An oil-soluble zinc oxide dispersion, its preparation method and application

Abstract

The present invention belongs to the technical field of solar cells, and relates to an oil-soluble zinc oxide dispersion liquid, a preparation method and an application thereof. During the preparation, compounds of thiols and organophosphines are bonded with Zn element to form stable ligands, which can be dispersed in an oily dispersion medium. The free thiols and organophosphine compounds on the zinc oxide nanoparticles will coordinate with lead Pb on the perovskite, thereby achieving the purpose of passivating the perovskite and improving the performance and lifespan of the perovskite solar cell. The prepared zinc oxide dispersion liquid can be stably stored at room temperature for more than one year, and this characteristic provides great convenience for its wide application in industrial production. The present invention also expands its application potential in high-precision and high-efficiency manufacturing processes such as inkjet printing, ultrasonic spraying and slot coating, injecting new vitality into the development of the new energy material field.

Description

Technical Field

[0001] The present invention belongs to the technical field of solar cells, and relates to an oil-soluble zinc oxide dispersion liquid, a preparation method thereof, and an application thereof. Background Art

[0002] In a perovskite solar cell with a trans structure, a hole transport layer is provided on a transparent electrode, and then an optical absorption layer. The main advantage of this structure is that light first passes through the hole transport layer, which can make the battery have less hysteresis and a higher fill factor, and the deposition of the electron transport layer does not affect the perovskite layer.

[0003] As a commonly used electron transport layer material in perovskite solar cells, zinc oxide has the advantages of being inexpensive, stable, and easy to prepare. However, conventional zinc oxide nanomaterials are dispersed in an ethanol solution, and ethanol will dissociate perovskite crystals; moreover, the ZnO dispersion liquid is alkaline, and alkaline substances will also damage perovskite crystals, which limits its use in trans devices. Therefore, in order to prepare a zinc oxide dispersion liquid that does not damage the perovskite layer, a solvent that can effectively disperse zinc oxide and does not cause perovskite dissociation needs to be selected. The selected solvent should avoid strong polarity to prevent the perovskite structure from being damaged, and at the same time ensure that zinc oxide is evenly distributed in the dispersion liquid. Experiments have found that methanol and ethanol will dissociate perovskite due to their high polarity, while low-polarity oily solvents have less damage to perovskite. Therefore, it is particularly important to study oil-soluble zinc oxide dispersion liquids. Summary of the Invention

[0004] The purpose of the present invention is to provide an oil-soluble zinc oxide dispersion liquid, a preparation method thereof, and an application thereof, so as to solve the problem that conventional zinc oxide nanomaterials are limited in application in trans devices in the prior art.

[0005] The technical solution of the present invention is as follows:

[0006] A preparation method of an oil-soluble zinc oxide dispersion liquid includes the following steps:

[0007] S1. Dissolve a zinc salt and a metal dopant in a first organic solvent to form a transparent first reaction system;

[0008] S2. At an environment temperature of 10 - 30°C, dissolve an alkali and a particle size regulator in a second organic solvent to prepare an alkali solution with a specified concentration, and obtain a second reaction system;

[0009] S3. At a temperature of 20 - 60°C, uniformly drop the second reaction system into the first reaction system, and after reacting for 0.2 - 24 h, obtain a zinc oxide nanoparticle mother liquor;

[0010] S4. Add ethyl acetate to the above system to precipitate and obtain zinc oxide nanomaterials;

[0011] S5. Dissolve the zinc oxide nanomaterials obtained in S4 in a second organic solution, add a ligand exchanger of a thiol compound or an organic phosphine compound with 2-12 carbon atoms in the carbon chain, react for 0.1-24 h, add a third organic solvent to precipitate, and the precipitate is the zinc oxide nanoparticles after ligand exchange;

[0012] S6. Disperse the zinc oxide nanoparticles after ligand exchange in a fourth organic solvent to obtain an oil-soluble zinc oxide dispersion.

[0013] Further, the metal dopant in S1 is one or more of lithium salt, magnesium salt, aluminum salt, tin salt, silver salt, zirconium salt; the first organic solvent is one of DMF (dimethylformamide), DMAc (dimethylacetamide), DMSO (dimethyl sulfoxide), NMP (N-methylpyrrolidone), THF (tetrahydrofuran), ethylene glycol monomethyl ether.

[0014] Further, the particle size regulator in S2 is a straight-chain alkanolamine with 2-4 carbon atoms in the carbon chain or one of PEG200, PEG400, PEG600; the second organic solvent is one of methanol, ethanol or ethylene glycol monomethyl ether.

[0015] Further, in terms of molar amount, the ratio of the zinc salt to the base is 1:(1.0-1.8).

[0016] Further, the third organic solvent in S5 is one of acetonitrile and acetone.

[0017] The oil-soluble zinc oxide dispersion prepared by any of the above preparation methods includes zinc oxide inorganic substances, organic ligands on the surface of the zinc oxide inorganic substances, and an oily dispersion.

[0018] Further, the size of the zinc oxide nanoparticles is 3-5 nm, and the band gap is 3.2-3.4 eV.

[0019] Further, the organic ligand is one or more of thiol compounds with 2-12 carbon atoms in the carbon chain, one or more of alkyl phosphines and organic phosphonic acids in organic phosphine compounds, and the total ligand content accounts for 5%-30% of the total weight of the entire nanomaterial.

[0020] Further, the dispersion is one or more of dichloromethane, chloroform, carbon tetrachloride, benzene, toluene, xylene, chlorobenzene, n-pentane, n-hexane, n-heptane, n-octane, isooctane, white oil, liquid paraffin.

[0021] Application of the above-mentioned oil-soluble zinc oxide dispersion as an electron transport layer material for perovskite solar cells.

[0022] The beneficial effects of the present invention are as follows:

[0023] The zinc oxide dispersion prepared by the present invention can successfully construct a uniform electron transport layer on the perovskite film, avoiding the interference of alcohols such as methanol and ethanol to the perovskite structure, thereby greatly improving the photoelectric conversion efficiency and long-term stability of the perovskite solar cell. Secondly, the dispersion can be stably stored at room temperature for more than one year, which provides great convenience for its wide application in industrial production. Finally, due to the excellent dispersion performance of zinc oxide nanomaterials, the present invention also expands its application potential in high-precision and high-efficiency manufacturing processes such as inkjet printing, ultrasonic spraying, and slot coating.

[0024] The particle size of the zinc oxide nanomaterial prepared by the present invention is controlled within 3-5 nm, acting as an electron transport layer material on the perovskite solar cell to meet the requirements of better film flatness, fewer film surface defects, and reduced charge accumulation at the film surface tips; compounds such as thiols and organophosphorus compounds can bond with Zn elements to form stable ligands, and this ligand can be dispersed in an oily dispersion medium; the free thiol compounds and organophosphorus compounds on the ZnO nanoparticles will coordinate with lead (Pb) on the perovskite, thereby achieving the purpose of passivating the perovskite and improving the performance and lifespan of the perovskite solar cell. Brief Description of the Drawings

[0025] Figure 1 It is a schematic diagram of zinc oxide nanoparticles.

[0026] Figure 2 It is a schematic diagram of the coordination of perovskite and thiol and organophosphorus on the surface of zinc oxide nanoparticles of the present invention.

[0027] Figure 3 It is a TEM image of the zinc oxide nanoparticles prepared by the present invention.

[0028] Figure 4 It is an XRD pattern of the zinc oxide nanoparticles prepared by the present invention.

[0029] Figure 5 It is an ultraviolet-visible absorption spectrum of the zinc oxide nanoparticles prepared by the present invention.

[0030] Figure 6 It is a thermogravimetric analysis chart of the zinc oxide nanoparticles prepared by the present invention. Detailed Description of the Invention

[0031] The present invention will be described in detail below with reference to the drawings and specific embodiments.

[0032] A preparation method of an oil-soluble zinc oxide dispersion includes the following steps:

[0033] S1. Dissolve a zinc salt and a metal dopant in a first organic solvent to form a transparent first reaction system;

[0034] In an environment of 2.10 - 30 °C, dissolve an alkali and a particle size regulator in a second organic solvent to prepare an alkali solution with a specified concentration, obtaining a second reaction system;

[0035] At a temperature of 20 - 60 °C, slowly add the second reaction system drop by drop to the first reaction system. After reacting for 0.2 - 24 h, obtain a mother liquor of zinc oxide nanoparticles;

[0036] Add ethyl acetate to the above system for precipitation to obtain zinc oxide nanomaterials;

[0037] Dissolve the zinc oxide nanomaterials obtained in S4 in a second organic solution, add a straight-chain alkane containing a mercapto group or an organic phosphorus ligand exchanger thereto, react for 0.1 - 24 h, and add a third organic solvent for precipitation. The precipitate is zinc oxide nanoparticles after ligand exchange;

[0038] Disperse the zinc oxide nanoparticles after ligand exchange in a fourth organic solvent to obtain an oil-soluble zinc oxide dispersion.

[0039] The zinc salt described in S1 can be selected from but not limited to zinc nitrate and its hydrates, zinc stearate, zinc acetate and its hydrates, zinc isopropoxide, zinc fluoride, zinc chloride, zinc bromide, zinc oxalate and its hydrates, zinc sulfate and its hydrates, zinc phosphate and its hydrates, zinc acetylacetonate, zinc oxide.

[0040] The alkali described in S2 can be selected from but not limited to KOH, NaOH, LiOH, tetramethylammonium hydroxide, tetraethylammonium hydroxide, ammonia water;

[0041] The particle size regulator described in S2 can be selected from but not limited to straight-chain alkanolamines with a carbon chain number of 2 - 4, such as ethanolamine, n-propanolamine, n-butanolamine; and PEG200, PEG400, PEG600, PEG800, PEG1000.

[0042] The ligand exchanger described in S5 is a straight-chain alkane containing a mercapto group, which can be selected from but not limited to n-hexanethiol, n-heptanethiol, n-octanethiol, n-nonanethiol, n-decanethiol, n-undecanethiol, dodecanethiol, n-tetradecanethiol, n-hexadecanethiol, n-octadecanethiol, preferably: n-hexanethiol, n-octanethiol, dodecanethiol;

[0043] The ligand exchanger described in S5 can also be alkyl phosphines and organic phosphonic acids in organic phosphorus compounds; alkyl phosphines such as: trioctylphosphine, triphenylphosphine, tributylphosphine; organic phosphonic acids such as: aminomethylphosphonic acid, phenylethylphosphonic acid, ethylphosphonic acid, hexylphosphonic acid, octylphosphonic acid, etc.

[0044] The ZnO nanomaterials in this application are not limited to this. By selecting different metal dopants in S1, zinc oxide nanomaterials doped with corresponding metals can be obtained, as follows:

[0045] Al-doped ZnO: such as Al:ZnO (where the molar doping amount of Al is 1%-5%; preferably 1%, 2%, 5%);

[0046] Mg-doped ZnO: such as Mg:ZnO (where the molar doping amount of Mg is 1-20%; preferably 1%, 5%, 10%, 15%, 20%);

[0047] Li-doped ZnO: such as Li:ZnO (where the molar doping amount of Li is 1%-6%; preferably 1%, 2%, 4%, 6%);

[0048] Ag-doped ZnO: such as Ag:ZnO (where the molar doping amount of Ag is 1%-4%; preferably 1%, 2%, 4%);

[0049] Zr-doped ZnO: such as Zr:ZnO (where the molar doping amount of Zr is 1%-3%; preferably 1%, 2%, 3%);

[0050] The present invention also provides an oily zinc oxide dispersion, which is prepared according to the above method. The zinc oxide dispersion comprises zinc oxide inorganic substances, organic ligands on the surface of zinc oxide, and an oily dispersion. After calculation, its band gap range is 3.2 eV - 3.4 eV. The calculation method is well-known to those skilled in the art. For example, it can be calculated by the Tauc Plot method, which will not be elaborated here.

[0051] According to another aspect of the present invention, a perovskite solar cell is provided, comprising an anode, a hole transport layer, a light absorption layer, an electron transport layer, and a cathode, wherein the electron transport layer is prepared by one of spin coating, printing, spraying, and blade coating with the above zinc oxide nano-dispersion.

[0052] Example 1

[0053] S1. Dissolve 1 mmol of zinc acetate dihydrate in 100 ml of DMSO, stir well to form a transparent first reaction system;

[0054] S2. At room temperature, dissolve 1.5 mmol of tetramethylammonium hydroxide pentahydrate and 2 mmol of ethanolamine in 200 ml of ethanol to obtain a second reaction system;

[0055] S3. At 50 °C, add the second reaction system dropwise to the first reaction system at a rate of 200 ml / h, and react for 4 h to obtain a mother liquor of zinc oxide nanoparticles;

[0056] S4. Add ethyl acetate to the above system, precipitate to obtain zinc oxide nanomaterials;

[0057] S5. Dissolve the zinc oxide nanomaterials obtained in S4 in 50 ml of ethanol, add 1 mmol of n-octanethiol and 0.5 mmol of aminomethylphosphonic acid thereto, react for 0.5 h, continue to add 200 ml of ethanol, then add 100 ml of acetonitrile, and centrifuge to obtain ligand-exchanged zinc oxide nanoparticles;

[0058] S6. The ligand-exchanged zinc oxide nanoparticles can be dispersed in n-hexane to prepare a n-hexane spin coating solution with a concentration of 25 mg / ml, that is, the ZnO oil-based dispersion liquid described in the present application is obtained;

[0059] Example 2

[0060] S1. Dissolve 1 mmol of zinc isopropoxide in 100 ml of DMF, stir well to form a transparent first reaction system;

[0061] S2. At room temperature, dissolve 1.5 mmol of KOH and 1 mmol of n-propanolamine in 200 ml of ethylene glycol monomethyl ether to obtain a second reaction system;

[0062] S3. At 30 °C, add the second reaction system dropwise to the first reaction system at a rate of 200 ml / h, and react for 6 h to obtain a mother liquor of zinc oxide nanoparticles;

[0063] S4. Add ethyl acetate to the above system, precipitate to obtain zinc oxide nanomaterials;

[0064] S5. Dissolve the zinc oxide nanomaterials obtained in S4 in 50 ml of ethylene glycol monomethyl ether, add 1 mmol of dodecanethiol and 0.2 mmol of trioctylphosphine thereto, react for 1 h, continue to add 200 ml of ethylene glycol monomethyl ether, then add 100 ml of acetone, and centrifuge to obtain ligand-exchanged zinc oxide nanoparticles;

[0065] S6. The ligand-exchanged zinc oxide nanoparticles can be dispersed in n-octane to prepare a n-octane spin coating solution with a concentration of 25 mg / ml, that is, the ZnO oil-based dispersion liquid described in the present application is obtained;

[0066] Example 3

[0067] S1. Dissolve 1 mmol of zinc acetate dihydrate and 0.2 mmol of aluminum isopropoxide in 100 ml of DMSO, stir well to form a transparent first reaction system;

[0068] S2. At room temperature, dissolve 1.5 mmol of tetramethylammonium hydroxide pentahydrate and 0.2 mmol of PEG400 in 200 ml of ethanol to obtain a second reaction system;

[0069] S3. At 40 °C, the second reaction system was added dropwise to the first reaction system at a rate of 200 ml / h. After reacting for 2 h, a mother liquor of aluminum-doped zinc oxide nanoparticles was obtained;

[0070] S4. Ethyl acetate was added to the above system for precipitation to obtain aluminum-doped zinc oxide nanomaterials;

[0071] S5. The aluminum-doped zinc oxide nanomaterials obtained in S4 were dissolved in 50 ml of ethanol. 1 mmol of ethanethiol and ethylphosphonic acid were added thereto, and the mixture was reacted for 0.5 h. Then, 200 ml of ethanol was continuously added, and 100 ml of acetonitrile was further added. After centrifugation, aluminum-doped zinc oxide nanoparticles after ligand exchange were obtained;

[0072] S6. The aluminum-doped zinc oxide nanoparticles after ligand exchange can be dispersed in n-octane to prepare an n-octane spin coating solution with a concentration of 25 mg / ml, that is, the oil-based aluminum-doped zinc oxide dispersion liquid described in the present application is obtained;

[0073] Example 4

[0074] S1. 1 mmol of nanomaterials with the structure of Mg:ZnO (5 mol% Mg) was ultrasonically dispersed in 50 ml of ethylene glycol methyl ether. 1 mmol of n-octanethiol and 0.6 mmol of octylphosphonic acid were added thereto, and the mixture was stirred and reacted for 2 h. Then, 100 ml of ethylene glycol methyl ether was continuously added, and 100 ml of acetone was further added. After centrifugation, magnesium-doped zinc oxide nanoparticles after ligand exchange were obtained;

[0075] S2. The zinc oxide nanoparticles after ligand exchange can be dispersed in chlorobenzene to prepare a chlorobenzene spin coating solution with a concentration of 25 mg / ml, that is, the Mg:ZnO chlorobenzene dispersion liquid described in the present application is obtained;

[0076] Example 5

[0077] This example provides a device of a perovskite solar cell for an inverter. Its manufacturing method includes the following steps: A layer of NiOx nanomaterials was spin-coated on the IT0 anode layer and then annealed at 150 °C for 30 min to form a hole transport layer; A perovskite solution was spin-coated on the hole transport layer as a bearing part to form an absorption layer; The organic dispersion liquid of ZnO in the example was spin-coated on the absorption layer, annealed at 80 °C, and dried to form an electron transport layer; Finally, an Au cathode electrode layer was evaporated and encapsulated to form a perovskite solar cell device, and the device performance structure is as described in Table 1.

[0078] Comparative Example 1

[0079] S1. 1 mmol of zinc acetate dihydrate was dissolved in 100 ml of ethanol and stirred evenly to form a first reaction system;

[0080] S2. At room temperature, dissolve 1.5 mmol of KOH in 200 ml of ethanol to obtain a second reaction system;

[0081] S3. At 50 °C, add the second reaction system dropwise to the first reaction system at a rate of 200 ml / h. After reacting for 4 h, obtain a mother liquor of zinc oxide nanoparticles;

[0082] S4. Add ethyl acetate to the above system to precipitate and obtain zinc oxide nanomaterials;

[0083] S5. Add an ethanol solution to the zinc oxide nanomaterials to prepare an ethanol spin coating solution with a concentration of 25 mg / ml, thereby obtaining the ZnO ethanol dispersion of the present application;

[0084]

[0085]

[0086] The above embodiments are merely examples given for clear illustration and are not intended to limit the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. The obvious changes or modifications derived therefrom still fall within the protection scope of the present invention.

Claims

1. A method for preparing an oil-soluble zinc oxide dispersion, characterized in that, It includes the following steps: S1. Dissolve zinc salt and metal dopant in the first organic solvent to form a transparent first reaction system; S2. At an environment of 10 - 30 °C, dissolve alkali and particle size regulator in the second organic solvent to prepare an alkali solution with a specified concentration, obtaining a second reaction system; S3. At a temperature of 20 - 60 °C, slowly add the second reaction system to the first reaction system at a uniform speed. After reacting for 0.2 - 24 h, obtain a mother liquor of zinc oxide nanoparticles; S4. Add ethyl acetate to the above-mentioned mother liquor of zinc oxide nanoparticles for precipitation to obtain zinc oxide nanomaterials; S5. Dissolve the zinc oxide nanomaterials obtained in S4 in the second organic solution, and add a ligand exchanger of thiol compound with 2 - 12 carbon atoms and organic phosphine compound. React for 0.1 - 24 h, and add the third organic solvent for precipitation. The precipitate is zinc oxide nanoparticles after ligand exchange; S6. Disperse the zinc oxide nanoparticles after ligand exchange in the fourth organic solvent to obtain an oil-soluble zinc oxide dispersion; The particle size regulator described in S2 is a straight-chain alkanolamine with 2 - 4 carbon atoms or one of PEG200, PEG400, and PEG600. The second organic solvent is one of methanol, ethanol, or ethylene glycol monomethyl ether; The prepared zinc oxide nanoparticles have a size of 3 - 5 nm and a band gap of 3.2 - 3.4 eV; The fourth organic solvent described in S6 is one or more of dichloromethane, chloroform, carbon tetrachloride, benzene, toluene, xylene, chlorobenzene, n-pentane, n-hexane, n-heptane, n-octane, isooctane, white oil, and liquid paraffin; 2. The preparation method of the oil-soluble zinc oxide dispersion according to claim 1, characterized in that: The metal dopant described in S1 is one or more of lithium salt, magnesium salt, aluminum salt, tin salt, silver salt, and zirconium salt; the first organic solvent is one of DMF (dimethylformamide), DMAc (dimethylacetamide), DMSO (dimethyl sulfoxide), NMP (N-methylpyrrolidone), THF (tetrahydrofuran), and ethylene glycol monomethyl ether; 3. The preparation method of the oil-soluble zinc oxide dispersion according to claim 1, wherein: In terms of the amount of substance, the ratio of the zinc salt to the alkali is 1:(1.0 - 1.8).

4. The preparation method of the oil-soluble zinc oxide dispersion according to claim 1, wherein: The third organic solvent described in S5 is one of acetonitrile and acetone; 5. The oil-soluble zinc oxide dispersion prepared by the preparation method according to any one of claims 1 - 4, including zinc oxide inorganic substances, organic ligands on the surface of zinc oxide inorganic substances, and an oily dispersion; 6. The oil-soluble zinc oxide dispersion according to claim 5, wherein: The organic ligands are one or more of thiol compounds with 2 - 12 carbon atoms, and one or more of alkyl phosphines and organic phosphonic acids in organic phosphine compounds. The total ligand content accounts for 5% - 30% of the total weight of the entire nanomaterial; 7. Application of the oil-soluble zinc oxide dispersion according to claim 6 as an electron transport layer material for perovskite solar cells.

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