Ultraviolet light down-conversion photovoltaic gain film based on self-trapping exciton and photovoltaic device

Abstract

The invention belongs to the technical field of new energy, and particularly relates to an ultraviolet light down-conversion photovoltaic gain film based on self-trapping excitons and a photovoltaic device. Compared with the prior art, the diamond-type triethylene diamine copper halide skeleton compound provided by the invention is an organic-inorganic hybrid copper halide compound and has a self-trapping exciton luminescence property, the converted wide spectrum emission is more beneficial to effective absorption and utilization of a crystalline silicon photovoltaic cell, and meanwhile, the diamond-type triethylene diamine copper halide skeleton compound has excellent light stability and damp-heat stability; therefore, the material is especially suitable for being applied to the field of crystalline silicon photovoltaic cell down-conversion gain films, compared with an existing ultraviolet light down-conversion photovoltaic gain film, the problems of organic matter ultraviolet aging, lead-based perovskite toxicity and the like do not exist, and compared with a pure inorganic self-sinking state exciton material, the material has the advantages that the material is simple in structure and low in cost. The organic components in the organic-inorganic hybrid copper halide compound material can effectively solve the problem of compatibility with high-molecular adhesive film processing, and have obvious advantages.

Description

Technical Field

[0001] This invention belongs to the field of new energy technology, and in particular relates to an ultraviolet down-conversion photovoltaic gain thin film and photovoltaic device based on self-trapped excitons. Background Technology

[0002] Ultraviolet down-conversion photovoltaic gain films are a type of technology that converts ultraviolet light into visible light, thereby increasing the power generation efficiency of crystalline silicon photovoltaic modules and reducing performance degradation caused by ultraviolet light, thus extending the life of the modules. They can also effectively improve the water resistance, weather resistance, corrosion resistance, airtightness, and light utilization of photovoltaic modules, and have a wide range of applications.

[0003] Currently, the materials used to achieve ultraviolet down-conversion photovoltaic gain films are organic fluorescent, perovskite, or quantum dot luminescent materials. However, these materials all utilize the light emission mechanism based on narrow-band emission of free excitons, and their emission peak shift is limited by the Stokes shift mechanism, typically resulting in a short shift. For example, ultraviolet down-conversion based on organic fluorescent materials is mostly in the blue light band, while perovskite or quantum dot materials are mostly in the green light band, and their converted emission wavelengths rarely reach >550nm. This results in limited gain effect of the down-converted photons on crystalline silicon cells that easily absorb long-wavelength photons (550nm~1100nm). Furthermore, the aforementioned narrow-band emission materials generally have a narrow half-width at half-maximum (FWHM) of their emission spectra (<100nm), which also limits the gain wavelength range and effect on the broad-band absorption (550nm-1100nm) of crystalline silicon cells. Summary of the Invention

[0004] In view of this, the technical problem to be solved by the present invention is to provide a UV downconversion photovoltaic gain film based on self-trapped excitons and a crystalline silicon photovoltaic cell. The UV downconversion photovoltaic gain film can effectively extend the wavelength range of downconverted photons, thereby obtaining a large range of photon gain effect in the visible light band of 450-750nm.

[0005] This invention provides a UV down-conversion photovoltaic gain thin film based on self-trapped excitons, comprising a diamond-type triethylenediamine copper halide framework compound; the molecular formula of the diamond-type triethylenediamine copper halide framework compound is ACu2X2 or A2Cu4X4; wherein, A is one or more of triethylenediamine, triethylenediamine monoquaternary ammonium salt and triethylenediamine bisquaternary ammonium salt, and X is a halogen.

[0006] Preferably, the diamond-type triethylenediamine copper halide framework compound has a diamond structure; the diamond-type triethylenediamine copper halide framework compound includes an inorganic component Cu4X4 and an organic component A; the inorganic component Cu4X4 forms a tetrahedral copper halide cluster, wherein the halide ion is the four vertices of the tetrahedron, the cuprous ion is the four face centers of the tetrahedron, and the cuprous ion sites of adjacent tetrahedrons are bridged by the organic component A through covalent bonds or coordination bonds; the organic component A is one or more of triethylenediamine, triethylenediamine monoquaternary ammonium salt, and triethylenediamine diquaternary ammonium salt.

[0007] Preferably, the diamond-type triethylenediamine copper halide framework compound is obtained by reacting one or more of triethylenediamine, triethylenediamine monoquaternary ammonium salt and triethylenediamine bisquaternary ammonium salt with a copper halide.

[0008] Preferably, the molar ratio of one or more of the triethylenediamine, triethylenediamine monoquaternary ammonium salt, and triethylenediamine bisquaternary ammonium salt to the copper halide is 1:10 to 10:1.

[0009] Preferably, the diamond-type triethylenediamine copper halide framework compound is prepared according to the following method:

[0010] One or more of triethylenediamine, triethylenediamine monoquaternary ammonium salt and triethylenediamine bisquaternary ammonium salt, copper halide and a first solvent are mixed and subjected to mechanical ball milling and / or ultrasonic treatment to obtain diamond-type triethylenediamine copper halide framework compounds.

[0011] Preferably, the rotational speed of the mechanical ball mill is 100–1000 rpm; the mechanical ball milling time is 0.1–100 h.

[0012] And / or, the frequency of the ultrasonic treatment is 10 to 100 kHz; the power of the ultrasonic treatment is 100 to 500 W; and the duration of the ultrasonic treatment is 0.1 to 100 h.

[0013] Preferably, after mechanical ball milling and / or ultrasonic treatment, recrystallization is performed to obtain a diamond-type triethylenediamine copper halide framework compound;

[0014] The recrystallization process specifically involves adding a second solvent, heating to dissolve, cooling to room temperature, and then allowing it to stand at a low temperature to obtain a diamond-type triethylenediamine copper halide framework compound.

[0015] The heating and melting temperature is 90℃~120℃; the cooling rate is 0.1~10℃ / h; the low temperature condition is 0℃~-20℃.

[0016] Preferably, it further includes a film material; the film material is selected from one or more of EVA, POE, TPO, PVB, and SGP films; the mass of the diamond-type triethylenediamine copper halide framework compound is 0.1% to 10% of the mass of the film material.

[0017] The present invention also provides a photovoltaic device, including the above-mentioned ultraviolet down-conversion photovoltaic gain thin film.

[0018] The present invention also provides a diamond-type triethylenediamine copper halide framework compound, wherein the molecular formula of the diamond-type triethylenediamine copper halide framework compound is ACu2X2 or A2Cu4X4; wherein A is one or more of triethylenediamine, triethylenediamine monoquaternary ammonium salt and triethylenediamine bisquaternary ammonium salt, and X is a halogen.

[0019] This invention provides a self-trapped exciton-based ultraviolet down-conversion photovoltaic gain film, comprising a diamond-type triethylenediamine copper halide framework compound; the molecular formula of the diamond-type triethylenediamine copper halide framework compound is ACu2X2 or A2Cu4X4; wherein A is one or more of triethylenediamine, triethylenediamine monoquaternary ammonium salt, and triethylenediamine bisquaternary ammonium salt, and X is a halogen. Compared with the prior art, the diamond-type triethylenediamine copper halide framework compound provided by this invention is an organic-inorganic hybrid copper halide compound with self-trapped exciton luminescence properties, exhibiting a down-conversion gain efficiency approaching 100% in the visible light band, and its broadband emission is more conducive to the effective absorption and utilization of crystalline silicon photovoltaic cells. It also possesses excellent photostability (no significant attenuation after more than 10,000 hours of continuous AM1.5G illumination) and hydrothermal stability (no significant attenuation after more than 10,000 hours at 85°C and 85% relative humidity), thus making it particularly suitable for… Its application in the field of down-conversion gain thin films for crystalline silicon photovoltaic cells fills the gap in the long-wavelength range (>550nm) and wide-spectrum emission (half-width at half maximum >150nm) of ultraviolet down-conversion photovoltaic gain thin films. Compared with current ultraviolet down-conversion photovoltaic gain thin films, it does not have problems such as ultraviolet aging of organic matter and toxicity of lead-based perovskite. At the same time, compared with pure inorganic self-trapped exciton materials, the organic components in the organic-inorganic hybrid copper halide compound material used in this invention can effectively solve the compatibility problem with polymer film processing, which has obvious advantages. Attached Figure Description

[0020] Figure 1 The diamond prototype structure diagram provided for this invention;

[0021] Figure 2 The cell structure diagram of the diamond-type triethylenediamine copper halide framework compound provided by the present invention;

[0022] Figure 3The packing diagram of the diamond-type triethylenediamine copper halide framework compound provided by the present invention along the crystal extension axes a, b and c.

[0023] Figure 4 This is a schematic diagram of the (TEDA)2Cu4I4, (TEDA)2Cu4Br4 and (TEDA)2Cu4Cl4 powder materials prepared in Example 1 of the present invention under natural light and ultraviolet light irradiation;

[0024] Figure 5 Thermogravimetric curve of (TEDA)₂Cu₄I₄ prepared in Example 1 of this invention;

[0025] Figure 6 Thermogravimetric curve of (TEDA)₂Cu₄Br₄ prepared in Example 1 of this invention;

[0026] Figure 7 Thermogravimetric curve of (TEDA)₂Cu₄Cl₄ prepared in Example 1 of this invention;

[0027] Figure 8 This is a schematic diagram of the (TEDA)2Cu4I4, (TEDA)2Cu4Br4 and (TEDA)2Cu4Cl4 powder materials prepared in Example 2 of the present invention under natural light and ultraviolet light irradiation;

[0028] Figure 9 The X-ray diffraction (PXRD) patterns of the (TEDA)2Cu4I4, (TEDA)2Cu4Br4 and (TEDA)2Cu4Cl4 powder materials prepared in Example 2 of the present invention are shown.

[0029] Figure 10 This is a graph showing the crystallographic data of (TEDA)2Cu4I4 crystal prepared in Example 3 of the present invention;

[0030] Figure 11 This is a crystal structure diagram of the (TEDA)2Cu4I4 crystal prepared in Example 3 of the present invention;

[0031] Figure 12 The steady-state excitation and steady-state emission spectra of the (TEDA)2Cu4I4 and (TEDA)2Cu4Br4 materials prepared in Example 3 of the present invention are shown.

[0032] Figure 13 The absolute quantum efficiency diagram of the (TEDA)2Cu4I4 crystal prepared in Example 3 of this invention under 340 nm excitation was measured by an integrating sphere.

[0033] Figure 14The absolute quantum efficiency diagram of the (TEDA)2Cu4Br4 crystal prepared in Example 3 of this invention under 340 nm excitation was measured by an integrating sphere.

[0034] Figure 15 This is a schematic diagram of the (TEDA)2Cu4I4 crystal prepared in Example 3 of the present invention under natural light and irradiation with a 365nm ultraviolet lamp, observed under an optical microscope.

[0035] Figure 16 This is a schematic diagram of the product of ball milling in Comparative Example 1 of the present invention, in which diethylenediamine was substituted for triethylenediamine, under natural light and irradiated by a 365nm ultraviolet lamp.

[0036] Figure 17 The absolute quantum efficiency of the product obtained in Comparative Example 2 of this invention, measured by an integrating sphere, under 350 nm excitation.

[0037] Figure 18 The absolute quantum efficiency of the product obtained in Comparative Example 3 of this invention, measured by an integrating sphere, is plotted under 350 nm excitation.

[0038] Figure 19 The spectral color temperature diagrams of the (TEDA)2Cu4I4 and (TEDA)2Cu4Br4 warm white LED devices in Experimental Example 1 of this invention are shown.

[0039] Figure 20 These are scanning electron microscope (SEM) images of the ultraviolet down-conversion photovoltaic gain film before and after the addition of organic component (TEDA) in Experimental Example 2 of this invention.

[0040] Figure 21 This is a JV curve of the crystalline silicon photovoltaic cell in Experiment Example 2 of the present invention before and after using (TEDA)2Cu4I4 material for gain.

[0041] Figure 22 The graph shows the long-term stability test data of the crystalline silicon photovoltaic cell in Experiment Example 2 of this invention after using (TEDA)2Cu4I4 material for gain. Detailed Implementation

[0042] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0043] This invention provides a diamond-type triethylenediamine copper halide framework compound, wherein the molecular formula of the diamond-type triethylenediamine copper halide framework compound is ACu2X2 or A2Cu4X4; wherein A is one or more of triethylenediamine, triethylenediamine monoquaternary ammonium salt and triethylenediamine bisquaternary ammonium salt, and X is a halogen.

[0044] In a specific embodiment of the present invention, the diamond-type triethylenediamine copper halide framework compound has a diamond structure; the diamond-type triethylenediamine copper halide framework compound includes an inorganic component Cu4X4 and an organic component A; the inorganic component Cu4X4 constitutes a tetrahedral copper halide cluster, wherein the halide ion is the four vertices of the tetrahedron, the cuprous ion is the four face centers of the tetrahedron, and the cuprous ion sites of adjacent tetrahedrons are bridged by the organic component A through covalent bonds or coordination bonds; that is, the structure of the diamond-type triethylenediamine copper halide framework compound is like the prototype structure of diamond-type carbon, wherein the carbon atom positions in the prototype structure are replaced by the copper halide cluster Cu4X4, and the carbon-carbon bond positions in the prototype structure are replaced by the organic component A, ultimately forming an ACu2X2 or A2Cu4X4 diamond-type structure; Figures 1-3 , Figure 1 This is a diagram of the prototype structure of diamond. Figure 2 This is a cell structure diagram of a diamond-type triethylenediamine copper halide framework compound. Figure 3 This is a packing diagram of a diamond-type triethylenediamine copper halide framework compound along the crystal axes a, b, and c; the organic component A is one or more of triethylenediamine, triethylenediamine monoquaternary ammonium salt, and triethylenediamine bisquaternary ammonium salt.

[0045] In one specific embodiment of the present invention, the molecular formula of the diamond-type triethylenediamine copper halide framework compound is C6H. 12 N2Cu2X2 or (C6H) 12 N2)2Cu4X4, which can be abbreviated as (TEDA)2Cu4X4.

[0046] In one specific embodiment of the present invention, X is one or more of I, Br, Cl, and F. The diamond-type triethylenediamine copper halide framework compounds provided by the present invention all have similar structures when X is a different halogen atom, the only difference being the presence of a differentiating group at the halogen site.

[0047] In one specific embodiment of the present invention, X is I.

[0048] In one specific embodiment of the present invention, A is triethylenediamine.

[0049] In one specific embodiment of the present invention, the diamond-type triethylenediamine copper halide framework compound is a powder or a single crystal.

[0050] In a specific embodiment provided by the present invention, the diamond-type triethylenediamine copper halide framework compound has Figure 9 The X-ray diffraction pattern mentioned above.

[0051] In one specific embodiment of the present invention, the diamond-type triethylenediamine copper halide framework compound is C6H. 12 N₂Cu₂I₂ crystalline compound; the C₆H 12 The space group of the N2Cu2I2 crystalline compound is P4 / mcc; the C6H 12 The unit cell parameters of the N2Cu2I2 crystalline compound are: bond lengths a = 18.2022, b = 18.20200, c = 16.13100; bond angles α = 90°, β = 90°, γ = 90°; Z = 16, V = 5344.407.

[0052] In a specific embodiment of the present invention, the diamond-type triethylenediamine copper halide framework compound is obtained by reacting one or more of triethylenediamine, triethylenediamine monoquaternary ammonium salt, and triethylenediamine bisquaternary ammonium salt with a copper halide; the molar ratio of one or more of the triethylenediamine, triethylenediamine monoquaternary ammonium salt, and triethylenediamine bisquaternary ammonium salt with the copper halide is preferably 1:10 to 10:1, more preferably 1:10 to 8:1, even more preferably 1:10 to 5:1, even more preferably 1:8 to 5:1, even more preferably 1:8 to 3:1, even more preferably 1:8 to 2:1, even more preferably 1:5 to 2:1, even more preferably 1:5 to 1:1, even more preferably 1:4 to 1:1, even more preferably 1:3 to 1:2, and most preferably 1:2; the copper halide can be any copper halide well known to those skilled in the art, and there are no special limitations. In the present invention, cuprous halide is preferred, more preferably cuprous chloride, cuprous bromide, and cuprous iodide, and even more preferably cuprous iodide.

[0053] In a specific embodiment of the present invention, the diamond-type triethylenediamine copper halide framework compound is prepared by the following method: one or more of triethylenediamine, triethylenediamine monoquaternary ammonium salt, and triethylenediamine diquaternary ammonium salt, a copper halide, and a first solvent are mixed, and the mixture is subjected to mechanical ball milling and / or ultrasonic treatment to obtain the diamond-type triethylenediamine copper halide framework compound. The first solvent can be any solvent well-known to those skilled in the art and is not particularly limited. In this invention, it is preferably one or more of nitrile solvents, alcohol solvents, ester solvents, benzene solvents, and water solvents, more preferably nitrile solvents, and even more preferably acetonitrile. The amount of the first solvent can be selected according to different subsequent operations. When the subsequent operation is mechanical ball milling… The preferred ratio of one or more of the triethylenediamine, triethylenediamine monoquaternary ammonium salt, and triethylenediamine bisquaternary ammonium salt to the first solvent is 1 mmol:(0.1-10) mL, more preferably 1 mmol:(0.1-5) mL, even more preferably 1 mmol:(0.1-2) mL, even more preferably 1 mmol:(0.1-1) mL, even more preferably 1 mmol:(0.1-0.5) mL, and most preferably 1 mmol:0.2 mL; when the subsequent operation is ultrasonic treatment, the preferred ratio of one or more of the triethylenediamine, triethylenediamine monoquaternary ammonium salt, and triethylenediamine bisquaternary ammonium salt to the first solvent is 1 mmol:(0.1-10) mL, more preferably 1 mmol:(0.1-10) mL. The preferred concentrations are: mol: (0.5–8) mL, more preferably 1 mmol: (0.5–5) mL, more preferably 1 mmol: (0.5–3) mL, more preferably 1 mmol: (1–2) mL, and most preferably 1 mmol: 1 mL; the preferred rotational speed of the mechanical ball mill is 100–1000 rpm, more preferably 300–1000 rpm, more preferably 500–1000 rpm, more preferably 700–900 rpm, and most preferably 800 rpm; the preferred time of the mechanical ball mill is 0.1–100 h, more preferably 1–50 h, more preferably 3–30 h, more preferably 5–20 h, more preferably 5–15 h, and most preferably 6–10 h. The preferred time for ultrasonic treatment is 8 hours; the diameter of the grinding balls used in the mechanical ball mill is preferably 1-10 mm; the preferred ball-to-material ratio for the mechanical ball mill is 1:(5-20), more preferably 1:(8-15), even more preferably 1:(8-12), and most preferably 1:10; the preferred frequency for ultrasonic treatment is 10-100 kHz, more preferably 20-80 kHz, even more preferably 20-60 kHz, even more preferably 30-50 kHz, and most preferably 40 kHz; the preferred power for ultrasonic treatment is 100-500 W, more preferably 100-400 W, even more preferably 100-300 W, even more preferably 150-250 W, and most preferably 200 W; the preferred time for ultrasonic treatment is 0.The time frame is 1–100 h, more preferably 1–50 h, even more preferably 3–30 h, even more preferably 5–20 h, even more preferably 5–15 h, even more preferably 6–10 h, and most preferably 8 h; preferably, after mechanical ball milling and / or ultrasonic treatment, post-treatment is also performed; if mechanical ball milling is used, the post-treatment preferably involves centrifugation, filtration, washing, and drying after ball milling to obtain a diamond-type triethylenediamine copper halide framework compound, or specifically, after ball milling, adding a first solvent, dispersing the product in the solvent by ultrasound, filtering, washing, and drying to obtain a diamond-type triethylenediamine copper halide framework compound; if ultrasonic treatment is used, the post-treatment preferably involves filtering, washing, and drying after ultrasonic treatment to obtain a diamond-type triethylenediamine copper halide framework compound; the solvent used for washing can be the same as or different from the solvent used for the reaction, and there are no special restrictions, preferably one or more of nitrile solvents, alcohol solvents, ester solvents, benzene solvents, and aqueous solvents, more preferably nitrile solvents, and even more preferably acetonitrile.

[0054] The product obtained by mechanical ball milling and / or ultrasonic treatment is a powder of diamond-type triethylenediamine copper halide framework compound. To obtain its single crystal form, it is preferable to recrystallize after mechanical ball milling and / or ultrasonic treatment to obtain the diamond-type triethylenediamine copper halide framework compound. Specifically, the powder obtained after post-treatment is recrystallized to obtain the diamond-type triethylenediamine copper halide framework compound. The recrystallization specifically involves adding a second solvent, heating to dissolve, cooling to room temperature, and then allowing it to stand at a low temperature to obtain the diamond-type triethylenediamine copper halide framework compound. The second solvent is preferably one or more of nitrile solvents, alcohol solvents, ester solvents, benzene solvents, and water solvents, more preferably nitrile solvents, and even more preferably isobutyronitrile. The amount of the second solvent is such that the concentration of the diamond-type triethylenediamine copper halide framework compound in the recrystallization system is 0.5–1.5 mol / L, more preferably 0.8–1.2 mol / L, and even more preferably... The concentration is 1 mol / L; the heating and dissolving temperature is preferably 90℃~120℃, more preferably the boiling point of the second solvent; the cooling rate is preferably 0.1~10℃ / h, more preferably 1~10℃ / h, even more preferably 2~8℃ / h, even more preferably 4~6℃ / h, and most preferably 5℃ / h; the low temperature condition is preferably 0℃~-20℃, more preferably -5℃~-20℃, even more preferably -10℃~-20℃, even more preferably -15℃~-20℃, and most preferably -20℃; the standing time is preferably 8~20 hours, more preferably 10~15 hours, and even more preferably 12 hours; after recrystallization, it is preferably filtered, washed, and dried to obtain a diamond-type triethylenediamine copper halide framework compound; the solvent used for washing is preferably one or more of nitrile solvents, alcohol solvents, ester solvents, benzene solvents, and water solvents, more preferably nitrile solvents, and even more preferably acetonitrile.

[0055] Diamond-type triethylenediamine copper halide framework compounds offer considerable flexibility in the combination of halogen components. Most importantly, different halide ions significantly influence the photoelectric properties of the materials. For example, low-dimensional structures and strong spatial interactions favor the formation of efficient self-trapped exciton (STE) emission, and STE emission accompanied by large Stokes shifts often produces broad-range and long-wavelength emission bands. Therefore, to achieve efficient broadband and long-wavelength emission in diamond-type triethylenediamine copper halide framework compounds, this invention selects triethylenediamine, an organic molecule with a relatively large size that readily promotes the formation of intermolecular coordination bonds, as the starting material. Simultaneously, the synthesis method is optimized, using acetonitrile as the mother liquor to create a halogen-deficient environment, promoting the bridging of copper halide clusters (Cu4X4) and triethylenediamine molecules (TEDA) through coordination bonds to form a diamond-type three-dimensional structure. Furthermore, research indicates that the emission band can be effectively adjusted by changing the halide anion; therefore, by rationally selecting halogens and improving and optimizing the synthesis method, crystalline materials with different structural characteristics and photophysical properties can be designed and synthesized.

[0056] Therefore, through extensive experimentation, this invention selected triethylenediamine and copper halide to provide the atoms or clusters required for constructing diamond-type triethylenediamine copper halide framework compounds. The inorganic component Cu4X4 forms a tetrahedral copper halide cluster, wherein the halide ion X... - The four vertices of a regular tetrahedron, cuprous ions Cu + These are the four face centers of a regular tetrahedron, and the face centers of adjacent regular tetrahedrons (i.e., Cu) + The sites are bridged by triethylenediamine (TEDA) molecules through covalent or coordination bonds, ultimately forming a diamond-type structure.

[0057] The present invention also provides a UV down-conversion photovoltaic gain thin film based on self-trapped excitons, comprising a diamond-type triethylenediamine copper halide framework compound; the molecular formula of the diamond-type triethylenediamine copper halide framework compound is ACu2X2 or A2Cu4X4; wherein, A is one or more of triethylenediamine, triethylenediamine monoquaternary ammonium salt and triethylenediamine bisquaternary ammonium salt, and X is a halogen.

[0058] The diamond-type triethylenediamine copper halide framework compound is the same as described above, and will not be repeated here.

[0059] In a specific embodiment of the present invention, the ultraviolet down-conversion photovoltaic gain film preferably further includes a film material; the film material is one or more of EVA, POE, TPO, PVB, and SGP film; the mass of the diamond-type triethylenediamine copper halide framework compound is preferably 0.1% to 10% of the mass of the film material, more preferably 0.1% to 5%, even more preferably 0.1% to 2%, even more preferably 0.1% to 1.5%, even more preferably 0.5% to 1.5%, and most preferably 1%; the film-forming material can be any film-forming material well known to those skilled in the art, and there are no special limitations. In the present invention, EVA (polyethylene-polyvinyl acetate copolymer), POE, and TPO are preferred, with EVA being the most preferred; in the embodiments provided by the present invention, Formosa Plastics EVA7760 is specifically used as an example for illustration.

[0060] In one specific embodiment of the present invention, the thickness of the ultraviolet down-conversion photovoltaic gain film is preferably 0.1-5 mm, more preferably 0.1-2 mm, even more preferably 0.1-1 mm, and most preferably 0.5 mm.

[0061] The diamond-type triethylenediamine copper halide framework compound provided by this invention is an organic-inorganic hybrid copper halide compound with self-trapped exciton luminescence properties. It has a down-conversion gain efficiency approaching 100% in the visible light band, and its broadband emission is more conducive to the effective absorption and utilization of crystalline silicon photovoltaic cells. At the same time, it has excellent photostability and thermal stability, so it is particularly suitable for application in the field of down-conversion gain thin films for crystalline silicon photovoltaic cells. It fills the gap in the long-wavelength range (>550nm) and broadband emission (half-width at half maximum >150nm) of ultraviolet down-conversion photovoltaic gain thin films. Compared with the current ultraviolet down-conversion photovoltaic gain thin films, it does not have the problems of organic matter ultraviolet aging and lead-based perovskite toxicity. Moreover, compared with pure inorganic self-trapped exciton materials, the organic components in the organic-inorganic hybrid copper halide compound material used in this invention can effectively solve the compatibility problem with polymer film processing, which has obvious advantages.

[0062] The present invention also provides a photovoltaic device, including the above-mentioned ultraviolet down-conversion photovoltaic gain thin film.

[0063] In one specific embodiment of the present invention, the photovoltaic device is a crystalline silicon photovoltaic cell.

[0064] In one specific embodiment of the present invention, the photovoltaic device includes a solar cell and an ultraviolet down-conversion photovoltaic gain film; the ultraviolet down-conversion photovoltaic gain film is disposed on the surface of the solar cell; more specifically, the ultraviolet down-conversion photovoltaic gain film is disposed between the front panel glass of the solar cell module and the solar cell; the structure of the solar cell module, from the direction of sunlight incidence, includes, in sequence, the front panel glass, the aforementioned ultraviolet down-conversion photovoltaic gain film, the solar cell, a commercially available photovoltaic backing film, and the rear panel glass; the solar cell is preferably a crystalline silicon photovoltaic cell.

[0065] To further illustrate the present invention, the following describes in detail, with reference to embodiments, a self-trapped exciton-based ultraviolet down-conversion photovoltaic gain thin film and photovoltaic device provided by the present invention.

[0066] All reagents used in the following examples are commercially available.

[0067] Example 1

[0068] 1.1 Mixing: Add 20 mmol of cuprous halide (CuI, CuBr or CuCl), 10 mmol of triethylenediamine and 2 mL of acetonitrile to a 100 mL ball mill jar and mix to obtain a mixture.

[0069] 1.2 Ball milling: Add zirconia balls with a diameter of 5 mm (material-to-ball ratio of 1:10) to the ball milling jar, and ball mill in a planetary ball mill at 800 rpm for 8 hours to obtain a coarse powder product.

[0070] 1.3 Sieving out the milling beads: Add 50 mL of acetonitrile to the above-mentioned crude powder product, and disperse the crude product into the solvent by ultrasonic oscillation on the surface of the milling jar. Separate the milling beads through a sieve to obtain a product suspension.

[0071] 1.4 Filtration and Drying: The above product suspension was filtered through a vacuum funnel, washed with acetonitrile, and finally dried in an oven to obtain high-purity (TEDA)2Cu4I4, (TEDA)2Cu4Br4, or (TEDA)2Cu4Cl4 powder materials.

[0072] The (TEDA)2Cu4I4, (TEDA)2Cu4Br4, and (TEDA)2Cu4Cl4 powder materials prepared in Example 1 were subjected to natural light and 365nm ultraviolet light irradiation, respectively, and the images are shown below. Figure 4 As shown. By Figure 4It can be seen that the (TEDA)2Cu4I4 material prepared in Example 1 is a white powder under natural light, the (TEDA)2Cu4Br4 material is a gray powder under natural light, and the (TEDA)2Cu4Cl4 material is a yellow powder under natural light. The (TEDA)2Cu4I4 material prepared in Example 1 emits yellow light under 365nm ultraviolet light, the (TEDA)2Cu4Br4 material emits orange light under 365nm ultraviolet light, and the (TEDA)2Cu4Cl4 material does not emit obvious light under 365nm ultraviolet light.

[0073] The thermal stability of (TEDA)₂Cu₄I₄, (TEDA)₂Cu₄Br₄, and (TEDA)₂Cu₄Cl₄ powder materials was characterized by thermogravimetric analysis (TGA), and their thermogravimetric curves are shown in the figure below. Figures 5-7 As shown, where Figure 5 Thermogravimetric curve of (TEDA)₂Cu₄I₄. Figure 6 Thermogravimetric curve of (TEDA)₂Cu₄Br₄. Figure 7 Thermogravimetric curve of (TEDA)₂Cu₄Cl₄. (From...) Figures 5-7 It can be seen that the first thermal weight loss ratio is approximately 22%–36%, corresponding to the decomposition weight loss of triethylenediamine, and the second thermal weight loss ratio is approximately 78%–64%, corresponding to the decomposition weight loss of cuprous halide. This proves that the target product is composed of triethylenediamine (C6H... 12 It is composed of N2)2 and cuprous halide Cu4X4 clusters, and its weight loss ratio is consistent with the component mass ratio.

[0074] Example 2

[0075] 2.1 Mixing: Add 20 mmol of cuprous halide (CuI, CuBr or CuCl), 10 mmol of triethylenediamine and 20 mL of acetonitrile to a 100 mL conical flask to obtain a mixture.

[0076] 2.2 Ultrasonic oscillation: The conical flask was placed in an ultrasonic oscillator and ultrasonically oscillated for 8 hours at an ultrasonic frequency of 40 kHz and an ultrasonic power of 200 W to obtain a product suspension.

[0077] 2.3 Filtration and Drying: The above product suspension was filtered through a vacuum funnel, washed with acetonitrile, and finally dried in an oven to obtain high-purity (TEDA)2Cu4I4, (TEDA)2Cu4Br4, or (TEDA)2Cu4Cl4 powder materials.

[0078] The (TEDA)2Cu4I4, (TEDA)2Cu4Br4, and (TEDA)2Cu4Cl4 powder materials prepared in Example 2 were placed under natural light and a 365nm ultraviolet lamp, respectively, and the images are shown below. Figure 8 As shown. By Figure 8 It can be seen that the (TEDA)2Cu4I4 material prepared in Example 2 is a white powder under natural light, the (TEDA)2Cu4Br4 material is a gray powder under natural light, and the (TEDA)2Cu4Cl4 material is a yellow powder under natural light. The (TEDA)2Cu4I4 material prepared in Example 2 emits yellow light under 365nm ultraviolet light, the (TEDA)2Cu4Br4 material emits orange light under 365nm ultraviolet light, and the (TEDA)2Cu4Cl4 material does not emit obvious light under 365nm ultraviolet light.

[0079] The phase composition of the (TEDA)₂Cu₄I₄, (TEDA)₂Cu₄Br₄, and (TEDA)₂Cu₄Cl₄ powder materials obtained in Example 2 was characterized by powder X-ray diffraction (PXRD), and their PXRD patterns are shown below. Figure 9 As shown. By Figure 9 As can be seen, the structure is highly similar to that simulated by the XRD standard card, proving that the pure phase target product has been synthesized.

[0080] Example 3

[0081] 3.1 Heating and dissolving: The (TEDA)2Cu4X4 powder obtained in Example 1 and Example 2 was dispersed in 20 mL of isobutyronitrile at a concentration of 1 mol / L, and heated to the boiling point and refluxed until all the powder was completely dissolved.

[0082] 3.2 Cooling Crystallization: The above clear and transparent solution was cooled from high temperature to room temperature at a cooling rate of 5℃ / h, and then placed in a -20℃ refrigerator for 12 hours to obtain (TEDA)2Cu4X4 crystals with a crystal size of approximately 3mm. The target product was filtered and washed with acetonitrile, and finally dried in an oven to obtain high-purity (TEDA)2Cu4X4 crystals.

[0083] The high-purity (TEDA)₂Cu₄X₄ crystal obtained in Example 3 was analyzed by powder X-ray diffraction (PXRD), and its X-ray diffraction pattern was obtained. Figure 9 similar.

[0084] Crystal structure determination: A single crystal of appropriate size was placed on a Bruker SMART APEX IICCD single crystal diffractometer and monochromated with graphite-modified Mo Kα. Using X-rays as the light source, diffraction data were collected at 273(2) K using a ω / 2θ scan. Data reduction was performed using the SAINT program, and absorption correction was performed using the SADABS program. The structure of the compound was solved directly, and the coordinates of non-hydrogen atoms and the anisotropic temperature factor were refined using the full matrix least squares method. Geometric hydrogenation was performed. Structural analysis was performed using SHELXS-97, and structural refinement was performed using SHELXL-97. Detailed crystallographic data are as follows: Figure 10 As shown, the crystal structure is as follows Figure 11 As shown. Analysis and characterization of diamond-type triethylenediamine copper halide framework compounds: steady-state excitation and emission spectra of (TEDA)₂Cu₄I₄ and (TEDA)₂Cu₄Br₄ materials, as shown. Figure 12 As shown, the left side is the excitation spectrum and the right side is the emission spectrum.

[0085] Depend on Figure 12 In the excitation spectrum, the excitation spectrum of (TEDA)2Cu4I4 is located in the range of 300–410 nm, with the optimal excitation wavelength at 347 nm; the excitation spectrum of (TEDA)2Cu4Br4 is located in the range of 300–430 nm, with the optimal excitation wavelength at 356 nm.

[0086] Depend on Figure 12 In the emission spectrum, the emission spectrum of (TEDA)2Cu4I4 is located at 440–690 nm, with the maximum emission peak at 554 nm; the emission spectrum of (TEDA)2Cu4Br4 is located at 450–700 nm, with the maximum emission peak at 561 nm.

[0087] The absolute quantum efficiency (PLQY) of high-purity (TEDA)₂Cu₄I₄ crystal was tested using an integrating sphere, such as... Figure 13 As shown, the excitation wavelength was 340 nm, and the measured PLOY was 98%.

[0088] The absolute quantum efficiency (PLQY) of high-purity (TEDA)₂Cu₄Br₄ crystal was tested using an integrating sphere, such as... Figure 14 As shown, the excitation wavelength was 340 nm, and the measured PLQY was 93%.

[0089] The observation results of high-purity (TEDA)₂Cu₄I₄ crystals under an optical microscope, under natural light and 365 nm ultraviolet light, are as follows: Figure 15 As shown.

[0090] Example 4

[0091] 4.1 Mixing: Add 20 mmol cuprous iodide, 10 mmol triethylenediamine monoquaternary ammonium salt (commercially available, CAS No. 14968-74-2) and 2 mL acetonitrile to a 100 mL ball mill jar and mix to obtain a mixture.

[0092] 4.2 Ball milling: Add zirconia balls with a diameter of 5 mm (material-to-ball ratio of 1:10) to the ball milling jar, and ball mill in a planetary ball mill at 800 rpm for 8 hours to obtain a coarse powder product.

[0093] 4.3 Sieving out the milling beads: Add 50 mL of acetonitrile to the above-mentioned crude powder product, and disperse the crude product into the solvent by ultrasonic oscillation on the surface of the milling jar. Separate the milling beads through a sieve to obtain a product suspension.

[0094] 4.4 Filtration and Drying: The above product suspension was filtered through a vacuum funnel, washed with acetonitrile, and finally dried in an oven to obtain high-purity triethylenediamine monoquaternary ammonium salt copper iodine framework compound powder material.

[0095] Example 5

[0096] 5.1 Mixing: Add 20 mmol of cuprous iodide, 10 mmol of triethylenediamine bisquaternary ammonium salt (commercially available, CAS No. 14870-72-5) and 2 mL of acetonitrile to a 100 mL ball mill jar and mix to obtain a mixture.

[0097] 5.2 Ball milling: Add zirconia balls with a diameter of 5 mm (material-to-ball ratio of 1:10) to the ball milling jar, and ball mill in a planetary ball mill at 800 rpm for 8 hours to obtain a coarse powder product.

[0098] 5.3 Sieving out the milling beads: Add 50 mL of acetonitrile to the above-mentioned crude powder product, and disperse the crude product into the solvent by ultrasonic oscillation on the surface of the milling jar. Separate the milling beads through a sieve to obtain a product suspension.

[0099] 5.4 Filtration and Drying: The above product suspension was filtered through a vacuum funnel, washed with acetonitrile, and finally dried in an oven to obtain high-purity triethylenediamine bisquaternary ammonium salt copper iodine framework compound powder material.

[0100] Comparative Example 1

[0101] A copper halide was prepared using a method similar to that in Example 1, except that triethylenediamine in Example 1 was replaced with diethylenediamine (also known as piperazine). After mechanical ball milling, a crude product was obtained. The crude product was then dispersed in acetonitrile, filtered, washed, and dried to obtain a brown powder product.

[0102] The product was tested and found to have a color inconsistent with (TEDA)₂Cu₄I₄, and it did not emit light under 365nm ultraviolet light. Figure 16 As shown, this indicates that the synthesized product is not (TEDA)2Cu4I4, and does not meet the research and development objective of this invention to develop a diamond-type triethylenediamine copper halide framework compound material.

[0103] Comparative Example 2

[0104] A copper halide was prepared using a method similar to that in Example 1, except that the triethylenediamine in Example 1 was replaced with methyl-triethylenediamine. After mechanical ball milling, a crude product was obtained. The crude product was then dispersed in acetonitrile, filtered, washed, and dried to obtain a brown powder product.

[0105] The absolute quantum efficiency (PLQY) of the product obtained in Comparative Example 2 was tested using an integrating sphere, such as... Figure 17 As shown.

[0106] Comparative Example 3

[0107] A copper halide was prepared using a method basically the same as in Example 1, except that triethylenediamine in Example 1 was replaced with hexamethylenetetramine (urotropine). After mechanical ball milling, a crude product was obtained. The crude product was dispersed in acetonitrile, filtered, washed, and dried to obtain a brown powder product.

[0108] The absolute quantum efficiency (PLQY) of the product obtained in Comparative Example 3 was tested using an integrating sphere, such as... Figure 18 As shown.

[0109] Table 1 shows a comparison of the luminous efficiencies of the copper halide framework compound materials obtained in Examples 3, 4, 5, Comparative Examples 1, 2, and 3 above.

[0110] Table 1. Luminescence efficiency of copper halide framework materials

[0111]

[0112]

[0113] Experimental Example 1: Application of diamond-type triethylenediamine copper halide framework compounds in warm white LEDs

[0114] The (TEDA)2Cu4I4 and (TEDA)2Cu4Br4 materials prepared in Example 3 were respectively coated with epoxy resin (3M). TM Scotch-Weld TMAn epoxy resin adhesive (added at 1% of the epoxy resin adhesive mass) is cured and encapsulated on a 365nm ultraviolet LED chip with a thickness of approximately 0.5mm to prepare a warm white LED light-emitting device.

[0115] Figure 19 This is a spectrum color temperature diagram of the warm white LED light-emitting device. The spectral color temperatures of (TEDA)2Cu4I4 and (TEDA)2Cu4Br4 are 4036K and 4299K, respectively, which are in the middle part of the warm white light color temperature region (3300K~5300K). This is consistent with the spectral range that crystalline silicon photovoltaic cells can efficiently utilize, proving that diamond-type triethylenediamine copper halide framework compound materials have the potential for application as ultraviolet down-conversion photovoltaic gain thin films with self-trapped excitons.

[0116] Experimental Example 2: Application of diamond-type triethylenediamine copper halide framework compounds in photovoltaic cells

[0117] The (TEDA)2Cu4I4 material prepared in Example 3 was dispersed in a polyethylene-polyvinyl acetate copolymer (Formosa Plastics EVA7760) film. The mass of (TEDA)2Cu4I4 was 1% of the mass of the EVA film material. It was then encapsulated on the surface of a crystalline silicon photovoltaic cell (Sunpower high-efficiency solar cell 125*125mm with a conversion efficiency of ≥22.4%) with a thickness of 0.5mm to prepare a photovoltaic cell with down-conversion gain.

[0118] Figure 20 These are scanning electron microscope (SEM) images of EVA films with and without organic component (TEDA) (containing 1% pure inorganic CuI). The EVA film without organic component contains obvious particulate inorganic impurities, while the compatibility between the copper halide framework compound and EVA is significantly improved after the addition of TEDA. This demonstrates that the organic component TEDA can improve the film quality of self-trapped exciton ultraviolet down-conversion photovoltaic gain films.

[0119] Figure 21 This is a JV curve of a crystalline silicon photovoltaic cell before and after encapsulation with an EVA film containing (TEDA)₂Cu₄I₄. The photoelectric conversion efficiency of the crystalline silicon photovoltaic cell increased from 17.37% to 18.27% after using the gain film containing (TEDA)₂Cu₄I₄. The main reason for this is that the short-circuit current decreased from 39.15 mA / cm². 2 Increased to 41.50 mA / cm 2 This demonstrates that ultraviolet light, which is difficult for crystalline silicon cells to utilize, can be converted into visible light wavelengths that crystalline silicon cells can utilize through the down-conversion function of (TEDA)2Cu4I4, proving that diamond-type triethylenediamine copper halide framework compound materials have a promising application prospect in the field of photovoltaic cells.

[0120] Figure 22 The results are the long-term stability test data of the crystalline silicon photovoltaic cell in Experiment Example 2 after using (TEDA)2Cu4I4 material for gain.

[0121] Current density-voltage (JV) curves were obtained using a solar simulator (Class 3A, XES-40S3, SAN-EI) under AM1.5G standard light conditions equipped with a Keithley 2400 source meter. Light intensity was calibrated to AM1.5G irradiance (100 mW / cm²) using a standard silicon solar cell (QE-B1) calibrated with NIM. 2 The effective aperture area of ​​the device is limited to 0.09 cm² using a shadow mask. 2 .

[0122] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An ultraviolet light down-conversion photovoltaic gain thin film based on self-trapped excitons, characterized in that, The diamond type triethylenediamine copper halide skeleton compound; the molecular formula of the diamond type triethylenediamine copper halide skeleton compound is ACu2X2 or A2Cu4X4; wherein, A is one or more of triethylenediamine, triethylenediamine monoquaternary ammonium salt and triethylenediamine bisquaternary ammonium salt, and X is halogen.

2. The ultraviolet light down-conversion photovoltaic gain film of claim 1, wherein, The diamond type triethylenediamine copper halide skeleton compound has a diamond structure; the diamond type triethylenediamine copper halide skeleton compound comprises an inorganic component Cu4X4 and an organic component A; the inorganic component Cu4X4 forms a tetrahedral copper halide cluster, wherein the halide ions are the four apices of the tetrahedron, and the cuprous ions are the four face center points of the tetrahedron, and the cuprous ion sites of adjacent tetrahedrons are bridged by the organic component A through covalent bonds or coordination bonds; the organic component A is one or more of triethylenediamine, triethylenediamine monoquaternary ammonium salt and triethylenediamine bisquaternary ammonium salt.

3. The UV down-conversion photovoltaic gain film of claim 1, wherein, The diamond type triethylenediamine copper halide skeleton compound is obtained by reacting one or more of triethylenediamine, triethylenediamine monoquaternary ammonium salt and triethylenediamine bisquaternary ammonium salt with copper halide.

4. The ultraviolet light down-conversion photovoltaic gain film of claim 1, wherein, The molar ratio of one or more of triethylenediamine, triethylenediamine monoquaternary ammonium salt and triethylenediamine bisquaternary ammonium salt to copper halide is 1:10-10:

1.

5. The ultraviolet light down-conversion photovoltaic gain film of claim 1, wherein, The diamond type triethylenediamine copper halide skeleton compound is prepared by the following method: One or more of triethylenediamine, triethylenediamine monoquaternary ammonium salt and triethylenediamine bisquaternary ammonium salt, copper halide and a first solvent are mixed, and a diamond type triethylenediamine copper halide skeleton compound is obtained by mechanical ball milling and / or ultrasonic treatment.

6. The UV down-conversion photovoltaic gain film of claim 5, wherein, The rotation speed of the mechanical ball milling is 100-1000 revolutions per minute; the mechanical ball milling time is 0.1-100 hours; And / or, the ultrasonic treatment frequency is 10-100 kHz; the ultrasonic treatment power is 100-500 W; and the ultrasonic treatment time is 0.1-100 hours.

7. The UV down-conversion photovoltaic gain film of claim 5, wherein, After the mechanical ball milling and / or ultrasonic treatment, recrystallization is further performed to obtain the diamond type triethylenediamine copper halide skeleton compound; The recrystallization specifically comprises: heating and dissolving after adding a second solvent, then cooling to room temperature, and then standing under low temperature conditions to obtain the diamond type triethylenediamine copper halide skeleton compound; The heating and dissolving temperature is 90-120°C; the cooling rate is 0.1-10°C / h; and the low temperature condition temperature is 0- -20°C.

8. The UV down-conversion photovoltaic gain film of claim 1, wherein, It also comprises a film material; the film material is selected from one or more of EVA, POE, TPO, PVB and SGP film; and the mass of the diamond type triethylenediamine copper halide skeleton compound is 0.1-10% of the mass of the film material.

9. A photovoltaic device, characterized by The diamond type triethylenediamine copper halide skeleton compound has a molecular formula of ACu2X2 or A2Cu4X4; wherein, A is one or more of triethylenediamine, triethylenediamine monoquaternary ammonium salt and triethylenediamine bisquaternary ammonium salt, and X is halogen.

10. A diamondoid trivinyldiamine copper halide framework compound characterized by, The diamond type triethylenediamine copper halide skeleton compound has a molecular formula of ACu2X2 or A2Cu4X4; wherein, A is one or more of triethylenediamine, triethylenediamine monoquaternary ammonium salt and triethylenediamine bisquaternary ammonium salt, and X is halogen.

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