Perovskite solar cell based on diamine molten salt surface modification and preparation method thereof

Abstract

The invention discloses a perovskite solar cell based on diamine molten salt surface modification and a preparation method thereof, and the perovskite solar cell comprises a transparent conductive substrate layer, a hole transport layer, a perovskite light absorption layer, a surface modification layer, an electron transport layer, an interface buffer layer and an electrode layer from bottom to top. Or a transparent conductive substrate layer, an interface buffer layer, a surface modification layer, a perovskite light absorption layer, a hole transport layer and an electrode layer, wherein the surface modification layer is diamine molten salt. According to the invention, the surface of the perovskite cell is modified by using diamine molten salt, and by inducing a gradient energy band structure and ordered arrangement of molecules, optimizing charge transfer and realizing interface energy band alignment, compact stacking of a perovskite film is promoted, grain boundary defects are reduced, and the surface roughness is reduced; the light capture capability and the charge carrier mobility of the perovskite thin film are remarkably improved, and a new thought is provided for the development of a high-efficiency and high-stability perovskite solar cell.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cells, and in particular to a perovskite solar cell based on surface modification of a diamine molten salt and a preparation method thereof. Background Art

[0002] Among the emerging photovoltaic technologies, perovskite solar cells have received great attention in recent years. Thanks to the excellent optoelectronic properties of organic-inorganic hybrid perovskite materials (including highly adjustable band gap, long carrier lifetime, low exciton binding energy and high carrier mobility), laboratory-prepared perovskite cells have achieved a certified power conversion efficiency of 26.7%. Despite the remarkable performance of perovskite cells, their instability and degradation mechanisms are still unclear, hindering the commercialization of perovskite photovoltaic technology. The grain boundaries formed during the film formation process of perovskite films will become the main channels for ion migration, and surface dangling bond defects will increase non-radiative recombination losses, shorten carrier lifetimes, and make perovskite films susceptible to corrosion by moisture and oxygen in the air, resulting in low efficiency, poor stability and hysteresis effects in perovskite cells. In addition, interface defects and imperfect energy level alignment in perovskite cells will inevitably lead to severe non-radiative recombination and open-circuit voltage losses, which will also have an adverse effect on the performance of perovskite cells. Therefore, it is particularly important to prepare high-quality perovskite films with no pinholes and low defects, and to construct interfaces with aligned energy levels, high charge transfer efficiency, and stability and reliability. Summary of the invention

[0003] The object of the present invention is to provide a perovskite solar cell and a preparation method based on the surface modification of a diamine molten salt in view of the deficiencies in the prior art, wherein a diamine molten salt surface modification layer is inserted between the perovskite light absorption layer / electron transport layer or the interface buffer layer / perovskite light absorption layer, and on the one hand, the diamine molten salt can construct a gradient energy band structure. The diamine ions in the diamine molten salt induce the perovskite light absorption layer at the interface to be converted into a low-dimensional perovskite, eliminate the energy loss of the interface charge transfer, improve the charge transfer efficiency, and thus improve the efficiency of the perovskite battery. On the other hand, the diamine molten salt can achieve a bilateral passivation effect. The -COOH in the diamine molten salt can form an anchoring effect with the electron transport layer or the interface buffer layer, and can also strongly interact with the lead of the perovskite, enhance the interface bonding ability, improve the crystallinity of the perovskite, passivate the interface defects, and significantly improve the stability of the perovskite battery.

[0004] To achieve the above-mentioned purpose, the technical scheme adopted by the present invention is: as a first aspect, a perovskite solar cell based on the surface modification of a diamine molten salt, wherein the perovskite solar cell comprises, from bottom to top, a transparent conductive substrate layer, a hole transport layer, a perovskite light absorption layer, a surface modification layer, an electron transport layer, an interface buffer layer and an electrode layer, or a transparent conductive substrate layer, an interface buffer layer, a surface modification layer, a perovskite light absorption layer, a hole transport layer and an electrode layer, wherein the surface modification layer is a diamine molten salt.

[0005] As a second aspect, the present invention also provides a method for preparing a perovskite solar cell based on surface modification of a diamine molten salt, the method for preparing a perovskite solar cell comprising the following steps:

[0006] (1) depositing a hole transport layer on the transparent conductive substrate layer;

[0007] (2) Weighing perovskite powder and dissolving it in an organic solvent, stirring and clarifying it to form a perovskite precursor solution. Coating or printing the perovskite precursor solution on a substrate covered with a hole transport layer, and obtaining a perovskite light absorbing layer after heat treatment;

[0008] (3) Weighing a diamine molten salt and dissolving it in an organic solvent, stirring and clarifying to form a diamine molten salt solution. Coating or printing the diamine molten salt solution on a substrate covered with a perovskite light absorbing layer, and obtaining a surface modification layer after heat treatment;

[0009] (4) An electron transport layer, an interface buffer layer and an electrode layer are sequentially deposited on the surface modification layer to obtain an inverse perovskite solar cell based on diamine molten salt interface modification.

[0010] or

[0011] (1) depositing an interface buffer layer on a clean transparent conductive substrate layer;

[0012] (2) Weighing a diamine molten salt and dissolving it in an organic solvent, stirring and clarifying to form a diamine molten salt solution. Coating or printing the diamine molten salt solution on a substrate covered with an interface buffer layer, and obtaining a surface modification layer after heat treatment;

[0013] (3) Weighing perovskite powder and dissolving it in an organic solvent, stirring and clarifying it to form a perovskite precursor solution. Coating or printing the perovskite precursor solution on a substrate covered with a surface modification layer, and obtaining a perovskite light absorbing layer after heat treatment;

[0014] (4) A hole transport layer and an electrode layer are sequentially deposited on the perovskite light-absorbing layer to obtain a formal perovskite solar cell based on diamine molten salt interface modification.

[0015] Furthermore, the general structural formula of the perovskite is ABX 3, where A is selected from Rb + , Cs + 、MA + , FA + , B is selected from Pb 2+ Sn 2+ ,Ge 2+ , X is selected from I - Br - , Cl - .

[0016] Furthermore, the heat treatment temperature of the perovskite light absorbing layer is 30 to 300° C., and the time is 5 to 120 minutes.

[0017] Furthermore, the transparent conductive substrate layer is selected from: FTO glass, ITO glass, ITO / PET, ITO / PEN, ITO / PI; the hole transport layer is nickel oxide and doped nickel oxide, PTAA, Spiro-OMeTAD, Me-4PACz, 2PACz, MeO-2PACz, P3HT; the electron transport layer is fullerene and its derivatives, including: C60, C70, PC60M; the interface buffer layer is selected from: bathocuproin, tin oxide, zinc oxide, yttrium oxide, cerium oxide, titanium oxide, niobium oxide; the electrode layer is selected from: Cu, Ag, Au, Mo, Bi, ITO, IZO, AZO, IWO, ICO.

[0018] Furthermore, the thickness of the perovskite light absorption layer is 100 to 2000 nm; the thickness of the surface modification layer is 1 to 80 nm; the thickness of the electron transport layer is 1 to 100 nm; the thickness of the interface buffer layer is 1 to 100 nm; and the thickness of the electrode layer is 10 to 10000 nm.

[0019] Furthermore, the electron transport layer is deposited by evaporation; the interface buffer layer is deposited by coating, printing, evaporation, sputtering, reactive plasma deposition, chemical vapor deposition, coating, and printing; the electrode layer is deposited by evaporation, sputtering, chemical vapor deposition, coating, and printing.

[0020] Further, the concentration of the perovskite precursor solution is 0.1-3 mol / L; the concentration of the diamine molten salt is 0.001-50 mg / mL; preferably, the concentration of the perovskite precursor solution is 1.55 mol / L; the concentration of the diamine molten salt is 2.1 mg / mL;

[0021] Furthermore, the organic solvent used to prepare the perovskite precursor solution is N, N-dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone, 1,3-methyl-3,4,5,6-tetrahydro-2 (1H) -pyrimidinone, 2-methoxyethanol, and acetonitrile, mixed in any proportion; preferably, the organic solvent used to prepare the perovskite precursor solution is acetonitrile, N, N-dimethylformamide and 1,3-methyl-3,4,5,6-tetrahydro-2 (1H) -pyrimidinone mixed in a volume ratio of 3:6.3:0.7; the organic solvent used to prepare the diamine molten salt solution is isopropanol, chlorobenzene, ethyl acetate, butanol, chloroform, benzene, acetonitrile, One or more of dichloroethane are mixed in any proportion; preferably, the organic solvent used to prepare the diamine molten salt solution is chloroform and ethyl acetate mixed in a volume ratio of 9.5:0.5.

[0022] Further, the general structural formula of the diamine molten salt is M·N, wherein M is a diamine compound, including methylenediamine, ethylenediamine, propylenediamine, butylenediamine, 1,4-phenylenediamine, 2,5-thiophenedicarboxamidine, 3,4-thiophenedicarboxamidine, 2,2'-oxybis(ethylamine), 2,2'-thiobis(ethylamine), 3,3'-thiobis(propylamine), 3,3'-thiobis(propylamine), 2,2'-thiobis(acetamidine), 3,3'-thiobis(propionamidine), terephthalamidine, pyridine-3,5-diamine, pyridine-2,6-diamine, pyridine -2,6-dicarboxamidine, pyridine-3,5-dicarboxamidine, 2,5-thiophene dimethylamine, 3,4-thiophene dimethylamine, 4,5-diaminopyridazine, pyrazine-2,5-diamine, 2,6-diaminopyrazine, terephthalamidine, malonamide, 4,4'-diamino-2,2'-bipyridine, 4,5-dicarboxamidinopyridazine, malonamide, 1,3-phenyldiacetamidine, 1,2-phenyldiacetamidine, 4,4-bipiperidine, 1,3-di-4-piperidinylpropane, 1,2-bipiperidinylethane, 2,2-bithiophene-5,5-dimethylamine, bipiperidinylmethane, 4 ,4'-bipiperidine, 1,3-bis(4-pyridyl)propane, 4,4'-diaminodiphenyl sulfide, 4,4'-bipyridine sulfide, 1,4-phenylenediamine, succinic acid dihydrazide, maleic acid dihydrazide, oxalyl dihydrazide, isophthalic acid dihydrazide, carbohydrazide, N is a nitrogen- or sulfur-containing acid compound, including thiazole-4,5-dicarboxylic acid, 2,6-pyridinedicarboxylic acid, 3,5-pyridinedicarboxylic acid, 3,4-thiophenedicarboxylic acid, thiophene-2,5-dicarboxylic acid, 2,2'-bipyridine-6,6'-dicarboxylic acid, 3,3'-thiodipropionic acid, 3, 3'-dithiodipropionic acid, 3,4-pyrroledicarboxylic acid, dithioglycolic acid, methylenebis(thioglycolic acid), 2,2'-thiodiacetic acid, 2,2'-bipyridine-4,4'-dicarboxylic acid, 2,2'-bipyridine-3,3'-dicarboxylic acid, pyrazine-2,3-dicarboxylic acid, 2,2-bithiophene-5,5-dicarboxylic acid, pyrazine-2,6-dicarboxylic acid, imidazole-4,5-dicarboxylic acid, 3,5-pyrazoledicarboxylic acid, pyridazine-4,5-dicarboxylic acid, pyridazine-3,6-dicarboxylic acid, pyrimidine-4,6-dicarboxylic acid, 2,5-pyrimidinedicarboxylic acid. 2,2'-thiobis(acetamidine)·2,2'-thiodiacetic acid is preferred.

[0023] The beneficial effects of the present invention are:

[0024] 1. The diamine ions in the diamine molten salt surface modification layer used in the present invention can induce the perovskite to form a gradient energy band structure, achieving a more uniform surface energy distribution. The electronic interaction between SS atoms or NN atoms in the diamine molten salt molecules can also promote the regular and orderly arrangement of molecules, reduce the charge transfer barrier, and achieve interface energy band alignment.

[0025] 2. The diamine molten salt used in the present invention can assist the growth of perovskite film, regulate intercrystalline interconnection, fill the gaps between grain boundaries, induce the perovskite crystals to stack more closely, and achieve the effect of crystal cross-linking. The formation of large and vertically oriented electrically interconnected perovskite grains can eliminate large grain boundaries that are highly susceptible to moisture and oxygen, reduce the surface roughness of the perovskite film, enhance charge carriers and reduce charge recombination, thereby significantly improving the light capture ability of the perovskite film.

[0026] 3. The -COOH group in the diamine molten salt used in the present invention contains a carbonyl group with a lone pair of electrons in oxygen that can react with Pb in the perovskite. 2+ Sn 2+ Or Ge 2+ , forming a coordination effect, inhibiting ion migration, passivating potential defects of the perovskite film, and significantly reducing the tail energy value of the Urbach absorption band of the perovskite film. In addition, the -COOH group in the diamine molten salt can also produce an anchoring effect with the electron transport layer or the interface buffer layer, passivating the surface defects of the electron transport layer or the interface buffer layer, enhancing the interface adhesion, improving the interface mechanical reliability, reducing the interface charge transfer trap state, and improving the interface stability of the perovskite battery.

[0027] 3. The perovskite solar cell modified with diamine molten salt surface in the present invention can achieve high efficiency and high stability at the same time, has a simple deposition process, and can be used for large-scale batch preparation. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0029] Figure 1 This is a schematic diagram of the structure of an inverse perovskite solar cell based on surface modification of a diamine molten salt according to the present invention;

[0030] Figure 2 This is a schematic diagram of the structure of a formal perovskite solar cell based on surface modification of diamine molten salt according to the present invention;

[0031] Figure 3 This is a schematic diagram of the interface of the perovskite light absorbing layer / electron transport layer modified by molten salt in the present invention;

[0032] Figure 4 This is a schematic diagram of the interface buffer layer / perovskite light absorbing layer interface modified by molten salt in the present invention;

[0033] In the figure: transparent conductive substrate 1, hole transport layer 2, perovskite light absorption layer 3, surface modification layer 4, electron transport layer 5, interface buffer layer 6, electrode layer 7. DETAILED DESCRIPTION

[0034] The present invention is described in detail below in conjunction with the accompanying drawings. In the absence of conflict, the features of the following embodiments and implementations can be combined with each other.

[0035] The idea of ​​the present invention is to modify the interface of the perovskite light-absorbing layer / electron transport layer or the interface buffer layer / perovskite light-absorbing layer using a diamine molten salt. On the one hand, the diamine molten salt can construct a gradient band structure. The diamine ions in the diamine molten salt induce the perovskite light-absorbing layer at the interface to be converted into a low-dimensional perovskite, eliminate the energy loss of the interfacial charge transfer, improve the charge transfer efficiency, and thus improve the efficiency of the perovskite battery. On the other hand, the diamine molten salt can achieve a bilateral passivation effect. The -COOH in the diamine molten salt can form an anchoring effect with the electron transport layer or the interfacial buffer layer, and can also interact strongly with the lead of the perovskite, enhance the interfacial bonding ability, improve the crystallinity of the perovskite, passivate the interface defects, and significantly improve the stability of the perovskite battery.

[0036] The present invention discloses a perovskite solar cell based on the surface modification of a diamine molten salt, wherein the perovskite solar cell comprises, from bottom to top, a transparent conductive substrate layer, a hole transport layer, a perovskite light absorption layer, a surface modification layer, an electron transport layer, an interface buffer layer and an electrode layer; or a transparent conductive substrate layer, an interface buffer layer, a surface modification layer, a perovskite light absorption layer, a hole transport layer and an electrode layer, wherein the surface modification layer is a diamine molten salt.

[0037] The general structural formula of the diamine molten salt is M·N, wherein M is a diamine compound, including methylenediamine, ethylenediamine, propylenediamine, butylenediamine, 1,4-phenylenediamine, 2,5-thiophenedicarboxamidine, 3,4-thiophenedicarboxamidine, 2,2'-oxybis(ethylamine), 2,2'-thiobis(ethylamine), 3,3'-thiobis(propylamine), 3,3'-thiobis(propylamine), 4,5-dicarboxamidinopyridazine, 2,2'-thiobis(ethylamidine), 3,3'-thiobis(propionamidine), terephthalamidine, pyridine-3,5-diamine, pyridine- 2,6-diamine, pyridine-2,6-dicarboxamidine, pyridine-3,5-dicarboxamidine, 2,5-thiophene dimethylamine, 3,4-thiophene dimethylamine, 4,5-diaminopyridazine, pyrazine-2,5-diamine, 2,6-diaminopyrazine, terephthalamidine, malonic acid amidine, malonic acid amidine, 4,4'-diamino-2,2'-bipyridine, 1,3-phenylenediacetamidine, 2,2-bithiophene-5,5-dimethylamine, 1,2-phenylenediacetamidine, 4,4-bipiperidine, 1,3-di-4-piperidinylpropane, 1,2-dipiperidinylethane, dipiperidinylmethane, 4, 4'-Bipiperidine, 1,3-bis(4-pyridyl)propane, 4,4'-diaminodiphenyl sulfide, 4,4'-bipyridine sulfide, 1,4-phenylenediamine, succinic acid dihydrazide, maleic acid dihydrazide, oxalyl dihydrazide, isophthalic acid dihydrazide, carbohydrazide, acid compounds wherein N is nitrogen- or sulfur-containing, including thiazole-4,5-dicarboxylic acid, 2,6-pyridinedicarboxylic acid, 3,5-pyridinedicarboxylic acid, 3,4-thiophenedicarboxylic acid, thiophene-2,5-dicarboxylic acid, 2,2'-bipyridine-6,6'-dicarboxylic acid, 3,3'-thiodipropionic acid, 3,3 '-dithiodipropionic acid, 3,4-pyrroledicarboxylic acid, dithioglycolic acid, methylenebis(thioglycolic acid), 2,2'-thiodiacetic acid, 2,2'-bipyridine-4,4'-dicarboxylic acid, 2,2'-bipyridine-3,3'-dicarboxylic acid, pyrazine-2,3-dicarboxylic acid, 2,2-bithiophene-5,5-dicarboxylic acid, pyrazine-2,6-dicarboxylic acid, imidazole-4,5-dicarboxylic acid, 3,5-pyrazoledicarboxylic acid, pyridazine-4,5-dicarboxylic acid, pyridazine-3,6-dicarboxylic acid, pyrimidine-4,6-dicarboxylic acid, 2,5-pyrimidinedicarboxylic acid. 2,2'-thiobis(acetamidine)·2,2'-thiodiacetic acid is preferred.

[0038] The present invention also provides a method for preparing a perovskite solar cell based on the surface modification of a diamine molten salt, characterized in that it comprises the following steps:

[0039] (1) depositing a hole transport layer on the transparent conductive substrate layer;

[0040] (2) Weighing perovskite powder and dissolving it in an organic solvent, stirring and clarifying it to form a perovskite precursor solution. Coating or printing the perovskite precursor solution on the hole transport layer, and obtaining a perovskite light absorbing layer after heat treatment;

[0041] (3) Weighing a diamine molten salt and dissolving it in an organic solvent, stirring and clarifying to form a diamine molten salt solution. Coating or printing the diamine molten salt solution on the perovskite light absorbing layer, and obtaining a surface modification layer after heat treatment;

[0042] (4) An electron transport layer, an interface buffer layer and an electrode layer are sequentially deposited on the surface modification layer to obtain an inverse perovskite solar cell based on diamine molten salt interface modification.

[0043] or

[0044] (1) depositing an interface buffer layer on the transparent conductive substrate layer;

[0045] (2) Weighing a diamine molten salt and dissolving it in an organic solvent, stirring and clarifying to form a diamine molten salt solution. Coating or printing the diamine molten salt solution on the interface buffer layer, and obtaining a surface modification layer after heat treatment;

[0046] (3) Weighing perovskite powder and dissolving it in an organic solvent, stirring and clarifying it to form a perovskite precursor solution. Coating or printing the perovskite precursor solution on the surface modification layer, and obtaining a perovskite light absorbing layer after heat treatment;

[0047] (4) A hole transport layer and an electrode layer are sequentially deposited on the perovskite light-absorbing layer to obtain a formal perovskite solar cell based on diamine molten salt interface modification.

[0048] Specifically, the heat treatment temperature of the perovskite light absorbing layer is any value between 30 and 300° C., and the heat treatment time is any value between 5 and 120 minutes.

[0049] Specifically, the transparent conductive substrate layer is FTO glass, ITO glass, ITO / PET, ITO / PEN or ITO / PI; the hole transport layer is nickel oxide and doped nickel oxide, PTAA, Spiro-OMeTAD, Me-4PACz, 2PACz, MeO-2PACz or P3HT; the electron transport layer is fullerene or its derivatives, including: C60, C70, PC60M; the interface buffer layer is bathocuproin, tin oxide, zinc oxide, yttrium oxide, cerium oxide, titanium oxide or niobium oxide; the electrode layer is Cu, Ag, Au, Mo, Bi, ITO, IZO, AZO, IWO or ICO.

[0050] Specifically, the thickness of the perovskite light absorption layer is any value between 100 and 2000 nm; the thickness of the surface modification layer is any value between 1 and 80 nm; the thickness of the electron transport layer is any value between 1 and 100 nm; the thickness of the interface buffer layer is any value between 1 and 100 nm; and the thickness of the electrode layer is any value between 10 and 10000 nm.

[0051] Specifically, the electron transport layer is deposited by evaporation; the interface buffer layer is deposited by coating, printing, evaporation, sputtering, reactive plasma deposition, chemical vapor deposition, coating, and printing; the electrode layer is deposited by evaporation, sputtering, chemical vapor deposition, coating, and printing.

[0052] Specifically, the organic solvent used to prepare the perovskite precursor solution is one or more of N,N-dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone, 1,3-methyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone, 2-methoxyethanol, and acetonitrile mixed in any proportion; the organic solvent used to prepare the diamine molten salt solution is one or more of isopropanol, chlorobenzene, ethyl acetate, butanol, chloroform, benzene, acetonitrile, and dichloroethane mixed in any proportion.

[0053] Embodiment 1:

[0054] like Figure 1 As shown, a trans-perovskite solar cell based on surface modification of diamine molten salt and a preparation method thereof, comprising the following steps:

[0055] Step 1: Synthesis of 2,2'-thiobis(acetamidine)·2,2'-thiodiacetic acid:

[0056] 146.21 mg (1 mmol) of 2,2'-thiobis(acetamidine) was weighed and dissolved in 13 mL of anhydrous ethanol. 150.15 mg (1 mmol) of 2,2'-thiodiacetic acid was weighed and dissolved in 5 mL of anhydrous ethanol. The 2,2'-thiodiacetic acid ethanol solution was slowly added dropwise to the continuously stirred 2,2'-thiobis(acetamidine) ethanol solution. The reaction temperature was kept at zero degrees during the reaction. After the addition was completed, stirring was continued for 30 minutes. The crude product of 2,2'-thiobis(acetamidine)·2,2'-thiodiacetic acid was obtained by rotary evaporation. Finally, the crude product was washed four times with ether in turn to obtain pure 2,2'-thiobis(acetamidine)·2,2'-thiodiacetic acid molten salt (229 mg, yield 77%), which was vacuum dried for 12 hours for later use.

[0057] Step 2: Preparation of a trans-perovskite solar cell based on surface modification of diamine molten salt:

[0058] (1) ultrasonically cleaning the FTO glass with a glass cleaning agent, ultrapure water, and alcohol in sequence, and drying after cleaning to obtain a clean FTO glass substrate;

[0059] (2) 0.5 mg / mL Me-4PACz ethanol solution was slit coated on a clean FTO glass substrate, and the coated Me-4PACz layer was heat treated at 100°C for 10 min to obtain a hole transport layer with a thickness of 2.7 nm;

[0060] (3) Weighing CsI, MAI, FAI, PbI 2 (molar ratio of 0.1:0.1:0.8:1.03) powder was dissolved in a mixed solvent of acetonitrile, N,N-dimethylformamide and 1,3-methyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone in a volume ratio of 3:6.3:0.7, and stirred to clarify to obtain a 1.55 mol / L perovskite precursor solution;

[0061] (3) Slit coating a perovskite precursor solution on the surface of the hole transport layer, and heat treating the coated perovskite wet film at 110° C. for 22 min to obtain a perovskite light absorbing layer with a thickness of 600 nm;

[0062] (4) weighing 2,2'-thiobis(acetamidine)·2,2'-thiodiacetic acid and dissolving it in a mixed solvent of chloroform and ethyl acetate in a volume ratio of 9.5:0.5, stirring and clarifying to obtain a 2.1 mg / mL diamine molten salt solution;

[0063] (5) slit coating a diamine molten salt solution on the surface of the perovskite light absorbing layer, and heat treating the coated diamine molten salt at 100° C. for 3 min to obtain a diamine molten salt surface modification layer with a thickness of 6.2 nm;

[0064] (6) A 15 nm thick C60 electron transport layer, a 15 nm thick tin oxide interface buffer layer, and a 300 nm thick IZO electrode layer are sequentially evaporated on the diamine molten salt surface modification layer, thereby obtaining an inverse perovskite solar cell based on the diamine molten salt surface modification.

[0065] Embodiment 2:

[0066] like Figure 2 As shown, a formal perovskite solar cell based on surface modification of diamine molten salt and a preparation method thereof, comprising the following steps:

[0067] Step 1: Synthesis of 2,2'-thiobis(acetamidine)·2,2'-thiodiacetic acid:

[0068] 146.21 mg (1 mmol) of 2,2'-thiobis(acetamidine) was weighed and dissolved in 13 mL of anhydrous ethanol. 150.15 mg (1 mmol) of 2,2'-thiodiacetic acid was weighed and dissolved in 5 mL of anhydrous ethanol. The 2,2'-thiodiacetic acid ethanol solution was slowly added dropwise to the continuously stirred 2,2'-thiobis(acetamidine) ethanol solution. The reaction temperature was kept at zero degrees during the reaction. After the addition was completed, stirring was continued for 30 minutes. The crude product of 2,2'-thiobis(acetamidine)·2,2'-thiodiacetic acid was obtained by rotary evaporation. Finally, the crude product was washed four times with ether in turn to obtain pure 2,2'-thiobis(acetamidine)·2,2'-thiodiacetic acid molten salt (229 mg, yield 77%), which was vacuum dried for 12 hours for later use.

[0069] Step 2: Preparation of a formal perovskite solar cell based on surface modification of diamine molten salt:

[0070] (1) ultrasonically cleaning the FTO glass with a glass cleaning agent, ultrapure water, and alcohol in sequence, and drying after cleaning to obtain a clean FTO glass substrate;

[0071] (2) Slit coating of SnO on a clean FTO glass substrate 2 Nanoparticle aqueous solution (mass concentration 2.67%), the coated SnO2 layer was heat treated at 150℃ for 30min, and then an interfacial buffer layer with a thickness of 24nm was obtained;

[0072] (3) weighing 2,2'-thiobis(acetamidine)·2,2'-thiodiacetic acid and dissolving it in a mixed solvent of chloroform and ethyl acetate in a volume ratio of 9.5:0.5, stirring and clarifying to obtain a 2.1 mg / mL diamine molten salt solution;

[0073] (4) slit coating a diamine molten salt solution on the surface of the interface buffer layer, and heat treating the coated diamine molten salt at 100° C. for 3 min to obtain a diamine molten salt surface modification layer with a thickness of 6.2 nm;

[0074] (5) Weighing CsI, MAI, FAI, PbI 2 (molar ratio of 0.1:0.1:0.8:1.0) powder was dissolved in a mixed solvent of acetonitrile, N,N-dimethylformamide and 1,3-methyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone in a volume ratio of 3:6.3:0.7, and stirred to clarify to obtain a 1.55 mol / L perovskite precursor solution;

[0075] (6) Slit coating a perovskite precursor solution on the diamine molten salt surface modification layer, and heat treating the coated perovskite wet film at 110° C. for 22 min to obtain a perovskite light absorbing layer with a thickness of 600 nm;

[0076] (7) Slit coating a 40 mg / mL PTAA chlorobenzene solution on the surface of the perovskite light absorbing layer to obtain a hole transport layer with a thickness of 33 nm;

[0077] (8) A 17 nm thick molybdenum oxide layer was evaporated on the hole transport layer and a 350 nm thick IZO electrode layer was sputtered to obtain a formal perovskite solar cell based on the surface modification of diamine molten salt.

[0078] Comparative Example 1:

[0079] Steps to prepare inverse perovskite solar cells:

[0080] (1) ultrasonically cleaning the FTO glass with a glass cleaning agent, ultrapure water, and alcohol in sequence, and drying after cleaning to obtain a clean FTO glass substrate;

[0081] (2) 0.5 mg / mL Me-4PACz ethanol solution was slit coated on a clean FTO glass substrate, and the coated Me-4PACz layer was heat treated at 100°C for 10 min to obtain a hole transport layer with a thickness of 2.7 nm;

[0082] (3) Weighing CsI, MAI, FAI, PbI 2 (molar ratio of 0.1:0.1:0.8:1.03) powder was dissolved in a mixed solvent of acetonitrile, N,N-dimethylformamide and 1,3-methyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone in a volume ratio of 3:6.3:0.7, and stirred to clarify to obtain a 1.55 mol / L perovskite precursor solution;

[0083] (3) Slit coating a perovskite precursor solution on the surface of the hole transport layer, and heat treating the coated perovskite wet film at 110° C. for 22 min to obtain a perovskite light absorbing layer with a thickness of 600 nm;

[0084] (4) A 15 nm thick C60 electron transport layer is evaporated on the perovskite light absorbing layer, a 15 nm thick tin oxide interface buffer layer is atomically deposited, and a 300 nm thick IZO electrode layer is sputtered to obtain an inverted perovskite solar cell.

[0085] Comparative Example 2:

[0086] Steps to prepare a formal perovskite solar cell:

[0087] (1) ultrasonically cleaning the FTO glass with a glass cleaning agent, ultrapure water, and alcohol in sequence, and drying after cleaning to obtain a clean FTO glass substrate;

[0088] (2) Slit coating of SnO on a clean FTO glass substrate 2Nanoparticle aqueous solution (mass concentration 2.67%), the coated SnO2 layer was heat treated at 150℃ for 30min, and then an interfacial buffer layer with a thickness of 24nm was obtained;

[0089] (3) Weighing CsI, MAI, FAI, PbI 2 (molar ratio of 0.1:0.1:0.8:1.0) powder was dissolved in a mixed solvent of acetonitrile, N,N-dimethylformamide and 1,3-methyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone in a volume ratio of 3:6.3:0.7, and stirred to clarify to obtain a 1.55 mol / L perovskite precursor solution;

[0090] (6) Slit coating a perovskite precursor solution on the surface of the interface buffer layer, and heat treating the coated perovskite wet film at 110° C. for 22 min to obtain a perovskite light absorbing layer with a thickness of 600 nm;

[0091] (7) Slit coating a 40 mg / mL PTAA chlorobenzene solution on the surface of the perovskite light absorbing layer to obtain a hole transport layer with a thickness of 33 nm;

[0092] (8) On the hole transport layer, a 17 nm thick molybdenum oxide layer is evaporated and a 350 nm thick IZO electrode layer is sputtered to obtain a formal perovskite solar cell.

[0093] Embodiment 3:

[0094] like Figure 1 As shown, a trans-perovskite solar cell based on surface modification of diamine molten salt and a preparation method thereof, comprising the following steps:

[0095] Step 1: Synthesis of pyridine-3,5-dicarboxamidine·3,5-pyridinedicarboxylic acid:

[0096] Weigh 163.18 mg (1 mmol) of pyridine-3,5-dicarboxamidine and dissolve it in 13 mL of anhydrous ethanol. Weigh 167.12 mg (1 mmol) of 3,5-pyridinedicarboxylic acid and dissolve it in 5 mL of anhydrous ethanol. Slowly add the 3,5-pyridinedicarboxylic acid ethanol solution to the continuously stirred pyridine-3,5-dicarboxamidine ethanol solution. Keep the reaction temperature at zero degrees during the reaction. After the addition is completed, continue to stir for 30 minutes. Rotary evaporate to obtain a crude product of pyridine-3,5-dicarboxamidine·3,5-pyridinedicarboxylic acid. Finally, wash the crude product with ether four times in turn to obtain pure pyridine-3,5-dicarboxamidine·3,5-pyridinedicarboxylic acid molten salt (242 mg, yield 73%), which is vacuum dried for 12 hours for use.

[0097] Step 2: Preparation of a trans-perovskite solar cell based on surface modification of diamine molten salt:

[0098] (1) ultrasonically cleaning the FTO glass with a glass cleaning agent, ultrapure water, and alcohol in sequence, and drying after cleaning to obtain a clean FTO glass substrate;

[0099] (2) 0.5 mg / mL Me-4PACz ethanol solution was slit coated on a clean FTO glass substrate, and the coated Me-4PACz layer was heat treated at 100°C for 10 min to obtain a hole transport layer with a thickness of 2.7 nm;

[0100] (3) Weighing CsI, MAI, FAI, PbI 2 (molar ratio of 0.1:0.1:0.8:1.03) powder was dissolved in a mixed solvent of acetonitrile, N,N-dimethylformamide and 1,3-methyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone in a volume ratio of 3:6.3:0.7, and stirred to clarify to obtain a 1.55 mol / L perovskite precursor solution;

[0101] (3) Slit coating a perovskite precursor solution on the surface of the hole transport layer, and heat treating the coated perovskite wet film at 110° C. for 22 min to obtain a perovskite light absorbing layer with a thickness of 600 nm;

[0102] (4) weighing pyridine-3,5-dicarboxamidine·3,5-pyridinedicarboxylic acid and dissolving it in a mixed solvent of chloroform and ethyl acetate in a volume ratio of 9.5:0.5, stirring and clarifying to obtain a 2.1 mg / mL diamine molten salt solution;

[0103] (5) slit coating a diamine molten salt solution on the surface of the perovskite light absorbing layer, and heat treating the coated diamine molten salt at 100° C. for 3 min to obtain a diamine molten salt surface modification layer with a thickness of 6.2 nm;

[0104] (6) A 15 nm thick C60 electron transport layer, a 15 nm thick tin oxide interface buffer layer, and a 300 nm thick IZO electrode layer are sequentially evaporated on the diamine molten salt surface modification layer, thereby obtaining an inverse perovskite solar cell based on the diamine molten salt surface modification.

[0105] Embodiment 4:

[0106] like Figure 2 As shown, a formal perovskite solar cell based on surface modification of diamine molten salt and a preparation method thereof, comprising the following steps:

[0107] Step 1: Synthesis of pyridine-3,5-dicarboxamidine·3,5-pyridinedicarboxylic acid:

[0108] Weigh 163.18 mg (1 mmol) of pyridine-3,5-dicarboxamidine and dissolve it in 13 mL of anhydrous ethanol. Weigh 167.12 mg (1 mmol) of 3,5-pyridinedicarboxylic acid and dissolve it in 5 mL of anhydrous ethanol. Slowly add the 3,5-pyridinedicarboxylic acid ethanol solution to the continuously stirred pyridine-3,5-dicarboxamidine ethanol solution. Keep the reaction temperature at zero degrees during the reaction. After the addition is completed, continue to stir for 30 minutes. Rotary evaporate to obtain a crude product of pyridine-3,5-dicarboxamidine·3,5-pyridinedicarboxylic acid. Finally, wash the crude product with ether four times in turn to obtain pure pyridine-3,5-dicarboxamidine·3,5-pyridinedicarboxylic acid molten salt (242 mg, yield 73%), which is vacuum dried for 12 hours for use.

[0109] Step 2: Preparation of a formal perovskite solar cell based on surface modification of diamine molten salt:

[0110] (1) ultrasonically cleaning the FTO glass with a glass cleaning agent, ultrapure water, and alcohol in sequence, and drying after cleaning to obtain a clean FTO glass substrate;

[0111] (2) Slit coating of SnO on a clean FTO glass substrate 2 Nanoparticle aqueous solution (mass concentration 2.67%), the coated SnO2 layer was heat treated at 150℃ for 30min, and then an interfacial buffer layer with a thickness of 24nm was obtained;

[0112] (3) weighing pyridine-3,5-dicarboxamidine·3,5-pyridinedicarboxylic acid and dissolving it in a mixed solvent of chloroform and ethyl acetate in a volume ratio of 9.5:0.5, stirring and clarifying to obtain a 2.1 mg / mL diamine molten salt solution;

[0113] (4) slit coating a diamine molten salt solution on the surface of the interface buffer layer, and heat treating the coated diamine molten salt at 100° C. for 3 min to obtain a diamine molten salt surface modification layer with a thickness of 6.2 nm;

[0114] (5) Weighing CsI, MAI, FAI, PbI 2 (molar ratio of 0.1:0.1:0.8:1.0) powder was dissolved in a mixed solvent of acetonitrile, N,N-dimethylformamide and 1,3-methyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone in a volume ratio of 3:6.3:0.7, and stirred to clarify to obtain a 1.55 mol / L perovskite precursor solution;

[0115] (6) Slit coating a perovskite precursor solution on the diamine molten salt surface modification layer, and heat treating the coated perovskite wet film at 110° C. for 22 min to obtain a perovskite light absorbing layer with a thickness of 600 nm;

[0116] (7) Slit coating a 40 mg / mL PTAA chlorobenzene solution on the surface of the perovskite light absorbing layer to obtain a hole transport layer with a thickness of 33 nm;

[0117] (8) A 17 nm thick molybdenum oxide layer was evaporated on the hole transport layer and a 350 nm thick IZO electrode layer was sputtered to obtain a formal perovskite solar cell based on the surface modification of diamine molten salt.

[0118] As shown in Table 1, the photoelectric conversion efficiency of the trans-perovskite solar cell modified with 2,2'-thiobis(acetamidine)·2,2'-thiodiacetic acid diamine molten salt is as high as 25.39%, and the efficiency of the cell only decays by 3.7% after 1000 hours of maximum power point tracking. The device efficiency and stability are much better than the trans-perovskite solar cell without diamine molten salt surface modification prepared in Comparative Example 1, indicating that diamine molten salt surface modification can significantly improve the interface energy level matching of perovskite cells, enhance the interface charge transfer efficiency, passivate the double-sided interface defects, and act as an interface protection layer to inhibit ion migration and water erosion, thereby achieving the simultaneous improvement of perovskite cell efficiency and stability. In addition, the photoelectric conversion efficiency of the formal perovskite solar cell modified with the diamine molten salt surface is as high as 25.86%, and the efficiency of the battery is only attenuated by 4.9% after 1000 hours of maximum power point tracking. The device efficiency and stability are much better than the formal perovskite solar cell without diamine molten salt surface modification of 2,2'-thiobis(acetamidine)·2,2'-thiodiacetic acid prepared in Comparative Example 2, which also shows the excellent effect of diamine molten salt surface modification. In addition, the surface modification using pyridine-3,5-diformamidine·3,5-pyridinedicarboxylic acid diamine molten salt can also improve the efficiency and stability of perovskite solar cells, but the improvement is slightly lower than that of 2,2'-thiobis(acetamidine)·2,2'-thiodiacetic acid diamine molten salt. Other diamine molten salts have the same effect, which will not be repeated here.

[0119] Table 1. Performance parameters of the devices in the examples and comparative examples

[0120]

[0121] like Figure 3-Figure 4 As shown, the oxygen donor of -COOH in the diamine molten salt can passivate the under-coordinated Pb 2+ Sn 2+ and Ge 2 + Defective site, -NH 2 The hydrogen donor in the ion can passivate the halogen anion point defects (such as I - Br - , Cl -), effectively inhibiting the formation of vacancies and metal Pb clusters, thereby achieving multiple passivation effects. In addition, the diamine ions in the diamine molten salt induce the transformation of the three-dimensional perovskite at the interface to the low-dimensional perovskite, effectively adjusting the lowest orbital position of the energy level of the unoccupied electrons of the interface perovskite. In addition, the SS bond interaction in the diamine molten salt molecules can assist the growth of low-dimensional perovskite crystals, induce the formation of neatly arranged and vertically distributed quantum hydrazines, realize high-speed transmission of interface carriers, and achieve the effect of synergistic passivation.

[0122] In summary, the surface modification using diamine molten salt in the present invention can significantly improve the long-term stability of the efficiency of perovskite batteries, providing a new solution for the large-scale manufacturing of perovskite batteries.

[0123] The above description is only a preferred experimental example of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A perovskite solar cell based on surface modification of diamine molten salt, characterized in that: The perovskite solar cell comprises, from bottom to top, a transparent conductive substrate layer, a hole transport layer, a perovskite light absorbing layer, a surface modification layer, an electron transport layer, an interface buffer layer and an electrode layer; or a transparent conductive substrate layer, an interface buffer layer, a surface modification layer, a perovskite light absorbing layer, a hole transport layer and an electrode layer, wherein the surface modification layer is a diamine molten salt.

2. A method for preparing a perovskite solar cell based on surface modification of a diamine molten salt, characterized in that: The following steps are involved: (1) depositing a hole transport layer on the transparent conductive substrate layer; (2) first weighing perovskite powder and dissolving it in an organic solvent, stirring and clarifying it to form a perovskite precursor solution; coating or printing the perovskite precursor solution on the hole transport layer, and obtaining a perovskite light absorbing layer after heat treatment; (3) first weighing a diamine molten salt and dissolving it in an organic solvent, stirring and clarifying it to form a diamine molten salt solution; coating or printing the diamine molten salt solution on the perovskite light absorbing layer, and obtaining a surface modification layer after heat treatment; (4) depositing an electron transport layer, an interface buffer layer and an electrode layer on the surface modification layer in sequence, thereby obtaining an inverse perovskite solar cell based on diamine molten salt interface modification; or (1) depositing an interface buffer layer on the transparent conductive substrate layer; (2) first weighing a diamine molten salt and dissolving it in an organic solvent, stirring and clarifying it to form a diamine molten salt solution; coating or printing the diamine molten salt solution on the interface buffer layer, and obtaining a surface modification layer after heat treatment; (3) first weighing perovskite powder and dissolving it in an organic solvent, stirring and clarifying it to form a perovskite precursor solution; The perovskite precursor solution is coated or printed on the surface modification layer, and the perovskite light absorbing layer is obtained after heat treatment; (4) A hole transport layer and an electrode layer are sequentially deposited on the perovskite light-absorbing layer to obtain a formal perovskite solar cell based on diamine molten salt interface modification.

3. The preparation method according to claim 2, characterized in that: The general structural formula of the perovskite is ABX3, where A is Rb + , Cs + 、MA + or FA + , B is Pb 2+ Sn 2+ Or Ge 2+ , X is I - Br - or Cl - .

4. The preparation method according to claim 2, characterized in that: The heat treatment temperature of the perovskite light absorbing layer is 30 to 300° C., and the time is 5 to 120 minutes.

5. The preparation method according to claim 2, characterized in that: The transparent conductive substrate layer is FTO glass, ITO glass, ITO / PET, ITO / PEN or ITO / PI; the hole transport layer is nickel oxide and doped nickel oxide, PTAA, Spiro-OMeTAD, Me-4PACz, 2PACz, MeO-2PACz or P3HT; the electron transport layer is fullerene or its derivatives, including: C60, C70, PC60M; the interface buffer layer is bathocuproin, tin oxide, zinc oxide, yttrium oxide, cerium oxide, titanium oxide or niobium oxide; the electrode layer is Cu, Ag, Au, Mo, Bi, ITO, IZO, AZO, IWO or ICO.

6. The preparation method according to claim 2, characterized in that: The thickness of the perovskite light absorption layer is 100-2000nm; the thickness of the surface modification layer is 1-80nm; the thickness of the electron transport layer is 1-100nm; the thickness of the interface buffer layer is 1-100nm; and the thickness of the electrode layer is 10-10000nm.

7. The preparation method according to claim 2, characterized in that: The electron transport layer is deposited by evaporation; the interface buffer layer is deposited by coating, printing, evaporation, sputtering, reactive plasma deposition, chemical vapor deposition, coating, and printing; the electrode layer is deposited by evaporation, sputtering, chemical vapor deposition, coating, and printing.

8. The preparation method according to claim 2, characterized in that: The general structural formula of the diamine molten salt is M·N, wherein M is a diamine compound, including methylenediamine, ethylenediamine, propylenediamine, butylenediamine, 1,4-phenylenediamine, 2,5-thiophenedicarboxamidine, 3,4-thiophenedicarboxamidine, 2,2'-oxybis(ethylamine), 2,2'-thiobis(ethylamine), 3,3'-thiobis(propylamine), 3,3'-thiobis(propylamine), 4,5-dicarboxamidinopyridazine, 2,2'-thiobis(acetamidine), 3,3'-thiobis(propionamidine), terephthalamidine, pyridine-3,5-diamine, pyridine-2, 6-diamine, pyridine-2,6-dicarboxamidine, pyridine-3,5-dicarboxamidine, 2,5-thiophene dimethylamine, 3,4-thiophene dimethylamine, 4,5-diaminopyridazine, pyrazine-2,5-diamine, 2,6-diaminopyrazine, terephthalamidine, malonamide, malonamide, 4,4'-diamino-2,2'-bipyridine, 1,3-phenylenediacetamidine, 2,2-bithiophene-5,5-dimethylamine, 1,2-phenylenediacetamidine, 4,4-bipiperidine, 1,3-di-4-piperidinylpropane, 1,2-dipiperidinylethane, dipiperidinylmethane, 4,4 '-Bipiperidine, 1,3-bis(4-pyridyl)propane, 4,4'-diaminodiphenyl sulfide, 4,4'-bipyridine sulfide, 1,4-phenylenediamine, succinic acid dihydrazide, maleic acid dihydrazide, oxalyl dihydrazide, isophthalic acid dihydrazide, carbohydrazide, N is a nitrogen- or sulfur-containing acid compound, including thiazole-4,5-dicarboxylic acid, 2,6-pyridinedicarboxylic acid, 3,5-pyridinedicarboxylic acid, 3,4-thiophenedicarboxylic acid, thiophene-2,5-dicarboxylic acid, 2,2'-bipyridine-6,6'-dicarboxylic acid, 3,3'-thiodipropionic acid, 3,3 '-Dithiodipropionic acid, 3,4-pyrroledicarboxylic acid, dithioglycolic acid, methylenebis(thioglycolic acid), 2,2'-thiodiacetic acid, 2,2'-bipyridine-4,4'-dicarboxylic acid, 2,2'-bipyridine-3,3'-dicarboxylic acid, pyrazine-2,3-dicarboxylic acid, 2,2-bithiophene-5,5-dicarboxylic acid, pyrazine-2,6-dicarboxylic acid, imidazole-4,5-dicarboxylic acid, 3,5-pyrazoledicarboxylic acid, pyridazine-4,5-dicarboxylic acid, pyridazine-3,6-dicarboxylic acid, pyrimidine-4,6-dicarboxylic acid, 2,5-pyrimidinedicarboxylic acid.

9. The preparation method according to claim 2, characterized in that: The organic solvent used to prepare the perovskite precursor solution is a mixture of one or more of N,N-dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone, 1,3-methyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone, 2-methoxyethanol, and acetonitrile in any proportion; the organic solvent used to prepare the diamine molten salt solution is a mixture of one or more of isopropanol, chlorobenzene, ethyl acetate, butanol, chloroform, benzene, acetonitrile, and dichloroethane in any proportion.

10. The preparation method according to claim 2, characterized in that: The concentration of the perovskite precursor solution is 0.1-3 mol / L; the concentration of the diamine molten salt is 0.001-50 mg / mL.

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