Method for controlling light extraction characteristics of organic electroluminescent element, organic electroluminescent element, and display device

Abstract

According to the present invention, the light extraction characteristics of an organic electroluminescent element, which comprises a hole injection part, an electron injection part, and a light-emitting layer, and in which light generated in the light-emitting layer propagates in the lateral direction of the light-emitting layer and is extracted from a light extraction surface, are controlled by providing a recombination concentration part along the lateral direction of the light-emitting layer. Here, the control of the light extraction characteristics is the control of at least one among: the polarization state of the light generated in the light-emitting layer; the light intensity distribution in the lateral direction and the propagation direction from the lateral direction of the light extracted from the light extraction surface; and an optical crosstalk and an electrical crosstalk of the organic electroluminescent element.

Description

Method for controlling light extraction characteristics of organic electroluminescence element, organic electroluminescence element, and display device

[0001] The present invention relates to a method for controlling the light extraction characteristics of an organic electroluminescent element, an organic electroluminescent element having controlled light extraction characteristics, and a display device having pixels formed of the organic electroluminescent element.

[0002] Organic electroluminescence elements (organic EL elements) have been used, for example, as organic solid-state semiconductor lasers. Compared to inorganic semiconductor lasers, organic solid-state semiconductor lasers have a wider wavelength tunability, are easier to provide flexibility, and can be manufactured at low cost. Therefore, they are expected to be applied to various fields, such as laser light sources that oscillate at a specific wavelength, as well as display devices having multiple pixels with different emission wavelengths. Research and development is actively underway toward practical application. For example, Patent Document 1 describes the fabrication of an organic solid-state semiconductor laser using BSBCz (4-4'-bis[(N-carbazole)styryl]biphenyl) as a laser oscillation material, and the confirmation of laser oscillation. As shown in FIG. 13 , the organic solid-state semiconductor laser fabricated here comprises an ITO cathode 101, a light-emitting layer 102 containing BSBCz, and a MoO ３ The anode 103 is formed by laminating a layer / Ag layer / Al layer, and the light-emitting layer 102 is formed to a thickness of 210 nm.

[0003] WO2018 / 147470

[0004] Organic electroluminescent elements and organic solid-state semiconductor lasers are expected to be applied to displays with pixel densities of 5,000 ppi or more and pixel pitches of 5 μm or less, for example, for AR (Augmented Reality) glasses and VR (Virtual Reality) glasses. In such displays, crosstalk between pixels can occur. Furthermore, increasing brightness is difficult. Therefore, precise control of light extraction characteristics, such as the light intensity distribution and light propagation direction at each pixel and crosstalk between pixels, is important. Furthermore, in organic EL display devices, optical components such as polarizers and retardation films are typically placed on the light extraction surface to prevent contrast degradation due to the incidence and reflection of external light. Therefore, it is desirable to control the polarization of light emitted from organic electroluminescent elements so that it can be efficiently extracted through these optical components. However, to date, no effective method for controlling these light extraction characteristics has been found. Therefore, in order to solve these problems of the prior art, the inventors conducted research with the aim of providing an organic electroluminescent element with improved light extraction characteristics.

[0005] As a result of intensive research to solve the above-mentioned problems, the inventors have found a configuration that effectively improves at least one of the polarization state of light generated in the light-emitting layer of an organic electroluminescent element, the lateral light intensity distribution and propagation direction of light extracted from the light extraction surface, and crosstalk between adjacent elements. The present invention has been proposed based on this finding and specifically has the following configuration: [1] A method for controlling the light extraction characteristics of an organic electroluminescent element comprising: a hole injection section that injects holes; an electron injection section that injects electrons; and a light-emitting layer that recombines holes and electrons to emit light, wherein light generated in the light-emitting layer propagates in the lateral direction of the light-emitting layer and is emitted from the light extraction surface, the method comprising providing a recombination concentration section along the lateral direction of the light-emitting layer.

[0006] Here, the recombination concentration region is a region where the recombination of holes and electrons occurs intensively, resulting in a high exciton density (exciton high density region). The position of the recombination concentration region can be determined, for example, by simulating the exciton density distribution.

[0007] [2] The method according to [1], wherein the light extraction characteristics are controlled by controlling at least one of the polarization state of light generated in the light-emitting layer, the lateral light intensity distribution and the direction of propagation of light extracted from the light extraction surface, and optical crosstalk and electrical crosstalk of the organic electroluminescent element. [3] The method according to [2], wherein the light intensity distribution in the depth direction is controlled in addition to the lateral direction when controlling the lateral light intensity distribution of the light. [4] The method according to [2] or [3], wherein at least one of the polarization state of light generated in the light-emitting layer, the lateral light intensity distribution and the direction of propagation of light extracted from the light extraction surface, and optical crosstalk and electrical crosstalk of the organic electroluminescent element is controlled, and the full width at half maximum (FWHM) of the peak of the light intensity distribution relative to the wavelength of the light extracted from the light extraction surface is reduced. In this specification, the "light intensity distribution relative to the wavelength of light" may be referred to as the "emission spectrum." [5] The method according to any one of [1] to [4], wherein the light extraction characteristics are controlled by providing a control member made of an insulating material having a lower refractive index than the light-emitting layer in contact with the light-emitting layer. [6] The method according to any one of [2] to [5], wherein the control of the light extraction characteristics is control of the polarization state of light generated in the light-emitting layer. [7] The method according to [6], wherein the control of the polarization state of light generated in the light-emitting layer is control of a striped diffraction grating in contact with the light-emitting layer. [8] The method according to any one of [2] to [7], wherein the control of the light extraction characteristics is control of at least one of the lateral light intensity distribution and the propagation direction from the lateral direction of light extracted from the light extraction surface, and optical crosstalk and electrical crosstalk of the organic electroluminescent element.[9] The method according to [8], wherein at least one control member selected from a striped diffraction grating, a circular diffraction grating, a partition made of an insulating material having a refractive index lower than that of the light-emitting layer, and a photonic crystal material is provided in contact with the light-emitting layer to control at least one of the lateral light intensity distribution and the lateral propagation direction of light extracted from the light extraction surface, and optical crosstalk and electrical crosstalk of the organic electroluminescent element.

[10] The method according to any one of [1] to [9], wherein when the side of the light-emitting layer that becomes the exciton high-density region is the electron injection section side, a hole blocking layer is provided between the light-emitting layer and the electron injection section and adjacent to the light-emitting layer, and when the side of the light-emitting layer that becomes the exciton high-density region is the hole injection section side, an electron blocking layer is provided between the light-emitting layer and the hole injection section and adjacent to the light-emitting layer.

[11] The method according to any one of [1] to

[10] , wherein a low-refractive index layer having a refractive index lower than that of the light-emitting layer is provided between the light-emitting layer and the hole injection section and between the light-emitting layer and the electron injection section.

[12] The method according to any one of [1] to

[11] , wherein the position of the exciton high-density region of the light-emitting layer is determined by simulating the exciton density distribution in the light-emitting layer.

[13] The method according to any one of [8] to

[12] , wherein the side of the light-emitting layer that becomes the exciton high-density region is the electron injection section side, and a hole blocking layer is provided between the light-emitting layer and the electron injection section and adjacent to the light-emitting layer.

[14] The method according to

[13] , wherein the absolute value of the HOMO energy of the hole blocking layer is made larger (e.g., 0.1 eV or more, e.g., 0.2 eV or more, e.g., 0.4 eV or more) than the absolute value of the HOMO energy of the light-emitting layer.

[15] The method according to

[13] or

[14] , wherein the hole mobility of the hole blocking layer is reduced.

[16] The method according to any one of

[13] to

[15] , wherein one or more layers (e.g., an electron transport layer) are provided between the hole blocking layer and the electron injection part.

[17] The method according to

[16] , wherein the electron mobility of the electron transport layer is reduced.

[18] The method according to

[16] or

[17] , characterized in that the absolute value of the HOMO energy of the electron transport layer is made larger by 0.1 eV or more (e.g., larger by 0.2 eV or more) than the absolute value of the HOMO energy of the light-emitting layer.

[19] The method according to any one of

[13] to

[18] , characterized in that the total thickness of the layers between the light-emitting layer and the electron injection section is increased.

[20] The method according to any one of

[13] to

[19] , characterized in that the total thickness of one or more layers between the light-emitting layer and the electron injection section is made larger by two or more times (e.g., 2.5 or more times, e.g., 3 or more times) the total thickness of one or more layers between the light-emitting layer and the hole injection section.

[21] The method according to any one of

[13] to

[20] , characterized in that the refractive index of the layer between the light-emitting layer and the electron injection section is reduced.

[22] The method according to any one of

[13] to

[21] , characterized in that the refractive index of the light-emitting layer is increased.

[23] The method according to any one of

[13] to

[22] , characterized in that the hole mobility of the light-emitting layer is increased.

[24] The method according to any one of

[13] to

[23] , characterized in that the light-emitting layer is thinned.

[25] The method according to any one of

[13] to

[24] , characterized in that the hole mobility of a layer between the hole injection section and the light-emitting layer is increased.

[26] The method according to any one of

[10] to

[12] , wherein the side of the light-emitting layer that becomes the exciton high density region is the hole injection section side, and an electron blocking layer is provided between the light-emitting layer and the hole injection section and adjacent to the light-emitting layer.

[27] The method according to

[26] , characterized in that the absolute value of the LUMO energy of the electron blocking layer is smaller by 0.1 eV or more (e.g., 0.2 eV or more, e.g., 0.4 eV or more) than the absolute value of the HOMO energy of the light-emitting layer.

[28] The method according to

[26] or

[27] , characterized in that the electron mobility of the electron blocking layer is reduced.

[29] The method according to any one of

[26] to

[28] , wherein a hole transport layer is provided between the electron blocking layer and the hole injection part.

[30] The method according to any one of

[26] to

[29] , wherein the hole mobility of the hole transport layer is reduced.

[31] The method according to any one of

[26] to

[30] , characterized in that the absolute value of the LUMO energy of the hole transport layer is made smaller by 0.1 eV or more (e.g., smaller by 0.2 eV or more) than the absolute value of the LUMO energy of the light-emitting layer.

[32] The method according to any one of

[26] to

[31] , characterized in that the total thickness of the layers between the light-emitting layer and the hole injection section is increased.

[33] The method according to any one of

[26] to

[32] , characterized in that the total thickness of one or more layers between the light-emitting layer and the hole injection section is made larger by two or more times (e.g., 2.5 or more times, e.g., 3 or more times) the total thickness of one or more layers between the light-emitting layer and the electron injection section.

[34] The method according to any one of

[26] to

[33] , characterized in that the refractive index of the layer between the light-emitting layer and the hole injection section is reduced.

[35] The method according to any one of

[26] to

[34] , characterized in that the refractive index of the light-emitting layer is increased.

[36] The method according to any one of

[26] to

[35] , characterized in that the electron mobility of the light-emitting layer is increased.

[37] The method according to any one of

[26] to

[36] , characterized in that the light-emitting layer is thinned.

[38] The method according to any one of

[26] to

[37] , characterized in that the electron mobility of a layer between the electron injection section and the light-emitting layer is increased.

[39] The method according to any one of [1] to

[38] , characterized in that the full width at half maximum (FWHM) of the emission wavelength peak is 10 nm or less (e.g., 7 nm or less, e.g., 5 nm or less, e.g., 4 nm or less, e.g., 3 nm or less, e.g., 2 nm or less, e.g., 1 nm or less).

[40] The method according to any one of [1] to

[39] , wherein the electron injection section has a structure in which a dielectric, a metal, and a dielectric are sequentially stacked (DMD structure).

[41] The method according to any one of [1] to

[40] , characterized in that it is a method for designing an organic electroluminescence device.

[42] The method according to any one of [1] to

[41] , wherein the organic electroluminescent element further comprises an optical resonator that propagates emitted light within a light-emitting layer, and the organic electroluminescent element oscillates laser light.However, when the organic electroluminescence element has the striped diffraction grating or the circular diffraction grating, the diffraction grating may function both as a light extraction characteristic control member and as an optical resonator. [42-2] The method according to

[42] , wherein the light extracted from the light extraction surface is laser light.

[43] The method according to [42-2], wherein the optical resonator has a diffraction grating.

[44] The method according to

[43] , wherein the hole blocking layer or the electron blocking layer is formed along a flat interface of the light-emitting layer.

[45] The method according to

[43] or

[44] , wherein the diffraction grating is disposed between the exciton high density region and the hole injection part, or between the exciton high density region and the electron injection part.

[46] The method according to

[45] , wherein when a diffraction grating is provided between the exciton high density region and the hole injection section, the hole blocking layer is provided between the light-emitting layer and the electron injection section and adjacent to the light-emitting layer; and when a diffraction grating is provided between the exciton high density region and the electron injection section, the electron blocking layer is provided between the light-emitting layer and the hole injection section and adjacent to the light-emitting layer.

[47] The method according to any one of

[42] to

[46] , characterized in that it is a method for designing an organic solid-state semiconductor laser.

[48] A device having an organic electroluminescence element with controlled light extraction characteristics, manufactured by carrying out the method according to any one of [1] to

[47] .

[49] A method for manufacturing a device having an organic electroluminescence element with controlled light extraction characteristics, comprising a step of manufacturing an organic electroluminescence element by the method according to any one of [1] to

[47] .

[50] An organic electroluminescence element with controlled light extraction characteristics, manufactured by carrying out the method according to any one of [1] to

[47] .

[51] An organic solid-state semiconductor laser having controlled light extraction characteristics, produced by carrying out the method according to any one of

[42] to

[47] .

[52] An organic electroluminescence element comprising: a hole injection section for injecting holes; an electron injection section for injecting electrons; a light-emitting layer disposed between the hole injection section and the electron injection section and configured to recombine holes and electrons to emit light; and an optical resonator for propagating the emitted light within the light-emitting layer, wherein light is extracted from a light extraction surface, the organic electroluminescence element further comprising: a hole blocking layer adjacent to the light-emitting layer on the electron injection section side of the light-emitting layer; or an electron blocking layer adjacent to the light-emitting layer on the hole injection section side of the light-emitting layer; and a control member for controlling light extraction characteristics at the light extraction surface.

[53] The organic electroluminescence element according to

[52] , wherein the control of the light extraction characteristics is control of at least one of the polarization state of light generated in the light-emitting layer, the lateral light intensity distribution and the lateral propagation direction of light extracted from the light extraction surface, and optical crosstalk and electrical crosstalk of the organic electroluminescence element.

[54] The organic electroluminescent element according to

[52] or

[53] , wherein the control member is made of an insulating material having a lower refractive index than the light-emitting layer and is provided in contact with the light-emitting layer.

[55] The organic electroluminescent element according to any one of

[52] to

[54] , wherein the control member has a striped diffraction grating or a circular diffraction grating, and the striped diffraction grating and the circular diffraction grating also function as the optical resonator.

[56] The organic electroluminescent element according to any one of

[52] to

[55] , wherein the control member has a striped diffraction grating, and the diffraction grating has ridges arranged side by side in the lateral direction of the light-emitting layer.

[57] The organic electroluminescent element according to

[56] , wherein the striped diffraction grating is a first-order diffraction grating.

[58] The organic electroluminescent element according to

[56] , wherein the striped diffraction grating includes a second-order diffraction grating.

[59] The organic electroluminescent element according to

[58] , wherein the striped diffraction grating is a second-order diffraction grating.

[60] The organic electroluminescent element according to any one of

[52] to

[55] , having a circular diffraction grating including a second-order diffraction grating as the control member.

[61] The organic electroluminescent element according to

[60] , wherein the circular diffraction grating is a second-order diffraction grating.

[62] The organic electroluminescent element according to

[60] , wherein the circular diffraction grating is a mixed diffraction grating including a first-order diffraction grating and a second-order diffraction grating.

[63] The organic electroluminescent element according to any one of

[52] to

[52] , wherein the control member includes a partition wall surrounding the end face of the light-emitting layer, the partition wall being made of an insulating material having a refractive index lower than that of the light-emitting layer.

[64] The organic electroluminescent element according to any one of

[52] to

[62] , wherein the control member includes a photonic crystal material surrounding the light-emitting layer.

[65] The organic electroluminescent element according to any one of

[52] to

[64] , wherein the control member includes a hole-blocking layer adjacent to the light-emitting layer on the electron injection section side of the light-emitting layer.

[66] The organic electroluminescent device according to

[65] , wherein the absolute value of the HOMO (Highest Occupied Molecular Orbital) energy of the hole blocking layer is 0.1 eV or more greater than the absolute value of the HOMO energy of the light-emitting layer.

[67] The organic electroluminescent device according to

[65] , wherein the absolute value of the HOMO energy of the hole blocking layer is 0.2 eV or more greater than the absolute value of the HOMO energy of the light-emitting layer.

[68] The organic electroluminescent device according to

[65] , wherein the absolute value of the HOMO energy of the hole blocking layer is 0.4 eV or more greater than the absolute value of the HOMO energy of the light-emitting layer.

[69] The organic electroluminescent device according to any one of

[65] to

[68] , wherein the hole blocking layer is made of a material having low hole mobility.

[70] The organic electroluminescence device according to any one of

[65] to

[68] , wherein the hole blocking layer is made of a material having a hole mobility equal to or less than that of TPBi ([1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene]) (for example, equal to or less than that of T2T (2,4,6-tris([1,1'-biphenyl]-3-yl))-1,3,5-triazine)).

[71] The organic electroluminescence device according to any one of

[65] to

[70] , wherein the hole blocking layer has a thickness of 1 nm or more (for example, 3 nm or more, for example, 5 nm or more, for example, 8 nm or more, and for example, 80 nm or less, for example, 30 nm or less, for example, 15 nm or less).

[72] The organic electroluminescence device according to any one of

[65] to

[71] , further comprising an electron transport layer between the hole blocking layer and the electron injection part.

[73] The organic electroluminescence device according to

[72] , wherein the thickness of the electron transport layer is 10 nm or more (e.g., 20 nm or more, e.g., 40 nm or more, e.g., 60 nm or more, and e.g., 100 nm or less, e.g., 80 nm or less).

[74] The organic electroluminescence device according to

[72] or

[73] , wherein the electron transport layer is made of a material having an electron mobility equal to or less than that of TPBi ([1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene]).

[75] The organic electroluminescence device according to any one of

[72] to

[74] , wherein the absolute value of the HOMO energy of the electron transport layer is 0.1 eV or more (e.g., 0.2 eV or more) greater than the absolute value of the HOMO energy of the light-emitting layer.

[76] The organic electroluminescence element according to any one of

[65] to

[75] , wherein the total thickness of the one or more layers provided between the light-emitting layer and the electron injection part is at least twice (e.g., at least 2.5 times, e.g., at least 3 times) larger than the total thickness of the one or more layers provided between the light-emitting layer and the hole injection part.

[77] The organic electroluminescence device according to any one of

[65] to

[76] , characterized in that the light-emitting layer is composed of a material having a hole mobility equal to or greater than that of BSBCz (4-4'-bis[(N-carbazole)styryl]biphenyl).

[78] The organic electroluminescence device according to any one of

[65] to

[77] , characterized in that the light-emitting layer contains a laser oscillation material and a dopant material.

[79] The organic electroluminescence device according to

[78] , characterized in that the dopant material contains a light-emitting material.

[80] The organic electroluminescence device according to

[79] , characterized in that the light-emitting material is a compound selected from the group consisting of fluorene-based molecules, styrylbenzene-based molecules, carbazole-styrylbiphenyl compounds, TADF materials (thermally activated delayed fluorescence materials), star polymers, polyfluorenes, phenylene vinylene polymers, and ladder polymers.

[81] The organic electroluminescence device according to any one of

[78] to

[80] , wherein the dopant material contains a triplet quencher.

[82] The organic electroluminescence device according to

[81] , wherein the triplet quencher is a compound containing an anthracene ring.

[83] The organic electroluminescence device according to

[82] , wherein the compound containing an anthracene ring is the following compound:

[84] The organic electroluminescence device according to any one of

[65] to

[83] , characterized in that a layer composed of a material having a hole mobility equal to or greater than that of HATCN ([dipyrazino[2,3-f:2',3'-h]quinoxaline-2,3,6,7,10,11-hexacarbonitrile]) is disposed between the hole injection part and the light-emitting layer.

[85] The organic electroluminescence device according to any one of

[52] to

[64] , characterized in that an electron blocking layer is disposed adjacent to the light-emitting layer on the hole injection part side of the light-emitting layer.

[86] The organic electroluminescence device according to

[85] , characterized in that the absolute value of the energy of the lowest unoccupied molecular orbital (LUMO) of the electron blocking layer is smaller by 0.1 eV or more than the absolute value of the energy of the LUMO of the light-emitting layer.

[87] The organic electroluminescent device according to

[80] , wherein the absolute value of the LUMO energy of the electron blocking layer is smaller by 0.2 eV or more than the absolute value of the LUMO energy of the light-emitting layer.

[88] The organic electroluminescent device according to

[85] , wherein the absolute value of the LUMO energy of the electron blocking layer is smaller by 0.4 eV or more than the absolute value of the LUMO energy of the light-emitting layer.

[89] The organic electroluminescent device according to any one of

[85] to

[88] , wherein the electron blocking layer is made of a material having low electron mobility.

[90] The organic electroluminescent device according to any one of

[85] to

[89] , wherein the electron blocking layer is made of a material having low electron mobility.

[91] The organic electroluminescence device according to any one of

[85] to

[90] , wherein the thickness of the electron blocking layer is 1 nm or more (for example, 3 nm or more, for example, 5 nm or more, for example, 8 nm or more, and for example, 80 nm or less, for example, 30 nm or less, for example, 15 nm or less).

[92] The organic electroluminescence device according to any one of

[85] to

[91] , further comprising a hole transport layer between the electron blocking layer and the hole injection part.

[93] The organic electroluminescence device according to

[92] , wherein the thickness of the hole transport layer is 10 nm or more (e.g., 20 nm or more, e.g., 40 nm or more, e.g., 60 nm or more, and e.g., 100 nm or less, e.g., 80 nm or less).

[94] The organic electroluminescence device according to

[92] or

[93] , wherein the hole transport layer is made of a material having a hole mobility equal to or less than that of HATCN ([dipyrazino[2,3-f:2',3'-h]quinoxaline-2,3,6,7,10,11-hexacarbonitrile]).

[95] The organic electroluminescence device according to any one of

[92] to

[94] , wherein the absolute value of the LUMO energy of the hole transport layer is smaller by 0.1 eV or more (e.g., smaller by 0.2 eV or more) than the absolute value of the LUMO energy of the light-emitting layer.

[96] The organic electroluminescent device according to any one of

[84] to

[95] , wherein the total thickness of one or more layers provided between the light-emitting layer and the hole injection section is at least twice (e.g., at least 2.5 times, e.g., at least 3 times) greater than the total thickness of one or more layers provided between the light-emitting layer and the electron injection section.

[97] The organic electroluminescent device according to any one of

[52] to

[96] , wherein the refractive index of the layer provided between the light-emitting layer and the electron injection section is smaller than the refractive index of the light-emitting layer.

[98] The organic electroluminescent device according to any one of

[52] to

[97] , wherein the refractive index of the layer provided between the light-emitting layer and the hole injection section is smaller than the refractive index of the light-emitting layer.

[99] The organic electroluminescent device according to any one of

[51] to

[98] , wherein the thickness of the light-emitting layer is 10 nm or more and less than 200 nm.

[100] The organic electroluminescent element according to any one of

[51] to

[99] , wherein the hole mobility of the light-emitting layer is 10 times or more larger than the electron mobility.

[101] The organic electroluminescent element according to any one of

[51] to

[100] , wherein the light-emitting layer is composed of only a light-emitting material.

[102] The organic electroluminescent device according to any one of

[51] to

[101] , wherein the light-emitting layer is a layer in which a light-emitting material is doped into a host material.

[103] The organic electroluminescent device according to any one of

[51] to

[102] , wherein the hole injection part is an electrode.

[104] The organic electroluminescent device according to any one of

[51] to

[103] , wherein at least one of the electron injection part and the hole injection part is an electrode having a visible light transmittance of 10% or more (e.g., 50% or more, e.g., 80% or more, e.g., 90% or more).

[105] The organic electroluminescent device according to any one of

[51] to

[104] , wherein the hole injection part is made of ITO (indium tin oxide).

[106] The organic electroluminescent device according to any one of

[51] to

[105] , wherein the electron injection part is an electrode.

[107] The organic electroluminescent device according to any one of

[51] to

[106] , wherein the electron injection part is a metal electrode.

[108] The organic electroluminescent device according to any one of

[51] to

[107] , wherein the electron injection part has a structure in which a dielectric, a metal and a dielectric are laminated in this order.

[109] The organic electroluminescent device according to

[108] , wherein the metal is silver (Ag).

[110] The dielectric is molybdenum trioxide (MoO. ３The organic electroluminescent device according to

[108] or

[104] , characterized in that the organic electroluminescent device is a surface-emitting type.

[111] The organic electroluminescent device according to any one of

[52] to

[110] , characterized in that the organic electroluminescent device is a surface-emitting type.

[112] The organic electroluminescent device according to any one of

[52] to

[107] , wherein light generated in the light-emitting layer propagates laterally across the light-emitting layer.

[113] The method according to

[112] , wherein low-refractive index layers having a refractive index lower than that of the light-emitting layer are provided between the light-emitting layer and the hole injection section, and between the light-emitting layer and the electron injection section.

[114] The organic electroluminescent device according to

[52] to

[113] , wherein the organic electroluminescent device is an organic solid-state semiconductor laser, and preferably the optical resonator has a diffraction grating.

[115] The organic electroluminescent device according to

[114] , wherein the hole blocking layer or the electron blocking layer is formed along a flat interface of the light-emitting layer.

[116] The organic electroluminescent device according to

[114] or

[115] , wherein a base end of the diffraction grating is disposed at the interface of the light-emitting layer on the hole injection section side or closer to the hole injection section than the interface, and the hole blocking layer is disposed between the light-emitting layer and the electron injection section and adjacent to the light-emitting layer.

[117] The organic electroluminescent device according to

[114] or

[115] , wherein a base end of the diffraction grating is disposed at the interface of the light-emitting layer on the electron injection section side or closer to the electron injection section than the interface, and the electron blocking layer is disposed between the light-emitting layer and the hole injection section and adjacent to the light-emitting layer.

[118] The organic electroluminescent device according to any one of

[52] to

[111] and

[114] to

[117] , wherein the organic electroluminescent device is a top-emission type.

[119] The organic electroluminescence element according to any one of

[52] to

[111] and

[114] to

[118] , which is a bottom-emission type.

[120] The organic electroluminescence element according to any one of

[52] to

[111] and

[114] to

[119] , which is a dual-emission type.

[121] The organic electroluminescent element according to any one of

[52] to

[117] , characterized in that it is an edge-emitting type.

[122] A display device having a plurality of pixels, wherein the plurality of pixels are organic electroluminescent elements whose light extraction characteristics have been controlled by the method according to any one of [1] to

[47] , or the organic electroluminescent element according to any one of

[51] to

[121] .

[123] A program for carrying out the method according to any one of [1] to

[47] .

[0008] The above-mentioned "DMD structure" is an abbreviation of dielectric-metal-dielectric structure. It can be adopted in the present invention as an electrode that utilizes interference of a laminated structure. As the DMD structure, MoO ３ / Ag / MoO3, ITO / Ag / ITO, ZnS / Ag / ZnS, ZnO / Ag / ZnO, InZnSnO / Ag / InZnSnO, ITO / Ag / WO ３ , ZnO / Ag / WO ３ , W.O. ３ / Ag / WO ３ In one embodiment of the present invention, a DMD structure is employed as the electron injection portion. An element having the DMD structure can be manufactured, for example, through a process of forming the DMD structure on a silicon substrate.

[0009] By forming the electron injection section from a material with high light transmittance, a top-emission organic electroluminescence element or an organic solid-state semiconductor laser can be provided. In one embodiment of the present invention, the electron injection section is a DMD structure with high light transmittance or a thin Ag layer (for example, a thickness of 40 nm or less, for example, 5 to 30 nm, for example, 12 to 25 nm). Furthermore, by forming the hole injection section from a material with high light transmittance, a bottom-emission organic electroluminescence element or an organic solid-state semiconductor laser can be provided. In one embodiment of the present invention, the hole injection section is an ITO layer. Furthermore, by forming both the electron injection section and the hole injection section from a material with high light transmittance, a dual-emission (see-through) organic electroluminescence element or an organic solid-state semiconductor laser can also be provided.

[0010] According to the present invention, it is possible to realize an organic electroluminescent element in which at least one of the polarization state of light generated in the light-emitting layer, the lateral light intensity distribution and lateral propagation direction of light extracted from the light extraction surface, and the optical crosstalk and electrical crosstalk of the organic electroluminescent element are improved.

[0011] 1 is a perspective view showing a circular diffraction grating used as a control member in the present invention. It shows the results of simulation of the optical resonance mode of an element using a circular diffraction grating as a control member, where (a) is the simulation result of the optical resonance mode on the top surface, and (b) is the simulation result of the optical resonance mode on a longitudinal cross section. It is a schematic perspective view showing a display device in which pixels are formed with edge-emitting organic solid-state semiconductor lasers using a striped diffraction grating as a control member. It is a schematic diagram showing the propagation direction of light within the organic solid-state semiconductor laser shown in FIG. 3 and the traveling direction of extracted light. It is a schematic diagram showing control of the polarization state of light generated in the light-emitting layer in the organic solid-state semiconductor laser shown in FIG. 3. It is a schematic perspective view showing a display device in which pixels are formed with top-emission organic solid-state semiconductor lasers using a striped diffraction grating as a control member. It is a schematic diagram showing the propagation direction of light within the organic solid-state semiconductor laser shown in FIG. 6 and the traveling direction of extracted light. It is a schematic cross-sectional view showing a display device in which pixels are formed with top-emission organic solid-state semiconductor lasers using partition walls as control members. 1 shows a structural example of a first embodiment of an organic solid-state semiconductor laser of the present invention, where (a) is a schematic cross-sectional view showing a state before current injection, and (b) is a schematic cross-sectional view showing the behavior of holes and electrons during current injection. FIG. 1 is a schematic cross-sectional view showing a structural example of a second embodiment of an organic solid-state semiconductor laser of the present invention. FIG. 2 is an energy level diagram of the organic solid-state semiconductor laser (laser element 1) produced in Example 1. FIG. 3 is a graph showing the calculation results of exciton density distributions of the organic solid-state semiconductor lasers (laser elements 2 and 3, comparative laser element 1) produced in Examples 2 and 3 and Comparative Example 1. FIG. 4 is a schematic cross-sectional view showing an example of a conventional organic solid-state semiconductor laser. Detailed Description of the Invention

[0012] The present invention will be described in detail below. The following description of the constituent elements may be based on representative embodiments or specific examples of the present invention, but the present invention is not limited to such embodiments or specific examples. In this specification, a numerical range expressed using "to" refers to a range that includes the numerical values ​​before and after "to" as the lower and upper limits. The isotope of the hydrogen atoms present in the molecules of the compounds used in the present invention is not particularly limited. For example, all hydrogen atoms in the molecules may be 1H, or some or all may be 2H (deuterium D). "Transparent" in the present invention refers to a visible light transmittance of 50% or more, for example, 80% or more, for example, 90% or more, or for example, 99% or more. Visible light transmittance can be measured using an ultraviolet-visible spectrophotometer. In the following description, when " / adjacent layer" and "adjacent layer / " are used, the "adjacent layer" refers to the layer adjacent to the layer described before or after the diagonal line.

[0013] <Method for Controlling Light-Extraction Characteristics of an Organic Electroluminescent Device> The method of the present invention is a method for controlling the light-extraction characteristics of an organic electroluminescent device comprising a hole injection section for injecting holes, an electron injection section for injecting electrons, and a light-emitting layer disposed between the hole injection section and the electron injection section, the light-emitting layer recombining holes and electrons to emit light, wherein light generated in the light-emitting layer propagates laterally through the light-emitting layer and is extracted from the light-extraction surface, the method being characterized by providing a recombination concentration section along the lateral direction of the light-emitting layer. In one aspect of the present invention, when the side of the light-emitting layer that forms the exciton high-density region is the electron injection section side, a hole blocking layer is provided between the light-emitting layer and the electron injection section and adjacent to the light-emitting layer. When the side of the light-emitting layer that forms the exciton high-density region is the hole injection section side, an electron blocking layer is provided between the light-emitting layer and the hole injection section and adjacent to the light-emitting layer, thereby providing a recombination concentration section along the lateral direction of the light-emitting layer. In the present invention, the "recombination concentration section" refers to a region where hole-electron recombination occurs intensively, resulting in a high exciton density (exciton high-density region). The position of the recombination concentration portion can be determined, for example, by simulating the exciton density distribution.

[0014] (Organic Electroluminescent Element) The organic electroluminescent element to be controlled in the present invention will be described. The organic electroluminescent element whose light extraction characteristics are controlled in the present invention can be, for example, an organic electroluminescent element in which light generated in the light-emitting layer propagates laterally through the light-emitting layer. Here, the "lateral direction of the light-emitting layer" refers to the direction along the interface between the light-emitting layer and the adjacent layer (the direction perpendicular to the thickness direction). Light propagating laterally through the light-emitting layer may be emitted from an end face (edge) of the organic electroluminescent element, or may be bent vertically and emitted from the surface on the electron injection section or hole injection section side. In other words, the organic electroluminescent element to be controlled in the present invention may be an edge-emitting type, a top-emission type, or a bottom-emission type, or may be a dual-emission type in which light is emitted from both the top and bottom sides. An organic electroluminescent element in which light propagates laterally through the light-emitting layer can be obtained by forming a refractive index guide or a gain guide within the element. Refractive index waveguides are formed by configuring at least one layer between the light-emitting layer and the hole injection section, and at least one layer between the light-emitting layer and the electron injection section, as a low-refractive index layer with a refractive index lower than that of the light-emitting layer. For example, at least one of the electron transport layer and the hole blocking layer, and at least one of the electron blocking layer and the hole transport layer, can be configured as low-refractive index layers. In one embodiment of the present invention, the layer adjacent to the electron injection section of the light-emitting layer and the layer adjacent to the hole injection section of the light-emitting layer are both low-refractive index layers with a refractive index lower than that of the light-emitting layer. These low-refractive index layers can function as cladding layers of the optical waveguide, and the region surrounded by the cladding layers can function as a core layer in which light is confined. Gain waveguides can also be formed by designing the device so that the gain is high in the central portion of the horizontal path. For an explanation of these waveguides, please refer to the descriptions of refractive index waveguides and gain waveguides in the <Organic Solid-State Semiconductor Laser> section. In such organic electroluminescent devices, light propagates horizontally, while the movement of holes traveling vertically is impeded (blocked) by the hole blocking layer.Alternatively, while light propagates in the horizontal direction, the movement of electrons proceeding in the vertical direction is prevented (blocked) by the electron blocking layer. Note that in the organic electroluminescent element targeted by the present invention, it is sufficient that light propagates in the horizontal direction within the light-emitting layer, and the final light extraction direction can be vertical.

[0015] In the present invention, the "exciton high-density region" can refer to a virtual cross-sectional region perpendicular to the thickness direction at the position where the exciton density is highest in the light-emitting layer when holes from the hole injection portion and electrons from the electron injection portion are injected into the light-emitting layer and carrier recombination occurs. The position of the exciton high-density region can be determined by simulating the exciton density distribution in the light-emitting layer. For example, in the simulation results shown in FIG. 12 obtained in the examples, the interface between the hole blocking layer HBL and the light-emitting layer EML, which corresponds to the peak of the exciton density distribution, corresponds to the "exciton high-density region." Furthermore, in the present invention, the "side that becomes the exciton high-density region" can be determined to be the hole injection portion side of the light-emitting layer when the exciton high-density region is located closer to the hole injection portion than the central plane in the thickness direction of the light-emitting layer, or the electron injection portion side of the light-emitting layer when the exciton high-density region is located closer to the electron injection portion than the central plane. Therefore, in the simulation results shown in FIG. 12, the electron injection portion side is determined to be the "side that becomes the exciton high-density region," and a hole blocking layer is provided between the light-emitting layer and the electron injection portion and adjacent to the light-emitting layer. Furthermore, if the simulation results show that the exciton density distribution peaks on the hole injection section side of the light-emitting layer, the hole injection section side can be determined to be the "side that becomes the exciton high density region," and an electron blocking layer can be provided between the light-emitting layer and the hole injection section and adjacent to the light-emitting layer.

[0016] The behavior of carriers in an organic electroluminescent device having a hole blocking layer or an electron blocking layer will be described with reference to FIGS. 9 and 10 . FIG. 9 shows an example of a device having a hole blocking layer between the light-emitting layer and the electron injection layer. In FIG. 9( a), 51 denotes a hole injection layer, 52 denotes a hole injection layer, 53 denotes a hole transport layer, 54 denotes a light-emitting layer, 55 denotes a hole blocking layer, 56 denotes an electron transport layer, 57 denotes an electron injection layer, and 58 denotes a diffraction grating that constitutes an optical resonator. FIG. 10 shows an example of a device having an electron blocking layer between the light-emitting layer and the hole injection layer. In FIG. 10, 61 denotes a hole injection layer, 62 denotes a hole transport layer, 63 denotes an electron blocking layer, 64 denotes a light-emitting layer, 65 denotes an electron transport layer, 66 denotes an electron injection layer, 67 denotes an electron injection layer, and 68 denotes a diffraction grating that constitutes an optical resonator. For an explanation of each layer and each part that constitutes the device, please refer to the description in the <Organic Solid-State Semiconductor Laser> section below. However, the organic electroluminescent element targeted by the present invention is not limited to the elements shown in Figures 9 and 10. When the side that becomes the exciton high density region is the electron injection section side, as shown in Figure 9(a), a hole blocking layer 55 can be provided at a position adjacent to the electron injection section 57 side of the light emitting layer 54. As shown in Figure 9(b), in such an organic electroluminescent element, holes (+) that have moved through the light emitting layer 54 are retained at the interface between the light emitting layer 54 and the hole blocking layer 55, and carrier recombination occurs intensively in a narrow region near this interface, forming a carrier recombination region RZ where the exciton density is high. Ｈ is formed. This allows for effective control of light extraction characteristics and also reduces the peak full width at half maximum (FWHM) of the emission spectrum. On the other hand, when the side that becomes the exciton high density region is the hole injection section side, as shown in FIG. 10, an electron blocking layer 63 can be provided at a position adjacent to the hole injection section 61 side of the light emitting layer 64. In such an organic electroluminescence element, electrons (-) that have moved through the light emitting layer 64 are retained at the interface between the light emitting layer 64 and the electron blocking layer 63, and carrier recombination occurs intensively in a narrow region near this interface, forming a carrier recombination region RZ where the exciton density is high. ＨThis makes it possible to effectively control the light extraction characteristics and reduce the full width at half maximum (FWHM) of the emission spectrum.

[0017] In addition, in an embodiment in which a hole blocking layer is provided, an electron transport layer is provided between the electron injection section and the hole blocking layer, and the thickness of the electron transport layer is increased, thereby preventing light from the light-emitting layer from being absorbed by the electrode of the electron injection section. This improves the light extraction efficiency from the device. In addition, in an embodiment in which an electron blocking layer is provided, a hole transport layer is provided between the hole injection section and the electron blocking layer, and the thickness of the hole transport layer is increased, thereby preventing light from the light-emitting layer from being absorbed by the electrode of the hole injection section. This improves the light extraction efficiency from the device.

[0018] The organic electroluminescent element targeted by the present invention may be a normal organic electroluminescent element, or may be one (e.g., an organic solid-state semiconductor laser) that includes an optical resonator that propagates emitted light within the light-emitting layer and oscillates laser light. Here, when the optical resonator is a diffraction grating with periodic irregularities, the position of the recombination concentration area (exciton high density region) of the light-emitting layer can be near the interface (position along the interface) between the diffraction grating side and the adjacent layer on the opposite side. Furthermore, when the optical resonator is a diffraction grating with periodic irregularities, the position of the hole blocking layer or electron blocking layer can be adjacent to the flat interface of the light-emitting layer, or can be adjacent to the interface on the opposite side of the diffraction grating side of the light-emitting layer. This allows a carrier recombination region RZ to be formed in a narrow region along the interface between the light-emitting layer and the hole blocking layer or electron blocking layer. ＨSince a diffraction grating is formed, the light extraction characteristics can be effectively controlled, which is also advantageous for narrowing the peak width (FWHM) of the emission spectrum. The diffraction grating here may be a circular diffraction grating or a striped diffraction grating used as a control member, which will be described later. That is, a circular diffraction grating or a striped diffraction grating may be used both as a control member and an optical resonator. In a preferred embodiment of the present invention, the organic electroluminescent device to be used has a diffraction grating between the exciton high density region of the light-emitting layer and the hole injection section, and the hole blocking layer can be provided between the light-emitting layer and the electron injection section and adjacent to the light-emitting layer. In a preferred embodiment of the present invention, the organic electroluminescent device to be used has a diffraction grating between the exciton high density region of the light-emitting layer and the electron injection section, and the electron blocking layer can be provided between the light-emitting layer and the hole injection section and adjacent to the light-emitting layer.

[0019] For descriptions of the hole injection section, electron injection section, and light-emitting layer constituting the organic electroluminescent device, the optical resonator provided as needed, and the hole blocking layer or electron blocking layer provided depending on the position of the exciton high-density region, please refer to the corresponding descriptions in the [First Embodiment] and [Second Embodiment] sections below. Furthermore, the organic electroluminescent device of the present invention may have layers other than the hole injection section, electron injection section, light-emitting layer, hole blocking layer, and electron blocking layer. Examples of such layers include an electron transport layer, a hole transport layer, and a spacer layer, and the device may further have other layers or a substrate. For descriptions of these layers, please refer to the descriptions in the [First Embodiment] and [Second Embodiment] sections below. In this specification, organic electroluminescent devices having a substrate will be described with the substrate side referred to as the "bottom side" and the side opposite the substrate referred to as the "top side." The organic electroluminescence element may be the organic solid-state semiconductor laser of the first or second embodiment, or may be an organic electroluminescence element obtained by removing the optical resonator from these organic solid-state semiconductor lasers.

[0020] (Control of Light Extraction Characteristics) Next, the control of light extraction characteristics performed in the present invention will be described. The "light extraction characteristics" controlled in the present invention refer to the characteristics when light from an organic electroluminescent element is extracted from the light extraction surface. The light extraction characteristics need only be controlled when light is extracted from the light extraction surface. For example, the light extraction characteristics may be controlled before the light passes through the light extraction surface. Here, the light extraction surface refers to the location of an organic electroluminescent element from which light is emitted, and includes, for example, the surface, the inside, a non-flat shape, and an organic electroluminescent element with a small light-emitting area such as a point light source. The light extraction surface may be, for example, the surface on the hole injection section side or the surface on the electron injection section side, the top surface or the bottom surface, or an end surface (edge) of the element. Furthermore, both the surface on the hole injection section side and the surface on the electron injection section side, and both the surface on the top side and the bottom side may be light extraction surfaces. The "light extraction characteristics" controlled in the present invention are at least one of the polarization state of light generated in the light-emitting layer, the lateral light intensity distribution and propagation direction of light extracted from the light extraction surface (e.g., the propagation direction of light relative to the lateral direction), and the optical crosstalk and electrical crosstalk of the organic electroluminescent element. When controlling the lateral light intensity distribution of light, the light intensity distribution in the depth direction can also be controlled in addition to the lateral direction. That is, the light intensity distribution in the in-plane direction of light can also be controlled. Furthermore, the crosstalk controlled in the present invention may be crosstalk occurring within the element or crosstalk occurring outside the element. Examples of crosstalk occurring within the element include optical crosstalk caused by light propagating laterally through the light-emitting layer leaking into the light-emitting layer of an adjacent element, and electrical leakage (electrical crosstalk) between elements that occurs when adjacent elements share a hole transport layer or electron transport layer. For example, when adjacent elements constitute pixels of different colors, the optical crosstalk may manifest as, for example, color bleeding into adjacent pixels or a decrease in color purity in low-brightness areas.Examples of crosstalk that occurs outside the element include electrical crosstalk, which occurs when wiring coupling in the drive circuit affects the drive voltage and current, causing changes in gradation, and optical crosstalk, which occurs when light emitted from the element that makes up a pixel spreads in a fan shape and enters the color filter of an adjacent pixel, resulting in a decrease in color purity and brightness.

[0021] Furthermore, when controlling the "light extraction characteristics," it is also possible to control the propagation direction of light (for example, within the element) before it is extracted from the light extraction surface. The horizontal propagation direction of light within the element can be controlled to a direction perpendicular to the horizontal direction (vertical direction), for example, when the thickness of the electron transport layer or hole transport layer is increased. This allows light generated in the light-emitting layer to be efficiently extracted from the surface of the element, even when the thickness of the electron transport layer or hole transport layer is increased.

[0022] The control of the "light extraction characteristics" in the present invention is, for example, at least one of (a) converting the polarization state of light generated in the light-emitting layer from random polarization to specific polarization, (b) sharpening the peak of the light intensity distribution in the horizontal direction on the light extraction surface, (b') sharpening the peak of the light intensity distribution in the horizontal and depth directions on the light extraction surface, (c) aligning the traveling direction of light emitted from the light extraction surface in a specific direction, such as a direction perpendicular to the horizontal direction (vertical direction) or a direction parallel to the horizontal direction, (d) suppressing or preventing optical crosstalk, and (e) suppressing or preventing electrical crosstalk. Here, the recombination concentration portion (carrier recombination region RZ) along the horizontal direction of the light-emitting layer is ＨWhen a configuration in which a recombination concentration region is formed is adopted, excitons are generated locally in the recombination concentration region, forming an exciton high-density region, and light is emitted in this region. The light emitted in this manner has a smaller spread and a specific direction of travel than light emitted by carrier recombination dispersed throughout the entire light-emitting layer. Therefore, by providing a recombination concentration region along the lateral direction of the light-emitting layer, the peak of the lateral light intensity distribution of light extracted from the light extraction surface is sharpened, thereby suppressing or preventing optical crosstalk. Furthermore, by providing a control member (described later) in contact with the light-emitting layer, the above-mentioned light extraction characteristics can be effectively controlled. Below, a control member that can be used to control the light extraction characteristics will be described in detail.

[0023] (Control Member) The control member can be made of an insulating material with a lower refractive index than the light-emitting layer and can be provided so as to be in contact with the light-emitting layer. The insulating material used for the control member can be an inorganic insulating material or an organic insulating material. Examples of insulating materials that can be used for the control member include ceramics such as silicon dioxide, glass, and plastic. When the refractive index of the control member is lower than that of the light-emitting layer, light generated in the light-emitting layer is reflected at the interface between the light-emitting layer and the control member, thereby controlling the propagation direction, spatial light intensity distribution, and optical crosstalk between adjacent elements. Furthermore, when the control member is made of an insulating material, electrical crosstalk between adjacent elements can be suppressed or prevented. These low-refractive-index insulating materials can be used as materials for the circular diffraction gratings, striped diffraction gratings, and partition walls described below.

[0024] A circular diffraction grating can be used as an example of a control member that controls at least one of the lateral and depth-direction light intensity distribution of light extracted from the light extraction surface, the direction of light travel from the lateral direction, and optical crosstalk of an organic electroluminescent element. Figure 1 shows an example of a circular diffraction grating as a control member. In one embodiment of the present invention, in Figure 1, 10 denotes a substrate with a hole injection portion, 11 denotes a cladding layer (low refractive index layer), and 12 denotes a circular diffraction grating. At least a light-emitting layer, a hole blocking layer, and an electron injection portion can be provided on the circular diffraction grating 12. This allows a recombination concentration region to be formed near the interface of the light-emitting layer with the hole blocking layer. In one embodiment of the present invention, in Figure 1, 10 denotes a substrate with an electron injection portion, 11 denotes a cladding layer (low refractive index layer), and 12 denotes a circular diffraction grating. At least a light-emitting layer, an electron blocking layer, and a hole injection portion can be provided on the circular diffraction grating 12. This allows a recombination concentration region to be formed near the interface of the light-emitting layer with the electron blocking layer. When 10 is a substrate with a hole injection section, the low refractive index layer 11 can be configured as a hole transport layer, and when 10 is a substrate with an electron injection section, the low refractive index layer 11 can be configured as an electron transport layer. The circular diffraction grating has concentric grating projections in a planar view, and can be provided so that at least a portion of the grating projections contact the light-emitting layer (so that they penetrate into the light-emitting layer). The grating projections of the circular diffraction grating are formed with the interface between an adjacent layer ("low refractive index layer 11" in FIG. 1) and the light-emitting layer as their base end, and the entire grating projections may contact the light-emitting layer, or they may be formed with the interface between an electron injection section and an adjacent layer ("low refractive index layer 11" in FIG. 1) or the interface between layers disposed between the electron injection section and the light-emitting layer as their base end, and a portion of the grating projections may contact the light-emitting layer. The circular diffraction grating is designed to satisfy the following Bragg equation. Bragg equation: mλ Ｂｒａｇｇ = 2n ｅｆｆ Λ ｍ where m is the diffraction order, λ Ｂｒａｇｇ is the Bragg wavelength, n ｅｆｆ is the effective refractive index, Λ ｍis the period of the diffraction grating. The circular diffraction grating can be designed to include a second-order diffraction grating where m is 2. The circular diffraction grating may be a circular diffraction grating where m is 2, or may be a mixed-order diffraction grating that combines a first-order diffraction grating where m is 1 and a second-order diffraction grating where m is 2. In the case of a mixed-order diffraction grating, for example, the central region can be a second-order diffraction grating and its surrounding (peripheral region) can be a first-order diffraction grating. By using a circular diffraction grating including a second-order diffraction grating, light propagating laterally through the light-emitting layer can be confined to the center, bent vertically by the second-order diffraction grating, and emitted from the surface (light extraction surface). This allows a light intensity distribution with a sharp peak in the center to be obtained on the light extraction surface, effectively suppressing optical crosstalk between adjacent elements.

[0025] The dimensions of the diffraction grating as a control member (e.g., the height, width, and pitch of the grating projections, the diameter of the circular diffraction grating, etc.) can be appropriately designed according to the wavelength (emission color) of the light extracted from the light extraction surface. For example, in conventional organic displays that do not use a control member such as a diffraction grating, blue (B) pixels have a smaller amount of light emission per unit area than other pixels and a shorter lifespan. Therefore, for blue (B) pixels, the lifespan is secured by reducing the applied current per unit area, or the pixel area is increased to increase the amount of light emission. Therefore, in conventional organic displays, the blue (B) pixel area must be relatively large, which limits the improvement of pixel density. In contrast, in one aspect of this embodiment using a diffraction grating as a control member, for example, the grating pitch of the blue (B) pixel can be designed to be narrower than that of the red (R) and green (G) pixels so as to satisfy the Bragg equation, thereby increasing the amount of light emission per unit area. Therefore, a sufficient amount of light emission can be secured, and the blue (B) pixel area can be designed to be smaller.

[0026] Figure 2 shows the simulation results of the optical resonance mode of an element using a circular diffraction grating. Figure 2(a) shows the simulation results for the top surface of an element using a 10 μm diameter circular diffraction grating, and Figure 2(b) shows the simulation results for the cross section of an element using a 3.3 μm diameter circular diffraction grating. Table 1 also shows the results of calculations of the optical confinement ratio for elements using a second-order circular diffraction grating or a mixed-order circular diffraction grating. The calculation results shown in Table 1 show that by using a circular diffraction grating, light is confined to the center, resulting in a light intensity distribution with a sharp peak at the center.

[0027]

[0028] The circular diffraction grating used in the present invention may have the functions of both a control element and a distributed feedback (DFB) optical resonator. In one aspect of the present invention, the object to be controlled is an organic solid-state semiconductor laser, and a circular diffraction grating serving as both a control element and a DFB optical resonator is provided in contact with the light-emitting layer.

[0029] An example of a control member that controls at least one of the lateral light intensity distribution and the lateral propagation direction of light extracted from the light extraction surface, and the optical crosstalk of an organic electroluminescent element, is a diffraction grating having a plurality of convex portions arranged in a stripe pattern. In one aspect of the present invention, the stripe-shaped diffraction grating serving as the control member has the longitudinal direction of each convex portion perpendicular to the lateral direction of the light-emitting layer, and the plurality of convex portions arranged side by side in the lateral direction. The stripe-shaped diffraction grating is designed to satisfy the Bragg equation. The stripe-shaped diffraction grating may be a first-order diffraction grating where m is 1, a second-order diffraction grating where m is 2, or a third-order diffraction grating where m is 3, or may be a higher-order diffraction grating. It may also be a mixed-order diffraction grating that combines diffraction gratings of different orders. The stripe-shaped diffraction grating may function as both a control member and a DFB optical resonator. In one aspect of the present invention, the object to be controlled is an organic solid-state semiconductor laser, and a stripe-shaped diffraction grating that serves as both a control member and a DFB optical resonator is provided in contact with the light-emitting layer.

[0030] Control of light extraction characteristics using a striped diffraction grating will be described with reference to FIGS. 3 to 7 , using an organic solid-state semiconductor laser as an example. FIGS. 3 and 6 are schematic perspective views showing a portion of a display device in which three organic solid-state semiconductor lasers are arranged side by side to form red (R), green (G), and blue (B) pixels. FIG. 3 shows an edge-emitting display device, and FIG. 6 shows a top-emission display device. In one embodiment of the present invention, in FIGS. 3 and 6 , 21 and 31 are hole injection sections, 22R, 22G, 22B, 32R, 32G, and 32B are diffraction gratings (DFB optical resonators), 23 and 33 are hole transport layers, 24 and 34 are light-emitting layers, 25 and 35 are stacked structures of a hole blocking layer / electron transport layer, and 26 and 27 are electron injection sections. 3 and 6, 21 and 31 are electron injection sections, 22R, 22G, 22B, 32R, 32G, and 32B are diffraction gratings (DFB optical resonators), 23 and 33 are electron transport layers, 24 and 34 are light-emitting layers, 25 and 35 are stacked structures of electron blocking layer / hole transport layer, and 26 and 36 are hole injection sections. Here, the hole transport layer 23, the electron transport layer 23, and the hole blocking layer and electron blocking layer of the stacked structure 25 can be made of a material with a lower refractive index than the light-emitting layer and function as cladding layers. In the edge-emitting display device shown in FIG. 3, the DFB optical resonators 22R, 22G, and 22B are first-order diffraction gratings, and are each designed to satisfy the following formula: λ Ｂｒａｇｇ (R) = 2n ｅｆｆ Λ Ｒ１ λ Ｂｒａｇｇ (R) = 2n ｅｆｆ Λ Ｇ１ λ Ｂｒａｇｇ (B) = 2n ｅｆｆ Λ Ｂ１ where λ Ｂｒａｇｇ (R) is a wavelength in the red region, which can be selected, for example, from the range of 625 to 780 nm, and λ Ｂｒａｇｇ (G) is a wavelength in the green region, which can be selected, for example, from the range of 500 to 565 nm, and λ Ｂｒａｇｇ (B) is a wavelength in the blue region, which can be selected, for example, from the range of 450 to 485 nm. Ｒ１ is the period of the DFB optical resonator 22R, and ΛＧ１ is the period of the DFB optical resonator 22G, and Λ Ｂ１ is the period of the DFB optical resonator 22B. ｅｆｆ is the effective refractive index. As shown in Figure 4, in the organic solid-state semiconductor laser targeted by the present invention, the light generated in the recombination concentration zone RZ of the light-emitting layer propagates in the lateral direction. At this time, if a DFB optical resonator 22 (22B, 22G, 22R) which is a first-order diffraction grating is provided in the propagation path, the Bragg wavelength λ Ｂｒａｇｇ (R)λ Ｂｒａｇｇ (G), λ Ｂｒａｇｇ Only light with wavelengths matching (B) is amplified, and the light is confined to the center. Furthermore, as shown in FIG. 5, the vibration direction of the light's electric field is aligned parallel to the side surface of the lattice convex portion 22a, converting the light into linearly polarized light. Therefore, even if light generated in the light-emitting layer leaks into an adjacent pixel, only light of a specific wavelength is amplified by the DFB optical resonator in that pixel region, preventing color bleeding between pixels. Furthermore, the light amplified by each DFB optical resonator 22B, 22G, and 22R becomes linearly polarized light R, G, and B and is emitted from the center of the end surface (light extraction surface) of each pixel in a direction parallel to the horizontal direction. This effectively suppresses optical crosstalk that occurs within and outside the device, while efficiently obtaining linearly polarized light of multiple colors.

[0031] Furthermore, by linearly polarizing the light generated in the light-emitting layer, it is possible to eliminate the need for anti-reflection polarizers, which are used in, for example, virtual reality (VR) glasses and augmented reality (AR) glasses. This avoids light loss in the polarizer, allowing the light extracted from the element to be used efficiently, thereby improving the contrast or reducing power consumption of the VR glasses or AR glasses. While the embodiment of the present invention described herein linearly polarizes the light generated in the light-emitting layer, the polarization control performed in this embodiment is not limited to linear polarization and also includes other polarization states, such as circular polarization and reverse circular polarization.

[0032] In the top-emission display device shown in FIG. 6, the DFB optical resonators 32R, 32G, and 32B are second-order diffraction gratings, and are designed to satisfy the following equations: Ｂｒａｇｇ (R) = n ｅｆｆ Λ Ｒ２ λ Ｂｒａｇｇ (R) = n ｅｆｆ Λ Ｇ２ λ Ｂｒａｇｇ (B) = n ｅｆｆ Λ Ｂ２ where λ Ｂｒａｇｇ (R), λ Ｂｒａｇｇ (G), λ Ｂｒａｇｇ Regarding the explanation of (B), the λ of the DFB optical resonators 22R, 22G, and 22B Ｂｒａｇｇ (R), λ Ｂｒａｇｇ (G), λ Ｂｒａｇｇ See the description of (B). Ｒ２ is the period of the DFB optical resonator 32R, and Λ Ｇ２ is the period of the DFB optical resonator 32G, and Λ Ｂ２ is the period of the DFB optical resonator 32B. ｅｆｆ is the effective refractive index of the ridge portion. As shown in Figure 7, in the organic solid-state semiconductor laser targeted by the present invention, the light generated in the recombination concentration portion RZ of the light-emitting layer propagates in the horizontal direction. At this time, if a DFB optical resonator 32 (32B, 32G, 32R) which is a second-order diffraction grating is provided in the propagation path, the propagation direction of the light is bent in the vertical direction due to the diffraction phenomenon, and the wavelength is changed to the Bragg wavelength λ Ｂｒａｇｇ (R), λ Ｂｒａｇｇ (G), λ ＢｒａｇｇOnly light that matches the wavelength (B) is amplified and confined to the center. Furthermore, as shown in FIG. 5, the vibration direction of the light's electric field is aligned parallel to the side surface of the ridge portion 22a, converting the light into linearly polarized light. Therefore, even if light generated in one light-emitting layer leaks into an adjacent light-emitting layer, the DFB diffraction grating in that region bends the light's propagation direction vertically, amplifying only light of a specific wavelength, preventing color bleeding between pixels. Furthermore, the light amplified by each DFB optical resonator becomes linearly polarized and exits vertically from the center of the top surface (light extraction surface) of each pixel, resulting in a light intensity distribution with a sharp peak in the center on the light extraction surface. This effectively suppresses optical crosstalk that occurs within and outside the device, while efficiently obtaining linearly polarized light of multiple colors.

[0033] An example of a control member for controlling crosstalk is a partition wall made of a low-refractive-index insulating material formed to surround at least the end faces of the light-emitting layer. Control of light extraction characteristics using a partition wall will be described with reference to FIG. 8 , using an organic solid-state semiconductor laser as an example. FIG. 8 is a schematic cross-sectional view showing a portion of a top-emission display device in which three organic solid-state semiconductor lasers constituting red (R), green (G), and blue (B) pixels are arranged side by side. In one embodiment of the present invention, in FIG. 8 , 40 denotes a substrate, 41 denotes a hole injection portion, 42R, 42G, and 42B denote DFB optical resonators, 43 denotes a hole transport layer, 44 denotes a light-emitting layer, 45 denotes a stacked structure of a hole blocking layer / electron transport layer, 46 denotes an electron injection portion, and 47 denotes a partition wall. 8 , 40 denotes a substrate, 41 denotes an electron injection portion, 42R, 42G, and 42B denote DFB optical resonators, 43 denotes an electron transport layer, 44 denotes a light-emitting layer, 45 denotes a stacked structure of an electron blocking layer / hole transport layer, 46 denotes a hole injection portion, and 47 denotes a partition wall. In one embodiment of the display device shown in FIG. 8 , the partition wall 47 is provided so as to surround each end face of the hole injection portion 41, the light-emitting layer 44, and the stacked structure 45 of the elements constituting each pixel of red R and green G, while in another embodiment, the partition wall 47 is provided so as to surround each end face of the electron injection portion 41, the light-emitting layer 44, and the stacked structure 45 of the elements constituting each pixel of red R and green G. However, it is sufficient that the partition wall is provided around at least the end face of the light-emitting layer among the end faces of the elements. That is, the partition wall may be provided so as to surround only the edge of the light-emitting layer, or so as to surround the edge of the light-emitting layer and the edge of the layer other than the light-emitting layer, or so as to surround the edge of the light-emitting layer, the edge of the layer other than the light-emitting layer, and the edge of the hole injection section or the electron injection section. In this organic solid-state semiconductor laser, since the edge of the light-emitting layer is surrounded by the partition wall, light generated in the light-emitting layer is reflected at the interface between the light-emitting layer and the partition wall, thereby suppressing or preventing optical crosstalk caused by leakage to the light-emitting layer of an adjacent element. Furthermore, since the edge of the hole injection section or the electron injection section, the hole transport layer, the hole blocking layer, the electron transport layer, and the electron blocking layer are also surrounded by the partition wall, they are electrically insulated from the adjacent element, thereby suppressing or preventing electrical crosstalk.

[0034] Photonic crystal materials can also be cited as an example of a control member that suppresses crosstalk between adjacent elements. By surrounding the light-emitting layer with a photonic crystal material whose stop band includes the wavelength of light generated in the light-emitting layer, the photonic crystal inhibits the propagation of light to the surroundings. This makes it possible to suppress or prevent optical crosstalk caused by light generated in the light-emitting layer leaking into the light-emitting layer of an adjacent element. The photonic crystal material can be appropriately selected from known materials and used.

[0035] The light extraction characteristics may be controlled using only one of these control members, or two or more of them in combination. For example, combinations of two or more may include a combination of a circular diffraction grating and a partition wall, a combination of a circular diffraction grating and a photonic crystal material, a combination of a striped diffraction grating and a partition wall, and a combination of a striped diffraction grating and a photonic crystal material. Furthermore, the control of the light extraction characteristics using these control members may be performed on organic electroluminescence elements other than organic solid-state semiconductor lasers.

[0036] <Organic Solid-State Semiconductor Laser> Next, an example in which the organic electroluminescence device of the present invention is used as an organic solid-state semiconductor laser will be described. The organic solid-state semiconductor laser of the present invention comprises a hole injection section for injecting holes, an electron injection section for injecting electrons, a light-emitting layer that recombines holes and electrons to emit light, and an optical resonator for propagating the emitted light within the light-emitting layer. The organic solid-state semiconductor laser is characterized by having a hole blocking layer adjacent to the light-emitting layer on the electron injection section side of the light-emitting layer, or an electron blocking layer adjacent to the light-emitting layer on the hole injection section side of the light-emitting layer, and a control member for controlling light extraction characteristics. In the following description, an embodiment of the organic solid-state semiconductor laser of the present invention in which the hole blocking layer is adjacent to the light-emitting layer on the electron injection section side of the light-emitting layer will be referred to as a "first embodiment," and an embodiment in which the electron blocking layer is adjacent to the light-emitting layer on the hole injection section side of the light-emitting layer will be referred to as a "second embodiment." Below, the configurations of the first and second embodiments of the present invention will be described.

[0037] [First Embodiment] The organic solid-state semiconductor laser of the first embodiment includes at least a hole injection section, a light-emitting layer, a hole blocking layer, and an electron injection section stacked in this order. The laser includes an optical resonator that propagates emitted light within the light-emitting layer and a control member that controls light extraction characteristics. Here, the control member may also function as both the control member and the optical resonator. That is, in one aspect of the present invention, the organic solid-state semiconductor laser of the first embodiment includes at least a hole injection section, a light-emitting layer, a hole blocking layer, and an electron injection section stacked in this order. The control member also functions as both the control member and the optical resonator. For a description of the control member, examples of control members that also function as an optical resonator, and other examples of control members, please refer to the description in the (Control Member) section above. The organic solid-state semiconductor laser of the first embodiment may further include a spacer layer between the hole blocking layer and the electron injection section, or one or more layers between the light-emitting layer and the hole injection section. Here, the light-emitting layer, the hole blocking layer, the spacer layer, and one or more layers disposed between the light-emitting layer and the hole injection section may be organic layers. In this specification, the term "organic layer" refers to a layer containing 70% or more by weight of an organic compound, and the term "organic compound" refers to a compound containing one or more carbon atoms. The organic compound may be composed solely of atoms selected from the group consisting of carbon, hydrogen, oxygen, nitrogen, boron, and halogen atoms. A specific structural example of the first embodiment is shown in FIG. 9( a). In FIG. 9( a), 51 denotes a hole injection portion, 52 denotes a hole injection layer, 53 denotes a hole transport layer, 54 denotes a light-emitting layer, 55 denotes a hole blocking layer, 56 denotes an electron transport layer, 57 denotes an electron injection portion, and 58 denotes a diffraction grating that doubles as a control member and an optical resonator. Here, the electron transport layer 56 constitutes a spacer layer, and the hole injection layer 52 and the hole transport layer 53 correspond to the "one or more layers disposed between the light-emitting layer and the hole injection portion" described above. The diffraction grating may be a circular diffraction grating or a striped diffraction grating. For descriptions of these diffraction gratings, please refer to the corresponding descriptions in the (Control Member) section above.

[0038] The organic solid-state semiconductor laser of the first embodiment has a hole-blocking layer 55 provided adjacent to the light-emitting layer 54, thereby achieving high laser efficiency and laser emission with narrow peak widths in both the emission spectrum and the angular light intensity distribution. Furthermore, if necessary, a spacer layer 56 may be provided between the hole-blocking layer 55 and the electron injection section 57 to further improve the laser efficiency. The reason for this will be explained below with reference to FIGS. 9 and 13 . The conventional organic solid-state semiconductor laser shown in FIG. 13 has a light-emitting layer 102 with a thickness of approximately 200 nm made of a laser oscillation material and a diffraction grating 104 between the electron injection section 101 and the hole injection section 103, and has a homojunction structure in which carriers are injected from the electron injection section 101 and the hole injection section 103 into a single organic semiconductor layer (light-emitting layer 202). In such an organic solid-state semiconductor laser with a homojunction structure, when carriers (positive holes (+) and electrons (-)) are injected from the injection portions 101 and 103 into the light-emitting layer 102, the entire light-emitting layer 102 becomes a carrier recombination region RZ where the exciton density is low. Ｌ 9B , when carriers are injected from the injection sections 51 and 57, the holes (+) injected into the emission layer 54 are transported toward the hole blocking layer 55 within the emission layer 54. However, the interface 55 s between the emission layer 54 and the hole blocking layer 55 acts as a barrier, preventing the holes from moving toward the electron injection section 57. Therefore, holes (+) are accumulated near this interface 55s, and the accumulated holes and electrons (-) that have moved from the hole blocking layer 55 into the light emitting layer 54 cause concentrated carrier recombination, forming a carrier recombination region RZ with a high exciton density near this interface 55s. ＨAs a result, this region RZ Ｈ In addition, when the spacer layer 56 is disposed between the hole blocking layer 55 and the electron injection region 57, the carrier recombination region RZ Ｈ Since a space is created between the electron injection portion 57 and the carrier recombination region RZ Ｈ This can prevent light generated in the organic solid-state semiconductor laser from being lost due to the formation of surface plasmon polaritons on the electrode surface, and from being absorbed or scattered by the electrodes. Thus, the organic solid-state semiconductor laser of the present invention concentrates the recombination region, which corresponds to the gain region, in a limited region within the light-emitting layer, and further provides a spacer layer, if necessary, to distance it from the electrodes, which cause loss, thereby maintaining gain higher than loss and achieving stable laser oscillation. Because of these characteristics, the organic solid-state semiconductor laser of the present invention can further improve laser efficiency and monochromaticity, and also contributes to the realization of low-voltage operation.

[0039] Furthermore, in the organic solid-state semiconductor laser of the first embodiment, by having a diffraction grating that serves both as a control member and an optical resonator, a light intensity distribution having a sharp peak can be obtained on the light extraction surface, and when used to form pixels of a display device, optical crosstalk between adjacent pixels can be effectively suppressed or prevented. Furthermore, when a striped diffraction grating is used, light generated in the light-emitting layer can be converted into linearly polarized light and efficiently extracted from the light extraction surface.

[0040] Furthermore, the organic solid-state semiconductor laser of the first embodiment may further include a partition or a photonic crystal material as a control member. In this case, the optical resonator may also function as a control member, or may not function as a control member. By using a partition or a photonic crystal material as a control member, a light intensity distribution with a sharp peak can be obtained on the light extraction surface, and when used to form pixels of a display device, optical crosstalk between adjacent pixels can be effectively suppressed or prevented. Furthermore, when a partition is used, adjacent pixels are electrically insulated from each other, so electrical crosstalk can be effectively suppressed or prevented.

[0041] The following describes each component and each layer of the organic solid state semiconductor laser according to the first embodiment. For a description of the control component, please refer to the description in the (Control component) section above.

[0042] (Substrate) The organic solid-state semiconductor laser of the present invention may have each component and layer supported on a substrate. When the organic solid-state semiconductor laser is configured to extract laser light from the substrate side, a substrate that is transmissive to laser light is used as the substrate, and a transparent substrate made of glass, transparent plastic, quartz, or the like can be used. On the other hand, when the organic solid-state semiconductor laser is configured to extract laser light from the side opposite the substrate, the substrate is not particularly limited, and in addition to the transparent substrates described above, substrates made of silicon, paper, or cloth can also be used. The organic solid-state semiconductor laser of the first embodiment may have a hole injection section, a light-emitting layer, a hole blocking layer, and an electron injection section stacked in this order on a substrate, or may have an electron injection section, a hole blocking layer, a light-emitting layer, and a hole injection section stacked in this order on a substrate.

[0043] (Hole injection section) The hole injection section has the function of injecting holes. For example, when a light-emitting layer is provided adjacent to the hole injection section, holes are directly injected from the hole injection section into the light-emitting layer. Furthermore, when one or more layers are provided between the light-emitting layer and the hole injection section, holes are injected from the hole injection section into one of the one or more layers that is adjacent to the hole injection section, and the holes transported through the one or more layers are injected into the light-emitting layer.

[0044] In one aspect of the present invention, the hole injection portion of the first embodiment is an electrode, for example, a transparent electrode. The electrode (hereinafter referred to as "anode") that is the hole injection portion can be made of, for example, a metal, alloy, electrically conductive compound, or a mixture thereof that has a large work function (4 eV or more). Specific examples of such electrode materials include metals such as Au, CuI, indium tin oxide (ITO), and SnO. ２ , ZnO, TiN, and other conductive transparent materials. ２ O ３ Materials capable of producing amorphous, transparent conductive films, such as ZnO, may also be used. The anode can be formed by depositing these electrode materials by methods such as vapor deposition or sputtering. Alternatively, a desired pattern may be formed on the formed thin film using photolithography, or, if pattern precision is not required (approximately 100 μm or more), a pattern may be formed using a mask of the desired shape during vapor deposition or sputtering of the electrode material. Alternatively, when a coatable material such as an organic conductive compound is used, wet film formation methods such as printing or coating can also be used. However, if the organic solid-state semiconductor laser is configured to extract laser light by transmitting it through the anode, the anode must be transparent. Specifically, to form a transparent anode, for example, the above-mentioned conductive transparent materials can be used as the anode, a thin film formed of a metal or alloy with a thickness of 5 to 100 nm can be used as the anode, or an electrode having the DMD structure described below can be used as the anode. The thickness of the metal or alloy thin film is, for example, 40 nm or less, for example, 5 to 30 nm, for example, 12 to 25 nm. The sheet resistance as an anode is, for example, several hundred Ω / □ or less. Furthermore, the film thickness, although depending on the material, is usually selected in the range of 10 to 1000 nm, for example, 10 to 200 nm.

[0045] (Electron Injection Section) The electron injection section has the function of injecting electrons. For example, when a hole blocking layer is provided adjacent to the electron injection section, electrons are injected from the electron injection section to the hole blocking layer, and the electrons transported through the hole blocking layer are injected into the light-emitting layer. When a spacer layer is provided between the hole blocking layer and the electron injection section and adjacent to the electron injection section, electrons are injected from the electron injection section to the spacer layer, and the electrons transported through the spacer layer and the hole blocking layer are injected into the light-emitting layer.

[0046] In one aspect of the present invention, the electron injection section of the first embodiment is an electrode, for example, a metal electrode. The material of the metal electrode may be any of a simple metal element, a mixture of two or more simple metal elements, an alloy of two or more metal elements, a mixture of a simple metal element and an alloy, and a mixture of two or more alloys. For the electrode serving as the electron injection section (hereinafter referred to as the "cathode"), a metal (referred to as an electron injection metal) or alloy having a smaller work function than the electrode material used for the anode can be used. Furthermore, an electrically conductive compound or a mixture thereof can also be used as the electrode material for the cathode. Specific examples of such cathode materials include sodium, sodium-potassium alloy, magnesium, lithium, a magnesium / copper mixture, a magnesium / silver mixture, a magnesium / aluminum mixture, a magnesium / indium mixture, and aluminum / aluminum oxide (Al ２ O ３ Among these, for example, in terms of electron injection property and durability against oxidation, etc., a mixture of an electron injection metal and a second metal which is a metal having a larger work function value and is more stable than the electron injection metal can be used, and examples thereof include a magnesium / silver mixture, a magnesium / aluminum mixture, a magnesium / indium mixture, an aluminum / aluminum oxide (Al ２ O ３) mixture, lithium / aluminum mixture, aluminum, etc. can be used. Furthermore, a coated metal film, in which a coating of lithium fluoride or the like is provided on the surface of a thin film formed from an electron-injecting metal, can also be used as the cathode. The cathode can be formed by depositing these electrode materials by methods such as vapor deposition or sputtering. However, if the laser element is configured to extract laser light by transmitting light through the cathode, the cathode must be transparent. Specifically, to form a transparent cathode, a thin film formed from the above-mentioned electrode material to a thickness of 5 to 100 nm (e.g., 40 nm or less, e.g., 5 to 30 nm, e.g., 12 to 25 nm) can be used as the cathode; a laminated structure (e.g., an ITO / Al / LiF laminated structure) in which the above-mentioned coated metal film is laminated on a thin film of a conductive transparent material exemplified as an anode material can be used as the cathode; or an electrode having the DMD structure described below can be used as the cathode. The sheet resistance of the cathode is, for example, several hundred Ω / □ or less, and the film thickness is usually selected in the range of 10 nm to 5 μm, for example, 50 to 200 nm.

[0047] In one embodiment of the present invention, at least one of the electron injection part and the hole injection part is an electrode having a visible light transmittance of 10% or more, for example, 50% or more, for example, 80% or more, or for example, 90% or more.

[0048] (Light-Emitting Layer) The light-emitting layer is a layer in which excitons are generated by the recombination of holes and electrons injected from the hole injection section and electron injection section, respectively, forming a population inversion and causing stimulated emission. The light-emitting layer contains a laser oscillation material (optical gain medium) capable of causing such stimulated emission. The light-emitting layer may be composed solely of the laser oscillation material, or may be a layer in which the laser oscillation material is doped into a host material. The light-emitting layer may also contain a laser oscillation material and a dopant material. Examples of dopant materials include a light-emitting material and a triplet quencher. Doping the light-emitting layer with a light-emitting material can control the wavelength and color of light emitted by the light-emitting layer. Furthermore, doping the light-emitting layer with a triplet quencher suppresses the accumulation of triplet excitons in the light-emitting layer, thereby suppressing the generation of higher-order excited states due to collisions between triplet excitons and the degradation of excited molecules caused by these higher-order excited states. As a result, the light-emitting efficiency can be improved. In one embodiment of the present invention, the light-emitting layer is composed solely of the laser oscillation material. In one embodiment of the present invention, the light-emitting layer is a layer formed by doping a host material with a laser oscillation material. In one embodiment of the present invention, the light-emitting layer is a layer formed by mixing a laser oscillation material with a dopant material. In one embodiment of the present invention, the light-emitting layer is a layer formed by doping a host material with a laser oscillation material and a dopant material. In one embodiment of the present invention, the dopant material is an organic compound. In one embodiment of the present invention, the dopant material comprises an emitting material. In one embodiment of the present invention, the dopant material comprises a triplet quencher. In one embodiment of the present invention, the dopant material comprises an emitting material and a triplet quencher.

[0049] The laser oscillation material can be selected from organic compounds having at least one stilbene unit, where the stilbene unit has the following structure, at least one hydrogen atom of which may be substituted with a substituent:

[0050]

[0051] In one embodiment of the present invention, the laser oscillation material is selected from organic compounds having two or more stilbene units. In the two or more stilbene units, the phenyl groups of adjacent stilbene units may be linked by a single bond at the 4- and 4'-positions, or may be linked by a single bond at the 4- and 4'-positions and a methylene group at the 3- and 3'-positions to form a fluorene ring. At least one hydrogen atom of the benzene ring constituting the stilbene unit may be substituted with a substituent (e.g., an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 15 carbon atoms). Furthermore, the hydrogen atom at the 9-position (methylene group) of the fluorene ring may be substituted with two alkyl groups (e.g., having 1 to 10 carbon atoms, e.g., 6 carbon atoms), and a hydrocarbon ring such as a fluorene ring may be spiro-bonded to the 9-position.

[0052] Specific examples of laser oscillation materials that can be used in the present invention are listed below. However, the laser oscillation materials that can be used in the present invention should not be construed as being limited by these specific examples. First, a specific example of a laser oscillation material having a stilbene unit is 4,4'-bis[(N-carbazole)styryl]biphenyl (BSBCz) represented by the following formula. In one embodiment of the present invention, the light-emitting layer contains BSBCz. In one embodiment of the present invention, the light-emitting layer is a layer composed only of BSBCz. In another embodiment of the present invention, the light-emitting layer is a layer formed by doping BSBCz into a host material. The layer formed by doping BSBCz into a host material may further contain a dopant material.

[0053]

[0054] Examples of laser oscillation materials having a stilbene unit include the following compound and a polymer having the following repeating structure: １ and R ２ represents an alkyl group having 1 to 10 carbon atoms, such as a hexyl group. n and m each independently represent an integer of 2 to 20. n and m may be the same or different.

[0055]

[0056] The laser oscillation material can also be selected from organic compounds having at least one fluorene ring. Examples of laser oscillation materials having a fluorene ring include the following compounds and polymers having the following repeating structures: In the following formulas, R represents an alkyl group having 1 to 10 carbon atoms, such as a hexyl group; Me represents a methyl group, hexyl represents a hexyl group, and Oct represents an octyl group; n represents an integer from 2 to 30, such as 2, 3, 4, 5, or 6. Note that compounds having both a stilbene unit and a fluorene ring are shown above as specific examples of laser oscillation materials having a stilbene unit.

[0057]

[0058] The laser oscillation material can also be selected from organic compounds having at least one condensed polycyclic structure (julolidine ring) shown below.

[0059]

[0060] Examples of laser oscillation materials having a julolidine ring include the following compounds.

[0061] By using, for example, a material other than a polymer (a polymer of a monomer) among the above laser oscillation materials, the light emitting layer can be easily formed by vapor deposition.

[0062] The luminescent material used as the dopant material can be, for example, a luminescent organic compound, and may be any of a fluorescent material, a delayed fluorescent material, and a phosphorescent material. In this specification, a "fluorescent material" refers to a luminescent material whose fluorescent emission intensity is higher than its phosphorescence emission intensity when observed at 20°C, and a "phosphorescent material" refers to a luminescent material whose phosphorescence emission intensity is higher than its fluorescence emission intensity when observed at 20°C. A "delayed fluorescent material" refers to a material in which both fluorescence with a short emission lifetime and fluorescence with a long emission lifetime (delayed fluorescence) are observed at 20°C. Ordinary fluorescence (fluorescence other than delayed fluorescence) has an emission lifetime on the order of nanoseconds, while phosphorescence usually has an emission lifetime on the order of milliseconds. Therefore, fluorescence and phosphorescence can be distinguished by their emission lifetimes. Furthermore, luminescent organic compounds other than organometallic complexes are ordinary fluorescent materials or delayed fluorescent materials. Furthermore, the luminescent material used as the dopant material may be an organic compound known as an optical gain medium. However, the compound used as the luminescent material must be different from the compound used as the laser oscillation material in the organic solid-state semiconductor laser. The configuration and driving conditions of the optical resonator of the organic solid-state semiconductor laser used in the present invention are designed based on the conditions (e.g., emission wavelength and oscillation threshold) of the organic compound selected as the laser oscillation material so that the organic compound can oscillate as a laser.

[0063] The emission wavelength and color of the light-emitting material are appropriately selected depending on the oscillation wavelength of the laser oscillation material and the target emission wavelength and color. For example, the emission wavelength of the light-emitting material may be selected from the visible region, infrared region, or ultraviolet region.

[0064] Specific examples of luminescent materials include fluorene-based molecules, styrylbenzene-based molecules, carbazole-styrylbiphenyl compounds, TADF materials (thermally activated delayed fluorescent materials), star polymers, polyfluorenes, phenylene vinylene polymers, and ladder polymers described in Adv. Photonics Res. 2021, 2, 2000155, and examples of luminescent molecules described in CCS Chem. 2020, 2, 1203-1216. Here, "star polymer" refers to a polymer with three or more branched chains extending radially from a common center (e.g., a benzene core, a pyrene core, or a truxene core), and "ladder polymer" refers to a polymer in which monomer units are linked by two or more bonds. Representative examples of these compounds are listed below. Unless otherwise specified, n represents an integer between 2 and 20.

[0065]

[0066] These light-emitting materials may be used alone or in combination of two or more.

[0067] The triplet quencher can be a compound having a lower minimum excited triplet energy than the laser oscillation material, for example, a compound having a lower minimum excited triplet energy than the laser oscillation material and a higher minimum excited singlet energy than the laser oscillation material. The triplet quencher can be selected from organic compounds having an anthracene ring, for example. Specific examples of triplet quenchers having an anthracene ring are shown below.

[0068] The host material can be an organic compound having at least one of the excited singlet energy and the excited triplet energy higher than that of the laser material. This allows the singlet and triplet excitons generated in the laser material to be confined within the molecules of the laser material, thereby lowering the threshold current density for laser oscillation. However, even if the singlet and triplet excitons cannot be sufficiently confined, they may still contribute to lowering the threshold and improving the laser characteristics. Therefore, any host material that can achieve lowering the threshold and improving the laser characteristics can be used in the present invention without any particular restrictions. In the organic solid-state semiconductor laser of the present invention, light stimulated and emitted by the laser material propagates through the light-emitting layer due to the action of an optical resonator or the like, and is emitted externally as laser light. The light emitted by the laser element may include spontaneously emitted light or amplified spontaneous emission light from the laser material, or may include light emitted from the host material, but for example, laser light is the main component. When a host material is used, the amount of the laser oscillation material contained in the light-emitting layer is, for example, 0.1 wt % or more, for example, 0.5 wt % or more, for example, 1 wt % or more, and for example, 99 wt % or less, for example, 90 wt % or less, for example, 70 wt % or less, for example, 50 wt % or less, 30 wt % or less, for example, 15 wt % or less. As the host material in the light-emitting layer, for example, an organic compound having hole transport ability and electron transport ability, preventing the emission wavelength from shifting to a longer wavelength, and having a high glass transition temperature can be used. As the host material, an appropriate host material can be selected from known host materials in consideration of the energy conditions and physical properties as described above.

[0069] Furthermore, materials (lasing materials and host materials) constituting the light-emitting layer can have hole mobility equivalent to or greater than that of BSBCz. This allows holes to efficiently accumulate near the interface between the light-emitting layer and the hole-blocking layer, allowing carrier recombination to occur more intensively in this region. Here, the hole mobility of the light-emitting layer can be greater than the electron mobility, for example, 10 times or more greater than the electron mobility. The thickness of the light-emitting layer can be, for example, 10 nm or more, for example, 30 nm or more, 50 nm or more, or 70 nm or more, or can be, for example, less than 200 nm, for example, 150 nm or less, or 100 nm or less. The thickness of the light-emitting layer can be selected, for example, from the range of 10 nm or more to less than 200 nm.

[0070] (Hole Blocking Layer) The hole blocking layer can be provided adjacent to the light-emitting layer, for example, in contact with the light-emitting layer. In a preferred embodiment of the present invention, the hole blocking layer is formed along a flat interface of the light-emitting layer. As shown in FIG. 1( b), the hole blocking layer 15 has the function of preventing positive holes (+) transported through the light-emitting layer 14 toward the hole blocking layer 15 from migrating toward the electron injection section 17 beyond the interface between the light-emitting layer 14 and the hole blocking layer 15. This causes holes to remain near the interface between the light-emitting layer 14 and the hole blocking layer 15 and recombine with negative electrons (-) that have migrated from the hole blocking layer 15 into the light-emitting layer 14. As a result, carrier recombination occurs intensively near this interface, resulting in efficient stimulated emission and laser emission with narrow peak widths in both the emission spectrum and the angular light intensity distribution. Note that, while the effects of the present invention are described herein using the laser element shown in FIG. 1 as an example, the configuration of the organic solid-state semiconductor laser of the present invention should not be construed as being limited by this specific example. To achieve this hole-blocking function, a material is selected for the hole-blocking layer such that the absolute value of the HOMO (Highest Occupied Molecular Orbital) energy of the hole-blocking layer is greater than the absolute value of the HOMO energy of the light-emitting layer. For example, the absolute value of the HOMO energy of the hole-blocking layer may be greater than the absolute value of the HOMO energy of the light-emitting layer by 0.1 eV or more, 0.2 eV or more, or 0.4 eV or more. The hole-blocking layer may also be composed of a material with low hole mobility. Specific examples of materials for the hole-blocking layer include TPBi ([1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene]) and T2T (2,4,6-tris([1,1'-biphenyl]-3-yl))-1,3,5-triazine. Alternatively, the material for the hole blocking layer can be selected from the group consisting of materials having a hole mobility equal to or lower than that of TPBi and materials having a hole mobility equal to or lower than that of T2T.The material for the hole blocking layer can be selected from compounds having a nitrogen-containing aromatic heterocycle, or from compounds having a structure in which a nitrogen-containing aromatic heterocycle is bonded to an aromatic hydrocarbon ring. Examples of nitrogen-containing aromatic heterocycles include nitrogen-containing six-membered aromatic rings such as pyridine, pyrazine, pyrimidine, pyridazine, and triazine rings; azole rings such as imidazole, thiazole, and oxazole rings; and fused rings in which these nitrogen-containing six-membered aromatic rings or azole rings are fused with an aromatic hydrocarbon ring. The aromatic hydrocarbon ring may be a single ring or a fused ring in which two or more rings are fused. In the case of a fused ring, the number of fused rings can be selected from the range of 2 to 6. Specific examples of the ring include a benzene ring and a naphthalene ring. The thickness of the hole blocking layer is, for example, 1 nm or more, such as 3 nm or more, and may be, for example, 5 nm or more or 8 nm or more, or may be, for example, 80 nm or less, for example, 30 nm or less, or 15 nm or less.

[0071] (Spacer Layer) The spacer layer used in the first embodiment is a layer provided between the hole blocking layer and the electron injection section as needed. By disposing the spacer layer between the hole blocking layer and the electron injection section, a space is created between the carrier recombination region (near the interface between the light-emitting layer and the hole blocking layer) and the electron injection section, which can prevent light generated in the carrier recombination region from being lost due to the formation of surface plasmon polaritons on the electrode surface, as well as light loss due to absorption or scattering at the electrode. The spacer layer may have a single-layer structure or a multi-layer structure. Furthermore, when one or more layers are provided between the light-emitting layer and the hole injection section, the total thickness of the spacer layer can be at least twice the total thickness of the layers between the light-emitting layer and the hole injection section, for example, at least 2.5 times or at least 3 times. For a description of the one or more layers provided between the light-emitting layer and the hole injection section, please refer to the description in the "Other Layers" section below. By forming the spacer layer thicker than the layer between the light-emitting layer and the hole injection section, the electron migration distance becomes longer than the hole migration distance, preventing electrons from moving too far within the light-emitting layer. As a result, carrier recombination can be concentrated in a narrower region. Furthermore, the spacer layer can be made of, for example, a material with a lower refractive index than the light-emitting layer. This allows light from the light-emitting layer to be efficiently reflected at the interface of the spacer layer on the light-emitting layer side, thereby more reliably suppressing light loss in the electrodes as described above. The spacer layer used in the first embodiment can be, for example, a layer (electron transport layer) with electron transport properties that can transport electrons injected from the electron injection section to the hole blocking layer. Below, an electron transport layer will be described as an example of a spacer layer.

[0072] (Electron Transport Layer) TPBi is a specific example of a material for the electron transport layer. Alternatively, the material for the electron transport layer can be selected from a group of electron-transporting compounds having electron mobility equivalent to or lower than that of TPBi. The low electron mobility of the electron transport layer prevents electrons from moving too far within the light-emitting layer, allowing carrier recombination to occur in a more concentrated area. The material for the electron transport layer can also be selected from a group of compounds having a nitrogen-containing aromatic heterocycle, for example, a group of compounds having a structure in which a nitrogen-containing aromatic heterocycle and an aromatic hydrocarbon ring are bonded. For details and specific examples of the nitrogen-containing aromatic heterocycle and the aromatic hydrocarbon ring, please refer to the description of the nitrogen-containing aromatic heterocycle and the aromatic hydrocarbon ring in the hole-blocking layer section. However, the material for the electron transport layer can be different from the material for the hole-blocking layer. In one embodiment of the present invention, the electron transport layer is a layer having a higher absolute value of HOMO energy than the light-emitting layer. Specifically, the absolute value of the HOMO energy of the electron transport layer may be larger than the absolute value of the HOMO energy of the light-emitting layer by 0.1 eV or more, for example, 0.2 eV or more. The thickness of the electron transport layer may be, for example, 10 nm or more, for example, 20 nm or more, for example, 40 nm or more, or 60 nm or more, and may be, for example, 100 nm or less, for example, 80 nm or less.

[0073] (Other Layers) The organic solid-state semiconductor laser of the first embodiment may have one or more layers between the light-emitting layer and the hole injection section, as necessary. Examples of layers provided between the light-emitting layer and the hole injection section include a hole injection layer and a hole transport layer. The hole injection layer has the function of lowering the hole injection barrier in the hole injection section, and the hole transport layer has the function of transporting holes injected from the hole injection section to the light-emitting layer side. The hole transport layer may be a hole injection transport layer having a hole injection function. Examples of materials for the hole transport layer include triazole derivatives, oxadiazole derivatives, imidazole derivatives, carbazole derivatives, indolocarbazole derivatives, polyarylalkane derivatives, pyrazoline derivatives and pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, aniline-based copolymers, and conductive polymer oligomers, particularly thiophene oligomers. For example, the material may be selected from a group of compounds consisting of porphyrin compounds, aromatic tertiary amine compounds, and styrylamine compounds, or may be selected from a group of compounds consisting of aromatic tertiary amine compounds. A specific example of a material for the hole transport layer is NPD. In addition, the material for the hole transport layer may be selected from a group of compounds having a hole mobility equivalent to or higher than that of NPD. A specific example of the material for the hole injection layer is HATCN ([dipyrazino[2,3-f:2',3'-h]quinoxaline-2,3,6,7,10,11-hexacarbonitrile]). Alternatively, the material for the hole injection layer can be selected from a group of compounds having a LUMO level or HOMO level between the Fermi level of the hole injection portion and the HOMO level of the light-emitting layer. Furthermore, a layer composed of a material having a hole mobility equivalent to or higher than that of HATCN may be provided between the light-emitting layer and the hole injection portion.

[0074] (Optical Resonator) The optical resonator has the function of propagating emitted light within the light-emitting layer. The optical resonator may be a distributed feedback (DFB) optical resonator or a distributed Bragg reflector (DBR) optical resonator that reflects light using a diffraction grating, or a Fabry-Perot optical resonator composed of a reflecting mirror and a partially reflecting mirror arranged opposite each other. The optical resonator may also be a circular diffraction grating or a striped diffraction grating that functions as a control member. The diffraction grating that constitutes the optical resonator is designed to satisfy the following Bragg equation. The diffraction grating used in the optical resonator may be any of a first-order diffraction grating where m is 1, a second-order diffraction grating where m is 2, or a third-order diffraction grating where m is 3, or may even be a higher-order diffraction grating. It may also be a mixed-order diffraction grating that combines diffraction gratings of different orders. Bragg equation: mλ Ｂｒａｇｇ = 2n ｅｆｆ Λ ｍ where m is the diffraction order, λ Ｂｒａｇｇ is the Bragg wavelength, n ｅｆｆ is the effective refractive index, Λ ｍis the period of the diffraction grating. In one embodiment of the present invention, the diffraction grating constituting the optical resonator has a periodic uneven structure in which grating protrusions and recesses (grating recesses) partitioned by the grating protrusions are periodically arranged. Such a diffraction grating may be a one-dimensional diffraction grating in which linear grating protrusions (protrusions) are arranged horizontally, a two-dimensional diffraction grating in which linear grating protrusions are arranged vertically and horizontally and intersect, a two-dimensional diffraction grating in which rectangular grating protrusions are scattered in a matrix, or a three-dimensional diffraction grating in which two-dimensional diffraction gratings are stacked vertically. Here, the diffraction grating may be arranged so that at least a portion of the grating protrusions penetrate into the light-emitting layer from the hole injection section side of the light-emitting layer. In the following description, the portion of the grating protrusion that penetrates into the light-emitting layer is referred to as the "penetration portion." The length of the penetration portion of the grating protrusion can be selected from a range shorter than the thickness of the light-emitting layer, for example, a range shorter than the thickness of the light-emitting layer by 15 nm or more. This ensures a carrier recombination region in the region where the lattice protrusions do not penetrate, allowing carrier recombination and stimulated emission to occur efficiently. Such a diffraction grating can be formed, for example, on the surface of the electrode constituting the hole injection section, facing the light-emitting layer. In this case, the lattice protrusions may be formed on the surface of the electrode facing the light-emitting layer, with the electrode surface exposed from the bottom of the lattice recesses. Alternatively, the diffraction grating can be disposed between the region of the light-emitting layer that serves as the carrier recombination region and the hole injection section. Alternatively, the base ends of the lattice protrusions of the diffraction grating can be disposed at the interface of the light-emitting layer facing the hole injection section or closer to the hole injection section than the interface, and the hole blocking layer can be disposed between the light-emitting layer and the electron injection section, adjacent to the light-emitting layer. The lattice protrusions can be formed, for example, from an insulating material. The insulating material may be an inorganic insulating material or an organic insulating material. Specific examples of insulating materials include glass, silicon dioxide, and plastic.

[0075] Second Embodiment Next, a second embodiment of the organic solid-state semiconductor laser will be described. The organic solid-state semiconductor laser of the second embodiment is configured by stacking at least a hole injection section, an electron blocking layer, a light-emitting layer, and an electron injection section in this order, and includes an optical resonator that propagates emitted light within the light-emitting layer and a control member that controls light extraction characteristics. Here, the control member may serve both as the control member and the optical resonator. That is, in one aspect of the present invention, the organic solid-state semiconductor laser of the second embodiment is configured by stacking at least a hole injection section, a light-emitting layer, a hole blocking layer, and an electron injection section in this order, and includes a control member that serves both as the control member and the optical resonator. For a description of the control member, examples of a control member that also serves as an optical resonator, and examples of other control members, please refer to the description in the above section (Control Member). The organic solid-state semiconductor laser of the second embodiment may further include a spacer layer between the electron blocking layer and the hole injection section, or one or more layers between the light-emitting layer and the electron injection section. Here, the electron blocking layer, the light-emitting layer, the spacer layer, and one or more layers disposed between the light-emitting layer and the electron injection portion can be organic layers. A specific structural example of the second embodiment is shown in Fig. 2. In Fig. 2, 61 represents a hole injection portion, 62 represents a hole transport layer, 63 represents an electron blocking layer, 64 represents a light-emitting layer, 65 represents an electron transport layer, 66 represents an electron injection layer, 67 represents an electron injection portion, and 68 represents a diffraction grating that constitutes an optical resonator. Here, the hole transport layer 62 constitutes a spacer layer, and the electron transport layer 65 and the hole injection layer 66 correspond to the above-mentioned "one or more layers disposed between the light-emitting layer and the electron injection portion."

[0076] In the organic solid-state semiconductor laser of the second embodiment, by having a circular diffraction grating or a striped diffraction grating that serves as both a control member and an optical resonator, a light intensity distribution with a sharp peak can be obtained on the light extraction surface, and when used to form pixels in a display device, optical crosstalk between adjacent pixels can be effectively suppressed or prevented. Furthermore, when a striped diffraction grating is used, light generated in the light-emitting layer can be converted into linearly polarized light and efficiently extracted from the light extraction surface.

[0077] Furthermore, the organic solid-state semiconductor laser of the second embodiment may have a partition wall or a photonic crystal material as a control member in addition to the optical resonator. In this case, the optical resonator may also function as the control member, or may not function as the control member. By using a partition wall or a photonic crystal material as the control member, a light intensity distribution with a sharp peak can be obtained on the light extraction surface, and when used to form pixels of a display device, optical crosstalk between adjacent pixels can be effectively suppressed or prevented. Furthermore, when a partition wall is used, adjacent pixels are electrically insulated from each other, so electrical crosstalk can be effectively suppressed or prevented.

[0078] Each layer and each member constituting the organic solid-state semiconductor laser of the second embodiment will be described below. For an explanation of the control member, please refer to the description in the (Control Member) section above. For an explanation of the substrate and the light-emitting layer, please refer to the descriptions in the "Substrate" and "Light-emitting Layer" sections of the first embodiment. The organic solid-state semiconductor laser of the second embodiment may have a hole injection section, an electron blocking layer, a light-emitting layer, and an electron injection section stacked in this order on a substrate, or may have an electron injection section, a light-emitting layer, an electron blocking layer, and a hole injection section stacked in this order on a substrate.

[0079] (Hole Injection Section) The hole injection section has the function of injecting holes. For example, when an electron blocking layer is provided adjacent to the hole injection section, holes are injected from the hole injection section to the electron blocking layer, and the holes transported through the electron blocking layer are injected into the light-emitting layer. Furthermore, when a spacer layer is provided between the electron blocking layer and the hole injection section and adjacent to the hole injection section, holes are injected from the hole injection section to the spacer layer, and the holes transported through the spacer layer and the electron blocking layer are injected into the light-emitting layer. In one aspect of the present invention, the hole injection section of the second embodiment is an electrode, for example, a transparent electrode. For a description and specific examples of the electrode (anode) that is the hole injection section, please refer to the description of the "hole injection section" in the first embodiment.

[0080] (Electron Injection Section) The electron injection section has the function of injecting electrons into the laser element. For example, when a light-emitting layer is provided adjacent to the electron injection section, electrons are directly injected from the electron injection section into the light-emitting layer. Furthermore, when one or more layers are present between the light-emitting layer and the electron injection section, electrons are injected from the electron injection section into one of the one or more layers adjacent to the electron injection section, and electrons transported through the one or more layers are injected into the light-emitting layer. In one aspect of the present invention, the electron injection section of the second embodiment is an electrode, for example, a metal electrode. For a description and specific examples of the electrode (cathode) that is the electron injection section, please refer to the description of the "electron injection section" in the first embodiment.

[0081] (Electron Blocking Layer) The electron blocking layer can be provided adjacent to the light-emitting layer, for example, in contact with the light-emitting layer. In a preferred embodiment of the present invention, the electron blocking layer is formed along a flat interface of the light-emitting layer. The electron blocking layer has the function of preventing electrons transported through the light-emitting layer toward the electron blocking layer from migrating toward the hole injection portion beyond the interface between the light-emitting layer and the electron blocking layer. As a result, as shown in FIG. 2, electrons (e-) are retained near the interface between the light-emitting layer and the electron blocking layer and recombine with holes that have migrated from the electron blocking layer into the light-emitting layer. As a result, carrier recombination occurs intensively near this interface, efficiently generating stimulated emission light, and laser radiation with narrow peak widths in both the emission spectrum and the angular light intensity distribution can be achieved. Note that, while the effects of the present invention are described here using the laser element shown in FIG. 2 as an example, the configuration of the organic solid-state semiconductor laser of the present invention should not be construed as being limited by this specific example. To achieve this electron blocking function, a material is selected for the electron blocking layer such that the absolute value of the LUMO (Lowest Unoccupied Molecular Orbital) energy of the electron blocking layer is smaller than the absolute value of the LUMO energy of the light-emitting layer. For example, the absolute value of the LUMO energy of the electron blocking layer may be smaller than the absolute value of the LUMO energy of the light-emitting layer by 0.1 eV or more, 0.2 eV or more, or 0.4 eV or more. The electron blocking layer may also be composed of a material with low electron mobility. A specific example of a material for the electron blocking layer is N,N'-di(1-naphthyl)-N,N'-diphenylbenzidine (NPD). Alternatively, the material for the electron blocking layer may be selected from a group of materials having electron mobility equivalent to or lower than that of NPD. The thickness of the electron blocking layer is, for example, 1 nm or more, for example, 3 nm or more, and may be, for example, 5 nm or more, or 8 nm or more, and may be, for example, 80 nm or less, or, for example, 30 nm or less, or 15 nm or less.

[0082] (Spacer Layer) The spacer layer used in the second embodiment is a layer provided between the electron blocking layer and the hole injection section as needed. By disposing the spacer layer between the electron blocking layer and the hole injection section, a space is created between the carrier recombination region (near the interface between the light-emitting layer and the electron blocking layer) and the hole injection section, which can prevent light generated in the carrier recombination region from being lost due to the formation of surface plasmon polaritons on the electrode surface, as well as light loss due to absorption or scattering at the electrode. The spacer layer may have a single-layer structure or a multi-layer structure. Furthermore, when one or more layers are provided between the light-emitting layer and the electron injection section, the total thickness of the spacer layer can be at least twice the total thickness of the layers between the light-emitting layer and the electron injection section, for example, at least 2.5 times or at least 3 times. For a description of the one or more layers provided between the light-emitting layer and the electron injection section, please refer to the description in the "Other Layers" section below. By forming the spacer layer thicker than the layer between the light-emitting layer and the electron injection section, the hole migration distance becomes longer than the electron migration distance, preventing holes from moving too far within the light-emitting layer. As a result, carrier recombination can be concentrated in a narrower region. Furthermore, the spacer layer can be made of, for example, a material with a lower refractive index than the light-emitting layer. This allows light from the light-emitting layer to be efficiently reflected at the interface of the spacer layer on the light-emitting layer side, thereby more reliably suppressing light loss in the electrodes as described above. The spacer layer used in the second embodiment can be, for example, a layer (hole transport layer) with hole transport properties that can transport holes injected from the hole injection section to the electron blocking layer. Below, a hole transport layer will be described as an example of a spacer layer.

[0083] (Hole Transport Layer) The material for the hole transport layer can be, for example, a hole transport compound having a hole mobility equal to or lower than that of HATCN. The low hole mobility of the hole transport layer prevents holes from moving too far through the light-emitting layer, allowing carrier recombination to occur in a more concentrated area. The material for the hole transport layer can be different from the material for the electron blocking layer. In one embodiment of the present invention, the hole transport layer has a smaller absolute value of LUMO energy than the light-emitting layer. Specifically, the absolute value of the LUMO energy of the hole transport layer may be 0.1 eV or more smaller than the absolute value of the LUMO energy of the light-emitting layer, for example, 0.2 eV or more smaller. The thickness of the hole transport layer is, for example, 10 nm or more, for example, 20 nm or more, and may be, for example, 40 nm or more or 60 nm or more, or may be, for example, 100 nm or less, for example, 80 nm or less.

[0084] (Other Layers) The organic solid-state semiconductor laser of the second embodiment may have one or more layers between the light-emitting layer and the electron injection section, if necessary. Examples of layers provided between the light-emitting layer and the electron injection section include an electron injection layer and an electron transport layer. The electron injection layer has the function of lowering the electron injection barrier in the electron injection section, and the electron transport layer has the function of transporting electrons injected from the electron injection section to the light-emitting layer. The electron transport layer may also be an electron injection transport layer with an electron injection function. Examples of materials for the electron transport layer include nitro-substituted fluorene derivatives, diphenylquinone derivatives, thiopyran dioxide derivatives, carbodiimides, fluorenylidenemethane derivatives, anthraquinodimethane and anthrone derivatives, and oxadiazole derivatives. Furthermore, among the above oxadiazole derivatives, thiadiazole derivatives in which the oxygen atom of the oxadiazole ring is substituted with a sulfur atom, and quinoxaline derivatives having a quinoxaline ring known as an electron-withdrawing group can also be used as electron transport materials. Furthermore, polymer materials in which these materials are introduced into the polymer chain or in which these materials form the polymer main chain can also be used. TPBi is a specific example of a material for the electron transport layer. In addition, materials for the electron transport layer can be selected from a group of compounds having electron mobility equivalent to or higher than that of TPBi.

[0085] (Optical Resonator) For a description of the optical resonator, the description of the "Optical Resonator" in the first embodiment above can be referenced, except for the description of the diffraction grating arrangement and the penetration portions of the grating projections. In the diffraction grating used in the second embodiment, for example, at least a portion of the grating projections can be arranged so as to penetrate into the light-emitting layer from the electron injection portion side of the light-emitting layer. The length of the penetration portion of the grating projections that penetrate into the light-emitting layer can be selected from a range in which the penetration length is shorter than the thickness of the light-emitting layer, for example, from a range in which the penetration length is 15 nm or more shorter than the thickness of the light-emitting layer. This ensures a carrier recombination region in the region not penetrated by the grating projections, allowing carrier recombination and stimulated emission to occur efficiently here. Such a diffraction grating can be formed, for example, on the surface of the electrode that constitutes the electron injection portion, facing the light-emitting layer. In this case, the grating projections can be formed on the surface of the electrode that faces the light-emitting layer, and the electrode surface can be exposed from the bottom of the grating depressions. Alternatively, the diffraction grating may be disposed between the region of the light-emitting layer that serves as the carrier recombination region and the electron injection section, and the base ends of the grating projections of the diffraction grating may be disposed at the interface of the light-emitting layer on the electron injection section side or closer to the electron injection section than the interface, and the electron blocking layer may be disposed between the light-emitting layer and the hole injection section and adjacent to the light-emitting layer.

[0086] The organic solid-state semiconductor lasers of the first and second embodiments may be surface-emitting laser elements that extract laser light from the surface (light extraction surface), or edge-emitting laser elements that extract laser light from the end surface (light extraction surface). Furthermore, if the laser element is a surface-emitting laser element, it may be a bottom-emission type that extracts laser light from the surface (light extraction surface) on the substrate side, or a top-emission type that extracts laser light from the surface (light extraction surface) opposite the substrate. Furthermore, the organic solid-state semiconductor lasers of the first and second embodiments may be dual-emission laser elements in which the back side is visible from the front side. Note that, although laser light may leak from surfaces other than the surface set as the light extraction surface in each type of laser element, for example, the majority of the laser light (more than 50%) is emitted from the set light extraction surface.

[0087] In an organic solid-state semiconductor laser in which the electron injection portion is located on the opposite side of the substrate across the light-emitting layer, a top-emission organic solid-state semiconductor laser can be provided by forming the electron injection portion from a material with high light transmittance. In one embodiment of the present invention, the electron injection portion is a DMD structure with high light transmittance or a thin Ag layer (for example, a thickness of 40 nm or less, e.g., 5 to 30 nm, e.g., 12 to 25 nm). Furthermore, a bottom-emission organic solid-state semiconductor laser can be provided by forming the hole injection portion from a material with high light transmittance. In one embodiment of the present invention, the hole injection portion is an ITO layer. Furthermore, a dual-emission organic solid-state semiconductor laser can be provided by forming both the electron injection portion and the hole injection portion from a material with high light transmittance. Meanwhile, in an organic solid-state semiconductor laser in which the hole injection portion is located on the opposite side of the substrate across the light-emitting layer, a top-emission organic solid-state semiconductor laser can be provided by forming the hole injection portion from a material with high light transmittance. In one embodiment of the present invention, the hole injection portion is a DMD structure with high light transmittance or an ITO layer. Furthermore, by forming the electron injection section from a material with high light transmittance, a bottom-emission organic solid-state semiconductor laser can be provided. In one embodiment of the present invention, the electron injection section has a laminated structure of ITO / Al / LiF. Here, the thicknesses of Al and LiF are selected from the range of 0.5 to 10 nm. Furthermore, by forming both the hole injection section and the electron injection section from materials with high light transmittance, a dual-emission organic solid-state semiconductor laser can be provided. Here, the term "DMD structure" is an abbreviation for dielectric-metal-dielectric structure, and refers to a laminated structure of dielectric / metal / dielectric. The DMD structure can be employed in the present invention as an electrode utilizing interference of the laminated structure. Ag or the like can be used as the metal constituting the DMD structure. Furthermore, MoO ３ , ITO, ZnS, InZnSnO, WO ３ The materials of the two dielectric layers disposed on both sides of the metal layer may be the same or different. In one embodiment of the present invention, the materials of the two dielectric layers of the DMD structure are the same. The MoO３ / Ag / MoO ３ In addition, ITO / Ag / ITO, ZnS / Ag / ZnS, ZnO / Ag / ZnO, InZnSnO / Ag / InZnSnO, ITO / Ag / WO ３ , ZnO / Ag / WO ３ , W.O. ３ / Ag / WO ３ The thicknesses of the two dielectric layers disposed on both sides of the metal layer may be the same or different.

[0088] Furthermore, by controlling the refractive index of each layer constituting the organic solid-state semiconductor laser, the light generated in the laser oscillation material can be confined within the optical resonator. This reduces the optical loss at the electrodes and lowers the laser oscillation threshold. Specifically, the refractive index of each layer can be controlled in the following manner.

[0089] In one aspect of the present invention, the organic solid-state semiconductor laser is configured as the first embodiment and has a circular diffraction grating that serves both as a control member and an optical resonator.In one aspect of the present invention, the organic solid-state semiconductor laser is configured as the first embodiment and has a circular diffraction grating that serves both as a control member and an optical resonator, and a partition or photonic crystal material as the control member.In one aspect of the present invention, the organic solid-state semiconductor laser is configured as the first embodiment and has a striped diffraction grating that serves both as a control member and an optical resonator.In one aspect of the present invention, the organic solid-state semiconductor laser is configured as the first embodiment and has a striped diffraction grating that serves both as a control member and an optical resonator, and a partition or photonic crystal material as the control member.

[0090] In one aspect of the present invention, the organic solid-state semiconductor laser is configured as the first embodiment, and the refractive index of a layer (hole blocking layer, or hole blocking layer and spacer layer) provided between the light-emitting layer and the electron injection section is smaller than that of the light-emitting layer. In another aspect of the present invention, the organic solid-state semiconductor laser is configured as the second embodiment, and the refractive index of a layer (e.g., electron injection layer or electron transport layer) provided between the light-emitting layer and the electron injection section is smaller than that of the light-emitting layer. In this organic solid-state semiconductor laser, light generated in the laser oscillation material is efficiently reflected at the interface between the light-emitting layer and the layer adjacent to the electron injection section side of the light-emitting layer, and is confined within the optical resonator (refractive index waveguiding), or gain waveguiding is formed, thereby enabling efficient laser oscillation. Furthermore, the generated laser light can be extracted by transmitting through, for example, a layer between the light-emitting layer and the hole injection section, the hole injection section, or the substrate. Therefore, the organic solid-state semiconductor laser of these aspects can be used, for example, as a bottom-emission laser element.

[0091] In one aspect of the present invention, the organic solid-state semiconductor laser is configured as the first embodiment, and the refractive index of a layer (e.g., a hole injection layer or a hole transport layer) provided between the light-emitting layer and the hole injection section is smaller than that of the light-emitting layer. In another aspect of the present invention, the organic solid-state semiconductor laser is configured as the second embodiment, and the refractive index of a layer (e.g., an electron blocking layer, or an electron blocking layer and a spacer layer) provided between the light-emitting layer and the hole injection section is smaller than that of the light-emitting layer. In this aspect of the organic solid-state semiconductor laser, light generated in the laser oscillation material is efficiently reflected at the interface between the light-emitting layer and the layer adjacent to the hole injection section side of the light-emitting layer, and is confined within the optical resonator (refractive index waveguiding), or gain waveguiding is formed, thereby enabling efficient laser oscillation. Furthermore, the generated laser light can be extracted by transmitting through, for example, a layer between the light-emitting layer and the electron injection section or the electron injection section. Therefore, the organic solid-state semiconductor laser of these aspects can be used, for example, as a top-emission laser element.

[0092] In one aspect of the present invention, the organic solid-state semiconductor laser is configured as the first embodiment, and the refractive indexes of the layer provided between the light-emitting layer and the electron injection section and the layer provided between the light-emitting layer and the hole injection section are both smaller than that of the light-emitting layer. In another aspect of the present invention, the organic solid-state semiconductor laser is configured as the second embodiment, and the refractive indexes of the layer provided between the light-emitting layer and the electron injection section and the layer provided between the light-emitting layer and the hole injection section are both smaller than that of the light-emitting layer. In this organic solid-state semiconductor laser, light generated in the laser oscillation material is efficiently reflected at interfaces between the light-emitting layer and adjacent layers on both sides thereof and confined within the optical resonator, allowing the light to propagate laterally within the light-emitting layer and efficiently generate laser oscillation. In another aspect of the present invention, the organic solid-state semiconductor laser is configured as the first or second embodiment, and the gain is high in the central portion of the lateral path of the light-emitting layer. In this organic solid-state semiconductor laser, light passing through the central portion of the lateral path is strongly amplified, so that light naturally propagates along the lateral path (high-gain region). In the organic solid-state semiconductor lasers of these aspects, it is sufficient that light propagates laterally in the light-emitting layer, and the final light extraction direction can be vertical. These organic solid-state semiconductor lasers are characterized in that, in the first embodiment, light propagates laterally, while the movement of holes proceeding vertically is hindered (blocked) by the hole blocking layer, and in the second embodiment, light propagates laterally, while the movement of electrons proceeding vertically is hindered (blocked) by the electron blocking layer.

[0093] As described above, the organic solid-state semiconductor laser of the present invention includes a hole-blocking layer or an electron-blocking layer, which causes carrier recombination to occur intensively near the interface between the light-emitting layer and the hole-blocking layer or near the interface between the light-emitting layer and the electron-blocking layer, thereby reducing the peak width of the emission spectrum and the peak width of the angular light intensity distribution. As a result, an organic solid-state semiconductor laser with excellent laser properties such as laser efficiency and monochromaticity is realized. Herein, the term "peak width of the emission spectrum" refers to the full width at half maximum (FWHM) of the most intense emission peak among the emission peaks appearing in the light intensity distribution (emission spectrum) versus wavelength, and the term "peak width of the angular light intensity distribution" refers to the full width at half maximum (FWHM) of the most intense emission peak among the emission peaks appearing in the light intensity distribution measured by changing the angle of the light-receiving element. The peak width of the emission spectrum observed in the organic solid-state semiconductor laser of the present invention is, for example, 10 nm or less, for example, 7 nm or less, for example, 5 nm or less, for example, 4 nm or less, for example, 3 nm or less, for example, 2 nm or less, or for example, 1 nm or less. The peak width of the angular light intensity distribution observed in the organic solid-state semiconductor laser of the present invention is, for example, 10° or less, for example, 7° or less, for example, 5° or less, for example, 4° or less, for example, 3° or less, for example, 2° or less, for example, 1° or less.

[0094] <Display Device> The display device of the present invention has a plurality of pixels, each of which is composed of an organic electroluminescence element with controlled light extraction characteristics or an organic solid-state semiconductor laser with a control member. For an explanation of each element constituting a pixel, please refer to the above sections <Method for controlling the light extraction characteristics of an organic electroluminescence element> and <Organic solid-state semiconductor laser>. The plurality of pixels may include a plurality of pixels of different colors, or may include a plurality of combinations of a plurality of pixels of different colors. An example of a combination of a plurality of pixels of different colors is a combination of red, green, and blue pixels.

[0095] For example, when an organic electroluminescent element or control member with controlled light extraction characteristics according to this embodiment is used as the light-emitting portion of a pixel in AR glasses or VR glasses, the following effects can be obtained. First, because the optical system of AR glasses is designed compactly, the NA (numerical aperture) of the optical system is also small. When an organic electroluminescent element or control member with controlled light extraction characteristics according to this embodiment is used as the light-emitting portion of such AR glasses, the half-width of the angular light intensity distribution peak of the emitted light from the element is narrow, allowing the emitted light to be efficiently incident on an optical system with a small NA. This improves the light capture efficiency of the optical system. Furthermore, for example, a diffraction grating may be provided in the optical system of AR glasses for the purpose of guiding light propagating through a light guide in a predetermined direction. When an organic electroluminescent element or control member with controlled light extraction characteristics according to this embodiment is used as the light-emitting portion of such AR glasses, the half-width of the emission wavelength spectrum peak of the light emitted from the element is narrow, thereby improving the diffraction efficiency of light at the diffraction grating. Furthermore, for example, when an organic electroluminescent element or control member with controlled light extraction characteristics according to this embodiment is used as the light-emitting portion of VR glasses or AR glasses, the narrow half-width of the emission wavelength spectrum peak of the light emitted by the element can suppress color bleeding (chromatic aberration) in the optical system. This improves the design freedom of the optical system, for example, by using plastic as the lens material of the optical system. For example, when an organic electroluminescent element or control member with controlled light extraction characteristics according to this embodiment is used as the light-emitting portion of AR glasses, the lateral direction of the light emitted from the light extraction surface can be controlled, allowing for relatively free design of the path of image light from the AR glasses' display to the user's field of vision. This improves the design freedom of AR glasses, for example, making them lighter and improving their design.

[0096] The features of the present invention will be explained in more detail below with reference to examples. The materials, processing details, processing procedures, etc. shown below can be modified as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below. The light-emitting characteristics of each element were evaluated using a spectrophotometer (PMA-50 manufactured by Hamamatsu Photonics) by applying a DC voltage or a rectangular pulse voltage (pulse width: 400 ns, repetition frequency: 1 kHz) to the element, and the current density-voltage characteristics were evaluated at room temperature using an integrating sphere system (A10094 manufactured by Hamamatsu Photonics).

[0097] [1] Fabrication and Evaluation of Bottom-Emission Organic Solid-State Semiconductor Laser (Example 1) First, a second-order DFB diffraction grating was formed on a glass substrate on which an anode made of indium tin oxide (ITO) with a thickness of 30 nm was formed by electron beam lithography using the following procedure. After UV ozone treatment was performed on the ITO surface, a 100 nm thick SiO2 layer was formed by sputtering. Here, the sputtering was performed under an argon pressure of 0.66 Pa, a temperature of 100°C, and an RF power of 100 W. This SiO2 ２ After cleaning the surface of the layer and performing UV ozone treatment, hexamethyldisilazane (HMDS) was dripped onto the substrate, spin-coated at 4000 rpm for 15 seconds, and then annealed at 120°C for 120 seconds. Subsequently, a resist solution (Zeon Corporation: ZEP520A-7) was dripped onto the substrate, spin-coated at 4000 rpm for 30 seconds, and then baked at 180°C for 240 seconds to form a 70 nm thick resist layer. The resist layer was irradiated with an electron beam and treated with a developer (Zeon Corporation: ZEDN50) to form a resist mask having a lattice planar shape. Subsequently, CHF was applied through the resist mask. ３ / O ２ By performing plasma etching using as a process gas, SiO ２A second-order DFB diffraction grating was formed by removing the portions of the layer not covered by the resist mask to expose the ITO surface. Here, the length of the portion of the grating projections penetrating into the light-emitting layer (penetration portion) was 70 nm. Next, each thin film was laminated on the ITO-coated substrate (DFB substrate) on which the DFB diffraction grating was formed using vacuum deposition (vacuum degree 1.5 × 10-5 Pa) according to the following procedure. HATCN was deposited to a thickness of 10 nm on the ITO and DFB diffraction grating to form a hole injection layer, and NPD was deposited to a thickness of 20 nm on top of that to form a hole transport layer. Next, BSBCz was deposited to a thickness of 90 nm to form a light-emitting layer. Next, T2T was deposited to a thickness of 10 nm to form a hole blocking layer, and TPBi was deposited to a thickness of 60 nm on top of that to form an electron transport layer. Subsequently, LiF was vapor-deposited to a thickness of 1 nm, Al was vapor-deposited thereon, and Ag was further vapor-deposited to a thickness of 100 nm to form a cathode, thereby producing a bottom-emission organic solid-state semiconductor laser (laser device 1). Finally, the fabricated organic solid-state semiconductor laser was encapsulated in a nitrogen-filled glove box using a glass lid and UV-curable epoxy resin. The energy level diagram of the fabricated laser device 1 is shown in Figure 11. In Figure 11, "HIL" represents the hole injection layer, "HTL" represents the hole transport layer, "EML" represents the emission layer, "HBL" represents the hole blocking layer, and "ETL" represents the electron transport layer.

[0098] Example 2 An organic solid-state semiconductor laser (laser element 2) was fabricated in the same manner as in Example 1, except that the thickness of each layer was changed as shown in Table 2.

[0099] Example 3 An organic solid-state semiconductor laser (laser element 3) was fabricated in the same manner as in Example 1, except that the thickness of each layer was changed as shown in Table 2, the electron transport layer was not formed, and the hole blocking layer was formed of TPBi.

[0100] Example 4 An organic solid-state semiconductor laser (laser element 4) was fabricated in the same manner as in Example 2, except that the light-emitting layer was formed by co-evaporation of BSBCz and CBP. At this time, the concentration of BSBCz was set to 5 wt %.

[0101] Comparative Example 1 An organic solid-state semiconductor laser having the same layer structure as the laser element described in WO 2018 / 147470 was fabricated by laminating each thin film by vacuum deposition on a DFB substrate fabricated using the same procedure as in Example 1. Specifically, Cs and BSBCz were co-deposited on the ITO and diffraction grating of the DFB substrate to form a 60 nm thick layer, and BSBCz was deposited thereon to a thickness of 150 nm to form an emission layer. During the co-deposition, the BSBCz concentration was set to 20 wt %. Subsequently, MoO3, Ag, and Al were deposited in thicknesses of 10 nm, 10 nm, and 90 nm, respectively, to form an anode, resulting in an organic solid-state semiconductor laser (comparative laser element 1). This organic solid-state semiconductor laser was encapsulated using the same procedure as in Example 1.

[0102]

[0103] The results of calculating the exciton density distributions for laser elements 2 and 3 and comparative laser element 1 are shown in Figure 12. In Figure 12, the horizontal axis represents the distance from the top surface (the surface facing the cathode) of the light-emitting layer, with positive values ​​representing the distance from the top surface toward the anode (in the thickness direction of the light-emitting layer) and negative values ​​representing the distance from the top surface toward the cathode (in the thickness direction of the hole-blocking layer). As shown in Figure 12, in comparative laser element 1, which does not have a hole-blocking layer, the exciton density was uniformly low throughout the light-emitting layer, suggesting that carrier recombination occurs sparsely throughout the light-emitting layer. In contrast, in laser elements 2 and 3, which have a hole-blocking layer, the exciton density near the interface between the light-emitting layer and the hole-blocking layer is significantly higher than in other regions, indicating that carrier recombination occurs concentrated near this interface.

[0104] According to the present invention, it is possible to realize an organic electroluminescence element or an organic solid-state semiconductor laser in which the polarization state of light generated in the light-emitting layer, the lateral light intensity distribution and propagation direction of light extracted from the light extraction surface, and at least one of the optical crosstalk and electrical crosstalk of the organic electroluminescence element are controlled. By using such an organic electroluminescence element or organic solid-state semiconductor laser, it is possible to realize a display device in which crosstalk is suppressed or prevented and brightness can be increased. Therefore, the present invention has a high industrial applicability.

[0105] REFERENCE SIGNS LIST 10 Substrate with hole injection section or substrate with electron injection section 11 Low refractive index layer 12 Circular diffraction grating 21, 31, 41 Hole injection section or electron injection section 22R, 32R, 42R Diffraction grating 22G, 32G, 42G Diffraction grating 22B, 32B, 42B Diffraction grating 22 Diffraction grating 22a Convex stripe section 23, 33, 43 Hole transport layer or electron transport layer 24, 34, 44 Light-emitting layer 25, 35, 45 Layered structure of hole blocking layer / electron transport layer or electron blocking layer / hole transport layer 26, 36, 46 Electron injection section or hole injection section 47 Partition wall 51, 61 Hole injection section 52 Hole injection layer 53, 62 Hole transport layer 54, 64 Light-emitting layer 55 Hole blocking layer 56, 65 Electron transport layer 57, 67 Electron injection portion 58, 68 Diffraction grating of optical resonator 63 Electron blocking layer 66 Electron injection layer

Claims

1. A method for controlling the light extraction characteristics of an organic electroluminescence device comprising: a hole injection section that injects holes; an electron injection section that injects electrons; and a light emitting layer that recombines the holes and electrons to emit light, wherein light generated in the light emitting layer propagates laterally through the light emitting layer and is extracted from a light extraction surface, the method comprising providing a recombination concentration section along the lateral direction of the light emitting layer.

2. The method according to claim 1, wherein the control of the light extraction characteristics is control of at least one of the polarization state of light generated in the light-emitting layer, the lateral light intensity distribution and lateral propagation direction of light extracted from the light extraction surface, and optical crosstalk and electrical crosstalk of the organic electroluminescent element.

3. The method according to claim 2, wherein when controlling the light intensity distribution in the lateral direction, the light intensity distribution in the depth direction is controlled in addition to the lateral direction.

4. The method according to claim 2, wherein at least one of the polarization state of light generated in the light-emitting layer, the lateral light intensity distribution and lateral propagation direction of the light extracted from the light extraction surface, and the optical crosstalk and electrical crosstalk of the organic electroluminescent element is controlled, and the full width at half maximum (FWHM) of the peak of the light intensity distribution for the wavelength of the light extracted from the light extraction surface is reduced.

5. The method according to claim 2, wherein the light extraction characteristics are controlled by providing a control member made of an insulating material having a refractive index lower than that of the light emitting layer so as to be in contact with the light emitting layer.

6. The method according to claim 2, wherein the control of the light extraction characteristics is control of the polarization state of light generated in the light emitting layer.

7. The method according to claim 6, wherein the polarization state of the light generated in said light-emitting layer is controlled by providing a striped diffraction grating in contact with said light-emitting layer.

8. The method according to claim 2, wherein the control of the light extraction characteristics is control of at least one of the lateral light intensity distribution and lateral propagation direction of the light extracted from the light extraction surface, and optical crosstalk and electrical crosstalk of the organic electroluminescent element.

9. The method according to claim 8, wherein at least one control member selected from a striped diffraction grating, a circular diffraction grating, a partition made of an insulating material having a lower refractive index than the light-emitting layer, and a photonic crystal material is provided in contact with the light-emitting layer, thereby controlling at least one of the lateral light intensity distribution and the lateral propagation direction of light extracted from the light extraction surface, and the optical crosstalk and electrical crosstalk of the organic electroluminescent element.

10. The method according to claim 2, characterized in that when the side of the light-emitting layer that will become the exciton high density region is the electron injection section side, a hole blocking layer is provided between the light-emitting layer and the electron injection section and adjacent to the light-emitting layer, and when the side of the light-emitting layer that will become the exciton high density region is the hole injection section side, an electron blocking layer is provided between the light-emitting layer and the hole injection section and adjacent to the light-emitting layer.

11. The method according to claim 2, further comprising providing a low refractive index layer having a refractive index lower than that of the light emitting layer between the light emitting layer and the hole injection section, and between the light emitting layer and the electron injection section.

12. The method according to claim 10, wherein the location of the exciton high density region in the light-emitting layer is determined by simulating the exciton density distribution in the light-emitting layer.

13. The method according to claim 10, wherein the organic electroluminescent device further comprises an optical cavity for propagating emitted light within the light-emitting layer.

14. The method according to claim 13, wherein the light extracted from the light extraction surface is laser light.

15. The method of claim 14, wherein the optical resonator comprises a diffraction grating.

16. The method according to claim 15, wherein the light extraction characteristics are controlled by providing a circular diffraction grating or a striped diffraction grating in contact with the light emitting layer, and the circular diffraction grating or the striped diffraction grating is used as a diffraction grating for the optical resonator.

17. The method of claim 15, wherein the hole blocking layer or the electron blocking layer is formed along a planar interface of the light-emitting layer.

18. The method of claim 15, wherein the diffraction grating is disposed between the exciton high density region and the hole injection portion or between the exciton high density region and the electron injection portion.

19. The method of claim 18, wherein, when a diffraction grating is present between the exciton high density region and the hole injection section, the hole blocking layer is provided between the light emitting layer and the electron injection section and adjacent to the light emitting layer, and when a diffraction grating is present between the exciton high density region and the electron injection section, the electron blocking layer is provided between the light emitting layer and the hole injection section and adjacent to the light emitting layer.

20. The method of claim 10, further comprising providing a spacer layer between at least one of the hole injection section or the electron injection section and the exciton high density region.

21. An organic electroluminescence device having controlled light extraction characteristics, produced by carrying out the method according to any one of claims 1 to 20.

22. An organic solid-state semiconductor laser with controlled light extraction characteristics, manufactured by carrying out the method of claim 14.

23. An organic electroluminescence element comprising: a hole injection section that injects holes; an electron injection section that injects electrons; a light-emitting layer disposed between the hole injection section and the electron injection section and that recombines holes and electrons to emit light; and an optical resonator that propagates the emitted light within the light-emitting layer, wherein light is extracted from a light extraction surface, and the organic electroluminescence element further comprises a hole blocking layer adjacent to the light-emitting layer on the electron injection section side of the light-emitting layer, or an electron blocking layer adjacent to the light-emitting layer on the hole injection section side of the light-emitting layer, and further comprises a control member that controls the light extraction characteristics.

24. The organic electroluminescent element according to claim 23, wherein the control of the light extraction characteristics is control of at least one of the polarization state of light generated in the light-emitting layer, the lateral light intensity distribution and lateral propagation direction of the light extracted from the light extraction surface, and the optical crosstalk and electrical crosstalk of the organic solid-state semiconductor laser.

25. The organic electroluminescence device according to claim 24, wherein the control member is made of an insulating material having a refractive index lower than that of the light-emitting layer and is provided so as to be in contact with the light-emitting layer.

26. The organic electroluminescence device according to claim 24, wherein the control member is a striped diffraction grating or a circular diffraction grating, and the striped diffraction grating and the circular diffraction grating also function as the optical resonator.

27. The organic electroluminescence device according to claim 24, wherein the control member is a striped diffraction grating, and the diffraction grating has a plurality of ridges arranged side by side along the lateral direction of the light-emitting layer.

28. The organic electroluminescence device according to claim 27, wherein the striped diffraction grating is a first-order diffraction grating.

29. The organic electroluminescent device according to claim 27, wherein the striped diffraction grating includes a second-order diffraction grating.

30. The organic electroluminescence device according to claim 29, wherein the striped diffraction grating is a second-order diffraction grating.

31. The organic electroluminescence device according to claim 24, wherein the control member comprises a circular diffraction grating including a second-order diffraction grating.

32. The organic electroluminescent device according to claim 31, wherein the circular diffraction grating is a second-order diffraction grating.

33. The organic electroluminescence device according to claim 31, wherein the circular diffraction grating is a mixed diffraction grating including a first-order diffraction grating and a second-order diffraction grating.

34. The organic electroluminescence element according to claim 24, wherein the control member comprises a partition wall surrounding the end face of the light-emitting layer, the partition wall being made of an insulating material having a refractive index lower than that of the light-emitting layer.

35. The organic electroluminescence device according to claim 24, wherein the control member comprises a photonic crystal material surrounding the light-emitting layer.

36. The organic electroluminescence device according to any one of claims 23 to 35, characterized in that a hole blocking layer is provided adjacent to the light-emitting layer on the electron injection section side of the light-emitting layer.

37. The organic electroluminescence device according to claim 36, wherein the absolute value of the HOMO energy of the hole-blocking layer is greater than the absolute value of the HOMO energy of the light-emitting layer.

38. The organic electroluminescence device according to claim 36, wherein the absolute value of the HOMO energy of the hole-blocking layer is greater than the absolute value of the HOMO energy of the light-emitting layer by 0.1 eV or more.

39. The organic electroluminescence device according to claim 36, further comprising one or more layers between the hole blocking layer and the electron injection section.

40. The organic electroluminescence device according to any one of claims 34 to 35, wherein the hole mobility of the light-emitting layer is at least 10 times greater than the electron mobility.

41. The organic electroluminescence device according to any one of claims 23 to 35, wherein the light-emitting layer contains a laser oscillation material and a dopant material.

42. The organic electroluminescence device according to any one of claims 23 to 35, characterized in that the thickness of the light-emitting layer is 10 nm or more and less than 200 nm.

43. An organic electroluminescence device according to any one of claims 23 to 35, characterized in that the half-width of the emission angle peak is 10 degrees or less, and the half-width of the emission wavelength peak is 10 nm or less.

44. The organic electroluminescence element described in any one of claims 23 to 35, wherein at least one of the electron injection section and the hole injection section is an electrode having a visible light transmittance of 10% or more.

45. The organic electroluminescence device according to any one of claims 23 to 35, wherein light generated in the light-emitting layer propagates laterally across the light-emitting layer.

46. ​​The organic electroluminescence device according to claim 45, further comprising a low refractive index layer between the light-emitting layer and the hole injection section, and between the light-emitting layer and the electron injection section, the low refractive index layer having a refractive index lower than that of the light-emitting layer.

47. The organic electroluminescent device according to claim 23, wherein the optical cavity comprises a diffraction grating.

48. The organic electroluminescence device according to claim 47, wherein the hole blocking layer or the electron blocking layer is formed along a flat interface of the light-emitting layer.

49. An organic electroluminescent device according to claim 47, wherein the base end of the diffraction grating is located at the interface of the light-emitting layer on the hole injection section side or on the hole injection section side of the interface, and the hole blocking layer is located between the light-emitting layer and the electron injection section and adjacent to the light-emitting layer.

50. An organic electroluminescent device as described in claim 47, wherein the base end of the diffraction grating is positioned at the interface of the light-emitting layer on the electron injection section side or on the electron injection section side of the interface, and the electron blocking layer is positioned between the light-emitting layer and the hole injection section and adjacent to the light-emitting layer.

51. The organic electroluminescence device according to any one of claims 22 to 35, which is a top-emission type.

52. The organic electroluminescence device according to any one of claims 22 to 35, which is a bottom-emission type.

53. The organic electroluminescence device according to any one of claims 22 to 35, which is of a dual emission type.

54. The organic electroluminescence device according to any one of claims 22 to 35, characterized in that it is an edge-emitting type.

55. The organic electroluminescence element according to any one of claims 22 to 35, characterized in that the organic electroluminescence element is an organic solid-state semiconductor laser.

56. A display device having a plurality of pixels, wherein the plurality of pixels include an organic electroluminescent element according to any one of claims 22 to 35.

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