Light-emitting element

Abstract

In a light-emitting device using multiple light-emitting dopants, we propose a light-emitting device with high luminescence efficiency. It provides a light-emitting device with reduced power consumption, and also uses the aforementioned light-emitting elements. We provide optical modules, light-emitting display devices, electronic devices, and lighting devices, respectively. [Solution] Focusing on the Förster mechanism, one of the intermolecular energy transfer mechanisms, The emission wavelength of the energy-donating molecule and the absorption spectrum of the energy-receiving molecule. The peak with the longest wavelength maximal in the graph obtained by multiplying the wavelength by the fourth power is superimposed. By combining these elements, energy transfer in the above-mentioned Förster mechanism becomes more efficient. ru.

Description

[Technical Field]

[0001] This invention relates to light-emitting devices, display devices, light-emitting devices, and electronic devices using organic compounds as light-emitting materials. And relating to lighting devices. [Background technology]

[0002] In recent years, electroluminescence (EL) Research and development of the light-emitting elements used are actively underway. The basic configuration of these light-emitting elements is as follows: This device consists of a layer containing a light-emitting material sandwiched between a pair of electrodes. When a voltage is applied to this element... This allows us to obtain light emission from the light-emitting material.

[0003] Because these light-emitting elements are self-illuminating, the pixels are more visible compared to liquid crystal displays. It has advantages such as not requiring a backlight, making it a preferred flat panel display element. It is considered suitable. Furthermore, displays using such light-emitting elements are thin and light The ability to produce them in large quantities is a major advantage. Furthermore, their extremely fast response speed is another notable feature. That is the case.

[0004] Since these light-emitting elements can have the light-emitting layer formed as a film, it is possible to obtain light emission in a planar manner. This is possible. Therefore, large-area elements can be easily formed. This is because of the incandescent This is a characteristic that is difficult to obtain with point light sources such as spheres and LEDs, or line light sources such as fluorescent lamps. Therefore, it has high value as a surface light source that can be applied to lighting and other applications.

[0005] Organic EL using an organic compound as the light-emitting material, with a layer containing the organic compound placed between a pair of electrodes. In the case of a device, applying a voltage between a pair of electrodes causes electrons to be released from the cathode and holes to be released from the anode. Each (hole) is injected into a layer containing a luminescent organic compound, and an electric current flows. Then, The injected electrons and holes recombine, causing the luminescent organic compound to enter an excited state. Luminescence can be obtained from excited luminescent organic compounds.

[0006] Organic compounds can form two types of excited states: singlet excited states and triplet excited states. , singlet excited state (S * ) emits fluorescence, triplet excited state (T * ) Light is emitted from It is called light. Furthermore, the statistical generation ratio of the light-emitting element is S * :T * = It is believed to be 1:3.

[0007] Compounds that emit light from a singlet excited state (hereinafter referred to as fluorescent compounds) emit light at room temperature. Normally, no light emission (phosphorescence) from the triplet excited state is observed, but no light emission (firefly) from the singlet excited state is observed. Only light is observed. Therefore, the internal quantum effect in a light-emitting device using a fluorescent compound is... The theoretical limit of the rate (the ratio of photons generated to the injected carriers) is S * :T * = The figure of 25% is based on the 1:3 ratio.

[0008] On the other hand, if we use a compound that emits light from a triplet excited state (hereinafter referred to as a phosphorescent compound), Luminescence (phosphorescence) from the triplet excited state is observed. Furthermore, phosphorescent compounds exhibit intersystem crossover. Because transitions from singlet excited states to triplet excited states occur easily, the internal quantum efficiency is 1 Theoretically, it is possible to achieve up to 00%. In other words, it is possible to achieve a higher luminescence efficiency than that of fluorescent compounds. Therefore, in order to realize a highly efficient light-emitting element, phosphorescent compounds are used. The development of light-emitting elements has been actively pursued in recent years.

[0009] Patent Document 1 describes a light-emitting region having multiple light-emitting dopants, and the light-emitting dopants A white light-emitting element that emits light is disclosed. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] Special Publication No. 2004-522276 [Overview of the project] [Problems that the invention aims to solve]

[0011] Although phosphorescent compounds theoretically allow for 100% internal quantum efficiency, the device structure and other materials... Without optimizing the combination of ingredients, it is difficult to achieve high efficiency. In particular, different ingredients In a light-emitting element that uses multiple types of phosphorescent compounds of different luminescent colors as luminescent dopants, This involves considering not only energy transfer, but also the efficiency of the energy transfer itself. Without optimization, it is difficult to obtain highly efficient light emission. In fact, in the above-mentioned Patent Document 1, light emission Even if all the dopants are phosphorescent elements, the external quantum efficiency is only about 3-4%. Even considering the light extraction efficiency, the internal quantum efficiency is thought to be less than 20%. Therefore, it must be said that this is a low value for a phosphorescent light-emitting element.

[0012] Furthermore, in addition to increasing luminescence efficiency, multicolor light-emitting devices using dopants of different emission colors ( For example, in a white light-emitting element that combines blue, green, and red, the dopants for each light-emitting color are It is necessary for the light to be emitted in a balanced manner. While achieving high luminescence efficiency, the light emitted by each Dopant is also necessary. Maintaining a balance of light is no easy task.

[0013] Therefore, in one aspect of the present invention, in a light-emitting element using a plurality of light-emitting dopants, the light-emitting effect The objective is to provide a light-emitting element with a high efficiency. Another aspect of the present invention is the above-mentioned light-emitting element By using this technology, power consumption is reduced in light-emitting devices, display devices, electronic devices, and lighting. The purpose is to provide each device individually.

[0014] The present invention only needs to solve one of the above-mentioned problems. [Means for solving the problem]

[0015] In this invention, we focus on the Förster mechanism, which is one of the intermolecular energy transfer mechanisms, and energy The peak of the emission spectrum of the energy-donating molecule and the absorption spectrum of the energy-receiving molecule. The peak with the longest wavelength maxima in the characteristic curve obtained by multiplying the spectrum by the fourth power of the wavelength. By applying a combination of molecules such that the above-mentioned Förster mechanism is formed. This enables efficient energy transfer in the context of [the system]. Here, the above energy transfer is generally [the system]. This is not energy transfer from host to dopant, but energy transfer between dopants. One of its characteristics is that the energy transfer efficiency between Dopants is high. Apply a combination of dopants that makes the effect less pronounced, and furthermore, appropriately separate each dopant molecule. By designing a separated element structure, a light-emitting element according to one embodiment of the present invention can be obtained.

[0016] In other words, one aspect of the present invention involves placing a first phosphorescent compound that emits blue light between a pair of electrodes. However, the first light-emitting layer dispersed in the first host material, and in the range of 440 nm to 520 nm ε(λ)λ4 having a maximum value A located on the longest wavelength side of the function represented by, and the first A second phosphorescent compound that emits light with a longer wavelength than the phosphorescent compound is a second host material A second light-emitting layer dispersed in, and ε(λ)λ in the range of 520 nm to 600 nm 4 represented by having a maximum value B located on the longest wavelength side of the function represented by, and longer than the second phosphorescent compound A third phosphorescent compound that exhibits light emission with a wavelength of light is dispersed in a third host material and the third light-emitting A light-emitting element including a layer, wherein the first to third light-emitting layers are laminated in this order. (However, ε(λ) represents the molar absorption coefficient of each phosphorescent compound and is a function of the wavelength λ.) .

[0017] In addition, another aspect of the present invention is that between a pair of electrodes, a first phosphorescent compound that exhibits blue light emission , a first light-emitting layer dispersed in a first host material, and ε in the range of 440 nm to 520 nm (λ)λ 4 having a maximum value A located on the longest wavelength side of the function represented by, and having a peak wavelength of phosphorescent light emission in the range of 520 nm to 600 nm, a second phosphorescent compound is a second light-emitting layer dispersed in a second host material, and ε(λ)λ in the range of 520 nm to 600 nm A third light-emitting layer dispersed in a third host material, and having a maximum value B located on the longest wavelength side of the function represented by 4 4 having, and a third phosphorescent compound that emits light with a longer wavelength than the second phosphorescent compound is dispersed in a third host material The third light-emitting layer thus formed, and a light-emitting device in which the first to third light-emitting layers are laminated in this order. (However, ε(λ) represents the molar absorption coefficient of each phosphorescent compound and is a function of the wavelength λ is).). A child. (However, ε(λ) represents the molar absorption coefficient of each phosphorescent compound and is a function of the wavelength λ <on is).).

[0018] Another aspect of the present invention is a light-emitting element having the above configuration, compared to the maximum value A. The light-emitting element is characterized in that the maximum value B is larger.

[0019] Furthermore, in another aspect of the present invention, in a light-emitting element having the above configuration, the light-emitting layer of the first aforementioned element is The electron-transporting element, and the second and third light-emitting layers, are hole-transporting elements. He is a child.

[0020] Another aspect of the present invention is a light-emitting element having the above configuration, wherein the host material of the first aspect The material is electron-transporting, and the second and third host materials are hole-transporting. It is a light-emitting element.

[0021] Furthermore, in another aspect of the present invention, in a light-emitting element having the above configuration, the light-emitting layer of the first aforementioned element is The light-emitting element is hole-transporting, and the second and third light-emitting layers are electron-transporting. He is a child.

[0022] Another aspect of the present invention is a light-emitting element having the above configuration, wherein the host material of the first aspect The material is hole-transporting, and the second and third host materials are electron-transporting. It is a light-emitting element.

[0023] Another aspect of the present invention is a light-emitting element having the above configuration, wherein the first to third elements This light-emitting element is characterized by having the light-emitting layers stacked in this order, in contact with each other.

[0024] Another aspect of the present invention is a light-emitting element having the above configuration, wherein the second light-emitting layer The film thickness is characterized by being 5 nm to 20 nm, preferably 5 nm to 10 nm. This is a light-emitting element.

[0025] Another aspect of the present invention is a light-emitting device, a light-emitting display device, and a light-emitting display device, each equipped with the above-described light-emitting element. These are electronic devices and lighting equipment.

[0026] In this specification, the term "light-emitting device" includes image display devices that use light-emitting elements. Furthermore, a connector, such as an anisotropic conductive film, or TCP (Tape C) is attached to the light-emitting element. Modules with the Arrier Package installed, print distribution to the TCP destination A module equipped with a wire plate, or a light-emitting element, with a COG (Chip On Glass) The formula includes all modules on which ICs (integrated circuits) are directly mounted as light-emitting devices. Furthermore, this also includes light-emitting devices used in lighting fixtures and the like. [Effects of the Invention]

[0027] One aspect of the present invention can provide a light-emitting element with high luminescence efficiency. One aspect of the present invention can provide the light-emitting element By using this, a light-emitting device, a light-emitting display device, an electronic device, and a power-saving device can be produced with reduced power consumption. We can provide lighting equipment. [Brief explanation of the drawing]

[0028] [Figure 1] Conceptual diagram of a light-emitting element. [Figure 2] Diagram illustrating energy transfer in the light-emitting layer. [Figure 3] A diagram illustrating the movement of the Förster fossil from blue phosphorescence. [Figure 4] A diagram illustrating the movement of the Förster fossil from blue phosphorescence. [Figure 5] A diagram illustrating the movement of the Förster fossil from blue phosphorescence. [Figure 6] Conceptual diagram of an active matrix light-emitting device. [Figure 7] Conceptual diagram of a passive matrix type light-emitting device. [Figure 8] Conceptual diagram of an active matrix light-emitting device. [Figure 9] Conceptual diagram of an active matrix light-emitting device. [Figure 10] Conceptual diagram of a lighting device. [Figure 11] A diagram representing electronic devices. [Figure 12] A diagram representing electronic devices. [Figure 13] A diagram representing a lighting device. [Figure 14] A diagram illustrating lighting and display devices. [Figure 15] A diagram showing an in-vehicle display device and lighting system. [Figure 16] A diagram representing electronic devices. [Figure 17] A diagram showing the current density-luminance characteristics of light-emitting element 1 and light-emitting element 2. [Figure 18] A diagram showing the brightness-current efficiency characteristics of light-emitting element 1 and light-emitting element 2. [Figure 19] A diagram showing the voltage-luminance characteristics of light-emitting element 1 and light-emitting element 2. [Figure 20] A diagram showing the luminance-chromaticity characteristics of light-emitting element 1 and light-emitting element 2. [Figure 21] A diagram showing the brightness-power efficiency characteristics of light-emitting element 1 and light-emitting element 2. [Figure 22] A figure showing the luminance-external quantum efficiency characteristics of light-emitting element 1 and light-emitting element 2. [Figure 23] A figure showing the emission spectra of light-emitting element 1 and light-emitting element 2. [Figure 24] A diagram illustrating the movement of the Förster fossil from blue phosphorescence. [Figure 25] A diagram showing the current density-luminance characteristics of the light-emitting element 3. [Figure 26] A diagram showing the brightness-current efficiency characteristics of the light-emitting element 3. [Figure 27] A diagram showing the voltage-luminance characteristics of the light-emitting element 3. [Figure 28] A diagram showing the luminance-chromaticity characteristics of the light-emitting element 3. [Figure 29] A diagram showing the brightness-power efficiency characteristics of the light-emitting element 3. [Figure 30] A diagram showing the luminance-external quantum efficiency characteristics of the light-emitting element 3. [Figure 31] A diagram showing the emission spectrum of the light-emitting element 3. [Figure 32] A diagram showing the current density-luminance characteristics of the light-emitting element 4. [Figure 33] A diagram showing the brightness-current efficiency characteristics of the light-emitting element 4. [Figure 34] A diagram showing the voltage-luminance characteristics of the light-emitting element 4. [Figure 35] A diagram showing the luminance-chromaticity characteristics of the light-emitting element 4. [Figure 36] A diagram showing the brightness-power efficiency characteristics of the light-emitting element 4. [Figure 37] A diagram showing the luminance-external quantum efficiency characteristics of the light-emitting element 4. [Figure 38] A diagram showing the emission spectrum of the light-emitting element 4. [Figure 39] A diagram showing the time-normalized luminance characteristics of the light-emitting element 4. [Modes for carrying out the invention]

[0029] The embodiments of the present invention will be described in detail below with reference to the drawings. However, the present invention is as follows Not limited to the description, the form and details thereof may be described without departing from the spirit and scope of the present invention. Those skilled in the art will readily understand that the invention can be modified in various ways. Therefore, the present invention is as follows: This should not be interpreted as being limited to the contents described in the embodiments.

[0030] (Embodiment 1) First, the operating principle of a light-emitting element according to one aspect of the present invention will be described. The main point of the present invention is to provide a blue light-emitting element. The first phosphorescent compound that emits light (specifically, with an emission peak at 440 nm to 520 nm) A phosphorescent compound having, or a CIE chromaticity (x,y) of 0.12 ≤ x ≤ 0.25 and A phosphorescent compound that exhibits a light emission color in the color gamut of 0.05 ≤ y ≤ 0.5, and the first phosphorescent Second and third phosphorescence exhibit longer wavelength emission (e.g., green or red emission) than the ion compound. By using phosphorescent compounds and efficiently causing all of the first to third phosphorescent compounds to emit light, The goal is to obtain highly efficient multi-color light-emitting elements.

[0031] A common method for obtaining a multicolor light-emitting element using phosphorescent compounds involves some kind of host material One possible method involves dispersing multiple phosphorescent compounds with different emission colors in appropriate ratios within a material. However, in this method, the phosphorescent compound that exhibits the longest wavelength emission will emit light. Because it becomes cheaper, the element structure for obtaining multicolor emission (especially each phosphorescent in the host material) Designing and controlling the concentration of chemical compounds is extremely difficult.

[0032] Another method for obtaining multicolor light-emitting elements is to stack light-emitting elements of different colors in series, so to speak. One example is a tandem structure consisting of a blue light-emitting element, a green light-emitting element, and a red light-emitting element. By stacking these three elements in series and emitting light simultaneously, multi-colored light (in this case, white light) can be easily obtained. The element structure can be optimized for each of the blue, green, and red elements, so the design... Control is relatively easy. However, because three elements are stacked, the number of layers increases, and production Manufacturing becomes complicated. Also, problems arise with electrical contact at the connection points of each element (the so-called intermediate layer). This can lead to an increase in the driving voltage, i.e., power loss.

[0033] On the other hand, a light-emitting element according to one aspect of the present invention has a first phosphorescent element that emits blue light between a pair of electrodes. A first light-emitting layer in which the compound is dispersed in a first host material, and the first phosphorescent compound A second phosphorescent compound that exhibits long-wavelength emission is dispersed in a second host material. A photon layer and a third phosphorescent compound that exhibits longer wavelength emission than the second phosphorescent compound are The first to third light-emitting layers are dispersed in a third host material. This is a light-emitting element stacked in sequence. In this case, each of the first to third light-emitting layers is different from a tandem structure. They may be placed adjacent to each other.

[0034] Figure 1 schematically shows the element structure of a light-emitting element according to one embodiment of the present invention described above. Figure 1(C) shows The first electrode 101, the second electrode 102, and the EL layer 103 are shown. At least one light-emitting layer 113 is provided, and other layers may be provided as appropriate. In Figure 1(C), the hole injection layer 111, the hole transport layer 112, the electron transport layer 114, and the electron transport layer are shown. A configuration in which a sub-injection layer 115 is provided is shown as a hypothetical example. Note that the first electrode 101 is the anode. The first electrode functions as the first electrode, and the second electrode 102 functions as the cathode.

[0035] Furthermore, Figures 1(a) and 1(b) show enlarged views of the light-emitting layer 113 in the light-emitting element. Figures 1(a) and 1(b) show the first light-emitting layer 113B, the second light-emitting layer 113G, and the third Light-emitting layer 113R, light-emitting layer 113 formed by combining the three layers, first phosphorescent compound 113Bd, Second phosphorescent compound 113Gd, third phosphorescent compound 113Rd, first host material 113Bh, second host material 113Gh, third host material 113Rh, and recombination region Figure 1(a) shows that the first light-emitting layer 113B is provided on the cathode side. Figure 1(b) shows a schematic representation of the case where the first light-emitting layer 113B is located on the anode side. This is a diagram. In all cases, each phosphorescent compound (the first to third phosphorescent compounds) Since they are dispersed in the host material, each phosphorescent compound interacts with each other through the host material. They are isolated. Note that the first to third host materials may be the same or different. stomach.

[0036] In this case, electron exchange interactions (the so-called Dexter mechanism) occur between each phosphorescent compound. Energy transfer due to this is suppressed. That is, the first phosphorescent compound 113Bd is excited. After that, the excitation energy is converted by the Dexter mechanism to the second phosphorescent compound 113Gd Alternatively, the phenomenon of migration to the third phosphorescent compound 113Rd can be prevented. After the phosphorescent compound 113Gd of 2 is excited, its excitation energy is converted into a Dexter mechanism. This also prevents the phenomenon of migration to the third phosphorescent compound 113Rd. Therefore, A phenomenon in which the third phosphorescent compound 113Rd, which exhibits the longest wavelength emission, is primarily responsible for the emission. This can be suppressed. Furthermore, if excitons are directly generated in the third light-emitting layer 113R, Because the third phosphorescent compound 113Rd of the beam primarily emits light, carrier recombination occurs. Region 113ex is within the first light-emitting layer 113B, or between the first light-emitting layer 113B and the second light-emitting layer The interface with the photolayer 113G is set to be the vicinity of the interface (i.e., the first phosphorescent compound 113Bd is the main component). It is preferable to excite it in this way.

[0037] However, energy transfer from the first phosphorescent compound 113Bd is completely suppressed. Then, the emission of the third phosphorescent compound 113Rd cannot be obtained. In one aspect of the invention, the excitation energy of the first phosphorescent compound 113Bd that emits blue light. However, it partially migrates to the second phosphorescent compound 113Gd, and furthermore, the second phosphorescent compound The excitation energy of substance 113Gd is partially transferred to the third phosphorescent compound 113Rd. We design such devices. Energy transfer between isolated molecules in this way is dipole-dipole. This is made possible by utilizing polar interactions (Förster mechanism).

[0038] Here, we will explain the Förster mechanism. Below, we will discuss the part that provides the excitation energy. The child molecule is called the energy donor, and the molecule that receives the excitation energy is called the energy acceptor. To describe, in one embodiment of the present invention, an energy donor, an energy acceptor All of these are phosphorescent compounds and are isolated from each other by the host material.

[0039] The Förster mechanism does not require direct contact between molecules for energy transfer. Energy transfer through the resonance phenomenon of dipole oscillations between donors and energy acceptors. This occurs. Due to the resonance phenomenon of dipole oscillations, the energy donor becomes the energy acceptor. Energy is transferred, the excited energy donor returns to the ground state, and the ground state energy The energy acceptor becomes excited. The rate of energy transfer by the Förster mechanism is fixed. number k F This is shown in equation (1).

[0040]

number

[0041] In equation (1), ν represents the frequency, and F(ν) is the normalized energy donor. Emission spectrum (When discussing energy transfer from singlet excited states, use fluorescence spectrum) When discussing energy transfer from a triplet excited state, the phosphorescent spectrum is used, and ε( ν) represents the molar extinction coefficient of the energy acceptor, N represents Avogadro's number, and n R represents the refractive index of the medium, and R is the intermolecular distance between the energy donor and the energy acceptor. c represents the distance, τ represents the measured lifetime of the excited state (fluorescence lifetime or phosphorescence lifetime), and c represents light The speed is represented by φ, and φ is the emission quantum yield (when discussing energy transfer from a singlet excited state, it is called a firefly). The photon quantum yield (or phosphorescent photon yield when discussing energy transfer from triplet excited states) is expressed. And, K 2 This is the orientation of the transition dipole moments of the energy donor and energy acceptor. This is a coefficient (0-4) representing the direction. Note that in the case of random orientation, K 2 = 2 / 3

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

[0043] Here, as explained in Figure 1, each phosphorescent compound (the first to third phosphorescent compounds) The phosphorescent compounds are dispersed within each host material, and each phosphorescent compound is isolated from the others by each host material. Therefore, the distance R is at least one molecule (1 nm or more). Therefore, all of the excitation energy generated in the first phosphorescent compound is transferred to the Förster mechanism. Therefore, energy is not transferred to the second or third phosphorescent compound. If R is around 10nm to 20nm, then Förster movement is possible, for example By making the film thickness of the second light-emitting layer 113G in Figure 1 20 nm or less, partial energy Energy transfer occurs, resulting in the first phosphorescent compound 113Bd and the second phosphorescent compound 113G. d. The entirety of the third phosphorescent compound 113Rd can be made to emit light.

[0044] A first phosphorescent compound 113Bd that exhibits blue light emission, and a compound that is more than the first phosphorescent compound A second phosphorescent compound 113Gd that exhibits long-wavelength emission (e.g., green emission), and the second A third phosphorus that exhibits longer wavelength emission (e.g., red emission) than the phosphorescent compound 113Gd In a light-emitting element according to one aspect of the present invention using the photoactive compound 113Rd, between each phosphorescent compound A schematic diagram of the Förster movement is shown in Figure 2. In Figure 2, between electrode 10 and electrode 11 A first light-emitting layer 113B, a second light-emitting layer 113G, and a third light-emitting layer 113R are laminated on top of each other. The configuration is shown. Note that one of the electrodes 10 and 11 functions as the anode, and the other functions as the anode. This is an electrode that functions as a cathode. As shown in Figure 2, first the first phosphorescent compound 113B The singlet excited state (S) generated at d B ) is a triplet excited state (T B ) converted In other words, the excitons in the first light-emitting layer 113B are basically T B It can be summarized as follows.

[0045] Next, this T B The energy of the excitons in this state is partially converted into blue light emission. However, by utilizing the Förster mechanism, some of it becomes the second phosphorescent compound 113G Triplet excited state of d (T G This can be moved to the first phosphorescent compound 1. 13Bd is luminescent (high phosphorescence quantum yield φ), and the second phosphorescent compound 11 3Gd has a direct absorption corresponding to the electron transition from the singlet ground state to the triplet excited state. This is due to the existence of an absorption spectrum for the triplet excited state. If you satisfy it, T B From T G A triplet-triplet Förster move to T becomes possible. B From the singlet excited state of the third phosphorescent compound 113Rd (S R Energy transfer to ) Although its contribution is small, it can occur if the conditions for a Förster movement are met. This will be explained later. However, this is more likely to occur when the third phosphorescent compound 113Rd is a red light-emitting material. R Interterminate The difference leads to the triplet excited state of the third phosphorescent compound 113Rd (T R ) This contributes to the emission of the third phosphorescent compound 113Rd. The energy donor (in this case, the first phosphorescent compound 113Bd) needs to be luminescent. Therefore, the phosphorescence quantum yield of the first phosphorescent compound 113Bd must be 0.1 or higher. preferable.

[0046] Furthermore, the singlet excited state of the second phosphorescent compound 113Gd (S G ) is the first phosphorescence Triplet excited state of compound 113Bd (T B ) is often more energetic than, therefore, as mentioned above In many cases, it does not contribute much to the energy transfer. Therefore, it is omitted here.

[0047] Furthermore, the triplet T of the second phosphorescent compound 113Gd G The energy of the exciton in this state is Some of it is converted directly into light (for example, green light), but by using the Förster mechanism... As a result, some of the third phosphorescent compound 113Rd enters the triplet excited state (T R Move to ) This is possible. This is because the second phosphorescent compound 113Gd is luminescent (phosphorescent quantum emission (High rate φ) and the third phosphorescent compound 113Rd is triple-excited from the singlet ground state. It has direct absorption corresponding to the electronic transition to the state (the absorption spectrum of the triplet excited state is It is due to the existence of these conditions. G From T R Triplet-3 Multiplet Förster movement becomes possible. Note that energy donors in the Förster mechanism... (Here, the second phosphorescent compound 113Gd) needs to be luminescent, therefore the second glue The phosphorescent quantum yield of the photochromic compound 113Gd is preferably 0.1 or higher.

[0048] The T generated by the energy transfer described above R This is the third phosphorescent compound 113 It is converted into Rd emission (e.g., red emission). In this way, the first to third phosphorescence occurs. Luminescence can be obtained from each of the combined elements.

[0049] Furthermore, the above-mentioned Förster migration is efficiently generated between phosphorescent compounds that are dopants. Therefore, in order to design it so that no energy is transferred to the host material, the first to third hosts The material preferably does not have an absorption spectrum in the blue region. Specifically, the absorption spectrum It is preferable that the absorption edge of the clef is 440 nm or less. Thus, the host material (specifically Energy is directly transmitted between dopants without the need for a second or third host material. - By allowing movement, the generation of unnecessary energy transfer pathways is suppressed, resulting in a high luminescence effect. It can be linked to a rate.

[0050] Furthermore, the first host material is designed so as not to quench the first phosphorescent compound that exhibits blue light emission. Preferably, it has a triplet excitation energy higher than that of the first phosphorescent compound. .

[0051] As described above, the basic concept of one aspect of the present invention is, firstly, each of the first to third phosphorescence While isolating the compound using a host material and a layered structure, the first one exhibits emission at the shortest wavelength. The device structure primarily uses phosphorescent compounds for excitation. Therefore, within a certain distance (~20nm), Förster-type energy transfer occurs. Because it occurs only partially, the excitation energy of the first phosphorescent compound that exhibits blue light emission is partially The second phosphorescent compound then moves to the second phosphorescent compound, and furthermore, the excitation energy of the second phosphorescent compound is The phosphorescent material partially migrates to the third phosphorescent compound, and light emission is obtained from each of the first to third phosphorescent compounds. It is possible.

[0052] However, in one embodiment of the present invention, a more important point is to consider the energy transfer. This involves the selection of materials and the device structure.

[0053] First, in order to generate a Förster transfer, the emission quantum yield φ on the energy donor side must be Although it needs to be high, in one embodiment of the present invention, phosphorescent compounds (specifically, phosphorescent quantum Since a luminescent compound with a yield of 0.1 or higher is used, no problems arise. The important point is formula (1 Increasing the integral term of ) That is, the emission spectrum F(ν) of the energy donor and the energy The key is to effectively overlap the molar extinction coefficients ε(ν) of the energy acceptors.

[0054] Generally, in the wavelength region where the molar extinction coefficient ε(ν) of the energy acceptor is large, We just need to superimpose the Giedner emission spectra F(ν) (that is, the product of F(ν)ε(ν)) It is thought that (making it larger would be better). However, this is not always the case in the Förster mechanism. However, this is not true. This is because the integral term in equation (1) is inversely proportional to the fourth power of the frequency ν, This is because wavelength dependence exists.

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

[0056]

number

[0057] In other words, the integral term becomes larger as the wavelength λ increases. To put it simply, the longer the wavelength... This means that energy transfer is more likely to occur. In other words, the molar extinction coefficient ε(λ) It's not as simple as just needing F(λ) to overlap in a large wavelength region, but rather ε(λ)λ 4 but We must ensure that F(λ) overlaps over a large region.

[0058] Therefore, the second phosphorescent compound 113Gd in the light-emitting element of one aspect of the present invention is , the first phosphorescent compound 113Bd (specifically 440nm~520nm) exhibits blue light emission. To improve the energy transfer efficiency from phosphorescent compounds (which have an emission peak at m), ε(λ)λ in the range of 440nm to 520nm 4The longest wavelength side of the function represented by It has a maximum value A and exhibits emission at a longer wavelength than the first phosphorescent compound 113Bd. Phosphorescent compounds (specifically, phosphorus having an emission peak in the range of 520 nm to 600 nm) A photocatalytic compound is used. In addition, the third phosphorescent compound 113Rd is the second phosphorescent compound. To improve the energy transfer efficiency from the compound 113Gd, use 520nm~600nm. ε(λ)λ 4 The function represented by has a maximum value B located on the longest wavelength side, and the preceding A phosphorescent compound that exhibits longer wavelength emission than the second phosphorescent compound 113Gd is used. Furthermore, because the luminescence of each phosphorescent compound is as described above, lighting applications Therefore, a light emission with high color rendering can be obtained, and for display applications, good color quality can be achieved. This allows for more efficient emission of light.

[0059] To deepen our understanding of the composition of such phosphorescent compounds (especially the maximum values ​​A and B), please refer to the following: Let's explain using a specific example. Here, we'll use the first phosphorescent compound 113B, which exhibits blue light emission. As d, the following compound (1) (Tris{2-[5-(2-methylphenyl)-4-(2, [6-dimethylphenyl)-4H-1,2,4-triazole-3-yl-κN2]phenyl Iridium(III) (abbreviation: Ir(mpptz-dmp)3) is the first A second phosphorescent compound that exhibits longer wavelength emission (green emission) than phosphorescent compound 113Bd. As 113Gd, the following compound (2)((acetylacetonato)bis(6-tert-br Iridium(III) (abbreviation: Ir(tBuppm)) 2(acac))) emits light at a longer wavelength than the second phosphorescent compound 113Gd (red emission). As the third phosphorescent compound 113Rd exhibiting ), the following compound (3) (bis(2,3,5) -Triphenylpyrazinato) (dipivaloylmethanato) Iridium(III) (abbreviation: I Let's explain using the cases where r(tppr)²(dpm))) are used as examples.

[0060] [ka]

[0061] Figure 3(a) shows the molar extinction coefficient ε(λ) of compound (2), which is the second phosphorescent compound, and ε (λ)λ 4 This shows that the molar extinction coefficient ε(λ) decreases as the wavelength increases. We will go down, ε(λ)λ 4 This is around 490 nm (in the triplet MLCT absorption band of compound (2)). It has a local maximum value A at the corresponding point. As can be seen from this example, λ 4 Due to the influence of the second section, ε(λ)λ of phosphorescent compounds 4 This is the absorption band located on the longest wavelength side (triplet MLCT absorption). The convergence zone has a local maximum value A.

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

[0063] Next, Figure 4(a) shows the molar extinction coefficient ε(λ) of compound (3), which is the third phosphorescent compound. And, ε(λ)λ 4 This shows that the molar extinction coefficient ε(λ) increases as the wavelength increases. It decreases as it progresses, but ε(λ)λ 4 This is around 550 nm (triplet MLCT absorption of compound (3)). It has a local maximum value B in the band (corresponding to the band). As can be seen from this example, λ 4 Due to the influence of the section , the third phosphorescent compound ε(λ)λ 4 This is the absorption band located on the longest wavelength side (triplet ML). It has a maximum value B in the CT absorption band.

[0064] On the other hand, Figure 4(b) shows the photoluminescence (PL) spectrum F(λ) of compound (2). And, ε(λ)λ of compound (3) 4 This shows that compound (2) is second phosphorescent. It is a compound that exhibits green emission with an emission peak around 545 nm. This second phosphorus The PL spectrum F(λ) of the photosensitive compound is ε(λ)λ of the third phosphorescent compound. 4 Maximum value Near B, ε(λ)λ 4 It has a large overlap with the second phosphorescent compound. Energy transfer occurs to the third phosphorescent compound via the Förster mechanism. In total, the maximum value B corresponds to the triplet MLCT absorption band, therefore the triplet-triplet ferrust This is a type 1 energy transfer (T in Figure 2). G -T REnergy transfer).

[0065] Furthermore, based on the above, the second and third phosphorescent compounds are those with the longest wavelength in their absorption spectrum. On the longer side, there is direct absorption corresponding to the electron transition from the singlet ground state to the triplet excited state (for example, It is preferable to have triplet MLCT absorption. With this configuration, Figure 2 This results in efficient triplet-triplet energy transfer, as shown in the diagram.

[0066] Here, Figures 3(b) and 4(b) are combined on the same diagram, and further, with a third phosphorescent compound... Figure 5 shows a diagram that also includes the PL spectrum of a certain compound (3). PL spectrum and ε(λ)λ of compound (2) 4 Using the overlap (near the maximum value A) From substance (1) to compound (2), and then the PL spectrum of compound (2) and compound (3) ε(λ)λ 4 Using the overlap (near the maximum value B), we transition from compound (2) to compound (3), step It can be seen that energy transfer is possible in stages. Direct energy transfer from compound (1) to compound (3), which is a third phosphorescent compound. This is also possible. As can be seen from Figure 5, this is because of the triplet MLCT absorption band (polarity) of compound (3). On the shorter wavelength side (near the maximum value B), the PL spectrum F(λ) of compound (1) and compound (3) ε(λ)λ 4 This is because they overlap, resulting in a triplet-singlet Förster-type energy. - This suggests that movement exists (T in Figure 2) B -S R Energy transfer).

[0067] The important thing that can be seen from Figures 3, 4, and 5 above is λ 4 Due to the influence of the second phosphorescent compound Compared to the first, the third phosphorescent compound accepts energy more easily (energy accepts (It is prone to becoming a tar.) Both the second and third phosphorescent compounds are the most The molar extinction coefficient ε(λ) of the triplet MLCT absorption band on the longer wavelength side is 5000 [M -1 cm -1 It is approximately the same, and therefore almost equivalent. Nevertheless, as can be seen in Figure 5, ε(λ)λ 4 Comparing the local maximums A and B, local maximum B is about 1.6 times larger. This is λ 4 This is due to the influence of the term, and compounds with absorption bands at longer wavelengths tend to have an absorption band of ε(λ). )λ 4 It shows a tendency to become larger. Therefore, compared to the second phosphorescent compound, This indicates that the third phosphorescent compound is more likely to accept energy.

[0068] Therefore, the first to third light-emitting layers are stacked in this order, and the carrier recombination region is the first The light-emitting layer is either within the first light-emitting layer or near the interface between the first and second light-emitting layers (i.e., the first We focused on a device structure that primarily excites phosphorescent compounds (as shown in Figure 1). By using this device structure, the second light-emitting layer containing the second phosphorescent compound is more However, the third light-emitting layer containing the third phosphorescent compound is further away from the carrier recombination region. In this way, the third phosphorescent compound, which readily accepts energy, is recombined from the bonding region. A second phosphorescent compound, which is relatively less likely to receive energy, is located far away, near the recombination region. By arranging them accordingly, the emission from each of the first to third phosphorescent compounds is balanced. It can be obtained. As a result, the luminescence efficiency is good and the spectral balance is good. A light-emitting element can be obtained.

[0069] Furthermore, in order to obtain the recombination region described above, the first light-emitting layer is electron-transporting, and the second The light-emitting layer and the third light-emitting layer are preferably hole-transporting (Figure 1(a)). Specifically For example, an electron-transporting material is used as the first host material, and the second host material is Furthermore, a hole-transporting material may be used as the third host material.

[0070] Furthermore, in another embodiment for obtaining the aforementioned recombination region, the first light-emitting layer is hole-transporting, The second and third light-emitting layers are preferably electron-transporting (Figure 1(b) Specifically, for example, a hole-transporting material is used as the first host material, and the second host As the host material and the third host material, electron-transporting materials may be used.

[0071] Furthermore, in order to obtain light emission from the second light-emitting layer as well as from the third light-emitting layer Considering the distance R of the Förster migration, the film thickness of the second light-emitting layer is 5 nm to 20 nm. Preferably, the following: More preferably, 5 nm to 10 nm.

[0072] (Embodiment 2) In this embodiment, Figure 1 shows an example of the detailed structure of the light-emitting element described in Embodiment 1. I will explain below.

[0073] The light-emitting element in this embodiment has an EL layer consisting of multiple 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 consists of an EL layer 103 provided between electrode 101 and second electrode 102. In this embodiment, the first electrode 101 functions as the anode, and the second electrode 102 functions as the cathode. The following explanation assumes that it functions as follows: In other words, the first electrode 101 is more like 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 2. Sometimes, the device is configured to emit light.

[0074] Since the first electrode 101 functions as an anode, it has a large work function (specifically 4.0e Formed using metals, alloys, conductive compounds, and mixtures thereof (V or higher). Preferred. Specifically, for example, indium tin oxide (ITO) indium oxide-tin oxide containing silicon or silicon oxide, Indium oxide containing zinc oxide, tungsten oxide, and zinc oxide ( Examples include IWZO. These conductive metal oxide films are usually produced by sputtering. Although it is formed by film deposition, it may also be fabricated using methods such as the sol-gel method. Indium oxide-zinc oxide is produced by adding 1-20 wt% zinc oxide to indium oxide. One method involves forming the target using a sputtering technique. Indium oxide (IWZO) containing sten and zinc oxide is a type of indium oxide. This product contains 0.5-5 wt% tungsten oxide and 0.1-1 wt% zinc oxide. It can also be formed by sputtering using a t. In addition, gold (Au), platinum ( Pt, Nickel (Ni), Tungsten (W), Chromium (Cr), Molybdenum (Mo) Iron (Fe), cobalt (Co), copper (Cu), palladium (Pd), or metallic materials Examples include nitrides (e.g., titanium nitride). Graphene can also be used. By using the composite material described later in the layer that comes into contact with the first electrode 101 in the EL layer 103, This allows for the selection of electrode materials regardless of the work function.

[0075] The laminated structure of the EL layer 103 is such that the light-emitting layer 113 has the configuration shown in Embodiment 1. As long as it is included, the rest is not particularly limited. For example, hole injection layer, hole transport layer, light-emitting layer, electron The structure is constructed by appropriately combining a transport layer, electron injection layer, carrier block layer, intermediate layer, etc. Yes, it is possible. In this embodiment, the EL layer 103 is a hole layer that is sequentially stacked on top of the first electrode 101. Injection layer 111, hole transport layer 112, light-emitting layer 113, electron transport layer 114, electron injection layer 115 The following describes the configuration having the following characteristics. The materials that make up each layer are specifically shown below.

[0076] The hole injection layer 111 is a layer containing a material with high hole injection potential. This includes molybdenum oxide and vanadium. Uses materials such as zinc oxide, ruthenium oxide, tungsten oxide, and manganese oxide. This can be done. In addition, phthalocyanine (abbreviated as H2Pc) and copper phthalocyanine (CuPC) can be used. Phthalocyanine compounds such as 4,4'-bis[N-(4-diphenylaminophenyl )-N-phenylamino]biphenyl (abbreviation: DPAB), N,N'-bis{4-[bis (3-methylphenyl)amino]phenyl}-N,N'-diphenyl-(1,1'-biphenyl Aromatic amine compounds such as phenyl-4,4'-diamine (abbreviation: DNTPD), or por Li(ethylenedioxythiophene) / Poly(styrenesulfonic acid)(PEDOT / PSS) The hole injection layer 111 can also be formed by polymers such as ).

[0077] Furthermore, the hole injection layer 111 contains a hole transporting substance and an acceptor substance. Composite materials can be used. Furthermore, the hole-transporting material may contain an acceptor material. By using this method, it is possible to select the material for forming the electrodes regardless of the work function of the electrodes. Yes, it is possible. In other words, not only materials with a large work function can be used as the first electrode 101, but also materials with a large work function. Smaller materials can also be used. Acceptable materials include 7, 7, 8 ,8-Tetracyano-2,3,5,6-Tetrafluoroquinodimethane (abbreviation: F4-TC Examples include NQ, chloranil, etc. Transition metal oxides can also be mentioned. Furthermore, oxides of metals belonging to groups 4 through 8 of the periodic table can be listed. Specifically, vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide. Den, tungsten oxide, manganese oxide, and rhenium oxide are preferred due to their high electron-accepting properties. In particular, molybdenum oxide is stable in the atmosphere, has low hygroscopicity, and is easy to handle. preferable.

[0078] Examples of hole-transporting substances used in composite materials include aromatic amine compounds and carbazole derivatives. Body, aromatic hydrocarbons, polymer compounds (oligomers, dendrimers, polymers, etc.), species Various organic compounds can be used. Note that the organic compounds used in the composite material are... It is preferable that the organic compound has high pore transport properties. Specifically, 10 -6 cm 2 / Vs or later It is preferable that the material has the above hole mobility. Below, hole transport in composite materials The following is a list of specific organic compounds that can be used as transportable substances.

[0079] For example, an aromatic amine compound is N,N'-di(p-tolyl)-N,N'-diph Phenyl-p-phenylenediamine (abbreviation: DTDPPA), 4,4'-bis[N-(4- [Diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation: DPAB), N ,N'-bis{4-[bis(3-methylphenyl)amino]phenyl}-N,N'-diph Phenyl-(1,1'-biphenyl)-4,4'-diamine (abbreviation: DNTPD), 1,3 ,5-Tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene Examples include (abbreviated as DPA3B).

[0080] Carbazole derivatives that can be used in composite materials include, specifically, 3-[N- (9-phenylcarbazole-3-yl)-N-phenylamino]-9-phenylcarb Zol (abbreviation: PCzPCA1), 3,6-bis[N-(9-phenylcarbazole-3 -yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA2) , 3-[N-(1-naphthyl)-N-(9-phenylcarbazole-3-yl)amino] Examples include -9-phenylcarbazole (abbreviated as PCzPCN1).

[0081] In addition, 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[ Using 4-(N-carbazolyl)phenyl]-2,3,5,6-tetraphenylbenzene, etc. It is possible to be there.

[0082] Furthermore, examples of aromatic hydrocarbons that can be used in composite materials 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 Cene (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]anthrace n, 9,10-bis[2-(1-naphthyl)phenyl]anthracene, 2,3,6,7- Tetramethyl-9,10-di(1-naphthyl)anthracene, 2,3,6,7-tetramethyl Chil-9,10-di(2-naphthyl)anthracene, 9,9'-biantril, 10,1 0'-Diphenyl-9,9'-biantryl, 10,10'-bis(2-phenylphenyl Ru)-9,9'-Biantril, 10,10'-Bis[(2,3,4,5,6-Pentaf [phenyl]-9,9'-bianthryl, anthracene, tetracene, rubrene, Examples include perylene and 2,5,8,11-tetra(tert-butyl)perylene. In addition, pentacene, coronene, etc. can also be used. -6 cm 2 Aromatic hydrocarbons with a hole mobility of / Vs or higher and having 14 to 42 carbon atoms are used. It is preferable to do so.

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

[0084] Also, poly(N-vinylcarbazole) (abbreviation: PVK) and poly(4-vinyltriphen 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 High molecular weight compounds such as (phenyl)benzidine (abbreviated as Poly-TPD) can also be used. can.

[0085] By forming a hole injection layer, hole injection performance is improved, and a low driving voltage is required. This makes it possible to obtain optical elements.

[0086] The hole transport layer 112 is a layer containing a hole-transporting substance. The hole-transporting substance is: For example, 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviated) Name: NPB) or 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-phenylfluorene-9-yl)triphenylamine (abbreviation: BPAFLP), etc. Aromatic amine compounds such as these can be used. The substances described here have high hole transport properties and mainly have a hole mobility of 10 -6 cm 2 / Vs or more of substances. Also, the organic compounds cited as hole transport substances in the above composite materials can also be used for the hole transport layer 112. In addition, polymer compounds such as poly(N-vinylcarbazole) (abbreviation: PVK) and poly(4-vinylt ) riphenylamine) (abbreviation: PVTPA) can also be used. Note that the layer containing the hole transport substance may be not only a single layer but also a laminate of two or more layers formed from the above substances.

[0087] The light-emitting layer 113 is a layer containing a light-emitting substance . Since the light-emitting layer 113 has the structure described in Embodiment 1 , the light-emitting device in this embodiment can be a light-emitting device with very good luminous efficiency. For the structure and materials of the light-emitting layer 113, refer to the description in Embodiment 1.

[0088] In the light-emitting layer 113, there is no particular limitation on the materials that can be used as the light-emitting substance or the light-emitting center substance. Examples of the above light-emitting substance or light-emitting center substance include the following kinds of substances.

[0089] ​The first phosphorescent compound is preferably one that exhibits blue light emission, for example, 440 nm to 520 nm. A phosphorescent compound having an emission peak can be selected. Specifically, Tris{ 2-[5-(2-methylphenyl)-4-(2,6-dimethylphenyl)-4H-1,2 ,4-triazole-3-yl-κN2]phenyl-κC}iridium(III) (abbreviation) :Ir(mpptz-dmp)3), Tris(5-methyl-3,4-diphenyl-4H- 1,2,4-Triazolat) Iridium(III) (abbreviation: Ir(Mptz)3), Tri S[4-(3-biphenyl)-5-isopropyl-3-phenyl-4H-1,2,4- 4 such as rhazolato iridium(III) (abbreviation: Ir(iPrptz-3b)3) Organometallic iridium complexes having an H-triazole skeleton, and tris[3-methyl-1-( 2-methylphenyl)-5-phenyl-1H-1,2,4-triazolato]iridium( III) (Abbreviation: Ir(Mptz1-mp)3), Tris(1-methyl-5-phenyl- 3-Propyl-1H-1,2,4-Triazolato) Iridium(III) (Abbreviation: Ir( Organometallic iridium with a 1H-triazole skeleton, such as Prptz1-Me)3) Complexes, and fac-tris[1-(2,6-diisopropylphenyl)-2-phenyl-1 H-imidazole] Iridium(III) (abbreviation: Ir(iPrpmi)3), Tris[ 3-(2,6-dimethylphenyl)-7-methylimidazo[1,2-f]phenantidine Imidium(III) (abbreviation: Ir(dmpimpt-Me)3) Organometallic iridium complexes having a zole skeleton, and bis[2-(4',6'-difluoro Enyl)pyridinate-N,C 2’Iridium(III) tetrakis(1-pyrazolyl) Borate (abbreviation: FIr6), bis[2-(4',6'-difluorophenyl)pyridina To-N,C 2’ Iridium(III) picolinate (abbreviation: Firpic), bis{2 -[3',5'-bis(trifluoromethyl)phenyl]pyridinate-N,C 2’ Iri Dium(III) picolinate (abbreviation: Ir(CF3ppy)2(pic)), bis[2 -(4',6'-difluorophenyl)pyridinate-N,C 2’ Iridium (III) Pheny compounds with electron-withdrawing groups, such as acetylacetonate (abbreviation: FIr(acac)) Examples include organometallic iridium complexes with lupyridine derivatives as ligands. , polyazole skeletons such as 4H-triazole, 1H-triazole, and imidazole The organometallic iridium complex possesses high hole-trapping properties. Therefore, in one aspect of the present invention When the first light-emitting layer in the light-emitting element is electron-transporting (specifically, the first host material (When the material is an electron transport material), an organometallic iridium complex having a polyazole skeleton is used. By using it as a phosphorescent compound 1, the carrier recombination region is located within the first light-emitting layer. This is preferable because it can be controlled to occur near the interface between the first and second light-emitting layers. Oh, organometallic iridium complexes with a 4H-triazole skeleton also offer reliability and luminescence efficiency. It is particularly preferable because it is superior.

[0090] The second phosphorescent compound is a compound that exhibits longer wavelength emission than the first phosphorescent compound. It is acceptable, but preferably, phosphorescent light having an emission peak in, for example, 520 nm to 600 nm. A sex compound can be selected. Specifically, tris(4-methyl-6-phenylpyr midinato)iridium(III) (abbreviation: Ir(mppm)3), tris(4-t-but yl-6-phenylpyrimidinato)iridium(III) (abbreviation: Ir(tBuppm)3 ), (acetylacetonato)bis(6-methyl-4-phenylpyrimidinato)iridium (III) (abbreviation: Ir(mppm)2(acac)), (acetylacetonato)bis( 6-tert-butyl-4-phenylpyrimidinato)iridium(III) (abbreviation: Ir (tBuppm)2(acac)), (acetylacetonato)bis[6-(2-norborn yl)-4-phenylpyrimidinato]iridium(III) (abbreviation: Ir(nbppm) 2(acac)), bis{2-[5-methyl-6-(2-methylphenyl)-4-pyrimi dinyl-κN3]phenyl-κC}(2,4-pentanedionato-κ 2 O,O’)iridi um(III) (abbreviation: Ir(mpmppm)2(acac)), (acetylacetonato )bis(4,6-diphenylpyrimidinato)iridium(III) (abbreviation: Ir(dpp m)2(acac)) and other organometallic iridium complexes having a pyrimidine skeleton, or (a 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) (abbre viation: Ir(mppr-iPr)2(acac)) and other organometallic iridium complexes having a pyrazine skeleton, or tris(2-phenylpyridinato-N,C 2’ )iridium(III ) (Abbreviation: Ir(ppy)3), bis(2-phenylpyridinato-N,C) 2’ ) Iridiu Mu(III)acetylacetonate (abbreviation: Ir(ppy)2acac), bis(benzo) [h]Quinolinate) Iridium(III) acetylacetonate (abbreviation: Ir(bzq) 2(acac), Tris(benzo[h]quinolinato) iridium(III) (abbreviation: I r(bzq)3), Tris(2-phenylquinolinato-N,C) 2’ ) Iridium (III )(Abbreviation: Ir(pq)3), bis(2-phenylquinolinato-N,C) 2’ )iridium (III) Pyridogenes such as acetylacetonate (abbreviation: Ir(pq)2(acac)) In addition to organometallic iridium complexes with a rib skeleton, tris(acetylacetonate)(monofe) Nanthroline terbium(III) (abbreviation: Tb(acac)3(Phen)) Examples include rare earth metal complexes. Among those mentioned above, diazinos such as pyrimidines and pyrazines are particularly noteworthy. Organometallic iridium complexes with a nano skeleton have weak hole trapping properties and high electron trapping properties. Therefore, in the case where the second light-emitting layer in the light-emitting element of one aspect of the present invention is hole-transporting, In combination (specifically, when the second host material is a hole transport material), it has a diazine skeleton. By using an organometallic iridium complex as a second phosphorescent compound, carrier recombination occurs. The region is controlled to be within the first light-emitting layer or near the interface between the first and second light-emitting layers. This is preferable because it allows for this. Furthermore, organometallic iridium complexes having a pyrimidine skeleton are reliable. It is particularly preferable because it is outstanding in terms of reliability and luminous efficiency.

[0091] The third phosphorescent compound uses a compound that exhibits longer wavelength emission than the second phosphorescent compound. It is acceptable as long as it is, but preferably, a red light having an emission peak at, for example, 600 nm to 700 nm is used. A phosphorescent compound can be selected. Specifically, bis[4,6-bis(3-methyl [Diisobutyrylmethano](Tylphenyl)pyrimidinato (Abbreviation: Ir(5mdppm)2(dibm)), bis[4,6-bis(3-methylphenyl) Limiginato (dipivaloylmethanato) Iridium(III) (Abbreviation: Ir(5mdpp) m)2(dpm)), bis[4,6-di(naphthalene-1-yl)pyrimidinato](dipi Valoylmethanato iridium(III) (abbreviation: Ir(d1npm)2(dpm)) organometallic iridium complexes having a pyrimidine skeleton, such as (acetylacetonato)bis (2,3,5-triphenylpyrazinate)iridium(III) (abbreviation: Ir(tppr) )2(acac)), bis(2,3,5-triphenylpyradinate)(dipivaloylmeth Sodium iridium(III) (abbreviation: Ir(tppr)2(dpm)), (acetylacetate) Tonato)bis[2,3-bis(4-fluorophenyl)quinoxalinato]iridium(I Organometallic metals with a pyrazine skeleton, such as II) (abbreviation: Ir(Fdpq)2(acac)) Iridium complexes of the genus, and tris(1-phenylisoquinolinato-N,C) 2’ )iridium( III) (Abbreviation: Ir(piq)3), Bis(1-phenylisoquinolinate-N,C) 2’ ) Iridium(III) acetylacetonate (abbreviation: Ir(piq)2acac) In addition to organometallic iridium complexes with a pyridine skeleton, 2, 3, 7, 8, 12, 13, 17,18-Octaethyl-21H,23H-Porphyrin Platinum(II) (Abbreviation: PtO Platinum complexes such as EP, and tris(1,3-diphenyl-1,3-propanedionato) (Monophenanthroline) Europium(III) (Abbreviation: Eu(DBM)3(Phen )), Tris[1-(2-tenoyl)-3,3,3-trifluoroacetonate](monof Phenanthroline europium(III) (abbreviation: Eu(TTA)3(Phen)) Examples include rare earth metal complexes. Among those mentioned above, pyrimidines and pyrazines are examples of dia. Organometallic iridium complexes with a din skeleton have weak hole trapping properties and electron trapping properties. It is expensive. Therefore, the third light-emitting layer in the light-emitting element of one aspect of the present invention is hole-transporting. In this case (specifically, when the third host material is a hole transport material), having a diazine skeleton By using an organometallic iridium complex as a third phosphorescent compound, carrier regeneration The combined region is controlled to be within the first light-emitting layer or near the interface between the first and second light-emitting layers. This is preferable because it allows for this. Furthermore, organometallic iridium complexes having a pyrimidine skeleton are, It is particularly preferable because it is outstanding in terms of reliability and luminous efficiency. Furthermore, it possesses a pyrazine skeleton. The organometallic iridium complex produces a red emission with good chromaticity, thus providing a white light according to one embodiment of the present invention. Applying this to light-emitting elements can improve color rendering.

[0092] Furthermore, in addition to the phosphorescent compounds described above, from among known phosphorescent light-emitting materials, the embodiments include The first phosphorescent material, the second phosphorescent material, and the third phosphorescent material have the relationship shown in 1. You may select and use the appropriate ingredients.

[0093] Furthermore, the materials that can be used as the first to third host materials described above are not particularly limited. Instead, various carrier transport materials are selected and appropriately chosen to obtain the device structure shown in Figure 1. They can be combined. In this case, as mentioned above, an electron-transporting host material and a hole-transporting host material are used. It is preferable to combine different materials.

[0094] For example, as a host material having electron transport properties, bis(10-hydroxybenzo[h] (Quinolinato) Beryllium(II) (abbreviation: BeBq2), bis(2-methyl-8-quinolinato) (4-phenylphenolato)aluminum(III) (abbreviation: BAlq), bis (8-Quinolinolato)zinc(II) (abbreviation: Znq), bis[2-(2-benzoxaz [Ryl)phenolate]zinc(II) (abbreviation: ZnPBO), bis[2-(2-benzothiazo Metal complexes such as lyl(phenolate)zinc(II) (abbreviation: ZnBTZ) and 2-(4-bi Phenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (Abbreviation: PBD), 3-(4-biphenylyl)-4-phenyl-5-(4-tert- Tylphenyl)-1,2,4-triazole (abbreviation: TAZ), 1,3-bis[5-(p -tert-butylphenyl)-1,3,4-oxadiazole-2-yl]benzene ( Abbreviation: OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazole-2- Il)phenyl]-9H-carbazole (abbreviation: CO11), 2,2',2''-(1, 3,5-Benzenetriyl)tris(1-phenyl-1H-benzoimidazole) (abbreviation) :TPBI), 2-[3-(dibenzothiophen-4-yl)phenyl]-1-phenyl Polyazole skeletons such as -1H-benzoimidazole (abbreviation: mDBTBIm-II) Heterocyclic compounds containing 2-[3-(dibenzothiophen-4-yl)phenyl]dibene Zo[f,h]quinoxaline (abbreviation: 2mDBTPDBq-II), 2-[3'-(diben Zothiophene-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviated) Name: 2mDBTBPDBq-II), 2-[3'-(9H-carbazole-9-yl)bi Phenyl-3-yl dibenzo[f,h]quinoxaline (abbreviation: 2mCzBPDBq), 4,6-Bis[3-(phenanthren-9-yl)phenyl]pyrimidine (abbreviation: 4,6) mPnP2Pm), 4,6-bis[3-(4-dibenzothienyl)phenyl]pyrimidine Heterocyclic compounds having a diazine skeleton, such as (abbreviation: 4,6mDBTP2Pm-II), 3,5-Bis[3-(9H-carbazole-9-yl)phenyl]pyridine (abbreviation: 35) DCzPPy), 1,3,5-tri[3-(3-pyridyl)phenyl]benzene (abbreviation: Examples include heterocyclic compounds having a pyridine skeleton, such as TmPyPB. Heterocyclic compounds with a diazine skeleton or a pyridine skeleton are reliable. Good and preferable. In particular, heterocyclic compounds having a diazine (pyrimidine or pyrazine) skeleton. The material has high electron transport properties and contributes to reducing the drive voltage.

[0095] Furthermore, as a host material that possesses hole transport properties, 4,4'-bis[N-(1-naphthyl) -N-phenylamino]biphenyl (abbreviation: NPB), N,N'-bis(3-methylphenyl) (Nyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (abbreviation) :TPD), 4,4'-bis[N-(spiro-9,9'-bifluoren-2-yl)-N ―phenylamino]biphenyl (abbreviation: BSPB), 4-phenyl-4'-(9-phenyl (Fluoren-9-yl)triphenylamine (abbreviation: BPAFLP), 4-phenyl- 3'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: mBPAFL) P), 4-phenyl-4'-(9-phenyl-9H-carbazole-3-yl)triphen Nylamine (abbreviation: PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl -9H-carbazole-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4 -(1-naphthyl)-4'-(9-phenyl-9H-carbazole-3-yl)trife Nylamine (abbreviation: PCBANB), 4,4'-di(1-naphthyl)-4''-(9-f Phenyl-9H-carbazole-3-yl)triphenylamine (abbreviation: PCBNBB), 9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazole-3] -yl)phenyl]fluoren-2-amine (abbreviation: PCBAF), N-phenyl-N- [4-(9-phenyl-9H-carbazole-3-yl)phenyl]spiro-9,9'- Compounds having an aromatic amine skeleton, such as bifluoren-2-amine (abbreviation: PCBASF) For example, 1,3-bis(N-carbazolyl)benzene (abbreviation: mCP), 4,4'-di(N -Carbazolyl)biphenyl (abbreviation: CBP), 3,6-bis(3,5-diphenyl) (nyl)-9-phenylcarbazole (abbreviation: CzTP), 3,3'-bis(9-phenyl Compounds having a carbazole skeleton, such as -9H-carbazole (abbreviated as PCCP), 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene)( Abbreviation: DBT3P-II), 2,8-diphenyl-4-[4-(9-phenyl-9H-f Luoren-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-III), 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldi Compounds containing a thiophene skeleton, such as benzothiophene (abbreviation: DBTFLP-IV) and ,4,4',4''-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviated) Name: DBF3P-II), 4-{3-[3-(9-phenyl-9H-fluorene-9-I Phenyl dibenzofuran (abbreviation: mmDBFFLBi-II), etc. Examples include compounds having a ranic skeleton. Among those mentioned above, compounds having an aromatic amine skeleton Compounds containing substances or carbazole skeletons are highly reliable and have high hole transport properties. This is preferable because it also contributes to reducing the drive voltage.

[0096] In addition to the host materials described above, other known substances may be used as host materials. Oh, as a host material, a phosphorescent compound with a triplet level (between the ground state and the triplet excited state) It is preferable to select a material that has a triplet level greater than the energy difference. These host materials preferably do not have an absorption spectrum in the blue region. Specifically, Preferably, the absorption edge of the absorption spectrum is 440 nm or less.

[0097] The light-emitting layer 113 having the above configuration can be co-deposited by vacuum deposition or as a mixed solution. It can be fabricated using methods such as inkjet printing, spin coating, and dip coating. ru.

[0098] The electron transport layer 114 is a layer containing an electron-transporting material. For example, tris(8-quinoli) Aluminum (abbreviation: Alq), Tris(4-methyl-8-quinolinolato)al Minium (abbreviation: Almq3), bis(10-hydroxybenzo[h]quinolinato)beri Rium (abbreviation: BeBq2), bis(2-methyl-8-quinolinolate)(4-phenyl Enola aluminum (abbreviation: BAlq), etc., quinoline skeleton or benzoquinoline skeleton It is a layer consisting of metal complexes having a specific property. In addition, bis[2-(2-hydroxyphenyl] [Nyl)benzoxazolate]zinc (abbreviation: Zn(BOX)2), bis[2-(2-hydro Oxazoles such as xyphenyl)benzothiazolat]zinc (abbreviation: Zn(BTZ)2) Metal complexes having thiazole ligands can also be used. In addition, 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3 ,4-oxadiazole (abbreviation: PBD) and 1,3-bis[5-(p-tert-butyric acid) [Oxadiazole-2-yl]benzene (abbreviation: OXD-7) ), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl) -1,2,4-triazole (abbreviation: TAZ), vasophenanthroline (abbreviation: BPhe n) Vasocuproine (abbreviated as BCP) can also be used. It has high electron transport properties, mainly 10 -6 cm 2 It is a substance with an electron mobility of / Vs or greater. Furthermore, the electron-transporting host material described above may be used for the electron transport layer 114.

[0099] Furthermore, the electron transport layer 114 is not limited to a single layer, but can also consist of two or more layers made of the above material. It may also be considered as a layered structure.

[0100] Furthermore, a layer for controlling the movement of electron carriers may be provided between the electron transport layer and the light-emitting layer. This involves adding a small amount of a substance with high electron-trapping properties to a material with high electron-transporting properties as described above. This layer adjusts the carrier balance by suppressing the movement of electron carriers. This becomes possible. In such a configuration, electrons penetrate the light-emitting layer, causing emission. It is highly effective in suppressing problems that may arise (for example, a decrease in the lifespan of the device).

[0101] Furthermore, between the electron transport layer 114 and the second electrode 102, electrons are in contact with the second electrode 102. An injection layer 115 may be provided. The electron injection layer 115 may be lithium fluoride (LiF), Alkali metals such as cesium fluoride (CsF) and calcium fluoride (CaF2) or Alkaline earth metals or compounds thereof can be used. For example, those with electron transport properties. A layer made of a substance contains alkali metals, alkaline earth metals, or compounds thereof. A material having electron transport properties can be used as the electron injection layer 115. By using a layer containing alkali metals or alkaline earth metals, This is more preferable because electron injection from the second electrode 102 is performed efficiently.

[0102] The material forming the second electrode 102 has a small work function (specifically 3.8 eV) The following can be used: metals, alloys, electrically conductive compounds, and mixtures thereof. Specific examples of such cathode materials include lithium (Li) and cesium (Cs). Potassium metals, as well as magnesium (Mg), calcium (Ca), and strontium (Sr) Elements belonging to Group 1 or Group 2 of the periodic table, and alloys containing these elements (MgAg Rare earth metals such as AlLi, europium (Eu), ytterbium (Yb), and Examples include alloys containing these. However, between the second electrode 102 and the electron transport layer By providing an electron injection layer, regardless of the magnitude of the work function, Al, Ag, ITO, Ke Various conductive materials such as indium oxide-tin oxide containing ion or silicon oxide are used in the second These conductive materials can be used as electrodes 102. The film can be deposited using methods such as the stencil method and spin coating method.

[0103] Furthermore, various methods can be used to form the EL layer 103, regardless of whether they are dry or wet methods. This can be done using methods such as vacuum deposition, inkjet printing, or spin coating. It is permissible to do so. Furthermore, different film deposition methods may be used for each electrode or layer. .

[0104] The electrodes can also be formed using a wet process with the sol-gel method, or they can be formed using a metallic base material. It may also be formed by a wet method using a t. Alternatively, dry methods such as sputtering or vacuum deposition may be used. It may also be formed using [a specific method / tool].

[0105] The light-emitting element having the above configuration has a first electrode 101 and a second electrode 102 between them. The resulting potential difference causes an electric current to flow, and in the light-emitting layer 113, which is a layer containing a highly luminescent material, Holes and electrons recombine and emit light. In other words, an luminescent region is formed in the luminescent layer 113. It is structured in such a way that it can be used.

[0106] The light is emitted through either the first electrode 101 or the second electrode 102, or both. It is removed to the outside. Therefore, either the first electrode 101 or the second electrode 102 Alternatively, both may consist of translucent electrodes. Only the first electrode 101 is a translucent electrode. In this case, the light is extracted through the first electrode 101. Also, the second electrode 102 If the electrode is transparent, the light is extracted through the second electrode 102. When both electrode 101 and electrode 102 are translucent electrodes, light emission occurs. It passes through the first electrode 101 and the second electrode 102 and is extracted from both.

[0107] The layer provided between the first electrode 101 and the second electrode 102 is as described above. It is not limited to this. However, if the light-emitting region and the metal used in the electrodes or carrier injection layer are close together The first electrode 101 and the second electrode are positioned so as to suppress quenching caused by contact. A configuration is preferred in which a light-emitting region is provided at a location away from 102 where holes and electrons recombine.

[0108] Furthermore, the hole transport layer and electron transport layer in contact with the light-emitting layer 113, and especially the light emission in the light-emitting layer 113, are also important. The carrier transport layer in contact with the region is responsible for energy transfer from excitons generated in the light-emitting layer. In order to suppress this, the band gap is contained in the luminescent material that makes up the luminescent layer or in the luminescent layer. The material is composed of a material having a band gap larger than the band gap of the luminescent central material. It is preferable to do so.

[0109] The light-emitting element in this embodiment is fabricated on a substrate made of glass, plastic, or the like. That's all. As for the order of fabrication on the substrate, even if you stack them in order from the first electrode 101 side, The electrodes 102 and 2 may be stacked in order from the electrode 102 side. The light-emitting device forms one light-emitting element on one substrate. It is acceptable to have only one such light-emitting element, but it is also acceptable to form multiple light-emitting elements on a single substrate. By creating multiple of these, it is possible to create lighting devices with divided elements or passive matrix type light-emitting devices. It can be manufactured. Furthermore, a thin film can be applied to a substrate made of glass, plastic, etc. A transistor (TFT) is formed, and a light-emitting element is fabricated on an electrode electrically connected to the TFT. This may also be done. This allows for an active matrix that controls the driving of the light-emitting elements by the TFT. A light-emitting device of this type can be fabricated. The structure of the TFT is not particularly limited. (Example: Staggered TFT) It can be a TFT or an inverse staggered TFT. Also, regarding the crystallinity of the semiconductor used in the TFT... However, this is not particularly limited; amorphous semiconductors or crystalline semiconductors may be used. Furthermore, the driving circuit formed on the TFT substrate also consists of N-type and P-type TFTs. It may be either N-type TFT or P-type TFT, or it may consist of only one of them. That is also acceptable.

[0110] Furthermore, this embodiment can be appropriately combined with other embodiments.

[0111] (Embodiment 3) In this embodiment, a light-emitting device using the light-emitting elements described in Embodiment 1 and Embodiment 2 is provided. I will explain this.

[0112] In this embodiment, the light-emitting element described in Embodiment 1 and Embodiment 2 is used to create the element. The light-emitting device will be explained using Figure 6. Figure 6(A) is a top view showing the light-emitting device. Figure 6(B) is a cross-sectional view of Figure 6(A) cut along lines AB and CD. This light-emitting device The drive circuit section (source line drive circuit), shown by the dotted line, controls the emission of light from the light-emitting element. It includes a path (601), a pixel section (602), and a drive circuit section (gate line drive circuit) (603). , 604 is the sealing substrate, 625 is the desiccant, and 605 is the sealing material, surrounded by the sealing material 605 The inside of this structure is a space of 607.

[0113] The routing wiring 608 is connected to the source line drive circuit 601 and the gate line drive circuit 603. FPC (Flexible Printed Circuit) is a wiring used to transmit signals and serves as an external input terminal. (Lindt Circuit) Video signal, clock signal, start signal, reset signal from 609 Receives, etc. Note that only FPC is shown in the diagram here, but this FPC has print A circuit board (PWB) may be attached. The light-emitting device in this specification includes light-emitting This includes not only the device itself, but also the state in which the FPC or PWB is attached to it. do.

[0114] Next, the cross-sectional structure will be explained using Figure 6(B). The drive circuit is located on the element substrate 610. A section and a pixel section are formed, but here, the source line drive circuit 601 is the drive circuit section. This shows one of the pixels in the pixel section 602.

[0115] The source line drive circuit 601 uses an n-channel TFT 623 and a p-channel TFT 62 A CMOS circuit is formed by combining it with 4. In addition, the drive circuit is a variety of CMOS circuits It may also be formed using PMOS or NMOS circuits. In this embodiment, the substrate The image above shows a driver integrated with a drive circuit, but this is not always necessary; the drive circuit can be... It can also be formed on an external surface rather than on the substrate.

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

[0117] Furthermore, in order to ensure good coverage, the upper or lower end of the insulator 614 has a curvature. A curved surface is formed. For example, as the material for the insulator 614, a positive-type photosensitive material is used. When krill is used, the radius of curvature (0.2 μm to 3 μm) is only present at the upper end of the insulator 614. It is preferable to give it a curved surface. Also, as the insulator 614, a negative type photosensitive resin, Alternatively, any of the positive-type photosensitive resins can be used.

[0118] An EL layer 616 and a second electrode 617 are formed on the first electrode 613, respectively. Here, the material used for the first electrode 613 which functions as an anode is, work function It is desirable to use a material with a large ion content. For example, ITO film or silicon-containing ink Dium-tin oxide film, indium oxide film containing 2-20 wt% zinc oxide, titanium nitride film, In addition to single-layer films such as chromium films, tungsten films, Zn films, and Pt films, titanium nitride and aluminum Lamination with a film mainly composed of aluminum, titanium nitride film and aluminum film and titanium nitride A three-layer structure with a film can be used. Furthermore, a laminated structure can be used as a wiring resistor. It has low noise levels, provides good ohmic contact, and can even function as an anode. .

[0119] Furthermore, the EL layer 616 can be coated using a deposition method with a deposition mask, an inkjet method, or a spin coat. It is formed by various methods such as the law. The EL layer 616 is formed by Embodiment 1 and Embodiment 2 It includes the configuration described above. Furthermore, other materials constituting the EL layer 616 include: It may be a low-molecular-weight compound or a high-molecular-weight compound (including oligomers and dendrimers). .

[0120] Furthermore, the material used for the second electrode 617, which is formed on the EL layer 616 and functions as a cathode As for materials, materials with a low work function (Al, Mg, Li, Ca, or alloys of these) It is preferable to use a compound (such as MgAg, MgIn, AlLi, etc.). Note that the EL layer 616 If the light generated passes through the second electrode 617, the second electrode 617 is defined as having a film thickness A thin metal film and a transparent conductive film (ITO, indigo oxide containing 2-20 wt% zinc oxide) Lamination with indium tin oxide containing um and silicon, zinc oxide (ZnO), etc. is used. That's good.

[0121] The first electrode 613, the EL layer 616, and the second electrode 617 form a light-emitting element. The light-emitting element is the same as the light-emitting element described in Embodiment 1 and Embodiment 2. Oh, the pixel section is made up of multiple light-emitting elements, but the light-emitting device in this embodiment Now, let's look at the light-emitting elements described in Embodiment 1 and Embodiment 2, and the light-emitting elements having other configurations. It is acceptable for both elements to be included.

[0122] Furthermore, by bonding the sealing substrate 604 to the element substrate 610 with the sealing material 605, A light-emitting element is placed in the space 607 surrounded by the element substrate 610, the sealing substrate 604, and the sealing material 605. The structure is equipped with child 618. Furthermore, the space 607 is filled with a filler material. In addition to cases where an inert gas (such as nitrogen or argon) is filled, it is also filled with sealant 605. In some cases, a recess is formed in the sealing substrate and a desiccant 625 is placed there, which reduces the effects of moisture. This configuration is preferable because it can suppress deterioration caused by [unspecified factor].

[0123] Furthermore, it is preferable to use epoxy resin or glass frit for the sealant 605. Furthermore, it is desirable that these materials be as impermeable to moisture and oxygen as possible. In addition to glass substrates and quartz substrates, FRP (Fiberg) is also used as a material for the encapsulating substrate 604. Glass-reinforced plastics), PVF (polyvinyl fluoride) ), a plastic substrate made of polyester or acrylic can be used.

[0124] As described above, the light-emitting elements described in Embodiment 1 and Embodiment 2 are used to create the following: A light-emitting device can be obtained.

[0125] The light-emitting device in this embodiment has the light-emitting elements described in Embodiment 1 and Embodiment 2. Because it is used, a light-emitting device with good characteristics can be obtained. Specifically, the implementation The light-emitting element shown in Embodiment 1 and Embodiment 2 has good luminous efficiency and reduces power consumption. It can be made into a light-emitting device. Furthermore, it is a light-emitting element with a low driving voltage, A light-emitting device can be obtained.

[0126] As described above, this embodiment describes an active matrix type light-emitting device. However, a passive matrix type light-emitting device may also be used. Figure 7 shows the application of the present invention. The passive matrix type light-emitting device fabricated by [method] is shown. Figure 7(A) shows the light-emitting device. The perspective view shown, Figure 7(B), is a cross-sectional view obtained by cutting Figure 7(A) along the X and Y lines. In Figure 7, On the substrate 951, an EL layer 955 is provided between the electrode 952 and the electrode 956. The end of the electrode 952 is covered with an insulating layer 953. And on the insulating layer 953 is a partition layer 9 54 is provided. The side walls of the partition layer 954 are such that as they get closer to the substrate surface, one side wall It has a slope such that the distance between it and the other side wall becomes narrower. In other words, the short of the partition wall layer 954 The cross-section in the lateral direction is trapezoidal, with the base (facing the same direction as the surface direction of the insulating layer 953) and insulating The side in contact with layer 953 is the upper side (which faces the same direction as the plane direction of insulating layer 953, and the insulating layer 9 It is shorter than the side that does not touch 53. In this way, by providing the partition layer 954, static electricity, etc. This can prevent defects in the light-emitting element caused by this process. Furthermore, it can be used in passive matrix type light-emitting devices. In addition, the light-emitting element described in Embodiments 1 and 2 operates at a low driving voltage. This allows for operation with low power consumption. Furthermore, Embodiment 1 and the implementation By having the light-emitting element described in Embodiment 2, it is possible to create a highly reliable light-emitting device. Yes.

[0127] Furthermore, in order to achieve full-color display, the light from the light-emitting element must be able to escape to the outside of the light-emitting device. A colored layer or color conversion layer can be placed on the optical path. Examples of a light-emitting device with a luminescent coating are shown in Figures 8(A) and (B). Figure 8(A) shows substrate 1001, Base insulating film 1002, gate insulating film 1003, gate electrodes 1006, 1007, 1008 , first interlayer insulating film 1020, second interlayer insulating film 1021, peripheral portion 1042, pixel portion 10 40, drive circuit section 1041, first electrodes 1024W, 1024R, 1024G of the light-emitting element , 1024B, partition wall 1025, layer containing organic compound 1028, second electrode 10 of the light-emitting element Figure 29 shows the encapsulation substrate 1031, sealing material 1032, etc. Also, the colored layer (red) The colored layer 1034R (green colored layer 1034G, blue colored layer 1034B) is on a transparent substrate. It is provided at 1033. Alternatively, a black layer (black matrix) 1035 may also be provided. i. The transparent substrate 1033, which has a colored layer and a black layer, is aligned and placed on the substrate 1001 It is fixed in place. The colored layer and the black layer are covered with an overcoat layer 1036. Furthermore, in this embodiment, there is a light-emitting layer through which light does not pass through the colored layer and exits to the outside, and each color There is a colored layer and an emissive layer that allows light to pass through to the outside. Light that does not pass through the colored layer is white, and the colored layer... Since the transmitted light is red, blue, and green, images can be represented using pixels of these four colors.

[0128] Furthermore, in the light-emitting device described above, light is taken to the substrate 1001 on which the TFT is formed. Although the light-emitting device was designed with a bottom-emission structure, the light-emitting element was directed towards the sealing substrate 1031. It can also be used as a light-emitting device with an extraction structure (top emission type). Top emission type Figure 9 shows a cross-sectional view of the light-emitting device. In this case, the substrate 1001 is a substrate that does not transmit light. It is possible. Until the connecting electrode that connects the TFT and the anode of the light-emitting element is fabricated, the bottom It is formed in the same way as an emission-type light-emitting device. Then, the third interlayer insulating film 1037 is attached to the electrode. It covers and forms 1022. This third interlayer insulating film 1037 plays a role in planarization. This is also good. The third interlayer insulating film 1037 may be made of the same material as the second interlayer insulating film, as well as other known materials. It can be formed using a material.

[0129] The first electrodes 1024W, 1024R, 1024G, and 1024B of the light-emitting element are positive here. This is referred to as the pole, but it can also be the cathode. Furthermore, top-emission type light emission as shown in Figure 9 is also possible. In the case of a device, it is preferable that the first electrode be a reflective electrode. Layer 10 containing an organic compound The configuration of 28 is as described in Embodiment 1 and Embodiment 2, and white light emission is The device structure will be such that the desired result is obtained. For a configuration that produces white light emission, two EL layers will be used. In this case, blue light is emitted from the light-emitting layer of one EL layer, and light is emitted from the light-emitting layer of the other EL layer. A configuration in which orange light is obtained from the layer, or in which blue light is obtained from the light-emitting layer of one of the EL layers, One possible configuration is one in which red and green light can be obtained from the light-emitting layer of the other EL layer. It is possible. Also, when three EL layers are used, red, green, and blue light can be emitted from each light-emitting layer. By enabling the emission of light, a light-emitting element that emits white light can be obtained. If the configurations shown in Embodiment 1 and Embodiment 2 are applied, white light emission can be obtained. Of course, this is not the only possible configuration.

[0130] The colored layer is placed on the optical path through which light from the light-emitting element exits to the outside. A bottle like the one in Figure 8(A) In the case of a emission-type light-emitting device, a transparent substrate 1033 is covered with a colored layer 1034R, 1034 It can be provided by providing G, 1034B and fixing it to the substrate 1001. As shown in Figure 8(B), the colored layer is placed between the gate insulating film 1003 and the first interlayer insulating film 1020. It may also be configured to be installed in the following way. If the structure is a top emission as shown in Figure 9, the colored layer (red A seal with a colored layer 1034R, a green colored layer 1034G, and a blue colored layer 1034B. Sealing can also be performed with a sealing substrate 1031. The sealing substrate 1031 has a position between the pixels. A black layer (black matrix) 1035 may be provided. A colored layer (red Colored layer 1034R, green colored layer 1034G, blue colored layer 1034B) and black layer (black The black matrix 1035 may be covered by an overcoat layer 1036. Furthermore, the sealing substrate 1031 shall be a light-transmitting substrate.

[0131] When a voltage is applied between the pair of electrodes of the resulting organic light-emitting element, a white light-emitting region 10 is produced. 44W can be obtained. Also, by combining it with a colored layer, a red light-emitting region 1044R can be obtained. A blue light-emitting region 1044B and a green light-emitting region 1044G are obtained. Since the light-emitting device uses the light-emitting elements described in Embodiment 1 and Embodiment 2, This makes it possible to create light-emitting devices that require little power.

[0132] Furthermore, while we have shown an example of full-color display using four colors—red, green, blue, and white—this is not particularly limited to... Alternatively, full-color display may be performed using three colors: red, green, and blue.

[0133] Furthermore, this embodiment can be freely combined with other embodiments.

[0134] (Embodiment 4) In this embodiment, the light-emitting elements described in Embodiment 1 and Embodiment 2 are used as an illumination device. An example of its use will be explained with reference to Figure 10. Figure 10(B) is a top view of the lighting device, Figure 10( A) is a cross-sectional view of ef in Figure 10(B).

[0135] The lighting device in this embodiment has a light-transmitting substrate 400 which is a support, and a first An electrode 401 is formed. The first electrode 401 is the first electrode 1 in Embodiment 3. This corresponds to 01.

[0136] An auxiliary electrode 402 is provided on the first electrode 401. In this embodiment, the first Since we have shown an example where light emission is extracted from the electrode 401 side, the first electrode 401 is made of a translucent material. Formed by the material. The auxiliary electrode 402 is provided to compensate for the low conductivity of the translucent material. This is caused by a voltage drop due to the high resistance of the first electrode 401 within the light-emitting surface. It has the function of suppressing brightness unevenness. The auxiliary electrode 402 is made of at least the material of the first electrode 401. Formed using a material with higher conductivity than the material, preferably a material with high conductivity such as aluminum. It is preferable to form it using a thick material. Note that the auxiliary electrode 402 is in contact with the first electrode 401. It is preferable that the surface other than the part to be removed is covered with an insulating layer. This is because it can be removed. This is to suppress light emission from the upper part of the auxiliary electrode 402, reduce reactive current, and improve power efficiency. This is to suppress the decrease in rate. Furthermore, the second electrode 404 is formed simultaneously with the formation of the auxiliary electrode 402. A pad 412 may be formed to supply voltage to it.

[0137] An EL layer 403 is formed on the first electrode 401 and the auxiliary electrode 402. Embodiment 3 has the configuration described in Embodiment 1 and Embodiment 2. Please refer to the relevant description. Note that the EL layer 403 is viewed from a planar perspective than the first electrode 401. Making it slightly larger suppresses short circuits between the first electrode 401 and the second electrode 404. This configuration is preferable because it can also serve as an insulating layer.

[0138] The EL layer 403 is covered to form the second electrode 404. The second electrode 404 is in Embodiment 3 It corresponds to the second electrode 102 in and has a similar configuration. In this embodiment, Since the light is extracted from the first electrode 401 side, the second electrode 404 is made of a material with high reflectivity. It is preferable that it is formed in this manner. In this embodiment, the second electrode 404 is the pad 4 Voltage will be supplied by connecting to 12.

[0139] The above describes the first electrode 401, the EL layer 403, and the second electrode 404 (and auxiliary electrode 402) The lighting device shown in this embodiment has a light-emitting element having ). Because it is a light-emitting element with a high efficiency, the lighting device in this embodiment is a lighting device with low power consumption. It can be placed in this position. Furthermore, since this light-emitting element is a highly reliable light-emitting element, The lighting device in this embodiment can be a highly reliable lighting device.

[0140] The light-emitting element having the above configuration is sealed to a substrate 407 using sealing materials 405 and 406. The lighting device is completed by attaching and sealing it. Either sealing material 405 or 406 is used. Either way is fine. Also, a desiccant can be mixed into the inner sealant 406, and this This allows for greater moisture absorption, leading to improved reliability.

[0141] Furthermore, the pad 412, the first electrode 401 and a portion of the auxiliary electrode 402 are sealed with sealing material 405. By extending it outside of 406, it can be used as an external input terminal. An IC chip 420 with a converter or other components may be placed on top of it.

[0142] As described above, the lighting device described in this embodiment has an EL element as described in Embodiment 1 and Embodiment 2. Because it has the described light-emitting element, it can be used as a lighting device with low power consumption. This allows for lighting devices with low drive voltages. Furthermore, it enables highly reliable lighting devices. It is possible.

[0143] (Embodiment 5) This embodiment includes, as a part, the light-emitting elements described in Embodiments 1 and 2. Examples of electronic devices will be described. The light-emitting elements described in Embodiment 1 and Embodiment 2 emit light. This light-emitting element has good efficiency and reduced power consumption. As a result, the following is described in this embodiment. The electronic device can be an electronic device having a light-emitting part with reduced power consumption. Furthermore, the light-emitting elements described in Embodiment 1 and Embodiment 2 are light-emitting elements with a low driving voltage. Therefore, it is possible to use electronic devices with low drive voltage.

[0144] Examples of electronic devices to which the above light-emitting element is applied include television equipment (television, or television). (also called a revision receiver), monitors for computers, digital cameras, digital Video cameras, digital photo frames, mobile phones (also called mobile phones or mobile phone devices) ), portable game consoles, personal digital assistants, sound playback devices, large game machines such as pachinko machines, etc. These include [examples of electronic devices]. Specific examples of these electronic devices are shown below.

[0145] Figure 11(A) shows an example of a television system. The television system consists of a housing 71 The display unit 7103 is incorporated into 01. Also, here the stand 7105 is used to form the enclosure. This shows the configuration supporting the body 7101. The display unit 7103 can display images. It is possible, and the display unit 7103 aggregates the light-emitting elements described in Embodiment 1 and Embodiment 2. It is configured by arranging in a rix-like pattern. This light-emitting element is designed to have good luminescence efficiency. This is possible. Furthermore, it is possible to create a light-emitting element with a low driving voltage. Also, the lifespan It is possible to create a light-emitting element with a long lifespan. Therefore, the display unit composed of this light-emitting element Television equipment having 7103 is to be television equipment with reduced power consumption. This is possible. Furthermore, it is possible to create a television system with a low drive voltage. Also, This can result in a highly reliable television system.

[0146] The television equipment can be operated using the control switches on the housing 7101 or a separate remote control. This can be done using the device 7110. The remote control device 7110 has an operation key 7109. This allows you to control the channel and volume, and the video displayed on the display unit 7103 It can be operated. Also, the remote control unit 7110 A display unit 7107 that displays the information output from the unit may also be provided.

[0147] The television system shall consist of a receiver, modem, etc. It can receive television broadcasts, and also communicate via wired or wireless connection through a modem. By connecting to a network, one-way (sender to receiver) or two-way (sender to receiver) communication is possible. It is also possible to communicate information between recipients, or between recipients themselves.

[0148] Figure 11(B1) is a computer, consisting of a main unit 7201, a casing 7202, a display unit 7203, Includes keyboard 7204, external connection port 7205, pointing device 7206, etc. Hmm. This computer is similar to the one described in Embodiment 2 or Embodiment 3. It is manufactured by arranging light-emitting elements in a matrix and using them in the display unit 7203. Figure 1 The computer in 1(B1) may take the form shown in Figure 11(B2). 2) The computer replaces the keyboard 7204 and the pointing device 7206. A second display unit 7210 is provided. The second display unit 7210 is a touch panel type. The input display shown on the second display unit 7210 is operated with a finger or a special pen. Input can be made by doing so. Also, the second display unit 7210 is not only for input display. It is also possible to display other images. Furthermore, the display unit 7203 is a touch panel. It's fine to have it. The two screens are connected by a hinge, which makes storage and transport easier. This also prevents problems such as scratches or damage to the screen. The child can be made into a light-emitting element with good luminescence efficiency. Therefore, the child is made into a light-emitting element. A computer having a display unit 7203 is a computer with reduced power consumption. It is possible.

[0149] Figure 11(C) shows a portable gaming machine, which consists of two casings, casing 7301 and casing 7302. It is connected by a connecting part 7303 so that it can be opened and closed. The housing 7301 is implemented A display made by arranging the light-emitting elements described in Embodiment 1 and Embodiment 2 in a matrix. The unit 7304 is incorporated, and the display unit 7305 is incorporated into the housing 7302. Also, The portable gaming machine shown in Figure 11(C) also includes a speaker unit 7306 and a recording medium insertion unit 73 07. LED lamp 7308, input means (operation key 7309, connection terminal 7310, sensor) 7311 (force, displacement, position, velocity, acceleration, angular velocity, rotational speed, distance, light, liquid, magnetism, temperature) , chemical substances, sound, time, hardness, electric field, electric current, voltage, power, radiation, flow rate, humidity, gradient, Equipped with functions to measure vibration, odor, or infrared radiation, a microphone (7312), etc. Of course, the configuration of portable gaming machines is not limited to those described above, and at least the display unit Both 7304 and the display unit 7305, or one of them, are described in Embodiment 1 and Embodiment 2. It is sufficient to use a display unit made by arranging the mounted light-emitting elements in a matrix, and other attached The configuration can be configured with additional equipment as appropriate. The portable gaming machine shown in Figure 11(C) is Functions that read programs or data recorded on a recording medium and display them on the display unit, It has the function of sharing information by communicating wirelessly with other portable gaming machines. (See Figure 11(C)) The functions of the portable gaming machine shown are not limited to those described, and it can have a variety of functions. A portable gaming machine having the display unit 7304 as described above uses the following in the display unit 7304 Because the light-emitting element has good luminous efficiency, it can be used in portable gaming machines with reduced power consumption. This is possible. In addition, the light-emitting elements used in the display unit 7304 can be driven with a low drive voltage. Because it can be operated, it can be made into a portable gaming machine with a low drive voltage. Furthermore, since the light-emitting element used in the display unit 7304 is a long-life light-emitting element, It can be made into a highly reliable portable gaming machine.

[0150] Figure 11(D) shows an example of a mobile phone. The mobile phone is built into the housing 7401. In addition to the display unit 7402, there are operation buttons 7403, an external connection port 7404, and a speaker 7 It is equipped with 405, microphone 7406, etc. Note that the mobile phone 7400 is in Embodiment 1 and a display unit 7402 manufactured by arranging the light-emitting elements described in Embodiment 2 in a matrix. It has the following characteristics. This light-emitting element can be made into a light-emitting element with good luminous efficiency. This makes it possible to create a light-emitting element with a low driving voltage. Furthermore, it allows for a long lifespan. Therefore, it is possible to have a portable cell phone with a display unit 7402 composed of the light-emitting element. The handset can be a mobile phone with reduced power consumption. Also, a mobile phone with a low operating voltage can be used. It can be used as a mobile phone. Furthermore, it can be used as a highly reliable mobile phone. ru.

[0151] The mobile phone shown in Figure 11(D) allows users to input information by touching the display unit 7402 with their finger or other object. It can also be configured to allow for making phone calls or creating emails. Operations such as performing actions can be carried out by touching the display unit 7402 with a finger or the like.

[0152] The display unit 7402 has three main modes. The first is a display that primarily displays images. The first mode is display mode, the second is input mode which is mainly for inputting information such as characters. The third is display mode. This is a display + input mode, which is a combination of two modes: display mode and input mode.

[0153] For example, when making a phone call or composing an email, the display unit 7402 is used for text input. In this case, the primary text input mode should be used, and you should perform the input operation for the characters displayed on the screen. It is preferable to display a keyboard or number buttons on most of the screen of the display unit 7402. It seems so.

[0154] Furthermore, the mobile phone has sensors inside that detect tilt, such as a gyroscope and an accelerometer. By providing an output device, the orientation of the mobile phone (vertical or horizontal) is determined, and the image of the display unit 7402 is displayed accordingly. The display can be configured to switch automatically.

[0155] Furthermore, screen modes can be switched by touching the display unit 7402 or by operating the housing 7401. This is done by operating button 7403. Also, the type of image displayed on display unit 7402 Therefore, it is also possible to switch between them. For example, the image signal displayed on the display unit is a video signal. Switch to display mode if it's data, or to input mode if it's text data.

[0156] Furthermore, in input mode, the signal detected by the optical sensor of the display unit 7402 is detected and displayed If there is no input via touch operation on unit 7402 for a certain period of time, the screen mode will be changed to input mode. You may also control the system to switch from that display mode to a different mode.

[0157] The display unit 7402 can also function as an image sensor. For example, the display unit 74 By touching device 02 with the palm or fingers, the user can be authenticated by capturing images of their palm print, fingerprints, etc. Furthermore, the display unit may have a backlight that emits near-infrared light or a sensing light that emits near-infrared light. Using the appropriate source, it is also possible to image finger veins, palmar veins, and other veins.

[0158] The configuration shown in this embodiment is a combination of the configurations shown in Embodiments 1 to 4 as appropriate. They can be used together.

[0159] As described above, the scope of application of the light-emitting device equipped with the light-emitting element described in Embodiment 1 and Embodiment 2 Its applications are extremely broad, making it possible to apply this light-emitting device to electronic equipment in all fields. By using the light-emitting elements described in Embodiment 1 and Embodiment 2, power consumption can be reduced. You can obtain advanced electronic devices.

[0160] Figure 12 shows the light-emitting elements described in Embodiments 1 and 2 applied to a backlight. This is an example of a liquid crystal display device. The liquid crystal display device shown in Figure 12 consists of a housing 901 and a liquid crystal layer 902 The liquid crystal layer 902 has a backlight unit 903 and a housing 904, and the driver IC 90 It is connected to 5. Also, the backlight unit 903 has the same configuration as in Embodiment 1 and the embodiment. The light-emitting element described in Form 2 is used, and current is supplied via terminal 906.

[0161] The light-emitting elements described in Embodiments 1 and 2 are applied to the backlight of a liquid crystal display device. As a result, a backlight with reduced power consumption can be obtained. Also, in Embodiment 2 By using the described light-emitting element, a surface-emitting illumination device can be fabricated, and it is also possible to scale it up to a large area. This makes it possible to increase the backlight area, and also to increase the liquid crystal display area. Furthermore, the light-emitting device to which the light-emitting element described in Embodiment 2 is applied has a thickness compared to the conventional device. Because it can be made smaller, it also becomes possible to make display devices thinner.

[0162] Figure 13 shows the light-emitting element described in Embodiment 1 and Embodiment 2, which is an electrical lighting device. This is an example of its use in a lamp. The lamp shown in Figure 13 consists of a housing 2001 and a light source 2002 The device has the light-emitting device described in Embodiment 4, and the light-emitting device described in Embodiment 4 is used as the light source 2002.

[0163] Figure 14 shows the light-emitting elements described in Embodiment 1 and Embodiment 2 in an indoor lighting device 300. Examples of use as 1 and display device 3002 are described in Embodiments 1 and 2. Because the light-emitting element is a light-emitting element with reduced power consumption, it is a lighting device with reduced power consumption. This can be done. Furthermore, the light-emitting elements described in Embodiments 1 and 2 can be made to have a large area. Because this is possible, it can be used as a large-area lighting device. Also, Embodiment 1 and The light-emitting element described in Embodiment 2 is thin and can be used as a thinned lighting device. This becomes possible.

[0164] The light-emitting elements described in Embodiments 1 and 2 are used in automobile windshields and dashcams. It can also be mounted on a board. Figure 15 shows the light-emitting element described in Embodiment 2 on an automobile. This shows one application to the windshield and dashboard. (Display 5000 to Display 5005) This is a display provided using the light-emitting elements described in Embodiment 1 and Embodiment 2.

[0165] Display 5000 and Display 5001 are provided on the windshield of an automobile in Embodiment 1 and This is a display device equipped with the light-emitting element described in Embodiment 2. Embodiments 1 and 2 The light-emitting element described in 2 is made by fabricating the first electrode and the second electrode with light-transmitting electrodes. Therefore, it can be used as a display device that is transparent, allowing the other side to be seen through, a so-called see-through display device. If the display is see-through, even if it is installed on the windshield of a car, the field of view will be obstructed. It can be installed without obstruction. Furthermore, transistors and other components for driving the device are provided. In such cases, organic transistors made from organic semiconductor materials, or transistors using oxide semiconductors, are used. It is best to use a translucent transistor, such as a sta.

[0166] Display 5002 is a light-emitting element according to Embodiment 1 and Embodiment 2 provided on the pillar portion. This is a display device equipped with a child. Display 5002 shows images from an imaging device installed on the vehicle body. By projecting this image, the view obstructed by the pillar can be compensated for. The display 5003 located on the dashboard shows the view obstructed by the vehicle body, By displaying images from imaging devices located on the outside, blind spots are compensated for, and safety is improved. It can be enhanced. By projecting images in a way that complements the unseen parts, it can be made more natural. Safety checks can be performed without any sense of unease.

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

[0168] The light-emitting elements described in Embodiments 1 and 2 are light-emitting elements with high luminous efficiency. This is possible. Furthermore, it allows for the creation of light-emitting elements with low power consumption. Therefore, display 5 Even if you have many large screens like 000 or 5005, it puts a load on the battery. Because it is less likely to cause problems and can be used comfortably, Embodiments 1 and 2 are preferred. The light-emitting device or lighting device using the described light-emitting element is a vehicle-mounted light-emitting device or lighting device. It can be used suitably.

[0169] Figures 16(A) and 16(B) show examples of foldable tablet devices. 6(A) is in the open state, and the tablet terminal consists of the housing 9630 and the display unit 9631a Display unit 9631b, display mode switching switch 9034, power switch 9035, It has a power mode selector switch 9036, a fastener 9033, and an operation switch 9038. The tablet terminal is equipped with the light-emitting elements described in Embodiment 1 and Embodiment 2. By using the light-emitting device in either or both of the display unit 9631a and the display unit 9631b It is made.

[0170] The display unit 9631a can be partially designated as a touch panel area 9632a, and the display will be Data can be entered by touching the operation key 9637. Note that the display unit 963 In 1a, as an example, one half of the area has a display-only function, and the other half of the area The diagram shows a configuration that includes touch panel functionality, but is not limited to this configuration. Display unit 963 The entire area of ​​1a may also be configured to have touch panel functionality. For example, the display unit 96 The entire surface of 31a is used as a touch panel with keyboard buttons, and the display unit 9631b is displayed. It can be used as a screen.

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

[0172] Furthermore, if you touch the touch panel area 9632a and the touch panel area 9632b simultaneously... You can also input "chi".

[0173] Additionally, the display mode switch 9034 selects the display orientation, such as portrait or landscape. You can switch between modes, such as black and white or color display. Power saving mode switching. Switch 9036 is detected by an optical sensor built into the tablet device when it is in use. The display brightness can be optimized according to the amount of light. In addition to sensors, other detection devices such as gyroscopes, accelerometers, and other sensors that detect tilt It may be built-in.

[0174] Furthermore, Figure 16(A) shows an example where the display area of ​​display unit 9631b and display unit 9631a are the same. However, this is not particularly limited, and one size may be different from the other. The quality of the display may also differ. For example, one display panel can provide a higher resolution display than the other. You can also use "ru".

[0175] Figure 16(B) shows the closed state, and in this embodiment, the tablet terminal has a casing. Body 9630, solar cell 9633, charge / discharge control circuit 9634, battery 9635, DCD An example is shown that includes a C converter 9636. Note that in Figure 16(B), the charge / discharge control circuit 963 As an example of 4, consider a configuration having a battery 9635 and a DC-DC converter 9636. It is showing.

[0176] Note that the tablet device is foldable, so when not in use, the casing 9630 is closed. This can be done. Therefore, the display units 9631a and 9631b can be protected. We can provide tablet devices that are highly durable and reliable from a long-term use perspective.

[0177] In addition, the tablet devices shown in Figures 16(A) and 16(B) are also available in various forms. Functions to display information (still images, videos, text images, etc.), calendar, date or time, etc. A function that displays information on the display unit, and a touch input operation or editing of the information displayed on the display unit. It has input capabilities, and functions to control processing through various software (programs), etc. It is possible.

[0178] The touch panel is powered by a solar cell 9633 mounted on the surface of the tablet device. It can be supplied to the display unit or the video signal processing unit, etc. Note that the solar cell 9633 is It can be provided on one or both sides of the housing 9630, and the battery 9635 can be charged efficiently. This configuration can be implemented in this way.

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

[0180] First, let's explain an example of how the solar cell 9633 operates when generating electricity using ambient light. The electricity generated by the solar panel is converted to DC to provide the voltage needed to charge the 9635 battery. The DC converter 9636 performs either a boost or a buck. Then, the display unit 9631 operates as follows: When power charged by solar cell 9633 is used, turn on switch SW1. The converter 9638 will boost or lower the voltage to the required level for the display unit 9631. When you do not want to display anything on the display unit 9631, turn SW1 off and turn SW2 on. The configuration should be designed to charge the 9635 battery.

[0181] While the solar cell 9633 is shown as an example of a power generation method, the power generation method is not particularly limited. It is not limited to other power generation devices such as piezoelectric elements (piezoelectric elements) and thermoelectric elements (Peltier elements). The battery 9635 may be charged by some means. A contactless power transmission module that charges by sending and receiving power, or a combination of other charging methods. This configuration is also acceptable, and it does not require a means of generating electricity.

[0182] Furthermore, if the above-mentioned display unit 9631 is included, it is a tablet terminal with the shape shown in Figure 16. Not limited to this. [Examples]

[0183] In this embodiment, compounds (1) to (3) described in Embodiment 1 are used in one of the present inventions. The light-emitting element 1 and light-emitting element 2 corresponding to the embodiment will be described. Light-emitting element in this embodiment So, the first light-emitting layer 113B, the second light-emitting layer 113G, and the third light-emitting layer 113R are used. As phosphorescent compounds, we have compound (1) and compound (2) described in Embodiment 1, respectively. ) and compound (3) are used, so the respective emission wavelengths (F(λ)) and ε(λ)λ 4 of The relationship is as described in Figure 5 of Embodiment 1.

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

[0185] [ka]

[0186] The following describes the method for manufacturing the light-emitting element 1 and light-emitting element 2 in this embodiment.

[0187] (Method for fabricating light-emitting element 1) First, indium tin oxide (ITSO) containing silicon oxide is sputtered onto a glass substrate. The first electrode 101 was formed by depositing a film using the 3D method. The film thickness was set to 110 nm. The area was set to 2 mm x 2 mm. Here, the first electrode 101 functions as the anode of the light-emitting element. It is an electrode.

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

[0189] Then, 10 -4 A substrate is introduced into a vacuum deposition apparatus where the internal pressure is reduced to approximately Pa, and then vacuum deposition is performed. After vacuum firing at 170°C for 30 minutes in the heating chamber of the apparatus, the substrate is left for approximately 30 minutes. It was allowed to cool.

[0190] Next, the first electrode 101 is formed such that the surface on which the first electrode 101 is formed faces downwards. The prepared substrate is fixed to a substrate holder provided inside the vacuum deposition apparatus, 10 -4 Reduced to approximately Pa After applying pressure, the above structural formula (i) is applied to the first electrode 101 by a vapor deposition method using resistance heating. 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophen By co-depositing (abbreviation: DBT3P-II) and molybdenum(VI) oxide, holes An injection layer 111 was formed. Its film thickness was set to 40 nm, and it was made of DBT3P-II and molybdenum oxide. The ratio of ingredients is adjusted to be 4:2 by weight (=DBT3P-II:molybdenum oxide). Co-evaporation is a method of vapor deposition in which multiple evaporation sources are used to deposit vapor simultaneously within a single processing chamber. It is the law.

[0191] Next, on the hole injection layer 111, 4-phenyl-4'-( represented by the above structural formula (ii) 9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP) 20 A film was deposited to a thickness of nm, forming a hole transport layer 112.

[0192] Furthermore, on the hole transport layer 112, 2-[3-(dibenzo) represented by the above structural formula (iii) is added. Thiofen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBT) PDBq-II) and 4-phenyl-4'-(9-phenyl represented by the above structural formula (iv) Lu-9H-carbazole-3-yl)triphenylamine (abbreviation: PCBA1BP), The above structural formula (v) represents bis(2,3,5-triphenylpyrazinate)(dipivaloy). Lumetanato Iridium(III) (Abbreviation: [Ir(tppr)2(dpm)]) (Chemical Compound) Object (3)) and the weight ratio 0.5:0.5:0.05 (=2mDBTPDBq-II:PC Co-deposited at 10 nm so that BA1BP:[Ir(tppr)2(dpm)]) and the third After fabricating the light-emitting layer 113R, 2mDBTPDBq-II and PCBA1BP and the above structure (Acetylacetonate)bis(6-tert-butyl-4-phenyl) Iridium(III) (abbreviation: [Ir(tBuppm)2(acac)) ])(compound (2)) and are mixed in a weight ratio of 0.5:0.5:0.05 (=2mDBTPDBq -II:PCBA1BP:[Ir(tBuppm)2(acac)]) so that 5 nm co-deposited to form a second light-emitting layer 113G, and further represented by the above structural formula (vii) 3,5-Bis[3-(9H-carbazole-9-yl)phenyl]pyridine (abbreviation: 3 5DCzPPy) and the 3,3'-bis(9-phenyl-) represented by the above structural formula (viii) 9H-carbazole) (abbreviation: PCCP) and tris{2- represented by the above structural formula (ix) [5-(2-methylphenyl)-4-(2,6-dimethylphenyl)-4H-1,2,4 -triazole-3-yl-κN2]phenyl-κC}iridium(III) (abbreviation:[ Ir(mpptz-dmp)3)(compound (1)) and in a weight ratio of 0.5:0.5:0 It will be .06 (=35DCzPPy:PCCP:[Ir(mpptz-dmp)3]). A 30nm layer of sea urchin was co-deposited to form the first light-emitting layer 113B, and then the light-emitting layer 113 was formed.

[0193] Note that 2mDBTPDBq-II and PCBA1BP, and 35DCzPPy and PCCP are... Each forms an excited complex. Furthermore, 2mDBTPDBq-II has electron transport properties, and PC BA1BP has hole transport properties, and these are included in a ratio of 0.5:0.5. Therefore, the second light-emitting layer 113G and the third light-emitting layer 113R are hole-transporting. Furthermore, 35DCzPPy has electron transport properties, and PCCP has hole transport properties. By incorporating these in a ratio of 0.5:0.5, the first light-emitting layer 113B enables electron transport. It is a sexual thing.

[0194] Subsequently, 2-[3-(dibenzothiophene represented by the above structural formula (x)) is placed on the light-emitting layer 113. -4-yl)phenyl]-1-phenyl-1H-benzoimidazole (abbreviation: mDBTB) Im-II) is deposited to a thickness of 10 nm, and further, the above structural formula (xi) is used. Bathophenanthroline (abbreviated as BPhen) is deposited to a thickness of 20 nm, and electron transport A transport layer 114 was formed.

[0195] After forming the electron transport layer 114, lithium fluoride (LiF) is then applied to a thickness of 1 nm. A layer is deposited to form an electron injection layer 115, and finally, a second electrode 1 that functions as a cathode is formed. As O2, aluminum is deposited to a film thickness of 200 nm, thus in this embodiment A light-emitting element 1 was fabricated.

[0196] In the vapor deposition process described above, resistance heating was used for all deposition steps.

[0197] (Method for fabricating light-emitting element 2) The light-emitting element 2 is configured such that the film thickness of the second light-emitting layer 113G in the light-emitting element 1 is 10 nm. Aside from the formation of the element, it was manufactured using the same configuration and process as the light-emitting element 1.

[0198] The light-emitting element 1 and light-emitting element 2 are placed inside a glove box in a nitrogen atmosphere, and the light-emitting elements are large The process of sealing the element with a glass substrate to prevent exposure to the elements (applying a sealing material around the element, After heat treatment at 80°C for 1 hour during sealing, the reliability of these light-emitting elements was measured. Yes, it was done. The measurements were taken at room temperature (in an atmosphere maintained at 25°C).

[0199] Figure 17 shows the current density-luminance characteristics of light-emitting element 1 and light-emitting element 2, and Figure 1 shows the luminance-current efficiency characteristics. In Figure 8, the voltage-luminance characteristics are shown in Figure 19, the luminance-chromaticity characteristics in Figure 20, and the luminance-power efficiency characteristics are shown in Figure 20. Figure 21 shows the luminance-external quantum efficiency characteristics, Figure 22 shows the characteristics, and Figure 23 shows the emission spectrum.

[0200] As described above, the light-emitting element 1 has a practical brightness of 1000 cd / m². 2 Current efficiency in the vicinity is 47 It exhibits very good characteristics with a cd / A ratio, an external quantum efficiency of 22%, and a power efficiency of 32 lm / W. It was found that the emitted color is 2930K incandescent color, and the average color rendering index Ra is 91.7. It was also found to exhibit good color rendering. The light-emitting element 2 has a practical brightness of 1000 cd / m². 2 Attached In recent times, it has an extremely high current efficiency of 52 cd / A, an external quantum efficiency of 22%, and a power efficiency of 36 lm / W. It was found to exhibit good efficiency. Figure 20 shows a light-emitting element according to one embodiment of the present invention. It can also be seen that light-emitting elements 1 and 2 have the characteristic of having little luminance dependence on chromaticity.

[0201] Furthermore, the carrier recombination regions of light-emitting elements 1 and 2 are determined by the transport properties of each light-emitting layer. This is near the interface between the first light-emitting layer 113B and the second light-emitting layer 113G, but the second light-emitting layer 113G Both the light-emitting element 1, which has a wavelength of 5 nm, and the light-emitting element 2, which has a second light-emitting layer 113G of 10 nm The third light-emitting layer 113R emits sufficient light. Also, the first light-emitting layer 113B to the third Light from the light-emitting material contained in each of the three light-emitting layers 113R is clearly visible in the spectrum. This indicates that the transfer of excitation energy is occurring effectively and in a balanced manner. [Examples]

[0202] This embodiment is a light-emitting element (light-emitting element) of the present invention having a configuration different from that of Example 1. Let's explain child 3). The light-emitting element 3 is the second compound used in Example 1, [Ir(t A phosphorescent compound that exhibits a yellow emission color instead of Buppm)2(acac) Compound (4) (bis{2-[5-methyl-6-(2-methylphenyl)-4-pyrimidinyl -κN3]phenyl-κC}(2,4-pentanedionato-κ 2 O,O') Iridium ( III) (abbreviation: [Ir(mpmppm)2(acac)])) is a light-emitting element that uses [Ir(mpmppm)2(acac)])). Note that for other substances used in the light-emitting element 3, the same substances as those in the light-emitting element 1 and the light-emitting element 2 in Example 1 were used.

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

[0204] [Chemical formula]

[0205] Here, for the three types of phosphorescent compounds used in the light-emitting element 3, the emission wavelength F(λ ) and the relationship with ε(λ)λ of the compound (3) and the compound (4) 4 are shown in Fig. 24. In the light-emitting element of this example, as shown in Fig. 24, the first light-emitting layer 113B contains the compound (1), which is the first phosphorescent compound that exhibits blue light emission. Also, the second light-emitting layer 11 3G contains the compound (4 ), which is the second phosphorescent compound that exhibits light emission with a longer wavelength than the first phosphorescent compound (emission peak wavelength 566 nm), and the maximum value A located on the longest wavelength side of the function represented by ε(λ)λ is within the range of 440 n 4 m to 520 nm (512 nm). The third light-emitting layer 113R contains the compound (3 ), which is the third phosphorescent compound that exhibits light emission with a longer wavelength than the second phosphorescent compound, and the maximum value B located on the longest wavelength side of the function represented by ε(λ)λ is within the range of 5 20 nm to 600 nm (near 542 nm). Also, from Fig. 24, it can be seen that the relationship that the maximum value B is larger than the maximum value A can also be observed. 4 is within the range of 5 20 nm to 600 nm (near 542 nm). Also, from Fig. 24, it can be seen that the relationship that the maximum value B is larger than the maximum value A can also be observed. is within the range of 5 20 nm to 600 nm (near 542 nm). Also, from Fig. 24, it can be seen that the relationship that the maximum value B is larger than the maximum value A can also be observed.

[0206] The method for fabricating the light-emitting element 3 in this embodiment is shown below.

[0207] (Method for fabricating the light-emitting element 3) First, indium tin oxide (ITSO) containing silicon oxide is sputtered onto a glass substrate. The first electrode 101 was formed by depositing a film using the 3D method. The film thickness was set to 110 nm. The area was set to 2 mm x 2 mm. Here, the first electrode 101 functions as the anode of the light-emitting element. It is an electrode.

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

[0209] Then, 10 -4 A substrate is introduced into a vacuum deposition apparatus where the internal pressure is reduced to approximately Pa, and then vacuum deposition is performed. After vacuum firing at 170°C for 30 minutes in the heating chamber of the apparatus, the substrate is left for approximately 30 minutes. It was allowed to cool.

[0210] Next, the first electrode 101 is formed such that the surface on which the first electrode 101 is formed faces downwards. The prepared substrate is fixed to a substrate holder provided inside the vacuum deposition apparatus, 10 -4 Reduced to approximately Pa After applying pressure, the above structural formula (i) is applied to the first electrode 101 by a vapor deposition method using resistance heating. 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophen By co-depositing (abbreviation: DBT3P-II) and molybdenum(VI) oxide, holes An injection layer 111 was formed. Its film thickness was set to 40 nm, and it was made of DBT3P-II and molybdenum oxide. The ratio of ingredients is adjusted to be 4:2 by weight (=DBT3P-II:molybdenum oxide). Co-evaporation is a method of vapor deposition in which multiple evaporation sources are used to deposit vapor simultaneously within a single processing chamber. It is the law.

[0211] Next, on the hole injection layer 111, 4-phenyl-4'-( represented by the above structural formula (ii) 9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP) 20 A film was deposited to a thickness of nm, forming a hole transport layer 112.

[0212] Furthermore, on the hole transport layer 112, 2-[3-(dibenzo) represented by the above structural formula (iii) is added. Thiofen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBT) PDBq-II) and 4-phenyl-4'-(9-phenyl represented by the above structural formula (iv) Lu-9H-carbazole-3-yl)triphenylamine (abbreviation: PCBA1BP), The above structural formula (v) represents bis(2,3,5-triphenylpyrazinate)(dipivaloy). Lumetanato Iridium(III) (Abbreviation: [Ir(tppr)2(dpm)]) (Chemical Compound) Object (3)) and the weight ratio 0.5:0.5:0.05 (=2mDBTPDBq-II:PC Co-deposited at 20 nm so that BA1BP:[Ir(tppr)2(dpm)]) and the third After fabricating the light-emitting layer 113R, 2mDBTPDBq-II and PCBA1BP and the above structure The bis{2-[5-methyl-6-(2-methylphenyl)-4-ply} represented by formula (xii) [limidinyl-κN3]phenyl-κC}(2,4-pentanedionato-κ 2 O,O') Lydium(III) (abbreviation: [Ir(mpmppm)2(acac)]) (compound(4)) ) and in weight ratio 0.5:0.5:0.05 (=2mDBTPDBq-II:PCBA1 Co-deposited at 5 nm so that BP:[Ir(mpmppm)2(acac)]) and the second A light-emitting layer 113G is formed, and further, 3,5-bis[3] represented by the above structural formula (vii) is formed. -(9H-carbazole-9-yl)phenyl]pyridine (abbreviation: 35DCzPPy) 3,3'-bis(9-phenyl-9H-carbazole) represented by the above structural formula (viii) ) (abbreviation: PCCP) and tris{2-[5-(2-methyl} represented by the above structural formula (ix) Phenyl)-4-(2,6-dimethylphenyl)-4H-1,2,4-triazole-3 -yl-κN2]phenyl-κC}iridium(III) (abbreviation: [Ir(mpptz- dmp)3)(compound (1)) and are mixed in a weight ratio of 0.5:0.5:0.06 (=35DC 30nm co-deposition so that zPPy:PCCP:[Ir(mpptz-dmp)3]) Then the first light-emitting layer 113B was formed, and the light-emitting layer 113 was formed.

[0213] Note that 2mDBTPDBq-II and PCBA1BP, and 35DCzPPy and PCCP are... Each forms an excited complex. Furthermore, 2mDBTPDBq-II has electron transport properties, and PC BA1BP has hole transport properties, but within the light-emitting layer, these are divided in a 0.5:0.5 ratio. By incorporating them together, the second light-emitting layer 113G and the third light-emitting layer 113R perform hole transport. It has properties. Also, 35DCzPPy has electron transport properties, and PCCP has hole transport properties. Although it has propulsion properties, these are included in the light-emitting layer in a ratio of 0.5:0.5. As a result, the first light-emitting layer 113B is electron-transporting.

[0214] Subsequently, 2-[3-(dibenzothiophene represented by the above structural formula (x)) is placed on the light-emitting layer 113. -4-yl)phenyl]-1-phenyl-1H-benzoimidazole (abbreviation: mDBTB) Im-II) is deposited to a thickness of 10 nm, and further, the above structural formula (xi) is used. Bathophenanthroline (abbreviated as BPhen) is deposited to a thickness of 20 nm, and electron transport A transport layer 114 was formed.

[0215] After forming the electron transport layer 114, lithium fluoride (LiF) is then applied to a thickness of 1 nm. A layer is deposited to form an electron injection layer 115, and finally, a second electrode 1 that functions as a cathode is formed. As O2, aluminum is deposited to a film thickness of 200 nm, thus in this embodiment A light-emitting element 3 was fabricated.

[0216] In the vapor deposition process described above, resistance heating was used for all deposition steps.

[0217] The light-emitting element 3 is placed in a glove box under a nitrogen atmosphere, so that the light-emitting element is not exposed to the atmosphere. The process involves sealing with a glass substrate (applying a sealing material around the element and sealing at 80°C). After heat treatment (for 1 hour), the reliability of these light-emitting elements was measured. The measurements were taken at room temperature (in an atmosphere maintained at 25°C).

[0218] Figure 25 shows the current density-luminance characteristics of the light-emitting element 3, and Figure 26 shows the luminance-current efficiency characteristics. Brightness characteristics are shown in Figure 27, luminance-chromaticity characteristics in Figure 28, and luminance-power efficiency characteristics in Figure 29. - The external quantum efficiency characteristics are shown in Figure 30, and the emission spectrum is shown in Figure 31.

[0219] As described above, the light-emitting element 3 has a practical brightness of 1000 cd / m². 2 Current efficiency in the vicinity is 48 It exhibits very good characteristics with a cd / A ratio, an external quantum efficiency of 23%, and a power efficiency of 32 lm / W. It was found that the emitted light color is 3860K white light, and the average color rendering index Ra is 85.1. It was also found to exhibit good color rendering properties. Figure 20 shows a light-emitting element according to one embodiment of the present invention. It can also be seen that the light-emitting element 3 has the characteristic of having little luminance dependence on chromaticity.

[0220] Furthermore, the carrier recombination region of the light-emitting element 3 is determined by the transport properties of each light-emitting layer, specifically the first light-emitting layer 113. Near the interface between B and the second light-emitting layer 113G, the light emission of the third light-emitting layer 113R is sufficient. It has been obtained. In addition, the first light-emitting layer 113B to the third light-emitting layer 113R each contain Since light from the photomaterial is clearly present in the spectrum, excitation occurs in the light-emitting element 3. This indicates that energy transfer is occurring effectively and in a balanced manner. [Examples]

[0221] This embodiment is a light-emitting element of the present invention having a different configuration from Examples 1 and 2. Child 4 will be described. Light-emitting element 4 is BPAFLP and P in the light-emitting element of Example 1. Instead of CBA1BP, the following structural formula (xiii) represents 4,4'-di(1-naphthyl) )-4''-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviated) Name: PCBNBB) replaces part of 35DCzPPy and 2mDBTPDBq-II The following structural formula (xiv) represents 2-[3'-(dibenzothiophen-4-yl)bifu [enyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-I This is an example using I). Note that the phosphorescent compounds contained in each light-emitting layer are the same as in Example 1. Therefore, each emission wavelength F(λ) and ε(λ)λ 4 The relationship is the same as in Example 1.

[0222] The structural formulas of PCBNBB and 2mDBTBPDBq-II are shown below. Other compounds Since it is the same as that used in Example 1, it will be omitted. Refer to Example 1. .

[0223] [Chemical formula]

[0224] The manufacturing method of the light-emitting element 4 of this example is shown below.

[0225] (Manufacturing method of the light-emitting element 4) First, indium tin oxide (ITSO) containing silicon oxide was formed into a film by a sputtering method on a glass substrate to form the first electrode 101. The film thickness was 110 nm, and the electrode area was 2 mm × 2 mm. Here, the first electrode 101 is an electrode that functions as the anode of the light-emitting element.

[0226] Next, as a pretreatment for forming a light-emitting element on the substrate, the substrate surface was washed with water, baked at 200 °C for 1 hour, and then subjected to UV ozone treatment for 370 seconds.

[0227] After that, the substrate was introduced into a vacuum evaporation apparatus whose internal pressure was reduced to about 10 " -4 "Pa, and vacuum baking was performed at 170 °C for 30 minutes in the heating chamber of the vacuum evaporation apparatus, and then the substrate was allowed to cool for about 30 minutes. <​​​​​​​​​​​​By co-depositing (abbreviation: DBT3P-II) and molybdenum(VI) oxide, holes An injection layer 111 was formed. Its film thickness was set to 40 nm, and it was made of DBT3P-II and molybdenum oxide. The ratio of ingredients is adjusted to be 4:2 by weight (=DBT3P-II:molybdenum oxide). Co-evaporation is a method of vapor deposition in which multiple evaporation sources are used to deposit vapor simultaneously within a single processing chamber. It is the law.

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

[0230] Furthermore, on the hole transport layer 112, 2mDBTBPDBq-II, PCBNBB, and [I r(tppr)²(dpm)] and a weight ratio of 0.5:0.5:0.05 (=2mDBTB) PDBq-II:PCBNBB:[Ir(tppr)2(dpm)]) so that 10 After co-depositing nm to create the third luminescent layer 113R, 2mDBTBPDBq-II and PC were added. BNBB and [Ir(tBuppm)2(acac)] are in a weight ratio of 0.5:0.5:0 .05(=2mDBTBPDBq-II:PCBNBB:[Ir(tBuppm)2(a A 10nm co-deposit is performed to form a second light-emitting layer 113G, and further 35DCzPPy, PCCP, and [Ir(mpptz-dmp)3] are used in a weight ratio of 0. 7:0.3:0.06(=35DCzPPy:PCCP:[Ir(mpptz-dmp) 3) Co-deposit a 30 nm layer to form the first light-emitting layer 113B, and the light-emitting layer 113 is formed I did it.

[0231] Note that 2mDBTBPDBq-II and PCBNBB, and 35DCzPPy and PCCP are... Each forms an excited complex. Furthermore, 2mDBTBPDBq-II has electron transport properties, and P CBNBB has hole transport properties, but within the light-emitting layer, these are divided in a 0.5:0.5 ratio. By incorporating them together, the second light-emitting layer 113G and the third light-emitting layer 113R perform hole transport. It has properties. Also, 35DCzPPy has electron transport properties, and PCCP has hole transport properties. Although it has propulsion properties, these are included in the light-emitting layer in a ratio of 0.5:0.5. As a result, the first light-emitting layer 113B is electron-transporting.

[0232] Subsequently, 35DCzPPy is deposited on the light-emitting layer 113 to a thickness of 10 nm, and further Then, BPhen was deposited to a thickness of 20 nm to form an electron transport layer 114.

[0233] After forming the electron transport layer 114, lithium fluoride (LiF) is then applied to a thickness of 1 nm. A layer is deposited to form an electron injection layer 115, and finally, a second electrode 1 that functions as a cathode is formed. As O2, aluminum is deposited to a film thickness of 200 nm, thus in this embodiment A light-emitting element 4 was fabricated.

[0234] In the vapor deposition process described above, resistance heating was used for all deposition steps.

[0235] The light-emitting element 4 is placed in a glove box under a nitrogen atmosphere, so that the light-emitting element is not exposed to the atmosphere. The process involves sealing with a glass substrate (applying a sealing material around the element and sealing at 80°C). After heat treatment (for 1 hour), the reliability of these light-emitting elements was measured. The measurements were taken at room temperature (in an atmosphere maintained at 25°C).

[0236] Figure 32 shows the current density-luminance characteristics of the light-emitting element 4, and Figure 33 shows the luminance-current efficiency characteristics. Brightness characteristics are shown in Figure 34, luminance-chromaticity characteristics in Figure 35, and luminance-power efficiency characteristics in Figure 36. - The external quantum efficiency characteristics are shown in Figure 37, and the emission spectrum is shown in Figure 38.

[0237] As described above, the light-emitting element 4 has a practical brightness of 1000 cd / m². 2 Current efficiency in the vicinity is 39 It was found to exhibit good characteristics such as cd / A, external quantum efficiency of 21%, and power efficiency of 29 lm / W. Furthermore, the emission color is 2260K, and the average color rendering index Ra is 93.4, indicating good color rendering. I also understood how to demonstrate it.

[0238] Furthermore, the carrier recombination region of the light-emitting element 4 is determined by the transport properties of each light-emitting layer, specifically the first light-emitting layer 113. Near the interface between B and the second light-emitting layer 113G, the light emission of the third light-emitting layer 113R is sufficient. It has been obtained. In addition, the first light-emitting layer 113B to the third light-emitting layer 113R each contain Since the light from the photomatter is clearly visible in the spectrum, there is a transfer of excitation energy. It is clear that the process is being carried out effectively and in a well-balanced manner.

[0239] Next, reliability testing was conducted. The reliability testing involved an initial brightness of 3000 cd / m². 2 , current density - Under specific conditions, the brightness change over time will be measured with the initial brightness set to 100%. The experiment was conducted further. The results are shown in Figure 39. From the figure, it can be seen that all the light emitted from each light-emitting layer is phosphorescence. Despite being a so-called all-phosphor element, it still maintained 65% of its initial brightness even after 440 hours. In addition, the light-emitting element 4, which is one aspect of the present invention, is a light-emitting element with good durability. That's what I found out.

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

[0241] [ka]

[0242] <Step 1; 3-(2-methylphenyl)-4-(2,6-dimethylphenyl)-5- Synthesis of phenyl-4H-1,2,4-triazole (abbreviation: Hmpptz-dmp) First, N-[1-chloro-1-(2-methylphenyl)methylidene]-N'-[1- [Lolo-(1-phenyl)methylidene]hydrazine 12.6g (43.3 mmol), 2, 6-dimethylaniline 15.7g (134.5 mmol), N,N-dimethylaniline 1 00 ml was placed in a 500 ml round-bottom flask and heated and stirred at 120°C for 20 hours. After the reaction, the reaction solution was slowly added to 200 ml of 1N hydrochloric acid. Dichlorometh The target substance was extracted into the organic layer by adding [amount of ammonium compound]. The resulting organic layer was then treated with water and sodium bicarbonate aqueous solution. It was washed and dried with magnesium sulfate. The magnesium sulfate was removed by natural filtration, and obtained The filtrate was concentrated to obtain a black liquid. This liquid was then subjected to silica gel column chromatography. It was purified by -. The developing solvent was ethyl acetate:hexane = 1:5. The obtained fraxil The solution was concentrated to obtain a white solid. This solid was recrystallized using ethyl acetate, and Hmppt 4.5 g of z-dmp was obtained as a white solid in a yield of 31%. The synthesis scheme for Step 1 is as follows: This will be shown.

[0243] [ka]

[0244] <Step 2; Tris{2-[5-(2-methylphenyl)-4-(2,6-dimethylphenyl [phenyl)-4H-1,2,4-triazole-3-yl-κN2]phenyl-κC}yl Synthesis of Dium(III) (abbreviation: Ir(mpptz-dmp)3) The ligand Hmpptz-dmp obtained in step 1 above, 2.5g (7.4 mmol), 0.7g (1.5 mmol) of acetylacetonatoiridium(III) was heated to a high temperature. The mixture was placed in a container and degassed. This reaction vessel was then subjected to a 48-hour reaction at 250°C while argon flowed through it. The mixture was heated and stirred. After the reaction for a predetermined time, the resulting solid was washed with dichloromethane, and the green color of the insoluble material was detected. The solid was obtained by suction filtration. This solid was dissolved in toluene, and a layer of alumina and Celite was formed. The fraction was filtered through [a specific filter]. The resulting fraction was concentrated to obtain a green solid. This solid was then [referred to] [a specific filter]. Recrystallization was performed using the phosphorescent organometallic iridium complex [Ir(mpptz-dmp)3]( 0.8 g of the green powder (abbreviated name) was obtained in a yield of 45%. The synthesis scheme for Step 2 is shown below. vinegar.

[0245] [ka]

[0246] Furthermore, nuclear magnetic resonance spectroscopy of the green powder obtained in step 2 above ( 1 (H-NMR) The analysis results are shown below. From this, it can be concluded that in the above synthesis method, organometallic complex, Ir(mpp) It was found that tz-dmp)3 (abbreviation) was obtained.

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

[0248] (Reference example 2) The organometallic complex used in the above embodiment, (acetylacetonato)bis(6-tert- Iridium(III) (also known as bis[2-(6-te)) [rt-butyl-4-pyrimidinyl-κN3)phenyl-κC](2,4-pentanediona To-κ 2 O,O') Iridium(III)) (Abbreviation: [Ir(tBuppm)2(aca c)) shows an example of synthesis. Note that the structure of [Ir(tBuppm)2(acac)] is as follows. This will be shown.

[0249] [ka]

[0250] Step 1; 4-tert-butyl-6-phenylpyrimidine (abbreviation: HtBuppm) ) synthesis > First, 22.5g of 4,4-dimethyl-1-phenylpentane-1,3-dione and formaldehyde 50g of Mido was placed in a round-bottom flask fitted with a reflux condenser, and the inside was purged with nitrogen. This reaction vessel The reaction solution was refluxed for 5 hours by heating. After that, this solution was treated with sodium hydroxide solution. The organic layer was poured into a solution and extracted with dichloromethane. The obtained organic layer was then mixed with water and saturated saline solution. The solution was washed and dried with magnesium sulfate. The dried solution was filtered. After removing the flux by distillation, the resulting residue is dissolved in hexane:ethyl acetate = 10:1 (volume ratio) The pyrimidine derivative HtBupp was purified using silica gel column chromatography as the substrate. m was obtained (colorless oil, yield 14%). The synthesis scheme for Step 1 is shown below.

[0251] [ka]

[0252] Step 2; Di-μ-chloro-bis[bis(6-tert-butyl-4-phenylpyryl] Synthesis of midinato iridium(III) (abbreviation: [Ir(tBuppm)2Cl]2) > Next, add 15 mL of 2-ethoxyethanol and 5 mL of water, and the HtBupp obtained in step 1 above. m1.49g, iridium chloride hydrate (IrCl3·H2O) 1.04g, attached to a reflux tube. It was placed in a round-bottom flask, and the flask was purged with argon. Then, microwave (2.4 The mixture was irradiated with 5GHz (100W) for 1 hour to allow the reaction to proceed. After removing the solvent by distillation, the resulting residue was collected. The dinuclear complex [Ir(tBuppm)2Cl]2 was obtained by suction filtration and washing with ethanol (yellow). Green powder, yield 73%. The synthesis scheme for Step 2 is shown below.

[0253] [ka]

[0254] Step 3; (Acetylacetonato)bis(6-tert-butyl-4-phenylpyryl) Iridium(III) (abbreviation: [Ir(tBuppm)2(acac)]) > Furthermore, 40 mL of 2-ethoxyethanol and the dinuclear complex [Ir(tB) obtained in step 2 above are added. [uppm)2Cl] 21.61g, acetylacetone 0.36g, sodium carbonate 1. 27g was placed in a round-bottom flask fitted with a reflux tubing, and the flask was purged with argon. The mixture was then irradiated with microwaves (2.45 GHz, 120 W) for 60 minutes to allow the reaction to proceed. The solvent was then removed by distillation. The resulting residue was filtered by suction with ethanol and washed with water and ethanol. This solid was then processed. Dissolve in chloromethane and use Celite (Wako Pure Chemical Industries, Ltd., catalog number: 531-1) The solution was filtered through a filtration aid consisting of layers of 6855), alumina, and Celite. The resulting solid is then recrystallized in a mixed solvent of dichloromethane and hexane. The target product was obtained as a yellow powder (yield 68%). The synthesis scheme for Step 3 is shown below.

[0255] [ka]

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

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

[0258] 10 electrodes 11 electrodes 101 First electrode 102 Second electrode 103 EL layer 111 Hole injection layer 112 Hole transport layer 113 Emitting layer 113B First light-emitting layer 113Bd First phosphorescent compound 113Bh First host material 113G Second light-emitting layer 113Gd Second phosphorescent compound 113GHz Second host material 113R Third luminescent layer 113Rd Third phosphorescent compound 113Rh Third host material 113ex recombination area 114 Electron transport layer 115 Electron injection layer 400 circuit boards 401 First electrode 402 Auxiliary electrode 403 EL layer 404 Second electrode 405 sealant 406 Sealant 407 Sealing substrate 412 pads 420 IC chips 601 Drive circuit section (source line drive circuit) 602 pixel section 603 Drive circuit section (gate wire drive circuit) 604 Sealing substrate 605 Sealant 607 Space 608 Wiring 609 FPC (Flexible Printed Circuit) 610 element substrate 611 Switching TFT 612 Current-controlled 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 cabinet 902 Liquid Crystal Layer 903 Backlight Unit 904 cabinet 905 Driver IC 906 terminal 951 circuit board 952 Electrode 953 Insulating layer 954 Partition layer 955 EL layer 956 Electrode 1001 circuit board 1002 Underlying insulating film 1003 Gate Insulator 10:06 Guard Station 1007 🙏 1008 Gate 1020 First interlayer insulating film 1021 Second interlayer insulating film 1022 Electrode First electrode of 1024W light-emitting element First electrode of 1024R light-emitting element First electrode of 1024G light-emitting element 1024B First electrode of light-emitting element 1025 Bulkhead 1028 Layer containing organic compounds 1029 Second electrode of light-emitting element 1031 Sealing substrate 1032 Sealant 1033 Transparent base material 1034R Red colored layer 1034G Green colored layer 1034B Blue colored layer 1035 Black Matrix 1036 Overcoat layer 1037 Third interlayer insulating film 1040 pixel section 1041 Drive circuit section 1042 Peripheral area 1044W White light emission area 1044R Red light emission area 1044B Blue light emission region 1044G Green luminescence region 2001 cabinet 2002 light source 3001 Lighting device 3002 Display device 5000 display 5001 display 5002 display 5003 display 5004 display 5005 display 7101 enclosure 7103 Display section 7105 Stand 7107 Display section 7109 Operation Keys 7110 Remote Control Unit 7201 Main Unit 7202 enclosure 7203 Display section 7204 Keyboard 7205 External connection port 7206 Pointing device 7210 Second display unit 7301 enclosure 7302 enclosure 7303 Connection section 7304 Display section 7305 Display section 7306 Speaker section 7307 Recording media insertion section 7308 LED Lamp 7309 Operation Keys 7310 Connection terminal 7311 Sensor 7400 mobile phones 7401 enclosure 7402 Display section 7403 Operation Buttons 7404 External connection port 7405 Speaker 7406 Microphone 9033 Fastener 9034 Switch 9035 Power switch 9036 Switch 9038 Operation switch 9630 cabinet 9631 Display section 9631a Display section 9631b Display section 9632a Touch panel area 9632b Touch panel area 9633 Solar Cell 9634 Charge / Discharge Control Circuit 9635 Battery 9636 DC-DC converter 9637 Operation Keys 9638 converter 9639 button

Claims

[Claim 1] Between the pair of electrodes, A first phosphorescent compound that emits blue light is dispersed in a first host material in a first light-emitting layer, ε(λ)λ in the range of 440 nm to 520 nm ４ A second phosphorescent compound having a maximum value A located on the longest wavelength side of the function represented by and exhibiting emission at a longer wavelength than the first phosphorescent compound is dispersed in a second host material in a second light-emitting layer, ε(λ)λ in the range of 520 nm to 600 nm ４ A third phosphorescent compound is dispersed in a third host material, comprising: a third phosphorescent layer having a maximum value B located on the longest wavelength side of the function represented by , and exhibiting emission at a longer wavelength than the second phosphorescent compound; A light-emitting element in which the first to third light-emitting layers are stacked in this order. (However, ε(λ) represents the molar extinction coefficient of each phosphorescent compound and is a function of wavelength λ.)

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