Perovskite precursor solution, perovskite thin film, perovskite solar cell and preparation method

Abstract

The invention belongs to the photovoltaic field, and particularly relates to a perovskite precursor solution, a perovskite thin film, a perovskite solar cell and a preparation method. The perovskite precursor solution comprises a perovskite structure substance raw material, an organic additive and a solvent, the chemical formula of the organic additive is shown as a formula I. A bidentate chelating structure in the used organic additive can be coordinated with Pb < 2 + >, N and O atoms provide binding sites for free Pb < 2 + > and I <-> in the perovskite film, the morphological characteristics of the film are improved, the more uniform and uninterrupted film is generated, and finally the efficiency and stability of a device are improved. # imgabs0 #

Description

Technical Field

[0001] The present invention belongs to the field of photovoltaics, and particularly relates to a perovskite precursor solution, a perovskite thin film, a perovskite solar cell, and a preparation method thereof. Background Art

[0002] Since the first perovskite solar cell (PSC) was reported by the Miyasaka research group in 2009, organic hybrid metal halide PSCs have received extensive attention due to their excellent properties such as small exciton binding energy, adjustable bandgap, high absorption coefficient, long charge carrier diffusion length, and low preparation cost. The certified power conversion efficiency (PCE) of PSCs has been significantly improved from 3.8% to 26.7%, showing great prospects for large-scale commercial production. However, preparing polycrystalline perovskite thin films by solution processing methods at low temperatures usually results in many harmful defects at grain boundaries (GBs) and surfaces.

[0003] As is well known, grain boundaries and undercoordinated ions basically exist in polycrystalline perovskite thin films, just like other semiconductor (such as Si) thin films. Therefore, defect states at grain boundaries in perovskite thin films will inevitably lead to higher non-radiative recombination rates and energy losses. These defects can form high-density trap states to capture photo-generated carriers, cause ion migration, shorten the carrier lifetime, and thus reduce the efficiency and stability of PSCs. In addition, GBs are vulnerable to high temperature and moisture, which again accelerates the formation of trap states and triggers instability problems. Therefore, passivating the defects of perovskite thin films is an effective means to eliminate perovskite GBs and achieve high-performance PSCs.

[0004] Perovskite solar cells usually use additives to achieve optimal performance, durability, and defect mitigation. Additives play a crucial role in controlling the crystal size in the initial stage and creating intermediate phases that promote nucleation, thereby enabling the manipulation of perovskite thin film morphology to improve efficiency. In addition, their basic function lies in guiding the growth of the surface, promoting the increase in crystal size, and suppressing the movement of the solution, ultimately improving efficiency. Additives can stabilize the perovskite phase through various mechanisms, such as promoting hydrogen bonding within the lattice, modifying the tolerance factor, and fine-tuning the surface energy levels. In addition, additives can modify the arrangement of energy levels within perovskite solar cells, thereby improving the performance level. They are integrated into perovskite photovoltaic devices, leading to the development of efficient, stable, and hysteresis-free technologies, and playing a crucial role in promoting the development of the industry. Generally speaking, additives play a key role in changing the structure of perovskite thin films, supporting the stability of cesium (Cs)- and formamidinium (FA)-based perovskites, adjusting energy levels, reducing non-radiative recombination, eliminating hysteresis, and improving the long-term performance of PSCs.

[0005] Currently, the defects in perovskites mainly include iodine vacancies, lead vacancies, and free I - and Pb2+ etc., introducing new substances into the perovskite bulk phase can effectively passivate the defects inside the perovskite lattice and avoid the occurrence of lattice mismatch; among various doping molecules, molecules with pyridine rings have received special attention. On the one hand, the N atom has a stable atomic structure, and on the other hand, the N atom in pyridine can coordinate with free I - to form a coordination bond and generate an N···H···I bond.

[0006] As mentioned above, although PSCs have high PCE, low cost, and the ability of scalable manufacturing, the instability of PSCs still hinders their widespread commercialization and application. The materials made of perovskite are prone to degradation when interacting with environmental effects (including light, oxygen, moisture, and heat). Over time, this deterioration may lead to a decline in the performance and efficiency of solar cells, ultimately affecting the long-term reliability and durability of solar cells. Summary of the Invention

[0007] To solve the problems existing in the prior art, the perovskite precursor solution provided by the present invention contains pyrimidine-4,6-dicarboxylic acid with a bidentate chelating structure as an organic additive. The bidentate chelating structure inside the compound is more beneficial for providing binding sites for free Pb 2+ and I - in the perovskite film than pyrimidine carboxylic acid analog compounds with a monodentate structure (such as pyrimidine-4-carboxylic acid), improving the crystallization quality and stability, thereby significantly reducing grain boundary defects and improving the photoelectric conversion efficiency of perovskite solar cells.

[0008] Specifically, the present invention provides a perovskite precursor solution, which comprises a perovskite structure material raw material, an organic additive, and a solvent; the chemical formula of the organic additive is shown in Formula I:

[0009]

[0010] In one or more embodiments, the concentration of the perovskite structure material generated theoretically from the perovskite structure material raw material in the perovskite precursor solution is 1-2 mol / L.

[0011] In one or more embodiments, the concentration of the organic additive in the perovskite precursor solution is 0.1-5 mg / mL.

[0012] In one or more embodiments, the perovskite structure material raw material comprises AX and BX 2 ; the A ion is one or more selected from methylammonium ion, formamidinium ion, cesium ion, and rubidium ion; the B ion is one or more selected from lead ion, tin ion, copper ion, zinc ion, gallium ion, and calcium ion; the X ion is selected from F - , I - , Br- , Cl - , BF 4 - and SCN - or more of the above.

[0013] In one or more embodiments, the solvent is one or more selected from ethanol, isopropanol, methanol, butanol, pentanol, N,N-dimethylformamide, dimethyl sulfoxide, 1,3-dimethyl-3,4,5,6-tetrahydro-2-pyrimidinone, acetonitrile, diphenyl sulfoxide, and dimethoxyethanol.

[0014] Another aspect of the present invention provides a perovskite thin film, which comprises a perovskite-structured substance and an organic additive; the chemical formula of the organic additive is shown in Formula I:

[0015]

[0016] In one or more embodiments, the chemical formula of the perovskite-structured substance is ABX 3 ; the A ion is one or more selected from methylammonium ion, formamidinium ion, cesium ion, and rubidium ion; the B ion is one or more selected from lead ion, tin ion, copper ion, zinc ion, gallium ion, and calcium ion; the X ion is one or more selected from F - , I - , Br - , Cl - , BF 4 - and SCN - or more of the above.

[0017] In one or more embodiments, the thickness of the perovskite thin film is 600 - 1200 nm.

[0018] In one or more embodiments, in the perovskite thin film, the mass ratio of the perovskite-structured substance to the organic additive is 1:(0.00038 - 0.0015).

[0019] Another aspect of the present invention further provides a method for preparing the perovskite thin film according to any one of the embodiments of the present invention, the method comprising coating the perovskite precursor solution according to any one of the embodiments of the present invention, and then annealing to obtain the perovskite thin film.

[0020] In one or more embodiments, the coating method is slot coating, blade coating, spin coating, inkjet printing, or screen printing.

[0021] Another aspect of the present invention further provides a perovskite solar cell comprising the perovskite thin film according to any one of the embodiments of the present invention.

[0022] In one or more embodiments, the perovskite solar cell is a single-junction perovskite cell, a crystalline silicon-perovskite tandem cell, a perovskite-perovskite tandem cell, a perovskite-copper indium gallium selenide tandem cell, a perovskite-gallium arsenide tandem cell, an organic-perovskite tandem cell, a flexible perovskite cell, or a flexible tandem cell containing perovskite.

[0023] In the present invention, by incorporating an appropriate amount of pyrimidine-4,6-dicarboxylic acid into the perovskite precursor solution, (1) the bidentate chelating structure of the material is more conducive to Pb 2+ coordination; (2) the N and O atoms provide binding sites for the free Pb 2+ and I - in the perovskite film to enhance the overall device stability; (3) the morphological properties of the film are improved, resulting in a more uniform and continuous film, ultimately enhancing the efficiency of the device. By adding the perovskite additive of the present invention, potential defects in the perovskite film can be appropriately eliminated, the interaction between the lattices can be strengthened, and ultimately the efficiency of the battery can be enhanced. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 FIG. is a schematic structural diagram of a crystalline silicon / perovskite tandem solar cell with a perovskite additive added in some embodiments.

[0025] Figure 2 FIG. is a schematic structural diagram of a crystalline silicon / perovskite tandem solar cell without a perovskite additive added in some embodiments. DETAILED DESCRIPTION

[0026] To enable those skilled in the art to understand the features and effects of the present invention, the following provides a general description and definition of the terms and phrases mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art for the present invention. In case of conflict, the definition in this specification shall prevail.

[0027] The theories or mechanisms described and disclosed herein, whether correct or incorrect, shall not limit the scope of the present invention in any way, that is, the content of the present invention can be implemented without being limited by any specific theory or mechanism.

[0028] As used herein, terms such as "comprising", "including", "containing" and similar terms encompass the meanings of "consisting essentially of" and "consisting of". For example, when the present disclosure states that "A comprises B and C", it should be considered that "A consists essentially of B and C" and "A consists of B and C" have been disclosed herein.

[0029] In this text, all features defined in the form of numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are only for the sake of brevity and convenience. Accordingly, the description of numerical ranges or percentage ranges should be regarded as having covered and specifically disclosed all possible sub-ranges and individual numerical values within the ranges (including integers and fractions).

[0030] In this text, unless otherwise specified, percentages refer to mass percentages and ratios refer to mass ratios.

[0031] In this text, when describing embodiments or examples, it should be understood that they are not used to limit the present invention to these embodiments or examples. On the contrary, all alternatives, modifications, and equivalents of the methods and materials described in the present invention can be covered within the scope defined by the claims.

[0032] In this text, for the sake of brevity of description, all possible combinations of all technical features in each embodiment or example are not described. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each embodiment or example can be combined arbitrarily, and all possible combinations should be considered as being within the scope described in this specification.

[0033] The present invention provides a perovskite precursor solution that may contain a raw material of a perovskite structure substance, an organic additive, and a solvent; the chemical formula of the organic additive is shown in Formula I:

[0034]

[0035] In the present invention, the raw material of the perovskite structure substance may contain AX and BX 2 ; the A ion may be one or more selected from methylammonium ion, formamidinium ion, guanidinium ion, cesium ion, and rubidium ion; the B ion may be one or more selected from lead ion, tin ion, copper ion, and germanium ion; the X ion may be one or more selected from F - 、I - 、Br - 、Cl - 、BF 4 - 、PF 6 - and SCN - among others.

[0036] In some embodiments, the raw material of the perovskite structure substance contains AI and BI 2 ; in some embodiments, the raw material of the perovskite structure substance contains AI, BI 2 and BBr 2 . The perovskite precursor solution may further include a second additive, and the second additive may be selected from CsCl, CsBr, CsI, PbCl 2, PbBr 2 , PbI 2 , FACl, FABr, FAI, FABF 4 , FASCN, CsSCN and Pb(SCN) 2 One or more of them. In the present invention, introducing a halogen or pseudohalogen salt (the second additive) containing a perovskite ion component can improve the nucleation and crystallization process of the perovskite.

[0037] In the present invention, the concentration of the perovskite structure substance theoretically generated from the raw materials of the perovskite structure substance in the perovskite precursor solution can be 1 - 2 mol / L, such as 1 mol / L, 1.2 mol / L, 1.4 mol / L, 1.6 mol / mL, 1.8 mmol / L, 2 mol / L. In the present invention, controlling the concentration of the perovskite structure substance within the above range can effectively improve the quality of the perovskite thin film and enhance the photoelectric conversion efficiency and open circuit voltage of the perovskite solar cell.

[0038] In the present invention, the concentration of the organic additive in the perovskite precursor solution can be 0.1 mg / mL - 5 mg / mL, such as 0.15 mg / mL, 0.2 mg / mL, 0.25 mg / mL, 0.3 mg / mL, 0.35 mg / mL, 0.4 mg / mL, 0.45 mg / mL, 0.5 mg / mL, 0.55 mg / mL, 0.6 mg / mL, 0.65 mg / mL, 0.7 mg / mL, 0.75 mg / mL, 0.8 mg / mL, 0.85 mg / mL, 0.9 mg / mL, 0.95 mg / mL, 1 mg / mL, 1.5 mg / mL, 2 mg / mL, 2.5 mg / mL, 3 mg / mL, 3.5 mg / mL, 4 mg / mL, 4.5 mg / mL, 5 mg / mL. Preferably, it is 0.1 - 2.5 mg / mL, and more preferably 0.5 - 2.5 mg / mL.

[0039] In the present invention, controlling the concentration of the organic additive within the above range can effectively improve the quality of the perovskite thin film and enhance the photoelectric conversion efficiency and open circuit voltage of the perovskite solar cell.

[0040] The present invention provides a method for preparing a perovskite thin film, which includes coating the perovskite precursor solution of the present invention and then annealing to obtain the perovskite thin film.

[0041] The preparation method of the present invention further includes: filtering the perovskite precursor solution before coating.

[0042] In the present invention, the coating method can be slit coating, blade coating, spin coating, inkjet printing or screen printing. In the present invention, the coating speed can be 5 - 30 millimeters per second.

[0043] In the present invention, the annealing process is one-step annealing or two-step annealing.

[0044] The present invention provides a perovskite thin film comprising a perovskite-structured material and an organic additive.

[0045] In the present invention, the chemical formula of the perovskite-structured material is ABX 3 ; the A ion can be one or more selected from methylammonium ion, formamidinium ion, guanidinium ion, cesium ion, and rubidium ion; the B ion can be one or more selected from lead ion, tin ion, copper ion, and germanium ion; the X ion can be one or more selected from F - 、I - 、Br - 、Cl - 、BF 4 - 、PF 6 - and SCN - among others.

[0046] In the present invention, the thickness of the perovskite thin film can be 600 - 1200 nm, such as 700 nm, 750 nm, 800 nm, 850 nm, 900 nm, 950 nm, 1000 nm, 1050 nm, 1100 nm, 1150 nm.

[0047] In the perovskite thin film of the present invention, the mass ratio of the perovskite-structured material to the organic additive can be 1:(0.00038 - 0.0015), such as 1:0.0004, 1:0.00045, 1:0.0005, 1:0.00055, 1:0.0006, 1:0.00065, 1:0.0007, 1:0.00075, 1:0.0008, 1:0.00085, 1:0.0009, 1:0.00095, 1:0.001.

[0048] The present invention provides a perovskite solar cell comprising the perovskite thin film of the present invention. In the present invention, the perovskite solar cell can include a single-junction perovskite solar cell or a tandem perovskite solar cell; the tandem perovskite solar cell can be a crystalline silicon-perovskite tandem cell, a perovskite-perovskite tandem cell, a perovskite-copper indium gallium selenide tandem cell, a perovskite-gallium arsenide tandem cell, or an organic-perovskite tandem cell.

[0049] In the present invention, the perovskite solar cell can also include a flexible perovskite cell or a flexible tandem cell containing perovskite.

[0050] In the present invention, the perovskite solar cell may further include a normal perovskite solar cell or an inverted perovskite solar cell. Specifically, the perovskite solar cell may be a normal single-junction perovskite solar cell, an inverted single-junction perovskite solar cell, a normal tandem perovskite solar cell, or an inverted tandem perovskite solar cell.

[0051] In the present invention, the normal single-junction perovskite solar cell may sequentially include a conductive substrate, an electron transport layer, a perovskite thin film, a hole transport layer, and a back electrode. In the present invention, the inverted single-junction perovskite solar cell may sequentially include a conductive substrate, a hole transport layer, a perovskite thin film, an electron transport layer, and a back electrode. In the present invention, the normal tandem perovskite solar cell may sequentially include a bottom electrode, a bottom cell, a tunneling layer, a normal perovskite top cell, and a top electrode, and the positive top cell may sequentially include an electron transport layer, a perovskite thin film, and a hole transport layer. In the present invention, the inverted tandem perovskite solar cell may sequentially include a bottom electrode, a bottom cell, a tunneling layer, an inverted perovskite top cell, and a top electrode, and the inverted top cell may sequentially include a hole transport layer, a perovskite thin film, and an electron transport layer.

[0052] In the present invention, the conductive substrate may be a flexible substrate or a rigid steel core, and the rigid substrate may be selected from indium tin oxide (ITO) transparent conductive glass, fluorine-doped tin oxide (FTO) transparent conductive glass, indium oxide doped with tungsten (IWO) transparent conductive glass, and aluminum-doped zinc oxide (AZO) transparent conductive glass.

[0053] In the present invention, the hole transport layer may be a self-assembled molecule (SAM) and / or NiOx; the self-assembled molecule is selected from one or more of [2-(3,6-dimethoxy-9H-carbazol-9-yl)ethyl]phosphonic acid (MeO-2PACZ), (2-(9H-carbazol-9-yl)ethyl)phosphonic acid, [4-(3,6-dimethyl-9H-carbazol-9-yl)butyl]phosphonic acid (MeO-4PACz), [4-(9H-carbazol-9-yl)butyl]phosphonic acid, and [4-(7H-dibenzocarbazol-7-yl)butyl]phosphoric acid.

[0054] The method for preparing a normal single-junction perovskite solar cell in the present invention includes:

[0055] (1) Depositing an electron transport layer on the surface of the conductive substrate;

[0056] (2) Depositing a perovskite thin film on the surface of the electron transport layer;

[0057] (3) Depositing a hole transport layer on the surface of the perovskite thin film;

[0058] (4) Depositing a back electrode on the surface of the hole transport layer to obtain a normal single-junction perovskite solar cell.

[0059] The method for preparing a trans single-junction perovskite solar cell according to the present invention includes:

[0060] (1) Depositing a hole transport layer on the surface of a conductive substrate;

[0061] (2) Depositing a perovskite thin film on the surface of the hole transport layer;

[0062] (3) Depositing an electron transport layer on the surface of the perovskite thin film;

[0063] (4) Depositing a back electrode on the surface of the electron transport layer to obtain a trans single-junction perovskite solar cell.

[0064] The method for preparing a normal stacked perovskite solar cell according to the present invention includes:

[0065] (1) Depositing a bottom electrode and a tunneling layer on both sides of the bottom cell respectively;

[0066] (2) Depositing an electron transport layer on the surface of the tunneling layer;

[0067] (3) Depositing a perovskite thin film on the surface of the electron transport layer;

[0068] (4) Depositing a hole transport layer on the surface of the perovskite thin film;

[0069] (5) Depositing a top electrode on the surface of the hole transport layer to obtain a normal stacked perovskite solar cell.

[0070] The method for preparing a trans stacked perovskite solar cell according to the present invention includes:

[0071] (1) Depositing a bottom electrode and a tunneling layer on both sides of the bottom cell respectively;

[0072] (2) Depositing a hole transport layer on the surface of the tunneling layer;

[0073] (3) Depositing a perovskite thin film on the surface of the hole transport layer;

[0074] (4) Depositing an electron transport layer on the surface of the perovskite thin film;

[0075] (5) Depositing a top electrode on the surface of the electron transport layer to obtain a trans stacked perovskite solar cell.

[0076] The present invention will be described below by way of specific embodiments. It should be understood that these embodiments are merely illustrative and not intended to limit the scope of the present invention. The methods, reagents, and materials used in the embodiments are conventional methods, reagents, and materials in the art unless otherwise specified. The starting compounds in the embodiments can all be obtained through commercial channels.

[0077] Example 1

[0078] This example prepares a structure asFigure 1 The shown crystalline silicon / perovskite tandem solar cell has the following specific steps:

[0079] Preparation of perovskite precursor solution: Mix 88.3 mg of cesium iodide (CsI), 233.9 mg of formamidinium iodide (FAI), 187.2 mg of lead bromide (PbBr 2 ) and 548.6 mg of lead iodide (PbI 2 ), then add 0.5 mg of pyrimidine-4,6-dicarboxylic acid as a perovskite additive, and add it to a mixed solvent of 800 μL of DMF and 200 μL of DMSO for dissolution. Filter it using a 250-μm oil filter head to obtain a perovskite precursor solution with a concentration of 1.7 mol / L of FA 0.8 Cs 0.2 Pb(I 0.8 Br 0.2 ) 3 ;

[0080] (1) Preparation of the bottom cell: Using the plasma-enhanced chemical vapor deposition (PECVD) process, deposit intrinsic amorphous silicon layers (a-Si(i)) on both sides of the intrinsic silicon layer (c-Si(n)) at 200 °C to obtain a passivation layer; then deposit an n-type microcrystalline silicon layer and a p-type microcrystalline silicon layer on both sides of the passivation layer respectively to obtain an electron transport layer (nc-Si(p)) and a hole transport layer (nc-Si(p)), and further obtain a bottom cell with a total thickness of 300 μm;

[0081] (2) Preparation of the back electrode and tunneling layer: Deposit ITO on the surface of the p-type microcrystalline silicon layer by physical vapor deposition to obtain a transparent electrode layer with a thickness of 80 nm; print silver on the surface of the transparent electrode layer by printing to obtain a silver grid line electrode with a height of 20 μm and a width of 30 μm; the transparent electrode layer and the silver grid line electrode together form the back electrode; deposit ITO on the surface of the n-type microcrystalline silicon layer by sputtering to obtain a tunneling layer with a thickness of 20 nm;

[0082] (3) Preparation of the hole transport layer: Dissolve [2-(3,6-dimethoxy-9H-carbazol-9-yl)ethyl]phosphonic acid (MeO-2PACZ) in ethanol to prepare a MeO-2PACZ solution with a concentration of 1 mmol / mL. Take 130 μL of the MeO-2PACZ solution and drop it on the surface of the tunneling layer ITO, then spin-coat it at a speed of 4000 rpm for 15 s, and transfer it to a heating plate at 100 °C for annealing for 10 min after the spin-coating is completed to obtain a hole transport layer with a thickness of 2 nm;

[0083] (4) Preparation of perovskite thin film: The perovskite thin film layer was prepared by spin coating method; the specific operation is as follows: Take 10 μL of perovskite precursor solution and drop it on the blade tip of the doctor blade. The moving speed of the doctor blade is 5 - 30 mm / s, and the height of the doctor blade is 50 - 150 μm. After scraping, it is purged with N 2 gas knife, the purging air pressure is 0.5 - 1.5 MPa, the moving speed is 5 - 30 mm / s. After purging, the perovskite thin film is annealed on a hot plate at 100 °C for 10 min to obtain a perovskite thin film layer with a thickness of 1500 nm;

[0084] (5) Preparation of electron transport layer: Fullerene (C60) was deposited on the surface of the perovskite thin film layer by thermal evaporation method (the temperature of the evaporation source is 450 °C, and the evaporation rate is 0.1 Å / s) to obtain a fullerene layer with a thickness of 12 nm; Tin dioxide (SnO 2 ) was deposited on the surface of the fullerene by atomic layer deposition method to obtain a tin dioxide layer with a thickness of 20 nm; The fullerene layer and the tin dioxide layer together form an electron transport layer with a thickness of 32 nm;

[0085] (6) Preparation of top electrode: Indium zinc oxide (IZO) was deposited on the surface of the electron transport layer by physical vapor deposition method (PVD) to obtain a transparent conductive layer with a thickness of 70 nm; Magnesium fluoride (MgF 2 ) was deposited on the surface of the transparent conductive layer by thermal evaporation method to obtain an antireflection layer with a thickness of 120 nm; Silver was deposited on the surface of the antireflection layer by thermal evaporation method to obtain a silver grid line electrode with a thickness of 800 nm; The transparent conductive layer, the antireflection layer and the silver grid line electrode together form the top electrode, and at the same time, a crystalline silicon / perovskite tandem solar cell is obtained.

[0086] Example 2

[0087] Other conditions of this example are the same as those of Example 1, except that the content of the organic additive pyrimidine - 4,6 - dicarboxylic acid in the perovskite precursor solution of this example is 1 mg.

[0088] Example 3

[0089] Other conditions of this example are the same as those of Example 1, except that the content of the organic additive pyrimidine - 4,6 - dicarboxylic acid in the perovskite precursor solution of this example is 1.5 mg.

[0090] Example 4

[0091] Other conditions of this example are the same as those of Example 1, except that the content of the organic additive pyrimidine - 4,6 - dicarboxylic acid in the perovskite precursor solution of this example is 2 mg.

[0092] Comparative Example 1

[0093] Other conditions of this comparative example are the same as those of Example 1, except that the perovskite precursor solution in this comparative example does not contain the organic additive pyrimidine-4,6-dicarboxylic acid.

[0094] Comparative Example 2

[0095] Other conditions of this comparative example are the same as those of Example 1, except that the organic additive in the perovskite precursor solution of this comparative example is 1.5 mg of pyrimidine-4-carboxylic acid.

[0096] Test Example 1

[0097] Under the standard solar spectrum of AM 1.5G at 25 °C, using a solar simulator, the voltage range was set to -0.3 - 2.05 V, and the performance (open-circuit voltage, short-circuit current density, fill factor, and photoelectric conversion efficiency) of the just-prepared crystalline silicon / perovskite tandem solar cell in Example 1 was measured.

[0098] (1) Open-circuit voltage (Voc): The voltage value corresponding to when the current is zero.

[0099] (2) Short-circuit current density (Jsc): The current value when the voltage is zero is the short-circuit current (Isc), and the current magnitude per unit cell surface area is the short-circuit current density.

[0100] (3) Fill factor (FF): The ratio of the maximum output power (Pmax) of the cell to the product of the open-circuit voltage and the short-circuit current, and the calculation formula is (Pmax / Voc*Isc), where the maximum power point is the point where the cell output power reaches the maximum value.

[0101] (4) Photoelectric conversion efficiency (PCE): The photoelectric conversion efficiency refers to the ratio of the maximum output power to the incident light power (Pin), and the calculation formula is (Pmax / Pin)*100%.

[0102] Test Example 2

[0103] The test method of this test example is the same as that of Test Example 1, except that the crystalline silicon / perovskite tandem solar cell in this test example is the just-prepared crystalline silicon / perovskite tandem solar cell in Example 2.

[0104] Test Example 3

[0105] The test method of this test example is the same as that of Test Example 1, except that the crystalline silicon / perovskite tandem solar cell in this test example is the just-prepared crystalline silicon / perovskite tandem solar cell in Example 3.

[0106] Test Example 4

[0107] The test method of this test example is the same as that of Test Example 1, with the only difference being that the crystalline silicon / perovskite tandem solar cell in this test example is the freshly prepared crystalline silicon / perovskite tandem solar cell in Example 4.

[0108] Test Example 5

[0109] The test method of this test example is the same as that of Test Example 1, with the only difference being that the crystalline silicon / perovskite tandem solar cell in this test example is the freshly prepared crystalline silicon / perovskite tandem solar cell in Comparative Example 1.

[0110] Test Example 6

[0111] The test method of this test example is the same as that of Test Example 1, with the only difference being that the crystalline silicon / perovskite tandem solar cell in this test example is the freshly prepared crystalline silicon / perovskite tandem solar cell in Comparative Example 2.

[0112] The test results of the open-circuit voltage, short-circuit current density, fill factor, and photoelectric conversion efficiency of the freshly prepared crystalline silicon / perovskite tandem solar cells (Test Examples 1 - 6) in Examples 1 - 4 and Comparative Examples 1 - 2 are shown in Table 1.

[0113] Table 1: Open-circuit voltage, short-circuit current density, fill factor, and photoelectric conversion efficiency of the crystalline silicon / perovskite tandem solar cells in Examples 1 - 4 and Comparative Examples 1 - 2

[0114]

[0115]

[0116] As can be seen from Table 1, compared with the crystalline silicon / perovskite tandem solar cell without doping pyrimidine-4,6-dicarboxylic acid in the precursor solution (Comparative Example 1), the crystalline silicon / perovskite tandem solar cell doped with pyrimidine-4,6-dicarboxylic acid in the present invention (Examples 1-4) has higher open-circuit voltage, short-circuit current density, fill factor and photoelectric conversion efficiency, which indicates that the introduction of pyrimidine-4,6-dicarboxylic acid can effectively improve the efficiency of the solar cell; compared with the crystalline silicon / perovskite tandem solar cell doped with 1.5 mg of pyrimidine-4-carboxylic acid in the precursor solution (Comparative Example 2), the crystalline silicon / perovskite tandem solar cell doped with 1.5 mg of pyrimidine-4,6-dicarboxylic acid in the present invention (Example 3) also has higher open-circuit voltage, short-circuit current density, fill factor and photoelectric conversion efficiency, which indicates that the pyrimidine carboxylic acid analog compound with a bidentate chelating structure (such as pyrimidine-4,6-dicarboxylic acid) is more conducive to effectively improving the efficiency of the solar cell than the pyrimidine carboxylic acid analog compound with a monodentate structure (such as pyrimidine-4-carboxylic acid); at the same time, from Table 1, we can also see that when the doping amount of pyrimidine-4,6-dicarboxylic acid is 1.5 mg, the device efficiency of the crystalline silicon / perovskite tandem solar cell is the highest, and further increasing the concentration of pyrimidine-4,6-dicarboxylic acid will instead lead to a decrease in the device efficiency.

Claims

1. A perovskite precursor solution, characterized in that: The perovskite precursor solution comprises a perovskite structural material raw material, an organic additive and a solvent; the chemical formula of the organic additive is shown in Formula I:

2. The perovskite precursor solution according to claim 1, characterized in that The theoretical concentration of the perovskite structure material generated by the perovskite structure material raw material in the perovskite precursor solution is 1-2 mol / L; and / or The concentration of the organic additive in the perovskite precursor solution is 0.1-5 mg / mL.

3. The perovskite precursor solution according to claim 1, characterized in that The raw materials of the perovskite structure material include AX and BX2; the A ion is one or more selected from methylamine ion, formamidine ion, cesium ion and rubidium ion; the B ion is one or more selected from lead ion, tin ion, copper ion, zinc ion, gallium ion and calcium ion; the X ion is one or more selected from F - ,I - Br - , Cl - , BF 4- and SCN - One or more of .

4. The perovskite precursor solution according to claim 1, characterized in that The solvent is one or more selected from ethanol, isopropanol, methanol, butanol, pentanol, N,N-dimethylformamide, dimethyl sulfoxide, 1,3-dimethyl-3,4,5,6-tetrahydro-2-pyrimidinone, acetonitrile, diphenyl sulfoxide and dimethoxyethanol.

5. A perovskite film, characterized in that: The perovskite film comprises a perovskite structure material and an organic additive; the chemical formula of the organic additive is shown in Formula I:

6. The perovskite film according to claim 5, characterized in that The chemical formula of the perovskite structure material is ABX3; the A ion is one or more selected from methylamine ion, formamidine ion, cesium ion and rubidium ion; the B ion is one or more selected from lead ion, tin ion, copper ion, zinc ion, gallium ion and calcium ion; the X ion is one or more selected from F - ,I - Br - , Cl - , BF 4- and SCN - One or more of .

7. The perovskite film according to claim 5, characterized in that The thickness of the perovskite film is 600-1200 nm; and / or In the perovskite film, the mass ratio of the perovskite structural material to the organic additive is 1:(0.00038-0.0015).

8. A method for preparing a perovskite film according to any one of claims 5 to 7, characterized in that: The method comprises coating the perovskite precursor solution according to any one of claims 1 to 4, and then annealing to obtain a perovskite film.

9. The method according to claim 8, characterized in that The coating method is slit coating, blade coating, spin coating, inkjet printing or screen printing.

10. A perovskite solar cell comprising the perovskite film according to any one of claims 5 to 7; preferably, the perovskite solar cell is a single-junction perovskite cell, a crystalline silicon-perovskite tandem cell, a perovskite-perovskite tandem cell, a perovskite-copper indium gallium selenide tandem cell, a perovskite-gallium arsenide tandem cell, an organic-perovskite tandem cell, a flexible perovskite cell or a flexible tandem cell containing perovskite.

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