Light-emitting element, light-emitting module, display module, lighting device, light-emitting device, display device, and electronic device

Abstract

To provide a multicolor light-emitting element in a light-emitting element using fluorescent emission and phosphorescent emission, which has comparatively less number of deposition layers thereby to achieve less number of manufacturing processes and is advantageous to practical use, and to provide a multicolor light-emitting element with good light-emitting efficiency in a light-emitting element using fluorescent emission and phosphorescent emission.SOLUTION: There is provided a light-emitting element including a light-emitting layer having a lamination structure of a first light-emitting layer exhibiting light emission from a first excited complex and a second light-emitting layer exhibiting phosphorescent emission.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

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

[0003] These light-emitting elements are self-luminous, so the pixels are more visible than LCD displays. It has the advantage of not requiring a backlight, making it suitable for use as a flat panel display element. Furthermore, displays using such light-emitting elements are thin and lightweight. Another major advantage is that it can be mass-produced. Another feature is its extremely fast response time. is.

[0004] These light-emitting devices can be fabricated with a continuous two-dimensional light-emitting layer, allowing for surface emission. Therefore, a large-area element can be easily formed. This is difficult to achieve with point light sources such as incandescent bulbs and LEDs, or linear light sources such as fluorescent lamps. Because of its unique characteristics, it is highly useful as a surface light source that can be applied to lighting, etc.

[0005] In such an organic EL element, electrons flow from the cathode and holes flow from the anode, respectively. The injected electrons and holes are then recombined to form a current. This causes the light-emitting organic compound to enter an excited state, thereby enabling light emission.

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

[0007] In compounds that emit light from a singlet excited state (hereinafter referred to as fluorescent materials), Usually, light emission from the triplet excited state (phosphorescence) is not observed, but light emission from the singlet excited state (fluorescence) is observed. Therefore, the internal quantum effect in a light-emitting device using a fluorescent material is The theoretical limit of the photon generation rate (the ratio of photons generated to injected carriers) is S * :T * = It is said to be 25% based on the ratio being 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, Light emission from the triplet excited state (phosphorescence) is observed. In addition, phosphorescent compounds exhibit intersystem crossing ( Since the transition from the singlet excited state to the triplet excited state occurs easily, the internal quantum efficiency is 1 In other words, it is possible to achieve a higher luminous efficiency than fluorescent materials. For this reason, in order to realize a highly efficient light-emitting device, a phosphorescent compound is used. 2. Description of the Related Art Light-emitting devices have been actively developed in recent years.

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

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

[0011] As for multicolor light emitting devices, which are typified by white light emitting devices, the light emitted in the short wavelength region is called fluorescent light. a layer that emits light in the long wavelength region as phosphorescence (phosphorescent layer); Some devices have been developed that have an intermediate layer (charge generating layer) between the fluorescent and phosphorescent layers. It has also been put to practical use.

[0012] This structure converts the short wavelength light emitted from the device, which has a limited life span, into fluorescence light, and the long wavelength light into phosphorescence light. Although the efficiency is lower than that of an all-phosphorescent device, this allows for stable multicolor emission. The feature of this method is that it allows optical elements to be obtained.

[0013] Multicolor light-emitting devices with this structure that prioritizes reliability over performance are suitable for practical use. On the other hand, the number of films that need to be formed to obtain one light-emitting element is large, which is a problem for practical use. At the same time, it also has disadvantages.

[0014] In such a device, an intermediate layer is provided between the phosphorescent and fluorescent light-emitting layers, and the device is directly The reason for adopting a structure in which the layers are connected in rows is to prevent quenching of phosphorescence by the fluorescent layer. This is because.

[0015] The fluorescent light-emitting layer usually contains a condensed aromatic ring structure such as anthracene as a host material. These condensed aromatic ring skeletons have triplet levels Therefore, when a fluorescent light-emitting layer and a phosphorescent light-emitting layer are provided in contact with each other, the The triplet excitation energy is transferred to the triplet level of the host material in the fluorescent-emitting layer and is deactivated. On the other hand, if a host material with high triplet excitation energy is used in the fluorescent-emitting layer, This problem can be alleviated, but the singlet excitation energy of the host material is then even larger. The energy transfer from the host material to the fluorescent dopant becomes too large (too large). As a result, the energy transfer becomes insufficient and sufficient luminous efficiency cannot be obtained in the fluorescent-emitting layer. The non-radiative deactivation process of the host material may increase, and the device characteristics (especially the life span) may deteriorate.

[0016] In view of this, in one embodiment of the present invention, in a light-emitting element using fluorescence and phosphorescence, Since the number of elements is relatively small, the number of manufacturing steps is small, and a multicolor light-emitting element advantageous for practical use can be provided. The following are the challenges.

[0017] In another embodiment of the present invention, a light-emitting element using fluorescence and phosphorescence can be favorably It is an object of the present invention to provide a multicolor light-emitting element having high luminous efficiency.

[0018] In another embodiment of the present invention, a light-emitting element using fluorescence and phosphorescence is formed by Multicolor light-emitting device with a relatively small number of layers, advantageous for practical use, and good luminous efficiency The objective is to provide the following.

[0019] Another embodiment of the present invention is a light-emitting device that can be manufactured inexpensively by using the above-described light-emitting element. The present invention aims to provide a device, a display device, an electronic device, and a lighting device.

[0020] Another embodiment of the present invention is a light-emitting device with reduced power consumption by using the above-described light-emitting element. The present invention aims to provide an optical device, a display device, an electronic device, and a lighting device.

[0021] The present invention is intended to solve any one of the above problems. [Means for solving the problem]

[0022] a first light-emitting layer that emits light from a first exciplex and a second light-emitting layer that emits phosphorescence; The above object can be achieved by a light emitting device including a light emitting layer having the above laminated structure. Furthermore, the light emitted from the first light-emitting layer has a shorter wavelength than the light emitted from the second light-emitting layer. It is preferable that the emission peak is on the side of the luminescence peak.

[0023] An exciplex is an excited state consisting of two substances. In the case of photoexcitation, the excited formed when one molecule in the ground state incorporates another molecule in the ground state Therefore, when it returns to its ground state by emitting light, it behaves like the original substance again. Therefore, there is no ground state for exciplexes, and energy transfer between exciplexes is possible in principle. This means that the energy transfer through the host material that occupies the majority of the light-emitting layer cannot occur. The light-emitting element having this structure has a first exciton complex in the first light-emitting layer. This makes it easy to achieve both the fluorescent emission of the main body and the phosphorescence of the phosphorescent compound in the second light-emitting layer.

[0024] In addition, phosphorescent materials that emit high-energy, short-wavelength light are particularly unstable. and luminescent elements using phosphorescent materials that emit light at short wavelengths (e.g., blue phosphorescent materials). Therefore, by using fluorescent light for short wavelengths, It is possible to provide a light-emitting device with little deterioration in luminance. The first light-emitting layer, which is a phosphorescent light-emitting layer, and the second light-emitting layer, which is a phosphorescent light-emitting layer, are stacked in contact with each other. The number of layers required to form the layers is small, which is advantageous in terms of cost and is suitable for mass production. Even if the fluorescent-emitting layer and the phosphorescent-emitting layer are in contact with each other, the exciplex is used as described above. Therefore, the triplet excited level is less likely to be deactivated, and it is possible to achieve both phosphorescence and fluorescence emission. be.

[0025] That is, one aspect of the present invention is a first electrode, a second electrode, and a second electrode. In a light-emitting device having an EL layer sandwiched between two electrodes, the EL layer comprises at least a first The first light-emitting layer and the second light-emitting layer are laminated together, and the first light-emitting layer is The second light-emitting layer also comprises a first organic compound and a second organic compound, and the second light-emitting layer comprises at least a third organic compound and a phosphorescent material, The compound is a light-emitting element that is a combination that forms a first exciplex.

[0026] Another aspect of the present invention is a light-emitting element having the above-described structure, wherein the first exciplex The light-emitting element has an emission peak on the shorter wavelength side than the emission of the phosphorescent compound. do.

[0027] In addition, the exciplex is in a state where the singlet excited level and the triplet excited level are close to each other. Therefore, the exciplex is prone to reverse intersystem crossing from the triplet excited level to the singlet excited level. When the exciplex capable of producing delayed fluorescence is applied to the first light-emitting layer, the delayed fluorescence is easily emitted. By using this method, the triplet excited state can also be converted into luminescence, which is To obtain a light-emitting element having a higher luminous efficiency than when a light-emitting material is used In order to efficiently demonstrate reverse intersystem crossing from the triplet excited level to the singlet excited level, It is advantageous that the energy difference between the first excited state and the singlet excited state is small, and The difference is preferably 0 eV or more and 0.2 eV or less, more preferably 0 eV or more and 0.1 eV or less. It's nice.

[0028] That is, another embodiment of the present invention is a light-emitting element having the above structure, The light-emitting element efficiently exhibits reverse intersystem crossing from the triplet excited level to the singlet excited level.

[0029] Another embodiment of the present invention is a light-emitting element having the above structure, wherein the first exciplex is The light-emitting element exhibits delayed fluorescence.

[0030] In addition, in the second light-emitting layer, energy transfer from the host to the phosphorescent compound is efficient. It is preferable that this be done quickly.

[0031] That is, another embodiment of the present invention is a light-emitting layer having the above-described structure, wherein the second light-emitting layer further comprises a fourth organic a compound, and the fourth organic compound and the third organic compound form a second exciplex. The phosphorescent material is a light-emitting element that forms the lowest energy It is more preferable that the absorption band of the second exciplex overlaps with the emission spectrum of the second exciplex.

[0032] Another embodiment of the present invention is a method for manufacturing a phosphorescent material having the above structure, wherein the phosphorescent material has the lowest energy The energy equivalent of the peak wavelength of the absorption band on the side of the The difference between the energy equivalent value of the wavelength of the light emitted from the light emitting element and the energy equivalent value of the wavelength of the light emitting element is 0.2 eV or less.

[0033] In addition, a combination of a first organic compound and a second organic compound and a combination of a third organic compound and a fourth organic compound The combination of organic compounds is sufficient if they can form an exciplex, but one of them is an electron transport It is preferable that one of the first and second layers is a material having hole transport properties and the other is a material having hole transport properties. By having the above structure, it becomes possible to efficiently form an exciplex. By changing the mixing ratio, it is possible to adjust the transport properties of the light-emitting layer itself, As a result, the recombination region can be controlled easily. This can avoid the above problem, which leads to a longer life of the element.

[0034] That is, another aspect of the present invention is a light-emitting device having the above-described structure, wherein the first organic compound One of the compound and the second organic compound is a material having an electron transporting property, and the other is a material having a hole transporting property. a material having transport properties, and one of the third organic compound and the fourth organic compound a light-emitting element in which one of the materials has an electron transporting property and the other has a hole transporting property. .

[0035] As described above, in the light-emitting element of one embodiment of the present invention, each light-emitting layer is made of a material having a hole-transporting property and a material having an electron-transporting property. The recombination region in the light-emitting layer is preferably made of a material having a light-transmitting property. It is preferable that the light emitting layer is located near the interface between the first light emitting layer and the second light emitting layer. In the optical element, the light-emitting layer closer to the anode contains a larger amount of material having hole transport properties, It is preferable that the light-emitting layer closer to the cathode contains a larger amount of a material having electron transport properties. By having this structure, the recombination region is located near the interface between the first light-emitting layer and the second light-emitting layer. This is advantageous for the distribution of recombination energy.

[0036] Furthermore, the first and second exciplexes may be the same exciplex. Another aspect of the present invention is a method for producing a photosensitive material comprising the steps of: The light-emitting element has the same combination of the third organic compound and the fourth organic compound.

[0037] That is, a phosphorescent material is doped into a part of a layer consisting of two kinds of materials that form an exciplex. By this method, a light-emitting device that emits light in multiple colors can be easily obtained. The first light-emitting layer and the second light-emitting layer are made of a material having hole transport properties and a material having electron transport properties. The ratio may be changed.

[0038] The light-emitting element having this structure emits light from the first exciplex and light from the phosphorescent material. Since the emission spectrum is a composite of the two maxima, the emission spectrum has at least two maxima. It has a light spectrum.

[0039] Here, the first light-emitting layer may further contain a fluorescent material as a dopant. As mentioned above, the exciplex formed in the first light-emitting layer has a singlet excited level and a triplet excited level. Because they are in close proximity, reverse intersystem crossing occurs from the triplet excited level to the singlet excited level. In other words, part of the triplet excited state can be converted to the singlet excited state, The proportion of singlet excited states will be higher than the conventional rate (25%). By transferring the energy of the singlet excited state with increased coupling to a fluorescent material, This allows for a higher luminous efficiency to be obtained than with a light-emitting element using a fluorescent material. The advantage is that a fluorescent substance with a high fluorescence quantum yield can be used as a dopant. In this way, the function of generating a singlet excited state from a triplet excited state (exciplex) and the function of generating a singlet excited state from a triplet excited state (exciplex) are The function of efficiently obtaining light emission from the doublet excited state (fluorescent material as a dopant) is By using a material that has a high luminous efficiency, it is easy to obtain high luminous efficiency. Since it exists as a cation, quenching and chemical reactions caused by impurities can be suppressed, resulting in a longer lifespan. It also leads to.

[0040] Furthermore, light emitting elements having these configurations can be selected to emit light of colors that are complementary to each other. can provide white light emission.

[0041] Another aspect of the present invention is a light-emitting element having the above-described structure and a means for controlling the light-emitting element. The light emitting module is provided with:

[0042] In addition, another aspect of the present invention is a display device having a light-emitting element having the above-described structure in a display portion, A display module with a means for controlling the display.

[0043] Another aspect of the present invention is a lighting device having a light-emitting element having the above-described structure.

[0044] Another aspect of the present invention is a light-emitting element having the above-described structure and a means for controlling the light-emitting element. The light emitting device is provided with:

[0045] In addition, another aspect of the present invention is a display device having a light-emitting element having the above-described structure in a display portion, The display device is provided with a control means.

[0046] Another aspect of the present invention is an electronic device having a light-emitting element having the above-described structure.

[0047] In this specification, the term "light-emitting device" includes an image display device using a light-emitting element. In addition, a connector, such as an anisotropic conductive film or TCP (Tape Carrier), is attached to the light emitting element. The module has a printed wiring board at the end of the TCP. The COG (Chip On Glass) method is used for the module or light emitting element. Modules on which ICs (integrated circuits) are directly mounted are also included in the category of light-emitting devices. This also includes light-emitting devices used in lighting fixtures, etc. [Effects of the Invention]

[0048] In one embodiment of the present invention, the number of film layers formed is compared between a light-emitting element using fluorescence and a light-emitting element using phosphorescence. Therefore, it is possible to provide a multicolor light emitting device that is advantageous for practical use.

[0049] In another embodiment of the present invention, a light-emitting element using fluorescence and phosphorescence can be favorably Therefore, a multicolor light-emitting device having high luminous efficiency can be provided.

[0050] In another embodiment of the present invention, a film layer is formed in a light-emitting element using fluorescent light and phosphorescent light. The number of multicolor light-emitting devices is relatively small, which is advantageous for practical use, and which have good luminous efficiency. can be provided.

[0051] Another embodiment of the present invention is a light-emitting element that can be manufactured at low cost by using the light-emitting element. Light devices, display devices, electronic devices, and lighting devices can each be provided.

[0052] Another embodiment of the present invention is a light-emitting element that can reduce power consumption by using the light-emitting element. It is possible to provide a light-emitting device, a display device, an electronic device, and a lighting device. [Brief explanation of the drawings]

[0053] [Figure 1] 1 is a conceptual diagram of a light-emitting element. [Figure 2] 1 is a conceptual diagram of an active matrix light-emitting device. [Figure 3] 1 is a conceptual diagram of an active matrix light-emitting device. [Figure 4] 1 is a conceptual diagram of an active matrix light-emitting device. [Figure 5] FIG. 1 is a conceptual diagram of a passive matrix light-emitting device. [Figure 6] FIG. [Figure 7] 1 is a diagram showing an electronic device. [Figure 8] FIG. [Figure 9] FIG. [Figure 10] FIG. [Figure 11] FIG. 2 is a diagram illustrating an in-vehicle display device and an illumination device. [Figure 12] 1 is a diagram showing an electronic device. [Figure 13] FIG. 10 is a graph showing current density-luminance characteristics of Light-emitting Element 1. [Figure 14] FIG. 10 shows luminance vs. current efficiency characteristics of Light-Emitting Element 1. [Figure 15] FIG. 10 shows voltage-luminance characteristics of the light-emitting element 1. [Figure 16] FIG. 10 is a graph showing luminance vs. external quantum efficiency characteristics of the light-emitting element 1. [Figure 17] Emission spectrum of light-emitting element 1. [Figure 18] FIG. 10 is a graph showing current density-luminance characteristics of Light-emitting element 2. [Figure 19]FIG. 10 shows luminance-current efficiency characteristics of Light-emitting Element 2. [Figure 20] FIG. 10 shows voltage-luminance characteristics of the light-emitting element 2. [Figure 21] FIG. 10 is a graph showing luminance vs. external quantum efficiency characteristics of Light-emitting Element 2. [Figure 22] Emission spectrum of light-emitting element 2. [Figure 23] FIG. 10 is a graph showing current density-luminance characteristics of Light-emitting element 3. [Figure 24] FIG. 10 shows luminance vs. current efficiency characteristics of Light-emitting Element 3. [Figure 25] FIG. 10 shows voltage-luminance characteristics of the light-emitting element 3. [Figure 26] FIG. 10 is a graph showing luminance vs. external quantum efficiency characteristics of the light-emitting element 3. [Figure 27] Emission spectrum of light-emitting element 3. [Figure 28] FIG. 10 is a graph showing current density-luminance characteristics of Light-emitting element 4. [Figure 29] FIG. 10 shows luminance vs. current efficiency characteristics of Light-emitting Element 4. [Figure 30] FIG. 10 shows voltage-luminance characteristics of the light-emitting element 4. [Figure 31] 10 is a graph showing luminance vs. external quantum efficiency of the light-emitting element 4. FIG. [Figure 32] Emission spectrum of light-emitting element 4. [Figure 33] FIG. 10 is a graph showing the change over time in normalized luminance of the light-emitting element 4. [Figure 34] Emission spectra of single and co-evaporated films of 2mDBTBPDBq-II and PCBNBB. DETAILED DESCRIPTION OF THE INVENTION

[0054] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the above description, and the form and details thereof may be changed without departing from the spirit and scope of the present invention. It will be readily apparent to those skilled in the art that various modifications may be made to the present invention. It should not be construed as being limited to the description of the embodiments.

[0055] (Embodiment 1) A schematic diagram of a light-emitting element of one embodiment of the present invention is shown in FIG. The EL layer 101 also includes a pair of electrodes (first electrode 101 and second electrode 102) and a light-emitting layer 113. The light-emitting layer 113 has a first light-emitting layer 113a and a second light-emitting layer 113b. The layers are stacked in layers.

[0056] In FIG. 1(A), the EL layer 103 further includes a hole injection layer 111 and a hole transport layer 112. 12, an electron transport layer 114 and an electron injection layer 115 are shown, but this stacked 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.

[0057] The first light-emitting layer 113a contains a first organic compound and a second organic compound. The second light-emitting layer 113b contains a third organic compound and a phosphorescent compound. The light-emitting device of the present embodiment is characterized in that the first organic compound and the second organic compound form a first exciplex. By having this configuration, the first light-emitting layer Fluorescence emission from the first exciplex is emitted from the second emitting layer, and phosphorescence emission from the phosphorescent compound is emitted from the second emitting layer. Both photoluminescence and photoluminescence can be obtained efficiently.

[0058] Usually, when a fluorescent light-emitting layer and a phosphorescent light-emitting layer are laminated together to emit light, the triplet state of the phosphorescent compound is The excitation energy is transferred to the host material that occupies most of the fluorescent-emitting layer, resulting in significant luminescence. This is because the fluorescent layer usually contains a host material As the raw material, substances with condensed aromatic ring skeletons, such as anthracene, are used. Therefore, the triplet level is low, and the triplet excitation energy generated in the phosphorescent layer is transferred to the At present, it is not possible to obtain the desired product by using a substance other than a substance having a fused aromatic ring skeleton. Since it is difficult to obtain the emission wavelength and good device characteristics and reliability, Therefore, it is difficult to obtain a light-emitting element having good characteristics by laminating an optical layer and a light-emitting layer.

[0059] Here, the exciplex used in the first light-emitting layer of this embodiment is composed of two kinds of substances. In the case of photoexcitation, one excited molecule reacts with another It is formed by incorporating ground state material and therefore by emitting light. When it returns to the ground state, it behaves as the original substance again. There is no energy transfer between exciplexes or from other substances to exciplexes. Therefore, energy transfer to the first exciplex cannot occur in principle. Therefore, the light emitting element of this embodiment has a first light emitting layer and a second light emitting layer. By suppressing the energy transfer between the two, it is possible to obtain a light-emitting device that can easily achieve both fluorescent and phosphorescent emission. This can be done.

[0060] The first organic compound and the second organic compound in the first light-emitting layer 113a are The triplet excitation level of the phosphorescent compound in the second light-emitting layer 113b is higher than that of the phosphorescent compound in the second light-emitting layer 113b. By selecting the triplet excited level of the phosphorescent compound, the first light-emitting layer 113 The energy transfer to the ground state material of a can also be suppressed.

[0061] In addition, organic compounds in an excited state quickly form exciplexes, so Energy transfer from the organic compound in an excited state before the formation of the compound is also unlikely to occur.

[0062] From the above, the light-emitting element of this embodiment can be obtained by emitting light via the host material that occupies most of the light-emitting layer. Therefore, the fluorescent emission of the first exciplex in the first emitting layer and the This light-emitting device is easy to achieve both phosphorescence and the phosphorescent emission of the phosphorescent compound in the second light-emitting layer.

[0063] Furthermore, a first exciplex is formed by the first organic compound and the second organic compound, and the By obtaining light emission from exciplexes, it is possible to obtain the desired emission while using materials with high triplet excitation levels. Furthermore, the emission of the exciplex is , and light emission resulting from the energy difference between the shallower HOMO and the deeper LUMO can be obtained. By changing the combination of the first organic compound and the second organic compound, a desired It is easy to obtain light emission of this order.

[0064] In addition, the first light-emitting layer 113a further contains a fluorescent material as a dopant in an amount of up to several wt %. It may be contained as (specifically, 0.01 wt% to 5 wt%, more preferably 0. 01wt%~1wt%. At this level of amount, energy transfer via fluorescent material is possible. Energy transfer through the host material is not a major issue, and the use of exciplexes allows for Therefore, the fluorescence emission of the fluorescent substance and the phosphorescence emission of the phosphorescent compound are suppressed. In addition, the first exciplex can be converted into a fluorescent substance with a high fluorescence quantum yield. By transferring energy, it is also possible to improve the luminous efficiency. As shown above, the exciplex formed in the first emitting layer has a singlet excited level and a triplet excited level close to each other. Since the electrons are in a state where the triplet excited state is high, reverse intersystem crossing from the triplet excited state to the singlet excited state is likely to occur. In other words, it is possible to convert part of the triplet excited state into the singlet excited state, which is advantageous over conventional methods ( 25%), the proportion of the singlet excited state increases. By transferring energy from the large singlet excited state to a fluorescent substance, Higher luminous efficiency can be obtained than that of a light-emitting element using a light-emitting material. The ability to generate a singlet excited state from a double excited state (exciplex) and the ability to efficiently generate a singlet excited state from a singlet excited state The function of obtaining light emission (fluorescent material as a dopant) is often performed by a different material. Therefore, high luminous efficiency can be easily obtained. This reduces quenching and chemical reactions caused by impurities, leading to a longer lifespan.

[0065] The second light-emitting layer 113b further contains a fourth organic compound, and the third organic compound and the fourth organic compound may be a combination that forms a second exciplex. By adopting such a configuration in the second light-emitting layer 113b, the energy between the light-emitting layers can be more effectively distributed. As will be described later, the phosphorescence from the second exciplex can be suppressed. Configurations can also be realized that further improve energy transfer to the compound.

[0066] Combination of the first and second organic compounds to form an exciplex, and the third organic compound The combination of the compound and the fourth organic compound is a combination that can form an exciplex. However, one of them may be a material having hole transport properties and the other a material having electron transport properties. In this case, it is more preferable that the donor-acceptor type excited state is easily formed. This is because the exciplex can be efficiently formed. The first organic compound and the second organic compound are combined by combining a material having electron transport properties and a material having electron transport properties. Combination of two organic compounds, a third organic compound and a fourth organic compound When using a mixture of these two materials, the carrier balance can be easily controlled by adjusting the mixture ratio. In particular, the ratio of the material having hole transporting properties to the material having electron transporting properties is preferably in the range of 1:9 to 9:1. stomach.

[0067] The light-emitting element having this configuration can easily control the carrier balance. Therefore, the recombination region can be easily controlled. It is preferable that a recombination region is provided near the interface between the first light-emitting layer and the second light-emitting layer. The light-emitting element of this embodiment has a structure capable of suppressing energy transfer between light-emitting layers. Therefore, by placing the recombination region near the interface between the first and second light-emitting layers, The excitation energy can be distributed evenly to the light-emitting layers. From the viewpoint of distributing the photovoltaic energy, it is preferable that the recombination region is near the interface between the two light-emitting layers. It is preferable that the carrier recombination region is located at the interface between the first light emitting layer 113a and the second light emitting layer 113b. In order to make them close to each other, the first light-emitting layer 113a or the second light-emitting layer 113b, whichever is closer to the anode, is selected. The layer closer to the recombination region may be a hole transport layer, and the layer closer to the cathode may be an electron transport layer. When adjustment is required, the ratio of the material having hole transport properties to the material having electron transport properties is adjusted. In order to form a hole transporting layer, a layer having hole transporting properties is formed by In order to make the layer have electron transport properties, the layer should contain a large amount of a material having electron transport properties. In addition, when adjusting the luminescent color, a material having hole transporting properties and a material having electron transporting properties are used. This can be easily achieved by adjusting the proportions of the materials.

[0068] In addition, a combination of a first organic compound and a second organic compound and a combination of a third organic compound and a third organic compound are also included. The combination with the organic compound of 4 may be the same or different. The first and second exciplexes are the same exciplex. This makes it possible to further suppress the energy transfer between the first light-emitting layer and the second light-emitting layer. Since fewer types of materials are required, it is cost-effective and the element is easier to put into practical use. In addition, the carrier injection barrier at the interface between the first light-emitting layer and the second light-emitting layer is reduced. This also contributes to extending the life of the element.

[0069] Of course, the first and second exciplexes may be different exciplexes. In order to increase the luminous efficiency of the phosphorescent compound, the absorption wavelength of the phosphorescent compound is It is preferable to select a second exciplex having an emission wavelength that matches the In this case, the first and second exciplexes are likely to be different exciplexes. Since energy transfer between the first and second emitting layers is theoretically impossible, This makes it possible to suppress energy transfer between the two, making it easy to achieve both fluorescent and phosphorescent emission. Furthermore, a light-emitting element with higher luminous efficiency can be obtained.

[0070] In this light-emitting device, the light emitted from the first light-emitting layer is stronger than the light emitted from the second light-emitting layer. It is preferable that the phosphorescent material has a light emission peak on the shorter wavelength side than the phosphorescent material. Materials that emit short wavelengths with high energy are more unstable and emit short wavelengths. Light-emitting elements using phosphorescent materials tend to have a tendency to deteriorate quickly in brightness. By using light emission, it is possible to provide a light-emitting element with little deterioration in luminance. The light-emitting device has a first light-emitting layer, which is a fluorescent light-emitting layer, and a second light-emitting layer, which is a phosphorescent light-emitting layer, which are in contact with each other. Since the layers are laminated, the number of layers required to form the EL layer is small, which is advantageous in terms of cost and quantity. Even if the fluorescent-emitting layer and the phosphorescent-emitting layer are in contact with each other, as described above, The use of exciplexes makes it difficult for the triplet excited level to deactivate, resulting in phosphorescence and fluorescence. It is possible to achieve both light emission and photoluminescence.

[0071] Here, the first exciplex efficiently undergoes reverse intersystem crossing from the triplet excited level to the singlet excited level. It is preferable to clearly show that an exciplex has an energy difference between a singlet excited state and a triplet excited state. Since the difference is small, reverse intersystem crossing from the triplet excited level to the singlet excited level occurs. In other words, it is easy to emit delayed fluorescence. By applying it to the light-emitting layer of 1, the triplet excited state can also be converted into light emission. Therefore, it is possible to obtain a light-emitting device with higher luminous efficiency than when a normal fluorescent material is used. This delayed fluorescence is expressed and increased by slight heating (including self-heating). When the fluorescence is amplified (so-called thermally activated delayed fluorescence), delayed fluorescence (TADF) In addition, the conditions for efficiently obtaining delayed fluorescence are the triplet and singlet excited levels. The energy difference is 0 eV or more and 0.2 eV or less, preferably 0 eV or more and 0.1 eV or less. It is a preferred configuration to use an exciplex having such a relationship. do.

[0072] In addition, the light-emitting element in this embodiment has different light-emitting wavelengths in the first light-emitting layer and the second light-emitting layer. By obtaining light of a long wavelength, it is possible to make a multicolor light emitting element. The spectrum is composed of light with different emission peaks, so there are at least two This results in an emission spectrum with a maximum value.

[0073] Such a light-emitting device is also suitable for obtaining white light emission. By making the light from the light-emitting layer and the light from the light-emitting layer complementary to each other, white light can be emitted. The white light emitting element utilizes phosphorescence and has high luminous efficiency. The number of film layers is smaller than that of a stacked light emitting element, making it easier to provide at low cost. In addition, it is possible to obtain light from an exciplex that efficiently exhibits delayed fluorescence as light emission on the short wavelength side. By utilizing the light emission of the above, a light emitting element with high light emitting efficiency and long life can be obtained. can be done.

[0074] Here, in order to obtain a light-emitting element with higher luminous efficiency, the phosphorescent material in the second luminescent layer In this explanation, we will consider the energy transfer to the phosphorescent material. The substance that provides this is called the host material. Since the phosphorescent material is used in both the host and the phosphorescent material, the phosphorescent material must be removed from the host material to improve the luminous efficiency. It is necessary to efficiently transfer energy from the host material to the phosphorescent material. Two mechanisms for energy transfer have been proposed: the Dexter mechanism and the Förster mechanism.

[0075] Energy transfer efficiency Φ from host molecules to guest molecules ET is expressed by the following formula: k r is the emission process (fluorescence when discussing energy transfer from the singlet excited state, and triplet excited state). When discussing energy transfer from the nucleus to the nucleus, k represents the rate constant of phosphorescence, and k n is a non-radiative process represents the rate constant of the excited state (thermal deactivation or intersystem crossing), and τ represents the lifetime of the excited state.

[0076]

number

[0077] First, from the above formula, the energy transfer efficiency Φ ET To increase the rate constant k h * →g , other competing rate constants k r +k n (=1 / τ) is much larger than The rate constant of the energy transfer, k h * →g Enlarge In order to achieve this, both the Förster mechanism and the Dexter mechanism require the host The emission spectrum of a molecule (or the fluorescence spectrum when discussing energy transfer from a singlet excited state) (phosphorescence spectrum when discussing energy transfer from triplet excited states) and guest The larger the overlap with the absorption spectrum of the molecule (phosphorescent material in the second emitting layer) is good.

[0078] Here, considering the overlap between the emission spectrum of the host molecule and the absorption spectrum of the phosphorescent material, In this regard, the absorption spectrum of the phosphorescent material is determined by the absorption at the longest wavelength (lowest energy). Consolidation is important.

[0079] It is believed to be the most important contributor to the emission in the absorption spectrum of phosphorescent materials. The absorption band is located near the absorption wavelength corresponding to the direct transition from the ground state to the triplet excited state. This is the absorption band that appears on the longest wavelength side. The fluorescence spectrum and phosphorescence spectrum are the longest wavelengths in the absorption spectrum of phosphorescent materials. It is considered preferable that the absorption band overlaps with the absorption band on the long side.

[0080] For example, in organometallic complexes, especially in luminescent iridium complexes, the longest wavelength absorption band is In many cases, a broad absorption band appears around 500 to 600 nm. Mainly, triplet MLCT (Metal to Ligand Charge Transfer) However, this absorption band is due to the triplet π-π transition. * Transition or singlet MLCT This includes some absorption due to transitions, and these overlap to form the absorption spectrum at the longest wavelength side. It is thought that a broad absorption band is formed. Therefore, it is considered that the guest material is an organometallic complex. When using complexes (especially iridium complexes), the broad spectrum at the longest wavelength is It is preferable that the absorption band of the host material largely overlaps with the emission spectrum of the host material.

[0081] First, let us consider the energy transfer from the triplet excited state of the host material. From the discussion, it can be seen that the phosphorescence spectrum of the host material changes with the energy transfer from the triplet excited state. It is sufficient that the overlap between the absorption band of the phosphorescent material and the absorption band on the longest wavelength side of the phosphorescent material is large.

[0082] However, the problem here is the energy from the singlet excited state of the host molecule. In addition to the energy transfer from the triplet excited state, the energy transfer from the singlet excited state From the above discussion, in order to efficiently transfer electrons, the phosphorescence spectrum of the host material must be Furthermore, the fluorescence spectrum is designed to overlap with the longest wavelength absorption band of the guest material. In other words, the fluorescent spectrum of the host material must be the same as the phosphorescent spectrum. If the host material is not designed to be at a similar position, the singlet excited state and This means that energy transfer from both the excited and triplet states cannot be performed efficiently. becomes.

[0083] However, in general, the singlet excitation level and the triplet excitation level are very different (singlet excitation level > triplet excited level), the emission wavelength of fluorescence and that of phosphorescence are also significantly different (fluorescence emission For example, it is often used in light-emitting devices that use phosphorescent materials. 4,4'-di(N-carbazolyl)biphenyl (abbreviation: CBP) is a 500 nm It has a phosphorescence spectrum around 400 nm, while its fluorescence spectrum is around 1 Even in this example, the fluorescence spectrum of the host material is It is extremely difficult to design a host material that has a similar position in the phosphorescence spectrum. is.

[0084] Also, the singlet excited level in a certain substance is higher in energy than the triplet excited level. Therefore, the fluorescence spectrum is close to the absorption spectrum of the longest wavelength of the guest material. The triplet excited level of the host material at such wavelengths is lower than that of the guest material. Put away.

[0085] However, in the second light-emitting layer of the light-emitting element of this embodiment, The fluorescence spectrum of the exciplex is similar to that of the third organic compound alone and the fourth organic compound alone. The emission spectrum has a longer wavelength side than the fluorescence spectrum of the organic compound alone, so The triplet excitation levels of the first and fourth organic compounds are compared with the triplet excitation levels of the guest material. It is possible to maximize the energy transfer from the singlet excited state while keeping the electron energy level higher than the In addition, since the triplet excited level and the singlet excited level are close to each other in the exciplex, Therefore, the fluorescence spectrum and phosphorescence spectrum are located at almost the same position. Absorption corresponding to the transition from the singlet ground state to the triplet excited state of the guest molecule (absorption of the guest molecule) The fluorescence spectrum of the exciplex is located in the broad absorption band at the longest wavelength side of the spectrum. The large overlap of both the luminescence and phosphorescence spectra allows for high energy transfer efficiency. Therefore, a light-emitting element with high efficiency can be obtained.

[0086] In this way, in the second emitting layer, the lowest energy absorption band of the phosphorescent material and The emission spectrum of the second exciplex overlaps with that of the first exciplex, thereby providing a light-emitting element with improved emission efficiency. In addition, the peak wavelength of the absorption band on the lowest energy side of the phosphorescent material can be obtained. and the difference between the converted energy values ​​of the peak wavelengths of the emission spectrum of the second exciplex is 0.2 If the distance is less than 1000 eV, the overlap is large, which is a preferable configuration.

[0087] In FIG. 1A, the first light-emitting layer 113a is connected to the first electrode 101 which functions as an anode. The second light-emitting layer 113b is formed on the side of the second electrode 102 that functions as a cathode. However, this stacking order may be reversed.

[0088] (Embodiment 2) In this embodiment, an example of a detailed structure of the light-emitting element described in Embodiment 1 will be described with reference to FIG. 1(A) . ) will be used below for explanation.

[0089] The light-emitting element in this embodiment mode 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 other words, the first electrode 101 is closer to the second electrode 10 A voltage was applied to 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.

[0090] The first electrode 101 functions as an anode, so it is made of 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 preferable. in Oxide), indium oxide-tin oxide containing silicon or silicon oxide, Indium oxide - zinc oxide, tungsten oxide and zinc oxide containing indium oxide ( These conductive metal oxide films are usually formed by sputtering. However, it may also be prepared by applying the sol-gel method. Indium oxide-zinc oxide is made by adding 1 to 20 wt% of zinc oxide to indium oxide. There are also methods for forming the film by sputtering using a target containing an oxide film. Indium oxide containing tungsten and zinc oxide (IWZO) has the following properties compared to indium oxide: The target contains 0.5 to 5 wt% of tungsten oxide and 0.1 to 1 wt% of zinc oxide. It can also be formed by sputtering using gold (Au), platinum ( Pt), Nickel (Ni), Tungsten (W), Chromium (Cr), Molybdenum (Mo) , iron (Fe), cobalt (Co), copper (Cu), palladium (Pd), or metallic materials Nitrides (for example, titanium nitride) and the like can be used. Graphene can also be used. By using a composite material described later for the layer in contact with the first electrode 101 in the EL layer 103, This allows electrode materials to be selected regardless of their work functions.

[0091] 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-described structure is satisfied, other layers are not particularly limited. For example, a hole injection layer, a hole transport layer, a light emitting layer, an electron It can be configured by appropriately combining a transport layer, an electron injection layer, a carrier blocking layer, an intermediate layer, etc. In this embodiment, the EL layer 103 is a hole transport layer formed by stacking the first electrode 101 in order. 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 shown below.

[0092] The hole injection layer 111 is a layer containing a substance with high hole injection properties. Use of zinc oxide, ruthenium oxide, tungsten oxide, manganese oxide, etc. In addition, phthalocyanine (abbreviated as H2Pc) and copper phthalocyanine (CuPC) Phthalocyanine compounds such as 4,4'-bis[N-(4-diphenylaminophenyl )-N-phenylamino]biphenyl (abbreviation: DPAB), N,N'-bis{4-[bis (3-methylphenyl)amino]phenyl}-N,N'-diphenyl-(1,1'-biphenyl) aromatic amine compounds such as phenyl-4,4'-diamine (abbreviation: DNTPD), or poly Poly(ethylenedioxythiophene) / poly(styrenesulfonic acid) (PEDOT / PSS The hole injection layer 111 can also be formed from a polymer such as .

[0093] In addition, the hole injection layer 111 is formed by adding an acceptor substance to a hole transporting substance. A composite material can be used. Note that the hole transporting material may contain an acceptor material. By using a material that has the same work function as the electrode, it is possible to select the material for forming the electrode regardless of the work function of the electrode. That is, the first electrode 101 can be made of not only a material with a large work function but also a material with a low work function. Small materials can also be used. ,8-Tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation: F4-TC NQ), chloranil, etc. Also included are transition metal oxides. Further examples include oxides of metals belonging to groups 4 to 8 in the periodic table. Specifically, vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, molyb oxide Tungsten oxide, manganese oxide, and rhenium oxide are preferred due to their high electron-accepting properties. Among them, molybdenum oxide is particularly stable in the air, has low hygroscopicity, and is easy to handle. preferable.

[0094] As hole transporting substances used in composite materials, aromatic amine compounds, carbazole derivatives, Species such as organic compounds, aromatic hydrocarbons, and polymeric compounds (oligomers, dendrimers, polymers, etc.) Various organic compounds can be used. It is preferable that the organic compound has high hole transport properties. -6 cm 2 / Vs or later In the following, the hole transport in the composite material is Specific examples of organic compounds that can be used as transport materials are listed below.

[0095] 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 Phenyl-(1,1'-biphenyl)-4,4'-diamine (abbreviation: DNTPD), 1,3 ,5-Tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene (abbreviation: DPA3B), etc.

[0096] 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.

[0097] 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. You can be there.

[0098] 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)-9,9'-bianthryl, (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.

[0099] The aromatic hydrocarbons 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.

[0100] In addition, poly(N-vinylcarbazole) (abbreviation: PVK) and poly(4-vinyltriphenyl ether) 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 [(phenyl)benzidine] (abbreviation: Poly-TPD) can also be used. can.

[0101] By forming a hole injection layer, the hole injection property is improved, and a light emitting device with a low driving voltage can be obtained. It is possible to obtain an optical element.

[0102] The hole transport layer 112 is a layer containing a substance with a hole transport 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 can be used. , mainly 10 -6 cm 2 The composite material has a hole mobility of 1 / Vs or more. The organic compounds listed as hole transporting materials in the material can also be used for the hole transport layer 112. In addition, poly(N-vinylcarbazole) (abbreviated as PVK) and poly(4-vinyl carbazole) Polymer compounds such as phenyltriphenylamine (PVTPA) can also be used. The layer containing the hole transporting substance may be a single layer or may be two or more layers containing the above substance. It may also be a laminate.

[0103] The light-emitting layer 113 has the same structure as that of the light-emitting layer 113 described in Embodiment 1. From the first electrode side, a first light-emitting layer 113a and a second light-emitting layer 113b are stacked. The first light-emitting layer 113a contains a first organic compound and a second organic compound. The second light-emitting layer 113b contains a third organic compound, a fourth organic compound, and a phosphorescent compound. The light-emitting element of this embodiment is characterized by the fact that the first organic compound and the second organic compound The compounds are combined to form a first exciplex, and a third organic compound and a fourth organic compound are combined to form a second exciplex. The compound is a combination that forms a second exciplex. The complex exhibits fluorescence, and the second exciplex provides energy to the phosphorescent compound, which then converts the first Both fluorescent light from the light-emitting layer and phosphorescent light from the second light-emitting layer can be efficiently obtained.

[0104] In the second light-emitting layer 113b, materials that can be used as phosphorescent compounds include For example, the following can be mentioned:

[0105] Tris{2-[5-(2-methylphenyl)-4-(2,6-dimethylphenyl)-4H -1,2,4-triazol-3-yl-κN2]phenyl-κC}iridium(III ) (abbreviation: Ir(mpptz-dmp)3), tris(5-methyl-3,4-diphenyl -4H-1,2,4-triazolato)iridium(III) (abbreviation: Ir(Mptz)3 ), tris[4-(3-biphenyl)-5-isopropyl-3-phenyl-4H-1,2 ,4-triazolato]iridium(III) (abbreviation: Ir(iPrptz-3b)3) Organometallic iridium complexes with 4H-triazole skeletons, such as tris[3-methyl -1-(2-methylphenyl)-5-phenyl-1H-1,2,4-triazolato]yl Ir(Mptz1-mp)3, tris(1-methyl-5-fluorouracil), (phenyl-3-propyl-1H-1,2,4-triazolato)iridium(III) (abbreviation Organometallic imines with 1H-triazole skeletons, such as Ir(PrPrtZ1-Me)3) Lithium complexes and fac-tris[(1-2,6-diisopropylphenyl)-2-phenyl] iridium(III) (abbreviation: Ir(iPrpmi)3), Tris[3-(2,6-dimethylphenyl)-7-methylimidazo[1,2-f]phena Iridium(III) (abbreviation: Ir(dmpimpt-Me)3) Organometallic iridium complexes with various imidazole structures and bis[2-(4',6'-difluoromethyl)-2-(4-phenyl ... (fluorophenyl)pyridinato-N,C 2’ ]iridium(III) tetrakis(1-pyra 2-(4',6'-difluorophenyl) bis[2-(4',6'-difluorophenyl) benzoate (abbreviation: FIr6) Pyridinato-N,C 2’ ]iridium(III) picolinate (abbreviation: FIrpic), Bis{2-[3',5'-bis(trifluoromethyl)phenyl]pyridinato-N,C 2 ’} Iridium(III) picolinate (abbreviation: Ir(CF3ppy)2(pic)), Bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2’ ]iridium( III) Fumarate containing an electron-withdrawing group such as acetylacetonate (abbreviated as FIracac) Organometallic iridium complexes with phenylpyridine derivatives as ligands are known. It is a compound that exhibits colored phosphorescence, with an emission peak between 440 nm and 520 nm. It is a compound.

[0106] Also, 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- (4-phenyl-4-pyrimidinato)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) (acetylacetonate) )Bis[5-methyl-6-(2-methylphenyl)-4-phenylpyrimidinato]iridine 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-phenylpyrazinato)iridium(I II) (Abbreviation: Ir(mppr-Me)2(acac)), (acetylacetonato)bis (5-isopropyl-3-methyl-2-phenylpyrazinato)iridium(III) Name: Organometallic iridium compounds with pyrazine skeletons, such as Ir(mppr-iPr)2(acac) Lithium complexes and 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(benzoyl) Ir(bzq) )2(acac)), tris(benzo[h]quinolinato)iridium(III) (abbreviation: Ir(bzq)3), tris(2-phenylquinolinato-N,C 2’ ) Iridium (II I) (abbreviation: Ir(pq)3), bis(2-phenylquinolinato-N,C 2’ ) Irijiu Pyrils such as Ir(III) acetylacetonate (abbreviated as Ir(pq)2(acac)) In addition to organometallic iridium complexes with an iridium skeleton, tris(acetylacetonato)(monofuran) phenanthroline) terbium(III) (abbreviation: Tb(acac)3(Phen)) These are compounds that mainly exhibit green phosphorescence, It has an emission peak at 500nm to 600nm. Iridium complexes of the group 1 are particularly preferred because they are remarkably excellent in reliability and luminous efficiency.

[0107] Also, (diisobutyrylmethanato)bis[4,6-bis(3-methylphenyl)pyrimidinyl] Nato]iridium(III) (abbreviation: Ir(5mdppm)2(dibm)), bis[4 ,6-bis(3-methylphenyl)pyrimidinato](dipivaloylmethanato)iridium (III) (abbreviation: Ir(5mdppm)2(dpm)), bis[4,6-di(naphthalene)] (1-phenyl-1-yl)pyrimidinato](dipivaloylmethanato)iridium(III) (abbreviation: Organometallic iridium with a pyrimidine backbone, such as Ir(d1npm)2(dpm) Complexes and (acetylacetonato)bis(2,3,5-triphenylpyrazinato)iridium Ir(tppr)2(acac)), bis(2,3,5-triphenylphosphine) Nylpyrazinato)(dipivaloylmethanato)iridium(III) (abbreviation: Ir(tpp r) 2(dpm)), (acetylacetonato)bis[2,3-bis(4-fluorophenyl) Ir(Fdpq)2(acac) Organometallic iridium complexes with pyrazine skeletons such as tris(1-phenylisoxid) Norinato-N,C 2’ ) Iridium(III) acetylacetonate (abbreviation: Ir(pi q)3), Bis(1-phenylisoquinolinato-N,C 2’ ) Iridium (III) (abbreviation Organometallic iridium with a pyridine skeleton, such as Ir(piq)2(acac) In addition to the complex, 2,3,7,8,12,13,17,18-octaethyl-21H,23H- Platinum complexes such as porphyrin platinum(II) (abbreviation: PtOEP) and tris(1,3- Diphenyl-1,3-propanedionato)(monophenanthroline)europium(II) I) (abbreviation: Eu(DBM)3(Phen)), tris[1-(2-thenoyl)-3,3 ,3-trifluoroacetonato](monophenanthroline)europium(III)(abbreviation These include rare earth metal complexes such as Eu(TTA)3(Phen). A compound that exhibits red phosphorescence, with an emission peak between 600 nm and 700 nm. In addition, organometallic iridium complexes with a pyrazine skeleton can emit red light with good chromaticity. can be.

[0108] In addition to the phosphorescent compounds described above, known phosphorescent light-emitting materials may be selected and used. stomach.

[0109] When the first light-emitting layer 113a contains a fluorescent material, the following compound may be used: Other known fluorescent materials can also be used.

[0110] 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-calcium (bazol-9-yl)-4'-(10-phenyl-9-anthryl)triphenylamine (Abbreviation: YGAPA), 4-(9H-carbazol-9-yl)-4'-(9,10-di N,9-diphenyl-2-anthryl)triphenylamine (abbreviation: 2YGAPPA) 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-biphenyl Bis(1,1'-biphenyl-2-yl)-N-[4-(9H-carbazol-9-yl) Phenyl]-N-phenylanthracen-2-amine (abbreviation: 2YGABPhA), N, N,9-triphenylanthracen-9-amine (abbreviation: DPhAPhA) Coumarin 54 5T, N,N'-diphenylquinacridone, (abbreviation: DPQd), rubrene, 5,12- Bis(1,1'-biphenyl-4-yl)-6,11-diphenyltetracene (abbreviation: B PT), 2-(2-{2-[4-(dimethylamino)phenyl]ethenyl}-6-methyl -4H-pyran-4-ylidene)propanedinitrile (abbreviation: DCM1), 2-{2-methyl- 6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolinyl] {4H-pyran-4-ylidene}propanedinitrile (abbreviated :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[i j]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinite 2-(2-tert-butyl-6-[2-(1,1,7,7 -Tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizidine 4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCJTB), 2-(2,6-bis{2-[4-(dimethylamino)phenyl]ethenyl }-4H-pyran-4-ylidene)propanedinitrile (abbreviation: BisDCM), 2-{ 2,6-bis[2-(8-methoxy-1,1,7,7-tetramethyl-2,3,6,7- Tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H- pyran-4-ylidene}propanedinitrile (abbreviation: BisDCJ™) In particular, pyrene diamines such as 1,6FLPAPrn and 1,6mMemFLPAPrn Condensed aromatic diamine compounds, such as fluorine compounds, have high hole trapping properties and high luminous efficiency. This is preferred because it has excellent reliability.

[0111] The fluorescent substance also includes a substance that efficiently exhibits delayed fluorescence. The substance can convert a part of the triplet excited state into a singlet excited state and contribute to light emission. In other words, the first light-emitting layer forms an exciplex, and the luminous efficiency can be improved. A synergistic effect can be expected with the use of the following materials: can be done.

[0112] Fullerene and its derivatives, acridine derivatives such as proflavine, eosin, etc. Sium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), Examples include metal-containing porphyrins containing indium (In) or palladium (Pd). The metal-containing porphyrin may be, for example, protoporphyrin represented by the following structural formula: Porphyrin-tin fluoride complex (SnF2(Proto IX)), mesoporphyrin-fluoride Tin complex (SnF2(Meso IX)), hematoporphyrin-tin fluoride complex (Sn F2 (Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride Complex (SnF2(Copro III-4Me)), Octaethylporphyrin-Fluoride Tin complex (SnF2(OEP)), etioporphyrin-tin fluoride complex (SnF2(E tio I)), octaethylporphyrin-platinum chloride complex (PtCl2OEP), etc. It can be obtained.

[0113] [ka]

[0114] In addition, 2-biphenyl-4,6-bis(12-phenylindolo) represented by the following structural formula [2,3-a]carbazol-11-yl)-1,3,5-triazine (PIC-TRZ Heterocyclic compounds having a π-electron rich heteroaromatic ring and a π-electron deficient heteroaromatic ring, such as The heterocyclic compound can be a π-electron rich heteroaromatic ring or a π-electron deficient heteroaromatic ring. Since it has a ring, it has high electron transport properties and hole transport properties, which is preferable. A substance in which an aromatic ring and a π-electron-deficient heteroaromatic ring are directly bonded is a dopant of a π-electron-rich heteroaromatic ring. The acceptor property of the π-electron-deficient heteroaromatic ring is also strengthened, and the S1 and T1 levels This is particularly preferable because the energy difference between

[0115] [ka]

[0116] The first organic compound, the second organic compound, the third organic compound, and the fourth organic compound The materials that can be used as the substrate include those that satisfy the conditions described in the first embodiment. There are no particular limitations as long as the carrier transport material is a combination, and various carrier transport materials can be selected.

[0117] For example, bis(10-hydroxybenzo[h]quinolinol) Nat)beryllium(II) (abbreviation: BeBq2), bis(2-methyl-8-quinolinolato) )(4-phenylphenolato)aluminum(III) (abbreviation: BAlq), bis(8- Quinolinolato)zinc(II) (abbreviation: Znq), bis[2-(2-benzoxazolyl) phenolato]zinc(II) (abbreviation: ZnPBO), bis[2-(2-benzothiazolyl) phenolato]zinc(II) (abbreviation: ZnBTZ) and other metal complexes, (4-tert-butylphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation :PBD), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl) phenyl)-1,2,4-triazole (abbreviation: TAZ), 1,3-bis[5-(p-te rt-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl) phenyl]-9H-carbazole (abbreviation: CO11), 2,2',2''-(1,3,5 -benzenetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TP BI), 2-[3-(dibenzothiophen-4-yl)phenyl]-1-phenyl-1H -benzimidazole (abbreviation: mDBTBIm-II) Heterocyclic compounds and 2-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f ,h]quinoxaline (abbreviation: 2mDBTPDBq-II), 2-[3'-(dibenzothiophene [f,h]quinoxaline (abbreviated as 2-phenyl-4-yl)biphenyl-3-yl)dibenzo[f,h]quinoxaline mDBTBPDBq-II), 2-[3'-(9H-carbazol-9-yl)biphenyl 4,6-Dibenzo[f,h]quinoxaline (abbreviation: 2mCzBPDBq) -Bis[3-(phenanthrene-9-yl)phenyl]pyrimidine (abbreviation: 4,6mPn P2Pm), 4,6-bis[3-(4-dibenzothienyl)phenyl]pyrimidine (abbreviation Heterocyclic compounds with diazine skeletons such as 3,5 -Bis[3-(9H-carbazol-9-yl)phenyl]pyridine (abbreviation: 35DCz PPy), 1,3,5-tri[3-(3-pyridyl)-phenyl]benzene (abbreviation: Tm PyPB) and other heterocyclic compounds having a pyridine skeleton. Heterocyclic compounds with an azine skeleton and heterocyclic compounds with a pyridine skeleton have good reliability. In particular, heterocyclic compounds having a diazine (pyrimidine or pyrazine) skeleton are The electron transport property is high, and this contributes to reducing the driving voltage.

[0118] Furthermore, examples of materials having hole transport properties include 4,4'-bis[N-(1-naphthyl)-N- N,N'-bis(3-methylphenyl)phenylaminobiphenyl (abbreviation: NPB) -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-phenyl-4-fluorophenyl)-4-phenyl-4'-(4-phenyl-4-fluorophenyl)-4-phenyl-4'-(9 ... 4-phenyl-3'-phenyl-2-phenyl-2-phenyl-1,3-diol-2-ol (abbreviation: BPAFLP) (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)- (9H-carbazol-3-yl)triphenylamine (abbreviation: PCBNBB), ,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 phenyl) 3,3'-bis(9-phenyl)-9-phenylcarbazole (abbreviation: CzTP), Compounds with a carbazole skeleton, such as PCCP (9H-carbazole) , 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (Abbreviation: DBT3P-II), 2,8-diphenyl-4-[4-(9-phenyl-9H- Fluoren-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-III) , 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyl Compounds with a thiophene skeleton, such as dibenzothiophene (abbreviation: DBTFLP-IV) and 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzofuran) ( Abbreviation: DBF3P-II), 4-{3-[3-(9-phenyl-9H-fluorene-9- (I)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II) Among the above, compounds having an aromatic amine skeleton are preferred. Compounds having a carbazole skeleton and compounds having a high reliability and high hole transport property are also used. This is preferable because it contributes to reducing the driving voltage.

[0119] In addition to the above-mentioned carrier transport materials, carrier transport materials from known substances may be used. The first to fourth organic compounds 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 substance that has a shallow valence. The luminescence is due to the energy difference between the lower HOMO level and the deeper LUMO level. Therefore, the first organic compound and the second organic compound are selected to be a combination that realizes emission of a desired emission wavelength. The third and fourth organic compounds are selected from the most phosphorescent compounds. A compound that forms an exciplex that emits light that overlaps with the wavelength of the low-energy absorption band. It is preferable to select a combination.

[0120] Furthermore, one of these combinations may be a material having electron transport properties and the other a material having hole transport properties. By using a material containing these compounds, it is advantageous for the formation of an exciplex. By changing the dopant concentration, the transport properties of the light-emitting layer can be easily adjusted, and the recombination region can also be controlled. The content of the material having hole transport properties and the material having electron transport properties can be easily determined. The ratio of the material having hole transport properties to the material having electron transport properties may be 1:9 to 9:1. .

[0121] The light-emitting layer 113 having the above-described structure can be formed by co-evaporation using a vacuum evaporation method or by forming a mixed solution. It can be produced 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 further divided into two layers, and the second light-emitting layer 113b may be divided into two layers. In this case, it is preferable that the ratio of the content of the third organic compound to the content of the fourth organic compound is different. This makes it possible to further suppress the deterioration in luminance of the light-emitting element.

[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 with electron transport properties. For example, tris(8-quinolinol) Tris(4-methyl-8-quinolinolato)aluminum (abbreviation: Alq), tris(4-methyl-8-quinolinolato)aluminum Almq3, bis(10-hydroxybenzo[h]quinolinato)beri Sodium (abbreviation: BeBq2), bis(2-methyl-8-quinolinolato)(4-phenylphenyl) quinoline or benzoquinoline skeletons, such as aluminum benzoate (abbreviation: BAlq) The layer is made of a metal complex having a structure. bis[2-(2-hydroxybenzoyl)benzoxazolato]zinc (abbreviation: Zn(BOX)2), Oxazoles such as [(oxyphenyl)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 (abbreviated as PBD) and 1,3-bis[5-(p-tert-butyl phenyl)-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 (abbreviated as BCP), etc. can also be used. has high electron transport properties and is mainly -6 cm 2 / Vs or higher electron mobility The electron-transporting host material described above may be used for the electron-transporting layer 114.

[0126] The electron transport layer 114 may be not only a single layer, but also a layer of two or more layers made of the above-mentioned materials. It may also be layered.

[0127] Furthermore, 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. It is a layer that adjusts the carrier balance by suppressing the movement of electron carriers. This type of structure prevents electrons from penetrating the light-emitting layer. This is highly effective in suppressing problems that arise (for example, a reduction in the device life).

[0128] In addition, an electron transport layer 114 is formed 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 their compounds can be used. For example, The layer is made of a material containing an alkali metal or alkaline earth metal or a compound thereof. Note that the electron-injecting layer 115 can be formed using a material having an electron-transporting property. By using a layer containing an alkali metal or alkaline earth metal This is more preferable because electrons are efficiently injected from the second electrode 102 .

[0129] The material forming the second electrode 102 is selected from those having a small work function (specifically, 3.8 eV Metals, alloys, electrically conductive compounds, and mixtures thereof can be used. Specific 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, rare earth metals such as AlLi), europium (Eu), ytterbium (Yb) and However, the second electrode 102 and the electron transport layer may be formed of a material other than the material itself. By providing an electron injection layer, it is possible to use Al, Ag, ITO, and ketone regardless of the magnitude of the work function. Various conductive materials such as indium oxide-tin oxide containing silicon or silicon oxide are used as the second These conductive materials can be used as the electrode 102. The film can be formed by a jet method, a spin coating method, or the like.

[0130] The EL layer 103 can be formed by various methods, including dry and wet methods. For example, a vacuum deposition method, an ink jet 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 also be formed by a wet method using the sol-gel method, or by a paste of a metal material. Alternatively, the film may be formed by a dry method such as sputtering or vacuum deposition. It may be formed using

[0132] The light-emitting element having the above-described structure has a first electrode 101 and a second electrode 102. The generated potential difference causes a current to flow, and the light-emitting layer 113, which is a layer containing a highly luminescent substance, The holes and electrons are recombined 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 Alternatively, both electrodes may be made of a light-transmitting electrode. Only the first electrode 101 may be made of a light-transmitting electrode. When the second electrode 102 is When only the first electrode 102 is light-transmitting, emitted light is extracted through the second electrode 102. When the first electrode 101 and the second electrode 102 are both light-transmitting electrodes, the light-emitting is taken out from both the first electrode 101 and the second electrode 102.

[0134] The structure of the layers provided between the first electrode 101 and the second electrode 102 is the same as that described above. However, it is not limited to the above. The first electrode 101 and the second electrode 102 are arranged so as to suppress quenching caused by contact. A preferred configuration is one in which a light-emitting region where holes and electrons recombine is provided at a location away from 102 .

[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 this, the band gap is determined by the luminescent material that constitutes the luminescent layer or the material contained in the luminescent layer. The material has a band gap larger than that of the luminescent center material. It is preferable to form

[0136] The light emitting element in this embodiment is manufactured on a substrate made of glass, plastic, or the like. The order of fabrication on the substrate may be stacked from the first electrode 101 side. The light emitting device may be formed by forming one light emitting element on one substrate. A single light emitting element may be formed on one substrate, or a plurality of light emitting elements may be formed on one substrate. By fabricating multiple elements, it is possible to create lighting devices with separate elements and passive matrix light-emitting devices. Also, a thin film transistor can be formed on a substrate made of glass, plastic, or the like. A thin-film transistor (TFT) is formed, and a light-emitting element is fabricated on an electrode electrically connected to the TFT. This allows for an active matrix display in which the driving of the light-emitting elements is controlled by the TFTs. The structure of the TFT is not particularly limited. The TFT may be a TFT or an inverted staggered type. There are no particular limitations on the type of semiconductor, and either an amorphous semiconductor or a crystalline semiconductor may be used. In addition, the driving circuit formed on the TFT substrate is also made up of N-type and P-type TFTs. Alternatively, the TFT may be composed of only one of N-type TFTs or P-type TFTs. It may also be the case.

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

[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) has 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 the first electrode 501 and the second electrode 502. The knit 511 and the second light-emitting unit 512 are stacked, 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. 1(A), respectively. 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 different It may be a configuration.

[0140] The charge generating layer 513 contains 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 organic compounds, aromatic amine compounds, chlorine compounds, azole compounds, aromatic hydrocarbons, polymer compounds (oligomers, dendrimers, polymers) As the organic compound, various compounds such as hole mobility is 1×10 -6 cm 2 It is preferable to apply a value of / Vs or more. Other materials may be used as long as they have a higher hole transporting property than the organic compounds. Metal oxide composite materials have excellent carrier injection and carrier transport properties, making them suitable for low-voltage driving. In addition, the surface of the light-emitting unit on the anode side is a charge generating layer. When the charge generating layer is in contact with the light emitting unit, the charge generating layer can also serve as a hole transport layer for the light emitting unit. Therefore, the light-emitting unit does not need to have a hole transport layer.

[0141] The charge generation 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 and the A layer containing a composite material of a metal oxide and a compound selected from electron donating substances and an electron transporting substance. Alternatively, a layer containing an organic compound and a metal compound may be combined. A layer containing an oxide composite material and a transparent conductive film may be combined.

[0142] In any case, the electrode sandwiched between the first light-emitting unit 511 and the second light-emitting unit 512 When a voltage is applied to the first electrode 501 and the second electrode 502, the charge generation layer 513 generates a It is sufficient that the light-emitting element injects electrons into the light-emitting unit and 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 generation layer 513 generates electrons, the charge generation layer 513 generates electrons in the first light-emitting unit 511. The electron injection hole 514 may be injected into the second 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 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, high brightness light emission is possible while keeping the current density low, and furthermore, long life is achieved. Furthermore, it is possible to realize a light-emitting device that can be driven at a low voltage and consumes little power. This can be done.

[0144] In addition, by making the light-emitting color of each light-emitting unit different, the light-emitting element as a whole For example, a light-emitting element having two light-emitting units can be used. In this case, the first light-emitting unit emits red and green light, and the second light-emitting unit emits blue light. By doing so, it is possible to obtain a light-emitting element that emits white light as a whole.

[0145] At least one of the plurality of units has the above-described 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 multicolor light emitting device that is advantageous for practical use.

[0146] The above configuration may be appropriately combined with other embodiments or other configurations in this embodiment. It is possible to do this.

[0147] (Embodiment 3) In this embodiment, a light-emitting device using the light-emitting element described in Embodiment 1 or 2 This article explains:

[0148] In this embodiment, a light-emitting element manufactured using the light-emitting element described in Embodiment 1 or 2 is The light-emitting device will be described with reference to FIG. 2. FIG. 2(A) is a top view showing the light-emitting device. 2(B) is a cross-sectional view taken along lines AB and CD in FIG. 2(A). The light emitting element is controlled by a driving circuit (source line driving circuit) shown by a dotted line. The display device includes a display circuit (gate line driver circuit) 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.

[0149] 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, this 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.

[0150] Next, the cross-sectional structure will be described with reference to FIG. A source line driver circuit 601, which is a driver circuit portion, is formed in this example. , one pixel in the pixel section 602 is shown.

[0151] The source line driver circuit 601 includes an n-channel TFT 623 and a p-channel TFT 62 4 is combined to form a CMOS circuit. In addition, the drive circuit is a CMOS circuit Alternatively, the substrate may be formed of a PMOS circuit or an NMOS circuit. Although the driver integrated type with the drive circuit formed on the top is shown, this is not necessarily required. It may also be formed externally rather than on the substrate.

[0152] The pixel section 602 includes a switching TFT 611, a current control TFT 612, and The pixel is formed by 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.

[0153] In order to improve the covering property, the upper end or the lower end of the insulator 614 is provided with a curvature. For example, the material of the insulator 614 is a positive photosensitive adhesive. When using krill, the radius of curvature (0.2 μm to 3 μm) is provided only at the upper end of the insulator 614. It is preferable to provide a curved surface. Alternatively, a positive photosensitive resin can be used.

[0154] 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 It is desirable to use a material with a large resistance. For example, an ITO film or an insulator 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, Zn film, and Pt film, titanium nitride film and aluminum film are also available. a titanium nitride film and a film mainly composed of aluminum; a titanium nitride film and a film mainly composed of aluminum and a titanium nitride film A three-layer structure with a titanium film can be used. It has low resistance, good ohmic contact, and can function as an anode. do.

[0155] The EL layer 616 can be formed by a deposition method using a deposition mask, an inkjet method, or a spin coating method. The EL layer 616 is formed by various methods such as the method of forming the EL layer 616 in accordance with the first embodiment or the second embodiment. Other materials that make up the EL layer 616 include: It may be a low molecular weight compound or a high molecular weight compound (including an oligomer or dendrimer). .

[0156] Furthermore, a material used for the second electrode 617 formed on the EL layer 616 and functioning as a cathode is The materials used are those with a low work function (Al, Mg, Li, Ca, or their alloys or compounds). It is preferable to use a material such as an alloy of MgAg, MgIn, or AlLi. When the light generated in 6 is transmitted through the second electrode 617, the second electrode 617 is Thin metal films and transparent conductive films (ITO, indium tin oxide containing 2-20 wt% zinc oxide) It uses lamination of indium tin oxide containing indium and silicon, zinc oxide (ZnO, etc.) It's good to do that.

[0157] 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. It should be noted 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 2 and a light-emitting element having other structures. The light emitting element may include both a light emitting element and a light emitting element.

[0158] Furthermore, by bonding the sealing substrate 604 to the element substrate 610 with a sealing material 605, A space 607 surrounded by an element substrate 610, a sealing substrate 604, and a sealing material 605 contains a light-emitting element. 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 influence of moisture. This is a preferable configuration because it can suppress deterioration due to the temperature change.

[0159] It is preferable to use epoxy resin or glass frit for the sealing material 605. In addition, it is desirable that these materials be as impermeable to moisture and oxygen as possible. The sealing substrate 604 may be made of a glass substrate, a quartz substrate, or a FRP (Fibre Reinforced Plastic) substrate. Glass-Reinforced Plastics), PVF (Polyvinyl Fluoride ), a plastic substrate made of polyester, acrylic, or the like can be used.

[0160] As described above, a light-emitting element manufactured using the light-emitting element described in Embodiment 1 or 2 A light emitting device having such a structure can be obtained.

[0161] 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 good characteristics can be obtained. The light-emitting element described in Embodiment 1 or 2 is a light-emitting element with high luminous efficiency and low power consumption. Furthermore, the light emitting device can be easily mass-produced and inexpensive. A light emitting device can be provided.

[0162] In FIG. 3, a light emitting element that emits white light is formed, and a colored layer (color filter) or the like is provided. FIG. 3(A) shows an example of a full-color light-emitting device. 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, The driving circuit unit 1041, the first electrodes 1024W, 1024R, 1024G, 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.

[0163] 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 on which a colored layer and a black layer are provided may be further provided. 1033 is aligned and fixed to the substrate 1001. The colored layer and the black layer are 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 color layers of each color, and light-emitting layers that 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. Images can be expressed using pixels.

[0164] In FIG. 3(B), 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 As shown in the figure, the colored layer is provided between the substrate 1001 and the sealing substrate 1031. is also good.

[0165] In the light emitting device described above, light is taken in from the substrate 1001 side on which the TFT is formed. The light emitting device has a bottom emission structure, but the light is emitted from the sealing substrate 1031 side. It may also be a light emitting device with a structure where light is extracted (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 TFT and the anode of the light-emitting element is formed, the bottom 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 1022 is formed to cover the insulating film 1022. This insulating film may also have a role of planarization. The insulating film 1037 is formed using the same material as the second interlayer insulating film, as well as other known materials. It is possible.

[0166] The first electrodes 1024W, 1024R, 1024G, and 1024B of the light-emitting element are positive electrodes. The cathode is also used as the top-emission type light-emitting diode, as shown in Figure 4. 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 obtain white light emission.

[0167] 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) may be provided. The blue colored layer 1034G and the black layer (black matrix) are overcoated. The sealing substrate 1031 may be covered with a coating layer 1036. A substrate will be used.

[0168] Although an example of full-color display using four colors, red, green, blue, and white, is shown here, the present invention is not particularly limited to this. Instead, a full color display using three colors, red, green, and blue, may be used.

[0169] 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 good characteristics can be obtained. The light-emitting element described in Embodiment 1 or 2 is a light-emitting element with high luminous efficiency and low power consumption. Furthermore, the light emitting device can be easily mass-produced and inexpensive. A light emitting device can be provided.

[0170] Up to this point, we have explained about active matrix type light emitting devices. A sub-matrix light-emitting device will be described. 5A is a perspective view of the light-emitting device, and FIG. 5B is a cross-sectional view of FIG. 5A cut along the XY line. 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 sidewalls of the partition layer 954 become thinner as they approach the substrate surface. That is, the cross section of the partition layer 954 in the short side direction has a slope such that the gap between the partition layers 954 becomes narrower. The trapezoidal shape has a base (which faces in the same direction as the surface 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 come into contact with the insulating layer 953) ) is shorter than the distance . ) 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 The light-emitting element having high emission efficiency shown in Embodiment 1 or 2 is used, and power consumption is low. Furthermore, 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.

[0171] The light emitting device described above has a large number of minute light emitting elements arranged in a matrix. Since it is possible to control the light, it can be suitably used as a display device for displaying images. It is an optical device.

[0172] This embodiment mode can be freely combined with other embodiment modes.

[0173] (Fourth embodiment) 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. 6(A) is a This is a cross-sectional view taken along line ef in FIG. 6(B).

[0174] The lighting device of this embodiment is a first light-transmitting substrate 400 that serves as a support. The first electrode 401 is formed on the substrate 1. The first electrode 401 is the same as the first electrode 1 in the first embodiment. When light is extracted from the first electrode 401 side, the first electrode 401 is a light-transmitting electrode. It is made of a material having the properties.

[0175] A pad 412 for supplying a voltage to the second electrode 404 is formed on the substrate 400 .

[0176] 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 For details about these configurations, please refer to the relevant descriptions.

[0177] 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, voltage is supplied.

[0178] As described above, the 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 with high luminous efficiency. Therefore, the lighting device in this embodiment can be a lighting device with low power consumption.

[0179] 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 bonding and sealing the sealing materials 405 and 406. In addition, the inner sealing material 406 (not shown in FIG. 6(B)) may contain a desiccant. This allows the material to absorb moisture, leading to improved reliability. .

[0180] In addition, a part of the pad 412 and the first electrode 401 is extended outside the sealing materials 405 and 406. By providing a terminal on the converter, it can be used as an external input terminal. An IC chip 420 incorporating the above may be provided.

[0181] As described above, the lighting device according to the present embodiment uses the EL element according to the first or second embodiment. Since the light-emitting element is included, the lighting device can consume less power. This allows the lighting device to be driven at a low voltage and is also inexpensive. do.

[0182] (Embodiment 5) In this embodiment, a light-emitting element including the light-emitting element described in Embodiment 1 or 2 is Examples of electronic devices will be described. The light-emitting element described in Embodiment 1 or 2 This light-emitting element has high efficiency and reduced power consumption. The electronic device may be an electronic device having a light-emitting section with reduced power consumption. The light-emitting element described in Embodiment 1 or 2 is a light-emitting element having a small number of film layers. Therefore, it is possible to make the electronic device inexpensive.

[0183] As an electronic device to which the light-emitting element is applied, for example, a television set (television or television) (also called revision receivers), monitors for computers, digital cameras, digital Video cameras, digital photo frames, mobile phones (also called mobile phones or mobile phone devices) ), portable game machines, personal digital assistants, audio playback devices, large game machines such as pachinko machines, etc. Specific examples of these electronic devices are listed below.

[0184] 7A shows an example of a television device. The television device includes a housing 710 A display unit 7103 is built into the housing 1. In this case, a stand 7105 is used to hold the housing The display unit 7103 can display images. The display portion 7103 includes the light-emitting element described in Embodiment 1 or 2. The light emitting elements are arranged in a box shape. The light emitting elements are light emitting elements with good light emitting efficiency. Furthermore, it is possible to provide a light emitting element with a low driving voltage. Therefore, the display unit 7 made up of the light emitting element can be The television device having the 103 can be a television device with reduced power consumption. It is also possible to provide a television device with a low driving voltage. This makes it possible to provide a highly user-friendly television device.

[0185] The television device can be operated using the operation switches on the housing 7101 or a separate remote control. This can be done by the remote control device 7110. This allows you to control the channel and volume, and the image displayed on the display unit 7103 In addition, the remote control operation device 7110 can be operated. A display portion 7107 for displaying information output from the

[0186] The television device is assumed to be equipped with a receiver, modem, etc. It can receive television broadcasts and can also communicate by wire or wirelessly via a modem. By connecting to a network, you can send and receive data in one direction (sender to receiver) or two directions (sender to receiver). It is also possible to communicate information between the recipient and the receiver, or between receivers themselves.

[0187] FIG. 7(B1) shows a computer, which includes a main body 7201, a housing 7202, a display portion 7203, and a keyboard. keyboard 7204, external connection port 7205, pointing device 7206, etc. This computer is similar to the one described in the second or third embodiment. The display unit 7203 is fabricated by arranging optical elements in a matrix. The computer of B1) may be in the form shown in FIG. 7(B2). The computer may have a second keyboard 7204 instead of a pointing device 7206. A display portion 7210 is provided. The second display portion 7210 is a touch panel type. By operating the input display 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 input but also for other purposes. It is also possible to display other images. The two screens are connected by a hinge, so you can easily store or transport the screens. This also prevents damage and other problems from occurring. The data is displayed by arranging the light-emitting elements described in Embodiment 1 or 2 in a matrix. The light-emitting element is manufactured by using the light-emitting element in the part 7203. Therefore, it is possible to display a computer having a display portion 7203 including the light-emitting element. The computer may be a reduced power computer.

[0188] FIG. 7C shows a portable gaming machine, which is composed of two housings, a housing 7301 and a housing 7302. The housing 7301 is connected by a connecting portion 7303 so as to be openable and closable. A display unit manufactured by arranging the light-emitting elements described in embodiment 1 or embodiment 2 in a matrix. A display unit 7305 is incorporated in the housing 7302. The portable gaming machine shown in 7(C) also has a speaker unit 7306, a recording medium insertion unit 7307, , LED lamp 7308, input means (operation keys 7309, connection terminal 7310, sensor 73 11 (force, displacement, position, velocity, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical Chemical substances, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration , including the function of measuring odor or infrared rays), microphone 7312) Of course, the configuration of the portable gaming machine is not limited to the above, and at least the display unit 73 The display portion 7304 and / or the display portion 7305 may be It is sufficient to use a display unit made by arranging light-emitting elements in a matrix, and other accessories The portable gaming machine shown in FIG. 7(C) can be configured with a recording medium. It has the function of reading out the programs or data stored in the device and displaying them on the display, and it also has the function of reading out the programs or data stored in the device and displaying them on the display, It has the function of sharing information with the mobile gaming machine by wireless communication. The functions of the belt-type gaming machine are not limited to these, and the machine may have a variety of functions. A portable game machine having such a display portion 7304 has a light-emitting element used in the display portion 7304. Since the device has good luminous efficiency, it is a portable gaming machine with reduced power consumption. In addition, the light-emitting element used in the display portion 7304 can be driven at a low driving voltage. Therefore, it is possible to make a portable gaming machine with a low driving voltage. Since the light emitting element used in the portion 7304 is a light emitting element with a long life, it is highly reliable. It can be a portable gaming machine.

[0189] 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, operation buttons 7403, an external connection port 7404, a speaker 74 05, a microphone 7406, etc. The mobile phone 7400 is the same as that of the first embodiment. The display portion 7402 is manufactured by arranging the light-emitting elements described in Embodiment 2 in a matrix. The light-emitting element can have high luminous efficiency. It is possible to provide a light emitting element with a low driving voltage. Therefore, a mobile phone having a display portion 7402 including the light-emitting element can be used. The mobile phone can be a mobile phone with reduced power consumption. It is possible to make a telephone. It is also possible to make a highly reliable mobile phone. .

[0190] The mobile phone shown in FIG. 7D allows a user 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 operations can be performed by touching the display portion 7402 with a finger or the like.

[0191] The screen of the display unit 7402 has three main modes. The first is a display mode that mainly displays images. The first mode is a display mode, and the second mode is an input mode that mainly inputs information such as characters. This is a display + input mode that combines two modes: display mode and input mode.

[0192] For example, when making a call or creating an email, the display unit 7402 is used to input characters. This is the main character input mode, and you can input characters displayed on the screen. It is preferable to display a keyboard or number buttons on most of the screen of the display portion 7402. Desirable.

[0193] In addition, the mobile phone may have a sensor for detecting tilt such as a gyro or acceleration sensor inside. By providing a display device, the orientation of the mobile phone (portrait or landscape) can be determined and the image of the display portion 7402 can be displayed. The surface display can be switched automatically.

[0194] The screen mode can be switched by touching the display portion 7402 or by operating the housing 7401. This is done by operating the button 7403. Also, depending on the type of image displayed on the display unit 7402, For example, if the image signal to be displayed on the display unit is a video signal, If it is data, the display mode is switched to, and if it is text data, the input mode is switched to.

[0195] In the input mode, the optical sensor of the display unit 7402 detects a signal and displays it. If there is no input by touch operation on the part 7402 for a certain period of time, the screen mode is changed to the input mode. Alternatively, the display mode may be switched from the normal mode to the display mode.

[0196] The display portion 7402 can also function as an image sensor. By touching the device with your palm or fingers and capturing an image of your palm print or fingerprint, you can authenticate your identity. In addition, a backlight that emits near-infrared light to the display unit or a sensing light that emits near-infrared light By using a source, it is also possible to image finger veins, palm veins, etc.

[0197] Note that the structure described in this embodiment mode may be obtained by appropriately combining the structures described in any of Embodiment Modes 1 to 4. They can be used in combination.

[0198] 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. Therefore, electronic devices can be obtained.

[0199] FIG. 8 shows a liquid crystal display device 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, a battery 903, and a display panel 904. The LCD panel 902 includes a backlight unit 903 and a housing 904, and the LCD panel 902 includes a driver IC 905 and a In addition, the backlight unit 903 is connected to the backlight unit 903. 2 is used, and a current is supplied through a terminal 906.

[0200] The light-emitting element described in Embodiment 1 or 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 element described above, it is possible to fabricate a surface-emitting lighting device, and it is also possible to make it large-area. This allows for a larger backlight area, which in turn allows for a larger LCD display area. Furthermore, the light emitting device to which the light emitting element described in Embodiment 2 is applied is thinner than the conventional one. Since the size can be reduced, the display device can be made thinner.

[0201] FIG. 9 shows a configuration in which the light-emitting element described in Embodiment 1 or 2 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 the light source 2002, the lighting device described in the fourth embodiment is used.

[0202] FIG. 10 shows an indoor lighting device 300 using the light-emitting element described in Embodiment 1 or 2. The light-emitting element described in Embodiment 1 or 2 has a low power consumption. Since the light-emitting element has a reduced power consumption, the lighting device can have a reduced power consumption. In addition, the light-emitting element described in Embodiment 1 or 2 can be made large in area; In addition, the present invention can be used as a lighting device for various applications. The light-emitting element is thin, and therefore can be used as a thin lighting device.

[0203] The light emitting element according to the first or second embodiment is used for a windshield or a dashboard of an automobile. FIG. 11 shows the light-emitting element described in Embodiment 2 mounted on a vehicle. The display area 5000 is a display area used on a windshield or dashboard. 5005 is a display provided using the light-emitting element described in Embodiment 1 or 2. do.

[0204] The display area 5000 and the display area 5001 are provided on the windshield of the automobile. A display device incorporating the light-emitting element according to Embodiment 1 or 2. 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 in which the other side can be seen through. If the display is see-through, it can be installed on the windshield of a car. It can be installed without obstructing the view. When 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.

[0205] The display area 5002 is the display area described in the first or second embodiment provided in the pillar portion. The display device is equipped with a photoelectric element. The display area 5002 is provided with an image pickup means mounted on the vehicle body. By projecting these images, it is possible to complement the view obstructed 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 increase safety. By projecting images to complement the invisible parts, This allows you to check for safety more naturally and without any discomfort.

[0206] The display area 5004 and the display area 5005 are used to display navigation information, a speedometer, and a tachometer. Provides various information such as meter, mileage, fuel level, gear status, air conditioning settings, etc. The display items and layout can be changed as needed to suit the user's preferences. This information can also be provided in display areas 5000 to 5003. In addition, the display areas 5000 to 5005 can be used as lighting devices. It is also possible.

[0207] The light-emitting element described in Embodiment 1 or 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 device is less likely to break and can be used comfortably, it is possible to use the device according to the first or second embodiment. A light-emitting device or a lighting device using the light-emitting element described in It can be suitably used as such.

[0208] Figures 12(A) and 12(B) show an example of a foldable tablet terminal. 2(A) shows the tablet terminal in an open state, and the tablet terminal includes a housing 9630, a display unit 9631a, and a , display unit 9631b, display mode changeover switch 9034, power switch 9035, A power mode changeover switch 9036, a fastener 9033, and an operation switch 9038 are included. The tablet terminal is equipped with the light-emitting element described in the first embodiment or the second embodiment. By using the light-emitting device having the above configuration in one or both of the display portion 9631a and the display portion 9631b, It is produced.

[0209] A part of the display unit 9631a can be used as a touch panel area 9632a. By touching the operation keys 9037, data can be input. In 1a, for 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 displayed as a keyboard button to serve as a touch panel, and the display part 9631b is displayed. It can be used as a screen.

[0210] In addition, in the display unit 9631b, as in the display unit 9631a, The part 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.

[0211] In addition, when touching the touch panel area 9632a and the touch panel area 9632b at the same time, You can also input the character.

[0212] 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 an external switch that is detected by a light sensor built into the tablet terminal. The display brightness can be optimized according to the amount of light. In addition to sensors, other detection devices such as gyros and acceleration sensors that detect tilt are also available. may be incorporated.

[0213] 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 display quality may also differ. For example, one display panel may be able to display a higher resolution image than the other. It may also be used as a rule.

[0214] FIG. 12(B) 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 9636 is provided. As an example of 4, a configuration having a battery 9635 and a DC-DC converter 9636 It shows.

[0215] In addition, since the tablet device can be folded in half, when not in use, the case 9630 is closed. 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 for long-term use.

[0216] 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 The function to display information on the display unit, and the function to input or edit the information displayed on the display unit. It has input functions, functions to control processing using various software (programs), etc. It is possible.

[0217] The solar cell 9633 attached to the surface of the tablet terminal supplies power to the touch panel. The solar cell 9633 can be supplied to a display unit, a video signal processor, or the like. The battery 9635 can be efficiently charged by installing it on one or both sides of the housing 9630. This is preferable because it is possible to configure the device to perform the above.

[0218] The configuration and operation of the charge / discharge control circuit 9634 shown in FIG. 12(B) are shown in FIG. A block diagram is shown in Fig. 12(C) and will be explained. 635, DC-DC converter 9636, converter 9638, switches SW1 to SW3 , the display unit 9631, the battery 9635, the 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.

[0219] First, an example of operation when 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 increases or decreases the voltage to the voltage required for the display unit 9631. When not displaying on the display unit 9631, turn SW1 off and SW2 on. The configuration may be such that the battery 9635 is charged.

[0220] 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 wireless (contactless) 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.

[0221] Furthermore, if the display unit 9631 is provided, a tablet terminal having the shape shown in FIG. Not limited to. [Example]

[0222] In this example, light-emitting elements (light-emitting elements 1 to 3) of one embodiment of the present invention will be described. The chemical formulas of the materials used in this example are shown below. The light-emitting layer is made up of two light-emitting layers (first light-emitting layer and second light-emitting layer) formed by The first emitting layer emits light from an exciplex, and the second emitting layer emits light from a phosphorescent compound. It has the configuration described in the first embodiment for obtaining light emission.

[0223] [ka]

[0224] A method for fabricating the light-emitting elements 1 to 3 of this example will be described below.

[0225] (Method for fabricating 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 film deposition method. The area was set to 2 mm x 2 mm. Here, the first electrode 101 functions as an anode of the light-emitting element. It is an electrode that

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

[0227] Then, 10 -4 The substrate is placed in a vacuum deposition apparatus whose inside pressure has been reduced to about 100 Pa. After vacuum baking at 170°C for 30 minutes in the heating chamber of the device, the substrate is left for about 30 minutes. Allow to cool.

[0228] Next, the first electrode 101 is formed so that the surface on which the first electrode 101 is formed faces downward. The substrate was fixed to a substrate holder installed in a vacuum deposition apparatus, and -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 vapor deposition method using resistance heating. 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) By co-evaporating DBT3P-II and molybdenum oxide (VI), The hole injection layer 111 was formed. Its thickness was set to 20 nm, and it was made of DBT3P-II and molybdenum oxide. The weight ratio of DBT3P-II to molybdenum oxide was adjusted to 4:2 (= DBT3P-II: molybdenum oxide). The co-evaporation method is a method of simultaneously depositing layers from multiple evaporation sources in a single processing chamber. It is a method of wearing.

[0229] Next, 4-phenyl-4′-( 9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP) for 20 The hole transport layer 112 was formed by depositing the film so as to have a thickness of 100 nm.

[0230] Furthermore, on the hole transport layer 112, 2-[3-(dibenzo- Thiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBT PDBq-II) and N,N'-bis(9-phenyl-9H) represented by the above structural formula (iv). -carbazol-3-yl)-N,N'-diphenyl-spiro-9,9'-bifluorene 2,7-diamine (abbreviation: PCA2SF) in a weight ratio of 0.8:0.2 (=2mDB TPDBq-II:PCA2SF) was co-evaporated to a thickness of 20 nm to form the first light-emitting layer 113 After preparing a, 2mDBTPDBq-II, PCA2SF, and the compound represented by the above structural formula (v) were Bis(2,3,5-triphenylpyrazinato)(dipivaloylmethanato)iridium( III) (abbreviation: [Ir(tppr)2(dpm)]) in a weight ratio of 0.8:0.2: 0.025(=2mDBTPDBq-II:PCA2SF:[Ir(tppr)2(dp m)]) to form the second light-emitting layer 113b. The light-emitting layer 113 was formed by the above reaction. Forms the body.

[0231] Thereafter, 2mDBTPDBq-II was formed on the light-emitting layer 113 to a thickness of 20 nm. Furthermore, bathophenanthroline (abbreviation: BPhen) represented by the above structural formula (v) is The electron transport layer 114 was formed by depositing the film so as to have a thickness of 0 nm.

[0232] After the electron transport layer 114 is formed, lithium fluoride (LiF) is deposited to a thickness of 1 nm. Then, an electron injection layer 115 is formed, and finally, a second electrode 116 is formed to function as a cathode. 02, aluminum was evaporated to a film thickness of 200 nm. Light-emitting device 1 was fabricated.

[0233] In the above-described deposition process, the deposition was all carried out by resistance heating.

[0234] (Method for manufacturing light-emitting element 2) The light-emitting element 2 has the second light-emitting layer 113b of the light-emitting element 1 formed of 2mDBTPDBq-I I and [Ir(tppr)(dpm)] were mixed in a weight ratio of 1:0.025 (=2mDBTP DBq-II: [Ir(tppr)2(dpm)]) was co-evaporated to 20 nm. The other components were the same as those of the light-emitting element 1 and were fabricated by the same method.

[0235] (Method for manufacturing light-emitting element 3) The light-emitting element 3 is the same as the light-emitting element 1 except that the light-emitting layer 113 is made of 2mDBTPDBq-II and the above-mentioned structure. 2-[N-(9-phenylcarbazol-3-yl)-N-phenyl]- phenylamino]spiro-9,9'-bifluorene (abbreviation: PCASF) in a weight ratio of 0. 20 nm of the film was co-evaporated to a ratio of 8:0.2 (=2mDBTPDBq-II:PCASF). After the first light-emitting layer 113a was formed, 2mDBTPDBq-II, PCASF, and [Ir (tppr)2(dpm)] in a weight ratio of 0.8:0.2:0.025 (=2mDBT PDBq-II:PCASF:[Ir(tppr)2(dpm)], 20n The second light-emitting layer 113b was formed by co-evaporating the light-emitting element 113m. Light-emitting device 3 was fabricated by replacing PCA2SF in light-emitting device 1 with PCASF. The other components were the same as those of the light-emitting element 1 and were fabricated using the same method. q-II and PCASF form an exciplex.

[0236] The light-emitting elements 1 to 3 were placed in a glove box with a nitrogen atmosphere. The process of sealing with a glass substrate to prevent exposure to air (applying a sealant around the element, After UV treatment and heat treatment at 80°C for 1 hour during sealing, the reliability of these light-emitting devices was evaluated. The measurements were carried out at room temperature (an atmosphere maintained at 25°C).

[0237] FIG. 13 shows the current density-luminance characteristics of Light-emitting Element 1, FIG. 14 shows the luminance-current efficiency characteristics, and FIG. The luminance characteristics are shown in Figure 15, the luminance-external quantum efficiency characteristics are shown in Figure 16, and the emission spectrum is shown in Figure 17. .

[0238] FIG. 18 shows current density-luminance characteristics of Light-emitting Element 2, and FIG. 19 shows luminance-current efficiency characteristics. The voltage-luminance characteristics are shown in Fig. 20, the luminance-external quantum efficiency characteristics are shown in Fig. 21, and the emission spectrum is shown in Fig. 2 Shown in 2.

[0239] FIG. 23 shows the current density-luminance characteristics of Light-emitting Element 3, FIG. 24 shows the luminance-current efficiency characteristics, and FIG. 25 shows the voltage-luminance characteristics. The luminance characteristics are shown in Figure 25, the luminance-external quantum efficiency characteristics are shown in Figure 26, and the emission spectrum is shown in Figure 27. .

[0240] As described above, all of the light-emitting elements 1 to 3 have a light emitting efficiency of 1000 cd / m 2 Current efficiency around It was found that the device exhibited excellent luminous efficiency of 20 cd / A or more and external quantum efficiency of 10% or more.

[0241] The emission spectrum also shows red emission from [Ir(tppr)2(dpm)] and Green light emission (shoulder around 550 nm) originating from the exciplex was observed, and the first light-emitting layer 113a and It can be seen that light is emitted from both the light-emitting layers 113b. [Example]

[0242] In this example, a light-emitting element (light-emitting element 4) of one embodiment of the present invention will be described. The chemical formulas of the materials used are shown below. The light-emitting element 4 has two light-emitting layers ( The first light-emitting layer is an exciplex. The light emitted from the fluorescent compound is transferred from the first light-emitting layer to the phosphorescent compound. The structure has the same configuration as in the first embodiment, in which light emission from the

[0243] [ka]

[0244] The method for fabricating the light-emitting device 4 of this example will be described below.

[0245] (Method for manufacturing light-emitting element 4) First, indium tin oxide containing silicon oxide (ITSO) was sputtered onto a glass substrate. The first electrode 101 was formed by a film deposition method. The area was set to 2 mm x 2 mm. Here, the first electrode 101 functions as an anode of the light-emitting element. It is an electrode that

[0246] Next, as a pretreatment for forming a light emitting element on the substrate, the substrate surface was washed with water and After baking at ℃ for 1 hour, UV ozone treatment was performed for 370 seconds.

[0247] Then, 10 -4 The substrate is placed in a vacuum deposition apparatus whose inside pressure has been reduced to about 100 Pa. After vacuum baking at 170°C for 30 minutes in the heating chamber of the device, the substrate is left for about 30 minutes. Allow to cool.

[0248] 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 -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 vapor deposition method using resistance heating. 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) By co-evaporating DBT3P-II and molybdenum oxide (VI), The hole injection layer 111 was formed. Its thickness was set to 40 nm, and it was made of DBT3P-II and molybdenum oxide. The weight ratio of DBT3P-II to molybdenum oxide was adjusted to 4:2 (= DBT3P-II: molybdenum oxide). The co-evaporation method is a method of simultaneously depositing layers from multiple evaporation sources in a single processing chamber. It is a method of wearing.

[0249] Next, on the hole injection layer 111, 4,4'-di(1- naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)triphenyl A hole transport layer 112 was formed by depositing a film of PCBNBB (abbreviation: PCBNBB) to a thickness of 20 nm. Formed.

[0250] Furthermore, on the hole transport layer 112, 2-[3′-(dibenzo-p-(2-methyl-2-phenyl)-2-(2-methyl-2-phenyl)-2-(2-phenyl ...phenyl-2-phenyl)-2-(2-phenyl-2 Thiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation : 2mDBTBPDBq-II), PCBNBB, and the bis(dichlorophenyl)-2-propanol represented by the above structural formula (x) [2-(6-tert-butyl-4-pyrimidinyl-κN3)phenyl-κC](2,4 -pentanedionato-κ 2 O,O')iridium(III) (abbreviation: [Ir(tBupp m)2(acac)]) in a weight ratio of 0.8:0.2:0.05 (=2mDBTBPDB q-II: PCBNBB: [Ir(tBuppm)2(acac)]) After co-evaporation of 2mDBTBPDBq-II, PCBNBB, and [Ir(tppr )2(dpm)] and 0.9:0.1:0.05 (=2mDBTBPDBq-I I: PCBNBB: [Ir(tppr)2(dpm)]) was co-evaporated to a thickness of 5 nm. After forming the second light-emitting layer 113b, 2mDBTBPDBq-II, PCBNBB, N,N'-bis(3-methylphenyl)-N ... [3-(9-phenyl-9H-fluoren-9-yl)phenyl]-pyrene-1,6-di amine (abbreviation: 1,6mMemFLPAPrn) in a weight ratio of 0.3:0.7:0.05 The first light-emitting layer 113a was formed by co-evaporation to a thickness of 25 nm. 3 was formed.

[0251] 2mDBTBPDBq-II and PCBNBB form an exciplex. The spectra are the emission spectrum of the film of 2mDBTBPDBq-II alone, PC Emission spectra of the film of BNBB alone and the film of 2mDBTBPDBq-II and PCBNBB As shown in Figure 34, the emission spectrum of the co-evaporated film is The emission spectrum of the film co-evaporated with PCBNBB is different from that of either of the films alone. The emission spectrum of the film itself appears in a longer wavelength region than that of the film itself. The emission spectrum is present, which is due to the presence of 2mDBTBPDBq-II and PCBNB This suggests that an exciplex is formed by B.

[0252] Thereafter, 2mDBTBPDBq-II was formed on the light-emitting layer 113 to a thickness of 15 nm. Furthermore, bathophenanthroline (abbreviation: BPhen) represented by the above structural formula (v) The electron transport layer 114 was formed by depositing the film to a thickness of 15 nm.

[0253] After the electron transport layer 114 is formed, lithium fluoride (LiF) is deposited to a thickness of 1 nm. Then, an electron injection layer 115 is formed, and finally, a second electrode 116 is formed to function as a cathode. 02, aluminum was evaporated to a film thickness of 200 nm. Light-emitting device 4 was fabricated.

[0254] In the above-described deposition process, the deposition was all carried out by resistance heating.

[0255] The light emitting element 4 is placed in a glove box with a nitrogen atmosphere so that the light emitting element is not exposed to the atmosphere. The process of sealing the device with a glass substrate (applying a sealant around the device and applying UV light during sealing) After the device was subjected to a thermal treatment at 80°C for 1 hour, the reliability of the device was measured. The measurements were carried out at room temperature (an atmosphere maintained at 25°C).

[0256] FIG. 28 shows the current density-luminance characteristics of Light-emitting Element 4, FIG. 29 shows the luminance-current efficiency characteristics, and FIG. The luminance characteristics are shown in Figure 30, the luminance-external quantum efficiency characteristics are shown in Figure 31, and the emission spectrum is shown in Figure 32. .

[0257] As described above, the light emitting element 4 has a luminance of 1000 cd / m 2 Current efficiency of 20 cd / A or more near It was found that the device exhibited good luminous efficiency with a quantum efficiency of 10% or more.

[0258] In addition, the emission spectrum shows red emission from [Ir(tppr)2(dpm)] and [ Green emission from Ir(tBuppm)2(acac)] and 1,6mMemFLPAPr From this, it was found that the first light-emitting layer 113a and the second light-emitting layer 113b are Light emission was obtained from both the first light-emitting layer 113a and the second light-emitting layer 113b. It can be seen that good device characteristics can be obtained even in light-emitting devices using fluorescent materials as .

[0259] Next, the initial brightness was set to 3000 cd / m 2 The light-emitting element 4 is driven under the condition of a constant current density. The results of the reliability test are shown in Figure 33. In Figure 33, the initial luminance was set to 100%. The results show that the light-emitting element 4 maintained the same normalized luminance as the initial value even after 350 hours. It maintains 86% of its original brightness and exhibits little decrease in brightness over time, making it a highly reliable light source. It was found to be an optical element. [Explanation of symbols]

[0260] 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 114 Electron transport layer 115 Electron injection layer 400 boards 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 TFT 612 Current Control TFT 613 First electrode 614 Insulators 616 EL layer 617 Second electrode 618 Light-emitting element 623 n-channel TFT 624 p-channel TFT 625 Dry material 901 Case 902 Liquid crystal layer 903 Backlight Unit 904 Case 905 Driver IC 906 terminal 951 PCB 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 color layer 1034B Blue color 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 Housing 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 Housing 7302 Housing 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 Housing 7402 Display section 7403 Operation button 7404 External connection port 7405 Speaker 7406 Microphone 7400 mobile phone 9033 Fasteners 9034 Switch 9035 Power Switch 9036 Switch 9037 Operation Key 9038 Operation switch 9630 chassis 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 9638 Converter 9639 Button

Claims

1. a first light-emitting layer and a second light-emitting layer between a pair of electrodes; the first light-emitting layer and the second light-emitting layer are in contact with each other, the first light-emitting layer includes at least a first organic compound and a second organic compound; the second light-emitting layer includes at least a third organic compound, a fourth organic compound, and a phosphorescent material; the first organic compound is a compound having an electron transport property, a triplet excitation level of the first organic compound is higher than a triplet excitation level of the phosphorescent material; the second organic compound is a compound having a hole transport property, a triplet excitation level of the second organic compound is higher than a triplet excitation level of the phosphorescent material; the first organic compound and the second organic compound are a combination that forms a first exciplex, the third organic compound and the fourth organic compound are a combination that forms a second exciplex, the lowest energy absorption band in the absorption spectrum of the phosphorescent material overlaps with the emission spectrum of the second exciplex; the emission from the first light-emitting layer has an emission peak on the shorter wavelength side than the emission from the second light-emitting layer; (However, this does not include the case where the first organic compound and the second organic compound are a combination of 4,4',4"-tris(N-carbazolyl)-triphenylamine (TCTA) and 1,3,5-tris(2-N-phenylbenzimidazolyl)benzene (TPBi), and the third organic compound and the fourth organic compound are a combination of TCTA and TPBi.) Light-emitting element.

2. a first light-emitting layer and a second light-emitting layer between a pair of electrodes; the first light-emitting layer and the second light-emitting layer are in contact with each other, the first light-emitting layer includes at least a first organic compound and a second organic compound; the second light-emitting layer includes at least a third organic compound, a fourth organic compound, and a phosphorescent material; the first organic compound is a heterocyclic compound, a triplet excitation level of the first organic compound is higher than a triplet excitation level of the phosphorescent material; the second organic compound is a compound having an aromatic amine skeleton or a compound having a carbazole skeleton, a triplet excitation level of the second organic compound is higher than a triplet excitation level of the phosphorescent material; the first organic compound and the second organic compound are a combination that forms a first exciplex, the third organic compound and the fourth organic compound are a combination that forms a second exciplex, the lowest energy absorption band in the absorption spectrum of the phosphorescent material overlaps with the emission spectrum of the second exciplex; the emission from the first light-emitting layer has an emission peak on the shorter wavelength side than the emission from the second light-emitting layer; (However, this does not include the case where the first organic compound and the second organic compound are a combination of 4,4',4"-tris(N-carbazolyl)-triphenylamine (TCTA) and 1,3,5-tris(2-N-phenylbenzimidazolyl)benzene (TPBi), and the third organic compound and the fourth organic compound are a combination of TCTA and TPBi.) Light-emitting element.

3. a first light-emitting layer and a second light-emitting layer between a pair of electrodes; the first light-emitting layer and the second light-emitting layer are in contact with each other, the first light-emitting layer includes at least a first organic compound and a second organic compound; the second light-emitting layer includes at least a third organic compound, a fourth organic compound, and a phosphorescent material; the first organic compound is a compound having an electron transport property, a triplet excitation level of the first organic compound is higher than a triplet excitation level of the phosphorescent material; the second organic compound is a compound having a hole transport property, a triplet excitation level of the second organic compound is higher than a triplet excitation level of the phosphorescent material; the first organic compound and the second organic compound are a combination that forms a first exciplex, the third organic compound and the fourth organic compound are a combination that forms a second exciplex, the lowest energy absorption band in the absorption spectrum of the phosphorescent material overlaps with the emission spectrum of the second exciplex; the light emitted from the first light-emitting layer is green; the light emitted from the second light-emitting layer is red; (However, this does not include the case where the first organic compound and the second organic compound are a combination of 4,4',4"-tris(N-carbazolyl)-triphenylamine (TCTA) and 1,3,5-tris(2-N-phenylbenzimidazolyl)benzene (TPBi), and the third organic compound and the fourth organic compound are a combination of TCTA and TPBi.) Light-emitting element.

4. a first light-emitting layer and a second light-emitting layer between a pair of electrodes; the first light-emitting layer and the second light-emitting layer are in contact with each other, the first light-emitting layer includes at least a first organic compound and a second organic compound; the second light-emitting layer includes at least a third organic compound, a fourth organic compound, and a phosphorescent material; the first organic compound is a heterocyclic compound, a triplet excitation level of the first organic compound is higher than a triplet excitation level of the phosphorescent material; the second organic compound is a compound having an aromatic amine skeleton or a compound having a carbazole skeleton, a triplet excitation level of the second organic compound is higher than a triplet excitation level of the phosphorescent material; the first organic compound and the second organic compound are a combination that forms a first exciplex, the third organic compound and the fourth organic compound are a combination that forms a second exciplex, the lowest energy absorption band in the absorption spectrum of the phosphorescent material overlaps with the emission spectrum of the second exciplex; the light emitted from the first light-emitting layer is green; the light emitted from the second light-emitting layer is red; (However, this does not include the case where the first organic compound and the second organic compound are a combination of 4,4',4"-tris(N-carbazolyl)-triphenylamine (TCTA) and 1,3,5-tris(2-N-phenylbenzimidazolyl)benzene (TPBi), and the third organic compound and the fourth organic compound are a combination of TCTA and TPBi.) Light-emitting element.

5. a first light-emitting layer and a second light-emitting layer between a pair of electrodes; the first light-emitting layer and the second light-emitting layer are in contact with each other, the first light-emitting layer includes at least a first organic compound and a second organic compound; the second light-emitting layer includes at least a third organic compound, a fourth organic compound, and a phosphorescent material; the first organic compound is a compound having an electron transport property, a triplet excitation level of the first organic compound is higher than a triplet excitation level of the phosphorescent material; the second organic compound is a compound having a hole transport property, a triplet excitation level of the second organic compound is higher than a triplet excitation level of the phosphorescent material; the first organic compound and the second organic compound are a combination that forms a first exciplex, the third organic compound and the fourth organic compound are a combination that forms a second exciplex, the lowest energy absorption band in the absorption spectrum of the phosphorescent material overlaps with the emission spectrum of the second exciplex; the light emitted from the first light-emitting layer has an emission peak in the range of 500 to 600 nm; the light emitted from the second light-emitting layer has an emission peak in the range of 600 to 700 nm; (However, this does not include the case where the first organic compound and the second organic compound are a combination of 4,4',4"-tris(N-carbazolyl)-triphenylamine (TCTA) and 1,3,5-tris(2-N-phenylbenzimidazolyl)benzene (TPBi), and the third organic compound and the fourth organic compound are a combination of TCTA and TPBi.) Light-emitting element.

6. a first light-emitting layer and a second light-emitting layer between a pair of electrodes; the first light-emitting layer and the second light-emitting layer are in contact with each other, the first light-emitting layer includes at least a first organic compound and a second organic compound; the second light-emitting layer includes at least a third organic compound, a fourth organic compound, and a phosphorescent material; the first organic compound is a heterocyclic compound, a triplet excitation level of the first organic compound is higher than a triplet excitation level of the phosphorescent material; the second organic compound is a compound having an aromatic amine skeleton or a compound having a carbazole skeleton, a triplet excitation level of the second organic compound is higher than a triplet excitation level of the phosphorescent material; the first organic compound and the second organic compound are a combination that forms a first exciplex, the third organic compound and the fourth organic compound are a combination that forms a second exciplex, the lowest energy absorption band in the absorption spectrum of the phosphorescent material overlaps with the emission spectrum of the second exciplex; the light emitted from the first light-emitting layer has an emission peak in the range of 500 to 600 nm; the light emitted from the second light-emitting layer has an emission peak in the range of 600 to 700 nm; (However, this does not include the case where the first organic compound and the second organic compound are a combination of 4,4',4"-tris(N-carbazolyl)-triphenylamine (TCTA) and 1,3,5-tris(2-N-phenylbenzimidazolyl)benzene (TPBi), and the third organic compound and the fourth organic compound are a combination of TCTA and TPBi.) Light-emitting element.

7. a first light-emitting layer and a second light-emitting layer between a pair of electrodes; the first light-emitting layer and the second light-emitting layer are in contact with each other, the first light-emitting layer includes at least a first organic compound and a second organic compound; the second light-emitting layer includes at least a third organic compound, a fourth organic compound, and a phosphorescent material; the first organic compound is a compound having an electron transport property, a triplet excitation level of the first organic compound is higher than a triplet excitation level of the phosphorescent material; the second organic compound is a compound having a hole transport property, a triplet excitation level of the second organic compound is higher than a triplet excitation level of the phosphorescent material; the first organic compound and the second organic compound are a combination that forms a first exciplex, the third organic compound and the fourth organic compound are a combination that forms a second exciplex, a difference between an energy equivalent value of a peak wavelength of an absorption band on the lowest energy side in the absorption spectrum of the phosphorescent material and an energy equivalent value of a peak wavelength of an emission spectrum of the second exciplex is 0.2 eV or less; The light emitting element, wherein the light emitted from the first light emitting layer has a peak at a shorter wavelength than the light emitted from the second light emitting layer.

8. a first light-emitting layer and a second light-emitting layer between a pair of electrodes; the first light-emitting layer and the second light-emitting layer are in contact with each other, the first light-emitting layer includes at least a first organic compound and a second organic compound; the second light-emitting layer includes at least a third organic compound, a fourth organic compound, and a phosphorescent material; the first organic compound is a heterocyclic compound, a triplet excitation level of the first organic compound is higher than a triplet excitation level of the phosphorescent material; the second organic compound is a compound having an aromatic amine skeleton or a compound having a carbazole skeleton, a triplet excitation level of the second organic compound is higher than a triplet excitation level of the phosphorescent material; the first organic compound and the second organic compound are a combination that forms a first exciplex, the third organic compound and the fourth organic compound are a combination that forms a second exciplex, a difference between an energy equivalent value of a peak wavelength of an absorption band on the lowest energy side in the absorption spectrum of the phosphorescent material and an energy equivalent value of a peak wavelength of an emission spectrum of the second exciplex is 0.2 eV or less; The light emitting element, wherein the light emitted from the first light emitting layer has a peak at a shorter wavelength than the light emitted from the second light emitting layer.

9. a first light-emitting layer and a second light-emitting layer between a pair of electrodes; the first light-emitting layer and the second light-emitting layer are in contact with each other, the first light-emitting layer includes at least a first organic compound and a second organic compound; the second light-emitting layer includes at least a third organic compound, a fourth organic compound, and a phosphorescent material; the first organic compound is a compound having an electron transport property, a triplet excitation level of the first organic compound is higher than a triplet excitation level of the phosphorescent material; the second organic compound is a compound having a hole transport property, a triplet excitation level of the second organic compound is higher than a triplet excitation level of the phosphorescent material; the first organic compound and the second organic compound are a combination that forms a first exciplex, the third organic compound and the fourth organic compound are a combination that forms a second exciplex, a difference between an energy equivalent value of a peak wavelength of an absorption band on the lowest energy side in the absorption spectrum of the phosphorescent material and an energy equivalent value of a peak wavelength of an emission spectrum of the second exciplex is 0.2 eV or less; the light emitted from the first light-emitting layer is green; The light-emitting element, wherein the light emitted from the second light-emitting layer is red.

10. a first light-emitting layer and a second light-emitting layer between a pair of electrodes; the first light-emitting layer and the second light-emitting layer are in contact with each other, the first light-emitting layer includes at least a first organic compound and a second organic compound; the second light-emitting layer includes at least a third organic compound, a fourth organic compound, and a phosphorescent material; the first organic compound is a heterocyclic compound, a triplet excitation level of the first organic compound is higher than a triplet excitation level of the phosphorescent material; the second organic compound is a compound having an aromatic amine skeleton or a compound having a carbazole skeleton, a triplet excitation level of the second organic compound is higher than a triplet excitation level of the phosphorescent material; the first organic compound and the second organic compound are a combination that forms a first exciplex, the third organic compound and the fourth organic compound are a combination that forms a second exciplex, a difference between an energy equivalent value of a peak wavelength of an absorption band on the lowest energy side in the absorption spectrum of the phosphorescent material and an energy equivalent value of a peak wavelength of an emission spectrum of the second exciplex is 0.2 eV or less; the light emitted from the first light-emitting layer is green; The light-emitting element, wherein the light emitted from the second light-emitting layer is red.

11. a first light-emitting layer and a second light-emitting layer between a pair of electrodes; the first light-emitting layer and the second light-emitting layer are in contact with each other, the first light-emitting layer includes at least a first organic compound and a second organic compound; the second light-emitting layer includes at least a third organic compound, a fourth organic compound, and a phosphorescent material; the first organic compound is a compound having an electron transport property, a triplet excitation level of the first organic compound is higher than a triplet excitation level of the phosphorescent material; the second organic compound is a compound having a hole transport property, a triplet excitation level of the second organic compound is higher than a triplet excitation level of the phosphorescent material; the first organic compound and the second organic compound are a combination that forms a first exciplex, the third organic compound and the fourth organic compound are a combination that forms a second exciplex, a difference between an energy equivalent value of a peak wavelength of an absorption band on the lowest energy side in the absorption spectrum of the phosphorescent material and an energy equivalent value of a peak wavelength of an emission spectrum of the second exciplex is 0.2 eV or less; the light emitted from the first light-emitting layer has an emission peak in the range of 500 to 600 nm; The light emitting device, wherein the light emitted from the second light emitting layer has a peak in the range of 600 to 700 nm.

12. a first light-emitting layer and a second light-emitting layer between a pair of electrodes; the first light-emitting layer and the second light-emitting layer are in contact with each other, the first light-emitting layer includes at least a first organic compound and a second organic compound; the second light-emitting layer includes at least a third organic compound, a fourth organic compound, and a phosphorescent material; the first organic compound is a heterocyclic compound, a triplet excitation level of the first organic compound is higher than a triplet excitation level of the phosphorescent material; the second organic compound is a compound having an aromatic amine skeleton or a compound having a carbazole skeleton, a triplet excitation level of the second organic compound is higher than a triplet excitation level of the phosphorescent material; the first organic compound and the second organic compound are a combination that forms a first exciplex, the third organic compound and the fourth organic compound are a combination that forms a second exciplex, a difference between an energy equivalent value of a peak wavelength of an absorption band on the lowest energy side in the absorption spectrum of the phosphorescent material and an energy equivalent value of a peak wavelength of an emission spectrum of the second exciplex is 0.2 eV or less; the light emitted from the first light-emitting layer has an emission peak in the range of 500 to 600 nm; The light emitting device, wherein the light emitted from the second light emitting layer has a peak in the range of 600 to 700 nm.

13. In any one of claims 1 to 12, a third light-emitting layer; The light-emitting element, wherein the light emitted from the third light-emitting layer is blue.

14. In any one of claims 1 to 12, a third light-emitting layer; The light emitting device, wherein the light emitted from the third light emitting layer has a peak in the range of 440 nm to 520 nm.

15. In any one of claims 1 to 14, The first light-emitting layer further comprises a dopant.

16. In claim 15, The light-emitting device wherein the dopant is a light-emitting material.

17. A light-emitting element according to any one of claims 1 to 16, A light emitting module comprising means for controlling the light emitting element.

18. a display portion including the light-emitting element according to any one of claims 1 to 16; A display module comprising means for controlling said light emitting elements.

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

20. A light-emitting element according to any one of claims 1 to 16, A light emitting device comprising means for controlling the light emitting element.

21. a display portion including the light-emitting element according to any one of claims 1 to 16; A display device comprising means for controlling the light emitting elements.

22. 17. An electronic device comprising the light-emitting element according to claim 1.

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