Light emitting device

Abstract

To provide a new light-emitting element. To provide a light-emitting element having high luminous efficiency. To provide a light-emitting element having a high blue index (BI). To provide a light-emitting element with low power consumption.SOLUTION: A light-emitting element comprising: a first electrode; a second electrode; and an EL layer between the first electrode and the second electrode, wherein one of the first electrode and the second electrode is a reflective electrode and the other is a transflective electrode, in the light-emitting element, the EL layer contains an emission center substance, and when the EL layer contains only one kind of emission center substance, photon energy of a peak wavelength of light emitted from the light-emitting element is designed based on an average value of photon energy of light emitted from the emission center substance in a solution state and emission edge energy on a short wavelength side of an emission spectrum of the emission center substance in the solution state.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] One embodiment of the present invention relates to a light-emitting element, a light-emitting device, an electronic device, and a lighting device. The present invention is not limited to the above-mentioned technical fields. The technical field relates to an article, a method, or a manufacturing method. , process, machine, manufacture, or composition of matter Therefore, one embodiment of the present invention disclosed in this specification more specifically relates to The technical fields include semiconductor devices, display devices, liquid crystal display devices, light-emitting devices, lighting devices, and power storage devices. devices, storage devices, imaging devices, driving methods thereof, or manufacturing methods thereof, as examples. Some examples include: [Background technology]

[0002] Electroluminescence (EL) using organic compounds The practical application of light-emitting elements (organic EL elements) that utilize these elements is progressing. The basic structure of a liquid crystal display is a pair of electrodes sandwiching an organic compound layer (EL layer) containing a light-emitting material between them. A voltage is applied to this element to inject carriers, and the recombination energy of the carriers is By utilizing this, light can be emitted from the light-emitting material.

[0003] Since these light-emitting elements are self-luminous, when used as display pixels, they are more efficient than liquid crystals. Flat panels have the advantage of being highly visible and not requiring a backlight. It is more suitable as a display element. Another major advantage of the sensor is that it can be made thin and lightweight. This is also one of its characteristics.

[0004] In addition, these light-emitting elements can have a light-emitting layer formed continuously in two dimensions, This is similar to point light sources such as incandescent bulbs and LEDs, or This is a feature that is difficult to obtain with linear light sources such as fluorescent lamps, so the light-emitting element can be applied to lighting, etc. It is also highly useful as a surface light source.

[0005] Displays and lighting devices using such light-emitting elements are suitable for use in a variety of electronic devices. However, research and development is ongoing to develop light-emitting devices with better characteristics.

[0006] One of the important characteristics of a light-emitting element is the luminous efficiency, which is represented by the external quantum efficiency. As better light-emitting elements can reduce power consumption, they are becoming increasingly important in the global energy market. Considering the energy environment, the higher the efficiency, the better. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-187982 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 element. Another object of the present invention is to provide a light-emitting element with high luminous efficiency. An object of the present invention is to provide a light-emitting device with a high blue index (BI). Another embodiment of the present invention aims to provide a light-emitting element with low power consumption.

[0009] Another embodiment of the present invention is a light-emitting element, a light-emitting device, an electronic device, or a lighting device with low power consumption. The present invention aims to provide an apparatus and an electronic device, respectively.

[0010] Note that the description of these problems does not preclude the existence of other problems. It is not necessary to solve all of these problems. From the description of the section, it is possible to extract other issues. [Means for solving the problem]

[0011] One aspect of the present invention is a semiconductor device comprising a first electrode, a second electrode, and a coupling element between the first electrode and the second electrode. an EL layer sandwiched therebetween, and one of the first electrode and the second electrode is a reflective electrode In the light-emitting device, the EL layer has a light-emitting center material, and the other electrode is a semi-transmissive semi-reflective electrode. The average photon energy of the light emitted by the luminescent center substance in a solution state is E av e [eV] on the short wavelength side of the emission spectrum of the luminescent center substance in the solution state, The emission edge energy is E edge [eV], the peak wavelength of the light emitted from the light emitting element Long photon energy E em [eV] is a light-emitting element represented by the following formula (1).

[0012] E ave ≦E em ≦0.95E edge ···(1)

[0013] Alternatively, another aspect of the present invention is a light-emitting device having the above-described structure, wherein the luminescent center substance exhibits blue luminescence. It is a light emitting element.

[0014] Alternatively, another aspect of the present invention is a first electrode, a second electrode, and a second electrode. and an EL layer sandwiched between the first electrode and the second electrode, In a light-emitting device in which one electrode is a reflective electrode and the other electrode is a semi-transparent semi-reflective electrode, the EL layer emits blue light. The luminescent center substance has a photon energy of light emitted in a solution state. The average energy is E ave [eV], and the luminescence of the luminescent center substance in the solution state The emission edge energy on the short wavelength side of the spectrum is E edge [eV], the light emitting element Photon energy E of the peak wavelength of light emitted from em [eV] is expressed by the following formula (2): It is a light-emitting element.

[0015] E ave +0.02≦E em ≦0.95E edge ···(2)

[0016] Alternatively, another aspect of the present invention is any of the above-mentioned configurations, em is 2.6 eV or more The upper limit of the photoemission is 2.9 eV or less.

[0017] Alternatively, in any one of the above-described configurations, another aspect of the present invention is a semi-transmissive / semi-reflective electrode. an organic compound having a molecular weight of 300 to 1200 on the surface opposite to the surface facing the reflective electrode; The light emitting device has a compound layer formed thereon.

[0018] Alternatively, another aspect of the present invention is any of the above-mentioned configurations, The solvent is a light-emitting device having a relative dielectric constant of 1 or more and 10 or less at room temperature.

[0019] Alternatively, another aspect of the present invention is any of the above-mentioned configurations, The solvent is toluene or chloroform.

[0020] Alternatively, another embodiment of the present invention is a method for manufacturing a semiconductor device according to any one of the above structures, wherein the light-emitting element in the EL layer This is a light-emitting device that contains only one type of central substance.

[0021] Another embodiment of the present invention is a light-emitting element including any one of the above light-emitting elements and a transistor or is a light emitting device having a substrate.

[0022] Another embodiment of the present invention is a light-emitting device including the above light-emitting device and a sensor, an operation button, a speaker, or a is an electronic device having a microphone and

[0023] Another embodiment of the present invention is a lighting device including the above-described light-emitting device and a housing.

[0024] Another embodiment of the present invention is an electronic device including any of the organic compounds described above. be.

[0025] In this specification, the term "light-emitting device" includes an image display device using a light-emitting element. In addition, a connector, such as an anisotropic conductive film or TCP (Tape Carrier), is attached to the light emitting element. The module has a printed wiring board at the end of the TCP. The COG (Chip On Glass) method is used for the module or light emitting element. A module on which an IC (integrated circuit) is directly mounted may have a light-emitting device. In addition, lighting fixtures and the like may have a light-emitting device. [Effects of the Invention]

[0026] According to one embodiment of the present invention, a novel light-emitting element can be provided. In this manner, a light-emitting element with high emission efficiency can be provided. In this case, a light-emitting element having high external quantum efficiency can be provided. In this manner, a light-emitting device with a high blue index can be provided. In another embodiment, a light-emitting element with low power consumption can be provided.

[0027] In another embodiment of the present invention, a light-emitting element, a light-emitting device, an electronic device, a lighting device, or a light-emitting element with low power consumption is provided. A lighting apparatus and an electronic device can each be provided. [Brief explanation of the drawings]

[0028] [Figure 1] 1(A) and 1(B) are diagrams for explaining a method for calculating the average photon energy (Eave) of light emitted from a luminescent center substance in a solution state. [Figure 2] FIG. 2 is a diagram for explaining a method for calculating the emission edge energy (Eedge) on the short wavelength side of the emission spectrum. [Figure 3] FIG. 3 is a diagram illustrating the relationship between the EL emission peak energy (Eem) of a light-emitting element, and the external quantum efficiency (EQE) and blue index (BI). [Figure 4] 4(A) and 4(B) are conceptual diagrams of a light-emitting device. [Figure 5] 5(A) and 5(B) are conceptual diagrams of an active matrix light emitting device. [Figure 6] 6(A) and 6(B) are diagrams showing the lighting device. [Figure 7] 7(A), 7(B1), 7(B2) and 7(C) are diagrams showing electronic devices. [Figure 8] 8(A) to 8(C) are diagrams showing a light source device. [Figure 9] FIG. 9 is a diagram showing a lighting device. [Figure 10] FIG. 10 is a diagram showing a lighting device. [Figure 11] FIG. 11 is a diagram showing an in-vehicle display device and a lighting device. [Figure 12] 12(A) and 12(B) are diagrams showing electronic devices. [Figure 13] 13(A) to 13(C) are diagrams showing electronic devices. [Figure 14] FIG. 14 shows the emission spectrum of N,N'-diphenyl-N,N'-bis[3-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6mFLPAPrn) in a toluene solution. [Figure 15] FIG. 15 is a diagram for explaining a method for calculating the emission edge on the short wavelength side of the PL spectrum of a toluene solution of 1,6mMemFLPAPrn. [Figure 16] FIG. 16 is a graph showing the relationship between the external quantum efficiency (EQE) and the blue index (BI) and the emission peak energy (Eem) of the light-emitting elements 1-1 to 1-8. [Figure 17] FIG. 17 is a diagram showing the emission spectrum of N,N'-bis(3-methylphenyl)-N,N'-bis[3-(9-phenyl-9H-fluoren-9-yl)phenyl]-pyrene-1,6-diamine (abbreviation: 1,6mMemFLPAPrn) in a toluene solution. [Figure 18] FIG. 18 is a diagram for explaining a method for calculating the emission edge on the short wavelength side of the PL spectrum of a toluene solution of 1,6mMemFLPAPrn. [Figure 19] FIG. 19 is a graph showing the relationship between the external quantum efficiency (EQE) and the blue index (BI) and the peak energy (Eem) of light emission in the light-emitting elements 2-1 to 2-8. [Figure 20] FIG. 20 is a diagram showing an emission spectrum of N,N'-(pyrene-1,6-diyl)bis[(6,N-diphenylbenzo[b]naphtho[1,2-d]furan)-8-amine] (abbreviation: 1,6BnfAPrn-03) in a toluene solution. [Figure 21] FIG. 21 is a diagram illustrating a method for calculating the emission edge on the short wavelength side of the PL spectrum of a toluene solution of 1,6BnfAPrn-03. [Figure 22] FIG. 22 is a graph showing the relationship between the external quantum efficiency (EQE) and the blue index (BI) and the peak energy (Eem) of light emission in the light-emitting elements 3-1 to 3-8. [Figure 23] FIG. 23 is a diagram showing an emission spectrum of N,N'-(pyrene-1,6-diyl)bis[(6,N-diphenylbenzo[b]naphtho[1,2-d]furan)-8-amine] (abbreviation: 1,6BnfAPrn-03) in a toluene solution. [Figure 24] FIG. 24 is a diagram illustrating a method for calculating the emission edge on the short wavelength side of the PL spectrum of a toluene solution of 1,6BnfAPrn-03. [Figure 25] FIG. 25 is a graph showing the relationship between the external quantum efficiency (EQE) and the blue index (BI) and the peak energy (Eem) of light emission in the light-emitting elements 4-1 to 4-4. [Figure 26] FIG. 26 is a diagram showing an emission spectrum of N,N'-(pyrene-1,6-diyl)bis(N-phenyl-6-cyclohexylbenzo[b]naphtho[1,2-d]furan-8-amine) (abbreviation: 1,6chBnfAPrn) in a toluene solution. [Figure 27] FIG. 27 is a diagram illustrating a method for calculating the emission edge on the short wavelength side of the PL spectrum of a toluene solution of 1,6chBnfAPrn. [Figure 28] FIG. 28 is a graph showing the relationship between the external quantum efficiency (EQE) and the blue index (BI) and the peak energy (Eem) of light emission in the light-emitting elements 5-1 to 5-8. [Figure 29]FIG. 29 is a diagram showing the emission spectrum of 3,10-bis[N-(9-phenyl-9H-carbazol-2-yl)-N-phenylamino]naphtho[2,3-b;6,7-b′]bisbenzofuran (abbreviation: 3,10PCA2Nbf(IV)-02) in a toluene solution. [Figure 30] FIG. 30 is a diagram illustrating a method for calculating the emission edge on the short wavelength side of the PL spectrum of a toluene solution of 3,10PCA2Nbf(IV)-02. [Figure 31] FIG. 31 is a graph showing the relationship between the external quantum efficiency (EQE) and the blue index (BI) and the peak energy (Eem) of light emission in the light-emitting elements 6-1 to 6-8. [Figure 32] FIG. 32 is a diagram showing the emission spectrum of 3,10-bis[N-(dibenzofuran-3-yl)-N-phenylamino]naphtho[2,3-b;6,7-b′]bisbenzofuran (abbreviation: 3,10FrA2Nbf(IV)-02) in a toluene solution. [Figure 33] FIG. 33 is a diagram illustrating a method for calculating the emission edge on the short wavelength side of the PL spectrum of a toluene solution of 3,10FrA2Nbf(IV)-02. [Figure 34] FIG. 34 is a graph showing the relationship between the external quantum efficiency (EQE) and the blue index (BI) and the peak energy (Eem) of light emission in the light-emitting elements 7-1 to 7-8. DETAILED DESCRIPTION OF THE INVENTION

[0029] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the above description, and the form and details thereof may be changed without departing from the spirit and scope of the present invention. It will be readily apparent to those skilled in the art that various modifications may be made to the present invention. It should not be construed as being limited to the description of the embodiments.

[0030] (Embodiment 1) There are various light-emitting elements that emit light, but the most common are L In contrast to ED, OLED, or organic EL element, uses organic compounds as the luminescent center substance. Organic compounds have broader wavelengths than inorganic compounds due to the influence of vibration levels, etc. It is known that the emission spectrum has a distinctive shape.

[0031] In order to obtain a display with high color reproducibility in display elements such as displays, good color purity is required. Therefore, it is necessary to use a display element that exhibits a wide range of light emission. The organic EL element, which is broad and has relatively low color purity, is used as a display element for the display. In this case, color purity can be improved by using color filters or microcavity structures. There is a saying.

[0032] Compared to color filters that simply cut off light, it is possible to amplify light of the desired wavelength. The application of a microcavity structure that can be used is advantageous in that it reduces the loss of light emission and is efficient. A light-emitting element having a microcavity structure with an appropriate optical path length is used in combination with a color filter. By doing so, it is possible to reduce the amount of light of wavelengths that are cut, resulting in high efficiency and high color purity. Thus, the adoption of the microcavity structure makes it possible to obtain a light-emitting element that emits light in accordance with the This is suitable for improving color purity and maintaining luminous efficiency.

[0033] As mentioned above, an organic EL element is a light-emitting element that uses an organic compound as a light-emitting center substance. However, the spectrum of light emitted by organic compounds is derived from the structure of the organic compounds. It has a wavelength and shape that are specific to the material. The long range varies depending on the type of luminescent center material used in the light-emitting device.

[0034] The present inventors have discovered that a light-emitting device having a microcavity structure satisfies the following formula (1): The light-emitting element has good luminous efficiency (quantum efficiency calculated from the front luminance). found.

[0035] E ave ≦E em ≦0.95E edge ···(1)

[0036] In the above formula, E ave The luminescent center substance used in the light-emitting device is in a solution state. The average photon energy of the light emitted by em is the peak of light emitted from the light emitting element Photon energy of wavelength, E edge is the luminescence of the luminescent center substance in the solution state This is the emission edge energy on the short wavelength side of the spectrum, and all units are [eV].

[0037] <Average photon energy of light emitted by a luminescent center substance in solution (E ave ) Calculation method> E ave The calculation method of is explained with reference to FIG. 1(A). The vertical axis shows the normalized emission spectrum of the organic compound in toluene solution. The emission spectrum is expressed as a function of F(λ) (λ is wavelength): , the number of photons per unit time at each wavelength N p (λ) is N p (λ)=F0F(λ)(F0 is Therefore, the total flow rate of the organic compound in toluene solution per unit time is Photon number N pcan be expressed as the following formula (I): In the following formula (I), ∫F(λ )dλ is the integral value of the emission spectrum in FIG. 1(A).

[0038] N p =∫N p (λ)dλ=F0∫F(λ)dλ ··· (I)

[0039] On the other hand, the energy per unit time of a photon of a certain wavelength φ p (λ) is represented by the following formula (II): In the following formula (II), c is the speed of light and h is Planck's constant. Represents.

[0040] φ p (λ)=N p (λ)·ch / λ=F0F(λ)·ch / λ ··· (II)

[0041] Therefore, in the entire wavelength range per unit time of light emission in a toluene solution of the organic compound, The total energy in the reaction can be expressed by the following formula (III):

[0042] φ p =∫φ p (λ)dλ=F0ch∫F(λ) / λdλ ··· (III)

[0043] The average photon energy of the light emission (E ave ) is the total energy represented by the above formula (III) This is the value obtained by dividing the total number of photons expressed by the above formula (I), and is expressed by the following formula (IV): It is possible.

[0044]

number

[0045] The average emission spectrum of the organic compound in toluene solution shown in Fig. 1(A) ton energy (E ave ) is 2.65 eV, that is, 468 nm from the above formula (IV). (Figure 1(B)) Note that the significant figures are three digits.

[0046] Here, depending on the measuring equipment, the vertical axis of the PL spectrum may be the photon number N p (λ) but Energy φ p (λ) itself (for example, in the case of a spectroradiometer) or Energy φ p In some cases, the normalized spectrum I(λ) is proportional to (λ). In this case, the average photon energy of the emitted light is E ave can be obtained.

[0047] First, from the above formulas (I) and (II), the total number of photons per unit time N p is expressed by the following formula ( V).

[0048] N p =∫N p (λ)dλ=(1 / ch)∫φ p (λ)λdλ (V)

[0049] Therefore, the average photon energy of the emitted light (E ave ) is the vertical axis of the PL spectrum. Energy φ p When the compound is (λ) itself, it can be obtained from the formulas (III) to (V) by the following formula (VI): It can be calculated as follows.

[0050]

number

[0051] Alternatively, when a normalized spectrum I(λ) proportional to the energy is used, the following formula (VII) ) can be found as follows.

[0052]

number

[0053] As mentioned above, the average photon energy of light emission (E ave ) is a toluene solution of organic compounds. Depending on the instrument used to measure the emission spectrum in the liquid, the above formula (IV), (VI) or (V II).

[0054] <Emission edge energy on the short wavelength side of the emission spectrum (E edge ) Calculation method> E edge The calculation method of is explained below. Figure 2 shows the short wavelength side of the luminescent center substance used in Figure 1. An enlarged view of the light-emitting end. edge As shown in Figure 2, the emission spectrum F(λ) At the base of the short wavelength side, a tangent line is drawn near half-value, and the intersection of the tangent line and the x-axis can be found. can.

[0055] In the short wavelength tail of the emission spectrum shown in Figure 2, draw a tangent near half maximum. The intersection point of this line on the x-axis is 432 nm, which is the emission end of the short wavelength side of the emission spectrum. Energy (E edge ) can be calculated to be 2.87 eV.

[0056] In addition, these E ave , E edge PL spectrum of the luminescent center substance used to calculate is the spectrum in the solution state. Each energy level is affected by the relative dielectric constant of the medium. The relative dielectric constant of the organic compound that makes up the EL layer of the light-emitting element is about 3, so at room temperature By measuring in a solvent with a relative dielectric constant of 1 or more and 10 or less, more preferably 2 or more and 5 or less, Specific solvents include hexane, benzene, toluene, and diethylene glycol. ethyl ether, ethyl acetate, chloroform, chlorobenzene, and dichloromethane. In particular, toluene and chloroform have a relative dielectric constant of 2 or more and 5 or less at room temperature, and the solubility is Since toluene and chloroform are common solvents, the The difference between the values ​​in the solvent and those in the solvent is often within experimental error.

[0057] <EL emission peak energy of the light-emitting element (E em ) and external quantum efficiency (EQE) and Regarding the relationship with Lu Index (BI) Figure 3 shows a photoluminescent device with a microcavity structure, in which the luminescent material used in Figures 1 and 2 is used as the luminescent center. Regarding organic EL elements (top emission), em and its relationship with EQE, and E e m The relationship between EQE and BI was investigated. The uncorrected EQE is calculated assuming a cyan light distribution. 2 EQE is used when in the vicinity.

[0058] The blue index (BI) is calculated by dividing the current efficiency (cd / A) by the y chromaticity. This is a value that indicates the luminous characteristics of blue light. The smaller the y chromaticity, the better the blue light emission. Blue light with high color purity tends to be emitted even if the luminance component is small. It is possible to express a wide range of blue colors, and by using blue light with high color purity, The brightness required to express colors is reduced, which has the effect of reducing power consumption. Therefore, BI, which takes into account y chromaticity, which is one of the indicators of blue purity, is used as a means to express the efficiency of blue light emission. The higher the BI of a light-emitting element, the more suitable it is for use as a blue light-emitting element in a display. It can be said that the overall efficiency is good.

[0059] The EL emission peak energy (E em ) is the light emitted by organic EL elements. By changing the path length, the wavelength amplified by the microcavity effect can be adjusted. The E em The EQE plotted against the saturation temperature ranges from 2.65 eV to 2. It shows good efficiency in the range between 73 eV (range A in the figure), and above that E em Symptoms of It can be seen that the EQE of the optical element is significantly reduced. Also, in the same range, the BI is also good. As calculated above, 2.65 eV is the value used in these light-emitting devices. The average photon energy (E) of the luminescence of the luminescent center in toluene solution ave ) Equivalent.

[0060] In addition, the upper limit of range A in the figure, 2.73 eV, is the value calculated above for these organic EL elements. The PL emission spectrum of the luminescent center used in toluene solution is at the short wavelength side. Optical edge energy (E edge )2.87 eV, which is 0.95 times the

[0061] As described above, the organic EL element having a microcavity structure is represented by the following formula (1): The cavity length (optical path length) of the microcavity structure is controlled so that the following relationship is established: In this range, the BI can also be improved. It shows good figures.

[0062] E ave ≦Eem ≦0.95E edge ··· (1) (However, E ave is the luminescence of the luminescent center substance used in the light-emitting device in a toluene solution. represents the average photon energy (unit [eV]), and E edge is the luminescent center The emission edge energy (unit [eV]) on the short wavelength side of the PL emission spectrum in the fluorine solution is shown. S,E em represents the EL emission peak energy (unit [eV]).

[0063] In the case of an organic EL element that emits blue light, it is appropriate to focus on BI. BI and EQE reach their peaks at E em The inventors have found that the difference is shown in Figure 3. As shown in Fig. 1, BI has a higher E than EQE. em is located in a relatively high energy region Therefore, the microcavity structure is designed to satisfy the relationship shown in the following formula (2). It is preferable to control the cavity length (optical path length) of the structure.

[0064] E ave +0.02≦E em ≦ 0.95E edge ···(2)

[0065] The organic EL element according to one embodiment of the present invention is em is 2.6 eV or more and 2.9 eV or less It is preferable.

[0066] The organic EL element according to one embodiment of the present invention is a light-emitting element having a microcavity structure. An organic EL element is a device in which an EL layer containing an organic compound is sandwiched between a pair of electrodes, and a current is passed through the layer. The microcavity structure uses one of the pair of electrodes as a reflective electrode and the other as a By using a semi-transparent / semi-reflective electrode on one side, reflection is repeated, and the distance between the electrodes (cavity It has a structure that can amplify light of a wavelength corresponding to the length of the optical path. The cavity length can be changed by adjusting the thickness of the EL layer and the electrodes. When adjusting the cavity length using an electrode, a transparent electrode such as ITO can be used. When adjusting the EL layer, the thickness of the carrier transport layer and the carrier injection layer can be adjusted. The optical path length can be controlled by

[0067] Regarding the light emission direction of organic EL elements, even if they have a top emission structure, they can be bottom emission. In the case of a top-emission light-emitting element, the light extraction In order to achieve a more effective efficiency, the surface of the semi-transparent and semi-reflective electrode facing the reflective electrode and It is preferable that an organic compound layer having a molecular weight of 300 or more and 1200 or less is formed on the opposite surface. It's nice.

[0068] Note that in the light-emitting element of one embodiment of the present invention, one light-emitting element contains one type of luminescent center substance. It is preferable that:

[0069] The light-emitting element of one embodiment of the present invention having the above structure has high emission efficiency. This makes it possible to

[0070] Next, an example of a light-emitting element according to one embodiment of the present invention will be described in detail below with reference to FIG. 4(A). Reveal.

[0071] The light-emitting element in this embodiment is a light-emitting element including a first electrode 101 and a second electrode 102. The pair of electrodes and the EL layer 103 provided between the first electrode 101 and the second electrode 102. In FIG. 4A, the electrode provided on the fabrication substrate side is referred to as the first electrode 101. and provide an explanation.

[0072] A light-emitting element according to one embodiment of the present invention has a microcavity structure. The light-emitting element having a cavity structure has a pair of electrodes, a reflective electrode and a semi-transparent / semi-transparent electrode. The reflective electrode and the semi-transmissive / semi-reflective electrode are The first electrode 101 and the second electrode 102 are connected between the reflective electrode and the semi-transmissive / semi-reflective electrode. The device has at least an EL layer, and at least a light-emitting layer that serves as a light-emitting region.

[0073] Light-emitting devices with a microcavity structure emit light in all directions from the light-emitting layer contained in the EL layer. The emitted light is reflected by the reflective electrode and the semi-transmissive and semi-reflective electrode, causing resonance.

[0074] The reflectance of the reflective electrode to visible light is 40% to 100%, preferably 70% to 100%. and the resistivity is 1×10 -2 The material for forming the reflective electrode is Examples of the alloy include aluminum (Al) and alloys containing Al. is Al and L (L is titanium (Ti), neodymium (Nd), nickel (Ni), and lanthanum and alloys containing Al and Ti, Or an alloy containing Al, Ni, and La. Aluminum has low resistance and good light reflection. In addition, aluminum is abundant in the earth's crust and is inexpensive, so The use of aluminum can reduce the manufacturing cost of the light-emitting device. g), or Ag and N (N is yttrium (Y), Nd, magnesium (Mg), yttrium (Y), Terbium (Yb), Al, Ti, Gallium (Ga), Zinc (Zn), Indium (In ), tungsten (W), manganese (Mn), tin (Sn), iron (Fe), Ni, copper (C u), palladium (Pd), iridium (Ir), or gold (Au) As an alloy containing silver, for example, an alloy containing silver and palladium may be used. and copper alloys, silver and copper alloys, silver and magnesium alloys, silver and nickel alloys Examples include alloys containing silver and gold, and alloys containing silver and ytterbium. Transition metals such as copper, chromium (Cr), molybdenum (Mo), copper, and titanium can be used. It is possible to form a transparent electrode layer between the reflective electrode and the EL layer using a conductive material that is light-transmitting. The first electrode 101 can be formed by two layers of a reflective electrode and a transparent electrode. The optical path length (cavity length) of the microcavity structure can also be adjusted. The conductive material is indium tin oxide (hereinafter referred to as indium tin oxide). Indium tin oxide (ITSO) containing silicon or silicon oxide (ITO), Indium Zinc Oxide, an oxide containing titanium Contains indium-tin oxide, indium-titanium oxide, tungsten oxide and zinc oxide In FIG. 4(A), the reflective electrode 1 is made of a metal oxide such as indium oxide. The first electrode 101 is composed of the transparent electrode 101-1 and the transparent electrode 101-2.

[0075] The semi-transmissive / semi-reflective electrode has a visible light reflectance of 20% to 80%, preferably 40% or more. Up to 70% and resistivity is 1×10 -2 The semi-transparent and semi-reflective electrodes are The conductive layer is formed by using one or more conductive metals, alloys, conductive compounds, etc. Specifically, for example, indium tin oxide (InTinOx) Indium tin oxide (ITSO) containing silicon or silicon oxide ), Indium Zinc Oxide, Titanium Indium-tin oxide, indium-titanium oxide, tungsten oxide and oxide Metal oxides such as zinc-containing indium oxide can be used. A metal thin film having a thickness of about 1 nm or more and 30 nm or less can be used. Examples of metals include Ag, Ag and Al, Ag and Mg, Ag and Au, and Ag and An alloy such as Yb can be used.

[0076] The reflective electrode and the semi-transmissive / semi-reflective electrode are either the first electrode 101 or the second electrode 102. In FIG. 4A, when the first electrode 101 is on the formation substrate side as described above, Therefore, when the reflective electrode is the first electrode, the light emitting device is a top emitter. When the reflective electrode is the second electrode 102, the light emitting element is a bottom emission type. The first electrode 101 and the second electrode 102 may be either an anode or a cathode. However, FIG. 4A shows the case where the first electrode 101 is an anode.

[0077] In the case of a light emitting element having a top emission structure, the EL layer of the second electrode 102 The light extraction efficiency is improved by providing an organic cap layer 104 on the surface opposite to the surface in contact with 103. In the light-emitting device, the organic cap layer 1 is formed in contact with the electrode 102. By providing 04, the difference in refractive index at the interface between the electrode 102 and the air can be reduced. The light extraction efficiency can be improved. The film thickness is preferably 5 nm or more and 120 nm or less. The organic cap layer 104 has a molecular weight of 30 nm or more and 90 nm or less. It is preferable to use an organic compound layer having a molecular weight of 300 or more and 1200 or less. In this configuration, the second electrode 102 is a semi-transmissive and semi-reflective electrode, To maintain a certain degree of transparency, the film thickness must be thinned, which may result in poor conductivity. Here, by using a conductive material for the organic cap layer 104, the light extraction efficiency can be improved. It is possible to improve the yield of light-emitting device fabrication while ensuring conductivity. In this case, an organic compound that has little absorption in the visible light region can be suitably used. Alternatively, the organic compound used in the EL layer 103 can be used as the organic cap layer 104. In this case, the organic cap layer 104 is formed in the same film forming apparatus or film forming chamber as the EL layer 103. Since the organic cap layer 104 can be easily formed, the organic cap layer 104 can be easily formed.

[0078] The light-emitting element includes a transparent electrode provided in contact with the reflective electrode, a hole injection layer, a hole transport layer, and a The optical distance (K) between the reflective electrode and the semi-transparent / semi-reflective electrode is changed by changing the thickness of the carrier transport layer, such as the This allows the distance between the reflective electrode and the semi-transparent / semi-reflective electrode to be adjusted. In this case, the light of the resonating wavelength can be strengthened and the light of the non-resonating wavelength can be attenuated. In 4(A), the optical path length is adjusted by the transparent electrode 101-2, which is a part of the first electrode 101. However, the optical path length can be adjusted by the hole injection layer 111 as shown in FIG. 4(B). Alternatively, the hole transport layer 112 may be used to adjust the thickness of the hole transport layer 112, or two or more of these may be combined. It can also be used as such.

[0079] Of the emitted light, the light that is reflected by the reflective electrode and returned (first reflected light) is This causes significant interference with the light (first incident light) that directly enters the semi-transmissive / semi-reflective electrode from the layer. The optical distance between the reflective electrode and the light-emitting layer is (2n-1)λ / 4 (where n is a natural number greater than or equal to 1). It is preferable to adjust the optical distance (λ) to the wavelength of the emitted light to be amplified. This allows the phases of the first reflected light and the first incident light to be aligned, thereby amplifying the light emitted from the light-emitting layer. It is possible.

[0080] The microcavity structure makes it possible to enhance the front-direction emission intensity of specific wavelengths. This makes it possible to reduce power consumption.

[0081] The EL layer 103 preferably has a laminated structure, but there are no particular limitations on the laminated structure. There is no specific definition, and the layer may be a hole injection layer, a hole transport layer, an electron transport layer, an electron injection layer, a carrier blocking layer, an excitation layer, or a Various layer structures such as a charge blocking layer and a charge generating layer can be applied. As shown in FIG. 4(A), the hole injection layer 111, the hole transport layer 112, and the light emitting layer 113 are In addition, the structure including the electron transport layer 114 and the electron injection layer 115 and the structure including the electron transport layer 114 and the electron injection layer 115 as shown in FIG. In addition to the hole injection layer 111, the hole transport layer 112, and the light emitting layer 113, the electron transport layer 114 Two types of structures will be described, one having an electron injection layer 115 and the other having a charge generation layer 116. The materials constituting each layer are specifically shown below.

[0082] The hole injection layer 111 is a layer containing a substance having acceptor properties. The substance can be either an organic compound or an inorganic compound.

[0083] Acceptor substances include compounds with electron-withdrawing groups (halogen groups and cyano groups). The compound can be used, for example, 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroethylene. F4-TCNQ, 3,6-difluoro-2,5,7,7,8, 8-Hexacyanoquinodimethane, Chloranil, 2,3,6,7,10,11-Hexacyanoquinodimethane No-1,4,5,8,9,12-hexaazatriphenylene (abbreviation: HAT-CN), 1 ,3,4,5,7,8-Hexafluorotetracyano-naphthoquinodimethane (abbreviation: F6 Compounds having electron-withdrawing groups such as α-TCNNQ can be used. As an organic compound having multiple heteroatoms, there are compounds such as HAT-CN, which have an electron transport mechanism in a condensed aromatic ring having multiple heteroatoms. Compounds having an electron-withdrawing group bonded thereto are preferred because they are thermally stable. Radialene derivatives containing halogen groups such as fluoro groups or cyano groups are electron acceptors. It is preferred because it has very high tolerance, specifically α,α',α''-1,2,3-cyclopropyl Pantriylidene tris[4-cyano-2,3,5,6-tetrafluorobenzeneacetate nitrile], α,α',α''-1,2,3-cyclopropanetriylidenetris[2, 6-Dichloro-3,5-difluoro-4-(trifluoromethyl)benzeneacetonitrile α,α',α''-1,2,3-cyclopropanetriylidenetris[2,3,4 , 5,6-pentafluorobenzeneacetonitrile]. In addition to the organic compounds mentioned above, other substances that have this property include molybdenum oxide and vanadium oxide. Ruthenium oxide, tungsten oxide, manganese oxide, etc. can be used. In addition, phthalocyanine (abbreviated as H2Pc) and copper phthalocyanine (CuPC) are also used. Cyanine-based complex compounds, 4,4'-bis[N-(4-diphenylaminophenyl)- N-phenylamino]biphenyl (abbreviation: DPAB), N,N'-bis{4-[bis(3 -methylphenyl)amino]phenyl}-N,N'-diphenyl-(1,1'-biphenyl aromatic amine compounds such as diamine (diamino)-4,4'-diamine (abbreviation: DNTPD), or poly( 3,4-ethylenedioxythiophene) / poly(styrenesulfonic acid) (PEDOT / P The hole injection layer 111 can also be formed from a polymer such as SS. A material having the above structure is transported from an adjacent hole transport layer (or hole transport material) by application of an electric field. Electrons can be extracted.

[0084] In addition, the hole-injecting layer 111 may be formed by adding an acceptor substance to a substance having a hole-transporting property. A composite material containing an acceptor substance can also be used. By using a composite material with this structure, it is possible to select a material for forming the electrode regardless of the work function. That is, the first electrode 101 can be made of not only a material with a large work function but also a material with a small work function. The acceptor materials include 7,7,8 ,8-Tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation: F4-TC NQ), chloranil, 1,3,4,5,7,8-hexafluorotetracyano-naphthoquinone Acceptor organic compounds such as methyl methyl ether (abbreviated as F6-TCNNQ) and transition metals In addition, metal oxides belonging to groups 4 to 8 of the periodic table can be used. Oxides of metals belonging to groups 4 to 8 of the periodic table can also be used. The oxides include vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, and molybdenum oxide. tungsten oxide, manganese oxide, rhenium oxide, etc. are preferred because of their high electron-accepting properties. Among them, molybdenum oxide is particularly stable in the air, has low hygroscopicity, and is easy to handle. This is preferable.

[0085] As hole transporting substances used in the composite material, aromatic amine compounds and carbazole derivatives are , aromatic hydrocarbons, polymer compounds (oligomers, dendrimers, polymers, etc.), etc. The following organic compounds can be used as hole transporting substances for the composite material: , 10 -6 cm 2 It is preferable that the material has a hole mobility of 1 / Vs or more. The organic compounds that can be used as hole transporting substances in the composite material are specifically listed below. Raise.

[0086] Aromatic amine compounds that can be used in composite materials include N,N'-di(p-tolyl) )-N,N'-diphenyl-p-phenylenediamine (DTDPPA), 4,4' -Bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation Name: DPAB), N,N'-bis{4-[bis(3-methylphenyl)amino]phenyl }-N,N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine (abbreviation: D NTPD), 1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenyl 1,1-bis-(4-bis(4-methyl- (phenyl)-amino-phenyl)-cyclohexane (abbreviation: TAPC), etc. Specific examples of carbazole derivatives include 3-[N-(9-phenylcarbazole] [N-3-yl]-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPC A1), 3,6-bis[N-(9-phenylcarbazol-3-yl)-N-phenyla 3-[N-(1-naphthyl)amino]-9-phenylcarbazole (abbreviation: PCzPCA2), -N-(9-phenylcarbazol-3-yl)amino]-9-phenylcarbazol (abbreviation: PCzPCN1), 4,4'-di(N-carbazolyl)biphenyl (abbreviation: C BP), 1,3,5-tris[4-(N-carbazolyl)phenyl]benzene (abbreviation: T CPB), 9-[4-(10-phenylanthracen-9-yl)phenyl]-9H-ca Carbazolyl (abbreviation: CzPA), 1,4-bis[4-(N-carbazolyl)phenyl]- 2,3,5,6-tetraphenylbenzene, etc. can be used. For example, 2-tert-butyl-9,10-di(2-naphthyl)anthracene (abbreviation Name: t-BuDNA), 2-tert-butyl-9,10-di(1-naphthyl)anthracene 9,10-bis(3,5-diphenylphenyl)anthracene (abbreviation: DPPA) , 2-tert-butyl-9,10-bis(4-phenylphenyl)anthracene (abbreviation : t-BuDBA), 9,10-di(2-naphthyl)anthracene (abbreviation: DNA), 9 ,10-Diphenylanthracene (abbreviation: DPAnth), 2-tert-butylanthracene Helical (abbreviation: t-BuAnth), 9,10-bis(4-methyl-1-naphthyl)anthracene thracene (abbreviation: DMNA), 2-tert-butyl-9,10-bis[2-(1-naphthalene)] 9,10-bis[2-(1-naphthyl)phenyl]anthracene, 9,10-bis[2-(1-naphthyl)phenyl]anthracene anthracene, 2,3,6,7-tetramethyl-9,10-di(1-naphthyl)anthracene , 2,3,6,7-tetramethyl-9,10-di(2-naphthyl)anthracene, 9,9 '-bianthryl, 10,10'-diphenyl-9,9'-bianthryl, 10,10' -bis(2-phenylphenyl)-9,9'-bianthryl, 10,10'-bis[(2 ,3,4,5,6-pentaphenyl)phenyl]-9,9'-bianthryl, anthracene tetracene, rubrene, perylene, 2,5,8,11-tetra(tert-butyl) Perylene, etc. In addition, pentacene, coronene, etc. can also be used. It may have a vinyl skeleton. Examples of aromatic hydrocarbons having a vinyl group include For example, 4,4'-bis(2,2-diphenylvinyl)biphenyl (abbreviation: DPVBi), 9 ,10-bis[4-(2,2-diphenylvinyl)phenyl]anthracene (abbreviation: DP Note that the organic compound of one embodiment of the present invention can also be used. In this case, it is preferable to use F6-TCNNQ as the acceptor material.

[0087] In addition, poly(N-vinylcarbazole) (abbreviated as PVK) and poly(4-vinyltriphenyl) PVTPA), poly[N-(4-{N'-[4-(4-diphenylamine] N'-phenylamino)phenyl]phenyl-N'-phenylamino}phenyl)methacrylamide Name: PTPDMA), poly[N,N'-bis(4-butylphenyl)-N,N'-bis( Polymer compounds such as [(phenyl)benzidine] (abbreviation: Poly-TPD) can also be used. Cut.

[0088] By forming the hole injection layer 111, the hole injection property is improved, and the driving voltage is small. Furthermore, organic compounds having acceptor properties can be easily vapor deposited. It is an easy material to use because it is easy to form a film.

[0089] In addition, when the hole injection layer is formed from the above composite material, the composite material has good conductivity. Therefore, even if it is formed as a thick film, it is unlikely to cause a deterioration in the driving voltage, and it is suitable for a microcavity structure. This is very suitable as a layer for adjusting the cavity length.

[0090] The hole transport layer 112 is formed by including a material having a hole transport property. The material is 1 x 10 -6 cm 2 It is preferable that the hole mobility is equal to or higher than / Vs. The hole-transport layer 112 preferably contains an organic compound according to one embodiment of the present invention. By including the organic compound according to the first aspect in the hole transport layer 112, It is possible to form a layer with a low refractive index on the surface of the light emitting device, thereby improving the external quantum efficiency of the light emitting device. It becomes Noh.

[0091] The material having the hole transport property is 4,4'-bis[N-(1-naphthyl)-N-phenyl]- 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-phenyl 4-phenyl-4'-(9-phenylfluoro)biphenyl (abbreviation: BSPB), 4-phenyl-3'-(phenyl-9-yl)triphenylamine (abbreviation: BPAFLP), 9-phenylfluoren-9-yl)triphenylamine (abbreviation: mBPAFLP), 4 -phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine PCBA1BP, 4,4'-diphenyl-4''-(9-phenyl-9H- Carbazol-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-(1- naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)-triphenyla PCBAN (abbreviation: PCBAN) -9H-carbazol-3-yl)triphenylamine (abbreviation: PCBNBB), 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'-bi Compounds with an aromatic amine skeleton, such as fluorene-2-amine (abbreviated as PCBASF) , 1,3-bis(N-carbazolyl)benzene (abbreviation: mCP), 4,4'-di(N- Carbazolyl)biphenyl (abbreviation: CBP), 3,6-bis(3,5-diphenylphenyl) 3,3'-bis(9-phenyl- 9H-carbazole (abbreviated as PCCP), and ,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene)(abbreviation Name: DBT3P-II), 2,8-diphenyl-4-[4-(9-phenyl-9H-fluoro

[0123] (9-phenyl-2-olen-9-yl)dibenzothiophene (abbreviation: DBTFLP-III), 4 -[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzyl compounds with a thiophene skeleton, such as dibenzothiophene (abbreviated as DBTFLP-IV); 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviation :DBF3P-II), 4-{3-[3-(9-phenyl-9H-fluoren-9-yl )phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II) Among the above, compounds having an aromatic amine skeleton are Compounds having a carbazole skeleton have good reliability and high hole transport properties. This is also preferable because it contributes to reducing the driving voltage. The materials having a hole transporting property are also preferably used as materials for the hole transporting layer 112. It can be used appropriately.

[0092] The light-emitting layer 113 is a layer containing a host material and a light-emitting material. Whether it is a phosphorescent material or a material that exhibits thermally activated delayed fluorescence (TADF), Furthermore, even if the layer is a single layer, different light-emitting materials may be included. The film may be made up of multiple layers.

[0093] In the light-emitting layer 113, materials that can be used as fluorescent materials include, for example: Examples include the following: Other fluorescent materials can also be used.

[0094] 5,6-bis[4-(10-phenyl-9-anthryl)phenyl]-2,2'-bipyridine PAP2BPy, 5,6-bis[4'-(10-phenyl-9-anthracene] N, N'-diphenyl-N,N'-bis[4-(9-phenyl-9H-fluoren-9-yl] )phenyl]pyrene-1,6-diamine (abbreviation: 1,6FLPAPrn), N,N'-biphenyl bis(3-methylphenyl)-N,N'-bis[3-(9-phenyl-9H-fluorene 9-yl)phenyl]-pyrene-1,6-diamine (abbreviation: 1,6mMemFLPAPr n), N,N'-bis[4-(9H-carbazol-9-yl)phenyl]-N,N'- Diphenylstilbene-4,4'-diamine (abbreviation: YGA2S), 4-(9H-carba 4'-(10-phenyl-9-anthryl)triphenylamine ( Abbreviation: YGAPA), 4-(9H-carbazol-9-yl)-4'-(9,10-difluoromethyl) (phenyl-2-anthryl)triphenylamine (abbreviation: 2YGAPPA), N,9-diphenyl Phenyl-N-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazo Perylene, 2,5,8,11-tetra-tert- -butylperylene (TBP), 4-(10-phenyl-9-anthryl)-4'- (9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBA PA), N,N''-(2-tert-butylanthracene-9,10-diyldi-4, 1-phenylene)bis[N,N',N'-triphenyl-1,4-phenylenediamine] (abbreviation: DPABPA), N,9-diphenyl-N-[4-(9,10-diphenyl-2 -anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: 2PCAPPA) , N-[4-(9,10-diphenyl-2-anthryl)phenyl]-N,N',N'- Triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPPA), N,N,N', N',N'',N'',N''',N'''-Octaphenyldibenzo[g,p]chryse N-(9,10,15-tetraamine (abbreviation: DBC1), Coumarin 30, 10-Diphenyl-2-anthryl)-N,9-diphenyl-9H-carbazole-3- Amine (abbreviation: 2PCAPA), N-[9,10-bis(1,1'-biphenyl-2-yl)] [N,9-diphenyl-9H-carbazol-3-amine (abbreviated as 2-anthryl)-N,9-diphenyl-9H-carbazol-3-amine] :2PCABPhA), N-(9,10-diphenyl-2-anthryl)-N,N',N '-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPA), N-[9,1 0-Bis(1,1'-biphenyl-2-yl)-2-anthryl]-N,N',N'-t Triphenyl-1,4-phenylenediamine (abbreviation: 2DPABPhA), 9,10-bis (1,1'-biphenyl-2-yl)-N-[4-(9H-carbazol-9-yl)phenyl] N,N-phenylanthracen-2-amine (abbreviation: 2YGABPhA), ,9-triphenylanthracene-9-amine (abbreviation: DPhAPhA) Coumarin 545 T,N,N'-Diphenylquinacridone (abbreviation: DPQd), rubrene, 5,12-bi Bis(1,1'-biphenyl-4-yl)-6,11-diphenyltetracene (abbreviation: BP T), 2-(2-{2-[4-(dimethylamino)phenyl]ethenyl}-6-methyl- 4H-pyran-4-ylidene)propanedinitrile (abbreviation: DCM1), 2-{2-methyl 6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizidine] 4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCM2), N,N,N',N'-tetrakis(4-methylphenyl)tetracene-5, 11-diamine (abbreviation: p-mPhTD), 7,14-diphenyl-N,N,N',N' -Tetrakis(4-methylphenyl)acenaphtho[1,2-a]fluoranthene-3,1 0-diamine (abbreviation: p-mPhAFD), 2-{2-isopropyl-6-[2-(1, 1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij ]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitri (abbreviation: DCJTI), 2-{2-tert-butyl-6-[2-(1,1,7,7- Tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizine -9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: D CJTB), 2-(2,6-bis{2-[4-(dimethylamino)phenyl]ethenyl} -4H-pyran-4-ylidene)propanedinitrile (abbreviation: BisDCM), 2-{2 ,6-bis[2-(8-methoxy-1,1,7,7-tetramethyl-2,3,6,7-tetramethyl- tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pi N,N'-diphenyl-4-ylidene}propanedinitrile (abbreviation: BisDCJTM), Phenyl-N,N'-(1,6-pyrene-diyl)bis[(6-phenylbenzo[b]naphthyl) 1,6BnfAPrn-03, etc. In particular, 1,6FLPAPrn, 1,6mMemFLPAPrn, and 1,6Bn Condensed aromatic diamine compounds, such as pyrenediamine compounds like fAPrn-03 is preferable because it has a high hole trapping property, and is excellent in luminous efficiency and reliability.

[0095] In the light-emitting layer 113, materials that can be used as phosphorescent materials include, for example: The following are some examples:

[0096] Tris{2-[5-(2-methylphenyl)-4-(2,6-dimethylphenyl)-4H -1,2,4-triazol-3-yl-κN2]phenyl-κC}iridium(III ) (abbreviation: [Ir(mpptz-dmp)3]), tris(5-methyl-3,4-diphenyl Iridium(III) (abbreviation: [Ir(Mpt z)3]), tris[4-(3-biphenyl)-5-isopropyl-3-phenyl-4H -1,2,4-triazolato]iridium(III) (abbreviation: [Ir(iPrptz-3 b) Organometallic iridium complexes with a 4H-triazole skeleton, such as 3), and tris [3-methyl-1-(2-methylphenyl)-5-phenyl-1H-1,2,4-triazol- Zolato]iridium(III) (abbreviation: [Ir(Mptz1-mp)3]), tris(1 -methyl-5-phenyl-3-propyl-1H-1,2,4-triazolato)iridium (III) (abbreviation: [Ir(PrptZ1-Me)3]) Organometallic iridium complexes with fac-tris[1-(2,6-diisopropyl phenyl)-2-phenyl-1H-imidazole]iridium(III) (abbreviation: [Ir (iPrpmi)3]), tris[3-(2,6-dimethylphenyl)-7-methylimide Dazo[1,2-f]phenanthridinato]iridium(III) (abbreviation: [Ir(dmp and organometallic iridium complexes having an imidazole skeleton, such as impt-Me)3). Bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2’ ]iridium( III) Tetrakis(1-pyrazolyl)borate (abbreviation: FIr6), bis[2-(4' ,6'-difluorophenyl)pyridinato-N,C 2’ ]Iridium(III) picolinate bis(2-[3',5'-bis(trifluoromethyl) fluoride] (abbreviation: FIrpic), Phenyl]pyridinato-N,C 2’}Iridium(III) picolinate (abbreviation: [Ir( CF3ppy)2(pic)]), bis[2-(4',6'-difluorophenyl)pyri[ Ginat-N,C 2’ ]Iridium(III) acetylacetonate (abbreviation: FIraca c) Organometallic iridates with phenylpyridine derivatives having electron-withdrawing groups as ligands These are compounds that exhibit blue phosphorescence, with wavelengths from 440 nm to It is a compound that has an emission peak at 520 nm.

[0097] Also, tris(4-methyl-6-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(mppm)3]), tris(4-t-butyl-6-phenylpyrimidinato)yl Ir(tBuppm)3), (acetylacetonato)bis(Ir(tBuppm)3) (6-methyl-4-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(mp pm)2(acac)]), (acetylacetonato)bis(6-tert-butyl-4- Phenylpyrimidinato)iridium(III) (abbreviation: [Ir(tBuppm)2(ac ac)]), (acetylacetonato)bis[6-(2-norbornyl)-4-phenylpiperidinyl] [Ir(nbppm)2(acac)]), (acetylacetonato)bis[5-methyl-6-(2-methylphenyl)-4-phenyl [Pyrimidinato]iridium(III) (abbreviation: [Ir(mpmppm)2(acac)] ), (acetylacetonato)bis(4,6-diphenylpyrimidinato)iridium(II I) (abbreviation: [Ir(dppm)2(acac)]) Organic metal iridium complexes and (acetylacetonato)bis(3,5-dimethyl-2-phenyl) Rupirazinato)iridium(III) (abbreviation: [Ir(mppr-Me)2(acac) ]), (acetylacetonato)bis(5-isopropyl-3-methyl-2-phenylpyridine) Dinato)iridium(III) (abbreviation: [Ir(mppr-iPr)2(acac)]) Organometallic iridium complexes with pyrazine skeletons such as tris(2-phenylpyridinium) Nat-N,C 2’ ) Iridium(III) (abbreviation: [Ir(ppy)3]), bis(2- Phenylpyridinato-N,C 2’ ) Iridium(III) acetylacetonate (abbreviation: [Ir(ppy)2(acac)]), bis(benzo[h]quinolinato)iridium (I II) Acetylacetonate (abbreviation: [Ir(bzq)2(acac)]), tris(benzyl) Tribenzo[h]quinolinato)iridium(III) (abbreviation: [Ir(bzq)3]), tris (2-phenylquinolinato-N,C 2’ ) Iridium(III) (abbreviation: [Ir(pq) 3]), bis(2-phenylquinolinato-N,C 2’ ) Iridium(III) acetylacetone Pyridine skeleton-containing compounds such as setonate (abbreviation: [Ir(pq)2(acac)]) In addition to organometallic iridium complexes, tris(acetylacetonato)(monophenanthroline)tetrahydrogen Rare earth metals such as rubium(III) (abbreviated as [Tb(acac)3(Phen)]) These are mainly compounds that exhibit green phosphorescence, with wavelengths ranging from 500 nm to 6 The emission peak is at 100 nm. The body is particularly preferred because it is remarkably excellent in reliability and luminous efficiency.

[0098] Also, (diisobutyrylmethanato)bis[4,6-bis(3-methylphenyl)pyrimidinyl] Nato]iridium(III) (abbreviation: [Ir(5mdppm)2(dibm)]), bis [4,6-bis(3-methylphenyl)pyrimidinato](dipivaloylmethanato)iridine Ir(III) (abbreviation: [Ir(5mdppm)2(dpm)]), bis[4,6-di( Naphthalen-1-yl)pyrimidinato](dipivaloylmethanato)iridium(III) Organogold compounds with pyrimidine skeletons, such as [Ir(d1npm)2(dpm)] iridium complexes of the genus acetylacetonatobis(2,3,5-triphenylpyrazine) Iridium(III) (abbreviation: [Ir(tppr)2(acac)]), bis(2, 3,5-triphenylpyrazinate)(dipivaloylmethanato)iridium(III)(abbreviation Name: [Ir(tppr)2(dpm])]), (acetylacetonato)bis[2,3-bis(acetylacetonato) [Ir(F Organometallic iridium complexes having a pyrazine skeleton, such as dpq)2(acac)]), Tris(1-phenylisoquinolinato-N,C 2’ ) Iridium(III) (abbreviation: [I r(piq)3]), bis(1-phenylisoquinolinato-N,C 2’ ) Iridium (I II) Pyrithiol, such as acetylacetonate (abbreviation: [Ir(piq)2(acac)]) In addition to organometallic iridium complexes with an iridinium skeleton, 2,3,7,8,12,13,17,1 8-Octaethyl-21H,23H-porphyrin platinum(II) (abbreviation: PtOEP) Platinum complexes such as tris(1,3-diphenyl-1,3-propanedionato)(monof (Phenanthroline) europium(III) (abbreviation: [Eu(DBM)3(Phen)]) , tris[1-(2-thenoyl)-3,3,3-trifluoroacetonato](monofena (Eu(TTA)3(Phen)]) These are compounds that exhibit red phosphorescence, and It has an emission peak between 00 nm and 700 nm. The iridium complex emits red light with good chromaticity.

[0099] In addition to the phosphorescent compounds described above, known phosphorescent light-emitting materials may be selected and used. stomach.

[0100] TADF materials include fullerene and its derivatives, acridine and its derivatives, and eosin. Derivatives of magnesium (Mg), zinc (Zn), cadmium, etc. can also be used. (Cd), tin (Sn), platinum (Pt), indium (In), or palladium (P d) and the like. Examples of the metal-containing porphyrin include: For example, the protoporphyrin-tin fluoride complex (SnF2(Pro to IX), mesoporphyrin-tin fluoride complex (SnF2(Meso IX)), Hematoporphyrin-tin fluoride complex (SnF2(Hemato IX)), Copropor Phyllin tetramethyl ester-tin fluoride complex (SnF2(Copro III-4M e)), octaethylporphyrin-tin fluoride complex (SnF2(OEP)), ethiop Porphyrin-tin fluoride complex (SnF2(Etio I)), octaethylporphyrin -platinum chloride complex (PtCl2OEP) and the like.

[0101] [ka]

[0102] In addition, 2-(biphenyl-4-yl)-4,6-bis(12-phenyl)-4-phenyl-4-methyl-4-phenyl ... (phenylindolo[2,3-a]carbazol-11-yl)-1,3,5-triazine ( Abbreviation: PIC-TRZ) and 9-(4,6-diphenyl-1,3,5-triazine-2- yl)-9'-phenyl-9H,9'H-3,3'-bicarbazole (abbreviation: PCCzT zn), 9-[4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl phenyl]-9'-phenyl-9H,9'H-3,3'-bicarbazole (abbreviation: PCCzPT zn), 2-[4-(10H-phenoxazin-10-yl)phenyl]-4,6-difluoro Phenyl-1,3,5-triazine (abbreviation: PXZ-TRZ), 3-[4-(5-phenyl -5,10-dihydrophenazin-10-yl)phenyl]-4,5-diphenyl-1, 2,4-triazole (abbreviation: PPZ-3TPT), 3-(9,9-dimethyl-9H-azabicyclo[4.2.1.2]phenyl) cridin-10-yl)-9H-xanthen-9-one (abbreviation: ACRXTN), bis[ 4-(9,9-dimethyl-9,10-dihydroacridine)phenyl]sulfone (abbreviation: DMAC-DPS), 10-phenyl-10H,10'H-spiro[acridine-9,9 π-electron-rich heteroaromatic rings such as '-anthracene]-10'-one (abbreviation: ACRSA) A heterocyclic compound having both a π-electron-deficient heteroaromatic ring and a π-electron-deficient heteroaromatic ring can also be used. The compound has a π-electron rich heteroaromatic ring and a π-electron deficient heteroaromatic ring, and therefore has electron transport properties. The π-electron rich heteroaromatic ring and the π-electron deficient heteroaromatic ring are preferable. The substance in which the heteroaromatic ring is directly bonded exhibits the donor property of the π-electron rich heteroaromatic ring and the π-electron deficient heteroaromatic ring. The acceptor properties of the heteroaromatic rings become stronger, and the energy difference between the S1 and T1 levels becomes smaller. Therefore, it is particularly preferable since thermally activated delayed fluorescence can be efficiently obtained. Instead of the toe-shaped heteroaromatic ring, an aromatic ring to which an electron-withdrawing group such as a cyano group is bonded may be used. stomach.

[0103] [ka]

[0104] The host material of the light-emitting layer may be a material having electron transport properties or a material having hole transport properties. A variety of carrier transport materials can be used.

[0105] The material having hole transport properties is a material having hole transport properties contained in the hole transport layer 112. The substances listed as materials can be suitably used.

[0106] Examples of materials having electron transport properties include bis(10-hydroxybenzo[h]quinolinol). Nat)beryllium(II) (abbreviation: BeBq2), bis(2-methyl-8-quinolinolato) )(4-phenylphenolato)aluminum(III) (abbreviation: BAlq), bis(8- Quinolinolato)zinc(II) (abbreviation: Znq), bis[2-(2-benzoxazolyl) phenolato]zinc(II) (abbreviation: ZnPBO), bis[2-(2-benzothiazolyl) phenolato]zinc(II) (abbreviation: ZnBTZ) and other metal complexes, (4-tert-butylphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation :PBD), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl) phenyl)-1,2,4-triazole (abbreviation: TAZ), 1,3-bis[5-(p-te rt-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), 2,2',2''-(1,3,5 -benzenetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TP BI), 2-[3-(dibenzothiophen-4-yl)phenyl]-1-phenyl-1H -benzimidazole (abbreviation: mDBTBIm-II) Heterocyclic compounds and 2-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f ,h]quinoxaline (abbreviation: 2mDBTPDBq-II), 2-[3'-(dibenzothiophene [f,h]quinoxaline (abbreviated as 2-phenyl-4-yl)biphenyl-3-yl)dibenzo[f,h]quinoxaline mDBTBPDBq-II), 2-[3'-(9H-carbazol-9-yl)biphenyl 4,6-[(2-yl)-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzBPDBq) -Bis[3-(phenanthrene-9-yl)phenyl]pyrimidine (abbreviation: 4,6mPn P2Pm), 4,6-bis[3-(4-dibenzothienyl)phenyl]pyrimidine (abbreviation Heterocyclic compounds with diazine skeletons such as 3,5 -Bis[3-(9H-carbazol-9-yl)phenyl]pyridine (abbreviation: 35DCz PPy), 1,3,5-tri[3-(3-pyridyl)-phenyl]benzene (abbreviation: Tm PyPB) and other heterocyclic compounds having a pyridine skeleton. Heterocyclic compounds with an azine skeleton and heterocyclic compounds with a pyridine skeleton have good reliability. In particular, heterocyclic compounds having a diazine (pyrimidine or pyrazine) skeleton are The electron transport property is high, and this contributes to reducing the driving voltage.

[0107] When a fluorescent substance is used as the light-emitting material, the host material is a compound having an anthracene skeleton. A material having an anthracene skeleton is preferably used as a host material for a fluorescent material. When used in this way, it is possible to realize a light-emitting layer having good luminous efficiency and durability. Many materials having a Csene skeleton have a deep HOMO level, and therefore are suitable for use in one embodiment of the present invention. The substance having an anthracene skeleton used as the host material can be Substances with a phenylanthracene skeleton, especially a 9,10-diphenylanthracene skeleton, It is preferable because it is chemically stable. In addition, when the host material has a carbazole skeleton, This is preferable because it improves the hole injection and transport properties, but the benzene ring is further condensed to the carbazole. When the compound contains a benzocarbazole skeleton, the HOMO level is about 0.1 eV higher than that of carbazole. This is particularly preferable because the host material is dibenzocarbamic acid. When the compound contains a carbazole skeleton, the HOMO level is about 0.1 eV shallower than that of carbazole. This is preferable because it allows holes to easily enter, has excellent hole transport properties, and has high heat resistance. Therefore, a more preferable host material is 9,10-diphenylanthracene skeleton. and carbazole skeleton (or benzocarbazole skeleton or dibenzocarbazole skeleton) From the viewpoint of the hole injection and transport properties mentioned above, it is a material that has both carbazole and palladium. Instead of the fluorene skeleton, a benzofluorene skeleton or a dibenzofluorene skeleton may be used. Examples of such substances include 9-phenyl-3-[4-(10-phenyl-9-anthryl )phenyl]-9H-carbazole (abbreviation: PCzPA), 3-[4-(1-naphthyl) -phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPN), 9-[4-(1 0-phenyl-9-anthracenyl)phenyl]-9H-carbazole (abbreviation: 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: 2mBn fPPA), 9-phenyl-10-{4-(9-phenyl-9H-fluoren-9-yl )biphenyl-4'-yl}anthracene (abbreviation: FLPPA), etc. CzPA, cgDBCzPA, 2mBnfPPA, and PCzPA show very good properties Therefore, it is the preferred choice.

[0108] The host material may be a mixture of a plurality of substances. When used, a material having an electron transporting property and a material having a hole transporting property may be mixed. It is preferable to mix a material having an electron transport property with a material having a hole transport property. Therefore, the transport property of the light-emitting layer 113 can be easily adjusted, and the recombination region can be easily controlled. The ratio of the content of the material having hole transport properties to the content of the material having electron transport properties can be The ratio of the material having electron transport properties to the material having electron transport properties may be 1:9 to 9:1.

[0109] Furthermore, these mixed materials may form an exciplex. The exciplex is formed to emit light that overlaps with the wavelength of the lowest energy absorption band of By selecting such a combination, energy transfer becomes smooth and light emission can be obtained efficiently. In addition, the use of this configuration is also preferable because the driving voltage is reduced.

[0110] One embodiment of the present invention is particularly suitable for a light-emitting element that emits blue light.

[0111] The electron transport layer 114 is a layer containing a substance having an electron transport property. Examples of the electron-transporting material include those listed as the materials having electron-transporting properties that can be used as the host material. can be used.

[0112] Between the electron transport layer 114 and the second electrode 102, a lithium fluoride layer was formed as an electron injection layer 115. Lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF2), etc. A layer containing an alkali metal or alkaline earth metal or a compound thereof may be provided. The layer 115 is a layer made of a substance having an electron transporting property and containing an alkali metal or alkaline earth metal Alternatively, a material containing such a compound or an electride may be used. For example, a material in which a high concentration of electrons is added to a mixed oxide of calcium and aluminum is used. Quality, etc.

[0113] Note that the electron-injecting layer 115 is formed using a substance having an electron-transporting property (preferably a substance having a bipyridine skeleton). The fluoride of the alkali metal or alkaline earth metal is in a microcrystalline state in the organic compound having the above-mentioned structure. It is also possible to use a layer containing a concentration of 50 wt% or more of the refractive index of the layer. Since the layer has a low external quantum efficiency, it is possible to provide a light-emitting device with better external quantum efficiency. become.

[0114] In addition, a charge generation layer 116 may be provided instead of the electron injection layer 115 (FIG. 4(B)). When a potential is applied to the charge generating layer 116, holes are generated in the layer in contact with the cathode side of the layer, and electrons are generated in the layer in contact with the anode side. The charge generation layer 116 is a layer that can inject electrons into the layer adjacent to it. At least a P-type layer 117 is included. The P-type layer 117 constitutes the hole injection layer 111 described above. It is preferable to form the P-type layer 1 using the composite material mentioned above as a material that can be used. 17 is a film containing the above-mentioned acceptor material and a hole transport material as materials constituting a composite material. By applying a potential to the P-type layer 117, electrons Electrons are injected into the transport layer 114 and holes are injected into the second electrode 102, which is the cathode, and the light-emitting element operates. Furthermore, since the organic compound of one embodiment of the present invention has a low refractive index, P By using this for the mold layer 117, a light emitting device with good external quantum efficiency can be obtained.

[0115] The charge generation layer 116 includes an electron relay layer 118 and an electron injection buffer layer 119 in addition to the P-type layer 117. Preferably, one or both of layers 119 are provided.

[0116] The electron relay layer 118 contains at least a substance having electron transport properties, and the electron injection buffer layer 1 The electrons are transferred smoothly by preventing the interaction between the P-type layer 117 and the P-type layer 119. The LUMO level of the substance having electron transport properties contained in the relay layer 118 is The LUMO level of the acceptor material in the electron transport layer 114 and the charge generation layer 116 It is preferable that the LUMO level of the electron relay layer 11 is between the LUMO level of the material contained in the adjacent layer. Specific energy levels of the LUMO level in the electron transporting materials used in 8 is set to -5.0 eV or more, preferably -5.0 eV or more and -3.0 eV or less. The electron-transporting material used in the electron relay layer 118 is a phthalocyanine-based material. It is preferred to use materials or metal complexes having metal-oxygen bonds and aromatic ligands.

[0117] The electron injection buffer layer 119 contains an alkali metal, an alkaline earth metal, a rare earth metal, and These compounds (alkali metal compounds (oxides such as lithium oxide, halides, lithium carbonate) Alkaline earth metal compounds (including carbonates such as titanium and cesium carbonate), alkaline earth metal compounds (oxides, halogens compounds of rare earth metals (including oxides, halides, carbonates) or compounds of rare earth metals (including oxides, halides, carbonates) It is possible to use a material with high electron injection properties, such as SiO 2 .

[0118] The electron injection buffer layer 119 is formed by containing a substance having an electron transporting property and a donor substance. When the donor material is an alkali metal, an alkaline earth metal, or a rare earth metal, and their compounds (alkali metal compounds (oxides such as lithium oxide, halides , including carbonates such as lithium carbonate and cesium carbonate), alkaline earth metal compounds (oxides, compounds of rare earth metals (including oxides, halides, carbonates) In addition to tetrathianaphthacene (abbreviated as TTN), nickelocene, decamethicone, An organic compound such as nickelocene can also be used. The electron transport layer 114 may be formed using the same material as that used for forming the electron transport layer 114 described above. This can be done.

[0119] The material forming the second electrode 102 is preferably one having a small work function (specifically, 3.8 eV or less). Bottom) Metals, alloys, electrically conductive compounds, and mixtures thereof can be used. Specific examples of such cathode materials include alkali metals such as lithium (Li) and cesium (Cs). Lithium metals, as well as magnesium (Mg), calcium (Ca), strontium (Sr), etc. Elements belonging to Group 1 or 2 of the Periodic Table of Elements, and alloys containing these elements (MgAg, Rare earth metals such as AlLi), europium (Eu), ytterbium (Yb) and the like, However, when the second electrode 102 and the electron transport layer are connected to each other, By providing an electron injection layer, it is possible to use Al, Ag, ITO, silicon, etc., regardless of the magnitude of the work function. Various conductive materials such as indium oxide-tin oxide containing silicon oxide or silicon oxide are used as the second These conductive materials can be used as the electrode 102. It is possible to form the film using dry methods such as inkjet printing, spin coating, etc. It may also be formed by a wet method using a sol-gel method, or by using a paste of a metal material. Alternatively, the layer may be formed by a wet method.

[0120] The EL layer 103 can be formed by various methods, including dry and wet methods. For example, vacuum deposition, gravure printing, offset printing, screen printing, etc. A printing method, an ink jet method, a spin coating method, or the like may also be used.

[0121] Furthermore, the above-mentioned electrodes or layers may be formed using different film formation methods.

[0122] The structure of the layer provided between the first electrode 101 and the second electrode 102 is the same as that described above. However, it is not limited to the above. The first electrode 101 and the second electrode 102 are arranged so as to suppress quenching caused by the A preferred configuration is one in which a light-emitting region where holes and electrons recombine is provided at a location away from O2.

[0123] Furthermore, recombination in the hole transport layer or electron transport layer in contact with the light-emitting layer 113, particularly in the light-emitting layer 113 The carrier transport layer close to the region suppresses energy transfer from excitons generated in the light-emitting layer. Therefore, the band gap is determined by the luminescent material that constitutes the luminescent layer or the luminescent material contained in the luminescent layer. It is preferable that the material be made of a substance having a band gap larger than the band gap of the material. Desirable.

[0124] (Embodiment 2) In this embodiment mode, a light-emitting device using the light-emitting element described in Embodiment 1 will be described.

[0125] In this embodiment, a light-emitting device manufactured using the light-emitting element described in Embodiment 1 will be described. The description will be made with reference to FIG. 5. FIG. 5(A) is a top view showing a light-emitting device, and FIG. 5(B) is a top view showing a light-emitting device. (A) is a cross-sectional view taken along the lines AB and CD. The drive circuit section (source line drive circuit) 601 shown by the dotted line controls the pixel section 602 includes a driving circuit section (gate line driving circuit) 603. Also, 604 is a sealing substrate. , 605 is a sealing material, and the inside surrounded by the sealing material 605 is a space 607. .

[0126] The lead wiring 608 is connected to the source line driver circuit 601 and the gate line driver circuit 603. The wiring is for transmitting signals, and the FPC (flexible printed circuit board) is the external input terminal. Video signal, clock signal, start signal, reset signal, etc. from the input circuit 609 Although only the FPC is shown here, this FPC has a printed wiring board. The light emitting device in this specification may be a light emitting device. This includes not only the device itself but also the state in which an FPC or PWB is attached to it. do.

[0127] Next, the cross-sectional structure will be described with reference to FIG. A source line driver circuit 601 and a pixel portion are formed. , one pixel in the pixel section 602 is shown.

[0128] The element substrate 610 may be a substrate made of glass, quartz, organic resin, metal, alloy, semiconductor, or the like. FRP (Fiber Reinforced Plastics), PVF (Polyvinyl It is made using a plastic substrate made of a material such as fluoride, polyester, or acrylic resin. It is enough to manufacture it.

[0129] The structure of the transistors used in the pixels and driver circuits is not particularly limited. The transistor may be a top-type transistor or a staggered type transistor. The transistor may be a gate type transistor or a bottom gate type transistor. The semiconductor material is not particularly limited, and examples thereof include silicon, germanium, silicon carbide, and nitride. Gallium or the like can be used. Alternatively, in-type metal oxides such as In-Ga-Zn-based metal oxides can be used. An oxide semiconductor containing at least one of tungsten, gallium, and zinc may be used.

[0130] The crystallinity of the semiconductor material used in the transistor is not particularly limited. A semiconductor having crystallinity (microcrystalline semiconductor, polycrystalline semiconductor, single crystal semiconductor, or a semiconductor having a partially crystalline region) When a semiconductor having crystallinity is used, the transistor This is preferable because it can suppress deterioration of the star characteristics.

[0131] Here, in addition to the transistors provided in the pixels and the driver circuits, It is preferable to use an oxide semiconductor for a semiconductor device such as a transistor. In particular, it is preferable to use an oxide semiconductor having a wider band gap than silicon. By using an oxide semiconductor with a wider band gap than silicon, the off-state of the transistor can be This can reduce the current in the

[0132] The oxide semiconductor preferably contains at least indium (In) or zinc (Zn). In addition, In-M-Zn oxides (where M is Al, Ti, Ga, Ge, Y, Zr, Sn, It is preferable that the oxide semiconductor contains an oxide represented by the formula (metal such as La, Ce or Hf). More preferable.

[0133] In particular, the semiconductor layer has a plurality of crystal portions, and the c-axes of the crystal portions are aligned with the surface on which the semiconductor layer is formed, Alternatively, the oxide is oriented perpendicular to the upper surface of the semiconductor layer and has no grain boundary between adjacent crystal portions. It is preferable to use a nitride semiconductor film.

[0134] By using such materials for the semiconductor layer, fluctuations in electrical characteristics are suppressed, resulting in high reliability. This makes it possible to realize a low-power transistor.

[0135] Furthermore, the transistor having the above-described semiconductor layer can be used as a transistor due to its low off-state current. It is possible to retain the charge stored in the capacitor for a long period of time through such a transistor. By applying a transistor to each pixel, the gradation of the image displayed in each display area can be maintained while driving It is also possible to shut down the circuit. As a result, electronic devices with extremely low power consumption can be realized. It can be realized.

[0136] For stabilizing the characteristics of the transistor, it is preferable to provide an underlayer film. Inorganic films such as silicon oxide film, silicon nitride film, silicon oxynitride film, and silicon nitride oxide film The insulating film can be formed as a single layer or a laminated layer. CVD (Chemical Vapor Deposition) method (Plasma CVD method) , thermal CVD method, MOCVD (Metal Organic CVD) method, etc.), ALD ( Formed using Atomic Layer Deposition (ALD), coating, printing, etc. It should be noted that the undercoat film need not be provided if it is not necessary.

[0137] The FET 623 indicates one of the transistors formed in the driving circuit section 601. The drive circuit is made up of various CMOS circuits, PMOS circuits, or NMOS circuits. In this embodiment, a driver integrated type in which a driving circuit is formed on a substrate is shown. However, this is not necessarily required, and the drive circuit can be formed externally rather than on the substrate. .

[0138] The pixel section 602 includes a switching FET 611, a current control FET 612 and its driver. The pixel is formed by a plurality of pixels including a first electrode 613 electrically connected to the drain. However, the present invention is not limited to this, and a pixel unit that combines three or more FETs and a capacitance element may also be used. good.

[0139] An insulator 614 is formed to cover the end of the first electrode 613. It can be formed by using a photosensitive acrylic resin film of a mold.

[0140] In order to improve the coverage of the EL layer and the like to be formed later, the insulating material 614 is For example, the material of the insulator 614 is When a positive photosensitive acrylic resin is used, the radius of curvature ( It is preferable that the insulating material 614 has a curved surface having a thickness of 0.2 μm to 3 μm. Either a negative photosensitive resin or a positive photosensitive resin can be used.

[0141] An EL layer 616 and a second electrode 617 are formed on the first electrode 613. Here, the material used for the first electrode 613 functioning as an anode is a material having a work function of It is desirable to use a large material, for example, an ITO film or an indium-silicon-containing film. Indium tin oxide film, indium oxide film containing 2 to 20 wt% zinc oxide, titanium nitride film, In addition to single layer films such as ROM film, tungsten film, Zn film, and Pt film, titanium nitride film and aluminum film are also available. a titanium nitride film and an aluminum-based film; A three-layer structure with a silicon film can be used. The resistance is low, good ohmic contact can be achieved, and the electrode can also function as an anode. .

[0142] The EL layer 616 can be formed by a deposition method using a deposition mask, an inkjet method, or a spin coating method. The EL layer 616 is formed by various methods such as the above. Other materials that make up the EL layer 616 include low molecular weight compounds, may be a polymer compound (including an oligomer or a dendrimer).

[0143] Furthermore, a material used for the second electrode 617 formed on the EL layer 616 and functioning as a cathode As the material, materials with a small work function (Al, Mg, Li, Ca, or their alloys or compounds) It is preferable to use a material such as MgAg, MgIn, or AlLi. When the light generated in 6 is transmitted through the second electrode 617, the second electrode 617 is Thin metal films and transparent conductive films (ITO, indium tin oxide containing 2-20 wt% zinc oxide) It uses lamination of indium tin oxide containing indium and silicon, zinc oxide (ZnO, etc.) It's good to do that.

[0144] The first electrode 613, the EL layer 616, and the second electrode 617 form a light-emitting element. The light-emitting element is the light-emitting element described in Embodiment 1. Note that the pixel portion has a plurality of The light emitting device of this embodiment has a light emitting element formed thereon. The light-emitting element described above and light-emitting elements having other configurations may be mixed.

[0145] Furthermore, the sealing substrate 604 is bonded to the element substrate 610 with a sealing material 605. A light emitting element is disposed in a space 607 surrounded by a sub-substrate 610, a sealing substrate 604, and a sealing material 605. 618 is provided. The space 607 is filled with a filler. In addition to being filled with inert gas (nitrogen, argon, etc.), it can also be filled with sealing material. A recess is formed in the sealing substrate, and a desiccant is placed there to prevent deterioration due to moisture. This is a preferable configuration because it can suppress the noise.

[0146] It is preferable to use epoxy resin or glass frit for the sealing material 605. It is desirable that these materials be as impermeable to moisture and oxygen as possible. Materials used for the sealing substrate 604 include glass substrates, quartz substrates, and FRP (Fiber Reinforced Plastics). reinforced plastics), PVF (polyvinyl fluoride), polyester A plastic substrate made of polyester, acrylic resin, or the like can be used.

[0147] Although not shown in Figure 5, a protective film may be provided on the second electrode. The protective film is an organic resin film. The exposed portion of the sealant 605 may be covered with a protective film. A protective film may be formed on the surfaces and sides of the pair of substrates, the sealing layer, the insulating layer, and the like. A rim layer, etc. may be provided over the exposed side surface.

[0148] The protective film can be made of a material that is difficult for impurities such as water to permeate. It is possible to effectively prevent impurities such as these from diffusing from the outside to the inside.

[0149] The materials that make up the protective film include oxides, nitrides, fluorides, sulfides, ternary compounds, and metals. Alternatively, polymers and the like can be used, for example, aluminum oxide, hafnium oxide, hafnium Lanthanum silicate, lanthanum oxide, silicon oxide, strontium titanate, tantalum oxide , titanium oxide, zinc oxide, niobium oxide, zirconium oxide, tin oxide, yttrium oxide , cerium oxide, scandium oxide, erbium oxide, vanadium oxide or indium oxide Materials containing hafnium, aluminum nitride, hafnium nitride, silicon nitride, tantalum nitride, titanium nitride, niobium nitride, molybdenum nitride, zirconium nitride, or gallium nitride, etc. Materials, nitrides containing titanium and aluminum, oxides containing titanium and aluminum , oxides containing aluminum and zinc, sulfides containing manganese and zinc, cerium and sulfides containing erbium and strontium, oxides containing erbium and aluminum, yttrium Materials containing oxides containing lithium and zirconium can be used.

[0150] The protective film can be formed using a film formation method that provides good step coverage. One such method is atomic layer deposition (ALD). The ALD method can be used to form protective materials. It is preferable to use it for films. By using the ALD method, it is possible to eliminate cracks, pinholes, etc. It is possible to form a protective film with reduced defects or with a uniform thickness. Damage to the processed member when forming the protective film can be reduced.

[0151] For example, by forming a protective film using the ALD method, it is possible to fabricate a surface with complex irregularities or a surface with a touch panel. A uniform protective film with few defects can be formed on the top, sides and back of the panel. .

[0152] In this manner, a light-emitting device manufactured using the light-emitting element described in Embodiment 1 can be obtained. This can be done.

[0153] The light-emitting device in this embodiment mode uses the light-emitting element described in Embodiment 1; therefore, Specifically, the light-emitting device described in Embodiment 1 can be obtained. Since the element has high luminous efficiency, it is possible to provide a light-emitting device with low power consumption.

[0154] This embodiment mode can be freely combined with other embodiment modes.

[0155] (Embodiment 3) In this embodiment mode, an example in which the light-emitting element described in Embodiment 1 is used as a lighting device will be described with reference to FIG. 6. 6(B) is a top view of the lighting device, and FIG. 6(A) is a diagram of the lighting device in FIG. 6(B). ef cross-sectional view.

[0156] The lighting device of this embodiment is a light-transmitting substrate 400 serving as a support, on which a first The first electrode 401 is formed on the substrate 10. When light is extracted from the first electrode 401 side, the first electrode 401 is made of a transparent material. The material is formed from a material having the following properties.

[0157] A pad 412 for supplying a voltage to the second electrode 404 is formed on the substrate 400 .

[0158] An EL layer 403 is formed on the first electrode 401. The EL layer 403 is the same as that in Embodiment 1. This corresponds to the configuration of the EL layer 103 in the above. I want to be.

[0159] The second electrode 404 is formed to cover the EL layer 403. When light is extracted from the first electrode 401 side, the second electrode 102 corresponds to the second electrode 102. The first electrode 404 is formed of a highly reflective material. The voltage is supplied by connecting

[0160] As described above, a light-emitting element having the first electrode 401, the EL layer 403, and the second electrode 404 is realized in this embodiment. The lighting device shown in the embodiment has the light emitting element having high luminous efficiency. Therefore, the lighting device in this embodiment can be a lighting device with low power consumption.

[0161] The substrate 400 on which the light emitting element having the above structure is formed and the sealing substrate 407 are sealed with a sealing material 4. The lighting device is completed by fixing and sealing using the sealant 40. Either one of the seal material 5 and 406 may be used. (not shown) can also be mixed with a desiccant, which can absorb moisture. This leads to improved reliability.

[0162] In addition, a part of the pad 412 and the first electrode 401 is extended outside the sealing materials 405 and 406. By providing this, it can be used as an external input terminal. An IC chip 420 equipped with the above may be provided.

[0163] As described above, the lighting device described in this embodiment uses the light-emitting element described in Embodiment 1 as the EL element. Therefore, a light emitting device with low power consumption can be provided.

[0164] (Fourth embodiment) In this embodiment mode, examples of electronic devices each including the light-emitting element described in Embodiment 1 will be described. The light-emitting element described in Embodiment 1 has high luminous efficiency and low power consumption. As a result, the electronic device described in this embodiment has a light-emitting element with low power consumption. The electronic device may have the following configuration.

[0165] As an electronic device to which the light-emitting element is applied, for example, a television set (television or television) (also called revision receivers), monitors for computers, digital cameras, digital Video cameras, digital photo frames, mobile phones (also called mobile phones or mobile phone devices) ), portable game machines, personal digital assistants, audio playback devices, large game machines such as pachinko machines, etc. Specific examples of these electronic devices are listed below.

[0166] 7A shows an example of a television device. The television device includes a housing 710 A display unit 7103 is built into the housing 1. In this case, a stand 7105 is used to hold the housing The display unit 7103 can display images. The display portion 7103 has the light-emitting elements described in Embodiment 1 arranged in matrix. It is composed of:

[0167] The television device can be operated using the operation switches on the housing 7101 or a separate remote control. This can be done by the remote control device 7110. This allows you to control the channel and volume, and the image displayed on the display unit 7103 In addition, the remote control operation device 7110 can be operated. A display portion 7107 for displaying information output from the

[0168] The television device is assumed to be equipped with a receiver, modem, etc. It can receive television broadcasts and can also communicate by wire or wireless via a modem. By connecting to a network, you can send and receive data in one direction (sender to receiver) or two directions (sender to receiver). It is also possible to communicate information between the recipient and the receiver, or between receivers themselves.

[0169] FIG. 7(B1) shows a computer, which includes a main body 7201, a housing 7202, a display portion 7203, and a keyboard. keyboard 7204, external connection port 7205, pointing device 7206, etc. Note that this computer is configured by arranging the light-emitting elements described in Embodiment 1 in a matrix. The display portion 7203 is used for the computer shown in FIG. The computer shown in FIG. 7(B2) may have a keyboard 720. 4. A second display unit 7210 is provided instead of the pointing device 7206. The second display portion 7210 is a touch panel type, and the contents displayed on the second display portion 7210 can be displayed. Input can be made by operating the input display with a finger or a special pen. In addition, the second display portion 7210 can display not only an input display but also other images. The display unit 7203 may also be a touch panel. Two screens are connected by a hinge. This may cause problems such as scratches or breakage on the screen when storing or transporting the device. The occurrence of bubbles can also be prevented.

[0170] FIG. 7C shows an example of a mobile terminal. The mobile phone is built in a housing 7401. In addition to the display unit 7402, operation buttons 7403, an external connection port 7404, a speaker 740 5, a microphone 7406, etc. The mobile phone 7400 is the same as that described in the first embodiment. The display portion 7402 is made by arranging the above light-emitting elements in a matrix.

[0171] The mobile terminal shown in FIG. 7C allows users to input information by touching the display portion 7402 with a finger or the like. In this case, it is possible to make a call or create an email. Operations such as turning on / off the camera can be performed by touching the display portion 7402 with a finger or the like.

[0172] The screen of the display unit 7402 has three main modes. The first is a display mode that mainly displays images. The first mode is a display mode, and the second mode is an input mode that mainly inputs information such as characters. This is a display + input mode that combines two modes: display mode and input mode.

[0173] For example, when making a call or creating an email, the display unit 7402 is used to input characters. This is the main character input mode, and you can input characters displayed on the screen. It is preferable to display a keyboard or number buttons on most of the screen of the display portion 7402. Desirable.

[0174] In addition, the mobile terminal may include a sensor for detecting tilt, such as a gyro or acceleration sensor. By providing a device, the orientation of the mobile terminal (portrait or landscape) can be determined and the screen display of the display portion 7402 can be displayed. The display can be switched automatically.

[0175] The screen mode can be switched by touching the display portion 7402 or by operating the housing 7401. This is done by operating the button 7403. Also, depending on the type of image displayed on the display unit 7402, For example, if the image signal to be displayed on the display unit is a video signal, If it is data, the display mode is switched to, and if it is text data, the input mode is switched to.

[0176] In the input mode, the optical sensor of the display unit 7402 detects a signal and displays it. If there is no input by touch operation on the part 7402 for a certain period of time, the screen mode is changed to the input mode. Alternatively, the display mode may be switched from the normal mode to the display mode.

[0177] The display portion 7402 can also function as an image sensor. By touching the device with your palm or fingers and capturing an image of your palm print or fingerprint, you can authenticate your identity. In addition, a backlight that emits near-infrared light to the display unit or a sensing light that emits near-infrared light By using a source, it is also possible to image finger veins, palm veins, etc.

[0178] Note that the structure described in this embodiment mode may be obtained by appropriately combining the structures described in Embodiment Modes 1 to 3. They can be used in combination.

[0179] As described above, the light-emitting device including the light-emitting element described in Embodiment 1 has a very wide range of application. The light emitting device described in Embodiment 1 can be applied to electronic devices in a variety of fields. By using the light-emitting element, an electronic device with low power consumption can be obtained.

[0180] FIG. 8(A) is a schematic diagram showing an example of a cleaning robot.

[0181] The cleaning robot 5100 has a display 5101 on the top surface and multiple The camera 5102, the brush 5103, and the operation button 5104 are also shown. However, the underside of the cleaning robot 5100 is provided with tires, a suction port, etc. The robot 5100 also has an infrared sensor, an ultrasonic sensor, an acceleration sensor, a piezo sensor, It is equipped with various sensors such as a sensor, a light sensor, and a gyro sensor. 100 is equipped with wireless communication means.

[0182] The cleaning robot 5100 moves by itself, detects the dust 5120, and sucks it out from the suction port on the bottom. It can suck up dirt.

[0183] In addition, the cleaning robot 5100 analyzes the image captured by the camera 5102 and detects the wall, furniture, or It can detect obstacles such as steps. Image analysis can also detect obstacles such as wiring. If an object that may get tangled in the brush 5103 is detected, the rotation of the brush 5103 can be stopped. can.

[0184] The display 5101 can display the remaining battery level and the amount of dust sucked. The route traveled by the cleaning robot 5100 can be displayed on the display 5101. In addition, the display 5101 is a touch panel, and the operation button 5104 is It may be provided in the ray 5101.

[0185] The cleaning robot 5100 can communicate with a portable electronic device 5140 such as a smartphone. The images captured by the camera 5102 can be displayed on the portable electronic device 5140. Therefore, the owner of the Cleaning Robot 5100 can check the status of the room even when he is away from home. In addition, the display on the display 5101 can be displayed on a mobile electronic device such as a smartphone. You can also check it at 5140.

[0186] The light-emitting device according to one embodiment of the present invention can be used for the display 5101 .

[0187] The robot 2100 shown in FIG. 8(B) includes a computing device 2110, an illuminance sensor 2101, a microphone 2102, upper camera 2103, speaker 2104, display 2105, It is equipped with an internal camera 2106, an obstacle sensor 2107, and a movement mechanism 2108.

[0188] The microphone 2102 has a function of detecting the user's voice and environmental sounds. The speaker 2104 has a function of emitting sound. The device 2102 and the speaker 2104 can be used to communicate with the user. It is possible.

[0189] The display 2105 has the function of displaying various information. Any information desired by the user can be displayed on the display 2105. The display 2105 may be equipped with a touch panel. It may be an information terminal that can be charged by placing it in a fixed position on the robot 2100. and enables data transfer.

[0190] The upper camera 2103 and the lower camera 2106 are used to capture images of the surroundings of the robot 2100. The obstacle sensor 2107 detects the obstacles in the robot 210 by using the moving mechanism 2108. When moving forward, the robot can sense whether there are any obstacles in its path. 00 uses an upper camera 2103, a lower camera 2106, and an obstacle sensor 2107. The light-emitting device according to one embodiment of the present invention can recognize the surrounding environment and move safely. It can be used for the display 2105.

[0191] FIG. 8(C) is a diagram showing an example of a goggle-type display. For example, a housing 5000, a display unit 5001, a speaker 5003, an LED lamp 5004, Operation keys 5005 (including a power switch or an operation switch), a connection terminal 5006, a sensor Sa 5007 (force, displacement, position, velocity, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature Degree, chemical substance, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient , vibration, odor, or infrared measurement functions), microphone 5008, The display device 5002 includes two display units 5002, a support unit 5012, earphones 5013, and the like.

[0192] The light-emitting device of one embodiment of the present invention can be used for the display portion 5001 and the second display portion 5002. can.

[0193] FIG. 9 shows an example in which the light-emitting element described in Embodiment 1 is used in a desk lamp, which is a lighting device. The desk lamp shown in FIG. 9 has a housing 2001 and a light source 2002. Alternatively, the lighting device described in the second embodiment may be used.

[0194] FIG. 10 shows an example in which the light-emitting element described in Embodiment 1 is used as an indoor lighting device 3001. The light-emitting element described in Embodiment 1 has high emission efficiency, and therefore, power consumption is low. In addition, the light-emitting element described in Embodiment 1 can be made large in area. Therefore, it can be used as a large-area lighting device. The light-emitting element is thin, and therefore can be used as a thin lighting device.

[0195] The light-emitting element described in the first embodiment can be mounted on the windshield or dashboard of an automobile. FIG. 11 shows a case where the light-emitting element described in Embodiment 1 is applied to a windshield or a door of an automobile. The display areas 5200 to 5203 are examples of the display area 5200 to 5203. 1 shows a display area provided using the light-emitting element according to embodiment 1.

[0196] In this embodiment, the display area 5200 and the display area 5201 are provided on the windshield of a car. The light-emitting element according to the first embodiment is a display device including the light-emitting element according to the first embodiment. By making the first electrode and the second electrode from transparent electrodes, the opposite side can be seen through. In this case, a so-called see-through display device can be obtained. If it is installed on the windshield of a car, it can be installed without obstructing the view. In addition, when a transistor or the like is provided for driving, an organic semiconductor material Transistors that have light-transmitting properties, such as organic transistors using It is advisable to use a transistor.

[0197] The display region 5202 is a display region including the light-emitting element described in Embodiment 1 provided in a pillar portion. The display area 5202 displays an image captured by an imaging means provided on the vehicle body. This can compensate for the visibility obstructed by the pillars. The display area 5203 provided on the board allows the view outside the car to be hidden by the car body. By projecting images from the imaging means installed in the By projecting images that complement the invisible parts, it becomes more natural and less awkward. Safety can be checked without any sense of discomfort.

[0198] The display area 5203 also displays navigation information, speedometer, tachometer, odometer, fuel gauge, gear It can provide various other information by displaying the status, air conditioning settings, etc. The display items and layout can be changed as needed to suit the user's preferences. This information can also be provided in the display areas 5200 to 5202. The display areas 5200 to 5203 can also be used as lighting devices. .

[0199] 12(A) and (B) show a foldable mobile information terminal 5150. The foldable mobile information terminal 5150 includes a housing 5151, a display area 5152, and a bending portion 515 12(A) shows the mobile information terminal 5150 in an unfolded state. Fig. 5B) shows the portable information terminal 5150 in a folded state. Although it has a large display area 5152, it is compact and highly portable when folded.

[0200] The display area 5152 can be folded in half by the bend 5153. 3 is composed of an expandable member and multiple support members, and when folding, The member is stretched, and the bent portion 5153 has a radius of curvature of 2 mm or more, preferably 3 mm or more. It can be folded.

[0201] The display area 5152 is a touch panel (input / output) equipped with a touch sensor (input device). The light-emitting device of one embodiment of the present invention can be used in the display region 5152. Cut.

[0202] 13(A) to 13(C) show a foldable mobile information terminal 9310. 13(A) shows the mobile information terminal 9310 in an unfolded state. The mobile information terminal 9310 is shown in a state in which it is changing from one folded state to the other. FIG. 13C shows the portable information terminal 9310 in a folded state. The foldable design offers excellent portability and a seamless, large viewing area when unfolded. This provides excellent visibility of the display.

[0203] The display panel 9311 is supported by three housings 9315 connected by hinges 9313. The display panel 9311 is a touch panel equipped with a touch sensor (input device). The display panel 9311 may be a display panel (input / output device). The two housings 9315 are bent to open the mobile information terminal 9310. The light-emitting device of one embodiment of the present invention can be reversibly transformed from a folded state to a folded state. It can be used for a display panel 9311. A display area 931 in the display panel 9311 Reference numeral 2 denotes a display area located on the side of the portable information terminal 9310 in a folded state. [Example]

[0204] In this embodiment, the optical path length of a light emitting device having a microcavity structure is changed. The behavior of the external quantum efficiency and blue index (BI) when The structures of the organic compounds used in the light-emitting elements 1-1 to 1-8 fabricated in this example are as follows: As shown below.

[0205] [ka]

[0206] <Method for Fabricating Light-Emitting Elements 1-1 to 1-8> First, silver (Ag), palladium (Pd), and copper (Cu) were deposited on a glass substrate as a reflective electrode. The alloy film (Ag-Pd-Cu (APC) film) was deposited by sputtering to a thickness of 100 nm. After forming a thick film, indium tin oxide containing silicon oxide (ITSO) was sputtered as a transparent electrode. The first electrode 101 was formed by depositing a film with a thickness of 85 nm by a quartz crystal deposition method. The electrode area is 4mm 2 (2mm x 2mm).

[0207] Next, as a pretreatment for forming a light emitting element on the substrate, the substrate surface was washed with water and After baking at ℃ for 1 hour, UV ozone treatment was performed for 370 seconds.

[0208] Then, 10 -4 The substrate is placed in a vacuum deposition apparatus whose inside pressure has been reduced to about 100 Pa. After vacuum baking at 170°C for 30 minutes in the heating chamber of the device, the substrate is left for about 30 minutes. Allow to cool.

[0209] Next, the first electrode 101 is formed so that the surface on which the first electrode 101 is formed faces downward. The substrate was fixed to a substrate holder provided in a vacuum deposition apparatus, and the following was formed on the first electrode 101: 3-[4-(9-phenanthryl)-phenyl]- ]-9-phenyl-9H-carbazole (abbreviation: PCPPn) and molybdenum(VI) oxide and molybdenum oxide were co-deposited in a weight ratio of 1:0.5 (=PCPPn:molybdenum oxide) to form holes. An injection layer 111 was formed.

[0210] The optical path length of the light-emitting element can be changed by changing the film thickness of the hole injection layer 111. In the light-emitting element 1-1, the thickness of the hole injection layer 111 was 10 nm, and in the light-emitting element 1-2, 15 nm, 20 nm for light-emitting element 1-3, 25 nm for light-emitting element 1-4, and 1-5 30 nm for light-emitting element 1-6, 35 nm for light-emitting element 1-7, 40 nm for light-emitting element 1 In -8, it was fabricated at 45nm.

[0211] On the hole injection layer 111, PCPPn was evaporated to a thickness of 15 nm to form a hole transport layer 112.

[0212] Next, 7-[4-(10-phenyl-9-anthryl) phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA) and the above N,N'-diphenyl-N,N'-bis[3-(9-phenyl)- 1,6-diaminopyrene-1,6-diamine (abbreviation: 1, 6mFLPAPrn) in a weight ratio of 1:0.03 (=cgDBCzPA:1,6mFL The light-emitting layer 113 was formed by co-evaporation to a thickness of 25 nm so that the layer was PAPrn.

[0213] Thereafter, cgDBCzPA was evaporated onto the light-emitting layer 113 to a thickness of 5 nm, and the above structure 2,9-bis(naphthalen-2-yl)-4,7-diphenyl- represented by formula (iv) 1,10-phenanthroline (abbreviation: NBPhen) was evaporated to a film thickness of 15 nm. Then, an electron transport layer 114 was formed.

[0214] After forming the electron transport layer 114, lithium fluoride (LiF) was evaporated to a thickness of 1 nm. The electron injection layer 115 is formed by depositing silver (Ag) and magnesium (Mg) at a volume ratio of 1: The second electrode 102 is formed by vapor deposition to a thickness of 0.1 to 10 nm, and a light-emitting element is formed. The second electrode 102 has a function of reflecting light and a function of emitting light. The light emitting device of this embodiment has a semi-transmissive and semi-reflective electrode that has a function of transmitting light. It is a top-emission element that extracts light from the second electrode 102. is 1,3,5-tri(dibenzothiophen-4-yl)-benzophenone represented by the above structural formula (v). The extraction efficiency is improved by depositing 70 nm of benzene (abbreviated as DBT3P-II).

[0215] The device structures of the light-emitting devices 1-1 to 1-8 are summarized in Tables 1 and 2 below. indicates the film thickness of the hole injection layer in each light-emitting element.

[0216] [Table 1]

[0217] [Table 2]

[0218] The fabricated light-emitting device was placed in a glove box with a nitrogen atmosphere, and the light-emitting device was exposed to the atmosphere. The process of sealing with a glass substrate to prevent leakage (sealing material is applied around the element, and After UV treatment and heat treatment at 80°C for 1 hour, measurements were taken. It was.

[0219] The measurement results for the light-emitting elements 1-1 to 1-8 are shown below. 000cd / m 2 The external quantum efficiency is calculated by dividing the front luminance by the Lambertian ray. The uncorrected external quantum efficiency is calculated assuming a uniform light distribution.

[0220] [Table 3]

[0221] In addition, the PL spectrum of the luminescent center substance 1,6mFLPAPrn in toluene solution was The PL spectrum is shown in Figure 14. The PL spectrum was measured using a fluorometer (Hamamatsu Photonics Co., Ltd.). , Edinburgh Instruments FS920) and the average photon Energy E ave When calculating, the formula (I) shown in the first embodiment was used. The average energy of the PL spectrum of 1,6mFLPAPrn in toluene solution is (E ave ) was calculated to be 2.61 eV. The emission edge on the short wavelength side of the PL spectrum in the liquid was determined as shown in Figure 15. The wavelength was 438 nm and the energy was 2.83 eV.

[0222] FIG. 16 shows the peak energy (E em ) external quantum efficiency This is a graph showing the relationship between EQE and Blue Index (BI), with the horizontal axis being E e m where the vertical axis represents EQE and BI.

[0223] From the figure, both EQE and BI em E ave (2.61 eV in this example) and 2. 69 eV. Understood.

[0224] The value of 2.69 eV is E edge This corresponds to 0.95 times the value of 2.83 eV. It is the energy that

[0225] Thus, the blue light-emitting device with a microcavity structure has E ave E edge The cavity length is long enough to obtain a wavelength equivalent to an energy of 0.95 times or less. It was found that the light-emitting element can emit light with good efficiency. Chi, E ave ≦E em ≦0.95E edge (Range A in the figure) By controlling the EQE and BI, both can be maximized.

[0226] Also, especially considering BI, E ave +0.02(eV) or more edge ×0.95( eV) or less em Since a light-emitting element having E ave +0.02≦E em ≦0.95E edge It is preferable to control the cavity length so that it is within the range B in the figure. I found that... [Example]

[0227] In this embodiment, the optical path length of a light emitting device having a microcavity structure is changed. The behavior of the external quantum efficiency and blue index (BI) when The structures of the organic compounds used in the light-emitting elements 2-1 to 2-8 fabricated in this example are as follows: As shown below.

[0228] [ka]

[0229] <Method for Fabricating Light-Emitting Elements 2-1 to 2-8> First, silver (Ag), palladium (Pd), and copper (Cu) were deposited on a glass substrate as a reflective electrode. The alloy film (Ag-Pd-Cu (APC) film) was deposited by sputtering to a thickness of 100 nm. After forming a thick film, indium tin oxide containing silicon oxide (ITSO) was sputtered as a transparent electrode. The first electrode 101 was formed by depositing a film with a thickness of 85 nm by a quartz crystal deposition method. The electrode area is 4mm 2 (2mm x 2mm).

[0230] Next, as a pretreatment for forming a light emitting element on the substrate, the substrate surface was washed with water and After baking at ℃ for 1 hour, UV ozone treatment was performed for 370 seconds.

[0231] Then, 10 -4 The substrate is placed in a vacuum deposition apparatus whose inside pressure has been reduced to about 100 Pa. After vacuum baking at 170°C for 30 minutes in the heating chamber of the device, the substrate is left for about 30 minutes. Allow to cool.

[0232] Next, the first electrode 101 is formed so that the surface on which the first electrode 101 is formed faces downward. The substrate was fixed to a substrate holder provided in a vacuum deposition apparatus, and the following was formed on the first electrode 101: 3-[4-(9-phenanthryl)-phenyl]- ]-9-phenyl-9H-carbazole (abbreviation: PCPPn) and molybdenum(VI) oxide and molybdenum oxide were co-deposited in a weight ratio of 1:0.5 (=PCPPn:molybdenum oxide) to form holes. An injection layer 111 was formed.

[0233] The optical path length of the light-emitting element can be changed by changing the film thickness of the hole injection layer 111. In the light-emitting element 2-1, the thickness of the hole injection layer 111 was 10 nm, and in the light-emitting element 2-2, 15 nm, 20 nm for light-emitting element 2-3, 25 nm for light-emitting element 2-4, and 2-5 30 nm for light-emitting element 2-6, 35 nm for light-emitting element 2-7, 40 nm for light-emitting element 2 In -8, it was fabricated at 45nm.

[0234] On the hole injection layer 111, PCPPn was evaporated to a thickness of 15 nm to form a hole transport layer 112.

[0235] Next, 7-[4-(10-phenyl-9-anthryl) phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA) and the above N,N'-bis(3-methylphenyl)-N,N'-bis[ 3-(9-phenyl-9H-fluoren-9-yl)phenyl)-pyrene-1,6-diazomethane 1,6mMemFLPAPrn) at a weight ratio of 1:0.03 (=cgDB CzPA:1,6mMemFLPAPrn) was co-evaporated to form a 25 nm light-emitting layer 11 3 was formed.

[0236] Thereafter, cgDBCzPA was evaporated onto the light-emitting layer 113 to a thickness of 5 nm, and the above structure 2,9-bis(naphthalen-2-yl)-4,7-diphenyl- represented by formula (iv) 1,10-phenanthroline (abbreviation: NBPhen) was evaporated to a film thickness of 15 nm. Then, an electron transport layer 114 was formed.

[0237] After forming the electron transport layer 114, lithium fluoride (LiF) was evaporated to a thickness of 1 nm. The electron injection layer 115 is formed by depositing silver (Ag) and magnesium (Mg) at a volume ratio of 1: The second electrode 102 is formed by vapor deposition to a thickness of 0.1 nm and 15 nm. Light-emitting elements 2-1 to 2-8 were fabricated. The second electrode 102 has a function of reflecting light and a function of emitting light. The light emitting device of this embodiment has a semi-transmissive and semi-reflective electrode that has a function of transmitting light. It is a top-emission element that extracts light from the second electrode 102. is 1,3,5-tri(dibenzothiophen-4-yl)-benzophenone represented by the above structural formula (v). The extraction efficiency is improved by depositing 70 nm of benzene (abbreviated as DBT3P-II).

[0238] The device structures of the light-emitting devices 2-1 to 2-8 are summarized in Tables 4 and 5 below. indicates the film thickness of the hole injection layer in each light-emitting element.

[0239] [Table 4]

[0240] [Table 5]

[0241] The fabricated light-emitting device was placed in a glove box with a nitrogen atmosphere, and the light-emitting device was exposed to the atmosphere. The process of sealing with a glass substrate to prevent leakage (sealing material is applied around the element, and After UV treatment and heat treatment at 80°C for 1 hour, measurements were taken. It was.

[0242] The measurement results for the light-emitting elements 2-1 to 2-8 are shown below. 000cd / m 2 The external quantum efficiency is calculated by dividing the front luminance by the Lambertian ray. The uncorrected external quantum efficiency is calculated assuming a uniform light distribution.

[0243] [Table 6]

[0244] In addition, the PL spectra of the luminescent center substance 1,6mMemFLPAPrn in toluene solution were The PL spectrum is shown in Figure 17. The PL spectrum was measured using a fluorometer (Hamamatsu Photonics Co., Ltd.). The average flow was measured using a FS920 (manufactured by Edinburgh Instruments). Photon Energy E ave When calculating, the formula (I) shown in the first embodiment was used. As a result, the average PL spectrum of the toluene solution of 1,6mMemFLPAPrn of energy (E ave ) was calculated to be 2.59 eV. The emission edge on the short wavelength side of the PL spectrum of Prn in a toluene solution is shown in Figure 18. The wavelength was calculated as 440 nm and the energy was 2.82 eV.

[0245] FIG. 19 shows the peak energy (E em ) external quantum efficiency This is a graph showing the relationship between EQE and Blue Index (BI), with the horizontal axis being Ee m where the vertical axis represents EQE and BI.

[0246] From the figure, both EQE and BI em E ave (2.59 eV in this example) and 2. 68 eV. Understood.

[0247] The value of 2.68 eV is E edge This corresponds to 0.95 times the value of 2.82 eV. It is the energy that

[0248] Thus, the blue light-emitting device with a microcavity structure has E ave E edge The cavity length is long enough to obtain a wavelength equivalent to an energy of 0.95 times or less. It was found that the light-emitting element can emit light with good efficiency. Chi, E ave ≦E em ≦0.95E edge (Range A in the figure) By controlling the EQE and BI, both can be maximized.

[0249] Also, especially considering BI, E ave +0.02(eV) or more edge ×0.95( eV) or less em Since a light-emitting element having E ave +0.02≦E em ≦0.95E edge It is preferable to control the cavity length so that it is within the range B in the figure. I found that... [Example]

[0250] In this embodiment, the optical path length of a light emitting device having a microcavity structure is changed. The behavior of the external quantum efficiency and blue index (BI) when The structures of the organic compounds used in the light-emitting elements 3-1 to 3-8 fabricated in this example are as follows: As shown below.

[0251] [ka]

[0252] <Method for Fabricating Light-Emitting Elements 3-1 to 3-8> First, silver (Ag), palladium (Pd), and copper (Cu) were deposited on a glass substrate as a reflective electrode. The alloy film (Ag-Pd-Cu (APC) film) was deposited by sputtering to a thickness of 100 nm. After forming a thick film, indium tin oxide containing silicon oxide (ITSO) was sputtered as a transparent electrode. The first electrode 101 was formed by depositing a film with a thickness of 95 nm using a quartz crystal deposition method. The electrode area is 4mm 2 (2mm x 2mm).

[0253] Next, as a pretreatment for forming a light emitting element on the substrate, the substrate surface was washed with water and After baking at ℃ for 1 hour, UV ozone treatment was performed for 370 seconds.

[0254] Then, 10 -4 The substrate is placed in a vacuum deposition apparatus whose inside pressure has been reduced to about 100 Pa. After vacuum baking at 170°C for 30 minutes in the heating chamber of the device, the substrate is left for about 30 minutes. Allow to cool.

[0255] Next, the first electrode 101 is formed so that the surface on which the first electrode 101 is formed faces downward. The substrate was fixed to a substrate holder provided in a vacuum deposition apparatus, and the following was formed on the first electrode 101: 3-[4-(9-phenanthryl)-phenyl]- ]-9-phenyl-9H-carbazole (abbreviation: PCPPn) and molybdenum(VI) oxide and molybdenum oxide were co-deposited in a weight ratio of 1:0.5 (=PCPPn:molybdenum oxide) to form holes. An injection layer 111 was formed.

[0256] The optical path length of the light-emitting element can be changed by changing the film thickness of the hole injection layer 111. In the light-emitting element 3-1, the thickness of the hole injection layer 111 was 10 nm, and in the light-emitting element 3-2, 15 nm, 20 nm for light-emitting element 3-3, 25 nm for light-emitting element 3-4, and 3-5 30 nm for light-emitting element 3-6, 35 nm for light-emitting element 3-7, 40 nm for light-emitting element 3 In -8, it was fabricated at 45nm.

[0257] On the hole injection layer 111, PCPPn was evaporated to a thickness of 15 nm to form a hole transport layer 112.

[0258] Next, 7-[4-(10-phenyl-9-anthryl) phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA) and the above N,N'-(pyrene-1,6-diyl)bis[(6,N- Diphenylbenzo[b]naphtho[1,2-d]furan)-8-amine] (abbreviation: 1,6B nfAPrn-03) in a weight ratio of 1:0.03 (=cgDBCzPA:1,6Bnf The light-emitting layer 113 was formed by co-evaporation to a thickness of 25 nm so that the resulting layer was APrn-03).

[0259] Thereafter, cgDBCzPA was evaporated onto the light-emitting layer 113 to a thickness of 5 nm, and the above structure 2,9-bis(naphthalen-2-yl)-4,7-diphenyl- represented by formula (iv) 1,10-phenanthroline (abbreviation: NBPhen) was evaporated to a film thickness of 15 nm. Then, an electron transport layer 114 was formed.

[0260] After forming the electron transport layer 114, lithium fluoride (LiF) was evaporated to a thickness of 1 nm. The electron injection layer 115 is formed by depositing silver (Ag) and magnesium (Mg) at a volume ratio of 1: The second electrode 102 is formed by vapor deposition to a thickness of 0.1 nm and 15 nm. Light-emitting elements 3-1 to 3-8 were fabricated. The second electrode 102 has a function of reflecting light and a function of emitting light. The light emitting device of this embodiment has a semi-transmissive and semi-reflective electrode that has a function of transmitting light. It is a top-emission element that extracts light from the second electrode 102. is 1,3,5-tri(dibenzothiophen-4-yl)-benzophenone represented by the above structural formula (v). The extraction efficiency is improved by depositing 70 nm of benzene (abbreviated as DBT3P-II).

[0261] The device structures of the light-emitting devices 3-1 to 3-8 are summarized in Tables 7 and 8 below. indicates the film thickness of the hole injection layer in each light-emitting element.

[0262] [Table 7]

[0263] [Table 8]

[0264] The fabricated light-emitting device was placed in a glove box with a nitrogen atmosphere, and the light-emitting device was exposed to the atmosphere. The process of sealing with a glass substrate to prevent leakage (sealing material is applied around the element, and After UV treatment and heat treatment at 80°C for 1 hour, measurements were taken. It was.

[0265] The measurement results for the light-emitting elements 3-1 to 3-8 are shown below. 000cd / m 2 The external quantum efficiency is calculated by dividing the front luminance by the Lambertian ray. The uncorrected external quantum efficiency is calculated assuming a uniform light distribution.

[0266] [Table 9]

[0267] In addition, the PL spectrum of the luminescent center substance 1,6BnfAPrn-03 in toluene solution The PL spectrum is shown in Figure 20. The PL spectrum was measured using a fluorometer (Hamamatsu Photonikko Co., Ltd.). The average number of particles was measured using a FS920 (manufactured by Edinburgh Instruments). ton of energy E ave When calculating, the formula (I) shown in the first embodiment was used. The average energy of the PL spectrum of 1,6BnfAPrn-03 in toluene solution was Energy (E ave ) was calculated to be 2.65 eV. The emission edge on the side of the laser was calculated as shown in Figure 21 and found to be 432 nm. was 2.87 eV.

[0268] FIG. 22 shows the peak energy (E em ) external quantum efficiency This is a graph showing the relationship between EQE and Blue Index (BI), with the horizontal axis being E e m where the vertical axis represents EQE and BI.

[0269] From the figure, both EQE and BI em E ave (2.65 eV in this example) and 2. 73 eV. Understood.

[0270] The value of 2.73 eV is E edge This corresponds to 0.95 times the value of 2.87 eV. It is the energy that

[0271] Thus, the blue light-emitting device with a microcavity structure has E ave E edge The cavity length is long enough to obtain a wavelength equivalent to an energy of 0.95 times or less. It was found that the light-emitting element can emit light with good efficiency. Chi, E ave ≦E em ≦0.95E edge (Range A in the figure) By controlling the EQE and BI, both can be maximized.

[0272] Also, especially considering BI, E ave +0.02 (eV) (2.67 eV in this example) ) or more E edge × 0.95 (eV) or less E em Since a light-emitting element having , E ave +0.02≦E em ≦0.95E edge (Range B in the figure) It has been found that it is preferable to control the tee length. [Example]

[0273] In this embodiment, the optical path length of a light emitting device having a microcavity structure is changed. The behavior of the external quantum efficiency and blue index (BI) when The structures of the organic compounds used in the light-emitting elements 4-1 to 4-4 fabricated in this example are as follows: As shown below.

[0274] [ka]

[0275] <Method for Fabricating Light-Emitting Elements 4-1 to 4-4> First, on a glass substrate, indium tin oxide containing silicon oxide (ITSO) was used as a transparent electrode. After forming a 70 nm thick film, silver (Ag) and palladium ( An alloy film of Ag-Pd-Cu (APC) was formed by sputtering. After forming a film with a thickness of 25 nm, ITSO was sputtered on it as a transparent electrode. The first electrode 101 was formed by depositing a film with a thickness of 10 nm by a coating method. The area is 4mm 2 (2mm x 2mm).

[0276] Next, as a pretreatment for forming a light emitting element on the substrate, the substrate surface was washed with water and After baking at ℃ for 1 hour, UV ozone treatment was performed for 370 seconds.

[0277] Then, 10 -4 The substrate is placed in a vacuum deposition apparatus whose inside pressure has been reduced to about 100 Pa. After vacuum baking at 170°C for 30 minutes in the heating chamber of the device, the substrate is left for about 30 minutes. Allow to cool.

[0278] Next, the first electrode 101 is formed so that the surface on which the first electrode 101 is formed faces downward. The substrate was fixed to a substrate holder provided in a vacuum deposition apparatus, and the following was formed on the first electrode 101: 3-[4-(9-phenanthryl)-phenyl]- ]-9-phenyl-9H-carbazole (abbreviation: PCPPn) and molybdenum(VI) oxide and molybdenum oxide were co-deposited in a weight ratio of 1:0.5 (=PCPPn:molybdenum oxide) to form holes. An injection layer 111 was formed.

[0279] The optical path length of the light-emitting element can be changed by changing the film thickness of the hole injection layer 111. In the light-emitting element 4-1, the thickness of the hole injection layer 111 was 10 nm, and in the light-emitting element 4-2, The light emitting element 4-3 was fabricated at 12.5 nm, the light emitting element 4-4 at 15 nm, and the light emitting element 4-5 at 17.5 nm. Made.

[0280] On the hole injection layer 111, PCPPn was evaporated to a thickness of 15 nm to form a hole transport layer 112.

[0281] Next, 7-[4-(10-phenyl-9-anthryl) phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA) and the above N,N'-(pyrene-1,6-diyl)bis[(6,N- Diphenylbenzo[b]naphtho[1,2-d]furan)-8-amine] (abbreviation: 1,6B nfAPrn-03) in a weight ratio of 1:0.03 (=cgDBCzPA:1,6Bnf The light-emitting layer 113 was formed by co-evaporation to a thickness of 20 nm so that the resulting layer was APrn-03).

[0282] Then, on the light-emitting layer 113, 2-[3′-(dibenzo-p-(phenyl)-2-(2-methylphenyl)-2-(2-phenyl-2-methyl ...phenyl-2-methylphenyl)-2-(2-phenyl-2-methylphenyl)-2-(2- Thiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation :2mDBTBPDBq-II) was evaporated to a film thickness of 10 nm, and the above structural formula (iv 2,9-bis(naphthalen-2-yl)-4,7-diphenyl-1,10- Phenanthroline (abbreviation: NBPhen) was evaporated to a thickness of 10 nm, and electron transport A layer 114 was formed.

[0283] After forming the electron transport layer 114, lithium fluoride (LiF) was evaporated to a thickness of 1 nm. The electron injection layer 115 is formed by depositing aluminum to a thickness of 120 nm, and the second electrode 102 is formed by depositing aluminum to a thickness of 120 nm. The second electrode 102 was formed to fabricate light-emitting elements 4-1 to 4-4. The light emitting element of this embodiment has a bottom electrode that extracts light from the first electrode 101. It is an emission element.

[0284] The device structures of the light-emitting devices 4-1 to 4-4 are summarized in Tables 10 and 11 below. Table 11 shows the film thickness of the hole injection layer in each light-emitting device.

[0285] [Table 10]

[0286] [Table 11]

[0287] The fabricated light-emitting device was placed in a glove box with a nitrogen atmosphere, and the light-emitting device was exposed to the atmosphere. The process of sealing with a glass substrate to prevent leakage (sealing material is applied around the element, and After UV treatment and heat treatment at 80°C for 1 hour, measurements were taken. It was.

[0288] The measurement results for the light-emitting elements 4-1 to 4-4 are shown below. 000cd / m 2 The external quantum efficiency is calculated by dividing the front luminance by the Lambertian ray. The uncorrected external quantum efficiency is calculated assuming a uniform light distribution.

[0289] [Table 12]

[0290] In addition, the PL spectrum of the luminescent center substance 1,6BnfAPrn-03 in toluene solution The PL spectrum is shown in Figure 23. The PL spectrum was measured using a fluorometer (Hamamatsu Photonikko Co., Ltd.). The average number of particles was measured using a FS920 (manufactured by Edinburgh Instruments). ton of energy E ave When calculating, the formula (I) shown in the first embodiment was used. The average energy of the PL spectrum of 1,6BnfAPrn-03 in toluene solution was Energy (E ave ) was calculated to be 2.65 eV. The emission edge on the side of the laser was calculated as shown in Figure 24 and found to be 432 nm. was 2.87 eV.

[0291] FIG. 25 shows the peak energy (E em ) external quantum efficiency This is a graph showing the relationship between EQE and Blue Index (BI), with the horizontal axis being E e m where the vertical axis represents EQE and BI.

[0292] From the figure, both EQE and BI em E ave (2.65 eV in this example) and 2. 73 eV. Understood.

[0293] The value of 2.73 eV is E edge This corresponds to 0.95 times the value of 2.87 eV. It is the energy that

[0294] Thus, the blue light-emitting device with a microcavity structure has E ave E edge The cavity length is long enough to obtain a wavelength equivalent to an energy of 0.95 times or less. It was found that the light-emitting element can emit light with good efficiency. Chi, E ave ≦E em ≦0.95E edge (Range A in the figure) By controlling the EQE and BI, both can be maximized.

[0295] Also, especially considering BI, E ave +0.02 (eV) (2.67 eV in this example) ) or more E edge × 0.95 (eV) or less E em Since a light-emitting element having , E ave +0.02≦E em ≦0.95E edge (Range B in the figure) It has been found that it is preferable to control the tee length. [Example]

[0296] In this embodiment, the optical path length of a light emitting device having a microcavity structure is changed. The behavior of the external quantum efficiency and blue index (BI) when The structures of the organic compounds used in the light-emitting elements 5-1 to 5-8 fabricated in this example are as follows: As shown below.

[0297] [ka]

[0298] <Method for Fabricating Light-Emitting Elements 5-1 to 5-8> First, silver (Ag), palladium (Pd), and copper (Cu) were deposited on a glass substrate as a reflective electrode. The alloy film (Ag-Pd-Cu (APC) film) was deposited by sputtering to a thickness of 100 nm. After forming a thick film, indium tin oxide containing silicon oxide (ITSO) was sputtered as a transparent electrode. The first electrode 101 was formed by depositing a film with a thickness of 85 nm by a quartz crystal deposition method. The electrode area is 4mm 2 (2mm x 2mm).

[0299] Next, as a pretreatment for forming a light emitting element on the substrate, the substrate surface was washed with water and After baking at ℃ for 1 hour, UV ozone treatment was performed for 370 seconds.

[0300] Then, 10 -4 The substrate is placed in a vacuum deposition apparatus whose inside pressure has been reduced to about 100 Pa. After vacuum baking at 170°C for 30 minutes in the heating chamber of the device, the substrate is left for about 30 minutes. Allow to cool.

[0301] Next, the first electrode 101 is formed so that the surface on which the first electrode 101 is formed faces downward. The substrate was fixed to a substrate holder provided in a vacuum deposition apparatus, and the following was formed on the first electrode 101: 3-[4-(9-phenanthryl)-phenyl]- ]-9-phenyl-9H-carbazole (abbreviation: PCPPn) and molybdenum(VI) oxide and molybdenum oxide were co-deposited in a weight ratio of 1:0.5 (=PCPPn:molybdenum oxide) to form holes. An injection layer 111 was formed.

[0302] The optical path length of the light-emitting element can be changed by changing the film thickness of the hole injection layer 111. In the light-emitting element 5-1, the thickness of the hole injection layer 111 was 10 nm, and in the light-emitting element 5-2, 15 nm, 20 nm for light-emitting element 5-3, 25 nm for light-emitting element 5-4, and 5-5 30 nm for light-emitting element 5-6, 35 nm for light-emitting element 5-7, 40 nm for light-emitting element 5 In -8, it was fabricated at 45nm.

[0303] On the hole injection layer 111, PCPPn was evaporated to a thickness of 15 nm to form a hole transport layer 112.

[0304] Next, 7-[4-(10-phenyl-9-anthryl) phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA) and the above N,N'-(pyrene-1,6-diyl)bis(N-phenyl) -6-cyclohexylbenzo[b]naphtho[1,2-d]furan-8-amine) (abbreviation: 1,6chBnfAPrn) in a weight ratio of 1:0.03 (=cgDBCzPA:1,6 The light-emitting layer 113 was formed to a thickness of 25 nm by co-evaporation so that the composition was chloroBnfAPrn).

[0305] Thereafter, cgDBCzPA was evaporated onto the light-emitting layer 113 to a thickness of 5 nm, and the above structure 2,9-bis(naphthalen-2-yl)-4,7-diphenyl- represented by formula (iv) 1,10-phenanthroline (abbreviation: NBPhen) was evaporated to a film thickness of 15 nm. Then, an electron transport layer 114 was formed.

[0306] After forming the electron transport layer 114, lithium fluoride (LiF) was evaporated to a thickness of 1 nm. The electron injection layer 115 is formed by depositing silver (Ag) and magnesium (Mg) at a volume ratio of 1: The second electrode 102 was formed by vapor deposition of 0.1 (=Ag:Mg) to a film thickness of 10 nm. The second electrode 102 was formed to form light-emitting elements 5-1 to 5-8. The semi-transmissive and semi-reflective electrode has both a reflecting function and a light transmitting function. The element is a top-emission element that extracts light from the second electrode 102. On the electrode 102, 1,3,5-tri(dibenzothiophene) represented by the above structural formula (v) -4-yl)-benzene (abbreviation: DBT3P-II) was evaporated to 70 nm, and the extraction efficiency was It is improving.

[0307] The device structures of the light-emitting devices 5-1 to 5-8 are summarized in Tables 13 and 14 below. Table 14 shows the film thickness of the hole injection layer in each light-emitting device.

[0308] [Table 13]

[0309] [Table 14]

[0310] The fabricated light-emitting device was placed in a glove box with a nitrogen atmosphere, and the light-emitting device was exposed to the atmosphere. The process of sealing with a glass substrate to prevent leakage (sealing material is applied around the element, and After UV treatment and heat treatment at 80°C for 1 hour, measurements were taken. It was.

[0311] The measurement results for the light-emitting elements 5-1 to 5-8 are shown below. 000cd / m 2 The external quantum efficiency is calculated by dividing the front luminance by the Lambertian ray. The uncorrected external quantum efficiency is calculated assuming a uniform light distribution.

[0312] [Table 15]

[0313] In addition, the PL spectrum of the luminescent center substance 1,6chBnfAPrn in toluene solution was The PL spectrum is shown in Figure 26. The PL spectrum was measured using a fluorometer (Hamamatsu Photonics Co., Ltd. Edinburgh Instruments FS920) and the average photo Energy E ave When calculating, the formula (I) shown in the first embodiment was used. From the above, the average energy of the PL spectrum of 1,6chBnfAPrn in toluene solution is Ghee (E ave ) was calculated to be 2.65 eV. The emission edge at this point was calculated as shown in Figure 27 and was found to be 432 nm, with an energy of 2 0.87eV.

[0314] FIG. 28 shows the peak energy (E em ) external quantum efficiency This is a graph showing the relationship between EQE and Blue Index (BI), with the horizontal axis being E e m where the vertical axis represents EQE and BI.

[0315] From the figure, both EQE and BI em E ave (2.65 eV in this example) and 2. 73 eV. Understood.

[0316] The value of 2.73 eV is E edge This corresponds to 0.95 times the value of 2.87 eV. It is the energy that

[0317] Thus, the blue light-emitting device with a microcavity structure has E ave E edge The cavity length is long enough to obtain a wavelength equivalent to an energy of 0.95 times or less. It was found that the light-emitting element can emit light with good efficiency. Chi, E ave ≦E em ≦0.95E edge (Range A in the figure) By controlling the EQE and BI, both can be maximized.

[0318] Also, especially considering BI, E ave +0.02 (eV) (2.67 eV in this example) ) or more E edge × 0.95 (eV) or less E em Since a light-emitting element having , E ave +0.02≦E em ≦0.95E edge (Range B in the figure) It has been found that it is preferable to control the tee length. [Example]

[0319] In this embodiment, the optical path length of a light emitting device having a microcavity structure is changed. The behavior of the external quantum efficiency and blue index (BI) when The structures of the organic compounds used in the light-emitting elements 6-1 to 6-8 fabricated in this example are as follows: As shown below.

[0320] [ka]

[0321] <Method for Fabricating Light-Emitting Elements 6-1 to 6-8> First, silver (Ag), palladium (Pd), and copper (Cu) were deposited on a glass substrate as a reflective electrode. The alloy film (Ag-Pd-Cu (APC) film) was deposited by sputtering to a thickness of 100 nm. After forming a thick film, indium tin oxide containing silicon oxide (ITSO) was sputtered as a transparent electrode. The first electrode 101 was formed by depositing a film with a thickness of 85 nm by a quartz crystal deposition method. The electrode area is 4mm 2 (2mm x 2mm).

[0322] Next, as a pretreatment for forming a light emitting element on the substrate, the substrate surface was washed with water and After baking at ℃ for 1 hour, UV ozone treatment was performed for 370 seconds.

[0323] Then, 10 -4 The substrate is placed in a vacuum deposition apparatus whose inside pressure has been reduced to about 100 Pa. After vacuum baking at 170°C for 30 minutes in the heating chamber of the device, the substrate is left for about 30 minutes. Allow to cool.

[0324] Next, the first electrode 101 is formed so that the surface on which the first electrode 101 is formed faces downward. The substrate was fixed to a substrate holder provided in a vacuum deposition apparatus, and the following was formed on the first electrode 101: 3-[4-(9-phenanthryl)-phenyl]- ]-9-phenyl-9H-carbazole (abbreviation: PCPPn) and molybdenum(VI) oxide and molybdenum oxide were co-deposited in a weight ratio of 1:0.5 (=PCPPn:molybdenum oxide) to form holes. An injection layer 111 was formed.

[0325] The optical path length of the light-emitting element can be changed by changing the film thickness of the hole injection layer 111. In the light-emitting element 6-1, the thickness of the hole injection layer 111 was 10 nm, and in the light-emitting element 6-2, 15 nm, 20 nm for light-emitting element 6-3, 25 nm for light-emitting element 6-4, and 6-5 30 nm for light-emitting element 6-6, 35 nm for light-emitting element 6-7, 40 nm for light-emitting element 6 In -8, it was fabricated at 45nm.

[0326] On the hole injection layer 111, PCPPn was evaporated to a thickness of 15 nm to form a hole transport layer 112.

[0327] Next, 7-[4-(10-phenyl-9-anthryl) phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA) and the above 3,10-bis[N-(9-phenyl-9H-carbazole- 2-yl)-N-phenylamino]naphtho[2,3-b;6,7-b']bisbenzofura (abbreviation: 3,10PCA2Nbf(IV)-02) in a weight ratio of 1:0.01 (=c 25 nm co-evaporation of gDBCzPA:3,10PCA2Nbf(IV)-02 Thus, the light-emitting layer 113 was formed.

[0328] Thereafter, cgDBCzPA was evaporated onto the light-emitting layer 113 to a thickness of 5 nm, and the above structure 2,9-bis(naphthalen-2-yl)-4,7-diphenyl- represented by formula (iv) 1,10-phenanthroline (abbreviation: NBPhen) was evaporated to a film thickness of 15 nm. Then, an electron transport layer 114 was formed.

[0329] After forming the electron transport layer 114, lithium fluoride (LiF) was evaporated to a thickness of 1 nm. The electron injection layer 115 is formed by depositing silver (Ag) and magnesium (Mg) at a volume ratio of 1: The second electrode 102 was formed by vapor deposition of 0.1 (=Ag:Mg) to a film thickness of 10 nm. The second electrode 102 was formed to form light-emitting elements 6-1 to 6-8. The semi-transmissive and semi-reflective electrode has both a reflecting function and a light transmitting function. The element is a top-emission element that extracts light from the second electrode 102. On the electrode 102, 1,3,5-tri(dibenzothiophene) represented by the above structural formula (v) -4-yl)-benzene (abbreviation: DBT3P-II) was evaporated to 70 nm, and the extraction efficiency was It is improving.

[0330] The device structures of the light-emitting devices 6-1 to 6-8 are summarized in Tables 16 and 17 below. Table 17 shows the film thickness of the hole injection layer in each light-emitting device.

[0331] [Table 16]

[0332] [Table 17]

[0333] The fabricated light-emitting device was placed in a glove box with a nitrogen atmosphere, and the light-emitting device was exposed to the atmosphere. The process of sealing with a glass substrate to prevent leakage (sealing material is applied around the element, and After UV treatment and heat treatment at 80°C for 1 hour, measurements were taken. It was.

[0334] The measurement results for the light-emitting elements 6-1 to 6-8 are shown below. 000cd / m 2 The external quantum efficiency is calculated by dividing the front luminance by the Lambertian ray. The uncorrected external quantum efficiency is calculated assuming a uniform light distribution.

[0335] [Table 18]

[0336] In addition, the luminescent center substance 3,10PCA2Nbf(IV)-02 in toluene solution The PL spectrum is shown in Figure 29. The PL spectrum was measured using absolute PL quantum yield measurement. Using a device (Quantaurus-QY manufactured by Hamamatsu Photonics Co., Ltd.), the P The L spectrum has an energy φ on the vertical axis. p (λ) is the normalized spectrum I(λ) proportional to Therefore, in this example, the average photon energy of the emitted light E ave When asking for Formula (VII) shown in embodiment 1 was used. The average energy (E ave )teeth The emission edge on the short wavelength side of the PL spectrum was calculated as 2.66 eV. 30, the wavelength was 431 nm and the energy was 2.88 eV. .

[0337] FIG. 31 shows the peak energy (E em ) external quantum efficiency This is a graph showing the relationship between EQE and Blue Index (BI), with the horizontal axis being E e mwhere the vertical axis represents EQE and BI.

[0338] From the figure, both EQE and BI em E ave (2.66 eV in this example) and 2. 73 eV. Understood.

[0339] The value of 2.73 eV is E edge This corresponds to 0.95 times the value of 2.88 eV. It is the energy that

[0340] Thus, the blue light-emitting device with a microcavity structure has E ave E edge The cavity length is long enough to obtain a wavelength equivalent to an energy of 0.95 times or less. It was found that the light-emitting element can emit light with good efficiency. Chi, E ave ≦E em ≦0.95E edge (Range A in the figure) By controlling the EQE and BI, both can be maximized.

[0341] Also, especially considering BI, E ave +0.02 (eV) (2.67 eV in this example) ) or more E edge × 0.95 (eV) or less E em Since a light-emitting element having , E ave +0.02≦E em ≦0.95E edge (Range B in the figure) It has been found that it is preferable to control the tee length. [Example]

[0342] In this embodiment, the optical path length of a light emitting device having a microcavity structure is changed. The behavior of the external quantum efficiency and blue index (BI) when The structures of the organic compounds used in the light-emitting elements 7-1 to 7-8 fabricated in this example are as follows: As shown below.

[0343] [ka]

[0344] <Method for Fabricating Light-Emitting Elements 7-1 to 7-8> First, silver (Ag), palladium (Pd), and copper (Cu) were deposited on a glass substrate as a reflective electrode. The alloy film (Ag-Pd-Cu (APC) film) was deposited by sputtering to a thickness of 100 nm. After forming a thick film, indium tin oxide containing silicon oxide (ITSO) was sputtered as a transparent electrode. The first electrode 101 was formed by depositing a film with a thickness of 85 nm by a quartz crystal deposition method. The electrode area is 4mm 2 (2mm x 2mm).

[0345] Next, as a pretreatment for forming a light emitting element on the substrate, the substrate surface was washed with water and After baking at ℃ for 1 hour, UV ozone treatment was performed for 370 seconds.

[0346] Then, 10 -4 The substrate is placed in a vacuum deposition apparatus whose inside pressure has been reduced to about 100 Pa. After vacuum baking at 170°C for 30 minutes in the heating chamber of the device, the substrate is left for about 30 minutes. Allow to cool.

[0347] Next, the first electrode 101 is formed so that the surface on which the first electrode 101 is formed faces downward. The substrate was fixed to a substrate holder provided in a vacuum deposition apparatus, and the following was formed on the first electrode 101: 3-[4-(9-phenanthryl)-phenyl]- ]-9-phenyl-9H-carbazole (abbreviation: PCPPn) and molybdenum(VI) oxide and molybdenum oxide were co-deposited in a weight ratio of 1:0.5 (=PCPPn:molybdenum oxide) to form holes. An injection layer 111 was formed.

[0348] The optical path length of the light-emitting element can be changed by changing the film thickness of the hole injection layer 111. In the light-emitting element 7-1, the thickness of the hole injection layer 111 was 10 nm, and in the light-emitting element 7-2, 15 nm, 20 nm for light-emitting element 7-3, 25 nm for light-emitting element 7-4, and 7-5 30 nm for light-emitting element 7-6, 35 nm for light-emitting element 7-7, 40 nm for light-emitting element 7 In -8, it was fabricated at 45nm.

[0349] On the hole injection layer 111, PCPPn was evaporated to a thickness of 15 nm to form a hole transport layer 112.

[0350] Next, 7-[4-(10-phenyl-9-anthryl) phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA) and the above 3,10-bis[N-(dibenzofuran-3-yl)-N- phenylamino]naphtho[2,3-b;6,7-b']bisbenzofuran (abbreviation: 3,1 0FrA2Nbf(IV)-02) in a weight ratio of 1:0.01 (=cgDBCzPA: 3,10FrAlNbf(IV)-02) was co-deposited to form a 25 nm light-emitting layer 113 was formed.

[0351] Thereafter, cgDBCzPA was evaporated onto the light-emitting layer 113 to a thickness of 5 nm, and the above structure 2,9-bis(naphthalen-2-yl)-4,7-diphenyl- represented by formula (iv) 1,10-phenanthroline (abbreviation: NBPhen) was evaporated to a film thickness of 15 nm. Then, an electron transport layer 114 was formed.

[0352] After forming the electron transport layer 114, lithium fluoride (LiF) was evaporated to a thickness of 1 nm. The electron injection layer 115 is formed by depositing silver (Ag) and magnesium (Mg) at a volume ratio of 1: The second electrode 102 was formed by vapor deposition of 0.1 (=Ag:Mg) to a film thickness of 10 nm. The second electrode 102 was formed to form light-emitting elements 7-1 to 7-8. The semi-transmissive and semi-reflective electrode has both a reflecting function and a light transmitting function. The element is a top-emission element that extracts light from the second electrode 102. On the electrode 102, 1,3,5-tri(dibenzothiophene) represented by the above structural formula (v) -4-yl)-benzene (abbreviation: DBT3P-II) was evaporated to 70 nm, and the extraction efficiency was It is improving.

[0353] The device structures of the light-emitting devices 7-1 to 7-8 are summarized in Tables 19 and 20 below. Table 20 shows the film thickness of the hole injection layer in each light-emitting device.

[0354] [Table 19]

[0355] [Table 20]

[0356] The fabricated light-emitting device was placed in a glove box with a nitrogen atmosphere, and the light-emitting device was exposed to the atmosphere. The process of sealing with a glass substrate to prevent leakage (sealing material is applied around the element, and After UV treatment and heat treatment at 80°C for 1 hour, measurements were taken. It was.

[0357] The measurement results for the light-emitting elements 7-1 to 7-8 are shown below. All of the measurement results show that the luminance is 1 000cd / m 2 The external quantum efficiency is calculated by dividing the front luminance by the Lambertian ray. The uncorrected external quantum efficiency is calculated assuming a uniform light distribution.

[0358] [Table 21]

[0359] In addition, in a toluene solution of the luminescent center substance 3,10FrA2Nbf(IV)-02, The PL spectrum is shown in Figure 32. The PL spectrum was measured using absolute PL quantum yield measurement. Using a device (Quantaurus-QY manufactured by Hamamatsu Photonics Co., Ltd.), the P The L spectrum has an energy φ on the vertical axis. p (λ) is the normalized spectrum I(λ) proportional to Therefore, in this example, the average photon energy of the emitted light E ave When asking for Formula (VII) shown in embodiment 1 was used. The average energy (E ave )teeth The calculated value was 2.71 eV. The emission edge on the short wavelength side of the PL spectrum is shown in Figure 1. 33, the wavelength was 426 nm and the energy was 2.91 eV. .

[0360] FIG. 34 shows the peak energy (E em ) external quantum efficiency This is a graph showing the relationship between EQE and Blue Index (BI), with the horizontal axis being E e m where the vertical axis represents EQE and BI.

[0361] From the figure, both EQE and BI em E ave (2.71 eV in this example) and 2. 76 eV. Understood.

[0362] The value of 2.76 eV is E edge This corresponds to 0.95 times the value of 2.91 eV. It is the energy that

[0363] Thus, the blue light-emitting device with a microcavity structure has E ave E edge The cavity length is long enough to obtain a wavelength equivalent to an energy of 0.95 times or less. It was found that the light-emitting element can emit light with good efficiency. Chi, E ave ≦E em ≦0.95E edge (Range A in the figure) By controlling the EQE and BI, both can be maximized.

[0364] Also, especially considering BI, E ave +0.02 (eV) (2.73 eV in this example) ) or more E edge × 0.95 (eV) or less E em Since a light-emitting element having , E ave +0.02≦E em ≦0.95Eedge (Range B in the figure) It has been found that it is preferable to control the tee length. [Explanation of symbols]

[0365] 101: first electrode, 101-1: reflective electrode, 101-2: transparent electrode, 102: second electrode electrode, 103: EL layer, 104: organic cap layer, 111: hole injection layer, 112: hole transport layer layer, 113: light-emitting layer, 114: electron transport layer, 115: electron injection layer, 116: charge generation layer, 117: P-type layer, 118: electron relay layer, 119: electron injection buffer layer, 400: substrate, 401: first electrode, 403: EL layer, 404: second electrode, 405: sealing material, 406 : sealing material, 407: sealing substrate, 412: pad, 420: IC chip, 601: driving circuit 602: Pixel section; 603: Driver circuit section (gate line driver circuit) 604: sealing substrate, 605: sealing material, 607: space, 608: wiring, 609: FPC (flexible printed circuit), 610: element substrate, 611: switching FE T, 612: current control FET, 613: first electrode, 614: insulator, 616: EL layer , 617: second electrode, 618: light emitting element, 2001: housing, 2002: light source, 2100 : Robot, 2110: Computing device, 2101: Illuminance sensor, 2102: Microphone, 2103: Upper camera, 2104: Speaker, 2105: Display, 2106: Lower Camera, 2107: Obstacle sensor, 2108: Moving mechanism, 3001: Lighting device, 5000 : Housing, 5001: Display unit, 5002: Second display unit, 5003: Speaker, 5004: LED lamp, 5005: Operation key, 5006: Connection terminal, 5007: Sensor, 5008 : Microphone, 5012: Support part, 5013: Earphone, 5100: Cleaning robot, 5101: Display, 5102: Camera, 5103: Brush, 5104: Operation button , 5150: mobile information terminal, 5151: housing, 5152: display area, 5153: bending portion, 5120: Garbage, 5200: Display area, 5201: Display area, 5202: Display area, 52 03: Display area, 7101: Housing, 7103: Display unit, 7105: Stand, 7107: Display unit, 7109: Operation keys, 7110: Remote control unit, 7201: Main unit, 7202: Housing, 7203: Display unit, 7204: Keyboard, 7205: External connection port, 7206 : pointing device, 7210: second display unit, 7401: housing, 7402: display part, 7403: operation button, 7404: external connection port, 7405: speaker, 7406 : microphone, 7400: mobile phone, 9310: mobile information terminal, 9311: display panel, 9 312: Display area, 9313: Hinge, 9315: Housing

Claims

1. a first electrode; a second electrode; and an EL layer sandwiched between the first electrode and the second electrode; In a light-emitting device having a microcavity structure, one of the first electrode and the second electrode is a reflective electrode and the other is a semi-transparent / semi-reflective electrode, The EL layer has a luminescent center substance, The average energy of the PL spectrum of the luminescent center substance in a solution state is defined as E ａｖｅ [eV], and the emission edge energy on the short wavelength side of the PL spectrum of the luminescent center substance in the solution state is E ｅｄｇｅ [eV], the peak energy E of the light emitted from the light-emitting element ｅｍ [eV] is expressed by the following formula (1), E ｅｍ [eV] is E ａｖｅ [eV] and 2.73 eV. [Equation 1] E ａｖｅ ≦E ｅｍ ≦0.95E ｅｄｇｅ ・・・ (1)

2. In claim 1, The light-emitting device, wherein the optical distance between the reflective electrode and the light-emitting layer is (2n-1)λ / 4 (n is a natural number of 1 or more, and λ is the wavelength of the emitted light to be amplified).

3. 3. The light-emitting element according to claim 1, wherein the luminescent center substance emits blue light.

4. a first electrode; a second electrode; and an EL layer sandwiched between the first electrode and the second electrode; In a light-emitting device having a microcavity structure, one of the first electrode and the second electrode is a reflective electrode and the other is a semi-transparent / semi-reflective electrode, the EL layer has a luminescent center substance that emits blue light, The average energy of the PL spectrum of the luminescent center substance in a solution state is defined as E ａｖｅ [eV], and the emission edge energy on the short wavelength side of the PL spectrum of the luminescent center substance in the solution state is E ｅｄｇｅ [eV], the peak energy E of the light emitted from the light-emitting element ｅｍ [eV] is expressed by the following formula (2), and E ｅｍ [eV] is E ａｖｅ [eV] and 2.73 eV. [Equation 2] E ａｖｅ +0.02≦E ｅｍ ≦0.95E ｅｄｇｅ ・・・ (2)

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