Photon up-conversion film, manufacturing method of photon up-conversion film, photon up-conversion body, laminate and energy conversion device

Abstract

To provide a photon up-conversion film capable of up-conversion of a high performance, a photon up-conversion body, a laminate and an energy conversion device, and a manufacturing method of these.SOLUTION: The photon up-conversion film includes a color development part at least including: a sensitization 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 shorter wavelengths than the first wavelength region λ1. The photon up-conversion film has less than 210 ms relaxation time measured by a spin-echo method using a time domain nuclear magnetic resonance method (pulse NMR) at 298K.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a photon upconversion film, a method for manufacturing a photon upconversion film, a photon upconversion body, a laminate, and an energy conversion device. [Background technology]

[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 in various fields such as solar cells or photovoltaics, photocatalysis, bioimaging, and optical devices. A well-known example of upconversion luminescence in organic materials is triplet-triplet annihilation (TTA), which occurs when triplet molecules collide with each other. Among the TTA-based upconversion techniques (TTA-UC), in solution systems where donor and acceptor compounds are dissolved in a solvent, energy transfer is efficiently achieved through the diffusion of donor and acceptor compound molecules. However, the solution system has the drawback of limiting the fields in which it can be put to practical use.

[0003] Due to the above circumstances, research and development into upconversion luminescence in the solid state is progressing. However, since molecular diffusion hardly occurs in the solid state, there is a problem that TTA cannot be used efficiently. For example, resin films incorporating donor and acceptor compounds have been investigated, but the upconversion luminescence efficiency is insufficient. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5491408 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention has been made to solve the above-mentioned conventional problems, and its main object is to provide a photon upconversion film, a photon upconversion body, a laminate, and an energy conversion device capable of highly efficient upconversion, as well as methods for manufacturing each of them. Another object of the present invention is to provide a photon upconversion film, a photon upconversion body, a laminate and an energy conversion device that are capable of achieving high transmittance and high efficiency upconversion by optimizing the medium, as well as methods for manufacturing each of them. [Means for solving the problem]

[0006] [1] A photon upconversion film according to one embodiment of the present invention includes a color-forming portion. The color-forming portion includes at least a sensitizer and a light-emitting portion. The sensitizer is capable of absorbing light in a first wavelength region λ1. The light-emitting portion is capable of emitting light in a second wavelength region λ2, the wavelength of which is shorter than the first wavelength region λ1. The photon upconversion film has a relaxation time of less than 210 ms as measured by a spin-echo method using time-domain nuclear magnetic resonance (pulse NMR) at 298 K. [2] The photon upconversion film according to [1] above may further include a matrix, in which the color-forming portion is dispersed as a dispersed phase. [3] In the photon upconversion film described in [2] above, the matrix may be made of a resin. [4] In the photon upconversion film according to the above item [3], the resin may contain polyethylene oxide and / or polyvinyl alcohol-based resin. [5] In the photon up-conversion film according to any one of [1] to [4] above, the color-developing part may contain a solvent having a boiling point of 80° C. or higher. [6] In the photon up-conversion film according to any one of [1] to [5] above, the color-developing part may contain a solvent having a viscosity of 0.6 mPa·s or more at 23°C. [7] In the photon up-conversion film according to any one of [1] to [6] above, the color-developing portion may contain a monomolecular liquid crystal compound. [8] The photon upconversion film according to any one of [3] to [7] above, wherein the sensitizing component is added in an amount of 7.00 × 10 per 1 g of the resin. -9 mol ~ 5.00 × 10 -6 mol and the above luminescent components are 5.00 × 10 -6 mol ~ 7.00 × 10 -5 It may contain mol. [9] Another aspect of the present invention provides a method for producing a photon upconversion film according to any one of [1] to [8] above, which includes the steps of preparing an emulsion from a medium in which the sensitizing component and the luminescent component are dispersed and / or dissolved, and an aqueous solution containing a water-soluble resin; applying the emulsion to a substrate to form a coating film; and drying the coating film.

[10] A laminate according to another aspect of the present invention includes the photon upconversion film according to any one of [1] to [8] above.

[11] An energy conversion device according to yet another aspect of the present invention includes the photon upconversion film according to any one of [1] to [8] above.

[12] A photon upconversion film according to yet another aspect of the present invention includes a color-forming portion. The color-forming portion includes at least a sensitizer and a light-emitting portion. The sensitizer is capable of absorbing light in a first wavelength region λ1. The light-emitting portion is capable of emitting light in a second wavelength region λ2, the wavelength of which is shorter than that of the first wavelength region λ1. The photon upconversion film has a relaxation time of less than 210 ms as measured by a spin-echo method using time-domain nuclear magnetic resonance (pulse NMR) at 298 K. [Effects of the Invention]

[0007] According to the embodiments of the present invention, it is possible to realize a photon upconversion film, a photon upconversion body, a laminate, an energy conversion device, and their respective manufacturing methods, which are capable of highly efficient upconversion. Furthermore, it is possible to realize a photon upconversion film, a photon upconversion body, a laminate, an energy conversion device, and their respective manufacturing methods, which are capable of highly transparent and highly efficient upconversion by optimizing the medium. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a conceptual diagram of energy levels illustrating the mechanism of upconversion. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these embodiments.

[0010] A. Mechanism of Photon Upconversion The mechanism of photon upconversion will be explained with reference to Figure 1. First, the sensitizer (donor) absorbs incident light and converts it into an excited singlet state S D Intersystem crossing from the excited triplet state T D Then, triplet-triplet energy transfer (TTET) occurs from the donor to the emissive moiety (acceptor), resulting in the acceptor's excited triplet state T A is generated. Then, the triple excited state T A When two acceptors in the same region approach each other within the range of diffusion, collision, or energy transfer, triplet-triplet annihilation (TTA) occurs. As a result, the acceptors reach the higher 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

[0011] B. Overall structure of photon upconversion film A photon upconversion film (hereinafter sometimes referred to as an upconversion film) according to an embodiment of the present invention includes a color-forming portion. The color-forming portion includes at least a sensitizing component (donor) and a light-emitting component (acceptor). The sensitizing component can absorb light in a first wavelength region λ1. The light-emitting component can emit light in a second wavelength region λ2, which has a shorter wavelength than the first wavelength region λ1. Typically, the sensitizing component and the light-emitting component are located in close proximity to each other so that energy transfer is possible. In such a photon upconversion film, if the relaxation time measured by the spin-echo method using time-domain nuclear magnetic resonance (TD-NMR, pulsed NMR) at 298 K (24.85 °C) is less than 210 ms (milliseconds), the absolute quantum yield of the upconversion film can be improved. This allows for the realization of an upconversion film capable of highly efficient upconversion. Furthermore, by optimizing the medium, it is possible to produce a highly efficient upconversion film while improving the transmittance.

[0012] In one embodiment, the photon up-conversion film further includes a matrix. The color-forming moiety is dispersed in the matrix as a dispersed phase. The photon up-conversion film typically has an islands-in-a-sea structure.

[0013] The domain size of the color-forming portion is, for example, 0.05 μm to 10 μm, preferably 0.1 μm to 10 μm, more preferably 0.1 μm to 5.0 μm, and even more preferably 1.0 μm to 5.0 μm. The domain size of the color-forming portion is measured, for example, by observing the cross section with a scanning electron microscope (SEM) or the surface with an optical microscope. If the domain size of the color-forming portion is within this range, the luminous efficiency of the upconversion film can be stably improved.

[0014] The content of the color-forming portion in the upconversion film is, for example, 1.0 to 60% by volume, and preferably 5.0 to 50% by volume. The content of the color-forming portion is measured, for example, by any appropriate image processing of a cross-sectional SEM image. If the content of the color-forming portion is within this range, the luminous efficiency of the upconversion film can be more stably improved.

[0015] The thickness of the upconversion film is, for example, 5 μm to 200 μm, preferably 10 μm to 150 μm, and more preferably 15 μm to 100 μm. When the thickness of the upconversion film is within this range, the color-forming portion can be well dispersed throughout the entire thickness of the film, and the desired upconversion can be stably achieved.

[0016] C. Photon Up-Conversion Film Details As described above, in the photon upconversion film, the relaxation time (average relaxation time) measured by TD-NMR at 298 K (24.85° C.) is less than 210 ms, preferably 150 ms or less, more preferably 90 ms or less, and even more preferably 80 ms or less. The relaxation time (average relaxation time) can be measured, for example, by the spin-echo method. The lower limit of the relaxation time (average relaxation time) measured by TD-NMR at 298 K is typically 20 μs, and typically 6 μs. Details of the method for measuring the relaxation time (average relaxation time) will be described in the Examples below. If the relaxation time measured by TD-NMR at 298 K is within this range, it is presumed that the color-forming portion contained in the upconversion film exists in a form that allows efficient energy transfer at 298 K. It is also presumed that a highly efficient upconversion phosphor can be obtained by reducing energy loss due to non-radiative deactivation in the color-forming portion. Therefore, molecular diffusion between the sensitizing component and the light-emitting component can occur in the color-forming portion, allowing efficient energy transfer.

[0017] In one embodiment, the color-forming portion contains a medium capable of dissolving and / or dispersing the sensitizing component and the light-emitting component, which facilitates molecular diffusion between the sensitizing component and the light-emitting component in the color-forming portion, thereby further improving the luminous efficiency of the upconversion film.

[0018] D. Coloring medium The medium may be, for example, a monomolecular liquid crystal compound and / or a solvent. The medium may be used alone or in combination.

[0019] When the color-forming portion contains a monomolecular liquid crystal compound, the absolute quantum yield of the upconversion film can be further improved. The monomolecular liquid crystal compound may exhibit liquid crystallinity or crystallinity at 298 K (24.85° C.). The monomolecular liquid crystal compound may be a nematic liquid crystal compound, a smectic liquid crystal compound, or a cholesteric liquid crystal compound. The monomolecular liquid crystal compound is preferably a nematic liquid crystal compound.

[0020] Monomolecular liquid crystal compounds that exhibit liquid crystallinity at 298K (hereinafter, may be referred to as room temperature liquid crystal compounds) are typically capable of dissolving sensitizing components and light-emitting components. Examples of room temperature liquid crystal compounds include cyanobiphenyls, cyanophenylcyclohexane esters, alkoxyphenyl tolanes, and Schiff bases. The room temperature liquid crystal compounds may be used alone or in combination. Of the room temperature liquid crystal compounds, preferred are cyanobiphenyls, cyanophenylcyclohexane esters, and alkoxyphenyltolanes.

[0021] Examples of cyanobiphenyls include 4-cyano-4'-alkylbiphenyls such as 4-cyano-4'-pentylbiphenyl, 4-cyano-4'-hexylbiphenyl, 4-cyano-4'-heptylbiphenyl, and 4-cyano-4'-n-octylbiphenyl.

[0022] Examples of cyanophenylcyclohexane esters include 4-cyano-4'-alkylphenylcyclohexane esters such as 4-cyano-4'-pentylphenylcyclohexane ester, 4-cyano-4'-butylphenylcyclohexane ester, and 4-cyano-4'-propylphenylcyclohexane ester.

[0023] Examples of the alkoxyphenyl tolanes include 4-alkoxy-4'-alkylphenyl tolanes such as 4-ethoxy-4'-butylphenyl tolane, 4-methoxy-4'-ethylphenyl tolane, and 4-butoxy-4'-propylphenyl tolane.

[0024] A monomolecular liquid crystal compound that exhibits crystallinity at 298 K (hereinafter, sometimes referred to as a high-temperature liquid crystal compound) may be capable of forming a solid solution of the sensitizing component and the light-emitting component at 298 K (24.85°C), or may be capable of dispersing the sensitizing component and the light-emitting component.

[0025] Examples of high temperature liquid crystal compounds include cyanophenylcyclohexanes, cyanophenyl esters, alkoxyphenyl esters, alkoxyphenylcyclohexane esters, and alkoxycyanobiphenyls. The high temperature liquid crystal compounds may be used alone or in combination. Of the high-temperature liquid crystal compounds, preferred are cyanophenylcyclohexanes, cyanophenyl esters, alkoxyphenyl esters, alkoxyphenylcyclohexane esters, and alkoxycyanobiphenyls.

[0026] Examples of cyanophenylcyclohexanes include 4-cyano-4'-alkylphenylcyclohexanes such as 4-cyano-4'-pentylphenylcyclohexane and 4-cyano-4'-propylphenylcyclohexane.

[0027] Examples of cyanophenyl esters include 4-cyano-4'-alkylphenyl esters such as 4-cyano-4'-nonylphenyl ester, 4-cyano-4'-ethylphenyl ester, and 4-cyano-4'-butylphenyl ester.

[0028] Examples of the alkoxyphenyl esters include 4-alkyl-4'-alkoxyphenyl esters such as 4-pentyl-4'-hexyloxyphenyl ester, 4-pentyl-4'-methoxyphenyl ester, and 4-ethyl-4'-hexyloxyphenyl ester.

[0029] Examples of the alkoxyphenylcyclohexane esters include 4-alkoxy-4'-alkylphenylcyclohexane esters such as 4-methoxy-4'-pentylphenylcyclohexane ester, 4-ethoxy-4'-butylphenylcyclohexane ester, and 4-ethoxy-4'-propylphenylcyclohexane ester.

[0030] Examples of alkoxycyanobiphenyls include 4-cyano-4'-alkoxybiphenyls such as 4-cyano-4'-pentoxybiphenyl, 4-cyano-4'-butoxybiphenyl, and 4-cyano-4'-ethoxybiphenyl.

[0031] The solvent is typically in a liquid state at 298 K (24.85°C). The solvent may be in a solid state at 298 K (24.85°C), and any material with a melting point that is liquid at such a temperature during the upconversion film or upconversion body production process, or a material whose melting point can be lowered by mixing with an organic solvent, can be used. The solvent is typically capable of dissolving the sensitizing component and the luminescent component. The viscosity of the solvent at 23°C is, for example, 0.6 mPa·s or more, preferably 4.0 mPa or more. The viscosity of the solvent can be measured as the solution viscosity (mPa·s) of the coating liquid at a shear rate of 800 rpm under conditions of 23°C using any appropriate viscosity / viscoelasticity measuring device (for example, a rheometer trade name "RS-600" manufactured by HAAKE). The boiling point of the solvent is, for example, 60°C or higher, preferably 80°C or higher, more preferably 150°C or higher, and even more preferably 200°C or higher. The upper limit of the boiling point of the solvent is typically 300°C, and typically 400°C. When a mixture of multiple solvents is used as the medium, the boiling point of the mixed solvent is defined as the temperature at which the weight loss rate reaches 95% when the mixed solvent is heated from 30°C to 400°C at 10°C / min by TG / DTA. When the viscosity and / or boiling point of the solvent contained in the color-forming portion is within this range, the solvent is less likely to volatilize during the manufacturing process, and energy loss due to non-radiative deactivation can be suppressed, thereby further improving the absolute quantum yield of the upconversion film.

[0032] Examples of the solvent include organic solvents, and more specific examples include phthalate esters, glycerin, triglyceride compounds, and ionic liquids. The solvents may be used alone or in combination. Among the solvents, preferred are phthalate esters and triglyceride compounds.

[0033] Examples of phthalate esters include dimethyl phthalate, dibutyl phthalate, and dioctyl phthalate.

[0034] Examples of triglyceride compounds include tricaprin (1,2,3-tridecanoylglycerol), triacetin (glycerol triacetate), tricaprylin (glycerol tri-n-octanoate), and tricaproin (glycerol trihexanoate).

[0035] Among such media, room temperature liquid crystal compounds are preferred. When the medium contains a room temperature liquid crystal compound, the luminous efficiency of the upconversion film can be further improved.

[0036] The medium may contain additives. Examples of additives include fatty acid oils such as MCT oil; and saturated hydrocarbons such as hexadecane and liquid paraffin. Additives differ from solvents in that they are defined as materials that do not have high dye solubility. "Not having high dye solubility" means that when a dye is added to and mixed with an additive at room temperature and normal pressure (23°C, 0.1 MPa), the dye solubility concentration is, for example, 0.1 mM or less. By including an additive in the medium, the viscosity, refractive index, and phase transition temperature of the medium can be suitably adjusted.

[0037] E. Matrix Examples of the matrix material include resin and glass. In one embodiment, the matrix is composed of a resin, which is typically a water-soluble resin.

[0038] 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. Of these water-soluble resins, polyethylene oxide and polyvinyl alcohol resins are preferred, and polyvinyl alcohol resins are more preferred. When the resin constituting the matrix contains polyethylene oxide and / or polyvinyl alcohol-based resin, the luminous efficiency of the upconversion film can be stably improved.

[0039] The Hansen solubility parameter (HSP) distance Ra between the resin constituting the matrix and the sensitizing component and the luminescent component is, for example, 10 (MPa). 1 / 2 or more, for example, 11 (MPa) 1 / 2 or more, preferably 12 (MPa) 1 / 2 More preferably, 15 (MPa) or more. 1 / 2 More preferably, it is 18 (MPa) or more. 1 / 2 On the other hand, the HSP distance Ra between the resin constituting the matrix and the sensitizing component and the light-emitting component is, for example, 25 (MPa). 1 / 2 and preferably 23 (MPa) 1 / 2 More preferably, 21 (MPa) 1 / 2 The HSP distance Ra in this range means that the resin constituting the matrix has low affinity with the sensitizing component and the luminescent component. As a result, migration of the sensitizing component and the luminescent component into the matrix is significantly suppressed, allowing the sensitizing component and the luminescent component to be stably present in the color-developing portion.

[0040] HSP is expressed as a vector plotted in three-dimensional space by dividing the Hildebrand solubility parameter into three components: dispersion force (δD), permanent dipole intermolecular force (δP), and hydrogen bond force (δH). Similar vectors indicate high solubility. The similarity of solubility can be determined from the HSP distance Ra. The definition and calculation of HSP are described in "Hansen Solubility Parameters: A Users Handbook" by Charles M. Hansen (CRC Press, 2007). HSP values are publicly known for various resins and solvents. These values can be used directly, or values calculated using the computer software HSPiP (Hansen Solubility Parameters in Practice) can be used. HSPiP also includes a database of resins and solvents.

[0041] Resin (HSP value: δD R , δP R , δH R ) and the sensitizing component or luminescent component (HSP value: δD C , δP C , δH C The HSP distance Ra to the target object can be calculated using formula (1). Ra = {4 × (δD R -δD C ) 2 +(δP R -δP C ) 2 +(δH R -δH C ) 2} 1 / 2 ···(1) In formula (1), δD R is the dispersion force of the resin, δP R is the permanent dipole intermolecular force of the resin, δH R is the hydrogen bonding strength of the resin, δD C is the dispersion power of the sensitizing component or luminescent component, δP C is the permanent dipole intermolecular force of the sensitizer or luminescent component, δH C represents the hydrogen bonding strength of the sensitizing component or the luminescent component, respectively.

[0042] F. Sensitizing and Light-Emitting Components F-1. Sensitizing ingredients As is clear from the mechanism described in Section A, the sensitizing 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 the sensitizing component include compounds having a porphyrin structure, a phthalocyanine structure, or a fullerene 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. Pt, Pd, and Os are preferred. Specific examples of compounds that can function as sensitizing components will be described later in Section F-3.

[0043] 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. Semiconductor materials include, for example, II-VI, III-V, IV-VI, and IV semiconductors. Specific examples include Si, Ge, Sn, Se, Te, B, C (including diamond), P, BN, BP, BAs, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, InSb, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, ZnO, ZnS, ZnSe, ZnTe, CdS, CdSe, CdSeZn, and C. Examples include dTe, HgS, HgSe, HgTe, BeS, BeSe, BeTe, MgS, MgSe, GeS, GeSe, GeTe, SnS, SnSe, SnTe, PbO, PbS, PbSe, PbTe, CuF, CuCl, CuBr, CuI, SiN, GeN, AlO, (Al, Ga, In)(S, Se, Te), AlCO, and combinations (complexes) thereof.

[0044] The sensitizing component is preferably used in an amount of 7.00×10 -9mol ~ 5.00 × 10 -6 mol, more preferably 1.00 × 10 -8 mol ~ 3.00 × 10 -6 mol, more preferably 4.50 × 10 -8 mol ~ 2.00 × 10 -6 It is contained in the upconversion film in a molar ratio. If the content of the sensitizing component is within this range, triplet excitons can be generated sufficiently, and the efficiency of triplet-triplet annihilation can be improved.

[0045] F-2. Luminescent components As is clear from the mechanism described in Section A, the light-emitting component receives triplet-triplet energy transfer from the sensitizer component to generate an excited triplet state, and when molecules of the light-emitting component in the excited triplet state approach each other by a distance allowing diffusion, collision, or energy transfer, triplet-triplet annihilation occurs to generate an excited singlet state of a higher energy level. Various compounds with fused aromatic rings are known as light-emitting components. Specific examples include compounds with naphthalene, anthracene, pyrene, perylene, tetracene, bodipy (borondipyrromethene), and diketopyrrolopyrrole structures. Specific examples of compounds that can function as light-emitting components are described in Section F-3.

[0046] The light-emitting component is preferably 5.00×10 -6 mol ~ 7.00 × 10 -5 mol, more preferably 6.00 × 10 -6 mol ~ 6.00 × 10 -5 mol, more preferably 7.00 × 10 -6 mol ~ 5.00 × 10 -5 It is contained in the upconversion film in a molar ratio. If the content of the light-emitting component is within this range, the triplet excitons received from the sensitizing dye can diffuse sufficiently between molecules of the light-emitting component.

[0047] The blending ratio of the sensitizing component to the luminescent component (sensitizing component:luminescent component) (molar ratio) is, for example, 1:10 to 1:7000, preferably 1:25 to 1:3000, more preferably 1:30 to 1:200, and even more preferably 1:35 to 1:100. When the blending ratio is within this range, triplet excitons generated from the sensitizing component are efficiently transferred to the luminescent dye, deactivation between the luminescent dyes is minimized, and triplet-triplet annihilation can be satisfactorily achieved.

[0048] F-3. Combination of sensitizing component and luminescent component Preferred combinations of the sensitizing component and the light-emitting component depending on the wavelengths of the incident light and the upconversion light are as follows:

[0049] 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 ingredient> [ka] <Emitting component> [ka] [ka]

[0050] 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 ingredient> [ka] <Emitting component> [ka]

[0051] 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 ingredient> [ka] <Emitting component> [ka] [ka]

[0052] 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 ingredient> [ka] <Emitting component> [ka]

[0053] The sensitizing component that absorbs light in the wavelength region λ1 of 410 nm to 500 nm is 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 ingredient> [ka] [ka] <Emitting component> [ka] [ka] [ka]

[0054] 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). <Emitting component> [ka]

[0055] The sensitizing component that absorbs light in the wavelength region λ1 of around 970 nm to 990 nm (e.g., 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 (e.g., 560 nm) is the following compound: This combination can upconvert near-infrared light to visible light (green light). <Emitting component> [ka]

[0056] G. Surfactants The photon upconversion film may further contain a surfactant. When the photon upconversion film contains a surfactant, the dispersibility of the color-forming moiety in the matrix can be improved. Examples of surfactants include cationic surfactants such as hexadecyltrimethylammonium bromide (CTAB), anionic surfactants, and nonionic surfactants, and CTAB is preferred. The surfactant is added in an amount of, for example, 0 to 200 parts by mass, and preferably 1 to 50 parts by mass, relative to 100 parts by mass of the medium.

[0057] H. Photon upconversion film manufacturing method In one embodiment, the method for producing a photon upconversion film includes preparing an emulsion from an aqueous solution containing a water-soluble resin and a solution or dispersion of a sensitizing component and a light-emitting component (hereinafter, collectively referred to as a "dye solution, etc."); applying the emulsion to a substrate to form a coating film; and drying the coating film. Each step will be specifically described below.

[0058] <Preparation of emulsion> In preparing the emulsion, first, a dye solution and the like appropriate for the desired upconversion film are prepared.

[0059] When an upconversion film (UC film) is produced using a medium that is fluid at 298 K (24.85°C), an organic solvent is added as needed to the medium described in Section C above (specifically, the room temperature liquid crystal compound and / or solvent), and then the sensitizing component and light-emitting component described in Section F above are added and stirred. Adding an organic solvent to the medium can improve the solubility of the sensitizing component and the light-emitting component. In particular, when the fluid medium is a room-temperature liquid crystal compound, it is preferable to add an organic solvent to the room-temperature liquid crystal compound. As the organic solvent, for example, a volatile solvent can be used. Specific examples of such solvents include ethers such as tetrahydrofuran; halogenated hydrocarbons such as chloroform and dichloromethane; and toluene. The organic solvents can be used alone or in combination. Among such organic solvents, ethers are preferred, and tetrahydrofuran is more preferred. The proportion of the organic solvent added is, for example, 0 to 200 parts by mass, and preferably 80 to 120 parts by mass, relative to 100 parts by mass of the flowable medium. The medium may contain the additives described above. The additives may be added to the medium together with an organic solvent, or may be added alone. Adding an additive to the medium can appropriately adjust the viscosity, refractive index, and / or phase transition temperature of the medium. The additive content is, for example, 0 to 200 parts by mass, and preferably 5 to 100 parts by mass, relative to 100 parts by mass of the medium. Furthermore, a plurality of liquid crystal compounds, organic solvents, and other additives may be mixed in any desired ratio.

[0060] In addition, when an upconversion film (UC film containing a high-temperature liquid crystal compound) is produced using a high-temperature liquid crystal compound, the high-temperature liquid crystal compound described in the above section C is heated to change into a liquid crystal state, and then the above-mentioned organic solvent is added as necessary, and the sensitizing component and the light-emitting component described in the above section F are added and stirred. The heating temperature of the high-temperature liquid crystal compound can be arbitrarily and appropriately adjusted depending on the high-temperature liquid crystal compound. For example, the heating temperature of the high-temperature liquid crystal compound is adjusted to a temperature higher than the crystalline-liquid crystal phase transition temperature T K-N Above the liquid crystal-isotropic liquid phase transition temperature T N-I The following is the result. The addition of an organic solvent to the high-temperature liquid crystal compound in a liquid crystal state can improve the solubility of the sensitizing component and the light-emitting component. The proportion of the organic solvent added is, for example, 0 to 200 parts by mass, preferably 80 to 120 parts by mass, relative to 100 parts by mass of the high-temperature liquid crystal compound. These methods are used to prepare a dye solution suitable for producing a UC film having a relaxation time of less than 210 ms. A dye solution is typically a medium in which a sensitizing component and a light-emitting component are dissolved and / or dispersed.

[0061] The concentration of the sensitizing component in these dye solutions or the like can be, for example, 0.001 mM to 1 mM, and the concentration of the luminescent component can be, for example, 1 mM to 50 mM.

[0062] Also, prepare an aqueous solution of the water-soluble resin described above in Section E. The concentration of the aqueous solution can be, for example, 3% by weight to 20% by weight, or, for example, 5% by weight to 10% by weight.

[0063] Next, the aqueous solution of the water-soluble resin is mixed with the dye solution, etc., so that the blending ratio of the sensitizing component and the light-emitting component relative to the water-soluble resin (matrix) falls within the desired range described in Section F above. More specifically, the aqueous solution of the water-soluble resin is mixed with the dye solution, etc., and the mixture is emulsified using a homogenizer. At this time, the above-mentioned surfactant may be added, if necessary. This allows droplets of the dye solution, etc., to be suitably dispersed in the aqueous solution of the water-soluble resin, thereby preparing an emulsion. If necessary, the resulting emulsion may be degassed. Volatile components (e.g., organic solvents) contained in the resulting emulsion may also be removed under reduced pressure. This allows the concentrations of the sensitizing component and the light-emitting component in the emulsion to be improved. 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.

[0064] <Coating film formation and drying> 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 appropriate resin can be used as the resin constituting the resin sheet. Specific examples include polyimide-based resins, cellulose-based resins such as triacetyl cellulose (TAC), polyester-based resins such as polyethylene terephthalate (PET), polyvinyl alcohol-based resins, polycarbonate-based resins, polyamide-based resins, polyethersulfone-based resins, polysulfone-based resins, polystyrene-based resins, polynorbornene-based resins, polyolefin-based resins, (meth)acrylic-based resins, and acetate-based transparent resins. Other examples include thermosetting resins or ultraviolet-curing resins such as (meth)acrylic-based resins, urethane-based resins, (meth)acrylic urethane-based resins, epoxy-based resins, and silicone-based resins. Other examples include glassy polymers such as siloxane-based polymers.

[0065] 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). A coating film can also 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) is 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 is adjusted so that the thickness of the resulting upconversion film falls within the desired range described in section B above (for example, 5 μm to 200 μm). The thickness of the coating film can be, for example, 100 μm to 1000 μm.

[0066] 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 minutes to 60 minutes. By drying, a dried coating having substantially the same thickness as the resulting upconversion film can be obtained. The dried coating can typically be naturally cooled to room temperature (23°C). The upconversion film can be prepared in this manner. The upconversion film can be peeled off from the substrate, or can be used as a laminate with the substrate without being peeled off from the substrate.

[0067] I. Uses of photon upconversion film The upconversion films described in the above sections A to H can be applied to any suitable industrial product. Examples of industrial products include laminates and energy conversion devices. Therefore, one embodiment of the present invention also encompasses laminates and energy conversion devices using such upconversion films. The laminate comprises the upconversion film described in the above items A to H, and any appropriate film (layer) laminated on the upconversion film. The energy-converting device includes at least the up-conversion film described in the above items A to H, and may further include any appropriate configuration in addition to the up-conversion film.

[0068] I-1.Laminate The laminate may include a first protective layer and a second protective layer disposed on the light-incident surface and the light-exiting surface of the upconversion film, respectively. The first protective layer and the second protective layer may be omitted depending on the purpose. Furthermore, any suitable optical member may be disposed between the upconversion film and the first protective layer and / or between the upconversion film and the second protective layer, as long as the effects of the present invention are achieved. In one embodiment, the laminate has a configuration in which at least the first protective layer, the second protective layer, and the third protective layer are integrated. Here, "the first protective layer, the second protective layer, and the third protective layer are integrated" means that the components constituting the laminate, from the first protective layer to the second protective layer, are connected as a whole. Integration can be achieved, for example, by bonding adjacent components together via an adhesive layer such as a pressure-sensitive adhesive layer or an adhesive layer. Alternatively, a layer with a different function, such as an overcoat, may be directly applied to the photon upconversion film. Preferably, the first protective layer, the upconversion film, the second protective layer, and any other protective layers are integrated via an adhesive layer. The overcoat may be made of any suitable material, such as an acrylic resin or an epoxy resin. In another embodiment, the laminate has a configuration in which the first protective layer and the second protective layer are not integrated. Here, "the first protective layer and the second protective layer are not integrated" means that at least one of the components from the first protective layer to the second protective layer constituting the laminate is simply laminated on one or both of the adjacent components. The laminate in this embodiment may have, for example, a configuration in which the first protective layer, the upconversion film, and the second protective layer are arranged in this order without an adhesive layer. Furthermore, for example, the laminate in this embodiment may have a configuration in which the first protective layer to the upconversion film are integrated via an adhesive layer, and the second protective layer is arranged on the light-emitting side of the integrated laminate without an adhesive layer. Furthermore, for example, the laminate in this embodiment may have a configuration in which the upconversion film to the second protective layer are integrated via an adhesive layer, and the first protective layer is arranged on the light-incident side of the integrated laminate without an adhesive layer.

[0069] I-2.Protective layer The first and second protective layers are each formed of any suitable film suitable for use as a protective layer in an upconversion film. Specific examples of materials that can serve as the main component of the film include cellulose-based resins such as triacetyl cellulose (TAC), and transparent resins such as polyesters, polyvinyl alcohols, polycarbonates, polyamides, polyimides, polyethersulfones, polysulfones, polystyrenes, polynorbornenes, polyolefins, (meth)acrylics, and acetates. Other examples include thermosetting or ultraviolet-curing resins such as (meth)acrylics, urethanes, (meth)acrylic urethanes, epoxy resins, and silicones, as well as inorganic materials such as glass and silica. Other examples include glassy polymers such as siloxane-based polymers. Polymer films described in JP 2001-343529 A (WO 01 / 37007) can also be used. Examples of materials that can be used for this film include a resin composition containing a thermoplastic resin having substituted or unsubstituted imide groups in its side chains and a thermoplastic resin having substituted or unsubstituted phenyl and nitrile groups in its side chains, such as a resin composition containing an alternating copolymer of isobutene and N-methylmaleimide and an acrylonitrile-styrene copolymer.The polymer film can be, for example, an extrusion molded product of the above resin composition.

[0070] J. Photon Upconversion Body The upconversion film is described in detail in the above sections A to H. However, as long as upconversion is possible in a solid state, there are no limitations on the film shape. The photon upconversion material is in a solid state at room temperature (23° C.) and normal pressure (0.1 MPa). The photon upconversion material may be in the form of, for example, crystal, powder, or gel. The photon upconversion body can be described in the same manner as the upconversion film, except in the solution state, and therefore the description of the photon upconversion body will be omitted. [Example]

[0071] 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.

[0072] Example 1 1. Preparation of DMP solutions of sensitizing and luminescent components In a glove box, octaethylporphyrin platinum (PtOEP: chemical formula shown below) as a sensitizing component and 9,10-diphenylanthracene (DPA: chemical formula shown below) as a light-emitting component were dissolved in dimethyl phthalate (DMP) to prepare a DMP solution of the sensitizing component and light-emitting component. The concentration of the sensitizing component in the solution was 2.39 × 10 ―7 M, and the concentration of the luminescent component is 4.78 × 10 ―5 That is, the molar ratio of the sensitizing component to the luminescent component was 1:200. The prepared solution was stored in a sealed vial until the emulsification step. <Sensitizing ingredient> [ka] <Emitting component> [ka]

[0073] 2. Emulsion Preparation 0.4 ml of the solution obtained above was added to 5 g of an aqueous solution of polyvinyl alcohol (PVA) (9% by mass). The solution was injected through a tube with an inner diameter of 0.75 mm and stirred with a homogenizer at 17,500 rpm until the entire mixture was emulsified. Argon gas was sprayed into the resulting emulsion for approximately 2 minutes, and the mixture was stirred using a mixer (THINKY) in mixing mode (2,000 rpm) for 5 minutes and in degassing mode (2,200 rpm) for 5 minutes. In this way, an emulsion was prepared. The PVA used had a degree of polymerization of 1,700 and a degree of saponification of 99%.

[0074] 3. Formation of upconversion film The emulsion obtained above was applied to a polyimide film (substrate) using an applicator to a thickness of 700 μm. The coating / polyimide film laminate was dried in a thermostatic chamber. The drying temperature was 80°C, and the drying time was 30 minutes. After drying, the laminate was allowed to cool naturally to room temperature (23°C). Finally, the dried coating was peeled off from the polyimide film to obtain an upconversion film (thickness 63 μm). Note that the steps after emulsion preparation were carried out in air in a dark place (under an environment with only darkroom light).

[0075] <Example 2> An upconversion film was obtained in the same manner as in Example 1, except that the DMP solution of the sensitizing component and the light-emitting component was changed to a crystal solution of the sensitizing component and the light-emitting component prepared as follows. At room temperature (23°C), 100 parts by mass of 5CB (4-cyano-4'-pentylbiphenyl) was added to 100 parts by mass of tetrahydrofuran (THF) and stirred to prepare a liquid crystal solvent. Next, PtOEP as a sensitizing component and DPA as an emitting component were dissolved in the liquid crystal solvent to prepare a liquid crystal solution of the sensitizing component and the emitting component.

[0076] Example 3 An up-conversion film was obtained in the same manner as in Example 2, except that 5CB was changed to 7CB (4-cyano-4'-heptylbiphenyl).

[0077] Example 4 An upconversion film was obtained in the same manner as in Example 1, except that the DMP solution of the sensitizing component and the light-emitting component was changed to a crystal solution of the sensitizing component and the light-emitting component prepared as follows. 100 parts by mass of 5OCB (4-cyano-4'-pentyloxybiphenyl) was heated to 60°C in a water bath to form a liquid crystal, and 100 parts by mass of tetrahydrofuran was added and stirred to prepare a liquid crystal solvent. Next, PtOEP as a sensitizing component and DPA as an emitting component were dissolved in the liquid crystal solvent to prepare a liquid crystal solution of the sensitizing component and the emitting component.

[0078] <Example 5> An up-conversion film was obtained in the same manner as in Example 2, except that the PVA aqueous solution was changed to a polyethylene oxide (PEO) aqueous solution (molecular weight 200,000) (9% by mass).

[0079] Example 6 An upconversion film was obtained in the same manner as in Example 2, except that the sensitizing component was changed to meso-tetraphenyl-tetraanthraporphyrin palladium (PdTPTAP: chemical formula below) and the emitting component was changed to rubrene (chemical formula below). The PdTPTAP concentration in the solution was 0.554 mM, and the rubrene concentration was 20 mM. That is, the molar ratio of sensitizing component to emitting component was 1:36. <Sensitizing ingredient> [ka] <Emitting component> [ka]

[0080] Example 7 At room temperature (23°C), 100 parts by mass of 5CB (4-cyano-4'-pentylbiphenyl) was added with PtOEP as a sensitizing component, DPA as a light-emitting component, 100 parts by mass of tetrahydrofuran (THF), and 5 parts by mass of MCT oil, and the mixture was stirred to prepare a liquid crystal solvent. The liquid crystal solution was added to 1 mL of a 1% by mass aqueous solution of CTAB (surfactant solution), and the mixture was stirred with an ultrasonic homogenizer to prepare an emulsion solution. 1.8 mL of the solution obtained above was added to 5 g of an aqueous solution of polyvinyl alcohol (PVA) (9% by mass). The subsequent procedures were the same as in Example 1, and an upconversion film was obtained.

[0081] Example 8 An upconversion film was obtained in the same manner as in Example 7, except that 5CB was changed to PCH5CN (4-cyano-4'-pentylphenylcyclohexane).

[0082] Example 9 An up-conversion film was obtained in the same manner as in Example 7, except that 5CB was changed to 5OCB (4-cyano-4'-pentyloxybiphenyl).

[0083] Example 10 An upconversion film was obtained in the same manner as in Example 7, except that 5 parts by mass of MCT oil was changed to 5 parts by mass of hexadecane.

[0084] Example 11 An upconversion film was obtained in the same manner as in Example 7, except that 5 parts by mass of MCT oil was changed to 5 parts by mass of liquid paraffin.

[0085] Example 12 An upconversion film was obtained in the same manner as in Example 7, except that the sensitizing component was changed to meso-tetraphenyl-tetraanthraporphyrin palladium (PdTPTAP: chemical formula shown above) and the emitting component was changed to rubrene (chemical formula shown above). The concentrations were the same as in Example 6.

[0086] Example 13 An upconversion film was obtained in the same manner as in Example 2, except that 5CB was changed to ZLI1052 (a mixed liquid crystal of PE105 (4-pentylphenyl 4-methoxybenzoate) and PE605 (4-pentylphenyl 4-hexyloxybenzoate)).

[0087] Example 14 An upconversion film was obtained in the same manner as in Example 2, except that 5CB was changed to ZLI1132 (a mixed liquid crystal of PCH-3CN (4-cyano-4'-propylphenylcyclohexane), PCH-5CN (4-cyano-4'-pentylphenylcyclohexane), PCH-7CN (4-cyano-4'-phenylcyclohexane), and BCH-5CN (4-cyano-4'-pentylbiphenylcyclohexane)).

[0088] Example 15 An upconversion film was obtained in the same manner as in Example 2, except that 5CB was changed to ZLI1083 (a mixed liquid crystal of PCH-3CN (4-cyano-4'-propylphenylcyclohexane), PCH-5CN (4-cyano-4'-pentylphenylcyclohexane), and PCH-7CN (4-cyano-4'-phenylcyclohexane)).

[0089] Example 16 An upconversion film was obtained in the same manner as in Example 2, except that 5CB was changed to E7 (a mixed liquid crystal of 5CB (4-cyano-4'-pentylbiphenyl), 7CB (4-cyano-4'-heptylbiphenyl), 8OCB (4-cyano-4'-n-octyloxybiphenyl), and 5CT (4-cyano-4'-pentyl-p-terphenyl)).

[0090] Example 17 An upconversion film was obtained in the same manner as in Example 2, except that 5CB was changed to E8 (a mixed liquid crystal of 5CB (4-cyano-4'-pentylbiphenyl), 7CB (4-cyano-4'-heptylbiphenyl), 5OCB (4-cyano-4'-pentyloxybiphenyl), 8OCB (4-cyano-4'-n-octyloxybiphenyl), and 5CT (4-cyano-4'-pentyl-p-terphenyl)).

[0091] Example 18 An up-conversion film was obtained in the same manner as in Example 1, except that DMP was changed to tricaprin.

[0092] Example 19 A liquid crystal solvent was prepared in the same manner as in Example 4. In addition, a glass plate was placed on a hot plate heated to 80°C, and the liquid crystal solvent was placed on the glass plate to volatilize the THF. This resulted in a crystalline upconversion product.

[0093] <Comparative Example 1> An upconversion film (thickness: 60 μm) was obtained in the same manner as in Example 1, except that DMP was changed to toluene. <Comparative Example 2> An upconversion film was obtained in the same manner as in Example 6, except that the crystallization solvent was changed to toluene.

[0094] <Relaxation time measurement by time-domain nuclear magnetic resonance (TD-NMR)> The upconversion film or upconversion body obtained in the above examples was cut into strips to prepare samples. The short side of the sample was 1.5 cm, and the long side of the sample was 7 to 12 cm. Two to four samples were inserted into a sample tube. The sample in the sample tube was then measured at 298 K using the spin-echo method with TD-NMR (pulse NMR), and the free induction decay curve of the spin-spin relaxation of the obtained H nuclei was analyzed using the nonlinear least squares method to calculate the T2 relaxation time. The results are shown in Tables 1 to 3. The measurement conditions were a repetition time of 10 seconds, an accumulation count of 8, and 50 measurement points. The relaxation time was analyzed by measuring in a range where the relative signal intensity of the final plot, when the signal intensity of the first plot was normalized to 1, was 0.1 or less and 0.001 or more. The analysis software "TDNMR-A Version 6.9 Rev 2.0" manufactured by BRUKER was used, and fitting was performed according to the product manual using an exponential type with a Weibull coefficient of 1. If a Weibull coefficient of 1 was not appropriate for some samples, an optimal value in the range of 1 to 2 was used. The measurement conditions are described below. Apparatus: Bruker TD-NMR (the minispec mq20) Detected nuclides: 1 H Measurement temperature: 298K Measurement method: Spin-echo method Analysis method: Nonlinear least squares method Scan:8 Recycle Delay: 10 seconds First 90-180 Pulse Separation:0.0082 Final 90-180 Pulse Separation: Adjust to the conditions described above Number of Data Points for Fitting:50 When two or more components were detected in the obtained relaxation time, the obtained relaxation time was multiplied by the proton ratio, and the average value was calculated from the relaxation times obtained by summing all the components, and this average value was used as the relaxation time.

[0095] <Absolute quantum yield measurement> The upconversion luminescence absolute quantum yield (100% conversion) of the upconversion films or upconversion bodies (hereinafter referred to as samples) obtained in the above examples and comparative examples was measured using an absolute quantum yield measurement system Quantaurus-QY Plus C11347-02 (manufactured by Hamamatsu Photonics KK, detection wavelength: 400 to 1100 nm). For absolute quantum yield measurements, diode lasers (808 nm, 200 mW, 532 nm, 75 mW, 460 nm, 500 mW, RGB Photonics) were used as excitation sources, with the light intensity adjusted using laser output and ND filters. The 808 nm laser was 27,000 mW / cm. 2 , 532nm is 31000mW / cm 2 , 460nm is 31000mW / cm 2 The light intensity was adjusted so that the sample was irradiated with light. The measured absolute quantum yields are shown in Tables 1 to 3.

[0096] <Transmittance measurement> The transmittance of the upconversion films or upconversion bodies obtained in the above Examples and Comparative Examples was measured using a UV-Vis-NIR spectrometer UH4150 (Hitachi High-Tech Corporation). To measure transmittance, the sample was placed directly in front of an integrating sphere, and total light transmittance was measured in the wavelength range of 400 nm to 800 nm at 1 nm intervals. The average transmittance from 400 nm to 800 nm was used as the average transmittance. The measured average transmittances are shown in Tables 1 to 3.

[0097] [Table 1]

[0098] [Table 2]

[0099] [Table 3]

[0100] [evaluation] As is clear from Tables 1 to 3, when the T2 relaxation time measured by the TD-NMR spin-echo method at 298 K is less than 210 ms, the absolute quantum yield can be improved and the upconversion luminescence efficiency can be improved. [Industrial Applicability]

[0101] The photon upconversion films and photon upconversion bodies according to the embodiments of the present invention can be suitably used in solar cells or photovoltaic power generation, photocatalysis, bioimaging, optical instruments, laminates, energy conversion devices, and the like.

Claims

1. a color-developing portion including at least 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 that of the first wavelength region λ1; a matrix; the color-forming portion is dispersed in the matrix as a dispersed phase, the color-forming portion contains a monomolecular liquid crystal compound, the matrix comprises a water-soluble resin, A photon upconversion film having a relaxation time of less than 210 ms as measured by the spin-echo method using time-domain nuclear magnetic resonance (pulse NMR) at 298K.

2. The photon upconversion film according to claim 1 , wherein the water-soluble resin comprises a polyethylene oxide and / or a polyvinyl alcohol-based resin.

3. The photon upconversion film according to claim 1 , wherein the color-forming portion contains a solvent having a boiling point of 80° C. or higher.

4. The photon upconversion film according to claim 1 , wherein the color-forming portion contains a solvent having a viscosity of 0.6 mPa·s or more at 23° C.

5. The sensitizing component was added to 1 g of the water-soluble resin at 7.00 × 10 －９ mol~5.00×10 －６ mol and the luminescent component is 5.00 × 10 －６ mol~7.00×10 －５ The photon upconversion film of claim 1 , comprising:

6. A method for producing the photon upconversion film according to any one of claims 1 to 5, comprising: preparing an emulsion from a medium in which the sensitizing component and the light-emitting component are dispersed and / or dissolved, and an aqueous solution containing a water-soluble resin; applying the emulsion to a substrate to form a coating film; and drying the coating film.

7. A laminate comprising the photon upconversion film according to any one of claims 1 to 5.

8. An energy conversion device comprising the photon upconversion film according to any one of claims 1 to 5.

9. a color-developing portion including at least 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 that of the first wavelength region λ1; a matrix; the color-forming portion is dispersed in the matrix as a dispersed phase, the color-forming portion contains a monomolecular liquid crystal compound, the matrix comprises a water-soluble resin, A photon upconversion agent having a relaxation time of less than 210 ms as measured by the spin-echo method using time-domain nuclear magnetic resonance (pulse NMR) at 298K.

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