Upconversion material, adhesive sheet, sheet for temporarily fixing electronic component, and method for processing electronic component using sheet for temporarily fixing electronic component

Abstract

Provided are: an upconversion material having a larger maximum wavelength (for example, 460 nm or more) larger than an adherend and an adhesive sheet (for example, a base material of the adhesive sheet); and an adhesive sheet in which the effects of an adherend and other components are suppressed and the designed adhesiveness can be exhibited. An upconversion material according to an embodiment of the present invention includes: a sensitizing component capable of absorbing light in a first wavelength range λ1; and a light-emitting component capable of emitting light in a second wavelength range λ2 shorter than the first wavelength range λ1. The sensitizing component includes a condensed polycyclic compound having a structure (a), a structure (b), a structure (c), or a structure (d).

Description

Upconversion material, adhesive sheet, electronic component temporary fixing sheet, and method for treating electronic components using said electronic component temporary fixing sheet

[0001] The present invention relates to an upconversion material and a pressure-sensitive adhesive sheet. More specifically, the present invention relates to a pressure-sensitive adhesive sheet used in processing electronic components (e.g., a sheet for temporarily fixing electronic components). The present invention also relates to a method for processing electronic components using the sheet for temporarily fixing electronic components.

[0002] Photon upconversion (hereinafter sometimes simply referred to as "upconversion") technology, which converts low-energy light into high-energy light, is expected to be applied to various fields such as solar cells or photovoltaic power generation, photocatalysis, bioimaging, optical equipment, etc. A known upconversion luminescence technology in organic materials utilizes triplet-triplet annihilation (TTA), which occurs when triplet-state molecules collide with each other.

[0003] Pressure-sensitive adhesive sheets are widely used for the purposes of protecting the surface of an adherend and fixing it. For example, when used in a processing step for electronic components, the pressure-sensitive adhesive sheet can be used to hold the electronic components during the processing step and properly protect the surface of the electronic components. Pressure-sensitive adhesive sheets used in the processing step for electronic components are required to have adhesive strength sufficient to properly hold the electronic components. On the other hand, since the pressure-sensitive adhesive sheet is to be peeled off from the electronic components after processing, it is required that the sheet can be peeled off with light force without leaving any adhesive residue. As such a pressure-sensitive adhesive sheet, a pressure-sensitive adhesive sheet using an active energy ray-curable pressure-sensitive adhesive composition in the pressure-sensitive adhesive layer has been proposed.

[0004] Japanese Patent Application Laid-Open No. 2021-31594

[0005] However, depending on the type of adherend and other components of the pressure-sensitive adhesive sheet (e.g., substrate), the pressure-sensitive adhesive may not be able to exert the desired adhesive strength. As a result, the pressure-sensitive adhesive may not be able to sufficiently hold the adherend, or problems such as adhesive residue on the adherend or damage may occur. Furthermore, in order to further utilize the properties of the photocurable pressure-sensitive adhesive composition, a light-emitting material having an emission wavelength longer than the maximum absorption wavelength of the adherend and pressure-sensitive adhesive sheet (e.g., substrate of the pressure-sensitive adhesive sheet) is required as an upconversion material.

[0006] The present invention has been made to solve the above-mentioned conventional problems, and its object is to provide an upconversion material having an emission wavelength longer (e.g., 460 nm or longer) than the maximum absorption wavelength of the adherend and the pressure-sensitive adhesive sheet (e.g., the substrate of the pressure-sensitive adhesive sheet), and to provide a pressure-sensitive adhesive sheet that is capable of exerting the designed adhesive strength while suppressing the influence of the adherend and other components.

[0007] 1. An upconversion material according to an embodiment of the present invention includes a sensitizer component capable of absorbing light in a first wavelength region λ1 and a light-emitting component capable of emitting light in a second wavelength region λ2 having a wavelength shorter than that of the first wavelength region λ1, wherein the sensitizer component includes a fused polycyclic compound having a structure (a), a structure (b), a structure (c), or a structure (d): (wherein R represents a substituent other than a hydrogen atom). 2. In the upconversion material described in 1 above, the sensitizing component may be a compound represented by the following formula (A), formula (B), formula (C), or formula (D): (In the formula, R １ represents a hydrogen atom or one of the following substituents: (In the formula, R ３０ ~R ６３ each independently represents a hydrogen atom or any of the following substituents: R ２ ~R ２９ each independently represents a hydrogen atom or any of the following substituents: 3. In the upconversion material according to 1 or 2 above, the sensitizing component may be any of the following compounds: 4. In the upconversion material according to any one of 1 to 3 above, the light-emitting component may have any of the following structures: 5. In the upconversion material according to any one of 1 to 4 above, the light-emitting component may be a compound represented by the following formula: (In the formula, R ６４ ~R ８１ each independently represents a hydrogen atom or one of the following substituents: 6. A pressure-sensitive adhesive sheet according to an embodiment of the present invention comprises: a wavelength conversion layer that converts light in a first wavelength region λ1 into light in a second wavelength region λ2 that has a shorter wavelength than the first wavelength region λ1; and a pressure-sensitive adhesive layer that is disposed on one side of the wavelength conversion layer and changes its adhesive strength by absorbing light in the second wavelength region λ2; and a hardness E of the pressure-sensitive adhesive layer measured by a nanoindentation method before absorbing light in the second wavelength region λ2. １ is 0.01 MPa or more, and the hardness E of the pressure-sensitive adhesive layer after absorbing light in the second wavelength region λ2 as measured by a nanoindentation method ２ is the hardness E measured by the nanoindentation method １ 7. In the pressure-sensitive adhesive sheet according to the above item 6, the hardness E of the pressure-sensitive adhesive layer measured by a nanoindentation method is 5 times or more. ２ is the hardness E of the pressure-sensitive adhesive layer measured by nanoindentation method. １, and the wavelength conversion layer may be 30 times or more and 1500 times or less. 8. In the pressure-sensitive adhesive sheet described in 6 or 7 above, the wavelength conversion layer may contain a sensitizing component capable of absorbing light in a first wavelength region λ1 and a light-emitting component capable of emitting light in a second wavelength region λ2 that has a shorter wavelength than the first wavelength region λ1. 9. In the pressure-sensitive adhesive sheet described in 6 or 7 above, the wavelength conversion layer may contain inorganic upconversion particles. 10. The pressure-sensitive adhesive sheet described in any one of 6 to 9 above may further include a substrate disposed on the opposite side of the wavelength conversion layer from the pressure-sensitive adhesive layer, and the transmittance of the substrate for light in the first wavelength region λ1 may be 50% or more and the transmittance of the substrate for light in the second wavelength region λ2 may be 10% or less. 11. In the pressure-sensitive adhesive sheet described in any one of items 6 to 10 above, the 180° peel strength of the pressure-sensitive adhesive layer after absorbing light in the second wavelength region λ2 may be 70% or less, where the 180° peel strength of the pressure-sensitive adhesive layer before absorbing light in the second wavelength region λ2 is taken as 100%. 12. A pressure-sensitive adhesive sheet according to another embodiment of the present invention comprises a pressure-sensitive adhesive layer including: a wavelength converting material that converts light in a first wavelength region λ1 into light in a second wavelength region λ2 that has a shorter wavelength than the first wavelength region λ1; and a pressure-sensitive adhesive whose adhesive strength changes upon absorbing light in the second wavelength region λ2, and wherein the hardness E of the pressure-sensitive adhesive layer before absorbing light in the second wavelength region λ2 is measured by a nanoindentation method. ３ is 0.01 MPa or more, and the hardness E of the pressure-sensitive adhesive layer measured by a nanoindentation method after absorbing light in the second wavelength region λ2 ４ The hardness E of the pressure-sensitive adhesive layer measured by the nanoindentation method ３ 13. In the pressure-sensitive adhesive sheet according to the above 12, the wavelength converting material may be dispersed in the pressure-sensitive adhesive. 14. In the pressure-sensitive adhesive sheet according to the above 12 or 13, the wavelength converting material may be a sensitizing component capable of absorbing light in a first wavelength region λ1 and a light-emitting component capable of emitting light in a second wavelength region λ2 having a wavelength shorter than the first wavelength region λ1. 15. In the pressure-sensitive adhesive sheet according to any one of the above 12 to 14, the hardness E of the pressure-sensitive adhesive layer measured by a nanoindentation method４ is the hardness E of the pressure-sensitive adhesive layer measured by nanoindentation method. ３ The optical transmittance may be 30 times or more and 1,500 times or less relative to the optical transmittance of the pressure-sensitive adhesive layer. 16. The pressure-sensitive adhesive sheet according to any one of 12 to 15 above may further include a substrate, and the substrate may have a transmittance of 50% or more for light in the first wavelength region λ1, and a transmittance of 10% or less for light in the second wavelength region λ2. 17. In the pressure-sensitive adhesive sheet according to any one of 12 to 16 above, the 180° peel strength of the pressure-sensitive adhesive layer after absorbing light in the second wavelength region λ2 may be 95% or less, where the 180° peel strength of the pressure-sensitive adhesive layer before absorbing light in the second wavelength region λ2 is taken as 100%. 18. In another aspect of the present invention, there is provided a sheet for temporary fixing of electronic components. This pressure-sensitive adhesive sheet for temporary fixing of electronic components includes the pressure-sensitive adhesive sheet according to any one of 6 to 12 above. 19. In yet another aspect of the present invention, there is provided a method for treating electronic components. This method for treating electronic components includes the steps of attaching an electronic component to the pressure-sensitive adhesive layer of the electronic component temporary fixing sheet described in 17 above, performing a predetermined treatment on the electronic component attached to the pressure-sensitive adhesive layer, and irradiating the wavelength conversion layer of the electronic component temporary fixing sheet with light in a first wavelength region λ1 to cause it to emit light in a second wavelength region λ2, and peeling the electronic component that has been subjected to the predetermined treatment from the pressure-sensitive adhesive layer that has absorbed the light in the second wavelength region λ2. 20. In yet another embodiment of the present invention, there is provided a sheet for temporary fixing of electronic components. This electronic component temporary fixing sheet includes the pressure-sensitive adhesive sheet described in any one of 13 to 17 above. 21. In yet another aspect of the present invention, there is provided a method for treating electronic components. This method for processing electronic components may include the steps of: attaching an electronic component to the adhesive layer provided on the sheet for temporarily fixing electronic components described in 18 above; performing a predetermined treatment on the electronic component attached to the adhesive layer; and irradiating the adhesive layer with light in a first wavelength region λ1 to emit light in a second wavelength region λ2, and peeling the electronic component that has been subjected to the predetermined treatment from the adhesive layer that has absorbed the light in the second wavelength region λ2.

[0008] According to an embodiment of the present invention, it is possible to provide an upconversion material having an emission wavelength longer (e.g., 460 nm or longer) than the maximum absorption wavelength of an adherend, a pressure-sensitive adhesive sheet (e.g., a substrate of a pressure-sensitive adhesive sheet), etc. Furthermore, according to an embodiment of the present invention, it is possible to provide a pressure-sensitive adhesive sheet that is capable of exerting a designed adhesive strength by suppressing the influence of the adherend and other components.

[0009] FIG. 1 is a conceptual diagram of energy levels illustrating the mechanism of upconversion. FIG. 2 is a schematic cross-sectional view of a pressure-sensitive adhesive sheet according to an embodiment of the present invention. FIG. 3 is a schematic cross-sectional view of a pressure-sensitive adhesive sheet according to another embodiment of the present invention. FIG. 4 is an emission spectrum diagram of a wavelength conversion film containing UC dye 1. FIG. 5 is an emission spectrum diagram of a wavelength conversion film containing UC dye 2. FIG. 6 is an emission spectrum diagram of a wavelength conversion film containing UC dye 3. FIG. 7 is an emission spectrum diagram of a wavelength conversion film containing UC dye 4. FIG. 8 is an emission spectrum diagram of a wavelength conversion film containing UC dye 5. FIG. 9 is an emission spectrum diagram of a wavelength conversion film containing UC dye 6. FIG. 10 is a spectral diagram (absorption spectrum, fluorescence spectrum, and phosphorescence spectrum) of UC dye 1. FIG. 11 is a spectral diagram (absorption spectrum, fluorescence spectrum, and phosphorescence spectrum) of UC dye 2. FIG. 12 is a spectral diagram (absorption spectrum, fluorescence spectrum, and phosphorescence spectrum) of UC dye 3. FIG. 13 is a spectral diagram (absorption spectrum, fluorescence spectrum, and phosphorescence spectrum) of UC dye 4. FIG. 14 is a spectral diagram (absorption spectrum, fluorescence spectrum, and phosphorescence spectrum) of UC dye 5. 1 is a spectrum diagram (absorption spectrum, fluorescence spectrum, and phosphorescence spectrum) of UC dye 6. FIG. 2 is a transmission spectrum diagram of a wavelength conversion film containing UC dye 4.

[0010] A. Upconversion Material The upconversion material of an embodiment of the present invention includes a sensitizer component (hereinafter simply referred to as "sensitizer component") capable of absorbing light in a first wavelength region λ1, and a light-emitting component (hereinafter simply referred to as "light-emitting component") capable of emitting light in a second wavelength region λ2, which has a shorter wavelength than the first wavelength region λ1. The mechanism of photon upconversion utilizing triplet-triplet annihilation (TTA), which occurs when triplet-state molecules collide with each other, will be described with reference to FIG. 1 . First, the sensitizer component (donor) absorbs incident light and converts it to an excited singlet state S Ｄ Intersystem crossing from Ｄ Then, triplet-triplet energy transfer (TTET) occurs from the sensitizer (donor) to the light-emitting component (acceptor), resulting in the excited triplet state T Ａ is generated. Then, the excited triplet state T Ａ The triplet-triplet annihilation (TTA) occurs when the light-emitting components (acceptors) in the luminescent state (S) diffuse and collide with each other. As a result, the light-emitting components (acceptors) are transported to the high excited singlet energy state S Ａ is generated. This high excited singlet energy state S Ａ Upconversion light (light having greater energy than the excitation light) is emitted from the sensitizer. The sensitizer component contained in the upconversion material of an embodiment of the present invention is a fused polycyclic compound having the following structure (a), structure (b), structure (c), or structure (d). Such fused polycyclic compounds may have a maximum absorption wavelength in a longer wavelength region (e.g., 460 nm or longer). By using these fused polycyclic compounds as the sensitizer, an upconversion material capable of utilizing light of longer wavelengths can be obtained. (wherein R represents a substituent other than a hydrogen atom).

[0011] In the upconversion material, the sensitizing component and the light-emitting component can be used in any appropriate blend ratio. The blend ratio of the sensitizing component to the light-emitting component (sensitizing component:light-emitting component) (molar ratio) is preferably 1:10 to 1:7000, more preferably 1:25 to 1:3000, even more preferably 1:30 to 1:200, and particularly preferably 1:35 to 1:100. When the blend ratio of the sensitizing component to the light-emitting component is within this range, triplet excitons generated from the sensitizing component can efficiently transfer to the light-emitting component, minimizing deactivation between the light-emitting components and achieving good triplet-triplet annihilation.

[0012] A-1. Sensitizing Component As the sensitizing component, a fused polycyclic compound having the structure (a), structure (b), structure (c), or structure (d) is used. The sensitizing component may contain only one of these fused polycyclic compounds, or may use two or more of them in combination.

[0013] The fused polycyclic compound having structure (a) may be any suitable fused polycyclic compound as long as it contains structure (a). Specific examples of fused polycyclic compounds having structure (a) include fused polycyclic compounds represented by the following formula (A) (hereinafter also referred to as fused polycyclic compound A). The use of fused polycyclic compound A can provide an upconversion material having a maximum absorption wavelength of approximately 510 nm. The maximum absorption wavelength of the fused polycyclic compound can be measured by any suitable method. For example, the maximum absorption wavelength can be obtained by measuring the transmission spectrum, and specifically, it can be measured by the method described in the examples of this specification. (In formula (A), R １ represents a hydrogen atom or one of the following substituents: (In the formula, R ３０ ~R ６３ each independently represents a hydrogen atom or any of the following substituents: .

[0014] The condensed polycyclic compound A is more preferably R １ is the following substituent: R １ If this substituent is present, the energy level difference between the excited singlet state and the excited triplet state of the fused polycyclic compound A becomes small, and the wavelength conversion width can be increased.

[0015] Specific examples of the condensed polycyclic compound A include the following compounds.

[0016] The fused polycyclic compound having structure (b) may be any suitable fused polycyclic compound as long as it contains structure (b). Specific examples of the fused polycyclic compound having structure (b) include fused polycyclic compounds represented by the following general formula (B) (hereinafter, also referred to as fused polycyclic compound B). Use of fused polycyclic compound B can provide an upconversion material with a maximum absorption wavelength of approximately 490 nm. (In formula (B), R ２ ~R ８ each independently represents a hydrogen atom or any of the following substituents:

[0017] The condensed polycyclic compound B is more preferably R ３ and R ６ is a tert-butyl group, and R ２ , R ４ , R ５ , R ７ , R ８ is a hydrogen atom. With such a structure, the stability of the fused polycyclic compound B is improved, the energy level difference between the excited singlet state and the excited triplet state is reduced, and the wavelength conversion width can be increased.

[0018] Specific examples of the condensed polycyclic compound B include the following compounds.

[0019] The fused polycyclic compound having structure (c) may be any suitable fused polycyclic compound as long as it contains structure (c). Specific examples of fused polycyclic compounds having structure (c) include fused polycyclic compounds represented by the following general formula (C) (hereinafter, also referred to as fused polycyclic compound C). Use of fused polycyclic compound C can provide an upconversion material with a maximum absorption wavelength of approximately 530 nm. (In formula (C), R ９ ~R ２２ each independently represents a hydrogen atom or any of the following substituents: .

[0020] The condensed polycyclic compound C is more preferably R １１ and R １４ is a tert-butyl group, and R １７ and R ２０ is the following substituent, and R ９ , R １０ , R １２ , R １３ , R １５ , R １６ , R １８ , R １９ , R ２１ , R ２２ is a hydrogen atom. In such a fused polycyclic compound C, the difference in energy level between the excited singlet state and the excited triplet state becomes small, and the wavelength conversion width can be increased.

[0021] Specific examples of the condensed polycyclic compound C include the following compounds.

[0022] The fused polycyclic compound having structure (d) may be any suitable fused polycyclic compound as long as it contains structure (d). Specific examples of the fused polycyclic compound having structure (d) include fused polycyclic compounds represented by the following general formula (D) (hereinafter, also referred to as fused polycyclic compound D). Use of fused polycyclic compound D can provide an upconversion material with a maximum absorption wavelength of approximately 520 nm. (In formula (D), R ２３ ~R ２９ each independently represents a hydrogen atom or any of the following substituents: .

[0023] The condensed polycyclic compound D is more preferably R ２５ and R ２８ is a tert-butyl group, and R ２３ , R ２４ , R ２６ , R ２７ , and R ２９ is a hydrogen atom. If the fused polycyclic compound D has such a structure, the difference in energy level between the excited singlet state and the excited triplet state becomes small, and the wavelength conversion width can be increased.

[0024] Specific examples of the condensed polycyclic compound D include the following compounds.

[0025] The fused polycyclic compound having the structure (a), the structure (b), the structure (c), or the structure (d) can be synthesized by any suitable method. For example, it can be synthesized by the method described in the examples of this specification. The synthesis method will be described below with specific examples.

[0026] The fused polycyclic compound having the structure (a) can be obtained, for example, by the following synthetic procedure.

[0027] Specifically, a fused polycyclic compound (A) can be obtained by reacting any suitable compound having structure (a) in which a halogen atom is bonded to a position where a substituent is to be introduced with a compound having any substituent in the presence of any catalyst under any suitable conditions. In the example shown above, fused polycyclic compound A is obtained by reacting 3,7,11-tribromoquinolino[3,2,1-de]acridine-5,9-dione (DiKTPABr), a compound having structure (a), with 3,6-di-tert-butyl-9H-carbazole (Di-tert-butyl-CBz), a compound having a specific substituent.

[0028] The fused polycyclic compound having the structure (b) can be obtained, for example, by the following synthetic procedure.

[0029] Specifically, a benzene (e.g., 3,4,5-pentafluoro-6-iodobenzene) having a halogen atom (1) bonded to one substitution position and halogen atoms different from the halogen atom (1) bonded to five substitution positions is reacted with a carbazole compound to obtain a compound having the structure (b). This compound and any suitable compound containing a boron element (e.g., boron tribromide (BBr ３ )) in the presence of any catalyst under any suitable conditions to obtain the fused polycyclic compound B.

[0030] The fused polycyclic compound having the structure (c) can be obtained, for example, by the following synthetic procedure.

[0031] Specifically, benzene having three different halogen atoms bonded thereto (for example, 1-bromo-2-chloro-3-fluorobenzene) and nitrogen-containing carbazole compounds (for example, N ３ , N ３ , N ６ , N ６ -tetraphenyl-9H-carbazole-3,6-diamine) to obtain intermediate c1. The obtained intermediate c1 is reacted with a carbazole compound having a predetermined substituent (for example, the carbazole compound c in the illustrated example) to obtain intermediate c2. Next, intermediate c2 is reacted with any suitable compound containing boron element (for example, boron tribromide (BBr ３ )) with the condensed polycyclic compound C can be obtained.

[0032] The fused polycyclic compound having the structure (d) can be obtained, for example, by the following synthetic procedure.

[0033] Specifically, benzene having a halogen element (1) attached to one substitution position and halogen elements different from the halogen element (1) attached to both sides of the position substituted with the halogen element (1) is reacted with 1,4-benzenedithiol to obtain intermediate d1. Next, intermediate d1 is reacted with a carbazole compound having a predetermined substituent (e.g., 3,6-di-tert-butylcarbazole) to obtain intermediate d2. Next, intermediate d2 is reacted with any suitable compound containing a boron element (e.g., boron tribromide (BBr ３ )) to give the fused polycyclic compound D.

[0034] A-2. Light-Emitting Component In an upconversion material, the sensitizing component can determine the absorption wavelength, and the light-emitting component can determine the emission wavelength. As a result, light irradiated at a wavelength within the absorption wavelength range can be converted into light with a maximum emission wavelength. As the light-emitting component, any suitable compound can be used that can emit light in a second wavelength region λ2 that is shorter in wavelength than the first wavelength region λ1 that can be absorbed by the sensitizing component. Only one light-emitting component may be used, or two or more light-emitting components may be used in combination.

[0035] The light-emitting component used in combination with the sensitizing component having the above structures (a) to (d) may be any appropriate compound that can have an appropriate energy level relationship with the sensitizing component. Examples include compounds having the following structures (e) to (g). Using these compounds as light-emitting components in combination with the sensitizing components having structures (a) to (d) can achieve more efficient upconversion. Using light-emitting component (e) can produce an upconversion material with a maximum emission wavelength of approximately 375 nm. Using light-emitting component (f) can produce an upconversion material with a maximum emission wavelength of approximately 380 nm. Using light-emitting component (g) can produce an upconversion material with a maximum emission wavelength of approximately 385 nm. The maximum emission wavelength of the light-emitting component can be measured by any appropriate method. For example, it can be measured by a photoluminescence method, specifically, it can be measured using an absolute PL quantum yield measurement device (e.g., Hamamatsu Photonics, product name "Quantaurus-QY").

[0036] Specific examples of compounds having the structure (e), (f), or (g) include the following compounds (E1) to (E3), (F1) to (F3), and (G1) to (G2). (In the formula, R ６４ ~R ８１ each independently represents one of the following substituents:

[0037] The following compounds are preferably used as the light-emitting component. Use of such compounds can suppress energy loss during wavelength conversion and enable more efficient energy transfer between the sensitizing component and the light-emitting component. In one embodiment, it is preferable to use, as the sensitizing component, a combination of the above-mentioned fused polycyclic compound A and the light-emitting component shown below. Such a combination of the sensitizing component and the light-emitting component can further suppress energy loss and further improve luminous efficiency.

[0038] The luminescent component can be obtained by any suitable method. For example, it can be synthesized by the method described in the paper by Yaxiong Wei et al. (CCS Chemistry, Volume 4, Issue 12, 3852-3863). Alternatively, commercially available compounds may be used. For example, compounds having the structures (f) and (g) above are sold by Tokyo Chemical Industry Co., Ltd.

[0039] The upconversion material may contain any other appropriate components in addition to the sensitizing component and the light-emitting component. Examples of the other components include a dye degradation inhibitor, an antioxidant, a scatterer, an oxidizing agent, and a reducing agent. The other components may be used in any appropriate amount. Only one type of the other components may be used, or two or more types may be used in combination.

[0040] A-4. Method for Producing Upconversion Material The upconversion material of the present embodiment can be produced by any suitable method. For example, a liquid upconversion material can be obtained by stirring and mixing the sensitizing component, the light-emitting component, any suitable solvent, and any suitable other components.

[0041] Any appropriate solvent can be used as the solvent. For example, an organic solvent, water, etc. can be used. Specific examples of organic solvents include nitrile-based solvents such as acetonitrile and benzonitrile; halogen-based solvents such as chloroform, dichloromethane, 1,2-dichloroethane, 1,1,2-trichloroethane, chlorobenzene, and o-dichlorobenzene; ether-based solvents such as tetrahydrofuran and dioxane; aromatic hydrocarbon-based solvents such as benzene, toluene, and xylene; aliphatic hydrocarbon-based solvents such as cyclohexane, methylcyclohexane, n-pentane, n-hexane, n-heptane, n-octane, n-nonane, and n-decane; ketone-based solvents such as acetone, methyl ethyl ketone, and cyclohexanone; ethyl acetate, butyl acetate, ethyl cellosolve, etc. Examples of suitable solvents include ester-based solvents such as rube acetate; polyhydric alcohols and derivatives thereof such as ethylene glycol, ethylene glycol monobutyl ether, ethylene glycol monoethyl ether, ethylene glycol monomethyl ether, dimethoxyethane, propylene glycol, diethoxymethane, triethylene glycol monoethyl ether, glycerin, and 1,2-hexanediol; alcohol-based solvents such as methanol, ethanol, propanol, isopropanol, and cyclohexanol; sulfoxide-based solvents such as dimethyl sulfoxide; and amide-based solvents such as N-methyl-2-pyrrolidone and N,N-dimethylformamide.

[0042] A solid upconversion material such as an upconversion film can be manufactured by any suitable method. For example, the upconversion film can be obtained by a manufacturing method including: preparing an emulsion from a solution or dispersion containing a sensitizing component and a light-emitting component (hereinafter, sometimes collectively referred to as a “dye solution, etc.”) and an aqueous solution containing a water-soluble resin; applying the emulsion to a substrate to form a coating; and drying the coating.

[0043] A solution or dispersion containing a sensitizing component and a light-emitting component can be prepared by any appropriate method. Specifically, it can be obtained by stirring and mixing the sensitizing component, the light-emitting component, any appropriate other components, and any appropriate organic solvent. Any appropriate organic solvent can be used. For example, a volatile organic solvent can be used. Specific examples include ethers such as tetrahydrofuran; halogenated hydrocarbons such as chloroform and dichloromethane; and toluene. The organic solvent is preferably an ether, and more preferably tetrahydrofuran. Only one organic solvent may be used, or two or more organic solvents may be used in combination. The concentrations of the sensitizing component and the light-emitting component in the dye solution or the like can be adjusted to any appropriate value. For example, the sensitizing component concentration can be, for example, 0.001 mM to 1 mM, and the light-emitting component concentration can be, for example, 1 mM to 50 mM.

[0044] The aqueous solution containing the water-soluble resin can be prepared by any appropriate method. This water-soluble resin can function as a matrix for the solid upconversion material. Any appropriate water-soluble resin can be used as long as it forms a matrix. Specific examples of water-soluble resins include polystyrene sulfonate, polyethylene oxide, polyethyleneimine, polyvinyl alcohol-based resins, and cellulose-based resins. Examples of polystyrene sulfonate include sodium polystyrene sulfonate. Examples of polyethyleneimine include polyethyleneimine hydrochloride. Examples of polyvinyl alcohol-based resins include polyvinyl alcohol, amine-modified polyvinyl alcohol, and carboxylic acid-modified polyvinyl alcohol. Examples of cellulose-based resins include hydroxyethyl cellulose. The water-soluble resin is preferably polyethylene oxide or a polyvinyl alcohol-based resin, and more preferably a polyvinyl alcohol-based resin. If the water-soluble resin contains polyethylene oxide and / or a polyvinyl alcohol-based resin, the luminescence efficiency of the upconversion material can be stably improved. The concentration of the water-soluble resin in the aqueous solution can be set to any appropriate value. For example, it may be 3% by weight to 20% by weight, or may be 5% by weight to 10% by weight.

[0045] Next, an aqueous solution of the water-soluble resin is mixed with a dye solution or the like so that the blending ratio of the sensitizing component and the light-emitting component relative to the water-soluble resin (matrix) falls within a predetermined range. More specifically, the aqueous solution of the water-soluble resin is mixed with the dye solution or the like, and the mixture is emulsified using a homogenizer. This allows for the preparation of an emulsion in which droplets of the dye solution or the like are suitably dispersed in the aqueous solution of the water-soluble resin. If necessary, the resulting emulsion may be degassed. Furthermore, volatile components (e.g., organic solvents) contained in the resulting emulsion may be distilled off under reduced pressure. This allows for the increased concentrations of the sensitizing component and the light-emitting component in the emulsion. The volume fraction of the emulsion particles is, for example, 5% to 60%. The average particle diameter of the emulsion particles is, for example, 0.1 μm to 10 μm. When the volume fraction and / or average particle diameter of the emulsion particles are within these ranges, a color-developing portion having a desired size can be formed as a dispersed phase in the upconversion film.

[0046] Next, the emulsion obtained above is applied to a substrate to form a coating film. Typical examples of the substrate include a resin sheet or glass. Any suitable resin can be used as the resin constituting the resin sheet. Specific examples include transparent resins such as polyimide resins, cellulose resins such as triacetyl cellulose (TAC), polyester resins, polyvinyl alcohol resins, polycarbonate resins, polyamide resins, polyethersulfone resins, polysulfone resins, polystyrene resins, polynorbornene resins, polyolefin resins, (meth)acrylic resins, and acetate resins. Thermosetting resins or ultraviolet-curing resins such as (meth)acrylic resins, urethane resins, (meth)acrylic urethane resins, epoxy resins, and silicone resins may also be used. Glassy polymers such as siloxane polymers may also be used.

[0047] Any appropriate method can be used as the coating method. Specific examples include roll coating, spin coating, wire bar coating, dip coating, die coating, curtain coating, spray coating, and knife coating (such as comma coating). Alternatively, a coating film can be formed using a drum coating machine. In this case, the coating roll (drying roll) of the drum coating machine can function as the substrate. The coating roll (drying roll) can be made of a metal such as nickel, chromium, copper, iron, or stainless steel. The temperature of the emulsion during coating can be, for example, 10°C to 60°C. The thickness of the coating film can be adjusted to any appropriate value according to the thickness of the upconversion film (for example, 5 μm to 200 μm). The thickness of the coating film can be, for example, 100 μm to 1000 μm.

[0048] The coating is then dried. Drying can be carried out by any suitable means (for example, an oven). The drying temperature can be, for example, 60°C to 90°C, and the drying time can be, for example, 20 to 60 minutes. By drying, a dried coating film having substantially the same thickness as the resulting upconversion film can be obtained. The dried coating film can typically be allowed to cool naturally to room temperature (23°C). The resulting upconversion film can be peeled from the substrate, or can be used as a laminate with the substrate without being peeled from the substrate.

[0049] A-5. Uses of Upconversion Material The upconversion material of an embodiment of the present invention can be used in any suitable application. For example, it can be suitably used in applications such as solar cells such as organic solar cells, photocatalysts, natural light illumination, LEDs, organic EL devices, biomarkers, displays, printing, security authentication, optical data storage devices, and sensors. In one embodiment, the upconversion material of an embodiment of the present invention may be used in the wavelength conversion layer of a pressure-sensitive adhesive sheet having a wavelength conversion layer, as described below.

[0050] B. Pressure-sensitive adhesive sheet B-1. Overall configuration of pressure-sensitive adhesive sheet The pressure-sensitive adhesive sheet according to an embodiment of the present invention comprises a wavelength conversion layer that converts light in a first wavelength region λ1 into light in a second wavelength region λ2 that has a shorter wavelength than the first wavelength region λ1; and a pressure-sensitive adhesive layer that is disposed on one side of the wavelength conversion layer and changes its adhesive strength by absorbing light in the second wavelength region λ2. The pressure-sensitive adhesive layer has a hardness E of 1.0 μm, as measured by a nanoindentation method, before absorbing light in the second wavelength region λ2. １ is 0.01 MPa or more, and the hardness E of the pressure-sensitive adhesive layer after absorbing light in the second wavelength region λ2 as measured by a nanoindentation method ２ is the hardness E measured by the nanoindentation method １ The adhesive strength is at least five times that of the wavelength conversion layer (hereinafter also referred to as the pressure-sensitive adhesive sheet of the first embodiment). If a wavelength conversion layer is provided, light in the first wavelength region λ1 transmitted through the wavelength conversion layer can be converted into light in the second wavelength region λ2, which changes the adhesive strength of the pressure-sensitive adhesive layer. As a result, the adhesive strength of the pressure-sensitive adhesive layer can be changed more efficiently. Another embodiment of the pressure-sensitive adhesive sheet of the present invention comprises a pressure-sensitive adhesive layer including: a wavelength converting material that converts light in the first wavelength region λ1 into light in the second wavelength region λ2, which has a shorter wavelength than the first wavelength region λ1; and a pressure-sensitive adhesive whose adhesive strength changes by absorbing light in the second wavelength region λ2. This pressure-sensitive adhesive layer has a hardness E of the pressure-sensitive adhesive layer measured by a nanoindentation method before absorbing light in the second wavelength region λ2. ３ is 0.01 MPa or more, and the hardness E of the pressure-sensitive adhesive layer after absorbing light in the second wavelength region λ2 as measured by a nanoindentation method ４ is the hardness E of the pressure-sensitive adhesive layer measured by the nanoindentation method. ３This is more than five times the wavelength of the first wavelength region λ1 (hereinafter also referred to as the pressure-sensitive adhesive sheet of the second embodiment). In this embodiment, the pressure-sensitive adhesive layer can also function as a wavelength conversion layer. Light in the first wavelength region λ1 incident on the pressure-sensitive adhesive layer can be converted by the wavelength conversion material contained in the pressure-sensitive adhesive layer into light in the second wavelength region λ2, which changes the adhesive strength of the pressure-sensitive adhesive layer. As a result, the adhesive strength of the pressure-sensitive adhesive layer can be changed more efficiently. According to the pressure-sensitive adhesive sheets of the first and second embodiments of the present invention, the influence of the adherend and other components is suppressed, and a pressure-sensitive adhesive sheet that can exhibit the designed adhesive strength can be obtained. Therefore, even when a substrate that can only transmit light with wavelengths longer than visible light (e.g., polyimide (PI) film, polyethylene naphthalate (PEN) film, silicone, etc.) is used, the designed adhesive strength can be exhibited. More specifically, when a film that can only transmit light with wavelengths longer than visible light is used as the substrate, there is a possibility that light in the second wavelength region λ2, which has a shorter wavelength and can change the adhesive strength of the pressure-sensitive adhesive layer, will not sufficiently reach the pressure-sensitive adhesive layer. Even in such cases, the wavelength conversion layer or the pressure-sensitive adhesive layer having a wavelength conversion function converts long-wavelength light into shorter-wavelength light, thereby sufficiently changing the adhesive strength of the pressure-sensitive adhesive layer. Furthermore, depending on the application of the pressure-sensitive adhesive sheet, the adhesive strength may be changed when the sheet is attached to an adherend. Depending on the type of adherend, light in the second wavelength region λ2, which is shorter wavelength, may not sufficiently reach the pressure-sensitive adhesive layer. Even in such an embodiment, the wavelength conversion layer or the pressure-sensitive adhesive layer having a wavelength conversion function converts long-wavelength light into shorter-wavelength light, thereby sufficiently changing the adhesive strength of the pressure-sensitive adhesive layer. Furthermore, photon upconversion generally depends on the excitation light intensity, and upconversion luminescence can be suppressed with light of low intensity below a threshold. Therefore, the adhesive strength can be controlled by the light irradiation intensity, the pressure-sensitive adhesive is prevented from reacting to normal lighting that can suppress upconversion luminescence, and storage stability can be improved.

[0051] The wavelength conversion layer may be any suitable layer capable of converting light in a first wavelength range λ1 into light in a second wavelength range λ2 having a shorter wavelength than the first wavelength range λ1. Examples of suitable wavelength conversion layers include a layer containing a sensitizing component (donor) capable of absorbing light in the first wavelength range λ1 and a light-emitting component (acceptor) capable of emitting light in a second wavelength range λ2 having a shorter wavelength than the first wavelength range λ1, a layer containing inorganic upconversion particles, a layer containing a first organic semiconductor layer containing a first organic semiconductor material and a second organic semiconductor layer containing a second organic semiconductor material, where the first organic semiconductor layer and the second organic semiconductor layer form a junction, and a layer containing a molecule having a sensitizing group and a light-emitting group in one molecule.

[0052] When the pressure-sensitive adhesive layer can also function as a wavelength conversion layer, the pressure-sensitive adhesive layer may contain any suitable wavelength conversion material capable of converting light in a first wavelength region λ1 into light in a second wavelength region λ2, which has a wavelength shorter than the first wavelength region λ1. Any suitable wavelength conversion material may be used depending on the light in the second wavelength region λ2 at which the adhesive strength of the pressure-sensitive adhesive layer changes. Examples of suitable wavelength conversion materials include a sensitizing component (donor) capable of absorbing light in the first wavelength region λ1, and a light-emitting component (acceptor) capable of emitting light in the second wavelength region λ2, which has a wavelength shorter than the first wavelength region λ1, as well as particles or crystals containing these; inorganic upconversion particles; and molecules having a sensitizing group and a light-emitting group in one molecule. Only one wavelength conversion material may be used, or two or more wavelength conversion materials may be used in combination.

[0053] This will be described in more detail below, taking as an example a case where a sensitizing component (donor) capable of absorbing light in a first wavelength region λ1 and a light-emitting component (acceptor) capable of emitting light in a second wavelength region λ2, the wavelength of which is shorter than the first wavelength region λ1, are used. The pressure-sensitive adhesive sheet of this embodiment comprises a wavelength conversion layer containing a sensitizing component (donor) capable of absorbing light in the first wavelength region λ1 and a light-emitting component (acceptor) capable of emitting light in a second wavelength region λ2, the wavelength of which is shorter than the first wavelength region λ1; and a pressure-sensitive adhesive layer disposed on one side of the wavelength conversion layer, the adhesive strength of which changes upon absorbing light in the second wavelength region λ2. Figure 2 is a schematic cross-sectional view of a pressure-sensitive adhesive sheet according to one embodiment of the present invention. The pressure-sensitive adhesive sheet 100 of the illustrated example comprises a pressure-sensitive adhesive layer 10, a wavelength conversion layer 20, and a substrate 30. The wavelength conversion layer 20 includes a sensitizing component 21 capable of absorbing light in a first wavelength region λ1 and a light emitting component 22 capable of emitting light in a second wavelength region λ2 having a shorter wavelength than the first wavelength region λ1. In the illustrated example, the pressure-sensitive adhesive layer 10 is disposed on the surface of the wavelength conversion layer 20 on which the substrate 30 is not laminated. The pressure-sensitive adhesive layer 10 changes its adhesive strength by absorbing light in the second wavelength region λ2. The pressure-sensitive adhesive layer 10 has a hardness E of 100 μm as measured by a nanoindentation method before absorbing light in the second wavelength region λ2. １ The pressure-sensitive adhesive layer 10 has a hardness E ２ However, the hardness E measured by the nanoindentation method １The optical density is at least five times that of the optical density of the first wavelength region λ1. A pressure-sensitive adhesive sheet according to another embodiment of the present invention comprises a pressure-sensitive adhesive layer including: a sensitizing component capable of absorbing light in a first wavelength region λ1; a light-emitting component capable of emitting light in a second wavelength region λ2 having a wavelength shorter than the first wavelength region λ1; and a pressure-sensitive adhesive whose adhesive strength changes upon absorbing light in the second wavelength region λ2. FIG. 3 is a schematic cross-sectional view of a pressure-sensitive adhesive sheet according to another embodiment of the present invention. The pressure-sensitive adhesive sheet 200 of the illustrated example comprises a pressure-sensitive adhesive layer 40 and a substrate 30. The pressure-sensitive adhesive layer 40 includes a sensitizing component 21 capable of absorbing light in the first wavelength region λ1; a light-emitting component 22 capable of emitting light in a second wavelength region λ2 having a wavelength shorter than the first wavelength region λ1; and a pressure-sensitive adhesive. Specifically, the sensitizing component 21 and the light-emitting component 22 are dispersed in the pressure-sensitive adhesive whose adhesive strength changes upon absorbing light in the second wavelength region λ2. The pressure-sensitive adhesive layer 40 has a hardness E ３ The pressure-sensitive adhesive layer 40 has a hardness E ４ However, the hardness E measured by the nanoindentation method ３ The viscosity of the adhesive layer of the pressure-sensitive adhesive sheet may be adjusted by irradiation with active energy rays such as ultraviolet rays. Pressure-sensitive adhesive sheets typically include a substrate, and depending on the substrate, light irradiated from the substrate side at a wavelength absorbed by the photopolymerization initiator may not sufficiently reach the adhesive layer. This may prevent the adhesive layer from exerting its designed adhesive strength. In the pressure-sensitive adhesive sheet according to an embodiment of the present invention, the wavelength conversion layer 20 or the adhesive layer 40 can convert light in a first wavelength region λ1 into light in a second wavelength region λ2, which has a wavelength shorter than the first wavelength region λ1. Such a wavelength conversion layer 20 or adhesive layer 40 can function as a so-called photon upconversion layer (a layer that converts long-wavelength light to short-wavelength light).

[0054] Although the illustrated example specifically illustrates a single-sided pressure-sensitive adhesive sheet having a substrate, the pressure-sensitive adhesive sheet of the present invention may also be a double-sided pressure-sensitive adhesive sheet. When the pressure-sensitive adhesive sheet of the present invention is a double-sided pressure-sensitive adhesive sheet, a pressure-sensitive adhesive layer may be formed on both sides of the substrate, or the pressure-sensitive adhesive sheet may be substrate-less. The wavelength conversion layer is preferably provided on the light irradiation side. In the case of a double-sided pressure-sensitive adhesive sheet having a substrate, the wavelength conversion layer may be formed on both sides of the substrate, or on only one side of the substrate. The wavelength conversion layer does not necessarily need to be formed on both sides of the substrate; it may be present on either one side. In the case of a substrate-less double-sided pressure-sensitive adhesive sheet, a pressure-sensitive adhesive layer may be formed on both sides of the wavelength conversion layer, and the pressure-sensitive adhesive layer may be formed using a pressure-sensitive adhesive containing a sensitizing component capable of absorbing light in a first wavelength region λ1, a light-emitting component capable of emitting light in a second wavelength region λ2 that has a shorter wavelength than the first wavelength region λ1, and a pressure-sensitive adhesive (i.e., the pressure-sensitive adhesive layer may function as a wavelength conversion layer).

[0055] The hardness measured by the nanoindentation method is obtained by pressing a diamond conical (spherical: radius 10 μm) probe perpendicularly against the surface of the layer to be measured, and the displacement-load hysteresis curve is obtained by numerically processing it using the software (triboscan) attached to the measuring device. In this specification, the hardness measured by the nanoindentation method refers to the hardness measured using a nanoindenter (manufactured by Hysitron Inc., product name "Triboindenter TI-950") at a predetermined temperature (25 ° C.) using a single indentation method under the measurement conditions of an indentation speed of about 500 nm / sec, an extraction speed of about 500 nm / sec, and an indentation depth of about 3000 nm. In addition, in order to prevent the adhesive from hardening due to the light source used to adjust the measurement area, a 130 μm thick polyimide (PI) film was placed in front of the light source, and the measurement was performed in a light-shielded environment. The hardness of the pressure-sensitive adhesive layer after absorption of light in the second wavelength region λ2 can be determined by irradiating light of an arbitrary wavelength (corresponding to light in the second wavelength region λ2) from the wavelength conversion layer side of the pressure-sensitive adhesive sheet at an irradiation speed of 10 mm / min to 10,000 mm / min (preferably 10 mm / min to 5,000 mm / min) and an irradiation intensity of 1 mW / cm. ２ More than 100,000W / cm ２The hardness refers to a value measured in the same manner using a pressure-sensitive adhesive sheet irradiated under the following conditions: In this specification, when the hardness measured by the nanoindentation method is simply referred to without mentioning the cross section or surface, the hardness refers to the hardness measured by the nanoindentation method of the surface of the pressure-sensitive adhesive layer that comes into contact with the adherend.

[0056] In measuring the hardness after light absorption, a laser irradiation device is used as the light source. Laser irradiation devices are disclosed, for example, in Japanese Patent No. 7403887. The disclosure of this publication is incorporated herein by reference. Any appropriate laser irradiation device can be used depending on the sensitizing component. For example, when the sensitizing component is an organic sensitizing component, a nanosecond pulse laser with a wavelength of 532 nm can be used. Specifically, the "7W Green Laser Marker" manufactured by Kokyosha can be used. When the sensitizing component is an inorganic sensitizing component, a CW (continuous wave) laser with a wavelength of 980 nm or a CW laser with a wavelength of 940 nm can be used. Specifically, the "MDL-III-980-2W DG7348" (980 nm fiber output CW diode laser) manufactured by CNI and the "CW Laser Diode L9418-42" manufactured by Hamamatsu Photonics KK can be used. Any suitable control device, such as a galvanometer scanner, may be used in combination with the laser irradiation device.

[0057] In the pressure-sensitive adhesive sheet of the first embodiment, the pressure-sensitive adhesive layer 10 has a hardness E １ The hardness E measured by the nanoindentation method before absorption of light in the second wavelength region λ2 is 0.01 MPa or more, and more preferably 0.015 MPa or more. １ is, for example, 1.2 MPa or less. １ If is within the above range, the pressure-sensitive adhesive sheet and the adherend can be sufficiently adhered to each other.

[0058] In the pressure-sensitive adhesive sheet of the first embodiment, the pressure-sensitive adhesive layer 10 has a hardness E ２ However, the hardness E measured by the nanoindentation method １The hardness E measured by the nanoindentation method after absorption of light in the second wavelength region λ2 is 5 times or more, more preferably 10 times or more, and even more preferably 50 times or more. ２ is the hardness E measured by nanoindentation method １ For example, the change in adhesive strength is 1500 times or less, and preferably 1200 times or less. According to the pressure-sensitive adhesive sheet of the embodiment of the present invention, it is possible to realize such a large change in adhesive strength.

[0059] In the pressure-sensitive adhesive sheet of the second embodiment, the pressure-sensitive adhesive layer 40 has a hardness E ３ The hardness E measured by the nanoindentation method before absorption of light in the second wavelength region λ2 is 0.01 MPa or more, and more preferably 0.015 MPa or more. ３ is, for example, 1.2 MPa or less. ３ If is within the above range, the pressure-sensitive adhesive sheet and the adherend can be sufficiently adhered to each other.

[0060] In the pressure-sensitive adhesive sheet of the second embodiment, the pressure-sensitive adhesive layer 40 has a hardness E ４ However, the hardness E measured by the nanoindentation method ３ The hardness E measured by the nanoindentation method after absorption of light in the second wavelength region λ2 is 5 times or more, more preferably 10 times or more, and even more preferably 50 times or more. ４ is the hardness E measured by nanoindentation method ３ The hardness of the pressure-sensitive adhesive sheet according to the second embodiment of the present invention is, for example, 1500 times or less, and preferably 1200 times or less, of the adhesive strength of the pressure-sensitive adhesive sheet according to the first embodiment of the present invention. The hardness of the pressure-sensitive adhesive sheet according to the second embodiment of the present invention after absorption of light in the second wavelength region λ2 is measured by irradiating light of an arbitrary wavelength (corresponding to light in the second wavelength region λ2) from one side of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet at an irradiation speed of 10 mm / min to 10,000 mm / min (preferably 10 mm / min to 5,000 mm / min) and an irradiation intensity of 1 mW / cm. ２ More than 100,000W / cm ２ This refers to the value measured in the same manner using a pressure-sensitive adhesive sheet irradiated under the following conditions.

[0061] In the pressure-sensitive adhesive sheet according to an embodiment of the present invention, the 180° peel strength of the pressure-sensitive adhesive layer after absorbing light in the second wavelength region λ2 is preferably 70% or less, more preferably 60% or less, and even more preferably 55% or less, when the 180° peel strength of the pressure-sensitive adhesive layer before absorbing light in the second wavelength region λ2 is taken as 100%. Furthermore, the 180° peel strength of the pressure-sensitive adhesive layer after absorbing light in the second wavelength region λ2 is preferably 0.001% or more, more preferably 0.01% or more, when the 180° peel strength of the pressure-sensitive adhesive layer before absorbing light in the second wavelength region λ2 is taken as 100%. If the 180° peel strength of the pressure-sensitive adhesive layer after absorbing light in the second wavelength region λ2 is within the above range, the adhesive strength of the pressure-sensitive adhesive layer can be appropriately adjusted, and for example, the pressure-sensitive adhesive layer can be peeled off without leaving any adhesive residue on the adherend. In this specification, the 180° peel strength refers to a value measured by the following method. The adhesive sheet is cut to a width of 20 mm and a length of 100 mm, and the adhesive layer of the adhesive sheet is bonded to an alkali glass plate (e.g., a 1.35 mm thick, polished blue plate, manufactured by Matsunami Glass Industry Co., Ltd.) by rolling it back and forth once with a 2 kg roller under pressure at 23°C and 50% RH. The alkali glass plate to which the adhesive sheet is bonded is left to stand for 6 hours under the same environment and used as an evaluation sample. The evaluation sample is placed in a tensile tester (e.g., Shimadzu Corporation, product name "EZ-S 50N" or equivalent) under an environment of 23°C and 50% RH, and the adhesive sheet is peeled from the adherend at a peel angle of 180° and a speed of 300 mm / min to measure the peel strength. If the adhesive sheet to be evaluated is a double-sided adhesive sheet, the non-measurement side can be backed with a PET film before the measurement. The peel strength after absorption of light in the second wavelength region λ2 was 16,000 W / cm2 in terms of integrated light intensity when light of an arbitrary wavelength (corresponding to light in the second wavelength region λ2) was irradiated from the wavelength conversion layer side of the pressure-sensitive adhesive sheet in the first embodiment, and from one side of the pressure-sensitive adhesive layer in the pressure-sensitive adhesive sheet in the second embodiment. ２The term "laminar wavelength" refers to a value measured in the same manner using an irradiated pressure-sensitive adhesive sheet. Depending on the pressure-sensitive adhesive layer, a value obtained by irradiating a smaller integrated amount of light than the above value may be used. For example, when a wavelength conversion layer with higher upconversion luminous efficiency or a wavelength conversion layer with high absorbance is used, and / or when a pressure-sensitive adhesive layer with a high content of photopolymerization initiator or a pressure-sensitive adhesive layer containing a photopolymerization initiator with high absorbance in the second wavelength region λ2 is used, a value smaller than the above value may be used.

[0062] The pressure-sensitive adhesive sheet of the present embodiment can be set to any appropriate thickness. It is preferably 5 μm to 200 μm, more preferably 10 μm to 200 μm, and even more preferably 20 μm to 100 μm. The thickness of the pressure-sensitive adhesive sheet of the first embodiment is preferably 5 μm to 200 μm, more preferably 10 μm to 200 μm. The thickness of the pressure-sensitive adhesive sheet of the second embodiment is preferably 5 μm to 200 μm, more preferably 10 μm to 200 μm.

[0063] The PSA sheet may further include any appropriate other layers. Examples of such other layers include an intermediate layer, an antistatic layer, and an undercoat layer. Furthermore, in practice, a release liner may be temporarily attached to the PSA layers 20 and 40 of the PSA sheet until use. Hereinafter, specific embodiments will be described in which the wavelength conversion layer includes a sensitizing component capable of absorbing light in a first wavelength region λ1 and a light-emitting component capable of emitting light in a second wavelength region λ2, the wavelength of which is shorter than that of the first wavelength region λ1.

[0064] C. Pressure-sensitive adhesive sheet of first embodiment As described above, the pressure-sensitive adhesive sheet of the first embodiment comprises a wavelength conversion layer that converts light in a first wavelength region λ1 into light in a second wavelength region λ2 that has a wavelength shorter than the first wavelength region λ1; and a pressure-sensitive adhesive layer that is disposed on one side of the wavelength conversion layer and whose adhesive strength changes by absorbing light in the second wavelength region λ2. In one embodiment, the pressure-sensitive adhesive sheet 100 comprises a wavelength conversion layer 20 that contains a sensitizing component 21 that can absorb light in the first wavelength region λ1 and a light-emitting component 22 that can emit light in a second wavelength region λ2 that has a wavelength shorter than the first wavelength region λ1; and a pressure-sensitive adhesive layer 10 that is disposed on one side of the wavelength conversion layer and whose adhesive strength changes by absorbing light in the second wavelength region λ2. The wavelength conversion layer will be described in detail below.

[0065] C-1. Wavelength Conversion Layer If the pressure-sensitive adhesive sheet includes a wavelength conversion layer, light in the first wavelength region λ1 transmitted through the wavelength conversion layer can be converted into light in the second wavelength region λ2, which can change the adhesive strength of the pressure-sensitive adhesive layer. As a result, light of the wavelength required for the pressure-sensitive adhesive layer to change its adhesive strength can be more efficiently absorbed by the pressure-sensitive adhesive layer, allowing for efficient change in adhesive strength. Furthermore, even when a substrate is used that does not sufficiently transmit light of the wavelength required for the pressure-sensitive adhesive layer to change its adhesive strength, irradiation with highly transparent long-wavelength light can be converted into shorter-wavelength light in the wavelength conversion layer, thereby changing the adhesive strength of the pressure-sensitive adhesive layer. Typically, the wavelength conversion layer 20 is a layer in which a sensitizing component 21 and a light-emitting component 22 are dispersed in any suitable matrix. As described above, the wavelength conversion layer may be a layer in which the sensitizing component 21 and the light-emitting component 22 form a bonding surface as an organic semiconductor layer, or a layer in which inorganic upconversion particles are dispersed in any matrix.

[0066] The thickness of the wavelength conversion layer 20 can be set to any appropriate thickness. The thickness of the wavelength conversion layer is preferably 5 μm to 200 μm, more preferably 10 μm to 150 μm, and even more preferably 15 μm to 100 μm. When the thickness of the wavelength conversion layer is within the above range, the sensitizing component and the light-emitting component can be well dispersed throughout the entire thickness direction of the wavelength conversion layer, and wavelength conversion can be stably achieved.

[0067] C-1-1. Wavelength conversion layer utilizing triplet-triplet annihilation (TTA) caused by collisions between triplet-state molecules In one embodiment, the wavelength conversion layer includes a sensitizer component (hereinafter simply referred to as "sensitizer component") capable of absorbing light in a first wavelength region λ1, and a light-emitting component (hereinafter simply referred to as "light-emitting component") capable of emitting light in a second wavelength region λ2 having a shorter wavelength than the first wavelength region λ1. The mechanism of photon upconversion utilizing triplet-triplet annihilation (TTA) caused by collisions between triplet-state molecules will be described with reference to FIG. 1. As described above, first, the donor absorbs incident light and converts it into an excited singlet state S Ｄ Intersystem crossing from Ｄ Then, triplet-triplet energy transfer (TTET) occurs from the donor to the acceptor, resulting in the excited triplet state T Ａ is generated. Then, the excited triplet state T Ａ The triplet-triplet annihilation (TTA) occurs when the acceptors in the high excited singlet energy state S Ａ is generated. This high excited singlet energy state S Ａ Upconversion light (light with more energy than the pump light) is emitted from the

[0068] C-1-1-1. Matrix The matrix may be formed of any suitable material. Typically, a resin may be used. Specifically, the resin may be a water-soluble resin or an oil-soluble resin.

[0069] Any suitable water-soluble resin can be used as the water-soluble resin as long as a matrix can be formed. Specific examples of water-soluble resins include polystyrene sulfonate, polyethylene oxide, polyethyleneimine, polyvinyl alcohol resins, and cellulose resins. Examples of polystyrene sulfonate include sodium polystyrene sulfonate. Examples of polyethyleneimine include polyethyleneimine hydrochloride. Examples of polyvinyl alcohol resins include polyvinyl alcohol, amine-modified polyvinyl alcohol, and carboxylic acid-modified polyvinyl alcohol. Examples of cellulose resins include hydroxyethyl cellulose.

[0070] As the oil-soluble resin, any suitable oil-soluble resin can be used as long as it can form a matrix. Specific examples of oil-soluble resins include (meth)acrylic resins, polystyrene, polycarbonate resins, and polyester resins. Examples of (meth)acrylic resins include polymethyl methacrylate (PMMA). Examples of polyester resins include polyethylene terephthalate (PET).

[0071] C-1-1-2. Sensitizer Component Capable of Absorbing Light in the First Wavelength Region λ1 The sensitizer component absorbs light (incident light), transitions from an excited singlet state to an excited triplet state through intersystem crossing, and induces triplet-triplet energy transfer in the light-emitting component. Examples of sensitizer components include compounds having a porphyrin structure, a phthalocyanine structure, a dipyrromethene boron complex (BODIPY) structure, a coumarin structure, a quinone structure, a xanthene structure, a fullerene structure, a phenoxazine structure, a phenothiazine structure, an acridone structure, a carbazole structure, or a phenazaborine structure. Such compounds may contain metal atoms in their molecules. Examples of metal atoms include Pt, Pd, Zn, Ru, Re, Ir, Os, Cu, Ni, Co, Cd, Au, Ag, Sn, Sb, Pb, P, and As. Preferred are Pt, Pd and Os. Specific examples of compounds that can function as a sensitizing component will be described later.

[0072] The sensitizing component may be a quantum dot. The quantum dot may be made of any suitable material. The quantum dot may be made of preferably an inorganic material, more preferably an inorganic conductive material or an inorganic semiconducting material. Examples of semiconducting materials include Group II-VI, Group III-V, Group IV-VI, and Group IV semiconductors. Specific examples include Si, Ge, Sn, Se, Te, B, C (including diamond), P, BN, BP, BAs, AlN, AlP, AlA. s, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, InSb, ZnO, ZnS, ZnSe, ZnTe, C dS, CdSe, CdSeZn, CdTe, HgS, HgSe, HgTe, BeS, BeSe, BeTe, MgS, MgSe, GeS, GeSe, GeTe, SnS, SnSe, SnTe, PbO, PbS, PbSe, PbTe, CuF, CuCl, CuBr, CuI, Si ３ N ４ , Ge ３ N ４ , Al ２ O ３ , (Al, Ga, In) ２ (S, Se, Te) ３ , Al ２ CO, and combinations (complexes) thereof.

[0073] The sensitizing component is preferably 7.00×10 －９ mol~5.00×10 －６ mol, more preferably 1.00 x 10 －８ mol~3.00×10 －６ mol, more preferably 4.50 × 10 －８ mol~2.00×10 －６ The wavelength conversion layer contains the sensitizing component in a ratio of 1 / 2 mole to 1 / 2 mole. If the content of the sensitizing component is too small, sufficient triplet excitons may not be generated, resulting in insufficient efficiency in triplet-triplet annihilation. If the content of the sensitizing component is too large, triplet-triplet annihilation between sensitizing component molecules or reabsorption of upconversion luminescence energy may result in insufficient efficiency.

[0074] C-1-1-3. Light-emitting component capable of emitting light in a second wavelength region λ2, which is shorter in wavelength than the first wavelength region λ1. The light-emitting component receives triplet-triplet energy transfer from the sensitizing component to generate an excited triplet state, and the light-emitting component molecules in the excited triplet state diffuse and collide with each other, causing triplet-triplet annihilation to generate an excited singlet of a higher energy level. Various compounds having fused aromatic rings are known as light-emitting components. Specific examples include compounds having a naphthalene structure, an anthracene structure, a pyrene structure, a perylene structure, a tetracene structure, a bodipyrromethene structure, and a diketopyrrolopyrrole structure. Specific examples of compounds that can function as light-emitting components will be described later.

[0075] The light-emitting component is preferably 5.00×10 －６ mol~7.00×10 －５ mol, more preferably 6.00 x 10 －６ mol~6.00×10 －５ mol, more preferably 7.00 × 10 －６ mol~5.00×10 －５ The wavelength conversion layer contains the luminescent component at a molar ratio of 1:1. If the content of the luminescent component is too small, the distance between the luminescent component molecules increases, and triplet excitons received from the sensitizing component may not be able to diffuse between the luminescent component molecules. If the content of the luminescent component is too large, it may lead to deactivation due to concentration quenching.

[0076] The blending ratio of the sensitizing component to the light-emitting component (sensitizing component:light-emitting component) (molar ratio) is preferably 1:10 to 1:7000, more preferably 1:25 to 1:3000, even more preferably 1:30 to 1:200, and particularly preferably 1:35 to 1:100. When the blending ratio is within this range, triplet excitons generated from the sensitizing component can efficiently transfer to the light-emitting component, and deactivation between the light-emitting components can be minimized, thereby achieving good triplet-triplet annihilation.

[0077] C-1-1-4. Combination of Sensitizing Component and Light-Emitting Component The sensitizing component and the light-emitting component may be used in any appropriate combination depending on the wavelength region of light absorbed by the pressure-sensitive adhesive layer. Preferred combinations of the sensitizing component and the light-emitting component depending on the wavelengths of the incident light included in the first wavelength region λ1 and the upconversion light included in the second wavelength region λ2 are as follows:

[0078] The sensitizing component that absorbs light in the wavelength region λ1 of 510 nm to 550 nm is the following compound, and the light-emitting component that emits (emits) light in the wavelength region λ2 of 400 nm to 500 nm is the following compound. This combination can upconvert green light to blue light. <Sensitizing Component> <Luminescent components>

[0079] The sensitizing component that absorbs light in the wavelength region λ1 of 610 nm to 650 nm is the following compound, and the light-emitting component that emits (emits) light in the wavelength region λ2 of 500 nm to 600 nm is the following compound. This combination can upconvert red light to yellow-green light. <Sensitizing Component> <Luminescent components>

[0080] The sensitizing component that absorbs light in the wavelength region λ1 of 700 nm to 810 nm is the following compound, and the light-emitting component that emits (emits) light in the wavelength region λ2 of 500 nm to 700 nm is the following compound. This combination can upconvert near-infrared light to visible light (red light to green light). <Sensitizing Component> <Luminescent components>

[0081] The sensitizing component that absorbs light in the wavelength region λ1 of 700 nm to 730 nm is the following compound, and the light-emitting component that emits (emits) light in the wavelength region λ2 of 400 nm to 500 nm is the following compound. This combination can upconvert near-infrared light to visible light (blue light). <Sensitizing Component> <Luminescent components>

[0082] The sensitizing components that absorb light in the wavelength region λ1 of 410 nm to 600 nm are compounds (A) to (D) described in the above section A and the following compound, and the light-emitting component that emits (emits) light in the wavelength region λ2 of 300 nm to 400 nm is the following compound. This combination can upconvert blue light to ultraviolet light. <Sensitizing Components> <Luminescent components>

[0083] The sensitizing component that absorbs light in the wavelength region λ1 of around 630 nm to 640 nm (e.g., 635 nm) is quantum dots (CdSe, CdSe / ZnS), and the light-emitting component that emits (emits) light in the wavelength region λ2 of around 440 nm to 460 nm (e.g., 450 nm) is the following compound. This combination can upconvert near-infrared light to visible light (blue light). <Light-emitting component>

[0084] The sensitizing component that absorbs light in the wavelength region λ1 of around 970 nm to 990 nm (for example, 980 nm) is quantum dots (PbSe, PbS / CdS), and the light-emitting component that emits (emits) light in the wavelength region λ2 of around 550 nm to 570 nm (for example, 560 nm) is the following compound. This combination can upconvert near-infrared light to visible light (green light). <Light-emitting component>

[0085] C-1-2. Photon Upconversion at a Junction Interface Using Organic Semiconductor Materials In one embodiment, the wavelength conversion layer includes a first organic semiconductor layer containing a first organic semiconductor material and a second organic semiconductor layer containing a second organic semiconductor material, where the first organic semiconductor layer and the second organic semiconductor layer form a junction interface. When this wavelength conversion layer is irradiated with long-wavelength excitation light (e.g., near-infrared light), the excitation light is absorbed by the first organic semiconductor material (acceptor) in the first organic semiconductor layer, generating an excited state (S1). Charge separation occurs at the junction interface between the first organic semiconductor layer and the second organic semiconductor layer, generating electron (-)-hole (+) pairs. The generated electron (-)-hole (+) pairs undergo charge recombination via a charge transfer (CT) state, generating a triplet state (T1) of the second organic semiconductor material (donor) in the second organic semiconductor layer. By causing TTA in the second organic semiconductor layer, a high-energy excited state (S1) is generated, and short-wavelength light emission (upconversion light emission) originating from the second organic semiconductor material can occur. Any appropriate material that can exhibit the wavelength shifting function described above can be used as the first organic semiconductor material and the second organic semiconductor material.

[0086] C-1-3. Wavelength Conversion Layer Containing Inorganic Upconversion Particles Any suitable particles can be used as inorganic particles having an upconversion function. Specifically, particles containing lanthanoid elements are known. Wavelength conversion can be performed by utilizing the phenomenon of "multiphoton excitation" due to the difference in energy levels of these elements. The lanthanoid may be any rare earth element that can be excited by light within a wavelength range and emit upconversion light. Examples include erbium (Er), holmium (Ho), praseodymium (Pr), thulium (Tm), neodymium (Nd), gadolinium (Gd), europium (Eu), ytterbium (Yb), samarium (Sm), and cerium (Ce). These lanthanoids may be used alone or in combination of two or more. Among them, lanthanoids with wavelengths of 10,000 cm －１Preferred are ytterbium, which has strong absorption in the vicinity of 1000 nm, and holmium, thulium, gadolinium, and combinations thereof, which emit light upon energy transfer from ytterbium and have wavelengths in the ultraviolet region. In addition to rare earth elements capable of emitting light, lanthanoid ions, alkali metals, alkaline earth metals, and the like may also be doped. When doped, highly stable oxides and fluorides are preferred as hosts.

[0087] Any suitable photon upconversion film may be used as the wavelength conversion layer. Photon upconversion films that can be used in the pressure-sensitive adhesive sheet of the present invention are disclosed, for example, in International Publication No. 2003 / 074040. The disclosure of this publication is incorporated herein by reference.

[0088] C-2. Pressure-sensitive adhesive layer As described above, the pressure-sensitive adhesive layer 10 is a layer whose adhesive strength changes upon absorbing light in the second wavelength region λ2. For example, when the pressure-sensitive adhesive layer contains a photopolymerization initiator, the photopolymerization initiator absorbs and activates light in the second wavelength region λ2, promoting polymerization of polymerizable functional groups in the polymer, thereby reducing the adhesive strength of the pressure-sensitive adhesive layer. The pressure-sensitive adhesive layer whose adhesive strength changes upon absorbing light in the second wavelength region λ2 can be formed from any appropriate pressure-sensitive adhesive. For example, an active energy ray-curable pressure-sensitive adhesive can be used.

[0089] The thickness of the pressure-sensitive adhesive layer can be set to any appropriate thickness. The thickness of the pressure-sensitive adhesive layer is preferably 5 μm to 500 μm, more preferably 10 μm to 300 μm, and even more preferably 20 μm to 100 μm. When the thickness of the pressure-sensitive adhesive layer is within the above range, it can exert sufficient adhesive strength to the adherend.

[0090] Examples of resin materials constituting the active energy ray-curable pressure-sensitive adhesive include those described in Ultraviolet Curing System (by Kiyomi Kato, published by the General Technology Center (1989)), Photocuring Technology (edited by the Technical Information Association (2000)), JP 2003-292916 A, and Japanese Patent No. 4151850. More specifically, examples include resin materials containing a polymer as a base material and an active energy ray-reactive compound (monomer or oligomer), and resin materials containing an active energy ray-reactive polymer.

[0091] Examples of the polymer that can be used as the base material include rubber-based polymers such as natural rubber, polyisobutylene rubber, styrene-butadiene rubber, styrene-isoprene-styrene block copolymer rubber, reclaimed rubber, butyl rubber, polyisobutylene rubber, and nitrile rubber (NBR); silicone-based polymers; and acrylic-based polymers. These polymers may be used alone or in combination of two or more.

[0092] Examples of the active energy ray-reactive compound include photoreactive monomers or oligomers having multiple functional groups with carbon-carbon multiple bonds, such as acryloyl groups, methacryloyl groups, vinyl groups, allyl groups, and acetylene groups. Among these, compounds having ethylenically unsaturated functional groups are preferably used, and (meth)acrylic compounds having ethylenically unsaturated functional groups are more preferably used. Compounds having ethylenically unsaturated functional groups readily generate radicals when exposed to ultraviolet light, and thus, by using such compounds, a pressure-sensitive adhesive layer that can be cured in a short period of time can be formed. Furthermore, by using a (meth)acrylic compound having an ethylenically unsaturated functional group, a pressure-sensitive adhesive layer that exhibits appropriate hardness after curing can be formed. Specific examples of photoreactive monomers or oligomers include (meth)acryloyl group-containing compounds such as trimethylolpropane tri(meth)acrylate, tetramethylolmethane tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol monohydroxypenta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, polyethylene glycol di(meth)acrylate, and urethane (meth)acrylate compounds; dimers to pentamers of the (meth)acryloyl group-containing compounds; and the like. These compounds may be used alone or in combination of two or more.

[0093] The active energy ray-reactive compound may be a monomer such as epoxidized butadiene, glycidyl methacrylate, acrylamide, or vinylsiloxane, or an oligomer formed from such a monomer. Resin materials containing these compounds can be cured by high-energy rays such as ultraviolet rays or electron beams.

[0094] Furthermore, the active energy ray-reactive compound may be a mixture of an organic salt such as an onium salt and a compound having multiple heterocycles in the molecule. When irradiated with active energy rays (e.g., ultraviolet light or an electron beam), the organic salt in the mixture is cleaved to generate ions, which act as initiating species to cause a ring-opening reaction of the heterocycles, forming a three-dimensional network structure. Examples of the organic salt include iodonium salts, phosphonium salts, antimonium salts, sulfonium salts, and borate salts. Examples of the heterocycle in the compound having multiple heterocycles in the molecule include oxirane, oxetane, oxolane, thiirane, and aziridine.

[0095] In the resin material containing the above-mentioned base polymer and active energy ray reactive compound, the content of the active energy ray reactive compound is preferably 0.1 to 500 parts by weight, more preferably 1 to 300 parts by weight, and even more preferably 10 to 200 parts by weight, relative to 100 parts by weight of the base polymer.

[0096] Examples of the active energy ray-reactive polymer include polymers having an active energy ray-reactive functional group having a carbon-carbon multiple bond, such as an acryloyl group, a methacryloyl group, a vinyl group, an allyl group, or an acetylene group. Preferably, a compound (polymer) having an ethylenically unsaturated functional group is used, and more preferably, a (meth)acrylic polymer having an acryloyl group or a methacryloyl group is used. Specific examples of polymers having an active energy ray-reactive functional group include polymers composed of polyfunctional (meth)acrylates. The polymer composed of the polyfunctional (meth)acrylate preferably has an alkyl ester having 4 or more carbon atoms in the side chain, more preferably an alkyl ester having 6 or more carbon atoms, even more preferably an alkyl ester having 8 or more carbon atoms, particularly preferably an alkyl ester having 8 to 20 carbon atoms, and most preferably an alkyl ester having 8 to 18 carbon atoms.

[0097] The resin material containing the active energy ray-reactive polymer may further contain the active energy ray-reactive compound (monomer or oligomer).

[0098] The active energy ray-curable adhesive can be cured by irradiation with active energy rays. In the pressure-sensitive adhesive sheet of an embodiment of the present invention, an adherend can be attached to the adhesive sheet before curing the adhesive, and then the adhesive can be cured by irradiating the adherend with active energy rays, thereby adhering the adhesive to the adhesive. Examples of active energy rays include gamma rays, ultraviolet rays, visible light, infrared rays (heat rays), radio waves, alpha rays, beta rays, electron beams, plasma flow, ionizing rays, and particle beams. Conditions such as the wavelength and dose of the active energy rays can be set as appropriate depending on the type of resin material used, etc. Here, the second wavelength range λ2 can be set to include the wavelength of the active energy rays used.

[0099] C-2-1. Photopolymerization initiator The pressure-sensitive adhesive layer preferably contains a photopolymerization initiator. If the pressure-sensitive adhesive layer contains a photopolymerization initiator, the photopolymerization initiator is activated by light in the second wavelength region λ2 converted by the wavelength conversion layer, and the adhesive strength of the pressure-sensitive adhesive layer can be changed. Any appropriate initiator can be used as the photopolymerization initiator. Examples of the photopolymerization initiator include acylphosphine oxide-based photopolymerization initiators such as ethyl 2,4,6-trimethylbenzylphenylphosphinate and (2,4,6-trimethylbenzoyl)-phenylphosphine oxide; α-ketol-based compounds such as 4-(2-hydroxyethoxy)phenyl(2-hydroxy-2-propyl)ketone, α-hydroxy-α,α'-dimethylacetophenone, 2-methyl-2-hydroxypropiophenone, and 1-hydroxycyclohexylphenyl ketone; acetophenone-based compounds such as methoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone, and 2-methyl-1-[4-(methylthio)-phenyl]-2-morpholinopropane-1; benzoin ether-based compounds such as benzoin ethyl ether, benzoin isopropyl ether, and anisoin methyl ether; and benzo aromatic sulfonyl chloride compounds such as 2-naphthalenesulfonyl chloride; photoactive oxime compounds such as 1-phenone-1,1-propanedione-2-(o-ethoxycarbonyl)oxime; benzophenone compounds such as benzophenone, benzoylbenzoic acid, and 3,3'-dimethyl-4-methoxybenzophenone; thioxanthone compounds such as thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, and 2,4-diisopropylthioxanthone; camphorquinone; halogenated ketones; acylphosphonates; and α-hydroxyacetophenones such as 2-hydroxy-1-(4-(4-(2-hydroxy-2-methylpropionyl)benzyl)phenyl)-2-methylpropane-1. Preferably, an acetophenone-based compound can be used. The photopolymerization initiator may be used alone or in combination of two or more.

[0100] As the photopolymerization initiator, commercially available products may be used, for example, trade names of Omnirad 127D, Omnirad 379EG, Omnirad 651, Omnirad 819, Omnirad 907, and Omnipol TX manufactured by IGM Resins, and trade names of "Nikkacure TG-10" and "Nikkacure TKG10" manufactured by Nippon Chemical Industry Co., Ltd.

[0101] The photopolymerization initiator can be used in any appropriate amount. The content of the photopolymerization initiator is preferably 0.5 to 20 parts by weight, more preferably 0.5 to 10 parts by weight, relative to 100 parts by weight of the base polymer of the pressure-sensitive adhesive. If the content of the photopolymerization initiator is less than 0.5 parts by weight, there is a risk that the pressure-sensitive adhesive will not cure sufficiently when irradiated with ultraviolet light. If the content of the photopolymerization initiator exceeds 10 parts by weight, there is a risk that the storage stability of the pressure-sensitive adhesive will decrease.

[0102] The adhesive forming the adhesive layer may further contain any appropriate additives as needed, such as crosslinkers, tackifiers (e.g., rosin-based tackifiers, terpene-based tackifiers, hydrocarbon-based tackifiers, etc.), curing agents, plasticizers (e.g., trimellitic ester-based plasticizers, pyromellitic ester-based plasticizers), pigments, dyes, antioxidants, conductive materials, antistatic agents, light stabilizers, release modifiers, softeners, surfactants, flame retardants, antioxidants, etc.

[0103] Examples of the crosslinking agent include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, melamine-based crosslinking agents, peroxide-based crosslinking agents, as well as urea-based crosslinking agents, metal alkoxide-based crosslinking agents, metal chelate-based crosslinking agents, metal salt-based crosslinking agents, carbodiimide-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, and amine-based crosslinking agents. Of these, isocyanate-based crosslinking agents and epoxy-based crosslinking agents are preferred.

[0104] Specific examples of the isocyanate-based crosslinking agent include lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate; alicyclic isocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate and isophorone diisocyanate; aromatic isocyanates such as 2,4-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate and xylylene diisocyanate; and isocyanate adducts such as trimethylolpropane / tolylene diisocyanate trimer adduct (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name "Coronate L"), trimethylolpropane / hexamethylene diisocyanate trimer adduct (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name "Coronate HL"), and isocyanurate of hexamethylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name "Coronate HX"). The content of the isocyanate-based crosslinking agent can be set to any appropriate amount depending on the desired adhesive strength, and is typically 0.1 to 20 parts by weight, and preferably 0.5 to 10 parts by weight, per 100 parts by weight of the base polymer.

[0105] Examples of the epoxy crosslinking agent include N,N,N',N'-tetraglycidyl-m-xylylenediamine, diglycidylaniline, 1,3-bis(N,N-glycidylaminomethyl)cyclohexane (manufactured by Mitsubishi Gas Chemical Company, Inc., trade name "Tetrad C"), 1,6-hexanediol diglycidyl ether (manufactured by Kyoeisha Chemical Co., Ltd., trade name "Epolite 1600"), neopentyl glycol diglycidyl ether (manufactured by Kyoeisha Chemical Co., Ltd., trade name "Epolite 1500NP"), ethylene glycol diglycidyl ether (manufactured by Kyoeisha Chemical Co., Ltd., trade name "Epolite 1500NP"), and ethylene glycol diglycidyl ether (manufactured by Kyoeisha Chemical Co., Ltd., trade name "Epolite 1500NP"). Licor diglycidyl ether (manufactured by Kyoeisha Chemical Co., Ltd., trade name "Epolite 40E"), propylene glycol diglycidyl ether (manufactured by Kyoeisha Chemical Co., Ltd., trade name "Epolite 70P"), polyethylene glycol diglycidyl ether (manufactured by NOF Corporation, trade name "Epiol E-400"), polypropylene glycol diglycidyl ether (manufactured by NOF Corporation, trade name "Epiol P-200"), sorbitol polyglycidyl ether (manufactured by Nagase ChemteX Corporation, trade name "Denacol") Examples of suitable crosslinking agents include glycerol polyglycidyl ether (manufactured by Nagase ChemteX Corporation, trade name "Denacol EX-611"), glycerol polyglycidyl ether (manufactured by Nagase ChemteX Corporation, trade name "Denacol EX-314"), pentaerythritol polyglycidyl ether, polyglycerol polyglycidyl ether (manufactured by Nagase ChemteX Corporation, trade name "Denacol EX-512"), sorbitan polyglycidyl ether, trimethylolpropane polyglycidyl ether, adipic acid diglycidyl ester, o-phthalic acid diglycidyl ester, triglycidyl tris(2-hydroxyethyl)isocyanurate, resorcinol diglycidyl ether, bisphenol-S-diglycidyl ether, and epoxy resins having two or more epoxy groups in the molecule. The content of the epoxy crosslinking agent can be set at any appropriate amount depending on the desired adhesive strength, and is typically 0.01 to 10 parts by weight, and preferably 0.03 to 5 parts by weight, per 100 parts by weight of the base polymer.

[0106] Hardness E of adhesive layer measured by nanoindentation method １ is as described above. The hardness E of the pressure-sensitive adhesive layer measured by the nanoindentation method after absorbing light in the second wavelength region λ2 is ２ is the above hardness E １Specifically, the hardness E measured by the nanoindentation method is 5 times or more. ２ is preferably 1 MPa to 30 MPa, more preferably 1.5 MPa to 20 MPa, and even more preferably 2 MPa to 20 MPa. ２ If the viscosity is within the above range, adhesive residue on the adherend can be suppressed and the adhesive can be easily peeled off.

[0107] C-3. Substrate Any appropriate substrate is used as the substrate depending on the application of the PSA sheet, etc. For example, the substrate can be composed of any appropriate resin. The substrate may be a silicon wafer, glass, or the like. Specific examples of resins constituting the substrate include polyester-based resins such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), and polybutylene naphthalate (PBN); polyolefin-based resins such as ethylene-vinyl acetate copolymer, ethylene-methyl methacrylate copolymer, polyethylene, polypropylene, and ethylene-propylene copolymer; polyvinyl alcohol, polyvinylidene chloride, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyamide, polyimide, cellulose, fluorine-based resins, polystyrene-based resins such as polyether and polystyrene; polycarbonate, polyethersulfone, and polyetheretherketone. When the PSA sheet is to be used for applications requiring high heat resistance, a substrate composed of a resin having a rigid chain is preferably used. Specifically, polyimide-based resin films and polyethylene naphthalate-based resin films are used. Use of these resin films can provide a pressure-sensitive adhesive sheet with better heat resistance. Furthermore, when using these resin films, the substrate may absorb specific wavelengths, and the change in adhesive strength of the pressure-sensitive adhesive layer may not reach a predetermined value. The pressure-sensitive adhesive sheet of an embodiment of the present invention includes a wavelength conversion layer. Therefore, even when these resin films are used as the substrate, a pressure-sensitive adhesive sheet that can exert the designed adhesive strength can be provided. Note that these resin films absorb light of 400 nm or more, and therefore cannot transmit ultraviolet light, and the change in adhesive strength of the pressure-sensitive adhesive layer may not reach a predetermined value. The pressure-sensitive adhesive sheet of an embodiment of the present invention includes a wavelength conversion layer. Therefore, even when these resin films are used as the substrate, a pressure-sensitive adhesive sheet that can exert the designed adhesive strength can be provided.

[0108] The substrate may further contain other components within the range that does not impair the effects of the present invention. Examples of other components include antioxidants, ultraviolet absorbers, light stabilizers, heat stabilizers, antistatic agents, etc. The types and amounts of other components can be any appropriate amount depending on the purpose.

[0109] In one embodiment, the substrate may be a resin film that has been subjected to a surface treatment. Examples of the surface treatment include corona treatment, adhesion-enhancing treatment, and formation of a surface treatment layer such as a primer layer. The surface treatment layer can be formed by any suitable method. For example, the surface treatment layer can be formed by applying or printing any suitable composition onto the surface of the substrate.

[0110] The transmittance of the substrate for light in the first wavelength region λ1 is preferably 50% or more, more preferably 55% or more, and even more preferably 60% or more. The transmittance of the substrate for light in the first wavelength region λ1 is, for example, 92% or less. If the transmittance of light in the first wavelength region λ1 is in the upper range, the light transmitted through the substrate can be more efficiently converted into light in the second wavelength region λ2 by the wavelength conversion layer.

[0111] The transmittance of the substrate for light in the second wavelength region λ2 is preferably 10% or less, more preferably 7% or less, and even more preferably 5% or less. The transmittance of the substrate for light in the second wavelength region λ2 is, for example, 0.1% or more. If the transmittance of light in the second wavelength region λ2 is within the above range, the reaction does not proceed even when stored under normal conditions, and long-term storage stability can be ensured.

[0112] The thickness of the substrate is preferably 10 μm to 400 μm, more preferably 15 μm to 350 μm, and even more preferably 20 μm to 250 μm.

[0113] D. Pressure-Sensitive Adhesive Sheet of Second Embodiment In a pressure-sensitive adhesive sheet according to another embodiment (second embodiment) of the present invention, the pressure-sensitive adhesive layer may contain a wavelength converting material. Any suitable material having wavelength converting functionality may be used as the wavelength converting material. Examples include a sensitizing component capable of absorbing light in the first wavelength region λ1, a light-emitting component capable of emitting light in a second wavelength region λ2 that is shorter than the first wavelength region λ1, and inorganic upconversion particles. In one embodiment, a pressure-sensitive adhesive sheet 200 according to the second embodiment includes a pressure-sensitive adhesive layer 40 including a sensitizing component 21 capable of absorbing light in the first wavelength region λ1; a light-emitting component 22 capable of emitting light in a second wavelength region λ2 that is shorter than the first wavelength region λ1; and a pressure-sensitive adhesive whose adhesive strength changes upon absorbing light in the second wavelength region λ2. In this embodiment, the pressure-sensitive adhesive layer may also function as the wavelength converting layer in the first embodiment. In one embodiment, the pressure-sensitive adhesive layer 40 may contain inorganic upconversion particles and / or molecules having a sensitizing group and a luminescent group in one molecule, instead of the sensitizing component 21 and the luminescent component 22. Furthermore, the sensitizing component (donor) capable of absorbing light in the first wavelength region λ1 and the luminescent component (acceptor) capable of emitting light in a second wavelength region λ2 having a shorter wavelength than the first wavelength region λ1 may be particles or crystals containing these.

[0114] D-1. Pressure-sensitive Adhesive Layer As described above, the pressure-sensitive adhesive layer contains a wavelength converting material. In one embodiment, the pressure-sensitive adhesive layer 40 includes a sensitizing component 21 capable of absorbing light in a first wavelength region λ1; a light-emitting component 22 capable of emitting light in a second wavelength region λ2, which has a wavelength shorter than the first wavelength region λ1; and a pressure-sensitive adhesive whose adhesive strength changes upon absorbing light in the second wavelength region λ2. In this embodiment, the sensitizing component 21 and the light-emitting component 22 are dispersed in the pressure-sensitive adhesive layer. For example, if the pressure-sensitive adhesive layer includes a photopolymerization initiator, the photopolymerization initiator may be activated by absorbing light in the second wavelength region λ2 and react with the curing component contained in the pressure-sensitive adhesive layer, thereby reducing the adhesive strength of the pressure-sensitive adhesive layer. The pressure-sensitive adhesive layer whose adhesive strength changes upon absorbing light in the second wavelength region λ2 may be formed using any suitable pressure-sensitive adhesive. For example, an active energy ray-curable pressure-sensitive adhesive may be used.

[0115] The thickness of the pressure-sensitive adhesive layer can be set to any appropriate thickness. The thickness of the pressure-sensitive adhesive layer is preferably 5 μm to 500 μm, more preferably 10 μm to 300 μm, and even more preferably 20 μm to 100 μm. When the thickness of the pressure-sensitive adhesive layer is within the above range, it can exert sufficient adhesive strength to the adherend.

[0116] The adhesives used to form the adhesive layer may be any of those described in the above item B.

[0117] D-1-1. Wavelength Converting Material Any appropriate wavelength converting material can be used as the wavelength converting material (sensitizing component and luminescent component) that can be contained in the adhesive layer. The sensitizing component and luminescent component that can be contained in the adhesive layer include those exemplified in Section B above, and combinations thereof. Furthermore, inorganic upconversion particles and materials in which an organic dye required for upconversion is encapsulated in an inorganic material may also be used as the wavelength converting material.

[0118] Any suitable inorganic particles can be used as the inorganic upconversion particles depending on the first wavelength region λ1 and the second wavelength region λ2. Examples of lanthanoids constituting the inorganic upconversion particles include rare earth elements that can be excited by light with wavelengths within a predetermined range to emit upconversion light. Examples include erbium (Er), holmium (Ho), praseodymium (Pr), thulium (Tm), neodymium (Nd), gadolinium (Gd), europium (Eu), ytterbium (Yb), samarium (Sm), and cerium (Ce). Holmium, thulium, ytterbium, gadolinium, and combinations thereof, which produce wavelengths in the ultraviolet light region, are preferred. Among these, lanthanoids with wavelengths of 10,000 cm －１A combination of ytterbium, which has strong absorption near the wavelength of 1000 nm, and at least one selected from holmium, thulium, and gadolinium, which emits light upon energy transfer from ytterbium and has a wavelength in the ultraviolet region, is preferred. The inorganic upconversion particles may be composed of a substance containing the above-mentioned lanthanoid, and may be composed of, for example, an oxide or halide such as a fluoride of the above-mentioned lanthanoid. The inorganic upconversion particles may also be sodium salts or potassium salts. These lanthanoids may be used alone or in combination of two or more. In addition to the rare earth elements capable of emitting light, lanthanoid ions, alkali metals, alkaline earth metals, etc. may also be doped. When doped, highly stable oxides and fluorides are preferred as hosts.

[0119] The inorganic upconversion particles may further contain an element or a compound thereof having an ionic radius or a structure upon crystallization similar to that of lanthanoids. For example, rare earth elements other than lanthanoids and metal elements may be mentioned, specifically yttrium (Y), scandium (Sc), tungsten (W), etc. The rare earth elements other than lanthanoids may be oxides, halides, etc. of rare earth elements other than lanthanoids. The metal elements may be oxides of metal elements. The inorganic upconversion particles preferably contain yttrium (Y), yttrium oxide, or yttrium halide. If these are contained, high efficiency in energy transfer between lanthanoids can be expected, and luminous efficiency can be improved. Yttrium oxide is Y ２ O ３ is preferred, and the yttrium halide is NaYF ４ The oxide of tungsten is preferably (WO ４ ) ２ is preferred.

[0120] The inorganic upconversion particles may have a coating layer that coats the inorganic particles. The coating layer may contain any suitable additives, such as an amphiphilic polymer, a photosensitizer, an antioxidant, a light stabilizer, a surfactant, a flame retardant, an antistatic agent, a moisture-resistant agent, a heat-reflecting agent, or a heat-absorbing agent.

[0121] Inorganic upconversion particles can be prepared by any suitable method. For example, a method including the steps of preparing lanthanoid-containing inorganic particles having an upconversion function, adding an amphiphilic polymer to a dispersion containing the obtained lanthanoid-containing inorganic particles having an upconversion function, and adding a silica precursor and a photosensitizer to the dispersion can be used. Such inorganic upconversion particles are disclosed, for example, in JP 2018-172253 A. The disclosure of this publication is incorporated herein by reference.

[0122] Hardness E of adhesive layer measured by nanoindentation method ３ is as described above. The hardness E of the pressure-sensitive adhesive layer measured by the nanoindentation method after absorbing light in the second wavelength region λ2 is ４ is the above hardness E ３ Specifically, the hardness E measured by the nanoindentation method is 5 times or more. ４ is preferably 1 MPa to 30 MPa, more preferably 1.5 MPa to 20 MPa, and even more preferably 2 MPa to 20 MPa. ４ If the viscosity is within the above range, adhesive residue on the adherend can be suppressed and the adhesive can be easily peeled off.

[0123] D-2. Substrate The substrate can be any of the substrates exemplified in Section B above. As described above, in this embodiment, the pressure-sensitive adhesive layer can also function as a wavelength conversion layer. Therefore, even when a substrate exemplified in Section B above is used, a pressure-sensitive adhesive sheet that can exert the designed adhesive strength can be provided.

[0124] E. Method for Producing Pressure-Sensitive Adhesive Sheets The pressure-sensitive adhesive sheets of the present invention can be produced by any suitable method. For example, the pressure-sensitive adhesive sheet of the first embodiment can be obtained by preparing an oil-in-water emulsion from an aqueous solution of a water-soluble resin and an oil-based solvent solution or oil-based solvent dispersion of a sensitizing component and a light-emitting component, or by preparing a water-in-oil emulsion from an oil-based solvent solution of an oil-soluble resin and an aqueous dispersion of a sensitizing component and a light-emitting component, applying the resulting emulsion to a substrate and drying it to form a wavelength-converting layer, and then forming a pressure-sensitive adhesive layer using a pressure-sensitive adhesive. Alternatively, a pressure-sensitive adhesive layer formed on any release liner may be transferred to the formed wavelength-converting layer. Methods for preparing emulsions and producing wavelength-converting layers are disclosed, for example, in International Publication No. 2003 / 074040. The disclosure of this publication is incorporated herein by reference.

[0125] The PSA sheet of the second embodiment can be formed by applying a composition obtained by mixing the sensitizing component, the light-emitting component, and the PSA by any suitable method to a substrate and drying the composition. Alternatively, the PSA layer can be formed on any release liner using the composition, and then transferred to the substrate.

[0126] F. Electronic Component Temporary Fixing Sheet The pressure-sensitive adhesive sheet of an embodiment of the present invention can be used for any suitable application. For example, it can be suitably used as a sheet for temporarily fixing electronic components, a sheet for transferring electronic components, etc. As described above, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet of an embodiment of the present invention is formed from a pressure-sensitive adhesive whose adhesive strength changes when it absorbs light in the second wavelength region λ2. Therefore, the adhesive strength can be changed (e.g., reduced) by irradiating the pressure-sensitive adhesive sheet with any suitable light. Reducing the adhesive strength of the pressure-sensitive adhesive layer can reduce adhesive residue on the surface of the adherend and can also reduce damage to electronic components during peeling.

[0127] G. Electronic Component Processing Method The electronic component temporary fixing sheet including the pressure-sensitive adhesive sheet according to the embodiment of the present invention can be used in any suitable electronic component processing step. The electronic component processing method according to the embodiment of the present invention includes the steps of attaching an electronic component to a pressure-sensitive adhesive layer provided on the electronic component temporary fixing sheet, performing a predetermined processing on the electronic component attached to the pressure-sensitive adhesive layer, and irradiating a wavelength conversion layer or a pressure-sensitive adhesive layer containing a sensitizing component and a light-emitting component provided on the electronic component temporary fixing sheet with light in a first wavelength region λ1 to emit light in a second wavelength region λ2, and peeling the electronic component that has been subjected to the predetermined processing from the pressure-sensitive adhesive layer that has absorbed the light in the second wavelength region λ2. Examples of electronic components include semiconductor chips, LED chips, and MLCCs.

[0128] The electronic components can be peeled off selectively at their positions. Specifically, a plurality of electronic components are attached and fixed to the electronic component temporary fixing sheet, and then some of the electronic components are peeled off while the remaining electronic components remain fixed.

[0129] In one embodiment, the method for treating an electronic component according to the embodiment of the present invention includes applying a predetermined treatment to the electronic component after the electronic component is attached to the electronic component temporary fixing sheet and before the electronic component is peeled off from the electronic component temporary fixing sheet. The treatment is not particularly limited, and examples thereof include grinding, dicing, die bonding, wire bonding, reflow, hybrid bonding, TSV (Through Silicon Via), etching, vapor deposition, molding, circuit formation, inspection, testing, cleaning, transfer, alignment, repair, and device surface protection.

[0130] The size of the electronic component (area of ​​the adhesive surface) is, for example, 1 μm ２ ~250,000 μm ２ In one embodiment, the size of the electronic component (area of ​​the attachment surface) is 1 μm ２ ~6400μm ２ In another embodiment, an electronic component having a size (area of ​​the attachment surface) of 1 μm can be subjected to the treatment. ２ ~2500μm ２of electronic components can be subjected to processing.

[0131] In one embodiment, a plurality of electronic components can be arranged on the sheet for temporarily fixing electronic components. The intervals between the electronic components are, for example, 1 μm to 500 μm. The present invention is advantageous in that the intervals can be narrowed to temporarily fix the object to be treated.

[0132] After the predetermined treatment of the predetermined electronic component, the wavelength conversion layer or the pressure-sensitive adhesive layer containing the sensitizing component and the light-emitting component provided in the electronic component temporary fixing sheet is irradiated with light in the first wavelength region λ1 to emit light in the second wavelength region λ2, and the electronic component subjected to the predetermined treatment is peeled off from the pressure-sensitive adhesive layer that has absorbed the light in the second wavelength region λ2. Any appropriate means can be used to irradiate the light in the first wavelength region λ1, depending on the first wavelength region λ1. Examples include a halogen lamp, black light, mercury lamp, high-power laser, and laser light irradiator capable of irradiating lasers such as fiber lasers (e.g., high-power continuous irradiation laser, femtosecond pulse laser, nanosecond pulse laser, fiber laser, laser pointer). The irradiation time of the light in the first wavelength region λ1 can be set to any appropriate value. For example, the integrated light amount on the pressure-sensitive adhesive layer can be set to a predetermined value. Furthermore, the irradiation position can be controlled in combination with a galvanometer scanner to uniformly irradiate a certain area. The intensity of the laser may be further increased by focusing it with a lens or the like.

[0133] In one embodiment, the method for treating an electronic component may further include, after the electronic component is peeled off, placing the electronic component on another sheet (for example, an adhesive sheet, a substrate, or the like).

[0134] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, "parts" and "%" in the examples are by weight.

[0135] Example 1 Synthesis of Upconversion (UC) Dye 1 (3,7,11-tris(3,6-di-tert-butyl-9H-carbazol-9-yl)quinolino[3,2,1-de]acridine-5,9-dione) 3,7,11-Tribromoquinolino[3,2,1-de]acridine-5,9-dione (DiKTPABr) (0.10 g, 0.187 mmol, 1.0 equivalent), 3,6-di-tert-butyl-9H-carbazole (Di-tert-butyl-CBz) (0.21 g, 0.74 mmol, 4.0 equivalent), sodium tert-butoxide (NaOtBu) (0.09 g, 0.936 mmol, 5.0 equivalent), tris(dibenzylideneacetone)dipalladium(0) (Pd ２ (dba) ３ ) (36 mg, 0.0374 mmol, 0.2 equivalents), tri-tert-butylphosphonium tetrafluoroborate (P( ｔ Bu) ３ HBF ４ ) (22 mg, 0.074 mmol, 0.4 equivalents) was stirred in dry toluene (15 mL) at reflux for 18 hours (room temperature). After completion of the reaction, the reaction mixture was passed through a silica gel plug (eluted with dichloromethane). The filtrate was then collected and concentrated to obtain a red solid. The resulting red solid was then purified by flash chromatography (hexane:toluene) and reprecipitated in methanol to obtain UC dye 1 (red solid), a sensitizing component (0.15 g, yield 72%). Mass spectrometry of the resulting UC dye 1 was performed using MS (LCMS, Shimadzu Corporation, product name "LCMS-2020 Single Quadrupole", eluent: methanol / water). The chemical formula (C ８０ H ８１ N ４ O ２ ([M+H]) ＋ The molecular weight calculated from the NMR spectroscopy was 1129, and the molecular weight detected by LCMS was 1129. In addition, a nuclear magnetic resonance spectrometer (manufactured by Bruker, product name "Bruker Avance III 400 MHz Spectrometer") １ H-NMR (400MHz, CDCl ３The structure was confirmed using the HCl (HCl) HCl (HCl) HCl (HCl). The proton chemical shifts were measured in the deuterated solvent CDCl. ３ The residual proton signal at 7.26 ppm was used as the reference for calculation. The results were δ 9.05 (s, 2H), 8.79 (d, J = 2.6 Hz, 2H), 8.54 (d, J = 9.0 Hz, 2H), 8.20 (d, J = 2.0 Hz, 6H), 8.05 (dd, J = 9.0, 2.6 Hz, 2H), and 7.62-7.41 (m, 12H).

[0136] Example 2 Synthesis of upconversion (UC) dye 2 (3,7,11-tri(10H-phenothiazin-10-yl)quinolino[3,2,1-de]acridine-5,9-dione) (Synthesis of Intermediate 1) Aniline (1.0 g, 10.73 mmol, 1.0 equivalent), 4-bromobenzonitrile (1.95 g, 10.73 mmol, 1.0 equivalent), sodium tert-butoxide (3.09 g, 32.21 mmol, 3.0 equivalent), palladium(II) acetate (Pd(OAc) ２ ) (0.24 g, 1.07 mmol, 0.1 equivalents), 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl (BINAP) (0.33 g, 0.53 mmol, 0.05 equivalents) were stirred in dry toluene (40 mL) at reflux for 16 hours (room temperature). After the reaction was completed, the resulting reaction mixture was passed through a silica gel plug (eluted with toluene). The filtrate was then recovered. The recovered filtrate was subjected to flash chromatography (hexane:CH ２ Cl ２ , 40:60 (v / v)) to obtain Intermediate 1 (0.56 g, yield 52.3%). Mass spectrometry of Intermediate 1 was performed using MS (LCMS, manufactured by Shimadzu Corporation, product name "LCMS-2020 Single Quadrupole", eluent: methanol / water). １３ H １１ N ２ ([M+H]) ＋ The molecular weight calculated from the NMR spectroscopy was 195, and the molecular weight detected by LCMS was 195. In addition, a nuclear magnetic resonance spectrometer (manufactured by Bruker, product name "Bruker Avance III 400 MHz Spectrometer") １H-NMR (400MHz, CDCl ３ The structure was confirmed using the HCl (HCl) HCl (HCl) HCl (HCl). The proton chemical shifts were measured in the deuterated solvent CDCl. ３ The residual proton signal at 7.26 ppm was used as the reference for calculation. The results were δ 7.51-7.44 (m, 2H), 7.36 (t, J = 7.9 Hz, 2H), 7.22-7.07 (m, 3H), 7.03-6.93 (m, 2H), and 6.04 (s, 1H). (Synthesis of UC dye 2) 3,7,11-tribromoquinolino[3,2,1-de]acridine-5,9-dione (DiKTPABr) (0.15 g, 0.28 mmol, 1.0 equivalent), intermediate 1 (4-(phenylamino)benzonitrile) (0.22 g, 1.12 mmol, 4.0 equivalent), sodium tert-butoxide (0.13 g, 1.40 mmol, 5.0 equivalent), tris(dibenzylideneacetone)dipalladium(0) (Pd ２ (dba) ３ ) (52 mg, 0.056 mmol, 0.2 equivalents), tri-tert-butylphosphonium tetrafluoroborate (P( ｔ Bu) ３ HBF ４ ) (33 mg, 0.11 mmol, 0.4 equivalents) was stirred in dry toluene (20 mL) at reflux for 16 hours (room temperature). The resulting reaction mixture was passed through a silica gel plug (eluted with dichloromethane). The filtrate was then collected and concentrated to give a red solid. The resulting red solid was then purified by flash chromatography (7% ethyl acetate in toluene) to give UC dye 2, a sensitizing component (red solid, 0.15 g, yield 61%). Mass spectrometry of the resulting UC dye 2 was performed using MS (LCMS, Shimadzu Corporation, product name "LCMS-2020 Single Quadrupole", eluent: methanol / water). The compound represented by the chemical formula (C ５９ H ３６ N ７ O ２ ([M+H]) ＋ The molecular weight calculated from the NMR spectroscopy was 874, and the molecular weight detected by LCMS was 874. In addition, a nuclear magnetic resonance spectrometer (manufactured by Bruker, product name "Bruker Avance III 400 MHz Spectrometer") １H-NMR (400MHz, CDCl ３ The structure was confirmed using the HCl (HCl) HCl (HCl) HCl (HCl). The proton chemical shifts were measured in the deuterated solvent CDCl. ３ The residual proton signal at 7.26 ppm was used as the reference for calculation. The results were δ 8.49 (s, 2H), 8.17 (d, J = 2.8 Hz, 2H), 8.10 (d, J = 9.2 Hz, 2H), 7.57-7.46 (m, 8H), 7.46-7.34 (m, 6H), 7.26 (d, J = 7.5 Hz, 3H), 7.24-7.14 (m, 7H), 7.14-7.05 (m, 4H), and 7.02 (d, J = 8.7 Hz, 2H).

[0137] Example 3 Synthesis of upconversion (UC) dye 3 (6-iodo-1,2,3,4,5-pentakis(3,6-di-tert-butylcarbazol-9-yl)benzene) (Synthesis of Intermediate) 3,6-Di-tert-butylcarbazole (BCz, 4.61 g, 16.5 mmol, 5.5 equiv.) and potassium tert-butoxide (t-BuOK) (1.85 g, 16.5 mmol, 5.5 equiv.) were dissolved in DMF (60 mL) at room temperature. After stirring for 30 minutes, 3,4,5-pentafluoro-6-iodobenzene (0.88 g, 3.0 mmol, 1.0 equiv.) was added to the solution. The mixture was stirred at 100°C for 12 hours and then cooled to room temperature. The resulting reaction mixture was then poured into a large amount of water. The product was then extracted with chloroform, and the combined organic layer was dried over anhydrous sodium sulfate. After filtration and evaporation, the crude product was purified by recrystallization from chloroform / methanol to give compound b (2.82 g, 59% yield) as a white solid. (Synthesis of UC dye 3) To a solution of the intermediate (3.18 g, 2.0 mmol, 1.0 equivalent) in tert-butylbenzene, n-butyllithium (n-BuLi) (1.6 M in hexane, 1.9 mL, 3.0 mmol) was slowly added at 0°C. After reacting for 4 hours at room temperature, boron tribromide (BBr ３ ) (0.29 mL, 3.0 mmol) was added slowly at 0°C, and the mixture was stirred at room temperature for 12 hours. ２) (0.8 mL) was added at 0°C, and the reaction mixture was further stirred at 170°C for 24 hours. After that, it was cooled to room temperature, and the reaction mixture was carefully quenched by adding water. The product was extracted with dichloromethane, and the combined organic layers were dried over anhydrous sodium sulfate. After filtration and evaporation, the crude product was purified by silica gel column chromatography (eluent: hexane / chloroform = 9:1, v / v), and then recrystallized from chloroform / methanol to obtain the sensitizing component UC dye 3 (0.67 g, yield 36%). A nuclear magnetic resonance spectrometer (manufactured by Bruker, product name "Bruker Avance III 400 MHz Spectrometer") was used. １ H-NMR (400MHz, CDCl ３ )) was used to confirm the structure of UC dye 3. The results obtained were as follows: １ H-NMR (400MHz, CDCl ３ ): δ8.78 (d, J=2.0Hz, 2H), 8.35 (d, J=1.6Hz, 2H), 7.71 (d, J=2.0Hz, 2H), 7.35 (d, J = 2.0Hz, 4H), 7.22 (d, J = 9.2Hz, 2H), 7.18 (d, J = 1.6Hz, 2H), 6.53 (dd, J = 8.6, 1.8H z, 4H), 6.43 (d, J = 8.4Hz, 4H), 6.32 (dd, J = 8.8, 2.0Hz, 2H), 6.10 (dd, J = 8.8Hz, 2H) , 5.85 (d, J=8.8Hz, 2H), 1.69 (s, 18H), 1.23 (s, 18H), 1.21 (s, 36H), 1.08 (s, 18H). １３ C{ １ H}NMR (100MHz, CDCl ３): δ145.85, 145.02, 143.32, 143.27, 141.92, 141.13, 139.63, 138.24, 13 7.89, 137.65, 128.85, 125.77, 125.13, 124.24, 123.48, 122.48, 122.23, 1 21.85, 121.58, 120.94, 115.56, 115.23, 114.94, 114.78, 114.32, 109.51, 109.04, 108.98, 35.26, 34.24, 34.20, 34.18, 32.20, 31.90, 31.76, 31.36. Mass spectrometry of the obtained UC dye 3 was performed using MS (MALDI-TOF, manufactured by Bruker, product name "Bruker Daltonics Autoflex III Spectrometer"). MS (MALDI-TOF): m / z calculated value 1471.95, [M] ＋ Measured value 1471.37, analytical calculated value (%) C １０６ H １１８ BN ５ : C86.44, H8.08, N4.75, Detected values: C86.31, H8.05, N4.70.

[0138] Example 4 Synthesis of upconversion (UC) dye 4 (3,7,11-tris(diphenylamino)quinolino[3,2,1-de]acridine-5,9-dione) According to the method described in S. Madayanad Suresh, D. Hall, D. Beljonne, Y. Olivier, E. Zysman-Colman, Adv. Funct. Mater. 2020, 30, 1908677, four steps of Ullmann coupling, bromination, hydrolysis, and Friedel-Crafts acylation were carried out to obtain Intermediate 1. The obtained Intermediate 1 (600 mg, 1.12 mmol, 1 equivalent), diphenylamine (856 mg, 5.06 mmol, 4.5 equivalents), tris(dibenzylideneacetone)dipalladium (Pd ２ (dba) ３ ) (206 mg, 0.23 mmol, 0.2 equivalents), tri-tert-butylphosphonium tetrafluoroborate (P(t-Bu) ３ HBF ４) (91 mg, 0.45 mmol, 0.4 equiv.), sodium tert-butoxide (t-BuONa) (646 mg, 6.72 mmol, 6.0 equiv.), and 15 mL of dry toluene were added to a 50 mL Schlenk tube and placed under a nitrogen atmosphere. The solution was heated to reflux and stirred for 24 hours. After cooling to room temperature, 50 mL of dichloromethane (DCM) was added to the reaction mixture. The organic phase was collected and washed three times with brine (50 mL). The solvent was then removed under reduced pressure. The crude product was purified by silica gel column chromatography (ethyl acetate (EtOAc):hexane = 1:15). The corresponding fractions were combined and concentrated under reduced pressure to give UC dye 4 (550 mg, yield: 61%), a deep red solid, which is the sensitizing component. It had an Rf value of 0.35 (EtOAc:hexane = 1:6). Nuclear magnetic resonance apparatus (manufactured by Bruker, product name "Bruker Avance III 400 MHz Spectrometer") １ H-NMR (500MHz, CDCl ３ ), １３ C-NMR (126MHz, CDCl ３ )) was used to confirm the structure of UC dye 4. １ H-NMR spectrum and １３ C-NMR spectra were obtained using a Bruker Avance spectrometer ( １ H is 500MHz, １３ C was recorded at 126 MHz. １ H and １３ C NMR spectra were referenced to the solvent peak. １ H-NMR (500MHz, CDCl ３ ) δ8.44 (s, 2H), 8.04 (dd, J = 17.4, 6.0Hz, 4H), 7.42 (dd, J = 9.2, 2.8Hz, 2H), 7.31 (dt, J = 10.3, 5.1Hz, 12H), 7.17 (d, J = 7.6Hz, 8H), 7.14-7.09 (m, 8H), 7.08 (d, J = 7.4Hz, 2H). １３ C-NMR (126MHz, CDCl ３) δ 177.70, 147.10, 146.04, 145.02, 144.17, 134.23, 134.15, 129.70, 129.05, 127.80, 127.06, 126.91, 124.73, 124.41, 124.31, 123.82, 123.76, 121.37, 119.29. In addition, analysis was performed by HPLC (Shimadzu Corporation, product name "LCMS-40 HPLC", eluent: methanol / water) (purity 97.87%, analysis with a retention time of 8.3 minutes in 95% methanol and 5% water). C ５６ H ３８ N ４ O ２ Calculated values ​​were C, 84.19%; H, 4.79%; N, 7.01%. Found values ​​were C, 83.74%; H, 4.84%; and N, 6.63%.

[0139] Example 5 Synthesis of upconversion (UC) dye 5 (1,4-bis((3-(3,6-di-tert-butyl-9H-carbazol-9-yl)phenyl)thio)benzo-di-borane) Synthesis of Intermediate 1: A solution of 1,4-benzenedithiol (1.0 g, 7.0 mmol, 1.0 equivalent), cesium carbonate (5.9 g, 18.1 mmol, 2.6 equivalent), 1-bromo-2,6-difluorobenzene (3.0 g, 15.4 mmol, 2.2 equivalent), and dry N,N-dimethylformamide (DMF) (40 mL) was stirred at 120°C for 16 hours. The mixture was cooled to room temperature, and water (10 mL) was added. The aqueous layer was then extracted with dichloromethane (3 x 30 mL). The combined organic layer was washed with water (50 mL) and evaporated under reduced pressure to obtain the crude product. The residue was purified by flash chromatography (petroleum ether / dichloromethane = 20:1) to obtain Intermediate 1 (1.7 g, 50% yield) as a white powder. Synthesis of Intermediate 2: A mixture of Intermediate 1 (2.0 g, 4.1 mmol, 1.0 equiv.), cesium carbonate (3.5 g, 10.7 mmol, 2.6 equiv.), 3,6-di-tert-butylcarbazole (2.5 g, 9.0 mmol, 2.2 equiv.), and dry dimethylacetamide (DMAC) (40 mL) was stirred at 185°C for 24 hours. The mixture was then cooled to room temperature, water (100 mL) was added, and the aqueous layer was extracted with dichloromethane (3 x 30 mL). The combined organic layer was washed with water (50 mL) and evaporated under reduced pressure to obtain the crude product. The residue was then purified by flash chromatography (petroleum ether / dichloromethane = 8:1) to obtain the crude product (Intermediate 2) (2.8 g) as a white powder, which was used in the synthesis of UC dye 5 without further purification. (Synthesis of UC dye 5) To a tert-butylbenzene solution of the brominated compound (intermediate 2) (1.0 g), n-butyllithium (n-BuLi) (1.6 M in hexane, 2.5 mL, 4.0 mmol) was slowly added at 0°C. After reacting at 80°C for 5 hours, boron tribromide (BBr ３ ) (0.8 mL, 8.0 mmol) was slowly added at -30°C, and the mixture was stirred at room temperature for 3 hours. Then, N-ethyldiisopropylamine (NEt(i-Pr) ２) (1.1 mL) was added, and the reaction mixture was further stirred at 190°C for 16 hours. After cooling to room temperature, saturated brine was added to carefully quench the reaction mixture. The product was extracted with dichloromethane, and the combined organic matter was dried over anhydrous sodium sulfate. After filtration and evaporation, the crude product was purified by silica gel column chromatography (eluent: hexane / chloroform = 20:1, v / v) and recrystallization from chloroform / methanol to obtain the sensitizing component UC dye 5 as a yellow solid (206 mg, yield 24%). A nuclear magnetic resonance spectrometer (Bruker, product name "ARX 400 NMR") was used. １ H-NMR (400MHz, CDCl ３ )) was used to confirm the structure of UC dye 5. １ H-NMR (400MHz, CDCl ３ ) δ9.02 (s, 1H), 8.67 (s, 1H), 8.43 (s, 1H), 8.37 (d, J = 8.3Hz, 1H), 8.31 (d, J = 8.7Hz, 1H), 8.22 (s, 1H), 7.98 (s, 2H), 7.78 (t, J=8.1Hz, 1H), 7.70 (s, 2H), 7 .64 (d, J=8.7Hz, 1H), 7.49 (dd, J=15.8, 7.6Hz, 3H), 7.41 (d, J=7.3Hz, 1H), 7 .35 (d, J=7.4Hz, 1H), 7.12 (s, 4H), 1.50 (s, 9H), 1.46 (s, 9H), 1.30 (s, 18H). １３ C NMR (101MHz, CDCl ３) δ 145.79, 145.21, 143.56, 143.16, 142.88, 142.73, 139.67, 139.31, 139. 06, 138.79, 137.85, 134.65, 131.80, 130.51, 130.35, 130.10, 127.17, 1 27.11, 126.45, 124.48, 124.34, 123.90, 123.50, 123.32, 121.31, 117.8 1, 117.44, 116.04, 114.15, 110.86, 109.10, 35.13, 34.55, 32.06, 31.84. The mass of UC dye 5 was analyzed using a high-resolution mass spectrometer (HRMS) (MALDI-TOF, manufactured by Bruker, product name "MICROTOF-Q III instrument"): m / z [M] ＋ C ５８ H ５７ BN ２ S ２ Calculated value: 857.038, measured value: 856.644.

[0140] Example 6: Upconversion (UC) dye 6 (6,9-di-tert-butyl-N １６ , N １６ , N １９ , N １９ Synthesis of -tetraphenyl-3b,10b,13b-triaza-20b boradifluoreno[1,9-ab:1',9'-jk]perylene-16,19-diamine (Intermediate 1 (9-(3-bromo-2-chlorophenyl)-N ３ , N ３ , N ６ , N ６ Synthesis of N-tetraphenyl-9H-carbazole-3,6-diamine (CzDPABrCl)) was prepared according to the method described in H. J. Kim, M. Godumala, S. K. Kim, J. Yoon, C. Y. Kim, H. Park, J. H. Kwon, M. J. Cho, D. H. Choi, Adv. Optical Mater. 2020, 8, 1902175. ３ , N ３ , N ６ , N ６1-tetraphenyl-9H-carbazole-3,6-diamine (CzDPA) was synthesized. Next, a mixture of 1-bromo-2-chloro-3-fluorobenzene (2.1 g, 10.0 mmol), CzDPA (5.0 g, 10.0 mmol), and cesium carbonate (4.9 g, 15.0 mmol) was dissolved in dry N,N-dimethylformamide (5 mL). After stirring overnight at 120°C, the suspension was mixed with dichloromethane and washed four times with water. After drying over anhydrous sodium sulfate, the organic phase was concentrated, and the crude product was purified by column chromatography to obtain intermediate 1 (CzDPABrCl) (yield 68%). (Intermediate 2 (9-(2-chloro-3-(7,10-di-tert-butyl-5H-indolo[3,2,1-de]phenazin-5-yl)phenyl)-N ３ , N ３ , N ６ , N ６ Synthesis of IPCzDPA (tetraphenyl-9H-carbazole-3,6-diamine) Intermediate 1 (5.17 g, 5.0 mmol), 1-bromo-2,3-dichlorobenzene (1.13 g, 5.0 mmol), 9,9-bis(3,5-di-tert-butylphenyl)-9,10-dihydroacridine (3.35 g, 6.0 mmol), and palladium(II) acetate (Pd(OAc) ２ ) (0.02 g, 0.1 mmol) and tri-tert-butylphosphine tetrafluoroborate ((t-Bu) ３ PHBF ４A mixture of 2-(2-methyl-2-propanol)-3-one (0.06 g, 0.2 mmol) and sodium tert-butoxide (t-BuONa) (0.63 g, 6.6 mmol) was added to dry toluene (10 mL) under an argon atmosphere. The reaction mixture was refluxed overnight and then cooled to room temperature. The resulting suspension was then thoroughly mixed with dichloromethane and washed three times with water. The organic phase was dried over anhydrous sodium sulfate, filtered, and concentrated under reduced pressure. The crude product was purified by column chromatography to obtain Intermediate 2 (76% yield) as a white solid. (Synthesis of UC Dye 6) Intermediate 2 (5.17 g, 5.0 mmol) was dissolved in dry tert-butylbenzene (t-BuPh) (10 mL) under an argon atmosphere to obtain a mixture. tert-Butyllithium (t-BuLi) in n-pentane (8.4 mL, 1.3 M, 11 mmol) was slowly added to the mixture at -30 °C. After stirring at 60°C for 1 hour, n-pentane was removed under vacuum. The reaction mixture was then cooled to -30°C and treated with boron tribromide (BBr ３ ) (0.71 mL, 7.5 mmol) was added to the reaction mixture. The resulting reaction mixture was stirred at room temperature for 1 hour. The mixture was heated to 130°C, and N,N-diisopropylethylamine (DIPEA) (1 mL) was added at 0°C, followed by stirring for 24 hours. The reaction mixture was then cooled to room temperature, and methanol was added to the reaction mixture to remove residual BBr. ３ The mixture was then diluted with dichloromethane and washed four times with water. The diluted solution was then dried over anhydrous sodium sulfate and concentrated under vacuum. The crude product was then purified by column chromatography to obtain UC dye 6 (yield 40%), an orange solid and a sensitizing component. １ H NMR: manufactured by Bruker, product name "Advanced II" １３ The structure of UC dye 6 was confirmed using C NMR (product name "Mercury VX300" manufactured by Varian). １ H NMR (400MHz, CD ２ Cl ２) δ (ppm): 8.53 (d, J = 2.1 Hz, 1H), 8.40 (d, J = 9.0 Hz, 1H), 8.22-8.13 ( m, 3H), 8.07 (d, J = 2.1Hz, 1H), 8.01-7.92 (m, 2H), 7.92-7.83 (m, 3H), 7.72 (s, 2H), 7.65-7.64 (m, 1H), 7.45-7.42 (m, 1H), 7.33-7.27 (m, 8H), 7.24-7.13 (m, 9H), 7.09-6.97 (m, 4H), 1.51 (s, 9H), 1.45 (s, 9H). １３ C NMR (100MHz, CD ２ Cl ２ ) δ (ppm): 148.50, 148.20, 146.23, 144.73, 144.56, 142.74, 142.55, 142.21, 140.62, 137.15, 136.60, 134.20, 132.80, 132.37, 130.94, 129.25, 129.20, 128.81, 128.25, 127.77, 126.42, 1 25.05, 124.62, 124.08, 123.48, 123.34, 123.05, 122.99, 122.37, 122.27, 122.01, 117.80, 117.47, 115.31, 114.15, 113.81, 112.08, 111.65, 110.06, 106.85, 35.19, 34.69, 31.61, 31.56. Mass spectrometry of the obtained UC dye 6 was performed using a high-resolution mass spectrometer (HRMS, ESI-MS, Thermo-Fisher Scientific, product name "LCQ-Orbitrap Elite"): m / z [M] ＋ : C ６８ H ５５ BN ５ The calculated value was 952.45450 and the measured value was 952.45453.

[0141] [Evaluation 1] Measurement of Emission Spectrum Wavelength conversion films were prepared using UC dyes 1 to 6 as the sensitizing component and the following compound (1,4-bis((triisopropylsilyl)ethynyl)naphthalate (TiPs-NaPh)) as the emitting component, and the emission spectrum was evaluated by the following method.

[0142] 1. Fabrication of Wavelength Conversion Film (Preparation of Sensitizing Component and Light-Emitting Component Solutions) In a glove box, the sensitizing component and the light-emitting component were dissolved in phenylcyclohexane to prepare a solution of the sensitizing component and the light-emitting component. In the solution, the concentration of the sensitizing component was 0.95 μM, and the concentration of the light-emitting component was 21.88 μM (molar ratio of sensitizing component to light-emitting component: 1:23). The prepared solution was sealed in a vial and stored until the emulsification process. (Preparation of Emulsion) 0.4 ml of the solution obtained above was added to 5 parts by weight of an aqueous solution (9 wt %) of polyvinyl alcohol (PVA, degree of polymerization 1700, degree of saponification 99%). While injecting the solution into a tube with an inner diameter of 0.75 mm, the solution was stirred (rotation speed 17,500 rpm) using a homogenizer (manufactured by EMERSON, product name "SFX550") until the entire solution was emulsified. Argon gas was blown into the resulting emulsion for approximately 2 minutes. Next, using a mixer (manufactured by THINKY Corporation, product name "Awatori Rentaro"), the mixture was stirred in mixing mode (2000 rpm) for 5 minutes, and then in degassing mode (2200 rpm) for 5 minutes to prepare an emulsion. (Formation of Wavelength Conversion Film) The above-mentioned aqueous solution of polyvinyl alcohol (PVA) (degree of polymerization 1700, degree of saponification 99%) (9 wt %) was applied to a polyimide (PI) film (manufactured by UBE Corporation, product name "Upilex S", thickness 125 μm) to a coating thickness of 750 μm, and dried in a thermostatic oven at 80° C. for 30 minutes to form a PVA resin layer. Next, the emulsion obtained above was applied to the formed PVA resin layer using an applicator to a coating thickness of 750 μm, and dried in a thermostatic oven at 80° C. for 30 minutes to form a wavelength conversion film. Thereafter, the wavelength conversion film was coated with a PVA aqueous solution to a coating thickness of 750 μm, and dried in a thermostatic oven at 80° C. for 30 minutes. Next, the PI film and the PVA film were peeled off to obtain a wavelength conversion film. After drying in each step, the laminate was naturally cooled to room temperature (23° C.). The steps after the preparation of the emulsion were carried out in air in a dark place (under an environment with only a darkroom light).

[0143] (Evaluation Method) Absolute Quantum Yield Measurement The upconversion luminescence absolute quantum yield (50% conversion) of the wavelength conversion films containing the prepared UC dyes 1 to 6 was measured using an absolute quantum yield measurement system (manufactured by Hamamatsu Photonics, product name "Quantaurus-QY Plus C11347-02"). For the absolute quantum yield measurement, a diode laser (532 nm, 75 mW; 980 nm, 2 W) was used as an excitation source, and the light intensity was adjusted using the laser output and an ND filter. For each sample, the irradiation intensity at 532 nm was 31,000 mW / cm. ２ , 980 nm has an irradiation intensity of 590,000 mW / cm ２ The measurement was carried out by adjusting the amount of light so that the light was irradiated so as to satisfy the following conditions.

[0144] The emission spectrum of the wavelength conversion film containing UC dye 1 is shown in Fig. 4, the emission spectrum of the wavelength conversion film containing UC dye 2 is shown in Fig. 5, the emission spectrum of the wavelength conversion film containing UC dye 3 is shown in Fig. 6, the emission spectrum of the wavelength conversion film containing UC dye 4 is shown in Fig. 7, the emission spectrum of the wavelength conversion film containing UC dye 5 is shown in Fig. 8, and the emission spectrum of the wavelength conversion film containing UC dye 6 is shown in Fig. 9. It was confirmed that the wavelength conversion films containing UC dyes 1 to 6 all have long absorption maxima, and the wavelength conversion films containing UC dyes 1 to 6 have absorption maxima at wavelengths of 460 nm or more (maximum absorption wavelength of 510 nm for UC dye 1, 510 nm for UC dye 2, 490 nm for UC dye 3, 510 nm for UC dye 4, 520 nm for UC dye 5, and 530 nm for UC dye 6).

[0145] [Evaluation 2] Measurement of Absorption or Transmission Spectrum The absorption or transmission spectra, fluorescence spectra, and phosphorescence spectra of UC dyes 1 to 6 were measured by the following method. The spectral diagrams (absorption spectra, fluorescence spectra, and phosphorescence spectra (77K)) of UC dyes 1 to 6 are shown in Figures 10 to 15.

[0146] 1. Method for measuring the absorption spectrum of a UC dye solution A 1 cm x 1 cm cell was placed in an ultraviolet-visible-infrared spectrophotometer (Shimadzu Corporation, product name "UV-3600i Plus") at room temperature in the atmosphere. Next, a 0.01 mM to 0.1 mM solution of UC dyes 1 to 6 (solvent: toluene) was placed in the cell, and the solution was irradiated with light of 300 nm to 800 nm. The light transmitted through the solution was detected, and the spectrum was evaluated. The concentration of the UC dye solution was adjusted to match the detection sensitivity of the analyzer.

[0147] 2. Method for measuring the fluorescence spectrum of a UC dye solution A 1 cm x 1 cm cell was placed in an ultra-high sensitivity multi-function fluorescence spectrophotometer (manufactured by Edinburgh, product name "FLS-1000 Instrument") at room temperature and in atmospheric air. Next, 0.01 mM to 0.1 mM solutions of UC dyes 1 to 6 (solvent: toluene) were placed in the cell, and the solution was irradiated with light (200 nm to 600 nm) within the absorption wavelength range of each UC dye. The light emitted from the solution (300 nm to 900 nm) was detected, and the spectrum was evaluated. The concentration of the UC dye solution was adjusted to match the detection sensitivity of the analyzer.

[0148] 3. Method for Measuring the Phosphorescence Spectrum of a UC Dye Solution A 1 cm x 1 cm cell was placed in an ultra-high sensitivity multi-function fluorescence spectrophotometer (manufactured by Edinburgh, product name "FLS-1000 Instrument") under atmospheric conditions at 77 K. Next, 0.01 mM to 0.1 mM solutions of UC dyes 1 to 6 (solvent: toluene) were placed in the cell, and the solution was irradiated with light (200 nm to 600 nm) within the absorption wavelength range of each UC dye. 100 μs after irradiation, the light emitted from the solution (300 nm to 900 nm) was detected, and the spectrum was evaluated. The concentration of the UC dye solution was adjusted to match the detection sensitivity of the analytical instrument.

[0149] [Evaluation 3] Measurement of absorption or transmittance spectrum of film (Preparation of sensitizing component and luminescent component solutions) In a glove box, a sensitizing component (UC dye 4) and a luminescent component (1,4-bis((triisopropylsilyl)ethynyl)naphthalene (Tips-Nap)) were dissolved in phenylcyclohexane to prepare a solution of the sensitizing component and the luminescent component. In the solution, the concentration of the sensitizing component was 0.95 μM, and the concentration of the luminescent component was 21.88 μM (molar ratio of sensitizing component:luminescent component: 1:23). The prepared solution was stored in a sealed vial until the emulsification step. (Preparation of emulsion) 0.4 ml of the solution obtained above was added to 5 parts by weight of an aqueous solution (9 wt %) of polyvinyl alcohol (PVA, degree of polymerization 1700, degree of saponification 99%). The solution was poured into the mixture using a tube with an inner diameter of 0.75 mm, and stirred using a homogenizer (manufactured by EMERSON, product name "SFX550") until the entire mixture was emulsified (rotation speed: 17,500 rpm). Argon gas was sprayed into the resulting emulsion for approximately 2 minutes. Next, using a mixer (manufactured by THINKY, product name "Awatori Rentaro"), the mixture was stirred for 5 minutes in mixing mode (rotation speed: 2,000 rpm), and then for 5 minutes in degassing mode (rotation speed: 2,200 rpm) to prepare an emulsion. (Formation of Wavelength Conversion Film) The above-mentioned aqueous solution of polyvinyl alcohol (PVA) (degree of polymerization 1700, degree of saponification 99%) (9% by weight) was applied to a polyimide (PI) film (manufactured by UBE, product name "Upilex S", thickness 125 μm) to a coating thickness of 750 μm, and dried in a thermostatic oven at 80° C. for 30 minutes to form a PVA resin layer. Next, the emulsion obtained above was applied to the formed PVA resin layer using an applicator to a coating thickness of 750 μm, and dried in a thermostatic oven at 80° C. for 30 minutes to form a wavelength conversion film. Thereafter, an aqueous PVA solution was applied to the wavelength conversion film to a coating thickness of 750 μm, and dried in a thermostatic oven at 80° C. for 30 minutes. Next, the PI film was peeled off, to obtain a laminate of PVA-based film / wavelength conversion film / PVA-based film (wavelength conversion film laminate). After drying in each step, the laminate was allowed to cool naturally to room temperature (23° C.) The steps after the preparation of the emulsion were carried out in air in a dark place (under an environment with only a darkroom light).

[0150] (Evaluation Method) The transmission spectrum of the wavelength conversion film laminate prepared by the above method was measured using an ultraviolet-visible-near-infrared spectrophotometer (manufactured by Hitachi High-Tech Corporation, product name "UH4150"). The measurement was carried out at a wavelength of 1000 nm or 200 nm. The transmission spectrum of the wavelength conversion film is shown in FIG. 16. UC dyes 2 to 6 can also be evaluated by the same method.

[0151] Absorption or transmittance spectrum measurement using an ultraviolet-visible-infrared spectrophotometer confirmed that UC dyes 1 to 6 had maximum absorption wavelengths of 460 nm or more. Furthermore, emission spectrum measurement of wavelength conversion films containing UC dyes 1 to 6 using an absolute quantum yield measurement system confirmed emission at 375 nm, which is shorter than 460 nm, and confirmed UC emission with a large anti-Stokes shift.

[0152] Example 7 1. Production of UV-curable pressure-sensitive adhesive layer-forming film <Preparation of prepolymer composition> A reaction vessel equipped with a cooling tube, a nitrogen inlet tube, a thermometer, and a stirrer was charged with 100 parts by weight of a monomer component containing 2-ethylhexyl acrylate (2EHA) and hydroxyethyl acrylate (HEA) in an amount such that the molar ratio of 2EHA to HEA was 100:20, and 65 parts by weight of toluene as a polymerization solvent, and 0.2 parts by weight of benzoyl peroxide was added as a thermal polymerization initiator, and a polymerization reaction (solution polymerization) was carried out at 61°C for 6 hours under a nitrogen atmosphere to obtain a solution containing an acrylic polymer a. To the resulting solution containing the acrylic polymer a, 16 moles of methacryloyloxyethyl isocyanate (MOI) was added to the 20 moles of HEA used as the monomer composition used in the polymerization of the acrylic polymer a, and the addition reaction treatment was carried out at 50 ° C. for 48 hours in an air stream, to obtain a solution of acrylic polymer A (solids content 41.2%) having a methacryloyl group at the side chain end. Next, to 100 parts by weight of the acrylic polymer A solution, 0.5 parts by weight of an isocyanate crosslinking agent (manufactured by Mitsui Chemicals, Inc. under the trade name "Takenate D-101E"), 5 parts by weight of a curing agent (dipentaerythritol hexaacrylate (DPHA), manufactured by Nippon Kayaku Co., Ltd., under the trade name "DPHA"), and 5 parts by weight of a photopolymerization initiator (manufactured by IGM Resins BV, under the trade name "Omnirad 651") were added and mixed uniformly to obtain an ultraviolet-curable adhesive composition. <Preparation of ultraviolet-curable pressure-sensitive adhesive layer-forming film> The pressure-sensitive adhesive composition was applied to the release-treated surface of a release-treated polyester film, dried at 80°C for 5 minutes in a thermostatic oven, and further aged at 50°C for 72 hours to prepare an ultraviolet-curable pressure-sensitive adhesive layer-forming film on which a pressure-sensitive adhesive layer having a thickness of 30 µm was formed.

[0153] 2. Fabrication of Wavelength Conversion Layer <Preparation of Sensitizing Component and Emitting Component Solutions> In a glove box, a sensitizing component (a compound represented by the following formula) and an emitting component (1,4-bis((triisopropylsilyl)ethynyl)naphthalene (Tips-Nap)) were dissolved in phenylcyclohexane to prepare a solution of the sensitizing component and the emitting component. In the solution, the concentration of the sensitizing component was 0.95 μM, and the concentration of the emitting component was 21.88 μM (molar ratio of sensitizing component:emitting component: 1:23). The prepared solution was stored in a sealed vial until the emulsification step.

[0154] <Preparation of Emulsion> 0.4 ml of the solution obtained above was added to 5 parts by weight of an aqueous solution (9 wt %) of polyvinyl alcohol (PVA, degree of polymerization 1700, degree of saponification 99%). While the solution was being poured into a tube with an inner diameter of 0.75 mm, the mixture was stirred using a homogenizer (manufactured by EMERSON, product name "SFX550") until the entire mixture was emulsified (rotation speed: 17,500 rpm). Argon gas was sprayed onto the resulting emulsion for approximately 2 minutes. Next, using a mixer (manufactured by THINKY, product name "Awatori Rentaro"), the mixture was stirred for 5 minutes in mixing mode (rotation speed: 2,000 rpm) and then for 5 minutes in degassing mode (rotation speed: 2,200 rpm) to prepare an emulsion.

[0155] <Formation of Wavelength Conversion Layer> The above-mentioned polyvinyl alcohol (PVA, degree of polymerization 1700, degree of saponification 99%) aqueous solution (9 wt %) was applied to a polyimide (PI) film (manufactured by UBE, product name "Upilex S," thickness 125 μm) to a coating thickness of 750 μm, and dried in a thermostatic oven at 80°C for 30 minutes to form a PVA resin layer. Next, the emulsion obtained above was applied to the formed PVA resin layer using an applicator to a coating thickness of 750 μm, and dried in a thermostatic oven at 80°C for 30 minutes to form a wavelength conversion layer. Thereafter, a PVA aqueous solution was applied to the wavelength conversion layer to a coating thickness of 750 μm, and dried in a thermostatic oven at 80°C for 30 minutes. Next, the PI film was peeled off to obtain a laminate of PVA film / wavelength conversion layer / PVA film (wavelength conversion layer laminate). After drying in each step, the laminate was allowed to cool naturally to room temperature (23° C.) The steps after the preparation of the emulsion were carried out in air in a dark place (under an environment with only a darkroom light).

[0156] 3. Preparation of Pressure-Sensitive Adhesive Sheet The UV-curable pressure-sensitive adhesive layer-forming film obtained above was attached to the wavelength-converting layer laminate to transfer the pressure-sensitive adhesive layer. The release-treated polyester film was then peeled off to obtain a substrate-free pressure-sensitive adhesive sheet (UV-curable pressure-sensitive adhesive layer / wavelength-converting layer laminate (PVA-based film / wavelength-converting layer / PVA-based film)).

[0157] Example 8 An optically transparent adhesive (OCA) sheet (manufactured by Nitto Denko Corporation, thickness 12 μm) was bonded to the wavelength conversion layer laminate obtained in the same manner as in Example 7, and a substrate (PI-based film, manufactured by AS ONE Corporation, product name "HJA50", thickness 50 μm, 532 nm transmittance 63%) was bonded to the wavelength conversion layer laminate via the adhesive layer of the OCA sheet, to obtain a pressure-sensitive adhesive sheet (substrate (PI-based film) / OCA / wavelength conversion layer laminate (PVA-based film / wavelength conversion layer / PVA-based film) / ultraviolet-curable pressure-sensitive adhesive layer) in the same manner as in Example 1. Note that the ultraviolet-curable pressure-sensitive adhesive layer was bonded to the side of the wavelength conversion layer where the PI-based film was not laminated.

[0158] Example 9 An ultraviolet-curable pressure-sensitive adhesive composition was prepared in the same manner as in Example 7, except that Omnirad 907 (manufactured by IGM Resins B.V., product name "Omnirad 907") was used as the photopolymerization initiator instead of Omnirad 651. A pressure-sensitive adhesive sheet (substrate (PI-based film) / OCA / wavelength-converting layer laminate (PVA-based film / wavelength-converting layer / PVA-based film) / ultraviolet-curable pressure-sensitive adhesive layer) was produced in the same manner as in Example 8, except that the obtained ultraviolet-curable pressure-sensitive adhesive composition was used.

[0159] Example 10 A pressure-sensitive adhesive sheet (substrate (PI film) / OCA / wavelength conversion layer / ultraviolet-curable pressure-sensitive adhesive layer) was obtained in the same manner as in Example 8, except that Nikkacure TG-10 (manufactured by Nippon Chemical Industry Co., Ltd., trade name "Nikkacure TG-10") was used instead of Omnirad 651 as the photopolymerization initiator, and a wavelength conversion layer laminate prepared by the following method was used as the wavelength conversion layer. <Preparation of emulsion> In a glove box, a sensitizing component (platinum octaethylporphyrin (PtOEP)) and a light-emitting component (9,10-diphenylanthracene (DPA)) were dissolved in a mixed solvent of 4'-pentyl-4-cyanobiphenyl and tetrahydrofuran (mixing ratio 1:1) to prepare a solution of the sensitizing component and the light-emitting component. In the solution, the concentration of the sensitizing component was 129 μM, and the concentration of the luminescent component was 630 nM (molar ratio of sensitizing component to luminescent component: 1:204). 0.4 ml of the solution obtained above was added to 5 parts by weight of an aqueous solution (9 wt %) of polyvinyl alcohol (PVA, degree of polymerization 1700, degree of saponification 99%). While the solution was being poured into a tube with an inner diameter of 0.75 mm, it was stirred using a homogenizer (manufactured by EMERSON, product name "SFX550") until the entire solution was emulsified (17,500 rpm). Argon gas was sprayed onto the resulting emulsion for approximately 2 minutes. Next, using a mixer (manufactured by THINKY, product name "Awatori Rentaro"), the mixture was stirred for 5 minutes in mixing mode (2,000 rpm) and then for 5 minutes in degassing mode (2,200 rpm) to prepare an emulsion.

[0160] <Formation of Wavelength Conversion Layer> The above polyvinyl alcohol (PVA) aqueous solution (polyvinyl alcohol (PVA), degree of polymerization 1700, degree of saponification 99%) aqueous solution (9 wt %)) was applied to a polyimide (PI) film (manufactured by UBE, product name "Upilex S", thickness 125 μm) to a coating thickness of 750 μm, and the PVA coating film / PI film laminate was dried in a thermostatic oven at 80° C. for 30 minutes. After drying, the laminate was allowed to cool naturally to room temperature. Next, the PI film was peeled off to obtain a wavelength conversion layer (thickness 50 μm).

[0161] Example 11 An ultraviolet-curable pressure-sensitive adhesive composition was prepared in the same manner as in Example 7, except that Nikkacure TG-10 (manufactured by Nippon Chemical Industry Co., Ltd., trade name "Nikkacure TG-10") was used instead of Omnirad 651 as the photopolymerization initiator, and an ultraviolet-curable pressure-sensitive adhesive layer-forming film was produced. In a glove box, a sensitizing component represented by the following formula and a light-emitting component (Tips-Nap) were dissolved in a mixed solvent of 4'-pentyl-4-cyanobiphenyl and tetrahydrofuran (mixing ratio 1:1) to prepare a solution of the sensitizing component and the light-emitting component. In the solution, the concentration of the sensitizing component was 0.95 μM, and the concentration of the light-emitting component was 21.88 μM (molar ratio of sensitizing component:light-emitting component: 1:23). 0.4 ml of the solution obtained above was added to 5 parts by weight of an aqueous solution (9 wt %) of polyvinyl alcohol (PVA, degree of polymerization 1700, degree of saponification 99%). While injecting the solution through a tube with an inner diameter of 0.75 mm, the solution was stirred with a homogenizer (manufactured by EMERSON, product name "SFX550") until the entire solution was emulsified (rotation speed: 17,500 rpm). Argon gas was sprayed into the resulting emulsion for approximately 2 minutes. Next, using a mixer (manufactured by THINKY, product name "Awatori Rentaro"), the mixture was stirred in mixing mode (rotation speed: 2,000 rpm) for 5 minutes, and then in degassing mode (rotation speed: 2,200 rpm) for 5 minutes to prepare an emulsion. A wavelength converting layer laminate (PVA-based film / wavelength converting layer / PVA-based film) was obtained in the same manner as in Example 7, except that the obtained emulsion was used. A pressure-sensitive adhesive sheet (substrate (PI-based film) OCA / wavelength-converting layer laminate (PVA-based film / wavelength-converting layer / PVA-based film) / ultraviolet-curable pressure-sensitive adhesive layer) was obtained in the same manner as in Example 8, except that the obtained wavelength-converting layer was used.

[0162] [Example 12] <Na(La,Yb,Tm)(WO ４ ) ２ Hydrothermal synthesis of Na(LaYb)(WO ４ ) ２ and (Na(LaYbTm)(WO ４ ) ２ ; Yb and Tm di-doped NaLa(WO ４ ) ２ , double tungstate (Na(LaYb)(WO ４ ) ２ The aqueous combustion synthesis of NaNO was carried out as follows: The following precursors and distilled deionized water (MiliQ) (Sigma-Aldrich, St. Louis, MO, USA) were collected in 20 mL vials and dissolved: (1) 1.77 g of NaNO ３ (2) 7.19 g of La(NO) ３ ) ３ ・6H ２ (3) 2.03 g of Yb(NO) ３ ) ３ ・xH ２ 0 in 5 mL of MiLiQ water (4) 25.1 mg of Tm(NO ３ ) ３ . xH ２ (5) 10.41 g of ammonium metatungstate hydrate in 10 mL of MilliQ water. (6) 4.06 g of ammonium nitrate in 5 mL of MilliQ water. These were then transferred to a 250 mL low-form glass beaker. 2.6 g of 3-methylpyrazol-5-one, 1 g of glycine, 0.59 g of maleic hydrazide, and 0.55 g of oxalic dihydrazide were added to the beaker and mixed. The resulting mixture was combusted in a furnace at 400 °C for 30 minutes to complete the combustion reaction. The combustion product was then crushed with a mortar and pestle, transferred to a small alumina crucible, and annealed in a furnace at 750 °C for 60 minutes. The powder was then rapidly cooled from 750 °C to room temperature to obtain inorganic particles.

[0163] The obtained adhesive composition was added with the inorganic upconversion particles (Na(LaYbTm)(WO ４ ) ２ A pressure-sensitive adhesive composition containing inorganic upconversion particles was obtained in the same manner as in Example 7, except that 1 wt % of an inorganic upconversion particle-containing ultraviolet-curable pressure-sensitive adhesive layer (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) and 0.1 wt % of a surfactant (trade name "Noigen ET109" manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) were added and mixed. The pressure-sensitive adhesive composition obtained was applied to a PI film (manufactured by AS ONE Corporation, product name "HJA50", thickness 50 μm, 980 nm transmittance: 88%) to a coating thickness of 300 μm, and dried at 100° C. for 5 minutes to obtain a pressure-sensitive adhesive sheet (substrate (PI film) / ultraviolet-curable pressure-sensitive adhesive layer containing inorganic upconversion particles).

[0164] Comparative Example 1 A substrate (PI-based film, manufactured by AS ONE Corporation, product name "HJA50", thickness 50 μm) was attached to the polyester film release surface of the pressure-sensitive adhesive layer in the same manner as in Example 7, except that the wavelength conversion layer was not formed, to obtain a pressure-sensitive adhesive sheet (ultraviolet-curable pressure-sensitive adhesive layer / substrate (PI-based film)).

[0165] Comparative Example 2: Inorganic particles, Na(LaYb)(WO ４ ) ２ A pressure-sensitive adhesive sheet (ultraviolet-curable pressure-sensitive adhesive layer containing inorganic particles / substrate (PI film)) was obtained in the same manner as in Example 12, except that these inorganic particles were used.

[0166] [Evaluation 4] The pressure-sensitive adhesive sheets prepared in the examples and comparative examples were evaluated as follows.

[0167] 1. 180° Peel Strength The pressure-sensitive adhesive sheets obtained in the Examples and Comparative Examples were cut to a width of 20 mm and a length of 100 mm, and the adhesive layer of the pressure-sensitive adhesive sheet was bonded to an alkali glass plate (manufactured by Matsunami Glass Industry Co., Ltd., 1.35 mm thick, polished blue plate edge) by rolling a 2 kg roller back and forth once under an environment of 23 ° C and 50% RH. Under the same environment, the alkali glass plate to which the pressure-sensitive adhesive sheet was bonded was left to stand for 6 hours and then evaluated. The evaluation sample was placed in a tensile tester (manufactured by Shimadzu Corporation, product name "EZ-S 500N") under an environment of 23 ° C and 50% RH, and the peel strength was measured when the pressure-sensitive adhesive sheet was peeled from the adherend at a peel angle of 180 degrees and a speed of 300 mm / min. In addition, a laser was irradiated from the wavelength conversion layer side of the evaluation sample prepared in the same manner using a galvanometer scanner under the conditions listed in Table 1. The peel strength of the sample after light irradiation was also measured in the same manner. The measurements were carried out for two samples each, and the average value was calculated. The results are shown in Table 2.

[0168] 2. Nanoindentation Hardness The nanoindentation hardness of the adhesive layer (ultraviolet-curable adhesive layer) was measured using a nanoindentation device (manufactured by Hysitron Inc., product name "Triboindenter TI-950"). The adhesive sheets obtained in the examples and comparative examples were cut into 2 cm x 2 cm pieces and used as samples. The displacement-load hysteresis curve obtained by pressing a diamond conical-type (spherical: radius 10 μm) probe perpendicularly against the adhesive layer surface on the peeled side of the sample's release-treated polyester film was numerically processed using the software (triboscan) attached to the measuring device to obtain a hardness value. The measurement was performed at 25 ° C. using a single indentation method under the measurement conditions of an indentation speed of approximately 500 nm / sec, a pull-out speed of approximately 500 nm / sec, and an indentation depth of approximately 3000 nm. In order to prevent the adhesive layer from curing, a 130 μm thick polyimide (PI) film was placed in front of the light source in the measurement environment, and the measurement was performed in a light-shielding environment. Similarly, samples prepared in the same manner were irradiated with light from the wavelength conversion layer side of the adhesive sheet using a galvanometer scanner under light irradiation condition 1 or light irradiation condition 2 described in Table 1. The nanoindentation hardness of the adhesive sheet after irradiation was similarly measured. Measurements were performed on three samples before and after light irradiation, and the average value was calculated. The results are shown in Table 2.

[0169] 3. Percent Change The percent change was calculated from the results of the 180° peel strength before and after light irradiation using the following formula: Percent change (%) = {(180° peel strength after light irradiation) / (180° peel strength before light irradiation)} × 100 The percent change was calculated from the results of the nanoindentation hardness before and after light irradiation using the following formula: Percent change (times) = (nanoindentation hardness after light irradiation) / (nanoindentation hardness before light irradiation)

[0170] 4. Absolute Quantum Yield Measurement The upconversion luminescence absolute quantum yield (50% conversion) of the wavelength conversion layer (inorganic upconversion particles or adhesive in the case of an adhesive layer containing inorganic particles) used in the examples and comparative examples was measured using an absolute quantum yield measurement system (manufactured by Hamamatsu Photonics, product name "Quantaurus-QY Plus C11347-02"). For absolute quantum yield measurement, a diode laser (532 nm, 75 mW, 980 nm, 2 W) was used as an excitation source, and the light intensity was adjusted using the laser output and an ND filter. The irradiation intensity of 532 nm was 31,000 mW / cm ２ , 980 nm has an irradiation intensity of 590,000 mW / cm ２ The light intensity was adjusted so that each sample was irradiated with light so that the measurement was performed.

[0171] 5. Transmittance Measurement The transmittance of the PI film was measured using an ultraviolet-visible-near-infrared spectrophotometer (Hitachi High-Tech Corporation, product name "UH4150"). For transmittance measurement, the sample was placed directly in front of an integrating sphere, and the total light transmittance was measured in wavelengths ranging from 400 nm to 1000 nm at 1 nm intervals. In this example, the transmittance at the laser irradiation wavelengths of 532 nm and 980 nm was extracted.

[0172]

[0173] The upconversion material of the embodiment of the present invention can be suitably used in applications such as solar cells, photocatalysts, natural light illumination, LEDs, organic EL elements, biomarkers, displays, printing, security authentication, optical data storage devices, and sensors. The pressure-sensitive adhesive sheet of the embodiment of the present invention can be used in any appropriate application. For example, it can be suitably used in the processing of electronic components such as semiconductor chips.

[0174] REFERENCE SIGNS LIST 10 Pressure-sensitive adhesive layer 20 Wavelength conversion layer 21 Sensitizing component 22 Light-emitting component 30 Substrate 40 Pressure-sensitive adhesive layer 100 Pressure-sensitive adhesive sheet 200 Pressure-sensitive adhesive sheet

Claims

1. An upconversion material comprising a sensitizer component capable of absorbing light in a first wavelength region λ1 and a light-emitting component capable of emitting light in a second wavelength region λ2 having a wavelength shorter than the first wavelength region λ1, wherein the sensitizer component comprises a fused polycyclic compound having structure (a), structure (b), structure (c), or structure (d): (wherein R represents a substituent other than a hydrogen atom).

2. The upconversion material according to claim 1, wherein the sensitizing component is a compound represented by the following formula (A), (B), (C), or (D): (In the formula, R １ represents a hydrogen atom or one of the following substituents: (In the formula, R ３０ ~R ６３ each independently represents a hydrogen atom or any of the following substituents: (R ２ ~R ２９ each independently represents a hydrogen atom or any of the following substituents: .

3. The upconversion material of claim 2, wherein the sensitizing component is any of the following compounds:

4. The upconversion material of claim 3, wherein the emissive component has one of the following structures: .

5. The upconversion material of claim 3, wherein the luminescent component is a compound represented by the following formula: (In the formula, R ６４ ~R ８１ each independently represents a hydrogen atom or one of the following substituents: .

6. A wavelength conversion layer that converts light in a first wavelength region λ1 into light in a second wavelength region λ2 that has a shorter wavelength than the first wavelength region λ1; and an adhesive layer that is disposed on one side of the wavelength conversion layer and changes adhesive strength by absorbing light in the second wavelength region λ2; wherein the hardness E of the adhesive layer measured by a nanoindentation method before absorbing light in the second wavelength region λ2 is １ is 0.01 MPa or more, and the hardness E of the pressure-sensitive adhesive layer after absorbing light in the second wavelength region λ2 as measured by a nanoindentation method is ２ However, the hardness E measured by the nanoindentation method １ Adhesive sheet that is more than five times thicker than the original.

7. Hardness E of the pressure-sensitive adhesive layer measured by nanoindentation method ２ The pressure-sensitive adhesive layer has a hardness E measured by a nanoindentation method. １ The pressure-sensitive adhesive sheet according to claim 6, wherein the pressure-sensitive adhesive sheet has a viscosity of 30 times or more and 1500 times or less relative to the pressure-sensitive adhesive sheet.

8. The adhesive sheet of claim 6, wherein the wavelength conversion layer contains a sensitizing component capable of absorbing light in the first wavelength region λ1 and a light-emitting component capable of emitting light in a second wavelength region λ2 that has a shorter wavelength than the first wavelength region λ1.

9. The pressure-sensitive adhesive sheet according to claim 6, wherein the wavelength-converting layer comprises inorganic upconversion particles.

10. The pressure-sensitive adhesive sheet according to claim 6, further comprising a substrate disposed on the opposite side of the wavelength conversion layer from the pressure-sensitive adhesive layer, wherein the transmittance of the substrate for light in the first wavelength region λ1 is 50% or more, and the transmittance of the substrate for light in the second wavelength region λ2 is 10% or less.

11. The pressure-sensitive adhesive sheet according to claim 6, wherein the 180° peel strength of the pressure-sensitive adhesive layer after absorbing light in the second wavelength region λ2 is 70% or less, where the 180° peel strength of the pressure-sensitive adhesive layer before absorbing light in the second wavelength region λ2 is taken as 100%.

12. A pressure-sensitive adhesive layer including: a wavelength converting material that converts light in a first wavelength region λ1 into light in a second wavelength region λ2 that has a shorter wavelength than the first wavelength region λ1; and a pressure-sensitive adhesive whose adhesive strength changes by absorbing light in the second wavelength region λ2; wherein the hardness E of the pressure-sensitive adhesive layer measured by a nanoindentation method before absorbing light in the second wavelength region λ2 is ３ is 0.01 MPa or more, and the hardness E of the pressure-sensitive adhesive layer after absorbing light in the second wavelength region λ2 as measured by a nanoindentation method is ４ The hardness E of the pressure-sensitive adhesive layer measured by the nanoindentation method ３ This adhesive sheet is more than five times stronger than the original.

13. The adhesive sheet according to claim 12, wherein the wavelength converting material is dispersed in the adhesive.

14. The adhesive sheet according to claim 12, wherein the wavelength converting material is a sensitizing component capable of absorbing light in a first wavelength region λ1 and a light-emitting component capable of emitting light in a second wavelength region λ2 having a shorter wavelength than the first wavelength region λ1.

15. Hardness E of the pressure-sensitive adhesive layer measured by nanoindentation method ４ The pressure-sensitive adhesive layer has a hardness E measured by a nanoindentation method. ３ The pressure-sensitive adhesive sheet according to claim 12, wherein the pressure-sensitive adhesive sheet has a viscosity of 30 times or more and 1500 times or less relative to the pressure-sensitive adhesive sheet.

16. The pressure-sensitive adhesive sheet according to claim 12, further comprising a substrate, wherein the transmittance of the substrate for light in the first wavelength region λ1 is 50% or more, and the transmittance of the substrate for light in the second wavelength region λ2 is 10% or less.

17. The pressure-sensitive adhesive sheet according to claim 12, wherein the 180° peel strength of the pressure-sensitive adhesive layer after absorbing light in the second wavelength region λ2 is 95% or less, assuming that the 180° peel strength of the pressure-sensitive adhesive layer before absorbing light in the second wavelength region λ2 is 100%.

18. A sheet for temporarily fixing electronic components, comprising the pressure-sensitive adhesive sheet according to claim 6 or 8.

19. A method for processing electronic components, comprising the steps of: attaching an electronic component to the adhesive layer provided on the sheet for temporary fixing of electronic components according to claim 18; carrying out a predetermined treatment on the electronic component attached to the adhesive layer; and irradiating the wavelength conversion layer provided on the sheet for temporary fixing of electronic components with light in the first wavelength region λ1 to cause it to emit light in the second wavelength region λ2, and peeling the electronic component that has been subjected to the predetermined treatment from the adhesive layer that has absorbed the light in the second wavelength region λ2.

20. A sheet for temporarily fixing electronic components, comprising the pressure-sensitive adhesive sheet according to claim 12 or 14.

21. A method for processing electronic components, comprising the steps of: attaching an electronic component to the adhesive layer provided on the sheet for temporarily fixing electronic components described in claim 20; performing a predetermined treatment on the electronic component attached to the adhesive layer; and irradiating the adhesive layer with light in the first wavelength region λ1 to cause it to emit light in the second wavelength region λ2, and peeling the electronic component, which has been subjected to the predetermined treatment, from the adhesive layer that has absorbed the light in the second wavelength region λ2.

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