Perovskite precursor, perovskite film, perovskite battery, preparation method and application

Abstract

The invention relates to a perovskite precursor, a perovskite film, a perovskite battery, a preparation method and application. The perovskite precursor is prepared from Cs < x > FA < y > MA < 1-x-y > PbI < 3 > and 1-ethyl-3-guanidino thiourea hydrochloride; wherein FA represents formamidine ions, MA represents methylamine ions, x is more than or equal to 0 and less than or equal to 0.05, and y is more than or equal to 0.85 and less than or equal to 0.95. And the average grain size of the perovskite film is 650 to 850 nm. The 1-ethyl-3-guanidino thiourea hydrochloride is added into the perovskite precursor, grain growth of the perovskite thick film with uniform surfaces from top to bottom is achieved, the high-quality micron-sized perovskite thick film is obtained, and then the perovskite solar cell with high photoelectric conversion efficiency and almost no optical loss can be prepared.

Description

Technical Field

[0001] The invention relates to a perovskite precursor, a perovskite film, a perovskite battery, a preparation method and an application. Background Art

[0002] Perovskite solar cells have rapidly become an important technology in the photovoltaic field in recent years due to their excellent optoelectronic properties and low-cost manufacturing process. The unique structure of perovskite materials gives them excellent light absorption ability and efficient carrier transport characteristics, and their certified power conversion efficiency has exceeded 26%. However, with the growing demand for efficient and stable solar cells, the limitations of single-sided perovskite solar cells are becoming increasingly apparent, especially in terms of light absorption and utilization efficiency.

[0003] To address this challenge, researchers have begun to focus on the development of bifacial perovskite solar cells. This new structure can effectively utilize light sources from both sides, significantly improve light capture capabilities, and can be flexibly integrated into tandem cells and photonic engineering modules. The design of bifacial perovskite cells is inspired by bifacial silicon photovoltaic modules, which have achieved significant success in the market and are expected to have a market share of more than 70% by 2030. However, despite the broad application prospects of bifacial perovskite solar cells, their performance is still not comparable to that of single-sided perovskite cells. The current highest bifacial perovskite solar cell has an open circuit voltage and fill factor of 96.3% and 97.0% of that of single-sided cells, respectively, but the short-circuit current is only 93.0%. Therefore, the significant decrease in short-circuit current density has become the main bottleneck restricting the further development of bifacial perovskite cells. It is urgent to propose effective strategies to improve their short-circuit current to narrow the gap with single-sided perovskite cells.

[0004] Most of the current double-sided perovskite devices are based on the traditional single-sided perovskite cell design, replacing the back metal electrode with a transparent electrode. Researchers have introduced micron or nanoparticles with light scattering ability at the buried interface of the perovskite to extend the light path and enhance the light absorption effect. However, light scattering particles are prone to agglomeration and may diffuse into the perovskite layer, introducing additional defects; and increasing the thickness of other functional layers will bring additional parasitic absorption. A simple way is to directly increase the thickness of the perovskite layer. However, increasing the thickness of the perovskite layer often faces the negative effects of high concentrations of perovskite precursors on crystallization nucleation, which limits the further improvement of the performance of double-sided perovskite solar cells. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the defects in the prior art and provide a perovskite precursor, a perovskite film, a perovskite cell, a preparation method and an application. In the perovskite precursor of the present invention, 1-ethyl-3-guanidinothiourea hydrochloride is added to obtain a high-quality micron-level perovskite thick film, and then a perovskite solar cell with high photoelectric conversion efficiency and almost no optical loss can be prepared.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a perovskite precursor comprising Cs x FA y MA 1-x-y PbI 3 and 1-ethyl-3-guanidinothiourea hydrochloride; wherein FA represents formamidine ion, MA represents methylamine ion, 0≤x≤0.05, 0.85≤y≤0.95; the mass of the 1-ethyl-3-guanidinothiourea hydrochloride is the same as that of the Cs x FA y MA 1-x-y PbI 3 The molar ratio is (0.32-1.15) mg:1 mmol.

[0008] In the present invention, y may be 0.88.

[0009] In the present invention, x may be 0.05.

[0010] In the present invention, the 1-ethyl-3-guanidinothiourea hydrochloride and the Cs x FA y MA 1-x-y PbI 3 The mass ratio can be (5-18):10000, preferably (7.9-16):10000, such as 7.9:10000, 10:10000 or 15.7:10000.

[0011] In the present invention, the mass of the 1-ethyl-3-guanidinothiourea hydrochloride is the same as that of the Cs x FA y MA 1-x-y PbI 3 The molar ratio of may be (0.5-1.1) mg:1 mmol, such as 0.5 mg:1 mmol, 0.8 mg:1 mmol or 1 mg:1 mmol.

[0012] In the present invention, the Cs x FA y MA 1-x-y PbI 3The raw materials are conventionally selected in the art and may include lead iodide, formamidine iodide, methylamine iodide and cesium iodide.

[0013] In a second aspect, the present invention provides a method for preparing a perovskite film, comprising the following steps:

[0014] A precursor solution is coated on a substrate, and then an anti-solvent is added dropwise; the precursor solution includes a solvent and the perovskite precursor as described above.

[0015] In the present invention, the solvent is selected conventionally in the art, such as dimethyl sulfoxide and / or N,N-dimethylformamide. Preferably, the solvent is dimethyl sulfoxide and N,N-dimethylformamide in a volume ratio of 1:4.

[0016] In the present invention, the mass ratio of the 1-ethyl-3-guanidinothiourea hydrochloride to the precursor solution may be (0.0002-0.0012):1.

[0017] In the present invention, in the precursor solution, the Cs x FA y MA 1-x-y PbI 3 The ratio of the molar amount to the volume of the solvent is (1.8-2.2) mmol:1 mL, for example 2 mmol:1 mL.

[0018] In the present invention, the coating method is conventionally selected in the art, such as spin coating. The rotation speed of the spin coating is preferably 1000-6000 rpm.

[0019] In the present invention, the coating time is conventionally selected in the art, preferably 10-45 seconds.

[0020] In certain specific embodiments of the present invention, the coating process is: firstly spin-coating the perovskite precursor solution at a speed of 1000-3000 rpm, for example, 2000 rpm for 20-30s, and then spin-coating it on the substrate at a speed of 3000-6000 rpm for 10-15s.

[0021] In the present invention, according to conventional operations in the art, an anti-solvent may be added dropwise 5-10 seconds before the coating is completed. The anti-solvent is preferably ethyl acetate. The volume ratio of the anti-solvent to the solvent is preferably (50-200):1000.

[0022] In the present invention, after the anti-solvent is added dropwise, an annealing treatment may be performed according to conventional operations in the art. The annealing temperature is preferably 100-120° C. The annealing time is preferably 30-40 min.

[0023] In certain specific embodiments of the present invention, the specific operation of the method for preparing the perovskite film is as follows: spin coating the perovskite precursor solution onto the substrate, and the spin coating parameters are: first spin coating at a speed of 2000 rpm for 30 seconds, then spin coating at a speed of 6000 rpm for 15 seconds, and in the last 10 seconds of spin coating, 0.2 mL of ethyl acetate is quickly added to the spin-coated film; then the film is annealed at 120° C. for 30 minutes to prepare a perovskite thick film; the perovskite precursor includes 1-ethyl-3-guanidinothiourea hydrochloride, lead iodide, formamidine iodine, methylamine iodine and cesium iodide in a dosage ratio of (1-2) mg:2 mmol:1.76 mmol:0.14 mmol:1 mmol.

[0024] In the present invention, the method for preparing the perovskite film may further include the following steps: after the perovskite film is formed on the surface of the substrate, the substrate is removed. That is, in the present invention, those skilled in the art may remove the substrate according to actual conditions to obtain the separate perovskite active layer.

[0025] In the present invention, the substrate may be an electron transport layer. The electron transport layer may include tin dioxide or titanium dioxide.

[0026] In a third aspect, the present invention provides a perovskite film prepared by the method for preparing the perovskite film as described above.

[0027] In a fourth aspect, the present invention provides a perovskite film comprising an active component, wherein the active component comprises Cs x FA y MA 1-x-y PbI 3 ; Wherein, FA represents formamidinium ion, MA represents methylamine ion, 0≤x≤0.05, 0.85≤y≤0.95; the average grain size of the perovskite film is 650-850nm.

[0028] In the present invention, y may be 0.88.

[0029] In the present invention, x may be 0.05.

[0030] In the present invention, the surface root mean square roughness of the perovskite film may be 20-32 nm, such as 23 nm, 25 nm or 30 nm.

[0031] In the present invention, the average grain size of the perovskite film may be 700 nm, 750 nm, 800 nm or 850 nm.

[0032] In the present invention, the thickness of the perovskite film may be 1000-1500 nm, for example, 1320 nm.

[0033] In the present invention, the perovskite film can be prepared by the above-mentioned method for preparing the perovskite film. It should be noted that, according to the common understanding in the art, the auxiliary materials used in the preparation process, such as 1-ethyl-3-guanidinothiourea hydrochloride, will be evenly distributed in the perovskite film.

[0034] In a fifth aspect, the present invention provides an application of 1-ethyl-3-guanidinothiourea hydrochloride in the preparation of a perovskite film, wherein the mass of the 1-ethyl-3-guanidinothiourea hydrochloride and the molar amount of the active ingredient in the perovskite film are (0.32-1.15) mg:1 mmol.

[0035] In the present invention, the active ingredient preferably includes Cs x FA y MA 1-x-y PbI 3 ; wherein FA represents formamidinium ion, MA represents methylamine ion, 0≤x≤0.05, 0.85≤y≤0.95. x FA y MA 1-x-y PbI 3 The raw materials are conventionally selected in the art and may include lead iodide, formamidine iodide, methylamine iodide and cesium iodide.

[0036] In the present invention, preferably y=0.88.

[0037] In the present invention, x may be 0.05.

[0038] In the present invention, the perovskite film may be a perovskite film used in the field of perovskite cells.

[0039] In a sixth aspect, the present invention provides a perovskite cell comprising the perovskite film as described above.

[0040] In the present invention, preferably, the perovskite cell comprises a conductive substrate, an electron transport layer, the perovskite film, a hole transport layer, a buffer layer and an electrode layer stacked in sequence.

[0041] The conductive substrate may be a transparent material, preferably including indium tin oxide.

[0042] Wherein, the electron transport layer may include tin dioxide or titanium dioxide.

[0043] The thickness of the electron transport layer may be 10-100 nm, for example, 15 nm.

[0044] The hole transport layer may include 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene or poly(3-hexylthiophene).

[0045] The thickness of the hole transport layer may be 100-300 nm, for example, 200 nm.

[0046] The buffer layer may include molybdenum oxide or vanadium oxide.

[0047] The thickness of the buffer layer may be 5-15 nm, for example, 10 nm.

[0048] The electrode layer may be a transparent material, preferably including indium tin oxide or indium zinc oxide.

[0049] The thickness of the electrode layer may be 100-300 nm, for example, 200 nm.

[0050] In a seventh aspect, the present invention provides a method for preparing a perovskite battery as described above, comprising the following steps:

[0051] S1, coating an electron transport layer precursor solution onto the conductive substrate to obtain the electron transport layer;

[0052] S2, coating the precursor solution on the surface of the electron transport layer, and dropping the anti-solvent to obtain the perovskite film;

[0053] S3, coating a hole transport layer precursor solution onto the surface of the perovskite film to obtain the hole transport layer;

[0054] S4, evaporating a buffer layer material on the surface of the hole transport layer to obtain the buffer layer;

[0055] S5. Magnetron sputtering an electrode layer material on the surface of the buffer layer to obtain an electrode layer.

[0056] In the present invention, in step S1, in the electron transport layer precursor solution, the volume ratio of the electron transport layer precursor to the solvent is 1:(2-3). The solvent is preferably water.

[0057] In the present invention, in step S1, the coating method is conventionally selected in the art, such as spin coating. The rotation speed of the spin coating is preferably 4000-4500 rpm; and the coating time is preferably 25-30 s.

[0058] In the present invention, in step S1, according to conventional operations in the art, annealing may be performed after coating. The annealing temperature is preferably 120-150° C. The annealing time is preferably 30-40 minutes.

[0059] In the present invention, in step S2, the coating method is conventionally selected in the art, such as spin coating. The rotation speed of the spin coating is preferably 1000-6000 rpm. The coating time is preferably 10-45 s.

[0060] In the present invention, in step S2, according to conventional operations in the art, the anti-solvent may be added dropwise 5-10 seconds before the end of the coating.

[0061] In the present invention, in step S2, according to conventional operations in the art, after the anti-solvent is added dropwise, an annealing treatment may be performed. The annealing temperature is preferably 100-120° C. The annealing time is preferably 30-40 min.

[0062] In certain specific embodiments of the present invention, the specific operation of step S2 is: spin coating the perovskite precursor solution onto the surface of the electron transport layer, and the spin coating parameters are: first spin coating at a speed of 2000 rpm for 30 seconds, then spin coating at a speed of 6000 rpm for 15 seconds, and in the last 10 seconds of spin coating, 0.2 mL of ethyl acetate is quickly added to the spin-coated film; then the film is annealed at 120° C. for 30 minutes to prepare a perovskite thick film; the perovskite precursor includes 1-ethyl-3-guanidinothiourea hydrochloride, lead iodide, formamidine iodine, methylamine iodine and cesium iodide in a dosage ratio of (1-2) mg:2 mmol:1.76 mmol:0.14 mmol:1 mmol.

[0063] In the present invention, in step S3, according to the conventional selection in the art, the hole transport layer precursor solution may include 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene or poly(3-hexylthiophene), 4-tert-butylpyridine, a lithium salt solution and a main solvent. The lithium salt solution is preferably a lithium bis(trifluoromethanesulfonyl)imide solution. The concentration of the lithium salt solution is preferably 500-520 mg / mL. The solvent of the lithium salt solution is preferably acetonitrile. The mass of the 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene and the volume of the main solvent are preferably 72.3-80 mg / mL. The volume ratio of the 4-tert-butylpyridine and the main solvent is preferably (29-30):1000. The volume ratio of the lithium salt solution to the main solvent is preferably (15-17.5): 1000. The main solvent is preferably chlorobenzene.

[0064] In the present invention, in step S3, the coating method is conventionally selected in the art, such as spin coating. The rotation speed of the spin coating is preferably 1000-3000 rpm, such as 2000 rpm. The coating time is preferably 10-50 s, such as 30 s.

[0065] In the present invention, in step S3, the coating may be dried according to conventional methods in the art.

[0066] In the present invention, in step S4, according to conventional selection in the art, the evaporation rate can be 0.01-0.1 nm / s, for example 0.03 nm / s.

[0067] In the present invention, in step S5, according to conventional selection in the art, the power of the magnetron sputtering can be 30-80W, for example, 60W.

[0068] Without violating the common sense in the art, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present invention.

[0069] The reagents and raw materials used in the present invention are commercially available.

[0070] The positive and progressive effects of the present invention are:

[0071] (1) 1-ethyl-3-guanidinothiourea hydrochloride is added to the perovskite precursor of the present invention, so that the grains of the perovskite thick film grow from top to bottom, achieving surface uniformity, and thus obtaining a high-quality micron-level perovskite thick film;

[0072] (2) The perovskite film of the present invention has a smoother surface and a larger grain size, thereby being able to prepare a perovskite solar cell with high photoelectric conversion efficiency and almost no optical loss;

[0073] (3) The perovskite solar cell of the present invention has a front-side photoelectric conversion efficiency of more than 22% and almost no optical loss, maximizing its short-circuit current density;

[0074] (4) The perovskite solar cell of the present invention can maintain more than 80% of the initial efficiency after continuous operation for 2000 hours under 1 sun illumination, showing high operation stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0075] Figure 1 Optical microscope images of the thin films in Example 3 and Comparative Example 1 at different times during the annealing process;

[0076] Figure 2 The scanning electron microscope images of the perovskite thick film in Example 3 and Comparative Example 1;

[0077] Figure 3 The current-voltage curves of the front side of the double-sided perovskite solar cell prepared in Example 2 and Comparative Example 1 under one sun illumination;

[0078] Figure 4 Current-voltage curves of the front side of the double-sided perovskite solar cells prepared in Example 2, Comparative Example 2 and Comparative Example 3 under one sun illumination;

[0079] Figure 5The current-voltage curve of the front side of the double-sided perovskite solar cell prepared in Example 3 with or without a reflective layer under one sun illumination;

[0080] Figure 6 This is a comparison chart of the stability of the double-sided perovskite solar cells prepared in Example 3 and Comparative Example 1 when operating at the maximum power point under illumination. DETAILED DESCRIPTION

[0081] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples. The experimental methods in the following examples without specifying specific conditions are carried out according to conventional methods and conditions, or selected according to the product specifications.

[0082] In the following examples and comparative examples,

[0083] The surface root mean square roughness was tested based on atomic force microscopy with a scanning range of 2 μm × 2 μm.

[0084] The average grain size was measured by scanning electron microscopy with a scanning range of 5 μm × 5 μm.

[0085] Example 1

[0086] A preparation method of a perovskite thick film, the specific steps are as follows:

[0087] (1) Weigh 2 mg of 1-ethyl-3-guanidinothiourea hydrochloride for use;

[0088] (2) According to Cs 0.05 FA 0.88 MA 0.07 PbI 3 Weigh 922 mg (2 mmol) of the corresponding lead iodide, 302.7 mg (1.76 mmol) of formamidine iodine, 22.3 mg (0.14 mmol) of methylamine iodide and 26 mg (1 mmol) of cesium iodide, a total of 1273 mg, and dissolve them in a mixed solvent of 200 μL DMSO and 800 μL DMF to obtain a high-concentration precursor solution; directly add the 1-ethyl-3-guanidinothiourea hydrochloride weighed in step (1) to the prepared high-concentration precursor solution to obtain a perovskite precursor solution;

[0089] (3) At room temperature, the perovskite precursor solution prepared in step (2) was spin-coated onto the substrate. The spin-coating parameters were: first, spin-coating at a speed of 2000 rpm for 30 s, then spin-coating at a speed of 6000 rpm for 15 s. In the last 10 s of spin-coating, 0.2 mL of ethyl acetate was quickly added dropwise onto the thin film obtained by spin coating.

[0090] (4) The film was annealed at 120°C for 30 min to obtain a perovskite thick film with a thickness of 1320 nm, a surface root mean square roughness of 23 nm, and an average grain size of 800 nm.

[0091] Example 2

[0092] A preparation method of a double-sided perovskite solar cell, the specific steps are as follows:

[0093] (1) Tin oxide and deionized water were mixed in a volume ratio of 1:3, and then spin-coated on a transparent conductive substrate of indium tin oxide at a speed of 4500 rpm for 25 seconds, and then annealed at 150° C. for 30 minutes to prepare a tin oxide electron transport layer with a thickness of 15 nm;

[0094] (2) preparing a high concentration precursor solution identical to step (2) in Example 1, and directly adding 1 mg of 1-ethyl-3-guanidinothiourea hydrochloride to the high concentration precursor solution to obtain a perovskite precursor solution; spin coating the prepared perovskite precursor solution onto the electron transport layer, wherein the spin coating parameters are: first spin coating at a speed of 2000 rpm for 30 s, then spin coating at a speed of 6000 rpm for 15 s, and in the last 10 s of spin coating, quickly dripping 0.15 mL of ethyl acetate onto the spin-coated film, and then annealing at 120° C. to obtain a perovskite thick film having a thickness of 1320 nm, a surface root mean square roughness of 30 nm, and an average grain size of 700 nm;

[0095] (3) First, 72.3 mg of Spiro-OMeTAD was dissolved in 1 mL of chlorobenzene, and then 29 μL of 4-tert-butylpyridine and 17.5 μL of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) solution were added respectively, and the mixture was shaken until clear to obtain a mixed solution, wherein the LiTFSI solution refers to a 520 mg / mL acetonitrile solution; the mixed solution was then spin-coated on the perovskite film at a speed of 2000 rpm for 30 s, and after drying, a hole transport layer with a thickness of 200 nm was obtained; then, a molybdenum oxide buffer layer with a thickness of 10 nm was evaporated at a speed of 0.03 nm / s; finally, ITO was magnetron sputtered at a power of 60 W to obtain an ITO electrode with a thickness of 200 nm, and finally a double-sided perovskite solar cell was obtained.

[0096] Example 3

[0097] A preparation method of a double-sided perovskite solar cell, the specific steps are as follows:

[0098] (1) Tin oxide and deionized water were mixed in a volume ratio of 1:3, and then spin-coated on a transparent conductive substrate of indium tin oxide at a speed of 4500 rpm for 25 seconds, and then annealed at 150° C. for 30 minutes to prepare a tin oxide electron transport layer with a thickness of 15 nm;

[0099] (2) preparing a high concentration precursor solution identical to step (2) in Example 1, and directly adding 2 mg of 1-ethyl-3-guanidinothiourea hydrochloride to the high concentration precursor solution to obtain a perovskite precursor solution; spin coating the prepared perovskite precursor solution onto the electron transport layer, wherein the spin coating parameters are: first spin coating at a speed of 2000 rpm for 30 s, then spin coating at a speed of 6000 rpm for 15 s, and in the last 10 s of spin coating, quickly dripping 0.15 mL of ethyl acetate onto the spin-coated film, and then annealing at 120° C. to obtain a perovskite thick film having a thickness of 1320 nm, a surface root mean square roughness of 23 nm, and an average grain size of 800 nm;

[0100] (3) First, 72.3 mg of Spiro-OMeTAD was dissolved in 1 mL of chlorobenzene, and then 29 μL of 4-tert-butylpyridine and 17.5 μL of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) solution were added respectively, and the mixture was shaken until clear to obtain a mixed solution, wherein the LiTFSI solution refers to a 520 mg / mL acetonitrile solution; the mixed solution was then spin-coated on the perovskite film at a speed of 2000 rpm for 30 s, and after drying, a hole transport layer with a thickness of 200 nm was obtained; then, a molybdenum oxide buffer layer with a thickness of 10 nm was evaporated at a speed of 0.03 nm / s; finally, ITO was magnetron sputtered at a power of 60 W to obtain an ITO electrode with a thickness of 200 nm, and finally a double-sided perovskite solar cell was obtained.

[0101] Comparative Example 1

[0102] A preparation method of a double-sided perovskite solar cell, the specific steps are as follows:

[0103] (1) Tin oxide and deionized water were mixed in a volume ratio of 1:3, and then spin-coated on a transparent conductive substrate of indium tin oxide at a speed of 4500 rpm for 25 seconds, and then annealed at 150° C. for 30 minutes to prepare a tin oxide electron transport layer with a thickness of 15 nm;

[0104] (2) preparing a high concentration precursor solution identical to step (2) in Example 1; spin coating the prepared high concentration precursor solution onto the electron transport layer, wherein the spin coating parameters are as follows: firstly spin coating at a speed of 2000 rpm for 30 s, then spin coating at a speed of 6000 rpm for 15 s, and in the last 10 s of spin coating, quickly dripping 0.15 mL of ethyl acetate onto the spin-coated film, and then annealing at 120° C. to prepare a perovskite thick film having a thickness of 1320 nm, a surface root mean square roughness of 45 nm, and an average grain size of 400 nm;

[0105] (3) First, 72.3 mg of Spiro-OMeTAD was dissolved in 1 mL of chlorobenzene, and then 29 μL of 4-tert-butylpyridine and 17.5 μL of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) solution were added respectively, and the mixture was shaken until clear to obtain a mixed solution, wherein the LiTFSI solution refers to a 520 mg / mL acetonitrile solution; the mixed solution was then spin-coated on the perovskite film at a speed of 2000 rpm for 30 s, and after drying, a hole transport layer with a thickness of 200 nm was obtained; then, a molybdenum oxide buffer layer with a thickness of 10 nm was evaporated at a speed of 0.03 nm / s; finally, ITO was magnetron sputtered at a power of 60 W to obtain an ITO electrode with a thickness of 200 nm, and finally a double-sided perovskite solar cell was obtained.

[0106] Comparative Example 2

[0107] A preparation method of a double-sided perovskite solar cell, the specific steps are as follows:

[0108] (1) Tin oxide and deionized water were mixed in a volume ratio of 1:3, and then spin-coated on a transparent conductive substrate of indium tin oxide at a speed of 4500 rpm for 25 seconds, and then annealed at 150° C. for 30 minutes to prepare a tin oxide electron transport layer with a thickness of 15 nm;

[0109] (2) preparing a high concentration precursor solution identical to step (2) in Example 1, and directly adding 3 mg of 1-ethyl-3-guanidinothiourea hydrochloride to the high concentration precursor solution to obtain a perovskite precursor solution; spin coating the prepared perovskite precursor solution onto the electron transport layer, wherein the spin coating parameters are as follows: first spin coating at a speed of 2000 rpm for 30 s, then spin coating at a speed of 6000 rpm for 15 s, and in the last 10 s of spin coating, quickly dripping 0.15 mL of ethyl acetate onto the spin-coated film, and then annealing at 120° C. to obtain a perovskite thick film having a thickness of 1320 nm, a surface root mean square roughness of 35 nm, and an average grain size of 600 nm;

[0110] (3) First, 72.3 mg of Spiro-OMeTAD was dissolved in 1 mL of chlorobenzene, and then 29 μL of 4-tert-butylpyridine and 17.5 μL of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) solution were added respectively, and the mixture was shaken until clear to obtain a mixed solution, wherein the LiTFSI solution refers to a 520 mg / mL acetonitrile solution; the mixed solution was then spin-coated on the perovskite film at a speed of 2000 rpm for 30 s, and after drying, a hole transport layer with a thickness of 200 nm was obtained; then, a molybdenum oxide buffer layer with a thickness of 10 nm was evaporated at a speed of 0.03 nm / s; finally, ITO was magnetron sputtered at a power of 60 W to obtain an ITO electrode with a thickness of 200 nm, and finally a double-sided perovskite solar cell was obtained.

[0111] Comparative Example 3

[0112] A preparation method of a double-sided perovskite solar cell, the specific steps are as follows:

[0113] (1) Tin oxide and deionized water were mixed in a volume ratio of 1:3, and then spin-coated on a transparent conductive substrate of indium tin oxide at a speed of 4500 rpm for 25 seconds, and then annealed at 150° C. for 30 minutes to prepare a tin oxide electron transport layer with a thickness of 15 nm;

[0114] (2) preparing a high concentration precursor solution identical to step (2) in Example 1, and directly adding 5 mg of 1-ethyl-3-guanidinothiourea hydrochloride to the high concentration precursor solution to obtain a perovskite precursor solution; spin coating the prepared perovskite precursor solution onto the electron transport layer, wherein the spin coating parameters are as follows: first spin coating at a speed of 2000 rpm for 30 s, then spin coating at a speed of 6000 rpm for 15 s, and in the last 10 s of spin coating, quickly dripping 0.15 mL of ethyl acetate onto the spin-coated film, and then annealing at 120° C. to obtain a perovskite thick film having a thickness of 1320 nm, a surface root mean square roughness of 55 nm, and an average grain size of 300 nm;

[0115] (3) First, 72.3 mg of Spiro-OMeTAD was dissolved in 1 mL of chlorobenzene, and then 29 μL of 4-tert-butylpyridine and 17.5 μL of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) solution were added respectively, and the mixture was shaken until clear to obtain a mixed solution, wherein the LiTFSI solution refers to a 520 mg / mL acetonitrile solution; the mixed solution was then spin-coated on the perovskite film at a speed of 2000 rpm for 30 s, and after drying, a hole transport layer with a thickness of 200 nm was obtained; then, a molybdenum oxide buffer layer with a thickness of 10 nm was evaporated at a speed of 0.03 nm / s; finally, ITO was magnetron sputtered at a power of 60 W to obtain an ITO electrode with a thickness of 200 nm, and finally a double-sided perovskite solar cell was obtained.

[0116] Effect Example 1: Morphology Observation

[0117] 1. Test object: the perovskite thick film obtained in Example 3 and Comparative Example 1.

[0118] 2. Test results:

[0119] (1) During the annealing process in Example 3 and Comparative Example 1, an optical microscope was used to observe the annealing process. The results are as follows: Figure 1 As shown, Figure 1 Optical microscopy images of the films at different times during the annealing process are shown.

[0120] In Comparative Example 1, since 1-ethyl-3-guanidinothiourea hydrochloride was not added, as the annealing time increased from 10s to 90s, the number of nuclei in the thick film was very large, which can be clearly shown in the figures of 10s, 30s and 50s. Some nuclei will splash in the solution and on both the upper and lower surfaces, that is, the nucleation process of the perovskite film is faster and the film quality is poor.

[0121] In Example 3, 1-ethyl-3-guanidinothiourea hydrochloride was added. As the annealing time increased from 10s to 90s, the thick film showed a uniform nucleation process from top to bottom, and the existence of the nucleus could not be clearly seen in each figure, thereby obtaining a high-quality perovskite film.

[0122] (2) The perovskite thick films after annealing in Example 3 and Comparative Example 1 were observed by scanning electron microscope. The results are as follows: Figure 2 As shown. Figure 2 It can be seen that in Example 3, the surface of the perovskite thick film prepared by adding 1-ethyl-3-guanidinothiourea hydrochloride is smoother and the grain size is larger, which significantly improves the quality of the perovskite thick film.

[0123] Effect Example 2: Photoelectric Conversion Efficiency

[0124] 1. Test object: double-sided perovskite solar cells prepared in Examples 2-3 and Comparative Examples 1-3.

[0125] 2. Test method:

[0126] (1) The standard is T / CPIA 0032-2022, and the standard silicon cell is calibrated to 1 sun, 100mW·cm -2 , the test temperature is 25℃, and the current-voltage curve test is carried out on the double-sided perovskite solar cell. The voltage scanning range is 0-1.2V, the delay time is 10ms, and the number of sampling points is 21;

[0127] (2) When testing the double-sided perovskite solar cell prepared in Example 3, a reflective layer can be added to the back of the cell device, that is, behind the ITO electrode for testing, which is represented by Example 3 (without reflective layer) and Example 3 (with reflective layer) respectively; wherein the reflective layer is made of aluminum foil with a size of 0.4 cm 2 , added after the back electrode.

[0128] 3. Test results:

[0129] (1) Figure 3 The current-voltage curves of the double-sided perovskite solar cells prepared in Example 3 and Comparative Example 1 are shown in the figure. As compared with Comparative Example 1, the open circuit voltage Voc From 1.111V to 1.145V, the short-circuit current density J sc From 24.04 mA cm -2 Increased to 25.01 mA cm -2 Further calculations show that the fill factor FF increased from 78.75% to 81.72%, and the photoelectric conversion efficiency PCE increased from 21.04% to 23.42%. All indicators have been significantly improved.

[0130] (2) Figure 4 The current-voltage curve of the double-sided perovskite solar cell prepared in Example 2, Comparative Example 2 and Comparative Example 3. As can be seen from the figure, in Example 2, when a low content of 1-ethyl-3-guanidinothiourea hydrochloride is added, the short-circuit current density of the device is large, and the amount of 1-ethyl-3-guanidinothiourea hydrochloride is appropriately increased to effectively increase its open circuit voltage. In Comparative Examples 2-3, the amount of 1-ethyl-3-guanidinothiourea hydrochloride added is too much, and as the amount added increases, the short-circuit current density and open circuit voltage of the device both show a decreasing trend.

[0131] (3) Figure 5 The current-voltage curve of the front side of the double-sided perovskite solar cell prepared in Example 3 under one sun illumination with or without a reflective layer. As can be seen from the figure, the open circuit voltage V oc It only changes slightly between 1.145-1.153V, and the short-circuit current density J sc Only at 24.89-25.01 mA cm -2 Further calculations show that the fill factor FF is between 80.98% and 81.72%, and the photoelectric conversion efficiency PCE is between 23.25% and 23.42%. It can be seen that the short-circuit current of the device with or without the reflective layer has almost no increase, which shows that the thickness of the perovskite thick film is sufficient to absorb all visible photons and minimize optical losses.

[0132] The performances of the solar cells prepared in the examples and comparative examples are summarized in the following table.

[0133]

[0134] Effect Example 3: Stability of Perovskite Solar Cells

[0135] 1. Test object: double-sided perovskite solar cells prepared in Example 3 and Comparative Example 1.

[0136] 2. Test method: Under room temperature, at a sunlight intensity (100mW·cm -2) and continuously operated the double-sided perovskite solar cell for 2000 h in a nitrogen environment.

[0137] 3. Test results: The test results are as follows: Figure 6 It is shown that the perovskite solar cell prepared in Example 3 can still maintain about 80% of the initial efficiency after continuous operation for 2000 hours in a nitrogen environment, while the double-sided perovskite solar cell prepared in Comparative Example 1 without adding 1-ethyl-3-guanidinothiourea hydrochloride can only maintain about 50% of the initial efficiency.

[0138] From the above test results, it can be seen that introducing an appropriate amount of 1-ethyl-3-guanidinothiourea hydrochloride into the precursor can not only optimize the quality required for the perovskite thick film and minimize the optical loss, but also improve the operating stability of the double-sided perovskite solar cells.

Claims

1. A perovskite precursor, characterized in that: It includes Cs x FA y MA 1-x-y PbI3 and 1-ethyl-3-guanidinothiourea hydrochloride; wherein FA represents formamidine ion, MA represents methylamine ion, 0≤x≤0.05, 0.85≤y≤0.95; the mass of the 1-ethyl-3-guanidinothiourea hydrochloride is the same as that of the Cs x FA y MA 1-x-y The molar ratio of PbI3 is (0.32-1.15) mg:1 mmol.

2. The perovskite precursor according to claim 1, characterized in that It meets at least one of the following conditions: (1)y＝0.88； (2) The 1-ethyl-3-guanidinothiourea hydrochloride and the Cs x FA y MA 1-x-y The mass ratio of PbI3 is (5-18):10000, preferably (7.9-16):10000, such as 7.9:10000, 10:10000 or 15.7:10000; (3) The mass of the 1-ethyl-3-guanidinothiourea hydrochloride and the Cs x FA y MA 1-x-y The molar ratio of PbI3 is (0.5-1.1) mg:1 mmol, such as 0.5 mg:1 mmol, 0.8 mg:1 mmol or 1 mg:1 mmol; (4) Cs x FA y MA 1-x-y The raw materials of PbI3 include lead iodide, formamidinium iodide, methylamine iodide and cesium iodide.

3. A method for preparing a perovskite film, characterized in that: It includes the following steps: The precursor solution is coated on the substrate, and then an anti-solvent is added dropwise; the precursor solution comprises a solvent and the perovskite precursor as claimed in claim 1 or 2.

4. The method for preparing a perovskite film according to claim 3, characterized in that: It meets one or more of the following conditions: (1) The solvent is dimethyl sulfoxide and / or N,N-dimethylformamide; preferably, the solvent is dimethyl sulfoxide and N,N-dimethylformamide in a volume ratio of 1:4; (2) The mass ratio of the 1-ethyl-3-guanidinothiourea hydrochloride to the precursor solution is (0.0002-0.0012):1; (3) In the precursor solution, the Cs x FA y MA 1-x-y The ratio of the molar amount of PbI3 to the volume of the solvent is (1.8-2.2) mmol:1 mL, for example 2 mmol:1 mL; (4) The coating method is spin coating; the rotation speed of the spin coating is preferably 1000-6000 rpm; (5) The coating time is 10-45s; Preferably, the coating process is: firstly spin coating the perovskite precursor solution at a speed of 1000-3000 rpm, for example, 2000 rpm for 20-30 seconds, and then spin coating the substrate at a speed of 3000-6000 rpm for 10-15 seconds; (6) 5-10 seconds before the coating is completed, adding an anti-solvent dropwise; the anti-solvent is preferably ethyl acetate; the volume ratio of the anti-solvent to the solvent is preferably (50-200):1000; (7) After adding the anti-solvent, annealing is performed; the temperature of the annealing is preferably 100-120° C.; the time of the annealing is preferably 30-40 min; (8) The method for preparing the perovskite film further comprises the following steps: after the perovskite film is formed on the surface of the substrate, removing the substrate; and, (9) The substrate is an electron transport layer; the electron transport layer preferably comprises tin dioxide or titanium dioxide.

5. A perovskite film obtained by the method for preparing a perovskite film according to claim 3 or 4.

6. A perovskite film, characterized in that: It comprises an active ingredient, the active ingredient comprising Cs x FA y MA 1-x-y PbI3; wherein FA represents formamidinium ion, MA represents methylamine ion, 0≤x≤0.05, 0.85≤y≤0.95; the average grain size of the perovskite film is 650-850nm; Preferably, it satisfies one or more of the following conditions: (1)y＝0.88； (2) The surface root mean square roughness of the perovskite film is 20-32 nm, for example, 23 nm, 25 nm or 30 nm; (3) The average grain size of the perovskite film is 700 nm, 750 nm, 800 nm or 850 nm; (4) the thickness of the perovskite film is 1000-1500 nm, for example 1320 nm; and, (5) The perovskite film is prepared by the method for preparing a perovskite film according to claim 3 or 4.

7. Use of 1-ethyl-3-guanidinothiourea hydrochloride in the preparation of a perovskite film, wherein the mass of the 1-ethyl-3-guanidinothiourea hydrochloride and the molar amount of the active ingredient in the perovskite film are (0.32-1.15) mg:1 mmol; The active ingredient preferably includes Cs x FA y MA 1-x-y PbI3; among them, FA represents formamidinium ion, MA represents methylamine ion, 0≤x≤0.05, 0.85≤y≤0.95; preferably y=0.

88.

8. A perovskite battery, characterized in that: It comprises the perovskite film as claimed in claim 5 or 6; preferably, the perovskite cell comprises a conductive substrate, an electron transport layer, the perovskite film, a hole transport layer, a buffer layer and an electrode layer stacked in sequence; more preferably, it satisfies one or more of the following conditions: (1) The conductive substrate is a transparent material, preferably comprising indium tin oxide; (2) The electron transport layer comprises tin dioxide or titanium dioxide; (3) The thickness of the electron transport layer is 10-100 nm, for example 15 nm; (4) The hole transport layer comprises 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene or poly(3-hexylthiophene); (5) The thickness of the hole transport layer is 100-300 nm, for example, 200 nm; (6) The buffer layer comprises molybdenum oxide or vanadium oxide; (7) The thickness of the buffer layer is 5-15 nm, for example, 10 nm; (8) The electrode layer is a transparent material, preferably comprising indium tin oxide or indium zinc oxide; and, (9) The thickness of the electrode layer is 100-300 nm, for example, 200 nm.

9. A method for preparing a perovskite battery as claimed in claim 8, characterized in that: It includes the following steps: S1, coating an electron transport layer precursor solution onto the conductive substrate to obtain the electron transport layer; S2, coating the precursor solution on the surface of the electron transport layer, and dropping the anti-solvent to obtain the perovskite film; S3, coating a hole transport layer precursor solution onto the surface of the perovskite film to obtain the hole transport layer; S4, evaporating a buffer layer material on the surface of the hole transport layer to obtain the buffer layer; S5. Magnetron sputtering an electrode layer material on the surface of the buffer layer to obtain an electrode layer.

10. The method for preparing a perovskite battery according to claim 9, characterized in that: It meets one or more of the following conditions: (1) In step S1, in the electron transport layer precursor solution, the volume ratio of the electron transport layer precursor to the solvent is 1:(2-3); the solvent is preferably water; (2) In step S1, the coating method is spin coating; the spin coating speed is preferably 4000-4500 rpm; the coating time is preferably 25-30 s; (3) In step S1, after coating, annealing is performed; the annealing temperature is preferably 120-150° C.; the annealing time is preferably 30-40 minutes; (4) In step S2, the coating method is spin coating; the spin coating speed is preferably 1000-6000 rpm; the coating time is preferably 10-45 s; (5) In step S2, 5-10 seconds before the end of the coating, the anti-solvent is added dropwise; (6) In step S2, after the anti-solvent is added dropwise, annealing is performed; the temperature of the annealing is preferably 100-120° C.; the time of the annealing is preferably 30-40 min; (7) In step S3, the hole transport layer precursor solution includes 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene or poly(3-hexylthiophene), 4-tert-butylpyridine, a lithium salt solution and a main solvent; the lithium salt solution is preferably a lithium bis(trifluoromethanesulfonyl)imide solution; the concentration of the lithium salt solution is preferably 500-520 mg / mL; the solvent of the lithium salt solution is preferably acetonitrile ; The mass of the 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene and the volume of the main solvent are preferably 72.3-80 mg / mL; the volume ratio of the 4-tert-butylpyridine and the main solvent is preferably (29-30):1000; the volume ratio of the lithium salt solution and the main solvent is preferably (15-17.5):1000; the main solvent is preferably chlorobenzene; (8) In step S3, the coating method is spin coating; the spin coating speed is preferably 1000-3000 rpm, such as 2000 rpm; the coating time is preferably 10-50 s, such as 30 s; (9) In step S3, after coating, drying is performed; (10) In step S4, the evaporation rate is 0.01-0.1 nm / s, for example 0.03 nm / s; and (11) In step S5, the power of the magnetron sputtering is 30-80 W, for example, 60 W.

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