Light-emitting element, illuminating device, light-emitting device, display device, and electronic apparatus

Abstract

To provide a light-emitting element with high lighting efficiency in a light-emitting element using a plurality of light-emitting dopants, and provide a light-emitting device in which a power consumption is reduced by using the above light-emitting element, a light-emitting module, a light-emitting display device, an electronic apparatus, and an illuminating device.SOLUTION: In a light-emitting element, by focusing on a Foerster mechanism which is one of an intermolecular energy transfer mechanism, and overlapping an emission wavelength of a molecule on the side of providing energy with a peak having a local maximum on the longest wavelength side in a graph obtained by multiplying an absorption spectrum of a molecule on the side of receiving energy by a wavelength to the fourth power, energy transfer in the Foerster mechanism can be made efficient.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a light-emitting element, a display device, a light-emitting device, and an electronic device using an organic compound as a light-emitting substance. and lighting devices. [Background technology]

[0002] In recent years, electroluminescence (EL) Research and development of light-emitting devices using this material is currently underway. The basic structure of these light-emitting devices is as follows: A layer containing a light-emitting material is sandwiched between a pair of electrodes. Thus, light emission from the light-emitting substance can be obtained.

[0003] Since these light-emitting elements are self-luminous, the pixels have higher visibility than LCD displays. This has the advantage that it does not require a backlight, and is therefore favored as a flat panel display element. In addition, displays using such light-emitting elements are thin and lightweight. Another major advantage is that it can be produced in large quantities. Another feature is its extremely fast response time. It is.

[0004] These light emitting devices can form the light emitting layer in a film shape, so that light can be emitted in a planar manner. Therefore, a large-area element can be easily formed. This is a feature that is difficult to obtain with point light sources such as bulbs and LEDs, or linear light sources such as fluorescent lights. Therefore, it is highly useful as a surface light source for lighting and other applications.

[0005] An organic electroluminescence (EL) device that uses an organic compound as the light-emitting material and has a layer containing the organic compound between a pair of electrodes In the case of the element, by applying a voltage between a pair of electrodes, electrons are ejected from the cathode and holes are ejected from the anode. (holes) are injected into the layers containing the light-emitting organic compounds, causing a current to flow. The recombination of the injected electrons and holes excites the light-emitting organic compound, Light can be emitted from the excited light-emitting organic compound.

[0006] There are two types of excited states that organic compounds can form: singlet excited states and triplet excited states. , singlet excited state (S * ) is emitted from the triplet excited state (T * ) is phosphorus The statistical generation rate of the light in the light-emitting element is S * :T * = It is believed to be 1:3.

[0007] Compounds that emit light from a singlet excited state (hereafter referred to as fluorescent compounds) emit light at room temperature. Normally, luminescence from the triplet excited state (phosphorescence) is not observed, but luminescence from the singlet excited state (fluorescence) is observed. Therefore, the internal quantum efficiency in the light-emitting device using the fluorescent compound is The theoretical limit of the photon generation rate (the ratio of photons generated to the number of injected carriers) is S * :T * = It is said to be 25% based on the ratio of 1:3.

[0008] On the other hand, if a compound that emits light from a triplet excited state (hereinafter referred to as a phosphorescent compound) is used, Emission from the triplet excited state (phosphorescence) is observed. Phosphorescent compounds also exhibit intersystem crossing ( Since the transition from the singlet excited state to the triplet excited state occurs easily, the internal quantum efficiency is 1 In other words, it is possible to achieve a higher luminous efficiency than fluorescent compounds. For this reason, in order to realize a highly efficient light-emitting device, Light-emitting devices have been actively developed in recent years.

[0009] In Patent Document 1, a light-emitting region containing a plurality of light-emitting dopants is provided, A phosphorescent white light emitting device is disclosed. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Special Publication No. 2004-522276 Summary of the Invention [Problem to be solved by the invention]

[0011] Although a phosphorescent compound theoretically has an internal quantum efficiency of 100%, this is difficult to achieve due to the structure of the device and other materials. It is difficult to achieve high efficiency without optimizing the combination of materials. In a light-emitting device that uses multiple types of phosphorescent compounds of different luminescent colors as luminescent dopants, In addition to considering the energy transfer, the efficiency of the energy transfer itself must be maximized. It is difficult to obtain a highly efficient emission without optimization. Even if the dopants are all phosphorescent, the external quantum efficiency is about 3 to 4%. Even if the light extraction efficiency is taken into account, the internal quantum efficiency is thought to be 20% or less. It must be said that this is a low value for a phosphorescent light-emitting device.

[0012] In addition to improving the luminous efficiency, it is also possible to develop multicolor light-emitting devices using dopants with different luminescent colors ( For example, in a white light-emitting device that combines blue, green, and red, the dopants for each color of light are It is necessary to achieve high luminous efficiency while maintaining the luminous efficiency of each dopant. Maintaining light balance is no easy task.

[0013] In view of this, in one embodiment of the present invention, a light-emitting element using a plurality of light-emitting dopants is Another object of the present invention is to provide a light-emitting element having a high light-emitting efficiency. Light-emitting device, display device, electronic device, and lighting device with reduced power consumption by using the device The present invention aims to provide a device for

[0014] It is sufficient for the present invention to solve any one of the above problems. [Means for solving the problem]

[0015] In the present invention, we focus on the Förster mechanism, which is one of the mechanisms of energy transfer between molecules, and The peak of the emission spectrum of the molecule that gives the energy and the absorption spectrum of the molecule that receives the energy The peak with the longest wavelength on the characteristic curve obtained by multiplying the spectrum by the fourth power of the wavelength By applying a combination of molecules such that overlap, the above-mentioned Förster mechanism In this case, the energy transfer is generally Energy transfer between dopants rather than from the host to the dopant. This is one of the features of the device. The dopants are combined in a way that maximizes the molecular weight of the dopant. By designing an element structure in which the light-emitting element is spaced apart, a light-emitting element according to one embodiment of the present invention can be obtained.

[0016] That is, one embodiment of the present invention is a first phosphorescent compound that emits blue light and is disposed between a pair of electrodes. a first light-emitting layer having a first host material and a second light-emitting layer having a first host material and a second light-emitting layer having a first host material and a second light-emitting layer having a second host material and a second light-emitting layer having a ε(λ)λ4 The function represented by the formula (1) has a maximum value A located on the longest wavelength side, and the first A second phosphorescent compound having a longer wavelength emission than the phosphorescent compound is disposed in the second host material. and a second emissive layer having a wavelength of ε(λ) in the range of 520 nm to 600 nm. 4 Represented by a maximum value B located on the longest wavelength side of the function, and A third phosphorescent compound exhibiting a long wavelength emission is dispersed in a third host material. a light emitting layer, in which the first to third light emitting layers are laminated in this order. (where ε(λ) represents the molar absorption coefficient of each phosphorescent compound and is a function of wavelength λ.) .

[0017] Another embodiment of the present invention is a light-emitting device comprising: a first phosphorescent compound that emits blue light; a first light-emitting layer dispersed in a first host material; and (λ)λ 4 The function has a maximum value A located on the longest wavelength side and is no longer than 520 nm. A second phosphorescent compound having a phosphorescent emission peak wavelength in the range of 100 to 600 nm is A second light-emitting layer dispersed in a host material and having an ε(λ)λ in the range of 520 nm to 600 nm. 4 and the second phosphorescence function has a maximum value B located on the longest wavelength side of the function represented by A third phosphorescent compound having a longer wavelength emission than the first compound is dispersed in the third host material. and a third light-emitting layer, the first light-emitting layer, the second light-emitting layer, and the third light-emitting layer are laminated in this order. (where ε(λ) is the molar absorption coefficient of each phosphorescent compound and is a function of wavelength λ. ).

[0018] Another embodiment of the present invention is a light-emitting element having the above structure, and the maximum value B is larger than the maximum value D.

[0019] Another embodiment of the present invention is a light-emitting element having the above structure, the second light-emitting layer and the third light-emitting layer are hole-transporting light-emitting elements; He is a child.

[0020] Another aspect of the present invention is a light-emitting element having the above structure, The first host material has an electron transporting property, and the second host material and the third host material have a hole transporting property. It is a light emitting element.

[0021] Another embodiment of the present invention is a light-emitting element having the above structure, a light-emitting element having a hole transporting property, and the second light-emitting layer and the third light-emitting layer having an electron transporting property. He is a child.

[0022] Another aspect of the present invention is a light-emitting element having the above structure, The first host material has hole transport properties, and the second host material and the third host material have electron transport properties. It is a light emitting element.

[0023] Another embodiment of the present invention is a light-emitting element having the above structure, The light-emitting layers are laminated in this order in contact with each other to form a light-emitting element.

[0024] Another embodiment of the present invention is a light-emitting element having the above structure, The thickness is 5 nm to 20 nm, preferably 5 nm to 10 nm. This is a light-emitting element.

[0025] Another embodiment of the present invention is a light-emitting device or a light-emitting display device including a light-emitting element having the above structure. equipment, electronic devices and lighting devices.

[0026] In this specification, the term "light-emitting device" includes an image display device using a light-emitting element. In addition, the light emitting element is connected to a connector, such as anisotropic conductive film or TCP (Tape Cable). A module with a printed wiring board (Package A) attached, and a TCP Module with wiring board or COG (Chip On Glass) type for light emitting element According to the formula, all modules on which ICs (integrated circuits) are directly mounted are also included in the light-emitting device. Furthermore, it also includes light-emitting devices used in lighting fixtures and the like. Effect of the Invention

[0027] One embodiment of the present invention can provide a light-emitting element with high emission efficiency. A light-emitting device, a light-emitting display device, an electronic device, and an A lighting device can be provided. [Brief description of the drawings]

[0028] [Figure 1] 1 is a conceptual diagram of a light-emitting element. [Diagram 2] Diagram showing energy transfer in the light-emitting layer [Diagram 3] Diagram explaining Förster transfer from blue phosphorescence. [Figure 4] Diagram explaining Förster transfer from blue phosphorescence. [Diagram 5] Diagram explaining Förster transfer from blue phosphorescence. [Figure 6] FIG. 1 is a conceptual diagram of an active matrix light-emitting device. [Figure 7] FIG. 1 is a conceptual diagram of a passive matrix light-emitting device. [Figure 8] FIG. 1 is a conceptual diagram of an active matrix light-emitting device. [Figure 9] FIG. 1 is a conceptual diagram of an active matrix light-emitting device. [Figure 10] A conceptual diagram of a lighting device. [Figure 11] A diagram showing an electronic device. [Figure 12] A diagram showing an electronic device. [Figure 13] FIG. [Figure 14] 1A and 1B are diagrams illustrating a lighting device and a display device. [Figure 15] 1 is a diagram illustrating an in-vehicle display device and a lighting device. [Figure 16] A diagram showing an electronic device. [Figure 17] FIG. 13 shows current density-luminance characteristics of Light-emitting Element 1 and Light-emitting Element 2. [Figure 18] FIG. 13 shows luminance-current efficiency characteristics of Light-emitting Element 1 and Light-emitting Element 2. [Figure 19] FIG. 13 shows voltage-luminance characteristics of Light-emitting Element 1 and Light-emitting Element 2. [Figure 20] FIG. 13 shows luminance-chromaticity characteristics of the light-emitting element 1 and the light-emitting element 2. [Figure 21] FIG. 13 shows luminance-power efficiency characteristics of the light-emitting element 1 and the light-emitting element 2. [Figure 22] FIG. 13 shows luminance vs. external quantum efficiency characteristics of Light-emitting Elements 1 and 2. [Diagram 23] FIG. 2 shows emission spectra of Light-emitting Elements 1 and 2. [Figure 24] Diagram explaining Förster transfer from blue phosphorescence. [Diagram 25] FIG. 13 shows current density-luminance characteristics of the light-emitting element 3. [Figure 26] FIG. 13 shows luminance vs. current efficiency characteristics of the light-emitting element 3. [Figure 27] FIG. 13 shows voltage-luminance characteristics of the light-emitting element 3. [Figure 28] FIG. 13 shows luminance-chromaticity characteristics of the light-emitting element 3. [Figure 29] FIG. 13 shows luminance vs. power efficiency characteristics of the light-emitting element 3. [Diagram 30] FIG. 13 shows luminance vs. external quantum efficiency characteristics of the light-emitting element 3. [Diagram 31] FIG. 2 shows an emission spectrum of the light-emitting element 3. [Diagram 32] FIG. 13 shows current density-luminance characteristics of the light-emitting element 4. [Diagram 33] FIG. 13 shows luminance vs. current efficiency characteristics of the light-emitting element 4. [Diagram 34] FIG. 13 shows voltage-luminance characteristics of the light-emitting element 4. [Diagram 35] FIG. 13 shows luminance-chromaticity characteristics of the light-emitting element 4. [Diagram 36] FIG. 13 shows luminance vs. power efficiency characteristics of the light-emitting element 4. [Figure 37] FIG. 13 shows luminance vs. external quantum efficiency characteristics of the light-emitting element 4. [Figure 38] FIG. 13 shows an emission spectrum of the light-emitting element 4. [Figure 39] FIG. 13 is a graph showing time-normalized luminance characteristics of the light-emitting element 4. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] Hereinafter, the embodiment 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 are not limited thereto without departing from the spirit and scope of the present invention. It will be readily understood by those skilled in the art that various modifications may be made. It should not be construed as being limited to the description of the embodiment modes.

[0030] (Embodiment 1) First, the principle of operation of a light-emitting element according to one embodiment of the present invention will be described. A first phosphorescent compound that emits light (specifically, a compound that emits light with a peak wavelength of 440 nm to 520 nm) or a phosphorescent compound having a CIE chromaticity (x, y) of 0.12≦x≦0.25 and a phosphorescent compound having an emission color in a color range of 0.05≦y≦0.5; Secondary and tertiary phosphorescence, which emits light at longer wavelengths (e.g., green or red) than the phosphorescent compound. By using a phosphorescent compound and causing all of the first to third phosphorescent compounds to emit light efficiently, The aim is to obtain a highly efficient multi-color light emitting device.

[0031] A common method for obtaining a multicolor light-emitting device using a phosphorescent compound is to use some kind of host material. One possible method is to disperse multiple phosphorescent compounds with different luminescent colors in the material at appropriate ratios. However, in this method, the phosphorescent compound that emits the longest wavelength emits light. Therefore, the device structure for obtaining multicolor emission (especially the phosphorescence of each phosphorescent material in the host material) However, designing and controlling the concentration of active compounds is extremely difficult.

[0032] Another method for obtaining a multicolor light-emitting device is to stack light-emitting devices of different colors in series, a method known as For example, a tandem structure having a blue light-emitting element, a green light-emitting element, and a red light-emitting element may be used. By stacking these three in series and emitting light simultaneously, multicolor light (in this case, white light) can be easily obtained. The element structure can be optimized for each of the blue, green, and red elements. Control is relatively easy. However, since three elements are stacked, the number of layers increases and the operation In addition, problems may occur with electrical contact at the connection points (so-called intermediate layers) of each element. This may result in an increase in the driving voltage, i.e., a power loss.

[0033] On the other hand, the light-emitting element of one embodiment of the present invention has a first phosphorescent layer that emits blue light between a pair of electrodes. A first light-emitting layer having a compound dispersed in a first host material, and a first phosphorescent compound. A second phosphorescent compound having a longer wavelength emission is dispersed in a second host material. a light-emitting layer and a third phosphorescent compound that emits light at a longer wavelength than the second phosphorescent compound; and a third light-emitting layer dispersed in a third host material, the first to third light-emitting layers being In this case, the first to third light emitting layers are stacked in order. They may be provided in contact with each other.

[0034] FIG. 1 is a schematic diagram showing the element structure of the light-emitting element according to one embodiment of the present invention. A first electrode 101, a second electrode 102, and an EL layer 103 are shown. At least the light emitting layer 113 is provided, and other layers may be provided as appropriate. In FIG. 1C, a hole injection layer 111, a hole transport layer 112, an electron transport layer 114 and an electrode The figure shows a tentative configuration in which a electron injection layer 115 is provided. The first electrode 101 is an anode. The first electrode 101 functions as a cathode, and the second electrode 102 functions as a cathode.

[0035] 1(a) and 1(b) are enlarged views of a light-emitting layer 113 in the light-emitting device. 1(a) and (b) show a first light-emitting layer 113B, a second light-emitting layer 113G, a third light-emitting layer 113C, and a the light-emitting layer 113R, the light-emitting layer 113 formed by combining the three layers, the first phosphorescent compound 113Bd, A second phosphorescent compound 113Gd, a third phosphorescent compound 113Rd, and a first host material 113Bh, a second host material 113Gh, a third host material 113Rh, and a recombination region FIG. 1(a) shows a first light-emitting layer 113B provided on the cathode side. FIG. 1(b) is a schematic diagram showing a case where the first light-emitting layer 113B is provided on the anode side. In either case, each phosphorescent compound (first to third phosphorescent compounds) Since the phosphorescent compounds are dispersed in the host material, each phosphorescent compound is mutually insulated by each host material. The first to third host materials may be the same or different. stomach.

[0036] In this case, electron exchange interaction (the so-called Dexter mechanism) occurs between each phosphorescent compound. In other words, the first phosphorescent compound 113Bd is excited After the excitation energy is transferred to the second phosphorescent compound 113Gd via the Dexter mechanism, Alternatively, the phenomenon of migration to the third phosphorescent compound 113Rd can be prevented. After the phosphorescent compound 113Gd is excited, the excitation energy is transferred to the Dexter mechanism. It is also possible to prevent the phenomenon of the electron transfer to the third phosphorescent compound 113Rd. The third phosphorescent compound, 113Rd, which emits light at the longest wavelength, emits light predominantly. If excitons are generated directly in the third light-emitting layer 113R, The third phosphorescent compound, 113Rd, emits light mainly due to the recombination of carriers. The region 113ex is in the first light-emitting layer 113B or between the first light-emitting layer 113B and the second light-emitting layer 113B. The first phosphorescent compound 113Bd is mainly contained in the vicinity of the interface with the phosphorescent layer 113G. It is preferable to excite the electrons by excitation with a fluorine atom.

[0037] However, the energy transfer from the first phosphorescent compound 113Bd was completely suppressed. If the third phosphorescent compound 113Rd is used, the emission of the third phosphorescent compound 113Rd cannot be obtained. In one embodiment of the invention, the excitation energy of the first phosphorescent compound 113Bd that emits blue light is is partially transferred to the second phosphorescent compound 113Gd, and then The excitation energy of the compound 113Gd is partially transferred to a third phosphorescent compound 113Rd. The energy transfer between such isolated molecules is called dipole-bipolar. This is possible by utilizing the polar interaction (Förster mechanism).

[0038] Here, we will explain the Förster mechanism. The molecule that receives the excitation energy is called the energy donor, and the molecule that receives the excitation energy is called the energy acceptor. That is, in one embodiment of the present invention, an energy donor, an energy acceptor Both of these compounds are phosphorescent and are separated from each other by a host material.

[0039] The Förster mechanism does not require direct contact between molecules for energy transfer. Energy transfer through the resonance phenomenon of dipole vibration between donor and energy acceptor The dipole vibration resonance phenomenon causes the energy donor to become the energy acceptor. Energy is transferred, the excited state energy donor becomes the ground state, and the ground state energy The energy acceptor is excited. The rate of energy transfer by the Förster mechanism is number k F is shown in Equation (1).

[0040]

number

[0041] In formula (1), ν represents the vibration frequency, and F(ν) is the normalized energy donor The emission spectrum (or the fluorescence spectrum when discussing energy transfer from a singlet excited state) , and phosphorescence spectrum when discussing energy transfer from triplet excited states), and ε ( ν) represents the molar extinction coefficient of the energy acceptor, N represents Avogadro's number, and n represents the refractive index of the medium, and R is the intermolecular distance between the energy donor and the energy acceptor. represents the distance from the excited state, τ represents the lifetime of the excited state (fluorescence lifetime or phosphorescence lifetime) actually measured, and c represents the optical represents the light emission quantum yield (when considering energy transfer from a singlet excited state, When discussing energy transfer from a triplet excited state, the quantum yield is expressed as the light quantum yield. S,K 2 is the orientation of the transition dipole moments of the energy donor and energy acceptor In the case of random orientation, K 2 =2 / 3.

[0042] As can be seen from equation (1), the energy transfer by the Förster mechanism (Förster transfer) The conditions for this are: 1. The energy donor and the energy acceptor are not too far apart (distance R), 2. The energy donor emits light (related to the luminescence quantum yield φ), 3. The emission spectrum of the energy donor and the absorption spectrum of the energy acceptor overlap. (related to the integral term).

[0043] As described in FIG. 1, each phosphorescent compound (first to third phosphorescent compounds) is The phosphorescent compounds are dispersed in the respective host materials, and are isolated from one another by the respective host materials. Therefore, the distance R is at least one molecule (1 nm or more). Therefore, all of the excitation energy generated in the first phosphorescent compound is transported through the Förster mechanism. Therefore, there is no energy transfer to the second or third phosphorescent compound. If R is about 10 to 20 nm, Förster transfer is possible. For example, by setting the thickness of the second light-emitting layer 113G in FIG. 1 to 20 nm or less, partial energy Energy transfer occurs, and the first phosphorescent compound 113Bd and the second phosphorescent compound 113G d, all of the third phosphorescent compounds 113Rd can be made to emit light.

[0044] A first phosphorescent compound 113Bd that emits blue light and a second phosphorescent compound 113Bd that emits blue light a second phosphorescent compound 113Gd that emits light at a long wavelength (e.g., green light); The third phosphorus exhibiting longer wavelength emission (e.g. red emission) than that of the phosphorescent compound 113Gd In the light-emitting element of one embodiment of the present invention using the phosphorescent compound 113Rd, A schematic diagram of the Förster transfer in the ion exchange membrane is shown in FIG. 2. In FIG. 2, the Förster transfer in the ion exchange membrane is shown. A first light emitting layer 113B, a second light emitting layer 113G, and a third light emitting layer 113R are laminated on the first light emitting layer 113B. The structure is shown in FIG. 1. One of the electrodes 10 and 11 functions as an anode, and the other functions as an anode. The electrode functions as a cathode. As shown in FIG. The singlet excited state (S B ) can be converted to a triplet excited state (T B ) That is, the excitons in the first light-emitting layer 113B are basically T B It is summarized as follows.

[0045] Next, this T B A part of the energy of the exciton in the state is directly emitted and converted into blue light. However, by utilizing the Förster mechanism, some of the phosphorescence was observed in the second phosphorescent compound 113G. The triplet excited state of d (T G This can be transferred to the first phosphorescent compound 1 13Bd is luminescent (has a high phosphorescence quantum yield φ), and the second phosphorescent compound 11 3Gd has a direct absorption corresponding to the electronic transition from the singlet ground state to the triplet excited state. These conditions are due to the existence of an absorption spectrum in the triplet excited state. If satisfied, T B From T G Triplet-triplet Förster transfer to T B From the third phosphorescent compound 113Rd, the singlet excited state (S R ) energy transfer to Although the contribution is small, it can occur if the conditions for Förster transfer are met. This will be explained later. However, this is likely to occur when the third phosphorescent compound 113Rd is a red light-emitting material. R is intersystem By difference, the triplet excited state (T R ) , which contributes to the emission of the third phosphorescent compound 113Rd. The energy donor (here the first phosphorescent compound 113Bd) must be emissive. Therefore, the phosphorescence quantum yield of the first phosphorescent compound 113Bd is 0.1 or more. preferable.

[0046] The second phosphorescent compound 113Gd has a singlet excited state (S G ) is the first phosphorescent The triplet excited state (T B ) is often higher in energy than the above In many cases, they do not contribute much to the energy transfer, and therefore are omitted here.

[0047] Furthermore, the triplet T of the second phosphorescent compound 113Gd G The energy of the exciton in the state is Some of it is converted directly into light (e.g., green light), but by utilizing the Förster mechanism, As a result, some of the phosphorescence was observed in the triplet excited state (T R ) This is because the second phosphorescent compound 113Gd is luminescent (phosphorescence quantum yield The third phosphorescent compound 113Rd has a triplet excited state from the singlet ground state. The absorption spectrum of the triplet excited state corresponds to the electron transition to the If these conditions are met, T G From T R Triplet to triple The Förster mechanism allows the transfer of doublet states. Since the second phosphorescent compound (here, Gd) needs to be luminescent, the second The phosphorescent quantum yield of the phosphorescent compound 113Gd is preferably 0.1 or more.

[0048] The T generated by the energy transfer described above R The third phosphorescent compound 113 In this way, the first to third phosphorescent Luminescence can be obtained from each of the mixtures.

[0049] In addition, the above-mentioned Förster transfer can be efficiently generated between phosphorescent compounds serving as dopants. In order to design the first to third host materials so that the energy does not transfer to the host material, It is preferred that the material does not have an absorption spectrum in the blue region. It is preferable that the absorption edge of the spectrum is 440 nm or less. Energy is transferred directly between dopants without going through a second or third host material. By performing - transfer, the generation of unnecessary energy transfer paths is suppressed, resulting in high luminescence efficiency. can be linked to the rate.

[0050] In addition, the first host material is selected so as not to quench the first phosphorescent compound that emits blue light. It is preferable that the phosphorescent compound has a triplet excitation energy higher than that of the first phosphorescent compound. .

[0051] As described above, the basic concept of one embodiment of the present invention is to firstly provide first to third phosphorescent The first compound that exhibits the shortest wavelength emission while isolating the compound using a host material and a stacked structure The device structure is such that the phosphorescent compound is mainly excited. In the case of β-peptides, Förster-type energy transfer occurs within a certain distance (~20 nm). Since the excitation energy of the first phosphorescent compound that emits blue light is partially The excitation energy of the second phosphorescent compound is transferred to the second phosphorescent compound. The light is partially transferred to the third phosphorescent compound, and light is emitted from each of the first to third phosphorescent compounds. It is possible.

[0052] However, a more important point in one embodiment of the present invention is that the energy transfer is taken into consideration. The key points are the selection of materials and the device structure.

[0053] First, in order for the Förster transfer to occur, the luminescence quantum yield φ on the energy donor side must be In one embodiment of the present invention, a phosphorescent compound (specifically, a phosphorescent quantum This problem does not occur because the compound (a luminescent compound with a yield of 0.1 or more) is used. The important point is that the compound represented by the formula (1 ), i.e., the emission spectrum F(ν) of the energy donor and the energy The key is to ensure that the molar extinction coefficients ε(ν) of the energy acceptors overlap well.

[0054] In general, the energy acceptor is absorbed in the wavelength region where the molar absorption coefficient ε(ν) of the energy acceptor is large. We can simply superimpose the Giedner emission spectrum F(ν) (i.e., the product F(ν)ε(ν) However, this is not always the case in the Förster mechanism. This is not true because the integral term in equation (1) is inversely proportional to the fourth power of the frequency ν, This is because there is wavelength dependency.

[0055] To make it easier to understand, let us first transform equation (1). If the wavelength of light is λ, then ν=c / λ, equation (1) can be rewritten as equation (2) below.

[0056]

number

[0057] In other words, the integral term becomes larger as the wavelength λ increases. This means that energy transfer is more likely to occur. In other words, the molar extinction coefficient ε(λ) It is not as simple as F(λ) overlapping in the wavelength region where ε(λ)λ 4 but We must make F(λ) overlap over a large region.

[0058] Therefore, the second phosphorescent compound 113Gd in the light-emitting element of one embodiment of the present invention is The first phosphorescent compound 113Bd (specifically, 440 nm to 520 nm) exhibits blue light emission. In order to increase the efficiency of energy transfer from the phosphorescent compound having an emission peak at m, ε(λ)λ in the range of 440nm~520nm 4It is located on the longest wavelength side of the function expressed by It has a maximum value A and emits light at a longer wavelength than the first phosphorescent compound 113Bd. Phosphorescent compounds (specifically, phosphors having an emission peak in the range of 520 nm to 600 nm) As the third phosphorescent compound 113Rd, the second phosphorescent compound In order to increase the efficiency of energy transfer from the active compound 113Gd, in the range of ε(λ)λ 4 The function has a maximum value B located on the longest wavelength side, and The second phosphorescent compound 113 uses a phosphorescent compound that emits light at a longer wavelength than Gd. In addition, since the emission of each phosphorescent compound is as described above, it is suitable for lighting applications. If the material is used for display, it is possible to obtain light emission with high color rendering. Light emission can be obtained efficiently.

[0059] In order to better understand the structure of such phosphorescent compounds (especially the maximum values ​​A and B), A specific example will now be described. Here, the first phosphorescent compound 113B that emits blue light is As d, the following compound (1) (tris{2-[5-(2-methylphenyl)-4-(2, 6-Dimethylphenyl)-4H-1,2,4-triazol-3-yl-κN2]phenyl Iridium(III) (abbreviation: Ir(mptz-dmp)3) was added to the first A second phosphorescent compound that emits light at a longer wavelength (green emission) than the phosphorescent compound 113Bd. As 113Gd, the following compound (2) ((acetylacetonato)bis(6-tert-butyl) Iridium(III) (abbreviation: Ir(tBuppm) 2(acac))) which emits light at a longer wavelength (red emission) than the second phosphorescent compound 113Gd. As the third phosphorescent compound 113Rd, the following compound (3) (bis(2,3,5 -Triphenylpyrazinato)(dipivaloylmethanato)iridium(III)(abbreviation: I r(tppr)2(dpm)) will be used as an example.

[0060] [ka]

[0061] FIG. 3(a) shows the molar extinction coefficient ε(λ) of the second phosphorescent compound, compound (2), and the (λ)λ 4 The molar absorption coefficient ε(λ) decreases toward the longer wavelength side. It goes down, but ε(λ)λ 4 is near 490 nm (the triplet MLCT absorption band of compound (2)). As can be seen from this example, λ 4 Due to the influence of the term, the second ε(λ)λ of phosphorescent compounds 4 The absorption band located at the longest wavelength side (triplet MLCT absorption) The band has a maximum value A.

[0062] On the other hand, Figure 3(b) shows the photoluminescence (PL) spectrum F(λ) of compound (1). and ε(λ)λ of compound (2) 4 Compound (1) is a first phosphorescent It is a compound that emits blue light with emission peaks at around 475 nm and 505 nm. The PL spectrum F(λ) of the first phosphorescent compound is expressed by the ε( λ)λ 4 Near the maximum value A of ε(λ)λ 4 There is a large overlap with the first Energy transfer occurs from one phosphorescent compound to a second phosphorescent compound via the Förster mechanism. In this case, the maximum value A corresponds to the triplet MLCT absorption band, so This is a Förster type energy transfer of the doublet (T in Figure 2). B -T G Energy Transfer) .

[0063] Next, FIG. 4(a) shows the molar extinction coefficient ε(λ) of the third phosphorescent compound, compound (3). and ε(λ)λ 4 The molar absorption coefficient ε(λ) increases toward the longer wavelength side. It decreases as ε(λ)λ 4 The triplet MLCT absorption of compound (3) is observed around 550 nm. As can be seen from this example, λ 4 Due to the influence of the term ε(λ)λ of the third phosphorescent compound 4 is the absorption band located at the longest wavelength side (triplet ML It has a maximum value B in the CT absorption band.

[0064] On the other hand, Figure 4(b) shows the photoluminescence (PL) spectrum F(λ) of compound (2). and ε(λ)λ of compound (3) 4 Compound (2) is a second phosphorescent It is a compound that emits green light with a peak at about 545 nm. The PL spectrum F(λ) of the phosphorescent compound is expressed as ε(λ)λ of the third phosphorescent compound. 4 Maximum of In the vicinity of B, ε(λ)λ 4 and has a large overlap, and the second phosphorescent compound Energy transfer occurs to the third phosphorescent compound via the Förster mechanism. In this case, the maximum B corresponds to the triplet MLCT absorption band, so the triplet-triplet Förster This is a type of energy transfer (T in Figure 2). G -T Renergy transfer).

[0065] From the above, the second and third phosphorescent compounds have the longest wavelengths in the absorption spectrum. On the long side, there is direct absorption (e.g., It is preferable that the LC-TTL has triplet MLCT absorption. As a result, triplet-triplet energy transfer as shown in

[0066] Here, Fig. 3(b) and Fig. 4(b) are combined on the same diagram, and a third phosphorescent compound is The PL spectrum of compound (3) is also shown in Figure 5. PL spectrum and ε(λ)λ of compound (2) 4 Using the overlap with (near the maximum value A) From compound (1) to compound (2), and then the PL spectrum of compound (2) and that of compound (3) ε(λ)λ 4 Using the overlap with (near maximum B), compound (2) is moved to compound (3). It can be seen that energy transfer is possible stepwise. Direct energy transfer from compound (1) to a third phosphorescent compound, compound (3). As can be seen from Figure 5, the triplet MLCT absorption band (polar The PL spectrum F(λ) of compound (1) and compound (3) are shorter than the maximum value B. ε(λ) 4 This is due to the overlap of the triplet-singlet Förster type energy This suggests that there is a shift in the B -S R energy transfer).

[0067] The important thing to note from Figures 3, 4, and 5 above is that λ 4 The second phosphorescent compound The third phosphorescent compound is more likely to accept energy than the first phosphorescent compound (energy acceptor). The second phosphorescent compound and the third phosphorescent compound are both The molar extinction coefficient ε(λ) of the triplet MLCT absorption band on the long wavelength side is 5000 [M -1 cm -1 ], which is almost the same. Nevertheless, as can be seen from Figure 5, 4 Comparing maximum value A and maximum value B, maximum value B is about 1.6 times larger. This is λ 4 This is the effect of the term ε(λ )λ 4 Therefore, compared to the second phosphorescent compound, This indicates that the third phosphorescent compound is more likely to accept energy.

[0068] Therefore, the first to third light emitting layers are laminated in this order, and the carrier recombination region is formed as the first The first light-emitting layer is located in the first light-emitting layer, or in the vicinity of the interface between the first light-emitting layer and the second light-emitting layer (i.e., the first We focused on the device structure (as shown in Figure 1) which mainly excites phosphorescent compounds. By adopting such a device structure, the second light-emitting layer containing the second phosphorescent compound However, the third light-emitting layer containing the third phosphorescent compound is farther from the carrier recombination region. In this way, the third phosphorescent compound, which is more likely to receive energy, is removed from the recombination region. A second phosphorescent compound that is farther away and less likely to receive energy is placed near the recombination region. By arranging the first to third phosphorescent compounds in the same manner, the light emitted from the first to third phosphorescent compounds can be well balanced. As a result, good luminous efficiency and a well-balanced spectrum can be obtained. Therefore, a light emitting element with a good light emitting property can be obtained.

[0069] In order to obtain the above-mentioned recombination region, the first light-emitting layer is electron-transporting, and the second light-emitting layer is The light-emitting layer and the third light-emitting layer preferably have a hole-transporting property (FIG. 1(a)). Specifically, for example, a material having an electron transporting property is used as the first host material, and a material having an electron transporting property is used as the second host material. As the third host material, a material having a hole transporting property may be used.

[0070] In another embodiment of the present invention, the first light-emitting layer has a hole-transporting property, The second light-emitting layer and the third light-emitting layer preferably have an electron transporting property (FIG. 1(b) Specifically, for example, a material having a hole transporting property is used as the first host material, and As the second host material and the third host material, an electron transporting material may be used.

[0071] Furthermore, in order to obtain light emission from the second light-emitting layer and also from the third light-emitting layer, Considering the distance R of the Förster transfer, the thickness of the second light-emitting layer is 5 nm to 20 nm. It is more preferable that the thickness is 5 nm or more and 10 nm or less.

[0072] (Embodiment 2) In this embodiment mode, a detailed structure example of the light-emitting element described in Embodiment Mode 1 will be described with reference to FIG. The details are explained below.

[0073] The light emitting element in this embodiment has an EL layer made up of a plurality of layers between a pair of electrodes. In this embodiment, the light-emitting element includes a first electrode 101, a second electrode 102, and a first It is composed of an electrode 101, a second electrode 102 and an EL layer 103 provided between them. In this embodiment, the first electrode 101 functions as an anode, and the second electrode 102 functions as a cathode. In the following description, the first electrode 101 functions as a second electrode 10. A voltage was applied between the first electrode 101 and the second electrode 102 so that the potential was higher than that of the first electrode 101. In some cases, light emission is obtained.

[0074] Since the first electrode 101 functions as an anode, it is required to use a material having a large work function (specifically, 4.0 e V or higher) metals, alloys, conductive compounds, and mixtures thereof. Specifically, for example, indium oxide-tin oxide (ITO) is in Oxide), indium oxide-tin oxide containing silicon or silicon oxide, Indium oxide - zinc oxide, tungsten oxide and indium oxide containing zinc oxide ( These conductive metal oxide films are usually formed by sputtering. The film is formed by the sol-gel method, but it may be formed by applying the sol-gel method. Indium oxide-zinc oxide is made by adding 1 to 20 wt% zinc oxide to indium oxide. There is also a method of forming the film by sputtering using a target containing oxide. Indium oxide containing tin and zinc oxide (IWZO) has the following properties compared to indium oxide: The target contains 0.5-5 wt% tungsten oxide and 0.1-1 wt% zinc oxide. It can also be formed by sputtering using gold (Au), platinum ( Pt), Nickel (Ni), Tungsten (W), Chromium (Cr), Molybdenum (Mo) , iron (Fe), cobalt (Co), copper (Cu), palladium (Pd), or metallic materials Nitrides (for example, titanium nitride) and the like can be used. Graphene can also be used. By using a composite material described later for the layer in contact with the first electrode 101 in the EL layer 103, This makes it possible to select electrode materials regardless of their work functions.

[0075] Regarding the laminated structure of the EL layer 103, the light-emitting layer 113 has the same structure as that shown in the first embodiment. As long as the above is satisfied, the other layers are not particularly limited. For example, a hole injection layer, a hole transport layer, a light emitting layer, an electron The layer can be constructed by appropriately combining a transport layer, an electron injection layer, a carrier block layer, an intermediate layer, etc. In this embodiment, the EL layer 103 is a hole transport layer formed in sequence on the first electrode 101. Injection layer 111, hole transport layer 112, light emitting layer 113, electron transport layer 114, electron injection layer 115 The materials constituting each layer are specifically described below.

[0076] The hole injection layer 111 is a layer containing a substance with high hole injection properties. Use of tungsten oxide, manganese oxide, etc. In addition, phthalocyanine (abbreviation: H2Pc) and copper phthalocyanine (CuPC) can be used. Phthalocyanine compounds such as 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 phenyl-4,4'-diamine (abbreviation: DNTPD) or poly Poly(ethylenedioxythiophene) / Poly(styrenesulfonic acid) (PEDOT / PSS The hole injection layer 111 can also be formed from a polymer such as .

[0077] In addition, the hole-injecting layer 111 may be formed by adding an acceptor substance to a hole-transporting substance. A composite material can be used. Note that a hole transporting material may contain an acceptor material. By using a material that has been developed, it is possible to select a material for forming the electrode regardless of the work function of the electrode. In other words, the first electrode 101 can be made of not only a material with a large work function but also a material with a low work function. Small materials can also be used. Acceptor materials include 7,7,8 ,8-Tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation: F4-TC NQ), chloranil, etc. Also included are transition metal oxides. Further, oxides of metals belonging to groups 4 to 8 of the periodic table can be mentioned. Specifically, vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide, Dendrimer, tungsten oxide, manganese oxide, and rhenium oxide are preferred due to their high electron-accepting properties. In particular, molybdenum oxide is stable in the air, has low hygroscopicity, and is easy to handle. preferable.

[0078] The hole transporting substances used in the composite materials include aromatic amine compounds and carbazole derivatives. Various types of compounds, such as aromatic hydrocarbons, polymers (oligomers, dendrimers, polymers, etc.) Various organic compounds can be used. It is preferable that the organic compound has a high hole transporting property. -6 cm 2 / Vs or later In the following, the hole transport in the composite material is preferably a material having a hole mobility of 100 nm or higher. Specific examples of organic compounds that can be used as the transport material are listed below.

[0079] For example, the aromatic amine compound is N,N'-di(p-tolyl)-N,N'-diphenyl Phenyl-p-phenylenediamine (DTDPPA), 4,4'-bis[N-(4- Diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation: DPAB), N ,N'-Bis{4-[bis(3-methylphenyl)amino]phenyl}-N,N'-diphenyl 1,3-Diphenyl-(1,1'-biphenyl)-4,4'-diamine (abbreviation: DNTPD) ,5-Tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene (abbreviation: DPA3B) and the like.

[0080] Specific examples of carbazole derivatives that can be used in composite materials include 3-[N- (9-Phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazol 3,6-bis[N-(9-phenylcarbazole-3 -yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA2) , 3-[N-(1-naphthyl)-N-(9-phenylcarbazol-3-yl)amino] -9-phenylcarbazole (abbreviation: PCzPCN1), etc.

[0081] Other carbazole derivatives that can be used in composite materials include 4,4'- Di(N-carbazolyl)biphenyl (abbreviation: CBP), 1,3,5-tris[4-(N- Carbazolyl)phenyl]benzene (abbreviation: TCPB), 9-[4-(10-phenyl- 9-Anthryl)phenyl]-9H-carbazole (abbreviation: CzPA), 1,4-bis[ 4-(N-carbazolyl)phenyl]-2,3,5,6-tetraphenylbenzene, etc. There can be.

[0082] In addition, examples of aromatic hydrocarbons that can be used in the composite material include 2-tert -Butyl-9,10-di(2-naphthyl)anthracene (abbreviation: 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), 9,1 0-Di(2-naphthyl)anthracene (abbreviation: DNA), 9,10-diphenylanthracene 2-tert-butylanthracene (abbreviation: DPAnth), 2-tert-butylanthracene (abbreviation: t-BuAn th), 9,10-bis(4-methyl-1-naphthyl)anthracene (abbreviation: DMNA) , 2-tert-butyl-9,10-bis[2-(1-naphthyl)phenyl]anthracene 9,10-bis[2-(1-naphthyl)phenyl]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, 10,1 0'-Diphenyl-9,9'-bianthryl, 10,10'-bis(2-phenylphenyl) 10,10'-bis[(2,3,4,5,6-pentafluorophenyl) phenyl)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. -6 cm 2 / Vs or more and uses aromatic hydrocarbons with carbon numbers of 14 to 42. It is more preferable that

[0083] The aromatic hydrocarbon that can be used in the composite material may have a vinyl skeleton. Examples of aromatic hydrocarbons having a vinyl group include 4,4'-bis(2,2- Diphenylvinyl)biphenyl (abbreviation: DPVBi), 9,10-bis[4-(2,2- diphenylvinyl)phenyl]anthracene (abbreviation: DPVPA), and the like.

[0084] In addition, poly(N-vinylcarbazole) (abbreviation: PVK) and poly(4-vinyltriphenylphosphine) nylamine) (abbreviation: PVTPA), poly[N-(4-{N'-[4-(4-diphenyl Amino)phenyl]phenyl-N'-phenylamino}phenyl)methacrylamide]( abbreviation: PTPDMA), poly[N,N'-bis(4-butylphenyl)-N,N'-bis Polymer compounds such as Poly(phenyl)benzidine (abbreviation: Poly-TPD) can also be used. can.

[0085] By forming a hole injection layer, the hole injection property is improved, and the emission voltage is small. It is possible to obtain an optical element.

[0086] The hole transport layer 112 is a layer containing a substance having a hole transporting property. For example, 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[1, 1'-biphenyl]-4,4'-diamine (abbreviation: TPD), 4,4',4''-tris (N,N-diphenylamino)triphenylamine (abbreviation: TDATA), 4,4',4 ''-Tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine (abbreviation: MTDATA), 4,4'-bis[N-(spiro-9,9'-bifluorene-2 -yl)-N-phenylamino]biphenyl (abbreviation: BSPB), 4-phenyl-4'- (9-Phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP), etc. The aromatic amine compounds described here have high hole transport properties and , mainly 10 -6 cm 2 The composite material described above has a hole mobility of 100 / Vs or more. The organic compounds listed as hole transporting substances in the material can also be used for the hole transport layer 112. In addition, poly(N-vinylcarbazole) (abbreviation: PVK) and poly(4-vinyltetradecane) Polymer compounds such as polyphenylene sulfide (PVTPA) can also be used. The layer containing the hole transporting substance may be a single layer or may be a layer having two or more layers made of the above substance. It may also be a laminate.

[0087] The light-emitting layer 113 is a layer containing a light-emitting substance. Since the light emitting element in this embodiment has the above-mentioned structure, the light emitting efficiency is very high. The structure and materials of the light emitting layer 113 are as described in the embodiment. Please refer to the description of Form 1.

[0088] In the light-emitting layer 113, a material that can be used as a light-emitting substance or a light-emitting center substance The material is not particularly limited. Examples of the luminescent material or luminescent center material include the following: Some examples include:

[0089] The first phosphorescent compound preferably emits blue light, for example, at 440 nm to 520 nm. A phosphorescent compound having an emission peak at 1000 nm can be selected. 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-4H- 1,2,4-Triazolate)iridium(III) (abbreviation: Ir(Mptz)3), tri S[4-(3-biphenyl)-5-isopropyl-3-phenyl-4H-1,2,4-tetramethylbutanoate] 4 such as [riazolate]iridium(III) (abbreviation: Ir(iPrptz-3b)3) Organometallic iridium complexes with H-triazole skeletons and tris[3-methyl-1-( 2-Methylphenyl)-5-phenyl-1H-1,2,4-triazolato]iridium( III) (abbreviation: Ir(Mptz1-mp)3), tris(1-methyl-5-phenyl- 3-Propyl-1H-1,2,4-triazolato)iridium(III) (abbreviation: Ir( Organometallic iridium with a 1H-triazole skeleton, such as Prptz1-Me)3) Complexes and fac-tris[1-(2,6-diisopropylphenyl)-2-phenyl-1 H-imidazole]iridium(III) (abbreviation: Ir(iPrpmi)3), tris[ 3-(2,6-dimethylphenyl)-7-methylimidazo[1,2-f]phenanthridinium Imidazolium such as natoiridium(III) (abbreviation: Ir(dmpimpt-Me)3) Organometallic iridium complexes with zole skeletons and bis[2-(4',6'-difluorophenyl) Phenyl)pyridinato-N,C 2’]Iridium(III) tetrakis(1-pyrazolyl) Borate (abbreviation: FIr6), bis[2-(4',6'-difluorophenyl)pyridina To-N,C 2’ ]Iridium(III) picolinate (abbreviation: FIrpic), bis{2 -[3',5'-Bis(trifluoromethyl)phenyl]pyridinato-N,C 2’}Ili Ir(CF3ppy)2(pic) -(4',6'-difluorophenyl)pyridinato-N,C 2’ ]Iridium(III) Phenyl groups with electron-withdrawing groups such as acetylacetonate (abbreviation: FIr(acac)) Among the above, an organometallic iridium complex having an iridium derivative as a ligand is also included. , 4H-triazole, 1H-triazole, imidazole, etc. The organometallic iridium complex has a high hole trapping property. In the case where the first light-emitting layer in the light-emitting device has an electron transporting property (specifically, the first host material When the material is an electron transport material, an organometallic iridium complex having a polyazole skeleton is used as the first By using the phosphorescent compound 1 as the phosphorescent compound, the carrier recombination region is located in the first light-emitting layer, Alternatively, it is preferable because it can be controlled to be located near the interface between the first light-emitting layer and the second light-emitting layer. The organometallic iridium complexes with 4H-triazole skeletons have excellent reliability and luminescence efficiency. This is particularly preferred because it is excellent.

[0090] The second phosphorescent compound is a compound that emits light at a longer wavelength than the first phosphorescent compound. However, it is preferable to use a phosphorescent material having an emission peak at, for example, 520 nm to 600 nm. Specifically, tris(4-methyl-6-phenylpyridine) Iridium(III) (abbreviation: Ir(mppm)3), tris(4-t-butyl Ir(tBuppm)3 ), (acetylacetonato)bis(6-methyl-4-phenylpyrimidinato)iridium (III) (abbreviation: Ir(mppm)2(acac)), (acetylacetonato)bis( 6-tert-Butyl-4-phenylpyrimidinato)iridium(III) (abbreviation: Ir (tBuppm)2(acac)), (acetylacetonato)bis[6-(2-norborane nyl)-4-phenylpyrimidinato]iridium(III) (abbreviation: Ir(nbppm) 2(acac)), bis{2-[5-methyl-6-(2-methylphenyl)-4-pyrimidinyl 2,4-Pentanedionato-κN3]phenyl-κC} 2 O,O') Iridescent Ir(III) (abbreviation: Ir(mpmppm)2(acac)), (acetylacetonate )Bis(4,6-diphenylpyrimidinato)iridium(III) (abbreviation: Ir(dpp Organometallic iridium complexes with pyrimidine skeletons such as (acac) Cetylacetonato)bis(3,5-dimethyl-2-phenylpyrazinate)iridium(I II) (abbreviation: Ir(mppr-Me)2(acac)), (acetylacetonato)bis (5-isopropyl-3-methyl-2-phenylpyrazinate)iridium(III) Name: Organometallic compounds with a pyrazine skeleton, such as Ir(mppr-iPr)2(acac) Iridium complexes and tris(2-phenylpyridinato-N,C 2’ ) Iridium (III ) (abbreviation: Ir(ppy)3), bis(2-phenylpyridinato-N,C 2’ ) Iridium Ir(III) acetylacetonate (abbreviation: Ir(ppy)2acac), bis(benzo [h]Quinolinato)iridium(III) acetylacetonate (abbreviation: Ir(bzq) 2(acac)), tris(benzo[h]quinolinato)iridium(III) (abbreviation: I r(bzq)3), tris(2-phenylquinolinato-N,C 2’ ) Iridium (III ) (abbreviation: Ir(pq)3), bis(2-phenylquinolinato-N,C 2’ )iridium (III) Pyridyl acetylacetonate (abbreviation: Ir(pq)2(acac)) In addition to organometallic iridium complexes with a phenyl skeleton, tris(acetylacetonato)(monophenyl) Anthroline) terbium(III) (abbreviation: Tb(acac)3(Phen)) Among the above, diazines such as pyrimidines and pyrazines are preferred. Organometallic iridium complexes with an iridium skeleton have weak hole trapping properties and strong electron trapping properties. Therefore, when the second light-emitting layer in the light-emitting element of one embodiment of the present invention has a hole-transporting property, In the case where the second host material is a hole transport material (specifically, when the second host material is a hole transport material), By using an organometallic iridium complex as the second phosphorescent compound, carrier recombination The region is controlled to be within the first light-emitting layer or in the vicinity of the interface between the first light-emitting layer and the second light-emitting layer. In addition, organometallic iridium complexes having a pyrimidine skeleton are preferred because they can be used in a reliable manner. This is particularly preferable because it is remarkably excellent in reliability and luminous efficiency.

[0091] The third phosphorescent compound is a compound that emits light at a longer wavelength than the second phosphorescent compound. However, it is preferable to use a red light emitting diode having a light emission peak at, for example, 600 nm to 700 nm. A phosphorescent compound can be selected. Specifically, bis[4,6-bis(3-methylphenyl)phenyl] (Diisobutyryl)pyrimidinato](diisobutyrylmethano)iridium(III)(Abbreviation: Ir(5mdppm)2(dibm)), bis[4,6-bis(3-methylphenyl)pi [5mdpp](dipivaloylmethanato)iridium(III) m)2(dpm)), bis[4,6-di(naphthalene-1-yl)pyrimidinato](dipyridin Valoylmethanato)iridium(III) (abbreviation: Ir(d1npm)2(dpm)) Organometallic iridium complexes with pyrimidine skeletons such as (acetylacetonato)bis(trifluoromethyl)phenyl (2,3,5-triphenylpyrazinate)iridium(III) (abbreviation: Ir(tppr )2(acac)), bis(2,3,5-triphenylpyrazine)(dipivaloylmeth Nat)iridium(III) (abbreviation: Ir(tppr)2(dpm)), (acetylacetonate quinoxalinato)bis[2,3-bis(4-fluorophenyl)quinoxalinato]iridium(I II) Organogold with a pyrazine skeleton, such as Ir(Fdpq)2(acac) iridium complexes and tris(1-phenylisoquinolinato-N,C 2’ )iridium( III) (abbreviation: Ir(piq)3), bis(1-phenylisoquinolinato-N,C 2’ ) Iridium(III) acetylacetonate (abbreviation: Ir(piq)2acac) In addition to organometallic iridium complexes with pyridine skeletons, 2,3,7,8,12,13, 17,18-Octaethyl-21H,23H-porphyrin platinum(II) (abbreviation: PtO Platinum complexes such as tris(1,3-diphenyl-1,3-propanedione) (Monophenanthroline) europium(III) (abbreviation: Eu(DBM)3(Phen )), tris[1-(2-thenoyl)-3,3,3-trifluoroacetonato](monof phenanthroline) europium(III) (abbreviation: Eu(TTA)3(Phen)) Among the above, diazonium complexes such as pyrimidine and pyrazine are Organometallic iridium complexes with an iridium skeleton have weak hole trapping properties and strong electron trapping properties. Therefore, the third light-emitting layer in the light-emitting element of one embodiment of the present invention has a hole-transporting property. In the case where the third host material is a hole transport material (specifically, when the third host material is a hole transport material), By using an organometallic iridium complex as the third phosphorescent compound, the recombination of carriers is suppressed. The merging region is controlled within the first light-emitting layer or in the vicinity of the interface between the first light-emitting layer and the second light-emitting layer. The organometallic iridium complex having a pyrimidine skeleton is preferably It is particularly preferable because it has outstanding reliability and luminous efficiency. Since an organometallic iridium complex can emit red light with good chromaticity, the white light of one embodiment of the present invention can be obtained. By applying this to light-emitting devices, the color rendering properties can be improved.

[0092] In addition to the phosphorescent compounds described above, known phosphorescent light-emitting materials may be used in the embodiments. A first phosphorescent material, a second phosphorescent material and a third phosphorescent material having a relationship as shown in The fee may be selected and used.

[0093] In addition, there are no particular limitations on the materials that can be used as the first to third host materials. Instead, various carrier transport materials are selected and appropriately used to obtain the device structure shown in FIG. In this case, as described above, a host material having electron transport properties and a host material having hole transport properties are combined. It is preferable to combine the materials.

[0094] For example, an example of a host material having electron transport properties is bis(10-hydroxybenzo[h] Quinolinato) beryllium(II) (abbreviation: BeBq2), bis(2-methyl-8-quinolinato) beryllium(II) Bis(4-phenylphenolato)aluminum(III) (abbreviation: BAlq) (8-quinolinolato)zinc(II)(abbreviation: Znq), bis[2-(2-benzoxazolidinediamine] aryl)phenolato]zinc(II) (abbreviation: ZnPBO), bis[2-(2-benzothiazo Metal complexes such as 2-(4-(phenyl)phenolato)zinc(II) (abbreviation: ZnBTZ) and Phenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butyl) 1,3-bis[5-(p-phenyl)-1,2,4-triazole (abbreviation: TAZ), -tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene( Abbreviation: OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazole-2- 2,2',2''-(1,yl)phenyl]-9H-carbazole (abbreviation: CO11), 3,5-Benzenetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation :TPBI), 2-[3-(dibenzothiophen-4-yl)phenyl]-1-phenyl -1H-benzimidazole (abbreviation: mDBTBIm-II) Heterocyclic compounds having the above structure and 2-[3-(dibenzothiophen-4-yl)phenyl]dibenzo 2-[3'-(diphenylphosphine) (4-phenyl-4-yl)biphenyl-3-yl)dibenzo[f,h]quinoxaline (abbreviation Name: 2mDBTBPDBq-II), 2-[3'-(9H-carbazol-9-yl)biphenyl phenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzBPDBq), 4,6-Bis[3-(phenanthren-9-yl)phenyl]pyrimidine (abbreviation: 4,6 mPnP2Pm), 4,6-bis[3-(4-dibenzothienyl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II) and other heterocyclic compounds with a diazine skeleton. 3,5-Bis[3-(9H-carbazol-9-yl)phenyl]pyridine (abbreviation: 35 DCzPPy), 1,3,5-tri[3-(3-pyridyl)phenyl]benzene (abbreviation: Among the above, heterocyclic compounds having a pyridine skeleton such as TmPyPB are also included. Heterocyclic compounds having a diazine skeleton and heterocyclic compounds having a pyridine skeleton have high reliability. In particular, heterocyclic compounds having a diazine (pyrimidine or pyrazine) skeleton are preferred. The material has high electron transport properties and contributes to reducing the driving voltage.

[0095] As a host material having a hole transporting property, 4,4'-bis[N-(1-naphthyl) -N-phenylamino]biphenyl (abbreviation: NPB), N,N'-bis(3-methylphenyl) N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (abbreviation :TPD), 4,4'-bis[N-(spiro-9,9'-bifluoren-2-yl)-N ―Phenylamino]biphenyl (abbreviation: BSPB), 4-phenyl-4'-(9-phenyl 4-Phenyl- 3'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: mBPAFL) P), 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenyl PCBA1BP, 4,4'-diphenyl-4''-(9-phenyl -9H-carbazol-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4 -(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenyl PCBANNB, 4,4'-di(1-naphthyl)-4''-(9-phenyl) (phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBNBB), 9,9-Dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazole-3 -yl)phenyl]fluoren-2-amine (abbreviation: PCBAF), N-phenyl-N- [4-(9-phenyl-9H-carbazol-3-yl)phenyl]spiro-9,9'- Compounds with aromatic amine skeletons such as bifluorene-2-amine (abbreviation: 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)carbazole (abbreviation: CzTP), -9H-carbazole (abbreviation: PCCP) and other compounds with a carbazole skeleton. 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene)( Abbreviation: DBT3P-II), 2,8-diphenyl-4-[4-(9-phenyl-9H-fu (fluoren-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-III), 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldi Compounds with a thiophene skeleton, such as benzothiophene (abbreviation: DBTFLP-IV), , 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviation Name: DBF3P-II), 4-{3-[3-(9-phenyl-9H-fluorene-9-yl) (phenyl)phenyl)phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II) Among the above, compounds having an aromatic amine skeleton are preferred. Compounds having a carbazole skeleton and other compounds have good reliability and high hole transport properties. This is preferable since it also contributes to reducing the driving voltage.

[0096] In addition to the host materials described above, host materials from known substances may be used. As the host material, the triplet level (between the ground state and the triplet excited state) of the phosphorescent compound is It is preferable to select a substance having a triplet level larger than the energy difference between the two. It is preferable that these host materials do not have an absorption spectrum in the blue region. It is preferable that the absorption edge of the absorption spectrum is 440 nm or less.

[0097] The light-emitting layer 113 having the above-mentioned structure can be formed by co-deposition in a vacuum deposition method or by forming a mixed solution. It can be produced by using an inkjet method, a spin coating method, a dip coating method, etc. do.

[0098] The electron transport layer 114 is a layer containing a substance having an electron transporting property. For example, tris(8-quinolinol) (4-methyl-8-quinolinolato)aluminum (abbreviation: Alq), tris(4-methyl-8-quinolinolato)aluminum Mininium (abbreviation: Almq3), Bis(10-hydroxybenzo[h]quinolinato)beri BeBq2, bis(2-methyl-8-quinolinolato)(4-phenylphenyl) (Enolato)aluminum (abbreviation: BAlq), etc., quinoline skeleton or benzoquinoline skeleton The layer is made of a metal complex having a lattice structure. 2-(2-hydroxyphenyl)benzoxazolato]zinc (abbreviation: Zn(BOX)2), oxazoles such as [(xyphenyl)benzothiazolato]zinc (abbreviation: Zn(BTZ)2) Metal complexes having thiazole-based or thiazole-based ligands can also be used. In addition, 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3 ,4-Oxadiazole (abbreviation: PBD) and 1,3-bis[5-(p-tert-butyl 1,3,4-oxadiazol-2-yl)benzene (abbreviation: OXD-7 ), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl) -1,2,4-triazole (abbreviation: TAZ), bathophenanthroline (abbreviation: BPhe n), bathocuproine (abbreviation: BCP), etc. can also be used. has high electron transport properties and is mainly -6 cm 2 / Vs or higher. The electron transporting host material described above may be used for the electron transporting layer 114.

[0099] In addition, the electron transport layer 114 may be a single layer or may be a laminate of two or more layers made of the above-mentioned materials. It may also be layered.

[0100] In addition, a layer for controlling the movement of electron carriers may be provided between the electron transport layer and the light emitting layer. This is achieved by adding a small amount of a substance with high electron trapping properties to a material with high electron transport properties as described above. A layer that adjusts the carrier balance by suppressing the movement of electron carriers. This type of structure prevents light from being emitted by electrons passing through the light-emitting layer. This is highly effective in suppressing problems that arise (such as a decrease in element life).

[0101] In addition, an electron transport layer 114 is provided between the electron transport layer 114 and the second electrode 102. An electron injection layer 115 may be provided. The electron injection layer 115 may be formed of lithium fluoride (LiF), Alkali metals such as cesium fluoride (CsF), calcium fluoride (CaF2), etc. Alkaline earth metals or compounds thereof can be used. For example, The layer is made of a material containing an alkali metal or an alkaline earth metal or a compound thereof. Note that the electron-injecting layer 115 can be formed of a material having an electron-transporting property. By using a layer containing an alkali metal or an alkaline earth metal, This is more preferable because electron injection from the second electrode 102 can be performed efficiently.

[0102] The material for forming the second electrode 102 is a material having a small work function (specifically, 3.8 eV Metals, alloys, electrically conductive compounds, and mixtures thereof can be used. Examples of such cathode materials include lithium (Li) and cesium (Cs). Potash metal, as well as magnesium (Mg), calcium (Ca), and strontium (Sr) Elements belonging to Group 1 or 2 of the Periodic Table, such as Mg, Ag, etc., and alloys containing these elements (e.g., , AlLi), europium (Eu), ytterbium (Yb), and other rare earth metals However, the second electrode 102 and the electron transport layer may be formed of a material other than the above-mentioned material. By providing an electron injection layer, the material can be made of Al, Ag, ITO, and ketone regardless of the magnitude of the work function. Various conductive materials such as indium oxide-tin oxide containing silicon oxide or indium tin oxide are used as the second These conductive materials can be used as the electrode 102 by sputtering or in-situ deposition. The film can be formed by using a jet method, a spin coating method, or the like.

[0103] The EL layer 103 can be formed by a variety of methods, including a dry method and a wet method. For example, a vacuum deposition method, an inkjet method, a spin coating method, or the like can be used. Also, each electrode or each layer may be formed using a different film formation method. .

[0104] The electrodes may be formed by a wet method using the sol-gel method, or by a paste of a metal material. Alternatively, the insulating layer 12 may be formed by a dry method such as a sputtering method or a vacuum deposition method. It may be formed using.

[0105] The light-emitting element having the above-mentioned structure has a first electrode 101 and a second electrode 102 between them. The generated potential difference causes a current to flow, and the light-emitting layer 113, which is a layer containing a highly light-emitting substance, The holes and electrons recombine to emit light. It is structured so that

[0106] The light is emitted through either the first electrode 101 or the second electrode 102, or both. Therefore, either the first electrode 101 or the second electrode 102 Or both of them are made of an electrode having light transmitting properties. Only the first electrode 101 is an electrode having light transmitting properties. When the second electrode 102 is When only the second electrode 102 is a light-transmitting electrode, the emitted light is extracted through the second electrode 102. When the first electrode 101 and the second electrode 102 are both light-transmitting electrodes, light emission is taken out from both the first electrode 101 and the second electrode 102.

[0107] The structure of the layers provided between the first electrode 101 and the second electrode 102 is the same as that described above. However, the present invention is not limited to the above. The first electrode 101 and the second electrode 102 are arranged so as to suppress quenching caused by contact. It is preferable to provide a light-emitting region where holes and electrons recombine at a location away from 102 .

[0108] In addition, the hole transport layer and the electron transport layer in contact with the light emitting layer 113, particularly the light emitting layer 113 The carrier transport layer, which is adjacent to the region closer to the active layer, is responsible for the energy transfer from the excitons generated in the light-emitting layer. In order to suppress the band gap, the luminescent material constituting the luminescent layer or the material contained in the luminescent layer is The material has a band gap larger than that of the luminescent center material. It is preferable to form the

[0109] The light emitting element in this embodiment is manufactured on a substrate made of glass, plastic, or the like. Regarding the order of fabrication on the substrate, the layers may be stacked in order from the first electrode 101 side. The light emitting device may be formed by forming one light emitting element on one substrate. A single light emitting element may be formed on one substrate, or a plurality of light emitting elements may be formed on one substrate. By fabricating multiple elements, it is possible to create lighting devices with separate elements and passive matrix light-emitting devices. Also, a thin film, for example, can be formed on a substrate made of glass, plastic, etc. A thin-film transistor (TFT) is formed, and a light-emitting element is fabricated on the electrode electrically connected to the TFT. This allows an active matrix display device to control the driving of light-emitting elements using TFTs. A light-emitting device of this type can be manufactured. The structure of the TFT is not particularly limited. The TFT may be a TFT of a staggered type or a reverse staggered type. There is no particular limitation on the type of semiconductor, and either an amorphous semiconductor or a crystalline semiconductor may be used. In addition, the driving circuit formed on the TFT substrate is also made up of N-type and P-type TFTs. Alternatively, the TFT may be composed of only one of N-type TFT or P-type TFT. It may be also possible.

[0110] Note that this embodiment mode can be appropriately combined with other embodiment modes.

[0111] (Embodiment 3) In this embodiment, a light-emitting device using the light-emitting element described in Embodiments 1 and 2 is This article explains:

[0112] In this embodiment, a light-emitting element manufactured using the light-emitting element described in Embodiments 1 and 2 is used. The light-emitting device will be described with reference to FIG. 6. FIG. 6(A) is a top view showing the light-emitting device. 6B is a cross-sectional view taken along lines AB and CD in FIG. The light emission of the light emitting element is controlled by a driving circuit section (source line driving circuit) shown by a dotted line. The display device includes a display circuit (gate line driver) 601, a pixel section 602, and a driver circuit section (gate line driver circuit) 603. 604 is a sealing substrate, 625 is a desiccant, and 605 is a sealant. The inside of the hole is a space 607.

[0113] 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 the input signal, and the FPC (flexible printed circuit board) is the external input terminal. Video signal, clock signal, start signal, reset signal from Lint Circuit 609 Although only the FPC is shown here, the FPC has a printed circuit board. A printed wiring board (PWB) may be attached. This includes not only the device itself, but also the state in which an FPC or PWB is attached to it. do.

[0114] Next, the cross-sectional structure will be described with reference to FIG. A source line driver circuit 601, which is a driver circuit section, and a pixel section are formed in this example. 6, one pixel in the pixel section 602 is shown.

[0115] The source line driver circuit 601 includes an n-channel TFT 623 and a p-channel TFT 62 4 is combined to form a CMOS circuit. The driving circuit is also a variety of CMOS circuits. Alternatively, the substrate may be a PMOS circuit or an NMOS circuit. Although the driver integrated type with the drive circuit is shown above, this is not necessarily required. It may also be formed externally rather than on the substrate.

[0116] The pixel section 602 includes a switching TFT 611, a current control TFT 612, and The pixel is formed of a plurality of pixels including a first electrode 613 electrically connected to the drain. An insulator 614 is formed to cover the end of the first electrode 613. It is formed by using a photosensitive acrylic resin film of a mold.

[0117] In order to improve the covering property, the upper end or the lower end of the insulator 614 is provided with a curvature. For example, the material of the insulator 614 is a positive photosensitive adhesive. When using krill, the insulator 614 has a radius of curvature (0.2 μm to 3 μm) only at the top end. It is preferable to provide a curved surface for the insulating material 614. Alternatively, a positive photosensitive resin can be used.

[0118] 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 material with a large resistance. For example, an ITO film or an indium tin oxide film containing silicon indium tin oxide film, indium oxide film containing 2-20wt% zinc oxide, titanium nitride film, In addition to single-layer films such as chromium film, tungsten film, Zn film, and Pt film, titanium nitride and aluminum film are also available. A titanium nitride film and an aluminum-based film are laminated together. In addition, a three-layer structure with a silicon film can be used. The resistance is low, good ohmic contact can be achieved, and the material can also function as an anode. .

[0119] The EL layer 616 is formed by deposition using a deposition mask, inkjet printing, spin coating, etc. The EL layer 616 is formed by various methods such as the method of forming a luminescent layer or the method of forming a luminescent layer. The EL layer 616 may include other materials such as: It may be a low molecular weight compound or a high molecular weight compound (including oligomers and dendrimers). .

[0120] Furthermore, a material for a second electrode 617 that is formed on the EL layer 616 and functions as a cathode is The materials used are those with low work functions (Al, Mg, Li, Ca, or their alloys or compounds). It is preferable to use an EL layer 616 made of a material such as a compound of MgAg, MgIn, or AlLi. In the case where the light generated in the second electrode 617 is transmitted through the second electrode 617, the film thickness is set to Thinned metal film and transparent conductive film (ITO, indium oxide containing 2 to 20 wt% zinc oxide) It uses lamination of indium, silicon-containing indium tin oxide, zinc oxide (ZnO, etc.) It is better.

[0121] 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 and Embodiment 2. In addition, a pixel portion is formed with a plurality of light emitting elements. The light-emitting elements described in the first and second embodiments and light-emitting elements having other structures are described below. Both elements may be included.

[0122] Furthermore, the sealing substrate 604 is bonded to the element substrate 610 with a sealant 605. A light-emitting element is disposed in a space 607 surrounded by an element substrate 610, a sealing substrate 604, and a sealant 605. The space 607 is filled with a filler. In addition to being filled with an inert gas (nitrogen, argon, etc.), it is also possible to fill it with a sealing material 605. If a recess is formed in the sealing substrate and a desiccant 625 is provided there, the sealing substrate can be protected from the effects of moisture. This is a preferable configuration because it is possible to suppress deterioration due to the above-mentioned causes.

[0123] It is preferable to use epoxy resin or glass frit for the sealing material 605. In addition, it is desirable that these materials are as impermeable to moisture and oxygen as possible. The material used for the sealing substrate 604 may be a glass substrate, a quartz substrate, or FRP (Fibre Reinforced Plastics). Glass-Reinforced Plastics), PVF (Polyvinyl fluoride ), a plastic substrate made of polyester, acrylic or the like can be used.

[0124] In the above manner, the light-emitting element described in the embodiment 1 or 2 is used to manufacture the semiconductor device. A light emitting device having such a structure can be obtained.

[0125] The light-emitting device in this embodiment includes the light-emitting element described in Embodiments 1 and 2. Since the organic EL element is used, a light emitting device having excellent characteristics can be obtained. The light-emitting element shown in Embodiment 1 and Embodiment 2 has high emission efficiency and consumes less power. In addition, the light emitting device can be a light emitting device that requires a low driving voltage. Thus, a light emitting device can be obtained.

[0126] As described above, in this embodiment, an active matrix light emitting device will be described. However, a passive matrix type light emitting device may also be used. FIG. 7(A) shows a passive matrix light-emitting device manufactured by 7(B) is a cross-sectional view taken along the line XY in FIG. 7(A). On the substrate 951 , an EL layer 955 is provided between an electrode 952 and an electrode 956 . The ends of the electrodes 952 are covered with an insulating layer 953. A partition layer 9 The side walls of the partition layer 954 are gradually narrower toward the substrate surface. The partition layer 954 has a slope such that the distance between the first side wall and the second side wall becomes narrower. The cross section in the side direction is trapezoidal, and the base (which faces in the same direction as the surface direction of the insulating layer 953 and The upper side (the side in contact with the insulating layer 953) faces in the same direction as the surface direction of the insulating layer 953, 53) is shorter than the side not in contact with the partition layer 954. In addition, it is possible to prevent defects in the light-emitting element caused by the above-mentioned problem. In the present invention, the light-emitting device includes the light-emitting element according to the first embodiment and the light-emitting element according to the second embodiment, which operates at a low driving voltage. By doing so, it is possible to operate the device with low power consumption. By including the light-emitting element according to the second aspect, a highly reliable light-emitting device can be obtained. become.

[0127] In order to achieve full-color display, a light emitting element must have a certain thickness in order for the light to exit the light emitting device. A colored layer or a color conversion layer may be provided on the optical path. An example of a laser-formed light-emitting device is shown in Figures 8(A) and (B). Undercoat insulating film 1002, gate insulating film 1003, gate electrodes 1006, 1007, 1008 , a first interlayer insulating film 1020, a second interlayer insulating film 1021, a peripheral portion 1042, a pixel portion 10 40, driving circuit section 1041, first electrodes 1024W, 1024R, 1024G of the light-emitting element , 1024B, a partition wall 1025, a layer including an organic compound 1028, a second electrode 10 of the light-emitting element 29, a sealing substrate 1031, a seal material 1032, etc. are shown. The colored layer 1034R, the green colored layer 1034G, and the blue colored layer 1034B) are made of a transparent substrate. A black layer (black matrix) 1035 may be further provided. The transparent base material 1033 on which the colored layer and the black layer are provided is aligned and then attached to the substrate 1001. The colored layer and the black layer are covered with an overcoat layer 1036. In this embodiment, the light emitting layer emits light to the outside without passing through the colored layers, and the colored layers The light that does not pass through the colored layer is white, and the light that does pass through the colored layer is white. Since the light that passes through is red, blue, and green, images can be displayed using four color pixels.

[0128] In the light emitting device described above, light is taken in from the substrate 1001 side on which the TFT is formed. The light emitting device has a bottom emission structure, but the light is emitted from the sealing substrate 1031 side. The light emitting device may have a structure in which the light is extracted (top emission type). Top emission type A cross-sectional view of the light-emitting device is shown in FIG. 9. In this case, a substrate 1001 that does not transmit light is used. Until the connection electrode that connects the TFT and the anode of the light-emitting element is fabricated, The third interlayer insulating film 1037 is then formed in the same manner as in the case of an emission type light emitting device. This third interlayer insulating film 1037 plays a role of flattening. The third interlayer insulating film 1037 may be made of the same material as the second interlayer insulating film, or may be made of other known materials. It can be formed using materials.

[0129] The first electrodes 1024W, 1024R, 1024G, and 1024B of the light-emitting element are positive electrodes. The electrode is generally a top electrode, but it can also be a cathode. In the case of a liquid crystal display device, the first electrode is preferably a reflective electrode. The configuration of the LED 28 is as described in the first and second embodiments, and white light is emitted. The device structure is designed to obtain white light emission. In this case, blue light is emitted from the light-emitting layer in one EL layer and blue light is emitted from the light-emitting layer in the other EL layer. One of the EL layers emits orange light, while the other emits blue light. The other EL layer may be configured to emit red and green light. In addition, when three EL layers are used, red, green, and blue light are emitted from each emitting layer. By making it possible to obtain light emission of the above formula, a light-emitting element that emits white light can be obtained. If the configurations shown in the first and second embodiments are applied, white light can be obtained. Of course, the configuration is not limited to this.

[0130] The colored layer is provided on the optical path through which the light from the light emitting element exits to the outside. In the case of an M-emission type light-emitting device, a transparent substrate 1033 is provided with colored layers 1034R and 1034 G, 1034B and fixed to the substrate 1001. As shown in FIG. 8B, the colored layer is disposed between the gate insulating film 1003 and the first interlayer insulating film 1020. In the case of a top emission structure as shown in FIG. A seal having a colored layer 1034R, a green colored layer 1034G, and a blue colored layer 1034B) The sealing substrate 1031 may be provided between the pixels. A black layer (black matrix) 1035 may be provided so as to be placed on the substrate. Colored layer 1034R, green colored layer 1034G, blue colored layer 1034B) and black layer (black The matrix 1035 may be covered by an overcoat layer 1036 . Note that the sealing substrate 1031 is a light-transmitting substrate.

[0131] When a voltage is applied between the pair of electrodes of the organic light-emitting device thus obtained, a white light-emitting region 10 In addition, by combining with a colored layer, a red light emitting region 1044R and A blue light emitting region 1044B and a green light emitting region 1044G are obtained. Since the light-emitting device uses the light-emitting element described in Embodiment 1 and Embodiment 2, the consumption It is possible to realize a light emitting device that consumes less power.

[0132] In addition, although an example of full-color display using four colors, red, green, blue, and white, is shown here, the present invention is not limited to such a case. Alternatively, full color display may be achieved using the three colors red, green, and blue.

[0133] This embodiment mode can be freely combined with other embodiment modes.

[0134] (Embodiment 4) In this embodiment, the light-emitting element described in Embodiments 1 and 2 is used as a lighting device. An example of use will be described with reference to FIG. 10. FIG. 10(B) is a top view of the lighting device, and FIG. FIG. 10A is a cross-sectional view taken along line ef in FIG.

[0135] The lighting device in this embodiment is a first substrate 400 on a light-transmitting substrate 400 serving as a support. The first electrode 401 is the same as the first electrode 1 in the third embodiment. Equivalent to 01.

[0136] An auxiliary electrode 402 is provided on the first electrode 401. In this embodiment, Since an example in which light is extracted from the electrode 401 side has been shown, the first electrode 401 is made of a light-transmitting material. The auxiliary electrode 402 is designed to compensate for the low electrical conductivity of the light-transmitting material. The resistance of the first electrode 401 is high, and the voltage drop in the light-emitting surface is the cause of the problem. The auxiliary electrode 402 has a function of suppressing uneven brightness. The insulating layer is formed of a material having a higher electrical conductivity than the insulating material, and preferably made of a material having a higher electrical conductivity, such as aluminum. In addition, the auxiliary electrode 402 is connected to the first electrode 401. It is preferable that the surface other than the part to be removed is covered with an insulating layer. This is to suppress light emission from the upper part of the auxiliary electrode 402, which cannot be detected by the ion beam, and to reduce reactive current and improve power efficiency. This is to suppress the decrease in the efficiency. A pad 412 may be formed for supplying a voltage to the

[0137] The EL layer 403 is formed on the first electrode 401 and the auxiliary electrode 402. 3 has the configurations described in the first and second embodiments. For details, please refer to the description. Note that the EL layer 403 is located closer to the first electrode 401 than the first electrode 401 when viewed in plan. By forming the electrode 401 slightly larger, a short circuit between the first electrode 401 and the second electrode 404 is suppressed. This is a preferable configuration since it also plays the role of an insulating layer.

[0138] The second electrode 404 is formed to cover the EL layer 403. This corresponds to the second electrode 102 in the embodiment and has a similar configuration. Since light is extracted from the first electrode 401 side, the second electrode 404 is made of a highly reflective material. In this embodiment, the second electrode 404 is preferably formed by the pad 4. Voltage is supplied by connecting to 12.

[0139] As described above, the first electrode 401, the EL layer 403, and the second electrode 404 (and the auxiliary electrode 402) The lighting device described in this embodiment has a light-emitting element having a light-emitting efficiency of Since the light emitting element has a high efficiency, the lighting device in this embodiment is a lighting device with low power consumption. In addition, since the light-emitting element is a highly reliable light-emitting element, The lighting device according to the embodiment can be a highly reliable lighting device.

[0140] The light emitting element having the above structure is fixed to a sealing substrate 407 using sealing materials 405 and 406. The lighting device is completed by attaching and sealing the sealing materials 405 and 406. Also, a desiccant can be mixed into the inner sealant 406. This allows the material to adsorb moisture, leading to improved reliability.

[0141] In addition, the pad 412, the first electrode 401, and a part of the auxiliary electrode 402 are covered with a sealant 405. By extending it outside 406, it can be used as an external input terminal. An IC chip 420 having a converter mounted thereon may be provided on the same.

[0142] As described above, the lighting device according to the present embodiment has the EL element according to the first and second embodiments. Since the light-emitting element described above is included, a lighting device with low power consumption can be obtained. In this way, it is possible to provide a lighting device with a low driving voltage. can be done.

[0143] (Embodiment 5) In this embodiment, the light-emitting element described in the embodiment 1 and the embodiment 2 is included as a part of the light-emitting element. Examples of electronic devices will be described. The light-emitting elements described in Embodiments 1 and 2 are This light-emitting element has good efficiency and reduced power consumption. The electronic device may be an electronic device having a light-emitting section with reduced power consumption. In addition, the light-emitting elements described in Embodiments 1 and 2 are light-emitting elements that can be driven at a low voltage. Therefore, it is possible to provide an electronic device with a low driving voltage.

[0144] As an example of an electronic device to which the light-emitting element is applied, a television set (television, (also called revision receivers), computer monitors, 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, pachinko machines and other large game machines, etc. Specific examples of these electronic devices are shown below.

[0145] FIG. 11A shows an example of a television device. The television device has a housing 71. A display unit 7103 is built into the display unit 7101. The display unit 7103 can display images. The display portion 7103 may include the light-emitting element described in Embodiments 1 and 2. The light emitting elements are arranged in a rectangular shape. The light emitting elements have good light emitting efficiency. It is also possible to provide a light emitting element with a low driving voltage. It is possible to make the light emitting element have a long life. Television equipment having 7103 shall be television equipment with reduced power consumption. It is also possible to provide a television device with a low driving voltage. This makes it possible to provide a highly reliable television device.

[0146] The television device can be operated using an operation switch provided on the housing 7101 or a separate remote control. The remote control device 7110 includes an operation key 7109. 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 image forming apparatus may be provided.

[0147] The television set is assumed to be equipped with a receiver and a modem. It can receive television broadcasts and can also communicate by wire or wirelessly via a modem. By connecting to a network, communication can be one-way (sender to receiver) or two-way (sender to It is also possible to communicate information between the sender and the recipient, or between the recipients themselves.

[0148] FIG. 11(B1) shows a computer, which includes a main body 7201, a housing 7202, a display portion 7203, Including a keyboard 7204, an external connection port 7205, a pointing device 7206, etc. This computer is similar to the one described in the second or third embodiment. The display portion 7203 is manufactured by arranging light-emitting elements in a matrix. The computer of FIG. 1(B1) may be in the form of FIG. 11(B2). 2) The computer uses a keyboard 7204 and a pointing device 7206 instead The second display portion 7210 is a touch panel type. The input display on the second display unit 7210 can be operated with a finger or a special pen. The second display unit 7210 can be used not only for displaying input data, but also for displaying the The display unit 7203 can also display other images. It's okay. The two screens are connected by a hinge, which makes it easier to store and transport. This also prevents the occurrence of problems such as scratching or breaking the screen. The device can be a light-emitting element with good light-emitting efficiency. The computer having the display unit 7203 is a computer with reduced power consumption. It is possible.

[0149] FIG. 11C shows a portable game machine that is composed of two housings, a housing 7301 and a housing 7302. The housing 7301 is connected to the connector 7303 so as to be openable and closable. A display device manufactured by arranging the light-emitting elements described in the first and second embodiments in a matrix. A display portion 7305 is incorporated in the housing 7302. The portable game machine shown in FIG. 11C also includes a speaker unit 7306 and a recording medium insertion unit 73 07, LED lamp 7308, input means (operation keys 7309, connection terminal 7310, sensor 7311 (force, displacement, position, velocity, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature , chemicals, voice, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, Equipped with a microphone 7312) and other equipment, including a function to measure vibration, odor, or infrared rays Of course, the configuration of the portable gaming machine is not limited to the above, and at least the display unit The display portion 7304 and / or the display portion 7305 may be It is sufficient to use a display unit in which the above-mentioned light-emitting elements are arranged in a matrix. The portable gaming machine shown in FIG. 11(C) is A function to read out the program or data recorded on the recording medium and display it on the display unit, It has a function to share information with other portable gaming machines through wireless communication. The functions of the portable gaming machine shown in are not limited to these, and the portable gaming machine may have various functions. The portable game machine having the display unit 7304 as described above has a display unit 7304. Since the light-emitting element has good light-emitting efficiency, the portable game machine has reduced power consumption. In addition, the light-emitting element used in the display portion 7304 can be driven at a low driving voltage. Since the device can be operated in a variety of ways, it is possible to provide a portable gaming machine that requires a small driving voltage. In addition, since the light-emitting element used in the display portion 7304 has a long life, This makes it possible to create a highly reliable portable gaming machine.

[0150] FIG. 11D shows an example of a mobile phone. The mobile phone is built in a housing 7401. In addition to the display unit 7402, the operation buttons 7403, the external connection port 7404, the speaker 7 405, a microphone 7406, etc. The mobile phone 7400 is the same as that of the first embodiment. and a display portion 7402 in which the light-emitting elements described in Embodiment 2 are arranged in a matrix. The light-emitting element can have high light-emitting efficiency. In addition, it is possible to provide a light-emitting element having a long life. Therefore, a portable phone having a display portion 7402 including the light-emitting element can be used. The handset can be a mobile phone with reduced power consumption. It is possible to make a mobile phone with high reliability. do.

[0151] In the mobile phone shown in FIG. 11D, information can be input by touching the display portion 7402 with a finger or the like. In this case, the user can make a call or write an email. An operation such as making a setting can be performed by touching the display portion 7402 with a finger or the like.

[0152] The screen of the display unit 7402 has three main modes. The first is a display mode that is mainly used for displaying images. The first mode is a display mode, the second is an input mode for inputting information such as characters, and the third mode is a display mode. This is a display + input mode that combines the display mode and the input mode.

[0153] For example, when making a call or composing an e-mail, the display unit 7402 is used to input characters. The main character input mode is to 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. I wish.

[0154] In addition, the mobile phone may include a sensor that detects the inclination of the mobile phone, such as a gyro or an acceleration sensor. By providing a display device, the orientation of the mobile phone (vertical or horizontal) can be determined and the image of the display portion 7402 can be displayed. The surface display can be switched automatically.

[0155] The screen mode can be changed 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, the image signal to be displayed on the display unit is a moving image. If it is data, the mode is switched to display mode, and if it is text data, the mode is switched to input mode.

[0156] In the input mode, the optical sensor of the display unit 7402 detects a signal and displays If there is no input by touch operation of 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.

[0157] The display portion 7402 can also function as an image sensor. By touching the palm or fingers of the user on the sensor 02 and capturing an image of the palm print or fingerprint, the user can be authenticated. 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.

[0158] Note that the configuration shown in this embodiment mode is a combination of the configurations shown in Embodiment Modes 1 to 4. They can be used in combination.

[0159] As described above, the scope of application of the light emitting device including the light emitting element according to the first and second embodiments is as follows: The range of applications is extremely wide, and this light emitting device can be applied to electronic devices in all fields. By using the light-emitting element described in Embodiment 1 and Embodiment 2, power consumption can be reduced. The electronic device can be obtained.

[0160] FIG. 12 shows a case where the light-emitting element according to the first and second embodiments is applied to a backlight. The liquid crystal display device shown in FIG. 12 includes a housing 901, a liquid crystal layer 902, and a liquid crystal display device. 902, a driver IC 90 5. The backlight unit 903 is connected to the The light emitting element according to the second embodiment is used, and a current is supplied through a terminal 906 .

[0161] The light-emitting element described in the first and second embodiments is applied to a backlight of a liquid crystal display device. As a result, a backlight with reduced power consumption can be obtained. By using the light-emitting device described above, it is possible to fabricate a surface-emitting lighting device, and it is also possible to make the device larger in area. This makes it possible to increase the area of ​​the backlight, and therefore the area of ​​the liquid crystal display device. Furthermore, the light emitting device to which the light emitting element described in the second embodiment is applied is thinner than the conventional one. Since the size can be reduced, the display device can be made thinner.

[0162] FIG. 13 shows a configuration in which the light-emitting element described in each of the first and second embodiments is mounted on an electric switch which is a lighting device. The desk lamp shown in FIG. 13 is an example of a desk lamp that is used for a lamp. The light emitting device described in the fourth embodiment is used as the light source 2002.

[0163] FIG. 14 shows an indoor lighting device 300 in which the light-emitting element described in the first and second embodiments is used. 1 and a display device 3002. Since the light-emitting element is a light-emitting element with reduced power consumption, a lighting device with reduced power consumption can be provided. In addition, the light-emitting elements described in the first and second embodiments can be made large-area. Since this is possible, it can be used as a large-area lighting device. The light-emitting element described in the second embodiment is thin and can be used as a thin lighting device. It becomes possible.

[0164] The light emitting elements described in the first and second embodiments are used for the windshield and dash of an automobile. FIG. 15 shows the light-emitting element described in the second embodiment. An embodiment for use on a windshield or dashboard is shown. The display is provided using the light-emitting element described in Embodiments 1 and 2.

[0165] The display 5000 and the display 5001 are the same as those in the first embodiment and the second embodiment, which are provided on the windshield of an automobile. A display device incorporating the light-emitting device according to the second embodiment. The light-emitting element described in 2 is manufactured by using a first electrode and a second electrode having a light-transmitting property. As a result, a so-called see-through display device can be obtained, in which the opposite side can be seen through. If the display is see-through, even if it is installed on the windshield of a car, the visibility will be reduced. It can be installed without being disturbed. In this case, organic transistors using organic semiconductor materials and transistors using oxide semiconductors are used. For example, a light-transmitting transistor such as a transistor having a light-transmitting property may be used.

[0166] The display 5002 is the light-emitting element described in the first and second embodiments provided in the pillar portion. The display 5002 displays an image captured by an imaging means provided on the vehicle body. By projecting the image, it is possible to complement the view blocked by the pillar. The display 5003 provided on the dashboard allows the driver to see through the obstructed view of the vehicle body. By projecting images from an imaging device installed outside the vehicle, blind spots are filled and safety is improved. By projecting an image that complements the invisible parts, it becomes more natural. This allows users to perform safety checks without any discomfort.

[0167] Display 5004 and Display 5005 display navigation information, speedometer and tachometer , mileage, fuel level, gear status, air conditioning settings, and various other information. The display items and layout can be changed as needed to suit the user's preferences. This information can also be provided in displays 5000 to 5003. Moreover, the displays 5000 to 5005 can also be used as lighting devices.

[0168] The light-emitting elements described in the first and second embodiments are light-emitting elements with high luminous efficiency. In addition, it is possible to provide a light-emitting element with low power consumption. Even if you install many large screens such as the 5000 to 5005, it will not put a strain on the battery. Since the above-mentioned configuration is less likely to cause trouble and can be used comfortably, the first and second embodiments are preferred. A light-emitting device or a lighting device using the light-emitting element described above can be used as an in-vehicle light-emitting device or a lighting device. It can be suitably used.

[0169] FIG. 16(A) and FIG. 16(B) show an example of a tablet terminal that can be folded in half. FIG. 6(A) shows the tablet terminal in an open state. The tablet terminal includes a housing 9630 and a display unit 9631a. , a display unit 9631b, a display mode changeover switch 9034, a power switch 9035, A power mode changeover switch 9036, a fastener 9033, and an operation switch 9038 are included. The tablet terminal includes the light-emitting element described in the first and second embodiments. By using the light-emitting device as one or both of the display portions 9631a and 9631b, It is produced.

[0170] A part of the display unit 9631a can be used as a touch panel area 9632a. By touching the operation keys 9637, data can be input. In 1a, as an example, half of the area has a display function only, and the other half The display unit 963 has a touch panel function, but is not limited to this. The entire area of ​​the display unit 96 may have a touch panel function. The entire surface of 31a is made to display keyboard buttons to make it a touch panel, and the display part 9631b is displayed It can be used as a screen.

[0171] In addition, in the display unit 9631b, as in the display unit 9631a, The portion of the keyboard 9632 can be used as a touch panel area 9632b. By touching the area where the display switch button 9639 is displayed with your finger or a stylus, Keyboard buttons can be displayed on the display portion 9631b.

[0172] In addition, when touching the touch panel area 9632a and the touch panel area 9632b at the same time, You can also input the

[0173] A display mode changeover switch 9034 is used to change the display orientation, such as portrait or landscape. You can switch between black and white and color display. The switch 9036 is a switch that turns on and off when the tablet terminal is in use and is detected by a light sensor built into the tablet terminal. The brightness of the display can be optimized according to the amount of light. In addition to sensors, other detection devices such as gyros, acceleration sensors, etc. that detect tilt may be incorporated.

[0174] FIG. 16A shows an example in which the display area of ​​the display portion 9631b is the same as that of the display portion 9631a. However, there is no particular limitation, and one size may be different from the other size. The quality of the display may also be different. For example, one display panel may provide a higher resolution display than the other. It may also be used as a rule.

[0175] FIG. 16B shows the tablet terminal in the closed state. Body 9630, solar cell 9633, charge / discharge control circuit 9634, battery 9635, DCD 16B shows an example in which a charge / discharge control circuit 963 is provided. As an example of 4, a configuration having a battery 9635 and a DCDC converter 9636 It shows.

[0176] In addition, since the tablet device can be folded in half, the case 9630 can be folded when not in use. Therefore, the display portions 9631a and 9631b can be protected. This makes it possible to provide a tablet device that is highly durable and reliable even when used for a long period of time.

[0177] In addition, the tablet terminals shown in Figs. 16(A) and 16(B) can be used in various Functions that display information (still images, videos, text images, etc.), calendars, dates, or times A function to display information on the display unit, and a function to input or edit information displayed on the display unit. It has input functions, functions to control processing by various software (programs), etc. It is possible.

[0178] The solar cell 9633 attached to the surface of the tablet device supplies power to the touch panel. The solar cell 9633 can supply the light to a display unit, a video signal processor, or the like. The battery 9635 can be efficiently charged by providing a light-emitting diode (LED) on one or both sides of the housing 9630. The configuration may be such that:

[0179] The configuration and operation of the charge / discharge control circuit 9634 shown in FIG. A block diagram is shown in FIG. 16(C) and will be explained. FIG. 16(C) shows a solar cell 9633, a battery 9 635, DC-DC converter 9636, converter 9638, switches SW1 to SW3 , a display unit 9631, a battery 9635, a DC-DC converter 963 6. The converter 9638 and the switches SW1 to SW3 are configured to perform the charge / discharge control shown in FIG. 16(B). This corresponds to the circuit 9634 .

[0180] First, an example of operation in which power is generated by the solar cell 9633 using external light will be described. The power generated by the solar cell is converted to DC voltage to charge the Battery 9635. The voltage is increased or decreased by the DC converter 9636. When the power charged by the solar cell 9633 is used, switch SW1 is turned on and the The inverter 9638 raises or lowers the voltage to the voltage required for the display unit 9631. When the display unit 9631 is not to be displayed, turn SW1 off and SW2 on to The configuration may be such that the battery 9635 is charged.

[0181] Although the solar cell 9633 is shown as an example of a power generating means, the power generating means is not particularly Other power generating devices such as, but not limited to, piezoelectric elements (piezo elements) and thermoelectric conversion elements (Peltier elements) may also be used. The battery 9635 may be charged by a wireless (non-contact) means. It can be combined with a non-contact power transmission module that transmits and receives power to charge, or other charging methods. The power generating means may be omitted.

[0182] In addition, if the display unit 9631 is provided, a tablet terminal having the shape shown in FIG. Not limited to. EXAMPLES

[0183] In this example, one embodiment of the present invention uses the compounds (1) to (3) described in the first embodiment. The light-emitting element 1 and the light-emitting element 2 corresponding to the embodiment will be described. The first light-emitting layer 113B, the second light-emitting layer 113G, and the third light-emitting layer 113R are formed of the following materials. The phosphorescent compounds that can be used are the compound (1) and the compound (2) described in the first embodiment. ) and compound (3), the emission wavelengths (F(λ) and ε(λ) 4 of The relationship is as explained in FIG. 5 in the first embodiment.

[0184] Substances used in the light-emitting element in this embodiment are shown below.

[0185] [ka]

[0186] A method for fabricating the light-emitting element 1 and the light-emitting element 2 of this example will be described below.

[0187] (Method of manufacturing light-emitting element 1) First, indium tin oxide containing silicon oxide (ITSO) was sputtered onto a glass substrate. The first electrode 101 was formed by a deposition method. The area was set to 2 mm×2 mm. Here, the first electrode 101 functions as an anode of the light-emitting element. It is an electrode that

[0188] Next, as a pretreatment for forming a light emitting element on the substrate, the substrate surface was washed with water and then dried for 200 After baking at ℃ for 1 hour, UV ozone treatment was performed for 370 seconds.

[0189] Then, 10 -4 The substrate is placed in a vacuum deposition apparatus whose inside has been reduced in pressure to about Pa, and vacuum deposition is performed. 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.

[0190] 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 installed in a vacuum deposition apparatus and was heated for 10 -4 Reduced to about Pa After pressing, a film represented by the above structural formula (i) was deposited on the first electrode 101 by a deposition method using resistance heating. 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) By co-evaporating DBT3P-II and molybdenum oxide (VI), An implantation layer 111 was formed. The thickness of the implantation layer was set to 40 nm. The weight ratio of DBT3P-II to molybdenum oxide was adjusted to 4:2 (=DBT3P-II:molybdenum oxide). The co-evaporation method is a method of simultaneously evaporating from multiple evaporation sources in one processing chamber. It is law.

[0191] Next, on the hole injection layer 111, 4-phenyl-4'-( 9-Phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP) for 20 The hole transport layer 112 was formed to a thickness of 100 nm.

[0192] Furthermore, on the hole transport layer 112, 2-[3-(dibenzo Thiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBT PDBq-II) and 4-phenyl-4'-(9-phenyl) represented by the above structural formula (iv). (9H-carbazol-3-yl)triphenylamine (abbreviation: PCBA1BP) Bis(2,3,5-triphenylpyrazine)(dipivaloy) represented by the above structural formula (v) Iridium(III) (abbreviation: [Ir(tppr)2(dpm)]) (3)) in a weight ratio of 0.5:0.5:0.05 (=2mDBTPDBq-II:PC BA1BP:[Ir(tppr)2(dpm)]) was co-evaporated to a thickness of 10 nm, and the third After preparing the light-emitting layer 113R, 2mDBTPDBq-II, PCBA1BP, and the above structure were mixed. (Acetylacetonato)bis(6-tert-butyl-4-phenyl)phenyl having the formula (vi) Rupyrimidinato)iridium(III) (abbreviation: [Ir(tBuppm)2(acac) ]) (compound (2)) in a weight ratio of 0.5:0.5:0.05 (=2mDBTPDBq -II: PCBA1BP: [Ir(tBuppm)2(acac)]), 5 nm thick, to form a second light-emitting layer 113G, and further to form a layer represented by the above structural formula (vii). 3,5-bis[3-(9H-carbazol-9-yl)phenyl]pyridine (abbreviation: 3 5DCzPPy) and 3,3'-bis(9-phenyl- 9H-carbazole) (abbreviation: PCCP) and 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) (compound (1)) in a weight ratio of 0.5:0.5:0 .06(=35DCzPPy:PCCP:[Ir(mpptz-dmp)3]) As shown in the figure, the first light-emitting layer 113B was formed to a thickness of 30 nm by co-evaporation, and the light-emitting layer 113 was formed.

[0193] In addition, 2mDBTPDBq-II and PCBA1BP, 35DCzPPy and PCCP Furthermore, 2mDBTPDBq-II has electron transport properties and BA1BP has hole transport properties, and by including these in a ratio of 0.5:0.5, Therefore, the second light-emitting layer 113G and the third light-emitting layer 113R have hole transport properties. In addition, 35DCzPPy has electron transport properties, and PCCP has hole transport properties. By incorporating these in a ratio of 0.5:0.5, the first light-emitting layer 113B becomes an electron transport layer. It has become a gender.

[0194] Thereafter, 2-[3-(dibenzothiophene) -4-yl)phenyl]-1-phenyl-1H-benzimidazole (abbreviation: mDBTB Im-II) was formed into a film having a thickness of 10 nm, and further, Bathophenanthroline (abbreviation: BPhen) was deposited to a thickness of 20 nm and used for electron transport. A transfer layer 114 was formed.

[0195] After the electron transport layer 114 is formed, lithium fluoride (LiF) is then deposited to a thickness of 1 nm. Then, a second electrode 112 is deposited on the second conductive layer 111 so as to form an electron injection layer 115. 02, aluminum was evaporated to a film thickness of 200 nm, A light-emitting element 1 was produced.

[0196] In the above-mentioned deposition process, the deposition was all performed by a resistance heating method.

[0197] (Method of manufacturing light-emitting element 2) In the light-emitting element 2, the thickness of the second light-emitting layer 113G in the light-emitting element 1 is set to 10 nm. The other components were the same as those of the light-emitting element 1 and were fabricated by the same process.

[0198] The light-emitting element 1 and the light-emitting element 2 are placed in a glove box with a nitrogen atmosphere, and the light-emitting element is The process of sealing the element with a glass substrate to prevent it from being exposed to air (applying a sealant around the element, After heat treatment at 80°C for 1 hour during sealing, the reliability of these light-emitting devices was measured. The measurements were carried out at room temperature (atmosphere maintained at 25°C).

[0199] FIG. 17 shows the current density-luminance characteristics of the light-emitting element 1 and the light-emitting element 2, and FIG. 18 shows the luminance-current efficiency characteristics of the light-emitting element 1 and the light-emitting element 2. 8, voltage-luminance characteristics are shown in Fig. 19, luminance-chromaticity characteristics are shown in Fig. 20, and luminance-power efficiency characteristics are shown in Fig. FIG. 21 shows the luminance-external quantum efficiency characteristics, and FIG. 22 shows the emission spectrum.

[0200] As described above, the light-emitting element 1 has a practical luminance of 1000 cd / m 2 Current efficiency around 47 cd / A, external quantum efficiency 22%, and power efficiency 32lm / W. The light color is 2930K, which is the color of a warm bulb, and the average color rendering index Ra is 91.7. It was also found that the light-emitting element 2 exhibited good color rendering properties. 2 Attached Very high current efficiency of 52cd / A, external quantum efficiency of 22%, and power efficiency of 36lm / W. It is to be noted that the efficiency of the light-emitting element according to one embodiment of the present invention is excellent. It can also be seen that the light-emitting element 1 and the light-emitting element 2 have a feature that the luminance dependency of the chromaticity is small.

[0201] In addition, the recombination regions of the carriers in the light-emitting element 1 and the light-emitting element 2 are the first light-emitting element due to the transport properties of each light-emitting layer. The area near the interface between the first light-emitting layer 113B and the second light-emitting layer 113G is Both the light-emitting element 1 in which the second light-emitting layer 113G is 5 nm and the light-emitting element 2 in which the second light-emitting layer 113G is 10 nm The third light-emitting layer 113R emits sufficient light. The light from the luminescent material contained in each of the three luminescent layers 113R is clearly visible in the spectrum. This indicates that the excitation energy is transferred efficiently and in a well-balanced manner. EXAMPLES

[0202] In this example, a light-emitting element (light-emitting element) according to one embodiment of the present invention having a different structure from that in Example 1 The light-emitting device 3 is made of the second compound [Ir(t Instead of [Buppm)2(acac)], a phosphorescent compound with a yellow emission color was Compound (4) (bis{2-[5-methyl-6-(2-methylphenyl)-4-pyrimidinyl -κN3]phenyl-κC}(2,4-pentanedionato-κ 2 O,O') Iridium ( III) (abbreviation: [Ir(mpmppm)2(acac)]) Other materials used in the light-emitting element 3 are the same as those in the light-emitting element 1 and the light-emitting element 2 in Example 1. The same material as that of the light-emitting element 2 was used.

[0203] The structural formula of compound (4) ([Ir(mpmppm)2(acac)]) is shown below. Other compounds are omitted since they are shown in Example 1.

[0204] [ka]

[0205] Here, the emission wavelength F(λ) of each of the three phosphorescent compounds used in the light-emitting element 3 is ) and ε(λ)λ of compound (3) and compound (4) 4 The relationship is shown in FIG. In the light emitting device of this embodiment, as shown in FIG. 24, the first light emitting layer 113B emits blue light. The second light-emitting layer 11 contains a compound (1) which is a first phosphorescent compound having a phosphorescent property. 3G exhibits longer wavelength emission (peak emission wavelength 566 nm) than the first phosphorescent compound. And ε(λ)λ 4 The maximum value A on the longest wavelength side of the function expressed by is 440n A second phosphorescent compound having a wavelength in the range of m to 520 nm (512 nm) (compound (4 The third light-emitting layer 113R contains a phosphorescent compound having a longer wavelength than the second phosphorescent compound. It emits light and ε(λ) 4 The maximum value B on the longest wavelength side of the function expressed by A third phosphorescent compound having a wavelength in the range of 20 nm to 600 nm (approximately 542 nm). Compound (3) is included. Also, as shown in FIG. 24, the maximum value B is closer to the maximum value A than the maximum value B. We can also see the relationship between

[0206] A method for fabricating the light emitting device 3 of this example will be described below.

[0207] (Method of Manufacturing Light-Emitting Element 3) First, indium tin oxide containing silicon oxide (ITSO) was sputtered onto a glass substrate. The first electrode 101 was formed by a deposition method. The area was set to 2 mm×2 mm. Here, the first electrode 101 functions as an anode of the light-emitting element. It is an electrode that

[0208] Next, as a pretreatment for forming a light emitting element on the substrate, the substrate surface was washed with water and then dried for 200 After baking at ℃ for 1 hour, UV ozone treatment was performed for 370 seconds.

[0209] Then, 10 -4 The substrate is placed in a vacuum deposition apparatus whose inside has been reduced in pressure to about Pa, and vacuum deposition is performed. 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.

[0210] 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 installed in a vacuum deposition apparatus and was heated for 10 -4 Reduced to about Pa After pressing, a film represented by the above structural formula (i) was deposited on the first electrode 101 by a deposition method using resistance heating. 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) By co-evaporating DBT3P-II and molybdenum oxide (VI), An implantation layer 111 was formed. The thickness of the implantation layer was set to 40 nm. The weight ratio of DBT3P-II to molybdenum oxide was adjusted to 4:2 (=DBT3P-II:molybdenum oxide). The co-evaporation method is a method of simultaneously evaporating from multiple evaporation sources in one processing chamber. It is law.

[0211] Next, on the hole injection layer 111, 4-phenyl-4'-( 9-Phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP) for 20 The hole transport layer 112 was formed to a thickness of 100 nm.

[0212] Furthermore, on the hole transport layer 112, 2-[3-(dibenzo Thiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBT PDBq-II) and 4-phenyl-4'-(9-phenyl) represented by the above structural formula (iv). (9H-carbazol-3-yl)triphenylamine (abbreviation: PCBA1BP) Bis(2,3,5-triphenylpyrazine)(dipivaloy) represented by the above structural formula (v) Iridium(III) (abbreviation: [Ir(tppr)2(dpm)]) (3)) in a weight ratio of 0.5:0.5:0.05 (=2mDBTPDBq-II:PC BA1BP:[Ir(tppr)2(dpm)]) was co-evaporated to 20 nm, and the third After preparing the light-emitting layer 113R, 2mDBTPDBq-II, PCBA1BP, and the above structure were mixed. Bis{2-[5-methyl-6-(2-methylphenyl)-4-pyridinyl]-2-phenylpropanediol represented by formula (xii) Rimidinyl-κN3]phenyl-κC}(2,4-pentanedionato-κ 2 O,O')I Lithium(III) (abbreviation: [Ir(mpmppm)2(acac)]) (compound (4) ) in a weight ratio of 0.5:0.5:0.05 (=2mDBTPDBq-II:PCBA1 BP: [Ir(mpmppm)2(acac)]) was co-evaporated to a thickness of 5 nm, and the second The light-emitting layer 113G is formed by adding 3,5-bis[3 -(9H-carbazol-9-yl)phenyl]pyridine (abbreviation: 35DCzPPy) 3,3'-bis(9-phenyl-9H-carbazole) represented by the above structural formula (viii) ) (abbreviation: PCCP) and tris{2-[5-(2-methylphenyl)-2-phenylpropanediol represented by the above structural formula (ix) Phenyl)-4-(2,6-dimethylphenyl)-4H-1,2,4-triazole-3 {Ir(mpptz- dmp)3]) (compound (1)) in a weight ratio of 0.5:0.5:0.06 (=35DC zPPy:PCCP:[Ir(mpptz-dmp)3]) was co-evaporated to 30 nm. Then, the first light-emitting layer 113B was formed, and the light-emitting layer 113 was formed.

[0213] In addition, 2mDBTPDBq-II and PCBA1BP, 35DCzPPy and PCCP Furthermore, 2mDBTPDBq-II has electron transport properties and BA1BP has hole transport properties, but in the light-emitting layer, these are mixed at a ratio of 0.5:0.5. By including the compound, the second light-emitting layer 113G and the third light-emitting layer 113R have hole transport properties. In addition, 35DCzPPy has electron transport properties, and PCCP has hole transport properties. However, these are contained in the light-emitting layer in a ratio of 0.5:0.5. This gives the first light-emitting layer 113B an electron transporting property.

[0214] Thereafter, 2-[3-(dibenzothiophene) -4-yl)phenyl]-1-phenyl-1H-benzimidazole (abbreviation: mDBTB Im-II) was formed into a film having a thickness of 10 nm, and further, Bathophenanthroline (abbreviation: BPhen) was deposited to a thickness of 20 nm and used for electron transport. A transfer layer 114 was formed.

[0215] After the electron transport layer 114 is formed, lithium fluoride (LiF) is then deposited to a thickness of 1 nm. Then, a second electrode 112 is deposited on the second conductive layer 111 so as to form an electron injection layer 115. 02, aluminum was evaporated to a film thickness of 200 nm, A light-emitting element 3 was fabricated.

[0216] In the above-mentioned deposition process, the deposition was all performed by a resistance heating method.

[0217] The light emitting element 3 is placed in a glove box with a nitrogen atmosphere so that the light emitting element is not exposed to the atmosphere. The process of sealing the element with a glass substrate (sealing material is applied around the element and the temperature is kept at 80℃ during sealing) After performing a heat treatment at 400 K for 1 hour, the reliability of these light-emitting devices was measured. The measurements were carried out at room temperature (atmosphere maintained at 25°C).

[0218] FIG. 25 shows the current density-luminance characteristics of the light-emitting element 3, FIG. 26 shows the luminance-current efficiency characteristics, and FIG. 27 shows the luminance vs. chromaticity characteristics, FIG. 28 shows the luminance vs. power efficiency characteristics, and FIG. The external quantum efficiency characteristics are shown in FIG. 30, and the emission spectrum is shown in FIG.

[0219] As described above, the light-emitting element 3 has a practical luminance of 1000 cd / m 2 Current efficiency around 48 cd / A, external quantum efficiency 23%, and power efficiency 32lm / W. The emitted color is 3860K white light, and the average color rendering index Ra is 85.1. It was also found that the light-emitting element according to one embodiment of the present invention had good color rendering properties. It can also be seen that the light-emitting element 3 has a feature that the luminance dependency of chromaticity is small.

[0220] In addition, the recombination region of the carriers in the light-emitting element 3 is the first light-emitting layer 113 due to the transport properties of each light-emitting layer. B and the vicinity of the interface between the second light-emitting layer 113G, but the third light-emitting layer 113R does not emit light sufficiently. In addition, the luminescent materials contained in each of the first light-emitting layer 113B to the third light-emitting layer 113R are Since the light from the photoluminescent material is clearly visible in the spectrum, the light-emitting element 3 is It can be seen that the energy transfer is efficient and well-balanced. EXAMPLES

[0221] Example 2 In this example, a light-emitting element according to one embodiment of the present invention having a different structure from those in Examples 1 and 2 is The light-emitting element 4 will be described. The light-emitting element 4 is the same as the light-emitting element of Example 1 except that the BPAFLP and P Instead of CBA1BP, 4,4'-di(1-naphthyl) )-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation PCBNBB) as a substitute for part of 35DCzPPy and 2mDBTPDBq-II The compound represented by the following structural formula (xiv) is 2-[3'-(dibenzothiophen-4-yl)biphenyl] phenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-I I) was used. The phosphorescent compound contained in each light-emitting layer was the same as in Example 1. Therefore, the emission wavelength F(λ) and ε(λ) 4 The relationship is the same as in the first embodiment.

[0222] The structural formulas of PCBNBB and 2mDBTBPDBq-II are shown below. The details are omitted since they are the same as those used in Example 1. Please refer to Example 1. .

[0223] [ka]

[0224] A method for fabricating the light-emitting device 4 of this example will be described below.

[0225] (Method of manufacturing light-emitting element 4) First, indium tin oxide containing silicon oxide (ITSO) was sputtered onto a glass substrate. The first electrode 101 was formed by a deposition method. The area was set to 2 mm×2 mm. Here, the first electrode 101 functions as an anode of the light-emitting element. It is an electrode that

[0226] Next, as a pretreatment for forming a light emitting element on the substrate, the substrate surface was washed with water and then dried for 200 After baking at ℃ for 1 hour, UV ozone treatment was performed for 370 seconds.

[0227] Then, 10 -4 The substrate is placed in a vacuum deposition apparatus whose inside has been reduced in pressure to about Pa, and vacuum deposition is performed. 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.

[0228] 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 installed in a vacuum deposition apparatus and was heated for 10 -4 Reduced to about Pa After pressing, a film represented by the above structural formula (i) was deposited on the first electrode 101 by a deposition method using resistance heating. 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) By co-evaporating DBT3P-II and molybdenum oxide (VI), An implantation layer 111 was formed. The thickness of the implantation layer was set to 40 nm. The weight ratio of DBT3P-II to molybdenum oxide was adjusted to 4:2 (=DBT3P-II:molybdenum oxide). The co-evaporation method is a method of simultaneously evaporating from multiple evaporation sources in one processing chamber. It is law.

[0229] Next, a film of PCBNBB was formed on the hole injection layer 111 to a thickness of 20 nm. A transport layer 112 was formed.

[0230] Further, on the hole transport layer 112, 2mDBTBPDBq-II, PCBNBB, and [I r(tppr)2(dpm)] in a weight ratio of 0.5:0.5:0.05 (=2mDBTB PDBq-II: PCBNBB: [Ir(tppr)2(dpm)]) After co-evaporating 113R, the third emitting layer 113R was formed, and then 2mDBTBPDBq-II and PC BNBB and [Ir(tBuppm)2(acac)] were mixed in a weight ratio of 0.5:0.5:0. .05(=2mDBTBPDBq-II:PCBNBB:[Ir(tBuppm)2(a cac)) to form a second light-emitting layer 113G, , 35DCzPPy, PCCP, and [Ir(mpptz-dmp)3] were mixed in a weight ratio of 0. 7:0.3:0.06(=35DCzPPy:PCCP:[Ir(mpptz-dmp) 3]), a 30 nm thick first light-emitting layer 113B is formed by co-evaporation, and a light-emitting layer 113 is formed. Successful.

[0231] In addition, 2mDBTBPDBq-II and PCBNBB, 35DCzPPy and PCCP are Furthermore, 2mDBTBPDBq-II has electron transport properties and CBNBB has hole transport properties, but in the light-emitting layer, they are mixed at a ratio of 0.5:0.5. By including the compound, the second light-emitting layer 113G and the third light-emitting layer 113R have hole transport properties. In addition, 35DCzPPy has electron transport properties, and PCCP has hole transport properties. However, these are contained in the light-emitting layer in a ratio of 0.5:0.5. This gives the first light-emitting layer 113B an electron transporting property.

[0232] Thereafter, a film of 35DCzPPy was formed on the light-emitting layer 113 to a thickness of 10 nm. Then, BPhen was deposited to a thickness of 20 nm to form the electron transport layer 114 .

[0233] After the electron transport layer 114 is formed, lithium fluoride (LiF) is then deposited to a thickness of 1 nm. Then, a second electrode 112 is deposited on the second electrode 113 so as to function as a cathode. 02, aluminum was evaporated to a film thickness of 200 nm, A light-emitting element 4 was fabricated.

[0234] In the above-mentioned deposition process, the deposition was all performed by a resistance heating method.

[0235] The light emitting element 4 is placed in a glove box with a nitrogen atmosphere so that the light emitting element is not exposed to the atmosphere. The process of sealing the element with a glass substrate (sealing material is applied around the element and the temperature is kept at 80℃ during sealing) After performing a heat treatment at 400 K for 1 hour, the reliability of these light-emitting devices was measured. The measurements were carried out at room temperature (atmosphere maintained at 25°C).

[0236] FIG. 32 shows the current density-luminance characteristics of the light-emitting element 4, FIG. 33 shows the luminance-current efficiency characteristics, and FIG. The luminance vs. chromaticity characteristics are shown in Fig. 34, the luminance vs. power efficiency characteristics in Fig. 35, and the luminance vs. The external quantum efficiency characteristics are shown in FIG. 37, and the emission spectrum is shown in FIG.

[0237] As described above, the light-emitting element 4 has a practical luminance of 1000 cd / m 2 Current efficiency around 39 It was found to have good characteristics of cd / A, external quantum efficiency of 21%, and power efficiency of 29lm / W. In addition, the light emission color is 2260K, and the average color rendering index Ra is 93.4, which is a good color rendering performance. I also understood that it is necessary to show

[0238] In addition, the recombination region of the carriers in the light-emitting element 4 is the first light-emitting layer 113 due to the transport properties of each light-emitting layer. B and the vicinity of the interface between the second light-emitting layer 113G, but the third light-emitting layer 113R does not emit light sufficiently. In addition, the luminescent materials contained in each of the first light-emitting layer 113B to the third light-emitting layer 113R are The light from the photoactive material is clearly visible in the spectrum, indicating that excitation energy transfer is occurring. This shows that the implementation is efficient and well-balanced.

[0239] Next, a reliability test was carried out. The reliability test was carried out at an initial brightness of 3000 cd / m 2 , current density - Under certain conditions, the initial brightness is set to 100% and the change in brightness over time is measured. The results are shown in Figure 39. As can be seen from the figure, all the light emitted from each light-emitting layer was phosphorescence. Even though it is an all-phosphorescent device, it still retains 65% of its initial brightness after 440 hours. Therefore, the light-emitting element 4 according to one embodiment of the present invention is a light-emitting element having good durability. I found out that...

[0240] (Reference example 1) The organometallic complex used in the above embodiment, tris{2-[5-(2-methylphenyl)- 4-(2,6-dimethylphenyl)-4H-1,2,4-triazol-3-yl-κN 2]Phenyl-κC}iridium(III) (abbreviation: [Ir(mpptz-dmp)3] The synthesis method of [Ir(mpptz-dmp)3] (abbreviation) is explained below. The structure is shown below.

[0241] [ka]

[0242] <Step 1; 3-(2-methylphenyl)-4-(2,6-dimethylphenyl)-5- Synthesis of phenyl-4H-1,2,4-triazole (abbreviation: Hmpptz-dmp) First, N-[1-chloro-1-(2-methylphenyl)methylidene]-N'-[1-chloro 12.6 g (43.3 mmol) of 2,4-dihydro-(1-phenyl)methylidenehydrazine 6-Dimethylaniline 15.7g (134.5mmol), N,N-Dimethylaniline 1 00ml was placed in a 500ml eggplant flask and heated and stirred at 120℃ for 20 hours. After the reaction, the reaction solution was slowly added to 200 ml of 1N hydrochloric acid. The organic layer was then washed with water and an aqueous solution of sodium bicarbonate. The resulting mixture was washed with magnesium sulfate and dried over magnesium sulfate. The filtrate was concentrated to give a black liquid. The developing solvent was ethyl acetate:hexane = 1:5. The solution was concentrated to give a white solid. This solid was recrystallized from ethyl acetate to give Hmppt Z-DMP was obtained as a white solid (4.5 g, 31% yield). The synthesis scheme for step 1 is shown below. As shown in.

[0243] [ka]

[0244] Step 2: Tris{2-[5-(2-methylphenyl)-4-(2,6-dimethylphenyl) phenyl)-4H-1,2,4-triazol-3-yl-κN2]phenyl-κC}yl Synthesis of Ir(mpptz-dmp)3 (abbreviation: Ir(mpptz-dmp)3) 2.5 g (7.4 mmol) of the ligand Hmpptz-dmp obtained in step 1 above, tri 0.7g (1.5mmol) of bis(acetylacetonato)iridium(III) was heated at high temperature. The reaction vessel was then heated at 250° C. for 48 hours while Ar was flowing inside. After the reaction for a certain period of time, the solid obtained was washed with dichloromethane, and the green insoluble matter was removed. The solid was obtained by suction filtration. The solid was dissolved in toluene and stacked on alumina and celite. The resulting fraction was concentrated to give a green solid. The phosphorescent organometallic iridium complex [Ir(mpptz-dmp)3]( The green powder (abbreviation) was obtained in 0.8 g with a yield of 45%. The synthesis scheme of step 2 is shown below. vinegar.

[0245] [ka]

[0246] The green powder obtained in step 2 was analyzed by nuclear magnetic resonance spectroscopy ( 1 H-NMR The analytical results are shown below. From these results, it was confirmed that the organometallic complex, Ir(mpp It was found that tz-dmp3 (abbreviation) was obtained.

[0247] 1 H-NMR.δ(toluene-d8):1.82(s,3H),1.90(s, 3H),2.64(s,3H),6.56-6.62(m,3H),6.67-6.75 (m,3H),6.82-6.88(m,1H),6.91-6.97(t,1H),7 .00-7.12(m,2H),7.63-7.67(d,1H).

[0248] (Reference example 2) The organometallic complex used in the above embodiment, (acetylacetonato)bis(6-tert-butyl) Bis[2-(6-ethyl-4-phenylpyrimidinato]iridium(III) rt-Butyl-4-pyrimidinyl-κN3)phenyl-κC](2,4-pentanediona To-κ 2 O,O') Iridium(III) (abbreviation: [Ir(tBuppm)2(aca The synthesis example of [Ir(tBuppm)2(acac)] is shown below. As shown in.

[0249] [ka]

[0250] <Step 1: 4-tert-butyl-6-phenylpyrimidine (abbreviation: HtBuppm Synthesis of First, 22.5 g of 4,4-dimethyl-1-phenylpentane-1,3-dione and formaldehyde were 50 g of mide was placed in a recovery flask equipped with a reflux condenser, and the inside of the flask was replaced with nitrogen. The reaction solution was refluxed for 5 hours by heating. Then, the solution was diluted with sodium hydroxide solution. The organic layer was extracted with dichloromethane. The organic layer was washed with water and saturated saline. The solution was washed and dried over magnesium sulfate. The solution after drying was filtered. After removing the solvent, the residue was dissolved in hexane and ethyl acetate (volume ratio: 10:1) and The pyrimidine derivative HtBupp was purified by silica gel column chromatography using a solvent. m was obtained (colorless oil, yield 14%). The synthetic scheme of step 1 is shown below.

[0251] [ka]

[0252] <Step 2: Di-μ-chloro-bis[bis(6-tert-butyl-4-phenylpyridine] Synthesis of [midinato)iridium(III)] (abbreviation: [Ir(tBuppm)2Cl]2) > Next, 15 mL of 2-ethoxyethanol, 5 mL of water, and the HtBupp obtained in step 1 above were added. 1.49 g of m and 1.04 g of iridium chloride hydrate (IrCl3·H2O) were The flask was then filled with argon gas. The mixture was irradiated with a 5 GHz 100 W power source for 1 hour to cause a reaction. After the solvent was removed by distillation, the resulting residue was The binuclear complex [Ir(tBuppm)2Cl]2 was obtained by suction filtration and washing with ethanol (yellow). Green powder, 73% yield. The synthesis scheme for step 2 is shown below.

[0253] [ka]

[0254] <Step 3; (acetylacetonato)bis(6-tert-butyl-4-phenylpyridine) Iridium(III) (abbreviation: [Ir(tBuppm)2(acac)] > Furthermore, 40 mL of 2-ethoxyethanol and the binuclear complex [Ir(tB uppm)2Cl]21.61 g, acetylacetone 0.36 g, sodium carbonate 1. 27 g was placed in a recovery flask equipped with a reflux condenser, and the atmosphere in the flask was replaced with argon. The mixture was then irradiated with microwaves (2.45 GHz, 120 W) for 60 minutes to react. The solvent was removed by distillation. The resulting residue was filtered with ethanol and washed with water and ethanol. Dissolve in chloromethane and filter with Celite (Wako Pure Chemical Industries, Ltd., Catalog No. 531-1 The mixture was filtered through a filter aid consisting of a layer of 6855), alumina, and celite in that order. The solid obtained by removing the residue was recrystallized in a mixed solvent of dichloromethane and hexane to give The target product was obtained as a yellow powder (yield 68%). The synthesis scheme of step 3 is shown below.

[0255] [ka]

[0256] Nuclear magnetic resonance spectroscopy of the yellow powder obtained in step 3 above ( 1 H NMR Analysis Results The results are shown below. From these results, the organometallic complex Ir(tBuppm)2(acac) was obtained. It was found that this was the case.

[0257] 1 H NMR.δ(CDCl3):1.50(s,18H),1.79(s,6H), 5.26(s,1H),6.33(d,2H),6.77(t,2H),6.85(t, 2H),7.70(d,2H),7.76(s,2H),9.02(s,2H). [Explanation of symbols]

[0258] 10 electrodes 11 electrodes 101 First electrode 102 Second electrode 103 EL layer 111 Hole injection layer 112 Hole transport layer 113 Light-emitting layer 113B First light-emitting layer 113Bd The first phosphorescent compound 113Bh First host material 113G Second light-emitting layer 113Gd Second phosphorescent compound 113Gh Second host material 113R Third luminescent layer 113Rd The third phosphorescent compound 113Rh Third host material 113ex recombination area 114 Electron transport layer 115 Electron injection layer 400 Substrates 401 First electrode 402 Auxiliary electrode 403 EL layer 404 Second electrode 405 Sealing material 406 Sealing material 407 Sealing substrate 412 Pad 420 IC chip 601 Driver circuit section (source line driver circuit) 602 Pixel section 603 Drive circuit section (gate line drive circuit) 604 Sealing substrate 605 Sealing material 607 Space 608 Wiring 609 FPC (Flexible Printed Circuit) 610 Element Substrate 611 Switching TFT 612 Current Control TFT 613 First electrode 614 Insulation 616 EL layer 617 Second Electrode 618 Light-emitting element 623 n-channel TFT 624 p-channel TFT 625 Dry material 901 Case 902 Liquid crystal layer 903 Backlight unit 904 Case 905 Driver IC 906 Terminal 951 Board 952 Electrode 953 Insulation Layer 954 Partition layer 955 EL layer 956 Electrode 1001 Board 1002 Undercoat insulating film 1003 Gate insulating film 1006 Gate electrode 1007 Gate electrode 1008 Gate electrode 1020 First interlayer insulating film 1021 Second interlayer insulating film 1022 Electrode First electrode of 1024W light emitting element 1024R First electrode of light emitting element 1024G First electrode of light-emitting element 1024B First electrode of light emitting element 1025 Bulkhead 1028 Layer containing organic compounds 1029 Second electrode of light emitting element 1031 Sealing substrate 1032 Sealing material 1033 Transparent substrate 1034R Red color layer 1034G Green colored layer 1034B Blue colored layer 1035 Black layer (black matrix) 1036 Overcoat layer 1037 Third interlayer insulating film 1040 Pixel section 1041 Drive circuit section 1042 Periphery 1044W White light emission area 1044R Red light area 1044B Blue light emitting area 1044G Green light emitting area 2001 Case 2002 light source 3001 Lighting equipment 3002 Display device 5000 display 5001 display 5002 display 5003 display 5004 display 5005 display 7101 Case 7103 Display section 7105 Stand 7107 Display section 7109 Operation key 7110 Remote control device 7201 Main unit 7202 Case 7203 Display section 7204 Keyboard 7205 External connection port 7206 Pointing Device 7210 Second display unit 7301 Case 7302 Case 7303 Connection section 7304 Display section 7305 Display section 7306 Speaker section 7307 Recording medium insertion section 7308 LED Lamp 7309 Operation key 7310 Connection terminal 7311 Sensor 7400 Mobile Phone 7401 Case 7402 Display section 7403 Operation button 7404 External connection port 7405 Speaker 7406 Mike 9033 Fastener 9034 Switch 9035 Power Switch 9036 Switch 9038 Operation switch 9630 Case 9631 Display section 9631a Display section 9631b Display section 9632a Touch Panel Area 9632b Touch panel area 9633 Solar Cells 9634 Charge / discharge control circuit 9635 Battery 9636 DC-DC Converter 9637 Operation key 9638 Converter 9639 Button

Claims

1. A first light-emitting layer and a second light-emitting layer are disposed between a pair of electrodes, the first light-emitting layer comprises a first phosphorescent compound and a first host material; the second light-emitting layer comprises a second phosphorescent compound and a second host material; the first phosphorescent compound has an emission spectrum peak in a wavelength range of 520 nm to 600 nm; ε(λ)λ of the second phosphorescent compound ４ The function represented by the formula (1) has a maximum value in the wavelength range from 520 nm to 600 nm, λ represents the wavelength, ε(λ) represents the molar extinction coefficient of the light emitting element.

2. A first light-emitting layer and a second light-emitting layer are disposed between a pair of electrodes, the first light-emitting layer comprises a first phosphorescent compound and a first host material; the second light-emitting layer comprises a second phosphorescent compound and a second host material; the first phosphorescent compound has an emission spectrum peak in a wavelength range of 520 nm to 600 nm; ε(λ)λ of the second phosphorescent compound ４ The function represented by the formula (1) has a maximum value in the wavelength range from 520 nm to 600 nm, the second phosphorescent compound has an emission spectrum peak in a wavelength range of 600 nm to 700 nm; λ represents the wavelength, ε(λ) represents the molar extinction coefficient of the light emitting element.

3. A lighting device comprising the light-emitting element according to claim 1 or 2.

4. 3. A light emitting device comprising: the light emitting element according to claim 1; and means for controlling the light emitting element.

5. 3. A display device comprising the light-emitting element according to claim 1 or 2 in a display section, and means for controlling the light-emitting element.

6. 3. An electronic device comprising the light-emitting element according to claim 1.

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