 2] It is a curve graph showing an example of simulation of reflectance. [Figure 3] It is a curve graph showing an example of simulation of reflectance. [Figure 4] It is a curve graph showing an example of simulation of reflectance. [Figure 5] It is a cross-sectional view of a light-emitting device and a driving TFT. [Figure 6] (A) It is a circuit diagram of a first pixel circuit, (B) It is a circuit diagram of a second pixel circuit. [Figure 7] It is a bar graph for comparing light loss and luminous efficiency. [Figure 8] (A) When a polarizing plate is formed, (B) When a color filter is formed, it is a schematic diagram showing a configuration example of a light extraction layer in each case. [Figure 9] It is a schematic diagram showing a configuration example of a microlens array. [Figure 10] It is a bar graph for comparing the ratio of losses. [Figure 11] It is a curve graph for comparing the current-voltage characteristics of an organic material layer. [Figure 12] It is a diagram showing the energy states of each layer constituting an organic light-emitting device. [Figure 13] It is a line graph showing the relationship between the driving voltage and the concentration of an n-type dopant material. [Figure 14]This is a line graph showing the relationship between the driving voltage and the concentration of the p-type dopant material. [Figure 15] This is a schematic diagram showing a second configuration example of an organic light-emitting device according to the first embodiment. [Figure 16] This is a schematic diagram showing a third configuration example of an organic light-emitting device according to the first embodiment. [Figure 17] This is a bar graph used to compare the percentage of losses. [Figure 18] (A) A diagram showing a structural comparison example of the prior art, and (B) A diagram showing a structural comparison example of the embodiment of the present disclosure. [Figure 19] (A) A diagram showing an example of sub-pixel configuration corresponding to the publicly known technology, and (B) A diagram showing an example of sub-pixel configuration corresponding to the embodiment of the present disclosure. [Figure 20] This is a schematic diagram showing an example of the configuration of an organic light-emitting device according to the second embodiment. [Figure 21] This is a schematic diagram showing an example of the configuration of an organic light-emitting device according to the third embodiment. [Figure 22] This is a curve graph showing reflectance and other properties in organic light-emitting devices. [Figure 23] This is a bar graph used to compare the percentage of losses. [Figure 24] This is a cross-sectional view of the light-emitting device and the driving TFT. [Figure 25] This is a schematic diagram showing an example of the configuration of a display device according to the fourth embodiment. [Figure 26] This is a plan view showing a portion of the display area of ​​a display device. [Figure 27] This is a schematic diagram showing an example configuration of an in-vehicle display according to the fifth embodiment and a vehicle equipped with this in-vehicle display. [Figure 28] This is a perspective view showing an example configuration of a smartphone as an electronic device according to the sixth embodiment. [Figure 29] (A) Cross-sectional view of the first sealing structure, (B) Cross-sectional view of the second sealing structure, (C) Cross-sectional view of the third sealing structure. [Figure 30](A) A schematic diagram showing an example of the configuration of an organic light-emitting device in the prior art, and (B) A diagram showing the light emission intensity obtained from an optical simulation of the prior art. [Figure 31] This is a curve graph showing the luminescence intensity based on experimental results of conventional technology. [Figure 32] This is a schematic diagram showing an example of a tandem structure configuration in conventional technology. [Modes for carrying out the invention]

[0018] (First Embodiment) Figure 1 is a schematic diagram showing a first configuration example of the organic light-emitting device 1 according to this embodiment. The organic light-emitting device 1 is configured as a type of top-emission OLED. The organic light-emitting device 1 comprises an anode electrode 11 and a cathode electrode 12 provided opposite each other on a circuit board 10. The organic light-emitting device 1 comprises a light-emitting structure 20 and an interference reflection section 30 provided between the anode electrode 11 and the cathode electrode 12. In addition, the organic light-emitting device 1 comprises a capping layer 13 on the cathode electrode 12. The laminate made of an organic compound sandwiched between the anode electrode 11 and the cathode electrode 12 is also referred to as an organic compound layer or an organic material layer. This disclosure is not limited to the materials contained in each layer.

[0019] The circuit board 10 is a rigid or flexible substrate on which, for example, the pixel circuit PX01 shown in Figure 6(A) or the pixel circuit PX02 shown in Figure 6(B) is formed. The circuit board 10 includes a thin-film transistor (TFT) array. The organic light-emitting device 1 has a laminated structure on the circuit board 10. In Figure 1, the side closer to the circuit board 10 is referred to as the lower side, and the side further from the circuit board 10 is referred to as the upper side.

[0020] The anode electrode 11 is the lower electrode, serving as the first electrode in the organic light-emitting device 1, and is connected to a power supply (not shown). The anode electrode 11 can be formed using any material that is transparent and conductive. For example, indium tin oxide (ITO), tin oxide (SnO2), indium zinc oxide (IZO), etc., can be used as the material for the anode electrode 11. In the organic light-emitting device 1 according to this embodiment, metallic reflection by the anode electrode 11 is not necessary. However, if the reflection characteristics of the interference reflection section 30 are sufficient, a conventional metal electrode can be used for the anode electrode 11.

[0021] The cathode electrode 12 is the upper electrode serving as the second electrode in the organic light-emitting device 1 and is connected to a power supply (not shown). The cathode electrode 12 can be formed using a material that is semi-transparent and semi-reflective. For example, aluminum, magnesium-silver alloy, ITO, IZO, etc. can be used as the material for the cathode electrode 12.

[0022] The light-emitting structure 20 is formed by including, in order from bottom to top, a hole injection layer 21, a hole transport layer 22, an electron blocking layer 23, a light-emitting layer 24, a hole blocking layer 25, an electron transport layer 26, and an electron injection layer 27. The light-emitting structure 20 can utilize the structure and materials of conventional OLED elements, or new structures and materials that are applicable to OLED elements. Note that all or part of the hole injection layer 21, hole transport layer 22, electron blocking layer 23, hole blocking layer 25, electron transport layer 26, and electron injection layer 27 do not need to be included in the light-emitting structure 20. Therefore, the light-emitting structure 20 only needs to include at least a light-emitting layer 24.

[0023] The hole injection layer 21 facilitates hole injection by lowering the hole injection barrier from the anode electrode 11. In the hole injection layer 21, the energy level of the highest occupied molecular orbital (HOMO), referred to as the HOMO level, is lower than the work function of the anode electrode 11 and higher than the HOMO level of the hole transport layer 22. Therefore, the hole injection layer 21 has an HOMO level between the work function of the anode electrode 11 and the HOMO level of the hole transport layer 22.

[0024] The hole transport layer 22 facilitates the transport of holes to the light-emitting layer 24. Generally, the hole transport layer 22 has a larger energy band gap than the light-emitting layer 24. The energy band gap is the energy difference between the energy level of the lowest unoccupied molecular orbital (LUMO), also known as the LUMO level, and the HOMO level.

[0025] The electron blocking layer 23 has the effect of preventing electron movement. The electron blocking layer 23 suppresses hole accumulation at the interface between the hole transport layer 22 and the electron blocking layer 23, and at the interface between the electron blocking layer 23 and the light-emitting layer 24.

[0026] The light-emitting layer 24 emits light through the recombination of holes and electrons. Holes are injected into the light-emitting layer 24 from the anode electrode 11. Electrons are injected into the light-emitting layer 24 from the cathode electrode 12. The light-emitting layer 24 can be formed using any organic light-emitting material, such as a fluorescent material, a thermally activated delayed fluorescence material, a phosphorescent material, or other suitable organic light-emitting material.

[0027] The hole-blocking layer 25 has the effect of preventing the movement of holes. The hole-blocking layer 25 suppresses the accumulation of electrons at the interface between the light-emitting layer 24 and the hole-blocking layer 25, and at the interface between the hole-blocking layer 25 and the electron-transport layer 26.

[0028] The electron transport layer 26 has the effect of promoting the transport of electrons to the light-emitting layer 24. Similar to the hole transport layer 22, it is preferable that the electron transport layer 26 has a larger energy band gap than the light-emitting layer 24. In addition, the electron transport layer 26 may have the effect of preventing the movement of excitons generated in the light-emitting layer 24.

[0029] The electron injection layer 27 facilitates electron injection by lowering the electron injection barrier from the cathode electrode 12. In the electron injection layer 27, the LUMO level is higher than the work function of the cathode electrode 12 and lower than the LUMO level of the electron transport layer 26. Therefore, the electron injection layer 27 has a LUMO level between the work function of the cathode electrode 12 and the LUMO level of the electron transport layer 26.

[0030] Thus, the light-emitting structure 20 is composed of a hole injection layer 21, a hole transport layer 22, an electron injection layer 27, and an electron transport layer 26 between the anode electrode 11 and the cathode electrode 12. The interference reflection section 30 is provided separately from the light-emitting structure 20 between the anode electrode 11 and the cathode electrode 12. Therefore, the interference reflection section 30 is formed at a different position from the hole injection layer 21, the hole transport layer 22, the electron injection layer 27, and the electron transport layer 26. In the organic light-emitting device 1 shown in Figure 1, the interference reflection section 30 is formed in contact with the hole injection layer 21.

[0031] The interference reflection section 30 includes a plurality of p-type low refractive index layers 31 having p-type conductivity and a low refractive index as a first charge generation layer having a first conductivity type and a first refractive index. The interference reflection section 30 includes a plurality of n-type high refractive index layers 32 having n-type conductivity and a high refractive index as a second charge generation layer having a second conductivity type and a second refractive index. In the interference reflection section 30, the plurality of p-type low refractive index layers 31 and the plurality of n-type high refractive index layers 32 are alternately stacked. The interference reflection section 30 shown in Figure 1 is formed between the anode electrode 11 and the light-emitting layer 24, in contact with the anode electrode 11. Note that the material having p-type conductivity is a material with hole transport properties. The material having n-type conductivity is a material with electron transport properties.

[0032] The multiple p-type low refractive index layers 31 and the multiple n-type high refractive index layers 32 have refractive indices and film thicknesses defined in correspondence with the emission wavelength. For example, in the p-type low refractive index layer 31, the refractive index may be 1.4 or higher and 1.6 or lower. In the n-type high refractive index layer 32, the refractive index may be 2.0 or higher and 2.2 or lower. The difference in refractive index between the p-type low refractive index layer 31 and the n-type high refractive index layer 32 should be 0.4 or higher.

[0033] The p-type low refractive index layer 31 may have a thickness of approximately 120 nm when the emitted color is a visible light spectrum of red. The n-type high refractive index layer 32 may have a thickness of approximately 70 nm when the emitted color is a visible light spectrum of red. The p-type low refractive index layer 31 may have a thickness of approximately 90 nm when the emitted color is a visible light spectrum of green. The n-type high refractive index layer 32 may have a thickness of approximately 70 nm when the emitted color is a visible light spectrum of green. The p-type low refractive index layer 31 may have a thickness of approximately 65 nm when the emitted color is a visible light spectrum of blue. The n-type high refractive index layer 32 may have a thickness of approximately 55 nm when the emitted color is a visible light spectrum of blue.

[0034] The film thickness of the p-type low refractive index layer 31 and the n-type high refractive index layer 32 can be determined depending on the emission wavelength and refractive index. More specifically, the combined film thickness of the p-type low refractive index layer 31 and the n-type high refractive index layer 32 may be determined to satisfy the condition that it is 1 / 4 of the in-layer wavelength obtained by dividing the emission wavelength by the refractive index. Note that each film thickness may contain an error of, for example, 10% or less. In the interference reflection section 30, the multiple p-type low refractive index layers 31 and the multiple n-type high refractive index layers 32 can each be configured with a film thickness that is optimal for the wavelength of the emitted color.

[0035] The emission spectrum from the light-emitting layer 24 produces a microcavity effect between the opposing first and second reflective surfaces. Here, let L be the optical distance between the first and second reflective surfaces. Let λ be the peak wavelength of the emission. Let θ be the angle at which the emission from the element is viewed, with 0° being the angle when the element is directly facing the element and being viewed from there. Let φ [rad] be the sum of the phase shifts when the emission is reflected by the first and second reflective surfaces. The optical distance L is the sum of the optical thickness of the organic compound layer between the first and second reflective surfaces. Note that the optical thickness is obtained by multiplying the actual thickness by the refractive index. When the emission is actually reflected by the first and second reflective surfaces, the sum of the phase shifts φ changes depending on the combination of materials constituting the reflective interface. In this case, if there is a relationship between each parameter that satisfies equation (1), constructive interference due to resonance effect can be utilized.

[0036]

number

[0037] In the organic light-emitting device 1, the cathode electrode 12 is the first reflective surface. The interference reflection section 30 includes a plurality of second reflective surfaces at the interface between a plurality of p-type low refractive index layers 31 and a plurality of n-type high refractive index layers 32. Light emitted from the light-emitting layer 24 and light reflected by the cathode electrode 12 are reflected with a predetermined reflectivity when incident from one of the n-type high refractive index layers 32 to one of the p-type low refractive index layers 31. The peak wavelength that is most strongly amplified by resonance can be adjusted in accordance with the optical film thickness of the light-emitting structure 20 and the interference reflection section 30.

[0038] Figures 2 to 4 are curve graphs showing simulation examples of reflectance corresponding to the number of pairs of p-type low refractive index layers 31 and n-type high refractive index layers 32. Figure 2 shows a simulation example corresponding to emission with a red visible light spectrum. Figure 3 shows a simulation example corresponding to emission with a green visible light spectrum. Figure 4 shows a simulation example corresponding to emission with a blue visible light spectrum.

[0039] In the example of red light emission simulation shown in Figure 2, curve CV11 indicates the reflectance of an electrode having a three-layer structure of ITO / Ag / ITO, where a silver thin film is sandwiched between ITO films. Curve CV12 indicates the reflectance of a laminate with 3 pairs of p-type low refractive index layers 31 and n-type high refractive index layers 32. Curve CV13 indicates the reflectance of a laminate with 4 pairs of p-type low refractive index layers 31 and n-type high refractive index layers 32. Curve CV14 indicates the reflectance of a laminate with 5 pairs of p-type low refractive index layers 31 and n-type high refractive index layers 32. Curve CV15 indicates the reflectance of a laminate with 6 pairs of p-type low refractive index layers 31 and n-type high refractive index layers 32. Curve CV16 indicates the reflectance of a laminate with 7 pairs of p-type low refractive index layers 31 and n-type high refractive index layers 32. Curve CV17 indicates the reflectance of a laminate with 8 pairs of p-type low refractive index layers 31 and n-type high refractive index layers 32. Curve CV18 indicates the reflectance of a laminate with 9 pairs of p-type low refractive index layers 31 and n-type high refractive index layers 32.

[0040] In the green light emission simulation example shown in Figure 3, curve CV21 indicates the reflectance of an electrode having a three-layer structure of ITO / Ag / ITO. Curve CV22 indicates the reflectance when there is one pair of p-type low refractive index layer 31 and n-type high refractive index layer 32. Curve CV23 indicates the reflectance of a laminate with two pairs of p-type low refractive index layer 31 and n-type high refractive index layer 32. Curve CV24 indicates the reflectance of a laminate with three pairs of p-type low refractive index layer 31 and n-type high refractive index layer 32. Curve CV25 indicates the reflectance of a laminate with four pairs of p-type low refractive index layer 31 and n-type high refractive index layer 32. Curve CV26 indicates the reflectance of a laminate with five pairs of p-type low refractive index layer 31 and n-type high refractive index layer 32. Curve CV27 indicates the reflectance of a laminate with 6 pairs of p-type low refractive index layers 31 and n-type high refractive index layers 32. Curve CV28 indicates the reflectance of a laminate with 7 pairs of p-type low refractive index layers 31 and n-type high refractive index layers 32.

[0041] In the blue light emission simulation example shown in Figure 4, curve CV31 indicates the reflectance of an electrode having a three-layer structure of ITO / Ag / ITO. Curve CV32 indicates the reflectance when there is one pair of p-type low refractive index layer 31 and n-type high refractive index layer 32. Curve CV33 indicates the reflectance when there are two pairs of p-type low refractive index layer 31 and n-type high refractive index layer 32. Curve CV34 indicates the reflectance when there are three pairs of p-type low refractive index layer 31 and n-type high refractive index layer 32. Curve CV35 indicates the reflectance when there are four pairs of p-type low refractive index layer 31 and n-type high refractive index layer 32. Curve CV36 indicates the reflectance when there are five pairs of p-type low refractive index layer 31 and n-type high refractive index layer 32. Curve CV37 shows the reflectance when there are 6 pairs of p-type low refractive index layers 31 and n-type high refractive index layers 32. Curve CV38 shows the reflectance when there are 7 pairs of p-type low refractive index layers 31 and n-type high refractive index layers 32.

[0042] These simulation examples show that the interference reflection section 30 has a reflectivity comparable to that of an electrode with a three-layer structure of ITO / Ag / ITO, and it is preferable that the number of pairs of p-type low refractive index layers 31 and n-type high refractive index layers 32 be 7 or more so that a reflectivity of 90% or more can be obtained. In the interference reflection section 30 shown in Figure 1, the number of pairs of p-type low refractive index layers 31 and n-type high refractive index layers 32 is 7. In this case, the interference reflection section 30 of the organic light-emitting device 1 is constructed by alternately stacking seven p-type low refractive index layers 31 having p-type conductivity and a low refractive index as a plurality of first charge generation layers having a first conductivity type and a first refractive index, and seven n-type high refractive index layers 32 having n-type conductivity and a high refractive index as a plurality of second charge generation layers having a second conductivity type and a second refractive index.

[0043] The p-type low refractive index layer 31 may be realized as a first-conductivity material by laminating or doping any inorganic material that functions as an electron-accepting additive, such as Lewis acid compounds like molybdenum trioxide (MoO3), or vanadium pentoxide (V2O5), rhenium heptaoxide (Re2O7), or other metal oxides or metal halides, with an organic material as a hole transport material. Alternatively, a p-type conductive material may be realized as a first-conductivity material by doping any organic dopant that functions as an electron-accepting additive, represented by a specific chemical formula, such as organic materials having fluorine, cyano groups, or other substituents, titanyl phthalocyanine, other p-type conductive phthalocyanine compounds, or hexaazatriphenylene (HAT) derivatives including hexaazatriphenylene-hexacarbonnitrile (HAT-CN), with a host organic material as a hole transport material. Thus, the p-type low refractive index layer 31 can be any organic material layer exhibiting electron-acceptance, doped with p-type conductive impurities to a hole transport material as a charge transport material.

[0044] The n-type high refractive index layer 32 may be realized as an n-type conductive material as a second conductivity type material by laminating or doping any inorganic material that functions as an electron-donating additive, such as lithium fluoride (LiF), cesium fluoride (CsF), barium oxide (BaO), other alkali metals, alkaline earth metals, compounds thereof, or rare earth metals, with an organic material as an electron transport material, or by doping any organic dopant that functions as an electron-donating additive, represented by a specific chemical formula, such as antimony phthalocyanine compounds or other n-type conductive phthalocyanine compounds, with a host organic material as an electron transport material. Thus, the n-type high refractive index layer 32 can be any organic material layer that exhibits electron-donating properties by doping an n-type conductive impurity with respect to a hole transport material as a charge transport material.

[0045] The p-type low refractive index layer 31 may achieve a low refractive index as the first refractive index by using an organic material containing a boron-coordinating compound, such as a condensed heteroaromatic ring containing nitrogen and boron, an organic material having fluorine as a substituent, or any other inorganic or organic material having a low refractive index. The n-type high refractive index layer 32 may achieve a high refractive index as the second refractive index by using, for example, an aromatic amine derivative, a carbazole derivative, a benzimidazole derivative, or a triazole derivative, or any other inorganic or organic material having a high refractive index.

[0046] Figure 5 is a cross-sectional view of the red light-emitting device 1R, the green light-emitting device 1G, the blue light-emitting device 1B, these three primary color light-emitting devices, and the drive TFT 41 that drives each light-emitting device. The red light-emitting device 1R, the green light-emitting device 1G, and the blue light-emitting device 1B are each fitted with the organic light-emitting device 1 according to this embodiment. The red light-emitting device 1R includes an interference reflection section 30R in which the interference reflection section 30 of the organic light-emitting device 1 according to this embodiment is applied to correspond to the red visible light spectrum. The green light-emitting device 1G includes an interference reflection section 30G in which the interference reflection section 30 of the organic light-emitting device 1 according to this embodiment is applied to correspond to the green visible light spectrum. The blue light-emitting device 1B includes an interference reflection section 30B in which the interference reflection section 30 of the organic light-emitting device 1 according to this embodiment is applied to correspond to the blue visible light spectrum.

[0047] Figure 5 also shows the pixel definition layer (PDL) 42. The pixel definition layer 42 is a resin layer having an aperture pattern. At each aperture of the pixel definition layer 42, the anode electrodes 11 contained in the red light-emitting device 1R, the green light-emitting device 1G, and the blue light-emitting device 1B are exposed. The pixel definition layer 42 separates the red light-emitting device 1R, the green light-emitting device 1G, the blue light-emitting device 1B, and several adjacent light-emitting devices including these from one another.

[0048] The red light-emitting device 1R, along with a correspondingly positioned driving TFT 41, a switching TFT that supplies a scanning signal to the gate electrode, and a pixel circuit having a retention capacitor that holds the pixel signal, constitutes a red light-emitting pixel 101R that emits red light. The green light-emitting device 1G, along with a correspondingly positioned driving TFT 41, a switching TFT, and a pixel circuit having a retention capacitor, constitutes a green light-emitting pixel 101G that emits green light. The blue light-emitting device 1B, along with a correspondingly positioned driving TFT 41, a switching TFT, and a pixel circuit having a retention capacitor, constitutes a blue light-emitting pixel 101B that emits blue light. The driving TFT 41 is formed using known techniques and is conductive to the anode electrode 11 of the correspondingly positioned light-emitting device below the pixel definition layer 42. The red light-emitting device 1R, the green light-emitting device 1G, and the blue light-emitting device 1B each receive drive current from the power supply line via the correspondingly positioned driving TFT 41. The driving TFT 41 controls the drive current flowing to the red light-emitting device 1R, green light-emitting device 1G, and blue light-emitting device 1B according to the voltage level of the pixel signal held in the holding capacitor. The red light-emitting pixel 101R, green light-emitting pixel 101G, and blue light-emitting pixel 101B are also called sub-pixels.

[0049] In the organic light-emitting device 1, which functions as a red light-emitting device 1R, the light-emitting layer 24 exhibits a red visible light spectrum as an example of a first color. The interference reflection section 30R shown in Figure 5 is formed on the anode electrode 11 included in the red light-emitting device 1R. In the interference reflection section 30R, a plurality of p-type low refractive index layers 31 and a plurality of n-type high refractive index layers 32 each have refractive indices and film thicknesses defined to correspond to the red visible light spectrum.

[0050] In the organic light-emitting device 1, which functions as a green light-emitting device 1G, the light-emitting layer 24 exhibits a green visible light spectrum as an example of a second color. The interference reflection section 30G shown in Figure 5 is formed on the anode electrode 11 included in the green light-emitting device 1G. In the interference reflection section 30G, a plurality of p-type low refractive index layers 31 and a plurality of n-type high refractive index layers 32 each have refractive indices and film thicknesses defined to correspond to the green visible light spectrum.

[0051] In the organic light-emitting device 1, which functions as a blue light-emitting device 1B, the light-emitting layer 24 exhibits a blue visible light spectrum as an example of a third color. The interference reflection section 30B shown in Figure 5 is formed on the anode electrode 11 included in the blue light-emitting device 1B. In the interference reflection section 30B, the multiple p-type low refractive index layers 31 and the multiple n-type high refractive index layers 32 each have refractive indices and film thicknesses defined to correspond to the blue visible light spectrum. Note that the combination of the first to third colors may be any combination of colors with different emission wavelengths.

[0052] In the structure shown in Figure 5, the circuit board 10, on which the anode electrode 11 and cathode electrode 12 are provided facing each other at the top, is divided into three regions, from the first to the third, corresponding to the red light-emitting device 1R, the green light-emitting device 1G, and the blue light-emitting device 1B, respectively. In the first region of the circuit board 10, a light-emitting layer 24 showing the red visible light spectrum included in the red light-emitting device 1R is formed between the anode electrode 11 and the cathode electrode 12, and an interference reflection portion 30R for the red visible light spectrum is formed on the anode electrode 11 in contact with the anode electrode 11. In the second region of the circuit board 10, a light-emitting layer 24 showing the green visible light spectrum included in the green light-emitting device 1G is formed between the anode electrode 11 and the cathode electrode 12, and an interference reflection portion 30G for the green visible light spectrum is formed on the anode electrode 11 in contact with the anode electrode 11. In the third region on the circuit board 10, a light-emitting layer 24 that shows the blue visible light spectrum contained in the blue light-emitting device 1B is formed between the anode electrode 11 and the cathode electrode 12, and an interference reflection portion 30B for the blue visible light spectrum is formed on the anode electrode 11 in contact with the anode electrode 11.

[0053] The organic light-emitting device 1 eliminates the need for metal film reflective electrodes due to the interference reflection section 30, thereby suppressing light loss near the electrodes due to the surface plasmon effect. As a result, light loss is suppressed compared to conventional structures and known technologies, improving luminescence efficiency. Furthermore, since electrodes are not placed in the resonant region of the microcavity structure, light absorption by the electrodes is avoided, further improving luminescence efficiency.

[0054] Multiple pixel circuits are formed on the circuit board 10. These pixel circuits control the current supplied to the anode electrodes 11 of each of the multiple subpixels. Figure 6(A) is a circuit diagram showing pixel circuit PX01 as an example of the configuration of a first pixel circuit. Figure 6(B) is a circuit diagram showing pixel circuit PX02 as an example of the configuration of a second pixel circuit. The circuit board 10 only needs to have multiple pixel circuits, such as multiple pixel circuits PX01 or multiple pixel circuits PX02.

[0055] The pixel circuit PX01 shown in Figure 6(A) includes transistors Tr01 to Tr03 and a retaining capacitor Cs01, and can control the light emission from the light-emitting element E1, which is an organic light-emitting device 1 as an OLED element. The anode AN of the light-emitting element E1 may be the anode electrode 11. The cathode CA of the light-emitting element E1 may be the cathode electrode 12. Transistors Tr01 to Tr03 are all p-type TFTs. Transistor Tr01 is a driving TFT 41 positioned corresponding to the light-emitting element EL. Transistor Tr02 is a TFT for image signal writing control as a switching TFT, and functions as a switch for selecting sub-pixels. Transistor Tr03 is a light emission control TFT as an emission transistor, and functions as a switch for controlling the supply and stop of drive current to the light-emitting element EL.

[0056] The gate terminal of transistor Tr01 is connected to the drain terminal of transistor Tr02. The source terminal of transistor Tr01 is connected to the drive power line 141. The drive power line 141 is supplied with the drive voltage VDD. The drain terminal of transistor Tr01 is connected to the source terminal of transistor Tr03. A retaining capacitor Cs01 is connected between the gate terminal and the source terminal of transistor Tr01.

[0057] The gate terminal of transistor Tr02 is connected to scan line 142. The source terminal of transistor Tr02 is connected to data line 143. The drain terminal of transistor Tr02 is connected to the gate terminal of transistor Tr01.

[0058] The gate terminal of transistor Tr03 is connected to emission control line 144. The source terminal of transistor Tr03 is connected to the drain terminal of transistor Tr01. The drain terminal of transistor Tr03 is connected to the anode AN of light-emitting element E1. A cathode voltage VEE is applied to the cathode CA of light-emitting element E1.

[0059] The scan line 142 transmits selection pulses output from the scan driver or other components of the display device. In response to the selection pulse, transistor Tr02 switches from the off state to the on state. The data line 143 is supplied with data voltage VDATA from the driver IC or other components of the display device. When transistor Tr02 is in the on state, the data voltage VDATA is stored in the retention capacitor Cs01. The retention capacitor Cs01 holds the stored voltage throughout one frame period. The conductance of transistor Tr01 changes analogously according to the retention voltage of the retention capacitor Cs01. As a result, transistor Tr01 supplies a forward bias current corresponding to the light emission gradation to the light-emitting element E1.

[0060] Transistor Tr03 is located on the drive current supply path. Emission control line 144 transmits control signals output from the display device's emission driver, etc. The on / off state of transistor Tr03 is controlled in accordance with the control signals on emission control line 144. When transistor Tr03 is on, drive current is supplied to the light-emitting element E1. When transistor Tr03 is off, this supply is stopped. The duty cycle, which is the lighting period within one field cycle, can be controlled by controlling the on / off state of transistor Tr03.

[0061] The pixel circuit PX02 shown in Figure 6(B) has a transistor Tr04 instead of the transistor Tr03 of the pixel circuit PX01. Transistor Tr04 controls the electrical connection between the reference voltage supply line 145 and the anode AN of the light-emitting element E1. The reference voltage supply line 145 is supplied with a reference voltage VREF. The gate terminal of transistor Tr04 is connected to the reset control line 146. The reset control line 146 transmits the reset control signal output from the reset IC of the display device, etc. The on / off state of transistor Tr04 is controlled in accordance with the reset control signal in the reset control line 146.

[0062] Transistor Tr04 may be used to suppress crosstalk due to leakage current between multiple light-emitting elements E1. For example, the anode AN of a light-emitting element E1 may be reset by transistor Tr04 to a voltage sufficiently low, below the black signal level.

[0063] Transistor Tr04 may be used to measure the characteristics of transistor Tr01 as a driving transistor. For example, bias conditions are selected such that transistor Tr01 operates in the saturation region and transistor Tr04 operates in the linear region. Under these bias conditions, the voltage-current conversion characteristics of transistor Tr01 can be accurately measured by measuring the current flowing from the drive power supply line 141 having the drive voltage VDD to the reference voltage supply line 145 having the reference voltage VREF. When differences in voltage-current conversion characteristics among multiple transistors Tr01 corresponding to multiple subpixels are compensated by generating data signals in an external circuit, the display device can produce a display image with high uniformity.

[0064] Transistor Tr04 may be used to accurately measure the voltage-current characteristics of the light-emitting element E1. For example, when transistor Tr01 is in the off state, transistor Tr04 is operated in the linear region. In this case, the voltage that causes the light-emitting element E1 to emit light is supplied from the reference voltage supply line 145. For example, if the degradation of the light-emitting element E1 due to prolonged use is compensated for by generating data signals in an external circuit, the display device may have a longer lifespan.

[0065] The circuit board 10 may have pixel circuits with different circuit configurations from the pixel circuit PX01 in Figure 6(A) and the pixel circuit PX02 in Figure 6(B). Transistors Tr01 to Tr04 may use n-type TFTs instead of p-type TFTs. Pixel circuits PX01, PX02, and any other arbitrary pixel circuits should be able to compensate for variations in the threshold voltage of the multiple driving transistors Tr01 to suppress image quality degradation. Display irregularities that are not sufficiently suppressed by the pixel circuits may be suppressed by any technique that suppresses differences in transistor characteristics.

[0066] Figure 7 shows bar graphs BC01 to BC03 for comparing optical loss and luminous efficiency obtained from optical simulations. Bar graph BC01 shows the percentage of optical loss due to the surface plasmon effect. Bar graph BC02 shows the percentage of absorption by the anode electrode such as ITO. Bar graph BC03 shows the ratio of luminous efficiency to the conventional structure. On the horizontal axis, known technology KA01, known technology KA03, and conventional structure SA01 are set as comparison targets for embodiment PD01 according to this disclosure. Known technology KA01, as shown in Patent Document 1, consists of a structure in which ITO is used as the anode electrode, a dielectric mirror is provided below the ITO in which high refractive index and low refractive index dielectrics are stacked, and a light reflective layer is used further below. Known technology KA03, as shown in Patent Document 3, consists of a structure in which ITO is used as the anode electrode, and a reflector is used which is stacked with a copolymer of high refractive index and low refractive index at the bottom of the back side of the TFT substrate. Conventional structure SA01 uses a reflective metal electrode as the anode electrode. The results shown in bar graphs BC01 to BC03 are all results obtained from the optical simulations related to this disclosure.

[0067] The percentage of optical loss shown by the bar graph BC01 should be obtainable as the optical loss caused by the surface plasmon effect by calculating the parcel factor. In the case of the conventional structure SA01, the percentage of optical loss is close to 60%. In contrast, in known technologies KA01 and KA03, the percentage of optical loss is reduced to about 10% by using ITO for the anode electrode. In embodiment PD01 of this disclosure, the percentage of optical loss is further reduced to about 5% by using an interference reflection portion 30 formed on the upper part of the anode electrode 11.

[0068] The absorption rate shown by bar graph BC02 is due to the anode electrode formed in the microcavity. In known technology KA01, a dielectric mirror is formed below the anode electrode, which uses ITO as the first electrode. The dielectric mirror in known technology KA01 acts as an optical resonator. In known technology KA03, a TFT array substrate and an optical element are formed below the anode electrode, which uses ITO as the first electrode. The optical element in known technology KA03 selectively reflects light of a wavelength corresponding to the emission color of the emission layer. In these structures, the light emitted and reflected by the reflective part of the emission layer passes through the anode electrode using ITO many times. Therefore, in known technologies KA01 and KA03, in order to achieve a sheet resistance equivalent to that of the conventional structure SA01 using ITO / Ag / ITO, for example, the film thickness of the ITO needs to be increased to a certain extent, which increases light absorption. Embodiment PD01 of this disclosure uses an interference reflection portion 30 formed on the upper part of the anode electrode 11, so that the absorption rate is approximately 0%, similar to the conventional structure SA01.

[0069] As shown in the luminous efficiency ratio by bar graph BC03, known technologies KA01 and KA03 have luminous efficiency comparable to that of the conventional structure SA01. In contrast, embodiment PD01 of the present disclosure achieves a luminous efficiency more than 1.5 times higher than the conventional structure SA01 by using an interference reflection portion 30 formed on the upper part of the anode electrode 11. Thus, embodiment PD01 of the present disclosure having an interference reflection portion 30 eliminates the need for a reflective electrode using a metal electrode and improves luminous efficiency by eliminating absorption in the anode electrode using ITO.

[0070] A portion of the light emitted by an organic light-emitting element has a component parallel to the emission surface, causing reflection and limiting its extraction to the outside. The luminous efficiency of the organic light-emitting element can potentially be further improved by increasing the efficiency of such light extraction. Therefore, microlenses may be used as part of the external or internal structure of the organic light-emitting device 1.

[0071] Figures 8(A) and 8(B) are schematic diagrams showing examples of the configuration of a light extraction layer 50 that can be used as the external structure of the organic light-emitting device 1. A sealing layer 51 is formed on the upper part of the organic light-emitting device 1. For example, the sealing layer 51 can be made of hard glass, or a flexible transparent inorganic material or transparent organic material. The light extraction layer 50 is formed on top of the sealing layer 51. A polarizing plate 52 is formed on top of the light extraction layer 50 shown in Figure 8(A). A color filter 53, a black matrix 54, and an anti-reflective layer 55 are formed on top of the light extraction layer 50 shown in Figure 8(B). The light extraction layer 50 shown in Figures 8(A) and 8(B) is formed on a different side from the circuit board 10, outside the anode electrode 11 and cathode electrode 12 which are provided opposite each other on the circuit board 10.

[0072] The light extraction layer 50 includes a high refractive index region 50A and a low refractive index region 50B. In a direction perpendicular to the plane of the circuit board 10 or the plane of the light-emitting layer 24, the high refractive index region 50A overlaps with the light-emitting layer 24 of the organic light-emitting device 1. The high refractive index region 50A is formed in contact with the low refractive index region 50B above it. On the other hand, the low refractive index region 50B does not overlap with the light-emitting layer 24 of the organic light-emitting device 1 in a direction perpendicular to the plane of the circuit board 10 or the plane of the light-emitting layer 24, but overlaps with the pixel definition layer 42. The low refractive index region 50B should be formed so as to surround the light-emitting layer 24 of the organic light-emitting device 1. The thickness of the low refractive index region 50B has a curved shape that gradually decreases in a direction parallel to the plane of the circuit board 10 or the plane of the light-emitting layer 24, etc., from the pixel definition layer 42 which is farther from the light-emitting layer 24 of the organic light-emitting device 1 to the direction closer to the light-emitting layer 24 of the organic light-emitting device 1. In other words, in a direction parallel to the plane of the circuit board 10 or the plane of the light-emitting layer 24, etc., the thickness of the low refractive index region 50B increases in a curved shape in a direction from the direction closer to the light-emitting layer 24 of the organic light-emitting device 1 to the direction farther away.

[0073] In the light extraction layer 50 shown in Figures 8(A) and 8(B), light emitted vertically from the organic light-emitting device 1 travels straight through the high refractive index region 50A and is extracted to the outside, as indicated by arrow LP1. In contrast, light emitted obliquely from the organic light-emitting device 1 is refracted in the light extraction layer 50, as indicated by arrows LP2 or LP3. According to the law of refraction of light, when light is incident from a medium with a high refractive index to a medium with a low refractive index, light with an incident angle exceeding the critical angle undergoes total internal reflection. As indicated by arrows LP2 or LP3, the light from the organic light-emitting device 1 is deflected vertically by total internal reflection at the interface between the high refractive index region 50A and the low refractive index region 50B. This increases the probability that the light emitted from the organic light-emitting device 1 is emitted to the outside, thereby improving the light extraction efficiency.

[0074] A display device using an organic light-emitting device may be equipped with a touch panel function. In this case, the light extraction layer 50 shown in Figures 8(A) and 8(B) may be provided on the wiring TW of the touch panel.

[0075] The polarizing plate 52 shown in Figure 8(A) is provided as an anti-reflective coating to prevent a decrease in visibility due to the reflection of ambient light. However, the polarizing plate 52 blocks not only ambient light but also some of the light emitted by the organic light-emitting device 1, making it difficult to improve luminescence efficiency. Furthermore, the thickness of the polarizing plate 52 makes it difficult to achieve thinness and flexibility. In contrast, the color filter 53, black matrix 54, and anti-reflective layer 55 shown in Figure 8(B) reduce the reflection of ambient light, improve luminescence efficiency, and facilitate the achievement of thinness and flexibility. For example, the color filter 53 can block ambient light other than specific wavelengths, thereby improving the monochromaticity of the organic light-emitting device 1. The black matrix 54 can absorb ambient light and reflected light. Therefore, the color filter 53, black matrix 54, and anti-reflective layer 55 shown in Figure 8(B) eliminate the need for the polarizing plate 52 shown in Figure 8(A) and the circular polarizing plate as a phase difference plate.

[0076] Figure 9 is a schematic diagram showing an example configuration of a microlens array 60 that can be used as the internal structure of the organic light-emitting device 1. A smoothing layer 61 is formed on the circuit board 10 shown in Figure 9. The organic light-emitting device 1, including the light-emitting structure 20 and the interference reflection section 30, together with the anode electrode 11 and cathode electrode 12 provided opposite each other, is formed as a microlens array 60 on top of the smoothing layer 61. An overcoat layer 62 is provided on top of the microlens array 60. A wavelength conversion layer, a passivation layer, a face seal, a protective film, or all or part thereof may be provided on top of the overcoat layer 62.

[0077] Below the overcoat layer 62, the anode electrode 11, cathode electrode 12, light-emitting structure 20, and interference reflection section 30 are arranged along the shapes of the maximum, inclined, and minimum portions of the surface of the overcoat layer 62, and have the shape of microlenses. In the microlens array 60, portions where two or more microlenses are adjacent constitute a minimum portion. The central portion of a microlens constitutes a maximum portion. The space between the maximum and minimum portions constitutes an inclined portion. In the microlens array 60, the components of the organic light-emitting device 1, such as the anode electrode 11, cathode electrode 12, light-emitting structure 20, and interference reflection section 30, have the same shape as the maximum, minimum, and inclined portions of the microlenses in the overcoat layer 62.

[0078] The light generated in the light-emitting structure 20 is repeatedly reflected between the cathode electrode 12 and the interference reflection section 30. At this time, the shape of the microlenses changes the path of the light to a direction perpendicular to the plane of the circuit board 10. The microlens array 60 is arranged throughout the light-emitting region of the organic light-emitting device 1. This increases the probability that the light emitted from the organic light-emitting device 1 is emitted to the outside, thereby improving the light extraction efficiency.

[0079] Figure 10 is a bar graph BC10 for comparing the loss ratio in light-emitting elements based on optical simulation results. On the horizontal axis of the bar graph BC10, known technologies KA02, KA03, and conventional structure SA01 are set as comparison targets for Embodiment PD01 according to this disclosure. Known technology KA02, as in Patent Document 2, has an organic layer between the light-emitting layer and the anode electrode, which has either a high or low refractive index and is either n-type or p-type polarity. Known technology KA03, as in Patent Document 3, uses ITO for the anode electrode and employs a reflective structure laminated with a copolymer of high and low refractive indices on the lower back side of the TFT substrate. Conventional technology SA01 uses a reflective metal electrode for the anode electrode. The bar graph BC10 is also based on results obtained from optical simulations according to this disclosure. In addition to the emitted light LE1, the light emission in a light-emitting element includes losses DL1 due to absorption in the material, losses DL2 due to light confinement in the organic layer, and optical losses DL3.

[0080] In the conventional structure SA01, the optical loss DL3 is close to 60%. In the known technologies KA02 and KA03, the optical loss DL3 exceeds 70%. In these cases, even if optical extraction technology is employed, there is a risk that light cannot be extracted efficiently due to the large optical loss. Known technologies KA02 and KA03 increase the microcavity effect and improve monochromaticity. On the other hand, known technologies KA02 and KA03 cannot suppress optical loss.

[0081] In contrast, Embodiment PD01 of this disclosure uses an interference reflection section 30, resulting in a light loss DL3 of approximately 5%. In Embodiment PD01 of this disclosure, the loss DL2 due to light confinement within the organic layer accounts for the majority of the total loss. Therefore, Embodiment PD01 of this disclosure can efficiently extract light by employing light extraction technology, thereby achieving a significant improvement in luminous efficiency.

[0082] Figure 11 is a curve graph for comparing the current-voltage characteristics of organic material layers placed between the anode electrode 11 and the cathode electrode 12. In this comparison, the hole transport layer 22, electron transport layer 26, p-type low refractive index layer 31, and n-type high refractive index layer 32 of the organic light-emitting device 1, and evaluation elements formed from these constituent materials are used. The evaluation element for each constituent material is connected to an evaluation electrode formed from the same material as the anode electrode 11 and the cathode electrode 12. The first evaluation element is a single-film element with a film thickness of 20 nm using the constituent material of the electron transport layer 26. The second evaluation element is a single-film element with a film thickness of 20 nm using the constituent material of the hole transport layer 22. The third evaluation element is a single-film element with a film thickness of 20 nm using the constituent material of the n-type high refractive index layer 32. The fourth evaluation element is a single-film element with a film thickness of 20 nm using the constituent material of the p-type low refractive index layer 31. The fifth evaluation element is a multilayer film element with a film thickness of 40 nm, formed by stacking the constituent materials of a p-type low refractive index layer 31 having a film thickness of 20 nm and the constituent materials of an n-type high refractive index layer 32 having a film thickness of 20 nm.

[0083] In the curve graph shown in Figure 11, curve CV51 represents the characteristics of the first evaluation element. Curve CV52 represents the characteristics of the second evaluation element. Curve CV53 represents the characteristics of the third evaluation element. Curve CV54 represents the characteristics of the fourth evaluation element. Curve CV55 represents the characteristics of the fifth evaluation element. The p-type low refractive index layer 31 and the n-type high refractive index layer 32 have higher conductivity than the hole transport layer 22 and the electron transport layer 26. The fifth evaluation element, which is formed by stacking the p-type low refractive index layer 31 and the n-type high refractive index layer 32, has the same conductivity as the fourth evaluation element, which is the p-type low refractive index layer 31. In the organic light-emitting device 1, by using a stacked structure of the highly conductive p-type low refractive index layer 31 and the n-type high refractive index layer 32 in the interference reflection section 30, the voltage increase can be suppressed compared to charge transport layers such as the hole transport layer 22 and the electron transport layer 26. Therefore, the organic light-emitting device 1 includes an interference reflection section 30 in which a p-type low refractive index layer 31 and an n-type high refractive index layer 32 are stacked, which enables lower driving voltage and lower power consumption.

[0084] Figure 12 shows the energy states of each layer constituting the organic light-emitting device 1. The energy states shown in Figure 12 include the work function 11W of the anode electrode 11 and the work function 12W of the cathode electrode 12. The energy states of each layer in the light-emitting structure 20 include the energy state 21E of the hole injection layer 21, the energy state 22E of the hole transport layer 22, the energy state 23E of the electron blocking layer 23, the energy state 24E of the light-emitting layer 24, the energy state 25E of the hole blocking layer 25, and the energy states 26E of the electron transport layer 26 and the electron injection layer 27. The energy states of each layer in the interference reflection section 30 include the energy state 31E of the p-type low refractive index layer 31 and the energy state 32E of the n-type high refractive index layer 32. In the example shown in Figure 12, there are 2 pairs of p-type low refractive index layers 31 and n-type high refractive index layers 32. To accommodate other numbers of pairs, the energy state 31E of the p-type low refractive index layer 31 and the energy state 32E of the n-type high refractive index layer 32 may be added. In the energy states of each layer, the upper edge represents the LUMO level, which is the lowest energy orbital in the conductor, and the lower edge represents the HOMO level, which is the highest energy orbital in the valence band.

[0085] When a voltage is applied between the anode electrode 11 and the cathode electrode 12, electrons are supplied from the cathode electrode 12 to the LUMO level of the light-emitting layer 24 via the electron transport layer 26 and electron injection layer 27 of the light-emitting structure 20, and holes are supplied from the anode electrode 11 to the HOMO level of the light-emitting layer 24 via the hole injection layer 21 and hole transport layer 22 of the light-emitting structure 20. The electrons and holes supplied to the light-emitting layer 24 recombine inside the light-emitting layer 24, generating light emission.

[0086] In the organic light-emitting device 1, the interference reflection section 30 has a laminated structure of a p-type low refractive index layer 31 and an n-type high refractive index layer 32 with different polarities. In this laminated structure, a charge transfer complex is formed between the p-type low refractive index layer 31, which has electron-accepting properties, and the n-type high refractive index layer 32, which has electron-donating properties, allowing charge transport without hindering the supply of carriers to each layer. In other words, it can be fabricated as a low-voltage pn-connected multi-unit. In Figure 12, a charge transfer complex is formed at the interface between the p-type low refractive index layer 31 and the n-type high refractive index layer 32 by a redox reaction, and when a voltage is applied, holes in the charge transfer complex move to the hole transport layer 22 side, and electrons move to the anode electrode 11 side. Therefore, the voltage rise between the anode electrode 11 and the cathode electrode 12 due to the interference reflection section 30 is suppressed, and carriers can be smoothly injected from the anode electrode 11 side to the hole injection layer 21 via the interference reflection section 30.

[0087] The electrical properties of the p-type low refractive index layer 31 change depending on the p-type dopant concentration, and the electrical properties of the n-type high refractive index layer 32 change depending on the n-type dopant concentration. Figure 13 shows the relationship between the driving voltage of the light-emitting element according to this disclosure and the n-type dopant material concentration in the n-type high refractive index layer 32 (volume concentration of n-type dopant in the n-type high refractive index layer). Here, the driving voltage (vertical axis) is the relative driving voltage ratio normalized by the driving voltage when the n-type dopant material concentration (volume concentration) in the n-type high refractive index layer 32 is 30 vol%, and the p-type dopant material concentration in the p-type low refractive index layer 31 is fixed at 3 vol%. Figure 14 shows the relationship between the driving voltage of the light-emitting element according to this disclosure and the p-type dopant material concentration in the p-type low refractive index layer 31 (volume concentration of p-type dopant in the p-type low refractive index layer). Here, the driving voltage (vertical axis) is the relative driving voltage ratio normalized by the driving voltage when the p-type dopant material concentration in the p-type low refractive index layer 31 is 1 vol%, and the n-type dopant material concentration in the n-type high refractive index layer 32 is fixed at 4 vol%.

[0088] The results in Figures 13 and 14 show that there are n-type dopant concentrations in the n-type high refractive index layer and p-type dopant concentrations in the p-type low refractive index layer that are suitable for efficiently supplying carriers from the stacked structure of the p-type low refractive index layer 31 and the n-type high refractive index layer 32. More specifically, the preferred concentration range for the formation of the aforementioned charge transfer complex is an n-type dopant concentration of 2-10 vol% in the n-type high refractive index layer and a p-type dopant concentration of 3-6 vol% in the p-type low refractive index layer.

[0089] The light-emitting structure 20, located above the interference reflection section 30, can utilize a conventional device structure, thus minimizing changes in carrier balance and suppressing a decrease in luminous efficiency and shortened lifespan. Carrier balance contributes to the external quantum efficiency as the probability of generating excited states through the recombination of electrons and holes injected from the electrodes.

[0090] Figure 15 is a schematic diagram showing a second configuration example of the organic light-emitting device 1 according to this embodiment. In Figure 15, the same reference numerals are used for components identical to those in Figure 1. In the organic light-emitting device 1 shown in Figure 15, the interference reflection section 30 includes a plurality of n-type low refractive index layers 33 having n-type conductivity and a low refractive index as a first charge generation layer having a first conductivity type and a first refractive index. In the organic light-emitting device 1 shown in Figure 15, the interference reflection section 30 includes a plurality of p-type high refractive index layers 34 having p-type conductivity and a high refractive index as a second charge generation layer having a second conductivity type and a second refractive index. In the interference reflection section 30 shown in Figure 15, the plurality of n-type low refractive index layers 33 and the plurality of p-type high refractive index layers 34 are alternately stacked. The interference reflection section 30 shown in Figure 15 is formed between the anode electrode 11 and the light-emitting layer 24, in contact with the anode electrode 11. Thus, in the interference reflection section 30, the first conductivity type and the second conductivity type, the first refractive index and the second refractive index can be any combination of p-type and n-type, and low refractive index and high refractive index.

[0091] Figure 16 is a schematic diagram showing a third configuration example of the organic light-emitting device 1 according to this embodiment. In Figure 16, the same reference numerals are used for components identical to those in Figure 1. In the organic light-emitting device 1 shown in Figure 16, the light-emitting structure 20 has a tandem structure in which two sets of each layer from the hole transport layer 22 to the electron transport layer 26 are formed between the hole injection layer 21 and the electron injection layer 27. Between the first set of hole transport layers 22 to the electron transport layer 26 and the second set of hole transport layers 22 to the electron transport layer 26, an n-type charge generation layer 28 and a p-type charge generation layer 29 are formed. The interference reflection section 30 shown in Figure 16 is formed between the anode electrode 11 and the lower light-emitting layer 24, in contact with the anode electrode 11.

[0092] Figure 17 shows bar graphs BC21 and BC22 for comparing the loss ratios of the conventional structure and the embodiments of the present disclosure. On the horizontal axis of bar graph BC21, the first single structure SA11, the second single structure SA12, and the tandem structure SA13 are set as comparison targets for the conventional technology using a reflective metal electrode as the anode electrode. On the horizontal axis of bar graph BC22, the first single structure PD11, the second single structure PD12, and the tandem structure PD13 are set as comparison targets for the embodiments of the present disclosure.

[0093] Figure 18(A) shows structural comparison examples of a conventional technology using a reflective metal electrode as the anode electrode, specifically a first single structure SA11, a second single structure SA12, and a tandem structure SA13. The first single structure SA11 has a single-layer light-emitting layer 24 with distances DA and DB corresponding to zone Z01 shown in Figure 30(B) as the first resonance condition. The second single structure SA12 has a single-layer light-emitting layer 24 with distances DA and DB corresponding to zone Z03 shown in Figure 30(B) as the second resonance condition. The tandem structure SA13 has a two-layer light-emitting layer 24, which includes a light-emitting layer 24 with distances DA and DB corresponding to zone Z03 shown in Figure 30(B) as the second resonance condition, and a light-emitting layer 24 with distances DA and DB corresponding to zone Z02 shown in Figure 30(B) as the third resonance condition.

[0094] Figure 18(B) shows structural examples of the embodiments of the present disclosure, specifically the first single structure PD11, the second single structure PD12, and the tandem structure PD13. In the first single structure PD11, the interference reflection portion 30 added to the conventional first single structure SA11 is formed in contact with the anode electrode 11 between the anode electrode 11 and the light-emitting layer 24. In the second single structure PD12, the interference reflection portion 30 added to the conventional second single structure SA12 is formed in contact with the anode electrode 11 between the anode electrode 11 and the light-emitting layer 24. In the tandem structure PD13, the interference reflection portion 30 added to the conventional tandem structure SA13 is formed in contact with the anode electrode 11 between the anode electrode 11 and the lower light-emitting layer 24.

[0095] The bar graphs BC21 and BC22 shown in Figure 17 are also results obtained from the optical simulations related to this disclosure. In addition to the emitted light LE1, the light emission from the light-emitting element includes losses DL1 due to absorption in the material, losses DL2 and DL3 due to light confinement within the organic layer.

[0096] The conventional technology shown in bar graph BC21 has an optical loss DL3 of nearly 50% when it is the first single structure SA11. Furthermore, the conventional technology has an optical loss DL3 of approximately 15% when it is the second single structure SA12. The conventional tandem structure SA13 has an optical loss DL3 of approximately 30%. In contrast, the embodiment of the present disclosure shown in bar graph BC22 has an optical loss DL3 of approximately 15% when it is the first single structure PD11. Furthermore, the embodiment of the present disclosure has an optical loss DL3 of less than 5% when it is the second single structure PD12. The tandem structure PD13 of the embodiment of the present disclosure has an optical loss DL3 of less than 10%. Therefore, the tandem structure PD13 of the embodiment of the present disclosure can suppress optical loss DL3 by using the interference reflection section 30, thereby achieving a significant improvement in luminous efficiency.

[0097] Figure 19(A) shows an example configuration of a sub-pixel 502 corresponding to known technologies KA01 and KA03. In the sub-pixel 502, the light-emitting structure 20A is positioned not only above the anode electrode 11A, but also above the inclined portion GA1 in the pixel definition layer 42A and part or all of the upper surface portion GB1 in the pixel definition layer 42A. Therefore, the light-emitting structure 20A is formed in contact with the inclined portion GA1 in the pixel definition layer 42A and part or all of the upper surface portion GB1 in the pixel definition layer 42A. In Figure 19(A), the pixel definition layer 42A has a pixel opening that exposes a part of the anode electrode 11A corresponding to the sub-pixel 502. This pixel opening of the pixel definition layer 42A is formed by the inclined portion GA1. Note that in Figure 19(A), the cathode electrode and capping layer are omitted.

[0098] The sub-pixel 502 corresponding to the known technology KA01 has a dielectric mirror in which high-refractive-index and low-refractive-index dielectrics are stacked beneath the ITO used in the anode electrode 11A, and a light-reflecting layer further beneath the dielectric mirror. The sub-pixel 502 corresponding to the known technology KA03 has an anode electrode 11A made of ITO and a reflective structure stacked with a copolymer of high-refractive-index and low-refractive-index materials on the lower back side of the TFT substrate. In these sub-pixels 502, no reflective structure is formed on the inclined portion GA1 and the upper surface portion GB1 of the pixel definition layer 42A. Therefore, light emitted from the light-emitting structure 20A enters the interior of the pixel definition layer 42A from the inclined portion GA1 and the upper surface portion GB1 of the pixel definition layer 42A. For example, in Figure 19(A), as shown by arrows A01 and A02, the light emitted from the light-emitting structure 20A passes through the inclined portion GA1 of the pixel definition layer 42A and dissipates in a lateral direction parallel to the substrate surface. Therefore, the light extraction rate of the sub-pixel 502 may decrease, making it difficult to improve the luminous efficiency. The same problem occurs in the conventional technology SA01, which uses a reflective metal electrode for the anode electrode 11A.

[0099] Figure 19(B) shows an example of the configuration of a sub-pixel 102 corresponding to an embodiment of the present disclosure. In the sub-pixel 102, part or all of the organic compound layer, including the light-emitting structure 20 and the interference reflection portion 30, is arranged not only above the anode electrode 11, but also above part or all of the inclined portion GA2 and the upper surface portion GB2 of the pixel definition layer 42. In this case, the interference reflection portion 30 is formed in contact with part or all of the inclined portion GA2 and the upper surface portion GB2 of the pixel definition layer 42A. In Figure 19(B), the pixel definition layer 42 has a pixel opening that exposes part of the anode electrode 11 corresponding to the sub-pixel 102. This pixel opening of the pixel definition layer 42 is formed by the inclined portion GA2. Note that in Figure 19(B), the cathode electrode 12 and the capping layer 13 are omitted.

[0100] In the sub-pixel 102, an interference reflection section 30 is formed between the anode electrode 11 and the light-emitting structure 20, and also between the pixel definition layer 42 and the light-emitting structure 20. That is, the reflection structure by the interference reflection section 30 is formed on part or all of the inclined section GA2 and the upper surface section GB2 of the pixel definition layer 42. Therefore, the light emitted from the light-emitting structure 20 is reflected by the interference reflection section 30 and does not enter the interior of the pixel definition layer 42 from the inclined section GA2 and the upper surface section GB2 of the pixel definition layer 42. For example, in Figure 19(B), as shown by arrows A11 and A12, the light emitted from the light-emitting structure 20 does not pass through the inclined section GA2 of the pixel definition layer 42, but travels upward toward the light emission surface. Therefore, the light extraction rate of the sub-pixel 102 can be increased, and the luminescence efficiency can be improved.

[0101] In addition, in the sub-pixel 102, part or all of the organic compound layer including the light-emitting structure 20 and the interference reflection portion 30 may be positioned above the anode electrode 11 and above the inclined portion GA2 in the pixel definition layer 42, but not above the upper surface portion GB2 in the pixel definition layer 42. In this case, the interference reflection portion 30 may be formed in contact with the inclined portion GA2 in the pixel definition layer 42. Thus, part or all of the organic compound layer including the light-emitting structure 20 and the interference reflection portion 30 may be positioned above the anode electrode 11 and at least above the inclined portion GA2 in the pixel definition layer 42.

[0102] (Second Embodiment) Hereinafter, a second embodiment of the organic light-emitting device 2, configured as a type of bottom-emission OLED, will be described. In the organic light-emitting device 2 of the second embodiment, the same reference numerals will be used for components identical to those of the organic light-emitting device 1 of the first embodiment.

[0103] Figure 20 is a schematic diagram showing an example of the configuration of an organic light-emitting device 2 according to the second embodiment. The organic light-emitting device 2 comprises an anode electrode 11 and a cathode electrode 12 provided opposite each other on a circuit board 10. The organic light-emitting device 2 comprises a light-emitting structure 20 and an interference reflection section 30 provided between the anode electrode 11 and the cathode electrode 12. The organic light-emitting device 2 has a laminated structure on the circuit board 10. The anode electrode 11 is the lower electrode as the first electrode in the organic light-emitting device 2. The cathode electrode 12 is the upper electrode as the second electrode in the organic light-emitting device 2. The anode electrode 11 can be formed using a material that is semi-transparent and semi-reflective. In the organic light-emitting device 2 according to this embodiment, metallic reflection by the cathode electrode 12 is not necessary. However, if the reflection characteristics of the interference reflection section 30 are sufficient, a conventional metal electrode can be used for the cathode electrode 12. The light-emitting structure 20 can be configured in the same way as the organic light-emitting device 1 of the first embodiment. However, in the light-emitting structure 20 of the organic light-emitting device 2, the hole injection layer 21 is formed in contact with the anode electrode 11.

[0104] The interference reflection section 30 shown in Figure 20 is formed between the cathode electrode 12 and the light-emitting layer 24, in contact with the cathode electrode 12. In the interference reflection section 30, the multiple p-type low refractive index layers 31 and the multiple n-type high refractive index layers 32 can each be configured with a film thickness optimal for the wavelength of the emitted color. In the organic light-emitting device 2 shown in Figure 20, the interference reflection section 30 is formed in contact with the electron injection layer 27.

[0105] In the organic light-emitting device 2, the anode electrode 11 is the first reflective surface. The interference reflection section 30 includes a plurality of second reflective surfaces at the interface between a plurality of p-type low refractive index layers 31 and a plurality of n-type high refractive index layers 32. Light emitted from the light-emitting layer 24 and light reflected by the anode electrode 11 are reflected with a predetermined reflectivity when incident from the light-emitting structure 20 onto one of the p-type low refractive index layers 31, or when incident from one of the n-type high refractive index layers 32 onto one of the p-type low refractive index layers 31. It is preferable that the interference reflection section 30 has 7 or more pairs of p-type low refractive index layers 31 and n-type high refractive index layers 32. In the interference reflection section 30 shown in Figure 20, the number of pairs of p-type low refractive index layers 31 and n-type high refractive index layers 32 is 7. In this case, the interference reflection section 30 of the organic light-emitting device 2 is constructed by alternately stacking seven p-type low refractive index layers 31 having p-type conductivity and a low refractive index as a plurality of first charge generation layers having a first conductivity type and a first refractive index, and seven n-type high refractive index layers 32 having n-type conductivity and a high refractive index as a plurality of second charge generation layers having a second conductivity type and a second refractive index.

[0106] In this case as well, similar to embodiment PD01 in bar graph BC10 shown in Figure 10, the organic light-emitting device 2 can significantly reduce the ratio of light loss DL3 compared to the conventional structure SA01 by using the interference reflection section 30. Therefore, the organic light-emitting device 2 can achieve a remarkable improvement in luminous efficiency.

[0107] In the organic light-emitting device 2, the interference reflection section 30 includes a plurality of n-type low refractive index layers 33 having n-type conductivity and a low refractive index as a first charge generation layer having a first conductivity type and a first refractive index, and a plurality of p-type high refractive index layers 34 having p-type conductivity and a high refractive index as a second charge generation layer having a second conductivity type and a second refractive index, and the plurality of n-type low refractive index layers 33 and the plurality of p-type high refractive index layers 34 may be alternately stacked. In this case as well, the interference reflection section 30 of the organic light-emitting device 2 is formed between the cathode electrode 12 and the light-emitting layer 24, in contact with the cathode electrode 12.

[0108] In the organic light-emitting device 2, the light-emitting structure 20 may have a tandem structure in which two sets of each layer from the hole transport layer 22 to the electron transport layer 26 are formed between the hole injection layer 21 and the electron injection layer 27. Between the first set of hole transport layers 22 to the electron transport layer 26 and the second set of hole transport layers 22 to the electron transport layer 26, an n-type charge generation layer 28 and a p-type charge generation layer 29 are formed. In this case, the interference reflection section 30 of the organic light-emitting device 2 is formed between the cathode electrode 12 and the upper light-emitting layer 24, in contact with the cathode electrode 12.

[0109] In these cases as well, the organic light-emitting device 2 can significantly reduce the rate of light loss by using the interference reflection section 30. Therefore, the organic light-emitting device 2 can achieve a remarkable improvement in luminous efficiency. Furthermore, by employing light extraction technology using microlenses as an external or internal structure of the organic light-emitting device 2, light emission can be extracted efficiently, thereby achieving a further improvement in luminous efficiency.

[0110] (Third embodiment) The following describes an organic light-emitting device 3 in which the characteristics of the interference reflection section 30 have been modified, as a third embodiment. In the organic light-emitting device 3 of the third embodiment, the same reference numerals will be used for components identical to those in the above embodiment.

[0111] Figure 21 is a schematic diagram showing an example of the configuration of an organic light-emitting device 3 according to a third embodiment, which combines a red light-emitting device 3R, a green light-emitting device 3G, a blue light-emitting device 3B, and these three primary color light-emitting devices. The red light-emitting device 3R includes a light-emitting structure 20R whose light-emitting layer 24 exhibits a red visible light spectrum, corresponding to the light-emitting structure 20 in the above embodiment. The green light-emitting device 3G includes a light-emitting structure 20G whose light-emitting layer 24 exhibits a green visible light spectrum, corresponding to the light-emitting structure 20 in the above embodiment. The blue light-emitting device 3B includes a light-emitting structure 20B whose light-emitting layer 24 exhibits a blue visible light spectrum, corresponding to the light-emitting structure 20 in the above embodiment.

[0112] The red light-emitting device 3R, the green light-emitting device 3G, and the blue light-emitting device 3B all include an anode electrode 11 and a cathode electrode 12 that are provided opposite to each other on the circuit board 10. The red light-emitting device 3R includes a light-emitting structure 20R provided between the anode electrode 11 and the cathode electrode 12. The green light-emitting device 3G includes a light-emitting structure 20G provided between the anode electrode 11 and the cathode electrode 12. The blue light-emitting device 3B includes a light-emitting structure 20B provided between the anode electrode 11 and the cathode electrode 12.

[0113] The red light-emitting device 3R, the green light-emitting device 3G, and the blue light-emitting device 3B shown in Figure 21 all include interference reflection sections 30R, 30G, and 30B, respectively, which are provided between the anode electrode 11 and the cathode electrode 12. The interference reflection section 30R shown in Figure 21 is formed as a first interference reflection section on the anode electrode 11 included in each of the red light-emitting device 3R, the green light-emitting device 3G, and the blue light-emitting device 3B, in contact with the anode electrode 11. In the interference reflection section 30R, the plurality of p-type low refractive index layers 31 and the plurality of n-type high refractive index layers 32 each have refractive indices and film thicknesses defined to correspond to the red visible light spectrum. The interference reflection section 30G shown in Figure 21 is formed as a second interference reflection section on top of the interference reflection section 30R. In the interference reflection section 30G, the plurality of p-type low refractive index layers 31 and the plurality of n-type high refractive index layers 32 each have refractive indices and film thicknesses defined to correspond to the green visible light spectrum. The interference reflection section 30B shown in Figure 21 is formed as a third interference reflection section, in contact with the hole injection layer 21 on top of the interference reflection section 30G. In the interference reflection section 30B, the multiple p-type low refractive index layers 31 and the multiple n-type high refractive index layers 32 each have refractive indices and film thicknesses defined to correspond to the blue visible light spectrum. Thus, in the organic light-emitting device 3 shown in Figure 21, interference reflection sections 30R, 30G, and 30B, which are suited to the reflection conditions of the visible light spectrum corresponding to the red, green, and blue emission colors, are sequentially stacked in the vertical direction, which is the film thickness direction.

[0114] Figure 22 is a curve graph showing the reflectance of the organic light-emitting device 3 equipped with interference reflective sections 30R, 30G, and 30B. In the curve graph shown in Figure 22, curve CV61 indicates the reflectance of the electrode having a two-layer structure of ITO / Ag, which is a combination of a silver thin film and an ITO film. Curve CV62 indicates the reflectance of the interference reflective sections 30R, 30G, and 30B provided in the organic light-emitting device 3. In this way, the organic light-emitting device 3 can appropriately reflect and output red, green, and blue light by using the interference reflective sections 30R, 30G, and 30B. As a result, the organic light-emitting device 3 does not require a reflective electrode made of a metal film, so light loss is suppressed and luminous efficiency can be improved.

[0115] Figure 23 is a bar graph BC30 for comparing the percentage of losses in the organic light-emitting device 3. On the horizontal axis of the bar graph BC30, the first embodiment PD01 using the organic light-emitting device 1, the third embodiment PD31 using the organic light-emitting device 3, and the conventional structure SA01 using a reflective metal electrode as the anode electrode are set as comparison targets. The bar graph BC30 is also the result obtained by optical simulation according to this disclosure. In addition to the emitted light LE1, the light emission in the light-emitting device includes loss DL1 due to absorption in the material, loss DL2 due to light confinement in the organic layer, and optical loss DL3.

[0116] Compared to the first embodiment PD01, which significantly reduced the ratio of light loss DL3 compared to the conventional structure SA01, the organic light-emitting device 3 further reduces the ratio of light loss DL3. Therefore, the organic light-emitting device 3 according to the third embodiment can further suppress the light loss DL3 by using sequentially stacked interference reflection sections 30R, 30G, and 30B, thereby achieving a remarkable improvement in luminous efficiency. Furthermore, by employing light extraction technology using microlenses as an external or internal structure of the organic light-emitting device 3, light emission can be efficiently extracted, further improving luminous efficiency.

[0117] Figure 24 is a cross-sectional view of the red light-emitting device 3R, the green light-emitting device 3G, the blue light-emitting device 3B, these three primary color light-emitting devices, and the driving TFT 41 that drives each light-emitting device. The red light-emitting device 3R, the green light-emitting device 3G, and the blue light-emitting device 3B shown in Figure 24 are included in the organic light-emitting device 3 according to the third embodiment. The driving TFT 41 shown in Figure 24 only needs to be operable in the same way as in Figure 5. Figure 24 also shows a pixel definition layer (PDL) 42 similar to that in Figure 5.

[0118] The red light-emitting device 3R, along with a correspondingly positioned driving TFT 41, a switching TFT that supplies a scanning signal to the gate electrode, and a pixel circuit having a holding capacitor that holds the pixel signal, constitutes a red light-emitting pixel 103R that emits red light. The green light-emitting device 3G, along with a correspondingly positioned driving TFT 41, a switching TFT, and a pixel circuit having a holding capacitor, constitutes a green light-emitting pixel 103G that emits green light. The blue light-emitting device 3B, along with a correspondingly positioned driving TFT 41, a switching TFT, and a pixel circuit having a holding capacitor, constitutes a blue light-emitting pixel 103B that emits blue light.

[0119] In the structure shown in Figure 24, a light-emitting layer 24 showing the red visible light spectrum included in the red light-emitting device 3R, a light-emitting layer 24 showing the green visible light spectrum included in the green light-emitting device 3G, and a light-emitting layer 24 showing the blue visible light spectrum included in the blue light-emitting device 3B are formed between the anode electrode 11 and the cathode electrode 12. In the entire organic light-emitting device 3, an interference reflection portion 30R for the red visible light spectrum, as an example of a first color, is formed on the anode electrode 11 in contact with the anode electrode 11. An interference reflection portion 30G for the green visible light spectrum, as an example of a second color, is formed on the interference reflection portion 30R. An interference reflection portion 30B for the blue visible light spectrum, as an example of a third color, is formed on the interference reflection portion 30G. Note that the combination of the first to third colors may be any combination of colors with different emission wavelengths.

[0120] In the organic light-emitting device 3, all or part of the interference reflection sections 30R, 30G, and 30B include a plurality of n-type low refractive index layers 33 having n-type conductivity and a low refractive index as a first charge generation layer having a first conductivity type and a first refractive index, and a plurality of p-type high refractive index layers 34 having p-type conductivity and a high refractive index as a second charge generation layer having a second conductivity type and a second refractive index, and the plurality of n-type low refractive index layers 33 and the plurality of p-type high refractive index layers 34 may be alternately stacked. In this case as well, the interference reflection section 30R of the organic light-emitting device 3 is formed on the anode electrode 11 in contact with the anode electrode 11 between the anode electrode 11 and the light-emitting layer 24. The interference reflection section 30G of the organic light-emitting device 3 is formed on the interference reflection section 30R between the anode electrode 11 and the light-emitting layer 24. The interference reflection section 30B of the organic light-emitting device 3 is formed on the interference reflection section 30G between the anode electrode 11 and the light-emitting layer 24.

[0121] In the organic light-emitting device 3, all or part of the light-emitting structure 20R included in the red light-emitting device 3R, the light-emitting structure 20G included in the green light-emitting device 3G, and the light-emitting structure 20B included in the blue light-emitting device 3B may have a tandem structure in which two sets of each layer from the hole transport layer 22 to the electron transport layer 26 are formed between the hole injection layer 21 and the electron injection layer 27. Between the first set of hole transport layers 22 to the electron transport layer 26 and the second set of hole transport layers 22 to the electron transport layer 26, an n-type charge generation layer 28 and a p-type charge generation layer 29 are formed. In this case as well, the interference reflection section 30R of the organic light-emitting device 3 is formed on the anode electrode 11 in contact with the anode electrode 11, between the anode electrode 11 and the light-emitting layer 24. The interference reflection section 30G of the organic light-emitting device 3 is formed on the interference reflection section 30R, between the anode electrode 11 and the light-emitting layer 24. The interference reflection section 30B of the organic light-emitting device 3 is formed on the interference reflection section 30G between the anode electrode 11 and the light-emitting layer 24.

[0122] The organic light-emitting device 3 may be configured as a type of bottom-emission OLED. In this case, the interference reflection portion 30R of the organic light-emitting device 3 is formed between the cathode electrode 12 and the light-emitting layer 24, below the cathode electrode 12 and in contact with the cathode electrode 12. The interference reflection portion 30G of the organic light-emitting device 3 is formed between the cathode electrode 12 and the light-emitting layer 24, below the interference reflection portion 30R. The interference reflection portion 30B of the organic light-emitting device 3 is formed between the cathode electrode 12 and the light-emitting layer 24, below the interference reflection portion 30G and in contact with the electron injection layer 27.

[0123] (Fourth Embodiment) As a fourth embodiment, a display device 90 using the organic light-emitting device according to the above-described embodiment will be explained. Figure 25 is a schematic diagram showing an example of the configuration of the display device 90 according to this embodiment.

[0124] The display device 90 comprises a TFT substrate 110 similar to the circuit board 10, a sealing substrate 200, and a bonding portion (glass frit seal portion) 300. One of the organic light-emitting devices 1 to 3, which are OLED elements, is formed on the TFT substrate 110. The sealing substrate 200 is positioned opposite the TFT substrate 110. The bonding portion 300 is provided between the TFT substrate 110 and the sealing substrate 200, bonding the TFT substrate 110 and the sealing substrate 200 and sealing the OLED element.

[0125] A scanning driver 131, an emission driver 132, a protection circuit 133, and a driver IC (Integrated Circuit) 134 are arranged around the cathode electrode formation area 114 outside the display area 125 of the TFT substrate 110. These are connected to external devices via an FPC (Flexible Printed Circuit) 135.

[0126] The scanning driver 131 drives the scan lines of the TFT substrate 110. The emission driver 132 drives the emission control lines to control the light emission period of each subpixel. The driver IC 134 is mounted using, for example, an anisotropic conductive film (ACF).

[0127] The driver IC 134 supplies power and timing signals (control signals) to the scanning driver 131 and the emission driver 132, and also supplies data voltages corresponding to the video data to the data lines. In other words, the driver IC 134 has a display control function.

[0128] The sealing substrate 200 is a transparent insulating substrate, such as a glass substrate. A λ / 4 phase difference plate and a polarizing plate are arranged on the light-emitting surface (front surface) of the sealing substrate 200 to suppress the reflection of light incident from the outside.

[0129] Figure 26 is a plan view showing a part of the display area 125. Multiple subpixels are arranged in the display area 125. Figure 26 shows multiple subpixels arranged in a matrix in the display area 125. At least three subpixels are subpixels that emit different first to third colors. The first color is, for example, blue, the second color is, for example, red, and the third color is, for example, green. Figure 26 shows the red subpixel (emitting area) 251R, the blue subpixel (emitting area) 251B, and the green subpixel (emitting area) 251G. The cross-sectional view along line A1-A1 in Figure 26 may be the one shown in Figure 5 or the one shown in Figure 24. The subpixels that emit the first to third colors do not have to be arranged in the stripe pattern exemplified in Figure 24.

[0130] As shown in Figure 26, the entire area of ​​each subpixel (emitting region) is covered with an organic light-emitting layer of the same color. Specifically, the red subpixel 251R, blue subpixel 251B, and green subpixel 251G are completely covered with the red organic light-emitting layer 269R, the blue organic light-emitting layer 269B, and the green organic light-emitting layer 269G, respectively. Of the subpixels in Figure 26, only one subpixel each of red, blue, and green is indicated by a code. Each subpixel displays either red, blue, or green. A single pixel (major pixel) is composed of the red, blue, and green subpixels.

[0131] In this embodiment, each sub-pixel is composed of one of the organic light-emitting devices 1 to 3 described in the first to third embodiments. Therefore, the operation of the configuration described in any of the first to third embodiments can improve the luminescence efficiency.

[0132] (Fifth embodiment) As a fifth embodiment, an in-vehicle display 92 using the display device 90 according to the fourth embodiment will be described. Figure 27 is a schematic diagram showing an example configuration of the in-vehicle display 92 according to this embodiment and a vehicle 95 equipped with this in-vehicle display 92.

[0133] The in-vehicle display 92 is installed inside the vehicle 95 shown in Figure 27 and displays various information. The in-vehicle display 92 is, for example, the CID (Center Information Display) 301, cluster display 302, and side display 303 shown in Figure 27. In this embodiment, the CID 301, cluster display 302, and side display 303 can be configured using the display device 90.

[0134] The CID301 is located in the center of the vehicle's dashboard and displays information such as the audio, navigation system, and vehicle status management system. The cluster display 302 displays the speedometer, etc. The side displays 303 are located on the left and right sides of the dashboard and function as side mirrors by displaying camera images.

[0135] In the interior of a vehicle 95 equipped with these in-vehicle displays 92, the visibility of the screen may be reduced due to the effects of sunlight, etc. By using a display device 90 equipped with one of the organic light-emitting devices 1 to 3, the luminous efficiency of the in-vehicle display 92 can be improved. Therefore, the screen of the in-vehicle display 92, when illuminated by sunlight, can provide a good display with improved visibility.

[0136] The in-vehicle display 92 is not limited to the CID 301, cluster display 302, and side display 303, but may be any display installed in the vehicle. Furthermore, the display device 90 is not limited to being used as the in-vehicle display 92, but may be mounted on any industrial transport equipment.

[0137] (Sixth Embodiment) As a sixth embodiment, a smartphone 98 as an electronic device using the display device 90 according to the fourth embodiment will be described. Figure 28 is a perspective view showing an example of the configuration of a smartphone 98 as an electronic device. In the smartphone 98, the display device 90 according to the fourth embodiment is provided inside the housing 401, and the cover glass 402 is provided on the display surface side of the display device 90. In addition, the housing 401 is equipped with devices that have the functions required of a smartphone, such as a transmitter / receiver, various control devices, a storage device, an audio device including a speaker and microphone, and a battery.

[0138] Smartphone 98 may be used in bright environments, such as outdoors. By using the display device 90, Smartphone 98 can achieve improved luminous efficiency. Therefore, the screen of Smartphone 98 in bright environments can provide a good display with enhanced visibility.

[0139] The display device 90 is not limited to those used in the smartphone 98 as an electronic device. For example, the display device 90 may be used in personal computers, PDAs (Personal Digital Assistance), tablet devices, head-mounted displays, projectors, digital (video) cameras, etc.

[0140] Although embodiments have been described above, various modifications are possible without departing from the gist of this disclosure. For example, the sealing structure using the sealing layer 51 shown in Figures 8(A) and 8(B), or the sealing structure using the sealing substrate 200 and the bonding portion 300 shown in Figure 25, can be adapted to various structures depending on the characteristics of the device.

[0141] Figures 29(A) to 29(C) are cross-sectional views illustrating the sealing structures of the organic light-emitting devices according to each embodiment described above. Figure 29(A) shows a first sealing structure SE01 using two glass substrates. Figure 29(B) shows a second sealing structure SE02 using one glass substrate and TFE (Thin Film Encapsulation). Figure 29(C) shows a third sealing structure SE03 using polyimide (PI) and TFE.

[0142] The first sealing structure SE01 seals the organic light-emitting device 210 and the TFT substrate 211 as a circuit board with a first glass substrate 212, a second glass substrate 213, and glass frit 214. The first glass substrate 212 has a thickness of, for example, 0.2 to 0.25 mm. The second glass substrate 213 has a thickness of, for example, 0.4 to 0.5 mm. The glass frit 214 is provided between the first glass substrate 212 and the second glass substrate 213, bonding the first glass substrate 212 and the second glass substrate 213 and sealing the organic light-emitting device 210 and the TFT substrate 211. While the first sealing structure SE01 is less susceptible to external environmental influences such as moisture and can achieve the best color reproduction, it has the problem of being thick and heavy.

[0143] The second sealing structure SE02 seals the organic light-emitting device 210 and the TFT substrate 211 with a glass substrate 215 and a TFE layer 216. The glass substrate 215 has a thickness of, for example, 0.4 to 0.5 mm. The TFE layer 216 has a thickness of, for example, 20 μm. The TFE layer 216 covers the top of the organic light-emitting device 210 and the TFT substrate 211 and seals the organic light-emitting device 210 and the TFT substrate 211 by bonding them with the glass substrate 215 at their edges. The second sealing structure SE02 has better characteristics than the first sealing structure SE01 in terms of thickness, form factor, safety, and weight. Furthermore, the second sealing structure SE02 has the best functional integration.

[0144] The third sealing structure SE03 seals the organic light-emitting device 210 and the TFT substrate 211 with a polyimide layer 217 and a TFE layer 218. The polyimide layer 217 has a thickness of, for example, 20 μm. The TFE layer 218 has a thickness of, for example, 20 μm. The TFE layer 218 covers the top of the organic light-emitting device 210 and the TFT substrate 211 and seals the organic light-emitting device 210 and the TFT substrate 211 by bonding them with the polyimide layer 217 at their edges. The third sealing structure SE03 has better characteristics in terms of weight than the first sealing structure SE02 and the second sealing structure SE03. Furthermore, the third sealing structure SE03 has the best characteristics in terms of thickness, form factor, safety, and functional integration.

[0145] This disclosure allows for various embodiments and modifications without departing from the broad spirit and scope of this disclosure. Furthermore, the embodiments and examples described above are for illustrative purposes only and do not limit the scope of this disclosure. That is, the scope of this disclosure is indicated by the claims, not by the embodiments and examples. Various modifications made within the scope of the claims and the equivalent significance of the disclosure are considered to be within the scope of this disclosure. [Explanation of symbols]

[0146] 1-3, 210, 501 Organic light-emitting devices 1R, 3R Red Light Emitting Device 1G, 3R Green Light Emitting Device 1B, 3B Blue light emitting device 10, 510 Circuit Board 11, 11A, 511 Anode electrodes 12, 512 Cathode electrodes 13. Capping layer 20, 20A, 20R, 20G, 20B Light-emitting structure 21 Hole injection layer 22 Hole transport layer 23 Electron Block Layer 24, 513, 513A, 513B Light-emitting layer 25 Hole block layer 26 Electron transport layer 27 Electron injection layer 30, 30R, 30G, 30B Interference Reflection Section 31 p-type low refractive index layer 32 n-type high refractive index layer 33 n-type low refractive index layer 34 p-type high refractive index layer 41 TFT for driving 42, 42A Pixel Definition Layer 50 Light extraction layer 50A High refractive index region 50B Low refractive index region 51 Sealing layer 52 Polarizing plates 53 Color Filters 54 Black Matrix 55 Anti-reflection layer 60 microlens array 61 Smoothing layer 62 Overcoat layer 90 Display device 92 In-car displays 95 vehicles 98 Smartphones 101R, 103R Red light-emitting pixels 101G, 103G Green Emitting Pixels 101B, 103B Blue light-emitting pixels 110, 211 TFT substrates 114 Cathode electrode formation region 125 Display area 131 Scanning Driver 132 Emission Driver 133 Protection circuit 134 Driver ICs 135 FPC 141 Power supply line 142 scan lines 143 data lines 144 Emission Control Line 145 Reference voltage supply line 146 Reset control line 200 Sealing substrate 212 First glass substrate 213 Second glass substrate 214 Glass frit 215 Glass substrate 216, 218 TFE layer 217 Polyimide layer 251R Red subpixel 251G Green subpixel 251B Blue subpixel 269R Red Organic Emitting Layer 269B Blue organic light-emitting layer 269G Green Organic Emitting Layer 300 joint 301 CID 302 Cluster Display 303 Side Display 401 cabinet 402 Cover glass AN Anode CA Cathode Cs01 holding capacity E1 Light-emitting element GA1, GA2 slope section GB1, GB2 top part Tr01~Tr04 Transistors RX01, RX02 Pixel Circuit VDATA Data Voltage VDD drive voltage VEE (Cathode Voltage) VREF Reference Voltage

Claims

1. A first electrode and a second electrode are provided opposite each other, The first electrode and the second electrode are provided with an organic compound layer having at least a light-emitting layer and an interference-reflecting portion, The aforementioned interference reflection section is Multiple first charge generation layers having a first conductivity type and a first refractive index and multiple second charge generation layers having a second conductivity type and a second refractive index are alternately stacked. Formed in contact with either the first electrode or the second electrode, Organic light-emitting device.

2. The first charge generation layer is a first organic material layer exhibiting electron-accepting properties, obtained by doping a charge transport material with a first conductive impurity. The second charge generation layer is a second organic material layer exhibiting electron-donating properties, which is doped with a second conductive impurity to the charge transport material. The organic light-emitting apparatus according to claim 1.

3. The first electrode and the second electrode are provided with a hole injection layer, a hole transport layer, an electron injection layer, and an electron transport layer, The interference reflection portion is formed at a position different from the hole injection layer, the hole transport layer, the electron injection layer, and the electron transport layer. The organic light-emitting apparatus according to claim 1.

4. The interference reflection portion is formed in contact with the hole injection layer or the electron injection layer, The organic light-emitting apparatus according to claim 3.

5. The aforementioned light-emitting layer is A first light-emitting layer formed in the first region and exhibiting a visible light spectrum of the first color, A second light-emitting layer formed in the second region, which exhibits a visible light spectrum of a second color having a different emission wavelength from the first color, A third light-emitting layer is formed in the third region and exhibits a visible light spectrum of a third color having an emission wavelength different from that of the first and second colors, The aforementioned interference reflection section is A first interference reflection portion for the visible light spectrum of the first color is formed in the first region in contact with the first electrode or the second electrode, A second interference reflection portion for the visible light spectrum of the second color is formed in the second region in contact with the first electrode or the second electrode, A third interference reflection portion for the visible light spectrum of the third color is formed in the third region in contact with the first electrode or the second electrode. The organic light-emitting apparatus according to claim 1.

6. The aforementioned light-emitting layer is A first light-emitting layer formed in the first region and exhibiting a visible light spectrum of the first color, A second light-emitting layer formed in the second region, which exhibits a visible light spectrum of a second color having a different emission wavelength from the first color, A third light-emitting layer is formed in the third region and exhibits a visible light spectrum of a third color having an emission wavelength different from that of the first and second colors, The aforementioned interference reflection section is A first interference reflection portion for the visible light spectrum of the first color is formed in contact with the first electrode or the second electrode, A second interference reflection portion for the visible light spectrum of the second color is formed in contact with the first interference reflection portion. A third interference reflection portion is formed in contact with the second interference reflection portion for the visible light spectrum of the third color. The organic light-emitting apparatus according to claim 1.

7. The device comprises a light extraction layer formed on the outside of the first electrode and the second electrode, The aforementioned light extraction layer is A high refractive index region that overlaps with the light-emitting layer in a direction perpendicular to the plane of the light-emitting layer, A low refractive index region that does not overlap with the light-emitting layer in a direction perpendicular to the plane of the light-emitting layer, The low refractive index region has a curved thickness that is parallel to the plane of the light-emitting layer and gradually decreases in the direction from farther away from the light-emitting layer towards the nearer layer. The organic light-emitting apparatus according to claim 1.

8. The first electrode, the second electrode, the light-emitting layer, and the interference reflection portion are formed as a microlens array having a maximum portion, a slanted portion, and a minimum portion. The organic light-emitting apparatus according to claim 1.

9. A portion or all of the aforementioned organic compound layer is positioned above the inclined portion of the pixel definition layer. The interference reflection portion is formed in contact with the inclined portion of the pixel definition layer, The organic light-emitting apparatus according to claim 1.

10. A display device comprising an organic light-emitting device according to any one of claims 1 to 9.

11. An in-vehicle display comprising the display device described in claim 10.

12. An electronic device comprising the display device described in claim 10.

13. A vehicle equipped with the in-vehicle display according to claim 11.

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