Light emitting element

Abstract

To provide a multicolor light emitting element that is advantageous for practical use in a light emitting element using fluorescence emission and phosphorescence emission.SOLUTION: A light emitting element has a laminated structure of a first light emitting layer including a host material and a fluorescent emissive material, and a second light emitting layer containing two kinds of organic compounds forming an exciplex and a substance capable of converting triplet excitation energy into light emission. It is more useful to use a light emitting element in which the emission from the first light emitting layer has a peak of the emission spectrum on the shorter wavelength side than the light emitted from the second light emitting layer.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an article, a method, or a manufacturing method. The present invention relates to a method, manufacture, or composition of matter. One embodiment of the present invention is a semiconductor device, a display device, a light-emitting device, a power storage device, and a driving method thereof. In particular, one aspect of the present invention relates to a method for producing the same. A light-emitting element, a display module, a lighting module, a display device, and a light-emitting device used as a light-emitting element , electronic devices and lighting devices. [Background technology]

[0002] In recent years, electroluminescence (EL) using organic compounds has become Research and development of light-emitting elements (organic electroluminescence) that utilize luminescence is being actively carried out. The basic structure of these light-emitting elements is an organic compound layer (E By applying a voltage to this element, light is emitted from the luminescent material. can be obtained.

[0003] Such light-emitting elements are self-luminous, so they have high visibility and do not require a backlight. These advantages make it suitable for use as a flat panel display element. Another advantage of using such light-emitting devices is that they can be made thin and lightweight. Another advantage is that it has a fast response time.

[0004] These light emitting devices can emit light in a planar manner, making it easy to form large-area devices. This means that the light emitted from point light sources such as incandescent light bulbs and LEDs, as well as from fluorescent lamps, can be used This is a feature that is difficult to obtain with typical line light sources, making it highly useful as a light source for illumination, etc.

[0005] In such an organic EL element, electrons flow from the cathode and holes flow from the anode. The electrons and holes are injected into the EL layer, causing a current to flow. As a result, the light-emitting organic compound is excited, and light can be emitted.

[0006] The excited state of organic compounds is the singlet excited state (S * ) and triplet excited states (T * )but Emission from the singlet excited state is called fluorescence, and emission from the triplet excited state is called phosphorescence. The statistical generation ratio of the light emitting element is S * :T * =1:3 It is believed that.

[0007] In compounds that emit light from a singlet excited state (hereafter referred to as fluorescent substances), at room temperature, Usually, luminescence from the triplet excited state (phosphorescence) is not observed, but luminescence from the singlet excited state ( Therefore, only the internal quantum The theoretical limit of efficiency (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, In this case, light emission from the triplet excited state (phosphorescence) is observed. In addition, phosphorescent compounds exhibit intersystem crossing. Therefore, the internal quantum efficiency can theoretically reach 100%. Light-emitting elements using luminescent materials have a higher luminous efficiency than light-emitting elements using fluorescent materials. For this reason, in order to realize a highly efficient light-emitting device, In recent years, light-emitting devices using organic EL devices have been actively developed.

[0009] In Patent Document 1, a light-emitting region containing a plurality of light-emitting dopants is provided, A white light emitting element that emits phosphorescence is disclosed. The device has an intermediate layer (charge generating layer) between the phosphorescent light emitting layer (so-called tandem device). It has been done. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Special Publication No. 2004-522276 [Patent Document 2] JP 2006-024791 A Summary of the Invention [Problem to be solved by the invention]

[0011] Multi-color light-emitting devices, such as white light-emitting devices, are characterized by the use of a fluorescent layer and a phosphorescent layer. Elements with an intermediate layer (charge generating layer) have been developed and some have been put to practical use (for example, Patent Document In a light-emitting device having this structure, light emitted on the short wavelength side is obtained from the fluorescent layer, and light emitted on the long wavelength side is obtained from the The light emitted from the side is obtained from a phosphorescent layer.

[0012] This configuration converts the short-wavelength emission, which is prone to life-time issues, into fluorescence and the long-wavelength emission into phosphorescence. By doing so, the efficiency is lower than that of devices that derive all light emission from phosphorescence, but the efficiency is stable. The purpose of this configuration is to obtain a multi-color light-emitting element with excellent characteristics.

[0013] Multi-color light-emitting devices with this structure prioritize reliability over performance, but their life span is still an issue. Although it is advantageous for practical use in organic EL elements, it is difficult to obtain a single light-emitting element. At the same time, there is also a disadvantage in terms of practical application in that the number of membranes required is large.

[0014] In the multicolor light-emitting device having the above configuration, an intermediate layer is provided between the phosphorescent light-emitting layer and the fluorescent light-emitting layer. There are several reasons for this, one of which is to suppress the quenching of phosphorescence by the fluorescent layer. This is the case.

[0015] The fluorescent layer usually contains a condensed aromatic ring ( In particular, substances having a condensed aromatic hydrocarbon ring skeleton are used. Many of the substances with this property have relatively low triplet levels. When the phosphorescent layer is provided adjacent to the fluorescent layer, the triplet excitation energy generated in the phosphorescent layer is absorbed by the fluorescent layer. The triplet excitons are transferred to the triplet level of the host material and are deactivated. Triplet excitons have a long life span. Therefore, the diffusion distance of excitons is long, and the excitation energy generated at the interface between the fluorescent and phosphorescent emitting layers is Not only the excitation energy generated in the phosphorescent layer but also the excitation energy generated in the fluorescent layer The host material in the light-emitting layer deactivates the photoluminescence, causing a significant decrease in the luminescence efficiency. cormorant.

[0016] On the other hand, if a host material with high triplet excitation energy is used in the fluorescent layer, This problem is solved, but the singlet excitation energy of the host material is then very large. Therefore, the energy transfer from the host material to the fluorescent dopant is insufficient, and the fluorescence Insufficient luminous efficiency is obtained in the emitting layer. As a result, the non-radiative deactivation process of the host material This can lead to a decrease in the properties (especially the life) of the device. The fact that the singlet excitation energy of the material is large indicates that the HOMO-LUMO This is synonymous with a large gap, which also leads to an excessive increase in the driving voltage.

[0017] In view of the above, in one embodiment of the present invention, a light-emitting element using fluorescent light and phosphorescent light is The object of the present invention is to provide a light-emitting element that is advantageous for light emission. In light-emitting devices, the number of film layers is relatively small, which reduces the number of manufacturing steps and is advantageous for practical use. An object of the present invention is to provide a light-emitting element.

[0018] In another embodiment of the present invention, a light-emitting element using fluorescence and phosphorescence is An object of the present invention is to provide a light-emitting element having good luminous efficiency.

[0019] In another embodiment of the present invention, a light-emitting element using fluorescence and phosphorescence is A light-emitting device having a relatively small number of film layers, which is advantageous for practical use, and has good light-emitting efficiency Another object of the present invention is to provide a novel light-emitting element. The objective of the project is to

[0020] Another embodiment of the present invention is a device that can be manufactured at low cost by using the above-described light-emitting element. DISPLAY MODULE, LIGHTING MODULE, LIGHT-EMITTING DEVICE, DISPLAY DEVICE, ELECTRONIC DEVICE, AND LIGHTING DEVICE The purpose of this document is to provide the following:

[0021] Another embodiment of the present invention is a light-emitting element that consumes less power. Display module, lighting module, light-emitting device, display device, electronic device, and lighting The present invention aims to provide a device for

[0022] It is sufficient for the present invention to solve any one of the above problems. [Means for solving the problem]

[0023] The first light-emitting layer 113a includes a host material and a fluorescent material, and two types of exciplex-forming A second light-emitting layer 1 containing an organic compound of the above-mentioned type and a substance capable of converting triplet excitation energy into light emission. The light emitting device having a laminated structure with 13b can achieve the above object. The emission spectrum of the light emitted from the light-emitting layer 113a is on the shorter wavelength side than the emission from the second light-emitting layer 113b. Light emitting devices with a peak in the spectrum are more useful.

[0024] One aspect of the present invention is a light-emitting device having a pair of electrodes and an EL layer sandwiched between the pair of electrodes, The L layer has a first light-emitting layer 113a and a second light-emitting layer 113b. The emission spectrum from the second light-emitting layer 113a is shorter in wavelength than the emission spectrum from the second light-emitting layer 113b. The first light-emitting layer 113a is located in the long region and includes at least a fluorescent material and a host material. The second light-emitting layer 113b can convert at least triplet excitation energy into light emission. The present invention relates to a method for manufacturing a semiconductor device, comprising: The light-emitting element is characterized in that the second organic compound forms an exciplex.

[0025] Another embodiment of the present invention is a light-emitting diode having a pair of electrodes and an EL layer sandwiched between the pair of electrodes, The EL layer is formed by laminating a first light-emitting layer 113a and a second light-emitting layer 113b in contact with each other. The emission spectrum from the first light-emitting layer 113a is different from the emission spectrum from the second light-emitting layer 113b. The first light-emitting layer 113a is made of at least a fluorescent material. and a host material, and the second light-emitting layer 113b has at least a triplet excitation energy a material capable of converting light into light, a first organic compound, and a second organic compound, and the second organic compound form an exciplex. It is.

[0026] Alternatively, another embodiment of the present invention is a method for producing a triplet excited state from the exciplex in the above-described structure. A luminescent element characterized by the transfer of energy to a substance capable of converting the energy into luminescence. He is a child.

[0027] Alternatively, in the above-mentioned structure, another embodiment of the present invention is a method for manufacturing a semiconductor device comprising the steps of: is greater than the singlet excitation level of the fluorescent material, and the triplet excitation level of the host material is The light-emitting element is characterized in that the triplet excitation level is lower than that of the fluorescent material.

[0028] Alternatively, in the above-mentioned structure, another embodiment of the present invention is a triplet excitation level of the host material. is smaller than the triplet excitation levels of the first organic compound and the second organic compound. The light-emitting device is characterized by the above.

[0029] Alternatively, in the above-described structure, the host material may have a condensed aromatic ring skeleton. The light-emitting element is an organic compound having the above structure.

[0030] Alternatively, in another aspect of the present invention, in the above structure, the host material has an anthracene skeleton. The light-emitting element is an organic compound having the above structure.

[0031] Alternatively, in another aspect of the present invention, in the above-mentioned configuration, the host material is an anthracene skeleton. the fluorescent substance is an organic compound having a pyrene skeleton. It is a light emitting element.

[0032] Alternatively, in the above structure, another embodiment of the present invention is a semiconductor device having a structure in which the second light-emitting layer 113b is As the substances that can convert the triplet excitation energy into light emission, The light-emitting element is characterized by including a type of substance (n is an integer of 2 or more).

[0033] Alternatively, in the above-described structure, another embodiment of the present invention is such that the second light-emitting layer 113b is an n-layer. Each of the n layers is made of a material capable of converting triplet excitation energy into light. The light-emitting element is characterized by comprising:

[0034] Alternatively, in the above structure, another embodiment of the present invention is a semiconductor device having a structure in which the second light-emitting layer 113b is As the substances capable of converting the triplet excitation energy into light emission, A light-emitting element comprising a first phosphorescent material and a second phosphorescent material. .

[0035] Alternatively, in the above-mentioned structure, the first phosphorescent material is a red phosphorescent material. the second phosphorescent material has an emission in the green region, and the fluorescent material has an emission in the red region. The material is a light-emitting element that emits light in the blue region.

[0036] Alternatively, in the above-mentioned structure, the first phosphorescent material is The second phosphorescent material has an emission spectrum peak at 50 nm to 680 nm. The fluorescent substance has an emission spectrum peak at 400 nm to 560 nm. The light-emitting element has an emission spectrum peak in the range from 480 nm to 480 nm.

[0037] Alternatively, another embodiment of the present invention is a semiconductor device having the above structure, wherein the second light-emitting layer 113b is a first light-emitting layer. The first phosphorescent light-emitting layer is provided with a first phosphorescent light-emitting layer and a second phosphorescent light-emitting layer. the first phosphorescent-emitting layer contains a second phosphorescent-emitting material; The light emitting device is characterized by the above.

[0038] Alternatively, another embodiment of the present invention is a semiconductor device having the above structure, further comprising: A light-emitting device comprising the first phosphorescent-emitting layer and the second phosphorescent-emitting layer laminated in this order. It is an optical element.

[0039] Alternatively, in the above-described structure, the first light-emitting layer 113a may be an anode. The light-emitting element is one in which the second phosphorescent layer is formed on the cathode side.

[0040] Alternatively, in the above-mentioned configuration, the first phosphorescent material is A light-emitting device characterized in that the first phosphorescent layer exhibits carrier trapping properties. be.

[0041] Alternatively, in the above-mentioned structure, the carrier trapping property is an electron The light-emitting element is characterized by having a trapping property.

[0042] Another embodiment of the present invention is a display module including any one of the light-emitting elements described above. It is a rule.

[0043] Another embodiment of the present invention is a lighting module including any one of the light-emitting elements described above. be.

[0044] Another embodiment of the present invention is a light-emitting element according to any one of the above, and a light-emitting element controlling the light-emitting element. The light emitting device is provided with a means for detecting the light.

[0045] Alternatively, one embodiment of the present invention is a display device including any one of the above light-emitting elements in a display portion, The display device is provided with a means for controlling the elements.

[0046] Alternatively, one embodiment of the present invention is a light-emitting element including any one of the above light-emitting elements for an illumination portion, A lighting device with means for controlling the elements.

[0047] Another embodiment of the present invention is an electronic device including any of the above light-emitting elements.

[0048] Note that the light-emitting device in this specification includes an image display device using a light-emitting element. In addition, a connector, such as an anisotropic conductive film or TCP (Tape Carrier) The module has a printed wiring board (PCB) attached to the TCP. Modules with COG (Chip On Glass) technology or light emitting elements Therefore, all modules on which ICs (integrated circuits) are directly mounted are also included in the category of light-emitting devices. It also includes light-emitting devices used in lighting fixtures, etc. Effect of the Invention

[0049] In one embodiment of the present invention, in a light-emitting element using fluorescent light and phosphorescent light, the number of film layers is relatively large. It is therefore possible to provide a multi-color light-emitting device which is relatively small and advantageous for practical use.

[0050] In another embodiment of the present invention, a light-emitting element using fluorescence and phosphorescence is It is possible to provide a multi-color light-emitting device having good luminous efficiency.

[0051] In another embodiment of the present invention, a film is formed in a light-emitting element that uses fluorescent light and phosphorescent light. Multi-color light-emitting device having a relatively small number of layers, advantageous for practical use, and good luminous efficiency can be provided.

[0052] Another embodiment of the present invention is a light-emitting element that can be manufactured at low cost by using the light-emitting element. Display module, lighting module, light-emitting device, display device, electronic device, and lighting device Each of the above-mentioned devices may be provided with a different device.

[0053] Another embodiment of the present invention is a light-emitting element that can reduce power consumption. Display module, lighting module, light-emitting device, display device, electronic device, and lighting module A lighting device can be provided for each. [Brief description of the drawings]

[0054] [Figure 1] 1 is a conceptual diagram of a light-emitting element. [Diagram 2] FIG. 1 is a conceptual diagram of an active matrix light-emitting device. [Diagram 3] FIG. 1 is a conceptual diagram of an active matrix light-emitting device. [Figure 4] FIG. 1 is a conceptual diagram of an active matrix light-emitting device. [Diagram 5] FIG. 1 is a conceptual diagram of a passive matrix light-emitting device. [Figure 6] FIG. [Figure 7] FIG. [Figure 8] FIG. [Figure 9] FIG. [Figure 10]FIG. [Figure 11] 1 is a diagram illustrating an in-vehicle display device and a lighting device. [Figure 12] FIG. [Figure 13] FIG. 13 shows current density-luminance characteristics of the light-emitting element 1. [Figure 14] FIG. 13 shows luminance vs. current efficiency characteristics of the light-emitting element 1. [Figure 15] FIG. 13 shows voltage-luminance characteristics of the light-emitting element 1. [Figure 16] FIG. 13 shows luminance vs. external quantum efficiency characteristics of the light-emitting element 1. [Figure 17] Emission spectrum of light-emitting element 1. [Figure 18] FIG. 2 is a graph showing a change in normalized luminance over time of the light-emitting element 1. [Figure 19] 4 shows emission spectra of the light-emitting element 2 and the light-emitting element 3. [Figure 20] Emission spectrum of light-emitting element 4. [Figure 21] 1 is a correlation diagram of energy levels of each substance and an exciplex in a light-emitting element of one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0055] 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 embodiments and details thereof are not limited to those described above without departing from the spirit and scope of the present invention. It will be readily understood by those skilled in the art that the above may be modified in various ways. The present invention should not be construed as being limited to the description of the embodiments.

[0056] (Embodiment 1) A schematic diagram of a light-emitting element of one embodiment of the present invention is shown in FIG. The EL layer 1 has a pair of electrodes (a first electrode 101 and a second electrode 102) and a light-emitting layer 113. The light-emitting layer 113 includes a first light-emitting layer 113a and a second light-emitting layer 113b. It has.

[0057] In FIG. 1A, the EL layer 103 further includes a hole injection layer 111 and a hole transport layer 1 12, an electron transport layer 114 and an electron injection layer 115 are shown, but this laminate structure is only an example. However, the structure of the EL layer 103 in the light-emitting element of one embodiment of the present invention is not limited to this. In FIG. 1A, the first electrode 101 functions as an anode, and the second electrode 102 functions as a It is shown as functioning as a cathode.

[0058] The first light-emitting layer 113a contains a fluorescent material and a host material. The light emitting layer 113b contains a first organic compound, a second organic compound, and a phosphorescent material. In the light-emitting layer having the above-described configuration, the first organic compound and the second organic compound are The combination forms an inducing complex.

[0059] With this configuration, the first light-emitting layer 113a emits light derived from a fluorescent material. However, the second light-emitting layer 113b efficiently emits light originating from the phosphorescent material. In this light-emitting element, a charge generating layer is provided between the first light-emitting layer 113a and the second light-emitting layer 113b. Even if the device is not provided with a tandem element, both the fluorescent and phosphorescent emission are efficient. You can get it easily.

[0060] Usually, when a fluorescent layer and a phosphorescent layer are introduced into the same EL layer, phosphorescence is produced. The triplet excitation energy of the layer is transferred to the host material that occupies most of the fluorescent layer, This causes a significant decrease in luminous efficiency. This is because the fluorescent layer usually contains a host material Condensed aromatic rings (especially condensed aromatic hydrocarbon rings) such as anthracene, which have low triplet levels ) skeleton is used, the triplet excitation energy generated in the phosphorescent layer is This is because the phosphorus migrates to the host material of the fluorescent-emitting layer and is deactivated without any radiation. In the optical layer, the desired emission wavelength and good device characteristics can be obtained without using a substance with a condensed aromatic ring structure. Because it is difficult to obtain reliability, the fluorescent and phosphorescent layers are integrated into the same EL layer. With such a structure, it is difficult to obtain a light emitting element having good characteristics.

[0061] In addition, the triplet excited state has a long relaxation time, so the diffusion distance of excitons is long, and the fluorescent layer Most of the excitons generated in the phosphorescent layer away from the phosphorescence layer are transferred to the fluorescent layer by diffusion. What makes the situation even more serious is that the atoms move around and are deactivated without any radiation.

[0062] In this embodiment, the second light-emitting layer 113b is made of a first organic compound and a second organic compound. The compound forms an exciplex, and the triplet excitation energy is transferred from this exciplex to the phosphorescent material. The above problem can be solved by adopting a configuration in which light emission can be obtained by movement.

[0063] An exciplex is an excited state consisting of two substances. And exciplexes release energy. When the exciplex is released to the ground state, the two substances that formed the exciplex return to their original state. In other words, there is no ground state in an exciplex. Therefore, energy transfer between exciplexes and from other substances to exciplexes is possible in principle. This is unlikely to occur.

[0064] The generation of an exciplex in the light-emitting element is carried out by using, among the first organic compound and the second organic compound, When one of the cations is adjacent to the other anion, a direct exciplex is formed. The electroplex process is considered to be predominant. Even if one of the first and second organic compounds becomes excited, it quickly incorporates the other substance. Since the excitons in the second light-emitting layer 113b form an exciplex, most of the excitons in the second light-emitting layer 113b exists as an exciplex.

[0065] The singlet excitation energy of the exciplex is expressed by the H The energy between the higher HOMO level and the lower LUMO level of the OMO and LUMO levels Since this corresponds to the energy difference between the singlet excitation energies of the two organic compounds, The value of γ is also small, and the singlet excitation from the exciplex to the first organic compound and the second organic compound is No energy transfer occurs. Furthermore, the triplet excitation energy of the exciplex is converted to the first Preferably, the first organic compound and the second organic compound are smaller than the first organic compound or the second organic compound. The first organic compound and the second organic compound are selected so that the first organic compound and the second organic compound are smaller than each other. By selecting the exciplex, the energy is transferred from the exciplex to the first organic compound and the second organic compound. As mentioned above, the energy transfer between exciplexes can be reduced. Since there is almost no energy transfer, there is almost no diffusion of excitons in the second light-emitting layer 113b. As a result, the above-mentioned problems can be solved.

[0066] Here, the first light-emitting layer 113a and the second light-emitting layer 113b, which are fluorescent light-emitting layers, are in contact with each other. When the first light-emitting layer 113a is formed in the first light-emitting layer 113b, the exciplex emits light at the interface between the first light-emitting layer 113a and the host material. Energy transfer (especially triplet energy transfer) to the In the second light-emitting layer 113b, the diffusion of excitons hardly occurs, so that the excitons are released from the exciplex. The range in which energy transfer to the host material of the first light-emitting layer 113a occurs is extremely localized. The excited electrons remain in the vicinity of the interface between the first light-emitting layer 113a and the second light-emitting layer 113b. Therefore, the first light-emitting layer 113a and the second light-emitting layer 113b do not necessarily have to be in contact, but even if they are in contact, high efficiency can be achieved. That is, the first light-emitting layer 113a and the second light-emitting layer 113b are The element structure in which the light emitting layer 113b is formed in contact with the light emitting layer 113b is also one embodiment of the present invention.

[0067] In this way, the triplet excitation energy of the host material contained in the fluorescent-emitting layer is converted into phosphorescence. The triplet excitation energy of the first organic compound and the second organic compound contained in the layer is smaller than that of the second organic compound. Even in a case where the fluorescent light is not emitted from the semiconductor device, by applying one embodiment of the present invention, it is possible to obtain both fluorescent light and phosphorescent light. Thus, a light emitting element having excellent luminous efficiency can be obtained.

[0068] In the light-emitting element of one embodiment of the present invention, the first light-emitting layer 113a and the second light-emitting layer At the interface with 113b, the exciplex transfers energy to the host material of the first light-emitting layer 113a. Energy transfer (especially triplet energy transfer) and the phosphorescence from the first light-emitting layer 113a Even if energy transfer to the host material of the first light-emitting layer 113a occurs, a part of the energy is transferred to the first light-emitting layer 113a. That is, the first light-emitting layer 113a is configured to be capable of converting light into light in the three Singlet excited states are generated by triplet-triplet annihilation (TT annihilation; TTA). By making it easy to convert the exciplex to the hologram at the interface, A part of the triplet excitation energy transferred to the second light-emitting layer 113a is converted into fluorescent light. Thus, the light-emitting element according to one embodiment of the present invention can be It is possible to obtain a light-emitting element with reduced energy loss. In order to easily form the first light-emitting layer 113a, a single layer of the host material is used. The singlet excitation level of the fluorescent material is higher than the singlet excitation level of the host material. The host material and the fluorescent material are arranged so that the triplet excitation level of the fluorescent material is smaller than that of the fluorescent material. The host material and the fluorescent material that satisfy this relationship can be selected as follows: Typically, the host material is a material having an anthracene skeleton, and the fluorescent material is pyrene. A combination of materials having a skeleton is preferable.

[0069] If the first light-emitting layer 113a is too thick, the light emitted from the second light-emitting layer 113b may be reduced. Moreover, if the film thickness is too thin, it becomes difficult to obtain light emission from the first light-emitting layer 113a. Therefore, the thickness of the first light emitting layer 113a is set to be 5 nm or more and 20 nm or less. is preferred.

[0070] In addition, when the first light-emitting layer 113a is formed on the anode side, the first light-emitting layer 113a is In this case, the host material preferably has a bipolar layer having a high hole transporting property. It is preferable to use a material having an anthracene skeleton. Furthermore, when the fluorescent material has a high hole trapping property (e.g. The concentration of the condensed aromatic amine compound (described later) is 5% or less, preferably 1% or more. The ratio of the phosphorescence emission and the fluorescence emission is preferably 4% or less, and more preferably 1% to 3%. This is a preferred configuration for obtaining good lance and high efficiency. The hole trapping property occurs when O is higher than the HOMO of the host material.

[0071] In the second light-emitting layer 113b, a first organic compound and a second organic compound that form an exciplex are The combination of substances may be any combination that can form an exciplex, but It is more preferable that one of the first and second materials has a hole transporting property and the other has an electron transporting property. In this case, it becomes easier to form a donor-acceptor type excited state, and the excited complex is efficiently formed. In addition, a material having hole transport properties and a material having electron transport properties can be formed. A combination of a first organic compound and a second organic compound is formed by combining the first organic compound with a material that supports the first organic compound. When the mixture is made of the above-mentioned materials, the carrier balance can be easily controlled by the mixture ratio. In general, the ratio of the material having hole transport properties to the material having electron transport properties is 1:9 to 9:1 (weight ratio, In particular, in order to further increase the quantum efficiency, In the region of the light-emitting layer 113b closest to the anode, a material having a hole transporting property: Transportable material = 5:5 to 9:1 (weight ratio, including 5:5 and 9:1) In addition, it is more preferable that the light-emitting element having the above structure can easily achieve a carrier balance. Since the recombination region can be easily controlled, the recombination region can be easily controlled. The light-emitting element according to one embodiment of the present invention emits light by controlling the carrier balance as described above. It also has the feature of being able to adjust the light color.

[0072] In the light emitting device of this embodiment, the recombination region of the carriers has a certain degree of distribution. For this purpose, it is preferable that each light-emitting layer has an appropriate carrier trapping property. It is particularly preferable that the phosphorescent material has an electron trapping property. Diazine skeletons such as pyrimidine and pyrazine are examples of substances with high electron trapping properties. Examples include transition metal complexes with ligands containing hexagonal rings (such as iridium complexes and platinum complexes). In addition, the LUMO of the phosphorescent material is the same as that of either the first organic compound or the second organic compound. If the compound has a lower temperature than the above, the electron trapping property occurs.

[0073] In this light emitting device, the light emitted from the first light emitting layer 113a is mixed with the light emitted from the second light emitting layer 11 It is preferable that the emission peak is on the shorter wavelength side than the emission from 3b. Light-emitting elements using phosphorescent materials that emit light for a long period of time tend to deteriorate in luminance quickly. By using fluorescent light as the short-wavelength light emission, a light-emitting element with little deterioration in luminance can be provided. This can be done.

[0074] In addition, the number of layers for forming the EL layer in this light-emitting device is smaller than that in a tandem type device. Since the thickness of the layer is thin, the structure is cost-effective and suitable for mass production. Since the number of layers required to form the EL layer is small, the thickness of the EL layer can be made thin, and the light It is also an optically advantageous configuration (high light extraction efficiency). The present invention provides a light-emitting device that can efficiently emit both fluorescent and phosphorescent light at a driving voltage of 500 V or less. This can be done.

[0075] In addition, even if the fluorescent layer and the phosphorescent layer are in contact with each other, the above-mentioned exciplex is used. Therefore, the triplet excitation energy is less likely to be deactivated, and both phosphorescence and fluorescence can be achieved. This is a configuration that is easy to implement.

[0076] Correlation diagram of energy levels of each substance and an exciplex in the light-emitting element described in this embodiment This is shown in Figure 21. FH represents the singlet excitation of the host material in the first light-emitting layer 113a. level, T FH is the triplet excitation level of the host material in the first light-emitting layer 113a, S FG , T FG are the singlet excitation levels of the guest material (fluorescent material) in the first light-emitting layer 113a. , triplet excited level, S PH , T PH are the host materials in the second light-emitting layer 113b (the The singlet excitation level, triplet excitation level, S E ,T E are the singlet and triplet excitation levels of the exciplex in the second light-emitting layer 113b, T PG is the triplet excitation level of the guest material (phosphorescent material) in the second light-emitting layer 113b. .

[0077] As shown in FIG. 21, in the first light-emitting layer 113a, the triplet excited molecules of the host material collide with each other to emit light. This causes TTA, and some of the triplet excited molecules in the host material are converted to singlet excited molecules. (Part of it is thermally deactivated.) The singlet excited energy of the host material generated by this TTA The energy is transferred to the singlet excited state of the fluorescent material, and the energy is converted to fluorescence.

[0078] In the second light-emitting layer 113b, the excitation level S E ,T E The host material (first The excited level S of the first organic compound and the second organic compound PH ,T PH Since it is smaller than There is no transfer of excitation energy from the complex to the host material. Of course, there is no energy transfer to the exciplex. When the ions are transferred to the second light-emitting layer 113b, the ions are converted into light. There is almost no diffusion of triplet excitation energy and it is converted into light emission.

[0079] In this way, since there is almost no diffusion of triplet excitation energy, the first light-emitting layer 113a and the second light-emitting layer 113b are Although there is some energy transfer at the interface where the light emitting layer 113b is in contact (for example, T of phosphorescent materials present in PG From T FH Or T FG (e.g., energy transfer to the It is possible to obtain light emission with good efficiency from both the first light-emitting layer 113a and the second light-emitting layer 113b. In the first light-emitting layer 113a, the triplet excitation energy by TTA can be used. Since the singlet excited state is generated by the electrons, the energy transfer that occurs at the interface is also A portion of the light can be converted into fluorescent light, reducing energy loss. It is.

[0080] In addition, the light emitting element in this embodiment includes a first light emitting layer 113a and a second light emitting layer 113. By obtaining light of different emission wavelengths at b, a multicolor light emitting element can be obtained. The emission spectrum of a light-emitting element is a composite of light having different emission peaks. This results in an emission spectrum with at least two maxima.

[0081] In addition, such a light-emitting element is also suitable for obtaining white light emission. By making the light from the first light-emitting layer 113a and the second light-emitting layer 113b complementary to each other, white light can be obtained. In addition, it is possible to use a plurality of light-emitting materials having different emission wavelengths in either or both of the light-emitting layers. By using this material, it is possible to obtain white light with high color rendering consisting of three or more colors. In this case, each light-emitting layer is further divided into layers, and each divided layer is Different luminescent materials may be included.

[0082] In the second light-emitting layer 113b, the absorption energy of the phosphorescent material is on the lowest energy side. By overlapping the emission spectrum of the exciplex with that of the band, a light-emitting element with better luminous efficiency can be obtained. In addition, the peak wavelength of the absorption band on the lowest energy side of the phosphorescent material and the excitation wavelength can be calculated. The difference in the energy equivalent value of the peak wavelength of the emission spectrum of the complex is 0.2 eV or less. The overlap is large, which is the preferred configuration. The band is preferably an absorption band of a triplet excited level, and as described later, it is preferable to use a phosphorescent material instead. When using TADF materials, the lowest energy absorption band is the absorption band of the singlet excitation level. It is preferable that:

[0083] In FIG. 1A, the first light-emitting layer 113a is a first electrode 101 that functions as an anode. The second light-emitting layer 113b is formed on the second electrode 102 side which functions as a cathode. However, this stacking order may be reversed. That is, the first light-emitting layer 113a serves as a cathode. The second light-emitting layer 113b is formed on the second electrode 102 side, and functions as an anode. It may be formed on the first electrode 101 side.

[0084] In the configuration of this embodiment, the light-emitting material contained in the second light-emitting layer 113b is a triplet excited light-emitting material. Any substance that can convert photoelectric energy into light emission is acceptable. In the above explanation, phosphorescent substances The part described as “quality” is thermally activated delayed fluorescence (TFA). TADF (Tested Delayed Fluorescence) material and phosphorescent layer The part written above can be read as TADF light-emitting layer. What is TADF material? , the triplet excited state is up-converted to the singlet excited state by a small amount of thermal energy ( It is easy to induce reverse intersystem crossing, and efficiently emits light (fluorescence) from the singlet excited state. The condition for efficient thermally activated delayed fluorescence is that the triplet excited state The energy difference between the singlet excitation level and the singlet excitation level is 0 eV or more and 0.2 eV or less, preferably 0 eV or more and The triplet energy of both phosphorescent and TADF materials is 0.1 eV or less. A substance capable of converting excitation energy into luminescence.

[0085] (Embodiment 2) In this embodiment, a detailed structure example of the light-emitting element described in Embodiment 1 will be described with reference to FIG. ) will be used below for explanation.

[0086] 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.

[0087] 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 a material in which 1 to 20 wt% of zinc oxide is mixed with indium oxide. There is also a method of forming the film by sputtering using a target containing the oxide. Indium oxide containing tungsten and zinc oxide (IWZO) is In contrast, tungsten oxide was 0.5 to 5 wt% and zinc oxide was 0.1 to 1 wt%. It can also be formed by sputtering using a gold (Au) target. Platinum (Pt), Nickel (Ni), Tungsten (W), Chromium (Cr), Molybdenum ( Mo), iron (Fe), cobalt (Co), copper (Cu), palladium (Pd), or metal Nitrides of materials such as titanium nitride, etc. Graphene can also be used. In addition, a composite material to be described later is used for the layer in contact with the first electrode 101 in the EL layer 103. This makes it possible to select an electrode material regardless of the work function.

[0088] 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, other layers are not particularly limited. For example, a hole injection layer, a hole transport layer, a light emitting layer, an electron The layer can be constructed by appropriately combining a transport layer, an electron injection layer, a carrier block layer, an intermediate layer, etc. In this embodiment, the EL layer 103 is a hole transport layer formed in sequence on the first electrode 101. Injection layer 111, hole transport layer 112, light emitting layer 113, electron transport layer 114, electron injection layer 115 The materials constituting each layer are specifically described below.

[0089] The hole injection layer 111 is a layer containing a substance with high hole injection properties. Use of tungsten oxide, manganese oxide, etc. In addition, phthalocyanine (abbreviation: H2Pc) and copper phthalocyanine (CuPC) can be used. Phthalocyanine compounds such as 4,4'-bis[N-(4-diphenylaminophenyl )-N-phenylamino]biphenyl (abbreviation: DPAB), N,N'-bis{4-[bis (3-methylphenyl)amino]phenyl}-N,N'-diphenyl-(1,1'-biphenyl aromatic amine compounds such as phenyl-4,4'-diamine (abbreviation: DNTPD) or poly Poly(3,4-ethylenedioxythiophene) / Poly(styrenesulfonic acid) (PEDOT The hole injection layer 111 can also be formed from a polymer such as polysilicon (PSS).

[0090] 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.

[0091] 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.

[0092] 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.

[0093] 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.

[0094] 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.

[0095] 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 to do so.

[0096] 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.

[0097] 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.

[0098] 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.

[0099] 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.

[0100] In the light-emitting element of one embodiment of the present invention, when the first light-emitting layer 113a is provided on the anode side, The HOMO level of the material used in the hole transport layer 112 and the HOMO level of the material used in the first light emitting layer 113a are The HOMO levels of the materials are preferably close to each other (energy difference of 0.2 eV or less). This allows the holes to be trapped in the first light-emitting layer without being trapped too much in the trap level. Since the light flows into the second light-emitting layer 113a and the second light-emitting layer 113b, the fluorescent light emission and the phosphorescent light emission are balanced. Often, this is easy to achieve with good efficiency.

[0101] The light-emitting layer 113 has the structure of the light-emitting layer 113 described in the first embodiment. From the first electrode side, a first light emitting layer 113a and a second light emitting layer 113b are laminated. The first light-emitting layer 113a contains a host material and a fluorescent material, and the second light-emitting layer 113b contains a host material and a fluorescent material. The light-emitting layer 113b contains a first organic compound, a second organic compound, and a triplet excitation energy The material contains a substance (phosphorescent compound or TADF material) that can convert light into light. In the light-emitting element having the above structure, the first organic compound and the second organic compound are combined to form an exciplex. The exciplex is then capable of converting triplet excitation energy into luminescence. The energy is provided to the substance, and the first light-emitting layer 113a and the second light-emitting layer 113b emit light. It is possible to obtain light emission efficiently.

[0102] In the first light-emitting layer 113a, materials that can be used as the fluorescent material include Examples of the fluorescent materials include the following. There can be.

[0103] 5,6-Bis[4-(10-phenyl-9-anthryl)phenyl]-2,2'-bipyridine PAP2BPy, 5,6-bis[4'-(10-phenyl-9-anthracene N, N'-Bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-N,N' -Diphenyl-pyrene-1,6-diamine (abbreviation: 1,6FLPAPrn), N,N'- Bis(3-methylphenyl)-N,N'-bis[3-(9-phenyl-9H-fluorene -9-yl)phenyl]-pyrene-1,6-diamine (abbreviation: 1,6mMemFLPAP rn), N,N'-bis[4-(9H-carbazol-9-yl)phenyl]-N,N' -Diphenylstilbene-4,4'-diamine (abbreviation: YGA2S), 4-(9H-cal 4'-(10-phenyl-9-anthryl)-4'-(10-phenyl-9-benzol-9-yl)triphenylamine (Abbreviation: YGAPA), 4-(9H-carbazol-9-yl)-4'-(9,10-diphenyl Phenyl-2-anthryl)triphenylamine (abbreviation: 2YGAPPA), N,9-di Phenyl-N-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazo Perylene, 2,5,8,11-tetra-tert-butylamine (abbreviation: PCAPA), t-Butylperylene (TBP), 4-(10-phenyl-9-anthryl)-4' -(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCB APA), N,N''-(2-tert-butylanthracene-9,10-diyldi-4 ,1-phenylene)bis[N,N',N'-triphenyl-1,4-phenylenediamine ](abbreviation: DPABPA), N,9-diphenyl-N-[4-(9,10-diphenyl- 2-Anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: 2PCAPPA ), N-[4-(9,10-diphenyl-2-anthryl)phenyl]-N,N',N' -Triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPPA), N,N,N' ,N',N'',N'',N''',N'''-Octaphenyldibenzo[g,p]chloride Cen-2,7,10,15-tetraamine (abbreviation: DBC1), Coumarin 30, N-(9 ,10-diphenyl-2-anthryl)-N,9-diphenyl-9H-carbazole-3 -amine (abbreviation: 2PCAPA), N-[9,10-bis(1,1'-biphenyl-2- yl)-2-anthryl]-N,9-diphenyl-9H-carbazol-3-amine (abbreviation Name: 2PCABPhA), N-(9,10-diphenyl-2-anthryl)-N,N', N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPA), N-[9, 10-Bis(1,1'-biphenyl-2-yl)-2-anthryl]-N,N',N'- Triphenyl-1,4-phenylenediamine (abbreviation: 2DPABPhA), 9,10-Bi S(1,1'-biphenyl-2-yl)-N-[4-(9H-carbazol-9-yl) Phenyl]-N-phenylanthracen-2-amine (abbreviation: 2YGABPhA), N, N,9-triphenylanthracene-9-amine (abbreviation: DPhAPhA), Coumarin 5 45T, N,N'-diphenylquinacridone, (abbreviation: DPQd), rubrene, 5,12 -Bis(1,1'-biphenyl-4-yl)-6,11-diphenyltetracene (abbreviation: BPT), 2-(2-{2-[4-(dimethylamino)phenyl]ethenyl}-6-methyl 2-(4H-pyran-4-ylidene)propanedinitrile (abbreviation: DCM1), Methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinoline Lysin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation Name: DCM2), N,N,N',N'-tetrakis(4-methylphenyl)tetracene 5,11-diamine (abbreviation: p-mPhTD), 7,14-diphenyl-N,N,N', N'-Tetrakis(4-methylphenyl)acenaphtho[1,2-a]fluoranthene-3 ,10-diamine (abbreviation: p-mPhAFD), 2-{2-isopropyl-6-[2-( 1,1,7,7-Tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanediyl tolyl (abbreviation: DCJTI), 2-{2-tert-butyl-6-[2-(1,1,7, 7-Tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolin 4H-pyran-4-ylidene)propanedinitrile (abbreviation) :DCJTB), 2-(2,6-bis{2-[4-(dimethylamino)phenyl]ethene {4H-pyran-4-ylidene}propanedinitrile (abbreviation: BisDCM), 2- {2,6-bis[2-(8-methoxy-1,1,7,7-tetramethyl-2,3,6,7 -Tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H -pyran-4-ylidene}propanedinitrile (abbreviation: BisDCJTM) In particular, pyrenes such as 1,6FLPAPrn and 1,6mMemFLPAPrn Condensed aromatic diamine compounds, such as amine compounds, have high hole trapping properties and high luminescence efficiency. This is preferred because it has excellent efficiency and reliability.

[0104] In the first light-emitting layer 113a, examples of a substance that can be used as a host material include For example, the following can be mentioned:

[0105] 9-Phenyl-3-[4-(10-phenyl-9-anthryl)phenyl]-9H-ca Rubazol (abbreviation: PCzPA), 9-[4-(10-phenyl-9-anthracenyl) phenyl]-9H-carbazole (abbreviation: CzPA), 7-[4-(10-phenyl-9 -anthryl)phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBC zPA), 6-[3-(9,10-diphenyl-2-anthryl)phenyl]-benzo[ b]naphtho[1,2-d]furan (abbreviation: 2mBnfPPA), 9-phenyl-10-{ 4-(9-phenyl-9H-fluoren-9-yl)biphenyl-4'-yl}anthra Examples of anthracene compounds include phenylene (abbreviation: FLPPA). By using such a substance as a host material, it is possible to realize a light-emitting layer with good luminous efficiency and durability. In particular, CzPA, cgDBCzPA, 2mBnfPPA, and PCzPA are It exhibits very good properties and is therefore the preferred choice.

[0106] In the second light-emitting layer 113b, a material capable of converting triplet excitation energy into light emission The materials that fall under this category are phosphorescent materials and TADF materials, for example: can be done.

[0107] The phosphorescent material is 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 ethyl-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-triazolato]iridium(III) (abbreviation: Ir(i Organometallic iridium complexes with 4H-triazole skeletons such as Prptz-3b)3) The body and tris[3-methyl-1-(2-methylphenyl)-5-phenyl-1H-1,2 ,4-Triazolate]iridium(III) (abbreviation: Ir(Mptz1-mp)3), Tris(1-methyl-5-phenyl-3-propyl-1H-1,2,4-triazolato)i 1H-Triazolium such as iridine(III) (abbreviation: Ir(PrptZ1-Me)3) Organometallic iridium complexes with fac-tris[(1-2,6-diisopropyl Iridium(III) (abbreviation: Ir (iPrpmi)3), tris[3-(2,6-dimethylphenyl)-7-methylimidazolium Dizo[1,2-f]phenanthridinato]iridium(III) (abbreviation: Ir(dmpim Organometallic iridium complexes with imidazole skeletons such as bis[2 -(4',6'-difluorophenyl)pyridinato-N,C 2’ ]Iridium(III) Tetrakis(1-pyrazolyl)borate (abbreviation: FIr6), bis[2-(4',6'- Difluorophenyl)pyridinato-N,C 2’ ]Iridium(III) picolinate (abbreviation Name: FIrpic), bis{2-[3',5'-bis(trifluoromethyl)phenyl] Pyridinate-N,C 2’}Iridium(III) picolinate (abbreviation: Ir(CF3pp y) 2(pic)), bis[2-(4',6'-difluorophenyl)pyridinato-N, C 2’ ]Iridium(III) acetylacetonate (abbreviation: FIracac) Organometallic iridium complexes with phenylpyridine derivatives bearing electron-withdrawing groups as ligands have been proposed. These are compounds that exhibit blue phosphorescence and emit light at wavelengths from 440 nm to 520 nm. It is a compound that has a luminescence peak.

[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) Title: Organometallic iridium compounds with pyrazine skeleton, such as Ir(mppr-iPr)2(acac) Lithium complex, tris(2-phenylpyridinato-N,C 2’ ) Iridium(III)( Abbreviation: Ir(ppy)3), Bis(2-phenylpyridinato-N,C 2’ )iridium( III) Acetylacetonate (abbreviation: Ir(ppy)2(acac)), bis(benzo [h]Quinolinato)iridium(III) acetylacetonate (abbreviation: Ir(bzq) 2(acac)), tris(benzo[h]quinolinato)iridium(III) (abbreviation: I r(bzq)3), tris(2-phenylquinolinato-N,C 2’ ) Iridium (III ) (abbreviation: Ir(pq)3), bis(2-phenylquinolinato-N,C 2’ )iridium (III) Pyridyl acetylacetonate (abbreviation: Ir(pq)2(acac)) In addition to organometallic iridium complexes with a phenyl skeleton, tris(acetylacetonato)(monophenyl) Anthroline) terbium(III) (abbreviation: Tb(acac)3(Phen)) Rare earth metal complexes can also be used. These are mainly compounds that exhibit green phosphorescence. It has an emission peak at 500 nm to 600 nm. The organometallic iridium complex is particularly preferred because it has excellent reliability and luminous efficiency. .

[0109] Also, (diisobutyrylmethanato)bis[4,6-bis(3-methylphenyl)pyrimidinium] dinato]iridium(III) (abbreviation: Ir(5mdppm)2(dibm)), bis[ 4,6-Bis(3-methylphenyl)pyrimidinate](dipivaloylmethanate)iridium Ir(III) (abbreviation: Ir(5mdppm)2(dpm)), bis[4,6-di(naphthalene [(1-phenyl-1-yl)pyrimidinato](dipivaloylmethanato)iridium(III)(abbreviation Organometallic iridium compounds with pyrimidine skeletons, such as Ir(dpm)2(dpm) (acetylacetonato)bis(2,3,5-triphenylpyrazinate)iridine complexes Ir(tppr)2(acac)), bis(2,3,5-trifluoroethylene) (phenylpyrazinato)(dipivaloylmethanato)iridium(III) (abbreviation: Ir(tp pr)2(dpm)), (acetylacetonato)bis[2,3-bis(4-fluorophenyl) Iridium(III) (abbreviation: 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) (abbreviation: Ir(piq)2 In addition to organometallic iridium complexes with pyridine skeletons such as (acac)), 2,3,7 ,8,12,13,17,18-Octaethyl-21H,23H-porphyrin platinum(I I) (abbreviation: PtOEP) and tris(1,3-diphenyl-1,3- Propanedionato)(monophenanthroline)europium(III) (abbreviation: Eu(D BM)3(Phen)), tris[1-(2-thenoyl)-3,3,3-trifluoroacetate [Cetonato](monophenanthroline)europium(III) (abbreviation: Eu(TTA)3 Rare earth metal complexes such as (Phen) can also be used. These give red phosphorescence. It is a compound that emits light and has a peak emission wavelength of 600 to 700 nm. An organometallic iridium complex having a radine skeleton can emit red light with good chromaticity.

[0110] In addition to the phosphorescent compounds described above, various phosphorescent light-emitting materials can be selected and used. good.

[0111] The following TADF materials can be used:

[0112] Fullerene and its derivatives, acridine derivatives such as proflavine, eosin, etc. Magnesium (Mg), Zinc (Zn), Cadmium (Cd), Tin (Sn), Platinum (Pt) , indium (In), or palladium (Pd), or the like. Examples of metal-containing porphyrins include protoporphyrin- Tin fluoride complex (SnF2(Proto IX)), mesoporphyrin-tin fluoride complex (SnF2(Meso IX)), hematoporphyrin-tin fluoride complex (SnF2(H emato IX), coproporphyrin tetramethyl ester-tin fluoride complex (S nF2(Copro III-4Me)), Octaethylporphyrin-Tin Fluoride Complex (SnF2(OEP)), etioporphyrin-tin fluoride complex (SnF2(Etio I)), octaethylporphyrin-platinum chloride complex (PtCl2OEP), etc. .

[0113] [ka]

[0114] In addition, 2-(biphenyl-4-yl)-4,6-bis(12-phenyl)-2-phenylpropanediol having the following structural formula is also available. phenylindolo[2,3-a]carbazol-11-yl)-1,3,5-triazine ( Heteroaromatic rings with π-electron rich and π-electron deficient heteroaromatic rings, such as PIC-TRZ A heterocyclic compound can also be used. The heterocyclic compound can be a π-electron-rich heteroaromatic ring and a π-electron Since it has a deficient heteroaromatic ring, it has high electron transport properties and hole transport properties, which is preferable. A substance in which an electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring are directly bonded is called a π-electron-rich The donor property of the heteroaromatic ring and the acceptor property of the π-electron-deficient heteroaromatic ring are both strong, resulting in S1 This is particularly preferred since the energy difference between the T1 level and the T2 level becomes small.

[0115] [ka]

[0116] The first organic compound and the second organic compound can be used as the above-mentioned materials. As long as the combination satisfies the conditions described in the first embodiment, there is no particular limitation, and various combinations can be used. A carrier transport material can be selected.

[0117] For example, bis(10-hydroxybenzo[h]quinolidinyl) Nat)beryllium(II)(abbreviation:BeBq2), bis(2-methyl-8-quinolinolato )(4-phenylphenolato)aluminum(III)(abbreviation: BAlq), bis(8- Quinolinolato)zinc(II)(abbreviation:Znq), bis[2-(2-benzoxazolyl) phenolato]zinc(II) (abbreviation: ZnPBO), bis[2-(2-benzothiazolyl) Metal complexes such as phenolato zinc(II) (abbreviation: ZnBTZ) and 2-(4-biphenyl (aryl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation : PBD), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl) phenyl)-1,2,4-triazole (abbreviation: TAZ), 1,3-bis[5-(p-tert-butyl) rt-Butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl) phenyl]-9H-carbazole (abbreviation: CO11), 2,2',2''-(1,3,5 -benzenetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TP BI), 2-[3-(dibenzothiophen-4-yl)phenyl]-1-phenyl-1H -benzimidazole (abbreviation: mDBTBIm-II) and other polyazole skeletons Heterocyclic compounds, 2-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f, h]quinoxaline (abbreviation: 2mDBTPDBq-II), 2-[3'-(dibenzothiophene [f,h]quinoxaline (abbreviation: 2m DBTBPDBq-II), 2-[3'-(9H-carbazol-9-yl)biphenyl -3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzBPDBq), 4,6- Bis[3-(phenanthren-9-yl)phenyl]pyrimidine (abbreviation: 4,6mPnP 2Pm), 4,6-bis[3-(4-dibenzothienyl)phenyl]pyrimidine (abbreviation: Heterocyclic compounds with diazine skeletons such as 4,6mDBTP2Pm-II, 3,5-biphenyl 35DCzPP y), 1,3,5-tri[3-(3-pyridyl)phenyl]benzene (abbreviation: TmPyP B) and other heterocyclic compounds having a pyridine skeleton. Heterocyclic compounds having a pyridine skeleton and heterocyclic compounds having a pyridine skeleton have good reliability. In particular, heterocyclic compounds having a diazine (pyrimidine or pyrazine) skeleton are preferred. It has high transportability and also contributes to reducing the driving voltage.

[0118] As a material having a hole transporting property, 4,4'-bis[N-(1-naphthyl)-N- Phenylamino]biphenyl (abbreviation: NPB), N,N'-bis(3-methylphenyl) -N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (abbreviation: TP D) 4,4'-bis[N-(spiro-9,9'-bifluoren-2-yl)-N-phenyl 4-phenyl-4'-(9-phenylfuranylamino)biphenyl (abbreviation: BSPB), oren-9-yl)triphenylamine (abbreviation: BPAFLP), 4-phenyl-3'- (9-phenylfluoren-9-yl)triphenylamine (abbreviation: mBPAFLP), 4-Phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenyla PCBA1BP, 4,4'-diphenyl-4''-(9-phenyl-9- H-carbazol-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-( 1-Naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)-triphenyl PCBANB, 4,4'-di(1-naphthyl)-4''-(9-phenyl)amine PCBNBB, 9H-carbazol-3-yl)triphenylamine ,9-Dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazole-3- N-phenyl-N-phenyl]-fluoren-2-amine (abbreviation: PCBAF), [4-(9-phenyl-9H-carbazol-3-yl)phenyl]-spiro-9,9' -bifluorene-2-amine (abbreviation: PCBASF) and other compounds with aromatic amine skeletons Compounds, 1,3-bis(N-carbazolyl)benzene (abbreviation: mCP), 4,4'-di( N-carbazolyl)biphenyl (abbreviation: CBP), 3,6-bis(3,5-diphenyl 3,3'-bis(9-phenyl)-9-phenylcarbazole (abbreviation: CzTP), Compounds having a carbazole skeleton, such as PCCP (Propylene Carbonate), 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene)( Abbreviation: DBT3P-II), 2,8-diphenyl-4-[4-(9-phenyl-9H-fu (fluoren-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-III), 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldi Compounds with a thiophene skeleton, such as benzothiophene (abbreviation: DBTFLP-IV), 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviation :DBF3P-II), 4-{3-[3-(9-phenyl-9H-fluoren-9-yl )phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II) Among the above, compounds having an aromatic amine skeleton are preferred. Compounds having a carbazole skeleton have good reliability and high hole transport properties. This is also preferable since it contributes to reducing the driving voltage.

[0119] In addition to the above-mentioned carrier transport materials, various carrier transport materials are used. The first organic compound and the second organic compound may be three phosphorescent compounds. It has a triplet level greater than the singlet level (energy difference between the ground state and the triplet excited state). It is preferable to select a material that is phosphorus-containing. An exciplex that emits light with a wavelength that overlaps with the lowest energy absorption band of a photoluminescent substance is called It is preferable to select a combination that forms

[0120] Furthermore, one of the combination of the first organic compound and the second organic compound is an organic compound having an electron transport property. By using one material having hole transport properties and the other material having hole transport properties, it is advantageous for the formation of an exciplex. In addition, the transport properties of the light-emitting layer can be easily adjusted by changing the content of each compound. The recombination region can be easily controlled. The ratio of the content of the material having the electron transport property is: material having the hole transport property: material having the electron transport property. The ratio should be between 1:9 and 9:1.

[0121] The light-emitting layer 113 having the above-mentioned structure can be formed by co-deposition in a vacuum deposition method or by forming a mixed solution. It can be produced by using an inkjet method, a spin coating method, a dip coating method, etc. do.

[0122] In this embodiment, the first light-emitting layer 113a is disposed on the anode side, and the second light-emitting layer 113b is disposed on the cathode side. Although the structure in which the layer 113b is formed has been described, the stacking order may be reversed. The second light-emitting layer 113b may be formed on the anode side, and the first light-emitting layer 113a may be formed on the cathode side. .

[0123] The second light-emitting layer 113b may be divided into two or more layers. In particular, the second light-emitting layer 113b may contain a different light-emitting material than the first phosphorus. It is divided into two layers: a light-emitting layer and a second phosphorescent-emitting layer. The first phosphorescent-emitting layer emits red light. The emission (emission having a peak in the emission spectrum at 580 nm to 680 nm) is The phosphorescent layer emits green light (having a peak in the emission spectrum at 500 nm to 560 nm). The first light-emitting layer 113a emits blue light (light having a wavelength of 400 nm or less). If the composition is such that light emission having a peak in the emission spectrum at 480 nm can be obtained, the color rendering This is a preferable configuration because it is possible to obtain good white light emission. The light-emitting layers are laminated in the following order: first light-emitting layer 113a, first phosphorescent light-emitting layer, second phosphorescent light-emitting layer, and so on. It is preferable that the first light-emitting layer 11 is a light-emitting layer from the viewpoint of durability of the light-emitting device. It is preferable that 3a is formed on the anode side in order to obtain better characteristics.

[0124] The configuration and effects of the light-emitting layer 113 other than those described above are the same as those described in the first embodiment. Please refer to the description in the first embodiment.

[0125] 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.

[0126] 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.

[0127] In addition, a layer for controlling the movement of electron carriers may be provided between the electron transport layer and the light emitting layer. This is achieved by adding a small amount of a substance with high electron trapping properties to a material with high electron transport properties as described above. A layer that adjusts the carrier balance by suppressing the movement of electron carriers. This type of structure prevents light from being emitted by electrons passing through the light-emitting layer. This is highly effective in suppressing problems that arise (such as a decrease in element life).

[0128] 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.

[0129] The material for forming the second electrode 102 is a material having a small work function (specifically, 3.8 eV Metals, alloys, electrically conductive compounds, and mixtures thereof can be used. Examples of such cathode materials include lithium (Li) and cesium (Cs). Potash metal, as well as magnesium (Mg), calcium (Ca), and strontium (Sr) Elements belonging to Group 1 or 2 of the Periodic Table, such as Mg, Ag, etc., and alloys containing these elements (e.g., , AlLi), europium (Eu), ytterbium (Yb), and other rare earth metals However, the second electrode 102 and the electron transport layer may be formed of a material other than the above-mentioned material. By providing an electron injection layer, the material can be made of Al, Ag, ITO, and ketone regardless of the magnitude of the work function. Various conductive materials such as indium oxide-tin oxide containing silicon oxide or indium tin oxide are used as the second These conductive materials can be used as the electrode 102 by sputtering or in-situ deposition. The film can be formed by using a jet method, a spin coating method, or the like.

[0130] 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. .

[0131] 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.

[0132] 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

[0133] 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 may be made of a light-transmitting electrode.

[0134] The EL layer 103 provided between the first electrode 101 and the second electrode 102 has a structure as follows: However, the above-mentioned materials are not limited to the above. However, the materials used for the light-emitting region, the electrodes, and the carrier injection layer are In order to suppress quenching caused by the proximity of the first electrode 101 and the metal, A preferred configuration is one in which a light-emitting region where holes and electrons recombine is provided at a location away from the second electrode 102. I wish.

[0135] In addition, the hole transport layer and the electron transport layer in contact with the light emitting layer 113, particularly the light emitting layer 113 The carrier transport layer, which is adjacent to the region closer to the active layer, is responsible for the energy transfer from the excitons generated in the light-emitting layer. In order to suppress the band gap, the luminescent material constituting the luminescent layer or the material contained in the luminescent layer is The material has a band gap larger than that of the luminescent center material. It is preferable to form the

[0136] 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 substrate made of glass, plastic, or the like can be fabricated using a field effect device, for example. A transistor (FET) is formed, and a light-emitting element is fabricated on an electrode electrically connected to the FET. This allows an active matrix that controls the driving of the light-emitting element by the FET. A light emitting device of a FET type can be fabricated. The structure of the FET is not particularly limited. The crystallinity of the semiconductor used for T is not particularly limited, and an amorphous semiconductor may be used. Crystalline semiconductors may also be used. The driving circuits formed on the FET substrate are also made of N It may be composed of N-type and P-type FETs, or N-type FETs or P-type FETs. It may be only one of the two.

[0137] Note that this embodiment mode can be appropriately combined with other embodiment modes.

[0138] Next, a light-emitting element having a structure in which a plurality of light-emitting units are stacked (hereinafter, also referred to as a stacked element) The embodiment will be described with reference to FIG. 1(B). This light-emitting element has a first electrode and a second electrode. The light-emitting element has a plurality of light-emitting units between the electrodes. 1(A) in the same structure as the EL layer 103 shown in FIG. The element is 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 to be a light-emitting element having a unit.

[0139] In FIG. 1B, a first light-emitting unit is disposed between a first electrode 501 and a second electrode 502. The knit 511 and the second light-emitting unit 512 are laminated, and the first light-emitting unit 511 A charge generating layer 513 is provided between the first electrode and the second light-emitting unit 512. 501 and the second electrode 502 correspond to the first electrode 101 and the second electrode 102 in FIG. 102, and the same as that described in the explanation of FIG. 1(A) can be applied. In addition, the first light emitting unit 511 and the second light emitting unit 512 may have the same configuration but have different It may be a configuration.

[0140] 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. As an organic compound, a composite material with a hole mobility of 1×10 -6 cm 2 / Vs or more. However, it is preferable to use a valence electron transporter with a higher transport efficiency than a valence electron transporter. Other substances may be used as long as they have high conductivity. The composite material has excellent carrier injection and transport properties, making it suitable for low-voltage and low-current driving. In addition, when the surface of the light-emitting unit on the anode side 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 unit does not necessarily need to have a hole transport layer.

[0141] 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, the organic compound may be formed as a laminated structure in which a layer made of the organic compound is combined with the layer made of the organic compound. and a layer including a composite material of a metal oxide and a compound selected from the electron donating materials and an electron A layer containing a compound having high transport properties may be formed by combining an organic compound and a gold compound. Alternatively, a layer containing a composite material of metal oxides and a transparent conductive film may be combined.

[0142] 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. 1B, the potential of the first electrode is higher than the potential of the second electrode. When a voltage is applied so that the charge generating layer 513 emits electrons to the first light-emitting unit 511, It is sufficient that the second light-emitting unit 512 injects holes into the first light-emitting unit 512.

[0143] Although the light emitting element having two light emitting units has been described in FIG. 1B, the light emitting element having three or more light emitting units may be used. The present invention can be similarly applied to a light-emitting device in which the light-emitting units are stacked. As in the light-emitting device according to the embodiment, a plurality of light-emitting units are separated by a charge generating layer between a pair of electrodes. By cutting and arranging the LEDs, it is possible to emit high-intensity light while keeping the current density low, and it also has a long life. It is also possible to realize a light-emitting device that can be driven at a low voltage and consumes low power. This can be done.

[0144] 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.

[0145] The above configuration may be appropriately combined with other embodiments or other configurations in this embodiment. It is possible.

[0146] (Embodiment 3) In this embodiment, a light-emitting device using the light-emitting element described in Embodiment 1 or 2 This article explains:

[0147] In this embodiment, a light-emitting element manufactured using the light-emitting element described in Embodiment 1 or 2 is used. The light-emitting device will be described with reference to FIG. 2. FIG. 2(A) is a top view of the light-emitting device. FIG. 2B is a cross-sectional view taken along lines AB and CD in FIG. 2A. The light emission of the light emitting element is controlled by a driving circuit section (source line driving circuit) shown by a dotted line. The display device includes a display circuit (gate line driver) 601, a pixel section 602, and a driver circuit section (gate line driver circuit) 603. 604 is a sealing substrate, 605 is a sealing material, and the inside surrounded by the sealing material 605 is a space. It's now 607.

[0148] 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.

[0149] Next, the cross-sectional structure will be described with reference to FIG. A source line driver circuit 601, which is a driver circuit section, and a pixel section are formed in this example. 6, one pixel in the pixel section 602 is shown.

[0150] The source line driver circuit 601 includes an n-channel FET 623 and a p-channel FET 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.

[0151] The pixel section 602 includes a switching FET 611, a current control FET 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.

[0152] Also, the insulator 614 is designed to have a curved surface at the upper or lower end. For example, when a positive photosensitive acrylic is used as the material of the insulator 614, In this case, only the upper end of the insulator 614 has a curved surface having a radius of curvature (0.2 μm to 3 μm). The insulator 614 may be either a negative photosensitive resin or a positive photosensitive resin. It can be used.

[0153] 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 to 20 wt% zinc oxide, titanium nitride film In addition to single-layer films such as chromium film, tungsten film, zinc film, and platinum film, titanium nitride film and aluminum film are also available. 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 also function as an anode. Cut.

[0154] The EL layer 616 is formed by deposition using a deposition mask, inkjet printing, spin coating, etc. The EL layer 616 is formed by various methods such as the method of forming the EL layer 616 shown in FIG. 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). .

[0155] 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 6 made of a material such as MgAg, MgIn, or AlLi. In the case where the light generated in 16 is transmitted through the second electrode 617, a film is used as the second electrode 617. Thin metal films and transparent conductive films (ITO, oxide containing 2 to 20 wt% zinc oxide) Indium, silicon-containing indium tin oxide, zinc oxide (ZnO, etc.) It is good to use.

[0156] 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 of the first embodiment or the second embodiment. Note that the pixel portion is formed with a plurality of light emitting elements. The optical device includes the light-emitting element described in embodiment 1 or embodiment 2 and other components. The light emitting element may include both a light emitting element and a light emitting element.

[0157] 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.

[0158] 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 is glass substrate, quartz substrate, FRP (Fiberglass), etc. Reinforced Plastics), PVF (Polyvinyl fluoride), Polyethylene A plastic substrate made of, for example, steel or acrylic can be used.

[0159] In the above manner, a light-emitting element according to the present invention is manufactured using the light-emitting element described in Embodiment 1 or 2. A light emitting device having such a structure can be obtained.

[0160] In FIG. 3, a light emitting element that emits white light is formed, and a colored layer (color filter) and the like are provided. FIG. 3(A) shows a substrate 1001, an insulating layer 1002, and a light-emitting device 1003. An insulating film 1002, a gate insulating film 1003, gate electrodes 1006, 1007, 1008, a first the first interlayer insulating film 1020, the second interlayer insulating film 1021, the peripheral portion 1042, the pixel portion 1040, A driving circuit section 1041, first electrodes 1024W, 1024R, 1024G, and 10 24B, a partition wall 1025, an EL layer 1028, a second electrode 1029 of the light-emitting element, and a sealing substrate 10 31, sealing material 1032, etc. are shown.

[0161] In addition, in FIG. 3(A), the colored layers (red colored layer 1034R, green colored layer 1034G, blue The colored layer 1034B is provided on the transparent substrate 1033. A transparent substrate provided with a colored layer and a black layer may be provided. 1033 is aligned and fixed to the substrate 1001. In FIG. 3(A), the colored layer is covered with an overcoat layer 1036. There are light-emitting layers that emit light to the outside without passing through the light source, and light-emitting layers that transmit light through the colored layers of each color and emit light to the outside. The light that does not pass through the colored layer is white, and the light that passes through the colored layer is red, blue, and green, so there are four colors. Images can be expressed using pixels.

[0162] In FIG. 3B, the colored layers (red colored layer 1034R, green colored layer 1034G, blue colored layer An example in which a layer (1034B) is formed between the gate insulating film (1003) and the first interlayer insulating film (1020) In this way, the colored layer is provided between the substrate 1001 and the sealing substrate 1031. is also good.

[0163] In the light emitting device described above, light is taken in toward the substrate 1001 on which the FET 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. 4. In this case, a substrate 1001 that does not transmit light is used. Until the connection electrode that connects the FET 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 various materials, including the same material as the second interlayer insulating film. It is possible.

[0164] The first electrodes 1024W, 1024R, 1024G, and 1024B of the light-emitting element are positive electrodes. The electrode is generally the cathode, but it can also be the cathode. In the case of a device, it is preferable that the first electrode is a reflective electrode. The EL layer 103 has the same structure as that described in the first or second embodiment. In addition, the device structure is designed to provide white light emission.

[0165] In the top emission structure shown in Figure 4, the colored layers (red colored layer 1034R, green The sealing is performed using a sealing substrate 1031 provided with a colored layer 1034G and a blue colored layer 1034B. The sealing substrate 1031 has a black layer (black A coloring layer (a red coloring layer 1034R, a green coloring layer 1035R, a matrix) may be provided. The layer 1034G, the blue colored layer 1034B, and the black layer (black matrix) 1035 are The sealing substrate 1031 may be covered with an overcoat layer. A substrate will be used.

[0166] 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.

[0167] The light-emitting device in this embodiment includes the light-emitting element described in Embodiment 1 or 2. Since the organic EL element is used, a light emitting device having excellent characteristics can be obtained. The light-emitting element described in embodiment 1 or embodiment 2 has high emission efficiency and consumes low power. In addition, the light emitting device can be manufactured easily in a mass production manner and at low cost. A light emitting device can be provided.

[0168] Up to this point, we have explained about active matrix type light emitting devices. A sub-matrix light-emitting device manufactured by applying the present invention is described below. FIG. 5(A) is a perspective view of the light-emitting device, and FIG. 5B is a cross-sectional view taken along the line XY of FIG. 5A. In FIG. 5, An EL layer 955 is provided between the electrode 952 and the electrode 956. The insulating layer 953 is covered with a partition layer 954. The side walls of the partition layer 954 become thinner as they approach the substrate surface. In other words, the cross section of the partition layer 954 in the short side direction is The trapezoidal shape has a base (which faces in the same direction as the surface direction of the insulating layer 953 and is in contact with the insulating layer 953). The upper side (the side that faces in the same direction as the surface direction of the insulating layer 953 and does not contact the insulating layer 953) In this way, by providing the partition layer 954, the light emitting element caused by static electricity or the like can be prevented from In addition, in a passive matrix light emitting device, the above-mentioned defects can be prevented. The light-emitting element having high emission efficiency described in Embodiment 1 or 2 is used, and power consumption is low. In addition, the light emitting element is a light emitting element that can be easily mass-produced. This makes it possible to provide an inexpensive light emitting device.

[0169] The light emitting device described above has a large number of minute light emitting elements arranged in a matrix. Since the light can be controlled by the light source, the light can be suitably used as a display device for displaying images. It is an optical device.

[0170] This embodiment mode can be freely combined with other embodiment modes.

[0171] (Embodiment 4) In this embodiment, the light-emitting element described in Embodiment 1 or 2 is used as a lighting device. An example of use will be described with reference to FIG. 6. FIG. 6(B) is a top view of the lighting device, and FIG. FIG. 6B is a cross-sectional view taken along line ef in FIG.

[0172] The lighting device in this embodiment is a first substrate 400 on a light-transmitting substrate 400 serving as a support. The first electrode 401 is the same as the first electrode 1 in the first embodiment. In the case where light is extracted from the first electrode 401 side, the first electrode 401 is a light-transmitting It is formed from a material having such properties.

[0173] A pad 412 for supplying a voltage to the second electrode 404 is formed on the substrate 400 .

[0174] An EL layer 403 is formed on the first electrode 401. The EL layer 403 is the same as that of the first embodiment. The configuration of the EL layer 103, or the light-emitting units 511, 512 and the charge generating layer 513 in For details of these configurations, please refer to the relevant descriptions.

[0175] The second electrode 404 is formed to cover the EL layer 403. In the case where light is extracted from the first electrode 401 side, The second electrode 404 is formed of a highly reflective material. 2 provides voltage.

[0176] As described above, a light-emitting element having the first electrode 401, the EL layer 403, and the second electrode 404 is The lighting device described in the embodiment has a light-emitting element having high light-emitting efficiency. Therefore, the lighting device in this embodiment can be a lighting device with low power consumption.

[0177] The light emitting element having the above structure is fixed to a sealing substrate 407 using sealing materials 405 and 406. The lighting device is completed by attaching and sealing the sealing materials 405 and 406. Also, the inner sealant 406 (not shown in FIG. 6B) may contain a desiccant. It is also possible to mix it with other materials, which can absorb moisture and improve reliability. .

[0178] In addition, the pad 412 and a part of the first electrode 401 are extended outside the sealing materials 405 and 406. By providing a 1 / 4" connector on the 1 / 4" input, it can be used as an external input terminal. An IC chip 420 incorporating the above may be provided.

[0179] As described above, the lighting device according to the present embodiment has an EL element according to the first or second embodiment. Since the light-emitting element described above is included, a lighting device with low power consumption can be obtained. Therefore, the lighting device can be manufactured with a low driving voltage and at low cost. do.

[0180] (Embodiment 5) In this embodiment, the light-emitting element described in Embodiment 1 or 2 is included in a part of the light-emitting element. Examples of electronic devices will be described. The light-emitting element described in Embodiment 1 or 2 is 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 the first or second embodiment is a light-emitting element having a small number of film layers. Therefore, it is possible to produce an inexpensive electronic device.

[0181] 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.

[0182] FIG. 7A 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 Embodiment 1 or 2 as a matrix. The elements are arranged in a square shape.

[0183] 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.

[0184] 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.

[0185] FIG. 7(B1) shows a computer, which includes a main body 7201, a housing 7202, a display unit 7203, and a keyboard. keyboard 7204, external connection port 7205, pointing device 7206, etc. This computer is capable of generating the same data as that described in the first or second embodiment. The display unit 7203 is fabricated by arranging optical elements in a matrix. The computer of FIG. 7(B2) may be in the form of the computer of FIG. 7(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 data is displayed by arranging the light-emitting elements described in embodiment 1 or embodiment 2 in a matrix. It is produced by using it in part 7203.

[0186] FIG. 7C shows a portable game machine that is composed of two housings, a housing 7301 and a housing 7302. The housing 7301 is connected to the connector 7303 so as to be openable and closable. A display unit manufactured by arranging the light-emitting elements described in the first or second embodiment in a matrix. A display unit 7305 is incorporated in the housing 7302. The portable gaming machine shown in FIG. 7(C) also includes a speaker unit 7306 and a recording medium insertion unit 7307. , LED lamp 7308, input means (operation keys 7309, connection terminal 7310, sensor 73 11 (force, displacement, position, velocity, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical Chemical substances, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration , odor or infrared measuring function), microphone 7312) etc. Of course, the configuration of the portable gaming machine is not limited to the above, and at least the display unit 73 04 and / or the display portion 7305 may be 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. 7(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 a variety of functions.

[0187] FIG. 7D shows an example of a mobile phone. The mobile phone is built in a housing 7401. In addition to the display unit 7402, the operation buttons 7403, the external connection port 7404, the speaker 74 05, a microphone 7406, etc. The mobile phone is The display unit 7402 has the light-emitting elements according to the second embodiment arranged in a matrix. do.

[0188] The mobile phone shown in FIG. 7D is a mobile phone that allows users to input information 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.

[0189] 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.

[0190] 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.

[0191] 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.

[0192] 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.

[0193] 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.

[0194] 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.

[0195] Note that the configuration shown in this embodiment mode is a combination of the configurations shown in Embodiment Modes 1 to 4. They can be used in combination.

[0196] As described above, the scope of application of the light emitting device including the light emitting element according to the first or second embodiment is as follows: The range of applications is extremely wide, and this light emitting device can be applied to electronic devices in all fields. By using the light-emitting element described in Embodiment 1 or 2, power consumption can be reduced. The electronic device can be obtained.

[0197] FIG. 8 is a liquid crystal display in which the light emitting element according to the first or second embodiment is applied to a backlight. The liquid crystal display device shown in FIG. 8 includes a housing 901, a liquid crystal layer 902, The liquid crystal layer 902 has a driver IC 905 and In addition, the backlight unit 903 is connected to the backlight unit 902. 2 is used, and a current is supplied through a terminal 906.

[0198] The light-emitting element described in embodiment 1 or embodiment 2 is applied to a backlight of a liquid crystal display device. As a result, a backlight with reduced power consumption can be obtained. By using the light-emitting device described above, it is possible to fabricate a surface-emitting lighting device, and it is also possible to make the device larger in area. This makes it possible to increase the area of ​​the backlight, and therefore the area of ​​the liquid crystal display device. Furthermore, the light emitting device to which the light emitting element described in the second embodiment is applied is thinner than the conventional one. Since the size can be reduced, the display device can be made thinner.

[0199] FIG. 9 shows a configuration in which the light-emitting element according to the first or second embodiment is mounted on an electric star which is a lighting device. The desk lamp shown in FIG. 9 has a housing 2001 and a light source 2002. As light source 2002, the lighting device described in the fourth embodiment is used.

[0200] FIG. 10 shows an indoor lighting device 300 in which the light-emitting element described in embodiment 1 or embodiment 2 is used. The light-emitting element described in the embodiment 1 or 2 has a low power consumption. Since the light-emitting element has a reduced power consumption, a lighting device with reduced power consumption can be provided. In addition, since the light-emitting element described in embodiment 1 or embodiment 2 can be made large in area, In addition, the present invention can be used as a lighting device for a variety of lighting applications. The light-emitting element is thin, and therefore can be used as a thin lighting device.

[0201] The light emitting element according to the first or second embodiment is used as a light emitting element for a windshield or a dash board of an automobile. FIG. 11 shows the light-emitting element described in the second embodiment. The display area 5000 is a display area used for a windshield or a dashboard. 5005 is a display provided using the light-emitting element described in Embodiment 1 or 2. do.

[0202] 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 according to the first embodiment or the second embodiment. In the light-emitting element according to the second 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.

[0203] The display region 5002 is a display region according to the first or second embodiment provided in a pillar portion. 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.

[0204] The display area 5004 and the display area 5005 display navigation information, a speedometer, a tachometer, and driving It can provide information such as distance, fuel level, gear status, air conditioning settings, and much more. 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 also be used as lighting devices. do.

[0205] The light-emitting element described in embodiment 1 or embodiment 2 is a light-emitting element with high emission efficiency. In addition, it is possible to provide a light-emitting element with low power consumption. Even if many large screens are provided in the display area 5000 to the display area 5005, the load on the battery is not increased. Since the above-mentioned embodiment is less likely to break and can be used comfortably, it is preferred to use the embodiment 1 or 2. A light-emitting device or a lighting device using the light-emitting element according to the present invention is an in-vehicle light-emitting device or a lighting device. It can be suitably used as such.

[0206] FIG. 12(A) and FIG. 12(B) show an example of a tablet terminal that can be folded in half. 2(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 according to the first embodiment or the second embodiment. By using the light-emitting device as one or both of the display portions 9631a and 9631b, It is produced.

[0207] 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.

[0208] 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.

[0209] In addition, when touching the touch panel area 9632a and the touch panel area 9632b at the same time, You can also input the

[0210] 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.

[0211] FIG. 12A 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.

[0212] FIG. 12B shows the tablet terminal in the closed state. Body 9630, solar cell 9633, charge / discharge control circuit 9634, battery 9635, DCD 12B 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.

[0213] 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.

[0214] In addition, the tablet terminals shown in Figs. 12(A) and 12(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.

[0215] 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.

[0216] The configuration and operation of the charge / discharge control circuit 9634 shown in FIG. A block diagram is shown in FIG. 12(C) and will be explained. FIG. 12(C) shows a solar cell 9633, a battery 9 635, DC-DC converter 9636, converter 9638, switches SW1 to SW3 , a display unit 9631, a battery 9635, a DC-DC converter 963 6. The converter 9638 and the switches SW1 to SW3 are configured to perform the charge / discharge control shown in FIG. 12(B). This corresponds to the circuit 9634 .

[0217] 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.

[0218] 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.

[0219] In addition, if the display unit 9631 is provided, a tablet terminal having the shape shown in FIG. Not limited to. EXAMPLES

[0220] In this example, a light-emitting element (light-emitting element 1) of one embodiment of the present invention will be described. The element 1 has a fluorescent light-emitting layer (first light-emitting layer 113a) and a phosphorescent light-emitting layer (second light-emitting layer 113b). The light-emitting layer 113 is formed in contact with the phosphorescent light-emitting layer (second light-emitting layer 113b). The first phosphorescent light-emitting layer (second light-emitting layer 113b-1) exhibits red phosphorescence, and the second phosphorescent light-emitting layer (second light-emitting layer 113b-2) exhibits green phosphorescence. The second phosphorescent light-emitting layer (second light-emitting layer 113b-2) is laminated to the first phosphorescent light-emitting layer 113b-1. The structural formula of the organic compound used in the light-emitting element 1 is shown below.

[0221] [ka]

[0222] A method for fabricating the light-emitting device 1 of this example will be described below.

[0223] (Method of manufacturing light-emitting element 1) First, indium tin oxide containing silicon oxide (ITSO) was sputtered onto a glass substrate. The first electrode 101 was formed by a deposition method. The area was set to 2 mm×2 mm. Here, the first electrode 101 functions as an anode of the light-emitting element. It is an electrode that

[0224] 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.

[0225] 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.

[0226] 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.

[0227] Next, on the hole injection layer 111, 9-phenyl-3-[4 -(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: PCz PA) was deposited to a thickness of 20 nm to form the hole transport layer 112.

[0228] Furthermore, on the hole transport layer 112, a 7-[4-(10-fluoro)- [phenyl-9-anthryl)phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA) and N,N'-bis(3-methylphenyl) n,n'-bis[3-(9-phenyl-9H-fluoren-9-yl)phenyl] -pyrene-1,6-diamine (abbreviation: 1,6mMemFLPAPrn) in a weight ratio of 1: 0.04 (=cgDBCzPA:1,6mMemFLPAPrn) A fluorescent light-emitting layer (first light-emitting layer 113a) was formed by co-evaporation. Represented by 2-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]dibenzothiophene Benzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II) and the above structural formula (v i) N-(1,1'-biphenyl-4-yl)-N-[4-(9-phenyl- 9H-Carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluorene-2 -amine (abbreviation: PCBBiF) and (dipivaloyl methyl ether) represented by the above structural formula (vii). Thanato)bis(2,3,5-triphenylpyrazinate)iridium(III) (abbreviation: [ Ir(tppr)2(dpm)]) in a weight ratio of 0.6:0.4:0.05 (=2mDB TBPDBq-II:PCBBiF:[Ir(tppr)2(dpm)] A first phosphorescent light-emitting layer (second light-emitting layer 113b-1) is formed by co-evaporation of 5 nm. mDBTBPDBq-II and PCBBiF and the bis[2 -(6-tert-butyl-4-pyrimidinyl-κN3)phenyl-κC](2,4-phenyl ntandionate-κ 2 O,O') Iridium(III) (abbreviation: [Ir(tBuppm) 2(acac)]) in a weight ratio of 0.8:0.2:0.05 = (=2mDBTBPDBq -II: PCBBiF: [Ir(tBuppm)2(acac)]) m co-evaporation to form a second phosphorescent emitting layer (second emitting layer 113b-2). (The second light-emitting layer 113b) was formed.

[0229] In the phosphorescent light-emitting layer (second light-emitting layer 113b), 2mDBTBPDBq-II and PCBBiF form an exciplex. 2mDBTBPDBq-II and PCBBiF The photoluminescence wavelength of the co-evaporated film (i.e., the emission wavelength of the exciplex) is 515 nm. The emission wavelength is around [Ir(tppr)2(dpm)] and [Ir(tB uppm)2(acac)], and the efficiency of energy transfer is It is a highly structured product.

[0230] Furthermore, the singlet excitation energy of cgDBCzPA, the host material of the fluorescent emitting layer, is This is larger than the singlet excitation energy of the fluorescent substance 1,6mMemFLPAPrn. , and the triplet excitation energy of cgDBCzPA is 1,6mMemFLPAPrn. The triplet excitation energy is smaller than that of the fluorescent light-emitting layer (first light-emitting layer 113). a) The regeneration and emission of singlet excitons accompanying triplet-triplet annihilation are easily obtained. In fact, the generation of delayed fluorescence was confirmed in this configuration.

[0231] Then, 2mDBTBPDBq-II was deposited on the phosphorescent light-emitting layer (second light-emitting layer 113b) to a thickness of The film was then formed to a thickness of 10 nm, and the bathophenanthroline represented by the above structural formula (ix) was then added. Phosphorus (abbreviation: BPhen) is deposited to a thickness of 15 nm to form the electron transport layer 114. Ta.

[0232] After the electron transport layer 114 is formed, lithium fluoride (LiF) is then deposited to a thickness of 1 nm. Then, a second electrode 112 is deposited on the second electrode 113 so as to function as a cathode. 02, aluminum was evaporated to a film thickness of 200 nm, A light-emitting element 1 was produced.

[0233] In the above-mentioned deposition process, the deposition was all performed by a resistance heating method.

[0234] 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 (sealing material is applied around the element, UV treatment is performed during sealing, and the temperature is kept at 80℃ After heat treatment at 25°C for 1 hour, the reliability was measured. The experiment was carried out in an atmosphere maintained at 0.4 °C.

[0235] FIG. 13 shows the current density-luminance characteristics of the light-emitting element 1, FIG. 14 shows the luminance-current efficiency characteristics, and FIG. The luminance characteristics are shown in Fig. 15, the luminance-external quantum efficiency characteristics in Fig. 16, and the emission spectrum in Fig. 17. .

[0236] As described above, the light-emitting element 1 has a light emission rate of 1000 cd / m despite having a structure without an intermediate layer. 2 Attached It was found that the device exhibited good luminous efficiency with a current efficiency of about 30 cd / A and an external quantum efficiency of about 13%. In addition, the driving voltage is low at the 3V level.

[0237] In addition, the emission spectrum shows red emission from [Ir(tppr)2(dpm)] and [ Green emission from 1,6mMemFLPAPr From this, it was confirmed that the fluorescent light-emitting layer (first light-emitting layer 113a) and Sufficient light emission is obtained from both the phosphorescent light-emitting layer (the second light-emitting layer 113b) and the In addition, the luminance of light-emitting element 1 is 1000 cd / m 2 The correlated color temperature in the vicinity is 3130K. The average color rendering index is 92, which is sufficient for lighting purposes, and the color temperature is also very good. It was also found that the element has color rendering properties.

[0238] Next, the initial brightness was set to 5000cd / m 2 The light-emitting element 1 is driven under a constant current density condition. The results of the reliability test are shown in Figure 18. The results show that the light-emitting element 1 maintained the initial luminance even after 62 hours. The luminance of the light-emitting element is 94% of the original value, and the decrease in luminance over time is small. It turned out to be a child.

[0239] Here, the single layer of cgDBCzPA and 1,6mMemFLPArn used in the light-emitting element 1 The first excitation level (S1 level) is 2.95 eV and 2.68 eV from the absorption edge of the evaporated film, respectively. It was estimated at eV.

[0240] In this embodiment, 2mDBTBPDBq-II and PCBB The triplet levels of iF, cgDBCzPA, and 1,6mMemFLPAPrn (T1 levels The results of the measurements of the T1 levels are shown in Table 1. The T1 levels were measured by measuring the phosphorescence of each substance. The measurement conditions were as follows: each substance was irradiated with 325 nm excitation light, and the measurement temperature was The measurements were performed at a temperature of 10K. The energy level is better calculated from the absorption wavelength than from the emission wavelength. Although the accuracy is high, the absorption at the T1 level is extremely weak and difficult to measure, so The phosphorescence emission peak wavelength located on the shortest wavelength side was set as the T1 level. Therefore, the measured value There may be some errors in the above. For Prn, intersystem crossing is unlikely to occur, so tris(2-phenylpyridinato)yl By adding (co-evaporating) Ir(ppy)3 as a sensitizer, phosphorescence is generated. Observed the light.

[0241] [Table 1]

[0242] From the above results, in the fluorescent-emitting layer of the light-emitting element 1, the host material cgDBCzPA The singlet excited state of the fluorescent substance 1,6mMemFLPAPrn is The triplet excited level of cgDBCzPA is larger than that of 1,6mMemFLPA. The triplet excitation level of Prn is smaller than that of the fluorescent light-emitting layer (first light-emitting layer 11). 3a) shows the regeneration of singlet excitons and emission following triplet-triplet annihilation. It is clear that it is a simple configuration.

[0243] In addition, the triplet excitation level of cgDBCzPA, the host material of the fluorescent layer, is phosphorescent. The first organic compound (2mDBTBPDBq-II) and the second organic compound ( It can be seen that the triplet excitation level of this structure is smaller than that of PCBBiF. In this case, it is common sense that most of the triplet excitons generated in the phosphorescent layer diffuse into the fluorescent layer. However, in the light-emitting element 1 of this embodiment, the first The organic compound and the second organic compound form an exciplex, so that the phosphorescent light is generated inside the phosphorescent layer. The triplet excitons are difficult to diffuse into the fluorescent layer. One of the reasons for this is thought to be that energy transfer from one exciplex to another is difficult. As a result, the light-emitting element 1 can achieve high light emission while obtaining light from both the fluorescent and phosphorescent light-emitting layers. The result is a characteristic that defies conventional wisdom, achieving extremely high efficiency.

[0244] As described above, the light-emitting element 1 according to one embodiment of the present invention has very well-balanced and excellent characteristics. It can be seen that the light-emitting device has the above-mentioned properties and can be easily and inexpensively manufactured. By using exciplexes as energy donors in the phosphorescent layer, The diffusion of the triplet excitation energy is suppressed, and the non-radiative deactivation of the triplet excitation energy is reduced. Emission due to delayed fluorescence accompanying triplet-triplet annihilation in silicon materials This is due to improved efficiency. EXAMPLES

[0245] Example 1 In this example, a manufacturing method of light-emitting element 2 and light-emitting element 3, which are light-emitting elements of one embodiment of the present invention, and The structural formulas of the organic compounds used in the light-emitting elements 2 and 3 are shown below. vinegar.

[0246] [ka]

[0247] (Method of manufacturing light-emitting element 2) Indium tin oxide containing silicon oxide (ITSO) is deposited on a glass substrate by sputtering. The first electrode 101 was formed to a thickness of 110 nm. The value was m.

[0248] 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.

[0249] 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.

[0250] 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 30 nm. The weight ratio of DBT3P-II to molybdenum oxide was adjusted to 2:1 (=DBT3P-II:molybdenum oxide). did.

[0251] Next, on the hole injection layer 111, 9-phenyl-3-[ 4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: PC A film of zPA) was formed to a thickness of 20 nm to form the hole transport layer 112.

[0252] Furthermore, on the hole transport layer 112, a 7-[4-(10-fluoro)- [phenyl-9-anthryl)phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA) and N,N'-bis(3-methylphenyl) n,n'-bis[3-(9-phenyl-9H-fluoren-9-yl)phenyl] -pyrene-1,6-diamine (abbreviation: 1,6mMemFLPAPrn) in a weight ratio of 1: 10 nm so that the value becomes 0.02 (=cgDBCzPA:1,6mMemFLPAPrn) The first light-emitting layer 113a, which is a fluorescent light-emitting layer, was formed by co-evaporation. ) represented by 2-[3'-(dibenzothiophene-4-yl)biphenyl-3-yl]diphenyl Benzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II) and the above structural formula ( vi) N-(1,1'-biphenyl-4-yl)-N-[4-(9-phenyl -9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluorene- 2-amine (abbreviation: PCBBiF), bis{4,6-dimethyl 2-[5-(2,6-dimethylphenyl)-3-(3,5-dimethylphenyl)-2 -pyrazinyl-κN]phenyl-κC}(2,4-pentanedionato-κ 2 O,O')I Ir(dmdppr-dmp)2(acac)] Weight ratio 0.5:0.5:0.05(=2mDBTBPDBq-II:PCBBiF:[I r(dmdppr-dmp)2(acac)]) was co-evaporated to form the first adhesive layer of 5 nm. A phosphorescent light-emitting layer (second light-emitting layer 113b-1) was then formed, followed by 2mDBTBPDBq-II and PCBBiF and bis[2-(6-tert-butyl -4-pyrimidinyl-κN3)phenyl-κC](2,4-pentanedionato-κ 2 O, O') iridium(III) (abbreviation: [Ir(tBuppm)2(acac)]) Weight ratio 0.8:0.2:0.05=(=2mDBTBPDBq-II:PCBBiF:[ Ir(tBuppm)2(acac)]) was co-evaporated to 20 nm, and the second phosphorescent The light-emitting layer (second light-emitting layer 113b-2) is formed to form the second light-emitting layer 113 b was formed.

[0253] In the phosphorescent layer 113b, 2mDBTBPDBq-II and PCBBiF The exciplex is formed. The emission wavelength is [Ir(dmdppr-dmp)2(a cac)] and [Ir(tBuppm)2(acac)]. This structure allows for highly efficient energy transfer.

[0254] Furthermore, the host material of the fluorescent-emitting layer (first light-emitting layer 113a) is cgDBCzPA. The singlet excitation energy is the singlet excitation energy of the fluorescent substance 1,6mMemFLPAPrn. The triplet excitation energy of cgDBCzPA is 1,6 The triplet excitation energy of mMemFLPAPrn is smaller than that of The light emitting layer (first light emitting layer 113a) is a layer that emits singlet excitons associated with triplet-triplet annihilation. This configuration makes it easy to regenerate and emit light.

[0255] Thereafter, 2mDBTBPDBq-II was formed as a film on the second light-emitting layer 113b, which is a phosphorescent light-emitting layer. The film was formed to a thickness of 10 nm, and further, the bathophenanthrene represented by the above structural formula (ix) was added. A film of BPhen (abbreviation: BPhen) is formed to a thickness of 15 nm to form the electron transport layer 114. did.

[0256] After the electron transport layer 114 is formed, lithium fluoride (LiF) is then deposited to a thickness of 1 nm. Then, a second electrode 112 is deposited on the second electrode 113 so as to function as a cathode. 02, aluminum was evaporated to a film thickness of 200 nm, A light-emitting element 2 was fabricated.

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

[0258] (Method of Manufacturing Light-Emitting Element 3) The light-emitting element 3 has the first phosphorescent light-emitting layer (second light-emitting layer 113b-1) in the light-emitting element 2. The ratio of the constituent substances is 2mDBTBPDBq-II:PCBBiF:[Ir(dmdpp r-dmp)2(acac)] = 0.2:0.8:0.05 (weight ratio), and the second phosphorus The ratio of the material constituting the light-emitting layer (second light-emitting layer 113b-2) is 2mDBTBPDBq- II:PCBBiF:[Ir(tBuppm)2(acac)]=0.9:0.1:0. The light-emitting element was fabricated in the same manner as in the light-emitting element 2, except that the weight ratio was changed to 0.5.

[0259] The light emitting element 2 and the light emitting element 3 are placed in a glove box with a nitrogen atmosphere, and the light emitting element is The process of sealing the element with a glass substrate to prevent it from being exposed to air (applying a sealant around the element, After performing UV treatment during sealing and heat treatment at 80°C for 1 hour, the characteristics of these light-emitting devices were The measurements were performed at room temperature (atmosphere maintained at 25°C) using an integrating sphere. The current density was 2.5mA / cm 3 The characteristic values ​​of the above are summarized in a table.

[0260] [Table 2]

[0261] Although neither the light-emitting element 2 nor the light-emitting element 3 is provided with a special light extraction structure, the light-emitting element 2 and the light-emitting element 3 are excellent. The device showed excellent external quantum efficiency and power efficiency. The voltage was also 3 V, which is comparable to that of a tandem-type light-emitting device. It is a comparatively low value.

[0262] The emission spectra of the light-emitting element 2 and the light-emitting element 3 are shown in FIG. 19(A) and (B), respectively. The emission spectrum shows that the red ions originating from [Ir(dmdppr-dmp)2(acac)] Color emission, green emission from [Ir(tBuppm)2(acac)] and 1,6mMem Blue light emission from FLPAPrn was observed in all the fluorescent layers. Both the first light-emitting layer 113a and the second light-emitting layer 113b, which is a phosphorescent light-emitting layer, emit sufficient light. It can be seen that light emission is obtained at

[0263] Furthermore, these light-emitting elements have good color rendering properties, with an average color rendering index Ra of 85 or higher. The v is also small, making it suitable for lighting applications. The color temperatures are 4710K daylight white and 295 It exhibits a 0K incandescent light color and characteristics that conform to the standards.

[0264] The difference between the light-emitting element 2 and the light-emitting element 3 is the material constituting the second light-emitting layer 113b. In other words, the mixing ratio of the constituent substances can be adjusted to 2950 by a simple operation. This example also shows that white light can be emitted over a wide color temperature range from 100K to 4710K. Depending on the adjustment, the color temperature can be adjusted to 2950K or lower or 4710K or higher. It is also significant that this can be achieved without any significant loss of efficiency. In this embodiment, a light-emitting element was fabricated that emits three colors of blue, green, and red light, so that white light was emitted. However, when a light-emitting device is manufactured with another emission color, By adjusting the mixing ratio of the materials, the ratio of the mixed colors of the emitted light can be controlled, and the desired emitted color can be easily obtained. It is possible to provide a light emitting device that can achieve the above.

[0265] In this way, the light-emitting element 2 and the light-emitting element 3 have very well-balanced and excellent characteristics. This result shows that the phosphorescent light-emitting device can be easily and inexpensively fabricated. By using exciplexes as energy donors in the light-emitting layer, exciton diffusion is improved. The host material of the fluorescent-emitting layer is suppressed and non-radiative deactivation of triplet excitation energy is reduced. Improvement of emission efficiency by generation of delayed fluorescence accompanying triplet-triplet annihilation in The top is contributing. EXAMPLES

[0266] In this example, a manufacturing method and characteristics of a light-emitting element 4, which is one embodiment of the present invention, will be described. In the light-emitting element 4, the first light-emitting layer 113a is disposed on the cathode side, and the second light-emitting layer 113b is disposed on the anode side. The structural formula of the organic compound used in the light-emitting element 4 is shown below.

[0267] [ka]

[0268] (Method of manufacturing light-emitting element 4) Indium tin oxide containing silicon oxide (ITSO) is deposited on a glass substrate by sputtering. The first electrode 101 was formed to a thickness of 110 nm. The value was m.

[0269] 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.

[0270] 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.

[0271] 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). did.

[0272] Next, N-(1,1'-biphenyl) represented by the above structural formula (vi) is deposited on the hole injection layer 111. phenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl 2,9-Dimethyl-9H-fluoren-2-amine (abbreviation: PCBBiF) The hole transport layer 112 was formed to a thickness of 0 nm.

[0273] Furthermore, on the hole transport layer 112, 2-[3′-(dibenzothiophene) [4-phenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II) and PCBBiF, represented by the above structural formula (vii) (di (pivaloylmethanato)bis(2,3,5-triphenylpyrazinato)iridium(III) ) (abbreviation: [Ir(tppr)2(dpm)] in a weight ratio of 0.2:0.8:0.05 ( =2mDBTBPDBq-II:PCBBiF:[Ir(tppr)2(dpm)]) The first phosphorescent light-emitting layer (second light-emitting layer 113b-1) was formed by co-evaporation of 20 nm. Then, 2mDBTBPDBq-II and PCBBiF and the above structural formula (viii) were Bis[2-(6-tert-butyl-4-pyrimidinyl-κN3)phenyl-κC] (2,4-pentanedionato-κ 2 O,O') Iridium(III) (abbreviation: [Ir(t Buppm)2(acac)]) in a weight ratio of 0.3:0.7:0.05 (=2mDBT BPDBq-II:PCBBiF:[Ir(tBuppm)2(acac)]) A second phosphorescent-emitting layer (second light-emitting layer 113b-2) was formed by co-evaporation of 5 nm on the The second light-emitting layer 113b, which is a light-emitting layer, was then formed. 7-[4-(10-phenyl-9-anthryl)phenyl]-7H-dibenzo[c, g]carbazole (abbreviation: cgDBCzPA) and N,N '-Bis(3-methylphenyl)-N,N'-bis[3-(9-phenyl-9H-fluoro 1,6mMemFLP APrn) in a weight ratio of 1:0.04 (=cgDBCzPA:1,6mMemFLPAP rn), a first light-emitting layer 113a, which is a fluorescent light-emitting layer, is formed by co-evaporation of 25 nm. Then, the light emitting layer 113 was formed.

[0274] In the second light-emitting layer 113b, which is a phosphorescent light-emitting layer, 2mDBTBPDBq-I I and PCBBiF form an exciplex. The emission wavelength is [Ir(tppr)2( dpm)] and [Ir(tBuppm)2(acac)] on the longest wavelength side. This structure allows for highly efficient energy transfer.

[0275] Furthermore, the host material of the fluorescent-emitting layer (first light-emitting layer 113a) is cgDBCzPA. The singlet excitation energy is the singlet excitation energy of the fluorescent substance 1,6mMemFLPAPrn. The triplet excitation energy of cgDBCzPA is 1,6 The triplet excitation energy of mMemFLPAPrn is smaller than that of The light emitting layer (first light emitting layer 113a) is a layer that emits singlet excitons associated with triplet-triplet annihilation. This configuration makes it easy to regenerate and emit light.

[0276] Thereafter, cgDBCzPA was deposited to a thickness of 10 nm on the first light-emitting layer 113a, which was a fluorescent light-emitting layer. Further, bathophenanthroline (abbreviation: A film of 15 nm thick ZnO:BPhen was then formed to form the electron transport layer 114.

[0277] After forming the electron transport layer 114, lithium fluoride (LiF) was deposited to a thickness of 1 nm. Then, an electron injection layer 115 is formed, and finally, a second electrode 102 that functions as a cathode is formed. Then, aluminum was evaporated to a thickness of 200 nm to form the light-emitting element of this embodiment. In the above-mentioned deposition process, the deposition was all performed using a resistance heating method.

[0278] The element structure of the light-emitting element 4 is shown in the table below.

[0279] The light emitting element 4 is placed in a glove box with a nitrogen atmosphere so that the light emitting element 4 is not exposed to the air. The process of sealing the element with a glass substrate to prevent damage to the element (sealing material is applied around the element and UV is applied during sealing). After that, the current density of the light-emitting element 4 was 2.5 mA / cm 2 At 1000cd / cm 2 The characteristics in the vicinity were measured.

[0280] [Table 3]

[0281] The light-emitting element 4 has a good external quantum efficiency even though it does not have a special light extraction structure. The power efficiency was also very high, at 2.7 V, compared to tandem-type light-emitting devices. It is a low value.

[0282] The emission spectrum of the light-emitting element 4 is shown in FIG. red emission from [Ir(tBuppm)2(acac)] and red emission from [Ir(tBuppm)2(acac)] Both green emission from the 1,6mMemFLPAPrn complex and blue emission from 1,6mMemFLPAPrn were observed. For this reason, the first light-emitting layer 113a is a fluorescent light-emitting layer and the second light-emitting layer is a phosphorescent light-emitting layer. It can be seen that sufficient light emission is obtained from both optical layers 113b.

[0283] Furthermore, the light-emitting element 4 has a good color rendering property with an average color rendering index Ra of 84 and a small dub. It is suitable for lighting applications. In addition, the color temperature is 2690K, which is in line with the standard for warm white light. is doing.

[0284] Thus, the light-emitting element 4 has well-balanced and excellent characteristics and can be easily and inexpensively fabricated. This result shows that the light-emitting device can achieve the energy transfer of the phosphorescent layer. By using an exciplex as a donor, exciton diffusion is suppressed and triplet excited energies are generated. The non-radiative deactivation of energy has been reduced, and triplet-triplet coupling in the host material of the fluorescent emitting layer has been improved. This is due to the increased luminescence efficiency caused by the generation of delayed fluorescence accompanying the annihilation of the electrons. It was also found that good characteristics could be obtained even if the lamination order of the light emitting layers 113 was changed. [Explanation of symbols]

[0285] 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 113b Second light-emitting layer 113b-1 Second light-emitting layer 113b-2 Second light-emitting layer 114 Electron transport layer 115 Electron injection layer 400 Substrates 401 First electrode 403 EL layer 404 Second electrode 405 Sealing material 406 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 FET 612 Current Control FET 613 First electrode 614 Insulation 616 EL layer 617 Second Electrode 618 Light-emitting element 623 n-channel FET 624 p-channel FET 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 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 7400 Mobile Phone 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 and a second light-emitting layer are disposed between a first electrode and a second electrode, the first light-emitting layer is provided between the first electrode and the second light-emitting layer, the second light-emitting layer is provided between the first light-emitting layer and the second electrode, the first light-emitting layer comprises a fluorescent material and a host material; the second light-emitting layer includes a substance, a first organic compound, and a second organic compound; the first organic compound and the second organic compound are a combination capable of forming an exciplex, the substance is capable of converting triplet excitation energy into luminescence; a difference between an energy value of a peak wavelength of an emission spectrum of the exciplex and an energy value of a peak wavelength of an absorption band on the lowest energy side of the substance is within 0.2 eV; A light-emitting element in which an emission spectrum from the first light-emitting layer is in a shorter wavelength region than an emission spectrum from the second light-emitting layer.

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