Preparation method of perovskite solar cell using alcohol-soluble SnO2 as electron transport layer, alcohol-soluble SnO2 and preparation method thereof

Abstract

The present invention belongs to the field of solar energy technology and specifically relates to a method for preparing a perovskite solar cell using alcohol-soluble SnO2 as an electron transport layer, alcohol-soluble SnO2, and its preparation method. The present invention utilizes a hydrothermal method to prepare SnO2 nanoparticles with high crystallinity and small particle size. The ligands on the SnO2 surface are optimized, with short-chain hydroxycarboxylic acids selected to provide relatively stable, highly conductive, low-boiling-point, and easily removable ligands. Diester compounds are used for chelation to form stable coordination bonds with the SnO2. The SnO2 prepared by the present invention is soluble in organic alcohol solvents (such as isopropyl alcohol) that do not destroy the perovskite structure. The system maintains a near-neutral pH, making it suitable for use as an electron transport layer material in perovskite devices.

Description

Technical Field

[0001] The present invention belongs to the field of solar energy technology, and specifically relates to a method for preparing a perovskite solar cell using alcohol-soluble SnO2 as an electron transport layer, alcohol-soluble SnO2 and its preparation method. Background Art

[0002] With the continuous development of science and technology, perovskite solar cells have gradually attracted widespread attention as an emerging technology. In perovskite solar cells, commonly used inorganic electron transport materials include TiO2 and SnO2, which are usually dispersed in water and widely used in formal device structures.

[0003] However, the application of these materials in the trans structure is limited. One of the main reasons is that moisture will destroy the perovskite structure, thus narrowing their scope of use in the field of perovskite solar cells. Secondly, because in the formal device structure, SnO2 is dispersed in an alkaline aqueous solution with a pH of 11-12, it can only be used on ITO (tin-doped indium oxide) and FTO (Fluorine-doped Tin Oxide fluorine-doped tin oxide conductive glass) substrates, and cannot be directly spin-coated on the perovskite layer because alkaline substances will also dissociate the perovskite, affecting its photoelectric conversion efficiency and operating life. In addition, the strong alkaline solution remaining in the SnO2 aqueous solution requires high corrosion resistance of the equipment, which further limits its application in the perovskite industry. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for preparing a perovskite solar cell using alcohol-soluble SnO2 as an electron transport layer, alcohol-soluble SnO2 and its preparation method, so as to solve the problem of limited application of SnO2 materials in perovskite solar cells in the prior art.

[0005] The technical solutions adopted in the present invention are as follows:

[0006] The preparation method of alcohol-soluble SnO2 comprises:

[0007] S1. At 20-30 ° C, the tin salt is mixed with the first solvent to form a first reaction system, the ligand is mixed with the second solvent to form a second reaction system, the second reaction system is added dropwise to the first reaction system, and heated to 50-60 ° C under vacuum conditions to dissolve to obtain a transparent SnO2 reaction liquid precursor solution;

[0008] S2. The SnO2 reaction liquid precursor solution was loaded into a hydrothermal reactor, set the temperature to 90-200 ℃, the reaction was 1-24h, to obtain SnO2 nanomaterial mother liquor;

[0009] S3. The SnO2 nanomaterial mother liquor is mixed with a precipitant to form a precipitate, which is then dissolved with a good solvent, precipitated with a precipitant, and the SnO2 nanoparticles are separated by centrifugation and repeatedly washed to obtain pure SnO2 nanoparticles;

[0010] S4. The SnO2 nanoparticles in S3 were dispersed with an organic alcohol, and a hydroxycarboxylic acid compound having a carbon chain number of 2-9 was added for ligand exchange. The reaction was carried out for 1-24 hours and purified to obtain alcohol-soluble SnO2 nanoparticles.

[0011] S5. Dispersing the SnO2 nanoparticles in an organic alcohol solvent to obtain an alcohol-soluble SnO2 dispersion.

[0012] Furthermore, the ligand in S1 is an organic amine with a carbon chain number of 6-18, an organic acid, and an organic amine with a hydroxyl group.

[0013] Furthermore, the first solvent described in S1 refers to a solvent whose boiling point is lower than the reaction temperature of the system, and the second solvent refers to a solvent whose boiling point is higher than the reaction temperature of the system.

[0014] Furthermore, in S1, the ratio of the tin salt to the ligand is 1:(0.1-10) in terms of the amount of substance.

[0015] Furthermore, the precipitant in S3 is one of methanol, ethanol, acetone and acetonitrile.

[0016] Furthermore, the good solvent in S3 is one of dichloromethane, chloroform, n-hexane, n-heptane, n-octane, toluene, and xylene.

[0017] Alcohol-soluble SnO2, including SnO2 inorganic matter and organic ligands on the surface of SnO2 inorganic matter.

[0018] Furthermore, the organic ligand is a hydroxycarboxylic acid compound with a carbon chain number of 2-9, and the weight of the organic ligand accounts for 3%-25% of the total.

[0019] Furthermore, the alcohol-soluble SnO2 has a particle size of 3-10 nm and a band gap of 3.6-4.0 eV.

[0020] The preparation method of perovskite solar cells using alcohol-soluble SnO2 as the electron transport layer is as follows: first, a hole transport material is spin-coated on the ITO anode layer to form a hole transport layer, a perovskite solution is spin-coated on the hole transport layer serving as the carrier to form an absorption layer, an alcohol solution of SnO2 is spin-coated on the absorption layer, and after drying, an electron transport layer is formed, and finally, an Au cathode electrode layer is evaporated and encapsulated to form a perovskite solar cell.

[0021] The beneficial effects of the present invention are as follows:

[0022] The SnO2 provided by the present invention can be dissolved in organic alcohol solvents. These solvents (such as isopropyl alcohol) will not destroy the perovskite structure, and the pH value of the system is close to neutral, so that it can be used as an electron transport layer material in perovskite devices.

[0023] This invention uses short-chain hydroxycarboxylic acids as organic ligands on the tin oxide surface, providing a relatively stable, highly conductive, low-boiling-point, and easily removable ligand. The carboxyl group (-COOH) chelates to form a stable coordination bond with SnO2, effectively reducing dangling bonds (both Sn and O) on the SnO2 surface, thereby increasing the lifetime of photogenerated carriers in the device and, consequently, enhancing device performance and lifespan. The hydrothermal method produces SnO2 nanoparticles with high crystallinity and small particle size, which have fewer defect states than SnO2 prepared by conventional low-temperature sol-gel methods, thus improving device performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 (a) is a schematic diagram of dangling bonds on the surface of conventional SnO2 nanomaterials, and (b) is a schematic diagram of ligands on the surface of modified SnO2 nanomaterials.

[0025] Figure 2 This is a TEM image (Transmission Electron Microscope image) of SnO2 nanoparticles prepared in the present invention.

[0026] Figure 3 This is the XRD pattern (X-Ray Diffraction pattern) of SnO2 nanoparticles prepared in the present invention. DETAILED DESCRIPTION

[0027] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0028] The present invention provides a method for preparing a perovskite solar cell using alcohol-soluble SnO2 as an electron transport layer, an alcohol-soluble SnO2 dispersion, and a preparation method thereof. The perovskite solar cell comprises a transparent anode, a hole transport layer, a perovskite absorption layer, an electron transport layer, and a cathode layer. The electron transport layer is prepared by spin coating, printing, and slit coating of an alcohol-soluble SnO2 dispersion.

[0029] The preparation method of alcohol-soluble SnO2 comprises the following steps:

[0030] S1. At 20-30 ° C, the tin salt is mixed with the first solvent to form a first reaction system, the ligand is mixed with the second solvent to form a second reaction system, the second reaction system is added dropwise to the first reaction system, and heated to 50-60 ° C under vacuum conditions to dissolve to obtain a transparent SnO2 reaction liquid precursor solution;

[0031] S2. The SnO2 reaction liquid precursor solution was loaded into a hydrothermal reactor, set the temperature to 90-200 ℃, the reaction was 1-24h, to obtain SnO2 nanomaterial mother liquor;

[0032] S3. The SnO2 nanomaterial mother liquor is mixed with a precipitant to form a precipitate, which is then dissolved with a good solvent, precipitated with a precipitant, and centrifuged to separate the SnO2 nanoparticles. The washing is repeated twice to obtain pure SnO2 nanoparticles.

[0033] S4. The SnO2 nanomaterial in S3 is dispersed with an organic alcohol solution, and a hydroxycarboxylic acid compound having a carbon chain number of 2-9 is added for ligand exchange. The reaction is carried out for 1-24 hours and purified to obtain alcohol-soluble SnO2 nanoparticles.

[0034] S5. Dispersing the SnO2 nanoparticles in an organic alcohol solvent to obtain an alcohol-soluble SnO2 dispersion.

[0035] The particle size of SnO2 nanomaterials is determined by the temperature and reaction time during the hydrothermal reaction. Generally speaking, the higher the temperature and the longer the time, the larger the particle size of the nanomaterial will be. The photoelectric performance of the nanomaterial is related to the particle size. The device performance of SnO2 with a particle size of 5-10nm is the best.

[0036] The tin salt described in S1 can be selected from but is not limited to SnCl4 and its pentahydrate, SnCl2 and its dihydrate, tin (II) sulfate, tin acetate, tin trifluoromethanesulfonate, tin tetrafluoride, stannous isooctanoate, tin tetraiodide, butyltin trichloride, tin tetrabromide, dibutyltin oxide, stannous iodide, tin (II) bromide, tin (II) oxalate, tin diacetylacetonate, tin diacetylacetonate chloride, sodium stannate and its compounds, tin ethoxide, dibutyltin dichloride, stannous tetrafluoroborate, dibutyltin diacetate, butyltin tri(2-ethyl-1-hexanoate), potassium stannate (IV) and its trihydrate, monobutyltin trichloride, and one or more of trimethyltin chloride.

[0037] The ligands described in S1 are selected from organic amines, organic acids, and organic amines with hydroxyl groups having a carbon chain number of 6-18, wherein the organic amines can be selected from but not limited to one or more of n-hexylamine, n-octylamine, n-decylamine, n-dodecylamine, n-tetradecylamine, n-hexadecylamine, n-octadecylamine, and oleylamine; the organic acids can be selected from but not limited to one or more of n-hexanoic acid, n-octanoic acid, n-decanoic acid, n-dodecanoic acid, n-tetradecylamine, n-hexadecylamine, n-octadecylamine, and oleic acid; the amines with hydroxyl groups can be selected from but not limited to one or more of ethanolamine, diethanolamine, triethanolamine, and isopropanolamine.

[0038] The first solvent described in S1 refers to a solvent whose boiling point is lower than the reaction temperature of the system, which is used to form high pressure conditions; it can be selected from but not limited to water, methanol, ethanol, and isopropanol;

[0039] The second solvent described in S1 refers to a solvent whose boiling point is higher than the reaction temperature of the system, and can be selected from but not limited to the following substances: water, dimethylformamide (DMF), dimethyl sulfoxide (DMSO) and N-methyl-2-pyrrolidone (NMP) and monohydric alcohols with a boiling point of 100-250°C, such as n-butanol, tert-butanol, isopentanol, n-pentanol, isohexanol, n-hexanol, n-heptanol, n-octanol, n-nonanol, n-decanol, benzyl alcohol, and phenylethyl alcohol;

[0040] The hydroxycarboxylic acid compound with a carbon chain number of 2-9 described in S4 satisfies the following general formula:

[0041] HO-R-COOH, where R can be an alkyl group (R-) or an aryl group (Ar-);

[0042] For example, the alkyl group may be selected from but not limited to one or more of glycolic acid, propanoic acid, hexanoic acid, isopropanoic acid, and isohexanoic acid; for example, the aryl group may be selected from but not limited to one or more of benzoic acid, phenylacetic acid, and phenylpropionic acid.

[0043] The organic alcohol solvent may be selected from, but is not limited to, one or more mixed solvents of ethanol, methanol, isopropanol, n-butanol, and isobutanol.

[0044] The present invention also provides an alcohol-soluble SnO2 dispersion, wherein the alcohol-soluble SnO2 comprises an inorganic SnO2 substance and an organic ligand on the surface of the SnO2. The calculated band gap range of the dispersion is 3.6-4.0 eV.

[0045] The surface of the nanoparticles carries the hydroxycarboxylic acid ligands of this application. On the one hand, these ligands disperse SnO2 in alcohol organic solvents; on the other hand, they coordinate with the dangling bonds in SnO2 to reduce the defect states in SnO2, thereby increasing the lifetime of photogenerated carriers and improving device performance and lifetime.

[0046] The weight of the ligands on the surface of the nanoparticles accounts for 3%-25% of the total weight. The calculation method is based on thermogravimetric analysis and the percentage of thermal weight loss of the nanomaterial powder in the temperature range of 100-600°C.

[0047] The electron mobility of the nanomaterials of the present invention is 10-200 cm 2 V -1 s -1 between.

[0048] The present invention also provides an inverse perovskite solar cell structure, namely, a transparent anode, a hole transport layer, a perovskite absorption layer, an electron transport layer, and a cathode layer. The electron transport layer is prepared by spin coating, printing, and slit coating of the alcohol-soluble tin oxide dispersion described in the present application.

[0049] A method for preparing alcohol-soluble SnO2 comprises the following steps:

[0050] Example 1

[0051] S1. At room temperature, 1 mmol of SnCl₄・5H₂O was mixed with 50 ml of ethanol to form a first reaction system. 1 mmol of ethanolamine, 1 mmol of n-hexylamine, and 2 mmol of n-hexanoic acid were mixed with 50 ml of DMF to form a second reaction system. The second reaction system was added dropwise to the first reaction system and heated at 100 Pa and 60°C to dissolve, yielding a transparent SnO₂ reaction liquid precursor solution.

[0052] S2. The SnO2 reaction liquid precursor solution was loaded into a 200ml hydrothermal reactor, set the temperature to 120 ℃, and reacted for 3h to obtain SnO2 nanomaterial mother liquor;

[0053] S3. The SnO2 nanomaterial mother liquor was mixed with 500ml of methanol, centrifuged to obtain a precipitate, and then dissolved with 50ml of n-hexane, 100ml of methanol was added to precipitate, and centrifuged at 5000rpm to separate the SnO2 nanoparticles. The washing was repeated twice to obtain pure SnO2 nanoparticles.

[0054] S4. Disperse SnO2 nanoparticles in 100 ml of isopropanol, add 1 g of isopropanoic acid, react for 2 h, and precipitate with 200 ml of n-hexane to obtain alcohol-soluble SnO2 nanoparticles.

[0055] S5. Disperse SnO2 nanoparticles in isopropanol to obtain a 2.5 wt% isopropanol SnO2 dispersion.

[0056] Example 2

[0057] S1. At room temperature, 1 mmol of tin acetate was mixed with 50 ml of ethanol to form a first reaction system. 0.5 mmol of ethanolamine, 1 mmol of oleic acid, and 0.5 mmol of oleylamine were mixed with 80 ml of DMSO to form a second reaction system. The second reaction system was added dropwise to the first reaction system and heated at 100 Pa and 60 ° C to dissolve to obtain a transparent SnO2 reaction liquid precursor solution.

[0058] S2. The SnO2 reaction liquid precursor solution was loaded into a 200ml hydrothermal reactor, set the temperature to 150 ℃, and reacted for 2h to obtain SnO2 nanomaterial mother liquor;

[0059] S3. The SnO2 nanomaterial mother liquor was mixed with 500ml of ethanol, centrifuged to obtain a precipitate, then dissolved in 50ml of n-heptane, precipitated with 100ml of ethanol, centrifuged at 5000rpm to separate the SnO2 nanoparticles, and the washing was repeated twice to obtain pure SnO2 nanoparticles;

[0060] S4. Disperse SnO2 nanoparticles in 100 ml of isopropanol, add 2 g of p-hydroxyphenylacetic acid, react for 5 h, and precipitate with 200 ml of n-heptane to obtain alcohol-soluble SnO2 nanoparticles.

[0061] S5. Disperse SnO2 nanoparticles in isopropanol to obtain a 2.5 wt% isopropanol SnO2 dispersion.

[0062] Example 3

[0063] S1. At room temperature, 1 mmol of SnCl₂·2H₂O was mixed with 50 ml of tert-butanol to form a first reaction system. 1 mmol of diethanolamine, 1 mmol of n-dodecylamine, and 2 mmol of n-dodecanoic acid were mixed with 50 ml of ethanol to form a second reaction system. The second reaction system was added dropwise to the first reaction system and heated at 100 Pa and 60°C to dissolve, yielding a transparent SnO₂ reaction liquid precursor solution.

[0064] S2. The SnO2 reaction liquid precursor solution was loaded into a 200ml hydrothermal reactor, set the temperature to 180 ℃, and reacted for 3h to obtain SnO2 nanomaterial mother liquor;

[0065] S3. The SnO2 nanomaterial mother liquor was mixed with 500ml of acetone, centrifuged to obtain a precipitate, and then dissolved with 50ml of n-octane, 100ml of acetone was added to precipitate, and centrifuged at 5000rpm to separate the SnO2 nanoparticles. The washing was repeated twice to obtain pure SnO2 nanoparticles.

[0066] S4. The SnO2 nanoparticles were dispersed in 100ml of isopropanol, 3g of hydroxyhexanoic acid was added, the reaction was allowed to proceed for 10h, and precipitated with 200ml of n-heptane to obtain alcohol-soluble SnO2 nanoparticles;

[0067] S5. Disperse SnO2 nanoparticles in isopropanol to obtain a 2.5 wt% isopropanol SnO2 dispersion.

[0068] The electron transport layer of the device is made from the tin oxide isopropanol dispersion in the embodiment and applied to the inverse perovskite solar cell. The inverse perovskite solar cell includes an ITO anode, a NiO x Hole transport layer, perovskite absorption layer, tin oxide electron transport layer and cathode gold.

[0069] The preparation method of an inverse perovskite solar cell includes the following steps: spin-coating an aqueous solution of nickel oxide on the ITO anode layer, and then annealing at 100°C for 10 minutes to form a hole transport layer; spin-coating a perovskite solution on the hole transport layer serving as a carrier to form an absorption layer; spin-coating the tin oxide isopropanol dispersion in Example 1 on the absorption layer, and forming an electron transport layer after drying; finally, evaporating an Au cathode electrode layer and encapsulating to form a perovskite solar cell device.

[0070] Inkjet printing method: In the above spin coating method, only the spin coating process is changed to inkjet printing, and the tin oxide layer material is annealed by a gradient temperature increase method under high vacuum conditions.

[0071] Comparative Example 1

[0072] S1. The 1mmol tin tetrachloride pentahydrate was dissolved in 500ml of deionized water, 10% NaOH aqueous solution was added, the pH was controlled at 12, and stirred until transparent to obtain SnO2 nanomaterial mother liquor;

[0073] S2. Add hydrochloric acid to the mother liquor to precipitate SnO2, centrifuge to obtain SnO2 nanoparticles, and then disperse them in deionized water to obtain SnO2 aqueous dispersion.

[0074] The above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications may be made based on the above descriptions. It is not necessary and impossible to enumerate all implementation methods here, and obvious variations or modifications derived therefrom remain within the scope of protection of the present invention.

Claims

1. A method for preparing alcohol-soluble SnO2, characterized in that: include: S1. At 20-30 ° C, the tin salt is mixed with the first solvent to form a first reaction system, the ligand is mixed with the second solvent to form a second reaction system, the second reaction system is added dropwise to the first reaction system, and heated to 50-60 ° C under vacuum conditions to dissolve to obtain a transparent SnO2 reaction liquid precursor solution; S2. The SnO2 reaction liquid precursor solution was loaded into a hydrothermal reactor, set the temperature to 90-200 ℃, the reaction was 1-24h, to obtain SnO2 nanomaterial mother liquor; S3. The SnO2 nanomaterial mother liquor is mixed with a precipitant to form a precipitate, which is then dissolved with a good solvent, precipitated with a precipitant, and the SnO2 nanoparticles are separated by centrifugation and repeatedly washed to obtain pure SnO2 nanoparticles; S4. The SnO2 nanoparticles in S3 were dispersed with an organic alcohol, and a hydroxycarboxylic acid compound having a carbon chain number of 2-9 was added for ligand exchange. The reaction was carried out for 1-24 hours and purified to obtain alcohol-soluble SnO2 nanoparticles. S5. The SnO2 nanoparticles are dispersed in an organic alcohol solvent to obtain an alcohol-soluble SnO2 dispersion; The ligands in S1 are straight-chain organic amines with carbon chains of 6-12, organic acids, and organic amines with hydroxyl groups; The first solvent described in S1 refers to a solvent whose boiling point is lower than the reaction temperature of the system, and the second solvent refers to a solvent whose boiling point is higher than the reaction temperature of the system; The hydroxycarboxylic acid compound described in S4 has a carbon chain number of 2-9 and satisfies the following general formula: HO-R-COOH, wherein R is an alkyl group R- or an aromatic group Ar-.

2. The preparation method of alcohol-soluble SnO2 according to claim 1, wherein: In S1, the ratio of the tin salt to the ligand is 1:(0.1-10) based on the amount of substance.

3. The preparation method of alcohol-soluble SnO2 according to claim 1, characterized in that: The precipitant in S3 is one of methanol, ethanol, acetone and acetonitrile.

4. The preparation method of alcohol-soluble SnO2 according to claim 1, characterized in that: The good solvent in S3 is one of dichloromethane, chloroform, n-hexane, n-heptane, n-octane, toluene and xylene.

5. Alcohol-soluble SnO2 prepared by the preparation method according to any one of claims 1 to 4, characterized in that: Including SnO2 inorganic matter and organic ligands on the surface of SnO2 inorganic matter.

6. The alcohol-soluble SnO2 according to claim 5, characterized in that: The organic ligand is a hydroxycarboxylic acid compound with a carbon chain number of 2-9, and the weight of the organic ligand accounts for 3%-25% of the total.

7. The alcohol-soluble SnO2 according to claim 5, characterized in that: The alcohol-soluble SnO2 has a particle size of 3-10 nm and a band gap of 3.6-4.0 eV.

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