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

Abstract

To provide a light-emitting element using a plurality of light emitting dopant, which has high light-emitting efficiency, and provide each of a light-emitting device, a light-emitting module, a light-emitting display device, an electronic apparatus, and an illuminating device, in which a power consumption is reduced by using the light-emitting element as mentioned.SOLUTION: By focusing on a Foerster mechanism as one of an intermolecular energy transfer mechanism, an energy transfer in the Foerster mechanism can be efficiently performed by overlapping a light emission wavelength of an energy giving side molecule and a peak having a local maximum on the longest wavelength side in a graph obtained by multiplying an absorption spectrum on the side of receiving energy by a wavelength to the fourth power.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 substance (EL layer) is sandwiched between a pair of electrodes. When a voltage is applied to this element, By this, it is possible to obtain light emission from the light emitting substance.

[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 lamps. Therefore, it is highly useful as a surface light source for lighting and other applications.

[0005] In the case of an organic EL element in which an organic compound is used as a light-emitting substance and the EL layer is provided between a pair of electrodes, By applying a voltage between a pair of electrodes, electrons are emitted from the cathode and holes are emitted from the anode. The electrons and holes are injected into the EL layer, causing a current to flow. The recombination causes the light-emitting organic compound to enter an excited state, and the excited light-emitting organic The compound can emit light.

[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 create multicolor light-emitting devices using dopants with different luminescent colors. In order to achieve high luminous efficiency, it is necessary for the dopants of each luminescent color to emit light in a well-balanced manner. It is not easy to achieve a high efficiency while also balancing the emission of each dopant.

[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 that overlaps with the Förster mechanism, The energy transfer is efficiently achieved in the conventional Energy transfer occurs not from the host to the dopant, but between the dopants. In this way, the efficiency of energy transfer between dopants is high. By applying a combination of dopants that achieves the desired effect, and by isolating each dopant molecule appropriately, By designing an element structure to achieve this, a light-emitting element of one embodiment of the present invention can be obtained.

[0016] That is, one embodiment of the present invention is a light-emitting device having a first phosphorescent compound and a first host A first light-emitting layer is dispersed in the material, and a second light-emitting layer is formed on the first phosphorescent compound, the second light-emitting layer having a longer wavelength than the first phosphorescent compound. a second light-emitting layer in which the second phosphorescent compound is dispersed in a second host material; ε(λ)λ of phosphorescent compounds 4 The wavelength of the maximum value on the longest wavelength side of the function expressed by It is a light-emitting element that overlaps with the phosphorescence emission spectrum F(λ) of the first phosphorescent compound. ε(λ) represents the molar absorption coefficient of each phosphorescent compound and is a function of wavelength λ.

[0017] In another embodiment of the present invention, a first phosphorescent compound is disposed between a pair of electrodes, A first light-emitting layer is dispersed in the material, and a second light-emitting layer is formed on the first phosphorescent compound, the second light-emitting layer having a longer wavelength than the first phosphorescent compound. a second light-emitting layer in which the first phosphorescent compound is dispersed in a second host material; The peak containing the maximum of the phosphorescence emission spectrum of the phosphorescent compound and the peak containing the second phosphorescent compound Compound ε(λ)λ 4 The peak containing the maximum value located on the longest wavelength side of the function represented by (where ε(λ) represents the molar absorption coefficient of each phosphorescent compound.) and a function of wavelength λ.)

[0018] In another embodiment of the present invention, in the above structure, the first light-emitting layer further comprises a first organic compound. The first host material and the first organic compound form an exciplex to form a first phosphorescent The compound emits light at a longer wavelength than the exciplex emits light.

[0019] Another embodiment of the present invention is a method for producing a compound semiconductor laser having the above structure, comprising: ε(λ)λ of phosphorescent compounds 4 The wavelength of the maximum value on the longest wavelength side of the function expressed by (where ε(λ) represents the molar absorption coefficient of each phosphorescent compound, A function of wavelength λ.)

[0020] Another embodiment of the present invention is a method for producing an exciplex having an emission spectrum with a maximum value of 100 nm, The peaks included and the ε(λ)λ of the first phosphorescent compound 4 Located on the longest wavelength side of the function expressed by The light-emitting element is one in which the peaks containing the maximum values ​​overlap each other. (Note that ε(λ) is the It represents the molar absorption coefficient of a photoactive compound as a function of wavelength λ.

[0021] In another embodiment of the present invention, in the above structure, the first phosphorescent compound is The second phosphorescent compound has a phosphorescence emission peak in the range of 600 nm to 600 nm. The phosphorescent light emitting element has an emission peak in the range of 500 nm to 700 nm.

[0022] Another embodiment of the present invention is a semiconductor device having the above structure, in which a recombination region of electrons and holes is a first light-emitting The light-emitting element is a layer.

[0023] Another embodiment of the present invention is a semiconductor device having the above structure, in which the first light-emitting layer is closer to the anode than the second light-emitting layer. At least the second light-emitting layer is a light-emitting element having a higher electron transporting property than a hole transporting property. He is a child.

[0024] Another embodiment of the present invention is a semiconductor device having the above structure, in which the first light-emitting layer is closer to the anode than the second light-emitting layer. the first host material and the second host material are both electron transporting materials. The material having electron transport properties is a material having a higher electron transport property than a hole transport property. A material with low

[0025] Another embodiment of the present invention is a semiconductor device having the above structure, in which the first light-emitting layer is closer to the cathode than the second light-emitting layer. At least the second light-emitting layer is a light-emitting element having a higher hole transporting property than an electron transporting property. He is a child.

[0026] Another embodiment of the present invention is a semiconductor device having the above structure, in which the first light-emitting layer is closer to the cathode than the second light-emitting layer. the first host material and the second host material are both hole transporting materials. In addition, the material having a hole transporting property is a material having a higher hole transporting property than an electron transporting property. A material with low resistance is preferred.

[0027] Another embodiment of the present invention is a semiconductor device having the above structure, in which the first light-emitting layer and the second light-emitting layer are The light emitting element is laminated in contact with the

[0028] 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.

[0029] 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 a wiring board or COG (Chip On Glass) type 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

[0030] 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]

[0031] [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] A diagram explaining the Förster transfer. [Figure 4] FIG. 1 is a conceptual diagram of an active matrix light-emitting device. [Diagram 5] FIG. 1 is a conceptual diagram of a passive matrix light-emitting device. [Figure 6] FIG. 1 is a conceptual diagram of an active matrix light-emitting device. [Figure 7] FIG. 1 is a conceptual diagram of an active matrix light-emitting device. [Figure 8] A conceptual diagram of a lighting device. [Figure 9] FIG. [Figure 10] FIG. [Figure 11] FIG. [Figure 12] 1A and 1B are diagrams illustrating a lighting device and a display device. [Figure 13] 1 is a diagram illustrating an in-vehicle display device and a lighting device. [Figure 14] A diagram showing an electronic device. [Figure 15] Luminance-current efficiency characteristics of light-emitting element 1. [Figure 16] Voltage-luminance characteristics of light-emitting element 1. [Figure 17] Luminance-external quantum efficiency characteristics of light-emitting element 1. [Figure 18] Luminance-power efficiency characteristics of light-emitting element 1. [Figure 19] Emission spectrum of light-emitting element 1. [Figure 20] 3A and 3B are diagrams for explaining the Forster movement of the light-emitting element 1. [Figure 21] 3A and 3B are diagrams for explaining the Forster movement of the light-emitting element 1. [Figure 22] 3A and 3B are diagrams for explaining the Forster movement of the light-emitting element 1. [Figure 23] PL spectra of 2mDBTPDBq-II, PCBA1BP and their mixed films. [Figure 24]Luminance-current efficiency characteristics of light-emitting element 2. [Diagram 25] Voltage-luminance characteristics of light-emitting element 2. [Figure 26] Luminance-external quantum efficiency characteristics of light-emitting element 2. [Figure 27] Luminance-power efficiency characteristics of light-emitting element 2. [Figure 28] Emission spectrum of light-emitting element 2. [Figure 29] FIG. 13 shows the results of a reliability test of the light-emitting element 2. [Diagram 30] Luminance-current efficiency characteristics of light-emitting element 3. [Diagram 31] Voltage-luminance characteristics of light-emitting element 3. [Diagram 32] Luminance-external quantum efficiency characteristics of light-emitting element 3. [Diagram 33] Luminance-power efficiency characteristics of light-emitting element 3. [Diagram 34] Emission spectrum of light-emitting element 3. [Diagram 35] Luminance-current efficiency characteristics of light-emitting element 4. [Diagram 36] Voltage-luminance characteristics of light-emitting element 4. [Figure 37] Luminance-external quantum efficiency characteristics of light-emitting element 4. [Figure 38] Luminance-power efficiency characteristics of light-emitting element 4. [Figure 39] Emission spectrum of light-emitting element 4. [Diagram 40] Luminance-current efficiency characteristics of light-emitting element 5. [Diagram 41] Voltage-luminance characteristics of light-emitting element 5. [Diagram 42] Luminance-external quantum efficiency characteristics of light-emitting element 5. [Diagram 43] Luminance-power efficiency characteristics of light-emitting element 5. [Diagram 44] Emission spectrum of light-emitting element 5. [Diagram 45] 4A to 4C are diagrams for explaining the Forster movement of the light-emitting element 4. [Figure 46] 4A to 4C are diagrams for explaining the Forster movement of the light-emitting element 4. [Figure 47] 4A to 4C are diagrams for explaining the Forster movement of the light-emitting element 5. [Figure 48] 4A to 4C are diagrams for explaining the Forster movement of the light-emitting element 5. [Figure 49] 4A to 4C are diagrams for explaining the Forster movement of the light-emitting element 5. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] 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.

[0033] (Embodiment 1) First, the principle of operation of a light-emitting element according to one embodiment of the present invention will be described. A phosphorescent compound and a second phosphorescent compound that emits light at a longer wavelength than the first phosphorescent compound. By using a compound, both the first phosphorescent compound and the second phosphorescent compound can be efficiently emitted. By doing so, a highly efficient multi-color light emitting device can be obtained.

[0034] 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.

[0035] 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.

[0036] On the other hand, in a light-emitting element according to one embodiment of the present invention, a first phosphorescent compound is disposed between a pair of electrodes. a first light-emitting layer having a first phosphorescent compound dispersed therein and a second phosphorescent compound having a longer wavelength than the first phosphorescent compound; A second light-emitting layer in which a second phosphorescent compound is dispersed in a second host material is laminated. In this case, the first light-emitting layer and the second light-emitting layer are mutually polarized, unlike the tandem structure. It may be provided adjacent to the surface.

[0037] 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.

[0038] 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 113a, a second light-emitting layer 113b, and The light-emitting layer 113 is a combination of the first phosphorescent compound 113Da and the second phosphorescent compound 1 Shown are a first host material 113Ha, a second host material 113Hb, and a second host material 113Db. In addition, in FIG. 1(b), the first light-emitting layer 113a further contains a first organic compound 113A. In either case, each phosphorescent compound (first and second Since the phosphorescent compounds are dispersed in the host material, each phosphorescent compound is The first and second host materials are separated from each other by the same material. The first light-emitting layer 113a and the second light-emitting layer 113b may be the same or different. Either side may be the anode side or the cathode side.

[0039] In this case, electron exchange interaction (the so-called Dexter mechanism) occurs between each phosphorescent compound. In other words, the first phosphorescent compound 113Da is excited After the excitation energy is transferred to the second phosphorescent compound 113Db via the Dexter mechanism, Therefore, the second phosphorescence, which shows the longest wavelength emission, can be prevented. The phenomenon that the photoactive compound 113Db mainly emits light can be suppressed. When excitons are generated directly in the light-emitting layer 113b, the second phosphorescent compound 113Db is mainly Therefore, the recombination region of the carriers is set within the first light emitting layer 113a (also That is, it is preferable that the first phosphorescent compound 113Da is mainly excited.

[0040] However, the energy transfer from the first phosphorescent compound 113Da was completely suppressed. If the second phosphorescent compound 113Db is used, the emission of the second phosphorescent compound 113Db cannot be obtained. In one embodiment of the invention, the excitation energy of the first phosphorescent compound 113Da is partially The device is designed to move the electrons from the electrons to the phosphorescent compound 113Db. Energy transfer between molecules is achieved by utilizing dipole-dipole interactions (Förster mechanism). This is possible by:

[0041] 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.

[0042] 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).

[0043]

number

[0044] 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.

[0045] 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).

[0046] Here, as described in FIG. 1, each phosphorescent compound (first and second phosphorescent compounds) The phosphorescent compounds are dispersed in the respective host materials, and the phosphorescent compounds are separated from each other by the respective host materials. Since they are separated, 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 via the Förster mechanism. On the other hand, when R is 1, the energy is not transferred to the second phosphorescent compound. Forster transfer is possible up to about 0 nm to 20 nm. In order to ensure a distance R of at least one molecule between phosphorescent compounds, It is preferable that the volume of each phosphorescent compound to be dispersed is set to a certain value or less. The concentration of the phosphorescent compound in the light-emitting layer is 10 wt % or less. If the concentration is too low, it is difficult to obtain good characteristics. The concentration of the first phosphorescent material is preferably 0.1 wt % or more and 10 wt % or less. The compound is contained in the first light-emitting layer 113a at a concentration of 0.1 wt % or more and 5 wt % or less. is more preferred.

[0047] A first phosphorescent compound 113Da and a phosphorescent compound having a longer wavelength than the first phosphorescent compound. Each phosphorescent element in a light-emitting element according to one embodiment of the present invention using the second phosphorescent compound 113Db A schematic diagram of Förster transfer between electrochemical compounds is shown in FIG. The first light-emitting layer 113a and the second light-emitting layer 113b are laminated between the electrodes 11. In addition, one of the electrodes 10 and 11 functions as an anode and the other functions as a cathode. As shown in FIG. 2(A), the first phosphorescent compound 113Da was used. The singlet excited state (S a ) can be converted to a triplet excited state (T a ) That is, the excitons in the first light-emitting layer 113a are essentially T a It is summarized as follows.

[0048] Next, this T aSome of the energy of the excitons in the phe- state is converted directly into light emission, but The triplet excitation of the second phosphorescent compound 113Db was partially achieved by utilizing the Luster mechanism. Waking state (T b This is because the first phosphorescent compound 113Da emits The second phosphorescent compound 113Db is a single-layer phosphorescent compound (having a high phosphorescence quantum yield φ). It has a direct absorption corresponding to the electronic transition from the triplet ground state to the triplet excited state (triplet excitation). If these conditions are met, then T a From T b triplet-triplet Förster transfer to

[0049] In addition, the singlet excited state (S b ) is the first phosphorescent The triplet excited state (T a ) 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. Of course, the singlet excited state (S b ) is the first phosphorescent The triplet excited state (T a ), if the energy is lower than In this case, the singlet excited state ( S b The energy transferred to the triplet state of the second phosphorescent compound 113Db undergoes intersystem crossing. Excited state (T b ) and is involved in light emission.

[0050] In addition, the above-mentioned Förster transfer can be efficiently generated between the phosphorescent compounds serving as dopants. In order to design the first and second host materials so that the energy is not transferred to the host material, The phosphorescent material does not have an absorption spectrum in the emission region of the first phosphorescent compound 113Da. In this way, it is preferable that the compound is not formed through a host material (specifically, a second host material). By directly transferring energy between dopants, the process of extra energy transfer is eliminated. This is a preferable configuration since it can suppress the occurrence of voids and lead to high light emission efficiency.

[0051] The first host material is preferably a material that is resistant to the first phosphorescent compound so as not to quench the first phosphorescent compound. It is preferred that the compound has a higher triplet excitation energy than the reactive compound.

[0052] As described above, the basic concept of one embodiment of the present invention is to firstly generate first and second phosphorescent The first laminate exhibits short wavelength emission while isolating the active compound using a host material and a laminate structure. The device structure is such that the phosphorescent compound is mainly excited. For the electrons, Förster-type energy transfer occurs within a certain distance (up to 20 nm). Since the excitation energy of the first phosphorescent compound is partially absorbed by the second phosphorescent compound, The mixture can be transferred to the first and second phosphorescent compounds, and light emission can be obtained from each of the first and second phosphorescent compounds.

[0053] 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.

[0054] 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 ) is increased, that is, 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.

[0055] 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.

[0056] 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.

[0057]

number

[0058] 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.

[0059] Therefore, as the second phosphorescent compound 113Db in the light-emitting element of one embodiment of the present invention, In order to increase the efficiency of energy transfer from the first phosphorescent compound 113Da, The spectral peak where the emission spectrum maximum of phosphorescent compound 113Da exists and the second Phosphorescent compound 113Db ε(λ)λ 4 The pole at the longest wavelength side of the function A phosphorescent compound is used that has overlapping peaks at which maximum values ​​exist.

[0060] The ε(λ)λ of the second phosphorescent compound 4 The pole at the longest wavelength side of the function The wavelength of the maximum value overlaps with the phosphorescence emission spectrum F(λ) of the first phosphorescent compound. In addition, the above maximum value in the emission spectrum of the first phosphorescent compound 113Da is preferably present. a wavelength range having an intensity half the maximum value of the peaks, and a second phosphorescent compound; ε(λ) 4 The function expressed by the formula If there is overlap in the wavelength ranges with intensity, the overlap between the spectra will be greater, preferable.

[0061] The light-emitting element having the above-mentioned structure has high light-emitting efficiency and has well-balanced phosphorus. A light-emitting element capable of obtaining light emission from a light-emitting compound can be obtained.

[0062] In order to deepen understanding of the structure of such phosphorescent compounds, a specific example will be used below. Here, the first phosphorescent compound 113Da is the following compound (1) (bis[ 2-(6-tert-butyl-4-pyrimidinyl-κN3)phenyl-κC](2,4- Pentanedionate-κ 2 O,O') Iridium(III) (abbreviation: Ir(tBuppm) 2(acac))) with a second phosphorescent compound that exhibits emission at a longer wavelength than the first phosphorescent compound 113Da. As the phosphorescent compound 113Db, the following compound (2) (bis(2,3,5-triphenylphosphine) Rupyrazinate)(dipivaloylmethanato)iridium(III) (abbreviation: Ir(tppr )2(dpm))) will be used as examples.

[0063] [ka]

[0064] 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 550 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 is the absorption band located at the longest wavelength side (triplet MLCT absorption It has a maximum value in the band.

[0065] 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 This 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 second phosphorescent compound. 4 Maximum of In the vicinity of ε(λ)λ 4 and the first phosphorescent compound has a large overlap with the second phosphorescent compound. Energy transfer occurs to the phosphorescent compound 2 via the Förster mechanism. , the maximum corresponds to the triplet MLCT absorption band, so that the triplet-triplet Förster type This is energy transfer (T in Figure 2). a -T b In this case, the first phosphorus The emission peak wavelength of the PL spectrum F(λ) of the phosphorescent compound and the ε( λ)λ 4 If the difference in wavelength between the maximum values ​​of the two is 0.2 eV or less, the energy transfer is efficient. This is a preferred configuration because the PL spectrum F(λ) of compound (1) has a peak emission wavelength of is 546 nm, and the ε(λ)λ of compound (2) 4 The wavelength of the maximum value of is 543 nm, and the difference is 3 nm corresponds to 0.01 eV. Therefore, the energy between compound (1) and compound (2) is Energy transfer is very efficient.

[0066] From the above, the second phosphorescent compound has a single phosphorescent element on the longest wavelength side of the absorption spectrum. Direct absorption corresponding to electronic transition from the singlet ground state to the triplet excited state (e.g., triplet ML It is preferable that the CT absorption is sufficient. By adopting such a configuration, as shown in FIG. Such triplet-triplet energy transfer occurs efficiently.

[0067] In order to obtain the recombination region described above, when the first light-emitting layer 113a is located on the anode side, At least the second light-emitting layer 113b preferably has an electron transporting property, and the first light-emitting layer 1 Both the first light-emitting layer 113a and the second light-emitting layer 113b may have electron transport properties. When 113a is located on the cathode side, at least the second light-emitting layer 113b has hole transport properties. It is preferable that both the first light-emitting layer 113a and the second light-emitting layer 113b have a hole-transporting property. It's fine.

[0068] Here, in the first light-emitting layer 113a, the first host material 113Ha is further The peak where the maximum value of PL spectrum F(λ) exists and the first phosphorescence peak Compound ε(λ)λ 4 The weight of the peaks at which the maximum value exists on the longest wavelength side of the function represented by It is preferable that the difference be large.

[0069] However, usually the photoluminescence (PL) spectrum F(λ) of the host material The peak at which the maximum value of ε(λ)λ of the guest material (first phosphorescent compound 113Da) is present. 4 It is difficult to overlap the peak where the maximum value is located on the longest wavelength side of the function represented by This is because the photoluminescence (PL) of the host material is usually fluorescence. Since fluorescence emission is emitted from a higher energy level than phosphorescence emission, the fluorescence spectrum The absorption spectrum of the guest material is close to the longest wavelength side (triplet excited state of the guest material). The triplet excitation energy level of the host material at a wavelength that This is because there is a high probability that the triplet excited energy level of the host material will be lower than the If the energy level of the guest material falls below the triplet excited energy level of the guest material, The triplet excitation energy of the luminescence element is transferred to the host material, resulting in a decrease in the luminescence efficiency. .

[0070] Therefore, in this embodiment, the first light-emitting layer 113a further contains the first organic compound 113 A first host material 113Ha and a first organic compound 113A form an exciplex 11 It is preferable that the combination forms 3Ec (also called exciplex) (Figure 1(b), FIG. 2(B). In FIG. 2(B), 10 and 11 are electrodes. One of the exciplexes 113E functions as an anode and the other as a cathode. The singlet excited state of c is represented by Se, and the triplet excited state is represented by Te. The singlet excited state of 3Da is represented by Sa, the triplet excited state is represented by Ta, and the second phosphorescent compound The singlet excited state of 113Db is represented by Sb, and the triplet excited state by Tb.

[0071] In this case, the first light-emitting layer 113a is recombined with the carriers (electrons and holes). The first organic compound 113A and the first host material 113Ha are converted into a compound by recombination of electrons and holes. When it obtains energy from the 113Ec complex, it forms the exciplex 113Ec. The light emission is a fluorescent spot of the first organic compound 113A alone and the first host material 113Ha alone. The emission spectrum is longer than the singlet of the exciplex 113Ec. The excited state Se and the triplet excited state Te have the characteristic that their energies are very close. Therefore, the PL spectrum F(λ) is the emission from the singlet excited state of the exciplex 113Ec. The peak at which the maximum value of ε(λ)λ of the guest material (first phosphorescent compound 113Da) is present. 4 The peak at which the maximum value is located on the longest wavelength side of the function expressed by By overlapping the spectrum with the absorption spectrum of the excited state Ta, the energy This maximizes both the energy transfer from Te to Ta and the energy transfer from Te to Ta. In this case, the emission peak wavelength of the exciplex 113Ec and the guest material (first phosphorescent compound 113 Da) ε(λ) 4 If the difference in wavelength between the maximum values ​​is less than 0.2 eV, the energy transfer is This is a preferable configuration because the reaction is efficiently performed. The triplet excited energy level of the host material 113Ha is It is preferable to keep the energy level above the triplet excited energy level.

[0072] The energy transferred to the first phosphorescent compound 113Da in the above manner is A portion of the phosphorescent compound 113Db is transferred to the second phosphorescent compound 113Da. and the second phosphorescent compound 113Db both emit light efficiently.

[0073] The triplet excited state (Te) of the exciplex 113Ec is converted into the first phosphorescent compound 113D. Energy transfer to the singlet excited state (Se The energy transfer from the nucleus to the nucleus occurs efficiently by the Förster mechanism in the above configuration. This allows for efficient energy transfer in a completely carbon-free environment.

[0074] The first organic compound 113A and the first host material 113Ha are each an exciplex generating compound. Any combination is acceptable, but a compound that easily accepts electrons (electron trapping compound) and It is preferable to combine the compound with a compound that easily receives holes (a hole-trapping compound). stomach.

[0075] Compounds that readily accept electrons include bis(10-hydroxybenzo[h]quinolinato ) Beryllium(II)(abbreviation: BeBq2), bis(2-methyl-8-quinolinolato)( 4-phenylphenolato)aluminum(III) (abbreviation: BAlq), bis(8-quinol linolato)zinc(II)(abbreviation:Znq), bis[2-(2-benzoxazolyl)phenyl] ZnPBO, bis[2-(2-benzothiazolyl)phenyl]phenyl zinc(II) (abbreviation: ZnBTZ) and other metal complexes, )-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: P BD), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl) 1,3-bis[5-(p-tert -butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OX D-7), 9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl 2,2',2''-(1,3,5-benzyl)-9H-carbazole (abbreviation: CO11), 1-phenyl-1H-benzimidazole (TPBI) ), 2-[3-(dibenzothiophen-4-yl)phenyl]-1-phenyl-1H-benzyl Complex compounds with polyazole skeletons such as benzoimidazole (abbreviation: mDBTBIm-II) Ring compounds and 2-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h ]quinoxaline (abbreviation: 2mDBTPDBq-II), 2-[3'-(dibenzothiophene [f,h]quinoxaline (abbreviation: 2mD BTBPDBq-II), 2-[3'-(9H-carbazol-9-yl)biphenyl- 3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzBPDBq), 4,6-bi 4,6mPnP2 Pm), 4,6-bis[3-(4-dibenzothienyl)phenyl]pyrimidine (abbreviation: 4 Heterocyclic compounds with diazine skeletons such as 3,5-diphenylphosphine (Pm-II) and 6mDBTP2Pm-II) 35DCzPP y), 1,3,5-tri[3-(3-pyridyl)-phenyl]benzene (abbreviation: TmPy Among the above, heterocyclic compounds having a pyridine skeleton such as diazidophenyl tert-butyl ether (PB) are preferred. Heterocyclic compounds having an isidine skeleton and heterocyclic compounds having a pyridine skeleton have good reliability. In particular, heterocyclic compounds having a diazine (pyrimidine or pyrazine) skeleton are preferred. It has high electron transport properties and also contributes to reducing the driving voltage.

[0076] Compounds that readily accept holes include 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: TP D) 4,4'-bis[N-(spiro-9,9'-bifluoren-2-yl)-N-phenyl 4-phenyl-4'-(9-phenylfuranylamino)biphenyl (abbreviation: BSPB), oren-9-yl)triphenylamine (abbreviation: BPAFLP), 4-phenyl-3'- (9-phenylfluoren-9-yl)triphenylamine (abbreviation: mBPAFLP), 4-Phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenyla 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 PCBANB, 4,4'-di(1-naphthyl)-4''-(9-phenyl -9H-carbazol-3-yl)triphenylamine (abbreviation: PCBNBB), 9,9 -Dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl] )phenyl]fluoren-2-amine (abbreviation: PCBAF), N-phenyl-N-[4- (9-phenyl-9H-carbazol-3-yl)phenyl]spiro-9,9'-bifluor Compounds with aromatic amine skeletons such as PCBASF (abbreviation: PCBASF), 1,3-Bis(N-carbazolyl)benzene (abbreviation: mCP), 4,4'-di(N-carbazolyl)benzene 3,6-bis(3,5-diphenylphenyl) -9-phenylcarbazole (abbreviation: CzTP), 3,3'-bis(9-phenyl-9H Compounds with a carbazole skeleton, such as PCCP (PCP-carbazole) and 4,4 ',4''-(Benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II), 2,8-diphenyl-4-[4-(9-phenyl-9H-fluorene 4-[phenyl-9-yl]phenyl]dibenzothiophene (abbreviation: DBTFLP-III), 4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzo Compounds with a thiophene skeleton, such as DBTFLP-IV, 4',4''-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviation: D BF3P-II), 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)fluor phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II) and other furan skeletons Among the above, compounds having an aromatic amine skeleton and Compounds having a rubazoline skeleton have good reliability, high hole transport properties, and excellent driving properties. This is preferable since it also contributes to voltage reduction.

[0077] The first organic compound 113A and the first host material 113Ha are not limited to these. This combination allows the formation of an exciplex without any need for a complex, and the photoluminescence (PL ) The peak at which the maximum value of the spectrum F(λ) exists and the ε(λ)λ of the first phosphorescent compound 4 in The peak at the longest wavelength of the function represented by the luminescence of the exciplex overlaps with the peak at the longest wavelength of the function represented by the luminescence of the exciplex. The peak of the spectrum is closer to the peak of the emission spectrum of the first phosphorescent compound 113Da. It is sufficient that the wavelength of the light is long.

[0078] The first organic compound is a compound that easily accepts electrons and a compound that easily accepts holes. When the first host material 113A and the first host material 113Ha are formed, the carrier Specifically, the first organic compound 113A and the first pho The ratio of the stock material 113Ha is preferably in the range of 1:9 to 9:1.

[0079] In this configuration, the polarity of the photoluminescence (PL) spectrum F(λ) of the exciplex is The peak where the maximum value exists and the ε(λ)λ of the first phosphorescent compound 4 The longest wavelength of the function expressed by The first host material 1 is a material that forms an exciplex in which the peaks with the maximum values ​​located on the side of the first host material 1 overlap each other. 13Ha and the first organic compound 113A. The larger the overlap of these peaks, the more preferable. stomach.

[0080] The ε(λ)λ of the first phosphorescent compound 4 The pole at the longest wavelength side of the function The wavelength of the maximum value overlaps with the photoluminescence (PL) spectrum F(λ) of the exciplex. It is preferable that the photoluminescence (PL) spectrum F(λ ) a wavelength range having half the intensity of the maximum value at the peak where the maximum value exists, and a first ε(λ)λ of phosphorescent compounds 4 The maximum value of the function expressed by If there is an overlap in the wavelength range where the intensity is half the value, the spectra will overlap more. This is more preferable.

[0081] In this configuration, the excitation light emitting element 113 is made of a first host material 113Ha and a first organic compound 113A. It is possible to efficiently transfer energy from the phosphorescent complex to the first phosphorescent compound 113Da. This allows for a higher energy transfer efficiency, which further increases the external quantum A highly efficient light emitting element can be realized.

[0082] (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.

[0083] 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.

[0084] 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.

[0085] 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 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.

[0086] The hole injection layer 111 is a layer containing a substance with high hole injection properties. Use of zinc oxide, ruthenium oxide, 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 .

[0087] 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.

[0088] 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.

[0089] 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.

[0090] 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.

[0091] 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.

[0092] 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

[0093] 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.

[0094] 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.

[0095] 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.

[0096] 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.

[0097] The light-emitting layer 113 is a layer including a first phosphorescent compound and a second phosphorescent compound. Since the optical layer 113 has the configuration as described in the first embodiment, The light-emitting element in the light-emitting layer 113 can be a light-emitting element with very good light-emitting efficiency. For the main configuration, please refer to the description of embodiment 1.

[0098] In the light-emitting layer 113, the first phosphorescent compound and the second phosphorescent compound are The materials that can be used are combinations having the relationship described in the first embodiment. As long as the first phosphorescent compound and the second phosphorescent compound are not particularly limited, they may be, for example, , some of which include the following:

[0099] 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), tris(5-methyl-3,4-diphenyl -4H-1,2,4-triazolato)iridium(III) (abbreviation: Ir(Mptz)3 ), tris[4-(3-biphenyl)-5-isopropyl-3-phenyl-4H-1,2 ,4-Triazolate]iridium(III) (abbreviation: Ir(iPrptz-3b)3) Organometallic iridium complexes with 4H-triazole skeletons such as tris[3-methyl -1-(2-methylphenyl)-5-phenyl-1H-1,2,4-triazolato]yl Ir(Mptz1-mp)3, tris(1-methyl-5-fluorouracil (phenyl-3-propyl-1H-1,2,4-triazolato)iridium(III) (abbreviation Organometallic isomers with 1H-triazole skeletons, such as Ir(Pr(Ts1-Me)3). Lithium complexes and fac-tris[1-(2,6-diisopropylphenyl)-2-phenyl nyl-1H-imidazole]iridium(III) (abbreviation: Ir(iPrpmi)3), Tris[3-(2,6-dimethylphenyl)-7-methylimidazo[1,2-f]phenanthracene Iridium(III) (abbreviation: Ir(dmpimpt-Me)3) We have developed organometallic iridium complexes with imidazole skeletons and bis[2-(4',6'-difluorophenyl)phenyl] (fluorophenyl)pyridinato-N,C 2’ ]Iridium(III) tetrakis(1-pyra 2-(4',6'-difluorophenyl) bis[2-(4',6'-difluorophenyl) Pyridinate-N,C 2’ ]Iridium(III) picolinate (abbreviation: FIrpic), Bis{2-[3',5'-bis(trifluoromethyl)phenyl]pyridinato-N,C 2 ’}Iridium(III) picolinate (abbreviation: Ir(CF3ppy)2(pic)), Bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2’ ]iridium( III) Fumarate with an electron-withdrawing group such as acetylacetonate (abbreviation: FIracac) These include organometallic iridium complexes with phenylpyridine derivatives as ligands. It is a compound that exhibits color phosphorescence and has an emission peak between 440 nm and 520 nm. Among the above, 4H-triazole, 1H-triazole, imidazolium chloride, Organometallic iridium complexes with a polyazole skeleton, such as Therefore, these compounds are used as the first phosphorescent compound in the light-emitting element of one embodiment of the present invention. The first light-emitting layer is disposed closer to the cathode than the second light-emitting layer, and the second light-emitting layer is disposed closer to the cathode than the first light-emitting layer. When the optical layer has hole transport properties (specifically, when the second host material is a hole transport material), ) is preferable because it becomes easy to control the carrier recombination region within the first light-emitting layer. In addition, organometallic iridium complexes with a 4H-triazole skeleton have excellent reliability and luminescence efficiency. It is particularly preferred because it has excellent

[0100] In addition, tris(4-methyl-6-phenylpyrimidinato)iridium(III) (abbreviation: Ir(mppm)3), tris(4-t-butyl-6-phenylpyrimidinato)iridium Ir(III) (abbreviation: Ir(tBuppm)3), (acetylacetonato)bis(6-methyl Iridium(III) (abbreviation: Ir(mppm)2( acac), (acetylacetonato)bis(6-tert-butyl-4-phenylpyridine Iridium(III) (abbreviation: Ir(tBuppm)2(acac)), (A Cetylacetonato)bis[6-(2-norbornyl)-4-phenylpyrimidinato]yl Ir(nbppm)2(acac) )Bis[5-methyl-6-(2-methylphenyl)-4-phenylpyrimidinato]irid 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)2(acac)), bis(benzyl) Ir(bz)benzo[h]quinolinato(III) acetylacetonate q) 2(acac)), tris(benzo[h]quinolinato)iridium(III) (abbreviation :Ir(bzq)3), tris(2-phenylquinolinato-N,C 2’ ) Iridium (I II) (abbreviation: Ir(pq)3), bis(2-phenylquinolinato-N,C 2’ ) Iridi Ir(pq)2(acac) In addition to organometallic iridium complexes with a lysine skeleton, tris(acetylacetonato)(mono Phenanthroline) terbium(III) (abbreviation: Tb(acac)3(Phen)) These are mainly compounds that exhibit green phosphorescence. Among the above, pyrimidine, pyridine, Organometallic iridium complexes with a diazine skeleton, such as diazine, have poor hole-trapping properties. Therefore, these compounds can be used in the light-emitting element of one embodiment of the present invention. The first light-emitting layer is disposed closer to the anode than the second light-emitting layer. In the case where the second light-emitting layer is an electron-transporting layer (specifically, the second host material is an electron In the case of a charge transport material, it is easy to control the carrier recombination region within the first light-emitting layer. In addition, the organometallic iridium complex having a pyrimidine skeleton is highly reliable. Since the luminous efficiency is also remarkably excellent, it is particularly preferable.

[0101] Also, bis[4,6-bis(3-methylphenyl)pyrimidinato](diisobutyrylmeth Iridium(III) (abbreviation: Ir(5mdppm)2(dibm)), bis[4, 6-Bis(3-methylphenyl)pyrimidinato](dipivaloylmethanato)iridium( III) (abbreviation: Ir(5mdppm)2(dpm)), bis[4,6-di(naphthalene

[0111] (dipivaloylmethanato)iridium(III)(abbreviation: I Organometallic iridium complexes with pyrimidine skeletons such as r(d1npm)2(dpm) (acetylacetonato)bis(2,3,5-triphenylpyrazinate)iridium (III) (abbreviation: Ir(tppr)2(acac)), bis(2,3,5-triphenyl Rupyrazinate)(dipivaloylmethanato)iridium(III) (abbreviation: Ir(tppr )2(dpm)), (acetylacetonato)bis[2,3-bis(4-fluorophenyl )Quinoxalinato]iridium(III) (abbreviation: Ir(Fdpq)2(acac)) Organometallic iridium complexes with pyrazine skeletons such as tris(1-phenylisoquinoline) Rinat - N,C 2’ ) Iridium(III) (abbreviation: Ir(piq)3), bis(1-fluoro Phenylisoquinolinato-N,C 2’ ) Iridium(III) acetylacetonate (abbreviation Organometallic iridium complexes with pyridine skeletons such as Ir(piq)2(acac) In addition to the 2,3,7,8,12,13,17,18-octaethyl-21H,23H-poly Platinum complexes such as rufirin platinum(II) (abbreviation: PtOEP) and tris(1,3-diphenylphosphine) Phenyl-1,3-propanedionato)(monophenanthroline)europium(III) ) (abbreviation: Eu(DBM)3(Phen)), tris[1-(2-thenoyl)-3,3, 3-Trifluoroacetonato](monophenanthroline)europium(III)(abbreviation These include rare earth metal complexes such as Eu(TTA)3(Phen). It is a compound that exhibits color phosphorescence and has an emission peak at 600 nm to 700 nm. Among the above, organometallic iridates having a diazine skeleton such as pyrimidine and pyrazine are preferred. The diazine skeleton is a weak hole trapping material, but a strong electron trapping material. The second phosphorescent compound is an organometallic iridium complex having the formula: is provided closer to the cathode than the second light-emitting layer, and the second light-emitting layer has hole transport properties (specifically, Specifically, when the second host material is a hole transport material, the carrier recombination region is In addition, the pyrimidine skeleton is preferably a compound having a pyrimidine skeleton. Organic metal iridium complexes are particularly preferred because they are remarkably excellent in reliability and luminous efficiency. In addition, organometallic iridium complexes with pyrazine skeletons can emit red light with good chromaticity. Therefore, when applied to a white light emitting device, the color rendering can be improved.

[0102] In addition to the phosphorescent compounds described above, known phosphorescent light-emitting materials may be used in the embodiments. A first phosphorescent material and a second phosphorescent material having the relationship shown in FIG. 1 are selected and used. Good too.

[0103] The phosphorescent compounds (first phosphorescent compound 113a and second phosphorescent compound 113b) 13b), a material that exhibits thermally activated delayed fluorescence (TADF) Here, delayed fluorescence is a material that does not have the same spectrum as normal fluorescence. Its lifetime is approximately 10 -6 seconds or more, preferably 10 -3 Specific examples of thermally activated delayed fluorescent materials include fullerenes and their derivatives, Examples of the flavin derivatives include acridine derivatives such as flavin, and eosin. ), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (I n), or metal-containing porphyrins including palladium (Pd), etc. The porphyrin-containing complex is, for example, a protoporphyrin-tin fluoride complex (abbreviation: Sn F2(Proto IX)), mesoporphyrin-tin fluoride complex (abbreviation: SnF2(M eso IX), hematoporphyrin-tin fluoride complex (abbreviation: SnF2(Hemat o IX)), coproporphyrin tetramethyl ester-tin fluoride complex (abbreviation: Sn F2(Copro III-4Me)), Octaethylporphyrin-Tin Fluoride Complex ( abbreviation: SnF2(OEP)), etioporphyrin-tin fluoride complex (abbreviation: SnF2( Etio I), octaethylporphyrin-platinum chloride complex (abbreviation: PtCl2(OE Furthermore, 2-(biphenyl-4-yl)-4,6-bis(12- Phenylindolo[2,3-a]carbazol-11-yl)-1,3,5-triazine (abbreviation: PIC-TRZ) and other heteroaromatic rings with π-rich and π-deficient heteroaromatic rings. A cyclic compound can also be used. The bonded materials have donor properties of π-rich heteroaromatic rings and acceptor properties of π-deficient heteroaromatic rings. This is particularly preferable because it increases the strength of both the S1 and T1 energies and reduces the energy difference between S1 and T1.

[0104] Materials that can be used as the first and second host materials are not particularly limited. Instead, various carrier transport materials are selected and appropriately assembled to obtain the device structure shown in FIG. Just match them.

[0105] 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 mentioned. However, heterocyclic compounds with a diazine skeleton and heterocyclic compounds with a pyridine skeleton have high reliability. is preferable. In particular, heterocyclization having a diazine (pyrimidine or pyrazine) skeleton is preferable. The compound has a high electron transporting property and contributes to a reduction in the driving voltage.

[0106] 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.

[0107] 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.

[0108] 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.

[0109] 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.

[0110] 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.

[0111] 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).

[0112] 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.

[0113] 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.

[0114] The EL layer 103 may be formed by any method, 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. .

[0115] 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.

[0116] 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

[0117] 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 in the 1st electrode 101, the emitted light is taken out through the first electrode 101. 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.

[0118] 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 .

[0119] 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

[0120] 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 staggered TFT or an inverted staggered TFT. 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.

[0121] Note that this embodiment mode can be appropriately combined with other embodiment modes.

[0122] (Embodiment 3) In this embodiment, a light-emitting device using the light-emitting element described in Embodiments 1 and 2 is This article explains:

[0123] 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. 4. FIG. 4(A) is a top view showing the light-emitting device. 4B is a cross-sectional view taken along lines AB and CD in FIG. 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.

[0124] 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.

[0125] 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.

[0126] 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.

[0127] 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.

[0128] 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.

[0129] 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. .

[0130] 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). .

[0131] 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.

[0132] 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.

[0133] Furthermore, the sealing substrate 604 is bonded to the element substrate 610 with a sealant 605. A space 607 surrounded by an element substrate 610, a sealing substrate 604, and a sealant 605 contains light-emitting elements. 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.

[0134] 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.

[0135] 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.

[0136] 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.

[0137] 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. 5(A) shows a passive matrix light-emitting device manufactured by 5(B) is a cross-sectional view taken along the line XY in FIG. 5(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.

[0138] 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 6(A) and 6(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, an EL layer 1028, a second electrode 1029 of the light-emitting element, a sealing group The plate 1031, the seal material 1032, etc. are shown in the figure. The green colored layer 1034R, the green colored layer 1034G, and the blue colored layer 1034B are provided on a transparent substrate 1033. A black layer (black matrix) 1035 may be further provided. The transparent base material 1033 provided with the black layer is aligned and fixed to the substrate 1001 . The colored layer and the black layer are covered with an overcoat layer 1036. In the configuration of the first type, the light is emitted from the light-emitting layer without passing through the colored layers, and the light is transmitted through the colored layers of each color. 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 there are four colors, red, blue, and green, an image can be expressed using four pixels.

[0139] 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. 7. 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.

[0140] 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 device, it is preferable that the first electrode is a reflective electrode. In order to obtain white light emission, the configurations described in the first and second embodiments are used. A structure that can emit white light is one in which two EL layers are used. Blue light is emitted from the light-emitting layer in one EL layer, and orange light is emitted from the light-emitting layer in the other EL layer. The blue light is emitted from the light-emitting layer of one EL layer and the blue light is emitted from the other EL layer. A possible configuration is one in which red and green light can be obtained from the light-emitting layer in the L layer. When three EL layers are used, red, green and blue light are emitted from the respective emitting layers. By making the light emitting element emitting white light, it is possible to obtain a light emitting element emitting white light. If the configurations shown in the first and second embodiments are applied, the configuration for obtaining white light emission is as follows. Of course, this is not limited to the above.

[0141] 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. 6B, 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.

[0142] 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.

[0143] 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. Instead, full color display may be achieved using three colors: red, green, and blue. The color purity may be improved by providing a microcavity structure. This structure may be provided for all pixels, but may also be provided for only blue pixels.

[0144] This embodiment mode can be freely combined with other embodiment modes.

[0145] (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. 8. FIG. 8(B) is a top view of the lighting device, and FIG. 8(B) is a cross-sectional view taken along the line ef in FIG. 8(B).

[0146] 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.

[0147] 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

[0148] 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.

[0149] 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 material with high reflectivity. In this embodiment, the second electrode 404 is preferably formed by the pad 4. Voltage is supplied by connecting to 12.

[0150] 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.

[0151] 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.

[0152] 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.

[0153] 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.

[0154] (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.

[0155] 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.

[0156] FIG. 9A shows an example of a television device. The television device includes a housing 710. A display unit 7103 is built into the display unit 1. Also, in this embodiment, a stand 7105 is used to support the display unit 1. The display unit 7103 can display images. The display portion 7103 can be formed by using the light-emitting element described in Embodiments 1 and 2 as a matrix. The light emitting elements are arranged in a square shape. The light emitting elements are preferably light emitting elements with good light emitting efficiency. In addition, it is possible to provide a light emitting element with a low driving voltage. Therefore, the display unit 7 made up of the light emitting element can be made to have a long wavelength. The television apparatus having the above-mentioned 103 can be a television apparatus with reduced power consumption. It is also possible to provide a television device with a low driving voltage. It is possible to provide a television device with high usability.

[0157] 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.

[0158] 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.

[0159] FIG. 9(B1) shows a computer, which includes a main body 7201, a housing 7202, a display unit 7203, and a keyboard. keyboard 7204, external connection port 7205, pointing device 7206, etc. This computer is capable of generating the same data as that described in the second or third embodiment. The display unit 7203 is fabricated by arranging optical elements in a matrix. The computer of FIG. 9(B2) may be in the form of the computer of FIG. 9(B2). The computer includes a second keyboard 7204 and a second pointing device 7206. A display unit 7210 is provided. The second display unit 7210 is a touch panel type. By operating the display for input displayed on the second display unit 7210 with a finger or a special pen, The second display portion 7210 can be used not only for displaying input data but also for It is also possible to display other images. Good. The two screens are connected by a hinge, so you can easily fold the screens apart when storing or transporting. It is also possible to prevent troubles such as damage or breakage. It is possible to obtain a light emitting element with good efficiency. The computer having the display unit 7203 can be a computer with reduced power consumption. Cut.

[0160] FIG. 9C 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 unit manufactured by arranging the light-emitting elements described in the first and second embodiments in a matrix. A display unit 7305 is incorporated in the housing 7302. The portable gaming machine shown in FIG. 9(C) also includes a speaker unit 7306 and a recording medium insertion unit 7307. , LED lamp 7308, input means (operation keys 7309, connection terminal 7310, sensor 73 11 (force, displacement, position, velocity, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical Chemical substances, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration , odor or infrared measuring function), microphone 7312) etc. Of course, the configuration of the portable gaming machine is not limited to the above, and at least the display unit 73 The display portion 7304 and / or the display portion 7305 may be formed using the It is sufficient to use a display unit made by arranging light-emitting elements in a matrix, and other accessories The portable game machine shown in FIG. 9(C) is a configuration in which the recording medium The function of reading out the programs or data stored in the device and displaying them on the display unit, It has a function to share information with the mobile game machine by wireless communication. The functions of the strip-type gaming machine are not limited to those described above, and the machine may have various functions. A portable game machine having such a display portion 7304 has a light-emitting element used in the display portion 7304. Since the device has good luminous efficiency, it is a portable gaming machine with reduced power consumption. In addition, the light-emitting element used in the display portion 7304 can be driven at a low driving voltage. Therefore, it is possible to provide a portable gaming machine with a low driving voltage. Since the light emitting element used in the portion 7304 is a light emitting element with a long life, it is highly reliable. It can be a portable gaming machine.

[0161] FIG. 9D 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 74 05, a microphone 7406, etc. The mobile phone 7400 is 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. It is possible to provide a light emitting element with a low driving voltage. Therefore, a mobile phone having a display portion 7402 including the light-emitting element can be used. The mobile phone can be a mobile phone with reduced power consumption. It is possible to make a telephone set. It is also possible to make a highly reliable mobile phone. .

[0162] In the mobile phone shown in FIG. 9D, 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 create an email. Such an operation can be performed by touching the display portion 7402 with a finger or the like.

[0163] 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.

[0164] 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.

[0165] 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.

[0166] 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.

[0167] 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.

[0168] 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.

[0169] Note that the configuration shown in this embodiment mode may be obtained by appropriately combining the configurations shown in Embodiment Modes 1 to 4. They can be used in combination.

[0170] 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.

[0171] FIG. 10 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. 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 .

[0172] 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.

[0173] FIG. 11 shows a configuration in which the light-emitting element according to the first and second embodiments is mounted on an electric switch which is a lighting device. The desk lamp shown in FIG. 11 is an example of a desk lamp using a housing 2001 and a light source 2002. The light emitting device described in the fourth embodiment is used as the light source 2002.

[0174] FIG. 12 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.

[0175] The light emitting elements described in the first and second embodiments are used for the windshield and dash of an automobile. FIG. 13 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.

[0176] 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.

[0177] 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.

[0178] 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.

[0179] 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.

[0180] FIG. 14(A) and FIG. 14(B) show an example of a tablet terminal that can be folded in two. FIG. 4(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.

[0181] 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 used as a touch panel by displaying keyboard buttons, and the display section 9631b is displayed It can be used as a screen.

[0182] 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, A keyboard button can be displayed on the display portion 9631b.

[0183] In addition, when touching the touch panel area 9632a and the touch panel area 9632b at the same time, You can also input the

[0184] 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 that detect tilt, other detection devices such as gyros and acceleration sensors are also available. may be incorporated.

[0185] FIG. 14A 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.

[0186] FIG. 14B shows a state in which the tablet terminal according to the present embodiment is closed. Body 9630, solar cell 9633, charge / discharge control circuit 9634, battery 9635, DCD 14B 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.

[0187] 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.

[0188] In addition, the tablet terminals shown in Figs. 14(A) and 14(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.

[0189] 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:

[0190] The configuration and operation of the charge / discharge control circuit 9634 shown in FIG. A block diagram is shown in FIG. 14(C) and will be explained. FIG. 14(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. 14(B). This corresponds to the circuit 9634 .

[0191] 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.

[0192] 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.

[0193] In addition, if the display unit 9631 is provided, a tablet terminal having the shape shown in FIG. Not limited to. EXAMPLES

[0194] In this example, a light-emitting device corresponding to one embodiment of the present invention described in the first and second embodiments is used. The method of producing the device and its characteristics are described below. The structures of the organic compounds used in this example are as follows: The formula is shown below.

[0195] [ka]

[0196] Next, a method for fabricating the light emitting device of this embodiment will be described.

[0197] 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

[0198] 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.

[0199] Then, 10 -4 The substrate is placed in a vacuum deposition apparatus whose inside has been reduced in pressure to about Pa. After vacuum baking at 170°C for 30 minutes in the heating chamber of the device, the substrate is left for about 30 minutes. Allow to cool.

[0200] 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), The implantation layer 111 was formed. Its thickness was set to 33 nm, and it was made of DBT3P-II and molybdenum oxide. 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.

[0201] 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.

[0202] 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) and the above Bis[2-(6-tert-butyl-4-pyrimidinyl-κN3] represented by structural formula (v) )phenyl-κC](2,4-pentanedionato-κ 2O,O') Iridium(III) (abbreviation: Ir(tBuppm)2(acac)) in a weight ratio of 0.8:0.2:0.05 (=2mDBTPDBq-II:PCBA1BP:Ir(tBuppm)2(acac) ) to form the first light-emitting layer 113a, and 2mDBTPDBq-I I and bis(2,3,5-triphenylpyrazinate) (dipyridin) represented by the above structural formula (vi) Valoylmethanato)iridium(III) (abbreviation: Ir(tppr)2(dpm)) , weight ratio 1:0.06 (=2mDBTPDBq-II:Ir(tppr)2(dpm)) The second light-emitting layer 113b was formed by co-evaporation so as to have a thickness of 20 nm. 2mDBTPDBq-II and PCBA1BP form an exciplex.

[0203] Thereafter, 2mDBTPDBq-II was formed on the light-emitting layer 113 to a thickness of 15 nm. and further, bathophenanthroline (abbreviation: BPhen) represented by the above structural formula (vii). The electron transport layer 114 was formed by depositing the compound to a thickness of 15 nm.

[0204] After the electron transport layer 114 is formed, lithium fluoride (LiF) is then deposited to a thickness of 1 nm. The electron injection layer 115 was formed by vapor deposition in such a manner that the electron injection layer 115 was formed.

[0205] Finally, a second electrode 102 functioning as a cathode was formed by depositing aluminum to a thickness of 200 nm. Thus, the light-emitting element 1 of this example was fabricated.

[0206] In the above-mentioned deposition process, the deposition was all performed by a resistance heating method.

[0207] The element structure of the thus obtained Light-emitting Element 1 is shown in Table 1.

[0208] [Table 1]

[0209] The light emitting element 1 is placed in a nitrogen atmosphere glove box and covered with glass so as not to be exposed to the atmosphere. The process of sealing with a substrate (applying a sealant around the element and sealing at 80℃ for 1 hour) Heat treatment) was performed.

[0210] In the light-emitting element 1, the first phosphorescent compound 113Da was Ir(tBuppm)2(ac ac) using Ir(tppr)2(dpm) as the second phosphorescent compound 113Db. Here, the PL spectrum of Ir(tBuppm)2(acac) and the PL spectrum of Ir(tp ε(λ)λ of pr)2(dpm) 4 Here, λ is the wavelength, and ε(λ) is is the molar extinction coefficient.

[0211] First, in Figure 20(a), the molar absorption coefficient ε(λ) of Ir(tppr)2(dpm) and ε(λ )λ 4 The graph shows the molar absorption coefficient ε(λ) with a prominent peak in the long wavelength region. There is no peak, whereas ε(λ)λ 4 In the graph, there is a maximum at 543 nm. This peak is the triplet ML of Ir(tppr)2(dpm). CT absorption, and the emission peak of the first phosphorescent compound 113Da is superimposed on this peak. By combining these two, it is possible to greatly increase the efficiency of energy transfer.

[0212] FIG. 20(b) shows the first phosphorescent compound 113Da, Ir(tBuppm)2(ac PL spectrum F(λ) of the second phosphorescent compound 113Db, Ir(tpp ε(λ)λ of r2(dpm) 4 From this graph, Ir(tBu The PL spectrum of Ir(tpp ppm)2(acac) shows the peak of F(λ) and the peak of Ir(tpp ε(λ)λ of r2(dpm) 4 The peak with the longest wavelength maximum is largely overlapped with the peak with the longest wavelength maximum. This shows that this combination allows for extremely efficient energy transfer. The emission peaks of the first phosphorescent compound, Ir(tBuppm)2(acac), The peak is at 546 nm, and the second phosphorescent compound 113Db, Ir(tppr)2 (dpm)ε(λ) 4 The long-wavelength maximum in the spectrum is at 543 nm. Therefore, the difference is 3 nm. 546 nm is 2.27 eV, 543 nm is 2.28 e Since the difference is equivalent to 0.01 eV, it is smaller than the difference of 0.2 eV. The peak positions also suggest that efficient energy transfer occurs.

[0213] Next, FIG. 21(a) shows the first phosphorescent compound 113Da, Ir(tBuppm)2 The molar extinction coefficient ε(λ) of (acac) and ε(λ)λ 4 The graph below shows the molar absorption coefficient. The peak in the long wavelength region in the graph showing the optical coefficient ε(λ) is smaller than the peak in the short wavelength region. Its strength is small compared to ε(λ)λ 4 In the graph, the largest peak is at 494 nm. The peak where this maximum exists is Ir(tBu ppm)2(acac) triplet MLCT absorption, and this peak corresponds to the energy donor By overlapping the emission peaks, it is possible to greatly increase the efficiency of energy transfer. do.

[0214] In the light-emitting element 1 of this example, the first host material 2mDBTPDBq-II and the first organic compound PCBA1BP form an exciplex 113Ec, and the exciplex Energy is supplied from the phosphorescent compound 113Ec to the first phosphorescent compound 113Da. Figure 23 shows the results of the analysis of 2mDBTPDBq-II, PCBA1BP, and their mixed membranes. (mass ratio 0.8:0.2) -II and the first organic compound PCBA1BP form the exciplex 113Ec. In addition, Fig. 21(b) shows the PL spectrum F(λ) of the exciplex and the first ε(λ)λ of the phosphorescent compound Ir(tBuppm)2(acac) 4 of From this graph, it is clear that there is a peak in the PL spectrum F(λ) of the exciplex. The ε(λ)λ of the existing mountain and Ir(tBuppm)2(acac) 4 The maximum value on the longest wavelength side This combination allows for efficient energy transfer. The PL spectrum peak of the exciplex is at 519 nm, which corresponds to the first phosphorus. The ε(λ)λ of the photoactive compound Ir(tBuppm)2(acac) of 113Da 4 Represents The maximum on the long wavelength side of the spectrum is at 494 nm, so the difference is 25 nm. The energy equivalent of 519 nm is 2.39 eV, and the energy equivalent of 494 nm is This corresponds to 2.51 eV, so the difference is 0.12 eV, which is less than 0.2 eV. The small difference in the peak positions suggests that efficient energy transfer occurs. will be done.

[0215] As can be seen from FIG. 23, the first host material 113Ha is 2mDBTPDBq The PL spectrum peak of α-II is at 426 nm, which is equivalent to 2.91 nm in energy. eV. The PL spectrum of the first organic compound, PCBA1BP, The Ir peak is at 405 nm, which is equivalent to 3.06 eV in energy. (tBuppm)2(acac)ε(λ) 4 In the spectrum representing The maximum value is at 494 nm, which corresponds to 2.51 eV in terms of energy. The difference between the two is 0.4 eV (first host material 113Ha:2mDBTPDBq-II), 0.55 eV (first organic compound 113A: PCBA1BP), both of which are 0.2 e V or more, so 2mDBTPDBq-II and PCBA1BP It can be seen that energy transfer to Ir(tBuppm)2(acac) is difficult.

[0216] Figure 22 shows the PL spectrum of the exciplex F(λ), Ir(tBuppm)2(acac ) PL spectrum F(λ), Ir(tppr)2(dpm) PL spectrum F(λ) , ε(λ)λ of Ir(tBuppm)2(acac) 4 , Ir(tppr)2(dpm) ε(λ) 4 The PL spectrum of the exciplex and Ir(tB uppm)2(acac)ε(λ) 4 Using the overlap with (near the maximum A), the exciplex From Ir(tBuppm)2(acac) to Ir(tBuppm)2(aca c) PL spectrum and ε(λ)λ of Ir(tppr)2(dpm) 4 Overlap with (maximum Using Ir(tBuppm)2(acac) to Ir(tppr)2(dp m), it can be seen that energy can be transferred stepwise. It is also possible to directly transfer energy to the phosphorescent compound Ir(tppr)2(dpm) This can be seen in Figure 22, where the triplet ML of Ir(tppr)2(dpm) On the short wavelength side of the CT absorption band (near the maximum B), the PL spectrum F(λ) of the exciplex and Ir (tppr)2(dpm)ε(λ) 4 This is because they overlap.

[0217] The device characteristics of this light-emitting device were measured. The measurements were performed in an environment maintained at room temperature (25°C). The experiment was conducted in an atmospheric condition.

[0218] The luminance vs. current efficiency characteristics of the light-emitting element 1 are shown in FIG. 15. In FIG. 15, the horizontal axis represents luminance (cd / m 2 The vertical axis represents the current efficiency (cd / A), and the voltage-luminance characteristics are shown in FIG. In 16, the horizontal axis is voltage (V) and the vertical axis is luminance (cd / m 2 ) and also represents the luminance-external The quantum efficiency characteristics are shown in FIG. 17. In FIG. 17, the horizontal axis is the luminance (cd / m 2 ), the vertical axis is external The quantum efficiency (%) is shown. The luminance-power efficiency characteristics are shown in FIG. 18. In FIG. 18, The horizontal axis is luminance (cd / m 2 ), and the vertical axis indicates power efficiency (%).

[0219] As described above, it was found that the light-emitting element 1 exhibited good element characteristics. In particular, FIG. 7. As can be seen from FIG. 18, it has very good luminous efficiency, and the external quantum efficiency is practical brightness ( 1000cd / m 2 ), a high value of over 20% was shown. The brightness is around 60cd / A and the power efficiency is also very good, at around 60lm / W.

[0220] FIG. 19 shows the emission spectrum when a current of 0.1 mA is applied to the light-emitting element 1. In FIG. 19, the horizontal axis represents wavelength (nm) and the vertical axis represents emission intensity (arbitrary unit). The light-emitting element 1 is a bis[2-(6-tert-butyl-4-pyrimidinyl-κN3)phenyl -κC](2,4-pentanedionato-κ 2 O,O') Iridium(III) (abbreviation: I Green wavelength light from r(tBuppm)2(acac) and bis(2,3,5-trifluoroethylene) (phenylpyrazinato)(dipivaloylmethanato)iridium(III) (abbreviation: Ir(tp The emission spectrum contains a well-balanced amount of red wavelength light derived from the pr)2(dpm) I realized that.

[0221] As described above, the light-emitting element 1 according to one embodiment of the present invention has good luminous efficiency and can be used in two types of It was found that this light-emitting element was capable of obtaining well-balanced light from the luminescent center substances. EXAMPLES

[0222] In this example, a light-emitting device corresponding to one embodiment of the present invention described in the first and second embodiments is used. The method of producing the device and its characteristics are described below. The structures of the organic compounds used in this example are as follows: The formula is shown below.

[0223] [ka]

[0224] Next, a method for fabricating the light emitting device of this embodiment will be described.

[0225] 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. 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 compound represented by the above structural formula (viii) was deposited on the first electrode 101 by a deposition method using resistance heating. ) represented by 3-[4-(9-phenanthryl)-phenyl]-9-phenyl-9H-ca By co-evaporating rutile (PCPPn) and molybdenum (VI) oxide, An injection layer 111 was formed. The thickness of the injection layer 111 was set to 33.3 nm, and the injection layer 111 was made of PCPPn and molybdenum oxide. The weight ratio was adjusted to 1:0.5 (=PCPPn:molybdenum oxide). The co-evaporation method is a method in which deposition is performed simultaneously from multiple evaporation sources in one processing chamber. be.

[0229] 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.

[0230] Furthermore, on the hole transport layer 112, 2-[3′-(dibenzo Thiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation : 2mDBTBPDBq-II) and 4,4'-di(1-naphthalene) represented by the above structural formula (x) 4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBNBB) and bis[2-(6-tert-butyl) [2,4-pentanedionato-κ] 2 O ,O') iridium(III) (abbreviation: Ir(tBuppm)2(acac)) and heavy Amount ratio 0.8:0.2:0.06(=2mDBTBPDBq-II:PCBNBB:Ir( The first light-emitting layer 113a was formed by co-evaporation to a thickness of 20 nm. The bis(2,3,5- Triphenylpyrazinate)(dipivaloylmethanato)iridium(III)(abbreviation: Ir (tppr)2(dpm)) in a weight ratio of 1:0.06 (=2mDBTBPDBq-II :Ir(tppr)2(dpm)) was co-evaporated to a thickness of 20 nm to form the second light-emitting layer 113 b was formed. Note that the host materials 2mDBTBPDBq-II and PCBNBB It forms an exciplex.

[0231] Then, 2mDBTBPDBq-II was formed on the light-emitting layer 113 to a thickness of 15 nm. Furthermore, bathophenanthroline (abbreviation: BPhen) represented by the above structural formula (vii) ) was deposited to a thickness of 15 nm to form the electron transport layer 114.

[0232] After the electron transport layer 114 is formed, lithium fluoride (LiF) is then deposited to a thickness of 1 nm. The electron injection layer 115 was formed by vapor deposition in such a manner that the electron injection layer 115 was formed.

[0233] Finally, a second electrode 102 functioning as a cathode was formed by depositing aluminum to a thickness of 200 nm. Thus, the light-emitting element 2 of this example was fabricated.

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

[0235] The element structure of the thus obtained Light-emitting Element 2 is shown in Table 2.

[0236] [Table 2]

[0237] The light emitting element 2 is placed in a nitrogen atmosphere glove box and is covered with glass so as not to be exposed to the atmosphere. The process of sealing with a substrate (applying a sealant around the element and sealing at 80℃ for 1 hour) Heat treatment) was performed.

[0238] In the light-emitting element 2, similarly to the light-emitting element 1, Ir(tB uppm)2(acac) as the second phosphorescent compound 113Db, and Ir(tppr) Therefore, the PL spec of Ir(tBuppm)2(acac) ε(λ)λ of Ir(tppr)2(dpm) 4Regarding the relationship between Since the above is the same as that in the first embodiment, the repeated explanation will be omitted. As described above, the first phosphorescent compound 113 in the light-emitting element 2 Energy transfer between Da and the second phosphorescent compound 113Db is efficient. is suggested.

[0239] The device characteristics of this light-emitting device were measured. The measurements were performed in an environment maintained at room temperature (25°C). The experiment was conducted in an atmospheric condition.

[0240] FIG. 24 shows the luminance vs. current efficiency characteristics of the light-emitting element 2. FIG. 25 shows the voltage vs. luminance characteristics. The luminance vs. external quantum efficiency characteristics are shown in FIG. 26. The luminance vs. power efficiency characteristics are shown in FIG. As shown in.

[0241] As described above, it was found that the light-emitting element 2 exhibited good element characteristics. In particular, FIG. 6. As can be seen from FIG. 27, it has very good luminous efficiency, and the external quantum efficiency is practical brightness ( 1000cd / m 2 ), a high value of over 20% was shown. The brightness is around 60cd / A and the power efficiency is also very good, around 60lm / W.

[0242] FIG. 28 shows the emission spectrum when a current of 0.1 mA is applied to the light-emitting element 2. 28, the light-emitting element 2 is bis[2-(6-tert-butyl-4-pyrimidinyl-κN3 )phenyl-κC](2,4-pentanedionato-κ 2 O,O') Iridium(III) (abbreviation: Ir(tBuppm)2(acac)) and bis(2,3, 5-Triphenylpyrazinato)(dipivaloylmethanato)iridium(III)(Abbreviation: The emission spectrum contains a balanced amount of red wavelength light derived from Ir(tppr)2(dpm) It was found to show a kinetic energy of 1.2 kV.

[0243] In addition, the initial brightness is 5000cd / m 2 With the current density constant, the initial brightness is 100 The results of a reliability test performed under the above conditions are shown in FIG. 29. As shown in FIG. 29, the light-emitting element 2 had an initial brightness of 100 nm. degree 5000cd / m 2 Despite the reliability test, the brightness was only 96% of the initial brightness after 70 hours. It was found that the light-emitting element had good reliability.

[0244] As described above, the light-emitting element 2 according to one embodiment of the present invention has good luminous efficiency and has two types of It was found that this is a light-emitting device that can obtain light from the luminescent center substances in a well-balanced manner. It was also found that the light-emitting element had good reliability and a long life. EXAMPLES

[0245] In this example, a light-emitting device corresponding to one embodiment of the present invention described in the first and second embodiments is used. The method of producing the device and its characteristics are described below. The structures of the organic compounds used in this example are as follows: The formula is shown below.

[0246] [ka]

[0247] Next, a method for fabricating the light emitting device of this embodiment will be described.

[0248] 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

[0249] 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.

[0250] Then, 10 -4 The substrate is placed in a vacuum deposition apparatus whose inside has been reduced in pressure to about Pa. After vacuum baking at 170°C for 30 minutes in the heating chamber of the device, the substrate is left for about 30 minutes. Allow to cool.

[0251] 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), The hole injection layer 111 was formed. Its thickness was set to 40 nm, and it was made of DBT3P-II and molybdenum oxide. 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 in which deposition is performed simultaneously from multiple evaporation sources in one processing chamber. It is a method of wearing.

[0252] Next, on the hole injection layer 111, 4,4',4''-triphenylphosphine oxide represented by the above structural formula (xi) (N-Carbazolyl)triphenylamine (abbreviation: TCTA) was applied to a film thickness of 10 nm. Thus, a hole transport layer 112 was formed.

[0253] Furthermore, on the hole transport layer 112, TCTA and bis(2,3 ,5-Triphenylpyrazinato)(dipivaloylmethanato)iridium(III)(abbreviation :Ir(tppr)2(dpm)) in a weight ratio of 1:0.1 (=TCTA:Ir(tpp r) 2(dpm)) to form the second light-emitting layer 113b by co-evaporation of 10 nm. 2-[3-(dibenzothiophen-4-yl)phenyl]dibenzothiophene represented by formula (iii) Benzo[f,h]quinoxaline (abbreviation: 2mDBTPDBq-II) and the above structural formula (iv) Represented by 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)trimethyl phenylamine (abbreviation: PCBA1BP) and the bis[2-(6 -tert-Butyl-4-pyrimidinyl-κN3)phenyl-κC](2,4-pentane Geonath-κ 2 O,O') Iridium(III) (abbreviation: Ir(tBuppm)2(ac ac)) in a weight ratio of 0.8:0.2:0.05 (=2mDBTPDBq-II:PCB A1BP:Ir(tBuppm)2(acac)) was co-evaporated to form the first The light-emitting layer 113a was formed. Note that the host material 2mDBTPDBq-II and PCB It forms an exciplex with A1BP.

[0254] Then, 2mDBTPDBq-II and Ir(tBuppm)2(aca c) and 1:0.05 (=2mDBTPDBq-II:Ir(tBuppm)2(aca c)) was co-evaporated to a thickness of 20 nm, and 2mDBTPDBq-II was deposited to a thickness of 10 nm. In addition, bathophenanthroline (abbreviation: BPhen) represented by the above structural formula (vii) was added twice. The electron transport layer 114 was formed so as to have a thickness of 0 nm.

[0255] After the electron transport layer 114 is formed, lithium fluoride (LiF) is then deposited to a thickness of 1 nm. The electron injection layer 115 was formed by vapor deposition in such a manner that the electron injection layer 115 was formed.

[0256] Finally, a second electrode 102 functioning as a cathode was formed by depositing aluminum to a thickness of 200 nm. Thus, the light-emitting element 3 of this example was fabricated.

[0257] In the above-mentioned deposition process, the deposition was all performed by a resistance heating method.

[0258] The element structure of the light-emitting element 3 thus obtained is shown in Table 3. The material of the hole transport layer of the light-emitting element 3 is The light-emitting element was fabricated using a material that is significantly different from that of the light-emitting element 1 and the light-emitting element 2 as the first host material and the second host material. In addition, the positions of the first and second light-emitting layers relative to the electrodes and the electron transport The structures of the layers are also significantly different.

[0259] [Table 3]

[0260] The light emitting element 3 is placed in a glove box with a nitrogen atmosphere and is covered with glass so as not to be exposed to the atmosphere. The process of sealing with a substrate (applying a sealant around the element and sealing at 80℃ for 1 hour) Heat treatment) was performed.

[0261] In the light-emitting element 3, similarly to the light-emitting element 1, Ir(tB uppm)2(acac) as the second phosphorescent compound 113Db, and Ir(tppr) Therefore, the PL spec of Ir(tBuppm)2(acac) ε(λ)λ of Ir(tppr)2(dpm) 4 Regarding the relationship between Since the above is the same as that in the first embodiment, the repeated explanation will be omitted. As described above, the first phosphorescent compound 113 in the light-emitting element 3 Energy transfer between Da and the second phosphorescent compound 113Db is efficient. is suggested.

[0262] The device characteristics of this light-emitting device were measured. The measurements were performed in an environment maintained at room temperature (25°C). The experiment was conducted in an atmospheric condition.

[0263] FIG. 30 shows the luminance vs. current efficiency characteristics of the light-emitting element 3. FIG. 31 shows the voltage vs. luminance characteristics. The luminance vs. external quantum efficiency characteristics are shown in FIG. 32. The luminance vs. power efficiency characteristics are shown in FIG. 33. As shown in.

[0264] As described above, it was found that the light-emitting element 3 exhibited good element characteristics. In particular, FIG. 2. As can be seen from FIG. 33, it has very good luminous efficiency, and the external quantum efficiency is greater than the practical brightness ( 1000cd / m 2 ), a high value of over 20% was shown. The brightness is around 60cd / A and the power efficiency is around 70lm / W, both of which are very good values.

[0265] FIG. 34 shows the emission spectrum when a current of 0.1 mA is applied to the light-emitting element 3. From 34, the light-emitting element 3 is bis[2-(6-tert-butyl-4-pyrimidinyl-κN )phenyl-κC](2,4-pentanedionato-κ 2 O,O') Iridium(III) (abbreviation: Ir(tBuppm)2(acac)) and bis(2,3, 5-Triphenylpyrazinato)(dipivaloylmethanato)iridium(III)(Abbreviation: The emission spectrum contains a balanced amount of red wavelength light derived from Ir(tppr)2(dpm) It was found to show a kinetic energy of 1.2 kV.

[0266] Thus, the light-emitting element 3, which corresponds to one embodiment of the present invention, is different from the light-emitting element 1 and the light-emitting element 2. Although it uses a host material, it has good luminous efficiency and is composed of two types of luminescent center substances. It was found that this is a light-emitting element that can emit light in a well-balanced manner. EXAMPLES

[0267] In this example, a light-emitting device corresponding to one embodiment of the present invention described in the first and second embodiments is used. The method of producing the device and its characteristics are described below. The structures of the organic compounds used in this example are as follows: The formula is shown below.

[0268] [ka]

[0269] Next, a method for fabricating the light-emitting elements of this example (light-emitting element 4 and light-emitting element 5) will be described.

[0270] 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

[0271] 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.

[0272] Then, 10 -4 The substrate is placed in a vacuum deposition apparatus whose inside has been reduced in pressure to about Pa. After vacuum baking at 170°C for 30 minutes in the heating chamber of the device, the substrate is left for about 30 minutes. Allow to cool.

[0273] 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 compound represented by the above structural formula (ii) was deposited on the first electrode 101 by a deposition method using resistance heating. Represented by 4-phenyl-4'-(9-phenylfluoren-9-yl)triphenyl By co-evaporating BPAFLP and molybdenum(VI) oxide, hole injection was achieved. The layer 111 was formed. The thickness of the layer was set to 33.3 nm, and the layer was made of BPAFLP and molybdenum oxide. The weight ratio was adjusted to 1:0.5 (=BPAFLP:molybdenum oxide). The co-evaporation method is a method in which deposition is performed simultaneously from multiple evaporation sources in one processing chamber. be.

[0274] Next, a film of BPAFLP was formed to a thickness of 20 nm on the hole injection layer 111. A transfer layer 112 was formed.

[0275] 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) and the above Bis[2-(6-tert-butyl-4-pyrimidinyl-κN3] represented by structural formula (v) )phenyl-κC](2,4-pentanedionato-κ 2 O,O') Iridium(III) (abbreviation: Ir(tBuppm)2(acac)) in a weight ratio of 0.8:0.2:0.06 (=2mDBTPDBq-II:PCBA1BP:Ir(tBuppm)2(acac) ) to form the first light-emitting layer 113a, and 2mDBTPDBq-I I and bis{4,6-dimethyl-2-[3-(3,5-diphenyl Methylphenyl)-5-phenyl-2-pyrazinyl-κN]phenyl-κC}(2,6- Dimethyl-3,5-heptanedionate-κ 2 O,O'') Iridium(III) (abbreviation: [Ir(dmdppr-P)2(dibm)]) in a weight ratio of 1:0.06 (=2mDB TPDBq-II: [Ir(dmdppr-P)2(dibm)]) The second light-emitting layer 113b was formed by co-evaporation of 2mDBTPD, which is a host material. Bq-II and PCBA1BP form an exciplex.

[0276] Thereafter, 2mDBTPDBq-II was formed on the light-emitting layer 113 to a thickness of 15 nm. and further, bathophenanthroline (abbreviation: BPhen) represented by the above structural formula (vii). The electron transport layer 114 was formed by depositing the compound to a thickness of 15 nm.

[0277] After the electron transport layer 114 is formed, lithium fluoride (LiF) is then deposited to a thickness of 1 nm. The electron injection layer 115 was formed by vapor deposition in such a manner that the electron injection layer 115 was formed.

[0278] Finally, a second electrode 102 functioning as a cathode was formed by depositing aluminum to a thickness of 200 nm. Thus, the light-emitting element 4 of this example was fabricated.

[0279] The light-emitting element 5 has a first light-emitting layer 113a containing [Ir(tBuppm)2(acac)]. Tris[2-(6-tert-butyl-4-pyrimidinyl)phenyl]phenyl] [Ir(tBuppm) The light-emitting element was fabricated in the same manner as in the light-emitting element 4, except that the light-emitting element 4 was fabricated in place of the light-emitting element 3).

[0280] In the above-mentioned deposition process, the deposition was all performed by a resistance heating method.

[0281] The element structure of the thus obtained light-emitting element 4 is shown in Table 4, and the element structure of the light-emitting element 5 is shown in Table 5.

[0282] [Table 4]

[0283] [Table 5]

[0284] The light-emitting element 4 and the light-emitting element 5 are exposed to the air in a glove box with a nitrogen atmosphere. The process of sealing the element with a glass substrate to prevent damage (sealing material is applied around the element, and 8 Heat treatment was performed at 0°C for 1 hour.

[0285] In the light-emitting element 4, the first phosphorescent compound 113Da was Ir(tBuppm)2(ac ac) as the second phosphorescent compound 113Db, [Ir(dmdppr-P)2(di bm)] is used. Here, the PL spectrum of Ir(tBuppm)2(acac) and ε(λ)λ of [Ir(dmdppr-P)2(dibm)] 4 Describe the relationship between where λ is the wavelength and ε(λ) is the molar absorption coefficient.

[0286] First, in FIG. 45(a), the second phosphorescent compound 113Db of the light-emitting element 4 is [Ir(dmd ppr-P)2(dibm)] and ε(λ)λ 4 A graph showing The molar extinction coefficient ε(λ) does not have a significant peak in the long wavelength region. On the other hand, ε(λ)λ 4 In the graph, the maximum value at 509 nm and the maximum values ​​at 550 nm and 605 nm are There is a peak with a shoulder near m. This peak is [Ir(dmdppr-P) 2(dibm)], and this peak corresponds to the triplet MLCT absorption of the first phosphorescent compound 11. By overlapping the 3D emission peaks, the efficiency of energy transfer is greatly improved. This becomes possible.

[0287] FIG. 45(b) shows the first phosphorescent compound 113Da of the light-emitting element 4, which is Ir(tBupp m)2(acac) and the PL spectrum F(λ) of the second phosphorescent compound 113Db. ε(λ)λ of [Ir(dmdppr-P)2(dibm)] 4 A graph showing the above is shown. From the graph, the peak of PL spectrum F(λ) of Ir(tBuppm)2(acac) The peak where [Ir(dmdppr-P)2(dibm)] exists and ε(λ)λ 4 The longest wave The peak on the long side overlaps with the peak with the maximum value, indicating that energy transfer is very efficient. In addition, the first phosphorescent compound 113Da, Ir The emission peak of (tBuppm)2(acac) is at 546 nm, and the second phosphorescence The ε(λ)λ of compound 113Db, [Ir(dmdppr-P)2(dibm)] 4of The long-wavelength maximum in the spectrum is at 509 nm, so the difference is 37 nm. Since 546 nm corresponds to 2.27 eV and 509 nm corresponds to 2.44 eV, the difference is 0.17 eV, which is smaller than the difference of 0.2 eV. This suggests that the energy transfer is (dibm)] ε(λ)λ 4 The long-wavelength maximum (maximum C) in the spectrum represents The emission spectra F(λ) of Ir(tBuppm)2(acac) are almost completely non-overlapping. is the ε(λ)λ of [Ir(dmdppr-P)2(dibm)] 4 In the spectrum representing The peak with the maximum value C in the figure has a broad shape on the long wavelength side, and the spectrum on this long wavelength side The emission spectra F(λ) of Ir(tBuppm)2(acac) show a large overlap. Therefore, very good energy transfer is achieved.

[0288] In the light-emitting element 4, the first host material 2mDBTPDBq-II and the first organic compound The first phosphorescent compound, Ir Energy transfer is efficiently carried out to (tBuppm)2(acac). The relationship is the same as that of the light-emitting element 1 and is described in detail in the first embodiment. The relevant description is omitted here. Please refer to the relevant description in Example 1.

[0289] Figure 46 shows the PL spectrum of the exciplex F(λ), Ir(tBuppm)2(acac ) PL spectrum F(λ), [Ir(dmdppr-P)2(dibm)] PL spectrum vector F(λ), ε(λ)λ of Ir(tBuppm)2(acac)4 , [Ir(dmd ppr-P)2(dibm)]ε(λ) 4 The graph below shows the combined results of all the above. PL spectrum of Ir(tBuppm)2(acac) and ε(λ)λ of Ir(tBuppm)2(acac) 4 Overlap with (extreme (near the maximum value A) to convert the exciplex to Ir(tBuppm)2(acac), and then to I PL spectrum of r(tBuppm)2(acac) and [Ir(dmdppr-P)2( dibm)] ε(λ)λ 4 Using the overlap with (around 650 nm from the maximum value C), Ir( tBuppm)2(acac) to [Ir(dmdppr-P)2(dibm)], step It can be seen that energy transfer is possible stepwise. Direct energy transfer to the compound [Ir(dmdppr-P)2(dibm)] As can be seen from Figure 46, this can be expressed as [Ir(dmdppr-P)2(dib m)] triplet MLCT absorption band (near maximum C) of the exciplex PL spectrum F(λ) Also, [Ir(dmdppr-P)2(dibm)]'s ε(λ) 4 Because they overlap be.

[0290] In the light-emitting element 5, Ir(tBuppm)3 was used as the first phosphorescent compound 113Da, The phosphorescent compound 113Db was [Ir(dmdppr-P)2(dibm)]. Here, the PL spectrum of Ir(tBuppm)3 and [Ir(dmdppr -P)2(dibm)]ε(λ)λ 4 Here, λ is the wavelength, ε(λ ) is the molar extinction coefficient.

[0291] First, FIG. 47(a) shows the second phosphorescent compound 113Db of the light-emitting element 4, [Ir(dmd ppr-P)2(dibm)] and ε(λ)λ 4 A graph showing The molar extinction coefficient ε(λ) does not have a significant peak in the long wavelength region. On the other hand, ε(λ)λ 4 In the graph, the maximum value at 509 nm and the maximum values ​​at 550 nm and 605 nm are There is a peak with a shoulder near m. This peak is [Ir(dmdppr-P) 2(dibm)], and this peak corresponds to the triplet MLCT absorption of the first phosphorescent compound 11. By overlapping the 3D emission peaks, the efficiency of energy transfer is greatly improved. This becomes possible.

[0292] FIG. 47(b) shows the first phosphorescent compound 113Da of the light-emitting element 5, which is Ir(tBupp The PL spectrum F(λ) of the second phosphorescent compound 113Db, [Ir(dm ε(λ)λ of dppr-P)2(dibm)] 4 The graph below shows the results. The PL spectrum of Ir(tBuppm)3 shows the peak of F(λ) and the peak of [Ir(dm ε(λ)λ of dppr-P)2(dibm)] 4 What is the peak with the longest wavelength maximum? This combination has a large overlap, and energy transfer is extremely efficient. In addition, the emission of the first phosphorescent compound, Ir(tBuppm)3, was The peak is at 540 nm and is the second phosphorescent compound 113Db [Ir(dmdp ε(λ)λ of pr-P)2(dibm)] 4 The long wavelength maximum in the spectrum representing Since it exists at 509 nm, the difference is 31 nm. Since 9 nm corresponds to 2.44 eV, the difference is 0.14 eV, which is slightly less than 0.2 eV. The small difference in the peak positions suggests that efficient energy transfer occurs. In addition, ε(λ)λ of [Ir(dmdppr-P)2(dibm)] is 4 A space that represents The long-wavelength maximum (maximum C) in the t-band and the emission spectrum of Ir(tBuppm)3. The F(λ) values ​​are almost completely overlapped, but the ε (λ)λ 4 The peak with the maximum value C in the spectrum representing The spectrum on the long wavelength side and the emission spectrum of Ir(tBuppm)3 F( λ) have a large overlap, which allows for very good energy transfer.

[0293] Next, in FIG. 48(a), the first phosphorescent compound 113Da of the light-emitting element 5 is Ir(tB The molar extinction coefficient ε(λ) of uppm3 and ε(λ) 4 The graph shows the relationship between ε(λ )λ 4 In the graph, there are maxima with large intensities at 409 and 465 nm, and There is a peak with a shoulder at 4 nm. This peak is Ir(tBuppm)3 Triplet MLCT absorption, and the emission peak of the energy donor is superimposed on this peak. This makes it possible to greatly increase the efficiency of energy transfer.

[0294] In the light-emitting element 5 of this example, the first host material 2mDBTPDBq-II and the first organic compound PCBA1BP form an exciplex 113Ec, and the exciplex Energy is supplied from the phosphorescent compound 113Ec to the first phosphorescent compound 113Da. Figure 23 shows the results of the analysis of 2mDBTPDBq-II, PCBA1BP, and their mixed membranes. (mass ratio 0.8:0.2) -II and the first organic compound PCBA1BP form the exciplex 113Ec. In addition, Figure 48(b) shows the PL spectrum F(λ) of the exciplex and the first ε(λ)λ of the phosphorescent compound Ir(tBuppm)3, 113Da 4 A graph showing From this graph, it is clear that the peak of the PL spectrum F(λ) of the exciplex exists at the half-peak. A part of the wavelength range with an intensity of ε(λ)λ of Ir(tBuppm)3 4 The longest wavelength of The peaks overlap with a portion of the wavelength range having half the intensity at the peaks on the side of the peaks. This shows that this is a combination that allows for efficient energy transfer.

[0295] Figure 49 shows the PL spectrum of the exciplex F(λ) and the PL spectrum of Ir(tBuppm)3. F(λ), PL spectrum F(λ) of [Ir(dmdppr-P)2(dibm)] ), ε(λ)λ of Ir(tBuppm)3 4 , [Ir(dmdppr-P)2(dibm )] of ε(λ) 4 The PL spectrum of the exciplex and Ir( tBuppm)3ε(λ)λ 4 Using the overlap with (near the maximum A), Ir (tBuppm)3, and the PL spectrum of Ir(tBuppm)3 and [Ir(d mdppr-P)2(dibm)] 4 Overlap with (maximum C to 650 nm (nearby) from Ir(tBuppm)3 to [Ir(dmdppr-P)2(dibm) ]. It can be seen that energy can be transferred stepwise from the exciplex to the second Direct energy transfer to the phosphorescent compound [Ir(dmdppr-P)2(dibm)] This can be seen in Figure 49 by using the (dibm)] triplet MLCT absorption band (near maximum C) of the exciplex PL spectrum F(λ) and [Ir(dmdppr-P)2(dibm)] are both ε(λ)λ 4 are overlapping This is because.

[0296] The device characteristics of these light-emitting devices were measured. The measurements were performed at room temperature (25°C). The atmosphere was very friendly.

[0297] FIG. 35 shows the luminance vs. current efficiency characteristics of the light-emitting element 4. FIG. 36 shows the voltage vs. luminance characteristics. The luminance vs. external quantum efficiency characteristics are shown in FIG. 37. The luminance vs. power efficiency characteristics are shown in FIG. As shown in.

[0298] As described above, it was found that the light-emitting element 4 exhibited excellent element characteristics. In particular, as shown in FIG. 7. As can be seen from FIG. 38, it has very good luminous efficiency, and the external quantum efficiency is practical brightness ( 1000cd / m 2 ), a high value of over 20% was shown. The brightness is around 50cd / A and the power efficiency is also very good, at around 50lm / W.

[0299] FIG. 39 shows the emission spectrum when a current of 0.1 mA is applied to the light-emitting element 4. In FIG. 39, the horizontal axis represents wavelength (nm) and the vertical axis represents emission intensity (arbitrary unit). The light-emitting element 4 emits green wavelength light derived from [Ir(tBuppm)2(acac)] and [Ir( The light emitted contains a balanced amount of red wavelength light derived from It was found to show a spectrum.

[0300] FIG. 40 shows the luminance vs. current efficiency characteristics of the light-emitting element 5. FIG. 41 shows the voltage vs. luminance characteristics. The luminance vs. external quantum efficiency characteristics are shown in FIG. 42. The luminance vs. power efficiency characteristics are shown in FIG. As shown in.

[0301] As described above, it was found that the light-emitting element 5 exhibited excellent element characteristics. In particular, as shown in FIG. 2. As can be seen from FIG. 43, it has very good luminous efficiency, and the external quantum efficiency is greater than the practical brightness ( 1000cd / m 2 ), a high value of around 25% was shown. The brightness is around 65cd / A and the power efficiency is also very good, at around 70lm / W.

[0302] FIG. 44 shows the emission spectrum when a current of 0.1 mA is applied to the light-emitting element 5. In FIG. 44, the horizontal axis represents wavelength (nm) and the vertical axis represents emission intensity (arbitrary unit). The light-emitting element 5 emits green wavelength light derived from [Ir(tBuppm)2(acac)] and [Ir( The light emitted contains a balanced amount of red wavelength light derived from It was found to show a spectrum.

[0303] As described above, the light-emitting element 4 and the light-emitting element 5 according to one embodiment of the present invention have good luminous efficiency. It has also been found that this is a light-emitting device that can obtain well-balanced light from two types of luminescent center substances. It was.

[0304] (Reference example 1) The organometallic complex used in the above embodiment, bis[2-(6-tert-butyl-4-pyrimidinyl) 2,4-Pentanedionato-κN3)phenyl-κC] 2 O,O') Iridescent The following is an example of the synthesis of Ir(tBuppm)2(acac). The structure of [Ir(tBuppm)2(acac)] is shown below.

[0305] [ka]

[0306] <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.

[0307] [ka]

[0308] <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, 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.

[0309] [ka]

[0310] 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 obtain The target product was obtained as a yellow powder (yield 68%). The synthesis scheme of step 3 is shown below.

[0311] [ka]

[0312] 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.

[0313] 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).

[0314] (Reference example 2) In this reference example, the organometallic iridium complex used in the examples, bis{4,6-dimethyl-2 -[3-(3,5-dimethylphenyl)-5-phenyl-2-pyrazinyl-κN]phenyl {2,6-dimethyl-3,5-heptanedionato-κ} 2 O,O'') Iridescent Regarding the synthesis method of Ir(III) (abbreviation: [Ir(dmdppr-P)2(dibm)]) The structure of [Ir(dmdppr-P)2(dibm)] (abbreviation) is as follows: As shown in.

[0315] [ka]

[0316] <Step 1: 2,3-bis(3,5-dimethylphenyl)pyrazine (abbreviation: Hdmdp Synthesis of pr) First, 5.00 g of 2,3-dichloropyrazine and 10 g of 3,5-dimethylphenylboronic acid were .23g, sodium carbonate 7.19g, bis(triphenylphosphine)palladium(I I) Dichloride (abbreviation: Pd(PPh3)2Cl2) 0.29 g, water 20 mL, acetonitrile 20 mL of trifluoromethane was placed in a recovery flask equipped with a reflux condenser, and the inside of the flask was replaced with argon. The reaction vessel was heated by irradiating it with microwaves (2.45 GHz, 100 W) for 60 minutes. Here, 2.55 g of 3,5-dimethylphenylboronic acid and 1.80 g of sodium carbonate are added. 0.070 g of Pd(PPh3)2Cl2, 5 mL of water, and 5 mL of acetonitrile were added to a flask. Then, heat it again with microwaves (2.45GHz, 100W) for 60 minutes. did.

[0317] Thereafter, water was added to this solution, and the organic layer was extracted with dichloromethane. The mixture was washed with saturated aqueous sodium bicarbonate solution, water, and saturated saline, and then dried over magnesium sulfate. The dried solution was filtered. The solvent was removed by distillation, and the resulting residue was dissolved in hexane. Flash column chromatography was performed using xanthene:ethyl acetate = 5:1 (volume ratio) as the developing solvent. The solvent was removed, and the resulting solid was purified by filtration using a 10:1 mixture of dichloromethane and ethyl acetate. The product was purified by flash column chromatography using 100% (volume ratio) of 1 as a developing solvent. The pyrazine derivative Hdmdppr (abbreviation) was obtained (white powder, 44% yield). The microwave irradiation was performed using a microwave synthesis device (Discover, manufactured by CEM). The synthesis scheme of compound 1 is shown in (a-1) below.

[0318] [ka]

[0319] <Step 2: 2,3-bis(3,5-dimethylphenyl)-5-phenylpyrazine (abbreviation Synthesis of Hdmdppr-P) First, 4.28 g of Hdmdppr (abbreviation) obtained in step 1 above and 80 ml of dry THF L was placed in a three-neck flask and the inside was replaced with nitrogen. After cooling the flask on ice, phenyllithium ( 9.5 mL of 1.9 M butyl ether solution was added dropwise and the mixture was stirred at room temperature for 23.5 hours. The liquid was poured into water and extracted with chloroform. The obtained organic layer was washed with water and saturated saline, and The mixture was dried over magnesium oxide, and manganese oxide was added to the resulting mixture, which was then stirred for 30 minutes. The solution was then filtered and the solvent was removed by distillation. The resulting residue was mixed with dichloromethane as a developing solvent. The desired pyrazine derivative, Hdmdppr, was obtained by purifying the compound using silica gel column chromatography. The synthesis scheme of step 2 is shown below (a -2).

[0320] [ka]

[0321] <Step 3: Di-μ-chloro-tetrakis{4,6-dimethyl-2-[3-(3,5- Dimethylphenyl)-5-phenyl-2-pyrazinyl-κN]phenyl-κC}diylidin Synthesis of Ir(III) (abbreviation: [Ir(dmdppr-P)2Cl]2) Next, 15 mL of 2-ethoxyethanol, 5 mL of water, and the Hdmdp obtained in step 2 above were pr-P (abbreviation) 1.40 g, iridium chloride hydrate (IrCl3·H2O) (Sigma Put 0.51 g of a-Aldrich into a recovery flask equipped with a reflux condenser, and The inside was replaced with argon. After that, microwaves (2.45 GHz, 100 W) were irradiated for 1 hour. After the solvent was removed by distillation, the resulting residue was suction filtered and washed with ethanol. The complex [Ir(dmdppr-P)2Cl]2 (abbreviation) was obtained (reddish brown powder, 58% yield). The synthetic scheme for step 3 is shown below in (a-3).

[0322] [ka]

[0323] <Step 4: Bis{4,6-dimethyl-2-[3-(3,5-dimethylphenyl)-5 -phenyl-2-pyrazinyl-κN]phenyl-κC}(2,6-dimethyl-3,5-phenyl Butanedionate-κ 2 O,O'') Iridium(III) (abbreviation: [Ir(dmdppr Synthesis of -P)2(dibm)] Furthermore, 30 mL of 2-ethoxyethanol and the binuclear complex [Ir(d mdppr-P)2Cl]20.94g, diisobutyrylmethane (abbreviation: Hdibm) 0.23g of sodium chloride and 0.52g of sodium carbonate were placed in a recovery flask equipped with a reflux condenser. The inside of the container was replaced with argon. Then, microwaves (2.45 GHz, 120 W) were used for 60 minutes. The solvent was removed, and the resulting residue was filtered with ethanol. The solid was washed with water and ethanol, and then recrystallized in a mixed solvent of dichloromethane and ethanol. By crystallizing the organometallic complex [Ir(dmdppr-P)2(dibm)] of the present invention, (abbreviation) was obtained as a dark red powder (yield 75%). The synthesis scheme for step 4 is shown below (a -4).

[0324] [ka]

[0325] The dark red powder obtained by the above synthesis method was analyzed by nuclear magnetic resonance spectroscopy ( 1 H-NMR The analytical results are shown below. From the results, it was found that the organometallic complex [Ir(dmdp It was found that the compound (abbreviation): pr-P)2(dibm)] was obtained.

[0326] 1 H-NMR.δ(CDCl3):0.79(d,6H),0.96(d,6H),1 .41(s,6H),1.96(s,6H),2.24-2.28(m,2H),2.4 1(s,12H),5.08(s,1H),6.46(s,2H),6.82(s,2H ),7.18(s,2H),7.39-7.50(m,10H),8.03(d,4H) ,8.76(s,2H). [Explanation of symbols]

[0327] 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 113a first light-emitting layer 113Da The first phosphorescent compound 113Ha First host material 113b Second light-emitting layer 113Db Second phosphorescent compound 113Hb Second host material 113A First organic compound 113Ec exciplex 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 EL layer 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 light-emitting layer between a first electrode and a second electrode, the light-emitting layer including a first compound, a second compound that forms an exciplex with the first compound, and a phosphorescent compound; The ε(λ)λ of the phosphorescent compound ４ The wavelength of the longest maximum value of the function expressed by the formula (1) overlaps with the emission spectrum of the exciplex. (where ε(λ) represents the molar absorption coefficient and is a function of wavelength λ.)

2. a light-emitting layer between a first electrode and a second electrode, the light-emitting layer including a first compound having any one of an aromatic amine skeleton, a carbazole skeleton, a thiophene skeleton, and a furan skeleton, a second compound forming an exciplex with the first compound, and a phosphorescent compound; The ε(λ)λ of the phosphorescent compound ４ The wavelength of the longest maximum value of the function expressed by the formula (1) overlaps with the emission spectrum of the exciplex. (where ε(λ) represents the molar absorption coefficient and is a function of wavelength λ.)

3. a light-emitting layer having a first compound, a second compound that forms an exciplex with the first compound, and an iridium complex between a first electrode and a second electrode; The ε(λ)λ of the iridium complex ４ The wavelength of the longest maximum value of the function expressed by the formula (1) overlaps with the emission spectrum of the exciplex. (where ε(λ) represents the molar absorption coefficient and is a function of wavelength λ.)

4. a light-emitting layer between a first electrode and a second electrode, the light-emitting layer including a first compound having any one of an aromatic amine skeleton, a carbazole skeleton, a thiophene skeleton, and a furan skeleton, a second compound forming an exciplex with the first compound, and an iridium complex; The ε(λ)λ of the iridium complex ４ The wavelength of the longest maximum value of the function expressed by the formula (1) overlaps with the emission spectrum of the exciplex. (where ε(λ) represents the molar absorption coefficient and is a function of wavelength λ.)

5. In claim 3 or claim 4, The light-emitting device, wherein two of the three ligands in the iridium complex are the same ligand and one is a different ligand.

6. In any one of claims 1 to 5, The light-emitting device, wherein the second compound is a heterocyclic compound.

7. A lighting device comprising the light-emitting element according to claim 1 .

8. 7. A light emitting device comprising: the light emitting element according to claim 1; and a means for controlling the light emitting element.

9. 7. A display device comprising the light-emitting element according to claim 1 in a display portion, and means for controlling the light-emitting element.

10. 7. An electronic device comprising the light-emitting element according to claim 1.

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