Photon upconversion film, method for producing photon upconversion film, photon upconversion body, laminate, and energy conversion device

Abstract

To provide a photon upconversion film, a photon upconversion body, a laminate, an energy conversion device, and methods for manufacturing the same, which enable highly efficient upconversion. 【Solution means】The photon upconversion film according to an embodiment of the present invention includes a coloring part 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 shorter than the first wavelength region λ1. The relaxation time measured by the spin-echo method using time-domain nuclear magnetic resonance (pulse NMR) at 298K of the photon upconversion film is less than 210 ms.

Description

Technical Field

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

Background Art

[0002] Photon upconversion (hereinafter sometimes simply referred to as "upconversion") technology for converting low-energy light into high-energy light is expected to be applied to various fields such as solar cells or solar power generation, photocatalysts, bioimaging, and optical devices. As upconversion emission in organic materials, a technique utilizing triplet-triplet annihilation (TTA) that occurs when triplet-state molecules collide is known. Among upconversions utilizing TTA (TTA-UC), in a solution system in which a donor compound and an acceptor compound are dissolved in a solvent, energy transfer is efficiently performed by the diffusion of donor compound molecules and acceptor compound molecules. On the other hand, there is a problem that the fields where it can be put into practical use are limited in the solution system.

[0003] Under the above circumstances, research and development of upconversion emission in the solid state have been promoted. However, in the solid state, since there is almost no molecular diffusion, there is a problem that TTA cannot be efficiently utilized. For example, a resin film into which a donor compound and an acceptor compound are introduced has been studied, but its upconversion emission efficiency is insufficient.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present invention has been made to solve the above-described 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, and manufacturing methods thereof. Also, it is an object to provide a photon upconversion film, a photon upconversion body, a laminate, and an energy conversion device capable of upconversion that satisfies high transmittance and high efficiency by optimizing a medium, and manufacturing methods thereof.

Means for Solving the Problems

[0006] [1] A photon upconversion film according to one embodiment of the present invention includes a coloring part. The coloring part includes at least a sensitizing component and a light-emitting component. 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 that is shorter than the first wavelength region λ1. In the photon upconversion film, the relaxation time measured by the spin-echo method using time-domain nuclear magnetic resonance (pulse NMR) at 298K is less than 210 ms. [2] The photon upconversion film described in [1] above may further include a matrix. The coloring part is dispersed in the matrix as a dispersed phase. [3] In the photon upconversion film described in [2] above, the matrix may be composed of a resin. [4] In the photon upconversion film described in [3] above, the resin may include polyethylene oxide and / or a polyvinyl alcohol-based resin. [5] In the photon upconversion film according to any one of [1] to [4] above, the coloring part may include a solvent having a boiling point of 80°C or higher. [6] In the photon upconversion film according to any one of [1] to [5] above, the coloring part may contain a solvent having a viscosity of 0.6 mPa·s or more at 23°C. [7] In the photon upconversion film according to any one of [1] to [6] above, the coloring part may contain a monomolecular liquid crystal compound. [8] The photon upconversion film according to any one of [3] to [7] above may contain 7.00×10 -9 mol to 5.00×10 -6 mol of the sensitizing component and 5.00×10 -6 mol to 7.00×10 -5 mol of the light-emitting component with respect to 1 g of the resin. [9] A method for producing a photon upconversion film according to another aspect of the present invention is a method for producing a photon upconversion film according to any one of [1] to [8] above, including a step of 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; a step of applying the emulsion to a substrate to form a coating film; and a step of 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 still another aspect of the present invention includes the photon upconversion film according to any one of [1] to [8] above.

[12] A photon upconversion body according to still another aspect of the present invention includes a coloring part. The coloring part includes at least a sensitizing component and a light-emitting component. 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 that is shorter in wavelength than the first wavelength region λ1. In the photon upconversion film, the relaxation time measured by the spin-echo method using time-domain nuclear magnetic resonance (pulse NMR) at 298 K is less than 210 ms. [Advantages of the Invention]

[0007] According to an embodiment of the present invention, a photon upconversion film, a photon upconversion body, a laminate, and an energy conversion device capable of high-efficiency upconversion, and manufacturing methods thereof can be realized. Further, by optimizing the medium, a photon upconversion film, a photon upconversion body, a laminate, and an energy conversion device capable of high-transmission and high-efficiency upconversion, and manufacturing methods thereof can be realized.

Brief Description of Drawings

[0008]

Figure 1

Embodiments for Carrying Out 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 With reference to FIG. 1, the mechanism of photon upconversion will be described. First, a sensitizing component (donor) absorbs incident light, and an excited singlet state S D generates an excited triplet state T D by intersystem crossing from. Next, triplet-triplet energy transfer (TTET) occurs from the donor to the emitting component (acceptor), generating an excited triplet state T A of the acceptor. Next, acceptors in the excited triplet state T A approach each other within a range where diffusion, collision, or energy transfer is possible, causing triplet-triplet annihilation (TTA). As a result, a high excited singlet energy state S A of the acceptor is generated. Upconversion light (light having higher energy than the excitation light) is emitted from this high excited singlet energy state S A .

[0011] B. Overall Structure of Photon Upconversion Film The photon upconversion film according to an embodiment of the present invention (hereinafter sometimes referred to as an upconversion film) includes a coloring part. The coloring part contains at least a sensitizing component (donor) and a light-emitting component (acceptor). The sensitizing component can absorb light in the first wavelength region λ1. The light-emitting component can emit light in the second wavelength region λ2, which is shorter in wavelength than the first wavelength region λ1. Typically, the sensitizing component and the light-emitting component are located in the vicinity of 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. As a result, an upconversion film capable of high-efficiency upconversion can be realized. Further, by optimizing the medium, a high-efficiency upconversion film can be produced while improving the transmittance.

[0012] In one embodiment, the photon upconversion film further includes a matrix. The coloring part is dispersed in the matrix as a dispersed phase. The photon upconversion film typically has a sea-island structure.

[0013] The domain size of the coloring part 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 still more preferably 1.0 μm to 5.0 μm. The domain size of the coloring part is measured, for example, by observation with a scanning electron microscope (SEM) of a cross-section or an optical microscope from the surface. If the domain size of the coloring part is within such a range, the luminous efficiency of the upconversion film can be stably improved.

[0014] The content ratio of the color-developing part in the upconversion film is, for example, 1.0% to 60% by volume, preferably 5.0% to 50% by volume. The content ratio of the color-developing part is measured, for example, by any appropriate image processing from a cross-sectional SEM image. If the content ratio of the color-developing part is within such a 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. If the thickness of the upconversion film is within such a range, the color-developing part can be well dispersed throughout the thickness direction of the film, and the desired upconversion can be stably realized.

[0016] C. Details of the Photon Upconversion Film 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 still more preferably 80 ms or less. As a method for measuring the relaxation time (average relaxation time), for example, the spin-echo method is adopted. The lower limit of the relaxation time (average relaxation time) measured by TD-NMR at 298 K is typically 20 μs and also 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 by TD-NMR at 298 K is within such a range, it is presumed that at 298 K, the color-developing part contained in the upconversion film exists in a form that enables efficient energy transfer. It is also presumed that a highly efficient upconversion light emitter can be obtained by reducing the energy loss due to non-radiative deactivation in the color-developing part. Therefore, in the color-developing part, the sensitizing component and the light-emitting component can be molecularly diffused, and energy can be efficiently transferred.

[0017] In one embodiment, the color - forming part contains a medium in which a sensitizing component and a light - emitting component can be dissolved and / or dispersed. Therefore, in the color - forming part, molecular diffusion between the sensitizing component and the light - emitting component can be made smooth, and further improvement in the light - emitting efficiency of the up - conversion film can be achieved.

[0018] D. Medium of the Color - Forming Part Examples of the medium include, for example, single - molecule liquid - crystal compounds and / or solvents. The media can be used alone or in combination.

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

[0020] A single - molecule liquid - crystal compound that exhibits liquid - crystallinity at 298 K (hereinafter sometimes referred to as a room - temperature liquid - crystal compound) can typically dissolve a sensitizing component and a light - emitting component. Examples of the room - temperature liquid - crystal compound include cyanobiphenyls, cyanophenyl cyclohexane esters, alkoxyphenyl transes, and Schiff bases. The room - temperature liquid - crystal compounds can be used alone or in combination. Among the room - temperature liquid - crystal compounds, preferably, cyanobiphenyls, cyanophenyl cyclohexane esters, and alkoxyphenyl transes are mentioned.

[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 alkoxyphenylterans include 4-alkoxy-4'-alkylphenylterans such as 4-ethoxy-4'-butylphenylteran, 4-methoxy-4'-ethylphenylteran, and 4-butoxy-4'-propylphenylteran.

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

[0025] Examples of high-temperature liquid crystal compounds include cyanophenylcyclohexanes, cyanophenyl esters, alkoxyphenyl esters, alkoxyphenylcyclohexane esters, and alkoxycyanobiphenyls. High-temperature liquid crystal compounds can be used alone or in combination. Among the high-temperature liquid crystal compounds, preferably, cyanophenylcyclohexanes, cyanophenyl esters, alkoxyphenyl esters, alkoxyphenylcyclohexane esters, and alkoxycyanobiphenyls are mentioned.

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

[0027] As cyanophenyl esters, for example, 4-cyano-4'-alkylphenyl esters such as 4-cyano-4'-nonylphenyl ester, 4-cyano-4'-ethylphenyl ester, and 4-cyano-4'-butylphenyl ester can be mentioned.

[0028] As alkoxyphenyl esters, for example, 4-alkyl-4'-alkoxyphenyl esters such as 4-pentyl-4'-hexyloxyphenyl ester, 4-pentyl-4'-methoxyphenyl ester, and 4-ethyl-4'-hexyloxyphenyl ester can be mentioned.

[0029] As alkoxyphenylcyclohexane esters, for example, 4-alkoxy-4'-alkylphenylcyclohexane esters such as 4-methoxy-4'-pentylphenylcyclohexane ester, 4-ethoxy-4'-butylphenylcyclohexane ester, and 4-ethoxy-4'-propylphenylcyclohexane ester can be mentioned.

[0030] As alkoxysyanobiphenyls, for example, 4-cyano-4'-alkoxybiphenyls such as 4-cyano-4'-pentyoxybiphenyl, 4-cyano-4'-butoxybiphenyl, and 4-cyano-4'-ethoxybiphenyl can be mentioned.

[0031] The solvent is typically in a liquid state at 298K (24.85°C). Note that the solvent may be in a solid state at 298K (24.85°C), and materials having a melting point such that they become liquid at such temperatures during the production process of the upconversion film or upconversion body, or organic solvents, can be used in the same manner as long as they can lower the melting point by mixing. The solvent can typically dissolve the sensitizing component and the light-emitting 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 the condition of 23°C using any suitable viscosity and 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 more, preferably 80°C or more, more preferably 150°C or more, and even more preferably 200°C or more. The upper limit of the boiling point of the solvent is typically 300°C and also typically 400°C. When a plurality of solvents are mixed and used as the medium, the temperature at which the weight loss rate becomes 95% when the mixed solvent is heated from 30°C to 400°C at 10°C / min using TG / DTA is defined as the boiling point of the mixed solvent. When the viscosity and / or boiling point of the solvent contained in the color - developing part is within such a range, the solvent is difficult to volatilize in the manufacturing process, and energy loss due to non - radiative deactivation can be suppressed, so that the absolute quantum yield of the up - conversion film can be further improved.

[0032] Examples of the solvent include organic solvents. More specific examples include phthalic acid esters, glycerin, triglyceride compounds, ionic liquids, etc. The solvents can be used alone or in combination. Among the solvents, phthalic acid esters and triglyceride compounds are preferably mentioned.

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

[0034] Examples of triglyceride compounds include tricaprin (1,2,3 - tridecanoyl glycerol), triacetin (glycerol triacetate), tricaprylin (tri - n - octanoic acid glycerol), and tricaproin (tri - hexanoic acid glycerol).

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

[0036] The media may contain additives. Examples of additives include fatty acid oils such as MCT oil; saturated hydrocarbons such as hexadecane and liquid paraffin. Additives are defined as materials with low dye solubility, which is different from solvents. Low dye solubility means that when a dye is added to and mixed with an additive under normal temperature and pressure (23 °C, 0.1 MPa), the dye dissolution concentration is, for example, 0.1 mM or less. When the media contains additives, the viscosity, refractive index, and phase transition temperature of the media can be suitably adjusted.

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

[0038] As the water-soluble resin, any suitable water-soluble resin can be used as long as a matrix can be formed. 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. Among such water-soluble resins, preferably polyethylene oxide and polyvinyl alcohol-based resins are included, and more preferably polyvinyl alcohol-based resins are included. 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, respectively, for example, 10 (MPa) 1 / 2 or more, and for example, 11 (MPa) 1 / 2 or more, preferably 12 (MPa) 1 / 2 or more, more preferably 15 (MPa) 1 / 2 or more, still more preferably 18 (MPa) 1 / 2 or more. On the other hand, the HSP distance Ra between the resin constituting the matrix and the sensitizing component and the luminescent component is, respectively, for example, 25 (MPa) 1 / 2 or less, preferably 23 (MPa) 1 / 2 or more, more preferably 21 (MPa) 1 / 2 or less. The fact that the HSP distance Ra is in such a range means that the affinity between the resin constituting the matrix and each of the sensitizing component and the luminescent component is low. As a result, the movement of the sensitizing component and the luminescent component into the matrix is significantly suppressed, and the sensitizing component and the luminescent component can be stably present in the coloring part.

[0040] HSP is represented by a vector obtained by dividing the Hildebrand solubility parameter into three components: dispersion force (δD), permanent dipole intermolecular force (δP), and hydrogen bonding force (δH), and plotting these in three-dimensional space. It can be determined that those with similar vectors have high solubility. That is, the similarity of solubility can be determined from the HSP distance Ra between them. The definition and calculation of HSP are described in Charles M. Hansen, Hansen Solubility Parameters: A Users Handbook (CRC Press, 2007). HSP values are known for various resins and solvents, and these known values can be used as they are, or values calculated using the computer software HSPiP (Hansen Solubility Parameters in Practice) can be used. Note that this HSPiP also has a database of resins and solvents.

[0041] Resin (HSP values: δD R , δP R , δH R ) and the HSP distance Ra between the sensitizing component or luminescent component (HSP values: δD C , δP C , δH C ) can be calculated by Equation (1). Ra = {4 × (δD R - δD C ) 2 + (δP R - δP C ) 2 + (δH R - δH C ) 2} 1 / 2 ···(1) In Equation (1), δD R represents the dispersion force of the resin, δP R represents the permanent dipole intermolecular force of the resin, δH R represents the hydrogen bonding force of the resin, δD C represents the dispersion force of the sensitizing component or luminescent component, δP C represents the permanent dipole intermolecular force of the sensitizing component or luminescent component, δH C represents the hydrogen bonding force of the sensitizing component or luminescent component, respectively.

[0042] F. Sensitizing Component and Luminescent Component F-1. Sensitizing Component As is clear from the mechanism described in item A, the sensitizing component absorbs light (incident light), becomes an excited triplet state by intersystem crossing from the excited singlet state, and causes triplet-triplet energy transfer to the luminescent component. Examples of the sensitizing component include compounds having a porphyrin structure, a phthalocyanine structure, or a fullerene structure. Such compounds may contain a metal atom in the molecule. Examples of the metal atom include Pt, Pd, Zn, Ru, Re, Ir, Os, Cu, Ni, Co, Cd, Au, Ag, Sn, Sb, Pb, P, and As. Preferably, they are Pt, Pd, and Os. Specific examples of the compounds that can function as the sensitizing component will be described later in item F-3.

[0043] The sensitizing component may be a quantum dot. The quantum dot can be composed of any suitable material. The quantum dot is preferably composed of an inorganic material, more preferably an inorganic conductor material or an inorganic semiconductor material. Examples of the semiconductor material include group II-VI, III-V, IV-VI, and group 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, CdTe, HgS, HgSe, HgTe, BeS, BeSe, BeTe, MgS, MgSe, GeS, GeSe, GeTe, SnS, SnSe, SnTe, PbO, PbS, PbSe, PbTe, CuF, CuCl, CuBr, CuI, Si3N4, Ge3N4, Al2O3, (Al, Ga, In)2(S, Se, Te)3, Al2CO, and combinations (composites) thereof.

[0044] The sensitizing component is preferably 7.00×10 with respect to 1 g of the matrix -9mol to 5.00×10 -6 mol, more preferably 1.00×10 -8 mol to 3.00×10 -6 mol, even more preferably 4.50×10 -8 mol to 2.00×10 -6 mol, and is contained in the upconversion film at such a ratio. When the content of the sensitizing component is within such a range, triplet excitons can be sufficiently generated, and the efficiency leading to triplet-triplet annihilation can be improved.

[0045] F-2. Luminescent component As is clear from the mechanism described in item A, the luminescent component receives triplet-triplet energy transfer from the sensitizing component to generate an excited triplet state, and when the luminescent component molecules in the excited triplet state approach each other at a distance where diffusion, collision, or energy transfer is possible, triplet-triplet annihilation occurs, generating an excited singlet state with a higher energy level. As the luminescent component, various compounds having a condensed aromatic ring are known. Specific examples include compounds having a naphthalene structure, an anthracene structure, a pyrene structure, a perylene structure, a tetracene structure, a Bodipy structure (borondipyrromethene structure), and a diketopyrrolopyrrole structure. Specific examples of compounds that can function as the luminescent component will be described later in item F-3.

[0046] The luminescent component is preferably 5.00×10 -6 mol to 7.00×10 -5 mol, more preferably 6.00×10 -6 mol to 6.00×10 -5 mol, even more preferably 7.00×10 -6 mol to 5.00×10 -5 mol, and is contained in the upconversion film at such a ratio. When the content of the luminescent component is within such a range, the triplet excitons received from the sensitizing dye can be sufficiently diffused among the luminescent component molecules.

[0047] The mixing ratio of the sensitizing component and the luminescent component (sensitizing component:luminescent component) (molar ratio) is, for example, from 1:10 to 1:7000, preferably from 1:25 to 1:3000, more preferably from 1:30 to 1:200, and even more preferably from 1:35 to 1:100. When the mixing ratio is within such a range, the triplet excitons generated from the sensitizing component can efficiently move to the luminescent dye, and deactivation between the luminescent dyes can be suppressed as much as possible, and triplet-triplet annihilation can be achieved well.

[0048] F-3. Combination of Sensitizing Component and Luminescent Component Preferred combinations of the sensitizing component and the luminescent component according to 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 luminescent component that emits (luminesces) 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>

Chemical Formula

Chemical Formula

Chemical Formula

[0050] The sensitizing component that absorbs light in the wavelength region λ1 of 610 nm to 650 nm is the following compound, and the luminescent component that emits (luminesces) 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>

Chemical Formula

Chemical Formula

[0051] The sensitizing component that absorbs light in the wavelength range λ1 of 700 nm to 810 nm is the following compound, and the luminescent component that emits (luminesces) light in the wavelength range λ2 of 500 nm to 700 nm is the following compound. This combination can up-convert near-infrared light into visible light (red light to green light). <Sensitizing component> [Chemical formula] <Luminescent component> [Chemical formula] [Chemical formula]

[0052] The sensitizing component that absorbs light in the wavelength range λ1 of 700 nm to 730 nm is the following compound, and the luminescent component that emits (luminesces) light in the wavelength range λ2 of 400 nm to 500 nm is the following compound. This combination can up-convert near-infrared light into visible light (blue light). <Sensitizing component> [Chemical formula] <Luminescent component> [Chemical formula]

[0053] The sensitizing component that absorbs light in the wavelength range λ1 of 410 nm to 500 nm is the following compound, and the luminescent component that emits (luminesces) light in the wavelength range λ2 of 300 nm to 400 nm is the following compound. This combination can up-convert blue light into ultraviolet light. <Sensitizing component> [Chemical formula] [Chemical formula] <Light-emitting component>

Chem.

Chem.

Chem.

[0054] The sensitizing component that absorbs light in the wavelength region λ1 around 630 nm to 640 nm (for example, 635 nm) is a quantum dot (CdSe, CdSe / ZnS), and the light-emitting component that emits (luminesces) light in the wavelength region λ2 around 440 nm to 460 nm (for example, 450 nm) is the following compound. This combination can up-convert near-infrared light into visible light (blue light). <Light-emitting component>

Chem.

[0055] The sensitizing component that absorbs light in the wavelength region λ1 around 970 nm to 990 nm (for example, 980 nm) is a quantum dot (PbSe, PbS / CdS), and the light-emitting component that emits (luminesces) light in the wavelength region λ2 around 550 nm to 570 nm (for example, 560 nm) is the following compound. This combination can up-convert near-infrared light into visible light (green light). <Light-emitting component>

Chem.

[0056] G. Surfactant The photon upconversion film may further contain a surfactant. When the photon upconversion film contains a surfactant, the dispersibility of the color-developing portion in the matrix can be improved. Examples of the surfactant include cationic surfactants such as hexadecyltrimethylammonium bromide (CTAB), anionic surfactants, and nonionic surfactants, and preferably CTAB. The addition ratio of the surfactant is, for example, 0 parts by mass to 200 parts by mass, preferably 1 part by mass to 50 parts by mass, based on 100 parts by mass of the medium.

[0057] H. Method for manufacturing a photon upconversion film In one embodiment, the method for manufacturing 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 sometimes collectively referred to as "dye solution, etc."); applying the emulsion to a substrate to form a coating film; and drying the coating film. Hereinafter, each step will be specifically described.

[0058] <Preparation of emulsion> In the preparation of the emulsion, first, a dye solution, etc. corresponding to the desired upconversion film is prepared.

[0059] When manufacturing an upconversion film (UC film) using a medium having fluidity at 298 K (24.85 °C), after adding an organic solvent to the medium (specifically, a room-temperature liquid crystal compound and / or a solvent) described in item C above as necessary, the sensitizing component and the light-emitting component described in item F above are added and stirred. By adding an organic solvent to the medium, the solubility of the sensitizing component and the light-emitting component can be improved. 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 solvent can be used alone or in combination. Among such organic solvents, ethers are preferably used, and tetrahydrofuran is more preferably used. The addition ratio of the organic solvent is, for example, 0 parts by mass to 200 parts by mass, preferably 80 parts by mass to 120 parts by mass, based on 100 parts by mass of the fluid medium. In addition, the above-described additives may be added to the medium. The additive may be added to the medium together with the organic solvent, or the additive may be added to the medium alone. When an additive is added to the medium, the viscosity, refractive index, and / or phase transition temperature of the medium can be appropriately adjusted. The addition ratio of the additive is, for example, 0 parts by mass to 200 parts by mass, preferably 5 parts by mass to 100 parts by mass, based on 100 parts by mass of the medium. Also, a plurality of types of liquid crystal compounds, organic solvents, and other additives may be mixed at an arbitrary mixing ratio.

[0060] In addition, when producing an upconversion film (UC film containing a high-temperature liquid crystal compound) using a high-temperature liquid crystal compound, the high-temperature liquid crystal compound described in item C above is heated to a liquid crystal state, and then, if necessary, the above-described organic solvent is added, and the sensitizing component and the light-emitting component described in item F above are added and stirred. The heating temperature of the high-temperature liquid crystal compound can be arbitrarily and appropriately adjusted according to the high-temperature liquid crystal compound. The heating temperature of the high-temperature liquid crystal compound is, for example, the phase transition temperature T between crystal and liquid crystal K-N above, and the phase transition temperature T between liquid crystal and isotropic liquid N-I below. By adding an organic solvent to the high-temperature liquid crystal compound in the liquid crystal state, the solubility of the sensitizing component and the light-emitting component can be improved. The addition ratio of the organic solvent is, for example, 0 parts by mass to 200 parts by mass, preferably 80 parts by mass to 120 parts by mass, based on 100 parts by mass of the high-temperature liquid crystal compound. These methods prepare a dye solution or the like suitable for manufacturing a UC film with a relaxation time of less than 210 ms. The dye solution or the like is typically a medium in which a sensitizing component and a luminescent component are dissolved and / or dispersed.

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

[0062] Also, an aqueous solution of the water-soluble resin described in Item E above is prepared. The concentration of the aqueous solution can be, for example, from 3 wt% to 20 wt%, or for example, from 5 wt% to 10 wt%.

[0063] Next, the aqueous solution of the water-soluble resin and the dye solution or the like are mixed so that the blending amounts of the sensitizing component and the luminescent component with respect to the water-soluble resin (matrix) are within the desired ranges described in Item F above. More specifically, the aqueous solution of the water-soluble resin and the dye solution or the like are mixed, and the mixture is emulsified using a homogenizer. At this time, if necessary, the above-described surfactant is added. As a result, droplets of the dye solution or the like can be preferably dispersed in the aqueous solution of the water-soluble resin, and an emulsion can be prepared. If necessary, the obtained emulsion may be defoamed. Also, the volatile components (e.g., organic solvents) contained in the obtained emulsion may be distilled off under reduced pressure. This can improve the concentrations of the sensitizing component and the luminescent component in the emulsion. The volume fraction of the emulsion particles is, for example, from 5% to 60%. The average particle diameter of the emulsion particles is, for example, from 0.1 μm to 10 μm. If the volume fraction and / or the average particle diameter of the emulsion particles are within such ranges, a color-developing portion having a desired size can be formed as a dispersed phase in the upconversion film.

[0064] <Formation and Drying of Coating Film> Next, the emulsion obtained above is applied to a substrate to form a coating film. Representative examples of the substrate include a resin sheet or glass. As the resin constituting the resin sheet, any suitable resin can be used. 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, acetate-based resins, and other transparent resins. Also, thermosetting resins such as (meth)acrylic-based, urethane-based, (meth)acrylic urethane-based, epoxy-based, and silicone-based resins, or ultraviolet curable resins, etc. can be mentioned. In addition to this, for example, glassy polymers such as siloxane-based polymers can also be mentioned.

[0065] As the coating method, any suitable method can be used. Specific examples include roll coating method, spin coating method, wire bar coating method, dip coating method, die coating method, curtain coating method, spray coating method, knife coating method (comma coating method, etc.). Also, a coating film may be formed using a drum film forming machine. In this case, the film forming roll (drying roll) of the drum film forming machine can function as a substrate. The film forming roll (drying roll) is formed of a metal such as nickel, chromium, copper, iron, or stainless steel, for example. 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 obtained upconversion film falls within the desired range described in item 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] Next, the coating film is dried. Drying is performed 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 film having substantially the same thickness as the obtained upconversion film can be obtained. The dried coating film can typically be naturally cooled to room temperature (23°C). As described above, an upconversion film is prepared. The upconversion film may be separated from the substrate or may be used as a laminate with the substrate without being separable from the substrate.

[0067] I. Uses of the Photon Upconversion Film The upconversion film described in Items A to H above 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 includes laminates and energy conversion devices using such an upconversion film. The laminate includes the upconversion film described in Items A to H above and any suitable film (layer) laminated on the upconversion film. The energy conversion device includes at least the upconversion film described in Items A to H above, and may further include any suitable configuration in addition to the upconversion film.

[0068] I-1. Laminate In the laminate, a first protective layer and a second protective layer may be disposed on each of the light incident surface and the light emitting surface of the upconversion film. Each of the first protective layer and the second protective layer may be omitted according to the purpose. Also, as long as the effects of the present invention can be obtained, any suitable optical member can be disposed between the upconversion film and the first protective layer and / or between the upconversion film and the second protective layer. In one embodiment, the laminate has a structure in which at least from the first protective layer to the second protective layer is integrated. Here, "being integrated from the first protective layer to the second protective layer" means that each member from the first protective layer to the second protective layer constituting the laminate is connected as a whole. The integration can be performed, for example, by bonding adjacent members to each other via an adhesive layer such as an adhesive layer or an adhesive agent layer. Also, a layer having different functions 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 protective layer are integrated via an adhesive layer. The overcoat is composed of any suitable material. Examples of the material of the overcoat include acrylic resins and epoxy resins. In another embodiment, the laminate has a structure 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 it includes a state in which at least one of the members from the first protective layer to the second protective layer constituting the laminate is simply laminated on one or both of the adjacent members. The laminate in this embodiment may have, for example, a structure in which the first protective layer, the upconversion film, and the second protective layer are arranged in this order without passing through an adhesive layer. Also, for example, in this embodiment, the laminate may have a structure in which from the first protective layer to the upconversion film is integrated via an adhesive layer, and the second protective layer is arranged on the light-emitting side of the integrated laminate without passing through an adhesive layer. Also, for example, in this embodiment, the laminate may have a structure in which from the upconversion film to the second protective layer is integrated via an adhesive layer, and the first protective layer is arranged on the light-incident side of the integrated laminate without passing through an adhesive layer.

[0069] I-2. Protective Layer Each of the first protective layer and the second protective layer is formed of any suitable film that can be used as a protective layer of the upconversion film. Specific examples of the material that is the main component of the film include cellulose resins such as triacetyl cellulose (TAC), and transparent resins such as polyester-based, polyvinyl alcohol-based, polycarbonate-based, polyamide-based, polyimide-based, polyethersulfone-based, polysulfone-based, polystyrene-based, polynorbornene-based, polyolefin-based, (meth)acrylic-based, and acetate-based resins. Also included are thermosetting resins or ultraviolet curable resins such as (meth)acrylic-based, urethane-based, (meth)acrylic urethane-based, epoxy-based, and silicone-based resins, and inorganic materials such as glass and silica. In addition, for example, glassy polymers such as siloxane-based polymers are also included. Further, the polymer film described in Japanese Patent Application Laid-Open No. 2001-343529 (WO01 / 37007) can also be used. As the material of this film, for example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and a nitrile group in the side chain can be used. For example, a resin composition having an alternating copolymer composed of isobutene and N-methylmaleimide and an acrylonitrile-styrene copolymer can be mentioned. The polymer film can be, for example, an extruded product of the above resin composition.

[0070] J. Photon upconversion body In the above items A to H, the upconversion film has been described in detail. However, if upconversion is possible in the solid state, it is not limited to the film shape. The photon upconversion body has a solid state under normal temperature (23 °C) and normal pressure (0.1 MPa). Examples of the shape of the photon upconversion body include crystals, powders, and gel shapes. The photon upconversion body is described in the same manner as the upconversion film except for the solution state. Therefore, the description of the photon upconversion body is omitted.

Examples

[0071] Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples. Unless otherwise specified, "parts" and "%" in the examples are based on weight.

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

Chemical formula

Chemical formula

[0073] 2. Preparation of Emulsion To 5 g of an aqueous solution of polyvinyl alcohol (PVA) (9% by mass), 0.4 ml of the solution obtained above was added. While injecting the solution through a tube with an inner diameter of 0.75 mm, it was stirred with a homogenizer until the whole was emulsified (17,500 rpm). Argon gas was blown onto the obtained emulsion for about 2 minutes, and it was stirred using a stirrer (THINKY) for 5 minutes in the mixing mode (2,000 rpm) and for 5 minutes in the defoaming mode (2,200 rpm). In this way, an emulsion was prepared. Note that PVA with a polymerization degree of 1,700 and a saponification degree of 99% was used.

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

[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 luminescent component was changed to a crystal solution of the sensitizing component and the luminescent component prepared as follows. At room temperature (23°C), 100 parts by mass of 5CB (4-cyano-4'-pentylbiphenyl) and 100 parts by mass of tetrahydrofuran (THF) were added and stirred and mixed to prepare a liquid crystal solvent. Next, PtOEP as a sensitizing component and DPA as a luminescent component were dissolved in the liquid crystal solvent to prepare a liquid crystal solution of the sensitizing component and the luminescent component.

[0076] <Example 3> An upconversion 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 luminescent component was changed to a crystal solution of the sensitizing component and the luminescent component prepared as follows. 100 parts by mass of 5OCB (4-cyano-4'-pentyloxybiphenyl) was heated to 60°C in a hot water bath to a liquid crystal state, 100 parts by mass of tetrahydrofuran was added and stirred and mixed to prepare a liquid crystal solvent. Next, PtOEP as a sensitizing component and DPA as a luminescent component were dissolved in the liquid crystal solvent to prepare a liquid crystal solution of the sensitizing component and the luminescent component.

[0078] <Example 5> An upconversion film was obtained in the same manner as in Example 2, except that the PVA aqueous solution was changed to an aqueous solution of polyethylene oxide (PEO) (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: the following chemical formula), and the luminescent component was changed to rubrene (the following chemical formula). The concentration of PdTPTAP in the solution was 0.554 mM, and the concentration of rubrene was 20 mM. That is, the molar ratio of the sensitizing component to the luminescent component was 1:36. <Sensitizing component>

Chem.

Chem.

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

[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 upconversion 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: the above chemical formula) and the luminescent component was changed to rubrene (the above chemical formula). The concentrations for each are 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 upconversion 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 procedure as in Example 4. Also, a glass was placed on a hot plate heated to 80°C, and the liquid crystal solvent was placed on the glass to volatilize THF. As a result, an upconversion body in crystal form was obtained.

[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] <Measurement of Relaxation Time by Time Domain Nuclear Magnetic Resonance (TD-NMR)> The upconversion film or upconversion body obtained in the above Example was cut into strip shapes to obtain samples. The dimension of the short side of the sample was 1.5 cm, the dimension of the long side of the sample was 7 - 12 cm, and about 2 - 4 samples were inserted into the sample tube. Next, the samples in the sample tube were measured at 298 K by the spin-echo method using TD-NMR (pulse NMR), and analyzed by the non-linear least squares method from the free induction decay curve of the spin-spin relaxation of the obtained 1H nuclei to calculate the T2 relaxation time. The results are shown in Tables 1 - 3. As the measurement conditions, the repetition time was 10 s, the number of integrations was 8 times, and the number of measurement points was 50 points. The measurement and relaxation time analysis were performed in the range where the relative signal intensity of the final plot was 0.1 or less and 0.001 or more when the signal intensity of the first plot was normalized to 1. In addition, using the analysis software "TDNMR-A Version 6.9 Rev 2.0" manufactured by BRUKER, fitting was performed in an exponential type with a Weibull coefficient of 1 according to the product manual. When the Weibull coefficient of 1 was not appropriate for the sample, the optimum value was used in the range of 1 - 2. The measurement conditions are described below. Apparatus: Bruker, TD-NMR (the minispec mq20) Detected nuclide: 1 H Measurement temperature: 298 K Measurement method: Spin-echo method Analysis method: Non-linear least squares method Scan: 8 Recycle Deray: 10 sec First 90 - 180 Pulse Separation: 0.0082 Final 90 - 180 Pulse Separation: Adjusted to the conditions described above Number of Data Points for Fitting: 50 When two or more relaxation times were detected, the relaxation times obtained were multiplied by the proton ratio, and the average value was calculated from the relaxation times obtained by summing all components, and this average value was used as the relaxation time.

[0095] <Absolute Quantum Yield Measurement> The absolute quantum yield (converted to 100%) of the upconversion luminescence of the upconversion film or upconversion body (hereinafter referred to as the sample) obtained in the above Examples and Comparative Examples was measured by an absolute quantum yield measurement system Quantaurus - QY Plus C11347 - 02 (manufactured by Hamamatsu Photonics, detection wavelength; 400 - 1100 nm). For the absolute quantum yield measurement, a diode laser (808 nm, 200 mW, 532 nm, 75 mW, 460 nm, 500 mW, RGB Photonics) was used, and the light intensity was adjusted by using the laser output and an ND filter and used as an excitation source. 808 nm is 27000 mW / cm 2 and 532 nm is 31000 mW / cm 2 and 460 nm is 31000 mW / cm 2 The measurement was performed by adjusting the light quantity so that the sample was irradiated with light at these intensities. The measured absolute quantum yields are shown in Tables 1 - 3.

[0096] <Transmittance Measurement> The transmittance of the upconversion film or upconversion body obtained in the above Examples and Comparative Examples was measured by an ultraviolet - visible - near - infrared spectrophotometer UH4150 (manufactured by Hitachi High - Technologies Corporation). For the transmittance measurement, the sample was placed directly in front of the integrating sphere, and the total light transmittance was measured at 1 nm intervals in the wavelength range of 400 nm or more and 800 nm or less. In this case, the average value of the transmittance from 400 nm to 800 nm obtained was used as the average transmittance. The measured average transmittance is 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 spin-echo method of TD-NMR at 298K is less than 210 ms, it is possible to improve the absolute quantum yield and the up-conversion luminescence efficiency.

Industrial Applicability

[0101] The photon up-conversion film and the photon up-conversion body according to the embodiments of the present invention can be suitably used in solar cells or solar power generation, photocatalysts, bioimaging, optical devices, laminates, energy conversion devices, and the like.

Claims

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

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

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

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

5. For 1 g of the water-soluble resin, the sensitizing component is 7.00×10 －９ mol to 5.00×10 －６ mol and the light-emitting component is 5.00×10 －６ mol to 7.00×10 －５ mol, and the photon upconversion film according to claim 1.

6. A method for manufacturing a photon upconversion film according to any one of claims 1 to 5, comprising the steps of 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; coating the emulsion on 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 photon upconversion body comprising 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 that is shorter in wavelength than the first wavelength region λ1; A matrix, wherein the chromophore is dispersed in the matrix as a dispersed phase, the chromophore contains a monomolecular liquid crystal compound, the matrix contains a water-soluble resin, having a relaxation time measured by a spin-echo method using time-domain nuclear magnetic resonance (pulse NMR) at 298K of less than 210 ms.

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