Light-emitting devices

Abstract

To provide a light-emitting device.SOLUTION: A light-emitting device comprises a first light-emitting unit and a second light-emitting unit. An intermediate layer includes a region which is held between the first light-emitting unit and the second light-emitting unit, and the intermediate layer is provided with a function for supplying electrons to one of the first light-emitting unit and the second light-emitting unit and supplying positive holes to the other. The first light-emitting unit includes a first light-emitting layer, and the first light-emitting layer contains a first light-emitting material. The second light-emitting unit includes a second light-emitting layer, and the second light-emitting layer contains a second light-emitting material. The second light-emitting layer is provided with a first distance between the second light-emitting layer and the first light-emitting layer, and the first distance is 5 nm or more and 65 nm or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] One embodiment of the present invention relates to a light-emitting device, a light-emitting apparatus, a light-emitting module, an electronic device, or a lighting apparatus.

[0002] Note that one embodiment of the present invention is not limited to the above technical field. The technical field of one embodiment of the invention disclosed in this specification relates to an object, a method, or a manufacturing method. Alternatively, one embodiment of the present invention relates to a process, a machine, a manufacture, or a composition of matter. Therefore, more specifically, examples of the technical field of one embodiment of the present invention disclosed in this specification include a semiconductor device, a display device, a light-emitting device, a power storage device, a memory device, a driving method thereof, or a manufacturing method thereof. [Background technology]

[0003] Research and development of light-emitting devices (also called organic EL devices or organic EL elements) that utilize the organic electroluminescence (EL) phenomenon is actively underway. The basic structure of an organic EL device is a layer containing a light-emitting organic compound (hereinafter referred to as the light-emitting layer) sandwiched between a pair of electrodes. By applying a voltage to this organic EL device, light can be emitted from the light-emitting organic compound.

[0004] Examples of light-emitting organic compounds include compounds that can convert a triplet excited state into light emission (also called phosphorescent compounds or phosphorescent materials). Patent Document 1 discloses organometallic complexes containing iridium or the like as central metals as phosphorescent materials.

[0005] Image sensors are also used in a variety of applications, including personal authentication, defect analysis, medical diagnosis, and security. Image sensors use different wavelengths of light source depending on the application. Image sensors use light of various wavelengths, for example, visible light, short wavelength light such as X-rays, and long wavelength light such as near-infrared light.

[0006] In addition to display devices, applications of light-emitting devices as light sources for the image sensors described above are also being considered. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-137872 Summary of the Invention [Problem to be solved by the invention]

[0008] An object of one embodiment of the present invention is to provide a novel light-emitting device that is highly convenient or reliable, or to provide a novel light-emitting device or a novel semiconductor device.

[0009] Note that the description of these problems does not preclude the existence of other problems. Note that one embodiment of the present invention does not necessarily solve all of these problems. Note that problems other than these will become apparent from the description of the specification, drawings, claims, etc., and it is possible to extract other problems from the description of the specification, drawings, claims, etc. [Means for solving the problem]

[0010] (1) One embodiment of the present invention includes an intermediate layer, a first light-emitting unit, and a second light-emitting unit.

[0011] The intermediate layer has a region sandwiched between the first light-emitting unit and the second light-emitting unit, and has the function of supplying electrons to one of the first light-emitting unit and the second light-emitting unit and supplying holes to the other.

[0012] The first light-emitting unit comprises a first light-emitting layer, and the first light-emitting layer comprises a first light-emitting material.

[0013] The second light-emitting unit comprises a second light-emitting layer, and the second light-emitting layer comprises a second light-emitting material.

[0014] The second light-emitting layer is separated from the first light-emitting layer by a first distance D1, the first distance D1 being equal to or greater than 5 nm and equal to or less than 65 nm.

[0015] This allows a plurality of light-emitting regions (specifically, a plurality of light-emitting layers) to be closer to each other. Alternatively, optical design becomes easier. Alternatively, the degree of freedom in optical design increases. Alternatively, optical design for efficiently extracting light becomes easier. Alternatively, light can be extracted efficiently. Alternatively, an increase in driving voltage due to the use of an intermediate layer can be suppressed. As a result, a novel light-emitting device with excellent convenience and reliability can be provided.

[0016] (2) Another embodiment of the present invention includes an intermediate layer, a first light-emitting unit, a second light-emitting unit, a first electrode, a second electrode, and a function of emitting light.

[0017] The intermediate layer has a function of supplying electrons to one of the first light-emitting unit and the second light-emitting unit, and supplying holes to the other.

[0018] The first light-emitting unit comprises a region sandwiched between the first electrode and the intermediate layer, the first light-emitting unit comprises a first light-emitting layer, and the first light-emitting layer comprises a first light-emitting material.

[0019] The second light-emitting unit comprises a region sandwiched between the intermediate layer and the second electrode, the second light-emitting unit comprises a second light-emitting layer, and the second light-emitting layer comprises a second light-emitting material.

[0020] The emitted light has a spectrum with a maximum at a first wavelength EL1.

[0021] The first electrode has a higher reflectivity than the second electrode at the first wavelength EL1.

[0022] The second electrode has a higher transmittance than the first electrode at the first wavelength EL1, transmits a portion of the first wavelength EL1, and reflects another portion of the first wavelength EL1, and is separated from the first electrode by a second distance D2.

[0023] When the second distance D2 is multiplied by 1.8, it is within the range of 0.3 to 0.6 times the wavelength EL1.

[0024] (3) Another embodiment of the present invention includes an intermediate layer, a first light-emitting unit, a second light-emitting unit, a first electrode, a second electrode, a reflective film, and a light-emitting function.

[0025] The intermediate layer has a function of supplying electrons to one of the first light-emitting unit and the second light-emitting unit, and supplying holes to the other.

[0026] The first light-emitting unit comprises a region sandwiched between the first electrode and the intermediate layer, the first light-emitting unit comprises a first light-emitting layer, and the first light-emitting layer comprises a first light-emitting material.

[0027] The second light-emitting unit comprises a region sandwiched between the intermediate layer and the second electrode, the second light-emitting unit comprises a second light-emitting layer, and the second light-emitting layer comprises a second light-emitting material.

[0028] The emitted light has a spectrum with a maximum at a first wavelength.

[0029] The reflective film has a higher reflectivity at the first wavelength than the second electrode.

[0030] The first electrode comprises an area sandwiched between the first light-emitting unit and the reflective film, the first electrode having a higher transmittance than the second electrode at the first wavelength.

[0031] The second electrode transmits some light and reflects other light at the first wavelength.

[0032] a second electrode having a second distance from the reflective film; The second distance, when multiplied by 1.8, is in the range of 0.3 to 0.6 times the first wavelength.

[0033] This makes optical design easier. Or, optical design for efficiently extracting light becomes easier. Or, light can be extracted efficiently. Or, the half-width of the spectrum of the emitted light can be narrowed. Or, a microcavity structure can be formed. Or, an increase in driving voltage due to the use of an intermediate layer can be suppressed. As a result, a novel light-emitting device with excellent convenience and reliability can be provided.

[0034] (4) Another embodiment of the present invention is the light-emitting device described above, wherein the second light-emitting layer is separated from the first light-emitting layer by a first distance D1.

[0035] The first distance D1 has the relationship shown in formula (i) with the first wavelength EL1.

[0036] (Number 1) (6.3×10 -3 )×EL1≦D1≦(81.3×10 -3 )×EL1 (i)

[0037] This allows multiple light-emitting regions to be closer to each other. Alternatively, optical design becomes easier. Alternatively, the degree of freedom in optical design increases. Alternatively, optical design for efficient light extraction becomes easier. Alternatively, light can be extracted efficiently. Alternatively, an increase in driving voltage due to the use of an intermediate layer can be suppressed. As a result, a novel light-emitting device with excellent convenience and reliability can be provided.

[0038] (5) Another embodiment of the present invention is the light-emitting device, wherein the first light-emitting material, in solution, has a first emission spectrum having a maximum at the second wavelength PL1.

[0039] The second light-emitting material has, in solution, a second emission spectrum having a maximum at a third wavelength PL2.

[0040] The first wavelength EL1 has a difference of 100 nm or less from the second wavelength PL1, and the first wavelength EL1 has a difference of 100 nm or less from the third wavelength PL2.

[0041] This can increase the luminous efficiency of the light-emitting device, or allow light to be extracted efficiently, thereby providing a novel light-emitting device that is highly convenient and reliable.

[0042] (6) Another embodiment of the present invention is the above light-emitting device, in which the second light-emitting layer contains the first light-emitting material.

[0043] This can increase the luminous efficiency of the light-emitting device, or can provide high brightness, thereby providing a novel light-emitting device that is highly convenient and reliable.

[0044] (7) Another embodiment of the present invention is the light-emitting device, wherein the intermediate layer has a third distance D31 from the first light-emitting layer and a fourth distance D32 from the second light-emitting layer.

[0045] The third distance D31 is 5 nm or more, and the fourth distance D32 is 5 nm or more.

[0046] This makes it possible, for example, to distance the light-emitting layer from the intermediate layer. Alternatively, for example, it is possible to suppress a decrease in light-emitting efficiency that occurs when the light-emitting layer is brought closer to the intermediate layer. Alternatively, it is possible to increase the light-emitting efficiency of the light-emitting device. As a result, it is possible to provide a novel light-emitting device that is highly convenient and reliable.

[0047] In this specification, the EL layer refers to a layer provided between a pair of electrodes of a light-emitting device. Therefore, a light-emitting layer containing an organic compound as a light-emitting material sandwiched between electrodes is one embodiment of the EL layer.

[0048] In this specification, when substance A is dispersed in a matrix made of another substance B, substance B constituting the matrix is ​​called a host material, and substance A dispersed in the matrix is ​​called a guest material. Note that substance A and substance B may each be a single substance, or may be a mixture of two or more substances.

[0049] In this specification, the term "light-emitting device" refers to an image display device or a light source (including lighting devices). The term also includes modules in which a connector, such as an FPC (Flexible Printed Circuit) or TCP (Tape Carrier Package), is attached to a light-emitting device, modules in which a printed wiring board is provided at the end of a TCP, and modules in which an IC (Integrated Circuit) is directly mounted on a substrate on which a light-emitting device is formed using the COG (Chip On Glass) method. [Effects of the Invention]

[0050] According to one embodiment of the present invention, a novel light-emitting device that is highly convenient or reliable can be provided. Alternatively, a novel light-emitting device or a novel semiconductor device can be provided.

[0051] Note that the description of these effects does not preclude the existence of other effects. Note that one embodiment of the present invention does not necessarily have all of these effects. Note that effects other than these will become apparent from the description in the specification, drawings, claims, etc., and it is possible to extract other effects from the description in the specification, drawings, claims, etc. [Brief explanation of the drawings]

[0052] [Figure 1] 1A and 1B are diagrams illustrating the configuration of a light-emitting device according to an embodiment. [Figure 2] FIG. 2 is a diagram illustrating the configuration of the light-emitting device according to the embodiment. [Figure 3] 3A to 3C are diagrams illustrating the configuration of a light emitting device according to an embodiment. [Figure 4] 4A and 4B are diagrams illustrating the configuration of a light emitting device according to an embodiment. [Figure 5] 5A to 5E are diagrams illustrating the configuration of an electronic device according to an embodiment. [Figure 6] FIG. 6 is a diagram illustrating the configuration of a light-emitting device according to an embodiment. [Figure 7] 7A and 7B are diagrams illustrating the configuration of a light-emitting device according to an example. [Figure 8] FIG. 8 is a graph showing the current density-radiant emittance characteristics of the light-emitting device 1. As shown in FIG. [Figure 9] FIG. 9 is a graph showing the voltage-current density characteristics of the light-emitting device 1. As shown in FIG. [Figure 10] FIG. 10 is a graph showing the current density-radiant flux characteristics of the light-emitting device 1. As shown in FIG. [Figure 11] FIG. 11 is a graph showing the voltage-radiant emittance characteristics of the light-emitting device 1. As shown in FIG. [Figure 12] FIG. 12 is a graph showing the current density-external quantum efficiency characteristics of the light-emitting device 1. As shown in FIG. [Figure 13] FIG. 13 is a graph showing the emission spectrum of the light-emitting device 1. As shown in FIG. [Figure 14] FIG. 14 is a graph showing the current density-radiant emittance characteristics of the light-emitting device 2. As shown in FIG. [Figure 15] FIG. 15 is a graph showing the voltage-current density characteristics of the light-emitting device 2. As shown in FIG. [Figure 16] FIG. 16 is a graph showing the current density-radiant flux characteristics of the light-emitting device 2. As shown in FIG. [Figure 17] FIG. 17 is a graph showing the voltage-radiant emittance characteristics of the light-emitting device 2. As shown in FIG. [Figure 18] FIG. 18 is a graph showing the current density-external quantum efficiency characteristics of the light-emitting device 2. As shown in FIG. [Figure 19] FIG. 19 is a graph showing the emission spectrum of the light-emitting device 2. As shown in FIG. [Figure 20] FIG. 20 is a graph showing the current density-radiant emittance characteristics of the light-emitting device 3. As shown in FIG. [Figure 21] FIG. 21 is a graph showing the voltage-current density characteristics of the light-emitting device 3. As shown in FIG. [Figure 22] FIG. 22 is a graph showing the current density-radiant flux characteristics of the light-emitting device 3. As shown in FIG. [Figure 23] FIG. 23 is a graph showing the voltage-radiant emittance characteristics of the light-emitting device 3. As shown in FIG. [Figure 24] FIG. 24 is a graph showing the current density-external quantum efficiency characteristics of the light-emitting device 3. As shown in FIG. [Figure 25] FIG. 25 is a graph showing the emission spectrum of the light-emitting device 3. As shown in FIG. [Figure 26] FIG. 26 is a diagram illustrating the configuration of a light-emitting device according to an example. [Figure 27] FIG. 27 is a diagram illustrating the calculation results of the light-emitting device according to the example. [Figure 28] FIG. 28 shows the ultraviolet-visible absorption spectrum and emission spectrum of the organometallic complex represented by the structural formula (100). [Figure 29] FIG. 29 shows the emission spectrum of the organometallic complex represented by the structural formula (100). [Figure 30] FIG. 30 is a graph showing the current density-radiant emittance characteristics of the light-emitting device 4. As shown in FIG. [Figure 31] FIG. 31 is a graph showing the voltage-current density characteristics of the light-emitting device 4. As shown in FIG. [Figure 32] FIG. 32 is a graph showing the current density-radiant flux characteristics of the light-emitting device 4. As shown in FIG. [Figure 33] FIG. 33 is a graph showing the voltage-radiant emittance characteristics of the light-emitting device 4. As shown in FIG. [Figure 34] FIG. 34 is a graph showing the current density-external quantum efficiency characteristics of the light-emitting device 4. As shown in FIG. [Figure 35] FIG. 35 is a graph showing the emission spectrum of the light-emitting device 4. As shown in FIG. [Figure 36] FIG. 36 is a graph showing the angle dependence of the relative intensity of the light emitting device 4. As shown in FIG. [Figure 37]FIG. 37 is a graph showing the angle dependence of the normalized photon intensity of the light-emitting device 4. As shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0053] A light-emitting device according to one embodiment of the present invention includes an intermediate layer, a first light-emitting unit, and a second light-emitting unit. The intermediate layer has a region sandwiched between the first light-emitting unit and the second light-emitting unit, and functions to supply electrons to one of the first light-emitting unit and the second light-emitting unit and holes to the other. The first light-emitting unit includes a first light-emitting layer, the first light-emitting layer including a first light-emitting material. The second light-emitting unit includes a second light-emitting layer, the second light-emitting layer including a second light-emitting material. The second light-emitting layer is spaced from the first light-emitting layer by a first distance, the first distance being 5 nm to 65 nm.

[0054] This allows the multiple light-emitting regions to be closer to each other. Alternatively, optical design becomes easier. Alternatively, the degree of freedom in optical design increases. Alternatively, optical design for efficiently extracting light becomes easier. Alternatively, light can be extracted efficiently. Alternatively, an increase in driving voltage due to the use of the intermediate layer 104 can be suppressed. As a result, a novel light-emitting device that is highly convenient and reliable can be provided.

[0055] The embodiments will be described in detail with reference to the drawings. However, the present invention is not limited to the following description, and it will be readily understood by those skilled in the art that various changes in form and details can be made without departing from the spirit and scope of the present invention. Therefore, the present invention should not be interpreted as being limited to the description of the embodiments shown below. In the configuration of the invention described below, the same parts or parts having similar functions will be denoted by the same reference numerals in different drawings, and repeated explanations will be omitted.

[0056] (Embodiment 1) In this embodiment, a structure of a light-emitting device according to one embodiment of the present invention will be described with reference to FIG.

[0057] 1A and 1B are diagrams illustrating the structure of a light-emitting device according to one embodiment of the present invention, in which Fig. 1A is a cross-sectional view of the light-emitting device according to one embodiment of the present invention, and Fig. 1B is a schematic diagram illustrating the emission spectrum of the light-emitting device according to one embodiment of the present invention.

[0058] In this specification, variables that take on integer values ​​of 1 or greater may be used in codes. For example, (p) including a variable p that takes on an integer value of 1 or greater may be used as part of a code that identifies any one of up to p components. Also, for example, (m, n) including variables m and n that take on integer values ​​of 1 or greater may be used as part of a code that identifies any one of up to m×n components.

[0059] <Light-emitting device configuration example 1.> The light-emitting device described in this embodiment includes an intermediate layer 104, a light-emitting unit 103a, and a light-emitting unit 103b (see FIG. 1A).

[0060] <<Middle layer configuration example 1>> Intermediate layer 104 has a region sandwiched between light-emitting unit 103a and light-emitting unit 103b. Intermediate layer 104 also has the function of supplying electrons to one of light-emitting unit 103a or light-emitting unit 103b and supplying holes to the other. For example, it supplies electrons to light-emitting unit 103a arranged on the anode side and supplies holes to light-emitting unit 103b arranged on the cathode side. Intermediate layer 104 can also be referred to as, for example, a charge generation layer.

[0061] <Light-emitting unit configuration example 1> The light-emitting unit 103a includes a light-emitting layer 113a, which contains a first light-emitting material. The light-emitting unit 103a includes a region where electrons injected from one side recombine with holes injected from the other side. A configuration including multiple light-emitting units and intermediate layers is sometimes called a tandem light-emitting device. The first light-emitting material emits energy generated by the recombination of electrons and holes as light.

[0062] Light-emitting unit 103b includes light-emitting layer 113b, which includes a second light-emitting material.

[0063] <Emitting layer configuration example 1> The light-emitting layer 113b is separated from the light-emitting layer 113a by a distance D1. The distance D1 is 5 nm or more and 65 nm or less. Preferably, the distance D1 is 5 nm or more and 50 nm or less, and more preferably, 5 nm or more and 40 nm or less. The distance D1 is preferably 10 nm or more.

[0064] This allows a plurality of light-emitting regions (e.g., light-emitting layer 113a and light-emitting layer 113b) to be closer to each other. Alternatively, optical design becomes easier. Alternatively, the degree of freedom in optical design increases. Alternatively, optical design for efficiently extracting light becomes easier. Alternatively, light can be extracted efficiently. Alternatively, an increase in driving voltage due to the use of intermediate layer 104 can be suppressed. As a result, a novel light-emitting device with excellent convenience and reliability can be provided.

[0065] <Light-emitting device configuration example 2.> The light-emitting device described in this embodiment has an electrode 101, an electrode 102, and a function of emitting light (see FIG. 1A).

[0066] Emission spectrum The light emitted from the light-emitting device of one embodiment of the present invention has a spectrum with a maximum at a first wavelength EL1 (see FIG. 1B ). Note that when the spectrum has multiple maxima, the wavelength with the strongest maximum is set as the wavelength EL1.

[0067] <Configuration Example 1 of Electrode 101 and Electrode 102> The electrode 101 has a higher reflectivity than the electrode 102 at the wavelength EL1.

[0068] The electrode 102 has a higher transmittance than the electrode 101 at the wavelength EL1, and the electrode 102 transmits part of the light at the wavelength EL1 and reflects another part of the light.

[0069] The electrode 102 is separated from the electrode 101 by a distance D2. When the distance D2 is multiplied by 1.8, it falls within the range of 0.3 to 0.6 times the wavelength EL1.

[0070] For example, if the distance D2 is 180 nm, then (1.8 × 180) nm is 324 nm. Furthermore, if the wavelength EL1 is 800 nm, then (0.3 × 800) nm is 240 nm, and (0.6 × 800) nm is 480 nm. Therefore, 324 nm is included in the range of 240 nm to 480 nm.

[0071] This makes optical design easier. Or, optical design for efficiently extracting light becomes easier. Or, light can be extracted efficiently. Or, the half-width of the spectrum of the emitted light can be narrowed. Or, a microresonator structure can be formed. Or, an increase in driving voltage due to the use of the intermediate layer 104 can be suppressed. As a result, a novel light-emitting device with excellent convenience and reliability can be provided.

[0072] A conductive film that is transparent to light of wavelength EL1 and a film that is reflective to light of wavelength EL1 can be used in a light-emitting device.

[0073] For example, a conductive film that is translucent to light of wavelength EL1 can be used as the electrode 101, and a first film that is reflective to light of wavelength EL1 can be disposed between the electrode 101 and the light-emitting layer 113a. In other words, the reflective first film sandwiches the translucent conductive film between the electrode 101 and the light-emitting layer 113a. Alternatively, the translucent conductive film has the function of adjusting the distance between the electrode 102 and the reflective first film in addition to the function of the electrode 101. In such a configuration, the electrode 102 is separated from the reflective first film by a distance D2.

[0074] Alternatively, a conductive film that is translucent to light of wavelength EL1 can be used as the electrode 102, and a second film that is reflective to light of wavelength EL1 can be disposed so as to sandwich the electrode 102 between the electrode 102 and the light-emitting layer 113b. In other words, the reflective second film sandwiches the translucent conductive film between the electrode 102 and the light-emitting layer 113b. Alternatively, the translucent conductive film has the function of adjusting the distance between the electrode 101 and the reflective second film in addition to the function of the electrode 102. In such a configuration, the reflective second film is separated from the electrode 101 by a distance D2.

[0075] <Light-emitting device configuration example 3.> Furthermore, in the light-emitting device described in this embodiment, the distance D1 and the wavelength EL1 have the relationship shown in formula (i) (see FIG. 1A).

[0076] (Number 2) (6.3×10 -3 )×EL1≦D1≦(81.3×10 -3 )×EL1 (i)

[0077] For example, when the wavelength EL1 is 800 nm, (6.3 × 10 -3 ) × 800 nm is 5.04 nm, and (81.3 × 10 -3 )×800 nm is 65.04 nm. Therefore, when the wavelength EL1 is 800 nm, the preferable distance D1 is in the range of 5.04 nm to 65.04 nm.

[0078] This allows the multiple light-emitting regions to be closer to each other. Alternatively, optical design becomes easier. Alternatively, the degree of freedom in optical design increases. Alternatively, optical design for efficiently extracting light becomes easier. Alternatively, light can be extracted efficiently. Alternatively, an increase in driving voltage due to the use of the intermediate layer 104 can be suppressed. As a result, a novel light-emitting device that is highly convenient and reliable can be provided.

[0079] <Luminescent materials> The first light-emitting material, in solution, has a first emission spectrum having a maximum at wavelength PL1 (see FIG. 1B). If the spectrum has multiple maxima, the wavelength of the strongest maximum is set as wavelength PL1. The first emission spectrum can be measured in a solution using, for example, dichloromethane as a solvent and the first light-emitting material as a solute. Examples of solvents that can be used include ketones such as methyl ethyl ketone and cyclohexanone, fatty acid esters such as ethyl acetate, halogenated hydrocarbons such as dichlorobenzene, aromatic hydrocarbons such as toluene, xylene, mesitylene, and cyclohexylbenzene, aliphatic hydrocarbons such as cyclohexane, decalin, and dodecane, dimethylformamide (DMF), and dimethyl sulfoxide (DMSO).

[0080] The second light-emitting material has a second emission spectrum in solution, the second emission spectrum having a maximum at wavelength PL2. If the spectrum has multiple maxima, the wavelength of the most intense maximum is set as wavelength PL2.

[0081] Emission spectrum The wavelength EL1 has a difference of 100 nm or less from the wavelength PL1. Also, the wavelength EL1 has a difference of 100 nm or less from the wavelength PL2. For example, if the wavelength EL1 is 800 nm and the wavelengths PL1 and PL2 are 780 nm, the wavelength EL1 has a difference of 20 nm from the wavelength PL1.

[0082] This can increase the luminous efficiency of the light-emitting device, or allow light to be extracted efficiently, thereby providing a novel light-emitting device that is highly convenient and reliable.

[0083] <Emitting layer configuration example 2> The light-emitting layer 113b contains a first light-emitting material. The same material as the first light-emitting material can be used as the second light-emitting material.

[0084] This can increase the luminous efficiency of the light-emitting device, or can provide high brightness, thereby providing a novel light-emitting device that is highly convenient and reliable.

[0085] <<Middle layer configuration example 1>> Intermediate layer 104 is separated from light-emitting layer 113a by a distance D31, and intermediate layer 104 is separated from light-emitting layer 113b by a distance D32 (see FIG. 1A). Distance D31 is 5 nm or more, and distance D32 is 5 nm or more.

[0086] This makes it possible, for example, to distance the light-emitting layer 113a from the intermediate layer 104. Alternatively, for example, it is possible to suppress a decrease in light-emitting efficiency caused by the proximity of the light-emitting layer 113a to the intermediate layer 104. Alternatively, it is possible to increase the light-emitting efficiency of the light-emitting device. As a result, it is possible to provide a novel light-emitting device that is highly convenient and reliable.

[0087] <<Configuration Example 2 of the Middle Layer 104>> A structure containing a hole transporting material and an acceptor material (electron accepting material) can be used for the intermediate layer 104. Alternatively, a structure containing an electron transporting material and a donor material can be used for the intermediate layer 104.

[0088] Specifically, materials that can be used in the light-emitting unit (hole transport material, acceptor material, electron transport material, and donor material) can be used in the intermediate layer 104. Note that for materials that can be used in the light-emitting unit, reference can be made to the description of structural examples of the light-emitting unit described later.

[0089] By sandwiching the intermediate layer 104 between the plurality of light-emitting units, it is possible to suppress an increase in driving voltage and reduce power consumption compared to a configuration that does not use the intermediate layer 104.

[0090] <Configuration Example 2 of Electrode 101 and Electrode 102> The electrodes 101 and 102 are preferably 1×10-2 2, the electrode 101 is formed on the substrate by sputtering, and the electrode 102 is formed on the light-emitting unit by sputtering or vacuum deposition.

[0091] At least one of the electrodes 101 and 102 is translucent to the light emitted by the light-emitting device, for example, it has a transmittance of 5% or more to the light emitted by the light-emitting device.

[0092] Furthermore, for example, the reflectance of the light emitted by the light emitting device is 20% or more and 95% or less, preferably 40% or more and 70% or less.

[0093] A single or multiple conductive materials can be used as a single layer or a laminated layer for the electrodes 101 and 102. The materials listed below can be used in appropriate combination as materials for forming the electrodes 101 and 102. For example, metals, alloys, electrically conductive compounds, and mixtures thereof can be used appropriately. Specific examples include In-Sn oxide (also referred to as ITO), In-Si-Sn oxide (also referred to as ITSO), In-Zn oxide, and In-W-Zn oxide. Other examples of usable materials include aluminum (Al), titanium (Ti), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), gallium (Ga), zinc (Zn), indium (In), tin (Sn), molybdenum (Mo), tantalum (Ta), tungsten (W), palladium (Pd), gold (Au), platinum (Pt), silver (Ag), yttrium (Y), and neodymium (Nd), as well as alloys containing these metals in combination. Other examples include rare earth metals such as elements belonging to Groups 1 and 2 of the periodic table (e.g., lithium (Li), cesium (Cs), calcium (Ca), and strontium (Sr)), europium (Eu), and ytterbium (Yb), as well as alloys containing these metals in combination, graphene, and the like.

[0094] <Light-emitting unit configuration example 2> The light-emitting device described in this embodiment includes a light-emitting unit 103a and a light-emitting unit 103b.

[0095] Light-emitting unit 103a can include a hole-injection layer 111a, a hole-transport layer 112a, an emissive layer 113a, an electron-transport layer 114a, and an electron-injection layer 115a.

[0096] The light-emitting unit 103b can include a hole-transporting layer 112b, a light-emitting layer 113b, an electron-transporting layer 114b, and an electron-injecting layer 115b. The materials that can be used for the light-emitting unit 103a can also be used for the light-emitting unit 103b.

[0097] The light-emitting device described in this embodiment can be fabricated by a vacuum process such as vapor deposition or a solution process such as spin coating or inkjet printing. When a vapor deposition method is used, a physical vapor deposition (PVD) method such as sputtering, ion plating, ion beam deposition, molecular beam deposition, or vacuum deposition, or a chemical vapor deposition (CVD) method can be used. In particular, the functional layers (hole injection layer, hole transport layer, light-emitting layer, electron transport layer, electron injection layer) and the charge generation layer included in the EL layer can be formed by a vapor deposition method (vacuum deposition, etc.), a coating method (dip coating, die coating, bar coating, spin coating, spray coating, etc.), a printing method (inkjet printing, screen (stencil printing), offset (lithographic printing), flexography (relief printing), gravure printing, microcontact printing, etc.), or the like.

[0098] The materials for the functional layer and the charge generating layer are not limited to those mentioned above. For example, the functional layer may be made of a polymer compound (oligomer, dendrimer, polymer, etc.), a medium molecular weight compound (a compound between a low molecular weight and a high molecular weight: molecular weight of 400 to 4000), or an inorganic compound (quantum dot material, etc.). The quantum dot material may be a colloidal quantum dot material, an alloy quantum dot material, a core-shell quantum dot material, a core quantum dot material, etc.

[0099] [Hole injection layer and hole transport layer] For example, the hole injection layer 111a is a layer that injects holes from the anode into the light-emitting unit 103a and is a layer containing a material with high hole injection properties. The electrode 101 can be used as the anode. For example, in the light-emitting device shown in FIG. 2, the hole injection layer 111a and the hole transport layer 112a are sequentially stacked on the electrode 101 by vacuum deposition.

[0100] Examples of materials with high hole injection properties include transition metal oxides such as molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, and manganese oxide, and phthalocyanine compounds such as phthalocyanine (abbreviated as HPc) and copper phthalocyanine (abbreviated as CuPc).

[0101] Materials with high hole injection properties include 4,4',4''-tris(N,N-diphenylamino)triphenylamine (abbreviation: TDATA), 4,4',4''-tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine (abbreviation: MTDATA), 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation: DPAB), 4,4'-bis(N-{4-[N'-(3-methylphenyl)-N'-phenylamino]phenyl}-N-phenylamino)biphenyl (abbreviation: DNTPD), 1,3,5-tris[N- Aromatic amine compounds such as (4-diphenylaminophenyl)-N-phenylamino]benzene (abbreviation: DPA3B), 3-[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA1), 3,6-bis[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA2), and 3-[N-(1-naphthyl)-N-(9-phenylcarbazol-3-yl)amino]-9-phenylcarbazole (abbreviation: PCzPCN1) can be used.

[0102] Examples of materials with high hole injection properties include poly(N-vinylcarbazole) (abbreviation: PVK), poly(4-vinyltriphenylamine) (abbreviation: PVTPA), poly[N-(4-{N'-[4-(4-diphenylamino)phenyl]phenyl-N'-phenylamino}phenyl) methacrylamide] (abbreviation: PTPDMA), and poly[N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine] (abbreviation: Poly-TPD). Alternatively, polymer compounds with added acids, such as poly(3,4-ethylenedioxythiophene) / poly(styrenesulfonic acid) (abbreviation: PEDOT / PSS) and polyaniline / poly(styrenesulfonic acid) (PAni / PSS), can also be used.

[0103] A composite material containing a hole-transporting material and an acceptor material (electron-accepting material) can also be used as a material with high hole-injection properties. In this case, electrons are extracted from the hole-transporting material by the acceptor material, generating holes in the hole-injection layer 111a, which are then injected into the light-emitting layer 113a via the hole-transporting layer 112a. The hole-injection layer 111a may be formed as a single layer made of a composite material containing a hole-transporting material and an acceptor material, or may be formed by laminating the hole-transporting material and the acceptor material as separate layers.

[0104] The hole transport layer 112a transports holes injected from the electrode 101 by the hole injection layer 111a to the light-emitting layer 113a. The hole transport layer 112a is a layer containing a hole transport material. It is particularly preferable to use a hole transport material used for the hole transport layer 112a that has a HOMO level that is the same as or close to the HOMO level of the hole injection layer 111a.

[0105] The acceptor material used for the hole-injection layer 111a can be an oxide of a metal belonging to Groups 4 to 8 of the periodic table. Specific examples include molybdenum oxide, vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, tungsten oxide, manganese oxide, and rhenium oxide. Among these, molybdenum oxide is particularly preferable because it is stable in the air, has low hygroscopicity, and is easy to handle. Other organic acceptors that can be used include quinodimethane derivatives, chloranil derivatives, and hexaazatriphenylene derivatives. Examples of compounds having an electron-withdrawing group (a halogen group or a cyano group) include 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation: F4-TCNQ), chloranil, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (abbreviation: HAT-CN), 1,3,4,5,7,8-hexafluorotetracyano-naphthoquinodimethane (abbreviation: F6-TCNNQ), etc. In particular, compounds such as HAT-CN in which an electron-withdrawing group is bonded to a fused aromatic ring having multiple heteroatoms are preferred because they are thermally stable. Radialene derivatives having electron-withdrawing groups (especially halogen groups such as fluoro groups or cyano groups) are also preferred because of their extremely high electron-accepting properties. Specific examples include α,α',α''-1,2,3-cyclopropanetriylidene tris[4-cyano-2,3,5,6-tetrafluorobenzeneacetonitrile], α,α',α''-1,2,3-cyclopropanetriylidene tris[2,6-dichloro-3,5-difluoro-4-(trifluoromethyl)benzeneacetonitrile], and α,α',α''-1,2,3-cyclopropanetriylidene tris[2,3,4,5,6-pentafluorobenzeneacetonitrile].

[0106] The hole transporting material used for the hole injection layer 111a and the hole transport layer 112a is 10 -6 cm 2 A substance having a hole mobility of / Vs or more is preferred. Note that other substances can also be used as long as they have a higher hole transporting property than electron transporting property.

[0107] As the hole transporting material, a material with high hole transporting properties such as a π-electron rich heteroaromatic compound (for example, a carbazole derivative, a thiophene derivative, a furan derivative, etc.) or an aromatic amine compound (a compound having an aromatic amine skeleton) is preferred.

[0108] Examples of carbazole derivatives (compounds having a carbazole skeleton) include bicarbazole derivatives (for example, 3,3'-bicarbazole derivatives) and aromatic amine compounds having a carbazolyl group.

[0109] Specific examples of bicarbazole derivatives (for example, 3,3′-bicarbazole derivatives) include 3,3′-bis(9-phenyl-9H-carbazole) (abbreviation: PCCP), 9,9′-bis(1,1′-biphenyl-4-yl)-3,3′-bi-9H-carbazole, 9,9′-bis(1,1′-biphenyl-3-yl)-3,3′-bi-9H-carbazole, 9-(1,1′-biphenyl-3-yl)-9′-(1,1′-biphenyl-4-yl)-9H,9′H-3,3′-bicarbazole (abbreviation: mBPCCBP), and 9-(2-naphthyl)-9′-phenyl-9H,9′H-3,3′-bicarbazole (abbreviation: βNCCP).

[0110] Specific examples of aromatic amine compounds having a carbazolyl group include 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBA1BP), N-(4-biphenyl)-N-(9,9-dimethyl-9H-fluoren-2-yl)-9-phenyl-9H-carbazol-3-amine (abbreviation: PCBiF), N-(1,1'-biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluoren-2-yl], and N-(1,1'-biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluoren-2-yl]. PCBBiF, 4,4'-diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (PCBANB), 4,4'-di(1-naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (PCBNBB), 4-phenyldiphenyl-(9-phenyl-9H- N,N'-bis(9-phenylcarbazol-3-yl)-N,N'-diphenylbenzene-1,3-diamine (abbreviation: PCA2B), N,N',N''-triphenyl-N,N',N''-tris(9-phenylcarbazol-3-yl)benzene-1,3,5-triamine (abbreviation: PCA3B), 9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]fluoren-2-amine (abbreviation: PCBAF), N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]spiro-9,9'-bifluoren-2-amine (abbreviation: PCBASF), PCzPCA1, PCzPCA2, PCzPCN1, 3-[N-(4-diphenylaminophenyl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzDPA1), 3,6-bis[N-(4-diphenylaminophenyl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzDPA2), 3,Examples include 6-bis[N-(4-diphenylaminophenyl)-N-(1-naphthyl)amino]-9-phenylcarbazole (abbreviation: PCzTPN2), 2-[N-(9-phenylcarbazol-3-yl)-N-phenylamino]spiro-9,9'-bifluorene (abbreviation: PCASF), N-[4-(9H-carbazol-9-yl)phenyl]-N-(4-phenyl)phenylaniline (abbreviation: YGA1BP), N,N'-bis[4-(carbazol-9-yl)phenyl]-N,N'-diphenyl-9,9-dimethylfluorene-2,7-diamine (abbreviation: YGA2F), and 4,4',4''-tris(carbazol-9-yl)triphenylamine (abbreviation: TCTA).

[0111] In addition to the above, examples of carbazole derivatives include 3-[4-(9-phenanthryl)-phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPPn), 3-[4-(1-naphthyl)-phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPN), 1,3-bis(N-carbazolyl)benzene (abbreviation: mCP), 4,4'-di(N-carbazolyl)biphenyl (abbreviation: CBP), 3,6-bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviation: CzTP), 1,3,5-tris[4-(N-carbazolyl)phenyl]benzene (abbreviation: TCPB), and 9-[4-(10-phenyl-9-anthracenyl)phenyl]-9H-carbazole (abbreviation: CzPA).

[0112] Specific examples of thiophene derivatives (compounds having a thiophene skeleton) and furan derivatives (compounds having a furan skeleton) include compounds having a thiophene skeleton such as 4,4′,4″-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II), 2,8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-III), and 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV), as well as 4,4′,4″-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviation: DBF3P-II), and 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II).

[0113] Specific examples of the aromatic amine compound include 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB or α-NPD), N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (abbreviation: TPD), 4,4'-bis[N-(spiro-9,9'-bifluoren-2-yl)-N-phenylamino]biphenyl ( abbreviation: BSPB), 4-phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP), 4-phenyl-3'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: mBPAFLP), N-(9,9-dimethyl-9H-fluoren-2-yl)-N-{9,9-dimethyl-2-[N'-phenyl-N'-(9,9-dimethyl-9H-fluorene-2- yl)amino]-9H-fluoren-7-yl}phenylamine (abbreviation: DFLADFL), N-(9,9-dimethyl-2-diphenylamino-9H-fluoren-7-yl)diphenylamine (abbreviation: DPNF), 2-[N-(4-diphenylaminophenyl)-N-phenylamino]spiro-9,9'-bifluorene (abbreviation: DPASF), 2,7-bis[N-(4-diphenylaminophenyl)- N-phenylamino]-spiro-9,9'-bifluorene (abbreviation: DPA2SF), 4,4',4''-tris[N-(1-naphthyl)-N-phenylamino]triphenylamine (abbreviation: 1'-TNATA), TDATA, m-MTDATA, N,N'-di(p-tolyl)-N,N'-diphenyl-p-phenylenediamine (abbreviation: DTDPPA), DPAB, DNTPD, DPA3B, and the like.

[0114] As the hole transporting material, polymer compounds such as PVK, PVTPA, PTPDMA, and Poly-TPD can also be used.

[0115] The hole transporting material is not limited to the above, and various known materials can be used alone or in combination for the hole injection layer 111a and the hole transport layer 112a.

[0116] [Emitting layer] The light-emitting layer 113a is a layer containing a light-emitting material. For example, in the light-emitting device shown in Figure 2, the light-emitting layer 113a is formed on the hole-transporting layer 112a by vacuum deposition.

[0117] A light-emitting device according to one embodiment of the present invention includes a light-emitting organic compound as a light-emitting material. The light-emitting organic compound emits near-infrared light. Specifically, the maximum peak wavelength of the light emitted by the light-emitting organic compound is greater than 780 nm and less than or equal to 900 nm.

[0118] As the light-emitting organic compound, for example, it is possible to use the organometallic complex described in Embodiment 1. In addition, as the light-emitting organic compound, it is also possible to use the organometallic complex described in the examples described later.

[0119] Light-emitting layer 113a can have one or more light-emitting materials.

[0120] The light-emitting layer 113a may contain one or more organic compounds (host materials, assist materials, etc.) in addition to the light-emitting material (guest material). As the one or more organic compounds, one or both of a hole-transporting material and an electron-transporting material described in this embodiment can be used. Alternatively, as the one or more organic compounds, a bipolar material may be used.

[0121] The light-emitting material that can be used for the light-emitting layer 113a is not particularly limited, and a light-emitting material that converts singlet excitation energy into light emission in the near-infrared light region, or a light-emitting material that converts triplet excitation energy into light emission in the near-infrared light region can be used.

[0122] Examples of luminescent materials that convert singlet excitation energy into luminescence include substances that emit fluorescence (fluorescent materials), such as pyrene derivatives, anthracene derivatives, triphenylene derivatives, fluorene derivatives, carbazole derivatives, dibenzothiophene derivatives, dibenzofuran derivatives, dibenzoquinoxaline derivatives, quinoxaline derivatives, pyridine derivatives, pyrimidine derivatives, phenanthrene derivatives, and naphthalene derivatives.

[0123] Examples of light-emitting materials that convert triplet excitation energy into light include phosphorescent materials and thermally activated delayed fluorescence (TADF) materials.

[0124] Examples of phosphorescent materials include organometallic complexes (particularly iridium complexes) having a 4H-triazole skeleton, a 1H-triazole skeleton, an imidazole skeleton, a pyrimidine skeleton, a pyrazine skeleton, or a pyridine skeleton; organometallic complexes (particularly iridium complexes) having a phenylpyridine derivative having an electron-withdrawing group as a ligand; platinum complexes; and rare earth metal complexes.

[0125] The light-emitting device of one embodiment of the present invention may include a light-emitting material other than the light-emitting material that emits near-infrared light. For example, the light-emitting device of one embodiment of the present invention may include a light-emitting material that emits visible light (red, blue, green, etc.) in addition to the light-emitting material that emits near-infrared light.

[0126] As the organic compound (host material, assist material, etc.) used in the light-emitting layer 113a, one or more substances having an energy gap larger than the energy gap of the light-emitting material can be selected and used.

[0127] When the light-emitting material used for the light-emitting layer 113a is a fluorescent material, an organic compound used in combination with the light-emitting material is preferably an organic compound having a high energy level in a singlet excited state and a low energy level in a triplet excited state.

[0128] Although some of the examples overlap with those above, specific examples of organic compounds are shown below from the viewpoint of preferable combinations with light-emitting materials (fluorescent materials, phosphorescent materials).

[0129] When the light-emitting material is a fluorescent material, examples of organic compounds that can be used in combination with the light-emitting material include condensed polycyclic aromatic compounds such as anthracene derivatives, tetracene derivatives, phenanthrene derivatives, pyrene derivatives, chrysene derivatives, and dibenzo[g,p]chrysene derivatives.

[0130] Specific examples of organic compounds (host materials) used in combination with fluorescent materials include 9-phenyl-3-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: PCzPA), 3,6-diphenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: DPCzPA), PCPN, 9,10-diphenylanthracene (abbreviation: DPAnth), and N,N-diphenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: CzA1PA). , 4-(10-phenyl-9-anthryl)triphenylamine (abbreviation: DPhPA), 4-(9H-carbazol-9-yl)-4'-(10-phenyl-9-anthryl)triphenylamine (abbreviation: YGAPA), N,9-diphenyl-N-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: PCAPA), N,9-diphenyl-N-{4-[4-(10-phenyl-9-anthryl)phenyl]phenyl}-9H-carbazol-3-amine (abbreviation: PCAPBA), N-(9,10-diphenyl) (phenyl-2-anthryl)-N,9-diphenyl-9H-carbazol-3-amine (abbreviation: 2PCAPA), 6,12-dimethoxy-5,11-diphenylchrysene, N,N,N',N',N'',N'',N''',N'''-octaphenyldibenzo[g,p]chrysene-2,7,10,15-tetraamine (abbreviation: DBC1), CzPA, 7-[4-(10-phenyl-9-anthryl)phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA), 6-[3-(9,10-diphenyl-2-anthryl)phenyl] -benzo[b]naphtho[1,2-d]furan (abbreviation: 2mBnfPPA), 9-phenyl-10-{4-(9-phenyl-9H-fluoren-9-yl)-biphenyl-4'-yl}-anthracene (abbreviation: FLPPA), 9,10-bis(3,5-diphenylphenyl)anthracene (abbreviation: DPPA), 9,10-di(2-naphthyl)anthracene (abbreviation: DNA), 2-tert-butyl-9,10-di(2-naphthyl)anthracene (abbreviation: t-BuDNA), 9,9'-bianthryl (abbreviation: BANT), 9,9'-(stilbene-3,Examples include 3'-diyl)diphenanthrene (abbreviated as DPNS), 9,9'-(stilbene-4,4'-diyl)diphenanthrene (abbreviated as DPNS2), 1,3,5-tri(1-pyrenyl)benzene (abbreviated as TPB3), 5,12-diphenyltetracene, and 5,12-bis(biphenyl-2-yl)tetracene.

[0131] When the light-emitting material is a phosphorescent material, an organic compound having a triplet excitation energy greater than the triplet excitation energy (energy difference between the ground state and the triplet excited state) of the light-emitting material may be selected as the organic compound to be used in combination with the light-emitting material.

[0132] When a plurality of organic compounds (e.g., a first host material and a second host material (or assist material)) are used in combination with a light-emitting material to form an exciplex, it is preferable to use these plurality of organic compounds in combination with a phosphorescent material (particularly an organometallic complex).

[0133] With this structure, light emission can be efficiently obtained using Exciplex-Triplet Energy Transfer (ExTET), which is energy transfer from an exciplex to a light-emitting material. It is preferable to combine a plurality of organic compounds that easily form an exciplex, and it is particularly preferable to combine a compound that easily accepts holes (hole transport material) with a compound that easily accepts electrons (electron transport material). Specific examples of the hole transport material and the electron transport material include the materials described in this embodiment. This structure simultaneously achieves high efficiency, low voltage, and long life for a light-emitting device.

[0134] When the light-emitting material is a phosphorescent material, examples of organic compounds that can be used in combination with the light-emitting material include aromatic amine compounds, carbazole derivatives, dibenzothiophene derivatives, dibenzofuran derivatives, zinc- or aluminum-based metal complexes, oxadiazole derivatives, triazole derivatives, benzimidazole derivatives, quinoxaline derivatives, dibenzoquinoxaline derivatives, pyrimidine derivatives, triazine derivatives, pyridine derivatives, bipyridine derivatives, and phenanthroline derivatives.

[0135] Among the above, specific examples of the aromatic amine compounds (compounds having an aromatic amine skeleton), carbazole derivatives, dibenzothiophene derivatives (thiophene derivatives), and dibenzofuran derivatives (furan derivatives), which are organic compounds with high hole-transporting properties, are the same as the specific examples of the hole-transporting materials shown above.

[0136] Specific examples of zinc- or aluminum-based metal complexes, which are organic compounds with high electron-transporting properties, include metal complexes having a quinoline skeleton or a benzoquinoline skeleton, such as tris(8-quinolinolato)aluminum(III) (abbreviation: Alq), tris(4-methyl-8-quinolinolato)aluminum(III) (abbreviation: Almq3), bis(10-hydroxybenzo[h]quinolinato)beryllium(II) (abbreviation: BeBq2), bis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminum(III) (abbreviation: BAlq), and bis(8-quinolinolato)zinc(II) (abbreviation: Znq).

[0137] In addition, metal complexes having oxazole or thiazole ligands, such as bis[2-(2-benzoxazolyl)phenolato]zinc(II) (abbreviation: ZnPBO) and bis[2-(2-benzothiazolyl)phenolato]zinc(II) (abbreviation: ZnBTZ), can also be used.

[0138] Specific examples of organic compounds with high electron transport properties, such as oxadiazole derivatives, triazole derivatives, benzimidazole derivatives, quinoxaline derivatives, dibenzoquinoxaline derivatives, and phenanthroline derivatives, include 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl-1 ,3,4-oxadiazol-2-yl)phenyl]-9H-carbazole (abbreviation: CO11), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviation: TAZ), 3-(4-tert-butylphenyl)-4-(4-ethylphenyl)-5-(4-biphenylyl)-1,2,4-triazole (abbreviation: p-EtTAZ), 2,2',2''-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TPBI), 2-[3-( Dibenzothiophen-4-yl)phenyl]-1-phenyl-1H-benzimidazole (abbreviation: mDBTBIm-II), 4,4'-bis(5-methylbenzoxazol-2-yl)stilbene (abbreviation: BzOs), bathophenanthroline (abbreviation: Bphen), bathocuproine (abbreviation: BCP), 2,9-bis(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviation: NBphen), 2-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBT PDBq-II), 2-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviated as 2mDBTBPDBq-II), 2-[3'-(9H-carbazol-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviated as 2mCzBPDBq), 2-[4-(3,6-diphenyl-9H-carbazol-9-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviated as 2CzPDBq-III), 7-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviated as 7mDBTPDBq-II), and 6-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviated as 6mDBTPDBq-II).

[0139] Specific examples of heterocyclic compounds having a diazine skeleton, heterocyclic compounds having a triazine skeleton, and heterocyclic compounds having a pyridine skeleton, which are organic compounds with high electron transport properties, include 4,6-bis[3-(phenanthrene-9-yl)phenyl]pyrimidine (abbreviation: 4,6mPnP2Pm), 4,6-bis[3-(4-dibenzothienyl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II), 4,6-bis[3-(9H-carbazol-9-yl)phenyl]pyrimidine (abbreviation: 4,6mCzP2Pm), 2-{4-[3-(N-phenyl-9H -carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), 9-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9'-phenyl-2,3'-bi-9H-carbazole (abbreviation: mPCCzPTzn-02), 3,5-bis[3-(9H-carbazol-9-yl)phenyl]pyridine (abbreviation: 35DCzPPy), 1,3,5-tri[3-(3-pyridyl)phenyl]benzene (abbreviation: TmPyPB), and the like.

[0140] As organic compounds with high electron transport properties, polymer compounds such as poly(2,5-pyridinediyl) (abbreviation: PPy), poly[(9,9-dihexylfluorene-2,7-diyl)-co-(pyridine-3,5-diyl)] (abbreviation: PF-Py), and poly[(9,9-dioctylfluorene-2,7-diyl)-co-(2,2'-bipyridine-6,6'-diyl)] (abbreviation: PF-BPy) can also be used.

[0141] TADF materials are materials that can upconvert (reverse intersystem crossing) a triplet excited state to a singlet excited state with a small amount of thermal energy, and efficiently emit light (fluorescence) from the singlet excited state. The conditions for efficiently obtaining thermally activated delayed fluorescence include an energy difference between the triplet excited level and the singlet excited level of 0 eV or more and 0.2 eV or less, preferably 0 eV or more and 0.1 eV or less. The delayed fluorescence in TADF materials refers to light emission that has a spectrum similar to that of normal fluorescence but has a significantly long lifetime. The lifetime is approximately 10 -6 seconds or more, preferably 10 -3 More than a second.

[0142] Examples of TADF materials include fullerenes and their derivatives, acridine derivatives such as proflavine, eosin, etc. Also included are metal-containing porphyrins containing magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), or palladium (Pd). Examples of metal-containing porphyrins include protoporphyrin-tin fluoride complex (abbreviation: SnF2(Proto IX)), mesoporphyrin-tin fluoride complex (abbreviation: SnF2(Meso IX)), hematoporphyrin-tin fluoride complex (abbreviation: SnF2(Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride complex (abbreviation: SnF2(Copro III-4Me)), octaethylporphyrin-tin fluoride complex (abbreviation: SnF2(OEP)), etioporphyrin-tin fluoride complex (abbreviation: SnF2(Etio I)), and octaethylporphyrin-platinum chloride complex (abbreviation: PtCl2OEP).

[0143] Other examples include 2-(biphenyl-4-yl)-4,6-bis(12-phenylindolo[2,3-a]carbazol-11-yl)-1,3,5-triazine (abbreviated as PIC-TRZ), PCCzPTzn, 2-[4-(10H-phenoxazin-10-yl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviated as PXZ-TRZ), 3-[4-(5-phenyl-5,10-dihydrophenazin-10-yl)phenyl]-4,5-diphenyl-1,2,4-triazole (abbreviated as PXZ-TRZ), and Heterocyclic compounds having a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring can be used, such as bis[4-(9,9-dimethyl-9,10-dihydroacridine)phenyl]sulfone (abbreviation: DMAC-DPS), and 10-phenyl-10H,10'H-spiro[acridine-9,9'-anthracene]-10'-one (abbreviation: ACRSA). Substances in which a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring are directly bonded are particularly preferred because the donor properties of the π-electron-rich heteroaromatic ring and the acceptor properties of the π-electron-deficient heteroaromatic ring are both enhanced, resulting in a smaller energy difference between the singlet excited state and the triplet excited state.

[0144] When a TADF material is used, it can be used in combination with other organic compounds, particularly with the host material, hole transport material, and electron transport material described above.

[0145] The above materials can be used in combination with low-molecular-weight or high-molecular-weight materials to form the light-emitting layer 113a. For film formation, known methods (such as vapor deposition, coating, or printing) can be used as appropriate.

[0146] [Electron transport layer] The electron transport layer 114a is a layer that transports electrons injected from the electrode 102 to the light-emitting layer 113a by the electron injection layer 115a. The electron transport layer 114a is a layer that contains an electron transport material. The electron transport material used for the electron transport layer 114a is 1×10 -6cm 2 A substance having an electron mobility of 1 / Vs or higher is preferred. Note that other substances can also be used as long as they have a higher electron transporting property than hole transporting property. For example, in the light-emitting device shown in FIG. 2, the electron-transporting layer 114a is formed on the light-emitting layer 113a.

[0147] Examples of the electron-transporting material that can be used include metal complexes having a quinoline skeleton, metal complexes having a benzoquinoline skeleton, metal complexes having an oxazole skeleton, and metal complexes having a thiazole skeleton, as well as materials with high electron-transporting properties, such as oxadiazole derivatives, triazole derivatives, imidazole derivatives, oxazole derivatives, thiazole derivatives, phenanthroline derivatives, quinoline derivatives having a quinoline ligand, benzoquinoline derivatives, quinoxaline derivatives, dibenzoquinoxaline derivatives, pyridine derivatives, bipyridine derivatives, pyrimidine derivatives, and π-electron-deficient heteroaromatic compounds including nitrogen-containing heteroaromatic compounds.

[0148] As specific examples of the electron transporting material, the materials shown above can be used.

[0149] [Electron injection layer] The electron injection layer 115a is a layer containing a substance with high electron injection properties. For example, in the light-emitting device shown in Figure 2, the electron injection layer 115a is formed on the electron transport layer 114a by vacuum deposition.

[0150] The electron injection layer 115a may contain lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF), lithium oxide (LiO x ) or alkaline earth metals, or compounds thereof, can be used. Rare earth metal compounds, such as erbium fluoride (ErF3), can also be used. Electrides can also be used for the electron injection layer 115a. Examples of electrides include a substance in which a high concentration of electrons is added to a mixed oxide of calcium and aluminum. The above-mentioned substances constituting the electron transport layer 114a can also be used.

[0151] The electron-injection layer 115a may also be formed using a composite material containing an electron-transporting material and a donor material (electron-donating material). Such a composite material has excellent electron-injecting and electron-transporting properties because electrons are generated in the organic compound by the electron donor. In this case, the organic compound is preferably a material that is excellent in transporting the generated electrons. Specifically, the electron-transporting materials (metal complexes, heteroaromatic compounds, etc.) used in the electron-transporting layer 114a described above can be used. The electron donor may be any substance that exhibits electron-donating properties to the organic compound. Specifically, alkali metals, alkaline earth metals, and rare earth metals are preferred, such as lithium, cesium, magnesium, calcium, erbium, and ytterbium. Alkali metal oxides and alkaline earth metal oxides are preferred, such as lithium oxide, calcium oxide, and barium oxide. A Lewis base such as magnesium oxide can also be used. An organic compound such as tetrathiafulvalene (TTF) can also be used.

[0152] Note that this embodiment mode can be appropriately combined with other embodiment modes described in this specification.

[0153] (Embodiment 2) In this embodiment, a structure of a light-emitting device according to one embodiment of the present invention will be described with reference to FIGS.

[0154] 3A and 3B are diagrams illustrating a structure of a light-emitting device according to one embodiment of the present invention, in which Fig. 3A is a top view of a light-emitting device according to one embodiment of the present invention, and Fig. 3B is a cross-sectional view of the light-emitting device taken along the cutting lines X1-Y1 and X2-Y2 shown in Fig. 3A.

[0155] 4A and 4B are diagrams illustrating a structure of a light-emitting device according to one embodiment of the present invention, in which Fig. 4A is a top view of a light-emitting device according to one embodiment of the present invention, and Fig. 4B is a cross-sectional view of the light-emitting device taken along line AA' in Fig. 4A.

[0156] <Configuration example 1 of light-emitting device> 3A to 3C can be used, for example, in a lighting device. The light emitting device may be a bottom emission, top emission, or dual emission device.

[0157] 3B includes a substrate 490a, a substrate 490b, a conductive layer 406, a conductive layer 416, an insulating layer 405, an organic EL device 450 (a first electrode 401, an EL layer 402, and a second electrode 403), and an adhesive layer 407. The organic EL device 450 can also be referred to as a light-emitting element, an organic EL element, a light-emitting device, or the like. The EL layer 402 preferably includes, in its light-emitting layer, the organometallic complex described in Embodiment 1 as a light-emitting organic compound.

[0158] Organic EL device 450 has a first electrode 401 on a substrate 490a, an EL layer 402 on the first electrode 401, and a second electrode 403 on the EL layer 402. Organic EL device 450 is encapsulated by substrate 490a, adhesive layer 407, and substrate 490b.

[0159] The ends of the first electrode 401, the conductive layer 406, and the conductive layer 416 are covered with an insulating layer 405. The conductive layer 406 is electrically connected to the first electrode 401, and the conductive layer 416 is electrically connected to the second electrode 403. The conductive layer 406, covered with the insulating layer 405 via the first electrode 401, functions as an auxiliary wiring and is electrically connected to the first electrode 401. Having an auxiliary wiring electrically connected to the electrode of the organic EL device 450 is preferable because it can suppress voltage drops caused by electrode resistance. The conductive layer 406 may be provided on the first electrode 401. Furthermore, an auxiliary wiring electrically connected to the second electrode 403 may be provided on the insulating layer 405 or the like.

[0160] The substrate 490a and the substrate 490b can each be made of glass, quartz, ceramic, sapphire, organic resin, etc. Using a flexible material for the substrate 490a and the substrate 490b can increase the flexibility of the display device.

[0161] The light-emitting surface of the light-emitting device may be provided with a light extraction structure to increase the light extraction efficiency, an antistatic film to prevent dust from adhering, a water-repellent film to prevent dirt from adhering, a hard coat film to prevent scratches from occurring during use, an impact absorbing layer, etc.

[0162] Examples of insulating materials that can be used for the insulating layer 405 include resins such as acrylic resins and epoxy resins, and inorganic insulating materials such as silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, and aluminum oxide.

[0163] The adhesive layer 407 can be made of various curable adhesives, such as a photo-curable adhesive (e.g., an ultraviolet curable adhesive), a reactive curable adhesive, a thermosetting adhesive, or an anaerobic adhesive. Examples of such adhesives include epoxy resin, acrylic resin, silicone resin, phenolic resin, polyimide resin, imide resin, PVC (polyvinyl chloride) resin, PVB (polyvinyl butyral) resin, and EVA (ethylene vinyl acetate) resin. In particular, a material with low moisture permeability, such as epoxy resin, is preferable. Alternatively, a two-component resin may be used. Alternatively, an adhesive sheet or the like may be used.

[0164] The light-emitting device shown in FIG. 3C includes barrier layer 490c, conductive layer 406, conductive layer 416, insulating layer 405, organic EL device 450, adhesive layer 407, barrier layer 423, and substrate 490b.

[0165] Barrier layer 490c shown in FIG. 3C includes substrate 420, adhesive layer 422, and insulating layer 424 with high barrier properties.

[0166] 3C, organic EL device 450 is disposed between insulating layer 424 with high barrier properties and barrier layer 423. Therefore, even if a resin film with relatively low waterproof properties is used for substrate 420 and substrate 490b, it is possible to prevent impurities such as water from entering the organic EL device and shortening its lifespan.

[0167] Substrate 420 and substrate 490b may each be made of, for example, polyester resin such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN), polyacrylonitrile resin, acrylic resin, polyimide resin, polymethyl methacrylate resin, polycarbonate (PC) resin, polyethersulfone (PES) resin, polyamide resin (nylon, aramid, etc.), polysiloxane resin, cycloolefin resin, polystyrene resin, polyamideimide resin, polyurethane resin, polyvinyl chloride resin, polyvinylidene chloride resin, polypropylene resin, polytetrafluoroethylene (PTFE) resin, ABS resin, cellulose nanofiber, etc. Substrate 420 and substrate 490b may also be made of glass having a thickness sufficient to provide flexibility.

[0168] An inorganic insulating film is preferably used as the insulating layer 424 having high barrier properties. Examples of inorganic insulating films that can be used include a silicon nitride film, a silicon oxynitride film, a silicon oxide film, a silicon nitride oxide film, an aluminum oxide film, and an aluminum nitride film. Alternatively, a hafnium oxide film, an yttrium oxide film, a zirconium oxide film, a gallium oxide film, a tantalum oxide film, a magnesium oxide film, a lanthanum oxide film, a cerium oxide film, a neodymium oxide film, or the like may be used. Two or more of the above insulating films may be stacked.

[0169] The barrier layer 423 preferably has at least one inorganic film. For example, the barrier layer 423 can have a single inorganic film structure or a laminated structure of an inorganic film and an organic film. The inorganic insulating film described above is suitable as the inorganic film. An example of the laminated structure is a structure in which a silicon oxynitride film, a silicon oxide film, an organic film, a silicon oxide film, and a silicon nitride film are formed in this order. By forming the protective layer into a laminated structure of an inorganic film and an organic film, impurities (typically, hydrogen, water, etc.) that may enter the organic EL device 450 can be suitably suppressed.

[0170] The insulating layer 424 and the organic EL device 450, which have high barrier properties, can be formed directly on a flexible substrate 420. In this case, the adhesive layer 422 is not necessary. Alternatively, the insulating layer 424 and the organic EL device 450 can be formed on a rigid substrate via a release layer and then transferred to the substrate 420. For example, the release layer may be applied with heat, force, laser light, or the like to peel the insulating layer 424 and the organic EL device 450 from the rigid substrate, and then the substrate 420 may be attached using the adhesive layer 422 to transfer the insulating layer to the substrate 420. Examples of the release layer include a laminated structure of inorganic films including a tungsten film and a silicon oxide film, and organic resin films such as polyimide. When a rigid substrate is used, the insulating layer 424 can be formed at a higher temperature than when a resin substrate is used, resulting in a dense insulating film with extremely high barrier properties.

[0171] <Configuration Example 2 of Light-Emitting Device> The light-emitting device of one embodiment of the present invention can be a passive matrix type or an active matrix type. An active matrix type light-emitting device will be described with reference to FIG.

[0172] The active matrix light-emitting device shown in FIGS. 4A and 4B includes a pixel portion 302, a circuit portion 303, a circuit portion 304a, and a circuit portion 304b.

[0173] The circuit portion 303, the circuit portion 304a, and the circuit portion 304b can function as a scan line driver circuit (gate driver) or a signal line driver circuit (source driver), or may be a circuit that electrically connects an external gate driver or source driver to the pixel portion 302.

[0174] A lead wiring 307 is provided on the first substrate 301. The lead wiring 307 is electrically connected to an FPC 308, which is an external input terminal. The FPC 308 transmits external signals (e.g., video signals, clock signals, start signals, reset signals, etc.) and potentials to the circuit portion 303, the circuit portion 304a, and the circuit portion 304b. A printed wiring board (PWB) may be attached to the FPC 308. The configuration shown in FIGS. 4A and 4B can also be referred to as a light-emitting module having a light-emitting device (or light-emitting apparatus) and an FPC.

[0175] The pixel portion 302 has a plurality of pixels each having an organic EL device 317, a transistor 311, and a transistor 312. The transistor 312 is electrically connected to a first electrode 313 of the organic EL device 317. The transistor 311 functions as a switching transistor. The transistor 312 functions as a current control transistor. Note that the number of transistors included in each pixel is not particularly limited and can be appropriately provided as needed.

[0176] The circuit portion 303 has a plurality of transistors including a transistor 309, a transistor 310, etc. The circuit portion 303 may be formed of a circuit including transistors of the same conductivity type (either N-type or P-type), or may be formed of a CMOS circuit including N-type transistors and P-type transistors. The circuit portion 303 may also have a configuration including an external driver circuit.

[0177] The structure of the transistor included in the light-emitting device of this embodiment is not particularly limited. For example, a planar transistor, a staggered transistor, an inverted staggered transistor, or the like can be used. Furthermore, either a top-gate or bottom-gate transistor structure may be used. Alternatively, gates may be provided above and below a semiconductor layer in which a channel is formed.

[0178] The crystallinity of a semiconductor material used for a transistor is not particularly limited, and any of an amorphous semiconductor and a crystalline semiconductor (a microcrystalline semiconductor, a polycrystalline semiconductor, a single crystal semiconductor, or a semiconductor having a crystalline region in part) may be used. The use of a crystalline semiconductor is preferable because it can suppress deterioration of transistor characteristics.

[0179] The semiconductor layer of the transistor preferably contains a metal oxide (also referred to as an oxide semiconductor). Alternatively, the semiconductor layer of the transistor may contain silicon. Examples of silicon include amorphous silicon and crystalline silicon (such as low-temperature polysilicon and single-crystal silicon).

[0180] The semiconductor layer preferably contains, for example, indium, M (wherein M is one or more elements selected from gallium, aluminum, silicon, boron, yttrium, tin, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, and magnesium), and zinc. In particular, M is preferably one or more elements selected from aluminum, gallium, yttrium, and tin.

[0181] In particular, it is preferable to use an oxide containing indium (In), gallium (Ga), and zinc (Zn) (also referred to as IGZO) as the semiconductor layer.

[0182] When the semiconductor layer is an In-M-Zn oxide, the sputtering target used to deposit the In-M-Zn oxide preferably has an atomic ratio of In equal to or greater than the atomic ratio of M. Examples of atomic ratios of metal elements in such sputtering targets include In:M:Zn=1:1:1, In:M:Zn=1:1:1.2, In:M:Zn=2:1:3, In:M:Zn=3:1:2, In:M:Zn=4:2:3, In:M:Zn=4:2:4.1, In:M:Zn=5:1:6, In:M:Zn=5:1:7, In:M:Zn=5:1:8, In:M:Zn=6:1:6, and In:M:Zn=5:2:5.

[0183] The transistors included in the circuit portion 303, the circuit portion 304a, and the circuit portion 304b may have the same structure or different structures from the transistors included in the pixel portion 302. The transistors included in the circuit portion 303, the circuit portion 304a, and the circuit portion 304b may all have the same structure or may have two or more types. Similarly, the transistors included in the pixel portion 302 may all have the same structure or may have two or more types.

[0184] The end of the first electrode 313 is covered with an insulating layer 314. The insulating layer 314 can be made of an organic compound such as a negative photosensitive resin or a positive photosensitive resin (acrylic resin), or an inorganic compound such as silicon oxide, silicon oxynitride, or silicon nitride. The upper or lower end of the insulating layer 314 preferably has a curved surface. This can improve the coverage of a film formed on the insulating layer 314.

[0185] An EL layer 315 is provided on the first electrode 313, and a second electrode 316 is provided on the EL layer 315. The EL layer 315 has a light-emitting layer, a hole-injection layer, a hole-transport layer, an electron-transport layer, an electron-injection layer, a charge-generation layer, and the like.

[0186] The plurality of transistors and the plurality of organic EL devices 317 are sealed by the first substrate 301, the second substrate 306, and the sealant 305. A space 318 surrounded by the first substrate 301, the second substrate 306, and the sealant 305 may be filled with an inert gas (nitrogen, argon, etc.) or an organic substance (including the sealant 305).

[0187] Epoxy resin or glass frit can be used for the sealant 305. Note that it is preferable to use a material that is as moisture- and oxygen-impermeable as possible for the sealant 305. When glass frit is used as the sealant, it is preferable that the first substrate 301 and the second substrate 306 are glass substrates in terms of adhesiveness.

[0188] This embodiment mode can be combined with other embodiment modes as appropriate.

[0189] (Embodiment 3) In this embodiment, electronic devices in which the light-emitting device of one embodiment of the present invention can be used will be described with reference to FIGS.

[0190] FIG. 5A shows a biometric authentication device for finger veins, and includes a housing 911, a light source 912, a detection stage 913, and the like. By placing a finger on the detection stage 913, the shape of the veins can be imaged. A light source 912 that emits near-infrared light is provided above the detection stage 913, and an imaging device 914 is provided below it. The detection stage 913 is made of a material that transmits near-infrared light, and the near-infrared light that is irradiated from the light source 912 and passes through the finger can be imaged by the imaging device 914. An optical system may be provided between the detection stage 913 and the imaging device 914. The above device configuration can also be used in a biometric authentication device for palm veins.

[0191] The light-emitting device of one embodiment of the present invention can be used as the light source 912. The light-emitting device of one embodiment of the present invention can be installed in a curved shape and can uniformly irradiate an object with light. In particular, the light-emitting device is preferably a light-emitting device that emits near-infrared light having the strongest peak intensity in a wavelength range of 760 nm to 900 nm. The position of veins can be detected by receiving light that has passed through a finger or a palm and imaging it. This function can be used for biometric authentication. Furthermore, by combining it with a global shutter system, highly accurate sensing is possible even when the object is moving.

[0192] 5B, the light source 912 may have a plurality of light-emitting units, such as light-emitting units 915, 916, and 917. Each of the light-emitting units 915, 916, and 917 may emit light of a different wavelength, and may emit light at a different timing. Therefore, by changing the wavelength and angle of the emitted light, different images can be captured consecutively, and multiple images can be used for authentication, thereby achieving high security.

[0193] FIG. 5C shows a biometric authentication device for palm veins, which includes a housing 921, an operation button 922, a detection unit 923, a light source 924 that emits near-infrared light, and the like. The shape of palm veins can be recognized by holding a hand over the detection unit 923. A personal identification number or the like can also be input using the operation button. A light source 924 is disposed around the detection unit 923 and irradiates an object (hand). Reflected light from the object enters the detection unit 923. A light-emitting device according to one embodiment of the present invention can be used for the light source 924. An imaging device 925 is disposed directly below the detection unit 923 and can capture an image of the object (the entire image of the hand). Note that an optical system may be provided between the detection unit 923 and the imaging device 925. The above-described device configuration can also be used for a biometric authentication device for finger veins.

[0194] FIG. 5D shows a non-destructive inspection device, which includes a housing 931, an operation panel 932, a conveying mechanism 933, a monitor 934, a detection unit 935, and a light source 938 that emits near-infrared light. A light-emitting device according to one embodiment of the present invention can be used for the light source 938. An inspected member 936 is conveyed by the conveying mechanism 933 to a position directly below the detection unit 935. The inspected member 936 is irradiated with near-infrared light from the light source 938, and the transmitted light is captured by an imaging device 937 provided in the detection unit 935. The captured image is displayed on a monitor 934. The inspected member is then conveyed to the exit of the housing 931, where defective members are sorted and collected. By capturing images using near-infrared light, defective elements such as defects and foreign matter inside the inspected member can be detected non-destructively and quickly.

[0195] FIG. 5E illustrates a mobile phone including a housing 981, a display portion 982, operation buttons 983, an external connection port 984, a speaker 985, a microphone 986, a first camera 987, a second camera 988, and the like. The mobile phone includes a touch sensor in the display portion 982. The housing 981 and the display portion 982 are flexible. Any operation, such as making a call or inputting text, can be performed by touching the display portion 982 with a finger or a stylus. The first camera 987 can acquire a visible light image, and the second camera 988 can acquire an infrared light image (near-infrared light image). The mobile phone or the display portion 982 illustrated in FIG. 5E may include a light-emitting device of one embodiment of the present invention.

[0196] This embodiment mode can be combined with other embodiment modes as appropriate. [Example]

[0197] In this example, the structure, manufacturing method, and characteristics of a light-emitting device 1 of one embodiment of the present invention will be described with reference to FIGS.

[0198] The light-emitting device 1 fabricated in this example has an intermediate layer 816, a light-emitting unit 802a, a light-emitting unit 802b, an electrode 801, an electrode 803, and a function of emitting light (see FIG. 6).

[0199] The intermediate layer 816 has a region sandwiched between the light-emitting unit 802a and the light-emitting unit 802b, and has the function of supplying electrons to one of the light-emitting unit 802a or the light-emitting unit 802b and holes to the other.

[0200] The light-emitting unit 802a includes a region sandwiched between the electrode 801 and the intermediate layer 816, and includes a light-emitting layer 813a. The light-emitting layer 813a includes a first light-emitting material, which is bis{4,6-dimethyl-2-[3-(3,5-dimethylphenyl)-2-benzo[g]quinoxalinyl-κN]phenyl-κC}(2,2,6,6-tetramethyl-3,5-heptanedionato-κN) 2(O,O') Iridium(III) (abbreviation: [Ir(dmdpbq)2(dpm)]) (structural formula (100)) was used as the first light-emitting material. A synthesis example of [Ir(dmdpbq)2(dpm)] will be described later in the Reference Examples.

[0201] Light-emitting unit 802b includes a region sandwiched between intermediate layer 816 and electrode 803, and light-emitting unit 802b includes light-emitting layer 813b. Light-emitting layer 813b also includes a first light-emitting material. Light-emitting layer 813b is separated from light-emitting layer 813a by a distance D1. Distance D1 is 5 nm or more and 65 nm or less. In light-emitting device 1, distance D1 was (15 + 0.1 + 5 + 10) nm = 30.1 nm (see Table 1).

[0202] The spectrum of light emitted from the fabricated light-emitting device 1 has a maximum at a wavelength of 802 nm (see FIG. 13). -3 ) × 802 nm = 5.05 nm, and (81.3 × 10 -3 ) × 802 nm = 65.2 nm. Therefore, the distance D1 (= 30.1 nm) is within the range of 5.05 nm to 65.2 nm.

[0203] At a wavelength of 802 nm, electrode 801 has a higher reflectance than electrode 803. Furthermore, electrode 803 has a higher transmittance than electrode 801 at a wavelength of 802 nm, transmitting part of the light and reflecting the other part.

[0204] The electrode 803 is separated from the electrode 801 by a distance D2. When the distance D2 is multiplied by 1.8, it falls within the range of 0.3 to 0.6 times the wavelength 802 nm. The light-emitting device 1 includes a reflective first film, and a light-transmitting conductive film is sandwiched between the reflective first film and the light-emitting layer 813a. Specifically, the light-emitting device 1 includes a film of an alloy of silver (Ag), palladium (Pd), and copper (Cu) (Ag-Pd-Cu (APC)), and the APC film sandwiches a 10 nm ITSO film between the reflective first film and the light-emitting layer 813a. In this configuration, the distance D2 is (10 + 20 + 20 + 15 + 15 + 0.1 + 5 + 10 + 15 + 20 + 45 + 1) nm = 176.1 nm. Therefore, the value obtained by multiplying the distance D2 (=176.1 nm) by 1.8 is (1.8×176.1=) 316.98 nm, which is within the range of (0.3×802=) 240.6 nm or more and (0.6×802=) 481.2 nm or less.

[0205] Furthermore, the first light-emitting material has an emission spectrum in solution having a maximum at a wavelength PL1, and the wavelength EL1 has a difference of 100 nm or less from the second wavelength PL1.

[0206] The first light-emitting material, [Ir(dmdpbq)2(dpm)], has an emission spectrum with a maximum at a wavelength of 807 nm in a dichloromethane solution (see FIG. 28). Therefore, the maximum wavelength of 802 nm of the spectrum of light emitted from the light-emitting device 1 differs by 5 nm from the maximum wavelength of 807 nm of the emission spectrum of the first light-emitting material, which can be observed in solution.

[0207] The specific configuration of the light-emitting device 1 is shown in Table 1. The chemical formulas of the materials used in this example are shown below.

[0208] [Table 1]

[0209] [ka]

[0210] <<Fabrication of Light-Emitting Device 1>> The light-emitting device 1 shown in this example has a structure in which, as shown in FIG. 6, a first electrode 801 is formed on a substrate 800, an emitting unit 802a (a hole injection layer 811a, a hole transport layer 812a, an emitting layer 813a, an electron transport layer 814a, and an electron injection layer 815a), an intermediate layer 816, and an emitting unit 802b (a hole transport layer 812b, an emitting layer 813b, an electron transport layer 814b, and an electron injection layer 815b) are sequentially stacked on the first electrode 801, and a second electrode 803 is stacked on the emitting unit 802b.

[0211] First, a first electrode 801 was formed on a substrate 800. The electrode area was 4 mm 2 The dimensions were (2 mm × 2 mm). A glass substrate was used as the substrate 800. The first electrode 801 was formed by sputtering an alloy of silver (Ag), palladium (Pd), and copper (Cu) (Ag-Pd-Cu (APC)) to a thickness of 100 nm, and the ITSO was formed by sputtering to a thickness of 10 nm. In this example, the first electrode 801 functions as an anode.

[0212] Here, as a pretreatment, the surface of the substrate was washed with water, baked at 200°C for 1 hour, and then subjected to UV ozone treatment for 370 seconds. -4 The substrate was introduced into a vacuum deposition apparatus whose internal pressure had been reduced to about Pa, and after vacuum baking at 170°C for 30 minutes in the heating chamber of the vacuum deposition apparatus, the substrate was allowed to cool for about 30 minutes.

[0213] Next, a hole injection layer 811a was formed on the first electrode 801. The hole injection layer 811a was formed by evaporating the solution in a vacuum evaporation apparatus for 10 minutes. -4 After reducing the pressure to 10 Pa, 1,3,5-tri(dibenzothiophen-4-yl)benzene (abbreviation: DBT3P-II) and molybdenum oxide were co-evaporated in a weight ratio of DBT3P-II:molybdenum oxide = 2:1 to form a film with a thickness of 20 nm.

[0214] Next, a hole transport layer 812a was formed on the hole injection layer 811a by depositing N-(1,1'-biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: PCBBiF) to a thickness of 20 nm.

[0215] Next, the light-emitting layer 813a was formed on the hole-transporting layer 812a. 2-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II) was used as the host material, PCBBiF was used as the assist material, and bis{4,6-dimethyl-2-[3-(3,5-dimethylphenyl)-2-benzo[g]quinoxalinyl-κN]phenyl-κC}(2,2,6,6-tetramethyl-3,5-heptanedionato-κC) was used as the guest material (phosphorescent material). 2 Iridium(III) (abbreviation: [Ir(dmdpbq)2(dpm)]) (structural formula (100)) was co-evaporated at a weight ratio of 2mDBTBPDBq-II:PCBBiF:[Ir(dmdpbq)2(dpm)] = 0.7:0.3:0.1. The film thickness was 15 nm.

[0216] Next, electron transport layer 814a was formed on light emitting layer 813a by sequentially depositing 2,9-bis(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviation: NBphen) to a thickness of 15 nm.

[0217] Next, the electron injection layer 815a was formed on the electron transport layer 814a. The electron injection layer 815a was formed by vapor deposition using lithium oxide (Li2O) to a thickness of 0.1 nm.

[0218] Next, intermediate layer 816 was formed on electron injection layer 815a. Intermediate layer 816 was formed by co-evaporating DBT3P-II and molybdenum oxide in a weight ratio of DBT3P-II:molybdenum oxide=2:1 to a thickness of 5 nm.

[0219] Next, a hole transport layer 812b was formed on the intermediate layer 816. The hole transport layer 812b was formed by vapor deposition using PCBBiF to a film thickness of 10 nm.

[0220] Next, an emitting layer 813b was formed on the hole transport layer 812b. 2mDBTBPDBq-II was used as the host material, PCBBiF was used as the assist material, and [Ir(dmdpbq)2(dpm)] was used as the guest material (phosphorescent material). They were co-deposited in a weight ratio of 2mDBTBPDBq-II: PCBBiF: [Ir(dmdpbq)2(dpm)] = 0.7: 0.3: 0.1. The film thickness was 15 nm.

[0221] Next, the electron transport layer 814b was formed on the light emitting layer 813b by sequentially depositing 2mDBTBPDBq-II to a thickness of 20 nm and NBphen to a thickness of 45 nm.

[0222] Next, the electron injection layer 815b was formed on the electron transport layer 814b by vapor deposition of lithium fluoride (LiF) to a thickness of 1 nm.

[0223] Next, a second electrode 803 was formed on the electron injection layer 815b. The second electrode 803 was formed by co-evaporating silver (Ag) and magnesium (Mg) at a volume ratio of Ag:Mg=10:1 to a thickness of 30 nm. In this example, the second electrode 803 functions as a cathode.

[0224] Next, a buffer layer 804 was formed on the second electrode 803. The buffer layer 804 was formed by vapor deposition using DBT3P-II so as to have a film thickness of 100 nm.

[0225] Through the above steps, the light emitting device 1 was formed on the substrate 800. Furthermore, in all of the vapor deposition steps in the above-described manufacturing method, vapor deposition using resistance heating was used.

[0226] The light-emitting device fabricated as described above is sealed with another substrate (not shown). When sealing using another substrate (not shown), another substrate (not shown) coated with an adhesive that hardens when exposed to ultraviolet light is fixed on the substrate 800 in a glove box with a nitrogen atmosphere, and the substrates are bonded together so that the adhesive adheres to the periphery of the light-emitting device formed on the substrate 800. During sealing, 365 nm ultraviolet light is applied at 6 J / cm. 2 The adhesive was solidified by irradiation and then stabilized by heat treatment at 80°C for 1 hour.

[0227] A microcavity structure is applied to the light-emitting device 1. The light-emitting device 1 was fabricated so that the optical distance between a pair of reflective electrodes (APC film and Ag:Mg film) was approximately 1 / 2 the wavelength of the maximum peak wavelength of the light emitted by the guest material.

[0228] <<Operation characteristics of light-emitting device 1>> The operating characteristics of the light-emitting device 1 were measured. The measurements were carried out at room temperature (in an atmosphere maintained at 25° C.).

[0229] FIG. 8 shows the current density-radiant emittance characteristics of the light-emitting device 1. FIG. 9 shows the voltage-current density characteristics of the light-emitting device 1. FIG. 10 shows the current density-radiant flux characteristics of the light-emitting device 1. FIG. 11 shows the voltage-radiant emittance characteristics of the light-emitting device 1. FIG. 12 shows the current density-external quantum efficiency characteristics of the light-emitting device 1. The radiant emittance, radiant flux, and external quantum efficiency were calculated using radiance, assuming that the light distribution characteristics of the light-emitting device are Lambertian.

[0230] Table 2 shows 8.9W / sr / m 2 1 shows the main initial characteristic values ​​of the light-emitting device 1 in the vicinity of the luminance.

[0231] [Table 2]

[0232] As shown in FIGS. 8 to 12 and Table 2, it was found that light-emitting device 1 exhibited good characteristics. For example, at the same current density, light-emitting device 1 emitted light with a higher radiance than light-emitting devices 2 and 3 described below. Furthermore, at the same current density, light-emitting device 1 also had a higher external quantum efficiency than light-emitting devices 2 and 3. Furthermore, at the same current density, the driving voltage of light-emitting device 1 was lower than that of light-emitting device 3.

[0233] In addition, 10 mA / cm 2 The emission spectrum obtained when a current was passed at a current density of 1000 s is shown in Fig. 13. A near-infrared spectroradiometer (SR-NIR, manufactured by Topcon Corporation) was used to measure the emission spectrum. As shown in Fig. 13, the light-emitting device 3 exhibited an emission spectrum with a maximum peak near 802 nm, which was attributable to the emission of [Ir(dmdpbq)2(dpm)] contained in the light-emitting layers 813a and 831b.

[0234] Furthermore, by adopting a microcavity structure, the emission spectrum was narrowed to a half-width of 35 nm. Light-emitting device 1 efficiently emits light in the range of 760 nm to 900 nm, making it highly effective as a light source for sensors and other applications.

[0235] (Reference example 1) In this reference example, the structure, manufacturing method, and characteristics of the manufactured light-emitting device 2 will be described with reference to FIG. 7A and FIGS.

[0236] The light-emitting device 2 fabricated in this reference example has a light-emitting unit 802, electrodes 801 and 803, and a function of emitting light (see FIG. 7). Note that the light-emitting device 2 differs from the light-emitting device 1 in that it has one light-emitting unit.

[0237] The light-emitting unit 802 includes a region sandwiched between the electrode 801 and the electrode 803, and includes a light-emitting layer 813. The light-emitting layer 813 contains a first light-emitting material. [Ir(dmdpbq)2(dpm)] is used as the first light-emitting material.

[0238] The spectrum of light emitted from the fabricated light-emitting device 2 has a maximum at a wavelength of 798 nm (see FIG. 19).

[0239] The specific configuration of the light-emitting device 2 is shown in Table 3.

[0240] [Table 3]

[0241] <<Fabrication of Light-Emitting Device 2>> The light-emitting device 2 shown in this example has a structure in which, as shown in FIG. 7A, a first electrode 801 is formed on a substrate 800, a hole injection layer 811, a hole transport layer 812, a light-emitting layer 813, an electron transport layer 814, and an electron injection layer 815 are sequentially stacked on the first electrode 801, and a second electrode 803 is stacked on the electron injection layer 815.

[0242] First, a first electrode 801 was formed on a substrate 800. The electrode area was 4 mm 2 The dimensions were (2 mm × 2 mm). A glass substrate was used as the substrate 800. The first electrode 801 was formed by sputtering an alloy of silver (Ag), palladium (Pd), and copper (Cu) (Ag-Pd-Cu (APC)) to a thickness of 100 nm, and the ITSO was formed by sputtering to a thickness of 10 nm. In this example, the first electrode 801 functions as an anode.

[0243] Here, as a pretreatment, the surface of the substrate was washed with water, baked at 200°C for 1 hour, and then subjected to UV ozone treatment for 370 seconds. -4 The substrate was introduced into a vacuum deposition apparatus whose internal pressure had been reduced to about Pa, and after vacuum baking at 170°C for 30 minutes in the heating chamber of the vacuum deposition apparatus, the substrate was allowed to cool for about 30 minutes.

[0244] Next, a hole injection layer 811 was formed on the first electrode 801. The hole injection layer 811 was formed by evaporating the solution in a vacuum deposition apparatus for 10 minutes. -4After reducing the pressure to 10 Pa, DBT3P-II and molybdenum oxide were co-deposited in a weight ratio of DBT3P-II:molybdenum oxide=2:1 to form a film having a thickness of 25 nm.

[0245] Next, a hole transport layer 812 was formed on the hole injection layer 811. The hole transport layer 812 was formed by vapor deposition using PCBBiF so as to have a film thickness of 20 nm.

[0246] Next, an emitting layer 813 was formed on the hole transport layer 812. 2mDBTBPDBq-II was used as the host material, PCBBiF was used as the assist material, and [Ir(dmdpbq)2(dpm)] was used as the guest material (phosphorescent material), and they were co-deposited in a weight ratio of 2mDBTBPDBq-II:PCBBiF:[Ir(dmdpbq)2(dpm)]=0.7:0.3:0.1. The film thickness was 40 nm.

[0247] Next, an electron transport layer 814 was formed on the light-emitting layer 813. The electron transport layer 814 was formed by sequentially depositing 2mDBTBPDBq-II to a thickness of 20 nm and NBphen to a thickness of 75 nm.

[0248] Next, electron injection layer 815 was formed on electron transport layer 814. Electron injection layer 815 was formed by vapor deposition using lithium fluoride (LiF) so as to have a film thickness of 1 nm.

[0249] Next, a second electrode 803 was formed on the electron injection layer 815. The second electrode 803 was formed by co-evaporating silver (Ag) and magnesium (Mg) at a volume ratio of Ag:Mg=10:1 to a thickness of 30 nm. In this example, the second electrode 803 functions as a cathode.

[0250] Next, a buffer layer 804 was formed on the second electrode 803. The buffer layer 804 was formed by vapor deposition using DBT3P-II so as to have a film thickness of 100 nm.

[0251] Through the above steps, the light emitting device 2 was formed on the substrate 800. Furthermore, in all of the vapor deposition steps in the above-described manufacturing method, vapor deposition using resistance heating was used.

[0252] The light emitting device 2 is sealed with another substrate (not shown). The sealing method is the same as that of the light emitting device 1, and reference can be made to Example 1.

[0253] <<Operation characteristics of light-emitting device 2>> The operating characteristics of the light-emitting device 2 were measured. The measurements were carried out at room temperature (in an atmosphere maintained at 25° C.).

[0254] FIG. 14 shows the current density-radiant emittance characteristics of light-emitting device 2. FIG. 15 shows the voltage-current density characteristics of light-emitting device 2. FIG. 16 shows the current density-radiant flux characteristics of light-emitting device 2. FIG. 17 shows the voltage-radiant emittance characteristics of light-emitting device 2. FIG. 18 shows the current density-external quantum efficiency characteristics of light-emitting device 2. Note that the radiant emittance, radiant flux, and external quantum efficiency were calculated using radiance, assuming that the light distribution characteristics of the light-emitting device are Lambertian.

[0255] Table 4 shows 4.9 W / sr / m 2 1 shows the main initial characteristic values ​​of the light emitting device 2 in the vicinity of the luminance.

[0256] [Table 4]

[0257] In addition, 10 mA / cm 2 The emission spectrum when a current was passed at a current density of 1000 s is shown in Figure 19. The emission spectrum was measured using a near-infrared spectroradiometer (SR-NIR, manufactured by Topcon Corporation).

[0258] (Reference example 2) In this reference example, the structure, manufacturing method, and characteristics of the manufactured light-emitting device 3 will be described with reference to FIG. 7B and FIGS. 20 to 25. FIG.

[0259] Light-emitting device 3 fabricated in this reference example has intermediate layer 816, light-emitting unit 802a, light-emitting unit 802b, electrode 801, electrode 803, and the ability to emit light (see FIG. 7B). Light-emitting device 3 differs from light-emitting device 1 in that a longer distance is provided between light-emitting layer 813b and light-emitting layer 813a than in light-emitting device 1. Light-emitting device 3 also differs from light-emitting device 1 in that a longer distance is provided between electrode 801 and electrode 803 than in light-emitting device 1.

[0260] The intermediate layer 816 has a region sandwiched between the light-emitting unit 802a and the light-emitting unit 802b, and has the function of supplying electrons to one of the light-emitting unit 802a or the light-emitting unit 802b and holes to the other.

[0261] The light-emitting unit 802a includes a region sandwiched between the electrode 801 and the intermediate layer 816, and includes a light-emitting layer 813a. The light-emitting layer 813a includes a first light-emitting material.

[0262] Light-emitting unit 802b includes a region sandwiched between intermediate layer 816 and electrode 803, and light-emitting unit 802b includes light-emitting layer 813b. Light-emitting layer 813b also includes a first light-emitting material. A distance D1 is provided between light-emitting layer 813b and light-emitting layer 813a. In light-emitting device 3, distance D1 was (20 + 90 + 0.1 + 2 + 10 + 60) nm = 182.1 nm (see Table 5).

[0263] The spectrum of light emitted from the fabricated light-emitting device 2 has a maximum at a wavelength of 799 nm (see FIG. 25).

[0264] At wavelength EL1, electrode 801 has a higher reflectance than electrode 803. At wavelength EL1, electrode 803 has a higher transmittance than electrode 801, transmitting part of the light and reflecting the other part.

[0265] The specific configuration of the light-emitting device 3 used in this reference example is shown in Table 5. The chemical formulas of the materials used in this reference example are shown below.

[0266] [Table 5]

[0267] [ka]

[0268] "Fabrication of Light-Emitting Device 3" The light-emitting device 3 shown in this example has a structure in which, as shown in FIG. 7B , a first electrode 801 is formed on a substrate 800, a light-emitting unit 802a (a hole injection layer 811a, a hole transport layer 812a, a light-emitting layer 813a, an electron transport layer 814a, and an electron injection layer 815a), an intermediate layer 816, and a light-emitting unit 802b (a hole injection layer 811b, a hole transport layer 812b, a light-emitting layer 813b, an electron transport layer 814b, and an electron injection layer 815b) are sequentially stacked on the first electrode 801, and a second electrode 803 is stacked on the light-emitting unit 802b.

[0269] First, a first electrode 801 was formed on a substrate 800. The electrode area was 4 mm 2 The dimensions were (2 mm × 2 mm). A glass substrate was used as the substrate 800. The first electrode 801 was formed by sputtering an alloy of silver (Ag), palladium (Pd), and copper (Cu) (Ag-Pd-Cu (APC)) to a thickness of 100 nm, and the ITSO was formed by sputtering to a thickness of 10 nm. In this example, the first electrode 801 functions as an anode.

[0270] Here, as a pretreatment, the surface of the substrate was washed with water, baked at 200°C for 1 hour, and then subjected to UV ozone treatment for 370 seconds. -4 The substrate was introduced into a vacuum deposition apparatus whose internal pressure had been reduced to about Pa, and after vacuum baking at 170°C for 30 minutes in the heating chamber of the vacuum deposition apparatus, the substrate was allowed to cool for about 30 minutes.

[0271] Next, a hole injection layer 811a was formed on the first electrode 801. The hole injection layer 811a was formed by evaporating the solution in a vacuum evaporation apparatus for 10 minutes. -4 After reducing the pressure to 10 Pa, DBT3P-II and molybdenum oxide were co-deposited in a weight ratio of DBT3P-II:molybdenum oxide=2:1 to form a film having a thickness of 10 nm.

[0272] Next, a hole transport layer 812a was formed on the hole injection layer 811a by vapor deposition of PCBBiF to a thickness of 30 nm.

[0273] Next, an emitting layer 813a was formed on the hole transport layer 812a. 2mDBTBPDBq-II was used as the host material, PCBBiF was used as the assist material, and the organometallic complex [Ir(dmdpbq)2(dpm)] was used as the guest material (phosphorescent material). They were co-deposited in a weight ratio of 2mDBTBPDBq-II:PCBBiF:[Ir(dmdpbq)2(dpm)]=0.7:0.3:0.1. The film thickness was 40 nm.

[0274] Next, the electron transport layer 814a was formed on the light emitting layer 813a by sequentially depositing 2mDBTBPDBq-II to a thickness of 20 nm and NBphen to a thickness of 90 nm.

[0275] Next, the electron injection layer 815a was formed on the electron transport layer 814a. The electron injection layer 815a was formed by vapor deposition using lithium oxide (Li2O) to a thickness of 0.1 nm.

[0276] Next, intermediate layer 816 was formed on electron injection layer 815a. Intermediate layer 816 was formed by vapor deposition using copper phthalocyanine (CuPc) to a film thickness of 2 nm.

[0277] Next, hole injection layer 811b was formed on intermediate layer 816. Hole injection layer 811b was formed by co-evaporation of DBT3P-II and molybdenum oxide in a weight ratio of DBT3P-II:molybdenum oxide=2:1 to a thickness of 10 nm.

[0278] Next, a hole transport layer 812b was formed on the hole injection layer 811b by vapor deposition of PCBBiF to a thickness of 60 nm.

[0279] Next, a light-emitting layer 813b was formed over the hole-transport layer 812b. 2mDBTBPDBq-II was used as a host material, PCBBiF was used as an assist material, and [Ir(dmdpbq)2(dpm)], an organometallic complex of one embodiment of the present invention, was used as a guest material (phosphorescent material) by co-evaporation in a weight ratio of 2mDBTBPDBq-II:PCBBiF:[Ir(dmdpbq)2(dpm)]=0.7:0.3:0.1. The film thickness was 40 nm.

[0280] Next, the electron transport layer 814b was formed on the light emitting layer 813b by sequentially depositing 2mDBTBPDBq-II to a thickness of 20 nm and NBphen to a thickness of 65 nm.

[0281] Next, the electron injection layer 815b was formed on the electron transport layer 814b by vapor deposition of lithium fluoride (LiF) to a thickness of 1 nm.

[0282] Next, a second electrode 803 was formed on the electron injection layer 815b. The second electrode 803 was formed by co-evaporating silver (Ag) and magnesium (Mg) at a volume ratio of Ag:Mg=10:1 to a thickness of 20 nm. In this example, the second electrode 803 functions as a cathode.

[0283] Next, a buffer layer 804 was formed on the second electrode 803. The buffer layer 804 was formed by vapor deposition using DBT3P-II so as to have a film thickness of 110 nm.

[0284] Through the above steps, the light emitting device 3 was formed on the substrate 800. Furthermore, in all of the vapor deposition steps in the above-described manufacturing method, vapor deposition using resistance heating was used.

[0285] The light emitting device 3 is sealed with another substrate (not shown). The sealing method is the same as that of the light emitting device 1, and reference can be made to Example 1.

[0286] A microcavity structure is applied to the light-emitting device 3. The light-emitting device 3 was fabricated so that the optical distance between a pair of reflective electrodes (APC film and Ag:Mg film) was approximately one wavelength of the maximum peak wavelength of the light emitted from the guest material.

[0287] <<Operation characteristics of light-emitting device 3>> The operating characteristics of the light-emitting device 3 were measured. The measurements were carried out at room temperature (in an atmosphere maintained at 25° C.).

[0288] FIG. 20 shows the current density-radiant emittance characteristics of the light-emitting device 3. FIG. 21 shows the voltage-current density characteristics of the light-emitting device 3. FIG. 22 shows the current density-radiant flux characteristics of the light-emitting device 3. FIG. 23 shows the voltage-radiant emittance characteristics of the light-emitting device 3. FIG. 24 shows the current density-external quantum efficiency characteristics of the light-emitting device 3. The radiant emittance, radiant flux, and external quantum efficiency were calculated using radiance, assuming that the light distribution characteristics of the light-emitting device are Lambertian.

[0289] Table 6 shows 6.8W / sr / m 2 1 shows the main initial characteristic values ​​of the light emitting device 3 in the vicinity of the luminance.

[0290] [Table 6]

[0291] In addition, 10 mA / cm 2The emission spectrum when a current was passed at this current density is shown in Fig. 25. The emission spectrum was measured using a near-infrared spectroradiometer (SR-NIR, manufactured by Topcon Corporation). [Example]

[0292] In this example, structures of light-emitting devices 11 to 20 according to one embodiment of the present invention, calculations using calculated values, and calculation results will be described with reference to FIGS. 26 and 27. FIG.

[0293] FIG. 26 illustrates the structures of a light-emitting device of one embodiment of the present invention and a device of a reference example.

[0294] 27 illustrates the results of calculations performed on a light-emitting device of one embodiment of the present invention and a device of a reference example, specifically illustrating how the external quantum efficiency changes depending on the distance D1 between two light-emitting layers.

[0295] <Example of light-emitting device configuration> The light-emitting device of one embodiment of the present invention includes an intermediate layer 104, a light-emitting unit 103a, a light-emitting unit 103b, an electrode 101, an electrode 102, and a function of emitting light (see FIG. 26).

[0296] The intermediate layer 104 has a function of supplying electrons to one of the light-emitting units 103a and 103b, and supplying holes to the other.

[0297] <<Light-emitting layer 113a>> The light-emitting unit 103a includes a region sandwiched between the electrode 101 and the intermediate layer 104. The light-emitting unit 103a includes a light-emitting layer 113a, which includes a first light-emitting material. In this example, the thickness of the light-emitting layer 113a was 10 nm, and [Ir(dmdpbq)2(dpm)] was used as the first light-emitting material.

[0298] <<Luminescent layer 113b>> Light-emitting unit 103b includes a region sandwiched between intermediate layer 104 and electrode 102. Light-emitting unit 103b includes light-emitting layer 113b, which includes a second light-emitting material. In this example, the thickness of light-emitting layer 113b was 10 nm, and the same material as the first light-emitting material was used as the second light-emitting material.

[0299] The light-emitting device according to one embodiment of the present invention emits light having a spectrum with a maximum at wavelength EL1. In this example, the light-emitting device emits light having a spectrum with a maximum in the vicinity of 800 nm.

[0300] 《Electrode 101》 The electrode 101 has a higher reflectance at the wavelength EL1 than the electrode 102. In this example, the electrode 101 is made of silver having a thickness of 100 nm.

[0301] 《Electrode 102》 The electrode 102 has a higher transmittance at wavelength EL1 than the electrode 101. The electrode 102 transmits part of the light at wavelength EL1 and reflects the other part. In this example, silver with a thickness of approximately 30 nm was used for the electrode 102. The light-emitting device of one embodiment of the present invention also includes a protective layer 105 with a thickness of approximately 100 nm. Note that the protective layer 105 is in contact with the electrode 102.

[0302] Furthermore, the electrode 102 is separated from the electrode 101 by a distance D2. When the distance D2 is multiplied by 1.8, it falls within the range of 0.3 to 0.6 times the wavelength EL1. In this embodiment, the distance D2 is set to a value in the range of 134 nm to 266 nm.

[0303] The light-emitting layer 113b is separated from the light-emitting layer 113a by a distance D1. In this embodiment, the distance D1 is set to a value in the range of 10 nm to 90 nm.

[0304] Specifically, a distance D1 of 10 nm was applied to light-emitting device 12, a distance D1 of 20 nm was applied to light-emitting device 13, a distance D1 of 30 nm was applied to light-emitting device 14, a distance D1 of 40 nm was applied to light-emitting device 15, a distance D1 of 50 nm was applied to light-emitting device 16, a distance D1 of 60 nm was applied to light-emitting device 17, a distance D1 of 70 nm was applied to light-emitting device 18, a distance D1 of 80 nm was applied to light-emitting device 19, and a distance D1 of 90 nm was applied to light-emitting device 20.

[0305] The light-emitting layer 113a is separated from the electrode 101 by a distance D33. The light-emitting layer 113b is separated from the electrode 102 by a distance D34.

[0306] For each distance D1, the distance D33, the distance D34, the thickness of the electrode 102, and the thickness of the protective layer 105 were optimized using a computer. As a result, the efficiency of extracting light from the light-emitting device was compared for each distance D1.

[0307] 《Calculation method》 In this example, calculations were performed using an organic device simulator (semiconducting emissive thin film optics simulator: setfos; manufactured by Cybernet Systems Co., Ltd.).

[0308] In this calculation, the film thickness, refractive index n, and extinction coefficient k of each layer constituting the light-emitting device, the measured values ​​of the emission spectrum (photoluminescence (PL) spectrum) of the light-emitting material, and the emission position were input, and the emission intensity and peak waveform in the front direction were calculated by multiplying them by the Purcell factor and taking into account modulation of the radiative decay rate of excitons.

[0309] The refractive index n of each layer was assumed to be 1.8, and the extinction coefficient k was assumed to be 0. The silver (Ag) used for the reflective electrode and semi-reflective electrode had the values ​​listed on pages 355-356 of the Handbook of Optical Constants of Solids, Volume 1.

[0310] The emission spectrum of the luminescent material was measured using a near-infrared spectroradiometer (SR-NIR manufactured by Topcon Corporation) as a detector, an ultraviolet-emitting LED (NSCU033B manufactured by Nichia Corporation) as excitation light, a UV U360 bandpass filter (manufactured by Edmund Optics), and an SCF-50S-42L longpass filter (manufactured by Sigma Koki).

[0311] For the measurement of the infrared emission spectrum, a film was prepared by co-evaporation of 2mDBTBPDBq-II, PCBBiF, and bis{4,6-dimethyl-2-[3-(3,5-dimethylphenyl)-2-benzo[g]quinoxalinyl-κN]phenyl-κC}(2,2,6,6-tetramethyl-3,5-heptanedionato-κO,O')iridium(III) (abbreviation: [Ir(dmdpbq)(dpm)]) in a weight ratio of 0.7:0.3:0.1 on a quartz substrate to a thickness of 50 nm using a vacuum evaporation method.

[0312] The emission spectrum used in the calculation is shown in Fig. 29. In Fig. 29, the horizontal axis represents wavelength (unit: nm), and the vertical axis represents energy-based normalized intensity (arbitrary unit: au).

[0313] The light emission position was assumed to be the center of the light emitting layer.

[0314] The luminescence quantum yield, exciton generation probability, and recombination probability were assumed to be 100%. In other words, the calculated external quantum efficiency (Lambertian assumption) indicates the light extraction efficiency calculated from the front emission intensity assuming a Lambertian light distribution.

[0315] In the calculation, the film thicknesses of the hole transport layer, electron transport layer, semi-reflective electrode, and protective layer that maximize the external quantum efficiency (Lambertian assumption) were entered as the film thicknesses close to the target optical distance.

[0316] For devices where the optical distance between electrodes is close to λ, the thickness of the intermediate layer was also determined.

[0317] "result" The calculation results are shown in Tables 7 and 8 and Fig. 27. When the distance D1 was 5 nm or more and 65 nm or less, the light-emitting device according to one embodiment of the present invention emitted light with higher efficiency than the light-emitting device 21 of Reference Example 3 described below.

[0318] [Table 7]

[0319] [Table 8]

[0320] (Reference example 3) In the light-emitting device 21 of the reference example, when the distance D2 (395 nm = 90 + 10 + 193 + 10 + 92) is multiplied by 1.8, it is 0.89 times the maximum wavelength of 797 nm in the spectrum of the emitted light, which is outside the range of 0.3 times or more and 0.6 times or less of the maximum wavelength, which is different from the light-emitting device of one embodiment of the present invention.

[0321] (Synthesis Example 1) Example 1 This example describes a synthesis method for an organometallic complex of one embodiment of the present invention. In this example, bis{4,6-dimethyl-2-[3-(3,5-dimethylphenyl)-2-benzo[g]quinoxalinyl-κN]phenyl-κC}(2,2,6,6-tetramethyl-3,5-heptanedionato-κC) represented by structural formula (100) in Embodiment 1 was synthesized. 2 This article describes a method for synthesizing (O,O') iridium(III) (abbreviation: [Ir(dmdpbq)2(dpm)]).

[0322] [ka]

[0323] <Step 1: Synthesis of 2,3-bis-(3,5-dimethylphenyl)-2-benzo[g]quinoxaline (abbreviation: Hdmdpbq)> First, in step 1, Hdmdpbq, an organic compound according to one embodiment of the present invention and represented by structural formula (200), was synthesized. 3.20 g of 3,3',5,5'-tetramethylbenzyl, 1.97 g of 2,3-diaminonaphthalene, and 60 mL of ethanol were placed in a three-neck flask equipped with a reflux condenser. The atmosphere inside was replaced with nitrogen, and the mixture was stirred at 90°C for 7.5 hours. After the specified time had elapsed, the solvent was distilled off. The product was then purified by silica gel column chromatography using toluene as a developing solvent to obtain the target product (yellow solid, yield 3.73 g, 79%). The synthesis scheme for step 1 is shown in (a-1).

[0324] [ka]

[0325] Nuclear magnetic resonance spectroscopy of the yellow solid obtained in step 1 ( 1 The results of the analysis by H-NMR are shown below. From this, it was found that Hdmdpbq represented by structural formula (200) was obtained in this example.

[0326] of the obtained material 1 The 1 H NMR data is shown below. 1 H-NMR.δ(CD2Cl2):2.28(s,12H),7.01(s,2H),7.16(s,4H),7.56-7.58(m,2H),8.11-8.13(m,2H),8.74(s,2H).

[0327] Step 2: Synthesis of di-μ-chloro-tetrakis{4,6-dimethyl-2-[3-(3,5-dimethylphenyl)-2-benzo[g]quinoxalinyl-κN]phenyl-κC}diiridium(III) (abbreviation: [Ir(dmdpbq)Cl]) Next, in Step 2, a dinuclear complex according to one embodiment of the present invention, [Ir(dmdpbq)2Cl]2, represented by structural formula (210), was synthesized. 15 mL of 2-ethoxyethanol, 5 mL of water, 1.81 g of Hdmdpbq obtained in Step 1, and 0.66 g of iridium chloride hydrate (IrCl3·HO) (Furuya Metal Co., Ltd.) were placed in a recovery flask equipped with a reflux condenser, and the atmosphere inside the flask was replaced with argon. The reaction was then carried out by irradiating with microwaves (2.45 GHz, 100 W) for 2 hours. After the predetermined time had elapsed, the resulting residue was suction filtered and washed with methanol to obtain the target product (black solid, yield 1.76 g, 81%). The synthesis scheme for Step 2 is shown in (a-2).

[0328] [ka]

[0329] Step 3: Synthesis of [Ir(dmdpbq)2(dpm)] In step 3, [Ir(dmdpbq)2(dpm)], an organometallic complex according to one embodiment of the present invention and represented by structural formula (100), was synthesized. 20 mL of 2-ethoxyethanol, 1.75 g of [Ir(dmdpbq)2Cl]2 obtained in step 2, 0.50 g of dipivaloylmethane (abbreviation: Hdpm), and 0.95 g of sodium carbonate were placed in a recovery flask equipped with a reflux condenser, and the atmosphere in the flask was replaced with argon. Microwave irradiation (2.45 GHz, 100 W) was then performed for 3 hours. The resulting residue was suction filtered with methanol and then washed with water and methanol. The resulting solid was purified by silica gel column chromatography using dichloromethane as a developing solvent and then recrystallized from a mixed solvent of dichloromethane and methanol to obtain the target compound (dark green solid, yield: 0.42 g, 21%). 0.41 g of the resulting dark green solid was purified by train sublimation. The sublimation purification conditions were to heat the dark green solid to 300 °C under a pressure of 2.7 Pa and an argon gas flow rate of 10.5 mL / min. After sublimation purification, a dark green solid was obtained in 78% yield. The synthesis scheme for Step 3 is shown in (a-3).

[0330] [ka]

[0331] Nuclear magnetic resonance spectroscopy of the dark green solid obtained in step 3 ( 1 The results of the analysis by H-NMR are shown below. From this, it was found that [Ir(dmdpbq)2(dpm)] represented by structural formula (100) was obtained in this example.

[0332] of the obtained material 1 The 1 H NMR data is shown below. 1 H-NMR.δ(CD2Cl2):0.75(s,18H),0.97(s,6H),2.01(s,6H),2.52(s,12H),4.86(s,1H),6.39(s,2H),7.15 (s,2H),7.31(s,2H),7.44-7.51(m,4H),7.80(d,2H),7.86(s,4H),8.04(d,2H),8.42(s,2H),8.58(s,2H).

[0333] Next, the ultraviolet-visible absorption spectrum (hereinafter simply referred to as "absorption spectrum") and emission spectrum of a dichloromethane solution of [Ir(dmdpbq)2(dpm)] were measured.

[0334] Absorption spectra were measured using an ultraviolet-visible spectrophotometer (V550, manufactured by JASCO Corporation) with a dichloromethane solution (0.010 mmol / L) placed in a quartz cell at room temperature. Emission spectra were measured using a fluorometer (FS920, manufactured by Hamamatsu Photonics K.K.) with a deoxygenated dichloromethane solution (0.010 mmol / L) placed in a quartz cell under a nitrogen atmosphere, sealed, and measured at room temperature.

[0335] The measurement results of the obtained absorption spectrum and emission spectrum are shown in Figure 7. The horizontal axis represents wavelength, and the vertical axis represents absorption intensity and emission intensity. In Figure 28, the thin solid line represents the absorption spectrum, and the thick solid line represents the emission spectrum. The absorption spectrum shown in Figure 28 is the result of subtracting the absorption spectrum measured by putting only dichloromethane into a quartz cell from the absorption spectrum measured by putting a dichloromethane solution (0.010 mmol / L) into a quartz cell.

[0336] As shown in FIG. 28, [Ir(dmdpbq) 2 (dpm)], which is an organometallic complex of one embodiment of the present invention, exhibits an emission peak at 807 nm, and near-infrared emission was observed from a dichloromethane solution.

[0337] This embodiment can be appropriately combined with other embodiment modes shown in this specification. [Example]

[0338] In this example, the structure, manufacturing method, and characteristics of a light-emitting device 4 of one embodiment of the present invention will be described with reference to FIGS.

[0339] Note that light-emitting device 4 differs from light-emitting device 1 described using Table 1 in the configurations of hole injection layer 811a, hole transport layer 812a, intermediate layer 816, hole transport layer 812b, and electron transport layer 814b. Here, the differences will be described in detail, and the above description will be used for parts where a similar configuration can be used. Furthermore, in light-emitting device 4, distance D1 was (15 + 0.1 + 5 + 5) nm = 25.1 nm (see Table 9).

[0340] The spectrum of light emitted from the fabricated light-emitting device 4 has a maximum at a wavelength of 803 nm (see FIG. 35). -3 ) × 803 nm = 5.06 nm, and (81.3 × 10 -3 ) × 803 nm = 65.6 nm. Therefore, the distance D1 (= 25.1 nm) is within the range of 5.06 nm to 65.6 nm.

[0341] The light-emitting device 4 includes a reflective first film sandwiching a light-transmitting conductive film between the reflective first film and the light-emitting layer 813a. Specifically, the device includes a film of an alloy of silver (Ag), palladium (Pd), and copper (Cu) (Ag-Pd-Cu (APC)), with a 10 nm ITSO film sandwiched between the APC film and the light-emitting layer 813a. In this configuration, the distance D2 is (10 + 10 + 32.5 + 15 + 15 + 0.1 + 5 + 5 + 15 + 20 + 52.5 + 1) nm = 181.1 nm. Therefore, the distance D2 (= 181.1 nm) multiplied by 1.8 is (1.8 × 181.1 =) 325.98 nm, which is within the range of (0.3 × 803 =) 240.9 nm to (0.6 × 803 =) 481.8 nm.

[0342] The specific configuration of the light-emitting device 4 is shown in Table 9.

[0343] [Table 9]

[0344] "Fabrication of Light-Emitting Device 4" The hole injection layer 811a was formed by evaporating the solution in a vacuum deposition apparatus for 10 minutes. -4 After reducing the pressure to 10 Pa, PCBBiF and NDP-9 (Bunseki Kobo Co., Ltd., material serial number: 1S20170124) were co-evaporated in a PCBBiF:NDP-9 = 1:0.1 (weight ratio) to form a film with a thickness of 10 nm.

[0345] The hole transport layer 812a was formed by vapor deposition using PCBBiF to a thickness of 32.5 nm.

[0346] Intermediate layer 816 was formed by co-evaporating PCBBiF and NDP-9 at a weight ratio of PCBBiF:NDP-9=1:0.1 to a thickness of 5 nm.

[0347] The hole transport layer 812b was formed by vapor deposition using PCBBiF to a thickness of 5 nm.

[0348] The electron transport layer 814b was formed by sequentially depositing 2mDBTBPDBq-II to a thickness of 20 nm and NBphen to a thickness of 52.5 nm.

[0349] <<Operation characteristics of light-emitting device 4>> The operating characteristics of the light-emitting device 4 were measured. The measurements were carried out at room temperature (in an atmosphere maintained at 25° C.).

[0350] FIG. 30 shows the current density-radiant emittance characteristics of light-emitting device 4. FIG. 31 shows the voltage-current density characteristics of light-emitting device 4. FIG. 32 shows the current density-radiant flux characteristics of light-emitting device 4. FIG. 33 shows the voltage-radiant emittance characteristics of light-emitting device 4. FIG. 34 shows the current density-external quantum efficiency characteristics of light-emitting device 4. Note that the radiant emittance, radiant flux, and external quantum efficiency were calculated using radiance, assuming that the light distribution characteristics of the light-emitting device are Lambertian.

[0351] Table 10 shows 8.1W / sr / m 2 1 shows the main initial characteristic values ​​of the light emitting device 4 in the vicinity of the luminance.

[0352] [Table 10]

[0353] As shown in FIGS. 30 to 34 and Table 10, it was found that light-emitting device 4 exhibited good characteristics. For example, light-emitting device 4 emitted light with a higher radiance than light-emitting device 2 and light-emitting device 3 described above at the same current density. Furthermore, light-emitting device 4 has a higher external quantum efficiency than light-emitting device 2 and light-emitting device 3 at the same current density. Furthermore, the driving voltage of light-emitting device 4 is lower than that of light-emitting device 3 at the same current density.

[0354] In addition, 10 mA / cm 2The emission spectrum obtained when a current was passed at a current density of 100 s is shown in Fig. 35. A near-infrared spectroradiometer (SR-NIR, manufactured by Topcon Corporation) was used to measure the emission spectrum. As shown in Fig. 35, light-emitting device 4 exhibited an emission spectrum with a maximum peak near 803 nm, which was attributable to the emission of [Ir(dmdpbq)2(dpm)] contained in light-emitting layer 813a and light-emitting layer 831b.

[0355] Furthermore, by adopting a microcavity structure, the emission spectrum was narrowed to a half-width of 35 nm. Light-emitting device 4 efficiently emits light in the range of 760 nm to 900 nm, making it highly effective as a light source for sensors and other applications.

[0356] <Viewing angle characteristics of light-emitting device 3> Next, the viewing angle characteristics of the EL spectrum of the light-emitting device 4 were examined.

[0357] First, the EL spectrum of the light-emitting device 4 in the front direction and the EL spectrum in the oblique direction were measured. Specifically, the direction perpendicular to the light-emitting surface of the light-emitting device 4 was set to 0°, and the emission spectrum was measured at a total of 17 points, at 10° intervals from -80° to 80°. A multichannel spectrometer (PMA-12, manufactured by Hamamatsu Photonics KK) was used for the measurements. From the measurement results, the EL spectrum and photon intensity ratio of the light-emitting device 4 at each angle were obtained.

[0358] FIG. 36 shows the EL spectrum of light-emitting device 4 from 0° to 60°.

[0359] FIG. 37 shows the photon intensity at each angle in the light-emitting device 4, with the photon intensity at the front as the reference.

[0360] 36 and 37, it was found that light-emitting device 4 has a large viewing angle dependency, emitting strong light in the front direction. This is because the adoption of a microcavity structure strengthens the light emission in the front direction while weakening the light emission in oblique directions. As such, the viewing angle characteristic of strong light emission in the front direction makes it suitable as a light source for sensor applications such as vein sensors.

[0361] For example, when it is explicitly stated in this specification that X and Y are connected, it is assumed that the specification discloses the cases where X and Y are electrically connected, where X and Y are functionally connected, and where X and Y are directly connected. Therefore, it is not limited to a predetermined connection relationship, for example, a connection relationship shown in a drawing or text, and connection relationships other than those shown in a drawing or text are also assumed to be disclosed in the drawing or text.

[0362] Here, X and Y are assumed to be objects (for example, devices, elements, circuits, wiring, electrodes, terminals, conductive films, layers, etc.).

[0363] An example of a case where X and Y are directly connected is a case where an element that enables an electrical connection between X and Y (for example, a switch, transistor, capacitance element, inductor, resistance element, diode, display element, light-emitting element, load, etc.) is not connected between X and Y, and a case where X and Y are connected without an element that enables an electrical connection between X and Y (for example, a switch, transistor, capacitance element, inductor, resistance element, diode, display element, light-emitting element, load, etc.).

[0364] As an example of a case where X and Y are electrically connected, one or more elements (e.g., a switch, a transistor, a capacitance element, an inductor, a resistance element, a diode, a display element, a light-emitting element, a load, etc.) that enable the electrical connection between X and Y can be connected between X and Y. The switch has a function of controlling on / off. In other words, the switch has a function of being in a conductive state (on state) or a non-conductive state (off state) and controlling whether or not a current flows. Alternatively, the switch has a function of selecting and switching a path for the current to flow. The case where X and Y are electrically connected includes the case where X and Y are directly connected.

[0365] An example of a case where X and Y are functionally connected is when one or more circuits that enable the functional connection between X and Y (for example, logic circuits (inverters, NAND circuits, NOR circuits, etc.), signal conversion circuits (DA conversion circuits, AD conversion circuits, gamma correction circuits, etc.), potential level conversion circuits (power supply circuits (boosting circuits, step-down circuits, etc.), level shifter circuits that change the potential level of a signal, etc.), voltage sources, current sources, switching circuits, amplifier circuits (circuits that can increase the signal amplitude or current amount, operational amplifiers, differential amplifier circuits, source follower circuits, buffer circuits, etc.), signal generation circuits, memory circuits, control circuits, etc.) can be connected between X and Y. As an example, even if another circuit is sandwiched between X and Y, X and Y are considered to be functionally connected if a signal output from X is transmitted to Y. When X and Y are functionally connected, this includes a case where X and Y are directly connected and a case where X and Y are electrically connected.

[0366] Note that when it is explicitly stated that X and Y are electrically connected, it is assumed that the following cases are disclosed in this specification: when X and Y are electrically connected (i.e., when they are connected with another element or another circuit between them), when X and Y are functionally connected (i.e., when they are functionally connected with another circuit between them), and when X and Y are directly connected (i.e., when X and Y are connected without another element or another circuit between them). In other words, when it is explicitly stated that X and Y are electrically connected, it is assumed that the same content as when it is simply and explicitly stated that they are connected is disclosed in this specification.

[0367] For example, when the source (or first terminal, etc.) of the transistor is electrically connected to X via (or without) Z1 and the drain (or second terminal, etc.) of the transistor is electrically connected to Y via (or without) Z2, or when the source (or first terminal, etc.) of the transistor is directly connected to a part of Z1 and another part of Z1 is directly connected to X, and the drain (or second terminal, etc.) of the transistor is directly connected to a part of Z2 and another part of Z2 is directly connected to Y, it can be expressed as follows.

[0368] For example, it can be expressed as follows: "X, Y, and the source (or first terminal, etc.) and drain (or second terminal, etc.) of the transistor are electrically connected to each other, and are electrically connected in the order of X, the source (or first terminal, etc.) of the transistor, the drain (or second terminal, etc.) of the transistor, and Y." Or, it can be expressed as follows: "The source (or first terminal, etc.) of the transistor is electrically connected to X, and the drain (or second terminal, etc.) of the transistor is electrically connected to Y, and X, the source (or first terminal, etc.) of the transistor, the drain (or second terminal, etc.) of the transistor, and Y are electrically connected in this order." Or, it can be expressed as follows: "X is electrically connected to Y via the source (or first terminal, etc.) and drain (or second terminal, etc.) of the transistor, and X, the source (or first terminal, etc.) of the transistor, the drain (or second terminal, etc.) of the transistor, and Y are provided in this connection order." By using expressions similar to these examples to specify the order of connections in a circuit configuration, the source (or first terminal, etc.) and drain (or second terminal, etc.) of a transistor can be distinguished and the technical scope can be determined.

[0369] Alternatively, as another way of expressing this, for example, it can be expressed as follows: "The source (or first terminal, etc.) of the transistor is electrically connected to X via at least a first connection path, the first connection path does not have a second connection path, the second connection path is a path between the source (or first terminal, etc.) of the transistor and the drain (or second terminal, etc.) of the transistor via a transistor, the first connection path is a path via Z1, the drain (or second terminal, etc.) of the transistor is electrically connected to Y via at least a third connection path, the third connection path does not have the second connection path, and the third connection path is a path via Z2." Alternatively, it can be expressed as "the source (or first terminal, etc.) of the transistor is electrically connected to X via Z1 by at least a first connection path, the first connection path does not have a second connection path, the second connection path has a connection path via a transistor, and the drain (or second terminal, etc.) of the transistor is electrically connected to Y via Z2 by at least a third connection path, the third connection path does not have the second connection path." Alternatively, it can be expressed as follows: "The source (or first terminal, etc.) of the transistor is electrically connected to X via Z1 by at least a first electrical path, the first electrical path does not have a second electrical path, the second electrical path is an electrical path from the source (or first terminal, etc.) of the transistor to the drain (or second terminal, etc.) of the transistor, and the drain (or second terminal, etc.) of the transistor is electrically connected to Y via Z2 by at least a third electrical path, the third electrical path does not have a fourth electrical path, and the fourth electrical path is an electrical path from the drain (or second terminal, etc.) of the transistor to the source (or first terminal, etc.) of the transistor." By using expression methods similar to these examples to define connection paths in a circuit configuration, it is possible to distinguish between the source (or first terminal, etc.) and the drain (or second terminal, etc.) of the transistor and determine the technical scope.

[0370] Note that these representation methods are merely examples and are not limited to these. Here, X, Y, Z1, and Z2 are assumed to be objects (for example, devices, elements, circuits, wiring, electrodes, terminals, conductive films, layers, etc.).

[0371] Note that even when independent components are shown electrically connected in a circuit diagram, one component may have the functions of multiple components. For example, if part of a wiring also functions as an electrode, one conductive film has the functions of both wiring and an electrode. Therefore, the term "electrically connected" in this specification also includes such cases where one conductive film has the functions of multiple components. [Explanation of symbols]

[0372] 11: light-emitting device, 12: light-emitting device, 13: light-emitting device, 14: light-emitting device, 15: light-emitting device, 16: light-emitting device, 17: light-emitting device, 18: light-emitting device, 19: light-emitting device, 20: light-emitting device, 101: electrode, 102: electrode, 103a: light-emitting unit, 103b: light-emitting unit, 104: intermediate layer, 105: protective layer, 111a: hole injection layer, 112: hole transport layer, 112a: hole transport layer, 112b: hole transport layer, 113a: light-emitting layer, 113b: light-emitting layer, 114a: electron transport layer, 114b: electron transport layer, 115a: electron injection layer , 115b: electron injection layer, 301: substrate, 302: pixel portion, 303: circuit portion, 304a: circuit portion, 304b: circuit portion, 305: sealing material, 306: substrate, 307: wiring, 308: FPC, 309: transistor, 310: transistor, 311: transistor, 312: transistor, 313: electrode, 314: insulating layer, 315: EL layer, 316: electrode, 317: organic EL device, 318: space, 400: molecular weight, 401: electrode, 402: EL layer, 403: electrode, 405: insulating layer, 406: conductive layer, 407: adhesive layer, 416: conductive layer, 420: substrate, 4 22: adhesive layer, 423: barrier layer, 424: insulating layer, 450: organic EL device, 490a: substrate, 490b: substrate, 490c: barrier layer, 800: substrate, 801: electrode, 802: light-emitting unit, 802a: light-emitting unit, 802b: light-emitting unit, 803: electrode, 804: buffer layer, 811: hole injection layer, 811a: hole injection layer, 811b: hole injection layer, 812: hole transport layer, 812a: hole transport layer, 812b: hole transport layer, 813: light-emitting layer, 813a: light-emitting layer, 813b: light-emitting layer, 814: electron transport layer, 814a: electron transport layer, 814b: electron Transport layer, 815: electron injection layer, 815a: electron injection layer, 815b: electron injection layer, 816: intermediate layer, 831b: light emitting layer, 911: housing, 912: light source, 913: detection stage, 914: imaging device, 915: light emitting section, 916: light emitting section, 917: light emitting section, 921: housing, 922: operation button, 923: detection section, 924: light source, 925: imaging device, 931: housing, 932: operation panel, 933: conveying mechanism, 934: monitor, 935: detection unit, 936: inspected member, 937: imaging device, 938: light source, 981: housing, 982: display section, 983: operation button,984: External connection port, 985: Speaker, 986: Microphone, 987: Camera, 988: Camera,

Claims

1. A light-emitting device having a function of emitting light, the light-emitting device includes an intermediate layer, a first light-emitting layer, a second light-emitting layer, a first electrode, a second electrode, and a reflective film; the intermediate layer includes a hole transport material and a hole acceptor material, the first light-emitting layer has a region located between the first electrode and the intermediate layer; the first light-emitting layer comprises a first light-emitting material; the second light-emitting layer has a region located between the intermediate layer and the second electrode, the second light-emitting layer comprises a second light-emitting material; a spectrum of light emitted from the light emitting device having a maximum at a first wavelength; the reflectance of the reflective film at the first wavelength is higher than the reflectance of the second electrode; the first electrode has a region located between the first light-emitting layer and the reflective film; the transmittance of the first electrode is higher than the transmittance of the second electrode at the first wavelength; the second electrode transmits a portion of the light of the first wavelength and reflects another portion of the light; When the distance between the second electrode and the reflective film is defined as a second distance, the second distance, when multiplied by 1.8, is within a range of 0.3 to 0.6 times the first wavelength.

2. A light-emitting device having a function of emitting light, the light-emitting device includes an intermediate layer, a first light-emitting layer, a second light-emitting layer, a first electrode, a second electrode, and a reflective film; the intermediate layer includes a hole transport material and a hole acceptor material, the first light-emitting layer has a region located between the first electrode and the intermediate layer; the first light-emitting layer comprises a first light-emitting material; the second light-emitting layer has a region located between the intermediate layer and the second electrode, the second light-emitting layer comprises a second light-emitting material; a first distance is a distance between the second light-emitting layer and the first light-emitting layer, and the first distance is 5 nm or more and 65 nm or less; a spectrum of light emitted from the light emitting device having a maximum at a first wavelength; the reflectance of the reflective film at the first wavelength is higher than the reflectance of the second electrode; the first electrode has a region located between the first light-emitting layer and the reflective film; the transmittance of the first electrode is higher than the transmittance of the second electrode at the first wavelength; the second electrode transmits a portion of the light of the first wavelength and reflects another portion of the light; When the distance between the second electrode and the reflective film is defined as a second distance, the second distance, when multiplied by 1.8, is within a range of 0.3 to 0.6 times the first wavelength.

3. A light-emitting device having a function of emitting light, the light-emitting device includes an intermediate layer, a first light-emitting layer, a second light-emitting layer, a first electrode, a second electrode, and a reflective film; the intermediate layer comprises one of a π-electron-rich heteroaromatic compound and an aromatic amine compound, and one of an oxide of a metal belonging to Groups 4 to 8 of the periodic table, a quinodimethane derivative, a chloranil derivative, and a hexaazatriphenylene derivative; the first light-emitting layer has a region located between the first electrode and the intermediate layer; the first light-emitting layer comprises a first light-emitting material; the second light-emitting layer has a region located between the intermediate layer and the second electrode, the second light-emitting layer comprises a second light-emitting material; a spectrum of light emitted from the light emitting device having a maximum at a first wavelength; the reflectance of the reflective film at the first wavelength is higher than the reflectance of the second electrode; the first electrode has a region located between the first light-emitting layer and the reflective film; the transmittance of the first electrode is higher than the transmittance of the second electrode at the first wavelength; the second electrode transmits a portion of the light of the first wavelength and reflects another portion of the light; When the distance between the second electrode and the reflective film is defined as a second distance, the second distance, when multiplied by 1.8, is within a range of 0.3 to 0.6 times the first wavelength.

4. A light-emitting device having a function of emitting light, the light-emitting device includes an intermediate layer, a first light-emitting layer, a second light-emitting layer, a first electrode, a second electrode, and a reflective film; the intermediate layer comprises one of a π-electron-rich heteroaromatic compound and an aromatic amine compound, and one of an oxide of a metal belonging to Groups 4 to 8 of the periodic table, a quinodimethane derivative, a chloranil derivative, and a hexaazatriphenylene derivative; the first light-emitting layer has a region located between the first electrode and the intermediate layer; the first light-emitting layer comprises a first light-emitting material; the second light-emitting layer has a region located between the intermediate layer and the second electrode, the second light-emitting layer comprises a second light-emitting material; a first distance is a distance between the second light-emitting layer and the first light-emitting layer, and the first distance is 5 nm or more and 65 nm or less; a spectrum of light emitted from the light emitting device having a maximum at a first wavelength; the reflectance of the reflective film at the first wavelength is higher than the reflectance of the second electrode; the first electrode has a region located between the first light-emitting layer and the reflective film; the transmittance of the first electrode is higher than the transmittance of the second electrode at the first wavelength; the second electrode transmits a portion of the light of the first wavelength and reflects another portion of the light; When the distance between the second electrode and the reflective film is defined as a second distance, the second distance, when multiplied by 1.8, is within a range of 0.3 to 0.6 times the first wavelength.

5. A light-emitting device having a function of emitting light, the light-emitting device includes an intermediate layer, a first light-emitting layer, a second light-emitting layer, a first electrode, a second electrode, and a reflective film; the intermediate layer comprises an electron transporting material and a donor material, the first light-emitting layer has a region located between the first electrode and the intermediate layer; the first light-emitting layer comprises a first light-emitting material; the second light-emitting layer has a region located between the intermediate layer and the second electrode, the second light-emitting layer comprises a second light-emitting material; a spectrum of light emitted from the light emitting device having a maximum at a first wavelength; the reflectance of the reflective film at the first wavelength is higher than the reflectance of the second electrode; the first electrode has a region located between the first light-emitting layer and the reflective film; the transmittance of the first electrode is higher than the transmittance of the second electrode at the first wavelength; the second electrode transmits a portion of the light of the first wavelength and reflects another portion of the light; When the distance between the second electrode and the reflective film is defined as a second distance, the second distance, when multiplied by 1.8, is within a range of 0.3 to 0.6 times the first wavelength.

6. A light-emitting device having a function of emitting light, the light-emitting device includes an intermediate layer, a first light-emitting layer, a second light-emitting layer, a first electrode, a second electrode, and a reflective film; the intermediate layer comprises an electron transporting material and a donor material, the first light-emitting layer has a region located between the first electrode and the intermediate layer; the first light-emitting layer comprises a first light-emitting material; the second light-emitting layer has a region located between the intermediate layer and the second electrode, the second light-emitting layer comprises a second light-emitting material; a first distance is a distance between the second light-emitting layer and the first light-emitting layer, and the first distance is 5 nm or more and 65 nm or less; a spectrum of light emitted from the light emitting device having a maximum at a first wavelength; the reflectance of the reflective film at the first wavelength is higher than the reflectance of the second electrode; the first electrode has a region located between the first light-emitting layer and the reflective film; the transmittance of the first electrode is higher than the transmittance of the second electrode at the first wavelength; the second electrode transmits a portion of the light of the first wavelength and reflects another portion of the light; When the distance between the second electrode and the reflective film is defined as a second distance, the second distance, when multiplied by 1.8, is within a range of 0.3 to 0.6 times the first wavelength.

7. A light-emitting device having a function of emitting light, the light-emitting device includes an intermediate layer, a first light-emitting layer, a second light-emitting layer, a first electrode, a second electrode, and a reflective film; the intermediate layer comprises either a metal complex or a π-electron-deficient heteroaromatic compound, and either an alkali metal, an alkaline earth metal, a rare earth metal, an alkali metal oxide, an alkaline earth metal oxide, or a Lewis base; the first light-emitting layer has a region located between the first electrode and the intermediate layer; the first light-emitting layer comprises a first light-emitting material; the second light-emitting layer has a region located between the intermediate layer and the second electrode, the second light-emitting layer comprises a second light-emitting material; a spectrum of light emitted from the light emitting device having a maximum at a first wavelength; the reflectance of the reflective film at the first wavelength is higher than the reflectance of the second electrode; the first electrode has a region located between the first light-emitting layer and the reflective film; the transmittance of the first electrode is higher than the transmittance of the second electrode at the first wavelength; the second electrode transmits a portion of the light of the first wavelength and reflects another portion of the light; When the distance between the second electrode and the reflective film is defined as a second distance, the second distance, when multiplied by 1.8, is within a range of 0.3 to 0.6 times the first wavelength.

8. A light-emitting device having a function of emitting light, the light-emitting device includes an intermediate layer, a first light-emitting layer, a second light-emitting layer, a first electrode, a second electrode, and a reflective film; the intermediate layer comprises either a metal complex or a π-electron-deficient heteroaromatic compound, and either an alkali metal, an alkaline earth metal, a rare earth metal, an alkali metal oxide, an alkaline earth metal oxide, or a Lewis base; the first light-emitting layer has a region located between the first electrode and the intermediate layer; the first light-emitting layer comprises a first light-emitting material; the second light-emitting layer has a region located between the intermediate layer and the second electrode, the second light-emitting layer comprises a second light-emitting material; a first distance is a distance between the second light-emitting layer and the first light-emitting layer, and the first distance is 5 nm or more and 65 nm or less; a spectrum of light emitted from the light emitting device having a maximum at a first wavelength; the reflectance of the reflective film at the first wavelength is higher than the reflectance of the second electrode; the first electrode has a region located between the first light-emitting layer and the reflective film; the transmittance of the first electrode is higher than the transmittance of the second electrode at the first wavelength; the second electrode transmits a portion of the light of the first wavelength and reflects another portion of the light; When the distance between the second electrode and the reflective film is defined as a second distance, the second distance, when multiplied by 1.8, is within a range of 0.3 to 0.6 times the first wavelength.

9. A light-emitting device having a function of emitting light, the light-emitting device includes an intermediate layer, a first light-emitting layer, a second light-emitting layer, a first electrode, a second electrode, and a reflective film; the intermediate layer comprises a hole transporting material, an acceptor material, an electron transporting material, and a donor material; the first light-emitting layer has a region located between the first electrode and the intermediate layer; the first light-emitting layer comprises a first light-emitting material; the second light-emitting layer has a region located between the intermediate layer and the second electrode, the second light-emitting layer comprises a second light-emitting material; a spectrum of light emitted from the light emitting device having a maximum at a first wavelength; the reflectance of the reflective film at the first wavelength is higher than the reflectance of the second electrode; the first electrode has a region located between the first light-emitting layer and the reflective film; the transmittance of the first electrode is higher than the transmittance of the second electrode at the first wavelength; the second electrode transmits a portion of the light of the first wavelength and reflects another portion of the light; When the distance between the second electrode and the reflective film is defined as a second distance, the second distance, when multiplied by 1.8, is within a range of 0.3 to 0.6 times the first wavelength.

10. A light-emitting device having a function of emitting light, the light-emitting device includes an intermediate layer, a first light-emitting layer, a second light-emitting layer, a first electrode, a second electrode, and a reflective film; the intermediate layer comprises a hole transporting material, an acceptor material, an electron transporting material, and a donor material; the first light-emitting layer has a region located between the first electrode and the intermediate layer; the first light-emitting layer comprises a first light-emitting material; the second light-emitting layer has a region located between the intermediate layer and the second electrode, the second light-emitting layer comprises a second light-emitting material; a first distance is a distance between the second light-emitting layer and the first light-emitting layer, and the first distance is 5 nm or more and 65 nm or less; a spectrum of light emitted from the light emitting device having a maximum at a first wavelength; the reflectance of the reflective film at the first wavelength is higher than the reflectance of the second electrode; the first electrode has a region located between the first light-emitting layer and the reflective film; the transmittance of the first electrode is higher than the transmittance of the second electrode at the first wavelength; the second electrode transmits a portion of the light of the first wavelength and reflects another portion of the light; When the distance between the second electrode and the reflective film is defined as a second distance, the second distance, when multiplied by 1.8, is within a range of 0.3 to 0.6 times the first wavelength.

11. A light-emitting device having a function of emitting light, the light-emitting device includes an intermediate layer, a first light-emitting layer, a second light-emitting layer, a first electrode, a second electrode, and a reflective film; the intermediate layer comprises any one of a π-electron rich heteroaromatic compound and an aromatic amine compound, any one of an oxide of a metal belonging to Groups 4 to 8 of the periodic table, a quinodimethane derivative, a chloranil derivative, and a hexaazatriphenylene derivative, any one of a metal complex and a π-electron deficient heteroaromatic compound, and any one of an alkali metal, an alkaline earth metal, a rare earth metal, an alkali metal oxide, an alkaline earth metal oxide, and a Lewis base; the first light-emitting layer has a region located between the first electrode and the intermediate layer; the first light-emitting layer comprises a first light-emitting material; the second light-emitting layer has a region located between the intermediate layer and the second electrode, the second light-emitting layer comprises a second light-emitting material; a spectrum of light emitted from the light emitting device having a maximum at a first wavelength; the reflectance of the reflective film at the first wavelength is higher than the reflectance of the second electrode; the first electrode has a region located between the first light-emitting layer and the reflective film; the transmittance of the first electrode is higher than the transmittance of the second electrode at the first wavelength; the second electrode transmits a portion of the light of the first wavelength and reflects another portion of the light; When the distance between the second electrode and the reflective film is defined as a second distance, the second distance, when multiplied by 1.8, is within a range of 0.3 to 0.6 times the first wavelength.

12. A light-emitting device having a function of emitting light, the light-emitting device includes an intermediate layer, a first light-emitting layer, a second light-emitting layer, a first electrode, a second electrode, and a reflective film; the intermediate layer comprises any one of a π-electron rich heteroaromatic compound and an aromatic amine compound, any one of an oxide of a metal belonging to Groups 4 to 8 of the periodic table, a quinodimethane derivative, a chloranil derivative, and a hexaazatriphenylene derivative, any one of a metal complex and a π-electron deficient heteroaromatic compound, and any one of an alkali metal, an alkaline earth metal, a rare earth metal, an alkali metal oxide, an alkaline earth metal oxide, and a Lewis base; the first light-emitting layer has a region located between the first electrode and the intermediate layer; the first light-emitting layer comprises a first light-emitting material; the second light-emitting layer has a region located between the intermediate layer and the second electrode, the second light-emitting layer comprises a second light-emitting material; a first distance is a distance between the second light-emitting layer and the first light-emitting layer, and the first distance is 5 nm or more and 65 nm or less; a spectrum of light emitted from the light emitting device having a maximum at a first wavelength; the reflectance of the reflective film at the first wavelength is higher than the reflectance of the second electrode; the first electrode has a region located between the first light-emitting layer and the reflective film; the transmittance of the first electrode is higher than the transmittance of the second electrode at the first wavelength; the second electrode transmits a portion of the light of the first wavelength and reflects another portion of the light; When the distance between the second electrode and the reflective film is defined as a second distance, the second distance, when multiplied by 1.8, is within a range of 0.3 to 0.6 times the first wavelength.

13. In any one of claims 1 to 12, the first wavelength is EL1; When the distance between the second light-emitting layer and the first light-emitting layer is a first distance D1, A light-emitting device, wherein the first distance D1 and the first wavelength EL1 satisfy the relationship shown in formula (i). (6.3×10 －３ )×EL1≦D1≦(81.3×10 －３ )×EL1 (i)

14. In any one of claims 1 to 13, an emission spectrum of the first luminescent material in solution having a maximum at a second wavelength; an emission spectrum of the second luminescent material in solution having a maximum at a third wavelength; the difference between the first wavelength and the second wavelength is 100 nm or less; A light emitting device, wherein the difference between the first wavelength and the third wavelength is 100 nm or less.

15. In any one of claims 1 to 14, the second light-emitting layer comprises the first light-emitting material.

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