Perovskite photovoltaic cell high-transmittance low-scattering coating material and preparation method thereof

Abstract

The invention relates to a perovskite photovoltaic cell high-transmittance low-scattering coating material and a preparation method thereof, and belongs to the technical field of photovoltaic cells. The coating material is prepared from the following components in percentage by weight: 7.2 to 8.5 percent of PMMA (Polymethyl Methacrylate) resin, 0.17 to 0.22 percent of modified nano titanium dioxide, 0.09 to 0.11 percent of flatting agent, 0.03 to 0.04 percent of defoaming agent and the balance of solvent, the modified nano titanium dioxide is prepared into an intermediate through addition reaction of triallylamine and mercaptoethanol, and then a modifier with a network molecular structure is formed through substitution reaction of trifluoropropyl trichlorosilane and hydroxyl at the end part of an intermediate molecule; a thioether chain segment in a modifier molecule and similar nitrogen and oxygen elements form a strong chelation effect to coat the nano titanium dioxide; the introduction of the modified nano titanium dioxide makes up the problem of light transmission reduction caused by traditional titanium dioxide reinforcement.

Description

Technical Field

[0001] The present invention belongs to the technical field of photovoltaic cells, and specifically relates to a high-transparency and low-scattering coating material for perovskite photovoltaic cells and a preparation method thereof. Background Art

[0002] Perovskite materials are highly sensitive to environmental factors such as water oxygen, light, and temperature, and are prone to decomposition or lattice distortion, resulting in efficiency decay. Surface optical management of perovskite photovoltaic cells is one of the key technologies to improve the photoelectric conversion efficiency; among them, PMMA (polymethyl methacrylate) has high light transmittance and can be uniformly formed into a film by spin coating, spraying, etc. The forming process of the coating material is simple and is widely used in coating materials.

[0003] However, PMMA has insufficient mechanical strength and is easily worn and scratched by external actions in the coating, thus affecting the light transmittance of the coating, and PMMA has insufficient ultraviolet resistance, affecting the life of the coating; in the prior art, nano-scale titanium dioxide is used for blending modification to strengthen the coating, and at the same time has a certain absorption and shielding effect on ultraviolet rays, slowing down the aging of the coating and reducing the damage of ultraviolet rays to perovskite materials; however, the high surface energy of nano-titanium dioxide easily leads to agglomeration, causing light scattering loss. At the same time, the refractive index mutation between titanium dioxide (refractive index about 2.5) and PMMA (refractive index about 1.49) will cause interfacial Fresnel reflection, reducing the light transmittance. Summary of the Invention

[0004] In order to solve the technical problems mentioned in the background art, the purpose of the present invention is to provide a high-transparency and low-scattering coating material for perovskite photovoltaic cells and a preparation method thereof.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] A high-transparency and low-scattering coating material for perovskite photovoltaic cells, the components of which are: 7.2-8.5 wt% of PMMA resin, 0.17-0.22 wt% of modified nano-titanium dioxide, 0.09-0.11 wt% of leveling agent, and 0.03-0.04 wt% of defoaming agent, and the balance is solvent.

[0007] The modified nano-titanium dioxide is prepared by the following method:

[0008] Step A1: Premix triallylamine, photoinitiator and tetrahydrofuran, heat up to 40-50 °C, apply 500-650 mW / cm 2 UV irradiation, slowly add mercaptoethanol and stir for reaction for 5.5-7 h. After the reaction is completed, rotary evaporation is used to remove tetrahydrofuran to obtain an intermediate;

[0009] Further, the feeding ratio of triallylamine, mercaptoethanol, photoinitiator, and tetrahydrofuran is 10 mmol: 32 - 35 mmol: 5 - 8 mg: 15 - 20 mL. Under the action of photoinitiation, mercaptoethanol and triallylamine undergo an addition reaction to form a hydroxyl-terminated structure containing a thioether.

[0010] Step A2: Premix the intermediate, triethylamine, and anhydrous acetone, introduce dry nitrogen for protection, control the temperature at 5 - 15 °C in an ice-water bath, slowly add trifluoropropyltrichlorosilane and stir for reaction for 3 - 4 h, then raise the temperature for reflux reaction for 1.2 - 1.6 h. After the reaction, rotate and evaporate to remove acetone to obtain the modifier.

[0011] Further, the feeding ratio of the intermediate, trifluoropropyltrichlorosilane, triethylamine, and anhydrous acetone is 10 mmol: 10 mmol: 4 - 6 mL: 30 - 40 mL. Triethylamine is an acid-binding agent to promote the active chlorosilane substitution reaction between the introduced hydroxyl group on the intermediate molecule and trifluoropropyltrichlorosilane, forming a network compound.

[0012] Step A3: Premix the modifier, fatty alcohol polyoxyethylene ether, and dimethyl sulfoxide, heat to 60 - 80 °C, add nano-titanium dioxide and disperse it by ultrasonic wave, stop heating and stir for 24 h, centrifuge to obtain the separated liquid phase, wash and dry the substrate with ethanol to obtain modified nano-titanium dioxide.

[0013] Further, the feeding ratio of nano-titanium dioxide, modifier, fatty alcohol polyoxyethylene ether, and dimethyl sulfoxide is 50 g: 6.5 - 8.5 g: 10 - 15 mL: 120 - 150 mL. Fatty alcohol polyoxyethylene ether is a surfactant to promote the dispersion of nano-titanium dioxide particles. The thioether structure in the modifier forms a strong chelation with the adjacent nitrogen-oxygen structure, and the nano-titanium dioxide particles are coated by chelation loading.

[0014] Further, the nano-titanium dioxide is rutile-type titanium dioxide with an average particle size not higher than 100 nm, having high refractive index and low scattering effects, and having a good absorption effect on harmful ultraviolet light.

[0015] Further, both the leveling agent and the defoaming agent are silicone-based auxiliaries, having a low impact on the optical properties of the coating.

[0016] Further, the solvent is composed of a mixture of tetrahydrofuran, ethyl acetate, and anisole.

[0017] A preparation method of a high-transparency and low-scattering coating material for perovskite photovoltaic cells is as follows: Stir and dissolve PMMA resin and the solvent, then add a leveling agent and a defoaming agent and mix them. While stirring, add modified nano-titanium dioxide and mix evenly, and then perform vacuum defoaming to obtain the coating material.

[0018] The beneficial effects of the present invention:

[0019] The coating material of the present invention uses PMMA as the film-forming material, adds a modified nano-titanium dioxide to strengthen the coating, and at the same time maintains good optical properties of the coating; the modified nano-titanium dioxide is prepared by an addition reaction of triallylamine and mercaptoethanol to form an intermediate, and then a substitution reaction of trifluoropropyltrichlorosilane with the hydroxyl group at the end of the intermediate molecule to form a modifier with a network molecular structure. The sulfur ether segment in the modifier molecule forms a strong chelation with adjacent nitrogen and oxygen elements to coat the nano-titanium dioxide; compared with the traditional coupling treatment of nano-titanium dioxide, the chelation has less requirements for the surface groups and structure of titanium dioxide. In addition, the network structure of the modifier is more conducive to the uniform coating of nano-titanium dioxide, making the coating layer more uniform and flat, and more likely to be dispersed in the PMMA matrix in terms of structure. At the same time, it reduces interlayer scattering. The fluorine groups on the network structure form a dipole interaction with the ester groups in the PMMA molecular chain, promoting dispersion in terms of chemical composition, improving interfacial compatibility, and reducing light scattering at the interface. In addition, titanium dioxide has a high refractive index, and the uniformly coated fluorine layer effectively reduces the refractive index of the near-surface layer of titanium dioxide, forming a refractive index gradient between the PMMA-modifier layer-titanium dioxide matrix, reducing interlayer scattering, and compensating for the problem of decreased light transmittance caused by the introduction of titanium dioxide. Specific Embodiments

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts shall fall within the protection scope of the present invention.

[0021] Example 1, preparation of a high-transparency and low-scattering coating material for perovskite photovoltaic cells, and the specific implementation process is as follows:

[0022] (1) Preparation of modified nano-titanium dioxide

[0023] Step A1: Premix triallylamine, photoinitiator and tetrahydrofuran, heat up to 40 °C, apply ultraviolet irradiation of 500 mW / cm 2 and slowly add mercaptoethanol and stir for reaction for 7 h. Among them, the feeding ratio of triallylamine, mercaptoethanol, photoinitiator and tetrahydrofuran is 10 mmol: 32 mmol: 5 mg: 15 mL. After the reaction, rotary evaporation is used to remove tetrahydrofuran to obtain an intermediate.

[0024] Step A2: Premix the intermediate, triethylamine, and anhydrous acetone, introduce dry nitrogen for protection, control the temperature at 5 °C in an ice-water bath, slowly add trifluoropropyltrichlorosilane, and stir for reaction for 4 h. Then, raise the temperature to reflux for reaction for 1.6 h. Among them, the feeding ratio of the intermediate, trifluoropropyltrichlorosilane, triethylamine, and anhydrous acetone is 10 mmol: 10 mmol: 4 mL: 30 mL. After the reaction, rotate and evaporate to remove acetone to obtain the modifier.

[0025] Step A3: Premix the modifier, fatty alcohol polyoxyethylene ether, and dimethyl sulfoxide, raise the temperature to 60 °C, add nano-titanium dioxide and ultrasonically disperse it, stop heating and stir for 24 h. Among them, the feeding ratio of nano-titanium dioxide, modifier, fatty alcohol polyoxyethylene ether, and dimethyl sulfoxide is 50 g: 6.5 g: 10 mL: 120 mL. The nano-titanium dioxide is selected from rutile micropowder DK405-1, and the average particle size is about 30 nm. Centrifuge to obtain the separated liquid phase, wash and dry the substrate with ethanol to obtain modified nano-titanium dioxide.

[0026] (2) Preparation of the coating material

[0027] Ingredients: Take 7.2 wt% of PMMA resin, and select LA2114 type resin raw material; 0.17 wt% of modified nano-titanium dioxide, prepared by this example; 0.09 wt% of leveling agent, select BYK-346 type silicone leveling agent; 0.04 wt% of defoaming agent, select BYK-088 type silicone defoaming agent; the balance is solvent, which is compounded from tetrahydrofuran, ethyl acetate, and anisole according to the weight ratio of 1:0.4:0.15.

[0028] Miscibility: Stir and dissolve the PMMA resin and the solvent, then add the leveling agent and the defoaming agent and mix. Add the modified nano-titanium dioxide and mix well under stirring, and perform vacuum degassing to obtain the coating material.

[0029] Example 2, preparing a high-transparency and low-scattering coating material for perovskite photovoltaic cells, the specific implementation process is as follows:

[0030] (1) Preparation of modified nano-titanium dioxide

[0031] Step A1: Premix triallylamine, photoinitiator, and tetrahydrofuran, raise the temperature to 50 °C, apply ultraviolet irradiation of 650 mW / cm 2 Slowly add mercaptoethanol and stir for reaction for 5.5 h. Among them, the feeding ratio of triallylamine, mercaptoethanol, photoinitiator, and tetrahydrofuran is 10 mmol: 35 mmol: 8 mg: 20 mL. After the reaction, rotate and evaporate to remove tetrahydrofuran to obtain the intermediate.

[0032] Step A2: premix the intermediate, triethylamine and anhydrous acetone, introduce dry nitrogen for protection, control the temperature at 15°C in an ice-water bath, slowly add trifluoropropyltrichlorosilane and stir to react for 3 hours, then heat and reflux to react for 1.2 hours, wherein the feed ratio of the intermediate, trifluoropropyltrichlorosilane, triethylamine and anhydrous acetone is 10mmol:10mmol:6mL:40mL. After the reaction, remove acetone by rotary evaporation to obtain a modifier.

[0033] Step A3: pre-mix the modifier, fatty alcohol polyoxyethylene ether and dimethyl sulfoxide, heat to 80°C, add nano titanium dioxide for ultrasonic dispersion, stop heating and stirring for 24 hours, wherein the feed ratio of nano titanium dioxide, modifier, fatty alcohol polyoxyethylene ether and dimethyl sulfoxide is 50g:8.5g:15mL:150mL, the nano titanium dioxide is selected from DK405-2 rutile micropowder, and the average particle size is about 60nm, centrifuge to separate the liquid phase, wash the substrate with ethanol and dry it to obtain modified nano titanium dioxide.

[0034] (2) Preparation of coating materials

[0035] Ingredients: 8.5wt% PMMA resin, LA2114 resin raw material; 0.22wt% modified nano titanium dioxide, homemade in this embodiment; 0.11wt% leveling agent, BYK-346 organosilicon leveling agent; 0.03wt% defoamer, BYK-088 organosilicon defoamer; the remainder is solvent, which is compounded by tetrahydrofuran, ethyl acetate and anisole in a weight ratio of 1:0.3:0.2.

[0036] Miscibility: Stir and dissolve the PMMA resin and the solvent, then add the leveling agent and the defoamer and mix them, add the modified nano titanium dioxide in a stirring state and mix well, perform vacuum degassing, and obtain the coating material.

[0037] Example 3, preparation of high-transmittance and low-scattering coating materials for perovskite photovoltaic cells, the specific implementation process is as follows:

[0038] (1) Preparation of modified nano-titanium dioxide

[0039] Step A1: premix triallylamine, photoinitiator and tetrahydrofuran, heat to 45°C, and apply 550 mW / cm 2 After ultraviolet irradiation, mercaptoethanol was slowly added and stirred for reaction for 6.5 hours, wherein the feed ratio of triallylamine, mercaptoethanol, photoinitiator and tetrahydrofuran was 10 mmol: 33 mmol: 7 mg: 18 mL. After the reaction was completed, tetrahydrofuran was removed by rotary evaporation to obtain an intermediate.

[0040] Step A2: Premix the intermediate, triethylamine and anhydrous acetone, introduce dry nitrogen for protection, control the temperature at 10 °C in an ice-water bath, slowly add trifluoropropyltrichlorosilane and stir for reaction for 3.5 h, then raise the temperature for reflux reaction for 1.4 h. Among them, the feeding ratio of the intermediate, trifluoropropyltrichlorosilane, triethylamine and anhydrous acetone is 10 mmol: 10 mmol: 5 mL: 35 mL. After the reaction, rotary evaporate to remove acetone to obtain the modifier.

[0041] Step A3: Premix the modifier, fatty alcohol polyoxyethylene ether and dimethyl sulfoxide, raise the temperature to 70 °C, add nano-titanium dioxide and ultrasonically disperse it, stop heating and stir for 24 h. Among them, the feeding ratio of nano-titanium dioxide, modifier, fatty alcohol polyoxyethylene ether and dimethyl sulfoxide is 50 g: 7.5 g: 12 mL: 140 mL. The nano-titanium dioxide is selected from DK405-2 rutile-type fine powder with an average particle size of about 60 nm. Centrifuge to obtain the separated liquid phase, wash and dry the substrate with ethanol to obtain modified nano-titanium dioxide.

[0042] (2) Preparation of the coating material

[0043] Ingredients: Take 7.8 wt% of PMMA resin, and select LA2114-type resin raw material; 0.19 wt% of modified nano-titanium dioxide, prepared by this example; 0.1 wt% of leveling agent, select BYK-346-type silicone leveling agent; 0.03 wt% of defoaming agent, select BYK-088-type silicone defoaming agent; the balance is solvent, which is compounded from tetrahydrofuran, ethyl acetate and anisole according to the weight ratio of 1:0.3:0.15.

[0044] Miscibility: Stir and dissolve the PMMA resin and the solvent, then add the leveling agent and the defoaming agent and mix them. Add the modified nano-titanium dioxide with stirring and mix well, and perform vacuum degassing to obtain the coating material.

[0045] Example 4, preparation of a high-transparency and low-scattering coating material for perovskite photovoltaic cells, the specific implementation process is as follows:

[0046] (1) Preparation of modified nano-titanium dioxide

[0047] Step A1: Premix triallylamine, photoinitiator and tetrahydrofuran, raise the temperature to 50 °C, apply ultraviolet irradiation of 600 mW / cm 2 Slowly add mercaptoethanol and stir for reaction for 6.5 h. Among them, the feeding ratio of triallylamine, mercaptoethanol, photoinitiator and tetrahydrofuran is 10 mmol: 33 mmol: 6 mg: 20 mL. After the reaction, rotary evaporate to remove tetrahydrofuran to obtain the intermediate.

[0048] Step A2: premix the intermediate, triethylamine and anhydrous acetone, introduce dry nitrogen for protection, control the temperature at 5°C in an ice-water bath, slowly add trifluoropropyltrichlorosilane and stir to react for 4 hours, then heat and reflux to react for 1.5 hours, wherein the feed ratio of the intermediate, trifluoropropyltrichlorosilane, triethylamine and anhydrous acetone is 10mmol:10mmol:4mL:35mL. After the reaction, remove acetone by rotary evaporation to obtain a modifier.

[0049] Step A3: pre-mix the modifier, fatty alcohol polyoxyethylene ether and dimethyl sulfoxide, heat to 70°C, add nano titanium dioxide for ultrasonic dispersion, stop heating and stirring for 24 hours, wherein the feed ratio of nano titanium dioxide, modifier, fatty alcohol polyoxyethylene ether and dimethyl sulfoxide is 50g:8g:12mL:120mL, the nano titanium dioxide is selected from DK405-1 rutile micropowder, and the average particle size is about 30nm, centrifuge to separate the liquid phase, wash the substrate with ethanol and dry it to obtain modified nano titanium dioxide.

[0050] (2) Preparation of coating materials

[0051] Ingredients: 8.2wt% of PMMA resin is selected, and LA2114 resin raw material is selected; 0.21wt% of modified nano titanium dioxide is prepared by this embodiment; 0.1wt% of leveling agent is selected, and BYK-346 type silicone leveling agent is selected; 0.03wt% of defoaming agent is selected, and BYK-088 type silicone defoaming agent is selected; the balance is solvent, which is prepared by compounding tetrahydrofuran, ethyl acetate and anisole according to a weight ratio of 1:0.3:0.2.

[0052] Miscibility: Stir and dissolve the PMMA resin and the solvent, then add the leveling agent and the defoamer and mix them, add the modified nano titanium dioxide in a stirring state and mix well, perform vacuum degassing, and obtain the coating material.

[0053] In a comparative example, fluoride is used to modify the surface of nano titanium dioxide, specifically: nano titanium dioxide, tridecafluorooctyltrimethoxysilane and dimethyl sulfoxide are premixed, then an aqueous formic acid solution is added and mixed, and the mixture is stirred and coupled at room temperature for 24 hours, wherein the feed ratio of nano titanium dioxide, tridecafluorooctyltrimethoxysilane, dimethyl sulfoxide and aqueous formic acid solution is 50g:8g:150mL:50mL, and the volume fraction of the aqueous formic acid solution is 10%. Finally, the liquid phase is centrifuged and dried to obtain fluorine-modified nano titanium dioxide. Referring to Example 4, an equal amount of fluorine-modified nano titanium dioxide is replaced with modified nano titanium dioxide, and the rest of the implementation process is exactly the same.

[0054] Spin-coat the coating material prepared as above on a release mold, bake it at 80 °C for 2 h, demold to obtain a sample, and perform transmittance and haze tests with reference to the ASTM D1003-21 standard. Apply the above coating material to the surface of a perovskite photovoltaic cell, and set a blank example without a coating. Detect the cell efficiency with reference to the IEC 60904-1-2020 standard. The specific test results are shown in Table 1:

[0055] Table 1

[0056] Transmittance / % Haze / % Battery efficiency / % Example 1 91.24 3.55 20.13 Example 2 90.38 4.19 19.57 Example 3 90.79 3.82 19.82 Example 4 91.05 9.74 20.01 Comparative example 88.62 5.17 18.37 Blank example / / 20.45

[0057] It can be seen from the test results in Table 1 that the coating material prepared in the examples has higher light transmittance. Taking Example 4 and the comparative example as a comparison, under a similar introduction amount of nano-titanium dioxide in Example 4, the transmittance and cell efficiency of Example 4 are significantly better than those of the comparative example.

[0058] In the description of the specification, the description with reference to terms such as "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0059] The above content is only an example and explanation of the present invention. Those skilled in the art of this technology can make various modifications or supplements to the described specific embodiments or use similar methods to replace them. As long as they do not deviate from the invention or exceed the scope defined by this claim book, they should all fall within the protection scope of the present invention.

Claims

1. A high-transparency and low-scattering coating material for perovskite photovoltaic cells, characterized in that, The specific components are: 7.2 - 8.5 wt% of PMMA resin, 0.17 - 0.22 wt% of modified nano-titanium dioxide, 0.09 - 0.11 wt% of leveling agent, and 0.03 - 0.04 wt% of defoaming agent, with the balance being solvent; The modified nano-titanium dioxide is prepared by the following method: Step A1: Premix triallylamine, photoinitiator and tetrahydrofuran, heat up to 40 - 50 °C, apply 500 - 650 mW / cm 2 UV irradiation, slowly add mercaptoethanol and stir for reaction for 5.5 - 7 h to prepare an intermediate; Step A2: Premix the intermediate, triethylamine, and anhydrous acetone, introduce dry nitrogen for protection, control the temperature at 5 - 15 °C in an ice-water bath, slowly add trifluoropropyltrichlorosilane and stir for reaction for 3 - 4 h, then raise the temperature for reflux reaction for 1.2 - 1.6 h to prepare the modifier; Step A3: Premix the modifier, fatty alcohol polyoxyethylene ether, and dimethyl sulfoxide, raise the temperature to 60 - 80 °C, add nano-titanium dioxide for ultrasonic dispersion, stop heating and stir for 24 h, centrifuge to obtain the separated liquid phase, wash and dry the substrate with ethanol to obtain the modified nano-titanium dioxide.

2. The high-transmittance and low-scattering coating material for perovskite photovoltaic cells according to claim 1, wherein The feeding ratio of triallylamine, mercaptoethanol, photoinitiator, and tetrahydrofuran is 10 mmol : 32 - 35 mmol : 5 - 8 mg : 15 - 20 mL.

3. The high-transmittance and low-scattering coating material for perovskite photovoltaic cells according to claim 2, wherein, The feeding ratio of the intermediate, trifluoropropyltrichlorosilane, triethylamine, and anhydrous acetone is 10 mmol : 10 mmol : 4 - 6 mL : 30 - 40 mL.

4. The high-transparency and low-scattering coating material for perovskite photovoltaic cells according to claim 3, characterized in that The feeding ratio of nano-titanium dioxide, modifier, fatty alcohol polyoxyethylene ether, and dimethyl sulfoxide is 50 g : 6.5 - 8.5 g : 10 - 15 mL : 120 - 150 mL.

5. The high-transmission and low-scattering coating material for perovskite photovoltaic cells according to claim 4, wherein The nano-titanium dioxide is rutile-type titanium dioxide with an average particle size not higher than 100 nm.

6. The high-transparency and low-scattering coating material for perovskite photovoltaic cells according to claim 1, wherein Both the leveling agent and the defoaming agent are silicone-based additives.

7. The perovskite photovoltaic cell high-transparency and low-scattering coating material according to claim 1, wherein The solvent is compounded from tetrahydrofuran, ethyl acetate, and anisole.

8. A method for preparing a high-transparency and low-scattering coating material for a perovskite photovoltaic cell according to any one of claims 1-7, characterized in that, Specifically: Stir and dissolve the PMMA resin and the solvent, then add the leveling agent and the defoaming agent for mixing, add the modified nano-titanium dioxide with stirring to mix evenly, and perform vacuum degassing to obtain the coating material.