Light conversion adhesive film for sunlight wavelength conversion and preparation method thereof

Abstract

The invention provides a light conversion adhesive film for sunlight wavelength conversion and a preparation method thereof, the light conversion adhesive film comprises a compound of formula I and a substrate transparent to visible light, the definition of each group in the compound of formula I is described in the specification, and the mass fraction of the compound of formula I in the light conversion adhesive film is 0.001%-3%. The light conversion adhesive film can be used for a solar cell so as to enhance the efficiency and the stability of the cell.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of solar cell materials, and particularly relates to a light-conversion adhesive film for sunlight wavelength conversion and a preparation method thereof. BACKGROUND

[0002] Sunlight radiated to the earth's surface is mainly distributed in the interval of 200-2500nm, of which ultraviolet light with a wavelength shorter than 400nm accounts for about 5% of the total energy of sunlight. Limited by the energy band structure of silicon itself, these ultraviolet rays cannot be effectively utilized by silicon-based solar cells, which limits the maximum efficiency of the cell; and due to the high energy of a single photon of ultraviolet light, it may cause degradation of the materials in the solar cell and then lead to device deterioration. Therefore, converting ultraviolet light into a wavelength band that can be utilized by the silicon cell helps to improve the efficiency and service life of the cell at the same time. This conversion can be achieved by introducing a light-emitting wavelength conversion material (hereinafter referred to as light conversion material) into the cell. Through material design or selection, a light conversion material with an absorption spectrum located in the ultraviolet region and an emission spectrum located in the visible light region can be obtained, so that the energy of the ultraviolet light is ultimately used by the cell. Currently, light conversion adhesive films incorporating such materials have been increasingly widely introduced into solar cells.

[0003] The light conversion materials in the prior art include organic fluorescent materials, rare earth materials or quantum dot materials. For example, CN103339221A, CN117431022A, etc. of Rikagaku Co., Ltd. use adhesive films containing triazole fluorescent materials, CN114335353A of Hanwha Total Co., Ltd. uses adhesive films containing fluorescent materials containing pyrene, CN116997633A of Panasonic Intellectual Property Co., Ltd., CN102268261A of Hunan Normal University, CN116970346A of Zhijing Technology Co., Ltd., etc. use adhesive films containing materials containing Eu, Ce, etc. rare earth metals, CN117229728A of Suzhou Hongdao New Material Co., Ltd., CN113035990A of Dalian Institute of Chemical Physics, etc. use adhesive films containing materials containing ZnS, CdS, etc. quantum dots.

[0004] However, the light conversion materials in the above prior art all have certain deficiencies: the cell efficiency of the adhesive film using the organic fluorescent material in the prior art is low; the material containing rare earth metals cannot efficiently convert ultraviolet light into visible light; the quantum dot material is high in cost, has environmental protection hidden dangers, and the technology for large-scale production of stable quantum dots is not perfect.

[0005] Therefore, there is a need in the art for a light conversion adhesive film for sunlight wavelength conversion that can more effectively improve the efficiency and service life of a solar cell. SUMMARY

[0006] The present application is directed to the above-mentioned problems existing in the prior art, and proposes a light conversion film containing a thermally activated delayed fluorescence (TADF) material, which can convert ultraviolet light into sunlight wavelength, and can be used in a solar cell to enhance the efficiency and stability of the cell. The TADF material used in the present application is mainly constructed from cyanophenyl groups and carbazole groups. Such TADF material has a high photoluminescence quantum efficiency (PLQY), and the emission peak is in the range of 450-600 nm, which is matched with the absorption of the silicon-based cell, and is helpful to improve the light conversion efficiency; in addition, the cyanophenyl / carbazole construction units have high light stability, so the corresponding material itself has high stability, and has continuous absorption of light below 420 nm, especially the carbazole group has a strong absorption in the range of 320-350 nm, so the damage of ultraviolet light to the cell is effectively avoided.

[0007] Specifically, the present application provides a light conversion film for sunlight wavelength conversion, the light conversion film comprising a compound of formula I and a matrix,

[0008]

[0009] In formula I, A is a cyano group, a trifluoromethyl group or a cyanophenyl group;

[0010] Ar is an arylene group, preferably a phenylene group, and n is an integer in the range of 0-10;

[0011] D is selected from 9H-carbazol-9-yl which is unsubstituted or substituted by one or more substituents selected from a hydrogen atom, a halogen atom, a C1-C10 alkyl group, a C3-C11 cycloalkyl group, a C6-C14 aryl group, a trifluoromethyl group, an amino group and a diphenylamine group, wherein the C3-C11 cycloalkyl group and the C6-C14 aryl group are optionally substituted by one or more C1-C10 alkyl substituents;

[0012] F1, F2, F3 and F4 are each independently selected from the group consisting of the group A, the group D, a hydrogen atom, a halogen atom, a C6-C14 aryl group and a diphenylamine group, wherein the C6-C14 aryl group is optionally substituted by one or more C1-C10 alkyl groups;

[0013] The mass fraction of the compound of formula I in the light conversion film is 0.001% to 3%.

[0014] In one or more embodiments, the mass fraction of the compound of formula I in the light conversion film is 0.001% to 0.5%.

[0015] In one or more embodiments, the compound of formula I is a compound of formula II,

[0016]

[0017] In formula II, Ar is an arylene group, preferably a phenylene group, and i is an integer from 0 to 10, preferably 0 or 1.

[0018] R1and R2are each independently selected from the group consisting of a hydrogen atom, a halogen atom, a C1-C10alkyl group, a C3-C11cycloalkyl group, a C6-C14aryl group, a trifluoromethyl group, an amino group, and a diphenylamine group, wherein the C3-C11cycloalkyl group and the C6-C14aryl group are optionally substituted with one or more C1-C10alkyl groups;

[0019] F1, F2, F3, and F4are each independently selected from the group consisting of a hydrogen atom, a halogen atom, a C6-C14aryl group, a cyano group, a trifluoromethyl group, a cyanophenyl group, a diphenylamine group, and an unsubstituted or substituted 9H-carbazol-9-yl group substituted with one or more substituents selected from the group consisting of a hydrogen atom, a halogen atom, a C1-C10alkyl group, a C3-C11cycloalkyl group, a C6-C14aryl group, a trifluoromethyl group, an amino group, and a diphenylamine group, wherein the C3-C11cycloalkyl group and the C6-C14aryl group are optionally substituted with one or more C1-C10alkyl groups.

[0020] In one or more embodiments, the compound of formula I is selected from one or more of compounds 3 to 14:

[0021]

[0022] In one or more embodiments, the compound of formula I is selected from one or more of compounds 5, 6, 10, and 14.

[0023] In one or more embodiments, the light conversion adhesive film has a thickness of 0.1-1.0 mm, for example 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm.

[0024] In one or more embodiments, the substrate can be one or more selected from the group consisting of polyethylene terephthalate, polyvinyl butyral, ethylene-vinyl acetate copolymer, polyethylene, ethylene polytetrafluoroethylene, polyimide, polycarbonate, polystyrene, polyurethane, polyacrylate, silicone sol, silicone gel, and polyolefin elastomer.

[0025] In one or more embodiments, the substrate has a refractive index of 1.4-1.7.

[0026] In one or more embodiments, the light conversion adhesive film further comprises one or more auxiliary agents selected from the group consisting of a crosslinking agent, a co-crosslinking agent, a plasticizer, an antioxidant, and a water absorbent.

[0027] In one or more embodiments, the light conversion adhesive film comprises a crosslinking agent and a co-crosslinking agent, and optionally further comprises one or more selected from a plasticizer, an antioxidant, and a water absorbent.

[0028] Another aspect of the present application provides a method for preparing the light conversion adhesive film according to any of the embodiments described herein, the method comprising: mixing the components of the light conversion adhesive film uniformly, melt-extruding into a film, and cooling and setting to obtain the light conversion adhesive film.

[0029] Another aspect of the present application provides a solar cell module comprising the light conversion adhesive film according to any of the embodiments described herein.

[0030] In one or more embodiments, the solar cell module comprises one or more of the following devices: a PN junction device comprising III-V or II-IV elements, a Cu-In-Ga-Se thin film device, an organic sensitizer device, an organic thin film device, a quantum dot thin film device, an amorphous silicon solar cell device, a microcrystalline silicon solar cell device, and a crystalline silicon solar device.

[0031] Another aspect of the present application provides a method for enhancing the efficiency and stability of a solar cell, the method comprising: introducing the light conversion adhesive film according to any of the embodiments described herein into the solar cell.

[0032] In one or more embodiments, the solar cell comprises one or more of the following devices: a PN junction device comprising III-V or II-IV elements, a Cu-In-Ga-Se thin film device, an organic sensitizer device, an organic thin film device, a quantum dot thin film device, an amorphous silicon solar cell device, a microcrystalline silicon solar cell device, and a crystalline silicon solar device. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 Absorption-emission spectra of Compound 5, Compound 6, Compound 10, and Compound 14 used in the present application.

[0034] Figure 2 Absorption-emission spectra of fluorescent dyes used in Compound 5 and Comparative Example 2 of the present application. DETAILED DESCRIPTION

[0035] In order that those skilled in the art can understand the features and effects of the present application, the following is a general description and definition of the terms and phrases mentioned herein. Unless otherwise specified, all technical and scientific words used herein are used in the ordinary meaning understood by those skilled in the art of the present application, and in the event of a conflict, the definition in the present specification shall prevail.

[0036] Theories and mechanisms described and disclosed herein, whether correct or not, should not be considered limiting of the scope of the present application, which is defined by the claims. The description and examples are provided to illustrate the present application and to assist in understanding the application.

[0037] As used herein, the terms "comprises", "comprising", "includes", "including" and the like are inclusive of the stated features and do not exclude the presence of other features. As used herein, the term "consisting essentially of" means including the recited features and any additional features that do not materially alter the basic and novel characteristics of the application.

[0038] As used herein, all features of a numerical range or a percentage range, such as numerical values, amounts, contents and concentrations, are merely for the sake of brevity and convenience. Accordingly, the description of a numerical range or a percentage range should be considered to have encompassed and specifically disclosed all possible sub-ranges and individual numerical values (including integers and fractions) within the range.

[0039] As used herein, unless otherwise specified, percentages are by mass percentage and ratios are by mass ratio.

[0040] As used herein, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. As used herein, the term "comprises" means "includes, but is not limited to", the term "comprising" means "including, but not limited to".

[0041] As used herein, the various technical features in each embodiment or example are not intended to be limited to the described embodiments or examples. Rather, all alternatives, modifications, equivalents and equivalents of the described methods and materials are included within the scope of the present application.

[0042] The ideal light conversion material in the light conversion adhesive film for solar cells should have strong absorption for wavelengths below 400 nm, large Stokes shift, wide emission spectrum, and high PLQY. Although the organic fluorescent materials in the prior art have high PLQY, the Stokes shift is usually small, which results in that they can only convert ultraviolet light into deep blue light (<450 nm), which is still far from the highest efficiency band of silicon-based cells; or their absorption is greatly overlapped with the absorption of the silicon cell itself, affecting the cell efficiency. Although rare earth materials have a large Stokes shift, their luminescence peak is very narrow, and the PLQY is usually low, which cannot efficiently convert ultraviolet light into visible light.

[0043] The use of TADF materials as light conversion materials in the film can achieve the purpose of efficient conversion of ultraviolet light to visible light. TADF materials have a donor-aryl-acceptor structure, so the corresponding excited state is usually a charge transfer (CT) excited state. The structure of the molecule in the CT state is usually quite different from its ground state structure, resulting in a large Stokes shift (red shift of the emission spectrum compared to the absorption spectrum); at the same time, the molecular structure is more relaxed under the CT excited state, so the emission spectrum width of the material is significantly larger than that of materials with localized excitation (corresponding to traditional fluorescent materials) and f-f transition (corresponding to rare earth materials). Therefore, compared with the prior art, the advantages of TADF materials are: they usually have a large Stokes shift and a wide emission spectrum, and can achieve high PLQY. Therefore, the use of TADF materials with an absorption spectrum in the ultraviolet region in the present application can more efficiently convert ultraviolet light into a wavelength with higher solar cell utilization efficiency, thereby improving the efficiency and life of the cell.

[0044] The light conversion film of the present application comprises a TADF material comprising a donor (D)-aryl-acceptor (A) structure and a matrix transparent to visible light. The mass fraction of the TADF material in the light conversion film can be 0.001% to 3%. In some preferred embodiments, the mass fraction of the TADF material in the light conversion film is 0.001% to 0.5%, more preferably 0.01% to 0.5%, further preferably 0.05% to 0.5%, for example 0.1%, 0.2%, 0.3%, 0.4%. Controlling the amount of TADF material selected for use in the light conversion film in the preferred range described above is beneficial to improving the effect of the light conversion film on enhancing the efficiency and stability of the cell.

[0045] Further, the light conversion film of the present application optionally or preferably comprises an auxiliary agent. The available auxiliary agents include but are not limited to crosslinking agents, co-crosslinking agents, plasticizers, antioxidants, water absorbents, etc.

[0046] In some embodiments, the light conversion film of the present application is composed of a light conversion material, a matrix and an optional auxiliary agent.

[0047] The compound of formula I

[0048] In some preferred embodiments, the light conversion film comprises a compound of formula I as a TADF material and a matrix,

[0049]

[0050] In formula I, A is a cyano group, a trifluoromethyl group or a cyanophenyl group;

[0051] Ar is an arylene group, preferably a phenylene group, and n is an integer from 0 to 10;

[0052] D is selected from the group consisting of 9H-carbazol-9-yl which is unsubstituted or substituted by one or more substituents selected from the group consisting of hydrogen atoms, halogen atoms, C1-C10 alkyl groups, C3-C11 cycloalkyl groups, C6-C14 aryl groups, trifluoromethyl groups, amino groups and diphenylamine groups, wherein the C3-C11 cycloalkyl groups and the C6-C14 aryl groups optionally can be substituted by one or more C1-C10 alkyl groups;

[0053] F1, F2, F3 and F4 are each independently selected from the group consisting of the group A, the group D, hydrogen atoms, halogen atoms, C6-C14 aryl groups and diphenylamine groups, wherein the C6-C14 aryl groups optionally can be substituted by one or more C1-C10 alkyl groups;

[0054] The mass fraction of the compound of formula I in the light conversion adhesive film is 0.001% to 3%.

[0055] In the compound of formula I, the group A is an electron acceptor and the group D is an electron donor.

[0056] Herein, the cyanophenyl group is preferably a 4-cyanophenyl group.

[0057] In some preferred embodiments, A is a cyano group or a cyanophenyl group. This is advantageous for improving the effect of the light conversion adhesive film on enhancing the efficiency and stability of the battery.

[0058] In some preferred embodiments, in formula I, n is 0, i.e. Ar is absent, and the group A is directly connected to . This is advantageous for improving the effect of the light conversion adhesive film on enhancing the efficiency and stability of the battery. Herein, * indicates the position at which the group is connected to the rest of the molecule.

[0059] In formula I, D can be a 9H-carbazol-9-yl group or a 9H-carbazol-9-yl group substituted by one or more (e.g. 1, 2, 3, 4, 5, 6, 7, 8) substituents. The substituents on the 9H-carbazol-9-yl group are selected from the group consisting of hydrogen atoms, halogen atoms, C1-C10 alkyl groups, C3-C11 cycloalkyl groups, C6-C14 aryl groups, trifluoromethyl groups, amino groups and diphenylamine groups.

[0060] In the present application, an alkyl group refers to a monovalent saturated group having a straight chain or branched chain structure composed of carbon atoms and hydrogen atoms. In the present application, the number of Cs before a group indicates the number of carbon elements contained in the group, for example, a C1 alkyl group indicates an alkyl group containing 1 carbon atom, i.e. a methyl group. Alkyl groups suitable for use in the present application can be C1-C10 alkyl groups, for example, C1 alkyl groups, C2 alkyl groups, C3 alkyl groups, C4 alkyl groups, C5 alkyl groups, C6 alkyl groups, C7 alkyl groups, C8 alkyl groups, C9 alkyl groups, C10 alkyl groups. Examples of C4 alkyl groups include a tert-butyl group (t-Bu).

[0061] In the present application, cycloalkyl refers to a monovalent saturated group having a ring structure of aliphatic carbon atoms and hydrogen atoms, and the cycloalkyl is attached to the rest of the molecule through a carbon atom on the ring of aliphatic carbon atoms. Cycloalkyl groups suitable for use in the present application can be C3-C11 cycloalkyl groups, such as C3 cycloalkyl, C4 cycloalkyl, C5 cycloalkyl, C6 cycloalkyl, C7 cycloalkyl, C8 cycloalkyl, C9 cycloalkyl, C10 cycloalkyl, C11 cycloalkyl.

[0062] In the present application, aryl refers to a monovalent group consisting of carbon and hydrogen atoms having an aromatic ring structure, and the aryl is attached to the rest of the molecule through a carbon atom on the aromatic ring. Aryl groups suitable for use in the present application can be C6-C14 aryl groups, including but not limited to C6 aryl (e.g., phenyl), C10 aryl (e.g., naphthyl), C14 aryl (e.g., anthryl, phenanthryl).

[0063] In the present application, halogen includes fluorine, chlorine, bromine, iodine.

[0064] In some preferred embodiments, D is 9H-carbazol-9-yl or 9H-carbazol-9-yl substituted with 1-3 aforementioned substituents, preferably 9H-carbazol-9-yl or 9H-carbazol-9-yl substituted with 2 aforementioned substituents. The substituents on the 9H-carbazol-9-yl are preferably selected from C1-C10 alkyl and C6-C14 aryl, more preferably selected from C1-C6 alkyl and C6-C10 aryl, for example selected from t-butyl (t-Bu) and phenyl (Ph). This is advantageous for improving the effect of the light conversion adhesive film on enhancing the efficiency and stability of the battery.

[0065] In some preferred embodiments, F1, F3 and F4 are each independently selected from 9H-carbazol-9-yl and 9H-carbazol-9-yl substituted with 1-3 aforementioned substituents, preferably selected from 9H-carbazol-9-yl and 9H-carbazol-9-yl substituted with 2 aforementioned substituents. The substituents on the 9H-carbazol-9-yl are preferably selected from C1-C10 alkyl and C6-C14 aryl, more preferably selected from C1-C6 alkyl and C6-C10 aryl, for example selected from t-butyl (t-Bu) and phenyl (Ph). The two substituents on the 9H-carbazol-9-yl are preferably located on two phenyl rings of the 9H-carbazol-9-yl, more preferably on the 3rd and 6th positions of the 9H-carbazol-9-yl, respectively. This is advantageous for improving the effect of the light conversion adhesive film on enhancing the efficiency and stability of the battery.

[0066] In some preferred embodiments, each of F1, F3 and F4 is independently selected from 9H-carbazol-9-yl substituted with 1 to 3 of the aforementioned substituents, preferably from 9H-carbazol-9-yl substituted with 2 of the aforementioned substituents. The substituents on the 9H-carbazol-9-yl are preferably selected from C1-C10 alkyl and C6-C14 aryl, more preferably from C1-C6 alkyl and C6-C10 aryl, for example from tert-butyl and phenyl. The 2 substituents on the 9H-carbazol-9-yl are preferably on the two phenyl rings of the 9H-carbazol-9-yl, more preferably on the 3rd and 6th positions of the 9H-carbazol-9-yl, respectively. This is advantageous for improving the effect of the light conversion adhesive film on enhancing the efficiency and stability of the battery.

[0067] In some preferred embodiments, F2 is 9H-carbazol-9-yl, 9H-carbazol-9-yl substituted with 1 to 3 of the aforementioned substituents, a hydrogen atom or a cyanophenyl group. The substituents on the 9H-carbazol-9-yl are preferably selected from C1-C10 alkyl and C6-C14 aryl, more preferably from C1-C6 alkyl and C6-C10 aryl, for example from tert-butyl and phenyl. The 2 substituents on the 9H-carbazol-9-yl are preferably on the two phenyl rings of the 9H-carbazol-9-yl, more preferably on the 3rd and 6th positions of the 9H-carbazol-9-yl, respectively. This is advantageous for improving the effect of the light conversion adhesive film on enhancing the efficiency and stability of the battery.

[0068] In some preferred embodiments, F2 is 9H-carbazol-9-yl substituted with 1 to 3 of the aforementioned substituents, a hydrogen atom or a cyanophenyl group, more preferably 9H-carbazol-9-yl substituted with 2 of the aforementioned substituents or a cyanophenyl group, more preferably 9H-carbazol-9-yl substituted with 2 of the aforementioned substituents. The substituents on the 9H-carbazol-9-yl are preferably selected from C1-C10 alkyl and C6-C14 aryl, more preferably from C1-C6 alkyl and C6-C10 aryl, for example from tert-butyl and phenyl. The 2 substituents on the 9H-carbazol-9-yl are preferably on the two phenyl rings of the 9H-carbazol-9-yl, more preferably on the 3rd and 6th positions of the 9H-carbazol-9-yl, respectively. This is advantageous for improving the effect of the light conversion adhesive film on enhancing the efficiency and stability of the battery.

[0069] In the present application, the 3rd and 6th positions of the 9H-carbazol-9-yl are shown in the following formula:

[0070] wherein * indicates the position at which the 9H-carbazol-9-yl is connected to the rest of the compound.

[0071] Compound of formula II

[0072] In some preferred embodiments, the light conversion adhesive film comprises a compound of formula II as a TADF material and a matrix,

[0073]

[0074] In formula II, Ar is an arylene group, preferably a phenylene group, and i is an integer from 0 to 10, preferably 0 or 1.

[0075] R1and R2are each independently selected from the group consisting of a hydrogen atom, a halogen atom, a C1-C10alkyl group, a C3-C11cycloalkyl group, a C6-C14aryl group, a trifluoromethyl group, an amino group, and a diphenylamine group, wherein the C3-C11cycloalkyl group and the C6-C14aryl group are optionally substituted with one or more C1-C10alkyl groups;

[0076] F1, F2, F3, and F4are each independently selected from the group consisting of a hydrogen atom, a halogen atom, a C6-C14aryl group, a cyano group, a trifluoromethyl group, a cyanophenyl group, a diphenylamine group, and a 9H-carbazol-9-yl group which is unsubstituted or substituted with one or more substituents selected from the group consisting of a hydrogen atom, a halogen atom, a C1-C10alkyl group, a C3-C11cycloalkyl group, a C6-C14aryl group, a trifluoromethyl group, an amino group, and a diphenylamine group, wherein the C3-C11cycloalkyl group and the C6-C14aryl group are optionally substituted with one or more C1-C10alkyl groups.

[0077] In some preferred embodiments, R1and R2are each independently selected from the group consisting of H, a C1-C10alkyl group, and a C6-C14aryl group, more preferably from the group consisting of H, a C1-C6alkyl group, and a C6-C10aryl group, for example from the group consisting of H, a tert-butyl group, and a phenyl group, and further preferably from the group consisting of a C1-C6alkyl group and a C6-C10aryl group, for example from the group consisting of a tert-butyl group and a phenyl group. This is advantageous for improving the effect of the light conversion adhesive film on enhancing the efficiency and stability of the battery.

[0078] In some preferred embodiments, F1, F3, and F4are each independently selected from the group consisting of a 9H-carbazol-9-yl group and a 9H-carbazol-9-yl group substituted with one to three of the aforementioned substituents, preferably from the group consisting of a 9H-carbazol-9-yl group and a 9H-carbazol-9-yl group substituted with two of the aforementioned substituents. The substituents on the 9H-carbazol-9-yl group are preferably selected from the group consisting of a C1-C10alkyl group and a C6-C14aryl group, more preferably from the group consisting of a C1-C6alkyl group and a C6-C10aryl group, for example from the group consisting of a tert-butyl group and a phenyl group. The two substituents on the 9H-carbazol-9-yl group are preferably located on two phenyl rings of the 9H-carbazol-9-yl group, respectively, and more preferably on the 3rdand 6thpositions of the 9H-carbazol-9-yl group, respectively. This is advantageous for improving the effect of the light conversion adhesive film on enhancing the efficiency and stability of the battery.

[0079] In some preferred embodiments, each of F1, F3 and F4 is independently selected from 9H-carbazol-9-yl substituted with 1 to 3 of the aforementioned substituents, preferably from 9H-carbazol-9-yl substituted with 2 of the aforementioned substituents. The substituents on the 9H-carbazol-9-yl are preferably selected from C1-C10 alkyl and C6-C14 aryl, more preferably from C1-C6 alkyl and C6-C10 aryl, for example from tert-butyl and phenyl. The 2 substituents on the 9H-carbazol-9-yl are preferably on the two phenyl rings of the 9H-carbazol-9-yl, respectively, more preferably on the 3rd and 6th positions of the 9H-carbazol-9-yl, respectively. This is advantageous for improving the effect of the light conversion adhesive film on enhancing the efficiency and stability of the battery.

[0080] In some preferred embodiments, F2 is 9H-carbazol-9-yl, 9H-carbazol-9-yl substituted with 1 to 3 of the aforementioned substituents, a hydrogen atom or a cyanophenyl group. The substituents on the 9H-carbazol-9-yl are preferably selected from C1-C10 alkyl and C6-C14 aryl, more preferably from C1-C6 alkyl and C6-C10 aryl, for example from tert-butyl and phenyl. The 2 substituents on the 9H-carbazol-9-yl are preferably on the two phenyl rings of the 9H-carbazol-9-yl, respectively, more preferably on the 3rd and 6th positions of the 9H-carbazol-9-yl, respectively. This is advantageous for improving the effect of the light conversion adhesive film on enhancing the efficiency and stability of the battery.

[0081] In some preferred embodiments, F2 is 9H-carbazol-9-yl, 9H-carbazol-9-yl substituted with 1 to 3 of the aforementioned substituents, a hydrogen atom or a cyanophenyl group, more preferably 9H-carbazol-9-yl substituted with 2 of the aforementioned substituents or a cyanophenyl group, more preferably 9H-carbazol-9-yl substituted with 2 of the aforementioned substituents. The substituents on the 9H-carbazol-9-yl are preferably selected from C1-C10 alkyl and C6-C14 aryl, more preferably from C1-C6 alkyl and C6-C10 aryl, for example from tert-butyl and phenyl. The 2 substituents on the 9H-carbazol-9-yl are preferably on the two phenyl rings of the 9H-carbazol-9-yl, respectively, more preferably on the 3rd and 6th positions of the 9H-carbazol-9-yl, respectively. This is advantageous for improving the effect of the light conversion adhesive film on enhancing the efficiency and stability of the battery.

[0082] Compound 3 - Compound 14

[0083] In some preferred embodiments, the light conversion adhesive film comprises as the TADF material a compound selected from one or more of compounds 3 to 14 and a matrix:

[0084]

[0085] In some preferred embodiments, the TADF material is selected from one or more of Compound 4, Compound 5, Compound 7, Compound 8, Compound 10, Compound 11, Compound 13, and Compound 14. In some more preferred embodiments, the TADF material is selected from one or more of Compound 4, Compound 5, Compound 13, and Compound 14. In some more preferred embodiments, the TADF material is selected from one or both of Compound 4 and Compound 5. This is advantageous for enhancing the effect of the light conversion adhesive film on improving the efficiency and stability of the battery.

[0086] In some embodiments, the TADF material can be selected from one or more of Compound 5, Compound 6, Compound 10, and Compound 14. In some preferred embodiments, the TADF material can be selected from one or both of Compound 5 and Compound 14. In some preferred embodiments, the TADF material is Compound 5. This is advantageous for enhancing the effect of the light conversion adhesive film on improving the efficiency of the battery.

[0087] In the present application, the hydrogen atom in the compound of Formula I, the compound of Formula II, and Compound 3 to Compound 14 as the light conversion material can be protium or deuterium.

[0088] Source of the compound

[0089] In the present application, the compound of formula I, the compound of formula II, the compound 3 to the compound 14 as light conversion material can be prepared by referring to the method in the following literature: Zhang et al. Sterically shielded blue thermally activated delayed fluorescence emitters with improved efficiency and stability. Mater. Horiz., 2016, 3, 145-151. (DOI https: / / doi.org / 10.1039 / C5MH00258C); Uoyama et al. Highly efficient organic light-emitting diodes from delayed fluorescence. Nature, 2012, 492, 234-238. (DOI https: / / doi.org / 10.1038 / nature11687); Zhang et al. Efficient and Stable Deep-Blue Fluorescent Organic Light-Emitting Diodes Employing a Sensitizer with Fast Triplet Upconversion. Adv. Mater. 2020, 32, 1908355. (DOI https: / / doi.org / 10.1002 / adma.201908355).

[0090] The compound of formula I, the compound of formula II, the compound 3 to the compound 14 can also be purchased by a commercially available route.

[0091] Matrix

[0092] In the present application, the matrix is transparent to visible light. The transmittance of the matrix to visible light is preferably ≥ 85%.

[0093] The material of the matrix can be one or more selected from polyethylene terephthalate, polyvinyl butyral, ethylene-vinyl acetate copolymer (EVA for short), polyethylene, ethylene polytetrafluoroethylene, polyimide, polycarbonate, polystyrene, polyurethane, polyacrylate, silicone sol, silicone gel and polyolefin elastomer. In some embodiments, the material of the matrix is EVA.

[0094] The refractive index of the matrix is preferably 1.4-1.7, for example 1.5, 1.6. This is conducive to improving the effect of light conversion adhesive film on enhancing the efficiency and stability of the battery.

[0095] The mass fraction of the matrix in the light-conversion adhesive film can be 80% to 99.8%, for example, 90%, 95%, 96%, 97%, 98%, 98.5%, 99%, 99.5%.

[0096] Auxiliary agent

[0097] The auxiliary agent suitable for the present application includes, but is not limited to, those selected from cross-linking agent, auxiliary cross-linking agent, plasticizer, antioxidant, and water-absorbing agent, etc.

[0098] In some preferred embodiments, the auxiliary agent includes a cross-linking agent, for example, tert-butyl peroxy isopropyl carbonate. The mass fraction of the cross-linking agent in the light-conversion adhesive film is preferably 0.1% to 1%, for example, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%. This is conducive to improving the effect of the light-conversion adhesive film on enhancing the efficiency and stability of the battery.

[0099] In some preferred embodiments, the auxiliary agent includes an auxiliary cross-linking agent, for example, trimethylolpropane tetraacrylate. The mass fraction of the cross-linking agent in the light-conversion adhesive film is preferably 0.1% to 1%, for example, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%. This is conducive to improving the effect of the light-conversion adhesive film on enhancing the efficiency and stability of the battery.

[0100] In some preferred embodiments, the matrix is EVA, the cross-linking agent is tert-butyl peroxy isopropyl carbonate, and the auxiliary cross-linking agent is trimethylolpropane tetraacrylate. This is conducive to improving the effect of the light-conversion adhesive film on enhancing the efficiency and stability of the battery.

[0101] In the present application, the plasticizer, antioxidant, and water-absorbing agent are optionally or preferably added to the light-conversion adhesive film, and the amount thereof can be conventional.

[0102] Preparation method of light-conversion adhesive film

[0103] The light-conversion adhesive film of the present application can be prepared by uniformly mixing the components of the light-conversion adhesive film, melt-extruding the mixture into a film, and then cooling and setting the film.

[0104] The temperature for melt-extrusion can be 80 to 120°C, for example, 90°C, 100°C, 110°C. The cooling and setting can be performed at room temperature (for example, 25°C).

[0105] Solar cell module

[0106] In a high-temperature and negative-pressure environment, the light conversion adhesive film of the present application is used as a front adhesive film to laminate and package a solar cell (for example, a single-crystal silicon solar cell) and a back adhesive film (the material can be pure EVA) on a back plate (for example, a glass plate), and after cooling the assembly, the light conversion adhesive film becomes the front surface of the assembly, and the back adhesive film becomes the back surface of the assembly, thereby obtaining a solar cell assembly.

[0107] The present application has the following beneficial technical effects: the light conversion material in the light conversion adhesive film for solar cells is a TADF material with a more matched emission spectrum to silicon cells, the present application introduces such a material to improve the quantum efficiency of silicon-based cells, and effectively absorbs ultraviolet light below 400 nm, thereby improving the efficiency and stability of the cells. In the present application, the efficiency of the cell can be evaluated by the power improvement rate of the cell assembly, and the stability of the cell can be evaluated by the power stability of the cell assembly after UV aging.

[0108] The present application will be described below in the manner of specific examples. It should be understood that these examples are merely illustrative and are not intended to limit the scope of the present application. The methods, reagents and materials used in the examples are conventional in the art unless otherwise specified. The raw compound in the examples can be purchased by commercial means.

[0109] Example 1

[0110] This example provides an adhesive film using compound 5 (R is t-Bu) as a light conversion material and a corresponding device. Compound 5 used in Example 1 is purchased from Xi'an Yuray Solar Energy Technology Co., Ltd. R is t-Bu) as a light conversion material and a corresponding device. Compound 5 used in Example 1 is purchased from Xi'an Yuray Solar Energy Technology Co., Ltd.

[0111] This example manufactures a light conversion adhesive film by the following method:

[0112] According to the total mass of the light conversion adhesive film, 98.9%wt of EVA, 0.1%wt of compound 5, 0.5%wt of tert-butyl peroxy isopropyl carbonate as a crosslinking agent, and 0.5%wt of trimethylolpropane tetraacrylate as a co-crosslinking agent are uniformly mixed, then melted and extruded into a film at 100℃, and the extruded adhesive film is cooled and shaped at 25℃ to obtain the light conversion adhesive film of Example 1, with a thickness of 0.3mm.

[0113] This example manufactures a solar cell assembly by the following method:

[0114] In a negative-pressure environment at 130℃, the packaging glass, the above light conversion adhesive film, the 182mm HJT solar cell of Huasheng New Energy Technology Co., Ltd., the pure EVA polymer layer, and the glass back plate are laminated and packaged. After lamination, the assembly is naturally cooled, the light conversion adhesive film layer becomes the front surface of the cell, and the pure EVA adhesive film layer becomes the back surface of the cell, thereby finally obtaining the solar cell assembly of Example 1.

[0115] Example 2

[0116] Example 2 light conversion adhesive film and solar module were prepared by similar method as Example 1, but the difference is that compound 5 was replaced by the same mass fraction of compound 6 R is H) used in the light conversion adhesive film. Compound 6 used in Example 2 was purchased from Xi'an Yurayl Solar Technology Co., Ltd.

[0117] Example 3

[0118] Example 3 light conversion adhesive film and solar module were prepared by similar method as Example 1, but the difference is that compound 5 was replaced by the same mass fraction of compound 10 R is Ph) used in the light conversion adhesive film. Compound 10 used in Example 3 was purchased from Xi'an Yurayl Solar Technology Co., Ltd.

[0119] Example 4

[0120] Example 4 light conversion adhesive film and solar module were prepared by similar method as Example 1, but the difference is that compound 5 was replaced by the same mass fraction of compound 14 R is t-Bu) used in the light conversion adhesive film. Compound 14 used in Example 4 was purchased from Xi'an Yurayl Solar Technology Co., Ltd.

[0121] Comparative Example 1

[0122] Comparative Example 1 adhesive film and solar module were prepared by similar method as Example 1, but the difference is that no light conversion material was added, and the adhesive film components were 99.0%wt EVA, 0.5%wt tert-butyl peroxy isopropyl carbonate and 0.5%wt trimethylolpropane tetraacrylate.

[0123] Comparative Example 2

[0124] Comparative Example 2 light conversion adhesive film and solar module were prepared by similar method as Example 1, but the difference is that compound 5 was replaced by the same mass fraction of traditional fluorescent material, whose molecular structure is: This fluorescent material was purchased from Shanghai Bide Pharmaceutical Technology Co., Ltd.

[0125] Test Example

[0126] I. Photophysical property test: photophysical test was performed on the light conversion materials in each example and comparative example using ultraviolet-visible spectrometer, fluorescence spectrometer and integrating sphere. The absorption spectrum of the material was determined by Agilent Cary 3500 ultraviolet-visible spectrometer, and the emission spectrum and PLQY were determined by Horiba spectrometer FL-3 and its integrating sphere accessories. The results are as follows Figure 1 ,Figure 2 , as shown in Table 1.

[0127] From Figure 1 , Figure 2 and Table 1, it can be found that compared with the conventional fluorescent material in Comparative Example 2, the TADF material in the examples has a larger Stokes shift (~100 nm), a wider spectrum (FWHM > 50 nm), while the PLQY (0.7-0.9) is not significantly lower than that of the conventional fluorescent material. This is because the emission of the conventional fluorescent material comes from the localized excited state of the fused ring aromatic hydrocarbon. Due to the rigidity of the fused ring aromatic hydrocarbon structure, the relaxation of the excited state is small, so the degree of overlap between absorption and emission is large and the spectrum is approximately symmetrically distributed. While the emission of the TADF material comes from the CT excitation between the donor and the acceptor. The structure of the CT excited state is significantly different from that of the ground state and the excited state structure is relaxed, and the conformation changes are rich, so the degree of overlap between absorption and emission is small and the emission spectrum is wider. It can be found from the observation of the absorption spectrum of silicon that its absorption increases rapidly at 400-500 nm and gradually reaches a peak after 500 nm. Therefore, the TADF material with larger Stokes shift and wider emission peak can convert the short-wave component in sunlight into a band with higher utilization efficiency for silicon-based cells.

[0128] Table 1: Comparison of photophysical properties of light conversion materials in examples and comparative examples

[0129]

[0130] II. Device performance test: In order to evaluate the performance of the solar cell module to illustrate the effect of the present application, the power test and UV aging test of the solar cell module in each example and comparative example were carried out. The power test used ANPA1000 tester of Shandong Aino Instrument Co., Ltd., and the UV aging used 142W multi-fold UV aging box at 70°C for UV 120h aging, and the results are shown in Table 2.

[0131] From Table 2, it can be found that when the other components of the adhesive film and the production conditions are close, compared with the adhesive film without light conversion material, the light conversion adhesive film containing the light conversion material of the present application can improve the efficiency and stability of the battery. This is because the TADF material effectively absorbs and converts ultraviolet light, avoiding its damage to the battery. At the same time, the TADF material composed of cyanobenzene and carbazole and other stable building blocks is relatively stable to ultraviolet light; combined with its high PLQY (0.7-0.9), it can efficiently convert ultraviolet light into visible light, inhibiting the occurrence of photochemical reactions that may cause material decomposition. In compounds 5-14, many compounds introduce tert-butyl and phenyl groups at the 3rd and 6th positions of the carbazole group, which is to avoid chemical reaction between the adjuvant in the adhesive film and the light conversion material.

[0132] Table 2: Comparison of the efficiency and the decay rate of the solar cell devices in the examples and comparative examples

[0133]

Claims

1. A light-converting adhesive film for sunlight wavelength conversion, characterized in that, The light-converting film comprises a compound of formula I and a matrix that is transparent to visible light. In Formula I, A is cyano, trifluoromethyl, or cyanophenyl; Ar is arylene, preferably phenylene, and n is an integer from 0 to 10; D is selected from 9H-carbazole-9-yl, either unsubstituted or substituted with one or more substituents selected from hydrogen atom, halogen atom, C1-C10 alkyl, C3-C11 cycloalkyl, C6-C14 aryl, trifluoromethyl, amino and diphenylamine, wherein the C3-C11 cycloalkyl and C6-C14 aryl may optionally be substituted with one or more C1-C10 alkyl groups; F1, F2, F3 and F4 are each independently selected from group A, group D, hydrogen atom, halogen atom, C6-C14 aryl and diphenylamino group, wherein the C6-C14 aryl group may optionally be substituted by one or more C1-C10 alkyl groups; The mass fraction of the compound of formula I in the optical transfer film is 0.001% to 3%.

2. The light-converting adhesive film as described in claim 1, characterized in that, The mass fraction of the compound of formula I in the optical transfer film is 0.001% to 0.5%.

3. The light-converting adhesive film as described in claim 1, characterized in that, The compound of formula I is a compound of formula II. In Formula II, Ar is arylene, preferably phenylene, and i is an integer from 0 to 10, preferably 0 or 1; R1 and R2 are each independently selected from hydrogen atoms, halogen atoms, C1-C10 alkyl, C3-C11 cycloalkyl, C6-C14 aryl, trifluoromethyl, amino and diphenylamino groups, wherein the C3-C11 cycloalkyl and C6-C14 aryl groups may optionally be substituted by one or more C1-C10 alkyl groups. F1, F2, F3, and F4 are each independently selected from hydrogen atom, halogen atom, C6-C14 aryl, cyano, trifluoromethyl, cyanophenyl, diphenylamino, and 9H-carbazole-9-yl, which is unsubstituted or substituted with one or more substituents selected from hydrogen atom, halogen atom, C1-C10 alkyl, C3-C11 cycloalkyl, C6-C14 aryl, trifluoromethyl, amino, and diphenylamino, wherein the C3-C11 cycloalkyl and C6-C14 aryl may optionally be substituted with one or more C1-C10 alkyl groups.

4. The light-converting adhesive film as described in claim 1, characterized in that, The compound of formula I is selected from one or more of compounds 3 to 14:

5. The light-converting adhesive film as described in claim 4, characterized in that, The compound of Formula I is selected from one or more of Compound 5, Compound 6, Compound 10 and Compound 14.

6. The light-converting adhesive film as described in claim 1, characterized in that, The light-converting adhesive film has one or more of the following characteristics: The thickness of the light-converting adhesive film is 0.1-1.0 mm; The matrix may be one or more selected from polyethylene terephthalate, polyvinyl butyral, ethylene-vinyl acetate copolymer, polyethylene, ethylene polytetrafluoroethylene, polyimide, polycarbonate, polystyrene, polyurethane, polyacrylate, siloxane sol, siloxane gel and polyolefin elastomer. The refractive index of the matrix is ​​1.4-1.

7.

7. The light-converting adhesive film as described in claim 1, characterized in that, The light-converting film further includes one or more additives selected from crosslinking agents, co-crosslinking agents, plasticizers, antioxidants, and water-absorbing agents; preferably, the light-converting film includes crosslinking agents and co-crosslinking agents, and optionally also includes one or more additives selected from plasticizers, antioxidants, and water-absorbing agents.

8. A method for preparing the light-transfer adhesive film according to any one of claims 1-7, characterized in that, The method includes: mixing the components of the light-converting adhesive film evenly, melting and extruding them into a film, and cooling and shaping it to obtain the light-converting adhesive film.

9. A solar cell module, characterized in that, The solar cell module includes the light-converting adhesive film according to any one of claims 1-7; Preferably, the solar cell module includes one or more of the following devices: PN junction device containing group III-V or II-IV elements, Cu-In-Ga-Se thin film device, organic sensitizer device, organic thin film device, quantum dot thin film device, amorphous silicon solar cell device, microcrystalline silicon solar cell device, and crystalline silicon solar cell device.

10. A method for enhancing the efficiency and stability of solar cells, characterized in that, The method includes: introducing the light-converting adhesive film according to any one of claims 1-7 into a solar cell; Preferably, the solar cell includes one or more of the following devices: PN junction device containing III-V or II-IV group elements, Cu-In-Ga-Se thin film device, organic sensitizer device, organic thin film device, quantum dot thin film device, amorphous silicon solar cell device, microcrystalline silicon solar cell device, and crystalline silicon solar cell device.

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