Light-emitting element

Abstract

To provide a light-emitting element including a plurality of light-emitting dopants emitting light with balance and having high luminous efficiency, and a light-emitting device, a display device, an electronic apparatus, and an illumination device with reduced consumption power by the use of the aforementioned light-emitting element.SOLUTION: A light-emitting element includes a light-emitting layer in which a plurality of light-emitting layers containing different phosphorescence emitting materials are stacked. The light-emitting layer containing a light-emitting material exhibiting light emission with long wavelengths includes two kinds of carrier transport compounds with different transport polarities. The triplet excited energy of a host material in the light-emitting layer on the short wavelength side is higher than that of any one or all of the carrier transport compounds.SELECTED DRAWING: Figure 1

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 lights. 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 it is theoretically possible for phosphorescent compounds to achieve an internal quantum efficiency of 100%, It is difficult to achieve high efficiency without optimizing the structure and combination with other materials. In particular, we have developed a method for producing luminescent devices that use multiple phosphorescent compounds with different bands (luminescent colors) as luminescent dopants. In optical devices, it is of course necessary to take into account energy transfer. It is difficult to obtain high efficiency light emission without optimizing the efficiency of the device itself. In Reference 1, even if all the emitting dopants are phosphorescent, the external quantum efficiency is only 3-4%. This means that even if the light extraction efficiency is taken into account, the internal quantum efficiency is less than 20%. It must be said that this is a low value for a phosphorescent light-emitting device.

[0012] In addition to increasing the luminous efficiency, it is also possible to develop a multicolor light-emitting device using dopants with different luminescent colors. In this case, it is necessary for the dopants of each luminescent color to emit light in a well-balanced manner. Achieving efficiency while also balancing the emission of each dopant is not an easy task.

[0013] In view of the above, in one embodiment of the present invention, in a light-emitting element using a plurality of light-emitting dopants, The present invention aims to provide a light-emitting device that emits light with a well-balanced number of dopants and has high luminous efficiency. In addition, one embodiment of the present invention aims to reduce power consumption by using the above-described light-emitting element. The present invention aims to provide a light-emitting device, a display device, an electronic device, and a lighting device each having reduced light emission. .

[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, a light-emitting device in which each of a plurality of light-emitting layers has a different phosphorescent material is provided. Among the multiple light-emitting layers, the light-emitting layers containing a light-emitting material exhibiting long wavelength light emission are each It contains two types of carrier transport compounds with different polarities, and among the multiple light-emitting layers, it is the short-wavelength light-emitting The light-emitting layer containing the light-emitting material exhibiting the triplet excited states contains a host material. The triplet excitation energy is higher than any or all of the above carrier transport compounds. Thus, the present invention provides a light-emitting device having a high energy transfer efficiency between the hosts. By applying a combination of host materials and carrier transport compounds that increase the efficiency, A light-emitting element according to one embodiment of the present invention can be obtained.

[0016] That is, one embodiment of the present invention is a light-emitting device in which a first phosphorescent compound and a first host are disposed between an anode and a cathode. a first light-emitting layer including a second phosphorescent compound, a first electron transport compound, and a first and a second light-emitting layer containing a hole-transporting compound of the formula (1), is longer than the emission wavelength of the first phosphorescent compound and is the triplet excitation wavelength of the first host material. The electromotive energy is generated by three of the first electron transporting compound and the first hole transporting compound. The first light-emitting layer and the second light-emitting layer are provided in contact with each other. It is an optical element.

[0017] Another aspect of the present invention is a light-emitting element having the above-mentioned structure, further comprising: The compound and the first hole transporting compound form an exciplex. .

[0018] Another aspect of the present invention is a light-emitting element having the above-described structure, wherein the first host material is the first light-emitting layer is disposed on the cathode side of the second light-emitting layer; The light emitting device is characterized by the above.

[0019] Another aspect of the present invention is a light-emitting element having the above-described structure, wherein the first host material is a hole transporting compound, and the first light-emitting layer is provided on the anode side of the second light-emitting layer. The light emitting device is characterized by the above.

[0020] Another aspect of the present invention is a light-emitting element having the above-described structure, wherein the first light-emitting layer is The second host material is a hole transporting compound, and the second host material is a hole transporting compound. The triplet excitation energy of the material is determined by the first electron transport compound and the first hole transport compound. The triplet excitation energy of the light-emitting element is equal to or higher than any one of the triplet excitation energies of the light-emitting element.

[0021] Another aspect of the present invention is a light-emitting element having the above-described structure, wherein the first light-emitting layer is The second host material is an electron transporting compound, and the second host material is an electron transporting compound. The triplet excitation energy of the material is determined by the first electron transport compound and the first hole transport compound. The triplet excitation energy of the light-emitting element is equal to or higher than any one of the triplet excitation energies of the light-emitting element.

[0022] Another aspect of the present invention is a light-emitting element having the above-described structure, The second host material is a light-emitting element that forms an exciplex.

[0023] In another embodiment of the present invention, a first phosphorescent compound and a first host are disposed between an anode and a cathode. a first light-emitting layer including a second phosphorescent compound, a first electron-transporting compound, and a first a second light-emitting layer comprising a third phosphorescent compound and a second electron-transporting compound; a third light-emitting layer comprising a second phosphorescent compound and a second hole-transporting compound; The emission wavelength of the third phosphorescent compound is longer than the emission wavelength of the first phosphorescent compound. The emission wavelength of the first host compound is longer than the emission wavelength of the second phosphorescent compound. The triplet excitation energy of the material is determined by the first electron transport compound and the first hole transport compound. and the first light-emitting layer, the second light-emitting layer, and the third light-emitting layer are This is a light emitting element in which optical layers are provided in this order in contact with each other.

[0024] In another embodiment of the present invention, a first phosphorescent compound and a first host are disposed between an anode and a cathode. a first light-emitting layer including a second phosphorescent compound, a first electron transport compound, and a first a second light-emitting layer comprising a third phosphorescent compound and a second electron-transporting compound; a third light-emitting layer including a second phosphorescent compound and a second hole-transporting compound; The emission wavelength of the phosphorescent compound is longer than the emission wavelength of the first phosphorescent compound, and the third phosphorescent compound The emission wavelength of the compound is longer than the emission wavelength of the second phosphorescent compound, and the first phosphorescent compound The triplet excitation energy of the material is determined by the first electron transport compound and the first hole transport compound. The triplet excitation energy of the first electron transporting compound and the first The triplet excitation energy of the hole transporting compound is The triplet excitation energy of the first emitting layer and the second emitting layer is equal to or higher than the triplet excitation energy of any one of the transport compounds. The light emitting element has a first light emitting layer and a second light emitting layer provided in this order in contact with each other.

[0025] Another aspect of the present invention is a light-emitting element having the above-mentioned structure, further comprising: The compound and the first hole transporting compound form an exciplex, and the second electron transporting compound and the second The light-emitting element is characterized in that the hole-transporting compound forms an exciplex.

[0026] Another aspect of the present invention is a light-emitting element having the above-described structure, wherein the first host material is the first light-emitting layer is disposed on the cathode side of the second light-emitting layer; The light emitting device is characterized by the above.

[0027] Another aspect of the present invention is a light-emitting element having the above-described structure, wherein the first host material is a hole transporting compound, and the first light-emitting layer is provided on the anode side of the second light-emitting layer. The light emitting device is characterized by the above.

[0028] Another aspect of the present invention is a light-emitting element having the above-described structure, wherein the first light-emitting layer is The second host material is a hole transporting compound, and the second host material is a hole transporting compound. The triplet excitation energy of the material is determined by the first electron transport compound and the first hole transport compound. The triplet excitation energy of the light-emitting element is equal to or higher than any one of the triplet excitation energies of the light-emitting element.

[0029] Another aspect of the present invention is a light-emitting element having the above-described structure, wherein the first light-emitting layer is The second host material is an electron transporting compound, and the second host material is an electron transporting compound. The triplet excitation energy of the material is determined by the first electron transport compound and the first hole transport compound. The triplet excitation energy of the light-emitting element is equal to or higher than any one of the triplet excitation energies of the light-emitting element.

[0030] Another aspect of the present invention is a light-emitting element having the above-described structure, The second host material is a light-emitting element that forms an exciplex.

[0031] Another aspect of the present invention is a light-emitting element having the above-mentioned structure, further comprising: The light-emitting device is characterized in that the first compound and the second electron-transporting compound are the same.

[0032] Another aspect of the present invention is a light-emitting element having the above-described structure, comprising: a first hole-transporting layer; The light-emitting element is characterized in that the first compound and the second hole-transporting compound are the same.

[0033] Another aspect of the present invention is a light-emitting element having the above-mentioned structure, further comprising: The first and second electron transporting compounds are the same, and the first and second hole transporting compounds are the same. The light-emitting device is characterized in that the hole transporting compound is the same.

[0034] Another aspect of the present invention is a light-emitting element having the above-described structure, wherein the thickness of the second light-emitting layer is The light-emitting element has a thickness of 2 nm or more and 20 nm or less.

[0035] Another aspect of the present invention is a light-emitting element having the above-described structure, wherein the thickness of the second light-emitting layer is The light-emitting element has a thickness of 5 nm or more and 10 nm or less.

[0036] 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.

[0037] In this specification, the term "light-emitting device" includes an image display device using a light-emitting element. In addition, the light-emitting device is provided with a connector, such as anisotropic conductive film, TCP (Tape Carrier The module has a printed wiring board at the end of the TCP. The COG (Chip On Glass) method is used for the module or light emitting device. Modules on which ICs (integrated circuits) are directly mounted are also included in the category of light-emitting devices. This also includes light-emitting devices used in lighting fixtures, etc. Effect of the Invention

[0038] According to one embodiment of the present invention, a light-emitting element with high emission efficiency can be provided. Light emitting devices, light emitting display devices, electronic devices, and the like that consume less power by using optical elements. and a lighting device. [Brief description of the drawings]

[0039] [Figure 1] 1 is a conceptual diagram of a light-emitting element. [Diagram 2] 1 is a conceptual diagram of a light-emitting element. [Diagram 3] FIG. 1 is a conceptual diagram of an active matrix light-emitting device. [Figure 4] FIG. 1 is a conceptual diagram of a passive matrix light-emitting device. [Diagram 5]FIG. 1 is a conceptual diagram of an active matrix light-emitting device. [Figure 6] FIG. 1 is a conceptual diagram of an active matrix light-emitting device. [Figure 7] A conceptual diagram of a lighting device. [Figure 8] A diagram showing an electronic device. [Figure 9] A diagram showing an electronic device. [Figure 10] FIG. [Figure 11] FIG. [Figure 12] 1 is a diagram illustrating an in-vehicle display device and a lighting device. [Figure 13] A diagram showing an electronic device. [Figure 14] Emission spectrum of light-emitting element 1. [Figure 15] Luminance-current efficiency characteristics of light-emitting element 1. [Figure 16] Luminance-external quantum efficiency characteristics of light-emitting element 1. [Figure 17] Voltage-luminance characteristics of light-emitting element 1. [Figure 18] Luminance-power efficiency characteristics of light-emitting element 1. [Figure 19] 4 shows emission spectra of the light-emitting element 2 and the light-emitting element 3. [Figure 20] Luminance-current efficiency characteristics of Light-emitting Element 2 and Light-emitting Element 3. [Figure 21] luminance-external quantum efficiency characteristics of light-emitting element 2 and light-emitting element 3. [Figure 22] Voltage-luminance characteristics of the light-emitting element 2 and the light-emitting element 3. [Figure 23] Luminance-power efficiency characteristics of Light-emitting element 2 and Light-emitting element 3. [Figure 24] Emission spectrum of light-emitting element 4. [Diagram 25] Luminance-current efficiency characteristics of light-emitting element 4. [Figure 26] Luminance-external quantum efficiency characteristics of light-emitting element 4. [Figure 27] Voltage-luminance characteristics of light-emitting element 4. [Figure 28] Luminance-power efficiency characteristics of light-emitting element 4. [Figure 29] Normalized luminance change over time of light-emitting element 4. [Diagram 30] Phosphorescence spectrum of 35DCzPPy. [Diagram 31] Phosphorescence spectrum of PCCP. [Diagram 32] Phosphorescence spectrum of 2mDBTPDBq-II. [Diagram 33] Phosphorescence spectrum of PCBA1BP. [Diagram 34] Phosphorescence spectrum of 2mDBTBPDBq-II. [Diagram 35] Phosphorescence spectrum of PCBNBB. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0040] 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.

[0041] (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. The compound is used to efficiently emit light from both the first phosphorescent compound and the second phosphorescent compound. By doing so, a highly efficient multi-color light emitting element can be obtained.

[0042] 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.

[0043] 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.

[0044] On the other hand, in a light-emitting element according to one embodiment of the present invention, a first phosphorescent compound and a first hologram are provided between a pair of electrodes. a first light-emitting layer including a phosphorescent material and a second light-emitting layer including a phosphorescent material having a longer wavelength than the first phosphorescent compound; A second phosphorescent compound including a first electron transport compound and a first hole transport compound. The triplet excitation energy of the first host material is is a triplet excitation energy of either the first electron transporting compound or the first hole transporting compound. The first light-emitting layer and the second light-emitting layer are in contact with each other, unlike the tandem structure. It is provided.

[0045] FIG. 1 is a schematic diagram showing the element structure of the light-emitting element according to one embodiment of the present invention. The electrode 101, the second electrode 102, and the EL layer 103 are shown. At least a light-emitting layer 113 is provided, and other layers may be provided as appropriate. In the present embodiment, a hole injection layer 111, a hole transport layer 112, an electron transport layer 114 and an electron injection layer 11 The first electrode 101 functions as an anode. The second electrode 102 functions as a cathode.

[0046] 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 13Db, a first host material 113Ha1, a first carrier transporting compound 113H1, The carrier transport compound 113H2 of the second light-emitting element is shown in FIG. This is a schematic diagram in which the layer 113a further contains a second host material 113Ha2. The first host material 113Ha1 and the first carrier transporting compound 113H1 are the same. The second host material 113Ha2 and the second carrier transporting compound 113Ha3 may be different materials. The first light-emitting layer 113a and the second light-emitting layer 113H2 may be made of the same material or different materials. Either of the optical layers 113b may be the anode side or the cathode side. Either the first host material 113Ha1 or the second host material 113Ha2 is an electron transporting compound. The first carrier transport compound 113 is a compound having a hole transporting property, and the other is a compound having a hole transporting property. One of the H1 and the second carrier transporting compound 113H2 is an electron transporting compound, and the other is It is a hole transporting compound.

[0047] The recombination region in the light-emitting layer is set by the first host material 113Ha1 contained in each light-emitting layer, The second host material 113Ha2, the first carrier transporting compound 113H1 and the second carrier The ratio of the rear transport compound 113H2 can be adjusted. A first host material 113Ha1, a second host material 113Ha2, and a first carrier transport compound 113H As described above, one of the compounds 1 and 113H2 is an electron transport compound. The compound having a hole transporting property is a compound having a hole transporting property. This allows the carrier transport properties of each light-emitting layer to be adjusted, resulting in the control of the recombination region. can be easily carried out.

[0048] When excitons are generated directly in the second light-emitting layer 113b, the first phosphorescent compound 11 Since it is difficult to obtain 3D light emission, the recombination region of the carriers is located inside the first light-emitting layer 113a, is preferably in the vicinity of the interface between first light-emitting layer 113a and second light-emitting layer 113b.

[0049] In this way, the carrier recombination region is formed between the first light emitting layer 113a and the second light emitting layer 113b. In order to make the first light-emitting layer 113a near the interface, when the first light-emitting layer 113a is on the anode side, When the first light-emitting layer 113a is on the cathode side, the second light-emitting layer 113b is made to have hole transport properties, and when the first light-emitting layer 113a is on the cathode side, the second light-emitting layer 113b is made to have electron transport properties. Then, by making the second light-emitting layer 113b have the opposite transport properties, The coupling region may be near the interface between the first light-emitting layer 113a and the second light-emitting layer 113b. In order to make the carrier recombination region inside the first light emitting layer 113a, the above-mentioned configuration Based on this, the bipolar property of the first light-emitting layer 113a may be improved.

[0050] In the case of the configuration shown in FIG. 1(a), when the first light-emitting layer 113a is on the anode side, The first host material 113Ha1 is hole transporting, and the second host material 11 3Ha1 is made electron transporting, and the second light emitting layer 113b is made of the first carrier transporting compound 113 By changing the mixing ratio of H1 and the second carrier transport compound 113H2, The carrier transport property may be adjusted to be opposite to that of the first light-emitting layer 113a.

[0051] In the case of the second light-emitting layer 113b and the first light-emitting layer 113a as shown in FIG. The mixing ratio of the electron transporting compound and the hole transporting compound contained in the light emitting layer is changed. The transportability of each can be adjusted by

[0052] However, the recombination region is within the first light-emitting layer 113a or between the first light-emitting layer and the second light-emitting layer. If it is an interface, then the second phosphorescent compound 113D is more sensitive to the first phosphorescent compound. In one embodiment of the present invention, the emission intensity ratio of b may become small. In the case of the structure (a), the triplet excitation energy of the first host material 113Ha1 is Either the first carrier transporting compound 113H1 or the second carrier transporting compound 113H2 Select a combination of materials so that one or both of the following are greater than the other: A part of the triplet excitation energy due to the recombination of carriers is transferred to the first host material 113H a1 to the first carrier transport compound 113H1 and the second carrier transport compound 113H 2 or both triplet excited levels of the second phosphorescent compound 113Db can be made to emit light.

[0053] As shown in FIG. 1B, the first light-emitting layer 113a further includes a second host material 113H. When a2 is contained, the triplet excitation energy of the second host material 113Ha2 is also Either the carrier transport compound 113H1 or the second carrier transport compound 113H2 This allows the recombination of carriers to be prevented. A part of the triplet excitation energy is transferred from the second host material 113Ha2 to the first carrier Either or both of the transport compound 113H1 and the second carrier transport compound 113H2 The second phosphorescent compound 113Db can then emit light by transferring the excited triplet level of the first phosphorescent compound 113Db. do.

[0054] Thus, the triplet excitation energy, which accounts for 75% of the excitation energy generated by carrier recombination, By taking into consideration the transfer of excitation energy, the second phosphorescent compound 11 The 3Db emission can be obtained at a desired intensity.

[0055] On the other hand, the singlet excitation of the first host material 113Ha1 or the second host material 113Ha2 The energy is a first carrier transport compound 113H1 and a second carrier transport compound 1 If the concentration is higher than that of 13H2, the transfer occurs via the Dexter mechanism. If the first host material 113Ha1 or the second host material 113Ha2 is fluorescent, For example, energy transfer can also occur via the Förster mechanism.

[0056] Here, in order to obtain a light-emitting element with higher luminous efficiency, energy transfer to a phosphorescent compound is In this explanation, the substance that provides energy to the phosphorescent compound is called This will be referred to as a host material.

[0057] Carrier recombination occurs in both the host material and the phosphorescent compound, resulting in high luminous efficiency. To improve the efficiency of the emission, it is necessary to improve the efficiency of the energy transfer from the host material to the phosphorescent compound. Energy transfer from the host material to the phosphorescent compound can be achieved by the Dexter mechanism, the Ferroelectric mechanism, or the Two star mechanisms have been proposed.

[0058] Energy transfer efficiency from host molecules to guest molecules Φ ET is expressed by the following formula: r is the emission process (fluorescence when discussing energy transfer from a singlet excited state, triplet excited state). When discussing energy transfer from one state to another, k represents the rate constant of phosphorescence, n is a non-radiative process represents the rate constant of the excited state (thermal deactivation or intersystem crossing), and τ represents the lifetime of the excited state observed.

[0059]

number

[0060] First, from the above formula, the energy transfer efficiency Φ ET To increase the energy transfer rate constant k h * →g , other competing rate constants k r +k n (=1 / τ) is much larger than Then, the rate constant of the energy transfer, k h * →g Enlarge In order to improve the performance of both the Förster and Dexter mechanisms, The emission spectrum of a molecule (or the fluorescence spectrum when discussing energy transfer from a singlet excited state) (When discussing energy transfer from triplet excited states, phosphorescence spectrum) and guest The larger the overlap with the absorption spectrum of the molecule (phosphorescent compound in the second light-emitting layer) is good.

[0061] Here, considering the overlap between the emission spectrum of the host molecule and the absorption spectrum of the phosphorescent compound, In this regard, the absorption spectrum of the phosphorescent compound at the longest wavelength (lowest energy) is Collection is important.

[0062] It is believed to be the most important contributor to light emission in the absorption spectrum of phosphorescent compounds. The absorption band is located near the absorption wavelength corresponding to the direct transition from the ground state to the triplet excited state, This is the absorption band that appears on the longest wavelength side. The fluorescence spectrum and phosphorescence spectrum are the longest wavelengths in the absorption spectrum of phosphorescent compounds. It is considered preferable that the absorption band overlaps with the absorption band on the long side.

[0063] For example, in organometallic complexes, especially luminescent iridium complexes, the longest wavelength absorption band is In many cases, a broad absorption band appears around 500 to 600 nm. Mainly, triplet MLCT (Metal to Ligand Charge Trans sfer) transition. However, the absorption band includes the triplet π-π * Transition or singlet MLCT Some of the absorption is due to transitions, and these overlap to form the longest wavelength side of the absorption spectrum. It is believed that a broad absorption band is formed. When using complexes (especially iridium complexes), the broad spectrum at the longest wavelength is It is preferable that the absorption band of the host material largely overlaps with the emission spectrum of the host material.

[0064] First, let us consider the energy transfer from the triplet excited state of the host material. From the discussion, in the energy transfer from the triplet excited state, the phosphorescence spectrum of the host material It is sufficient that the overlap between the absorption band of the tor and the longest wavelength side of the phosphorescent compound becomes large.

[0065] However, the problem here is that the energy from the singlet excited state of the host molecule In addition to the energy transfer from the triplet excited state, the energy transfer from the singlet excited state From the above discussion, in order to efficiently transfer electrons, the phosphorescence spectrum of the host material must be In addition, the fluorescence spectrum was designed to overlap with the longest wavelength absorption band of the guest material. In other words, the fluorescent spectrum of the host material must be the same as its phosphorescent spectrum. If the host material is not designed to be in such a position, the singlet excited state and However, it is not possible to efficiently transfer energy from both the excited triplet state and the excited triplet state. become.

[0066] However, in general, the singlet excitation level and the triplet excitation level are significantly different (singlet excitation level > Triplet excitation level), the emission wavelengths of fluorescence and phosphorescence are also significantly different (fluorescence emission For example, it is often used in light-emitting devices that use phosphorescent compounds. The 4,4'-di(N-carbazolyl)biphenyl (abbreviation: CBP) that can be used is 500 nm It has a phosphorescence spectrum around 400 nm, while its fluorescence spectrum is around 400 nm. Even in this example, the fluorescence spectrum of the host material is It is extremely difficult to design a host material that has a similar phosphorescence spectrum. It is.

[0067] Also, the singlet excited level in a certain substance is at a higher energy level than the triplet excited level. Therefore, the fluorescence spectrum is close to the absorption spectrum of the longest wavelength of the guest material. The triplet excitation level of the host material at such wavelengths is lower than that of the guest material. Put away.

[0068] Here, we will discuss exciplexes, which are excited states made up of two materials. The optical spectrum is determined by the shallower HOMO level and the deeper LUMO level of the two materials. The emission spectrum is longer than that of the original substance because it is due to the difference in energy between the two. Therefore, the triplet of the two compounds forming the exciplex is The singlet excitation energy is kept higher than the triplet excitation energy of the guest material. This maximizes the energy transfer from the state.

[0069] Furthermore, since the triplet excited level and the singlet excited level are close to each other in an exciplex, Therefore, the fluorescence spectrum and phosphorescence spectrum are almost in the same position. Absorption corresponding to the transition from the singlet ground state to the triplet excited state of the guest molecule (absorption of the guest molecule The fluorescence spectrum of the exciplex is located in the broad absorption band at the longest wavelength side of the spectrum. The large overlap of both the fluorophore and phosphorescence spectra improves the energy transfer efficiency. Therefore, a light-emitting element with high light-emitting efficiency can be obtained.

[0070] In this manner, in the second light-emitting layer, the first carrier transporting compound 113H1 and the second The carrier transporting compound 113H2 is preferably a combination that forms an exciplex. Furthermore, the lowest energy absorption band of the second phosphorescent compound 113Db and the The overlap of the emission spectra of the exciplexes makes it possible to obtain light-emitting elements with better emission efficiency. In addition, the peak of the absorption band on the lowest energy side of the second phosphorescent compound 113Db The difference in energy between the wavelength and the peak wavelength of the emission spectrum of the exciplex is 0.2e If the wavelength is less than V, the overlap between the spectra becomes large, which is a preferable configuration.

[0071] In the case of the structure shown in FIG. 1(b), the first host material 113Ha1 and the second The host material 113Ha2 is preferably a combination that forms an exciplex. In addition, the lowest energy absorption band of the first phosphorescent compound and the emission spectrum of the exciplex are By overlapping the spectra, a light-emitting element having higher luminous efficiency can be obtained. The peak wavelength of the lowest energy absorption band of the phosphorescent compound 113Da of 1 and the excitation If the difference in the energy equivalent value of the peak wavelength of the emission spectrum of the complex is 0.2 eV or less, This is a preferable configuration because the overlap between the spectra is large.

[0072] As mentioned above, the emission of an exciplex occurs when the shallow exciplex is selected from the two substances that compose the exciplex. This is due to the energy difference between the HOMO level at the lower end and the LUMO level at the lower end. By using the complex as a host, the emission spectrum can be changed by changing the combination of materials. Since the wavelength can be changed, it is easy to adjust the emission to match the absorption of the phosphorescent compound on the long wavelength side. It can be easily obtained.

[0073] The first host material 113Ha1 and the second host material 113Ha2 are the first phosphorus The first phosphorescent compound 113Da is preferably at a higher concentration than the first phosphorescent compound 113Da so as not to quench the first phosphorescent compound 113Da. It is preferable that the first carrier transport compound has a high triplet excitation energy. The compound 113H1 and the second carrier transport compound 113H2 are a second phosphorescent compound 113 The second phosphorescent compound 113 has a higher triplet excitation energy than Db so as not to quench Db. It is preferable that the material has an energy.

[0074] 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.

[0075] A first host material 113Ha1, a second host material 113Ha2, a first carrier transport The first carrier transport compound 113H1 and the second carrier transport compound 113H2 can be used as the carrier transport compound 113H1. Examples of the electron transporting compound and hole transporting compound include the following compounds. Note that either the first host material 113Ha1 or the second host material 113Ha2 the first carrier transport compound is an electron transport compound and the other is a hole transport compound; Either 113H1 or the second carrier transport compound 113H2 is an electron transport compound. In addition, when selecting these combinations, the excitation It is preferable to select a combination that forms a complex.

[0076] The electron transport compound is bis(10-hydroxybenzo[h]quinolinato)beryllium. BeBq2, Bis(2-methyl-8-quinolinolato)(4-phenyl Bis(8-quinolinolato)aluminum(III)(abbreviation: BAlq) Zinc(II) (abbreviation: Znq), bis[2-(2-benzoxazolyl)phenolato] Lead(II) (abbreviation: ZnPBO), bis[2-(2-benzothiazolyl)phenolato] zinc Metal complexes such as lead(II) (abbreviation: ZnBTZ) and 2-(4-biphenylyl)-5-( 4-tert-Butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD), 3 -(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1, 2,4-Triazole (abbreviation: TAZ), 1,3-bis[5-(p-tert-butylphenyl) (phenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl]-9 H-Carbazole (abbreviation: CO11), 2,2',2''-(1,3,5-benzenetriazole yl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TPBI), 2-[ 3-(Dibenzothiophen-4-yl)phenyl]-1-phenyl-1H-benzimida Heterocyclic compounds with polyazole skeletons such as azole (abbreviation: mDBTBIm-II) and , 2-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxa Phosphorus (abbreviation: 2mDBTPDBq-II), 2-[3'-(dibenzothiophene-4-yl) 2mDBTBPD Bq-II), 2-[3'-(9H-carbazol-9-yl)biphenyl-3-yl] Dibenzo[f,h]quinoxaline (abbreviation: 2mCzBPDBq), 4,6-bis[3-( 4,6mPnP2Pm), ,6-Bis[3-(4-dibenzothienyl)phenyl]pyrimidine (abbreviation: 4,6mDB Heterocyclic compounds with diazine skeletons such as TP2Pm-II) and 3,5-bis[3-( 9H-carbazol-9-yl)phenyl]pyridine (abbreviation: 35DCzPPy), 1, 3,5-Tri[(3-pyridyl)-phen-3-yl]benzene (abbreviation: TmPyPB) Examples of heterocyclic compounds having a pyridine skeleton include π-electron deficient heteroaromatic compounds. Among the above, heterocyclic compounds having a diazine skeleton and heterocyclic compounds having a pyridine skeleton are preferred. Heterocyclic compounds are preferred because of their excellent reliability. In particular, diazines (pyrimidines and pyrazines) Heterocyclic compounds having a .DELTA..sub.3) skeleton have high electron transport properties and also contribute to reducing the driving voltage.

[0077] The hole transport compound is 4,4'-bis[N-(1-naphthyl)-N-phenylamino]bis( Phenyl (abbreviation: NPB), N,N'-bis(3-methylphenyl)-N,N'-diphenyl Nyl-[1,1'-biphenyl]-4,4'-diamine (abbreviation: TPD), 4,4'-biphenyl [N-(spiro-9,9'-bifluoren-2-yl)-N-phenylamino]biphenyl nyl (abbreviation: BSPB), 4-phenyl-4'-(9-phenylfluoren-9-yl) Triphenylamine (abbreviation: BPAFLP), 4-phenyl-3'-(9-phenylfulve oren-9-yl)triphenylamine (abbreviation: mBPAFLP), 4-phenyl-4' -(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCB A1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazole-3 -yl)triphenylamine (abbreviation: PCBBi1BP), 4-(1-naphthyl)-4' -(9-Phenyl-9H-carbazol-3-yl)-triphenylamine (abbreviation: PC BANB), 4,4'-di(1-naphthyl)-4''-(9-phenyl-9H-carbazo PCBNBB, 9,9-dimethyl-N- Phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]- PCBAF, N-phenyl-N-[4-(9-phenyl -9H-carbazol-3-yl)phenyl]-spiro-9,9'-bifluorene-2- Compounds with aromatic amine skeletons such as PCBASF (abbreviation: PCBASF) and 1,3-bis(1,3-diphenylamine) (N-carbazolyl)benzene (abbreviation: mCP), 4,4'-di(N-carbazolyl)biphenyl Phenyl (abbreviation: CBP), 3,6-bis(3,5-diphenylphenyl)-9-phenyl CzTP, 3,3'-bis(9-phenyl-9H-carbazole) Compounds with a carbazole skeleton, such as PCCP (abbreviation: PCCP), and 4,4',4''- (Benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P- II), 2,8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl )phenyl]dibenzothiophene (abbreviation: DBTFLP-III), 4-[4-(9-phenyl)dibenzothiophene (phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene ( Compounds with thiophene skeletons such as DBTFLP-IV and 4,4',4'' -(Benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviation: DBF3P-I I), 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl Compounds having a furan skeleton such as {nyl}dibenzofuran (abbreviation: mmDBFFLBi-II) Among the above, the aromatic heteroaromatic compounds are preferably π-electron-rich heteroaromatic compounds. Compounds having an amine skeleton and compounds having a carbazole skeleton have good reliability. In addition, it is preferable since it has a high hole transporting property and contributes to reducing the driving voltage.

[0078] The light-emitting element having the above-mentioned structure has good luminous efficiency and is made of a plurality of luminescent materials. The light-emitting element is capable of obtaining light emission from the tandem type. Therefore, the manufacturing process is not complicated, and the power loss due to the intermediate layer is small. It is also highly useful as an optical element.

[0079] As shown in FIG. 1(c) and (d), the light-emitting layer 113 is divided into a first light-emitting layer 113a and a second light-emitting layer 113b. Alternatively, the first light emitting layer 113b, the second light emitting layer 113c, and the third light emitting layer 113c may be formed. The relationship between 3a and the second light emitting layer 113b is as described above.

[0080] The third light-emitting layer 113c contains a third phosphorescent compound 113Dc and a third carrier-transporting The third phosphorescent compound includes a compound 113H3 and a fourth carrier transport compound 113H4. The emission wavelength of the phosphorescent compound 113Dc is longer than that of the second phosphorescent compound 113Db. In addition, the third carrier transport compound 113H3 and the fourth carrier transport compound 113H In the compound 4, one of the compounds is an electron transporting compound and the other is a hole transporting compound. The third carrier transport compound 113H3 and the fourth carrier transport compound 113H4 are used. The compounds that can be used are the first host material 113Ha1 and the second host material 113Ha2. 13Ha2, the first carrier transporting compound 113H1 and the second carrier transporting compound 1 The compounds listed as compounds that can be used as 13H2 can be used.

[0081] The third carrier transporting compound 113H3 and the fourth carrier transporting compound 113H4 are The first carrier transport compound 113H1 and the second carrier transport compound 113H2, For the same reason as in the first host material 113Ha1 and the second host material 113Ha2, It is preferable to form an exciplex. To optimize the energy transfer to the third phosphorus, the emission spectrum of the exciplex is It is preferable that the absorption bands on the longest wavelength side of the photoactive compound 113Dc overlap. The peak wavelength of the lowest energy absorption band of the phosphorescent compound 113Dc of 3 and the excitation If the difference in the energy equivalent value of the peak wavelength of the emission spectrum of the complex is 0.2 eV or less, This is a favorable configuration because the overlap between the spectra is large. Compound 113H3 and the fourth carrier transport compound 113H4 are the third phosphorescent compound 11 The third phosphorescent compound 11 has a higher triplet excitation energy than 3Dc so as not to quench 3Dc. It is preferable that the catalyst has high energy.

[0082] The third light-emitting layer 113c is disposed within the first light-emitting layer 113a or between the first light-emitting layer 113a and the second light-emitting layer 113c. The recombination energy in the recombination region near the interface of the second light-emitting layer 113b is Therefore, the first carrier transport compound 113H The triplet excitation energy of the first and second carrier transport compounds 113H2 is Either one of the carrier transport compound 113H3 and the fourth carrier transport compound 113H4 It is preferably greater than the singlet excitation energy.

[0083] The recombination region is located within the first light-emitting layer 113a or between the first light-emitting layer 113a and the second light-emitting layer 113b. In order to make the third light-emitting layer 113c in the vicinity of the interface with the second light-emitting layer 113b, the transport property of the third light-emitting layer 113c is The transporting property of the third carrier transporting compound 11 is preferably the same as that of the third carrier transporting compound 13b. The electron transport compound and the hole transport compound constituting the fourth carrier transport compound 113H4 are The carrier transport compound is a first carrier transport compound 113H1 and a second carrier transport compound 113H2. One of the electron transport compounds and hole transport compounds that make up the carrier transport compound 113H2 Or, both layers may be the same. This allows the materials constituting each layer to be common, and reduces costs. This will be advantageous in terms of business.

[0084] The light-emitting device of FIG. 1 having the configuration of the light-emitting layer 113 of FIG. 1(c) and FIG. 1(d) includes a first light-emitting layer 11 3a may be formed on the anode side or on the cathode side.

[0085] When the first light-emitting layer 113a is formed on the anode side, the first light-emitting layer 113a functions as a hole transport layer. The first light-emitting layer 113b and the third light-emitting layer 113c are electron-transporting layers. In the case of the configuration of FIG. 1(c), the transport property of the first light-emitting layer is preferably the first host. The hole transport material 113Ha1 may be a hole transport material. In this case, the first host material 113Ha1 and the second host material 113Ha2 (i.e., electron transport The thickness can be adjusted by changing the mixing ratio of the hole transporting compound and the hole transporting compound. Similarly, the second light-emitting layer 113b and the third light-emitting layer 113c also have the first carrier transport. By changing the mixing ratio of the carrier transport compound 113H1 to the fourth carrier transport compound 113H4, In this way, it is possible to obtain a light emitting layer having desired transport properties.

[0086] In addition, when the first light-emitting layer 113a is formed on the cathode side, the first light-emitting layer 113a is The second light-emitting layer 113b and the third light-emitting layer 113c are electron-transporting layers. The transport property of the first light-emitting layer 113a is preferably a layer having a structure shown in FIG. In this case, the first host material 113Ha1 may be an electron transporting material. In the case of the above-mentioned structure, the first host material 113Ha1 and the second host material 113Ha2 ( That is, the mixing ratio of the electron transport compound and the hole transport compound is changed to adjust the property. Similarly, in the second light-emitting layer 113b and the third light-emitting layer 113c, Mixture of the first carrier transporting compound 113H1 to the fourth carrier transporting compound 113H4 By varying the ratio, it is possible to obtain a light-emitting layer having the desired transport properties.

[0087] Furthermore, since energy transfer occurs via the second light-emitting layer 113b, If the film thickness of 13b is too thick, energy transfer to the third light-emitting layer 113c does not occur. Since light emission from the phosphorescent compound 113Dc cannot be obtained, the third light-emitting layer 113c In order to obtain light emission from the second light emitting layer 113b, the thickness of the second light emitting layer 113b is preferably 2 nm to 20 nm. The thickness is preferably 5 nm to 10 nm.

[0088] In addition, in the present embodiment having the configuration of the light emitting layer 113 as shown in FIG. The light-emitting device is made of a first phosphorescent compound 113Da which emits blue light, a second phosphorescent compound 113Da which emits blue light, and a The phosphorescent compound 113Db is a compound exhibiting green light emission, and the third phosphorescent compound 113Dc is By using a compound that emits red light, it is possible to achieve good white light emission (for example, in accordance with the JIS lighting standard). This white light emission also has high color rendering properties. Moreover, such white light emitting elements are highly suitable for use as lighting.

[0089] The light-emitting element having the above-mentioned structure is a light-emitting element using a plurality of light-emitting materials, and emits light. In addition, the light emission from the plurality of light-emitting substances can be uniformly distributed. Therefore, it is possible to provide a light emitting element that can provide good light performance.

[0090] (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.

[0091] 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.

[0092] 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.

[0093] 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 A transport layer, an electron injection layer, a carrier blocking layer, and the like can be appropriately combined to form the layer. In this embodiment, the EL layer 103 is a hole injection layer 102 laminated in sequence on the first electrode 101. 11, a hole transport layer 112, a light emitting layer 113, an electron transport layer 114, and an electron injection layer 115 The construction will be described below. The materials constituting each layer are specifically shown below.

[0094] The hole injection layer 111 is a layer containing a substance with high hole injection properties. Use of tungsten oxide, manganese oxide, etc. In addition, phthalocyanine (abbreviation: H2Pc) and copper phthalocyanine (abbreviation: Cu Phthalocyanine compounds such as 4,4'-bis[N-(4-diphenylamino)phthalocyanine phenyl)-N-phenylamino]biphenyl (abbreviation: DPAB), N,N'-bis{4- [bis(3-methylphenyl)amino]phenyl}-N,N'-diphenyl-(1,1' -biphenyl)-4,4'-diamine (abbreviation: DNTPD), or other aromatic amine compounds, or poly(ethylenedioxythiophene) / poly(styrenesulfonic acid) (abbreviation: PED The hole injection layer 111 can also be formed from a polymer such as OT / PSS.

[0095] 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.

[0096] 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.

[0097] 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.

[0098] 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.

[0099] 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.

[0100] 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

[0101] 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.

[0102] 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.

[0103] 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.

[0104] 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.

[0105] The light-emitting layer 113 has the structure described in the first embodiment. The light-emitting device in this form has good luminous efficiency, and the phosphorescent compounds contained therein are Regarding the main structure of the light emitting layer 113, refer to the description of the first embodiment. I want to be illuminated.

[0106] In the light-emitting layer 113, the first phosphorescent compound 113Da to the third phosphorescent compound 113Da Materials that can be used as 13Dc include those that satisfy the relationship explained in the first embodiment. There is no particular limitation as long as the combination has the above-mentioned structure. Examples of the phosphorescent compound 113Dc include the following:

[0107] Tris{2-[5-(2-methylphenyl)-4-(2,6-dimethylphenyl)-4H -1,2,4-triazol-3-yl-κN2]phenyl-κC}iridium(III ) (abbreviation: Ir(mpptz-dmp)3), tris(5-methyl-3,4-diphenyl -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'-bistrifluoromethylphenyl)pyridinato-N,C 2’ ] Iridium(III) picolinate (abbreviation: Ir(CF3ppy)2(pic)), bis [2-(4',6'-difluorophenyl)pyridinato-N,C 2’ ]Iridium (II I) Phenyl groups having electron-withdrawing groups such as acetylacetonate (abbreviation: FIracac) These include organometallic iridium complexes with iridium derivatives as ligands. A compound that exhibits phosphorescence and has an emission peak between 440 nm and 520 nm. Among the above, 4H-triazole, 1H-triazole, and imidazole are Such organometallic iridium complexes having a polyazole skeleton have high hole trapping properties. 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 has hole transport properties (specifically, the second host material is a hole transport material), This is preferable because it makes it easier to control the carrier recombination region within the first light-emitting layer. The organometallic iridium complexes with 4H-triazole skeletons are also excellent in reliability and luminescence efficiency. This is particularly preferred because

[0108] 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.

[0109] Also, (diisobutyrylmethanato)bis[4,6-bis(3-methylphenyl)pyrimidinyl] NatO]iridium(III) (abbreviation: Ir(5mdppm)2(dibm)), bis[4 ,6-Bis(3-methylphenyl)pyrimidinato](dipivaloylmethanato)iridium (III) (abbreviation: Ir(5mdppm)2(dpm)), bis[4,6-di(naphthalene (1-phenyl-1-yl)pyrimidinato](dipivaloylmethanato)iridium(III) (abbreviation: Organometallic iridium with a pyrimidine backbone, such as Ir(d1npm)2(dpm) Complexes and (acetylacetonato)bis(2,3,5-triphenylpyrazinate)iridium Ir(tppr)2(acac)), bis(2,3,5-triphenylphosphine(III) Nylpyrazinato)(dipivaloylmethanato)iridium(III) (abbreviation: Ir(tpp r) 2(dpm)), (acetylacetonato)bis[2,3-bis(4-fluorophenyl Ir(Fdpq)2(acac) Organometallic iridium complexes with pyrazine skeletons such as tris(1-phenylisoxid Norinato-N,C 2’ ) Iridium(III) (abbreviation: Ir(piq)3), bis(1- Phenylisoquinolinato-N,C 2’ ) Iridium(III) acetylacetonate (abbreviation Name: Organometallic iridium with a pyridine skeleton, such as Ir(piq)2(acac) In addition to the complex, 2,3,7,8,12,13,17,18-octaethyl-21H,23H- Platinum complexes such as porphyrin platinum(II) (abbreviation: PtOEP) and tris(1,3- Diphenyl-1,3-propanedionato)(monophenanthroline)europium(II) I) (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). A compound that exhibits red phosphorescence and has an emission peak between 600 nm and 700 nm. Among the above, organometallic iridium compounds having a diazine skeleton such as pyrimidine and pyrazine are preferred. The diazine complex has a weak hole trapping ability and a strong electron trapping ability. The second phosphorescent compound is an organometallic iridium complex having a structure similar to that of the first phosphorescent compound. In the case where the layer is provided closer to the cathode than the second light-emitting layer, and the second light-emitting layer has hole transport properties ( Specifically, when the second host material is a hole transport material, the carrier recombination region is It is preferable because it is easy to control the amount of the compound having a pyrimidine skeleton in the light-emitting layer. Organometallic 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.

[0110] In addition to the above-mentioned phosphorescent compounds, the first phosphorescent compound may be selected from among known phosphorescent light-emitting materials. A third phosphorescent compound 113Da to a third phosphorescent compound 113Dc may be selected and used.

[0111] The phosphorescent compounds (first phosphorescent compound 113Da to third phosphorescent compound 113Da) 13Dc), we developed a material that exhibits thermally activated delayed fluorescence (TAD F) materials may be used. Here, delayed fluorescence is a material that has a spectrum similar to that of normal fluorescence. Its lifetime is approximately 10 -6 seconds or more, preferably 10 - 3 sec or more. Specific examples of thermally activated delayed fluorescent materials include fullerenes and their derivatives, Examples include acridine derivatives such as proflavine, and eosin. Magnesium (M g), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium ( Examples of the metal-containing porphyrin include metal-containing porphyrins containing palladium (Pd) and the like. Examples of the porphyrin containing the fluorine atom include protoporphyrin-tin fluoride complex (SnF2 (Proto IX)), mesoporphyrin-tin fluoride complex (SnF2(Meso I) Hematoporphyrin-Tin Fluoride Complex (SnF2(Hemato IX)), Proporphyrin tetramethyl ester-tin fluoride complex (SnF2(Copro II I-4Me), octaethylporphyrin-tin fluoride complex (SnF2(OEP)), Ethioporphyrin-Tin Fluoride Complex (SnF2(Etio I)), Octaethylporphyrin Phyrin-platinum chloride complex (PtCl2OEP) and others. -4,6-bis(12-phenylindolo[2,3-a]carbazole- π-electron rich heteroaromatic rings such as 1,3,5-triazine (PIC-TRZ) and heterocyclic compounds having a π-electron deficient heteroaromatic ring. A substance in which an abundant heteroaromatic ring and a π-electron deficient heteroaromatic ring are directly bonded is called a π-electron abundant heteroaromatic ring. The donor property of the aromatic ring and the acceptor property of the π-electron-deficient heteroaromatic ring are both strong, and the S1 and T This is particularly preferred because the energy difference of 1 is small.

[0112] The first host material 113Ha1, the second host material 113Ha2, and the first carrier The transport compound 113H1 to the fourth carrier transport compound 113H4 can be used as Possible materials have been clearly stated in the first embodiment, so repeated description will be omitted.

[0113] The light-emitting layer 113 can be formed by co-evaporation using a vacuum deposition method, or by depositing a mixed solution using an inkjet method or a spin method. It can be prepared by using a coating method, a dip coating method, or the like.

[0114] 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.

[0115] 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.

[0116] 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 penetrating the light-emitting layer. This is highly effective in suppressing problems that arise (such as a decrease in element life).

[0117] 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.

[0118] 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, or indium oxide, regardless of the magnitude of the work function. Various conductive materials such as indium-tin oxide, indium oxide-tin oxide containing silicon or silicon oxide are available. Conductive materials can be used as the second electrode 102. These conductive materials can be sputtered. The film can be formed by using a ring method, an ink jet method, a spin coating method, or the like.

[0119] The EL layer 103 can be formed by a variety of methods, including a dry method and a wet method. For example, a vacuum deposition method, an inkjet method, a spin coating method, or the like can be used. Also, each electrode or each layer may be formed using a different film formation method. .

[0120] 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.

[0121] 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

[0122] The light is emitted through either the first electrode 101 or the second electrode 102, or both. Therefore, either the first electrode 101 or the second electrode 102 Or both of them are made of an electrode having light transmitting properties. Only the first electrode 101 is an electrode having light transmitting properties. When the second electrode 102 is When only the second electrode 102 is a light-transmitting electrode, the emitted light is extracted through the second electrode 102. When the first electrode 101 and the second electrode 102 are both light-transmitting electrodes, light emission is taken out from both the first electrode 101 and the second electrode 102.

[0123] 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 .

[0124] 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 triplet excitation energy, the triplet excitation energy of the material constituting the light-emitting layer is It is preferable that it be made of a substance that has greater energy than the energy of the object.

[0125] The light emitting element in this embodiment is manufactured on a substrate made of glass, plastic, or the like. Regarding the order of fabrication on the substrate, the layers may be stacked in order from the first electrode 101 side. The light emitting device may be formed by forming one light emitting element on one substrate. A single light emitting element may be formed on one substrate, or a plurality of light emitting elements may be formed on one substrate. By fabricating multiple elements, it is possible to create lighting devices with separate elements and passive matrix light-emitting devices. Also, a thin film, for example, can be formed on a substrate made of glass, plastic, etc. A thin-film transistor (TFT) is formed, and a light-emitting element is fabricated on the electrode electrically connected to the TFT. This allows an active matrix display device to control the driving of light-emitting elements using TFTs. A light-emitting device of this type can be manufactured. The structure of the TFT is not particularly limited. The TFT may be a TFT of a staggered type or a reverse staggered type. There is no particular limitation on the type of semiconductor, and either an amorphous semiconductor or a crystalline semiconductor may be used. In addition, the driving circuit formed on the TFT substrate is also made up of N-type and P-type TFTs. Alternatively, the TFT may be composed of only one of N-type TFT or P-type TFT. It may be also possible.

[0126] Note that this embodiment mode can be appropriately combined with other embodiment modes.

[0127] (Embodiment 3) In this embodiment, a light-emitting element having a configuration in which a plurality of light-emitting units are stacked (hereinafter, referred to as a stacked element) is The embodiment of the light-emitting element (also referred to as a "light-emitting element") will be described with reference to FIG. The light-emitting element has a plurality of light-emitting units between the first electrode and the second electrode. 1 has a similar structure to the EL layer 103 shown in FIG. A light-emitting element having one light-emitting unit, and in this embodiment, a light-emitting element having a plurality of light-emitting units It can be said that the light emitting element has such a structure.

[0128] In FIG. 2, a first light-emitting unit is disposed between a first electrode 501 and a second electrode 502. The first light-emitting unit 511 and the second light-emitting unit 512 are stacked. A charge generating layer 513 is provided between the first electrode 501 and the light emitting unit 512. and second electrode 502 correspond to first electrode 101 and second electrode 102 in FIG. The same as that described in the description of FIG. 1 can be applied. The first light-emitting unit 511 and the second light-emitting unit 512 may have the same or different configurations. .

[0129] The charge generating layer 513 includes a composite material of an organic compound and a metal oxide. The composite material of the compound and the metal oxide can be used for the hole injection layer 111 shown in FIG. A composite material can be used. The organic compound can be an aromatic amine compound, a carbazole compound, or the like. compounds, aromatic hydrocarbons, polymer compounds (oligomers, dendrimers, polymers, etc.) As the organic compound, a compound having a hole mobility of 1× 10 -6 cm 2 It is preferable to apply a value of 0.1V or more. However, it is preferable to apply a value of 0.1V or more. Other materials may be used as long as they have high pore transport properties. The composite material of these compounds has excellent carrier injection and transport properties, making it suitable for low-voltage operation and low Current driving can be realized. In addition, the anode side of the light-emitting unit is in contact with the charge generating layer. In this case, the charge generating layer can also function as a hole transport layer for the light emitting unit. The light-emitting unit does not necessarily need to have a hole transport layer.

[0130] The charge generating layer 513 is made of a layer containing a composite material of an organic compound and a metal oxide and other materials. For example, a layer composed of an organic compound and a metal oxide may be formed as a laminate structure. A layer including a composite material, a compound selected from electron donating substances, and a compound having high electron transport properties A layer containing an organic compound and a metal oxide may be laminated. The conductive layer may be formed by laminating a layer containing the above-mentioned compound and a transparent conductive film.

[0131] In any case, the battery sandwiched between the first light-emitting unit 511 and the second light-emitting unit 512 When a voltage is applied between the first electrode 501 and the second electrode 502, the charge generating layer 513 It is sufficient that the light-emitting unit injects electrons into the light-emitting unit and the light-emitting unit injects holes into the other light-emitting unit. For example, in FIG. 2, the potential of the first electrode is set higher than the potential of the second electrode. When a voltage is applied to the charge generating layer 513, the charge generating layer 513 injects electrons into the first light emitting unit 511. , it is sufficient that the second light-emitting unit 512 injects holes.

[0132] Although the light emitting device having two light emitting units has been described in FIG. 2, a light emitting device having three or more light emitting units may be used. The present invention can be similarly applied to a light emitting device in which units are stacked. In the case of the light-emitting element according to the embodiment, a plurality of light-emitting units are separated by a charge generating layer between a pair of electrodes. This arrangement allows for high-brightness light emission while keeping the current density low, and also makes the device longer-lasting. In addition, it is possible to realize a light-emitting device that can be driven at a low voltage and consumes low power. Cut.

[0133] In addition, by making the emission color of each light-emitting unit different, For example, a light-emitting element having two light-emitting units can be used. The first light-emitting unit emits red and green light, and the second light-emitting unit emits blue light. By this, it is possible to obtain a light-emitting element that emits white light as a whole.

[0134] At least one of the units has the above-mentioned structure of the light-emitting layer 113. By using this, the manufacturing process of the unit can be reduced, It is possible to provide a multi-color light-emitting device that is advantageous for practical use.

[0135] The above configuration may be appropriately combined with other embodiments or other configurations in this embodiment. It is possible.

[0136] (Embodiment 4) In this embodiment, a light-emitting device using the light-emitting element described in any of Embodiments 1 to 3 This article explains:

[0137] In this embodiment mode, a light-emitting element manufactured using any of the light-emitting elements described in any of Embodiments 1 to 3 is used. The light-emitting device will be described with reference to FIG. 3. FIG. 3(A) is a top view of the light-emitting device. 3B 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) 603. 604 is a sealing substrate, 605 is a sealing material, and the inside surrounded by the sealing material 605 is a space. It's now 607.

[0138] 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.

[0139] Next, a 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.

[0140] 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.

[0141] 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.

[0142] 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.

[0143] 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 film and aluminum film are also available. A titanium nitride film and an aluminum-based film are stacked together, and a titanium nitride film and an aluminum-based film are stacked together. A three-layer structure with a titanium film can be used. It has low resistance, good ohmic contact, and can function as an anode. do.

[0144] The EL layer 616 is formed by deposition using a deposition mask, inkjet printing, spin coating, etc. The EL layer 616 is formed by any of various methods described in the first to third embodiments. 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). .

[0145] 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.

[0146] The first electrode 613, the EL layer 616, and the second electrode 617 form a light-emitting element. The light-emitting element has the structure described in any one of the embodiments 1 to 3. Note that the pixel portion is formed with a plurality of light emitting elements. The optical device includes the light-emitting element described in any one of Embodiments 1 to 3 and other components. The light emitting element may include both a light emitting element and a light emitting element.

[0147] Furthermore, the sealing substrate 604 is bonded to the element substrate 610 with a sealant 605. A light-emitting element is disposed in a space 607 surrounded by an element substrate 610, a sealing substrate 604, and a sealant 605. The space 607 is filled with a filler. In addition to being filled with an inert gas (nitrogen, argon, etc.), it is also possible to fill it with a sealing material 605. If a recess is formed in the sealing substrate and a desiccant 625 is provided there, the sealing substrate can be protected from the effects of moisture. This is a preferable configuration because it is possible to suppress deterioration due to the above-mentioned causes.

[0148] 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.

[0149] In the above manner, the light-emitting element described in any of Embodiments 1 to 3 is used to manufacture the semiconductor device. A light emitting device having such a structure can be obtained.

[0150] The light-emitting device in this embodiment includes the light-emitting element described in any one of Embodiments 1 to 3. Since the organic EL element is used, a light emitting device having excellent characteristics can be obtained. The light-emitting element shown in any of Embodiments 1 to 3 has high emission efficiency and consumes reduced 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.

[0151] 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. 4(A) shows a passive matrix light-emitting device manufactured by 4(B) is a cross-sectional view taken along the line XY in FIG. 4(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 embodiment, the light-emitting element described in any one of the first to third embodiments can be driven at a low voltage. By doing so, it is possible to operate the device with low power consumption. By including the light-emitting element described in embodiment 3, the device can be driven with low power consumption. In addition, by using the light-emitting element described in any of Embodiments 1 to 3, It is possible to make a light emitting device.

[0152] 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 Fig. 5(A) and (B). Fig. 5(A) shows a substrate 1001, 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. 34R, green colored layer 1034G, and 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.

[0153] 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. 6. 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. The insulating film may be formed to cover the first interlayer 1022. The insulating film may also serve as a flattening film. The insulating film 1037 is formed using the same material as the second interlayer insulating film, as well as other known materials. It is possible.

[0154] 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 structure described in the first to third embodiments is 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 would be one in which red and green light is emitted 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 to third embodiments are applied, the configuration for obtaining white light emission is this. Of course, this is not limited to the above.

[0155] 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. 5B, 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 insulating layer 1036 may be covered with an overcoat layer 1036. The substrate 1031 is a light-transmitting substrate.

[0156] 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 any of the embodiments 1 to 3, the consumption It is possible to realize a light emitting device that consumes less power.

[0157] In addition, although an example of full-color display using four colors, red, green, blue, and white, is shown here, the present invention is not limited to such a case. Alternatively, full color display may be achieved using the three colors red, green, and blue.

[0158] This embodiment mode can be freely combined with other embodiment modes.

[0159] (Embodiment 5) In this embodiment, the light-emitting element described in any of the embodiments 1 to 3 is used as a lighting device. An example of use will be described with reference to FIG. 7. FIG. 7(B) is a top view of the lighting device, and FIG. 7(B) is a cross-sectional view taken along line ef in FIG.

[0160] 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 that in the first to third embodiments. This corresponds to the first electrode 101 in the semiconductor device.

[0161] 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. In addition, in order to supply a voltage to the second electrode 404 at the same time as the formation of the auxiliary electrode 402, A pad 412 for this purpose may be formed.

[0162] The EL layer 403 is formed on the first electrode 401 and the auxiliary electrode 402. 3 has the configurations described in the first to third 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.

[0163] The second electrode 404 is formed to cover the EL layer 403. This corresponds to the second electrode 102 in the third embodiment and has a similar configuration. In this embodiment, light is emitted from the first electrode 401 side, so the second electrode 404 is a reflecting electrode. It is preferable that the second electrode is made of a material having a high refractive index. Voltage is supplied to 404 by connecting it to pad 412 .

[0164] 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.

[0165] The light emitting element having the above structure is sealed by fixing a sealing substrate 407 using a sealing material 405. The lighting device is completed by sealing the sealing material 405 on either side. In addition, a desiccant can be mixed into the inner sealant 405, which absorbs moisture. This leads to improved reliability.

[0166] In addition, the pad 412, the first electrode 401, and a part of the auxiliary electrode 402 are covered with the sealing material 405. By extending it outside, it can be used as an external input terminal. An IC chip 420 equipped with an inverter or the like may be provided.

[0167] As described above, the lighting device described in this embodiment has the EL element according to the first to third 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.

[0168] (Embodiment 6) In this embodiment, the light-emitting element described in any one of Embodiments 1 to 3 is included as a part of the light-emitting element. Examples of electronic devices will be described. The light-emitting elements described in any of the embodiments 1 to 3 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 element described in any of the embodiments 1 to 3 is a light-emitting element that requires a low driving voltage. Therefore, it is possible to provide an electronic device with a low driving voltage.

[0169] 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.

[0170] FIG. 8A 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 any of Embodiments 1 to 3. 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.

[0171] 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.

[0172] 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.

[0173] FIG. 8(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 similar to the one described in the first to third embodiments. The display unit 7203 is fabricated by arranging optical elements in a matrix. The computer of FIG. 8(B2) may be in the form of the computer of FIG. 8(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. This also prevents damage and other troubles. The light-emitting elements described in any one of the embodiments 1 to 3 are arranged in a matrix. The light-emitting element is manufactured by using the same in the portion 7203. The light-emitting element has good light-emitting efficiency. Therefore, it is possible to display a display portion 7203 including the light-emitting element. The computer may be a reduced power computer.

[0174] FIG. 8C 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 any of the first to third embodiments in a matrix. A display unit 7305 is incorporated in the housing 7302. The portable gaming machine shown in FIG. 8(C) also includes a speaker unit 7306, 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 any one of the elements described in any one of the embodiments 1 to 3. 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. 8(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.

[0175] FIG. 8D shows an example of a mobile phone. The mobile phone is incorporated 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 is The display unit 7402 has the light-emitting elements according to the third embodiment 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 small light emission coefficient. In addition, it is possible to provide a light-emitting element with a long life. Therefore, a mobile phone having a display portion 7402 formed of the light-emitting element is a consumer electronics device. It is possible to provide a mobile phone with reduced power consumption. Also, it is possible to provide a mobile phone with a low driving voltage. It is also possible to provide a highly reliable mobile phone.

[0176] In the mobile phone shown in FIG. 8D, 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.

[0177] 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.

[0178] 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.

[0179] 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.

[0180] 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.

[0181] 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.

[0182] 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.

[0183] Note that the configuration shown in this embodiment mode is a combination of the configurations shown in Embodiment Modes 1 to 5. They can be used in combination.

[0184] As described above, the scope of application of the light-emitting device including the light-emitting element described in any one of the first to third 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 any of Embodiments 1 to 3, power consumption can be reduced. The electronic device can be obtained.

[0185] FIG. 9 is a liquid crystal display in which the light-emitting element described in any one of the first to third embodiments is applied to a backlight. The liquid crystal display device shown in FIG. 9 includes a housing 901, a liquid crystal layer 902, The liquid crystal layer 902 has a driver IC 905 and In addition, the backlight 903 is connected to the backlight 902. A light emitting element is used, and a current is supplied through a terminal 906.

[0186] The light-emitting element described in any one of the embodiments 1 to 3 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 in the first to third embodiments, a surface emitting lighting device can be fabricated. This allows the backlight to have a large area, and the liquid crystal display device Furthermore, the light-emitting element described in any of the embodiments 1 to 3 can be used. The thickness of the light-emitting device using this material can be reduced compared to conventional devices, making it possible to make thinner display devices. .

[0187] FIG. 10 illustrates a configuration in which the light-emitting element described in any one of Embodiments 1 to 3 is used as an electric switch which is a lighting device. The desk lamp shown in FIG. 10 is an example of a desk lamp using a housing 2001 and a light source 2002. The light emitting element described in any of the embodiments 1 to 3 is used as the light source 2002. It is being done.

[0188] FIG. 11 shows an indoor lighting device 300 in which the light-emitting element described in any one of the first to third embodiments is used. The light-emitting element described in any of the embodiments 1 to 3 has a low power consumption. Since the light-emitting device has a reduced power consumption, the lighting device can have a reduced power consumption. In addition, the light-emitting element described in any of the embodiments 1 to 3 can be made large in area; In addition, the light emitting device according to any one of the first to third embodiments can be used as a lighting device. The light-emitting element is thin, and therefore can be used as a thin lighting device.

[0189] The light-emitting element described in any one of the first to third embodiments is used for a windshield or a dash board of an automobile. The invention described in the first to third embodiments can be mounted on a display board. One embodiment of the optical element is shown in the windshield or dashboard of an automobile. The display regions 00 to 5005 are provided using the light-emitting elements described in any of the embodiments 1 to 3. can be done.

[0190] The display area 5000 and the display area 5001 are provided on the windshield of a car. A display device including the light-emitting element described in any of Embodiments 1 to 3. In the light-emitting element according to the third embodiment, the first electrode and the second electrode are made of light-transmitting electrodes. By doing so, it becomes a so-called see-through display device, where the other side can be seen through. If the display is see-through, it can be installed on the windshield of a car. The device can be installed without obstructing the view. In the case of providing a transistor, an organic transistor made of an organic semiconductor material or an oxide semiconductor is used. A light-transmitting transistor, such as a transistor having a light-transmitting property, is preferably used.

[0191] The display region 5002 is a display device provided in a pillar portion, as described in any one of the first to third embodiments. The display device is equipped with a photoelectric element. The display area 5002 is provided with an image pickup means provided on the vehicle body. By projecting images from these windows, it is possible to complement the view blocked by the pillars. Similarly, the display area 5003 provided on the dashboard is blocked by the vehicle body. By projecting images from an imaging device installed on the outside of the vehicle, blind spots are compensated for. This can improve safety by projecting images to complement the invisible parts. This allows safety checks to be performed more naturally and without any discomfort.

[0192] The display area 5004 and the display area 5005 display navigation information, a speedometer, a tachometer, etc. Provides various information such as meter, mileage, fuel level, gear status, air conditioning settings, etc. The display items and layout can be changed as needed to suit the user's preferences. This information can also be provided in the display areas 5000 to 5003. In addition, the display areas 5000 to 5005 can be used as lighting devices. It is also possible.

[0193] The light-emitting element described in any of the embodiments 1 to 3 has high luminous efficiency. In addition, a light-emitting device with low power consumption can be obtained. Even if many large screens such as the display area 5000 to the display area 5005 are provided, the burden on the battery is not large. Since it requires less weight and can be used comfortably, the first to third embodiments The light-emitting device or lighting device using the light-emitting element according to the third aspect is an in-vehicle light-emitting device or lighting device. It can be suitably used as a device.

[0194] FIG. 13(A) and FIG. 13(B) show an example of a tablet terminal that can be folded in half. 3(A) is in an open state, and the tablet terminal includes a housing 9630, a display unit 9631a, and , 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 any one of the first to third embodiments. By using the light-emitting device as one or both of the display portions 9631a and 9631b, It is produced.

[0195] A part of the display unit 9631a can be used as a touch panel area 9632a. By touching the operation keys 9637, data can be input. In 1a, as an example, half of the area has a display function only, and the other half The display unit 963 has a touch panel function, but is not limited to this. The entire area of ​​the display unit 96 may have a touch panel function. The entire surface of 31a is made to display keyboard buttons to make it a touch panel, and the display part 9631b is displayed It can be used as a screen.

[0196] In addition, in the display unit 9631b, as in the display unit 9631a, The portion of the keyboard 9632 can be used as a touch panel area 9632b. By touching the area where the display switch button 9639 is displayed with your finger or a stylus, Keyboard buttons can be displayed on the display portion 9631b.

[0197] In addition, when touching the touch panel area 9632a and the touch panel area 9632b at the same time, You can also input the

[0198] A display mode changeover switch 9034 is used to change the display orientation, such as portrait or landscape. You can switch between black and white and color display. The switch 9036 is a switch that turns on and off when the tablet terminal is in use and is detected by a light sensor built into the tablet terminal. The brightness of the display can be optimized according to the amount of light. In addition to sensors, other detection devices such as gyros, acceleration sensors, etc. that detect tilt may be incorporated.

[0199] FIG. 13A 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.

[0200] FIG. 13B shows the tablet terminal in the closed state. Body 9630, solar cell 9633, charge / discharge control circuit 9634, battery 9635, DCD 13B 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.

[0201] 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.

[0202] In addition, the tablet terminals shown in Figs. 13(A) and 13(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.

[0203] 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. When the battery is charged on one or both sides of the housing 9630, the battery 9635 can be charged efficiently. This is preferable because it is possible to configure the above.

[0204] The configuration and operation of the charge / discharge control circuit 9634 shown in FIG. A block diagram is shown in FIG. 13C. 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. 13(B). This corresponds to the circuit 9634 .

[0205] 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.

[0206] 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.

[0207] In addition, if the display unit 9631a or 9631b is provided, the shape shown in FIG. It is not limited to tablet devices. EXAMPLES

[0208] This embodiment is a light-emitting device corresponding to one embodiment of the present invention described in any one of Embodiments 1 to 3. 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.

[0209] [ka]

[0210] Next, a method for fabricating the light emitting device of this embodiment will be described.

[0211] First, indium oxide-tin oxide (ITSO) containing silicon oxide is sputtered onto a glass substrate. The first electrode 101 was formed by a ring method. The thickness of the first electrode 101 was 110 nm. The electrode area was set to 2 mm×2 mm. Here, the first electrode 101 was used as an anode of the light-emitting element. It is a functioning electrode.

[0212] 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.

[0213] Then, 10 -4 The substrate is placed in a vacuum deposition apparatus whose inside has been reduced in pressure to about Pa, and vacuum deposition is performed. After vacuum baking at 170°C for 30 minutes in the heating chamber of the device, the substrate is left for about 30 minutes. Allow to cool.

[0214] Next, the first electrode 101 is formed so that the surface on which the first electrode 101 is formed faces downward. The substrate was fixed to a substrate holder installed in a vacuum deposition apparatus and was heated for 10 -4 Reduced to about Pa After pressing, a film represented by the above structural formula (i) was deposited on the first electrode 101 by a deposition method using resistance heating. 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) By co-evaporating DBT3P-II and molybdenum oxide (VI), An implantation layer 111 was formed. The thickness of the implantation layer was set to 40 nm. The weight ratio of DBT3P-II to molybdenum oxide was adjusted to 4:2 (=DBT3P-II:molybdenum oxide). The co-evaporation method is a method of simultaneously evaporating from multiple evaporation sources in one processing chamber. It is law.

[0215] 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.

[0216] 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 (2,3,5-triphenylpyrazine)(dipivaloylmethanamide) represented by structural formula (v) g) Iridium (III) (abbreviation: [Ir(tppr)2(dpm)]) in a weight ratio of 0 .5:0.5:0.05(=2mDBTPDBq-II:PCBA1BP:[Ir(tp pr)2(dpm)]) to form the second light-emitting layer 113b. 3,5-bis[3-(9H-carbazol-9-yl)phenyl]phenyl]propane represented by the following structural formula (vi): 3,3-phenylpyridine (abbreviation: 35DCzPPy) and the above structural formula (vii), '-Bis(9-phenyl-9H-carbazole) (abbreviation: PCCP) and the above structural formula (v iii) Tris{2-[5-(2-methylphenyl)-4-(2,6-dimethyl 4H-1,2,4-triazol-3-yl-κN2]phenyl-κC} Iridium (III) (abbreviation: [Ir(mpptz-dmp)3]) in a weight ratio of 0.5 :0.5:0.06(=35DCzPPy:PCCP:[Ir(mpptz-dmp)3 ]) was co-evaporated to a thickness of 30 nm to form first light-emitting layer 113a.

[0217] Thereafter, 2-[3-(dibenzothiophene)-2-(4-methylphenyl)-2-propanediol represented by the above structural formula (ix) was deposited on the light-emitting layer 113. mDBT BIm-II) was formed into a film having a thickness of 10 nm, and further, Bathophenanthroline (abbreviation: BPhen) was deposited to a thickness of 20 nm and used for electron transport. A transfer layer 114 was formed.

[0218] 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.

[0219] 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.

[0220] In the above-mentioned deposition process, the deposition was all performed by a resistance heating method.

[0221] The element structure of the light-emitting element 1 thus obtained is shown in Table 1.

[0222] [Table 1]

[0223] 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.

[0224] 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.

[0225] FIG. 14 shows an emission spectrum when a current of 0.1 mA was applied to the light-emitting element 1. Therefore, the light-emitting element 1 emits blue wavelength light derived from [Ir(mpptz-dmp)3] and [Ir( The emission spectrum includes both red wavelength light from the 2-(3-(4-(diphenyl tppr)2(dpm)) and red wavelength light from the 2-(3-(diphenyl tppr)2(dpm)). I realized that.

[0226] Next, the luminance vs. current efficiency characteristics of the light-emitting element 1 are shown in FIG. 15, and the luminance vs. external quantum efficiency characteristics are shown in FIG. 6, voltage-luminance characteristics are shown in FIG. 17, and luminance-power efficiency characteristics are shown in FIG. Table 2 shows the main characteristics around 0 cd / m2.

[0227] [Table 2]

[0228] As described above, it was found that the light-emitting element 1 exhibited good element characteristics. In particular, FIG. As can be seen from FIG. 6, the luminous efficiency is very good, and the external quantum efficiency is 4.1 times higher than the practical brightness (1000 cd / m 2 ) showed a high value of 25%. It is clear that the light-emitting element has good voltage-luminance characteristics and requires a low driving voltage. As a result, as shown in FIG. 18, a light-emitting device having good power efficiency was obtained.

[0229] As described above, the light-emitting element 1 according to one embodiment of the present invention has excellent element characteristics 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

[0230] This embodiment is a light-emitting device corresponding to one embodiment of the present invention described in any one of Embodiments 1 to 3. 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: In this embodiment, the light emitting layer 113 includes a first light emitting layer 113a, a second light emitting layer 113b and a Light-emitting element 2 and light-emitting element 3 including the first light-emitting layer 113a and the third light-emitting layer 113c were fabricated.

[0231] [ka]

[0232] Next, a method for fabricating the light-emitting element 2 of this example will be described.

[0233] First, indium oxide-tin oxide (ITSO) containing silicon oxide is sputtered onto a glass substrate. The first electrode 101 was formed by a ring method. The thickness of the first electrode 101 was 110 nm. The electrode area was set to 2 mm×2 mm. Here, the first electrode 101 was used as an anode of the light-emitting element. It is a functioning electrode.

[0234] 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.

[0235] Then, 10 -4 The substrate is placed in a vacuum deposition apparatus whose inside has been reduced in pressure to about Pa, and vacuum deposition is performed. After vacuum baking at 170°C for 30 minutes in the heating chamber of the device, the substrate is left for about 30 minutes. Allow to cool.

[0236] 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, DBT3P-II and Molybdenum (VI) oxide was co-evaporated to form a hole injection layer 111. The thickness of the layer was , 40 nm, and the ratio of DBT3P-II to molybdenum oxide was 4:2 by weight (=DB T3P-II: molybdenum oxide). This is a deposition method in which deposition is carried out simultaneously from multiple evaporation sources in a processing chamber.

[0237] Next, a film of BPAFLP was formed on the hole injection layer 111 to a thickness of 20 nm. A transport layer 112 was formed.

[0238] Further, on the hole transport layer 112, 2mDBTPDBq-II, PCBA1BP, and [Ir( tppr)2(dpm)] in a weight ratio of 0.5:0.5:0.05 (=2mDBTPDB q-II: PCBA1BP: [Ir(tppr)2(dpm)]) The third light-emitting layer 113c was formed by co-evaporation of 2mDBTPDBq-II and PCBA1BP. (Acetylacetonato)bis(6-tert-butyl-4- Phenylpyrimidinato)iridium(III) (abbreviation: [Ir(tBuppm)2(ac ac)]) in a weight ratio of 0.5:0.5:0.05 (=2mDBTPDBq-II:PC BA1BP: [Ir(tBuppm)2(acac)]) was co-evaporated at 5 nm. The second light-emitting layer 113b is made of 35DCzPPy, PCCP, and [Ir(mptz-dmp )3] in a weight ratio of 0.5:0.5:0.06 (=35DCzPPy:PCCP:[Ir (mpptz-dmp)3]) was co-evaporated to a thickness of 30 nm to form the first light-emitting layer 113a. was formed.

[0239] Thereafter, mDBTBIm-II was formed on the light-emitting layer 113 to a thickness of 10 nm. Further, BPhen was deposited to a thickness of 20 nm to form the electron transport layer 114 .

[0240] 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.

[0241] 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.

[0242] In the above-mentioned deposition process, the deposition was all performed by a resistance heating method.

[0243] Next, a method for fabricating the light-emitting element 3 will be described. The thickness of the light-emitting layer 113b in the second embodiment was changed from 5 nm to 10 nm. The other configuration is the same as that of the light-emitting element 2.

[0244] Table 3 shows the element structures of the thus obtained Light-emitting Elements 2 and 3.

[0245] [Table 3]

[0246] The light-emitting element 2 and the light-emitting element 3 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.

[0247] 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.

[0248] FIG. 19 shows the emission spectra when a current of 0.1 mA was applied to the light-emitting element 2 and the light-emitting element 3. In FIG. 19, both the light-emitting element 2 and the light-emitting element 3 are [Ir(mpptz-dmp)3] blue wavelength light from [Ir(tBuppm)2(acac)], green light from [Ir(tBuppm)2(acac)], The emission spectrum contains red wavelength light from [Ir(tppr)2(dpm)]. In particular, light-emitting element 2 shows a light spectrum that meets the JIS standard for lighting. It emitted light.

[0249] Next, the luminance-current efficiency characteristics of the light-emitting element 2 and the light-emitting element 3 are shown in FIG. 20, and the luminance-external quantum The efficiency characteristics are shown in Fig. 21, the voltage-luminance characteristics in Fig. 22, and the luminance-power efficiency characteristics in Fig. 23. Also, 1000cd / m 2 The main characteristics of the area are shown in Table 4.

[0250] [Table 4]

[0251] As described above, it was found that the light-emitting elements 2 and 3 exhibited excellent element characteristics. As can be seen from Figs. 20 and 21, the luminous efficiency is very good, and the external quantum efficiency is practically satisfactory. Brightness (1000cd / m 2 ) showed a high value of over 20%. From the above, it can be seen that the light-emitting element 2 and the light-emitting element 3 have good voltage-luminance characteristics and can emit light with a low driving voltage. As a result, as shown in FIG. 23, it has good power efficiency. It became a light emitting element.

[0252] As described above, the light-emitting element 2 and the light-emitting element 3 according to one embodiment of the present invention have excellent element characteristics. It has also been found that this is a light-emitting device that can obtain well-balanced light from the three types of luminescent center substances. It was. EXAMPLES

[0253] This embodiment is a light-emitting device corresponding to one embodiment of the present invention described in any one of Embodiments 1 to 3. 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: In this embodiment, the light emitting layer 113 includes a first light emitting layer 113a, a second light emitting layer 113b and a A light-emitting element 4 including the first light-emitting layer 113c and the third light-emitting layer 113a was fabricated.

[0254] [ka]

[0255] Next, a method for fabricating the light emitting device 4 of this example will be described.

[0256] First, indium oxide-tin oxide (ITSO) containing silicon oxide is sputtered onto a glass substrate. The first electrode 101 was formed by a ring method. The thickness of the first electrode 101 was 110 nm. The electrode area was set to 2 mm×2 mm. Here, the first electrode 101 was used as an anode of the light-emitting element. It is a functioning electrode.

[0257] 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.

[0258] Then, 10 -4 The substrate is placed in a vacuum deposition apparatus whose inside has been reduced in pressure to about Pa, and vacuum deposition is performed. After vacuum baking at 170°C for 30 minutes in the heating chamber of the device, the substrate is left for about 30 minutes. Allow to cool.

[0259] 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, DBT3P-II and Molybdenum (VI) oxide was co-evaporated to form a hole injection layer 111. The thickness of the layer was , 40 nm, and the ratio of DBT3P-II to molybdenum oxide was 4:2 by weight (=DB T3P-II: molybdenum oxide). This is a deposition method in which deposition is carried out simultaneously from multiple evaporation sources in a processing chamber.

[0260] Next, on the hole injection layer 111, 4,4'-di(1-naphthalene) represented by the above structural formula (xii) 4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBNBB) is deposited to a thickness of 20 nm to form a hole transport layer 112. did.

[0261] Furthermore, on the hole transport layer 112, 2-[3′-(dibenzyl)- (benzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline ( Abbreviation: 2mDBTBPDBq-II) and PCBNBB and [Ir(tppr)2(dpm) ] and PCBNB in ​​a weight ratio of 0.5:0.5:0.05 (=2mDBTBPDBq-II:PCBNB B: [Ir(tppr)2(dpm)]) was co-evaporated to a thickness of 20 nm to form the third light-emitting layer. 113c, 2mDBTBPDBq-II, PCBNBB and [Ir(tBuppm)2 (acac)] in a weight ratio of 0.5:0.5:0.05 (=2mDBTBPDBq-II 10 nm co-evaporation to give PCBNBB:[Ir(tBuppm)2(acac)] The second light-emitting layer 113b was formed by depositing 35DCzPPy, PCCP, and [Ir(mpptz- dmp)3] in a weight ratio of 0.7:0.3:0.06 (=35DCzPPy:PCCP: [Ir(mpptz-dmp)3]) was co-evaporated to a thickness of 30 nm to form a first light-emitting layer 1 Formed 13a.

[0262] Thereafter, a film of 35DCzPPy was formed on the light-emitting layer 113 to a thickness of 10 nm. Then, BPhen was deposited to a thickness of 20 nm to form the electron transport layer 114 .

[0263] 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.

[0264] 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.

[0265] In the above-mentioned deposition process, the deposition was all performed by a resistance heating method.

[0266] The element structure of the thus obtained Light-emitting Element 4 is shown in Table 5.

[0267] [Table 5]

[0268] The light emitting element 4 is placed in a glove box with a nitrogen atmosphere and is covered with a 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.

[0269] 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.

[0270] FIG. 24 shows an emission spectrum when a current of 0.1 mA was applied to the light-emitting element 4. So, what is the blue wavelength light from [Ir(mpptz-dmp)3] and [Ir(tBupp green light from [Ir(tppr)2(dpm)] and It was found that the emission spectrum included all light of red wavelengths.

[0271] Next, the luminance vs. current efficiency characteristics of the light-emitting element 4 are shown in FIG. 25, and the luminance vs. external quantum efficiency characteristics are shown in FIG. 6, voltage-luminance characteristics are shown in FIG. 27, and luminance-power efficiency characteristics are shown in FIG. 0 cd / m 2 The main characteristics of the area are shown in Table 6.

[0272] [Table 6]

[0273] As described above, it was found that the light-emitting element 4 exhibited excellent element characteristics. In particular, as shown in FIG. As can be seen from FIG. 6, the luminous efficiency is very good, and the external quantum efficiency is 4.1 times higher than the practical brightness (1000 cd / m 2 ) showed a high value exceeding 20%. It can be seen that Device 4 has good voltage-luminance characteristics and is a light-emitting device with a low driving voltage. As a result, as shown in FIG. 28, a light-emitting device having good power efficiency was obtained.

[0274] As described above, the light-emitting element 4 according to one embodiment of the present invention has excellent element characteristics and has three types of It was found that this light-emitting element was capable of obtaining well-balanced light from the luminescent center substances.

[0275] In addition, the initial brightness is 3000cd / m 2 The light-emitting element 4 is driven under a constant current density condition. The results of the reliability test are shown in Figure 29. Figure 29 shows the standard brightness with the initial brightness set to 100%. From this result, it can be seen that the light-emitting element 4 exhibits a small decrease in luminance over driving time. It is therefore clear that the light-emitting element has good reliability.

[0276] (Reference example 1) In the above-mentioned examples, 35DCzPPy, PCCP, and 2mDBT were used for each light-emitting element. Triplet of PDBq-II, PCBA1BP, 2mDBTBPDBq-II, PCBNBB The excitation energy was measured. The triplet excitation energy was measured by phosphorescence of each substance. The emission was measured, and the phosphorescence emission wavelength was converted into electron volts. The conditions were as follows: each substance was irradiated with 325 nm excitation light and the measurement temperature was 10 K. The measurement of the energy level is more accurate when calculated from the absorption wavelength rather than the emission wavelength. However, the absorption of triplet excitation energy is extremely weak and difficult to measure. In this study, the triplet was obtained by measuring the peak wavelength located on the shortest wavelength side of the phosphorescence spectrum. The term excitation energy was calculated. Therefore, the measured values ​​may contain some error.

[0277] The measured phosphorescence is shown in Figures 30 to 35. The measurement results are summarized in Table 7. As can be seen from the results, 35DCzPPy and PCCP used in the first emitting layer 2mDBTPDBq-II, PCBA1BP, used in the second or third emitting layer, It was found that 2mDBTBPDBq-II has a higher triplet excitation energy than PCBNBB. do.

[0278] [Table 7]

[0279] (Reference example 2) The organometallic complex used in the above examples, (acetylacetonato)bis(6-tert-butyl -4-phenylpyrimidinato)iridium(III) (also known as bis[2-(6-tert -Butyl-4-pyrimidinyl-κN3)phenyl-κC](2,4-pentanedionato- κ 2 O,O') Iridium(III) (abbreviation: [Ir(tBuppm)2(acac) The structure of [Ir(tBuppm)2(acac)] is shown below. vinegar.

[0280] [ka]

[0281] <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.

[0282] [ka]

[0283] <Step 2: Di-μ-chloro-bis[bis(6-tert-butyl-4-phenylpyridine] Synthesis of [midinato)iridium(III)] (abbreviation: [Ir(tBuppm)2Cl]2) > Next, 15 mL of 2-ethoxyethanol, 5 mL of water, and the HtBupp obtained in step 1 above were added. 1.49 g of m and 1.04 g of iridium chloride hydrate (IrCl3·H2O) were The flask was then filled with argon gas. The mixture was irradiated with a 5 GHz 100 W power source for 1 hour to cause a reaction. After the solvent was removed by distillation, the resulting residue was The binuclear complex [Ir(tBuppm)2Cl]2 was obtained by suction filtration and washing with ethanol (yellow). Green powder, 73% yield. The synthesis scheme for step 2 is shown below.

[0284] [ka]

[0285] <Step 3; (acetylacetonato)bis(6-tert-butyl-4-phenylpyridine) Iridium(III) (abbreviation: [Ir(tBuppm)2(acac)] > Furthermore, 40 mL of 2-ethoxyethanol and the binuclear complex [Ir(tB uppm)2Cl]21.61 g, acetylacetone 0.36 g, sodium carbonate 1. 27 g was placed in a recovery flask equipped with a reflux condenser, and the atmosphere in the flask was replaced with argon. The mixture was then irradiated with microwaves (2.45 GHz, 120 W) for 60 minutes to react. The solvent was removed by distillation. The resulting residue was filtered with ethanol and washed with water and ethanol. Dissolve in chloromethane and filter with Celite (Wako Pure Chemical Industries, Ltd., Catalog No. 531-1 The mixture was filtered through a filter aid consisting of a layer of 6855), alumina, and celite in that order. The solid obtained by removing the residue was recrystallized in a mixed solvent of dichloromethane and hexane to give The target product was obtained as a yellow powder (yield 68%). The synthesis scheme of step 3 is shown below.

[0286] [ka]

[0287] 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.

[0288] 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)

[0289] (Reference example 3) In this Reference Example, the tris{2-[5-(2-methylphenyl)-4- (2,6-dimethylphenyl)-4H-1,2,4-triazol-3-yl-κN2] Phenyl-κC}iridium(III) (abbreviation: [Ir(mpptz-dmp)3]) The synthesis method is explained below. The structure of [Ir(mpptz-dmp)3] is shown below.

[0290] [ka]

[0291] <Step 1: Synthesis of N-benzoyl-N'-2-methylbenzoyl hydrazide> First, 15.0 g (110.0 mmol) of benzoylhydrazine and N-methyl-2-pyridinium 75 ml of NMP was placed in a 300 ml three-neck flask and stirred under ice cooling. In the mixture of 17.0g (110.0mmol) of o-toluic acid chloride and N-methyl- A mixed solution of 15 ml of 2-pyrrolidinone (NMP) was slowly added dropwise. After the addition, the mixture was left at room temperature for 2 The mixture was stirred for 4 hours. After the reaction time, the reaction solution was slowly added to 500 ml of water. A colored solid precipitated. The precipitated solid was ultrasonically washed alternately with water and 1M hydrochloric acid. The white solution of N-benzoyl-N'-2-methylbenzoyl hydrazide was prepared by ultrasonic cleaning in a San. A white solid was obtained in an amount of 19.5 g and a yield of 70%. The synthesis scheme for step 1 is shown below.

[0292] [ka]

[0293] <Step 2; N-[1-chloro-1-(2-methylphenyl)methylidene-N'-[1 Synthesis of -chloro-(1-phenyl)methylidene]hydrazine> Next, N-benzoyl-N'-2-methylbenzoyl hydrazide 1 obtained in step 1 above was 2.0g (47.2mmol) and 200ml of toluene were placed in a 500ml three-neck flask. To this mixture, 19.4 g (94.4 mmol) of phosphorus pentachloride was added and heated at 120°C for 6 hours. After the reaction time, the reaction solution was slowly poured into 200 ml of water and stirred for 1 hour. After stirring, the organic layer and the aqueous layer were separated, and the organic layer was washed with water and a saturated aqueous sodium hydrogen carbonate solution. After washing, the organic layer was dried over anhydrous magnesium sulfate. Magnesium sulfate was removed by filtration, and the filtrate was concentrated to give N-[1-chloro-1- (2-methylphenyl)methylidene]-N'-[1-chloro-(1-phenyl)methylidene The brown liquid of [N]hydrazine was obtained in 12.6 g with a yield of 92%. Synthesis scheme for step 2 is shown below.

[0294] [ka]

[0295] <Step 3; 3-(2-methylphenyl)-4-(2,6-dimethylphenyl)-5- Synthesis of phenyl-4H-1,2,4-triazole (abbreviation: Hmpptz-dmp) First, N-[1-chloro-1-(2-methylphenyl)methyl] 12.6 g of N'-[1-chloro-(1-phenyl)methylidene]-hydrazine ( 43.3mmol), 2,6-dimethylaniline 15.7g (134.5mmol), N 100 ml of N-dimethylaniline was placed in a 500 ml eggplant flask and heated at 120°C for 20 hours. After the reaction time had elapsed, the reaction solution was slowly added to 200 ml of 1N hydrochloric acid. Dichloromethane was added to this solution to extract the target substance into the organic layer. The obtained organic layer was washed with water, charcoal, and The extract was washed with an aqueous solution of sodium hydrogen carbonate and dried over magnesium sulfate. The magnesium was removed, and the resulting filtrate was concentrated to give a black liquid. The mixture was purified by column chromatography using a developing solvent of ethyl acetate:hexane=1:5. The obtained fraction was concentrated to obtain a white solid. Recrystallization was performed to obtain 4.5 g of a white solid, Hmpptz-dmp, in a yield of 31%. The synthetic scheme of compound 3 is shown below.

[0296] [ka]

[0297] <Step 4: Synthesis of [Ir(mpptz-dmp)3]> 2.5 g (7.4 mmol) of the ligand Hmpptz-dmp obtained in step 3 above, tri 0.7g (1.5mmol) of bis(acetylacetonato)iridium(III) was heated at high temperature. The reaction vessel was then heated at 250° C. for 48 hours while Ar was flowing inside. After the reaction for a certain period of time, the solid obtained was washed with dichloromethane, and the green insoluble matter was removed. The solid was obtained by suction filtration. The solid was dissolved in toluene and stacked on alumina and celite. The resulting fraction was concentrated to give a green solid. The product was recrystallized in ethanol to give 0.8 g of green powder in 45% yield. is shown below.

[0298] [ka]

[0299] The green powder obtained in step 4 was analyzed by nuclear magnetic resonance spectroscopy ( 1 H-NMR The analytical results are shown below. From these results, it was found that this synthesis method was able to produce [Ir(mpptz-dmp) 3] was found to be obtained.

[0300] 1 H-NMR.δ(toluene-d8):1.82(s,9H),1.90(s, 9H),2.64(s,9H),6.56-6.62(m,9H),6.67-6.75 (m,9H),6.82-6.88(m,3H),6.91-6.97(t,3H),7 .00-7.12(m,6H),7.63-7.67(d,3H) [Explanation of symbols]

[0301] 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 113Ha1 First host material 113Ha2 Second host material 113b Second light-emitting layer 113Db Second phosphorescent compound 113H1 First Carrier Transport Compound 113H2 Second Carrier Transport Compound 113c Third luminescent layer 113Dc The third phosphorescent compound 113H3 The third carrier transport compound 113H4 The fourth carrier transport compound 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 407 Sealing substrate 412 Pad 420 IC chip 501 First electrode 502 Second electrode 511 First Light Emitting Unit 512 Second Light Emitting Unit 513 Charge generation layer 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 5000 display area 5001 Display area 5002 Display area 5003 Display area 5004 Display area 5005 Display area 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 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

[Claim 1] a first light-emitting layer including a first phosphorescent compound and a first host material, and a second light-emitting layer including a second phosphorescent compound, a first electron-transporting compound, and a first hole-transporting compound, between an anode and a cathode; an emission wavelength of the second phosphorescent compound is longer than an emission wavelength of the first phosphorescent compound; a triplet excitation energy of the first host material is equal to or higher than a triplet excitation energy of either the first electron transporting compound or the first hole transporting compound; A light emitting element in which the first light emitting layer and the second light emitting layer are provided in contact with each other.

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