Perovskite solution and preparation method and application thereof

Abstract

The invention relates to a perovskite solution and a preparation method and application thereof, the perovskite solution comprises a perovskite precursor and a composite solvent, and the composite solvent comprises 2-methoxyethanol, N-methyl pyrrolidone and N, N '-dimethyl propenyl urea. The perovskite solution provided by the invention is prepared from 2-methoxyethanol, N-methyl pyrrolidone and N, N-dimethyl formamide. According to the method, N, N '-dimethyl propenyl urea are mutually compounded to jointly induce phase equilibrium of a perovskite precursor material in a solution, conditions are provided for preparing a perovskite layer under low energy consumption, an annealing process is not needed in the subsequent perovskite layer preparation process, the preparation energy consumption and cost of the perovskite layer are effectively reduced, and the method is suitable for industrial production. And the performance of the perovskite layer is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cells, and in particular to a perovskite solution and a preparation method and application thereof. Background Art

[0002] Perovskite materials are the stars of the third generation of photovoltaic materials, which are expected to simplify the preparation process, reduce costs, and have great application potential. Perovskite materials still face some challenges, such as large-area preparation in air, phase stability, long-term stability, etc., which need to be further studied. In addition, the preparation technology of perovskite solar cells still needs to be explored in order to further improve efficiency and promote its commercial development.

[0003] With the in-depth research of perovskite materials and the continuous advancement of industrialization, the demand for preparation methods and processes of phase-stable perovskite films is increasing. In traditional perovskite preparation systems, DMF or DMSO systems are often used as solvents for preparing perovskite films. However, the DMF or DMSO systems used in the prior art will lead to the production of intermediate phase and yellow phase (δ phase) perovskite films. The presence of intermediate phase and yellow phase perovskite films will reduce the efficiency and stability of perovskite devices. The conventional method for removing intermediate phase and yellow phase perovskites is to remove excess solvents through high temperature annealing (120-150°C) to form stable black phase (α phase) perovskites.

[0004] CN117711950A discloses a method for preparing an α-phase CsPbI3 thin film, comprising the following steps:

[0005] (1) CsI and PbI2 are dissolved in a solvent to obtain a CsPbI3 precursor solution; (2) The CsPbI3 precursor solution is spin-coated on the surface of a substrate, and after a first standing, a diphenylphosphine chloride solution is added dropwise to the substrate, and after a second standing until the color of the substrate surface changes from yellow to black, the substrate is rotated; (3) The substrate is annealed to obtain the α-phase perovskite on the substrate. In this method, DMF or DMSO is used as a solvent in the preparation of the CsPbI3 precursor solution, and an annealing process is required to prepare the α-phase perovskite. However, in the process of preparing the perovskite film, the annealing process used will, on the one hand, lead to high energy consumption and high process cost of the preparation process, and on the other hand, the annealing heat treatment process will also affect the preparation and performance of the perovskite film.

[0006] Therefore, how to improve the phase equilibrium stability of perovskite films and improve their performance has become a problem that needs to be solved urgently. Summary of the invention

[0007] In order to solve the above technical problems, the purpose of the present invention is to provide a perovskite solution and a preparation method and application thereof. The perovskite solution of the present invention is compounded by 2-methoxyethanol, N-methylpyrrolidone and N,N'-dimethylpropylene urea, which jointly induce the phase equilibrium of the perovskite precursor material in the solution, providing conditions for preparing a perovskite layer with excellent performance under the condition of low energy consumption and no annealing process.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a perovskite solution, comprising a perovskite precursor and a composite solvent, wherein the composite solvent comprises 2-methoxyethanol, N-methylpyrrolidone and N,N'-dimethylpropylene urea.

[0010] The perovskite solution provided by the present invention is obtained by combining a mixed solvent of 2-methoxyethanol, N-methylpyrrolidone and N,N'-dimethylpropyleneurea with a perovskite precursor material, wherein the 2-methoxyethanol is used to dissolve the organic salt in the perovskite precursor powder, and the saturated vapor pressure of 2-methoxyethanol is relatively high, so that it can be quickly removed by flash evaporation; the N-methylpyrrolidone is used to form a complex with lead iodide in the perovskite precursor powder to form a skeleton of the perovskite; and the N,N'-dimethylpropyleneurea is used to induce low-temperature crystallization.

[0011] The perovskite solution of the present invention uses 2-methoxyethanol, N-methylpyrrolidone and N,N'-dimethylpropylene urea as a composite solvent, and the three are compounded with each other to jointly induce the phase equilibrium of the perovskite precursor material in the solution, thereby stabilizing the phase equilibrium of the perovskite solution, and providing effective conditions for forming a perovskite film layer under low energy consumption conditions. By using the perovskite solution provided by the present invention, in the subsequent process of preparing the perovskite layer, no annealing treatment is required, which can reduce the energy consumption and cost of preparing the perovskite layer, and can improve the performance of the perovskite layer itself.

[0012] Preferably, the concentration of the perovskite solution is 0.5-3 mol / L, for example, 0.5 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L or 3 mol / L.

[0013] The present invention aims to adjust the thickness of the perovskite after film formation by regulating the concentration of the perovskite solution.

[0014] Preferably, in the perovskite solution, the volume ratio of the N-methylpyrrolidone to the 2-methoxyethanol is 1:(30-50), for example, 1:30, 1:32, 1:34, 1:36, 1:38, 1:40, 1:42, 1:44, 1:46, 1:48 or 1:50, etc.

[0015] In the perovskite solution provided by the present invention, if the volume ratio of N-methylpyrrolidone to 2-methoxyethanol is too low and the amount of N-methylpyrrolidone added is relatively small, the perovskite phase after flash evaporation will not be entirely black, and there will be residual yellow phase perovskite, thereby affecting the performance of the perovskite battery; if the volume ratio of the two is too high and the amount of 2-methoxyethanol added is relatively small, the flash evaporation process will not be able to achieve the effect of drying the perovskite wet film, and post-annealing will be required to dry the crystallization.

[0016] Preferably, in the perovskite solution, the volume ratio of the N,N'-dimethylpropylene urea to the 2-methoxyethanol is 1:(100-200), for example, 1:100, 1:110, 1:120, 1:130, 1:140, 1:150, 1:160, 1:170, 1:180, 1:190 or 1:200, etc.

[0017] In the perovskite solution provided by the present invention, if the volume ratio of N,N'-dimethylpropylene urea to 2-methoxyethanol is too low and the amount of N,N'-dimethylpropylene urea added is relatively small, low-temperature crystallization cannot be effectively induced, and the perovskite phase after flash evaporation still has residual yellow phase perovskite; if the volume ratio of the two is too high and the amount of 2-methoxyethanol added is relatively small, the flash evaporation process cannot achieve the effect of drying the perovskite wet film, and post-annealing is required to dry the crystallization.

[0018] Preferably, the complex solvent further comprises dimethyl sulfoxide.

[0019] The present invention further adds dimethyl sulfoxide and N-methyl pyrrolidone into the composite solvent of the perovskite solution to cooperate with each other, aiming to prepare the perovskite thick film by introducing dimethyl sulfoxide.

[0020] Preferably, the volume ratio of the dimethyl sulfoxide to the N-methylpyrrolidone is 1:(3-5), such as 1:3, 1:3.5, 1:4, 1:4.5 or 1:5.

[0021] The content of dimethyl sulfoxide added in the present invention needs to be regulated to avoid too high a content of dimethyl sulfoxide, thereby affecting the phase equilibrium of the solution, easily producing a mesophase and a yellow phase (δ phase) perovskite film, and further affecting the performance of the subsequently prepared perovskite layer. In addition, regulating the amount of dimethyl sulfoxide added can also improve the wettability of the solution, which is beneficial to the large-area preparation of perovskite films.

[0022] Preferably, the perovskite precursor includes a first perovskite precursor and a second perovskite precursor.

[0023] Preferably, the first perovskite precursor comprises any one of cesium halide, methylamine halide or formamidine halide, or a combination of at least two thereof.

[0024] Preferably, the second perovskite precursor comprises lead halide.

[0025] Preferably, the perovskite precursor in the perovskite precursor solution contains elements satisfying the molecular formula MA a FA b Cs 1-a-b The molar ratio of each element in PbX3, wherein 0≤a≤1, 0≤b≤1, MA is methylamino, FA is methylamidine, and X is a halogen element; wherein a can be 0-1, for example, 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 or 1, etc.; b can be 0-1, for example, 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 or 1, etc.

[0026] In a second aspect, the present invention provides a method for preparing the perovskite solution according to the first aspect, the preparation method comprising the following steps:

[0027] mixing a perovskite precursor with a composite solvent to obtain a perovskite solution;

[0028] The composite solvent includes 2-methoxyethanol, N-methylpyrrolidone and N,N'-dimethylpropylene urea.

[0029] The preparation method of the titanium ore solution provided by the present invention adopts a perovskite precursor material and a composite solvent to mix, and the preparation method has a simple process and low preparation cost. The 2-methoxyethanol, N-methylpyrrolidone and N,N'-dimethylpropylene urea used are compounded with each other to stabilize the phase equilibrium of the perovskite solution, so that the perovskite layer is prepared by using the obtained perovskite solution of a specific composition, and no annealing process is required, thereby reducing the energy consumption and cost of the perovskite layer preparation, and at the same time, the performance of the perovskite layer itself can be improved.

[0030] Preferably, the mixing temperature is 20-30°C, for example, 20°C, 21°C, 22°C, 23°C, 24°C, 25°C, 26°C, 27°C, 28°C, 29°C or 30°C, etc.

[0031] Preferably, the mixing time is 2-6 h, for example, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h, 5 h, 5.5 h or 6 h.

[0032] Preferably, the mixing method includes stirring.

[0033] Preferably, the complex solvent further comprises dimethyl sulfoxide.

[0034] In a third aspect, the present invention provides a perovskite layer, wherein the perovskite layer is prepared using the perovskite solution described in the first aspect.

[0035] The perovskite layer provided by the present invention is prepared by using a perovskite solution of a specific composition and has relatively excellent phase equilibrium stability and electrochemical performance.

[0036] Preferably, the thickness of the perovskite layer is 300-1200 nm, for example, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1000 nm, 1100 nm or 1200 nm.

[0037] In a fourth aspect, the present invention provides a method for preparing the perovskite layer according to the third aspect, the preparation method comprising the following steps:

[0038] The perovskite solution described in the first aspect is coated and flash evaporated to obtain the perovskite layer.

[0039] The preparation method of the perovskite layer provided by the present invention adopts a perovskite solution of a specific composition to be prepared by a coating process combined with a flash evaporation process, and the 2-methoxyethanol, N-methylpyrrolidone and N,N'-dimethylpropylene urea used in the perovskite solution are compounded with each other to jointly induce the phase equilibrium stability of the perovskite precursor material in the perovskite solution, so that after the perovskite solution is coated, only a low-energy consumption process of flash evaporation is used to achieve the preparation of a phase-stable perovskite layer. The present invention adopts a specific perovskite solution to prepare the perovskite layer, abandons the annealing process required for the conventional preparation of the perovskite layer, can reduce the energy consumption and cost of the perovskite layer preparation, and can also effectively improve the performance of the perovskite layer itself, thereby improving the photoelectric conversion efficiency of the perovskite device.

[0040] Preferably, the coating method includes any one of a blade coating method or a slit coating method.

[0041] Preferably, the specific process of the flash evaporation includes: evacuating the coated perovskite solution, and allowing the solute in the perovskite solution to crystallize into a film to obtain the perovskite layer.

[0042] The present invention uses a flash evaporation process to quickly evacuate the coated perovskite solution, and adopts a non-annealing process to volatilize the composite solvent in the perovskite solution, so that the solute in the perovskite solution can crystallize into a film, thereby preparing a perovskite layer with good stability and excellent electrochemical performance.

[0043] Preferably, the vacuuming time is 5-20 s, such as 5 s, 10 s, 15 s or 20 s.

[0044] Preferably, the vacuum is evacuated to a vacuum degree of less than 0.05 Pa, such as 0.05 Pa, 0.04 Pa, 0.03 Pa, 0.02 Pa or 0.01 Pa.

[0045] The present invention regulates the vacuuming time and vacuum degree in the flash evaporation process, quickly evacuates the vacuum to a specific vacuum degree in a relatively short time, realizes rapid volatilization of the solvent in the coated perovskite solution, improves the crystallization film-forming effect of the solute in the perovskite solution, and thus prepares an α-phase perovskite layer with good stability and excellent electrochemical performance.

[0046] In a fifth aspect, the present invention provides a perovskite solar cell, wherein the perovskite solar cell comprises the perovskite layer described in the third aspect.

[0047] The present invention uses a perovskite layer prepared from a perovskite solution having a specific composition in a perovskite solar cell, which can improve the photoelectric conversion efficiency and electrochemical stability of the perovskite solar cell.

[0048] Preferably, the perovskite solar cell comprises a substrate layer, a hole transport layer, the perovskite layer, an electron transport layer and an electrode layer which are stacked in sequence.

[0049] Preferably, a hole blocking layer is further provided between the electron transport layer and the electrode layer.

[0050] The other layers in the perovskite solar cell formed by the perovskite layer prepared from the specific perovskite solution provided by the present invention are all of conventional composition and structure, and the compositions and structures of the substrate layer, hole transport layer, electron transport layer, hole blocking layer and electrode layer in the perovskite solar cell obtained by technicians in this field within a reasonable range are all applicable to the present invention.

[0051] Exemplarily, the composition and structure of each layer in the perovskite solar cell provided by the present invention are as follows:

[0052] The material of the base layer includes an ITO glass substrate, and the thickness thereof is 40-80 nm, for example, 40 nm, 50 nm, 60 nm, 70 nm or 80 nm.

[0053] The material of the hole transport layer includes NiO, and the thickness thereof is 15-25 nm, for example, 15 nm, 16 nm, 17 nm, 18 nm, 19 nm, 20 nm, 21 nm, 22 nm, 23 nm, 24 nm or 25 nm.

[0054] The material of the electron transport layer includes C 60 , and its thickness is 25-35nm, for example, 25nm, 26nm, 27nm, 28nm, 29nm, 30nm, 31nm, 32nm, 33nm, 34nm or 35nm, etc.

[0055] The hole blocking layer is made of SnO2 and has a thickness of 5-15 nm, such as 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 11 nm, 12 nm, 13 nm, 14 nm or 15 nm.

[0056] The material of the electrode layer includes Cu, and the thickness thereof is 130-150 nm, for example, 130 nm, 135 nm, 140 nm, 145 nm or 150 nm.

[0057] The preparation methods of the substrate layer, hole transport layer, electron transport layer, hole blocking layer and electrode layer in the perovskite solar cell provided in the present invention are all conventional methods, and the preparation processes of the above-mentioned layer structures obtained within a reasonable range by those skilled in the art are all applicable to the present invention.

[0058] Illustratively, the preparation methods of the substrate layer, hole transport layer, electron transport layer, hole blocking layer and electrode layer in the perovskite solar cell provided by the present invention are as follows: the substrate layer is obtained by washing with acetone, water and isopropanol and then drying; the preparation method of the hole transport layer includes any one of spin coating, scraper coating or slit coating or a combination of at least two of them; the preparation method of the electron transport layer includes thermal evaporation coating; the preparation method of the hole blocking layer includes atomic deposition; the preparation method of the electrode layer includes thermal evaporation coating.

[0059] Compared with the prior art, the present invention has at least the following beneficial effects:

[0060] (1) The perovskite solution of the present invention uses 2-methoxyethanol, N-methylpyrrolidone and N,N'-dimethylpropylene urea as a composite solvent, and the three are compounded with each other to jointly induce the phase equilibrium of the perovskite precursor material in the solution, thereby stabilizing the phase equilibrium of the perovskite solution, and providing effective conditions for forming a perovskite film layer under low energy consumption conditions. By using the perovskite solution provided by the present invention, in the subsequent process of preparing the perovskite layer, no annealing treatment is required, which can reduce the energy consumption and cost of preparing the perovskite layer, and can improve the performance of the perovskite layer itself.

[0061] (2) The preparation method of the perovskite layer provided by the present invention is prepared by a coating process combined with a flash evaporation process using a perovskite solution of a specific composition. The 2-methoxyethanol, N-methylpyrrolidone and N,N'-dimethylpropyleneurea used in the perovskite solution are compounded with each other to jointly induce the phase equilibrium stability of the perovskite precursor material in the perovskite solution, so that after the perovskite solution is coated, only a low-energy consumption process of flash evaporation is used to achieve the preparation of a phase-stable perovskite layer. The present invention uses a specific perovskite solution to prepare the perovskite layer, abandons the annealing process required for the conventional preparation of the perovskite layer, can reduce the energy consumption and cost of the perovskite layer preparation, and can also effectively improve the performance of the perovskite layer itself, thereby improving the photoelectric conversion efficiency of the perovskite device. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 It is an X-ray diffraction spectrum of the perovskite layer obtained in the preparation process of the perovskite solar cell provided in Application Example 1, Comparative Application Example 2 and Comparative Application Example 3. DETAILED DESCRIPTION

[0063] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and through specific implementation methods. However, the following examples are only simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0064] Example 1

[0065] The present embodiment provides a perovskite solution, including a perovskite precursor and a composite solvent, wherein the composite solvent includes 2-methoxyethanol, N-methylpyrrolidone and N,N'-dimethylpropylene urea, the volume ratio of N-methylpyrrolidone to 2-methoxyethanol is 1:40, the volume ratio of N,N'-dimethylpropylene urea to 2-methoxyethanol is 1:160, the perovskite precursor is composed of CsI, MABr, FAI, PbI2 and PbBr2, and the content of the components in the precursor material meets the MABr content. 0.05 Cs 0.05 FA 0.9 Pb(I 0.95 Br 0.05 )3, the molar ratio of each element, the concentration of the perovskite solution is 1 mol / L.

[0066] The present embodiment provides a method for preparing the above-mentioned perovskite solution, including: mixing CsI, MABr, FAI, PbI2 and PbBr2 according to the above-mentioned formula, adding a composite solvent consisting of 2-methoxyethanol, N-methylpyrrolidone and N,N'-dimethylpropylene urea, stirring and mixing at 25°C for 4 hours to fully dissolve the mixture, and obtaining a perovskite solution.

[0067] Example 2

[0068] The present embodiment provides a perovskite solution, including a perovskite precursor and a composite solvent, wherein the composite solvent includes 2-methoxyethanol, N-methylpyrrolidone, N,N'-dimethylpropylene urea and dimethyl sulfoxide, the volume ratio of N-methylpyrrolidone to 2-methoxyethanol is 1:30, the volume ratio of N,N'-dimethylpropylene urea to 2-methoxyethanol is 1:100, the volume ratio of dimethyl sulfoxide to N-methylpyrrolidone is 1:3, the perovskite precursor is composed of CsI, MABr, FAI, PbI2 and PbBr2, and the content of the components in the precursor material meets the MABr content. 0.1 Cs 0.1 FA 0.8 Pb(I 0.9 Br 0.1 )3, the molar ratio of each element, the concentration of the perovskite solution is 1 mol / L.

[0069] The present embodiment provides a method for preparing the above-mentioned perovskite solution, comprising: mixing CsI, MABr, FAI, PbI2 and PbBr2 according to the above-mentioned formula, and adding a composite solvent consisting of 2-methoxyethanol, N-methylpyrrolidone, N,N'-dimethylpropylene urea and dimethyl sulfoxide, stirring and mixing at 30°C for 2h to fully dissolve the mixture, thereby obtaining a perovskite solution.

[0070] Example 3

[0071] The present embodiment provides a perovskite solution, including a perovskite precursor and a composite solvent, wherein the composite solvent includes 2-methoxyethanol, N-methylpyrrolidone and N,N'-dimethylpropylene urea, the volume ratio of N-methylpyrrolidone to 2-methoxyethanol is 1:50, the volume ratio of N,N'-dimethylpropylene urea to 2-methoxyethanol is 1:150, the perovskite precursor is composed of CsI, MABr, FAI, PbI2 and PbBr2, and the content of the components in the precursor material meets the MABr content. 0.05 Cs 0.1 FA 0.85 Pb(I 0.85 Br 0.15 )3, the molar ratio of each element, the concentration of the perovskite solution is 1 mol / L.

[0072] The present embodiment provides a method for preparing the above-mentioned perovskite solution, including: mixing CsI, MABr, FAI, PbI2 and PbBr2 according to the above-mentioned formula, adding a composite solvent consisting of 2-methoxyethanol, N-methylpyrrolidone and N,N'-dimethylpropylene urea, stirring and mixing at 20°C for 6 hours to fully dissolve the mixture, and obtaining a perovskite solution.

[0073] Example 4

[0074] The difference between this embodiment and embodiment 1 is that in the perovskite solution provided in this embodiment, the volume ratio of N-methylpyrrolidone to 2-methoxyethanol is 1:60. The rest of the contents are the same as those in embodiment 1.

[0075] Example 5

[0076] The difference between this embodiment and embodiment 1 is that in the perovskite solution provided in this embodiment, the volume ratio of N-methylpyrrolidone to 2-methoxyethanol is 1:20. The rest of the contents are the same as those in embodiment 1.

[0077] Example 6

[0078] The difference between this embodiment and embodiment 1 is that in the perovskite solution provided in this embodiment, the volume ratio of N,N'-dimethylpropylene urea to 2-methoxyethanol is 1:210. The rest of the contents are the same as those in embodiment 1.

[0079] Example 7

[0080] The difference between this embodiment and embodiment 1 is that in the perovskite solution provided in this embodiment, the volume ratio of N,N'-dimethylpropylene urea to 2-methoxyethanol is 1:90. The rest of the contents are the same as those in embodiment 1.

[0081] Example 8

[0082] The difference between this embodiment and embodiment 2 is that in the perovskite solution provided in this embodiment, the volume ratio of dimethyl sulfoxide to N-methylpyrrolidone is 1:0.2. The rest of the contents are the same as those in embodiment 2.

[0083] Example 9

[0084] The difference between this embodiment and embodiment 1 is that the concentration of the perovskite solution provided in this embodiment is 0.1 mol / L. The rest of the contents are the same as those in embodiment 1.

[0085] Example 10

[0086] The difference between this embodiment and embodiment 1 is that the concentration of the perovskite solution provided in this embodiment is 4 mol / L. The rest of the contents are the same as those in embodiment 1.

[0087] Comparative Example 1

[0088] The difference between this comparative example and Example 1 is that 2-methoxyethanol is omitted in the perovskite solution provided in this comparative example. The rest of the contents are the same as those in Example 1.

[0089] Comparative Example 2

[0090] The difference between this comparative example and Example 1 is that N,N'-dimethylpropylene urea is omitted in the perovskite solution provided in this comparative example. The rest of the contents are the same as those in Example 1.

[0091] Comparative Example 3

[0092] The difference between this comparative example and Example 1 is that N-methylpyrrolidone is omitted in the perovskite solution provided in this comparative example. The rest of the contents are the same as those in Example 1.

[0093] Application Example 1

[0094] This application example provides a method for preparing a perovskite solar cell, comprising the following steps:

[0095] S1. An ITO glass substrate with a thickness of 50 nm was cleaned with acetone, deionized water and isopropanol in sequence, and dried with a nitrogen gun. Then, a layer of NiO with a thickness of 20 nm was prepared on the ITO glass substrate by spin coating to obtain a hole transport layer.

[0096] S2. The perovskite solution provided in Example 1 is coated on the surface of the hole transport layer obtained in step S2 away from the ITO substrate by a slit coating method, and then placed in a vacuum drying device. By rapid vacuuming, that is, vacuuming the device to a vacuum degree of 0.05 Pa within 20 seconds, the solute in the perovskite solution is crystallized into a film to obtain a perovskite layer with a thickness of 500 nm.

[0097] S3. A layer of C with a thickness of 30 nm is deposited on the surface of the perovskite layer obtained in step S2 away from the hole transport layer by thermal evaporation coating method. 60 , an electron transport layer is obtained, and then a layer of tin dioxide with a thickness of 10 nm is grown on the surface of the electron transport layer away from the perovskite layer by atomic layer deposition to obtain a hole blocking layer.

[0098] S4. A layer of Cu with a thickness of 150 nm is deposited on the surface of the hole blocking layer obtained in step S3 away from the electron transport layer by thermal evaporation to obtain a metal electrode layer, thereby preparing a perovskite solar cell.

[0099] Application Example 2

[0100] The difference between this application example and application example 1 is that in step S2 of the method for preparing a perovskite solar cell provided in this application example, the vacuum degree of the equipment is evacuated to 0.04 Pa within 5 seconds, so that the solute in the perovskite solution is crystallized into a film. The rest is the same as application example 1.

[0101] Application Example 3

[0102] The difference between this application example and application example 1 is that in step S2 of the method for preparing a perovskite solar cell provided in this application example, the vacuum degree of the equipment is evacuated to 0.03 Pa within 15 seconds, so that the solute in the perovskite solution is crystallized into a film. The rest is the same as application example 1.

[0103] Application Example 4

[0104] The method for preparing a perovskite solar cell provided in this application example is the same as that of application example 1, except that the perovskite solution in step S2 uses the perovskite solution provided in embodiment 2.

[0105] Application Example 5

[0106] The method for preparing a perovskite solar cell provided in this application example is the same as that of application example 1, except that the perovskite solution in step S2 uses the perovskite solution provided in embodiment 3.

[0107] Application Example 6

[0108] The method for preparing a perovskite solar cell provided in this application example is the same as that of application example 1, except that the perovskite solution in step S2 uses the perovskite solution provided in embodiment 4.

[0109] Application Example 7

[0110] The method for preparing a perovskite solar cell provided in this application example is the same as that of application example 1, except that the perovskite solution in step S2 uses the perovskite solution provided in embodiment 5.

[0111] Application Example 8

[0112] The method for preparing a perovskite solar cell provided in this application example is the same as that of application example 1, except that the perovskite solution in step S2 uses the perovskite solution provided in embodiment 6.

[0113] Application Example 9

[0114] The method for preparing a perovskite solar cell provided in this application example is the same as that of application example 1, except that the perovskite solution in step S2 uses the perovskite solution provided in embodiment 7.

[0115] Application Example 10

[0116] The method for preparing a perovskite solar cell provided in this application example is the same as that of application example 4, except that the perovskite solution in step S2 uses the perovskite solution provided in embodiment 8.

[0117] Application Example 11

[0118] The method for preparing a perovskite solar cell provided in this application example is the same as that in application example 1, except that the perovskite solution in step S2 uses the perovskite solution provided in embodiment 9 and the thickness of the corresponding perovskite layer obtained is 50 nm.

[0119] Application Example 12

[0120] The method for preparing a perovskite solar cell provided in this application example is the same as that in application example 1, except that the perovskite solution in step S2 uses the perovskite solution provided in embodiment 10 and the thickness of the corresponding perovskite layer obtained is 2000 nm.

[0121] Application Example 13

[0122] The difference between this application example and the application example is that the preparation method of the perovskite solar cell provided in this application example, the preparation process of the perovskite layer in step S2 adopts a slow vacuuming method, that is, the vacuum is evacuated within 1 minute until the vacuum degree of the equipment is 0.05 Pa. The rest is the same as the application example 1.

[0123] Comparative application example 1

[0124] This comparative application example provides a method for preparing a perovskite solar cell. Except that the perovskite solution in step S2 uses the perovskite solution provided in comparative example 1, the rest is the same as that in application example 1.

[0125] Comparative Application Example 2

[0126] This comparative application example provides a method for preparing a perovskite solar cell. Except that the perovskite solution in step S2 uses the perovskite solution provided in comparative example 2, the rest is the same as that in application example 1.

[0127] Comparative Application Example 3

[0128] This comparative application example provides a method for preparing a perovskite solar cell. Except that the perovskite solution in step S2 uses the perovskite solution provided in comparative example 3, the rest is the same as that in application example 1.

[0129] Performance Testing

[0130] The perovskite solar cells prepared in Application Examples 1-13 and Comparative Application Examples 1-3 were subjected to performance tests, and the open circuit voltage (Voc), photoelectric conversion efficiency (PCE), short circuit current density (Jsc), and fill factor (FF) were recorded. The test method was to use an IV test system for forward scanning and set the step size to 0.5 V / S. The test results are shown in Table 1.

[0131] Table 1

[0132] Open circuit voltage(V) Photoelectric conversion efficiency (%) <![CDATA[Short-circuit current density (mA / cm 3 )]]> Fill factor (%) Application Example 1 1.03 13.91 20.77 0.65 Application Example 2 1.01 13.96 20.78 0.67 Application Example 3 1.04 13.96 20.76 0.65 Application Example 4 1.02 14.07 20.83 0.66 Application Example 5 1.02 14.18 20.71 0.67 Application Example 6 1.02 13.14 19.59 0.66 Application Example 7 1.01 12.37 19.66 0.62 Application Example 8 1.00 12.99 19.92 0.65 Application Example 9 1.01 13.43 19.71 0.67 Application Example 10 1.01 11.50 18.82 0.61 Application Example 11 1.00 5.73 9.6 0.60 Application Example 12 0.51 3.43 11.24 0.61 Application Example 13 0.93 11.47 20.82 0.59 Comparative application example 1 1.01 11.05 19.03 0.57 Comparative Application Example 2 1.00 11.06 18.29 0.60 Comparative Application Example 3 1.00 11.15 18.40 0.60

[0133] The test results show that:

[0134] (1) It can be seen from Application Examples 1 to 5 that the perovskite solution of the present invention, through the mutual cooperation of various substances in the composite solvent, jointly induces the phase equilibrium of the perovskite precursor material in the solution, forms a perovskite layer with excellent performance under low energy consumption conditions, thereby improving the electrochemical performance of the perovskite solar cell.

[0135] (2) By comparing Application Example 1 with Application Examples 6-7, it can be seen that in the perovskite solution provided by the present invention, if the volume ratio of N-methylpyrrolidone to 2-methoxyethanol is too low and the amount of N-methylpyrrolidone added is relatively small, the quality of perovskite crystallization will decrease, resulting in a decrease in the performance of the perovskite solar cell; if the volume ratio of the two is too high and the amount of 2-methoxyethanol added is relatively small, the solvent will not evaporate completely, thereby affecting the performance of the perovskite solar cell.

[0136] (3) By comparing Application Example 1 with Application Examples 8-9, it can be seen that in the perovskite solution provided by the present invention, if the volume ratio of N,N'-dimethylpropylene urea to 2-methoxyethanol is too low and the amount of N,N'-dimethylpropylene urea added is relatively small, low-temperature crystallization cannot be effectively induced, and the perovskite phase after flash evaporation is not entirely black, and there are residual yellow phase perovskite, thereby reducing the current density of the perovskite battery; if the volume ratio of the two is too high and the amount of 2-methoxyethanol added is relatively small, the flash evaporation process cannot achieve the effect of drying the perovskite wet film, thereby affecting the performance of the perovskite battery.

[0137] (4) By comparing Application Example 4 and Application Example 10, it can be seen that the present invention can prepare high-quality perovskite by adding a specific content of dimethyl sulfoxide; if the amount of dimethyl sulfoxide added to the composite solvent is too high, it will lead to the inability to directly form black phase perovskite, and the current density of the obtained perovskite solar cell will decrease.

[0138] (5) By comparing Application Example 1 with Application Examples 11-12, it can be seen that if the concentration of the perovskite solution of the present invention is too low, the prepared perovskite film will be thinner, thereby reducing the current density of the perovskite solar cell, reducing the photoelectric conversion efficiency, and deteriorating the device performance; if the concentration of the perovskite solution is too high, it will lead to a decrease in crystallization quality, and the carriers cannot be effectively extracted, thereby deteriorating the performance of the battery.

[0139] (6) By comparing Application Example 1 and Application Example 13, it can be seen that if the present invention adopts a slow vacuuming process after coating the perovskite solution, it will cause the perovskite solution to have more naturally volatile components and an unbalanced solvent ratio, thereby causing the fill factor of the resulting solar cell to decrease significantly.

[0140] (7) By comparing Application Example 1 with Comparative Application Example 1, it can be seen that if 2-methoxyethanol is omitted from the perovskite solution provided by the present invention, the crystallization will be too slow due to the absence of volatile 2-methoxyethanol, thereby reducing the performance of the constructed perovskite solar cell.

[0141] (8) By comparing Application Example 1 with Comparative Application Example 2, it can be seen that if N,N'-dimethylpropylene urea is omitted in the perovskite solution provided by the present invention, it will lead to the inability to effectively induce the complete formation of black phase perovskite, and there will be yellow phase perovskite remaining, thereby reducing the current density of the constructed perovskite solar cell and deteriorating the performance.

[0142] (9) It can be seen from Application Example 1 and Comparative Application Example 3 that if N-methylpyrrolidone is omitted from the perovskite solution provided by the present invention, it will lead to the inability to effectively induce the complete formation of black phase perovskite, and yellow phase perovskite will remain, which will deteriorate the electrochemical performance of the obtained perovskite solar cell.

[0143] Figure 1 The X-ray diffraction patterns of the perovskite layers obtained in the preparation process of the perovskite solar cells provided in Application Example 1, Comparative Application Example 2 and Comparative Application Example 3 are given. It can be seen from the figure that the perovskite solutions used in the preparation of the perovskite layers provided in Comparative Application Example 2 and Comparative Application Example 3 do not contain N,N'-dimethylpropylene urea (corresponding to the perovskite solution provided in Comparative Application Example 2) and N-methylpyrrolidone (corresponding to the perovskite solution provided in Comparative Application Example 3), respectively, and the X-ray diffraction patterns of the two have a wavelength of 12.5° or less. The production of lead iodide and yellow phase perovskite proves that under the perovskite solutions provided in Comparative Examples 2 and 3, pure black phase perovskite cannot be obtained by flash evaporation and formula matching, and high temperature annealing must be used to induce subsequent perovskite phase change; while for the perovskite layer preparation provided in Application Example 1, the perovskite solution used contains a composite solvent of 2-methoxyethanol, N-methylpyrrolidone and N,N'-dimethylpropylene urea, and a pure black phase (α phase) perovskite layer can still be formed without annealing.

[0144] In summary, the perovskite solution of the present invention uses 2-methoxyethanol, N-methylpyrrolidone and N,N'-dimethylpropylene urea as a composite solvent, and the three are compounded with each other to jointly induce the phase equilibrium of the perovskite precursor material in the solution, thereby stabilizing the phase equilibrium of the perovskite solution, and providing effective conditions for forming a perovskite film layer under low energy consumption conditions. Using the perovskite solution provided by the present invention, in the subsequent process of preparing the perovskite layer, no annealing treatment is required, the energy consumption and cost of the preparation are reduced, and the performance of the perovskite layer itself can be improved, thereby effectively improving the electrochemical performance of the solar cell composed of the perovskite layer.

[0145] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A perovskite solution, characterized in that: The perovskite solution comprises a perovskite precursor and a composite solvent, wherein the composite solvent comprises 2-methoxyethanol, N-methylpyrrolidone and N,N'-dimethylpropylene urea.

2. The perovskite solution according to claim 1, characterized in that The concentration of the perovskite solution is 0.5-3 mol / L; Preferably, in the perovskite solution, the volume ratio of the N-methylpyrrolidone to the 2-methoxyethanol is 1:(30-50); Preferably, in the perovskite solution, the volume ratio of the N,N'-dimethylpropylene urea to the 2-methoxyethanol is 1:(100-200); Preferably, the composite solvent further comprises dimethyl sulfoxide; Preferably, the volume ratio of the dimethyl sulfoxide to the N-methylpyrrolidone is 1:(3-5).

3. The perovskite solution according to claim 1 or 2, characterized in that: The perovskite precursor includes a first perovskite precursor and a second perovskite precursor; Preferably, the first perovskite precursor comprises any one of cesium halide, methylamine halide or formamidine halide, or a combination of at least two thereof; Preferably, the second perovskite precursor comprises lead halide; Preferably, the perovskite precursor in the perovskite precursor solution contains elements satisfying the molecular formula MA a FA b Cs 1-a- b The molar ratio of each element in PbX3, wherein 0≤a≤1, 0≤b≤1, MA is methylamino, FA is methylamidine, and X is a halogen element.

4. A method for preparing a perovskite solution according to any one of claims 1 to 3, characterized in that: The preparation method comprises the following steps: mixing a perovskite precursor with a composite solvent to obtain a perovskite solution; The composite solvent includes 2-methoxyethanol, N-methylpyrrolidone and N,N'-dimethylpropylene urea.

5. The method for preparing a perovskite solution according to claim 4, characterized in that: The mixing temperature is 20-30°C; Preferably, the mixing time is 2-6h; Preferably, the mixing method includes stirring; Preferably, the complex solvent further comprises dimethyl sulfoxide.

6. A perovskite layer, characterized in that: The perovskite layer is prepared by using the perovskite solution according to any one of claims 1 to 3; Preferably, the thickness of the perovskite layer is 300-1200 nm.

7. A method for preparing a perovskite layer according to claim 6, characterized in that: The preparation method comprises the following steps: The perovskite solution according to any one of claims 1 to 3 is coated and flash evaporated to obtain the perovskite layer.

8. The method for preparing a perovskite layer according to claim 7, characterized in that: The coating method includes any one of a blade coating method or a slit coating method; Preferably, the specific process of the flash evaporation includes: evacuating the coated perovskite solution, so that the solute in the perovskite solution crystallizes into a film to obtain the perovskite layer; Preferably, the vacuuming time is 5-20s; Preferably, the vacuum is evacuated to a vacuum degree below 0.05 Pa.

9. A perovskite solar cell, characterized in that: The perovskite solar cell comprises the perovskite layer according to claim 6.

10. The perovskite solar cell according to claim 9, characterized in that: The perovskite solar cell comprises a substrate layer, a hole transport layer, the perovskite layer, an electron transport layer and an electrode layer which are stacked in sequence; Preferably, a hole blocking layer is further provided between the electron transport layer and the electrode layer.

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