Color conversion sheet, light source unit including same, display and lighting device

Abstract

A color conversion composition according to an aspect of the present invention converts incident light into light of a wavelength different from that of the incident light, and contains a binder resin, and a luminescence material (a) and a luminescence material (b) that are described below. The luminescence material (a) and / or the luminescence material (b) is a compound that emits delayed fluorescence. The luminescence material (a) is a luminescence material with a luminescence peak wavelength of 500 nm or more but less than 580 nm. The luminescence material (b) is a luminescence material with a luminescence peak wavelength of 580-750 nm inclusive.

Description

Color-converting composition, color-converting sheet, light source unit including the same, display, and lighting device

[0001] The present invention relates to a color-converting composition, a color-converting sheet, a light source unit including the same, a display, and a lighting device.

[0002] There has been active research into applying multi-color technology using color conversion methods to liquid crystal displays, organic EL displays, lighting devices, etc. Color conversion refers to converting light emitted from a light emitter into light with a longer wavelength, such as converting blue light into green or red light.

[0003] By forming this composition having color conversion function (hereinafter referred to as color conversion composition) into a sheet and combining it with, for example, a blue light source, it becomes possible to obtain the three primary colors of blue, green, and red from the blue light source, i.e., to obtain white light. A white light source combining such a blue light source with a sheet having color conversion function (hereinafter referred to as color conversion sheet) is used as a light source unit such as a backlight unit, and by combining this light source unit with a liquid crystal driving part and a color filter, it becomes possible to produce a full-color display. Furthermore, a white light source combining a blue light source with a color conversion sheet can also be used directly as a white light source for LED lighting, etc.

[0004] One of the challenges facing liquid crystal displays that utilize a color conversion system is improving color reproducibility and durability. To improve color reproducibility, it is effective to narrow the half-widths of the blue, green, and red emission spectra of the light source unit and increase the color purity of each of the blue, green, and red colors. To solve this problem, for example, color conversion materials containing pyrromethene compounds have been proposed (see, for example, Patent Documents 1 and 2). Furthermore, a technique for improving durability has been proposed in which a light stabilizer is added (see, for example, Patent Document 3), but this technique still results in insufficient durability. Therefore, a light-emitting material having an electron-withdrawing group has been proposed as a technique for improving color reproducibility and durability (see, for example, Patent Document 4).

[0005] JP 2010-61824 A JP 2014-136771 A JP 2019-50381 A International Publication No. 2016 / 190283

[0006] The technology described in Patent Document 4 makes it possible to obtain color-changing compositions that have excellent color reproducibility and excellent durability with little decrease in luminance even when used continuously for long periods of time. However, in response to recent demands for finer and higher definition, it has been found that conventional color-changing compositions have a new problem in that their chromaticity changes slightly with long-term use.

[0007] The present invention has been made in view of the above circumstances, and a first object thereof is to provide a color-converting composition that exhibits excellent chromaticity durability. A second object thereof is to provide a color-converting sheet that uses the color-converting composition. A third object thereof is to provide a light source unit, a display, and a lighting device that include the color-converting composition or the color-converting sheet.

[0008] In order to solve the above-mentioned problems and achieve the object, the color conversion composition according to the present invention is [1] a color conversion composition that converts incident light into light of a wavelength different from that of the incident light, and is characterized in that it comprises a binder resin and the following luminescent material (a) and luminescent material (b), wherein at least one of the luminescent material (a) and the luminescent material (b) is a compound that emits delayed fluorescence. Luminescent material (a): a luminescent material having an emission peak wavelength of 500 nm or more and less than 580 nm Luminescent material (b): a luminescent material having an emission peak wavelength of 580 nm or more and 750 nm or less

[0009] The color-converting composition according to the present invention is [2] characterized in that, in the invention [1] above, the compound that emits delayed fluorescence is a compound represented by the following general formula (1) or general formula (2):

[0010] (Ring Za, ring Zb, and ring Zc are each independently a substituted or unsubstituted aryl ring having 6 to 30 ring carbon atoms, or a substituted or unsubstituted heteroaryl ring having 6 to 30 ring carbon atoms. Z 1 and Z 2are each independently an oxygen atom, NRa (a nitrogen atom having a substituent Ra), or a sulfur atom. 1 When R is NRa, the substituent R may be bonded to the ring Za or the ring Zb to form a ring. 2 When R is NRa, the substituent R may be bonded to the ring Z or the ring Zc to form a ring. E is a boron atom, a phosphorus atom, SiRa (a silicon atom having a substituent R) or P=O. E 1 and E 2 are each independently BRa (a boron atom having a substituent Ra), PRa (a phosphorus atom having a substituent Ra), SiRa2 (a silicon atom having two substituents Ra), C=O, P(=O)Ra2 (a phosphine oxide having two substituents Ra), or P(=S)Ra2 (a phosphine sulfide having two substituents Ra), S(=O) or S(=O)2. E 1 When is BRa, PRa, SiRa2, P(=O)Ra2 or P(=S)Ra2, the substituent Ra may be bonded to ring Za or ring Zb to form a ring. 2 is BRa, PRa, SiRa2, P(=O)Ra2, or P(=S)Ra2, the substituent Ra may be bonded to ring Za or ring Zc to form a ring. The substituents Ra are each independently a substituted or unsubstituted aryl group, a substituted or unsubstituted heteroaryl group, or a substituted or unsubstituted alkyl group.

[0011] The color-changing composition according to the present invention is [3] the invention of the above [2], wherein the compound that emits delayed fluorescence is a compound represented by the general formula (1), E in the general formula (1) is a boron atom, and Z 1 and Z 2 are each independently NRa, or the compound that emits delayed fluorescence is a compound represented by the general formula (2), and E 1 and E 2 are each independently BRa.

[0012] The color-converting composition according to the present invention is characterized in that, in any one of the above-mentioned inventions [1] to [3], the one of the luminescent material (a) and the luminescent material (b) that is not the compound that emits delayed fluorescence is a compound represented by the following general formula (3):

[0013] (X is C-R 7 Or N. 1 ~R 9 may be the same or different and are selected from hydrogen, an alkyl group, a cycloalkyl group, a heterocyclic group, an alkenyl group, a cycloalkenyl group, an alkynyl group, a hydroxyl group, a thiol group, an alkoxy group, an alkylthio group, an aryl ether group, an aryl thioether group, an aryl group, a heteroaryl group, a halogen atom, a cyano group, an aldehyde group, a carbonyl group, a carboxyl group, an oxycarbonyl group, a carbamoyl group, an amino group, a nitro group, a silyl group, a siloxanyl group, a boryl group, a phosphine oxide group, and a fused ring or an aliphatic ring formed between adjacent substituents.

[0014] Furthermore, the color-converting composition according to the present invention is [5] any one of the above-mentioned [1] to [4], characterized in that the luminescent material (a) is a compound that emits delayed fluorescence.

[0015] The color-converting composition according to the present invention is [6] any one of the above [1] to [5], characterized in that the half-width of the emission spectrum at the emission peak wavelength of the luminescent material (a) is 30 nm or more and 40 nm or less.

[0016] The color conversion sheet according to the present invention is characterized in that it contains the color conversion composition according to any one of the above inventions [1] to [6] or a cured product thereof.

[0017] The color conversion sheet according to the present invention is [8] characterized in that in the invention [7] above, the luminescent material (a) and the luminescent material (b) are contained in the same layer.

[0018] The color conversion sheet according to the present invention is [9] characterized in that, in the invention [8] above, the molar ratio of the luminescent material (a) to the luminescent material (b) contained in the same layer is luminescent material (a):luminescent material (b)=50:1 to 500:1.

[0019] Furthermore, the color conversion sheet according to the present invention is

[10] the invention of the above [8] or [9], characterized in that the luminescent material (b) is a compound that emits delayed fluorescence, and when the energy level of the triplet excited state of the luminescent material (a) is T1a and the energy level of the triplet excited state of the luminescent material (b) is T1b, |T1a-T1b|≦0.2 eV.

[0020] The color conversion sheet according to the present invention is

[11] the above invention [7], characterized in that it comprises at least the following (A) layer and (B) layer: (A) layer: a layer containing at least the luminescent material (a) and a binder resin; (B) layer: a layer containing at least the luminescent material (b) and a binder resin.

[0021]

[12] The color conversion sheet according to the present invention is characterized in that, in the invention

[11] above, the molar ratio of the luminescent material (a) contained in the (A) layer to the luminescent material (b) contained in the (B) layer is luminescent material (a):luminescent material (b)=5:1 to 100:1.

[0022] The light source unit according to the present invention is characterized in that it comprises a light source

[13] and the color-converting composition according to any one of the inventions [1] to [6] above or the color-converting sheet according to any one of the inventions [7] to

[12] above.

[0023]

[14] A display according to the present invention is characterized by including the light source unit according to the invention

[13] above.

[0024]

[15] A lighting device according to the present invention is characterized in that it includes the light source unit according to the invention

[13] above.

[0025] The present invention has the effect of providing a color-converting composition and a color-converting sheet that exhibit excellent chromaticity durability. The color-converting composition of the present invention and a color-converting sheet using the same can improve durability against chromaticity changes. Furthermore, the light source unit, display, and lighting device of the present invention can improve durability against chromaticity changes by including the color-converting composition or the color-converting sheet.

[0026] Fig. 1 is a schematic cross-sectional view showing a first example of a color conversion sheet according to an embodiment of the present invention. Fig. 2 is a schematic cross-sectional view showing a second example of a color conversion sheet according to an embodiment of the present invention. Fig. 3 is a schematic cross-sectional view showing a third example of a color conversion sheet according to an embodiment of the present invention. Fig. 4 is a schematic cross-sectional view showing a fourth example of a color conversion sheet according to an embodiment of the present invention.

[0027] Preferred embodiments of the color-converting composition, color-converting sheet, light source unit, display, and lighting device containing the same according to the present invention will be specifically described below, but the present invention is not limited to the following embodiments and can be modified and implemented in various ways depending on the purpose and application.

[0028] <Color Conversion Composition> A color conversion composition according to an embodiment of the present invention converts incident light from a light emitter such as a light source into light with a wavelength different from that of the incident light, and includes a binder resin and the following light-emitting material (a) and light-emitting material (b). The light-emitting material (a) is a light-emitting material with a peak emission wavelength of 500 nm or more and less than 580 nm. The light-emitting material (b) is a light-emitting material with a peak emission wavelength of 580 nm or more and 750 nm or less. At least one of the light-emitting material (a) and the light-emitting material (b) is a compound that emits delayed fluorescence. Hereinafter, "converting into light with a wavelength different from that of the incident light" preferably means converting the incident light into light with a wavelength longer than that of the incident light. Hereinafter, the color conversion composition according to an embodiment of the present invention may be abbreviated as the color conversion composition of the present invention.

[0029] In the color-converting composition of the present invention, the luminescent material (a) emits light with a peak wavelength observed in the region of 500 nm or more and less than 580 nm when excited with excitation light. The luminescent material (b) emits light with a peak wavelength observed in the region of 580 nm or more and less than 750 nm when excited with excitation light. Hereinafter, the luminescence observed in the region of 500 nm or more and less than 580 nm is referred to as "green luminescence," and the luminescence observed in the region of 580 nm or more and less than 750 nm is referred to as "red luminescence."

[0030] Furthermore, by using at least one of the luminescent material (a) and the luminescent material (b) as a compound that emits delayed fluorescence, the durability of the color-converting composition of the present invention against changes in chromaticity can be improved. Hereinafter, durability against changes in chromaticity may be abbreviated as "chromaticity durability" or simply "durability." Hereinafter, according to the present invention, for example, when the luminescent material (a) is a compound that emits delayed fluorescence and the luminescent material (b) is a compound other than the compound that emits delayed fluorescence, the durability of not only the luminescent material (a) itself but also the luminescent material (b) can be improved. As a result, the durability of the entire color-converting composition of the present invention can be improved.

[0031] The improvement in durability will be described in detail later, but this is because, when at least one of the luminescent material (a) and the luminescent material (b) is a compound that emits delayed fluorescence, it is possible to suppress the generation of singlet oxygen, which causes deterioration of the luminescent material. By suppressing the generation of singlet oxygen, not only the deterioration of the compound that emits delayed fluorescence but also the deterioration of the compound that does not emit delayed fluorescence is suppressed.

[0032] As a specific example, the pyrromethene derivative described below has a high electron density in the molecule, and therefore is easily reactive with electron-deficient singlet oxygen, i.e., is susceptible to oxidative degradation by singlet oxygen. Therefore, for example, when the luminescent material (a) is a compound that emits delayed fluorescence and the luminescent material (b) is a pyrromethene derivative, the durability of not only the luminescent material (a) itself but also the luminescent material (b) can be improved. As a result, the effect of improving the durability of the entire color-converting composition of the present invention is particularly easily achieved.

[0033] The light-emitting material (a) is preferably a light-emitting material that emits light with a peak wavelength of 500 nm or more and 550 nm or less when excited with light having a wavelength in the range of 430 nm or more and 500 nm or less.

[0034] Furthermore, it is preferable that the luminescent material (b) is a luminescent material that, when excited by either or both of excitation light having a wavelength in the range of 430 nm or more and 500 nm or less and the emission from the luminescent material (a), exhibits luminescence whose peak wavelength is observed in the range of 580 nm or more and 680 nm or less.

[0035] A portion of excitation light in the wavelength range of 430 nm or more and 500 nm or less is transmitted through the color conversion composition of the present invention or a portion of a color conversion sheet using the color conversion composition. Therefore, when a blue LED with a sharp emission peak is used as a light source of the excitation light, a sharply shaped emission spectrum is exhibited in each of the blue, green, and red colors, and white light with excellent color purity can be obtained. As a result, particularly in displays, a wider color gamut with more vivid colors can be efficiently produced. Furthermore, in lighting applications, the emission characteristics, particularly in the green and red regions, are improved compared to white LEDs that combine a blue LED and a yellow phosphor, which are currently mainstream, and therefore color rendering properties are improved, thereby enabling the realization of a desirable white light source.

[0036] The contents of the luminescent material (a) and the luminescent material (b) in the color-converting composition of the present invention can be selected depending on the molar absorption coefficient, fluorescence quantum yield, and absorption intensity at the excitation wavelength of the compound, as well as the thickness and transmittance of the color-converting sheet to be produced. Here, the contents of the luminescent material (a) and the luminescent material (b) refer to the total contents when two or more types of the luminescent material (a) and the luminescent material (b) are contained. The contents of the luminescent material (a) and the luminescent material (b) are 1.0 × 10 based on 100 parts by weight of the binder resin contained in the color-converting composition of the present invention. -2 It is preferably at least 1 part by weight and not more than 5 parts by weight.

[0037] (Compounds that Emit Delayed Fluorescence) Compounds that emit delayed fluorescence are discussed on pages 87-103 of "State-of-the-Art Organic EL" (edited by Adachi Chinaya and Fujimoto Hiroshi, published by CMC Publishing). The document explains that by bringing the energy levels of the singlet excited state and triplet excited state of an emitting material closer together, reverse energy transfer from the triplet excited state, which normally has a low transition probability, to the singlet excited state occurs with high efficiency, resulting in the manifestation of thermally activated delayed fluorescence (TADF). Furthermore, Figure 5 in the document explains the mechanism by which delayed fluorescence occurs. Delayed fluorescence emission can be confirmed by transient photoluminescence (PL) measurements.

[0038] It has also been reported that matching the energy levels of the singlet excited state and triplet excited state of a light-emitting material can speed up the reverse energy transfer from the triplet excited state to the singlet excited state (Nature Photonics volume 14, pages 643-649 (2020)). Furthermore, active research is being conducted on compounds whose triplet excited state energy level is higher than that of the singlet excited state of the light-emitting material.

[0039] In this specification, a compound that emits fluorescence by transitioning from a triplet excited state to a singlet excited state with high efficiency, including a compound that exhibits thermally activated delayed fluorescence, is referred to as a "compound that emits delayed fluorescence."

[0040] Typically, fluorescent light is emitted from a singlet excited state generated after photoexcitation of a light-emitting material, and the triplet excited state of the light-emitting material generated by intersystem crossing is thermally deactivated in a room temperature environment. Therefore, fluorescence is not emitted from the triplet excited state of the light-emitting material. On the other hand, as described above, a compound that emits delayed fluorescence quickly converts a triplet excited state into a singlet excited state even if the triplet excited state is generated, and then emits fluorescence. Therefore, the triplet excited state, which cannot contribute to light emission in ordinary fluorescent materials, can also contribute to fluorescent light emission. Therefore, highly efficient light emission can be obtained.

[0041] Compounds that emit delayed fluorescence have the characteristic of not easily generating singlet oxygen because their triplet excited state quickly converts to a singlet excited state. This characteristic has been found to prevent degradation of luminescent materials, suppress changes in chromaticity over time, and improve durability. This mechanism will be explained in detail below.

[0042] First, we will explain the degradation mechanism of luminescent materials. The chromaticity change of a color-changing composition is caused by degradation of the luminescent material. This degradation of the luminescent material is caused by singlet oxygen. Singlet oxygen is an oxygen molecule in a singlet state in which the two electrons occupying the π* orbital (antibonding π orbital) of the oxygen molecule's molecular orbital have different spin directions, i.e., an excited state in which the total spin quantum number is zero. This excited state exists in two states: the Σ1 state, in which each of the two π* orbitals is occupied by an electron with a different spin direction, and the Δ1 state, in which only one of the π* orbitals is occupied by two electrons with a different spin direction. In the Δ1 state, the vacant electron orbital of singlet oxygen has strong electrophilicity and strong oxidizing power. Therefore, singlet oxygen is thought to cause oxidative degradation of the luminescent material.

[0043] Next, we will discuss the mechanism by which singlet oxygen is generated. It is thought that singlet oxygen is unlikely to be generated by direct photoexcitation of ground-state triplet oxygen. This is because the transition from ground-state triplet oxygen to excited-state singlet oxygen is a spin-forbidden transition, and therefore the transition probability is extremely low.

[0044] Therefore, it is believed that the generation of singlet oxygen in the color-changing composition is due to dye sensitization. In other words, it is believed that singlet oxygen is generated by the exchange of electrons and energy between the triplet excited state of the light-emitting material and the triplet oxygen molecule in the ground state. The generation mechanism is believed to be as follows.

[0045] First, photoexcitation causes the light-emitting material to transition from the singlet ground state to the singlet excited state. Furthermore, a portion of the light-emitting material transitions from the singlet excited state to the triplet excited state through intersystem crossing. The transition from the triplet excited state to the singlet ground state of the generated light-emitting material is a spin-forbidden transition, so the transition probability is usually low and the triplet excited state has a long lifetime. However, when triplet oxygen in the ground state coexists, the spin forbidden state is lifted by the excitation from the ground state triplet oxygen to the excited state singlet oxygen, allowing the light-emitting material to quickly deactivate from the triplet excited state to the singlet ground state. This mechanism is called the Dexter mechanism (electron exchange mechanism).

[0046] The Dexter mechanism requires electron exchange via intermolecular wave function overlap, which is thought to require direct collision between an energy donor molecule (in this case, a light-emitting material in the triplet excited state) and an energy acceptor molecule (in this case, triplet oxygen in the ground state).

[0047] As mentioned above, compounds that emit delayed fluorescence have the property that the triplet excited state quickly converts to the singlet excited state, i.e., the lifetime of the triplet excited state is short. This reduces the probability of direct collision between the triplet excited state of the luminescent material and triplet oxygen in the ground state, making it difficult for singlet oxygen to be generated.

[0048] In order to design a molecule so that the energy levels of the singlet excited state and the triplet excited state are close to each other, it is effective to bond an electron donor skeleton and an electron acceptor skeleton within the same molecule. By doing so, the HOMO (highest occupied molecular orbital) orbital and the LUMO (lowest unoccupied molecular orbital) orbital can be separated within the molecule. The electron donor skeleton and the electron acceptor skeleton may be bonded directly or via a linking group. In this case, the linking group is preferably a skeleton containing an aromatic hydrocarbon.

[0049] Examples of electron donor skeletons include skeletons having an amine nitrogen atom. Among them, skeletons containing diarylamine or triarylamine, skeletons containing carbazole, skeletons containing benzocarbazole, skeletons containing indolocarbazole, skeletons containing phenoxazine, and skeletons containing phenothiazine are preferred. Among these, skeletons containing carbazole, skeletons containing benzocarbazole, skeletons containing indolocarbazole, and skeletons containing phenoxazine are more preferred, and skeletons containing carbazole and skeletons containing phenoxazine are even more preferred.

[0050] On the other hand, examples of electron-accepting skeletons include skeletons containing electron-withdrawing substituents (i.e., electron-withdrawing groups). Electron-withdrawing groups, also called electron-accepting groups, are atomic groups that attract electrons from substituted atomic groups due to inductive effects or resonance effects in organic electronics theory. Examples of electron-withdrawing groups include those whose Hammett's rule substituent constant (σp(para)) is a positive value. The Hammett's rule substituent constant (σp(para)) can be cited from the Revised 5th Edition of the Basic Chemistry Handbook (page II-380). It should be noted that, although there are examples in which phenyl groups also have a positive value, phenyl groups are not included in the electron-withdrawing groups of the present invention.

[0051] Examples of the electron-withdrawing group include -F (σp: +0.20), -Cl (σp: +0.28), -Br (σp: +0.30), -I (σp: +0.30), and -COR. 12 (σp:R12 is an ethyl group, -CONH2 (σp: +0.45), -COR 12 (σp:R 12 is a methyl group, -CF3 (σp: +0.49), -SO2R 12 (σp:R 12 is a methyl group), -NO2 (σp: +0.69), etc. 12 each independently represents a hydrogen atom, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 ring carbon atoms, a substituted or unsubstituted heterocyclic group having 5 to 30 ring atoms, a substituted or unsubstituted alkyl group having 1 to 30 carbon atoms, or a substituted or unsubstituted cycloalkyl group having 1 to 30 carbon atoms. Specific examples of each of these groups include the same examples as those of the compound represented by general formula (3) described below.

[0052] Among the skeletons containing an electron-withdrawing group, preferred are a skeleton containing a heteroaryl group having a partial structure in which a carbon atom and a nitrogen atom are bonded by a double bond, a skeleton containing a fluorinated substituent, a skeleton containing a cyano group, a skeleton containing a carbonyl group, a skeleton containing a sulfoxide or disulfoxide, and a skeleton containing a phosphine oxide group. Among these, a skeleton containing a heteroaryl group having a partial structure in which a carbon atom and a nitrogen atom are bonded by a double bond, a skeleton containing a fluorinated substituent, and a skeleton containing a cyano group are more preferred from the viewpoint of the stability of the compound that emits delayed fluorescence.

[0053] Among the skeletons containing a heteroaryl group having a partial structure in which a carbon atom and a nitrogen atom are bonded by a double bond, specifically, a skeleton containing pyridine, pyrimidine, pyrazine, triazine, quinoline, quinoxaline, quinazoline, or phenanthroline is preferred. Among these, a skeleton containing pyrimidine, triazine, quinoxaline, or quinazoline is more preferred, and a skeleton containing triazine is even more preferred.

[0054] Among the skeletons containing fluorinated substituents, skeletons containing fluorinated aryl groups or fluoroalkyl groups are more preferred.As the skeletons containing fluorinated aryl groups, fluorinated benzene rings are preferred, and specifically, skeletons containing fluorobenzene, difluorobenzene, trifluorobenzene, tetrafluorobenzene or pentafluorobenzene are more preferred.As the skeletons containing fluoroalkyl groups, skeletons containing benzene rings substituted with trifluoromethyl groups are preferred, and among these, skeletons containing mono(trifluoromethyl)benzene or bis(trifluoromethyl)benzene are more preferred.

[0055] Among the skeletons having a cyano group, skeletons containing cyanobenzene, dicyanobenzene, and tricyanobenzene are more preferred.

[0056] Examples of compounds in which the above-described electron donor skeleton and electron acceptor skeleton are bonded are shown below, but the compounds are not particularly limited to these. Note that the compounds shown here are known from previous literature to emit delayed fluorescence.

[0057]

[0058] In addition to the above-described compounds in which an electron donor skeleton and an electron acceptor skeleton are bonded, compounds represented by the following general formula (1) or (2) are preferred as compounds that emit delayed fluorescence:

[0059]

[0060] In general formula (1) or general formula (2), ring Za, ring Zb, and ring Zc each independently represent a substituted or unsubstituted aryl ring having 6 to 30 ring carbon atoms, or a substituted or unsubstituted heteroaryl ring having 6 to 30 ring carbon atoms.

[0061] In general formula (1), Z 1 and Z 2 are each independently an oxygen atom, NRa (a nitrogen atom having a substituent Ra), or a sulfur atom. 1When R is NRa, the substituent R may be bonded to the ring Za or the ring Zb to form a ring. 2 When R is NRa, the substituent R may be bonded to the ring Z or the ring Zc to form a ring. E is a boron atom, a phosphorus atom, SiRa (a silicon atom having a substituent R), or P=O.

[0062] In the general formula (2), E 1 and E 2 are each independently BRa (a boron atom having a substituent Ra), PRa (a phosphorus atom having a substituent Ra), SiRa2 (a silicon atom having two substituents Ra), C=O, P(=O)Ra2 (a phosphine oxide having two substituents Ra), or P(=S)Ra2 (a phosphine sulfide having two substituents Ra), S(=O) or S(=O)2. E 1 When is BRa, PRa, SiRa2, P(=O)Ra2 or P(=S)Ra2, the substituent Ra may be bonded to ring Za or ring Zb to form a ring. 2 When is BRa, PRa, SiRa2, P(=O)Ra2 or P(=S)Ra2, the substituent Ra may be bonded to ring Za or ring Zc to form a ring.

[0063] The substituents Ra are each independently a substituted or unsubstituted aryl group, a substituted or unsubstituted heteroaryl group, or a substituted or unsubstituted alkyl group.

[0064] In all of the above groups, hydrogen may be deuterium. This also applies to the compounds or partial structures thereof described below. In the following description, for example, a substituted or unsubstituted aryl group having 6 to 40 carbon atoms refers to an aryl group having 6 to 40 carbon atoms, including the number of carbon atoms contained in the substituents substituted on the aryl group. The same applies to other substituents that specify the number of carbon atoms.

[0065] The term "unsubstituted" in the context of "substituted or unsubstituted" means that a hydrogen atom or a deuterium atom has been substituted. The same applies to the term "substituted or unsubstituted" in the compounds or partial structures thereof described below.

[0066] In addition, in all of the above groups, the substituent when substituted is an alkyl group, a cycloalkyl group, a heterocyclic group, an alkenyl group, a cycloalkenyl group, an alkynyl group, an aryl group, a heteroaryl group, a hydroxyl group, a thiol group, an alkoxy group, an alkylthio group, an aryl ether group, an aryl thioether group, a halogen atom, a cyano group, an aldehyde group, a carbonyl group, a carboxyl group, an oxycarbonyl group, an amide group, a sulfonyl group, a sulfonate ester group, a sulfonamide group, an amino group, a nitro group, a silyl group, a siloxanyl group, a boryl group, or a phosphine oxide group. In addition, these substituents may be further substituted with the above-mentioned substituents.

[0067] The explanation of each group such as the "alkyl group" is as shown in the explanation of the compound represented by the general formula (3) below.

[0068] Examples of the substituted or unsubstituted aryl ring having 6 to 30 ring carbon atoms in ring Za, ring Zb, and ring Zc include aromatic hydrocarbon rings such as a benzene ring, a naphthalene ring, a phenanthrene ring, a chrysene ring, an anthracene ring, and a pyrene ring. Of these, a benzene ring is preferred from the viewpoint of ensuring solubility. Furthermore, examples of heteroaryl rings having 6 to 30 ring carbon atoms include aromatic heteroaryl ring structures such as a pyridine ring, a quinoline ring, and a phenanthroline ring. Of these, a pyridine ring is preferred from the viewpoints of ease of raw material availability and difficulty of synthesis.

[0069] The substituent Ra is preferably a group having 6 to 40 carbon atoms including the substituent. The substituent Ra is more preferably a substituted or unsubstituted aryl group. Examples of the substituted or unsubstituted aryl group include a substituted or unsubstituted phenyl group, a substituted or unsubstituted biphenyl group, a substituted or unsubstituted fluorenyl group, a substituted or unsubstituted naphthyl group, and a substituted or unsubstituted phenanthrenyl group. Among these, a substituted or unsubstituted phenyl group is more preferred.

[0070] The substituent Ra is preferably a group having 6 to 40 carbon atoms including the substituent, and more preferably a substituted or unsubstituted heteroaryl group or a substituted or unsubstituted alkyl group.

[0071] Z in general formula (1) 1 and Z 2 is preferably an oxygen atom or NRa, because the π-conjugated system of the compound represented by general formula (1) is efficiently expanded, and reverse intersystem crossing from the triplet excited state to the singlet excited state occurs more efficiently, thereby further improving durability.

[0072] Furthermore, E in the general formula (1) is preferably a boron atom, and E in the general formula (2) is preferably a 1 and E 2 is preferably BRa, because the π-conjugated system of the compound represented by general formula (1) or general formula (2) is efficiently expanded, and reverse intersystem crossing from the triplet excited state to the singlet excited state occurs more efficiently, thereby further improving durability.

[0073] That is, the compound that emits delayed fluorescence is a compound represented by general formula (1), in which E in general formula (1) is a boron atom and Z 1 and Z 2 are each independently an oxygen atom or NRa. Alternatively, the compound that emits delayed fluorescence is a compound represented by general formula (2), and E in general formula (2) 1 and E 2 are each independently BRa.

[0074] Furthermore, ring Za, ring Zb, and ring Zc are preferably benzene rings, because the π-conjugated system of the compound represented by general formula (1) or general formula (2) is efficiently expanded, and reverse intersystem crossing from the triplet excited state to the singlet excited state occurs more efficiently, thereby further improving durability.

[0075] The compound represented by general formula (1) or general formula (2) is a molecule that can separate the HOMO orbital and the LUMO orbital by the multiple resonance effect by optimally arranging an electron-donating amine nitrogen atom and an electron-accepting boron atom, as described in, for example, the literature Adv. Mater., 2016, 28, 2777-2781. From the viewpoint of clearly separating the HOMO orbital and the LUMO orbital and bringing the singlet excited state and the triplet excited state closer to each other, thereby facilitating the emission of delayed fluorescence, in general formula (1), E is a boron atom with strong electron-accepting properties, and Z １ and Z ２ In other words, when the compound emitting delayed fluorescence is a compound represented by general formula (1), E is a boron atom and Z 1 and Z 2 is preferably NRa.

[0076] In addition, the emission spectrum of a compound represented by general formula (1) or general formula (2) is sharper than that of a compound in which an electron donor skeleton and an electron acceptor skeleton are bonded due to the multiple resonance effect of the compound. Therefore, when the compound that emits delayed fluorescence is a compound represented by general formula (1) or general formula (2), light emission with high color purity can be obtained. That is, compounds represented by general formula (1) or general formula (2) are advantageous for improving the color gamut of the display, and are therefore preferred as compounds that emit delayed fluorescence. In addition, in compounds represented by general formula (1) or general formula (2), rings Za, Zb, and Zc are present around the E atom in general formula (1) or general formula (2), where the LUMO orbital is mainly localized, so that the LUMO orbital can be delocalized from the E atom to each ring. By delocalizing the LUMO orbital, the multiple resonance effect works efficiently, resulting in light emission with higher color purity. Note that the E atom is the E atom in general formula (1), and the E atom in general formula (2). 1 and E 2 are the atoms of

[0077] Furthermore, it is more preferable that the substituent Ra in the general formula (1) or the general formula (2) forms a ring structure bonded to at least one of the rings Za, Zb, and Zc, because the substituent Ra is bonded to at least one of the rings Za, Zb, and Zc, and thus the substituent Ra is bonded to at least one of the rings Za, Zb, and Zc, and thus the substituent Ra is bonded to at least one of the rings Za, Zb, and Zc, and thus forms a ring structure bonded to at least one of the rings Za, Zb, and Zc, and thus forms at least one of the rings Za, Zb, and Zc, and the substituent Ra is bonded to at least one of the rings Za, Zb, and Zc, and thus forms at least one of the rings Zc, Zb, and Zc, Zc, Zc, Zb, and Zc, Zc, Zc, Zb, and Zc, Zc, Zc, Zc, Zb ... 1 and E 2 This is because it is expected that the steric protection effect of the compound will be further enhanced, and the effect of suppressing a decrease in the fluorescence quantum yield will be further improved.

[0078] Examples of compounds represented by general formula (1) or general formula (2) are shown below, but the compounds are not particularly limited to these.

[0079]

[0080] (Other luminescent materials) Either the luminescent material (a) or the luminescent material (b) may be a luminescent material (other luminescent material) other than a compound that emits delayed fluorescence. In addition to the compound that emits delayed fluorescence, examples of the luminescent material used in either the luminescent material (a) or the luminescent material (b) include inorganic phosphors, fluorescent pigments, fluorescent dyes, quantum dots, etc. The other luminescent material may contain two or more of these. In order to achieve highly efficient color conversion, the other luminescent material is preferably a material that exhibits luminescent properties with high quantum yield. Specifically, quantum dots and organic luminescent materials are preferred, and organic luminescent materials are more preferred.

[0081] Suitable examples of the organic light-emitting material include compounds having a condensed aryl ring, such as naphthalene, anthracene, phenanthrene, pyrene, chrysene, naphthacene, triphenylene, perylene, fluoranthene, fluorene, and indene, and derivatives thereof.

[0082] Suitable examples of the organic light-emitting material include compounds having a heteroaryl ring, such as furan, pyrrole, thiophene, silole, 9-silafluorene, 9,9′-spirobisilafluorene, benzothiophene, benzofuran, indole, dibenzothiophene, dibenzofuran, imidazopyridine, phenanthroline, pyridine, pyrazine, naphthyridine, quinoxaline, and pyrrolopyridine, and derivatives thereof.

[0083] Suitable organic light-emitting materials include, for example, borane derivatives, stilbene derivatives, aromatic acetylene derivatives, tetraphenylbutadiene derivatives, aldazine derivatives, pyrromethene derivatives, diketopyrrolo[3,4-c]pyrrole derivatives, and coumarin derivatives. Examples of stilbene derivatives include 1,4-distyrylbenzene, 4,4'-bis(2-(4-diphenylaminophenyl)ethenyl)biphenyl, and 4,4'-bis(N-(stilben-4-yl)-N-phenylamino)stilbene. Examples of coumarin derivatives include coumarin 6, coumarin 7, and coumarin 153.

[0084] Suitable examples of the organic light-emitting material include azole derivatives such as imidazole, thiazole, thiadiazole, carbazole, oxazole, oxadiazole, and triazole, and metal complexes thereof.

[0085] Suitable organic light-emitting materials include, for example, cyanine compounds, xanthene compounds, and thioxanthene compounds. Examples of cyanine compounds include indocyanine green. Examples of xanthene compounds and thioxanthene compounds include fluorescein, eosin, and rhodamine.

[0086] Suitable organic light-emitting materials include, for example, polyphenylene compounds, naphthalimide derivatives, phthalocyanine derivatives and metal complexes thereof, porphyrin derivatives and metal complexes thereof, oxazine compounds, helicene compounds, etc. Examples of oxazine compounds include Nile Red and Nile Blue.

[0087] Suitable organic light-emitting materials include, for example, aromatic amine derivatives and organometallic complex compounds. Examples of aromatic amine derivatives include N,N'-diphenyl-N,N'-di(3-methylphenyl)-4,4'-diphenyl-1,1'-diamine. Examples of organometallic complex compounds include iridium (Ir), ruthenium (Ru), rhodium (Rh), palladium (Pd), platinum (Pt), osmium (Os), and rhenium (Re).

[0088] The organic light-emitting material described above may be a fluorescent material or a phosphorescent material, but is preferably a fluorescent material in order to achieve high color purity. Among them, pyrromethene derivatives can be preferably used because they provide a high fluorescence quantum yield and have better chromaticity durability. More preferably, it is a compound represented by the following general formula (3). That is, it is more preferable that the one of the light-emitting materials (a) and (b) that is not a compound that emits delayed fluorescence (a light-emitting material other than a compound that emits delayed fluorescence) is a compound represented by general formula (3).

[0089]

[0090] In the general formula (3), X is C—R 7 Or N. 1 ~R 9 may be the same or different and are selected from hydrogen, an alkyl group, a cycloalkyl group, a heterocyclic group, an alkenyl group, a cycloalkenyl group, an alkynyl group, a hydroxyl group, a thiol group, an alkoxy group, an alkylthio group, an aryl ether group, an aryl thioether group, an aryl group, a heteroaryl group, a halogen atom, a cyano group, an aldehyde group, a carbonyl group, a carboxyl group, an oxycarbonyl group, a carbamoyl group, an amino group, a nitro group, a silyl group, a siloxanyl group, a boryl group, a phosphine oxide group, and a fused ring or an aliphatic ring formed between adjacent substituents.

[0091] In all of the above groups, hydrogen may be deuterium. This also applies to the compounds or partial structures thereof described below. In the following description, for example, a substituted or unsubstituted aryl group having 6 to 40 carbon atoms refers to an aryl group having a total carbon number of 6 to 40, including the carbon atoms contained in the substituents substituted on the aryl group. The same applies to other substituents that specify the number of carbon atoms.

[0092] In addition, in all of the above groups, the substituent when substituted is preferably an alkyl group, a cycloalkyl group, a heterocyclic group, an alkenyl group, a cycloalkenyl group, an alkynyl group, a hydroxyl group, a thiol group, an alkoxy group, an alkylthio group, an aryl ether group, an aryl thioether group, an aryl group, a heteroaryl group, a halogen, a cyano group, an aldehyde group, a carbonyl group, a carboxyl group, an oxycarbonyl group, a carbamoyl group, an amino group, a nitro group, a silyl group, a siloxanyl group, a boryl group, or a phosphine oxide group, and more preferably a specific substituent that is preferred in the description of each substituent.In addition, these substituents may be further substituted with the above-mentioned substituents.

[0093] The term "unsubstituted" in the context of "substituted or unsubstituted" means that a hydrogen atom or a deuterium atom has been substituted. The same applies to the term "substituted or unsubstituted" in the compounds or partial structures thereof described below.

[0094] Of all the groups mentioned above, the alkyl group refers to a saturated aliphatic hydrocarbon group such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, or a tert-butyl group, which may or may not have a substituent. When substituted, the additional substituent is not particularly limited, and examples thereof include an alkyl group, a halogen, an aryl group, and a heteroaryl group, and this point is also common to the following description. Furthermore, the number of carbon atoms in the alkyl group is not particularly limited, but is preferably in the range of 1 to 20, more preferably 1 to 8, from the viewpoints of ease of availability and cost.

[0095] The cycloalkyl group refers to a saturated alicyclic hydrocarbon group, such as a cyclopropyl group, a cyclohexyl group, a norbornyl group, an adamantyl group, or the like, which may or may not have a substituent. The number of carbon atoms in the alkyl group is not particularly limited, but is preferably in the range of 3 to 20.

[0096] The heterocyclic group refers to an aliphatic ring having atoms other than carbon atoms in the ring, such as a pyran ring, a piperidine ring, or a cyclic amide, which may or may not have a substituent. The number of carbon atoms in the heterocyclic group is not particularly limited, but is preferably in the range of 2 to 20.

[0097] The alkenyl group refers to an unsaturated aliphatic hydrocarbon group containing a double bond, such as a vinyl group, an allyl group, or a butadienyl group, which may or may not have a substituent. The number of carbon atoms in the alkenyl group is not particularly limited, but is preferably in the range of 2 to 20.

[0098] The cycloalkenyl group refers to an unsaturated alicyclic hydrocarbon group containing a double bond, such as a cyclopentenyl group, a cyclopentadienyl group, or a cyclohexenyl group, which may or may not have a substituent. The number of carbon atoms in the cycloalkenyl group is not particularly limited, but is preferably in the range of 3 to 20.

[0099] The alkynyl group refers to an unsaturated aliphatic hydrocarbon group containing a triple bond, such as an ethynyl group, which may or may not have a substituent. The number of carbon atoms in the alkynyl group is not particularly limited, but is preferably in the range of 2 to 20.

[0100] The alkoxy group refers to a functional group in which an aliphatic hydrocarbon group is bonded via an ether bond, such as a methoxy group, an ethoxy group, or a propoxy group, and this aliphatic hydrocarbon group may or may not have a substituent. The number of carbon atoms in the alkoxy group is not particularly limited, but is preferably in the range of 1 to 20.

[0101] An alkylthio group is an alkoxy group in which the oxygen atom of the ether bond is replaced with a sulfur atom. The hydrocarbon group of the alkylthio group may or may not have a substituent. The number of carbon atoms in the alkylthio group is not particularly limited, but is preferably in the range of 1 to 20.

[0102] The aryl ether group refers to a functional group to which an aromatic hydrocarbon group, such as a phenoxy group, is bonded via an ether bond, and the aromatic hydrocarbon group may or may not have a substituent. The number of carbon atoms in the aryl ether group is not particularly limited, but is preferably in the range of 6 to 40.

[0103] An aryl thioether group is an aryl ether group in which the oxygen atom of the ether bond is substituted with a sulfur atom. The aromatic hydrocarbon group in the aryl thioether group may or may not have a substituent. The number of carbon atoms in the aryl thioether group is not particularly limited, but is preferably in the range of 6 to 40.

[0104] The aryl group refers to an aromatic hydrocarbon group such as a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthryl group, an anthracenyl group, a benzophenanthryl group, a benzanthracenyl group, a chrysenyl group, a pyrenyl group, a fluoranthenyl group, a triphenylenyl group, a benzofluoranthenyl group, a dibenzoanthracenyl group, a perylenyl group, or a helicenyl group. Among these, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a phenanthryl group, an anthracenyl group, a pyrenyl group, a fluoranthenyl group, or a triphenylenyl group is preferred. The aryl group may or may not have a substituent. The number of carbon atoms in the aryl group is not particularly limited, but is preferably in the range of 6 to 40, more preferably 6 to 30.

[0105] R 1 ~R 9is a substituted or unsubstituted aryl group, the aryl group is preferably a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a phenanthryl group, or an anthracenyl group, more preferably a phenyl group, a biphenyl group, a terphenyl group, or a naphthyl group, even more preferably a phenyl group, a biphenyl group, or a terphenyl group, and particularly preferably a phenyl group.

[0106] When each of the substituents is further substituted with an aryl group, the aryl group is preferably a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a phenanthryl group, or an anthracenyl group, more preferably a phenyl group, a biphenyl group, a terphenyl group, or a naphthyl group, and particularly preferably a phenyl group.

[0107] Examples of heteroaryl groups include pyridyl, furanyl, thienyl, quinolinyl, isoquinolinyl, pyrazinyl, pyrimidyl, pyridazinyl, triazinyl, naphthyridinyl, cinnolinyl, phthalazinyl, quinoxalinyl, quinazolinyl, benzofuranyl, benzothienyl, indolyl, dibenzofuranyl, dibenzothienyl, carbazolyl, and benzocarbazolyl. It refers to a cyclic aromatic group having one or more atoms other than carbon in the ring, such as a benzoyl group, a carbolinyl group, an indolocarbazolyl group, a benzofurocarbazolyl group, a benzothienocarbazolyl group, a dihydroindenocarbazolyl group, a benzoquinolinyl group, an acridinyl group, a dibenzoacridinyl group, a benzimidazolyl group, an imidazopyridyl group, a benzoxazolyl group, a benzothiazolyl group, or a phenanthrolinyl group. However, a naphthyridinyl group refers to a 1,5-naphthyridinyl group, a 1,6-naphthyridinyl group, a 1,7-naphthyridinyl group, a 1,8-naphthyridinyl group, a 2,6-naphthyridinyl group, or a 2,7-naphthyridinyl group. The heteroaryl group may or may not have a substituent. The number of carbon atoms in the heteroaryl group is not particularly limited, but is preferably in the range of 2 or more and 40 or less, and more preferably 2 or more and 30 or less.

[0108] R 1 ~R 9is a substituted or unsubstituted heteroaryl group, the heteroaryl group is preferably a pyridyl group, a furanyl group, a thienyl group, a quinolinyl group, a pyrimidyl group, a triazinyl group, a benzofuranyl group, a benzothienyl group, an indolyl group, a dibenzofuranyl group, a dibenzothienyl group, a carbazolyl group, a benzimidazolyl group, an imidazopyridyl group, a benzoxazolyl group, a benzothiazolyl group, or a phenanthrolinyl group, more preferably a pyridyl group, a furanyl group, a thienyl group, or a quinolinyl group, and particularly preferably a pyridyl group.

[0109] When each substituent is further substituted with a heteroaryl group, the heteroaryl group is preferably a pyridyl group, a furanyl group, a thienyl group, a quinolinyl group, a pyrimidyl group, a triazinyl group, a benzofuranyl group, a benzothienyl group, an indolyl group, a dibenzofuranyl group, a dibenzothienyl group, a carbazolyl group, a benzimidazolyl group, an imidazopyridyl group, a benzoxazolyl group, a benzothiazolyl group, or a phenanthrolinyl group, more preferably a pyridyl group, a furanyl group, a thienyl group, or a quinolinyl group, and particularly preferably a pyridyl group.

[0110] The term "halogen" refers to an atom selected from fluorine, chlorine, bromine, and iodine. The carbonyl group, carboxyl group, oxycarbonyl group, and carbamoyl group may or may not have a substituent. Examples of the substituent include an alkyl group, a cycloalkyl group, an aryl group, and a heteroaryl group, and these substituents may be further substituted.

[0111] The amino group is a substituted or unsubstituted amino group. In the case of substitution, examples of the substituent include an aryl group, a heteroaryl group, a linear alkyl group, and a branched alkyl group. As the aryl group and the heteroaryl group, a phenyl group, a naphthyl group, a pyridyl group, and a quinolinyl group are preferred. These substituents may be further substituted. The number of carbon atoms is not particularly limited, but is preferably in the range of 2 to 50, more preferably 6 to 40, and particularly preferably 6 to 30.

[0112] The silyl group refers to, for example, alkylsilyl groups such as trimethylsilyl group, triethylsilyl group, tert-butyldimethylsilyl group, propyldimethylsilyl group, and vinyldimethylsilyl group, and arylsilyl groups such as phenyldimethylsilyl group, tert-butyldiphenylsilyl group, triphenylsilyl group, and trinaphthylsilyl group. The substituent on silicon may be further substituted. The number of carbon atoms in the silyl group is not particularly limited, but is preferably in the range of 1 to 30.

[0113] The siloxanyl group refers to a silicon compound group via an ether bond, such as a trimethylsiloxanyl group. The substituent on the silicon may be further substituted. The boryl group refers to a substituted or unsubstituted boryl group. In the case of substitution, examples of the substituent include an aryl group, a heteroaryl group, a linear alkyl group, a branched alkyl group, an aryl ether group, an alkoxy group, and a hydroxyl group. Among these, an aryl group and an aryl ether group are preferred.

[0114] The phosphine oxide group is —P(═O)R 10 R 11 The R of the phosphine oxide group is a group represented by the formula: 10 R 11 is the above-mentioned R １ ~R ９ is selected from the same group as

[0115] In addition, any two adjacent substituents in the general formula (3) (for example, R 1 and R 2 ) may be bonded to each other to form a conjugated or non-conjugated fused ring. The fused ring may contain, in addition to carbon, an element selected from nitrogen, oxygen, sulfur, phosphorus, and silicon. The fused ring may further be fused with another ring.

[0116] The compound represented by general formula (3) exhibits a high fluorescence quantum yield and a small half-width peak of the emission spectrum, and therefore the compound represented by general formula (3) can achieve efficient color conversion and high color purity, and can further improve the durability of chromaticity.

[0117] In addition, X in the general formula (3) is C—R 7 If R 7 is preferably a moderately bulky substituent. 7 When R has an appropriate bulkiness, it is possible to prevent aggregation of molecules, and as a result, the luminous efficiency and durability of the compound represented by general formula (3) are further improved. 7 Examples of the moderately bulky substituents include R 7 The structure:

[0118]

[0119] In general formula (4), r is selected from the group consisting of hydrogen, alkyl groups, cycloalkyl groups, heterocyclic groups, alkenyl groups, cycloalkenyl groups, alkynyl groups, hydroxyl groups, thiol groups, alkoxy groups, alkylthio groups, aryl ether groups, aryl thioether groups, aryl groups, heteroaryl groups, halogens, cyano groups, aldehyde groups, carbonyl groups, carboxyl groups, oxycarbonyl groups, carbamoyl groups, amino groups, nitro groups, silyl groups, siloxanyl groups, boryl groups, and phosphine oxide groups. k is an integer of 1 to 3. When k is 2 or greater, each r may be the same or different.

[0120] In general formula (4), r is preferably a substituted or unsubstituted aryl group. Among such aryl groups, particularly preferred examples include a phenyl group and a naphthyl group. When r is an aryl group, k in general formula (4) is preferably 1 or 2, and from the viewpoint of obtaining a high fluorescence quantum yield, k is more preferably 2. Furthermore, when k is 2 or greater, at least one r is preferably substituted with an alkyl group or an aryl group. In this case, particularly preferred examples of the alkyl group include a methyl group, an ethyl group, and a tert-butyl group. Furthermore, when r is an aryl group, r is preferably a phenyl group or a naphthyl group, and these aryl groups may be further substituted with an alkyl group, a heterocyclic group, an alkenyl group, a hydroxyl group, an alkoxy group, an aryl ether group, an aryl group, a heteroaryl group, a halogen atom, a cyano group, a carboxyl group, an ester group, an oxycarbonyl group, or an alkoxy group.

[0121] Examples of the compound represented by general formula (3) are shown below, but the compound is not limited to these.

[0122]

[0123]

[0124]

[0125]

[0126]

[0127]

[0128]

[0129]

[0130]

[0131]

[0132]

[0133] The compound represented by general formula (3) can be produced by the methods described in, for example, JP-A-8-509471 and JP-A-2000-208262, in which a pyrromethene compound is reacted with a metal salt in the presence of a base to obtain the desired pyrromethene metal complex.

[0134] Furthermore, the compound represented by general formula (3) can be produced by referring to the methods described in J. Org. Chem., vol. 64, No. 21, pp. 7813-7819 (1999), Angew. Chem., Int. Ed. Engl., vol. 36, pp. 1333-1335 (1997), etc. For example, a compound represented by general formula (5) and a compound represented by general formula (6) are heated in 1,2-dichloroethane in the presence of phosphorus oxychloride, and then a compound represented by general formula (7) is reacted in 1,2-dichloroethane in the presence of triethylamine to obtain the compound represented by general formula (3). However, the present invention is not limited to this method. Here, R 1 ~R 9 is the same as described above. J represents a halogen.

[0135]

[0136] Furthermore, when introducing an aryl group or a heteroaryl group, a method of forming a carbon-carbon bond using a coupling reaction between a halogenated derivative and a boronic acid or a boronate ester derivative can be used, but the present invention is not limited to this. Similarly, when introducing an amino group or a carbazolyl group, a method of forming a carbon-nitrogen bond using a coupling reaction between a halogenated derivative and an amine or a carbazole derivative in the presence of a metal catalyst such as palladium can be used, but the present invention is not limited to this.

[0137] The color-converting composition of the present invention may contain an assist dopant such as rubrene in order to increase the efficiency of energy transfer from excitation light to the compound emitting delayed fluorescence. Furthermore, when it is desired to add another emission color in addition to the emission color of the compound emitting delayed fluorescence or the compound represented by general formula (3), the color-converting composition may contain a known emission material such as the above-mentioned organic light-emitting material, an inorganic phosphor, a fluorescent pigment, a fluorescent dye, or a quantum dot.

[0138] Examples of organic light-emitting materials other than the compound represented by general formula (3) are shown below, but the organic light-emitting materials are not particularly limited to these.

[0139]

[0140] (Binder Resin) The binder resin forms a continuous phase and may be any material that is excellent in moldability, transparency, heat resistance, etc. Examples of binder resins include known materials such as photocurable resist materials having reactive vinyl groups, such as acrylic acid-based, methacrylic acid-based, polyvinyl cinnamate-based, and cyclic rubber-based materials, epoxy resins, silicone resins (including organopolysiloxane cured products (crosslinked products) such as silicone rubber and silicone gel), urea resins, fluororesins, polycarbonate resins, acrylic resins, urethane resins, melamine resins, polyvinyl resins, polyamide resins, phenolic resins, polyvinyl alcohol resins, cellulose resins, aliphatic ester resins, aromatic ester resins, aliphatic polyolefin resins, and aromatic polyolefin resins. Furthermore, copolymer resins of these may also be used as the binder resin. By appropriately designing these resins, binder resins useful for the color conversion composition and color conversion sheet according to the present invention can be obtained. Among these resins, thermoplastic resins are more preferred because of the ease of the sheet formation process. Among thermoplastic resins, epoxy resins, silicone resins, acrylic resins, ester resins, olefin resins, or mixtures thereof can be preferably used from the viewpoints of transparency, heat resistance, etc. Furthermore, from the viewpoint of durability, particularly preferred thermoplastic resins are acrylic resins, ester resins, and cycloolefin resins.

[0141] Suitable specific examples of binder resins include those described in WO 2016 / 190283, WO 2017 / 61337, WO 2018 / 43237, WO 2019 / 21813, and WO 2019 / 188019.

[0142] The binder resin may contain additives such as dispersants and leveling agents for stabilizing the coating film, or may contain adhesive aids such as silane coupling agents as modifiers for the color conversion layer surface. The binder resin may also contain inorganic particles such as silica particles and silicone microparticles as agents for inhibiting the precipitation of the color conversion material.

[0143] In the color-converting composition for producing a color-converting sheet according to an embodiment of the present invention, the binder resin preferably contains, as an additional component, a hydrosilylation reaction retarder such as acetylene alcohol to inhibit curing at room temperature and thereby extend the pot life. Furthermore, the binder resin may contain, as necessary, fine particles such as fumed silica, glass powder, and quartz powder, inorganic fillers and pigments such as titanium oxide, zirconia oxide, barium titanate, and zinc oxide, flame retardants, heat-resistant agents, antioxidants, dispersants, solvents, and adhesion promoters such as silane coupling agents and titanium coupling agents, within the scope of the present invention.

[0144] (Solvent) The color-changing composition according to the embodiment of the present invention may contain a solvent. The solvent is not particularly limited as long as it can adjust the viscosity of the resin in a fluid state and does not excessively affect the luminescence and durability of the luminescent material. Examples of such solvents include toluene, methyl ethyl ketone, methyl isobutyl ketone, hexane, acetone, terpineol, Texanol, methyl cellosolve, butyl carbitol, butyl carbitol acetate, and propylene glycol monomethyl ether acetate. Two or more of these solvents may also be mixed and used. Among these solvents, toluene is particularly preferred because it does not affect the deterioration of the compound represented by general formula (1) or general formula (2) and leaves little residual solvent after drying.

[0145] (Other Components) The color-converting composition according to the embodiment of the present invention may contain, in addition to the compound that emits delayed fluorescence (for example, a compound represented by general formula (1) or general formula (2)) and the binder resin described above, other components (additives), such as a light stabilizer, an antioxidant, a processing and heat stabilizer, a light resistance stabilizer such as an ultraviolet absorber, scattering particles, silicone microparticles, and a silane coupling agent.

[0146] Examples of light stabilizers include, but are not limited to, tertiary amines, catechol derivatives, nickel compounds, and complexes or salts with organic acids containing at least one transition metal selected from the group consisting of Sc, V, Mn, Fe, Co, Cu, Y, Zr, Mo, Ag, and lanthanoids. These light stabilizers may be used alone or in combination.

[0147] Examples of the antioxidant include, but are not limited to, phenolic antioxidants such as 2,6-di-tert-butyl-p-cresol and 2,6-di-tert-butyl-4-ethylphenol. These antioxidants may be used alone or in combination.

[0148] Examples of processing and heat stabilizers include, but are not limited to, phosphorus-based stabilizers such as tributyl phosphite, tricyclohexyl phosphite, triethyl phosphine, and diphenylbutyl phosphine. These stabilizers may be used alone or in combination.

[0149] Examples of the light resistance stabilizer include, but are not limited to, benzotriazoles such as 2-(5-methyl-2-hydroxyphenyl)benzotriazole and 2-[2-hydroxy-3,5-bis(α,α-dimethylbenzyl)phenyl]-2H-benzotriazole. These light resistance stabilizers may be used alone or in combination.

[0150] The scattering particles are preferably inorganic particles having a refractive index of 1.7 to 2.8, such as titania, zirconia, alumina, ceria, tin oxide, indium oxide, iron oxide, zinc oxide, aluminum nitride, aluminum, tin, titanium or zirconium sulfide, and titanium or zirconium hydroxide.

[0151] In the color-converting composition according to the embodiment of the present invention, the content of these additives varies depending on the molar absorption coefficient, luminescence quantum yield, and absorption intensity at the excitation wavelength of the compound, as well as the thickness and transmittance of the color-converting sheet to be produced, but is usually 1.0 × 10 -3 The content of these additives is preferably 1.0×10 to 30 parts by weight based on 100 parts by weight of the binder resin. -2 It is more preferable that the amount is 1.0×10 parts by weight or more and 15 parts by weight or less. -1 It is particularly preferable that the amount is from 1 part by weight to 10 parts by weight.

[0152] The amount of solvent remaining after drying in a color conversion layer containing the color conversion composition of the present invention or a cured product thereof is preferably 3.0% by weight or less, more preferably 1.0% by weight or less, and even more preferably 0.5% by weight or less, from the viewpoint of further improving the durability of a color conversion sheet comprising the color conversion layer.

[0153] Furthermore, from the viewpoint of improving the quantum yield of a color conversion sheet having the color conversion layer, the amount of the residual solvent is preferably 0.01% by weight or more, more preferably 0.05% by weight or more, and even more preferably 0.1% by weight or more.

[0154] <Method for Producing Color-Converting Composition> An example of a method for producing the color-converting composition of the present invention is described below. In this method, the binder resin, luminescent material (a), and luminescent material (b) described above, as well as additives, solvents, and the like, are mixed in predetermined amounts. The components are mixed to a predetermined composition, and then homogeneously mixed or kneaded using a stirrer / kneader to obtain a color-converting composition. Examples of stirrers / kneaders include homogenizers, planetary stirrers, three-roller stirrers, ball mills, planetary ball mills, and bead mills. After mixing or dispersing, or during the mixing or dispersing process, degassing is preferably performed under vacuum or reduced pressure conditions. It is also possible to premix certain components or to perform aging or other treatments. The desired solids concentration can also be achieved by removing the solvent using an evaporator.

[0155] <Color Conversion Sheet> The color conversion sheet according to an embodiment of the present invention converts incident light from a light-emitting body such as a light source into light of a different wavelength from the incident light, and is preferably a color conversion sheet containing the binder resin described above and luminescent materials (a) and (b). In the color conversion sheet, at least one of the luminescent materials (a) and (b) is a compound that emits delayed fluorescence. Here, "converting into light of a different wavelength from the incident light" preferably converts the incident light into light of a longer wavelength than the incident light.

[0156] The color conversion sheet according to the embodiment of the present invention preferably includes a color conversion layer that is a layer made of the above-mentioned color conversion composition or a cured product thereof. The cured product of the color conversion composition is preferably included in the color conversion sheet as a layer obtained by curing the color conversion composition (a layer made of the cured product of the color conversion composition). Typical structural examples of the color conversion sheet include the following four, for example.

[0157] Fig. 1 is a schematic cross-sectional view showing a first example of a color conversion sheet according to an embodiment of the present invention. As shown in Fig. 1, this first example color conversion sheet 1A is a single-layer sheet composed of a color conversion layer 11. The color conversion layer 11 is a layer made of the color conversion composition of the present invention or a cured product thereof.

[0158] 2 is a schematic cross-sectional view showing a second example of a color conversion sheet according to an embodiment of the present invention. As shown in FIG. 2, this second example of a color conversion sheet 1B is a laminate of a base layer 10 and a color conversion layer 11. In this structural example of color conversion sheet 1B, the color conversion layer 11 is laminated on the base layer 10.

[0159] 3 is a schematic cross-sectional view showing a third example of a color conversion sheet according to an embodiment of the present invention. As shown in FIG. 3, this third example of a color conversion sheet 1C is a laminate of multiple base material layers 10 and a color conversion layer 11. In this structural example of color conversion sheet 1C, the color conversion layer 11 is sandwiched between multiple base material layers 10.

[0160] 4 is a schematic cross-sectional view showing a fourth example of a color conversion sheet according to an embodiment of the present invention. As shown in FIG. 4, this fourth example color conversion sheet 1D is a laminate of multiple base layers 10, a color conversion layer 11, and multiple barrier films 12. In this structural example of color conversion sheet 1D, the color conversion layer 11 is sandwiched between multiple barrier films 12, and this laminate of the color conversion layer 11 and the multiple barrier films 12 is further sandwiched between multiple base layers 10. That is, color conversion sheet 1D may have a barrier film 12 as shown in FIG. 4 to prevent deterioration of the color conversion layer 11 due to oxygen, moisture, or heat.

[0161] The thickness of the color conversion sheet according to an embodiment of the present invention (hereinafter sometimes abbreviated as the color conversion sheet of the present invention) is preferably 30 μm or more and 300 μm or less. Here, the thickness of the color conversion sheet refers to the combined thickness of all layers included in the color conversion sheet, and refers to the film thickness (average film thickness) measured based on Method A, a thickness measurement method using mechanical scanning, in JIS K7130 (1999) Plastics - Films and Sheets - Thickness Measurement Methods. By making the thickness of the color conversion sheet of the present invention 30 μm or more, the toughness of the color conversion sheet can be improved. Furthermore, by making the thickness of the color conversion sheet of the present invention 300 μm or less, cracking of the color conversion sheet can be suppressed.

[0162] The color conversion sheet of the present invention contains the above-mentioned luminescent material (a) and luminescent material (b) in its color conversion layer. In such a color conversion sheet, it is preferable to increase the overlap between the emission spectrum of the luminescent material (a) and the absorption spectrum of the luminescent material (b) so that the luminescent material (b) efficiently absorbs the light emitted by the luminescent material (a). Therefore, the half-width of the emission spectrum at the emission peak wavelength of the luminescent material (a) (hereinafter referred to as the "peak half-width") is preferably 30 nm or more. Here, by increasing the overlap between the emission spectrum of the luminescent material (a) and the absorption spectrum of the luminescent material (b), it becomes easier to maintain the luminescent intensity of the luminescent material (b), and as a result, the durability of the luminescent material (b) can be improved.

[0163] In order to obtain light emission with high color purity when the color conversion sheet of the present invention is applied to, for example, a display, the peak half width of the light emitting material (a) is preferably 50 nm or less, more preferably 40 nm or less.

[0164] That is, in the color-converting composition contained in the color-converting sheet of the present invention, the peak half-width of the light-emitting material (a) is preferably 30 nm or more and 50 nm or less, and more preferably 30 nm or more and 40 nm or less.

[0165] Furthermore, the color conversion sheet of the present invention may include, for example, one or more color conversion layers. In this case, the color conversion sheet of the present invention is preferably a color conversion sheet in which the luminescent material (a) and the luminescent material (b) are contained in the same layer among one or more color conversion layers. In such a color conversion sheet, the excitation energy of the luminescent material (a) in an excited state is transferred directly to the luminescent material (b) by electron resonance, without being converted into electromagnetic waves. This phenomenon is called fluorescence resonance energy transfer or Förster resonance energy transfer, and is a phenomenon with significantly higher energy transfer efficiency than when the excitation energy of the luminescent material (a) is emitted as light and absorbed by the luminescent material (b). Therefore, the molar ratio of the content of the luminescent material (a) to the content of the luminescent material (b) contained in the same layer is preferably luminescent material (a):luminescent material (b) = 50:1 to 500:1. Furthermore, it is particularly preferable that the luminescent material (a) and the luminescent material (b) are contained in the same layer among one or more color conversion layers, and that the luminescent material (a) and the luminescent material (b) that is not a compound that emits delayed fluorescence (the luminescent material other than the compound that emits delayed fluorescence) is a compound represented by general formula (3).

[0166] Furthermore, of the luminescent material (a) and the luminescent material (b) contained in the color conversion sheet of the present invention, it is preferable that the luminescent material (b) is a compound that emits delayed fluorescence, and where the energy level of the triplet excited state of the luminescent material (a) is T1a and the energy level of the triplet excited state of the luminescent material (b) is T1b, |T1a-T1b|≦0.2 eV. As described above, when the color conversion sheet of the present invention contains the luminescent material (a) and the luminescent material (b) in the same layer, energy transfer can occur between the luminescent material (a) in the triplet excited state and the luminescent material (b) in the ground state. In other words, when the luminescent material (b) in the ground state absorbs the excitation energy of the luminescent material (a) in the triplet excited state, the luminescent material (a) in the triplet excited state is deactivated. Meanwhile, the resulting luminescent material (b) in the triplet excited state is rapidly converted to the luminescent material (b) in the singlet excited state. In this way, the light-emitting material in the triplet excited state, which is a cause of singlet oxygen generation, is less likely to exist, and as a result, the generation of singlet oxygen can be suppressed. In order for the light-emitting material (b) in the ground state to efficiently absorb the excitation energy of the light-emitting material (a) in the triplet excited state, it is preferable that |T1a-T1b|≦0.2 eV, as described above.

[0167] In the present invention, the energy level of the triplet excited state is defined as the value obtained by measuring a phosphorescence spectrum (vertical axis: phosphorescence intensity, horizontal axis: wavelength) at low temperature (77 [K]) using a sample prepared by dissolving a compound to be measured in a solvent, drawing a tangent to the rising edge on the short wavelength side of the phosphorescence spectrum so as to pass through the inflection point, and dividing 1239.85 by the wavelength at the intersection of the tangent and the horizontal axis.

[0168] As a further example, the color conversion sheet of the present invention may include two or more color conversion layers. In this case, the color conversion sheet of the present invention may be a color conversion sheet in which the luminescent material (a) and the luminescent material (b) are contained in different layers. Specific examples of color conversion sheets including such color conversion layers include color conversion sheets including at least the following (A) layer and (B) layer: (A) layer: a layer containing at least the luminescent material (a) and a binder resin; (B) layer: a layer containing at least the luminescent material (b) and a binder resin. These (A) layer and (B) layer may be different color conversion layers among two or more color conversion layers, or may be separate layers within a single color conversion layer.

[0169] In the color conversion sheet including the above-mentioned (A) layer and (B) layer, Förster resonance energy transfer does not occur, and therefore it is preferable that the molar ratio of the luminescent material (a) contained in the (A) layer to the luminescent material (b) contained in the (B) layer is luminescent material (a):luminescent material (b)=5:1 to 100:1.

[0170] It is also preferable that at least one of the (A) layer and the (B) layer contains both a compound that emits delayed fluorescence and a light-emitting material that is not a compound that emits delayed fluorescence. By adopting such a configuration, it is possible to further improve the durability of the light-emitting material that is not a compound that emits delayed fluorescence.

[0171] (Substrate Layer) Examples of the substrate layer (for example, the substrate layer 10 shown in Figures 2 to 4) include glass and resin films. As the resin film, plastic films such as polyethylene terephthalate (PET), polyphenylene sulfide, polycarbonate, polypropylene, and polyimide are preferred. To facilitate peeling of the film, the surface of the substrate layer may be subjected to a release treatment in advance. There are no particular restrictions on the thickness of the substrate layer, but the lower limit is preferably 25 μm or more, and more preferably 38 μm or more. The upper limit is preferably 5000 μm or less, and more preferably 3000 μm or less.

[0172] (Color conversion layer) The color conversion layer (for example, color conversion layer 11 shown in Figures 1 to 4) can be formed by applying the color conversion composition prepared by the method described above to an underlayer such as a base layer or a barrier film, and drying it.

[0173] The thickness of the color conversion layer is not particularly limited, but is preferably 10 μm or more and 1000 μm or less. The lower limit of the thickness of the color conversion layer is more preferably 30 μm or more. The upper limit of the thickness of the color conversion layer is more preferably 200 μm or less, even more preferably 100 μm or less, and particularly preferably 50 μm or less. The film thickness of the color conversion sheet of the present invention refers to the film thickness (average film thickness) measured in accordance with Method A, a thickness measurement method by mechanical scanning, in JIS K7130 (1999) Plastics - Films and Sheets - Thickness Measurement Methods.

[0174] In the color conversion sheet of the present invention, the color conversion layer may be one layer or two or more layers. When the color conversion layer is two or more layers, it is preferable that at least one of the layers contains the compound represented by general formula (1) or general formula (2).

[0175] In addition to the above-mentioned luminescent material (a) and luminescent material (b) (for example, compounds represented by general formula (1) or general formula (2)) and binder resin, the color conversion layer may contain other components (additives), such as a light stabilizer, an antioxidant, a processing and heat stabilizer, a light resistance stabilizer such as an ultraviolet absorber, scattering particles, silicone microparticles, and a silane coupling agent.

[0176] (Barrier Film) A barrier film (for example, barrier film 12 shown in FIG. 4) is used as appropriate when improving the gas barrier properties of the color conversion layer. This barrier film (also referred to as a barrier layer) is preferably one that suppresses the penetration of oxygen, moisture, heat, etc. into the color conversion layer. The color conversion sheet of the present invention may have two or more layers of such barrier films. For example, the color conversion sheet of the present invention may have barrier films on both sides of the color conversion layer, as in the barrier film 12 exemplified in FIG. 4, or may have a barrier film on only one side of the color conversion layer.

[0177] Examples of barrier films having gas barrier properties include inorganic oxides such as silicon oxide, aluminum oxide, titanium oxide, tantalum oxide, zinc oxide, tin oxide, indium oxide, yttrium oxide, and magnesium oxide; inorganic nitrides such as silicon nitride, aluminum nitride, titanium nitride, and silicon carbonitride; metal oxide thin films or metal nitride thin films obtained by adding other elements to these; and films containing various resins such as polyvinylidene chloride, acrylic resins, silicone resins, melamine resins, urethane resins, fluorine-containing resins, and polyvinyl alcohol-based resins such as saponified vinyl acetate. The barrier film may contain two or more of these. Examples of barrier films having moisture barrier properties include films containing various resins such as polyethylene, polypropylene, nylon, polyvinylidene chloride, copolymers of vinylidene chloride and vinyl chloride, copolymers of vinylidene chloride and acrylonitrile, fluorine-containing resins, and polyvinyl alcohol-based resins such as saponified vinyl acetate.

[0178] The color conversion sheet of the present invention may further have an auxiliary layer having a light diffusion layer, an adhesive layer, an anti-reflection function, an anti-glare function, an anti-reflection and anti-glare function, a hard coat function (abrasion resistance function), an anti-static function, an anti-fouling function, an electromagnetic wave shielding function, an infrared ray blocking function, an ultraviolet ray blocking function, a polarizing function, or a color-tuning function, depending on the required functions.

[0179] (Other Films) The color conversion sheet of the present invention may further include a polarizing reflective film, a diffusion sheet, a prism sheet, a wavelength-selective reflective film, etc. Suitable specific examples of the wavelength-selective reflective film include those described in WO 2017 / 164155 and JP 2018-81250 A.

[0180] <Method for manufacturing color conversion sheet> Next, an example of a method for manufacturing a color conversion sheet of the present invention will be described. In this method for manufacturing a color conversion sheet, the color conversion composition prepared by the above-described method is applied to an underlayer such as a base layer or a barrier layer, and then dried. This forms a color conversion layer. When the binder resin contained in the color conversion composition is a thermosetting resin, the color conversion composition may be applied to an underlayer such as a base layer, and then heat-cured to form the color conversion layer. When the binder resin contained in the color conversion composition is a photocurable resin, the color conversion composition may be applied to an underlayer such as a base layer, and then photocured to form the color conversion layer.

[0181] The color-converting composition can be applied using a reverse roll coater, blade coater, comma coater, slit die coater, direct gravure coater, offset gravure coater, kiss coater, natural roll coater, air knife coater, roll blade coater, two-stream coater, rod coater, wire bar coater, applicator, dip coater, curtain coater, spin coater, knife coater, etc. In order to obtain a uniform thickness of the color-converting layer, application using a slit die coater, comma coater or dip coater is preferred.

[0182] The color conversion layer can be dried using a common heating device such as a hot air dryer or an infrared dryer. In this case, the heating temperature is preferably 60 to 200°C, and the heating time is preferably 2 minutes to 4 hours. It is also possible to heat and cure the color conversion layer in stages using a method such as step curing.

[0183] When the color conversion layer is formed by heat curing, a hot air oven or the like can be used as the heating device. The heating conditions for heat curing the color conversion layer can be selected depending on the binder resin. For example, the heating temperature is preferably 100°C to 300°C, and the heating time is preferably 1 minute to 2 hours.

[0184] When forming a color conversion layer by photocuring, it is preferable to irradiate the color conversion layer with high-energy light such as ultraviolet light. The light irradiation conditions for photocuring the color conversion layer can be selected depending on the binder resin. For example, the wavelength of the irradiated light is preferably 200 nm to 500 nm, and the light irradiation dose is preferably 10 mJ / cm. 2 ~10 J / cm 2 It is preferable that:

[0185] After the color conversion layer is formed, the base material layer can be changed as needed. In this case, simple methods include, for example, a method of replacing the base material layer using a hot plate, or a method using a vacuum laminator or a dry film laminator.

[0186] <Light Source Unit> A light source unit according to an embodiment of the present invention (hereinafter sometimes abbreviated as the light source unit of the present invention) includes at least a light source and the above-described color conversion composition or color conversion sheet. The light source included in the light source unit of the present invention is a source of the above-described excitation light. The arrangement of the light source and the color conversion sheet is not particularly limited, and the light source and the color conversion sheet may be closely attached to each other, or a remote phosphor type in which the light source and the color conversion sheet are separated from each other may be used. Furthermore, the light source unit of the present invention may be configured to further include a color filter in order to enhance color purity.

[0187] <Light Source> The light source provided in the light source unit of the present invention can be any light source that emits light in a wavelength range that can be absorbed by the light-emitting material (a) and the light-emitting material (b). In principle, any excitation light source can be used, such as a hot cathode tube, a cold cathode tube, a fluorescent light source such as an inorganic electroluminescence (EL), an organic EL element light source, an LED light source, an incandescent light source, or sunlight. Among these, an LED light source is a preferred light source. For display and lighting applications, a blue LED light source that can emit excitation light in a wavelength range of 430 nm to 500 nm is even more preferred, as it can enhance the color purity of blue light.

[0188] The light source may have one emission peak or two or more emission peaks, but in order to improve color purity, it is preferable that the light source has one emission peak. It is also possible to use a combination of multiple light sources with different emission peaks.

[0189] The light source unit of the present invention is useful for various light sources such as spatial illumination, backlighting, etc. Specifically, the light source unit of the present invention can be used for applications such as displays, lighting devices, interiors, signs, and billboards, and is particularly suitable for use in displays and lighting devices.

[0190] <Display, Lighting Device> A display according to an embodiment of the present invention includes at least the light source unit described above. For example, a display such as a liquid crystal display uses a light source unit having the above-described light source and a color conversion sheet as a backlight unit. Furthermore, a lighting device according to an embodiment of the present invention includes at least the light source unit described above. For example, this lighting device is configured to emit white light by combining a blue LED light source as the light source unit with a color conversion sheet that converts blue light from the blue LED light source into light with a longer wavelength.

[0191] The present invention will be described below with reference to examples, but the present invention is not limited to the following examples. First, the evaluation methods used in the examples and comparative examples will be described.

[0192] <Durability Evaluation> In the durability evaluation, in each example and each comparative example, a light-emitting device equipped with the prepared color conversion sheet and a blue LED element (manufactured by USHIO EPITEX Corporation; model number SMBB450H-1100, emission peak wavelength: 450 nm) was subjected to a current of 30 mA to light up the blue LED element, and the initial emission peak intensity of green light and the emission peak intensity of red light were measured using a spectroradiometer (CS-1000, manufactured by Konica Minolta). The distance between the color conversion sheet and the blue LED element in each light-emitting device was 3 cm. After that, light from the blue LED element was continuously irradiated for 1000 hours in an environment of 50°C, and the emission peak intensity of green light and the emission peak intensity of red light were similarly measured. The obtained emission peak intensities of the green light and red light were compared with the initial emission peak intensities of the green light and red light, and the chromaticity durability of the color conversion sheet was evaluated by calculating the emission intensity maintenance rate for each of the green light and red light.

[0193] <Light-emitting material (a) and light-emitting material (b)> In the following examples and comparative examples, compounds G-1, G-2, G-3, R-1, and R-2 were used as the light-emitting material (a) and the light-emitting material (b). Compounds G-1, G-2, G-3, R-1, and R-2 are the compounds shown below. Of these, compounds G-1, G-2, and compound R-1 are compounds that emit delayed fluorescence.

[0194]

[0195]

[0196] The physical properties of each of the compounds G-1, G-2, G-3, R-1, and R-2 are shown in Table 1.

[0197]

[0198] The triplet excited state energy levels of the compounds G-1, G-2, G-3, R-1, and R-2 were calculated by the following procedure.

[0199] Specifically, the compound to be measured was dissolved in toluene at 1×10 -5The phosphorescence measurement sample was dissolved at a concentration of 1000 mol / L to prepare a phosphorescence measurement sample. The phosphorescence measurement sample placed in a quartz cell was cooled to 77 K, and the phosphorescence spectrum was measured by irradiating the sample with 500 nm light as excitation light. A near-infrared fluorescence spectrophotometer "FluoroMax Plus" manufactured by Horiba, Ltd. was used as the phosphorescence spectrum measurement device. The phosphorescence spectrum was measured with the phosphorescence intensity on the vertical axis and the wavelength on the horizontal axis. The detection wavelength of the phosphorescence spectrum was 510 nm or more and 1000 nm or less. A tangent line was drawn to the rising edge of the short wavelength side of the phosphorescence spectrum, passing through the inflection point. The value obtained by dividing 1239.85 by the wavelength at the intersection of the tangent line and the horizontal axis was determined as the energy level of the target triplet excited state.

[0200] <Resin> In the following examples and comparative examples, polymethyl methacrylate resin "BR-85" (manufactured by Mitsubishi Chemical Corporation, glass transition temperature: 105°C) was used as the binder resin. In addition, polyester resin "Vylon" (registered trademark) 630 (manufactured by Toyobo Co., Ltd.) was used as the resin for the adhesive layer.

[0201] <Scattering Material> In the following examples and comparative examples, titanium dioxide particles "JR-301" (manufactured by Teika Co., Ltd.) were used as scattering materials.

[0202] Example 1 In Example 1, 0.34 parts by weight of compound G-1 as the luminescent material (a), 0.0020 parts by weight of compound R-2 as the luminescent material (b) (molar ratio of luminescent material (a):luminescent material (b) = 163:1), 3 parts by weight of JR-301 as a scattering material, and 300 parts by weight of ethyl acetate as a solvent were mixed with 100 parts by weight of binder resin (BR-85). Thereafter, this mixture was stirred and degassed for 20 minutes at 1000 rpm using a planetary stirring and degassing device "Mazerustar" (registered trademark) KK-400 (manufactured by Kurabo Industries, Ltd.), thereby obtaining a resin composition for producing a color conversion layer (color conversion composition).

[0203] Next, the color-changing composition obtained as described above was applied to a polyester film "Lumirror" (registered trademark) U48 (manufactured by Toray Industries, Inc., thickness 50 μm) using a slit die coater, and then heated and dried for 20 minutes at 120° C. This formed a color-changing layer with an average thickness of 20 μm, and a unit was obtained in which this color-changing layer and polyester film (base layer) were laminated together.

[0204] Next, 100 parts by weight of the resin for the adhesive layer ("Vylon" 630) was mixed with 300 parts by weight of ethyl acetate as a solvent. Thereafter, this solution was stirred and degassed for 20 minutes at 300 rpm using a planetary stirring and degassing device "Mazerustar" KK-400 (manufactured by Kurabo Industries, Ltd.). This yielded a resin composition for the adhesive layer.

[0205] Next, the resin composition for the adhesive layer obtained as described above was applied to a polyester film "Lumilar" (registered trademark) U48 (manufactured by Toray Industries, Inc., thickness 50 μm) using a slit die coater, and then heated and dried for 20 minutes at 120° C. This formed an adhesive layer with an average film thickness of 20 μm, and a unit in which the adhesive layer and polyester film (base layer) were laminated was obtained.

[0206] Next, the above two units were heat-laminated so that the color conversion layer and the adhesive layer were directly laminated together to produce a color conversion sheet with a structure of "base layer / color conversion layer / adhesive layer / base layer." The durability of the obtained color conversion sheet was evaluated using the method described above.

[0207] Example 2 In Example 2, a color conversion sheet was produced and its durability was evaluated in the same manner as in Example 1, except that compound G-2 was used as the luminescent material (a), and the contents of the luminescent material (a) and the luminescent material (b) were set to a molar ratio of luminescent material (a):luminescent material (b) = 161:1.

[0208] Example 3 In Example 3, 0.34 parts by weight of compound G-1 as the luminescent material (a), 3 parts by weight of JR-301 as the scattering material, and 300 parts by weight of ethyl acetate as the solvent were mixed with 100 parts by weight of the binder resin (BR-85). The mixture was then stirred and degassed for 20 minutes at 1000 rpm using a planetary stirring and degassing device "Mazerustar" (registered trademark) KK-400 (manufactured by Kurabo Industries, Ltd.), thereby obtaining a resin composition for producing a green color conversion layer (green color conversion composition).

[0209] Next, the green color conversion composition obtained as described above was applied to a polyester film "Lumirror" (registered trademark) U48 (manufactured by Toray Industries, Inc., thickness 50 μm) using a slit die coater, and then heated and dried for 20 minutes at 120° C. This formed a green color conversion layer with an average thickness of 20 μm, and a unit was obtained in which this green color conversion layer and polyester film (substrate layer) were laminated together.

[0210] Next, 100 parts by weight of the binder resin (BR-85) was mixed with 0.025 parts by weight of compound R-2 as the luminescent material (b) (molar ratio of luminescent material (a):luminescent material (b) = 13:1), 3 parts by weight of JR-301 as a scattering material, and 300 parts by weight of ethyl acetate as a solvent. Thereafter, this mixture was stirred and degassed for 20 minutes at 1000 rpm using a planetary stirring and degassing device "Mazerustar" (registered trademark) KK-400 (manufactured by Kurabo Industries, Ltd.), thereby obtaining a resin composition for producing a red color conversion layer (red color conversion composition).

[0211] Next, the red color conversion composition obtained as described above was applied to a polyester film "Lumirror" (registered trademark) U48 (manufactured by Toray Industries, Inc., thickness 50 μm) using a slit die coater, and then heated and dried for 20 minutes at 120° C. This formed a red color conversion layer with an average thickness of 20 μm, and a laminate of this red color conversion layer and polyester film (substrate layer) was obtained.

[0212] Next, 100 parts by weight of the resin for the adhesive layer ("Vylon" 630) was mixed with 300 parts by weight of ethyl acetate as a solvent. Thereafter, this solution was stirred and degassed for 20 minutes at 300 rpm using a planetary stirring and degassing device "Mazerustar" KK-400 (manufactured by Kurabo Industries, Ltd.). This yielded a resin composition for producing an adhesive layer.

[0213] Next, the resin composition for the adhesive layer obtained as described above was applied onto the red color conversion layer using a slit die coater, and then heated and dried for 20 minutes at 120° C. This formed an adhesive layer with an average thickness of 20 μm, and a unit was obtained in which the adhesive layer, base layer, and red color conversion layer were laminated.

[0214] Next, the two units were heat-laminated so that the green color conversion layer and the adhesive layer were directly laminated together to produce a color conversion sheet with a structure of "substrate layer / green color conversion layer / adhesive layer / red color conversion layer / substrate layer." The durability of the resulting color conversion sheet was evaluated using the method described above.

[0215] Example 4 In Example 4, a color-conversion sheet was produced and its durability was evaluated in the same manner as in Example 3, except that compound G-2 was used as the luminescent material (a), and the contents of the luminescent material (a) and the luminescent material (b) were set to a molar ratio of luminescent material (a):luminescent material (b) = 13:1.

[0216] Example 5 In Example 5, the production of a color conversion sheet and the evaluation of its durability were carried out in the same manner as in Example 1, except that compound G-3 was used as the luminescent material (a) in an amount of 0.9 parts by weight, compound R-1 was used as the luminescent material (b) in an amount of 0.0028 parts by weight, and the molar ratio of luminescent material (a):luminescent material (b) was 165:1.

[0217] Example 6 In Example 6, a color conversion sheet was produced and its durability was evaluated in the same manner as in Example 3, except that compound G-3 was used as the luminescent material (a) in an amount of 0.9 parts by weight, compound R-1 was used as the luminescent material (b) in an amount of 0.030 parts by weight, and the molar ratio of luminescent material (a):luminescent material (b) was 15:1.

[0218] Comparative Example 1 In Comparative Example 1, the preparation of a color conversion sheet and the evaluation of its durability were carried out in the same manner as in Example 1, except that compound G-3 was used as the luminescent material (a), the amount of compound G-3 added was 0.9 parts by weight, and the molar ratio of luminescent material (a):luminescent material (b) was 165:1.

[0219] Comparative Example 2 In Comparative Example 2, the preparation of a color conversion sheet and the evaluation of its durability were carried out in the same manner as in Example 3, except that compound G-3 was used as the luminescent material (a), the amount of compound G-3 added was 0.9 parts by weight, and the molar ratio of luminescent material (a):luminescent material (b) was 15:1.

[0220] The configurations of the color conversion sheets and the results of the durability evaluation in each of Examples 1 to 6 and Comparative Examples 1 and 2 are as shown in Table 2. In Table 2, "molar ratio (a):(b)" means the molar ratio of the luminescent material (a) to the luminescent material (b) contained in the color conversion sheet. "|T1a-T1b|" means the difference (absolute value) between the energy level T1a of the triplet excited state of the luminescent material (a) and the energy level T1b of the triplet excited state of the luminescent material (b). "Maintenance rate of green luminescence intensity" means the result of the durability evaluation of the chromaticity of the luminescent material (a) contained in the color conversion sheet. "Maintenance rate of red luminescence intensity" means the result of the durability evaluation of the chromaticity of the luminescent material (b) contained in the color conversion sheet.

[0221]

[0222] For example, a comparison between Example 1 and Comparative Example 1 shown in Table 2 reveals that the use of a compound that emits delayed fluorescence as the luminescent material (a) improves not only the durability of the luminescent material (a) but also the durability of the luminescent material (b), which is not a compound that emits delayed fluorescence.

[0223] As described above, the color-converting composition, color-converting sheet, light source unit, display and lighting device each including the color-converting composition, color-converting sheet and the light source unit, display and lighting device according to the present invention are suitable for achieving excellent durability of chromaticity.

[0224] 1A, 1B, 1C, 1D Color conversion sheet 10 Base layer 11 Color conversion layer 12 Barrier film

Claims

1. A color conversion sheet comprising a color conversion composition or a cured product thereof that converts incident light into light with a wavelength different from that of the incident light, A binder resin; The following luminescent material (a) and luminescent material (b): Including, At least one of the light-emitting material (a) and the light-emitting material (b) is a compound that emits thermally activated delayed fluorescence, The light-emitting material (a) and the light-emitting material (b) are contained in the same layer. A color conversion sheet. Luminescent material (a): a luminescent material having an emission peak wavelength of 500 nm or more and less than 580 nm Luminescent material (b): a luminescent material having an emission peak wavelength of 580 nm or more and 750 nm or less.

2. The compound that emits thermally activated delayed fluorescence is a compound represented by the following general formula (1) or general formula (2): The color conversion sheet according to claim 1 . 【Chemistry 1】 (Ring Za, ring Zb, and ring Zc are each independently a substituted or unsubstituted aryl ring having 6 to 30 ring carbon atoms, or a substituted or unsubstituted heteroaryl ring having 6 to 30 ring carbon atoms. Z 1 and Z 2 are each independently an oxygen atom, NRa (a nitrogen atom having a substituent Ra), or a sulfur atom. 1 When R is NRa, the substituent R may be bonded to the ring Za or the ring Zb to form a ring. 2 When R is NRa, the substituent R may be bonded to the ring Z or the ring Zc to form a ring. E is a boron atom, a phosphorus atom, SiR (a silicon atom having a substituent R) or P=O. 1 and E 2 each independently represents BRa (a boron atom having a substituent Ra), PRa (a phosphorus atom having a substituent Ra), or SiRa 2 (a silicon atom having two substituents Ra), C=O, P(=O)Ra 2 (phosphine oxide having two substituents Ra) or P(=S)Ra 2 (phosphine sulfide having two substituents Ra), S(=O) or S(=O) 2 It is. 1 is BRa, PRa, SiRa 2 , P(=O)Ra 2 Or P(=S)Ra 2 When the substituent Ra is represented by the formula (I), the substituent Ra may be bonded to the ring Za or the ring Zb to form a ring. 2 is BRa, PRa, SiRa 2 , P(=O)Ra 2 Or P(=S)Ra 2 In the case where R a is a substituted or unsubstituted aryl group, R a may be bonded to the ring Z a or the ring Z c to form a ring. Each R a is independently a substituted or unsubstituted aryl group, a substituted or unsubstituted heteroaryl group, or a substituted or unsubstituted alkyl group.

3. The compound emitting thermally activated delayed fluorescence is a compound represented by the general formula (1), in which E in the general formula (1) is a boron atom, and Z 1 and Z 2 are each independently NRa, or the compound emitting thermally activated delayed fluorescence is a compound represented by the general formula (2), wherein E 1 and E 2 are each independently BRa; 3. The color conversion sheet according to claim 2.

4. The light-emitting material (a) and the light-emitting material (b) that is not a compound that emits thermally activated delayed fluorescence is a compound represented by the following general formula (3): The color conversion sheet according to claim 1 . 【Chemistry 2】 (X is C-R 7 Or N. 1 ~R 9 may be the same or different, and are selected from hydrogen, an alkyl group, a cycloalkyl group, a heterocyclic group, an alkenyl group, a cycloalkenyl group, an alkynyl group, a hydroxyl group, a thiol group, an alkoxy group, an alkylthio group, an aryl ether group, an aryl thioether group, an aryl group, a heteroaryl group, a halogen, a cyano group, an aldehyde group, a carbonyl group, a carboxyl group, an oxycarbonyl group, a carbamoyl group, an amino group, a nitro group, a silyl group, a siloxanyl group, a boryl group, a phosphine oxide group, and a fused ring and an aliphatic ring formed between adjacent substituents.

5. The light-emitting material (a) is a compound that emits the thermally activated delayed fluorescence.

5. The color conversion sheet according to claim 1,

6. The half width of the emission spectrum at the emission peak wavelength of the light-emitting material (a) is 30 nm or more and 40 nm or less.

5. The color conversion sheet according to claim 1,

7. the molar ratio of the light-emitting material (a) to the light-emitting material (b) contained in the same layer is light-emitting material (a):light-emitting material (b)=50:1 to 500:1; 5. The color conversion sheet according to claim 1,

8. The light-emitting material (b) is a compound that emits the thermally activated delayed fluorescence, and the energy level of the triplet excited state of the light-emitting material (a) is T 1 a, and the energy level of the triplet excited state of the light-emitting material (b) is T 1 b, |T 1 a-T 1 b|≦0.2 eV; 5. The color conversion sheet according to claim 1,

9. A light source; A color conversion sheet according to any one of claims 1 to 4, A light source unit comprising:

10. The light source unit according to claim 9, A display characterized by:

11. The light source unit according to claim 9, A lighting device characterized by:

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