Composition, use of said composition as light-emitting composition, film, use of said film as light-emitting film, organic electroluminescence element, composition design method and program for carrying out said design method

Abstract

To provide conditions for a TAF type organic light-emitting element having high color purity.SOLUTION: There is provided a composition that contains a first organic compound satisfying the conditions (a) to (d) below, a second organic compound that is a delayed fluorescent material, and a third organic compound that is a fluorescent material. Condition (a): ES1 (1)>ES1 (2)>ES1 (3); condition (b): λEEM (2)<λPAB (3)-10 nm; condition (c): λPEM (3)<λPEM (2); and condition (d): λPEM (3)<480 nm. (In the conditions, ES1 (1) represents the lowest excited singlet energy of the first organic compound, ES1 (2) represents the lowest excited singlet energy of the second organic compound, ES1 (3) represents the lowest excited singlet energy of the third organic compound, λEEM (2) represents a short wavelength-side emission wavelength of the second organic compound, λPAB (3) represents the longest wavelength-side peak top wavelength of light absorption of the third organic compound, λPEM (2) represents a peak top wavelength of an emission of the second organic compound, and λPEM (3) represents a peak top wavelength of an emission of the third organic compound.)SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a composition capable of emitting light by a TAF (TADF-assisted fluorescent) mechanism, use of the composition as a light-emitting composition, an organic electroluminescence device using the composition, a method for designing the composition, and a program for carrying out the design method. [Background technology]

[0002] As an organic light-emitting element using a delayed fluorescent material, a TAF (TADF assisted fluorescence) type organic light-emitting element has been developed in which a delayed fluorescent material is used as an assist dopant in combination with a fluorescent material, which is a light-emitting material. The TAF type organic light-emitting element shows higher luminous efficiency than a normal fluorescent type organic light-emitting element for the following reasons. That is, when electrons and holes recombine in the light-emitting layer of an organic light-emitting device, an excited singlet state and an excited triplet state are generated with a probability of 25%:75% according to the law of spin statistics. Here, in a normal fluorescent material, the excited triplet state emits heat and is deactivated non-radiatively, so only 25% of the excited singlet energy is used for light emission, and there is a theoretical limit to the luminous efficiency. On the other hand, a delayed fluorescent material is an organic compound that causes reverse intersystem crossing from an excited triplet state to an excited singlet state. Therefore, when a delayed fluorescent material and a fluorescent material are combined and used in the light-emitting layer, the excited triplet energy is converted to excited singlet energy in the delayed fluorescent material and transferred to the fluorescent material by Forster transfer, and the fluorescent material that receives the energy also deactivates from the excited singlet state and emits light. Due to this mechanism, in a TAF-type organic light-emitting device, the excited singlet energy generated by direct excitation as well as the excited triplet energy generated by direct excitation are used for fluorescent emission, so that the TAF-type organic light-emitting device shows high luminous efficiency. In recent years, more excellent TAF-type organic light-emitting devices have been proposed by further improving the combination of delayed fluorescent materials and light-emitting materials.

[0003] For example, Patent Document 1 describes that a TAF-type organic light-emitting device using a specific BN polycyclic aromatic compound as a light-emitting material and cyanobenzene substituted with four substituted or unsubstituted carbazol-9-yl groups (however, the four groups are not all the same) as a delayed fluorescent material exhibits high light-emitting efficiency. Non-Patent Document 1 describes that in a TAF-type organic light-emitting device using a combination of general-purpose blue, green, yellow, and red fluorescent materials and a specific delayed fluorescent material, energy transfer from the delayed fluorescent material to the fluorescent material occurs efficiently, and high luminous efficiency is demonstrated. Non-Patent Document 2 describes that in a TAF-type organic light-emitting device that combines a specific yellow fluorescent material with dicyanobenzene substituted with four 3,6-dimethylcarbazol-9-yl groups as a delayed fluorescent material, Förster transfer of excited singlet energy occurs efficiently, improving operational stability. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2020 / 039930 [Non-patent literature]

[0005] [Non-Patent Document 1] Nature Commun. DOI: 10.1038 / ncomms5016 [Non-Patent Document 2] Sci. Rep. DOI: 10.1038 / srep08429 Summary of the Invention [Problem to be solved by the invention]

[0006] As described above, for TAF-type organic light-emitting devices, combinations of delayed fluorescent materials having specific chemical structures and luminescent materials having specific chemical structures have been proposed, and the luminous efficiency and operational stability of devices employing specific combinations of delayed fluorescent materials and luminescent materials have been examined. However, in the research and development of conventional TAF-type organic light-emitting devices, the conditions that serve as indicators for combining delayed fluorescent materials and luminescent materials have not been generalized, and it has been extremely difficult to find a combination that provides luminescence with high efficiency and high color purity from the range of delayed fluorescent materials and luminescent materials that have been proposed.

[0007] Therefore, in order to solve such problems of the conventional technology, the present inventors have carried out studies with the aim of generalizing the conditions to be satisfied by delayed fluorescent materials and light-emitting materials, in particular, in order to provide a TAF-type organic light-emitting device that exhibits high efficiency and high color purity of light emission. [Means for solving the problem]

[0008] As a result of intensive research to solve the above problems, the present inventors have found that a TAF-type organic light-emitting device exhibiting high efficiency and high color purity can be realized by adding a first organic compound having a minimum excited singlet energy higher than that of the delayed fluorescent material and the fluorescent material to the material system, and then specifying the minimum excited singlet energy, absorption spectrum, and emission spectrum conditions of the delayed fluorescent material and the fluorescent material. The present invention has been proposed based on these findings, and specifically has the following configuration.

[0009] [1] A composition comprising a first organic compound, a second organic compound which is a delayed fluorescent material, and a third organic compound which is a fluorescent material, all of which satisfy the following conditions (a) to (d): Condition (a) E S1 (1)> E S1 (2)> E S1 (3) Condition (b) λ E EM (2)< λ P AB (3)-10 nm Condition (c) λ P EM(3)< λ P EM (2) Condition (d) λ P EM (3) < 480 nm (In the above formula, E S1 (1) is the lowest excited singlet energy of the first organic compound, E S1 (2) is the lowest excited singlet energy of the second organic compound, E S1 (3) is the lowest excited singlet energy of the third organic compound, λ E EM (2) is the short wavelength emission wavelength (unit: nm) of the second organic compound, λ P AB (3) is the wavelength (unit: nm) of the peak top on the longest wavelength side of the absorption spectrum of the third organic compound, λ P EM (2) is the wavelength of the peak top of the emission spectrum of the second organic compound, λ P EM (3) represents the wavelength of the peak top of the emission spectrum of the third organic compound. [2] The composition according to [1], which satisfies the following condition (e): Condition (e) FW 0.3M < 40 nm (In the above formula, FW 0.3M represents the spectral width at a relative intensity of 30% of the emission peak of the emission spectrum of the composition. [3] The composition according to [2], which satisfies the following condition (e1): Condition (e1) FW 0.3M < 32 nm [4] The composition according to any one of [1] to [3], which satisfies the following conditions (f) and (g): Condition (f) LUMO(2)≦ LUMO(3) Condition (g) HOMO(2)≦HOMO(3) (In the above formula, LUMO(2) represents the LUMO energy of the second organic compound, LUMO(3) represents the LUMO energy of the third organic compound, HOMO(2) represents the HOMO energy of the second organic compound, and HOMO(3) represents the HOMO energy of the third organic compound.) [5] The composition according to any one of [1] to [4], which satisfies the following condition (h): Condition (h) R 0 (2-3)> 6.5 nm (In the above formula, R 0 (2-3) represents the Förster radius between the second organic compound and the third organic compound. [6] The composition according to any one of [1] to [5], which satisfies the following condition (i): Condition (i) r(2-3)< 3.91nm (In the above formula, r(2-3) represents the intermolecular distance between the second organic compound and the third organic compound.) [7] The composition according to any one of [1] to [6], which satisfies the following condition (j): Condition (j) k FRET (2-3)> 1.5×10 9 s -1 (In the above equation, k FRET (2-3) represents the Förster energy transfer rate constant between the second organic compound and the third organic compound. [8] The composition according to any one of [1] to [4], which satisfies the following conditions (h1), (i1), and (j1): Condition (h1) R 0 (2-3)≧ 7.3 nm Condition (i1) r(2-3)≦3.71nm Condition (j1) k FRET (2-3)≧ 6.1×10 9 s -1 (In the above formula, R 0 (2-3) is the Förster radius between the second organic compound and the third organic compound, r(2-3) is the intermolecular distance between the second organic compound and the third organic compound, k FRET (2-3) represents the Förster energy transfer rate constant between the second organic compound and the third organic compound. [9] The composition according to any one of [1] to [8], wherein the second organic compound has a structure represented by the following general formula (1): [ka] (In general formula (1), D represents a substituted or unsubstituted carbazol-9-yl group, and Ph represents a phenyl group which may be substituted with at least one group selected from the group consisting of an alkyl group, an aryl group, and a group formed by linking these groups.)

[10] The composition according to [9], wherein the organic second compound has a structure represented by the following general formula (1a): [ka] (In the general formula (1a), D 1 represents a substituted or unsubstituted carbazol-9-yl group, and Ph represents a phenyl group which may be substituted with at least one group selected from the group consisting of an alkyl group, an aryl group, and a group formed by linking these groups.

[11] The composition according to any one of the items [1] to [8], wherein the second organic compound has a structure represented by the following general formula (2): [ka] (In the general formula (2), D 1 represents a substituted or unsubstituted carbazol-9-yl group, D 2 D 1 and each of the two Ph's independently represents a phenyl group which may be substituted with at least one group selected from the group consisting of an alkyl group, an aryl group, and a group formed by linking these groups.

[12] The composition according to

[11] , wherein the organic second compound has a structure represented by the following general formula (2a): [ka] (In the general formula (2a), D 1 represents a substituted or unsubstituted carbazol-9-yl group, D2 D 1 and each of the two Ph's independently represents a phenyl group which may be substituted with at least one group selected from the group consisting of an alkyl group, an aryl group, and a group formed by linking these groups.

[13] D, D 1 and D. 2 each independently has a structure represented by any one of D1 to D37 below: [ka] JPEG0007674727000006.jpg230170

[14] Use of the composition according to any one of [1] to

[13] as a light-emitting composition.

[15] A film comprising the light-emitting composition according to any one of [1] to

[13] .

[16] Use of the film according to

[15] as a light-emitting film.

[17] An organic electroluminescence device having an anode, a cathode, and at least one organic layer including an emitting layer between the anode and the cathode, wherein the emitting layer contains the composition according to any one of items [1] to

[13] , and the largest component of light emitted from the device is fluorescence from the third organic compound.

[18] The organic electroluminescence element according to

[17] , which is a top emission type.

[19] A method for designing a composition containing a first organic compound, a second organic compound, and a third organic compound, comprising selecting the first organic compound, the second organic compound which is a delayed fluorescent material, and the third organic compound which is a fluorescent material so as to satisfy the above conditions (a) to (d).

[20] The method for designing a composition described in

[19] , wherein the selection is performed so as to also satisfy the above conditions (f) and (g).

[21] The method for designing a composition according to

[19] or

[20] , wherein the selection is carried out so as to also satisfy the above condition (h). Condition (h) R 0 (2-3)> 6.5 nm (In the above formula, R 0 (2-3) represents the Förster radius between the second organic compound and the third organic compound.

[22] The method for designing a composition according to any one of

[19] to

[21] , wherein the selection is carried out so as to also satisfy the above condition (i).

[23] The method for designing a composition according to any one of

[19] to

[22] , wherein the selection is carried out so as to also satisfy the above condition (j).

[24] The method for designing a composition according to

[19] , wherein the selection is carried out so as to also satisfy the above conditions (h1), (i1) and (j1).

[25] A program for carrying out the composition design method described in any one of

[19] to

[24] . Effect of the Invention

[0010] The composition of the present invention contains three types of organic compounds that satisfy certain conditions, and therefore the TAF mechanism functions to emit light with high efficiency and high color purity, and high color purity is obtained particularly in the wavelength range of less than 480 nm. Therefore, the composition of the present invention is highly useful as a light-emitting composition. By using the composition of the present invention, a TAF-type organic light-emitting device that emits light with high efficiency and high color purity can be easily realized. [Brief description of the drawings]

[0011] [Figure 1] 13 is a flowchart showing an example of a processing procedure of a program. [Diagram 2] These are emission spectra of a thin film of composition 1 consisting of compound H1, compound DF1, and compound F1, a thin film of composition 2 consisting of compound H1, compound DF2, and compound F1, and a thin film of comparative composition 1 consisting of compound H1, compound DF3, and compound F1. [Diagram 3] FIG. 2 is a schematic diagram showing a layered structure of an organic electroluminescence element. [Figure 4]These are emission spectra of EL element 2 using composition 1 in the light-emitting layer, EL element 1 in which the concentration of compound F1 was changed to 0.5% by weight, EL element 3 in which the concentration of compound F1 was changed to 2.0% by weight, and comparative EL element 1 in which compound F1 was not contained in the light-emitting layer. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The present invention will be described in detail below. The following description of the constituent elements may be based on representative embodiments and specific examples, but the present invention is not limited to such embodiments. In this specification, a numerical range expressed using "to" means a range including the numerical values ​​before and after "to" as the lower and upper limits. In addition, the isotope species of hydrogen atoms present in the molecules of the compound used in the present invention are not particularly limited, and for example, all hydrogen atoms in the molecule may be 1 H, or part or all of 2 It may also be H (Deuterium D). In this specification, "excitation light" refers to light that excites an object to cause it to emit light, and light having a wavelength that matches the absorption wavelength of the object can be used. In this specification, the term "host material" refers to a material contained in a mixed film of organic compounds, and is an organic compound having the highest minimum excited singlet energy among the organic compounds constituting the mixed film.

[0013] <Composition> The composition of the present invention contains a first organic compound, a second organic compound which is a delayed fluorescent material, and a third organic compound which is a fluorescent material, all of which satisfy the following conditions (a) to (d). Condition (a) E S1 (1)> E S1 (2)> E S1 (3) Condition (b) λ E EM (2)< λ P AB (3)-10 nm Condition (c) λ P EM (3)< λP EM (2) Condition (d) λ P EM (3) < 480 nm (In the above formula, E S1 (1) is the lowest excited singlet energy of the first organic compound, E S1 (2) is the lowest excited singlet energy of the second organic compound, E S1 (3) is the lowest excited singlet energy of the third organic compound, λ E EM (2) is the short-wavelength emission wavelength of the second organic compound (unit: nm), λ P AB (3) is the wavelength (unit: nm) of the peak top on the longest wavelength side of the absorption spectrum of the third organic compound, λ P EM (2) is the wavelength of the peak top of the emission spectrum of the second organic compound, λ P EM (3) represents the wavelength of the peak top of the emission spectrum of the third organic compound. The "delayed fluorescent material" in the present invention is a material that undergoes reverse intersystem crossing from an excited triplet state to an excited singlet state, and is preferably a thermally activated delayed fluorescent material in which reverse intersystem crossing occurs due to the absorption of thermal energy. A delayed fluorescent material is determined to be a material when both a fluorescence with a short emission lifetime and a fluorescence with a long emission lifetime (delayed fluorescence) are observed when the emission transient decay curves of a thin film (single film) made of the delayed fluorescent material or a mixed film made of the delayed fluorescent material and a host material are observed at 20°C. The "fluorescent material" in the present invention is a light-emitting material that, when the emission of a thin film (single film) made of the fluorescent material or a mixed film made of the fluorescent material and a host material is observed at 20°C, has a higher fluorescence emission intensity than phosphorescence emission intensity. Ordinary fluorescence (fluorescence that is not delayed fluorescence) has an emission lifetime on the order of ns, while phosphorescence usually has an emission lifetime on the order of ms, so fluorescence and phosphorescence can be distinguished by their emission lifetimes. The "fluorescent material" in the present invention may be a fluorescent material that does not emit delayed fluorescence, or may be a fluorescent material that emits delayed fluorescence (delayed fluorescent material). Here, the "fluorescent material that does not emit delayed fluorescence" is a fluorescent material in which only fluorescence with a short emission lifetime is observed at 20°C. λ defined in the present invention P AB (3) "Absorption spectrum", λ E EM (2), λ P EM (2) and λ P EM The measurement temperature for the "emission spectrum" in (3) shall be 20° C. For specific explanations of the "absorption spectrum" and "emission spectrum," please refer to the explanations in the definitions of physical properties below.

[0014] In the present invention, the "lowest excited singlet energy of the first organic compound" (E S1 (1)), "The lowest excited singlet energy of the second organic compound" (E S1 (2)), "The lowest excited singlet energy of the third organic compound" (E S1 (3)) is a method for measuring the fluorescence spectrum of a thin film of each of the first organic compound, the second organic compound, and the third organic compound (a single film of each organic compound) as a measurement sample, and measuring the wavelength λ at the short-wavelength end of the spectrum. E EM The fluorescence spectrum is a graph in which the luminescence intensity detected when a measurement sample is irradiated with excitation light at 20°C is plotted on the vertical axis and the emission wavelength on the horizontal axis. A tangent line is drawn to the rising edge of the fluorescence spectrum on the short wavelength side, and the wavelength (λ) at the intersection point between the tangent line and the horizontal axis (the end of the fluorescence spectrum on the short wavelength side) is calculated. E EM) [nm] is converted to energy value E using the following conversion formula S1 E S1 (1), E S1 (2) or E S1 (3). Conversion formula: E S1 [eV]=1239.85 / λ E EM In the present invention, the "short wavelength emission wavelength (unit: nm) of the second organic compound" (λ E EM (2)) is the wavelength at the end of the spectrum on the short wavelength side of the emission spectrum measured using a thin film made of the second organic compound (a film of the second organic compound alone) as the measurement sample. The emission spectrum is a graph in which the ordinate shows the emission intensity detected when the measurement sample is irradiated with light while the wavelength is continuously changed in the range of 900 to 190 nm, and the abscissa shows the wavelength. A tangent line is drawn to the rising edge of the short wavelength side of the emission spectrum, and the wavelength at the intersection point of the tangent line and the abscissa (the emission spectrum end on the short wavelength side) is defined as the wavelength λ. E EM (2) [nm]. In the present invention, the term "wavelength (unit: nm) of the peak top on the longest wavelength side of the absorption spectrum of the third organic compound" (λ P AB (3)) is a 10-membered tertiary organic compound. -5 The wavelength λ is the maximum absorption wavelength of the absorption peak located on the longest wavelength side in the absorption spectrum measured using a toluene solution as a measurement sample. For example, when there are multiple absorption peaks in the absorption spectrum, the maximum absorption wavelength of the absorption peak located on the longest wavelength side is taken as the wavelength λ P AB (3). In the present invention, the "peak top wavelength of the emission spectrum of the second organic compound" (λ P EM (2)) is the maximum wavelength of the emission peak of the emission spectrum measured using a mixed film of the second organic compound and the host material as a measurement sample. Here, the "host material" is the lowest excited singlet energy E S1(2) is an organic compound having a minimum excited singlet energy higher than that of (1), and the concentration of the second organic compound in the mixed film is 30% by weight. When multiple emission peaks exist in the emission spectrum, the emission maximum wavelength of the emission peak with the greatest intensity is λ P EM (2) is the case. The "peak top wavelength of the emission spectrum of the third organic compound" (λ P EM (3)) is the emission maximum wavelength of the emission peak of the emission spectrum measured using a mixed film of the third organic compound and the host material as a measurement sample. Here, the "host material" is the lowest excited singlet energy E S1 (3) is an organic compound having a minimum excited singlet energy higher than that of (1), and the concentration of the third organic compound in the mixed film is 1% by weight. When multiple emission peaks exist in the emission spectrum, the emission maximum wavelength of the emission peak with the greatest intensity is λ P EM (3). λ P EM Although there is no particular lower limit for (3), it is preferably 430 nm or more.

[0015] By satisfying the conditions (a) to (d), the composition of the present invention exhibits particularly efficient emission of high color purity due to the TAF (TADF-assisted fluorescent) mechanism, and particularly achieves high color purity in the wavelength range of less than 480 nm. The mechanism will be described using an example in which the composition is excited by electric current to emit light. Here, the "TAF mechanism (TADF-assisted fluorescent)" in this specification refers to a phenomenon in which reverse intersystem crossing occurs in the delayed fluorescent material, converting excited triplet energy into excited singlet energy, and the excited singlet energy is transferred to the fluorescent material by Förster transfer and utilized for fluorescent emission. First, when electrons and holes are injected into the composition of the present invention, the electrons and holes are recombined to generate an excited singlet state and an excited triplet state in each organic compound with a generation probability of 25:75. Here, by satisfying condition (a), the excited singlet energy generated in the third organic compound is transferred to the second organic compound and the third organic compound by Förster transfer, and the excited singlet energy generated in the second organic compound and the excited singlet energy received by the second organic compound from the first organic compound are transferred to the third organic compound by Förster transfer. Then, the third organic compound that has received the excited singlet energy emits fluorescence due to radiative deactivation from the excited singlet state. In addition, since the second organic compound is a delayed fluorescent material, the excited triplet state generated in the second organic compound undergoes reverse intersystem crossing to an excited singlet state, and the excited singlet energy is also transferred to the third organic compound by Förster transfer. That is, here, the second organic compound functions as an assist dopant that converts the excited triplet energy into excited singlet energy and supplies it to the third organic compound. Therefore, in this composition, not only the energy of the excited singlet state generated by direct excitation but also the excited triplet energy generated by direct excitation is utilized for the fluorescent emission of the third organic compound, thereby achieving a higher luminous efficiency than a fluorescent composition that does not use a delayed fluorescent material. Here, in the composition of the present invention, the third organic compound satisfies the condition (d), and the second organic compound and the third organic compound satisfy the conditions (a) and (c), so that the fluorescence peak emitted by the third organic compound has a peak top in a wavelength range of less than 480 nm, and the peak width is narrower than the emission peak when the second organic compound emits light. In addition, by satisfying the condition (b), the emission band of the second organic compound overlaps with the longest wavelength side absorption peak of the third organic compound. Therefore, competition in energy transfer, such as the excited singlet energy that should be transferred to the third organic compound by Förster transfer to the second organic compound and radiative deactivation, is avoided, and the emission spectrum shape of the composition is prevented from being broadened due to the influence of the light from the second organic compound. As described above, the composition of the present invention, by satisfying the conditions (a) to (d), emits light with particularly high efficiency and high color purity, and particularly achieves high color purity in the wavelength range of less than 480 nm. In addition, since the conditions (a) to (d) are objective indicators shown by the magnitude relationship of numerical values, it is possible to clearly determine whether the conditions are met. Therefore, by selecting the first organic compound, the second organic compound, and the third organic compound using the conditions (a) to (d) as indicators, it is possible to reliably realize a composition exhibiting the above-mentioned characteristics.

[0016] In addition to the condition (b), the second organic compound and the third organic compound preferably further satisfy the following condition (b1), and more preferably satisfy the following conditions (b2) to (b4). Condition (b1) λ E EM (2)< λ P AB (3)-12 nm Condition (b2) λ E EM (2)< λ P AB (3)-15 nm Condition (b3) λ E EM (2)< λ P AB (3)-18 nm Condition (b4) λ E EM (2)< λ P AB (3)-20 nm

[0017] The composition preferably satisfies the following condition (e), and more preferably satisfies the following condition (e1): A composition that satisfies the following condition has a narrow base of its emission peak and therefore exhibits emission of high color purity. Condition (e) FW 0.3M < 40 nm Condition (e1) FW 0.3M < 32 nm (In the above formula, FW 0.3M represents the spectral width at a relative intensity of 30% for the emission peak of the emission spectrum of the composition.)

[0018] Furthermore, it is preferable that the second organic compound and the third organic compound satisfy the following conditions (f) and (g), which makes it easier for electrons and holes to be injected into the second organic compound than into the third organic compound, thereby allowing the second organic compound to effectively exhibit its assist dopant function. Condition (f) LUMO(2)≦ LUMO(3) Condition (g) HOMO(2)≦HOMO(3) (In the above formula, LUMO(2) represents the LUMO (Lowest Unoccupied Molecular Orbital) energy of the second organic compound, LUMO(3) represents the LUMO energy of the third organic compound, HOMO(2) represents the HOMO (Highest Occupied Molecular Orbital) energy of the second organic compound, and HOMO(3) represents the HOMO energy of the third organic compound.) Here, the LUMO energy is the value obtained by subtracting the band gap from the ionization potential measured for a thin film made of the compound to be measured (a film of the compound to be measured alone) and adding a "-" sign to it, and the HOMO energy is the value obtained by adding a "-" sign to the ionization potential. The band gap is estimated from the wavelength at the end of the absorption spectrum on the long wavelength side. The ionization potential is measured by photoelectron spectroscopy, and for example, a photoelectron spectrometer (AC-3 manufactured by Riken Keiki Co., Ltd.) can be used for the measurement.

[0019] The second organic compound and the third organic compound preferably satisfy the following condition (h), more preferably satisfy the following condition (i), and more preferably satisfy the following condition (j), more preferably satisfy at least two of the following conditions (h), (i), and (j), and even more preferably satisfy all of the following conditions (h), (i), and (j), which facilitates Förster transfer of excited singlet energy from the second organic compound to the third organic compound, thereby enabling the efficiency and color purity of light emission to be further improved. Condition (h) R 0 (2-3)> 6.5 nm (In the above formula, R 0 (2-3) represents the Förster radius between the second organic compound and the third organic compound. Condition (i) r(2-3)< 3.91nm (In the above formula, r(2-3) represents the intermolecular distance between the second organic compound and the third organic compound.) Condition (j) k FRET (2-3)> 1.5×10 9 s -1 (In the above equation, k FRET (2-3) represents the Förster energy transfer rate constant between the second organic compound and the third organic compound.

[0020] Moreover, it is more preferable that the second organic compound and the third organic compound satisfy all of the following conditions (h1), (i1) and (j1). Condition (h1) R 0 (2-3)≧ 7.3 nm Condition (i1) r(2-3)≦3.71nm Condition (j1) k FRET (2-3)≧ 6.1×10 9 s -1 In the above formula, R 0 (2-3), r(2-3) and k FRET For the definition of (2-3), reference may be made to the corresponding definitions of conditions (h), (i) and (j). Here, the "Förster radius between the second and third organic compounds" (R 0 (2-3)) is the value calculated by the following formula.

number

[0021]

number

[0022] The light emitted from the composition of the present invention includes fluorescence from the third organic compound. The light emitted from the composition of the present invention may contain only the fluorescent component from the third organic compound, or may partially contain the light emitting components from the first organic compound and the second organic compound, but the maximum component of the light emitted from the composition is preferably the fluorescence from the third organic compound. The fact that the maximum component of the light emitted from the composition is the fluorescence from the third organic compound can be confirmed by the fact that the area of ​​the emission peak derived from the third organic compound is more than 50% of the area of ​​all emission peaks in the emission spectrum of the composition. The proportion of the fluorescent component derived from the third organic compound in the light emitted from the composition is more preferably more than 60%, more preferably more than 70%, even more preferably more than 80%, and particularly preferably more than 90%.

[0023] Compounds that can be used as the second organic compound, the third organic compound, and the first organic compound will be specifically described below.

[0024] [Second organic compound] An example of a compound that can be used as the second organic compound is a compound represented by the following general formula (1).

[0025] [ka]

[0026] In the general formula (1), D represents a substituted or unsubstituted carbazol-9-yl group. D may be an unsubstituted carbazol-9-yl group or a carbazol-9-yl group in which at least one hydrogen atom is substituted with a substituent (a substituted carbazol-9-yl group). However, all four Ds have the same chemical structure. The number of substituents in the substituted carbazol-9-yl group is not particularly limited and may be any of 1 to 8. The position of the substituent is also not particularly limited, but it is preferable that at least one of the 3rd and 6th positions is a substituent. When the substituted carbazol-9-yl group has two or more substituents, the multiple substituents may be the same or different from each other. Examples of the substituent in the substituted carbazol-9-yl group include an alkyl group, an aryl group, and a heteroaryl group, and these substituents may be further substituted with an alkyl group, an aryl group, or a heteroaryl group. Adjacent substituents in the carbazol-9-yl group may be bonded to each other to form a ring structure. Examples of the cyclic structure formed by bonding the substituents to each other include a benzofuran ring, a benzothiophene ring, and an indole ring, and these cyclic structures may be substituted with an alkyl group or an aryl group. The alkyl group as a substituent of the carbazol-9-yl group may be linear, branched, or cyclic. The number of carbon atoms is preferably 1 to 20, more preferably 1 to 10, and further preferably 1 to 6. Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, and an isopropyl group. The aromatic ring constituting the aryl group may be a single ring, a condensed ring in which two or more aromatic rings are condensed, or a linked ring in which two or more aromatic rings are linked. When two or more aromatic rings are linked, they may be linked in a straight chain or in a branched chain. The number of carbon atoms in the aromatic ring constituting the arylene group is preferably 6 to 40, more preferably 6 to 22, even more preferably 6 to 18, even more preferably 6 to 14, and particularly preferably 6 to 10. Specific examples of the aryl group include a phenyl group, a naphthalenyl group, and a biphenyl group. The heterocyclic ring constituting the heteroaryl group may be a monocyclic ring or a fused ring in which one or more heterocyclic rings are fused with one or more aromatic rings or heterocyclic rings. The number of carbon atoms in the heterocyclic ring constituting the heteroaryl group is preferably 3 to 40, more preferably 5 to 22, even more preferably 5 to 18, even more preferably 5 to 14, and particularly preferably 5 to 12. The heteroatom constituting the heterocyclic ring is preferably at least one of a nitrogen atom, an oxygen atom, and a sulfur atom. Specific examples of the heteroaryl group include a carbazol-9-yl group, a 10H-phenoxazine-10-yl group, a 10H-phenothiazine-10-yl group, and a 9,10-dihydroacridin-10-yl group. The substituted carbazol-9-yl group in D preferably has a structure represented by any one of the following D1 to D37. The wavy lines in the following D1 to D37 represent the substitution positions on the benzene ring.

[0027] [ka] JPEG0007674727000011.jpg231170

[0028] In the general formula (1), Ph represents a phenyl group which may be substituted with at least one group selected from the group consisting of an alkyl group, an aryl group, and a group formed by linking these groups. In the following description, "at least one group selected from the group consisting of an alkyl group, an aryl group, and a group formed by linking these groups" may be referred to as "substituent A". The phenyl group in Ph may be unsubstituted or may be a phenyl group (substituted phenyl group) in which at least one hydrogen atom is substituted with a substituent A. When the phenyl group is substituted with a substituent A, the number of the substituents A is not particularly limited and may be any one of 1 to 5. In addition, the position of the substituent A is not particularly limited and may be any one of 2 to 6 positions. When the phenyl group has two or more substituents A, the multiple substituents A may be the same or different from each other. For the explanation, preferred ranges and specific examples of the alkyl group and aryl group, reference can be made to the explanation, preferred ranges and specific examples of the alkyl group and aryl group exemplified above as the substituent of the carbazol-9-yl group. The group in which an alkyl group and an aryl group are linked may be an arylalkyl group or an alkylaryl group. The number of aryl groups substituted on the alkyl group and the number of alkyl groups substituted on the aryl group may be one or more than one. When an alkyl group is substituted with two or more aryl groups, the multiple aryl groups may be the same or different from each other. When an aryl group is substituted with two or more alkyl groups, the multiple alkyl groups may be the same or different from each other. In addition, the aryl group as a substituent of the alkyl group and the alkyl group as a substituent of the aryl group may be further substituted with one or more alkyl groups and one or more aryl groups. For the explanation and preferred ranges and specific examples of the alkyl group and the aryl group, the explanation and preferred ranges and specific examples of the alkyl group and the aryl group exemplified as the substituent of the carbazol-9-yl group can be referred to. In general formula (1), the substitution positions of the four Ds and Ph on the benzene ring are not particularly limited. For example, the substitution position of Ph may be any of the ortho, meta, and para positions relative to the CN group, but is preferably the para position. Regardless of the position of Ph, the remaining substitutable positions on the benzene ring are the substitution positions of the four Ds.

[0029] The compound used as the second organic compound is preferably a compound represented by the following general formula (1a).

[0030] [ka]

[0031] In the general formula (1a), D 1 represents a substituted or unsubstituted carbazol-9-yl group. 1 have the same chemical structure as each other. Ph represents a phenyl group which may be substituted with at least one group selected from the group consisting of an alkyl group, an aryl group, and a group formed by linking these groups. D 1 For the preferred range and specific examples of the explanation of D in the general formula (1) above, reference may be made to the explanation, preferred range and specific examples thereof, except for the explanation of the substitution position thereof. For the preferred range and specific examples of Ph, reference may be made to the explanation, preferred range and specific examples thereof, except for the explanation of the substitution position thereof.

[0032] An example of a compound that can be used as the second organic compound is a compound represented by the following general formula (2).

[0033] [ka]

[0034] In the general formula (2), D 1 represents a substituted or unsubstituted carbazol-9-yl group, D 2 D1 represents a substituted or unsubstituted carbazol-9-yl group different from 2 have the same chemical structure as each other. D 1 and D. 2 may be an unsubstituted carbazol-9-yl group or a carbazol-9-yl group in which at least one hydrogen atom is substituted with a substituent (a substituted carbazol-9-yl group). For the explanation, preferred range and specific examples of the substituted carbazol-9-yl group, the explanation, preferred range and specific examples of the substituted carbazol-9-yl group in D above can be referred to. However, D in the general formula (2) 2 D 1 D represents a substituted or unsubstituted carbazol-9-yl group different from 1 and a substituted or unsubstituted carbazol-9-yl group represented by D 2 The substituted or unsubstituted carbazol-9-yl group represented by the formula (I) may differ in the presence or absence of a substituent, the number of substituents, the structure of the substituent, and the substitution position. Each of the two Ph independently represents a phenyl group which may be substituted with at least one group selected from the group consisting of an alkyl group, an aryl group, and groups to which these are linked. The two Ph may be the same or different. For the explanation, preferred range, and specific examples of "a phenyl group which may be substituted with at least one group selected from the group consisting of an alkyl group, an aryl group, and groups to which these are linked" represented by Ph, reference may be made to the explanation, preferred range, and specific examples of "a phenyl group which may be substituted with at least one group selected from the group consisting of an alkyl group, an aryl group, and groups to which these are linked" represented by Ph in the above general formula (1). In the general formula (2), D 1 , D 2 The substitution positions of and Ph on the benzene ring are not particularly limited. For example, the substitution positions of the two Ph may be any of the ortho, meta, and para positions relative to the CN group, and in any case, the remaining substitutable positions are D 1 and two D's 2Preferred substitution positions of the two Ph's include the ortho and para positions relative to the CN group. 2 A preferred substitution position of the formula (I) is the meta position relative to the CN group.

[0035] The compound used as the second organic compound is also preferably a compound represented by the following general formula (2a).

[0036] [ka]

[0037] In the general formula (2a), D 1 represents a substituted or unsubstituted carbazol-9-yl group, D 2 D 1 represents a substituted or unsubstituted carbazol-9-yl group different from 2 have the same chemical structure. Each of the two Ph independently represents a phenyl group which may be substituted with at least one group selected from the group consisting of an alkyl group, an aryl group, and a group formed by linking these groups. The two Ph may be the same or different. D 1 , D 2 The explanation of Ph is based on the above general formula (2) D, except for the explanation of the substitution position on the benzene ring. 1 , D 2 , see the explanation in Ph.D.

[0038] Specific examples of compounds that can be used as the second organic compound are given below. However, the second organic compound that can be used in the present invention should not be construed as being limited by these specific examples.

[0039] [ka] JPEG0007674727000016.jpg224168JPEG0007674727000017.jpg135170

[0040] [Third organic compound] The third organic compound is preferably a multiple resonance fluorescent material, and more preferably a multiple resonance delayed fluorescent material. The third organic compound is preferably a compound that exhibits multiple resonance between one or more atoms selected from the group consisting of nitrogen atoms, oxygen atoms, and sulfur atoms and boron atoms. Compounds represented by the general formulas and specific compounds described in paragraphs

[0011] to

[0032] of International Publication No. 2020 / 039930, which are incorporated herein by reference as part of this specification, and compounds represented by the following formulas can be preferably used as the third organic compound.

[0041] [ka]

[0042] [First organic compound] The first organic compound is an organic compound having a higher minimum excited singlet energy than the second organic compound, and can be selected from known host materials, for example. Specific examples of compounds that can be used as the third organic compound are given below, but the third organic compound that can be used in the present invention should not be construed as being limited by these specific examples.

[0043] [ka] JPEG0007674727000020.jpg159164

[0044] [Composition ratio of the first organic compound, the second organic compound, and the third organic compound] In the composition of the present invention, the compounding ratio of the first organic compound, the second organic compound, and the third organic compound is not particularly limited, but it is preferable that the content of the second organic compound is less than the content of the first organic compound and more than the content of the third organic compound, that is, the relationship of "content of the third organic compound < content of the second organic compound < content of the first organic compound" is satisfied. Specifically, the content of the second organic compound in the composition is preferably less than 50% by weight based on the total amount of the first organic compound, the second organic compound, and the third organic compound. Furthermore, the upper limit of the content of the second organic compound is preferably less than 40% by weight based on the total amount of the first organic compound, the second organic compound, and the third organic compound, and can be, for example, less than 30% by weight, less than 20% by weight, or less than 10% by weight. The lower limit is preferably 0.1% by weight or more, and can be, for example, more than 1% by weight, or more than 3% by weight. The content of the third organic compound in the composition may be 0.1% by weight or more, or 1% by weight or more, based on the total amount of the first organic compound, the second organic compound, and the third organic compound, and may be 30% by weight or less, 20% by weight or less, or 10% by weight or less.

[0045] [Other components of the composition] The composition of the present invention may be composed only of the first organic compound, the second organic compound, and the third organic compound, or may contain other components.

[0046] <Use as a luminescent composition> As described above, the composition of the present invention exhibits particularly high efficiency and high color purity light emission, and particularly high color purity is obtained in the wavelength range of less than 480 nm. Therefore, the composition of the present invention can be effectively used as a light-emitting composition. The use mode of the composition of the present invention when used as a light-emitting composition is not particularly limited, and examples thereof include a mode in which the composition is formed into a film and used as a light-emitting film, a mode in which the light-emitting film is used as a light-emitting layer of an organic light-emitting device, and a mode in which the composition is dissolved in a solvent and used as a liquid light-emitting material. For the configuration of the light-emitting film using the composition of the present invention, the descriptions in the columns <Film> and <Light-emitting film> below can be referred to, and for the configuration of the organic light-emitting device using the composition of the present invention in the light-emitting layer, the descriptions in the column <Organic light-emitting device> below can be referred to.

[0047] <Membrane> Next, the membrane of the present invention will be described. The membrane of the present invention is characterized by comprising the composition of the present invention. For an explanation of the composition of the present invention, please refer to the description in the <Composition> section above. As described above, the composition of the present invention exhibits particularly efficient light emission with high color purity, and high color purity is obtained particularly in the wavelength range of less than 480 nm. Therefore, a film containing this composition also exhibits excellent properties reflecting the properties of the composition.

[0048] The membrane of the present invention can be formed as follows. In some embodiments, the film containing the composition of the present invention can be formed by a wet process. In the wet process, a solution containing the composition of the present invention is applied to a surface, and a film is formed after the solvent is removed. Examples of the wet process include, but are not limited to, spin coating, slit coating, inkjet (spray) printing, gravure printing, offset printing, and flexographic printing. In the wet process, a suitable organic solvent capable of dissolving the composition of the present invention is selected and used. In some embodiments, a substituent (e.g., an alkyl group) that increases the solubility in organic solvents can be introduced into the organic compound contained in the composition. In an embodiment, the film containing the composition of the present invention can be formed by a dry process. In an embodiment, the dry process can be a vacuum deposition method, but is not limited thereto. When the vacuum deposition method is adopted, each organic compound constituting the composition may be co-deposited from an individual deposition source, or each organic compound may be co-deposited from a single deposition source in which the organic compounds are mixed. When a single deposition source is used, a mixed powder in which the powders of each organic compound are mixed may be used, or a compression molded body in which the mixed powder is compressed may be used, or a mixture in which each organic compound is heated, melted, and cooled may be used. In an embodiment, a film having a composition ratio corresponding to the composition ratio of the organic compounds contained in the deposition source can be formed by performing co-deposition under conditions in which the deposition rates (weight reduction rates) of the organic compounds contained in a single deposition source are the same or almost the same. If a plurality of organic compounds are mixed in the same composition ratio as the composition ratio of the film to be formed and used as a deposition source, a film having a desired composition ratio can be easily formed. In an embodiment, a temperature at which the organic compounds to be co-deposited have the same weight reduction rate can be specified, and the temperature can be used as the temperature during co-deposition.

[0049] The film of the present invention may be a single layer or a multilayer.When the film of the present invention is a multilayer, each layer may have at least one of the first organic compound, the second organic compound, and the third organic compound different from each other, or may have different composition ratios, or may have different presence or absence of other components. The thickness of the film of the present invention is preferably 10 to 100 nm, more preferably 20 to 60 nm, and further preferably 30 to 50 nm. When the film of the present invention has a multilayer structure, the preferred range of the thickness of each film is the above-mentioned thickness range.

[0050] <Use as a light-emitting film> As described above, the film of the present invention exhibits particularly efficient and high color purity light emission, and particularly high color purity is obtained in the wavelength range of less than 480 nm. Therefore, the film of the present invention can be effectively used as a light-emitting film. For an explanation of the membrane of the present invention, please refer to the description in the <Membrane> section above. The light-emitting film of the present invention can be effectively used as a light-emitting layer of an organic light-emitting device. For the configuration of an organic light-emitting device using the light-emitting film of the present invention as a light-emitting layer, the description in the <Organic Light-Emitting Device> section below can be referred to.

[0051] <Organic light-emitting element> The composition of the present invention contains a first organic compound, a second organic compound, and a third organic compound that satisfy certain conditions, and thus the TAF mechanism operates to exhibit particularly efficient light emission with high color purity, and particularly high color purity is obtained in the wavelength range of less than 480 nm. Therefore, the composition of the present invention can be effectively used as a material for the light-emitting layer of a TAF-type organic light-emitting device, and is particularly suitable as a material for the light-emitting layer of an organic electroluminescence device. Here, the descriptions of the use examples, devices, displays, screens, and the like described in

[0141] to

[0169] and

[0192] to

[0242] of US2020 / 0168814A1 are hereby cited in their entirety as part of this specification, with the material of the "light-emitting layer" being replaced with the "composition of the present invention," to describe the present invention.

[0052] A preferred embodiment of the organic electroluminescent device (organic electroluminescent device of the present invention) is an organic electroluminescent device having an anode, a cathode, and at least one organic layer including an emitting layer between the anode and the cathode, wherein the emitting layer contains the composition of the present invention, and the largest component of the light emitted from the device is fluorescence from a third organic compound. For an explanation of the composition of the present invention, please refer to the description in the <Composition> section above. The fact that the maximum component of the emission from the element is the fluorescence from the third organic compound can be confirmed by the fact that the area of ​​the emission peak derived from the third organic compound is more than 50% of the total emission peak area in the emission spectrum of the organic electroluminescence element. The proportion of the fluorescent component derived from the third organic compound in the emission from the element is more preferably more than 60%, even more preferably more than 70%, even more preferably more than 80%, and particularly preferably more than 90%. The wavelength of the emission peak derived from the third organic compound (the wavelength of the emission peak of the organic electroluminescence element) is not limited, but in a preferred embodiment it is in the blue emission region (400 nm to 490 nm), and in a more preferred embodiment it is 420 nm to 480 nm.

[0053] In the organic electroluminescence device of the present invention, the organic layer includes at least a light-emitting layer, and may be composed of only a light-emitting layer, or may have one or more organic layers in addition to the light-emitting layer. Examples of such other organic layers include a hole transport layer, a hole injection layer, an electron blocking layer, a hole blocking layer, an electron injection layer, an electron transport layer, and an exciton blocking layer. The hole transport layer may be a hole injection transport layer having a hole injection function, and the electron transport layer may be an electron injection transport layer having an electron injection function.

[0054] The organic electroluminescence element of the present invention may be a bottom emission type that emits light from the substrate side, or a top emission type that emits light from the opposite side to the substrate, but is preferably a top emission type. In a bottom emission type organic electroluminescence element, the electrode (one electrode) on the substrate side of a pair of electrodes is composed of a transparent electrode, and in a top emission type organic electroluminescence element, the electrode (one electrode) on the opposite side to the substrate of a pair of electrodes is composed of a transparent electrode. The other electrode may be any of a transparent electrode, a semitransparent electrode, and a reflective electrode, but when it is a transparent electrode or a semitransparent electrode, a reflective layer formed of a metal element or an alloy may be provided adjacent to the electrode.

[0055] The following are specific examples of preferred materials that can be used in organic electroluminescence devices. However, the materials that can be used in the present invention are not limited to the following exemplary compounds. In addition, even if a compound is exemplified as a material having a specific function, it can also be used as a material having other functions.

[0056] In some embodiments of the present invention, the following compounds can be preferably used as electron blocking materials. [ka]

[0057] In some embodiments of the present invention, the following compounds can be preferably used as hole blocking materials. [ka]

[0058] Preferred examples of compounds that can be used as the hole injection material for the organic electroluminescence device are given below. [ka]

[0059] Next, preferred examples of compounds that can be used as the electron injection material for the organic electroluminescence device will be given. [ka]

[0060] Furthermore, examples of compounds that can be added to the organic layers of the organic electroluminescence element are given below, which may be used as stabilizing materials, for example.

[0061] [ka]

[0062] <Method of designing composition> The method for designing a composition of the present invention is a method for designing a composition containing a first organic compound, a second organic compound, and a third organic compound, characterized in that the first organic compound, the second organic compound which is a delayed fluorescent material, and the third organic compound which is a fluorescent material are selected so as to satisfy the above conditions (a) to (d). In the method for designing a composition of the present invention, the first organic compound, the second organic compound, and the third organic compound are preferably selected so as to also satisfy the above conditions (f) and (g), and also preferably so as to also satisfy at least one of the above conditions (h), (i), and (j), and more preferably so as to also satisfy all of the above conditions (h1), (i1), and (j1). That is, in the method for designing a composition of the present invention, the first organic compound, the second organic compound, and the third organic compound may be selected so as to satisfy the above conditions (a) to (d), and preferably so as to also satisfy conditions (f) and (g) or at least one of conditions (h), (i), and (j), more preferably so as to satisfy conditions (f) and (g) and at least one of conditions (h), (i), and (j), and particularly preferably so as to satisfy conditions (f) and (g) and all of conditions (h1), (i1), and (j1). For an explanation of the conditions (a) to (d), (f) to (j), and (h1) to (j1), please refer to the description in the <Composition> column above. As described above, an organic compound composition that satisfies the conditions (a) to (d), preferably an organic compound composition that satisfies the conditions (a) to (d), and the conditions (f) to (j), (h1) to (j1), exhibits particularly efficient and highly pure light emission, and particularly high color purity is obtained in the wavelength range of less than 480 nm. In addition, since the conditions (a) to (d), (f) to (j), and (h1) to (j1) are objective indicators shown by the magnitude relationship of numerical values, it is possible to clearly determine whether or not the conditions are satisfied. Therefore, by selecting the first organic compound, the second organic compound, and the third organic compound so as to satisfy the conditions (a) to (d), the conditions (f) to (j), and (h1) to (j1), a composition exhibiting the above-mentioned characteristics can be reliably realized. Here, the population of the first organic compound, the second organic compound, and the third organic compound to be selected may be the compound groups exemplified in the above columns [First organic compound], [Second organic compound], and [Third organic compound]. However, the selection targets used in the design method of the present invention should not be interpreted as being limited by these compound examples.

[0063] <Program> The program of the present invention is a program for carrying out the method for designing a composition of the present invention. For an explanation of the method for designing the composition of the present invention, the description in the above column <Method for Designing the Composition> can be referred to. The program of the present invention is for example a method for selecting a compound group E of a compound that can be used as the first organic compound. S1 (1) A database of compounds that can be used as second organic compounds, S1 (2), λ E EM (2) and λ P EM (2) A database of compounds that can be used as third organic compounds, S1 (3), λ P AB (3) and λ P EM(3) A step of selecting a combination of the first organic compound, the second organic compound, and the third organic compound that satisfies the conditions (a) to (d) by referring to a database in which the above-mentioned compounds are stored. It is preferable that the database for the second organic compounds also stores the LUMO(2) and HOMO(2) of the compound group, and the database for the third organic compounds also stores the LUMO(3) and HOMO(3) of the compound group, and that in the above step, these data are also referred to in selecting a combination of the first organic compound, the second organic compound, and the third organic compound that satisfies conditions (f) and (g) as well as conditions (a) to (d). In addition, the program of the present invention performs R 0 (2-3), r(2-3) and k FRET It is also preferable to have a step of calculating at least one of (2-3), and a step of selecting, from among the combinations, a combination that satisfies at least one of the conditions (h) to (j). An example of the processing procedure of the program of the present invention will be described with reference to FIG. 1. In one embodiment of the program, as shown in FIG. 1, first, one or more combinations of a first organic compound, a second organic compound, and a third organic compound are assumed (S1), and it is determined whether each combination satisfies the conditions (a) to (d) (S2). If it is desired to judge other combinations, steps S1 and S2 are repeated one or more times (S3). The judgment result can be output by displaying it on a display or printing it. The judgment result may be output for each cycle of steps S1 and S2, or may be output all at once after all cycles are completed. In step S3, a subprogram may determine whether to repeat the cycle. For example, a subprogram may be used that issues a command to repeat the cycle until a specific number or more of combinations that satisfy all of the conditions (a) to (d) are found. When the cycle is repeated one or more times, a new combination different from the combination previously assumed is assumed in step S1. At this time, only one of the first organic compound, the second organic compound, and the third organic compound may be changed, any two of them may be changed, or all three of them may be changed. Alternatively, a subprogram may be used in step S1 that reads candidate first organic compounds, second organic compounds, and third organic compounds in advance and sequentially outputs combinations of the candidate compounds. Other modifications obvious to those skilled in the art may be made as appropriate. EXAMPLES

[0064] The features of the present invention will be described in more detail below with reference to examples and comparative examples. The materials, amounts used, ratios, processing contents, processing procedures, etc. shown in the following examples can be changed 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 evaluation of the luminescence characteristics was performed using an absorption spectrum device (UV-2550, manufactured by SHIMAZU) and an absolute PL quantum yield measurement device (manufactured by Hamamatsu Photonics), and the optical calculation was performed using optical calculation software (setfos, manufactured by FLUXiM) using the refractive index of the material, the luminescence efficiency of the luminescent material measured in an integrating sphere, and the measured PL spectrum data. The compounds used in the following Examples and Comparative Examples are shown below. In each Example, compound H1 shown in the host material column corresponds to the first organic compound, compound DF1 or DF2 shown in the delayed fluorescent material column corresponds to the second organic compound, and compound F1 shown in the fluorescent material column corresponds to the third organic compound.

[0065] [ka]

[0066] Tables 1 to 3 show the physical properties of the compounds used in each of the Examples and Comparative Examples.

[0067] [Table 1]

[0068] [Table 2]

[0069] [Table 3]

[0070] The compositions used in each Example and Comparative Example are shown in Table 4. As shown in Table 4, Composition 1 and Composition 2 are compositions that satisfy all of the conditions (a) to (d) and (f) to (j) specified in the present invention. On the other hand, Comparative Composition 1 has a λ E EM (2) (=447 nm) is λ P AB (3) is a composition that does not satisfy condition (b) and does not satisfy conditions (h) to (j) because the value is equal to −10 nm (= 447 nm). E EM (2) (=430 nm) is λ P AB (3) A composition having a value equal to −10 nm (= 430 nm), which does not satisfy condition (b), and does not satisfy conditions (h) to (j).

[0071] [Table 4]

[0072] [1] Preparation and evaluation of thin films Example 1: Preparation of thin film of composition 1 Using the vacuum deposition method, the vacuum degree is 1×10 -6 Compound H1, compound DF1, and compound F1 were deposited from different deposition sources on a quartz substrate under conditions of 100 Pa. The composition ratio of each compound (compound H1:compound DF1:compound F1) was 69:30:1.0 (weight ratio).

[0073] Example 2: Preparation of thin film of composition 2 A thin film (composition 2) was formed in the same manner as in Example 1, except that compound DF2 was used instead of compound DF1.

[0074] Comparative Example 1 Preparation of Thin Film of Comparative Composition 1 A thin film (Comparative Composition 1) was formed in the same manner as in Example 1, except that compound DF3 was used instead of compound DF1.

[0075] Comparative Example 2 Preparation of Thin Film of Comparative Composition 2 A thin film (Comparative Composition 2) was formed in the same manner as in Example 1, except that compound H2 was used instead of compound H1, compound DF4 was used instead of compound DF1, and compound F2 was used instead of compound F1. The emission spectra of the thin films prepared in Examples 1 and 2 and Comparative Example 1 measured with 365 nm excitation light are shown in FIG. 2. The emission maximum wavelength, photoluminescence quantum yield (PLQY), and FW 0.3M The measurement results of the CIE chromaticity coordinates are shown in Table 5.

[0076] [Table 5]

[0077] As shown in Table 5, the luminescence observed in the thin films of Composition 1 and Composition 2 was FW 0.3M The wavelength of the emission from the comparative composition 1, which does not satisfy the condition (b), is broad and has a peak shape of FW 0.3M The wavelength was 54.5 nm, which was wide, and the color purity was low. Furthermore, when the emission spectrum of the thin film of Comparative Composition 2, which does not satisfy the condition (b), was measured using 365 nm excitation light, the spectrum had a broad peak shape with a wide base. This shows that by forming a composition using three types of organic compounds that satisfy conditions (a) to (d), the color purity is significantly improved compared to a composition that does not satisfy condition (b).

[0078] [2] Fabrication and evaluation of organic electroluminescence devices In the following Examples 3 to 5 and Comparative Examples 3 and 4, bottom-emission type organic electroluminescence elements having the layered structure shown in FIG. 3 were fabricated. Example 3: Preparation of an organic electroluminescence device using composition 1 in the light-emitting layer Each thin film was deposited on a glass substrate 1 with an anode 2 made of indium tin oxide (ITO) with a thickness of 50 nm by vacuum deposition at a vacuum degree of 1×10 -6 Pa. First, HATCN was evaporated on ITO to a thickness of 10 nm to form a hole injection layer 3. Next, α-NPD was evaporated to a thickness of 35 nm to form a first hole transport layer 4, and TrisPCz was evaporated to a thickness of 10 nm thereon to form a second hole transport layer 5. Furthermore, mCBP was evaporated to a thickness of 5 nm to form an electron blocking layer 6. Next, a light-emitting layer made of composition 1 was formed. Specifically, compound H1, compound DF1, and compound F1 were co-evaporated from different evaporation sources to form a layer with a thickness of 40 nm to serve as the light-emitting layer 7. At this time, the composition ratio of each compound (compound H1:compound DF1:compound F1) was 69:30:1.0 (weight ratio). Next, compound a was evaporated to a thickness of 10 nm to form a hole blocking layer 8, and compound a and Liq were co-evaporated from different evaporation sources thereon to form a hole transport layer 9 with a thickness of 30 nm. At this time, the composition ratio of each compound (compound a:Liq) was 70:30 (weight ratio). Subsequently, Liq was evaporated to a thickness of 2 nm to form an electron injection layer 10, and Al was evaporated thereon to a thickness of 100 nm to form a cathode 11. Through the above steps, an organic electroluminescence element (EL element 1) using composition 1 in the light-emitting layer was produced.

[0079] (Examples 4 and 5) Preparation of organic electroluminescence elements with different composition ratios of the light-emitting layer An organic electroluminescence element (EL element 2) was produced in the same manner as in Example 3, except that the composition ratio of the light-emitting layer (compound H1:compound DF1:compound F1) was 69.5:30:0.5 (weight ratio). Separately, an organic electroluminescence element (EL element 3) was produced in the same manner as in Example 3, except that the composition ratio of the light-emitting layer (compound H1:compound DF1:compound F1) was 68:30:2.0 (weight ratio).

[0080] Comparative Example 3: Preparation of an organic electroluminescence device not containing compound F1 in the light-emitting layer An organic electroluminescence element (comparative EL element 1) was produced in the same manner as in Example 3, except that the light-emitting layer was formed without using compound F1 and with compound H1:compound DF1 in a weight ratio of 70:30.

[0081] Comparative Example 4: Preparation of an organic electroluminescence device using Comparative Composition 1 in the light-emitting layer An organic electroluminescence element (comparative EL element 2) was produced in the same manner as in Example 3, except that the light-emitting layer was formed using Comparative Composition 1 instead of Composition 1.

[0082] [Evaluation of organic electroluminescence elements through actual measurements] The emission spectra measured for each of the EL devices prepared in Examples 3 to 5 and Comparative Example 3 are shown in Figure 4. In Figure 4, the numbers in parentheses indicate the concentration of compound F1 in the light-emitting layer. In addition, for each of the EL devices prepared in Examples 3 to 5 and Comparative Examples 3 and 4, the emission spectra measured for each of the EL devices prepared in Examples 3 to 5 and Comparative Examples 3 and 4 at 1000 cd / m 2 The driving voltage, external quantum efficiency (EQE), CIE chromaticity coordinates, and emission peak top wavelength (maximum emission wavelength) measured are shown in Table 6.

[0083] [Table 6]

[0084] 4, the emission peaks of EL elements 1 to 3 are clearly narrower than that of comparative EL element 1. Furthermore, as shown in Table 6, EL elements 1 to 3 have higher external quantum efficiency than comparative EL element 1, and also have smaller y values ​​of the chromaticity coordinates than comparative EL elements 1 and 2, indicating high color purity. From this, it was found that by constructing an emitting layer using three types of organic compounds satisfying conditions (a) to (d), the efficiency and color purity are improved compared to an element that does not use a third organic compound, and the color purity is improved compared to an element that uses three types of organic compounds but does not satisfy condition (b).

[0085] [Evaluation of organic electroluminescence devices by calculation] The device characteristics were evaluated by performing an optical simulation based on calculations for bottom-emission type EL device 1 prepared in Example 3, EL device 4 using composition 2 in the light-emitting layer instead of composition 1 of EL device 1, and bottom-emission type comparative EL device 2 prepared in Comparative Example 4. The device characteristics were also evaluated by performing an optical simulation based on calculations for top-emission type EL device 5 using composition 1 in the light-emitting layer, top-emission type EL device 6 using composition 2 in the light-emitting layer, and top-emission type comparative EL device 3 using comparative composition 1 in the light-emitting layer. The results are shown in Table 7. The top-emission type EL elements (EL elements 5, 6, and comparative EL element 3) are top-emission type organic electroluminescence elements in which the following layer configurations are laminated on a glass substrate. In the following layer configurations, " / " indicates the boundary between layers, and the numbers in parentheses indicate the thickness of each layer. The "APC reflective layer" is an alloy layer having a composition of 98% by weight of Ag, 1% by weight of Pd, and 1% by weight of Cu, and the APC reflective layer side is disposed on the glass substrate side. The "composition" is the composition constituting the light-emitting layer, which is composition 1 in EL element 5, composition 2 in EL element 6, and comparative composition 1 in comparative EL element 3. APC reflective layer (150 nm) / ITO anode (10 nm) / HATCN hole injection layer (10 nm) / α-NPD first hole transport layer (35 nm) / TrisPCz second hole transport layer (10 nm) / mCBP electron block layer (5 nm) / composition light emitting layer (40 nm) / compound a hole block layer (10 nm) / compound a (70 wt%):Liq (30 wt%) electron transport layer (30 nm) / Liq electron injection layer (2 nm) / MgAg cathode (15 nm) / α-NPD (105 nm)

[0086] [Table 7]

[0087] As shown in Table 7, EL element 1 using composition 1 and EL element 4 using composition 2 have higher color purity (smaller y value of chromaticity coordinate) than comparative EL element 2 using comparative composition 1, and EL element 5 using composition 1 and EL element 6 using composition 2 have higher color purity (smaller y value of chromaticity coordinate) than comparative EL element 3 using comparative composition 1. In particular, top-emission type EL elements 5 and 6 have significantly improved luminous intensity compared to top-emission type comparative EL element 3. This shows that when an emitting layer is formed using three types of organic compounds that satisfy conditions (a) to (d), the color purity is improved compared to one that does not satisfy condition (b), and the luminous intensity is significantly improved, especially in the top-emission type. The materials used in the organic electroluminescence element other than the light-emitting layer are shown below.

[0088] [ka] [Industrial Applicability]

[0089] The composition of the present invention is a composition that emits light by the TAF mechanism and exhibits high efficiency and high color purity light emission. Therefore, by using the composition of the present invention, a TAF-type organic light-emitting device with high efficiency and high color purity can be easily realized. Therefore, the present invention has a high industrial applicability. [Explanation of symbols]

[0090] 1 Glass substrate 2 Anode 3. Hole injection layer 4 First hole transport layer 5 Second hole transport layer 6 Electron Block Layer 7. Light-emitting layer 8 Hole Blocking Layer 9 Hole transport layer 10 cathode

Claims

1. The present invention includes a first organic compound, a second organic compound which is a delayed fluorescent material, and a third organic compound which is a fluorescent material, which satisfy the following conditions (a) to (d): Condition (a) E Ｓ１ (1)> E Ｓ１ (2)> E Ｓ１ (3) Condition (b) λ Ｅ ＥＭ (2)<λ Ｐ ＡＢ (3)-10nm Condition (c) λ Ｐ ＥＭ (3) < λ Ｐ ＥＭ (2) Condition (d) λ Ｐ ＥＭ (3) < 480nm (In the above formula, E Ｓ１ (1) is the lowest excited singlet energy of the first organic compound; E Ｓ１ (2) is the lowest excited singlet energy of the second organic compound; E Ｓ１ (3) is the lowest excited singlet energy of the third organic compound; λ Ｅ ＥＭ (2) is the short wavelength emission wavelength (unit: nm) of the second organic compound, λ Ｐ ＡＢ (3) is the wavelength (unit: nm) of the peak top on the longest wavelength side of the absorption spectrum of the third organic compound, λ Ｐ ＥＭ (2) is the wavelength of the peak top of the emission spectrum of the second organic compound; λ Ｐ ＥＭ (3) is the wavelength of the peak top of the emission spectrum of the third organic compound Represents.) The second organic compound is a compound represented by the following general formula (1a) or (2a): 【Chemistry 1】 [In general formula (1a), D 1 represents a substituted or unsubstituted carbazol-9-yl group. All four D 1 s have the same chemical structure. Ph represents a phenyl group which may be substituted with at least one group selected from the group consisting of an alkyl group, an aryl group, and a group formed by linking these groups.] 【Chemistry 2】 [In general formula (2a), D 1 represents a substituted or unsubstituted carbazol-9-yl group, and D 2 represents a substituted or unsubstituted carbazol-9-yl group different from D 1 . The two D 2 s have the same chemical structure. The two Phs each independently represent a phenyl group which may be substituted with at least one group selected from the group consisting of an alkyl group, an aryl group, and a group formed by linking these groups.] The composition, wherein the third organic compound is a compound that exhibits multiple resonance between one or more atoms selected from the group consisting of nitrogen atoms, oxygen atoms, and sulfur atoms and a boron atom.

2. The composition according to claim 1 , which satisfies the following condition (e): Condition (e) FW ０．３Ｍ < 40nm (In the above formula, FW ０．３Ｍ represents the spectral width at a relative intensity of 30% of the emission peak of the emission spectrum of the composition.)

3. The composition according to claim 2, which satisfies the following condition (e1): Condition (e1) FW ０．３Ｍ < 32nm

4. The composition according to any one of claims 1 to 3, which satisfies the following conditions (f) and (g): Condition (f) LUMO(2)≦LUMO(3) Condition (g) HOMO(2)≦HOMO(3) (In the above formula, LUMO(2) is the LUMO energy of the second organic compound; LUMO(3) is the LUMO energy of the third organic compound; HOMO(2) is the HOMO energy of the second organic compound, HOMO(3) is the HOMO energy of the third organic compound Represents.)

5. The composition according to any one of claims 1 to 4, which satisfies the following condition (h): Condition (h) R ０ (2-3)>6.5nm (In the above formula, R ０ (2-3) represents the Förster radius between the second organic compound and the third organic compound.

6. The composition according to any one of claims 1 to 5, which satisfies the following condition (i): Condition (i) r(2-3)<3.91nm (In the above formula, r(2-3) represents the intermolecular distance between the second organic compound and the third organic compound.)

7. The composition according to any one of claims 1 to 6, which satisfies the following condition (j): Condition (j) k ＦＲＥＴ (2-3) > 1.5×10 ９ s －１ (In the above formula, k ＦＲＥＴ (2-3) represents the Förster energy transfer rate constant between the second organic compound and the third organic compound.

8. The composition according to any one of claims 1 to 4, which satisfies the following conditions (h1), (i1) and (j1): Condition (h1) R ０ (2-3)≧ 7.3nm Condition (i1) r(2-3)≦3.71nm Condition (j1) k ＦＲＥＴ (2-3) ≧ 6.1×10 ９ s －１ (In the above formula, R ０ (2-3) is the Förster radius between the second organic compound and the third organic compound, r(2-3) is the intermolecular distance between the second organic compound and the third organic compound; k ＦＲＥＴ (2-3) is the Förster energy transfer rate constant between the second organic compound and the third organic compound Represents.)

9. D1 and D ２ Each of the formulas D1 to D37 independently has a structure represented by any one of the following formulas D1 to D37. 【Chemistry 3】 【change】

10. Use of the composition according to any one of claims 1 to 9 as a light-emitting composition.

11. A film comprising the luminescent composition of any one of claims 1 to 9.

12. Use of the film according to claim 11 as a light-emitting film.

13. An organic electroluminescence element having an anode, a cathode, and at least one organic layer including a light-emitting layer between the anode and the cathode, The light-emitting layer comprises the composition according to any one of claims 1 to 9, An organic electroluminescence element, wherein a maximum component of light emitted from the organic electroluminescence element is fluorescence from the third organic compound.

14. The organic electroluminescence device according to claim 13, which is a top-emission type.

15. A method for designing a composition containing a first organic compound, a second organic compound which is a delayed fluorescent material, and a third organic compound which is a fluorescent material, comprising: selecting a first organic compound, a second organic compound which is a delayed fluorescent material, and a third organic compound which is a fluorescent material so as to satisfy the following conditions (a) to (d): Condition (a) E Ｓ１ (1)> E Ｓ１ (2)> E Ｓ１ (3) Condition (b) λ Ｅ ＥＭ (2)<λ Ｐ ＡＢ (3)-10nm Condition (c) λ Ｐ ＥＭ (3) < λ Ｐ ＥＭ (2) Condition (d) λ Ｐ ＥＭ (3) < 480nm (In the above formula, E Ｓ１ (1) is the lowest excited singlet energy of the first organic compound; E Ｓ１ (2) is the lowest excited singlet energy of the second organic compound; E Ｓ１ (3) is the lowest excited singlet energy of the third organic compound; λ Ｅ ＥＭ (2) is the short wavelength emission wavelength (unit: nm) of the second organic compound, λ Ｐ ＡＢ (3) is the wavelength (unit: nm) of the peak top on the longest wavelength side of the absorption spectrum of the third organic compound, λ Ｐ ＥＭ (2) is the wavelength of the peak top of the emission spectrum of the second organic compound; λ Ｐ ＥＭ (3) is the wavelength of the peak top of the emission spectrum of the third organic compound Represents.) The second organic compound is a compound represented by the following general formula (1a) or (2a): 【Chemistry 4】 [In general formula (1a), D 1 represents a substituted or unsubstituted carbazol-9-yl group. All four D 1 s have the same chemical structure. Ph represents a phenyl group which may be substituted with at least one group selected from the group consisting of an alkyl group, an aryl group, and a group formed by linking these groups.] 【Chemistry 5】 [In general formula (2a), D 1 represents a substituted or unsubstituted carbazol-9-yl group, and D 2 represents a substituted or unsubstituted carbazol-9-yl group different from D 1 . The two D 2 s have the same chemical structure. The two Phs each independently represent a phenyl group which may be substituted with at least one group selected from the group consisting of an alkyl group, an aryl group, and a group formed by linking these groups.] The method for designing a composition, wherein the third organic compound is a compound that exhibits multiple resonance between a boron atom and one or more atoms selected from the group consisting of a nitrogen atom, an oxygen atom, and a sulfur atom.

16. The method for designing a composition according to claim 15, wherein the selection is performed so as to also satisfy the following conditions (f) and (g): Condition (f) LUMO(2)≦LUMO(3) Condition (g) HOMO(2)≦HOMO(3) (In the above formula, LUMO(2) is the LUMO energy of the second organic compound; LUMO(3) is the LUMO energy of the third organic compound; HOMO(2) is the HOMO energy of the second organic compound, HOMO(3) is the HOMO energy of the third organic compound Represents.)

17. The method for designing a composition according to claim 15 or 16, wherein the selection is performed so as to also satisfy the following condition (h): Condition (h) R ０ (2-3)>6.5nm (In the above formula, R ０ (2-3) represents the Förster radius between the second organic compound and the third organic compound.

18. The method for designing a composition according to any one of claims 15 to 17, wherein the selection is performed so as to also satisfy the following condition (i): Condition (i) r(2-3)<3.91nm (In the above formula, r(2-3) represents the intermolecular distance between the second organic compound and the third organic compound.)

19. The method for designing a composition according to any one of claims 15 to 18, wherein the selection is performed so as to also satisfy the following condition (j): Condition (j) k ＦＲＥＴ (2-3) > 1.5×10 ９ s －１ (In the above formula, k ＦＲＥＴ (2-3) represents the Förster energy transfer rate constant between the second organic compound and the third organic compound.

20. The method for designing a composition according to claim 15, wherein the selection is performed so as to also satisfy the following conditions (h1), (i1) and (j1). Condition (h1) R ０ (2-3)≧ 7.3nm Condition (i1) r(2-3)≦3.71nm Condition (j1) k ＦＲＥＴ (2-3) ≧ 6.1×10 ９ s －１ (In the above formula, R ０ (2-3) is the Förster radius between the second organic compound and the third organic compound, r(2-3) is the intermolecular distance between the second organic compound and the third organic compound; k ＦＲＥＴ (2-3) is the Förster energy transfer rate constant between the second organic compound and the third organic compound Represents.)

21. A program for carrying out the composition design method according to any one of claims 15 to 20.

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