A high-transmittance nano-coating for perovskite solar cell TCO glass and a preparation method thereof

Abstract

The application belongs to the technical field of solar cells, and particularly relates to a high-transmittance nano coating for transparent conductive oxide (TCO) glass of a perovskite solar cell and a preparation method thereof. The high-transmittance nano coating for the TCO glass of the perovskite solar cell is prepared from a composite silica dispersion liquid, a polyhydroxy polymer dispersion liquid and a wetting and leveling agent. The high-transmittance nano coating has higher mechanical properties, higher stability and service life, superhydrophilicity and self-cleaning property, can be prepared in a normal temperature environment, is suitable for the perovskite solar cell, and can increase the light transmittance of the TCO glass of the perovskite solar cell.

Description

Technical Field

[0001] This invention belongs to the field of solar cell technology, specifically relating to a high-reflection nanocoating for transparent conductive oxide (TCO) glass in perovskite solar cells and its preparation method. Background Technology

[0002] A solar cell is a device that uses semiconductor materials to absorb sunlight and convert it into electrical energy. When sunlight shines on a solar cell, electrons in the semiconductor material are excited, thus generating an electric current. Depending on the semiconductor materials used, solar cells can be classified into several types: silicon-based solar cells, thin-film solar cells, and perovskite solar cells.

[0003] To protect the internal structure of solar cells, photovoltaic glass or TCO glass is typically used as a cover. However, when sunlight strikes the surface of the cover glass, some light is reflected due to the difference in refractive index, thus reducing the absorption of incident light by the solar cell. Therefore, an optical antireflection coating (anti-reflective film or anti-reflective coating) is usually applied to the light-facing surface of the solar cell to reduce reflected light, increase transmitted light, and achieve higher photoelectric conversion efficiency.

[0004] Traditional silicon-based solar cells increase the light transmittance of photovoltaic glass by embossing and applying anti-reflective coatings, achieving transmittance of over 94%. However, the transmittance of TCO glass used in perovskite solar cells is typically between 80% and 90%. Due to the unique structure of perovskite solar cells, embossing of TCO glass is not possible. Therefore, applying anti-reflective coatings is an effective method to address the low transmittance of TCO glass in perovskite solar cells.

[0005] The preparation of anti-reflective coatings for photovoltaic glass usually requires annealing at temperatures above 600°C to achieve good anti-reflective and mechanical properties. However, TCO glass cannot be annealed at temperatures above 600°C, so room temperature coating processes are required.

[0006] In the existing technology, there are not many anti-reflection nano-coating technologies for TCO glass in perovskite solar cells. Conventional anti-reflection coatings are mostly low-refractive-index materials. Silica is a common low-refractive-index optical coating material. At the same time, silica coatings can be prepared at room temperature. Therefore, silica coatings can be used as anti-reflection coatings for TCO glass.

[0007] The room-temperature preparation of silica coatings often employs the sol-gel method. The preparation methods for silica sols are mainly divided into acid-catalyzed and alkali-catalyzed methods. Silica coatings prepared by acid catalysis exhibit higher mechanical properties but less pronounced anti-reflection performance; while silica coatings prepared by alkali catalysis have higher anti-reflection performance but poorer mechanical properties. For example, patent application number 202411629896.X discloses a self-cleaning anti-reflection coating solution, its preparation method, and its application. The coating material obtained after coating with this solution has the advantages of high anti-reflection and high weather resistance, but poor mechanical properties. The acid-alkali two-step catalytic method can solve these problems. This involves compounding acid-catalyzed sols and alkali-catalyzed sols, or first preparing an acid-catalyzed (alkali-catalyzed) sol followed by alkali-catalyzed (acid-catalyzed) treatment, to obtain an acid-alkali two-step catalytic sol, thereby preparing an optical coating with high anti-reflection and good mechanical properties. However, silica sols prepared by the acid-alkali two-step catalytic method suffer from poor sol stability and short lifespan, limiting their large-scale application.

[0008] For example, patent application CN201010587173.X proposes a large-area silicon-based thin-film solar cell with an antireflective film and its preparation method. This method employs a two-step acid-base catalytic process, where an antireflective film is prepared on photovoltaic glass using a sol-gel method, which is then combined with the TCO thin film at the front electrode of the cell to achieve a double-layer antireflective effect. The sol preparation scheme for this antireflective film is a two-step acid-base catalytic process, using hydrochloric acid and ammonia water sequentially for acid catalysis and then base catalysis to synthesize silicon dioxide. Although this method can obtain SiO2 thin films with a continuously tunable refractive index in the range of 1.1–1.4, and can provide good antireflective effects on TCO glass, the sol stability cannot be maintained in the long term, and the mechanical properties of the prepared antireflective film deteriorate over time under the subsequent long-term action of base catalysis.

[0009] Based on the above technical background, a method for preparing a silica coating that combines high transparency, good mechanical properties, and long service life is provided, which is crucial for improving the performance of TCO glass in perovskite solar cells. Summary of the Invention

[0010] Based on the above technical background, the main objective of this invention is to provide a high-transmittance nanocoating for TCO glass in perovskite solar cells and its preparation method, thereby solving the problem of low transmittance of existing TCO glass in perovskite solar cells.

[0011] To achieve the aforementioned objectives, the technical solution adopted by this invention includes:

[0012] A first aspect of this invention is to provide a high-reflection nanocoating for TCO glass in perovskite solar cells, said high-reflection nanocoating for TCO glass in perovskite solar cells is prepared from the following raw materials in parts by weight:

[0013] 2-10 parts by weight of composite silica dispersion;

[0014] 90-98 parts by weight of polyhydroxy polymer dispersion;

[0015] Wetting and leveling agent: 0.01 to 1 part by weight.

[0016] Preferably, the composite silica dispersion is prepared from the following raw materials in parts by weight:

[0017]

[0018] Preferably, the polyhydroxy polymer dispersion is prepared by dispersing a polyhydroxy polymer in a mixed solvent, and the mass fraction of the polyhydroxy polymer dispersion is 1-5%.

[0019] Preferably, the wetting and leveling agent is selected from one or both of gemini siloxanes and ethynyl glycol vinyl ethers.

[0020] A second aspect of the present invention is to provide a method for preparing a high-reflection nanocoating for TCO glass in perovskite solar cells as described in the first aspect of the present invention, the method comprising the following steps:

[0021] Step 1: Mix the composite silica dispersion, the polyhydroxy polymer dispersion and the wetting and leveling agent, and stir evenly to obtain a high-reflection nano-coating liquid.

[0022] Step 2: Apply the high-reflection nano-coating liquid and cure it at room temperature to obtain the high-reflection nano-coating for the TCO glass of perovskite solar cells.

[0023] In step 1,

[0024] Preferably, the composite silica dispersion is slowly added to the polyhydroxy polymer dispersion, and then a wetting and leveling agent is added, and the mixture is stirred at 50-500 rpm for 5-20 minutes.

[0025] Preferably, the preparation method of the composite silica dispersion includes the following steps:

[0026] Step a: Divide the organic solvent into two equal parts. Mix one part of the organic solvent with water and ammonia to obtain solution A. Mix the other part of the organic solvent with alkoxysilane to obtain solution B.

[0027] Step b: Slowly add solution B to solution A, stir and react, then let stand and age to obtain silica sol;

[0028] Step c: Grade and composite silica sols of different particle sizes, heat under vacuum, add water, heat and concentrate to obtain composite silica dispersion.

[0029] In step a,

[0030] Preferably, the organic solvent is selected from one or more of methanol, ethanol, ethylene glycol, n-propanol, and isopropanol;

[0031] Preferably, the concentration of the ammonia solution is 25-28 wt%.

[0032] Preferably, the alkoxysilane is selected from one or more of tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, tetramethoxysilane, dimethyldimethoxysilane, and dimethyldiethoxysilane.

[0033] In step b,

[0034] Preferably, at room temperature, solution B is slowly added to solution A, and the mixture is stirred at 50-500 rpm for 2-5 hours. After the reaction is complete, the mixture is allowed to stand and age for 2-10 days to obtain silica sol.

[0035] In step c,

[0036] Preferably, silica sols of different particle sizes are graded and compounded, heated to boiling under vacuum conditions below 5 kPa, and after removing some organic solvents and ammonia, water is added, and the sol is heated to boiling under vacuum conditions below 5 kPa to concentrate the mass fraction of silica sol to 20-30 wt% to obtain a composite silica dispersion.

[0037] The silica sols of different particle sizes are selected from two or more of the following: ultra-large particle size 100-200 nm, large particle size 60-100 nm, medium particle size 30-60 nm, small particle size 10-30 nm, and ultra-small particle size 1-10 nm.

[0038] The beneficial effects of this invention are as follows:

[0039] (1) The high-reflection nano-coating for TCO glass in perovskite solar cells is prepared from a composite silica dispersion, a polyhydroxy polymer dispersion, and a wetting and leveling agent. This invention uses a polyhydroxy polymer as a binder, which gives the high-reflection nano-coating liquid higher stability and lifespan, and higher mechanical properties compared to silica coatings prepared using acid-base mixtures.

[0040] This invention uses composite nano-silica with a certain grade as an anti-reflection material, which can improve the mechanical properties of the high-reflection nano-coating and make the coating super-hydrophilic, thus enabling the perovskite solar cell panel to be self-cleaning after coating.

[0041] (2) The high-transmittance nano-coating described in this invention can increase the transmittance of perovskite solar cell TCO glass by 3.5 to 4.5%.

[0042] (3) The method for preparing the high-reflection nanocoating of the present invention involves introducing a polyhydroxy polymer as a binder into nano-silica, and utilizing the condensation reaction between composite nano-silica particles with a certain gradation and the polyhydroxy polymer to form an organic-inorganic hybrid nanocoating. Compared with conventional antireflection coatings, the antireflection nanocoating of the present invention can be prepared in a room temperature environment and is suitable for perovskite solar cells. It can increase the light transmittance of TCO glass in perovskite solar cells and also has excellent mechanical properties and self-cleaning function. Attached Figure Description

[0043] Figure 1 Transmittance images of Example 1, Example 2, Comparative Example 1, Comparative Example 2, and FTO glass are shown;

[0044] Figure 2 Images showing the light transmittance of Example 3 and ITO glass are provided.

[0045] Figure 3 The diagram shows a cross-sectional view of the high-reflection nanocoating and perovskite solar cell prepared in Example 1, as well as an SEM image of the high-reflection nanocoating. Detailed Implementation

[0046] The present invention will now be described in detail, and its features and advantages will become clearer and more apparent from these descriptions.

[0047] A first aspect of this invention is to provide a high-reflection nanocoating for TCO glass in perovskite solar cells, said high-reflection nanocoating for TCO glass in perovskite solar cells is prepared from the following raw materials in parts by weight:

[0048] 2-10 parts by weight of composite silica dispersion;

[0049] 90-98 parts by weight of polyhydroxy polymer dispersion;

[0050] Wetting and leveling agent: 0.01 to 1 part by weight.

[0051] Preferably, the high-reflection nanocoating for the TCO glass of perovskite solar cells is prepared from the following raw materials in parts by weight:

[0052] 5-6 parts by weight of composite silica dispersion;

[0053] 93.98–94.95 parts by weight of polyhydroxy polymer dispersion;

[0054] Wetting and leveling agent: 0.02 to 0.1 parts by weight.

[0055] The composite silica dispersion is prepared from the following raw materials in parts by weight:

[0056]

[0057] Preferably, the composite silica dispersion is prepared from the following raw materials in parts by weight:

[0058]

[0059] The polyhydroxy polymer dispersion is prepared by dispersing a polyhydroxy polymer in a mixed solvent, and the mass fraction of the polyhydroxy polymer dispersion is 1-5%.

[0060] Preferably, the mass fraction of the polyhydroxy polymer dispersion is 1.8–2.5%.

[0061] The wetting and leveling agent is selected from one or both of gemini siloxanes and ethynyl glycol vinyl ethers.

[0062] Preferably, the wetting and leveling agent is a gemini siloxane, ethynyl glycol ethylene ether, or a mixture of gemini siloxane and ethynyl glycol ethylene ether.

[0063] When the wetting and leveling agent is a mixture of gemini siloxane and ethynyl glycol vinyl ether, the mass ratio of gemini siloxane to ethynyl glycol vinyl ether is 2:1.

[0064] A second aspect of the present invention is to provide a method for preparing a high-reflection nanocoating for TCO glass in perovskite solar cells as described in the first aspect of the present invention, the method comprising the following steps:

[0065] Step 1: Mix the composite silica dispersion, the polyhydroxy polymer dispersion and the wetting and leveling agent, and stir evenly to obtain a high-reflection nano-coating liquid.

[0066] Step 2: Apply the high-reflection nano-coating liquid onto the medium and cure it at room temperature to obtain the high-reflection nano-coating for the TCO glass of perovskite solar cells.

[0067] The steps described above are described in detail below.

[0068] In step 1, the composite silica dispersion is slowly added to the polymer dispersion, and then the wetting and leveling agent is added. The mixture is stirred at 50-500 rpm for 5-20 minutes.

[0069] Preferably, the mixture is stirred at 250 rpm for 10 minutes.

[0070] According to a preferred embodiment of the present invention, the preparation method of the composite silica dispersion includes the following steps:

[0071] Step a: Divide the organic solvent into two equal parts. Mix one part of the organic solvent with water and ammonia to obtain solution A. Mix the other part of the organic solvent with alkoxysilane to obtain solution B.

[0072] Step b: Slowly add solution B to solution A, stir and react, then let stand and age to obtain silica sol;

[0073] Step c: Grade and composite silica sols of different particle sizes, heat under vacuum, add water, heat and concentrate to obtain composite silica dispersion.

[0074] Preferably, in step a, the organic solvent is selected from one or more of methanol, ethanol, ethylene glycol, n-propanol, and isopropanol.

[0075] Preferably, the organic solvent is ethanol, methanol, or isopropanol.

[0076] The concentration of the ammonia solution is 25-28 wt%.

[0077] The alkoxysilane is selected from one or more of tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, tetramethoxysilane, dimethyldimethoxysilane, and dimethyldiethoxysilane.

[0078] Preferably, the alkoxysilane is tetraethoxysilane, tetramethoxysilane, or a mixture of tetraethoxysilane and methyltriethoxysilane.

[0079] In step b, at room temperature, solution B is slowly added to solution A, and the mixture is stirred at 50-500 rpm for 2-5 hours. After the reaction is complete, the mixture is allowed to stand and age for 2-10 days to obtain silica sol.

[0080] Preferably, at room temperature, solution B is slowly added to solution A, and the mixture is stirred at 300 rpm for 2-3 hours. After the reaction is complete, the mixture is allowed to stand and age for 5 days to obtain silica sol.

[0081] In step c, by controlling the amount of ammonia or water added, nano-silica sols with different particle sizes can be obtained, namely ultra-large particle size (100-200nm), large particle size (60-100nm), medium particle size (30-60nm), small particle size (10-30nm), and ultra-small particle size (1-10nm).

[0082] Different particle sizes of silica sol were graded and compounded, and then heated to boiling under vacuum conditions below 5 kPa. After removing some organic solvents and alkaline catalysts, a certain amount of water was added, and the sol was heated to boiling under vacuum conditions below 5 kPa to concentrate the mass fraction of silica sol to 20-30 wt%, thus obtaining a composite silica dispersion with a certain grade.

[0083] The silica sols of different particle sizes are selected from two or more of the following: ultra-large particle size, large particle size, medium particle size, small particle size, and ultra-small particle size silica sols.

[0084] The gradation relationship of the ultra-large particle size, large particle size, medium particle size, small particle size, and ultra-small particle size silica sol is (0-2):(0-3):(0-4):(1-5):1, based on the silica solid content.

[0085] By grading and compounding silica with different particle sizes, the smaller particles can adhere to the larger particles. On the one hand, this increases the surface roughness of the coating and achieves a superhydrophilic effect; on the other hand, the relatively small particles can fill the gaps between the large particles and can also act as "bridges" to connect the large particles, so that there are more connection sites between the large particles, thereby achieving better mechanical properties of the coating.

[0086] According to a preferred embodiment of the present invention, the preparation method of the polyhydroxy polymer dispersion includes the following steps:

[0087] The polyhydroxy polymer is added to a mixed solvent and dispersed evenly to obtain a polyhydroxy polymer dispersion with a mass fraction of 1-5%.

[0088] Preferably, the mass fraction of the polyhydroxy polymer dispersion is 1.8–2.5%.

[0089] The polyhydroxy polymer is selected from one or more of polyvinyl alcohol (PVA), polyacrylic acid (PAA), polysiloxane, polysilazane, and epoxy resin.

[0090] Preferably, the polyhydroxy polymer is selected from one or more of polysiloxane, polysilazane, polyvinyl alcohol, and polyacrylic acid.

[0091] More preferably, the polyhydroxy polymer is obtained by mixing polysiloxane and polysilazane in a mass ratio of 10:1.

[0092] Alternatively, the polyhydroxy polymer is obtained by mixing polysiloxane and polyvinyl alcohol in a mass ratio of 5:1.

[0093] Alternatively, the polyhydroxy polymer is obtained by mixing polysiloxane and polyacrylic acid in a mass ratio of 20:1.

[0094] The polyhydroxy polymers described in this invention are mainly water-soluble polymers, characterized by having a certain chain length, containing abundant hydroxyl groups or generating abundant hydroxyl groups after hydrolysis, and being miscible with water or other hydrophilic polar solvents.

[0095] The mixed solvent is selected from one or more of water, methanol, ethanol, ethylene glycol, n-propanol, and isopropanol.

[0096] Preferably, the mixed solvent is selected from one or more of water, ethanol, and isopropanol.

[0097] More preferably, the mixed solvent is obtained by mixing water and ethanol in a volume ratio of (1-2):(1-4).

[0098] Alternatively, the mixed solvent is obtained by mixing water, ethanol, and isopropanol in a volume ratio of 1:2:2.

[0099] In step 2, the medium is a TCO glass panel. Preferably, a high-reflection nano-coating liquid is applied to the TCO glass panel.

[0100] The preferred coating method is spraying, roller coating, or spin coating.

[0101] When using spraying or roller coating, apply the high-reflection nano coating liquid onto the TCO glass panel at a coating speed of 3–8 m / min, and cure at room temperature for 5–20 min.

[0102] Preferably, the high-reflection nano-coating liquid is applied to the TCO glass panel at a coating speed of 6 m / min and cured at room temperature for 10 min.

[0103] When using spin coating, spin coating is performed at a speed of 1000-2000 rpm and an acceleration of 100-300 rpm for 20-45 seconds. After spin coating, the mixture is cured at room temperature for 5-20 minutes.

[0104] Preferably, the spin coating is performed at a spin coating speed of 1500 rpm and an acceleration of 200 rpm for 30 seconds. After spin coating, the material is cured at room temperature for 10 minutes.

[0105] Example

[0106] The present invention is further illustrated below with specific examples. These embodiments are merely illustrative and not intended to limit the scope of the invention. All raw materials used in the embodiments of the present invention are commercially available.

[0107] Example 1

[0108] Step 1, Preparation of composite silica dispersion:

[0109] Weigh out 11.5 parts by weight of tetraethoxysilane, 85 parts by weight of organic solvent ethanol, 0.2 to 2 parts by weight of ammonia (the concentration of ammonia is 25-28 wt%), and 3.5 parts by weight of water.

[0110] Divide the ethanol into two equal parts. Mix one part of the ethanol with water and ammonia to obtain solution A. Mix the other part of the ethanol with tetraethoxysilane to obtain solution B.

[0111] At room temperature, solution B was slowly added to solution A and stirred at 300 rpm. After reacting for 3 hours, the mixture was allowed to stand for 5 days to obtain nano-silica sol.

[0112] By controlling the amount of ammonia added, nano-silica sols with different particle sizes can be obtained, namely large particle size (60-100nm), medium particle size (30-60nm), small particle size (10-30nm), and ultra-small particle size (1-10nm).

[0113] The silica sols of different particle sizes were graded and compounded according to different quantitative relationships. The gradation relationship of the medium, small and ultra-small particle size nano silica sols was 0.1:1:1 (the ratio of silica solid content). After removing some organic solvent and alkaline catalyst by heating to boiling under vacuum conditions below 5 kPa, a certain amount of water was added, and the sol was heated to boiling under vacuum conditions below 5 kPa to concentrate the mass fraction of silica sol to 20 wt%, thus obtaining a composite silica aqueous dispersion with a certain gradation.

[0114] By grading silica particles of different sizes and compounding them, the smaller particles can adhere to the larger particles. On the one hand, this increases the surface roughness of the coating and achieves a superhydrophilic effect; on the other hand, the relatively small particles can fill the gaps between the large particles and can also act as "bridges" to connect the large particles, so that there are more connection sites between the large particles, thereby achieving better mechanical properties of the coating.

[0115] Step 2, Preparation of the polyhydroxy polymer dispersion:

[0116] The polyhydroxy polymers described in this invention are mainly water-soluble polymers, characterized by having a certain chain length, containing abundant hydroxyl groups or generating abundant hydroxyl groups after hydrolysis, and being miscible in water or other hydrophilic polar solvents.

[0117] Polysiloxane and polysilazane were mixed at a mass ratio of 10:1 to obtain a polyhydroxy polymer mixture. The polyhydroxy polymer mixture was then uniformly dispersed in a mixed solvent to obtain a polyhydroxy polymer dispersion with a mass fraction of 1.8%. The mixed solvent was a mixture of water and ethanol with a volume ratio of water:ethanol = 2:1.

[0118] Step 3, Preparation of high-reflection nano-coating solution:

[0119] Weigh out 6 parts by weight of a composite silica aqueous dispersion with a certain gradation relationship, 93.98 parts by weight of a polyhydroxy polymer dispersion, and 0.02 parts by weight of a wetting and leveling agent, a gemini siloxane.

[0120] The composite silica dispersion from step 1 is slowly added to the polyhydroxy polymer dispersion from step 2, and then the wetting and leveling agent Gemini siloxane is added. After stirring at 50-500 rpm for 10 minutes, a high-reflection nano-coating solution is obtained.

[0121] Step 4, Preparation of the high-reflection nanocoating for the TCO glass of perovskite solar cells:

[0122] In this embodiment, a roller coating process is used to load the high-reflection nano-coating liquid into the coating equipment and deposit it onto the TCO glass panel of the perovskite solar cell at a transfer speed of 6 m / min. After curing at room temperature for 10 min, a high-reflection nano-coating of the perovskite solar cell TCO glass is obtained, and the film thickness is measured to be 115 nm.

[0123] The TCO glass used is fluorine-doped tin oxide conductive glass (FTO glass), with a size of 30cm*30cm and a thickness of 3.2mm.

[0124] Example 2

[0125] Step 1, Preparation of composite silica dispersion:

[0126] Weigh out 9.5 parts by weight of tetramethoxysilane, 85 parts by weight of methanol (organic solvent), 0.1 to 1.5 parts by weight of ammonia (ammonia concentration of 25-28 wt%), and 5 parts by weight of water.

[0127] Methanol was divided into two equal parts. One part of methanol was mixed with water and ammonia to obtain solution A. The other part of methanol was mixed with tetramethoxysilane to obtain solution B.

[0128] At room temperature, solution B was slowly added to solution A and stirred at 300 rpm. After reacting for 2 hours, the mixture was allowed to stand for 5 days to obtain nano-silica sol.

[0129] By controlling the amount of ammonia added, nano-silica sols with different particle sizes can be obtained, namely small particle size (10-30nm) and ultra-small particle size (1-10nm).

[0130] The silica sols of different particle sizes were graded and compounded according to different quantitative relationships. The gradation relationship of the small and ultra-small particle size nano silica sols was 1.5:1 (the ratio of silica solid content). After removing some of the organic solvent methanol and alkaline catalyst by heating to boiling under vacuum conditions below 5 kPa, a certain amount of water was added, and the sol was heated to boiling under vacuum conditions below 5 kPa to concentrate the mass fraction of silica sol to 20 wt%, thus obtaining a composite silica aqueous dispersion with a certain gradation.

[0131] Step 2, Preparation of the polyhydroxy polymer dispersion:

[0132] Polysiloxane and polyvinyl alcohol were mixed at a mass ratio of 5:1 to obtain a polyhydroxy polymer mixture. The polyhydroxy polymer was then uniformly dispersed in a mixed solvent to obtain a 2% (by mass) polyhydroxy polymer dispersion. The mixed solvent was a mixture of water and ethanol at a volume ratio of water:ethanol = 1:4.

[0133] Step 3, Preparation of high-reflection nano-coating solution:

[0134] Weigh out 5 parts by weight of composite silica dispersion, 94.9 parts by weight of polyhydroxy polymer dispersion, and 0.1 parts by weight of wetting and leveling agent. The wetting and leveling agent is a mixture of gemini siloxane and ethynyl glycol vinyl ether in a mass ratio of 2:1.

[0135] The composite silica aqueous dispersion with a certain gradation relationship in step 1 is slowly added to the polyhydroxy polymer dispersion in step 2, and then a wetting and leveling agent is added. After stirring at 50-500 rpm for 10 minutes, a high-transparency nano-coating liquid is obtained.

[0136] Step 4, Preparation of the high-reflection nanocoating for the TCO glass of perovskite solar cells:

[0137] In this embodiment, a roller coating process is used to load the high-reflection nano-coating liquid into the coating equipment and deposit it onto the TCO glass panel of the perovskite solar cell at a transfer speed of 6 m / min. After curing at room temperature for 10 min, a high-reflection nano-coating of the perovskite solar cell TCO glass is obtained, and the film thickness is measured to be 129 nm.

[0138] The TCO glass used is fluorine-doped tin oxide conductive glass (FTO glass), with a size of 30cm*30cm and a thickness of 3.2mm.

[0139] Example 3

[0140] Step 1, Preparation of composite silica dispersion:

[0141] Weigh out 12 parts by weight of alkoxysilane, 82.7-87.2 parts by weight of isopropanol (organic solvent), 0.3 parts by weight of ammonia (ammonia concentration 25-28 wt%), and 0.5-5 parts by weight of water. The alkoxysilane is tetraethoxysilane or methyltriethoxysilane, with a mass ratio of tetraethoxysilane:methyltriethoxysilane = 4:1.

[0142] Isopropanol was divided into two equal parts. One part of the isopropanol was mixed with water and ammonia to obtain solution A. The other part of the isopropanol was mixed with alkoxysilane to obtain solution B.

[0143] At room temperature, solution B was slowly added to solution A and stirred at 300 rpm. After reacting for 2 hours, the mixture was allowed to stand for 5 days to obtain nano-silica sol.

[0144] By controlling the amount of water added, nano-silica sols with different particle sizes can be obtained, namely medium particle size (30-60nm), small particle size (10-30nm), and ultra-small particle size (1-10nm).

[0145] The silica sols of different particle sizes were graded and compounded according to different quantitative relationships. The gradation relationship of the medium-sized, small-sized, and ultra-small-sized nano-silica sols was 0.5:0.8:1 (the ratio of silica solid content). After removing some organic solvent and alkaline catalyst by heating to boiling under vacuum conditions below 5 kPa, a certain amount of water was added, and the sol was heated to boiling under vacuum conditions below 5 kPa to concentrate the mass fraction of silica sol to 20 wt%, thus obtaining a composite silica aqueous dispersion with a certain gradation.

[0146] Step 2, Preparation of the polyhydroxy polymer dispersion:

[0147] Polysiloxane and polyacrylic acid were mixed at a mass ratio of 20:1 to obtain a polyhydroxy polymer mixture. The polyhydroxy polymer mixture was uniformly dispersed in a mixed solvent to obtain a polyhydroxy polymer dispersion with a mass fraction of 2.5%. The mixed solvent was a mixture of water, ethanol, and isopropanol, with a volume ratio of water:ethanol:isopropanol = 1:2:2.

[0148] Step 3, Preparation of high-reflection nano-coating solution:

[0149] Weigh out 5 parts by weight of a composite silica aqueous dispersion with a certain gradation relationship, 94.95 parts by weight of a polyhydroxy polymer dispersion, and 0.05 parts by weight of a wetting and leveling agent, a gemini siloxane.

[0150] The composite silica dispersion from step 1 is slowly added to the polyhydroxy polymer dispersion from step 2, followed by the addition of a wetting and leveling agent. After stirring at 50-500 rpm for 10 minutes, a high-reflection nano-coating solution is obtained.

[0151] Step 4, Preparation of the high-reflection nanocoating for the TCO glass of perovskite solar cells:

[0152] In this embodiment, a spin coating process is used. The TCO glass is placed in the center of the stage of the spin coater, and a high-reflection nano-coating droplet is added to the TCO glass. Spin coating is performed at a rotation speed of 1500 rpm and an acceleration of 200 rpm for 30 seconds. After completion, it is cured at room temperature for 10 minutes to obtain a high-reflection nano-coating for the perovskite solar cell TCO glass. The film thickness is measured to be 125 nm.

[0153] The TCO glass used is indium-doped tin oxide conductive glass (ITO glass), with a size of 5cm*5cm and a thickness of 1.1mm.

[0154] Comparative Example

[0155] Comparative Example 1

[0156] The high-reflection nanocoating was prepared in a manner similar to that in Example 1, except that a composite silica dispersion with a certain gradation was not used in step 1, and only silica with a small particle size was used to prepare an aqueous dispersion.

[0157] Comparative Example 2

[0158] The high-reflection nanocoating was prepared in a similar manner to that in Example 1, except that the polyhydroxy polymer in step 2 was polysiloxane.

[0159] Experimental Example

[0160] Experiment Example 1 Performance Test

[0161] The TCO glasses prepared in Examples 1-3 and Comparative Examples 1-2 were tested for transmittance, hardness, adhesion, water contact angle, and transmittance attenuation. The test results are shown in Table 1. Transmittance was measured using spectrophotometry in the wavelength range of 380-780 nm. Examples 1, 2, Comparative Examples 1 and 2 used FTO glass, which had a transmittance of 81.1%. Transmittance images are shown below. Figure 1 Example 3 uses ITO glass, which has a light transmittance of 83.8%. The light transmittance image is shown below. Figure 2The pencil hardness test method is conducted according to GB / T6739-2006 standard. The adhesion test method is conducted according to ISO9211-4:201 standard, using a cross-cut tester on the coated surface of the sample. The cut edges should be completely smooth and without peeling, indicating a grade of 0. The water contact angle test surface is the coated surface, and the static water contact angle is measured after 5 seconds. The transmittance decay test is conducted under accelerated pressure aging conditions of 121℃ and 100%RH for 24 hours. The change in transmittance before and after the test is calculated as: transmittance decay ΔT = (transmittance before test - transmittance after test) / transmittance before test.

[0162] Table 1 Performance Test Results

[0163] Test Project Light transmittance Pencil hardness Adhesion Water contact angle Transmittance attenuation ΔT Example 1 85.4％ 2H Level 0 3.8° △T＝0.47％ Example 2 85.2％ 3H Level 0 2.9° △T＝0.21％ Example 3 86.5％ 3H Level 0 4.2° △T＝0.55％ Comparative Example 1 85.1％ 2H Level 0 11.2° △T＝1.24％ Comparative Example 2 83.5％ 2H Level 0 15.5° △T＝0.86％

[0164] As can be seen from Table 1, the light transmittance of Examples 1 to 3 is 85.2% or higher, which is higher than that of Comparative Examples 1 to 2; the pencil hardness of Examples 1 to 3 is 2H or higher, which is higher than that of Comparative Examples 1 to 2; the adhesion of Examples 1 to 2 is grade 0, which is high; the water contact angle of Examples 1 to 3 is below 4.2°, and the hydrophilicity of Examples 1 to 3 is higher than that of Comparative Examples 1 to 2; the light transmittance attenuation of Examples 1 to 3 is lower than that of Comparative Examples 1 to 2.

[0165] from Figure 1 and Figure 2 It can be seen that the light transmittance of Examples 1 and 2 is higher than that of FTO glass, and the light transmittance of Example 3 is higher than that of ITO glass, indicating that coating the surface of FTO glass and ITO glass with the high-reflection nano-coating described in this invention can improve the light transmittance of TCO glass.

[0166] Experiment Example 2: SEM Testing

[0167] The high-reflection nanocoating prepared in Example 1 was tested by scanning electron microscopy, and the test results are as follows: Figure 3 As shown.

[0168] from Figure 3 It can be seen that in the high-reflection nano-coating, silica particles of different sizes are evenly distributed, which gives the large silica particles more connection sites, which is beneficial to improving the mechanical properties of the high-reflection nano-coating.

[0169] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

Claims

1. A method for preparing a high-reflection nanocoating for TCO glass in perovskite solar cells, characterized in that, The high-reflectance nanocoating for TCO glass in perovskite solar cells is prepared from the following raw materials in parts by weight: 2-10 parts by weight of composite silica dispersion; 90-98 parts by weight of polyhydroxy polymer dispersion; Wetting and leveling agent: 0.01 to 1 part by weight; The composite silica dispersion is prepared from the following raw materials in parts by weight: 60-90 parts by weight of organic solvent; 8-15 parts by weight of alkoxysilane; Ammonia solution 0.1–5 parts by weight; Water 0.1 to 8 parts by weight; The preparation method includes the following steps: Step 1: Mix the composite silica dispersion, the polyhydroxy polymer dispersion and the wetting and leveling agent, and stir evenly to obtain a high-reflection nano-coating liquid. Step 2: Apply the high-reflection nano-coating liquid and cure it at room temperature to obtain the high-reflection nano-coating for the TCO glass of perovskite solar cells. In step 1, the preparation method of the composite silica dispersion includes the following steps: Step a: Divide the organic solvent into two equal parts. Mix one part of the organic solvent with water and ammonia to obtain solution A. Mix the other part of the organic solvent with alkoxysilane to obtain solution B. Step b: Slowly add solution B to solution A, stir and react, then let stand and age to obtain silica sol; Step c: Grade and composite silica sols of different particle sizes, heat under vacuum, add water, heat and concentrate to obtain composite silica dispersion; The alkoxysilane is selected from one or more of tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, tetramethoxysilane, dimethyldimethoxysilane, and dimethyldiethoxysilane. The polyhydroxy polymer dispersion is prepared by dispersing a polyhydroxy polymer in a mixed solvent, and the mass fraction of the polyhydroxy polymer dispersion is 1-5%. The polyhydroxy polymer is obtained by mixing polysiloxane and polysilazane in a mass ratio of 10:

1. Alternatively, the polyhydroxy polymer is obtained by mixing polysiloxane and polyvinyl alcohol in a mass ratio of 5:1; Alternatively, the polyhydroxy polymer is obtained by mixing polysiloxane and polyacrylic acid in a mass ratio of 20:1; The wetting and leveling agent is selected from one or two of gemini siloxanes and acetylacetonide; In step c, Different particle sizes of silica sol were graded and compounded, and heated to boiling under vacuum conditions below 5 kPa. After removing some organic solvent and ammonia, water was added, and the sol was heated to boiling under vacuum conditions below 5 kPa to concentrate the mass fraction of silica sol to 20-30 wt% and obtain a composite silica dispersion. The silica sols of different particle sizes are selected from two or more of the following: ultra-large particle size 100-200 nm, large particle size 60-100 nm, medium particle size 30-60 nm, small particle size 10-30 nm, and ultra-small particle size 1-10 nm.

2. The preparation method according to claim 1, characterized in that, In step 1, The composite silica dispersion was slowly added to the polyhydroxy polymer dispersion, followed by the addition of a wetting and leveling agent. The mixture was stirred at 50–500 rpm for 5–20 minutes.

3. The preparation method according to claim 1, characterized in that, In step a, The organic solvent is selected from one or more of methanol, ethanol, ethylene glycol, n-propanol, and isopropanol; The concentration of the ammonia solution is 25-28 wt%. The alkoxysilane is selected from one or more of tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, tetramethoxysilane, dimethyldimethoxysilane, and dimethyldiethoxysilane.

4. The preparation method according to claim 1, characterized in that, In step b, At room temperature, solution B is slowly added to solution A, and the mixture is stirred at 50-500 rpm for 2-5 hours. After the reaction is complete, the mixture is allowed to stand and age for 2-10 days to obtain silica sol.

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