Organic electroluminescent element

Abstract

This organic electroluminescent element contains a first organic compound, a second organic compound, and a third organic compound in a light-emitting layer, wherein the second organic compound is a delayed fluorescent material having a metastable structure in an energy band higher than the lowest excited singlet energy, and the organic electroluminescent element satisfies ES1 (1) > ES2 (2) > ES1 (2) > ES1 (3) and ET1 (1) > ET1 (2) > E T1 (3), thereby exhibiting a high FRET efficiency between the delayed fluorescent material and the light-emitting material and being capable of emitting light having a desired chromaticity. Here, ES1 (1) to ES1 (3) respectively represent the lowest excited singlet energies of the first to third organic compounds; ES2 (2) represents the energy of the metastable structure of the second organic compound; and ET1 (1) to ET1 (3) respectively represent the lowest excited triplet energies of the first to third organic compounds.

Description

Organic electroluminescent element

[0001] This invention relates to an organic electroluminescent element that emits light through energy transfer from a delayed-fluorescence material to a light-emitting material.

[0002] Delayed fluorescence materials are organic materials that undergo reverse intersystem crossing from an excited triplet state to an excited singlet state. Organic electroluminescent elements are known that have a light-emitting layer using such a delayed fluorescence material in combination with a host material and a light-emitting material (for example, Patent Document 1). In the light-emitting layer of this type of organic electroluminescent element, of the excited states generated by electric current excitation with a probability of excited singlet state:excited triplet state = 25:75, the energy of the excited triplet state is converted to excited singlet energy via reverse intersystem crossing of the delayed fluorescence material, and is transferred to the light-emitting material along with the initial excited singlet energy and used for fluorescence emission of the light-emitting material. Therefore, the energy of the excited triplet state, which would normally be deactivated without radiation in ordinary fluorescent materials, is effectively utilized for emission, and high luminescence efficiency can be obtained. Incidentally, in such organic electroluminescent elements, the transfer of excited singlet energy from the delayed fluorescence material to the light-emitting material is carried out by Förster resonance energy transfer (FRET). Here, for Förster resonance energy transfer to occur, the energy of the excited donor must be higher than the energy required to excite the acceptor. Therefore, in order to ensure the efficiency of Förster resonance energy transfer (FRET efficiency) between the delayed fluorescence material and the luminescent material, a delayed fluorescence material is selected whose emission peak wavelength is considerably shorter than the emission peak wavelength of the luminescent material.

[0003] WO2015 / 022974A1

[0004] However, although various delayed fluorescent materials have been proposed to date, depending on the emission peak wavelength of the light-emitting material, there are situations in which an appropriate delayed fluorescent material to be combined cannot be found. For example, when producing an organic electroluminescent element using a light-emitting material having a desired emission peak wavelength, according to conventional selection methods, a delayed fluorescent material having an emission peak wavelength on the shorter wavelength side to some extent than the emission peak wavelength of the light-emitting material is searched for and used. However, it is often the case that sufficient FRET efficiency cannot be achieved because such a delayed fluorescent material cannot be found. Accordingly, the present inventors have conducted studies with the object of providing an organic electroluminescent element that can achieve high FRET efficiency between the delayed fluorescent material and the light-emitting material and emit light having desired chromaticity, in order to solve such problems of the prior art.

[0005] As a result of intensive studies to achieve the above object, the present inventors found that a metastable structure in an energy band higher than the lowest excited singlet energy (S ２ ) By using a delayed fluorescent material having the above in the light-emitting layer, the FRET efficiency between the delayed fluorescent material and the light-emitting material is increased, and an organic electroluminescent element capable of emitting light derived from the light-emitting material with high purity can be realized. The present invention has been proposed based on these findings, and specifically has the following configuration.

[0006] [1] An organic electroluminescent element having a light-emitting layer containing a first organic compound, a second organic compound, and a third organic compound, wherein the second organic compound is a delayed fluorescent material having a metastable structure in an energy band higher than the lowest excited singlet energy level, and the first organic compound, the second organic compound, and the third organic compound satisfy the following formulas (I) and (II): Formula (I) E Ｓ１ (1) > E Ｓ２ (2) > E Ｓ１ (2) > E Ｓ１ (3) Formula (II) E Ｔ１ (1) > E Ｔ１ (2) > E Ｔ１ (3) [In formulas (I) and (II), E Ｓ１(1) The lowest excitation singlet energy of the first organic compound, E Ｓ１ (2) The lowest excitation singlet energy of the second organic compound, E Ｓ２ (2) The energy of the metastable structure in an energy band higher than the lowest excited singlet energy level of the second organic compound, E Ｓ１ (3) The lowest excitation singlet energy of the third organic compound, E Ｔ１ (1) The lowest excited triplet energy of the first organic compound, E Ｔ１ (2) The lowest excited triplet energy of the second organic compound, E Ｔ１ (3) represents the lowest excited triplet energy of the third organic compound. [2] The organic electroluminescent element according to [1], wherein the difference between the emission peak wavelengths of the second organic compound and the third organic compound is within 20 nm. [3] The organic electroluminescent element according to [1] or [2], wherein the emission peak wavelength of the third organic compound is 500 nm or less. [4] E of the second organic compound Ｓ２ (2) An organic electroluminescent element according to any one of [1] to [3], wherein (2) is in the range of 2.85 to 3.05 eV. [5] An organic electroluminescent element according to any one of [1] to [4], wherein the second organic compound satisfies the following formula (III). Formula (III) E Ｓ２ (2) - E Ｓ１(2) > 0.04 eV [6] The organic electroluminescent element according to any one of [1] to [5], wherein the second organic compound has a structure in which a donor group is bonded to the ortho position of a benzene ring to which an acceptor group is bonded. [7] The organic electroluminescent element according to any one of [1] to [5], wherein the second organic compound has a structure in which a substituted or unsubstituted carbazole-9-yl group is bonded to the ortho position of a benzene ring to which a substituted or unsubstituted triazinyl group is bonded. [8] The organic electroluminescent element according to [6], wherein another donor group is further bonded to the benzene ring, and the donor group at the ortho position and the other donor group are bonded to each other with a substituted or unsubstituted arylene group or a substituted or unsubstituted heteroarylene group as linking groups to form a cyclic structure. [9] The organic electroluminescent element according to [8], wherein the shortest number of linked atoms in the cyclic structure is 12 to 14.

[10] The organic electroluminescent element according to any one of [1] to [9], wherein the second organic compound has a C2 symmetric structure.

[11] The organic electroluminescent element according to any one of [1] to

[10] , wherein the S value of the second organic compound contained in the light-emitting layer is less than -0.2.

[0007] The organic electroluminescent element of the present invention exhibits high efficiency in Förster resonance energy transfer (FRET efficiency) from the second organic compound to the third organic compound, enabling the emission of light originating from the third organic compound with high purity. Therefore, by using, for example, a third organic compound having an emission peak wavelength in the wavelength range of a desired chromaticity, a good emission color reflecting that chromaticity can be achieved.

[0008] This is the potential energy curve showing the Förster resonance energy transfer (FRET) from the second organic compound to the third organic compound. These are the emission spectra of the fast (prompt) and slow (delay) fluorescence components observed in compound 1, and the fast (prompt) and slow (delay) fluorescence components observed in comparative compound 1. These are the emission spectra of the fast (prompt) and slow (delay) fluorescence components observed in compound 2. These are the emission spectra of the fast (prompt) and slow (delay) fluorescence components observed in compound 3.

[0009] The contents of the present invention will be described in detail below. The following descriptions of constituent elements may be based on representative embodiments and specific examples of the present invention, but the present invention is not limited to such embodiments and specific examples. In this application, numerical ranges expressed using "~" mean a range that includes the numbers written before and after "~" as the lower and upper limits. Also, in this application, "consists of" means consisting only of what is written before "consists of" and does not include anything else. Furthermore, some or all of the hydrogen atoms present in the molecule of the compound used in the present invention are deuterium atoms ( ２ It can be substituted with H (deuterium D). In the chemical structural formulas herein, hydrogen atoms are either represented as H or omitted. For example, when the representation of an atom bonded to a carbon atom in the ring skeleton of a benzene ring is omitted, it is assumed that H is bonded to the carbon atom in the ring skeleton where the representation is omitted. In this specification, the term "substituent" means an atom or group of atoms other than hydrogen and deuterium atoms. On the other hand, the term "substituted or unsubstituted" means that the hydrogen atom may be substituted with a deuterium atom or a substituent.

[0010] (Characteristics of Organic Electroluminescent Element) The organic electroluminescent element of the present invention is an organic electroluminescent element having a light-emitting layer containing a first organic compound, a second organic compound, and a third organic compound, wherein the second organic compound is a delayed fluorescence material having a metastable structure in an energy band higher than the lowest excited singlet energy level, and the first organic compound, the second organic compound, and the third organic compound satisfy the following formulas (I) and (II). Formula (I) E Ｓ１ (1) > E Ｓ２ (2) > E Ｓ１ (2) > E Ｓ１ (3) Equation (II) E Ｔ１ (1) > E Ｔ１ (2) > E Ｔ１ (3) [In equations (I) and (II), E Ｓ１ (1) The lowest singlet excitation energy of the first organic compound, E Ｓ１ (2) The lowest excitation singlet energy of the second organic compound, E Ｓ２ (2) The energy of the metastable structure in an energy band higher than the lowest excited singlet energy level of the second organic compound is E Ｓ１ (3) The lowest excited singlet energy of the third organic compound, E Ｔ１ (1) The lowest excited triplet energy of the first organic compound, E Ｔ１ (2) The lowest excited triplet energy of the second organic compound, E Ｔ１ (3) represents the lowest excited triplet energy of the third organic compound. In the organic electroluminescent element of the present invention, the second organic compound has a metastable structure (S2) in an energy band higher than the lowest excited singlet energy, resulting in high efficiency of Förster resonance energy transfer (FRET efficiency) from the second organic compound to the third organic compound. Therefore, light originating from the third organic compound can be generated with high purity. This mechanism will be explained below with reference to Figure 1. Figure 1 is a potential energy curve showing the energy transitions of the second and third organic compounds, with the horizontal axis representing the reaction coordinate and the vertical axis representing energy. Here, the second organic compound has the lowest excited singlet energy [E Ｓ１(2)) is a delayed fluorescence material having a metastable structure (S2) in a higher energy band than the second organic compound, and the third organic compound has a lower lowest excitation singlet energy [E Ｓ１ (3) and the lowest excited triplet energy [E Ｔ１ (3) Both are small luminescent compounds. When excitation energy is supplied to a system in which such a second and third organic compound coexist, as shown in Figure 1, the second organic compound is excited to a metastable structure (S2) and an excited triplet state (T1). Of these, the second organic compound in the excited triplet state (T1) is transformed (reverse intersystem crossing) to an excited singlet state (S1) and relaxes to the lowest excited singlet state. Here, assuming that the third organic compound does not exist, the second organic compound reaches the minimum value of the potential energy curve of the metastable structure (S2) [E Ｓ２ (2) Radiative deactivation from the energy state corresponding to [E] and the minimum value of the potential energy curve of the excited singlet state (S1) Ｓ１ (2) Fluorescence is emitted by radiative deactivation from the energy state corresponding to (2) (lowest excited singlet state). At this time, the emission due to radiative deactivation from the metastable structure (S2) (fast fluorescence component) is observed relatively quickly, while the emission due to radiative deactivation from the lowest excited singlet state (slow fluorescence component) is observed later than the emission from the metastable structure (S2) because it goes through reverse intersystem crossing. The emission peak wavelength of the entire emission, combining the fast and slow fluorescence components, is longer than the emission peak wavelength of the fast fluorescence component alone. On the other hand, in the system of the present invention in which the second organic compound and the third organic compound coexist, the second organic compound in the metastable structure (S2) is E Ｓ２ After relaxing to the energy state of (2), its excited singlet energy is transferred to the third organic compound via Förster resonance energy transfer (FRET(1)), causing the third organic compound to transition to an excited singlet state. In addition, the second organic compound, which is in an excited singlet state (S1) generated by reverse intersystem crossing from the excited triplet state (T1), also transitions to the lowest excited singlet state [E Ｓ１After relaxation to (2), the excited singlet energy is transferred to the third organic compound via Förster resonance energy transfer (FRET(2)), causing the third organic compound to transition to the excited singlet state. At this time, even if the second organic compound is a delayed fluorescence material having an emission peak wavelength shorter than the emission peak wavelength of the third organic compound, but the difference in emission peak wavelengths between it and the third organic compound is small, or if it is a delayed fluorescence material having an emission peak wavelength that is a certain length longer than the emission peak wavelength of the third organic compound, the energy of the metastable structure (S2) [E Ｓ２ (2) Due to the high FRET efficiency, energy transfer occurs with high FRET efficiency, allowing the third organic compound to efficiently transition to an excited singlet state (S1) and emit light. As a result, the present invention can achieve emission with high purity of light originating from the third organic compound. Furthermore, by using a third organic compound having an emission peak wavelength in the wavelength range of a desired chromaticity, for example, a good emission color that reflects its chromaticity can be achieved.

[0011] In one aspect of the present invention, the difference E between the energy of the metastable structure of the second organic compound and the lowest excited singlet energy is Ｓ２ (2) - E Ｓ１ (2) satisfies the following equation (III). Equation (III) E Ｓ２ (2) - E Ｓ１ (2) > 0.04eV E Ｓ２ (2) - E Ｓ１ (2) can be set to a range greater than 0.06 eV, greater than 0.08 eV, greater than 0.1 eV, greater than 0.15 eV, and also to a range of 0.3 eV or less, or 0.2 eV or less. In one aspect of the present invention, the E of the second organic compound Ｓ２ (2) is in the range of 2.85 to 3.20 eV. In one aspect of the present invention, the E of the second organic compound Ｓ２ (2) is in the range of 2.85 to 3.05 eV.

[0012] The emission peak wavelengths of the second and third organic compounds may be such that the emission peak wavelength of the second organic compound is shorter or longer than that of the third organic compound. Since the second organic compound used in the present invention has a metastable structure in an energy band higher than the lowest excited singlet energy level, a high FRET efficiency can be obtained between the second and third organic compounds even when the emission peak wavelength of the second organic compound is a certain length longer than that of the third organic compound. In one aspect of the present invention, the difference in emission peak wavelengths between the second and third organic compounds is within 20 nm. The difference in emission peak wavelengths between the second and third organic compounds can be within 15 nm or within 12 nm. In one aspect of the present invention, the emission peak wavelength of the third organic compound is longer than that of the second organic compound, and the difference in emission peak wavelengths can be in the range of 5 nm or more, 10 nm or more, 15 nm or more, or within 30 nm, 25 nm or less, or 20 nm or less. In one aspect of the present invention, the emission peak wavelength of the third organic compound is shorter than the emission peak wavelength of the second organic compound, and the difference in emission peak wavelengths can be within the range of 15 nm, 10 nm, or 5 nm.

[0013] The difference between the lowest excited singlet energy of the first organic compound and the energy of the metastable structure of the second organic compound [E Ｓ１ (1) - E Ｓ２ (2)] can be in the range of 0.3 eV or more, 0.5 eV or more, 0.7 eV or more, and can also be in the range of 1.6 eV or less, 1.3 eV or less, or 0.9 eV or less. The difference between the energy of the metastable structure of the second organic compound and the lowest excited singlet energy of the third organic compound [E Ｓ２ (2) - E Ｓ１(3)) can be set to a range of 0.1 eV or more, 0.15 eV or more, 0.2 eV or more, 0.3 eV or more, 0.4 eV or more, and can also be set to a range of 0.6 eV or less, or 0.5 eV or less.

[0014] The difference in the lowest excitation triplet energy between the first and second organic compounds [E Ｔ１ (1) - E Ｔ１ (2)] can be in the range of 0.03 eV or more, 0.05 eV or more, 0.07 eV or more, 0.09 eV or more, and can also be in the range of 0.3 eV or less, 0.2 eV or less, or 0.15 eV or less. The difference in the lowest excited triplet energy between the second organic compound and the third organic compound [E Ｔ１ (2) - E Ｔ１ (3) can be set to a range of 0.05 eV or more, a range of 0.1 eV or more, a range of 0.15 eV or more, a range of 0.3 eV or less, or a range of 0.2 eV or less.

[0015] (Energy of the excited state and value of the emission peak wavelength) Here, E Ｓ１ (1), E Ｓ１ (2) and E Ｓ１ (3) is summarized as "E Ｓ１ It is written as " and E Ｔ１ (1), E Ｔ１ (2) and E Ｔ１ (3) is summarized as "E Ｔ１ This is expressed as follows: In this application, the lowest excitation singlet energy of the compound [E Ｓ１ ] and the lowest excited triplet energy [E Ｔ１ ], Energy of the metastable structure of the second organic compound [E Ｓ２ (2) is the value obtained by the following procedure. However, for the second organic compound, the emission spectra of the fast fluorescence component and the slow fluorescence component are obtained at room temperature (300 K), and the energy of the metastable structure [E] is obtained from the emission spectrum of the fast fluorescence component using the same procedure as in (1) below.Ｓ２ (2)) Determine the lowest excitation singlet energy [E Ｓ１ We will find the ΔE for the second organic compound, which will be discussed later. ＳＴ (2) is E Ｓ１ -E Ｔ１ This value was obtained by calculating the following: (1) Lowest excitation singlet energy [E Ｓ１ ] and the energy of the metastable structure [E Ｓ２ (2) A thin film or toluene solution of the compound to be measured (concentration 10 －５ Prepare a sample (mol / L). Measure the fluorescence spectrum of this sample at room temperature (300 K). The fluorescence spectrum has the emission intensity on the vertical axis and wavelength on the horizontal axis. Draw a tangent line to the rising edge of the short-wavelength side of this fluorescence spectrum, and determine the wavelength value λedge [nm] at the intersection of this tangent line and the horizontal axis. Convert this wavelength value to an energy value using the following conversion formula: E Ｓ１ or E Ｓ２ (2) Let's assume this. Conversion formula: E Ｓ１ [eV]=1239.85 / λedge, E Ｓ２ (2) [eV] = 1239.85 / λedge The emission spectrum in the example described below was measured using an LED light source (Thorlabs, M300L4) as the excitation light source and a detector (Hamamatsu Photonics, PMA-12 multichannel spectrometer C10027-01). (2) Lowest excitation triplet energy [E Ｔ１ Lowest excitation singlet energy [E Ｓ１ The same sample used in the measurement of [ ] is cooled to 77 [K] with liquid nitrogen, and excitation light is irradiated onto the sample for phosphorescence measurement. The phosphorescence is measured using a detector. The emission from 100 milliseconds after the excitation light irradiation is taken as the phosphorescence spectrum. A tangent line is drawn to the rising edge of the short wavelength side of this phosphorescence spectrum, and the wavelength value λedge [nm] at the intersection of the tangent line and the horizontal axis is determined. This wavelength value is converted to an energy value using the following conversion formula, and the value E is obtained. Ｔ１ Let's assume that. Conversion formula: E Ｔ１[eV] = 1239.85 / λedge The tangent to the rise of the short-wavelength side of the phosphorescence spectrum is drawn as follows: When moving along the spectral curve from the short-wavelength side of the phosphorescence spectrum to the shortest wavelength maximum value of the spectrum, consider the tangent at each point on the curve toward the long-wavelength side. The slope of this tangent increases as the curve rises (i.e., as the vertical axis increases). The tangent drawn at the point where this slope value is maximum is taken as the tangent to the rise of the short-wavelength side of the phosphorescence spectrum. Note that maximum points with a peak intensity of 10% or less of the maximum peak intensity of the spectrum are not included in the shortest wavelength maximum value mentioned above, and the tangent drawn at the point closest to the shortest wavelength maximum value where the slope value is maximum is taken as the tangent to the rise of the short-wavelength side of the phosphorescence spectrum.

[0016] (3) Emission peak wavelength (λpeak) Lowest excitation singlet energy [E Ｓ１ ], energy of metastable structure [E Ｓ２ (2)) The peak emission maximum wavelength [nm] is determined from the emission spectrum used in the calculation of (2), and this is taken as the emission peak wavelength. For the overall emission peak wavelength of the second organic compound, the peak emission maximum wavelength [nm] is determined from the emission spectrum combining the fast and slow fluorescence components, and this is taken as the emission peak wavelength.

[0017] The first organic compound, the second organic compound, and the third organic compound included in the light-emitting layer of the organic electroluminescent element of the present invention will be described in detail below.

[0018] (First Organic Compound) The first organic compound is an organic compound whose lowest excited singlet energy and lowest excited triplet energy are both higher than those of the second and third organic compounds, and whose lowest excited singlet energy is higher than the energy of the metastable structure of the second organic compound. The first organic compound has the function of acting as a host responsible for carrier transport and the function of confining the energy of the second and third organic compounds within itself. This allows the energy generated by the recombination of holes and electrons within the molecule to be efficiently converted into light emission.

[0019] The first organic compound is preferably an organic compound that has hole transport ability and electron transport ability, prevents the emission from becoming longer wavelengths, and has a high glass transition temperature. In a preferred embodiment of the present invention, the first organic compound is selected from compounds that do not emit delayed fluorescence. The first organic compound is preferably a compound composed only of atoms selected from the group consisting of carbon atoms, hydrogen atoms, deuterium atoms, nitrogen atoms, oxygen atoms, and sulfur atoms. For example, the first organic compound may be a compound composed only of atoms selected from the group consisting of carbon atoms, hydrogen atoms, deuterium atoms, nitrogen atoms, and oxygen atoms. For example, the first organic compound may be a compound consisting only of carbon atoms, hydrogen atoms, nitrogen atoms, and oxygen atoms. The first organic compound may also be a compound composed only of atoms selected from the group consisting of carbon atoms, hydrogen atoms, deuterium atoms, nitrogen atoms, and sulfur atoms. The first organic compound may also be a compound that does not have a cyano group. The first organic compound may also be a compound that has only one carbazole ring. The first organic compound may be a compound containing only one metaphenylene group. The first organic compound may be a compound containing a dibenzofuran structure or a dibenzothiophene structure. The first organic compound may be a compound other than 3,3-(9H-carbazole-9-yl)biphenyl (mCBP). Furthermore, the first organic compound may be a compound having a structure in which a carbazolyl group is bonded to a benzene ring, or a compound having a structure in which a carbazolyl group and a dibenzofuryl group are bonded to a benzene ring. In a compound having a structure in which a carbazolyl group and a dibenzofuryl group are bonded to a benzene ring, the dibenzofuryl group may be bonded to the meta position of the carbaryl group, or a compound having a structure in which one carbazolyl group and one dibenzofuryl group are bonded to a benzene ring, the carbazolyl group may be a carbazole-9-yl group, and the dibenzofuryl group may be a dibenzofuran-2-yl group.

[0020] The following are specific examples of compounds that can be used as the first organic compound. However, the first organic compound that can be used in the present invention is not limited to the following examples. In the following structural formulas, D represents a deuterium atom.

[0021]

[0022] (Second Organic Compound) The second organic compound used in the organic electroluminescent element of the present invention is a delayed fluorescence material having a metastable structure in an energy band higher than the lowest excited singlet energy level. In the present invention, a "delayed fluorescence material" is a material that undergoes reverse intersystem crossing from an excited triplet state to an excited singlet state, and it is preferable that it is a thermally activated delayed fluorescence material in which the reverse intersystem crossing occurs due to the absorption of thermal energy. Whether a material is a delayed fluorescence material is determined by observing the transient decay curve of a thin film (single film) made of the delayed fluorescence material or a mixed film made of the delayed fluorescence material and a host at room temperature (300 K), and observing both emission with a short emission lifetime and emission with a long emission lifetime. In this specification, of the emission from the second organic compound observed at room temperature, fluorescence with a short emission lifetime is called the "fast fluorescence component," and fluorescence with a long emission lifetime is called the "slow fluorescence component." Generally, fluorescence with an emission lifetime (τ) of 200 ns (nanoseconds) or more is considered a "slow fluorescence component." However, since "fast fluorescence components" and "slow fluorescence components" are relative, in this invention, fluorescence with an emission lifetime (τ) of less than 200 ns may also be considered a "slow fluorescence component." In this invention, a delayed fluorescence material having a "metastable structure" is determined by obtaining the emission spectra of the fast fluorescence component and the slow fluorescence component at room temperature (300 K), and determining the wavelength value (λedge) at the intersection of the short-wavelength fitting line and the horizontal axis for the peaks appearing in each emission spectrum. The λedge of the fast fluorescence component is determined to have a shorter wavelength than the λedge of the slow fluorescence component. Here, the "emission spectrum" has the emission intensity on the vertical axis and the wavelength on the horizontal axis, and the "short-wavelength fitting line" is drawn by fitting the short-wavelength side of the emission spectrum with a straight line. For specific methods of measuring the wavelength value (λedge), please refer to the description in the Examples section.

[0023] The second organic compound is the difference ΔE between the lowest excited singlet energy and the lowest excited triplet energy at 77K. ＳＴΔE(2) is preferably 0.3 eV or less, more preferably 0.25 eV or less, still more preferably 0.2 eV or less, even more preferably 0.15 eV or less, further more preferably 0.1 eV or less, even further more preferably 0.07 eV or less, still further preferably 0.05 eV or less, even still more preferably 0.03 eV or less, and particularly preferably 0.01 eV or less. ΔE ＳＴ When ΔE(2) is small, reverse intersystem crossing from an excited singlet state to an excited triplet state is likely to occur due to absorption of thermal energy, so the second organic compound functions as a thermally activated delayed fluorescent material. A thermally activated delayed fluorescent material can absorb heat emitted by a device, relatively easily undergo reverse intersystem crossing from an excited triplet state to an excited singlet state, and allow the excited triplet energy to contribute to light emission efficiently. The difference E between the energy of the metastable structure of the second organic compound and the lowest excited singlet energy Ｓ２ (2) - E Ｓ１ (2) and E Ｓ２ For the preferred ranges of (2), reference can be made to the above description of formula (I).

[0024] The second organic compound is a delayed fluorescence material whose lowest excited singlet energy and lowest excited triplet energy are both lower than those of the first organic compound, and whose lowest excited singlet energy and lowest excited triplet energy are both higher than those of the third organic compound, and whose metastable structure energy is lower than that of the first organic compound and higher than that of the second organic compound. The second organic compound can be any compound that can emit both a fast fluorescence component and a slow fluorescence component under certain conditions. In the organic electroluminescent element of the present invention, it is not essential to observe luminescence originating from the second organic compound, and luminescence from the third organic compound is the main emission. In the organic electroluminescent element of the present invention, the second organic compound receives energy from the first organic compound in an excited singlet state and transitions to a metastable structure. Alternatively, the second organic compound may receive energy from the first organic compound in an excited singlet state and transition to an excited singlet state, or it may receive energy from the first organic compound in an excited triplet state and transition to an excited triplet state. The second organic compound is ΔE ＳＴ Because of its small size, the second organic compound in the excited triplet state readily crosses back into the excited singlet state of the second organic compound. The metastable structure of the second organic compound and the excited singlet state of the second organic compound formed by these pathways transfer energy to the third organic compound, causing the third organic compound to transition to the excited singlet state.

[0025] The second organic compound is preferably a compound composed only of atoms selected from the group consisting of carbon atoms, hydrogen atoms, deuterium atoms, nitrogen atoms, oxygen atoms, and sulfur atoms. For example, the second organic compound may be a compound composed only of atoms selected from the group consisting of carbon atoms, hydrogen atoms, deuterium atoms, nitrogen atoms, and oxygen atoms. For example, the second organic compound may be a compound consisting only of carbon atoms, hydrogen atoms, nitrogen atoms, and oxygen atoms. Alternatively, the second organic compound may be a compound composed only of atoms selected from the group consisting of carbon atoms, hydrogen atoms, deuterium atoms, nitrogen atoms, and sulfur atoms. Alternatively, the second organic compound may be a compound composed only of atoms selected from the group consisting of carbon atoms, hydrogen atoms, deuterium atoms, and nitrogen atoms.

[0026] In one aspect of the present invention, a delayed fluorescence material having a metastable structure in an energy band higher than the lowest excited singlet energy level is selected from among compounds having a structure in which a donor group is bonded to the ortho position of a benzene ring to which an acceptor group is bonded, and used as the second organic compound. In this specification, "acceptor group" is a group that has the property of withdrawing electrons from the aromatic ring to which the acceptor group is bonded, and can be selected from groups with a positive Hammett σp value, for example. "Donor group" is a group that has the property of donating electrons to the aromatic ring to which the donor group is bonded, and can be selected from groups with a negative Hammett σp value, for example. Here, "Hammett σp value" was proposed by L. P. Hammett and quantifies the effect of substituents on the reaction rate or equilibrium of para-substituted benzene derivatives. Specifically, it is a constant (σp) specific to the substituent in the following equation that holds between the substituent and the reaction rate constant or equilibrium constant in a para-substituted benzene derivative: log(k / k0) = ρσp or log(K / K0) = ρσp. In the above equation, k0 is the rate constant of the unsubstituted benzene derivative, k is the rate constant of the substituted benzene derivative, K0 is the equilibrium constant of the unsubstituted benzene derivative, K is the equilibrium constant of the substituted benzene derivative, and ρ is the reaction constant determined by the type and conditions of the reaction. For an explanation of "Hammett's σp value" in this invention and the numerical values ​​of each substituent, refer to the description of σp values ​​in Hansch, C. et. al., Chem. Rev., 91, 165-195 (1991).

[0027] In a compound having a structure in which a donor group is bonded to the ortho position of a benzene ring to which an acceptor group is bonded, positions other than the ortho position of the acceptor group may be unsubstituted or substituted with a substituent. The substituent may be an acceptor group or a donor group, and may be a substituted or unsubstituted aryl group (for example, an aryl group having 6 to 40 carbon atoms). For examples of donor groups and acceptor groups, reference can be made to the following examples of donor groups and acceptor groups. Examples of compounds having a structure in which a donor group is bonded to the ortho position of a benzene ring to which an acceptor group is bonded include: a compound in which one of the substitutable positions of the benzene ring is substituted with an acceptor group and all remaining substitutable positions are substituted with donor groups; a compound in which one of the substitutable positions of the benzene ring is substituted with an acceptor group, the para position of the acceptor group is substituted with a substituted or unsubstituted aryl group, and all remaining substitutable positions are substituted with donor groups; and a compound in which one of the substitutable positions of the benzene ring is substituted with an acceptor group, the meta position thereof is also substituted with an acceptor group, the ortho positions of the two acceptor groups are substituted with donor groups, and all remaining substitutable positions are unsubstituted.

[0028] Examples of the "donor group" in a compound having a structure in which a donor group is bonded to the ortho position of a benzene ring to which an acceptor group is bonded include groups represented by the following general formula (1). General formula (1)

[0029] In general formula (1), R １ to R １０ each independently represent a hydrogen atom or a substituent. The number of deuterium atoms or substituents is not particularly limited, and all of R １ to R １０ may be unsubstituted (that is, hydrogen atoms). Also, for example, all of R １ to R １０ may be deuterium atoms. When two or more of R １ to R １０ are substituents, the plurality of substituents may be the same or different from each other. R １ to R １０The deuterium atoms and substituents that can be taken may be selected from, for example, group A, group B, group C, group D, group E, or from any of the groups A to E described below. In one embodiment of the present invention, R １ ~R １０ The substituents that can be taken are a hydroxyl group, a halogen atom, a C1-C20 alkyl group, a C1-C20 alkoxy group, a C1-C20 alkylthio group, a C1-C20 alkyl-substituted amino group, a C1-C20 aryl-substituted amino group, a C6-C40 aryl group, a C3-C40 heteroaryl group, a C2-C10 alkenyl group, a C2-C10 alkynyl group, a C2-C20 alkylamide group, a C7-C21 arylamide group, and a C3-C20 trialkylsilyl group. Among these specific examples, those that can be further substituted by substituents may be substituted, and if further substituted, for example, they may be selected from group D described later, or for example, from group E described later. In one aspect of the present invention, R １ ~R １０ The substituents that can be taken are C1-C20 alkyl groups, C1-C20 alkoxy groups, C1-C20 alkylthio groups, C1-C20 alkyl-substituted amino groups, C1-C20 aryl-substituted amino groups, C6-C40 aryl groups, and C3-C40 heteroaryl groups. Among these specific examples, those that can be further substituted with substituents may be substituted, and if further substituted, for example, they may be selected from group D described below, or for example, from group E described below.

[0030] R １ and R ２ , R ２ and R ３ , R ３ and R ４ , R ４ and R ５ , R ５ and R ６ , R ６ and R ７ , R ７ and R ８ , R８ and R ９ , R ９ and R １０ These elements may be bonded to each other to form a cyclic structure. The cyclic structure may be an aromatic ring or an antilipid ring, and may contain heteroatoms. Furthermore, the cyclic structure may be a fused ring of two or more rings. The heteroatoms referred to here are preferably selected from the group consisting of nitrogen atoms, oxygen atoms, and sulfur atoms. Examples of the cyclic structures formed include benzene rings, naphthalene rings, pyridine rings, pyridazine rings, pyrimidine rings, pyrazine rings, pyrrole rings, imidazole rings, pyrazole rings, imidazoline rings, oxazole rings, isoxazole rings, thiazole rings, isothiazole rings, cyclohexadiene rings, cyclohexene rings, cyclopentaene rings, cycloheptatriene rings, cycloheptadiene rings, and cycloheptaene rings. The cyclic structures formed may be substituted with deuterium atoms or substituents, or they may be unsubstituted. The deuterium atoms and substituents referred to herein may be selected from, for example, group A, group B, group C, group D, group E, or from any multiple of groups A through E.

[0031] Among the groups represented by general formula (1), R ５ and R ６ Those that are not bonded to each other, R ５ and R ６ Those that are connected to each other by single bonds, or R ５ and R ６ It is preferable that the atoms are bonded to each other to form a linking group with a chain length of one atom. ５ and R ６ When they are bonded to each other to form a linking group with a chain length of 1 atom, R ５ and R ６ The resulting ring structure formed by the bonding of these elements is a six-membered ring. ５ and R ６ Specific examples of linking groups formed by the bonding of these groups include -O-, -S-, and -N(R) Ａ ) - or - C (R Ｂ) (Caution Ｃ A linking group represented by ) is an example. Here, R Ａ ~R Ｃ Each of these independently represents a hydrogen atom, a deuterium atom, or a substituent. The deuterium atom and substituent referred to here may be selected from, for example, group A, group B, group C, group D, group E, or from any of the groups A to E. In one embodiment of the present invention, R Ａ Examples of substituents that can be formed include alkyl groups having 1 to 20 carbon atoms, aryl groups having 6 to 40 carbon atoms, and heteroaryl groups having 3 to 40 carbon atoms. Ｂ and R Ｃ Examples of substituents that can be taken include, independently, a hydroxyl group, a halogen atom, a C1-C20 alkyl group, a C1-C20 alkoxy group, a C1-C20 alkylthio group, a C1-C20 alkyl-substituted amino group, a C1-C20 aryl-substituted amino group, a C6-C40 aryl group, a C3-C40 heteroaryl group, a C2-C10 alkenyl group, a C2-C10 alkynyl group, a C2-C20 alkylamide group, a C7-C21 arylamide group, and a C3-C20 trialkylsilyl group. Of these specific substituents, those that can be further substituted by other substituents may be substituted, and if further substituted, for example, they may be selected from group D described below, or for example, from group E described below.

[0032] In general formula (1), L represents a single bond, a substituted or unsubstituted arylene group, or a substituted or unsubstituted heteroarylene group. * represents the bond position to the carbon atoms (C) constituting the benzene ring. L is preferably a single bond or a substituted or unsubstituted arylene group. The aromatic ring constituting the arylene group represented by L may be a monoring, a fused ring formed by the fusion of two or more aromatic rings, or a linked ring formed by the linkage of two or more aromatic rings. If two or more aromatic rings are linked, they may be linked in a linear chain or in a branched chain. The number of carbon atoms in the aromatic ring constituting the arylene group represented by L is preferably 6 to 22, more preferably 6 to 18, even more preferably 6 to 14, and even more preferably 6 to 10. Specific examples of arylene groups include phenylene, naphthalenediyl, and biphenylene groups. Furthermore, the heterocycle constituting the heteroarylene group represented by L may be a monocycle, a fused ring formed by the fusion of one or more heterocycles with an aromatic ring or a heterocycle, or a linked ring formed by the linkage of one or more heterocycles with an aromatic ring or a heterocycle. The number of carbon atoms in the heterocycle is preferably 5 to 22, more preferably 5 to 18, even more preferably 5 to 14, and even more preferably 5 to 10. The heteroatoms constituting the heterocycle are preferably nitrogen atoms. Specific examples of heterocycles include pyridine rings, pyridazine rings, pyrimidine rings, triazole rings, and benzotriazole rings. A more preferred group represented by L is a phenylene group. When L is a phenylene group, the phenylene group may be any of 1,2-phenylene, 1,3-phenylene, or 1,4-phenylene, but 1,4-phenylene is preferred. Also, L may be substituted with substituents. The number and position of substituents on L are not particularly limited. For a description of the substituents that can be introduced into L and their preferred ranges, see the above R. １ ~R １０ You can refer to the description of possible substituents and their preferred ranges.

[0033] A preferred example of a group represented by general formula (1) is a group represented by any of the following general formulas (2) to (7). General formula (2) General formula (3) General formula (4) General formula (5) General formula (6) General formula (7)

[0034] In general formulas (2) to (7), R １１ ~R １８ , R ２１ ~R ２８ , R ３１ ~R ３８ , R ４１ ~R ４８ , R ５１ ~R ５５ , R ６１ ~R ８０ Each of these independently represents a hydrogen atom, a deuterium atom, or a substituent. For a description of the deuterium atom and substituent and their preferred ranges, see the above R １ ~R １０ You can refer to the description and preferred range of deuterium atoms and substituents that can be taken by R. １１ ~R １８ , R ２１ ~R ２８ , R ３１ ~R ３８ , R ４１ ~R ４８ , R ５１ ~R ５５ , R ６１ ~R ６８ , R ７１ ~R ７８ It is also preferable that each of these groups be independently represented by one of the general formulas (2) to (7) above. The number of substituents in general formulas (2) to (7) is not particularly limited. It is also preferable that all substituents are unsubstituted (i.e., hydrogen atoms) or all substituents are deuterium atoms. Furthermore, if each of general formulas (2) to (7) has two or more substituents, these substituents may be the same or different.

[0035] In general formulas (2) to (7), R １１ and R １２ , R １２ and R １３ , R １３ and R １４ , R １５ and R １６, R １６ and R １７ , R １７ and R １８ , R ２１ and R ２２ , R ２２ and R ２３ , R ２３ and R ２４ , R ２５ and R ２６ , R ２６ and R ２７ , R ２７ and R ２８ , R ３１ and R ３２ , R ３２ and R ３３ , R ３３ and R ３４ , R ３５ and R ３６ , R ３６ and R ３７ , R ３７ and R ３８ , R ４１ and R ４２ , R ４２ and R ４３ , R ４３ and R ４４ , R ４５ and R ４６ , R ４６ and R ４７ , R ４７ and R ４８ , R ５１ and R ５２ , R ５２ and R ５３ , R ５３ and R ５４ , R ５４ and R ５５ , R ４４ and R ５１ , R ４５ and R ５５ , R ６１ and R ６２ , R ６２ and R ６３ , R ６３ and R ６４ , R ６５ and R ６６ , R ６６ and R ６７ , R ６７ and R ６８ , R ６９ and R ７０ , R７１ and R ７２ , R ７２ and R ７３ , R ７３ and R ７４ , R ７５ and R ７６ , R ７６ and R ７７ , R ７７ and R ７８ , R ７９ and R ８０ These may be bonded to each other to form a ring structure. For a description of the ring structure and preferred examples, see the general formula (1) above, where R １ and R ２ You can refer to a description and preferred examples of the annular structure formed by the combination of these elements.

[0036] In general formulas (2) to (7), L １ ~L ６ * represents a single bond, a substituted or unsubstituted arylene group, or a substituted or unsubstituted heteroarylene group. * represents the bond position to the carbon atoms (C) constituting the benzene ring. １ ~L ６ For a description of the arylene group or heteroarylene group represented by L, and the substituents that can be introduced to these groups, and their preferred ranges, refer to the description of the arylene group or heteroarylene group represented by L, and the substituents that can be introduced to these groups, and their preferred ranges. １ ~L ６ It is preferable that the arylene group is a single bond, substituted, or unsubstituted group.

[0037] An example of an "acceptor group" in a compound having a structure in which a donor group is bonded to the ortho position of a benzene ring to which an acceptor group is bonded is the group represented by the following general formula (8). General formula (8)

[0038] In general formula (8), A １ ~A ５ Each is independently N or C(R) １９ ) represents R １９ represents a hydrogen atom, a deuterium atom, or a substituent. A １ ~A ５At least one of them is N, more preferably 1 to 3 are N, and even more preferably 3 are N. The group represented by general formula (8) is R １９ When there are multiple R １９ They may be the same or different from each other. １９ The deuterium atoms and substituents that can be taken may be selected from, for example, group A, group B, group C, group D, group E, or from any of the groups A to E described below. In one embodiment of the present invention, R １９ Examples of substituents that can be taken include alkyl groups having 1 to 20 carbon atoms, aryl groups having 6 to 40 carbon atoms, cyano groups, halogen atoms, heteroaryl groups having 5 to 40 carbon atoms, and aryl groups having 6 to 40 carbon atoms are preferred. Substituents that can be substituted with other substituents may be substituted, and if they are substituted, they may be selected from group D described later, or from group E described later. In general formula (8), L ７ * represents a single bond, a substituted or unsubstituted arylene group, or a substituted or unsubstituted heteroarylene group. * represents the bond position to the carbon atoms (C) constituting the benzene ring. ７ For a description of the arylene group or heteroarylene group represented by L, and the substituents that can be introduced to these groups, and their preferred ranges, refer to the description of the arylene group or heteroarylene group represented by L, and the substituents that can be introduced to these groups, and their preferred ranges. ７ It is preferably a substituted or unsubstituted arylene group, more preferably a substituted or unsubstituted phenylene group, and even more preferably an unsubstituted phenylene group. ７ When is a substituted or unsubstituted phenylene group, the phenylene group may be any of 1,2-phenylene, 1,3-phenylene, or 1,4-phenylene, but it is preferably a 1,4-phenylene group.

[0039] As an example of a compound having a structure in which a donor group is bonded to the ortho position of a benzene ring to which an acceptor group is bonded, we can refer to a compound having a structure in which a substituted or unsubstituted carbazole-9-yl group is bonded to the ortho position of a benzene ring to which a substituted or unsubstituted triazinyl group is bonded. Preferred examples of substituted or unsubstituted triazinyl groups include a substituted or unsubstituted 4,6-diphenyl-1,3,5-triazin-2-yl group and a 1,3,5-triazin-2-yl group in which the 4-position is a substituted or unsubstituted phenyl group and the 6-position is a substituted or unsubstituted carbazole-9-yl group. In a compound having a structure in which a substituted or unsubstituted carbazole-9-yl group is bonded to the ortho position of a benzene ring to which a substituted or unsubstituted triazinyl group is bonded, positions other than the ortho position of the substituted or unsubstituted triazinyl group may be unsubstituted or substituted with substituents. The substituent may be either an acceptor group or a donor group, and may be, for example, a substituted or unsubstituted aryl group (e.g., an aryl group having 6 to 40 carbon atoms). For examples of donor and acceptor groups, refer to the examples of donor and acceptor groups above. Examples of compounds having a structure in which a substituted or unsubstituted carbazole-9-yl group is bonded to the ortho position of a benzene ring to which a substituted or unsubstituted triazinyl group is attached include: a compound in which one of the substituted positions of the benzene ring is substituted with a substituted or unsubstituted triazinyl group and all of the remaining substituted positions are substituted with a substituted or unsubstituted carbazole-9-yl group; a compound in which one of the substituted positions of the benzene ring is substituted with a substituted or unsubstituted triazinyl group, the para position of its acceptor group is substituted with a substituted or unsubstituted aryl group, and all of the remaining substituted positions are substituted with a substituted or unsubstituted carbazole-9-yl group; and a compound in which one of the substituted positions of the benzene ring is substituted with a substituted or unsubstituted triazinyl group, its meta position is also substituted with a substituted or unsubstituted triazinyl group, the ortho positions of the two substituted or unsubstituted triazinyl groups are substituted with a substituted or unsubstituted carbazole-9-yl group, and the remaining substituted positions are unsubstituted.Furthermore, the substituted or unsubstituted carbazole-9-yl groups mentioned in the explanation of acceptor groups include, for example, those formed by the condensation of cyclic structures such as substituted or unsubstituted benzofloxacin structures and substituted or unsubstituted benzothieno structures.

[0040] As an example of a compound having a structure in which a donor group is bonded to the ortho position of a benzene ring to which an acceptor group is bonded, there is also a compound in which another donor group is further bonded to the benzene ring, and the ortho donor group and the other donor group are bonded to each other with a substituted or unsubstituted arylene group or a substituted or unsubstituted heteroarylene group as linking groups to form a cyclic structure. In this case, it is preferable that a cyclic structure with a minimum number of linked atoms of 12 to 14 is formed by the benzene ring, the ortho donor group, the linking group and the other donor group. The minimum number of linked atoms referred to here is the number of ring constituent atoms when the ring constituent atoms are selected so as to minimize the number of atoms constituting the ring of the cyclic structure. The minimum number of linked atoms of the cyclic structure is, for example, 12, for example, 13, and for example, 14. In one aspect of the present invention, the other donor group is bonded to the para position with respect to the acceptor group. In one aspect of the present invention, the minimum number of linked atoms is 12, and the benzene ring, the ortho-position donor group, the linking group, and another donor group each constitute 3 atoms of the minimum number of linked atoms. In one aspect of the present invention, the donor group and the other donor group are each independently substituted or unsubstituted carbazole-diyl groups, for example, substituted or unsubstituted carbazole-1,8-diyl groups or substituted or unsubstituted carbazole-1,9-diyl groups. In one aspect of the present invention, the linking group is a substituted or unsubstituted phenylene group, for example, a substituted or unsubstituted 1,3-phenylene group.

[0041] As an example of a compound having a structure in which a donor group is bonded to the ortho position of a benzene ring to which an acceptor group is bonded, we can also cite a compound in which a second donor group and a third donor group are further bonded to the benzene ring, and the ortho donor group, the second donor group, and the third donor group are bonded to each other via a substituted or unsubstituted aromatic ring as a linking group to form a cage-like structure. In this case, the benzene ring and the linking group are linked via the ortho donor group, the second donor group, and the third donor group, respectively. The cage-like structure consists of three cyclic structures, and it is preferable that the minimum number of linked atoms in each cyclic structure is 12 to 14 independently. The minimum number of linked atoms in the three cyclic structures may be the same or different, but it is preferable that they be the same, for example, all of them being 12. In one aspect of the present invention, the second donor group bonded to the benzene ring is bonded at the para position relative to the acceptor group, and the third donor group is bonded at the ortho position relative to the acceptor group. In one aspect of the present invention, the linking group is a benzene ring, which may be substituted with a deuterium atom or a substituent, for example, bonded at the 1st, 3rd, and 5th positions to the ortho donor group, the second donor group, and the third donor group, respectively.

[0042] In one aspect of the present invention, a compound having a metastable structure in an energy band higher than the lowest excited singlet energy level is selected from among C2 symmetric delayed fluorescence materials and used as a second organic compound. A compound having a C2 symmetric structure has a structure that overlaps with the original image when rotated 180° around an axis (C axis) passing through the molecular center. In one aspect of the present invention, a compound having a metastable structure in an energy band higher than the lowest excited singlet energy level is selected from among C2 symmetric delayed fluorescence materials having a structure in which a donor group is bonded to the ortho position of a benzene ring to which an acceptor group is bonded and used as a second organic compound.

[0043] In one aspect of the present invention, the S value of the second organic compound in the light-emitting layer is less than -0.2. Here, the S value is an index indicating the degree of orientation of the second organic compound. A larger negative S value (a smaller numerical value) indicates higher orientation. The S value can be determined by the method described in Scientific Reports 2017, 7, 8405. The S value of the second organic compound in the light-emitting layer may be, for example, less than -0.3 or less than -0.4.

[0044] The following are specific examples of compounds that can be used as secondary organic compounds. In the following structural formulas, methyl groups are omitted from the representation; for example, the two carbazole rings in the seventh compound each have two methyl groups. D represents a deuterium atom.

[0045]

[0046] (Third Organic Compound) The third organic compound is a compound whose lowest excited singlet energy and lowest excited triplet energy are both lower than those of the first and second organic compounds. The organic electroluminescent element of the present invention emits fluorescence originating from the third organic compound. The emission from the third organic compound usually includes delayed fluorescence. The largest component of the emission from the organic electroluminescent element of the present invention is emission from the third organic compound. That is, the amount of emission from the third organic compound is the largest of the emission from the organic electroluminescent element of the present invention. The third organic compound transitions to the excited singlet state by receiving energy from the first organic compound in the excited singlet state, the second organic compound in the metastable structure, the second organic compound in the excited singlet state, and the second organic compound that has transitioned from the excited triplet state to the excited singlet state through reverse intersystem crossing. In a preferred embodiment of the present invention, the third organic compound transitions to the excited singlet state by receiving energy from the second organic compound in the metastable structure and the second organic compound that has transitioned from the excited triplet state to the excited singlet state through reverse intersystem crossing. The excited singlet state of the resulting third organic compound emits fluorescence when it returns to the ground state. The fluorescent material used as the third organic compound is not particularly limited as long as it can receive energy from the first and second organic compounds and emit light in this way, and the emission may include fluorescence, delayed fluorescence, or phosphorescence. Preferably, the emission includes fluorescence or delayed fluorescence, and more preferably, the largest component of the emission from the third organic compound is fluorescence. Two or more third organic compounds may be used as long as they satisfy the conditions of the present invention. For example, by using two or more third organic compounds with different emission colors in combination, it is possible to emit a desired color. Alternatively, monochromatic emission may be produced from the third organic compound using only one type of third organic compound. In the present invention, the emission peak wavelength of the compound that can be used as the third organic compound is not particularly limited. Therefore, it is possible to appropriately select and use emission materials having an emission peak wavelength in the visible region (380 to 780 nm) or emission materials having an emission peak wavelength in the infrared region (780 nm to 1 mm). Preferably, a fluorescent material having an emission peak wavelength in the visible region is used.For example, a light-emitting material may be selected and used in which the emission peak wavelength within the region of 380 to 780 nm is in the range of 380 to 570 nm, or in which the emission peak wavelength is in the range of 380 to 500 nm, or in which the emission peak wavelength is in the range of 380 to 480 nm, or in which the emission peak wavelength is in the range of 420 to 480 nm. In one aspect of the present invention, the emission peak wavelength of the third organic compound is 500 nm or less, and can be, for example, 490 nm or less, or 485 nm or less. The present invention is particularly useful when a third organic compound having an emission peak wavelength in the blue region (420 to 480 nm) is used.

[0047] The third organic compound is preferably a compound composed only of atoms selected from the group consisting of carbon atoms, hydrogen atoms, deuterium atoms, nitrogen atoms, boron atoms, oxygen atoms, and sulfur atoms. For example, the third organic compound may be a compound composed only of atoms selected from the group consisting of carbon atoms, hydrogen atoms, deuterium atoms, nitrogen atoms, boron atoms, and oxygen atoms. The third organic compound may be a compound composed only of atoms selected from the group consisting of carbon atoms, hydrogen atoms, deuterium atoms, nitrogen atoms, boron atoms, and sulfur atoms. The third organic compound may be a compound composed only of atoms selected from the group consisting of carbon atoms, hydrogen atoms, deuterium atoms, nitrogen atoms, and boron atoms. For example, the third organic compound may be a compound consisting only of carbon atoms, hydrogen atoms, nitrogen atoms, and boron atoms. The third organic compound may be a compound that does not have a cyano group. The third organic compound may be a compound having a multiple resonance effect, for example, a compound having a multiple resonance effect between boron atoms and nitrogen atoms. The third organic compound may be a compound having a diarylamino group.

[0048] A third organic compound can be listed as a compound represented by the following general formula (F1). General formula (F1)

[0049] In the general formula (F1), R １ , R ３ ~R １６Each of these independently represents a hydrogen atom, a deuterium atom, or a substituent. ２ represents an acceptor group, or R １ and R ２ Either they are bonded to each other to form an acceptor group, or R ２ and R ３ These groups are bonded to each other to form an acceptor group. ３ and R ４ , R ４ and R ５ , R ５ and R ６ , R ６ and R ７ , R ７ and R ８ , R ９ and R １０ , R １０ and R １１ , R １１ and R １２ , R １２ and R １３ , R １３ and R １４ , R １４ and R １５ , R １５ and R １６ They may be joined to each other to form a ring structure. １ represents O or NR, and R represents a substituent. X ２ ~X ４ Of these, X ３ and X ４ At least one of the atoms is O or NR, and the other may be O or NR but not linked. When not linked, each end independently represents a hydrogen atom, a deuterium atom, or a substituent. C-R in general formula (F1) １ , C-R ３ , C-R ４ , C-R ５ , C-R ６ , C-R ７ , C-R ８ , C-R ９ , C-R １０ , C-R １１ , C-R １２ , C-R １３ , C-R １４ , C-R １５ , C-R １６It may be replaced with N.

[0050] In one aspect of the present invention, X ２ When R is O or NR, ７ Is R an acceptor group? ６ and R ７ Either they are bonded to each other to form an acceptor group, or R ７ and R ８ These are bonded to each other to form an acceptor group. In one aspect of the present invention, X ３ When R is O or NR, １０ Is R an acceptor group? ９ and R １０ Either they are bonded to each other to form an acceptor group, or R １０ and R １１ These are bonded to each other to form an acceptor group. In one aspect of the present invention, X ４ When R is O or NR, １５ Is R an acceptor group? １４ and R １５ Either they are bonded to each other to form an acceptor group, or R １５ and R １６ These are bonded to each other to form an acceptor group. In one aspect of the present invention, X ２ NR is NR, and R is a substituted or unsubstituted phenyl group. ８ When a carbazole ring is formed by direct bonding with a carbon atom to which is bonded, at least one of the 3-position and 6-position of the carbazole ring is substituted with an acceptor group. In one aspect of the present invention, X ３ NR is NR, and R is a substituted or unsubstituted phenyl group. ９ When a carbazole ring is formed by direct bonding with a carbon atom to which is bonded, at least one of the 3-position and 6-position of the carbazole ring is substituted with an acceptor group. In one aspect of the present invention, X ４ NR is NR, and R is a substituted or unsubstituted phenyl group. １６When a carbazole ring is formed by direct bonding with a carbon atom to which is bonded, at least one of the 3-position and 6-position of the carbazole ring is substituted with an acceptor group. In one aspect of the present invention, X １ NR is NR, and R is a substituted or unsubstituted phenyl group. １ When a carbazole ring is formed by direct bonding with a carbon atom to which the phenyl group is bonded, the 3-position of the carbazole ring is substituted with an acceptor group (where the 3-position is located on the phenyl group). In one aspect of the present invention, the compound is represented by the following general formula (F2). General formula (F2)

[0051] In the general formula (F2), R １ , R ３ , R ６ ~R １１ , R １４ ~R １６ Each of these independently represents a hydrogen atom, a deuterium atom, or a substituent. ２ represents an acceptor group, or R １ and R ２ Either they are bonded to each other to form an acceptor group, or R ２ and R ３ These groups are bonded to each other to form an acceptor group. ６ and R ７ , R ７ and R ８ , R ９ and R １０ , R １０ and R １１ , R １４ and R １５ , R １５ and R １６ They may be joined to each other to form a ring structure. １ represents O or NR, and R represents a substituent. X ２ ~X ４ Of these, X ３ and X ４ At least one of the atoms is O or NR, and the other may be O or NR but not linked. When not linked, each end independently represents a hydrogen atom, a deuterium atom, or a substituent. Ar １ and Ar２ Each of these independently represents a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group. C-R in general formula (F2) １ , C-R ３ , C-R ６ , C-R ７ , C-R ８ , C-R ９ , C-R １０ , C-R １１ , C-R １４ , C-R １５ , C-R １６ It may be replaced with N.

[0052] As a third organic compound, a compound represented by the following general formula (F3) can also be mentioned. General formula (F3)

[0053] In the general formula (F3), R １ and R ２ Each independently represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group, R ３ ~R １６ Each of these independently represents a hydrogen atom, a deuterium atom, or a substituent. １ and R ３ , R ３ and R ４ , R ４ and R ５ , R ５ and R ６ , R ６ and R ７ , R ７ and R ８ , R ８ and R ９ , R ９ and R ２ , R ２ and R １０ , R １０ and R １１ , R １１ and R １２ , R １２ and R １３ , R １３ and R １４ , R １４ and R １５ , R １５ and R １６ , R１６ and R １ They may be bonded to each other to form a ring structure. C-R in general formula (F3) ３ , C-R ４ , C-R ５ , C-R ６ , C-R ７ , C-R ８ , C-R ９ , C-R １０ , C-R １１ , C-R １２ , C-R １３ , C-R １４ , C-R １５ , C-R １６ This may be replaced with N.

[0054] In one aspect of the present invention, R １ and R ２ R is a substituted or unsubstituted phenyl group, each independently of which other rings may be fused to it. In one aspect of the present invention, R ３ and R １０ Each of these is independently a substituted amino group. In one aspect of the present invention, R １ and R ３ , and, R ２ and R １０ At least one combination of these elements is bonded to each other to form a cyclic structure. In one aspect of the present invention, the cyclic structure includes a benzoazavorin ring.

[0055] As a third organic compound, a compound represented by the following general formula (F4) can also be mentioned. General formula (F4)

[0056] In the general formula (F4), Z １ and Z ２ Each of these independently represents a substituted or unsubstituted aromatic hydrocarbon ring, or a substituted or unsubstituted heteroaromatic ring, R １ ~R ９ Each of these independently represents a hydrogen atom, a deuterium atom, or a substituent. １ and R ２ , R ２ and R ３ , R ３ and R ４ , R ４ and R ５ , R５ and R ６ , R ７ and R ８ , R ８ and R ９ They may be bonded to each other to form a ring structure. However, Z １ Z ２ , R １ and R ２ A ring formed by the bonding of these elements, R ２ and R ３ A ring formed by the bonding of these elements, R ４ and R ５ A ring formed by the bonding of these elements, and R ５ and R ６ At least one of the rings formed by the bonding of these elements is a furan ring of a substituted or unsubstituted benzofuran, a thiophene ring of a substituted or unsubstituted benzothiophene, or a pyrrole ring of a substituted or unsubstituted indole, and R １ ~R ９ At least one of them is a substituted or unsubstituted aryl group, or an acceptor group, or Z １ and Z ２ At least one of the rings has an aryl group or an acceptor group as a substituent. Substitutable carbon atoms among the benzene ring skeleton constituent carbon atoms constituting the benzofuran ring, the benzothiophene ring, and the indole ring may be substituted with nitrogen atoms. C-R in general formula (F4) １ , C-R ２ , C-R ３ , C-R ４ , C-R ５ , C-R ６ , C-R ７ , C-R ８ , C-R ９ It may be replaced with N.

[0057] In one aspect of the present invention, Z １ and Z ２ However, each is independently a substituted or unsubstituted uncondensed benzene ring, a furan ring formed by the condensation of a substituted or unsubstituted benzene ring, a thiophene ring formed by the condensation of a substituted or unsubstituted benzene ring, or a pyrrole ring formed by the condensation of a substituted or unsubstituted benzene ring. In one embodiment of the present invention, R １~R ９ However, each is independently a substituted or unsubstituted aryl group, or an acceptor group, or R １ and R ２ A ring formed by the bonding of these elements, R ２ and R ３ A ring formed by the bonding of these elements, R ４ and R ５ A ring formed by the bonding of these elements, and R ５ and R ６ One or more rings selected from the group consisting of rings formed by the bonding of to each other are a furan ring formed by the condensation of substituted or unsubstituted benzene rings, a thiophene ring formed by the condensation of substituted or unsubstituted benzene rings, or a pyrrole ring formed by the condensation of substituted or unsubstituted benzene rings. In one aspect of the present invention, R ８ The group is a substituted or unsubstituted aryl group or an acceptor group. In one aspect of the present invention, the group comprises two or more rings selected from the group consisting of a benzofuran ring, the benzothiophene ring, and the indole ring.

[0058] As a third organic compound, we can list compounds having a fused ring structure A (where hydrogen atoms in the structure may be substituted with deuterium atoms or substituents) in which a furan ring constituting a substituted or unsubstituted benzofuran ring, a thiophene ring constituting a substituted or unsubstituted benzothiophene ring, or a pyrrole ring constituting a substituted or unsubstituted indole ring is fused to the carbon-carbon bond a of structure α below, or a benzene ring constituting a substituted or unsubstituted dibenzofuran ring, a benzene ring constituting a substituted or unsubstituted dibenzothiophene ring, a benzene ring constituting a substituted or unsubstituted carbazole ring, or a benzene ring constituting a substituted or unsubstituted dibenzodioxane ring is fused to the carbon-carbon bond b (hydrogen atoms in the structure may be substituted with deuterium atoms or substituents). Structure α

[0059] In structure α, X １ and X ２ Each of the following independently represents a substituted or unsubstituted aryl group, or a nitrogen atom or oxygen atom to which a substituted or unsubstituted aryl group is bonded; Z represents a substituted or unsubstituted aromatic hydrocarbon ring, or a substituted or unsubstituted heteroaromatic ring; R１ represents a hydrogen atom, a deuterium atom, or a substituent, and Z and X ２ They may be bonded to each other to form a ring structure. In the fused ring structure A, the structure condensed with b and X １ , a condensed structure with b and Z, Z and X ２ They may be joined together to form a ring structure.

[0060] As a third organic compound, a compound represented by the following general formula (F5) can also be mentioned. General formula (F5)

[0061] In the general formula (F5), Z １ This represents a furan ring formed by the condensation of substituted or unsubstituted benzene rings, a thiophene ring formed by the condensation of substituted or unsubstituted benzene rings, or an N-substituted pyrrole ring formed by the condensation of substituted or unsubstituted benzene rings, Z ２ and Z ３ Each of these independently represents a substituted or unsubstituted aromatic hydrocarbon ring, or a substituted or unsubstituted heteroaromatic ring, R １ R represents a hydrogen atom, a deuterium atom, or a substituent. ２ and R ３ Each of these independently represents a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group. １ and R １ , R ２ and Z ２ Z ２ and Z ３ Z ３ and R ３ They may be bonded to each other to form a ring structure. However, R ２ and Z ２ Z ２ and Z ３ Z ３ and R ３ At least one pair of these elements are joined together to form a ring structure.

[0062] As a third organic compound, a compound represented by the following general formula (F6) can also be mentioned. General formula (F6)

[0063] In the general formula (F6), X ３represents an oxygen atom or a sulfur atom, Z ２ and Z ３ Each of these independently represents a substituted or unsubstituted aromatic hydrocarbon ring, or a substituted or unsubstituted heteroaromatic ring, R １ and R ４ ~R ７ R represents a hydrogen atom, a deuterium atom, or a substituent. ２ and R ３ Each of these independently represents a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group. ２ and Z ２ Z ２ and Z ３ Z ３ and R ３ , R ４ and R ５ , R ５ and R ６ , R ６ and R ７ They may be bonded to each other to form a ring structure. However, R ２ and Z ２ Z ２ and Z ３ Z ３ and R ３ At least one pair of these elements are joined together to form a ring structure.

[0064] As a third organic compound, a compound represented by the following general formula (F7) can also be mentioned. General formula (F7)

[0065] In the general formula (F7), X ４ represents an oxygen atom or a sulfur atom, Z ２ and Z ３ Each of these independently represents a substituted or unsubstituted aromatic hydrocarbon ring, or a substituted or unsubstituted heteroaromatic ring, R １ and R ４ａ ~R ７ａ R represents a hydrogen atom, a deuterium atom, or a substituent. ２ and R ３ Each of these independently represents a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group. ２ and Z ２ Z ２ and Z３ Z ３ and R ３ , R ４ａ and R ５ａ , R ５ａ and R ６ａ , R ６ａ and R ７ａ , R ７ａ and R １ They may be bonded to each other to form a ring structure. However, R ２ and Z ２ Z ２ and Z ３ Z ３ and R ３ At least one pair of these elements are joined together to form a ring structure.

[0066] As a third organic compound, a compound represented by the following general formula (F8) can also be mentioned. General formula (F8)

[0067] In the general formula (F8), Z １ represents a furan ring formed by the condensation of substituted or unsubstituted benzene rings, a thiophene ring formed by the condensation of substituted or unsubstituted benzene rings, or an N-substituted pyrrole ring formed by the condensation of substituted or unsubstituted benzene rings, Z ３ R represents a substituted or unsubstituted aromatic hydrocarbon ring, or a substituted or unsubstituted heteroaromatic ring. １ and R ８ ~R １４ Each of these independently represents a hydrogen atom, a deuterium atom, or a substituent, R ３ Z represents a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group. １ and R １ , R ８ and R ９ , R ９ and R １０ , R １０ and R １１ , R １１ and R １２ , R １２ and R １３ , R １３ and R １４ , R １４ and Z ３ Z ３ and R ３They may be joined together to form a ring structure.

[0068] As a third organic compound, a compound represented by the following general formula (F9) can also be mentioned. General formula (F9)

[0069] In the general formula (F9), Z １ and Z ４ Each of these independently represents a furan ring formed by the condensation of a substituted or unsubstituted benzene ring, a thiophene ring formed by the condensation of a substituted or unsubstituted benzene ring, or an N-substituted pyrrole ring formed by the condensation of a substituted or unsubstituted benzene ring, Z ３ R represents a substituted or unsubstituted aromatic hydrocarbon ring, or a substituted or unsubstituted heteroaromatic ring. １ and R １５ ~R １７ Each of these independently represents a hydrogen atom, a deuterium atom, or a substituent, R ３ Z represents a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group. １ and R １ Z ４ and R １５ , R １５ and R １６ , R １６ and R １７ , R １７ and Z ３ Z ３ and R ３ They may be joined together to form a ring structure.

[0070] As a third organic compound, the compound represented by the following general formula (F10) can also be mentioned. General formula (F10)

[0071] In the general formula (F10), Z １ and Z ５ Each of these independently represents a furan ring formed by the condensation of a substituted or unsubstituted benzene ring, a thiophene ring formed by the condensation of a substituted or unsubstituted benzene ring, or an N-substituted pyrrole ring formed by the condensation of a substituted or unsubstituted benzene ring, Z ３ R represents a substituted or unsubstituted aromatic hydrocarbon ring, or a substituted or unsubstituted heteroaromatic ring. １R represents a hydrogen atom, a deuterium atom, or a substituent. ２ and R ３ Each of these independently represents a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group. １ and R １ , R ２ and Z ５ Z ５ and Z ３ Z ３ and R ３ They may be bonded to each other to form a ring structure. However, R ２ and Z ２ Z ２ and Z ３ Z ３ and R ３ At least one pair of these elements are joined together to form a ring structure.

[0072] As a third organic compound, the compound represented by the following general formula (F11) can also be mentioned. General formula (F11)

[0073] In the general formula (F11), Z １ represents a furan ring formed by the condensation of substituted or unsubstituted benzene rings, a thiophene ring formed by the condensation of substituted or unsubstituted benzene rings, or an N-substituted pyrrole ring formed by the condensation of substituted or unsubstituted benzene rings, Z ２ R represents a substituted or unsubstituted aromatic hydrocarbon ring, or a substituted or unsubstituted heteroaromatic ring. １ and R ２１ ~R ２７ Each of these independently represents a hydrogen atom, a deuterium atom, or a substituent, R ２ R represents a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group. １ and Z １ , R ２ and Z ２ Z ２ and R ２１ , R ２１ and R ２２ , R ２２ and R ２３ , R ２３ and R ２４ , R ２４ and R ２５ , R２５ and R ２６ , R ２６ and R ２７ They may be joined together to form a ring structure.

[0074] As a third organic compound, the compound represented by the following general formula (F12) can also be mentioned. General formula (F12)

[0075] In the general formula (F12), Z １ and Z ６ Each of these independently represents a furan ring formed by the condensation of a substituted or unsubstituted benzene ring, a thiophene ring formed by the condensation of a substituted or unsubstituted benzene ring, or an N-substituted pyrrole ring formed by the condensation of a substituted or unsubstituted benzene ring, Z ２ R represents a substituted or unsubstituted aromatic hydrocarbon ring, or a substituted or unsubstituted heteroaromatic ring. １ and R ２８ ~R ３０ Each of these independently represents a hydrogen atom, a deuterium atom, or a substituent, R ２ R represents a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group. １ and Z １ , R ２ and Z ２ Z ２ and R ２８ , R ２８ and R ２９ , R ２９ and R ３０ , R ３０ and Z ６ They may be joined together to form a ring structure.

[0076] As a third organic compound, the compound represented by the following general formula (F13) can also be mentioned. General formula (F13)

[0077] In the general formula (F13), Z １ and Z ７ Each of these independently represents a furan ring formed by the condensation of a substituted or unsubstituted benzene ring, a thiophene ring formed by the condensation of a substituted or unsubstituted benzene ring, or an N-substituted pyrrole ring formed by the condensation of a substituted or unsubstituted benzene ring, Z ２R represents a substituted or unsubstituted aromatic hydrocarbon ring, or a substituted or unsubstituted heteroaromatic ring. １ R represents a hydrogen atom, a deuterium atom, or a substituent. ２ and R ３ Each of these independently represents a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group. １ and Z １ , R ２ and Z ２ Z ２ and Z ７ Z ７ and R ３ They may be bonded to each other to form a ring structure. However, R ２ and Z ２ Z ２ and Z ７ Z ７ and R ３ At least one pair of these elements are joined together to form a ring structure.

[0078] As a third organic compound, the compound represented by the following general formula (F14) can also be mentioned. General formula (F14)

[0079] In the general formula (F14), Z １ R represents a furan ring formed by the condensation of a substituted or unsubstituted benzene ring, a thiophene ring formed by the condensation of a substituted or unsubstituted benzene ring, or an N-substituted pyrrole ring formed by the condensation of a substituted or unsubstituted benzene ring. １ and R ３１ ~R ４４ Each of these independently represents a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group. １ and Z １ , R ３１ and R ３２ , R ３２ and R ３３ , R ３３ and R ３４ , R ３４ and R ３５ , R ３５ and R ３６ , R ３６ and R ３７ , R ３７ and R ３８ , R ３８and R ３９ , R ３９ and R ４０ , R ４０ and R ４１ , R ４１ and R ４２ , R ４２ and R ４３ , R ４３ and R ４４ They may be joined together to form a ring structure.

[0080] As a third organic compound, the compound represented by the following general formula (F15) can also be mentioned. General formula (F15)

[0081] In the general formula (F15), Z １ and Z ８ Each of these independently represents a furan ring formed by the condensation of a substituted or unsubstituted benzene ring, a thiophene ring formed by the condensation of a substituted or unsubstituted benzene ring, or an N-substituted pyrrole ring formed by the condensation of a substituted or unsubstituted benzene ring, R １ and R ５１ ~R ６０ Each of these independently represents a hydrogen atom, a deuterium atom, or a substituent. １ and Z １ , R ５１ and R ５２ , R ５２ and R ５３ , R ５３ and R ５４ , R ５４ and R ５５ , R ５５ and R ５６ , R ５６ and R ５７ , R ５７ and R ５８ , R ５８ and R ５９ , R ５９ and R ６０ , R ６０ and Z ８ They may be joined together to form a ring structure.

[0082] As a third organic compound, the compound represented by the following general formula (F16) can also be mentioned. General formula (F16)

[0083] In the general formula (F16), Z １ Z ８ and Z ９ Each of these independently represents a furan ring formed by the condensation of a substituted or unsubstituted benzene ring, a thiophene ring formed by the condensation of a substituted or unsubstituted benzene ring, or an N-substituted pyrrole ring formed by the condensation of a substituted or unsubstituted benzene ring, R １ and R ６１ ~R ６６ Each of these independently represents a hydrogen atom, a deuterium atom, or a substituent. １ and Z １ Z ９ and R ６１ , R ６１ and R ６２ , R ６２ and R ６３ , R ６３ and R ６４ , R ６４ and R ６５ , R ６５ and R ６６ , R ６６ and Z ８ They may be joined together to form a ring structure.

[0084] As a third organic compound, the compound represented by the following general formula (F17) can also be mentioned. General formula (F17)

[0085] In the general formula (F17), Z １ Z ９ and Z １０ Each of these independently represents a furan ring formed by the condensation of a substituted or unsubstituted benzene ring, a thiophene ring formed by the condensation of a substituted or unsubstituted benzene ring, or an N-substituted pyrrole ring formed by the condensation of a substituted or unsubstituted benzene ring, R １ and R ６７ ~R ６９ Each of these independently represents a hydrogen atom, a deuterium atom, or a substituent, R ７０ R represents a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group. １ and Z １ Z ９ and R ６７ , R ６７ and R ６８ , R ６８ and R６９ , R ６９ and Z １０ Z １０ and R ７０ They may be joined together to form a ring structure.

[0086] As a third organic compound, the compound represented by the following general formula (F18) can also be mentioned. General formula (F18)

[0087] (In the general formula (F18), Z １ Z １１ and Z １２ Each of these independently represents a furan ring formed by the condensation of a substituted or unsubstituted benzene ring, a thiophene ring formed by the condensation of a substituted or unsubstituted benzene ring, or an N-substituted pyrrole ring formed by the condensation of a substituted or unsubstituted benzene ring, R １ and R ７２ ~R ７４ Each of these independently represents a hydrogen atom, a deuterium atom, or a substituent, R ７１ R represents a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group. １ and Z １ , R ７１ and Z １１ Z １１ and R ７２ , R ７２ and R ７３ , R ７３ and Z ７４ , R ７４ and Z １２ They may be joined together to form a ring structure.

[0088] As a third organic compound, the compound represented by the following general formula (F19) can also be mentioned. General formula (F19)

[0089] In the general formula (F19), Z １ and Z １１ Each of these independently represents a furan ring formed by the condensation of a substituted or unsubstituted benzene ring, a thiophene ring formed by the condensation of a substituted or unsubstituted benzene ring, or an N-substituted pyrrole ring formed by the condensation of a substituted or unsubstituted benzene ring, R １ and R ７６ ~R ８２Each of these independently represents a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group, R ７５ R represents a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group. １ and Z １ , R ７５ and Z １１ Z １１ and R ７６ , R ７６ and R ７７ , R ７７ and R ７８ , R ７８ and R ７９ , R ７９ and R ８０ , R ８０ and R ８１ , R ８１ and R ８２ They may be joined together to form a ring structure.

[0090] As a third organic compound, the compound represented by the following general formula (F20) can also be mentioned. General formula (F20)

[0091] In the general formula (F20), X ５ R represents an oxygen atom, a sulfur atom, or a nitrogen atom to which a substituted or unsubstituted aryl group or a substituted or unsubstituted heteroaryl group is bonded. １０１ ~R １３０ Each of these independently represents a hydrogen atom, a deuterium atom, or a substituent, R １０１ and R １０２ , R １０２ and R １０３ , R １０３ and R １０４ , R １０４ and R １０５ , R １０５ and R １０６ , R １０６ and R １０７ , R １０７ and R １０８ , R １０８ and R １０９ , R １０９ and R １１０ , R １１０ and R １１１ , R １１１ and R １１２ , R１１２ and R １１３ , R １１３ and R １１４ , R １１４ and R １１５ , R １１５ and R １１６ , R １１６ and R １１７ , R １１７ and R １１８ , R １１８ and R １１９ , R １１９ and R １２０ , R １２０ and R １２１ , R １２１ and R １２２ , R １２２ and R １２３ , R １２３ and R １２４ , R １２４ and R １２５ , R １２５ and R １２６ , R １２６ and R １２７ , R １２７ and R １２８ , R １２８ and R １２９ , R １２９ and R １３０ , R １３０ and R １０１ may be bonded to each other to form a cyclic structure.

[0092] As the third organic compound, compounds represented by the following general formula (F21) can also be mentioned. General formula (F21)

[0093] In the general formula (F21), R １ and R ２ each independently represent a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group, and Z １ and Z ２ each independently represent a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted heteroaromatic ring, and R ３ to R ９ each independently represent a hydrogen atom, a deuterium atom, or a substituent, provided that R １ , R ２ , Z １and Z ２ , at least one of which contains a substituted or unsubstituted benzofuran ring, a substituted or unsubstituted benzothiophene ring, or a substituted or unsubstituted indole ring. R １ and Z １ , Z １ and R ３ , R ３ and R ４ , R ４ and R ５ , R ５ and Z ２ , Z ２ and R ２ , R ２ and R ６ , R ６ and R ７ , R ７ and R ８ , R ８ and R ９ , R ９ and R １ may be bonded to each other to form a cyclic structure. Among the carbon atoms constituting the benzene ring skeleton of said benzofuran ring, said benzothiophene ring and said indole ring, a substitutable carbon atom may be substituted with a nitrogen atom. C-R in General Formula (F21) ３ , C-R ４ , C-R ５ , C-R ６ , C-R ７ , C-R ８ , C-R ９ may be substituted with N.

[0094] In one aspect of the present invention, R １ and R ２ are each independently a substituted or unsubstituted alkyl group, a substituted or unsubstituted phenyl group, or a group containing one or more ring structures selected from the group consisting of a substituted or unsubstituted benzofuran ring, a substituted or unsubstituted benzothiophene ring and a substituted or unsubstituted indole ring. In one aspect of the present invention, Z １ and Z ２However, each is independently a substituted or unsubstituted uncondensed benzene ring, a furan ring formed by the condensation of a substituted or unsubstituted benzene ring, a thiophene ring formed by the condensation of a substituted or unsubstituted benzene ring, a pyrrole ring formed by the condensation of a substituted or unsubstituted benzene ring, a benzene ring formed by the condensation of a substituted or unsubstituted benzofuran ring, a benzene ring formed by the condensation of a substituted or unsubstituted benzothiophene ring, or a benzene ring formed by the condensation of a substituted or unsubstituted indole ring. In one embodiment of the present invention, R １ and Z １ These are bonded together to form a ring structure. In one aspect of the present invention, R １ and Z １ These elements are bonded to each other, forming a pyrrole ring.

[0095] As a third organic compound, the compound represented by the following general formula (F22) can also be mentioned. General formula (F22)

[0096] In the general formula (F22), X １ and X ２ In this case, one atom is a nitrogen atom, and the other is a boron atom. １ ~R ２６ A １ A ２ Each of these independently represents a hydrogen atom, a deuterium atom, or a substituent. １ and R ２ , R ２ and R ３ , R ３ and R ４ , R ４ and R ５ , R ５ and R ６ , R ６ and R ７ , R ７ and R ８ , R ８ and R ９ , R ９ and R １０ , R １０ and R １１ , R １１ and R １２ , R １３ and R １４ , R １４ and R １５ , R １５ and R１６ , R １６ and R １７ , R １７ and R １８ , R １８ and R １９ , R １９ and R ２０ , R ２０ and R ２１ , R ２１ and R ２２ , R ２２ and R ２３ , R ２３ and R ２４ , R ２４ and R ２５ , R ２５ and R ２６ They may be joined to each other to form a ring structure. However, X １ When R is a nitrogen atom, １７ and R １８ They bond to each other to form a single bond and create a pyrrole ring, X ２ When R is a nitrogen atom, ２１ and R ２２ They bond to each other to form a single bond and create a pyrrole ring. However, X １ is a nitrogen atom, R ７ and R ８ and R ２１ and R ２２ The nitrogen atoms bond to form a six-membered ring, R １７ and R １８ When R is bonded to each other to form a single bond, １ ~R ６ At least one of them is a substituted or unsubstituted aryl group, or R １ and R ２ , R ２ and R ３ , R ３ and R ４ , R ４ and R ５ , R ５ and R ６ One of these is bonded to another to form an aromatic hydrocarbon ring or a heteroaromatic ring. For a detailed description, preferred range and specific examples of the compound represented by general formula (F22), refer to

[0010] to

[0119] of WO2022 / 270354A1, which is incorporated herein by reference as part of this specification.

[0097] As a third organic compound, the compound represented by the following general formula (F23) can also be mentioned. General formula (F23)

[0098] In the general formula (F23), R １ ~R ２２ Each of these independently represents a hydrogen atom, a deuterium atom, or a substituent. １ and R ２ , R ２ and R ３ , R ３ and R ４ , R ４ and R ５ , R ５ and R ６ , R ６ and R ７ , R ７ and R, R and R ８ , R ８ and R ９ , R ９ and R １０ , R １０ and R １１ , R １２ and R １３ , R １３ and R １４ , R １４ and R １５ , R １５ and R １６ , R １６ and R １７ , R １７ and R １８ , R １８ and R, R and R １９ , R １９ and R ２０ , R ２０ and R ２１ , R ２１ and R ２２ These may be joined together to form a ring structure. １ and X ２Each of these independently represents O, S, or NR. R represents a hydrogen atom, a deuterium atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. Compounds included in this general formula include the compounds represented by the general formula described in

[0022] of WO2022 / 085714A1, which is incorporated herein by reference, the compounds described in

[0040] to

[0043] and

[0221] , and BBCz-R(5) and BBCz-Y-II(6) of J. Am. Chem. Soc. 2020, 142, 46, 19468-19472, which is incorporated herein by reference.

[0099] As a third organic compound, the compound represented by the following general formula (F24) can also be mentioned. General formula (F24)

[0100] In the general formula (F24), R １ ~R １７ Each of these independently represents a hydrogen atom, a deuterium atom, or a substituent. １ and R ２ , R ２ and R ３ , R ３ and R ４ , R ５ and R ６ , R ６ and R ７ , R ７ and R ８ , R ８ and R ９ , R ９ and R １０ , R １１ and R １２ , R １２ and R １３ , R １３ and R １４ , R １４ and R １５ , R １５ and R １６ , R １６ and R １７ , R １７ and R １These may be bonded to each other to form a cyclic structure. Examples of compounds included in this general formula are BBCz-SB(2), BBCz-G(3), and BBCz-Y(4) of J. Am. Chem. Soc. 2020, 142, 46, 19468-19472, which are cited herein as part of this specification.

[0101] As a third organic compound, the compound represented by the following general formula (F25) can also be mentioned. General formula (F25)

[0102] In the general formula (F25), R １ ~R ２０ Each of these independently represents a hydrogen atom, a deuterium atom, or a substituent. １ and R ２ , R ２ and R ３ , R ３ and R ４ , R ５ and R ６ , R ６ and R ７ , R ７ and R ８ , R ８ and R ９ , R ９ and R １０ , R １１ and R １２ , R １２ and R １３ , R １３ and R １４ , R １４ and R １５ , R １５ and R １６ , R １７ and R １８ , R １８ and R １９ , R １９ and R ２０ These may be bonded to each other to form a cyclic structure. Examples of compounds included in this general formula include BBCz-DB(1) of J. Am. Chem. Soc. 2020, 142, 46, 19468-19472, which are cited herein as part of this specification.

[0103] As a third organic compound, the compound represented by the following general formula (F26) can also be mentioned. General formula (F26)

[0104] In the general formula (F26), X １ and X ２ Each of these independently represents either O or S. １ and Y ２ Each is independently a single bond, O, S, or C(R) ａ ) (Caution ｂ ) represents R １ ~R ２２ , R ａ , R ｂ Each of these independently represents a hydrogen atom, a deuterium atom, or a substituent, but R １ ~R ２２ At least one of them is a substituent. １ and R ２ , R ２ and R ３ , R ３ and R ４ , R ５ and R ６ , R ６ and R ７ , R ７ and Y １ , Y １ and R ８ , R ８ and R ９ , R ９ and R １０ , R １０ and R １１ , R １２ and R １３ , R １３ and R １４ , R １４ and R １５ , R １６ and R １７ , R １７ and R １８ , R １８ and Y ２ , Y ２ and R １９ , R １９ and R ２０ , R ２０ and R ２１ , R ２１ and R ２２ They may be bonded to each other to form a ring structure.２１ and R １ , R ４ and R ５ , R １０ and R １２ , R １５ and R １６ They are not bonded to each other to form a ring structure. C-R in general formula (F26) １ , C-R ２ , C-R ３ , C-R ４ , C-R ５ , C-R ６ , C-R ７ , C-R ８ , C-R ９ , C-R １０ , C-R １１ , C-R １２ , C-R １３ , C-R １４ , C-R １５ , C-R １６ , C-R １７ , C-R １８ , C-R １９ , C-R ２０ , C-R ２１ , C-R ２２ It may be replaced with N.

[0105] The following compounds are specific examples of compounds represented by the general formula (F26).

[0106] Compounds containing the BODIPY (4,4-difluoro-4-bora-3a,4a-diaza-s-indacene) structure can also be cited as third organic compounds. For example, a compound represented by the following general formula (F27) can be used. General formula (F27)

[0107] In the general formula (F27), R １ ~R ９ Each of these is independently a hydrogen atom, a deuterium atom, or a substituent. １ ~R ７ At least one of these is preferably a group represented by the following general formula (F28), R ８ and R ９It is preferably a halogen atom. General formula (F28)

[0108] In the general formula (F28), R １１ ~R １５ Each of the symbols represents a hydrogen atom, a deuterium atom, or a substituent, and the asterisk (*) represents a bond site.

[0109] The following are specific examples of compounds that can be used as third organic compounds. In the following structural formulas, t-Bu represents a tert-butyl group. As derivatives of the example compounds below, compounds in which at least one hydrogen atom is substituted with a deuterium atom, alkyl group, aryl group, heteroaryl group, or diarylamino group can also be listed.

[0110] (Definition of Chemical Structure) In this specification, "alkyl group" may be linear, branched, or cyclic. Furthermore, two or more of the linear, cyclic, and branched portions may be mixed. The number of carbon atoms in an alkyl group can be, for example, 1 or more, 2 or more, or 4 or more. Also, the number of carbon atoms can be 30 or less, 20 or less, 10 or less, 6 or less, or 4 or less. Specific examples of alkyl groups include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, n-pentyl group, isopentyl group, n-hexyl group, isohexyl group, 2-ethylhexyl group, n-heptyl group, isoheptyl group, n-octyl group, isooctyl group, n-nonyl group, isononyl group, n-decanyl group, isodecanyl group, cyclopentyl group, cyclohexyl group, and cycloheptyl group. In this specification, "alkoxy group" may be linear, branched, or cyclic. Furthermore, two or more of the linear, cyclic, and branched portions may be mixed. The number of carbon atoms in the alkoxy group can be, for example, 1 or more, 2 or more, or 4 or more. Also, the number of carbon atoms can be 30 or less, 20 or less, 10 or less, 6 or less, or 4 or less. Specific examples of alkoxy groups include those having a structure in which the alkyl groups listed above as specific examples of "alkyl groups" are bonded to oxygen. For example, alkoxy groups having a structure in which a methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, or tert-butyl group is bonded to oxygen are, respectively, a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, an isobutoxy group, and a tert-butoxy group. In this specification, the "aryl group" may consist of a monocyclic aromatic ring, a fused ring formed by the fusion of two or more aromatic rings, or a linked ring formed by the linkage of two or more aromatic rings. When two or more aromatic rings are linked, they may be linked in a linear manner or in a branched manner. The number of carbon atoms in the aromatic ring constituting the aryl group is preferably 6 to 22, more preferably 6 to 18, even more preferably 6 to 14, and even more preferably 6 to 10.Specific examples of aryl groups include phenyl, naphthalenyl, and biphenyl groups. In this specification, a "heteroaryl group" may consist of a monocycle or a fused ring formed by the fusion of one or more heterocycles with an aromatic ring or heterocycles. The heterocycle constituting the heteroaryl group preferably has 3 to 40 carbon atoms, more preferably 5 to 22, even more preferably 5 to 18, even more preferably 5 to 14, and particularly preferably 5 to 10 carbon atoms. Examples of heteroatoms constituting the heterocycle include nitrogen, oxygen, and sulfur atoms. Specific examples of heterocycles include pyridine, pyridazine, pyrimidine, triazole, and benzotriazole rings.

[0111] In this specification, "Group A" means deuterium atoms, hydroxyl groups, halogen atoms (e.g., fluorine atoms, chlorine atoms, bromine atoms, iodine atoms), alkyl groups (e.g., C1-C40), alkoxy groups (e.g., C1-C40), alkylthio groups (e.g., C1-C40), aryl groups (e.g., C6-C30), aryloxy groups (e.g., C6-C30), arylthio groups (e.g., C6-C30), heteroaryl groups (e.g., ring skeleton constituent atoms numbering 5-30), heteroaryloxy groups (e.g., This group consists of alkyl groups (e.g., ring skeleton with 5 to 30 constituent atoms), heteroarylthio groups (e.g., ring skeleton with 5 to 30 constituent atoms), acyl groups (e.g., 1 to 40 carbon atoms), alkenyl groups (e.g., 1 to 40 carbon atoms), alkynyl groups (e.g., 1 to 40 carbon atoms), alkoxycarbonyl groups (e.g., 1 to 40 carbon atoms), heteroaryloxycarbonyl groups (e.g., 1 to 40 carbon atoms), silyl groups (e.g., trialkylsilyl groups with 1 to 40 carbon atoms), and nitro groups. The alkyl groups, alkoxy groups, alkylthio groups, aryl groups, aryloxy groups, arylthio groups, heteroaryl groups, heteroaryloxy groups, heteroarylthio groups, acyl groups, alkenyl groups, alkynyl groups, alkoxycarbonyl groups, aryloxycarbonyl groups, heteroaryloxycarbonyl groups, silyl groups, and nitro groups referred to here may be substituted with substituents having a structure in which one or more of the deuterium atoms constituting group A and any of the substituents listed above are bonded. In this specification, "Group B" refers to the group consisting of a deuterium atom, an alkyl group (e.g., having 1 to 40 carbon atoms), an alkoxy group (e.g., having 1 to 40 carbon atoms), an aryl group (e.g., having 6 to 30 carbon atoms), an aryloxy group (e.g., having 5 to 30 atoms in the ring skeleton), an heteroaryl group (e.g., having 5 to 30 atoms in the ring skeleton), and a diarylaminoamino group (e.g., having 0 to 20 carbon atoms). The alkyl group, alkoxy group, aryl group, aryloxy group, heteroaryl group, heteroaryloxy group, and diarylaminoamino group referred to herein may be substituted with substituents having a structure in which one or more of the deuterium atoms constituting Group B and any of the substituents listed above are bonded.In this specification, "Group C" refers to the group consisting of a deuterium atom, alkyl groups (e.g., 1 to 20 carbon atoms), aryl groups (e.g., 6 to 22 carbon atoms), heteroaryl groups (e.g., 5 to 20 atoms in the ring skeleton), and diarylamino groups (e.g., 12 to 20 carbon atoms). The alkyl groups, aryl groups, heteroaryl groups, and diarylamino groups referred to here may be substituted with substituents having a structure in which one or more of the substituents listed above are bonded to the deuterium atom constituting Group C. In this specification, "Group D" refers to the group consisting of a deuterium atom, alkyl groups (e.g., 1 to 20 carbon atoms), aryl groups (e.g., 6 to 22 carbon atoms), and heteroaryl groups (e.g., 5 to 20 atoms in the ring skeleton). The alkyl groups, aryl groups, and heteroaryl groups referred to here may be substituted with substituents having a structure in which one or more of the substituents listed above are bonded to the deuterium atom constituting Group D. In this specification, "Group E" refers to the group consisting of a deuterium atom, alkyl groups (e.g., 1 to 20 carbon atoms), and aryl groups (e.g., 6 to 22 carbon atoms). The alkyl and aryl groups referred to herein may be substituted with substituents having a structure in which one or more of the deuterium atoms constituting group E and any of the substituents described above are bonded. When "substituted or unsubstituted" or "may be substituted" is described herein, the deuterium atoms or substituents to be substituted may be selected from, for example, group A, group B, group C, group D, group E, or from any of the groups A to E.

[0112] (Content of the first, second, and third organic compounds in the light-emitting layer) The content of the first, second, and third organic compounds in the light-emitting layer of the organic electroluminescent element of the present invention preferably satisfies the following condition (c): Condition (c) Conc(1) > Conc(2) > Conc(3) Conc(1) represents the concentration of the first organic compound in the light-emitting layer, Conc(2) represents the concentration of the second organic compound in the light-emitting layer, and Conc(3) represents the concentration of the third organic compound in the light-emitting layer. In this application, weight percent is used as the unit.

[0113] The organic electroluminescent element of the present invention preferably has a Conc(1) content of 30% by weight or more, which can be in the range of 50% by weight or more, or 65% by weight or more, or 99% by weight or less, or 85% by weight or less, or 75% by weight or less. The organic electroluminescent element of the present invention preferably has a Conc(2) content of 10% by weight or more, which can be in the range of 20% by weight or more, or 30% by weight or more, or 45% by weight or less, or 40% by weight or less, or 35% by weight or less.

[0114] In the organic electroluminescent element of the present invention, Conc(3) is preferably 5% by weight or less, and more preferably 3% by weight or less. Conc(3) can be in the range of 1% by weight or less, or 0.5% by weight or less, or in the range of 0.01% by weight or more, or 0.1% by weight or more, or 0.3% by weight or more. Furthermore, it is preferable to satisfy the following condition (d): Condition (d) Conc(2) / Conc(3) > 5 Conc(2) / Conc(3) can be in the range of 10 or more, or 30 or more, or 50 or more, or in the range of 500 or less, or 300 or less, or 100 or less.

[0115] The following describes each component of the organic electroluminescent element and each layer other than the light-emitting layer.

[0116] Substrate: In some embodiments, the organic electroluminescent element of the present invention is held by a substrate, which is not particularly limited and may be any material commonly used in organic electroluminescent elements, such as glass, transparent plastic, quartz, and silicon.

[0117] Anode: In some embodiments, the anode of an organic electroluminescent apparatus is made from a metal, alloy, conductive compound, or a combination thereof. In some embodiments, the metal, alloy, or conductive compound has a high work function (4 eV or more). In some embodiments, the metal is Au. In some embodiments, the conductive transparent material is CuI, indium tin oxide (ITO), SnO ２ and selected from ZnO. In some embodiments, IDIXO(In ２ O ３ An amorphous material capable of forming a transparent conductive film, such as -ZnO, is used. In some embodiments, the anode is a thin film. In some embodiments, the thin film is produced by vapor deposition or sputtering. In some embodiments, the film is patterned by a photolithography method. In some embodiments, if the pattern does not need to be highly accurate (e.g., about 100 μm or more), the pattern may be formed using a mask with a shape suitable for vapor deposition or sputtering onto the electrode material. In some embodiments, when a coating material such as an organic conductive compound can be applied, a wet film formation method such as a printing method or a coating method is used. In some embodiments, when synchrotron radiation passes through the anode, the anode has a transmittance of more than 10%, and the anode has a sheet resistance of several hundred ohms or less per unit area. In some embodiments, the thickness of the anode is 10 to 1,000 nm. In some embodiments, the thickness of the anode is 10 to 200 nm. In some embodiments, the thickness of the anode varies depending on the material used.

[0118] Cathode: In some embodiments, the cathode is made of an electrode material such as a metal with a low work function (4 eV or less) (referred to as an electron-injection metal), an alloy, a conductive compound or a combination thereof. In some embodiments, the electrode material is sodium, sodium-potassium alloy, magnesium, lithium, magnesium-copper mixture, magnesium-silver mixture, magnesium-aluminum mixture, magnesium-indium mixture, aluminum-aluminum oxide (Al ２ O ３ ) mixtures, indium, lithium-aluminum mixtures and rare earth elements are selected. In some embodiments, a mixture of an electron-injection metal and a second metal which is a stable metal having a higher work function than the electron-injection metal is used. In some embodiments, the mixture is a magnesium-silver mixture, a magnesium-aluminum mixture, a magnesium-indium mixture, an aluminum-aluminum oxide (Al ２ O ３ ) are selected from a mixture, a lithium-aluminum mixture, and aluminum. In some embodiments, the mixture improves electron injection properties and resistance to oxidation. In some embodiments, the cathode is manufactured by forming the electrode material as a thin film by deposition or sputtering. In some embodiments, the cathode has a sheet resistance of several hundred ohms or less per unit area. In some embodiments, the thickness of the cathode is 10 nm to 5 μm. In some embodiments, the thickness of the cathode is 50 to 200 nm. In some embodiments, either the anode or cathode of the organic electroluminescent element is transparent or translucent in order to transmit synchrotron radiation. In some embodiments, a transparent or translucent electroluminescent element improves light radiance. In some embodiments, a transparent or translucent cathode is formed by forming the cathode with respect to the anode from the conductive transparent material described above. In some embodiments, the element includes an anode and a cathode, both of which are transparent or translucent.

[0119] Injection layer: The injection layer is a layer between the electrode and the organic layer. In some embodiments, the injection layer reduces the driving voltage and enhances the light radiance. In some embodiments, the injection layer includes a hole injection layer and an electron injection layer. The injection layer can be located between the anode and the light-emitting layer or hole transport layer, and between the cathode and the light-emitting layer or electron transport layer. In some embodiments, an injection layer is present. In some embodiments, an injection layer is absent. The following are examples of preferred compounds that can be used as hole injection materials.

[0120]

[0121] Next, we will list some examples of preferred compounds that can be used as electron injection materials.

[0122] Barrier Layer: A barrier layer is a layer that can prevent charges (electrons or holes) and / or excitons present in the light-emitting layer from diffusing to the outside of the light-emitting layer. In some embodiments, an electron barrier layer exists between the light-emitting layer and the hole transport layer, preventing electrons from passing through the light-emitting layer to the hole transport layer. In some embodiments, a hole barrier layer exists between the light-emitting layer and the electron transport layer, preventing holes from passing through the light-emitting layer to the electron transport layer. In some embodiments, a barrier layer prevents excitons from diffusing to the outside of the light-emitting layer. In some embodiments, the electron barrier layer and the hole barrier layer constitute an exciton barrier layer. As used herein, the terms “electron barrier layer” or “exciton barrier layer” include layers that have both the functions of an electron barrier layer and an exciton barrier layer.

[0123] Hole barrier layer: The hole barrier layer functions as an electron transport layer. In some embodiments, the hole barrier layer prevents holes from reaching the electron transport layer during electron transport. In some embodiments, the hole barrier layer increases the probability of electron-hole recombination in the light-emitting layer. The material used for the hole barrier layer may be the same material described above for the electron transport layer. The following are examples of preferred compounds that can be used for the hole barrier layer.

[0124]

[0125] Electron barrier layer: The electron barrier layer transports holes. In some embodiments, during hole transport, the electron barrier layer prevents electrons from reaching the hole transport layer. In some embodiments, the electron barrier layer increases the probability of electron-hole recombination in the light-emitting layer. The material used for the electron barrier layer may be the same material described above for the hole transport layer. Specific examples of preferred compounds that can be used as electron barrier materials are listed below.

[0126]

[0127] Exciton barrier layer: The exciton barrier layer prevents excitons generated through the recombination of holes and electrons in the light-emitting layer from diffusing to the charge transport layer. In some embodiments, the exciton barrier layer enables effective confinement of excitons in the light-emitting layer. In some embodiments, the optical emission efficiency of the device is improved. In some embodiments, the exciton barrier layer is located on either the anode side or the cathode side and adjacent to the light-emitting layers on both sides. In some embodiments, when the exciton barrier layer is located on the anode side, it may be located between the hole transport layer and the light-emitting layer and adjacent to the light-emitting layer. In some embodiments, when the exciton barrier layer is located on the cathode side, it may be located between the light-emitting layer and the cathode and adjacent to the light-emitting layer. In some embodiments, a hole injection layer, electron barrier layer, or similar layer is located between the anode and the exciton barrier layer adjacent to the light-emitting layer on the anode side. In some embodiments, a hole injection layer, electron barrier layer, hole barrier layer, or similar layer is located between the cathode and the exciton barrier layer adjacent to the light-emitting layer on the cathode side. In some embodiments, the exciton barrier layer includes an excitation singlet energy and an excitation triplet energy, at least one of which is higher than the excitation singlet energy and excitation triplet energy of the light-emitting material, respectively.

[0128] Hole transport layer: The hole transport layer comprises a hole transport material. In some embodiments, the hole transport layer is a single layer. In some embodiments, the hole transport layer has multiple layers. In some embodiments, the hole transport material has one of the properties of hole injection or transport properties and electron barrier properties. In some embodiments, the hole transport material is an organic material. In some embodiments, the hole transport material is an inorganic material. Examples of known hole transport materials that can be used in the present invention include, but are not limited to, triazole derivatives, oxadiazole derivatives, imidazole derivatives, carbazole derivatives, indrocarbazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, allylamine derivatives, aminosubstituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, aniline copolymers and conductive polymer oligomers (especially thiophene oligomers), or combinations thereof. In some embodiments, the hole transport material is selected from porphyrin compounds, aromatic tertiary amine compounds, and styrylamine compounds. In some embodiments, the hole transport material is an aromatic tertiary amine compound. Specific examples of preferred compounds that can be used as hole transport materials are listed below.

[0129]

[0130] Electron transport layer: The electron transport layer comprises an electron transport material. In some embodiments, the electron transport layer is a single layer. In some embodiments, the electron transport layer has multiple layers. In some embodiments, the electron transport material only needs to have the function of transporting electrons injected from the cathode to the light-emitting layer. In some embodiments, the electron transport material also functions as a hole barrier material. Examples of electron transport layers that can be used in the present invention include, but are not limited to, nitro-substituted fluorene derivatives, diphenylquinone derivatives, thiopyrandioxide derivatives, carbodiimides, fluorenylidene methane derivatives, anthraquinodimethane, anthrone derivatives, oxadiazole derivatives, azole derivatives, azine derivatives or combinations thereof, or polymers thereof. In some embodiments, the electron transport material is a thiadiazole derivative or a quinoxaline derivative. In some embodiments, the electron transport material is a polymer material. Specific examples of preferred compounds that can be used as electron transport materials are listed below.

[0131]

[0132] Furthermore, examples of preferred compounds that can be added to each organic layer are given. For example, they can be added as stabilizing materials.

[0133]

[0134] While specific examples of preferred materials that can be used in organic electroluminescent elements have been provided, the materials that can be used in the present invention are not limited to the following exemplary compounds. Furthermore, even compounds exemplified as materials with specific functions can be repurposed as materials with other functions.

[0135] Devices: In some embodiments, the light-emitting layer is incorporated into a device. For example, devices include, but are not limited to, OLED bulbs, OLED lamps, television displays, computer monitors, mobile phones, and tablets. In some embodiments, the electronic device includes an OLED having at least one organic layer comprising an anode, a cathode, and a light-emitting layer between the anode and the cathode. In some embodiments, the components described herein may be incorporated into a variety of photosensitive or photoactivated devices, such as OLEDs or optoelectronic devices. In some embodiments, the components may be useful for facilitating charge transfer or energy transfer within the device and / or as hole transport materials. Examples of such devices include organic light-emitting diodes (OLEDs), organic integrated circuits (OICs), organic field-effect transistors (O-FETs), organic thin-film transistors (O-TFTs), organic light-emitting transistors (O-LETs), organic solar cells (O-SCs), organic optical detectors, organic photoreceptors, organic field-quench devices (O-FQDs), light-emitting fuel cells (LECs), or organic laser diodes (O-lasers).

[0136] Bulb or Lamp: In some embodiments, the electronic device includes an OLED comprising an anode, a cathode, and at least one organic layer comprising a light-emitting layer between the anode and the cathode. In some embodiments, the device includes OLEDs of different colors. In some embodiments, the device includes an array comprising a combination of OLEDs. In some embodiments, the combination of OLEDs is a combination of three colors (e.g., RGB). In some embodiments, the combination of OLEDs is a combination of colors other than red, green, or blue (e.g., orange and yellow-green). In some embodiments, the combination of OLEDs is a combination of two, four, or more colors. In some embodiments, the device is an OLED light comprising: a circuit board having a first surface with a mounting surface and a second surface opposite thereto, defining at least one opening; at least one OLED on the mounting surface having a light-emitting configuration comprising an anode, a cathode, and at least one organic layer including a light-emitting layer between the anode and the cathode; a housing for the circuit board; and at least one connector located at the end of the housing, wherein the housing and the connector define a package suitable for mounting to a lighting fixture. In some embodiments, the OLED light has a plurality of OLEDs mounted on the circuit board such that light is emitted in a plurality of directions. In some embodiments, some of the light emitted in the first direction is polarized and emitted in a second direction. In some embodiments, a reflector is used to polarize the light emitted in the first direction.

[0137] Displays or Screens: In some embodiments, the light-emitting layer of the present invention can be used in screens or displays. In some embodiments, the compounds according to the present invention are deposited onto a substrate using processes such as vacuum evaporation, deposition, vapor deposition, or chemical vapor deposition (CVD), but are not limited. In some embodiments, the substrate is a photoplate structure useful in two-sided etching, providing pixels with unique aspect ratios. The screen (also called a mask) is used in the manufacturing process of an OLED display. The design of the corresponding artwork pattern allows for the arrangement of very steep, narrow tie bars between pixels in the vertical direction, and large, wide oblique apertures in the horizontal direction. This enables the fine pattern configuration of pixels required for high-resolution displays while optimizing chemical vapor deposition onto the TFT backplane. Internal patterning of the pixels allows for the configuration of three-dimensional pixel apertures with various aspect ratios in the horizontal and vertical directions. Furthermore, the use of imaged "stripes" or halftone circles within a pixel area protects etching in a particular area until these specific patterns are undercut and removed from the substrate. At that time, all pixel areas are processed at a similar etching rate, but the depth varies depending on the halftone pattern. By changing the size and spacing of the halftone pattern, etching with varying degrees of protection within the pixels becomes possible, enabling localized, deep etching necessary to form steep vertical bevels. A preferred material for the deposition mask is Invar. Invar is a metal alloy that is cold-rolled into long, thin sheets at a steel mill. Invar cannot be electrodeposited onto a spin mandrel as a nickel mask. A suitable and low-cost method for forming aperture regions within the deposition mask is by wet chemical etching. In some embodiments, the screen or display pattern is a pixel matrix on a substrate. In some embodiments, the screen or display pattern is fabricated using lithography (e.g., photolithography and e-beam lithography).In some embodiments, the screen or display pattern is processed using wet chemical etching. In further embodiments, the screen or display pattern is processed using plasma etching.

[0138] Device manufacturing method: OLED displays are generally manufactured by forming a large mother panel and then cutting the mother panel into cell panels. Typically, each cell panel on the mother panel is formed by forming a thin-film transistor (TFT) having an active layer and source / drain electrodes on a base substrate, coating the TFT with a planarization film, sequentially forming pixel electrodes, an emissive layer, a counter electrode, and an encapsulation layer over time, and then cutting it from the mother panel.

[0139] In another aspect of the present invention, a method for manufacturing an organic light-emitting diode (OLED) display is provided, the method comprising the steps of: forming a barrier layer on a base substrate of a mother panel; forming a plurality of display units in cell panel units on the barrier layer; forming an encapsulation layer on each of the display units of the cell panel; and coating an organic film on the interface portions between the cell panels. In some embodiments, the barrier layer is an inorganic film formed of, for example, SiNx, and the edges of the barrier layer are covered with an organic film formed of polyimide or acrylic. In some embodiments, the organic film assists in the soft cutting of the mother panel in cell panel units. In some embodiments, the thin-film transistor (TFT) layer has a light-emitting layer, a gate electrode, and source / drain electrodes. Each of the plurality of display units may have a thin-film transistor (TFT) layer, a planarization film formed on the TFT layer, and a light-emitting unit formed on the planarization film, wherein the organic film coated on the interface portions is formed of the same material as the planarization film and is formed simultaneously with the formation of the planarization film. In some embodiments, the light-emitting unit is connected to the TFT layer by a passivation layer, a planarization film between them, and an encapsulation layer that covers and protects the light-emitting unit. In some embodiments of the manufacturing method, the organic film is not connected to the display unit or the encapsulation layer.

[0140] Each of the organic film and the planarization film may contain either polyimide or acrylic. In some embodiments, the barrier layer may be an inorganic film. In some embodiments, the base substrate may be formed of polyimide. The method may further include the steps of attaching a carrier substrate made of glass material to another surface of the base substrate before forming a barrier layer on one surface of the base substrate made of polyimide, and separating the carrier substrate from the base substrate before cutting along the interface. In some embodiments, the OLED display is a flexible display. In some embodiments, the passivation layer is an organic film placed on the TFT layer for coating the TFT layer. In some embodiments, the planarization film is an organic film formed on the passivation layer. In some embodiments, the planarization film, as well as the organic film formed at the edges of the barrier layer, is made of polyimide or acrylic. In some embodiments, the planarization film and the organic film are formed simultaneously during the manufacture of the OLED display. In some embodiments, the organic film may be formed at the edge of the barrier layer, so that a portion of the organic film is in direct contact with the base substrate, and the remaining portion of the organic film is in contact with the barrier layer while surrounding the edge of the barrier layer.

[0141] In some embodiments, the light-emitting layer includes a pixel electrode, a counter electrode, and an organic light-emitting layer disposed between the pixel electrode and the counter electrode. In some embodiments, the pixel electrode is connected to the source / drain electrodes of the TFT layer. In some embodiments, when a voltage is applied to the pixel electrode through the TFT layer, an appropriate voltage is formed between the pixel electrode and the counter electrode, causing the organic light-emitting layer to emit light, thereby forming an image. Hereinafter, an image forming unit having a TFT layer and a light-emitting unit will be referred to as a display unit. In some embodiments, the encapsulation layer covering the display unit and preventing the penetration of external moisture may be formed as a thin-film encapsulation structure in which organic films and inorganic films are alternately laminated. In some embodiments, the encapsulation layer has a thin-film encapsulation structure in which a plurality of thin films are laminated. In some embodiments, the organic film applied to the interface portion is spaced apart from each of the plurality of display units. In some embodiments, the organic film is formed such that a portion of the organic film is in direct contact with the base substrate, while the remaining portion of the organic film surrounds the edge of the barrier layer while in contact with the barrier layer.

[0142] In one embodiment, the OLED display is flexible and uses a flexible base substrate made of polyimide. In some embodiments, the base substrate is formed on a carrier substrate made of glass material, which is then separated. In some embodiments, a barrier layer is formed on the surface of the base substrate opposite the carrier substrate. In one embodiment, the barrier layer is patterned according to the size of each cell panel. For example, the base substrate is formed on all surfaces of the mother panel, while the barrier layer is formed according to the size of each cell panel, thereby creating grooves in the interface portions between the barrier layers of the cell panels. Each cell panel can be cut along the grooves.

[0143] In some embodiments, the manufacturing method further includes a step of cutting along the interface portion, where a groove is formed in the barrier layer, and at least a portion of the organic film is formed in the groove, and the groove does not penetrate the base substrate. In some embodiments, a TFT layer is formed for each cell panel, and a passivation layer, which is an inorganic film, and a planarization film, which is an organic film, are placed on the TFT layer and cover the TFT layer. For example, while a planarization film made of polyimide or acrylic is formed, the groove in the interface portion is covered with an organic film made of polyimide or acrylic, for example. This prevents cracking by allowing the organic film to absorb the impact generated when each cell panel is cut along the groove at the interface portion. That is, if all barrier layers are completely exposed without an organic film, when each cell panel is cut along the groove at the interface portion, the impact generated is transmitted to the barrier layer, thereby increasing the risk of cracking. However, in one embodiment, the groove in the interface portion between barrier layers may be covered with an organic film to absorb the impact that would otherwise be transmitted to the barrier layer, so that each cell panel is cut softly and cracking in the barrier layer is prevented. In one embodiment, the organic film and the planarizing film covering the grooves of the interface portion are arranged with a gap between them. For example, if the organic film and the planarizing film are connected to each other as a single layer, there is a risk that external moisture may penetrate the display unit through the remaining parts of the planarizing film and organic film. Therefore, the organic film and the planarizing film are arranged with a gap between them so that the organic film is spaced away from the display unit.

[0144] In some embodiments, the display unit is formed by forming a light-emitting unit, and an encapsulation layer is placed on the display unit to cover it. This separates the carrier substrate supporting the base substrate from the base substrate after the mother panel is completely manufactured. In some embodiments, when a laser beam is radiated onto the carrier substrate, the carrier substrate is separated from the base substrate due to the difference in thermal expansion coefficients between the carrier substrate and the base substrate. In some embodiments, the mother panel is cut in cell panel units. In some embodiments, the mother panel is cut along the interface portions between the cell panels using a cutter. In some embodiments, the grooves of the interface portions along which the mother panel is cut are covered with an organic film so that the organic film absorbs shock during cutting. In some embodiments, cracking of the barrier layer can be prevented during cutting. In some embodiments, the method reduces the defect rate of the product and stabilizes its quality. Another embodiment is an OLED display having a barrier layer formed on a base substrate, a display unit formed on the barrier layer, an encapsulation layer formed on the display unit, and an organic film coated on the edges of the barrier layer.

[0145] The features of the present invention will be described in more detail below with reference to examples. The materials, processing content, processing procedures, etc. shown below can be modified as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be interpreted as being limited by the specific examples shown below. The luminescence performance was evaluated using a source meter (Keithley Corporation: 2400 series), a semiconductor parameter analyzer (Agilent Technologies: E5273A), an optical power meter measuring device (Newport Corporation: 1930C), an optical spectrometer (Ocean Optics Corporation: USB2000), a spectroradiometer (Topcon Corporation: SR-3), and a streak camera (Hamamatsu Photonics K.K.: C4334). The orientation value (S value) was measured using a molecular orientation characteristic measuring device (Hamamatsu Photonics K.K.: C14234-01). In this example, the compounds used as the first organic compound, the second organic compound, and the third organic compound are shown below.

[0146]

[0147] (Synthesis Example 1) Synthesis of intermediate a of compound 1

[0148] A mixture of 1,3,5-phenyltriboronic acid tris(pinacol) ester (5.36 g, 11.7 mmol), 1-bromocarbazole (9.56 g, 38.8 mmol), tetrakis(triphenylphosphine)palladium (0) (1.26 g, 1.09 mmol), potassium carbonate (15.4 g, 111 mmol), 1,4-dioxane (90 mL), and deionized water (30 mL) was stirred at 110°C for 15 hours. After the mixture cooled to room temperature, the organic phase and aqueous phase were separated. The aqueous phase was extracted with ethyl acetate, and the combined organic phase was washed with saturated brine. The mixture was dried over anhydrous magnesium sulfate, filtered, and the resulting filtrate was concentrated. The crude product was purified by flash column chromatography (dichloromethane:hexane = 1:2) to obtain 5.51 g (9.60 mmol, yield 82%) of pale yellow solid intermediate a. 1H NMR (400 MHz, CDCl3): d 8.45 (s, 3H), 8.18-8.13 (m, 9H), 7.63 (dd, J = 7.4, 1.0 Hz, 3H), 7.43-7.40 (m, 9H), 7.28-7.24 (m, 3H). APCI-MS: Calculated value 573.22 (C 42 H 27 N3), Observed value 574.38 ([M+H] + ).

[0149] Synthesis of intermediate b

[0150] A mixture of 1,3,5-trifluorobenzene (4.02 g, 30.4 mmol) and tetrahydrofuran (THF, 150 mL) was cooled to -85°C, and lithium diisopropylamide (LDA, 1.07 M THF / hexane solution, 30 mL, 32.5 mmol) was added and the mixture was stirred for 1 hour. Zinc chloride (approximately 1 M THF solution, 38 mL, 38.0 mmol) was added to the mixture and stirred at -85°C for 30 minutes, then stirred at room temperature for 1 hour. Palladium acetate (0.282 g, 1.25 mmol), tri-tert-butylphosphonium tetrafluoroborate (0.731 g, 2.51 mmol), 2-chloro-4,6-di(phenyl-d ５ 6.96 g, 25.0 mmol of )-1,3,5-triazine was added and the mixture was stirred at 75°C for 15 hours. After the mixture cooled to room temperature, deionized water was added, and the precipitated solid was removed by Celite filtration. The obtained filtrate was separated into an organic phase and an aqueous phase. The aqueous phase was extracted with ethyl acetate, and the combined organic phase was washed with saturated brine. The mixture was dried over anhydrous magnesium sulfate, filtered, and the obtained filtrate was concentrated. The crude product was purified by flash column chromatography (dichloromethane:hexane = 1:5) to obtain 8.67 g (23.2 mmol, yield 93%) of intermediate b as a white solid. 1 H NMR (400 MHz, CDCl3): d 6.89-6.82 (m, 2H). APCI-MS: Calculated value 373.16 (C 21 H2D 10 F3N3), Observed value 374.27 ([M+H] + ).

[0151] Synthesis of Compound 1

[0152] A mixture of intermediate a (2.05 g, 3.57 mmol), intermediate b (1.12 g, 3.00 mmol), potassium carbonate (2.07 g, 15.0 mmol), and 1,3-dimethyl-2-imidazolidinone (DMI, 60 mL) was stirred at 230°C for 1 hour. After cooling to room temperature, saturated ammonium chloride aqueous solution was added to reprecipitation. The obtained solid was filtered off and washed with deionized water, methanol, and hexane in that order. The crude product was purified by flash column chromatography (toluene:hexane = 2:3) to obtain 1.07 g (1.20 mmol, yield 40%) of compound 1 as a pale yellow solid. 1 H NMR (400 MHz, DMSO-d6): d 8.26 (t, J = 6.8 Hz, 2H), 8.05 (d, J = 8.0 Hz, 2H), 7.94-7.92 (m, 3H), 7.72 (s, 2H), 7.52-7.27 (m, 13H), 7.15 (d, J = 1.4 Hz, 2H), 7.09 (ddd, J = 8.0, 5.6, 2.4 Hz, 2H). APCI-MS: Calculated value 886.36 (C 63 H 27 D 10 N6), Observed value 887.63 ([M+H] + ).

[0153] (Synthesis Example 2) Synthesis of intermediate d of compound 4

[0154] A mixture of compound c (9.70 g, 30.0 mmol), 3-chloro-2-fluorophenylboronic acid (11.4 g, 64.8 mmol), tetrakis(triphenylphosphine)palladium (0) (1.74 g, 1.50 mmol), potassium carbonate (12.5 g, 89.7 mmol), tetrahydrofuran (THF, 210 mL), and deionized water (70 mL) was stirred at 75°C for 18 hours. After the mixture cooled to room temperature, the precipitated solid was filtered off and washed with deionized water, methanol, ethyl acetate, and hexane in that order. After drying, the solid was dissolved in hot toluene and filtered by silica gel. The filtrate was concentrated, hexane was added, and the resulting solid was filtered off. Heat drying under reduced pressure yielded 10.6 g (20.6 mmol, yield 69%) of a pale yellow solid intermediate d. 1 H NMR (400 MHz, CDCl3): d 8.36 (ddd, J = 8.0, 6.4, 1.6 Hz, 2H), 7.69 (ddd, J = 8.0, 6.4, 1.6 Hz, 2H), 7.34 (td, J = 7.9, 1.1 Hz, 2H). APCI-MS spectral analysis: theoretical value 511.11 (C 27 H7D8Cl2F2N4), Observed value 511.38 [(M+H) + ].

[0155] Synthesis of intermediate e

[0156] A mixture of intermediate d (3.06 g, 5.98 mmol), bis(pinacolato)diborone (6.98 g, 24.3 mmol), tris(dibenzylideneacetone)dipalladium (0) (1.11 g, 1.21 mmol), tricyclohexylphosphine (339 mg, 1.20 mmol), potassium acetate (4.26 g, 43.4 mmol), and dioxane (60 mL) was stirred at 100°C for 18 hours. After cooling to room temperature, ethyl acetate was added and the mixture was filtered through silica gel. The obtained filtrate was concentrated, dichloromethane was added, and the mixture was filtered again through silica gel. The obtained filtrate was concentrated, hexane was added, and the mixture was reprecipitated. After filtering off the solid, the mixture was heated and dried under reduced pressure to obtain 3.16 g (4.55 mmol, yield 76%) of intermediate e, a pale yellow solid. 1H NMR (400 MHz, CDCl3): d 8.52 (td, J = 7.6, 1.8 Hz, 2H), 7.99 (ddd, J = 7.2, 5.2, 2.0 Hz, 2H), 7.37 (t, J = 7.6 Hz, 2H), 1.42 (s, 24H). APCI-MS spectral analysis: Theoretical value 695.36 (C 39 H 31 D8B2F2N4O4), Observed value 695.76 [(M+H) + ].

[0157] Synthesis of intermediate f

[0158] A mixture of intermediate e (3.16 g, 4.55 mmol), 2-chloro-4,6-bis[(2,3,4,5,6-d5)phenyl]-1,3,5-triazine (2.67 g, 9.61 mmol), tetrakis(triphenylphosphine)palladium (0) (267 mg, 0.231 mmol), potassium carbonate (1.87 g, 13.6 mmol), THF (66 mL), and deionized water (22 mL) was stirred at 75°C for 18 hours. After the mixture cooled to room temperature, the precipitated solid was filtered off and washed with ethyl acetate, deionized water, and methanol in that order, and then dried. The obtained solid was washed with hot toluene, and then with toluene and hexane in that order. The obtained solid was heated and dried under reduced pressure to obtain 3.79 g (4.09 mmol, 90% yield) of pale green intermediate f. APCI-MS spectral analysis: Theoretical value 925.48 (C 57 H7D 28 F2N 10 ), Observed value 924.74 [(M+H) + ].

[0159] Synthesis of Compound 4

[0160] Intermediate f (3.61 g, 3.90 mmol), carbazole-1,2,3,4,5,6,7,8-d ８A mixture of (2.08 g, 11.8 mmol), potassium carbonate (2.19 g, 15.8 mmol), and N-methyl-2-pyrrolidone (NMP, 78 mL) was stirred at 180°C for 2 hours. After cooling to room temperature, deionized water was added, and the precipitated solid was washed with deionized water, methanol, and hexane in that order. The obtained solid was dissolved in hot toluene and filtered by silica gel. The filtrate was concentrated, the precipitated solid was washed with toluene, and then heated and dried under reduced pressure to obtain 3.51 g (2.84 mmol, yield 73%) of compound 4 as a white solid. 1 H NMR (400 MHz, DMSO-d6): d 8.53 (dd, J = 7.8, 1.4 Hz, 2H), 7.86 (t, J = 7.8 Hz, 2H), 7.69 (dd, J = 7.9, 1.5 Hz, 2H). APCI-MS spectral analysis: theoretical value 1235.71 (C 81 H7D 44 N 12 ), Observed value 1235.87 [(M+H) + ].

[0161] (Synthesis Example 3) Synthesis of intermediate g of compound 5

[0162] 2-Fluorophenyl-1,3-diboronic acid, pinacol ester (3.48 g, 10 mmol), 9-[4-chloro-6-(phenyl-2,3,4,5,6-d ５ )-1,3,5-triazine-2-yl]-9H-carbazole-1,2,3,4,5,6,7,8-d ８ A mixture of (7.77 g, 21 mmol), tetrakis(triphenylphosphine)palladium (0) (0.578 g, 0.50 mmol), potassium carbonate (9.67 g, 70 mmol), dioxane (75 mL), and deionized water (25 mL) was stirred at 110°C for 16 hours. After the mixture cooled to room temperature, the precipitated solid was washed with deionized water, methanol, ethyl acetate, and hexane in that order. The obtained solid was washed with hot toluene, cooled to room temperature, filtered off, and washed with toluene and hexane in that order to obtain 6.13 g (8.03 mmol, yield 80%) of a pale gray solid intermediate. APCI MS spectral analysis: Theoretical value 762.4 (C48 H3D 26 FN8), Observed value 763.6 [(M+H) + ]

[0163] Synthesis of compound 5

[0164] Intermediate g (3.05 g, 4.00 mmol), carbazole-1,2,3,4,5,6,7,8-d ８ A mixture of (2.80 g, 16.0 mmol), potassium phosphate (2.76 g, 20.0 mmol), and NMP (80 mL) was stirred at 170°C for 1 hour. After cooling the mixture to room temperature, ammonium chloride aqueous solution was added and reprecipitation was performed. The obtained solid was filtered off and washed with deionized water. The crude product was purified by flash column chromatography (toluene) to obtain 2.51 g (1.32 mmol, yield 68%) of compound 5 as a white solid. APCI MS spectral analysis: theoretical value 917.5 (C 60 H3D 34 N9), Observed value 918.7 [(M+H) + ]

[0165] (Spectral Measurement) The emission spectra of the fast-fluorescence component (Prompt) and the slow-fluorescence component (Delay) of compounds 1-3 and comparative compound 1 were measured, and the results of fitting the short-wavelength side of each emission spectrum with a straight line are shown in Figures 2-4. Figure 2 shows the emission spectra of compound 1 and comparative compound 1, Figure 3 shows the emission spectrum of compound 2, and Figure 4 shows the emission spectrum of compound 3. In Figures 2-4, the solid line graphs represent the emission spectra of the fast-fluorescence component (Prompt), and the dotted line graphs represent the emission spectra of the slow-fluorescence component (Delay). The straight line along the short-wavelength side of the peak of each spectrum is the fitting line, and the wavelength indicated by the arrow is the wavelength value (λedge) at the intersection of the fitting line and the horizontal axis. As shown in Figures 2-4, in compounds 1-3, the λedge of the fast-fluorescence component is at a shorter wavelength than the λedge of the slow-fluorescence component, and a short-wavelength shift is observed in the emission spectrum of the fast-fluorescence component, whereas in comparative compound 1, no difference is observed in the emission spectra of the fast-fluorescence component and the slow-fluorescence component. Furthermore, when the emission spectra of the fast and slow fluorescence components were measured for compounds 4 and 5, a similar short-wavelength shift of the fast fluorescence component was observed. The reason why the emission spectra of the fast fluorescence components in compounds 1 to 5 are short-wavelength shifted is that the slow fluorescence component originates from emission from a compound that has undergone reverse intersystem crossing from an excited triplet state to an excited singlet state, whereas the fast fluorescence component originates from emission from a metastable structure in an energy band higher than the lowest excited singlet energy. From this, it was confirmed that compounds 1 to 5 are compounds with metastable structures.

[0166] (Example 1) Fabrication and evaluation of organic electroluminescent elements A glass substrate on which an anode made of indium tin oxide (ITO) with a film thickness of 100 nm was formed was used to deposit each thin film by vacuum deposition at a vacuum of 1 × 10⁻⁶ －６The layers were stacked using Pa. First, HATCN was formed to a thickness of 10 nm on ITO, and then NPD was formed to a thickness of 30 nm on top of it. Next, TrisPCz was formed to a thickness of 10 nm on top of that, and then H1 was formed to a thickness of 5 nm on top of that. Then, H1, compound 1, and F1 were co-deposited from different deposition sources to form a 30 nm thick luminescent layer. The concentration of H1 in the luminescent layer was 70 wt%, the concentration of compound 1 was 29 wt%, and the concentration of F1 was 1 wt%. On top of that, SF3TRZ was formed to a thickness of 10 nm, and then SF3TRZ and Liq were co-deposited from different deposition sources to form a 30 nm thick layer. At this time, the SF3TRZ:Liq (weight ratio) was 7:3. Furthermore, Liq was formed to a thickness of 2 nm, and then aluminum (Al) was deposited to a thickness of 100 nm to form the cathode. Following the above procedure, the organic electroluminescent element (EL element 1) of Example 1 was fabricated.

[0167] Furthermore, organic electroluminescent elements (EL elements 2-5, comparative element 1) were fabricated in the same manner using compounds 2-5 and comparative compound 1 instead of compound 1. However, in the light-emitting layer of the organic electroluminescent elements using compounds 2-5, H2 was used instead of H1.

[0168] When each of the fabricated organic electroluminescent elements was energized, delayed fluorescence was observed in all of them. Furthermore, the amount of light emitted from each element was greatest at F1. Each element was energized at 2 mA / cm². ２ When the external quantum yield (EQE) was measured when driven by the device, all showed high values ​​of 21% or higher. In addition, when the orientation values ​​(S values) of compounds 1 to 5 and comparative compound 1 in the light-emitting layer of each device were measured, all showed good values ​​of less than -0.25. Table 1 below shows the emission peak wavelength (λpeak) and E of the second organic compound used in the light-emitting layer. Ｓ２ (2) E Ｓ１ (2) E Ｔ１ (2) and the CIEy values ​​of the elements are shown together. The values ​​in the "CIEy of element" column are, from top to bottom, the CIEy values ​​of EL element 1, EL element 2, EL element 3, EL element 4, EL element 5, and comparison element 1. Also, Table 2 shows the E of the first organic compound used in the light-emitting layer. Ｓ１ (1) and EＴ１ (1) Emission peak wavelength (λpeak) of the third organic compound, E Ｓ１ (3) and E Ｔ１ (3) is shown in summary. Note that in Table 2, "E Ｓ１ " is E Ｓ１ (1) and E Ｓ１ (3) represents both, and "E Ｔ１ " is E Ｔ１ (1) and E Ｔ１ (3) represents both. Here, the excited state energy and λpeak values ​​of compound 1 and comparative compound 1 were measured on doped films in which each compound was doped with 0.5 wt% of H1, and the excited state energy and λpeak of compounds 2-5 and F1 were measured on doped films in which each compound was doped with 0.5 wt% of H2.

[0169]

[0170]

[0171] The CIEy value of a film formed solely of F1 (F1-only film) is approximately 0.08. As shown in Table 1, the CIEy values ​​of EL elements 1-5 using compounds 1-5 as the second organic compound were smaller than the CIEy value of comparative element 1 using comparative compound 1, and closer to the CIEy value of the F1-only film. From this, it was found that by using a delayed fluorescence material with a metastable structure in an energy band higher than the lowest excitation singlet energy as the second organic compound, emission that greatly reflects the emission color of the third organic compound can be achieved. Ｓ２ (2) - E Ｓ１ (2) When EL elements were fabricated using various different delayed fluorescence materials as the second organic compound, and the CIEy value was measured, E Ｓ２ (2) - E Ｓ１ It was confirmed that when (2) is 0.04 eV or higher, there is a tendency to show a CIEy value particularly close to that of an F1-only film.

[0172]

[0173] The organic electroluminescent element of the present invention exhibits high FRET efficiency between the second and third organic compounds, enabling the emission of light originating from the third organic compound with high purity. Therefore, by using, for example, a third organic compound having an emission peak wavelength in the wavelength range of a desired chromaticity, it is possible to provide an organic electroluminescent element that exhibits a good emission color reflecting that chromaticity. Accordingly, the present invention has high industrial applicability.

Claims

1. An organic electroluminescent device having a light-emitting layer containing a first organic compound, a second organic compound, and a third organic compound, wherein the second organic compound is a delayed fluorescent material having a metastable structure in an energy band higher than the lowest excited singlet energy level, wherein the first organic compound, the second organic compound, and the third organic compound satisfy the following formula (I) and formula (II): Formula (I): E Ｓ１ (1) > E Ｓ２ (2) > E Ｓ１ (2) > E Ｓ１ (3) Formula (II): E Ｔ１ (1) > E Ｔ１ (2) > E Ｔ１ (3) [In formula (I) and formula (II), E Ｓ１ (1) represents the lowest excited singlet energy of the first organic compound, E Ｓ１ (2) represents the lowest excited singlet energy of the second organic compound, E Ｓ２ (2) represents the energy of the metastable structure in the energy band higher than the lowest excited singlet energy level of the second organic compound, E Ｓ１ (3) represents the lowest excited singlet energy of the third organic compound, E Ｔ１ (1) represents the lowest excited triplet energy of the first organic compound, E Ｔ１ (2) represents the lowest excited triplet energy of the second organic compound, E Ｔ１ (3) represents the lowest excited triplet energy of the third organic compound.]] 2. The organic electroluminescent element according to claim 1, wherein the difference in emission peak wavelengths between the second organic compound and the third organic compound is within 20 nm.

3. The organic electroluminescent element according to claim 1, wherein the emission peak wavelength of the third organic compound is 500 nm or less.

4. E of the second organic compound Ｓ２ The organic electroluminescent element according to claim 1, wherein (2) is in the range of 2.85 to 3.05 eV.

5. The organic electroluminescent element according to claim 1, wherein the second organic compound satisfies the following formula (III). Formula (III) E Ｓ２ (2) - E Ｓ１ (2) > 0.04eV 6. The organic electroluminescent element according to claim 1, wherein the second organic compound has a structure in which a donor group is bonded to the ortho position of a benzene ring to which an acceptor group is bonded.

7. The organic electroluminescent element according to claim 1, wherein the second organic compound has a structure in which a substituted or unsubstituted carbazole-9-yl group is bonded to the ortho position of a benzene ring to which a substituted or unsubstituted triazinyl group is bonded.

8. The organic electroluminescent element according to claim 6, wherein another donor group is bonded to the benzene ring, and the ortho donor group and the other donor group are bonded to each other with a substituted or unsubstituted arylene group or a substituted or unsubstituted heteroarylene group as linking groups to form a cyclic structure.

9. The organic electroluminescent element according to claim 8, wherein the shortest number of linked atoms in the cyclic structure is 12 to 14.

10. The organic electroluminescent element according to claim 1, wherein the second organic compound has a C2 symmetric structure.

11. The organic electroluminescent element according to claim 1, wherein the S value of the second organic compound contained in the light-emitting layer is less than -0.2.

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