A stable printable formamidinium-based perovskite ink and a method for preparing a photovoltaic module thereof

Abstract

The application discloses a kind of stable printable formamidinium-based perovskite ink and photovoltaic module preparation method thereof, the formamidinium-based perovskite ink includes formamidinium-based perovskite, low volatility coordination solvent, high volatility non-coordination solvent and stabilizer;The stabilizer is the organic cesium salt with good solubility in the low volatility coordination solvent and the high volatility non-coordination solvent.The formamidinium-based perovskite ink provided by the application uses the organic cesium salt with good solubility as stabilizer, by introducing organic acid root, reduces the formation energy of photoactive black phase (alpha phase), induces the pure phase stable growth of photoactive black phase formamidinium-based perovskite, to realize the controllable preparation of high-efficiency stable large-area perovskite thin film and photovoltaic module.

Description

Technical Field

[0001] This invention belongs to the field of perovskite solar cell technology, specifically relating to a stable and printable formamidinium-based perovskite ink and its photovoltaic module preparation method. Background Technology

[0002] Efficiently utilizing solar energy resources is an effective way to achieve green, low-carbon, and sustainable development. Solar cells, as an advanced technology for efficiently utilizing solar energy resources, have evolved from first-generation crystalline silicon solar cells and second-generation thin-film solar cells such as gallium arsenide, cadmium telluride, and copper indium gallium selenide to the current third-generation novel thin-film solar cells, including organic, quantum dot, and perovskite solar cells. Solar cells are gradually developing towards lower-cost, higher-efficiency photovoltaic devices, giving them broader application prospects and core competitiveness.

[0003] Perovskite solar cells, as one of the most promising emerging photovoltaic technologies, possess excellent photoelectric performance and commercial application prospects. In particular, perovskite solar cells with formamidinium-based lead-iodine compounds as the main component exhibit a more ideal optical bandgap and superior photovoltaic characteristics, and have already achieved small-area (~0.1 cm²) perovskite solar cells. 2 The device's photoelectric conversion efficiency has exceeded 26.1%, which is comparable to that of traditional crystalline silicon solar cells. It also has significant advantages in manufacturing process and production cost, further highlighting its industrial application value. However, promoting the industrialization of perovskite still requires solving the problem of large-area preparation of high-efficiency and stable perovskite solar cells.

[0004] Currently, a series of research projects have been launched for the fabrication of large-area perovskite solar cell modules. However, due to problems such as uncontrollable crystallization, film inhomogeneity, film non-density, and a significant increase in surface defects during the scale-up process of perovskite films, the performance of perovskite solar cells decreases significantly with the increase of perovskite film area. In particular, during the preparation of formamidinium-based perovskite films, its nucleation and crystallization behavior is difficult to control effectively, and non-optically active phase transformations are prone to occur during growth, resulting in poor film quality and more significant performance degradation during scale-up. Therefore, developing a controllable printable formamidinium-based perovskite precursor ink to achieve stable pure-phase growth of large-area perovskite is crucial. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a stable and printable formamidinium-based perovskite ink and a method for preparing photovoltaic modules therewith, which addresses the shortcomings of the prior art. The nucleation and crystallization of the formamidinium-based perovskite ink are controllable during the preparation of formamidinium-based perovskite thin films, and the performance of the formamidinium-based perovskite solar cells prepared by it does not decrease as the area of ​​the perovskite thin film increases. At the same time, the preparation method is simple and suitable for widespread application.

[0006] The technical solution adopted by the present invention to solve the above-mentioned problems is as follows:

[0007] A stable printable formamidinium-based perovskite ink, comprising formamidinium-based perovskite, a low-volatility coordinating solvent, a high-volatility non-coordinating solvent, and a stabilizer; the stabilizer is an organic cesium salt having good solubility in both the low-volatility coordinating solvent and the high-volatility non-coordinating solvent.

[0008] In the above solution, the molar ratio of the stabilizer to the formamidinium-based perovskite is 1:(10 - 1000).

[0009] In the above solution, the molar concentration of the formamidinium-based perovskite in the formamidinium-based perovskite ink is 0.1M - 2.0M; the volume ratio of the high-volatility non-coordinating solvent to the low-volatility coordinating solvent is (1 - 100):1.

[0010] In the above solution, the formamidinium-based perovskite has a ABX3 structure, where A consists of FA with a content of m + and other ions with a content of n, and the other ions are K + , Rb + , Cs + , MA + (methylamine), EA + (ethylamine), GA + (guanidine), RNH3 + (long-chain alkylamine), and 70% < m ≤ 100%, 0 ≤ n ≤ 30%; B is at least one of Pb 2+ , Sn 2+ ; X is at least one of Cl - , Br - , I - .

[0011] In the above solution, the organic cesium salt is one or more of cesium formate, cesium acetate, cesium trifluoroacetate, cesium propionate, cesium trifluoropropionate, cesium pentafluoropropionate, cesium butyrate, cesium trifluorobutyrate, cesium isobutyrate, cesium perfluoroisobutyrate, cesium perfluorobutyrate, cesium methanesulfonate, cesium pivalate, cesium oxalate.

[0012] In the above solution, the low-volatility coordinating solvent is one or more of N-methylpyrrolidone (NMP), dimethyl sulfoxide (DMSO), dimethylacetamide (DMA), N,N-dimethylformamide (DMF), 1,3-dimethyl-2-imidazolidinone (DMI), γ-butyrolactone (GBL), N,N-dimethylpropyleneurea (DMPU), hexamethylphosphoric triamide (HMPA).

[0013] In the above scheme, the highly volatile noncoordinating solvent is one or more of ethylene glycol methyl ether (2-Me), acetonitrile (ACN), tetrahydrofuran (THF), ethanol (EtOH), isopropanol (IPA), butanol (BA), isobutanol (iBA), tert-butanol (tBA), and 1,2-dimethoxyethane (DME).

[0014] This invention also claims protection for a formamidinium-based perovskite photovoltaic module, comprising: a transparent conductive substrate, an electron transport layer, a perovskite light-absorbing layer, a hole transport layer, and a top electrode, wherein the perovskite light-absorbing layer is a formamidinium-based perovskite thin film prepared by any one of the following processing methods: spin coating, blade coating, slot coating, spraying, or inkjet printing; wherein the structure of the formamidinium-based perovskite cell includes a nip formal structure and a pin inverse structure.

[0015] The above-mentioned method for preparing a formamidinium-based perovskite photovoltaic module includes the following steps:

[0016] 1) Use laser etching to etch a transparent conductive substrate;

[0017] 2) Fabrication of formamidinium-based perovskite photovoltaic modules with nip formal structure: An electron transport layer, a perovskite light-absorbing layer, and a hole transport layer are sequentially fabricated on the transparent conductive substrate obtained in step 1); wherein the electron transport layer is fabricated by chemical bath deposition or blade coating, and the hole transport layer is fabricated by spin coating or blade coating.

[0018] To prepare a pin-structured formamidinium-based perovskite photovoltaic module, a hole transport layer, a perovskite light-absorbing layer, and an electron transport layer are sequentially prepared on the conductive substrate obtained in step 1). The hole transport layer is prepared by spin coating or blade coating, and the electron transport layer is prepared by spin coating, blade coating, or vapor deposition.

[0019] 3) The top electrode is prepared by vacuum evaporation to obtain the formamidinium-based perovskite photovoltaic module.

[0020] The above solution also includes the following steps:

[0021] 4) Fabricate formamidinium-based perovskite photovoltaic module sub-cells. Use a laser to scribing lines to open pathways between the top electrode and the transparent conductive substrate of adjacent formamidinium-based perovskite photovoltaic module sub-cells, namely P1, P2 and P3.

[0022] This invention uses an organic cesium salt, which has good solubility in both low-volatility coordination solvents and high-volatility non-coordination solvents, as a stabilizer. By introducing organic acid anions, the formation energy of the photoactive black phase (α phase) is reduced, the phase transition kinetics are increased, and the pure-phase stable growth of the optically active black phase formamidinium perovskite is induced. The dissociation energy of the photoactive black phase is enhanced, thereby achieving efficient and stable large-area formamidinium perovskite thin films and their controllable preparation in photovoltaic modules.

[0023] Compared with existing technologies, the beneficial effects of this invention are:

[0024] (1) The present invention provides a stable and printable formamidine perovskite ink. The nucleation and crystallization of the formamidine perovskite ink can be controlled during the preparation of formamidine perovskite thin films. It is not easy for non-optically active phase transformation to occur during the growth process. The prepared thin film is uniform, dense and free of surface and interface defects.

[0025] (2) The preparation method provided by the present invention is simple and suitable for widespread application. Attached Figure Description

[0026] Figure 1 This is a structural diagram of a formamidin-based large-area perovskite solar cell prepared according to the present invention.

[0027] Figure 2 Photographs showing the solubility of 1 mmol of a commonly used Cs salt in 1 mL of 2-Me and DMF solvents.

[0028] Figure 3 These are scanning electron microscope images of the perovskite thin films prepared in Example 1 and Comparative Example 1 of the present invention.

[0029] Figure 4 The images show the X-ray diffraction patterns of the perovskite thin films prepared in Example 1 and Comparative Example 1 of this invention.

[0030] Figure 5 The JV curves are for the photovoltaic modules prepared in Example 1 and Comparative Example 1 of this invention.

[0031] Figure 6 This is a scanning electron microscope image of the perovskite thin film prepared in Example 2 of the present invention.

[0032] Figure 7 The image shows the JV curve of the photovoltaic module prepared in Example 2 of this invention.

[0033] Figure 8 This is a scanning electron micrograph of the photovoltaic module prepared in Example 2 of the present invention.

[0034] Figure 9 The image shows the JV curve of the photovoltaic module prepared in Example 3 of this invention.

[0035] Figure 10 This is a scanning electron microscope image of the perovskite thin film prepared in Example 4 of the present invention.

[0036] Figure 11 This is a JV curve diagram of the photovoltaic module prepared in Example 4 of the present invention.

[0037] Figure 12 This is a scanning electron micrograph of the photovoltaic module prepared in Example 4 of the present invention.

[0038] Figure 13 This is a scanning electron microscope image of the perovskite thin film prepared in Example 5 of the present invention.

[0039] Figure 14 The image shows the JV curve of the photovoltaic module prepared in Example 5 of this invention.

[0040] Figure 15 The image shows the JV curve of the photovoltaic module prepared in Example 6 of this invention.

[0041] Figure 16 This is a photograph of the photovoltaic module prepared in Embodiment 6 of the present invention.

[0042] Figure 17 The image shows the JV curve of the photovoltaic module prepared in Example 7 of this invention.

[0043] Figure 18 This is a photograph of the photovoltaic module prepared in Example 7 of the present invention.

[0044] Figure 19 The JV curve is shown for the photovoltaic module prepared in Example 8 of this invention.

[0045] Figure 20 The images show the X-ray diffraction patterns of the perovskite thin films prepared in Example 9 and Comparative Example 2 of this invention. Detailed Implementation

[0046] The technical solution of the present invention will be described in detail below with reference to specific embodiments. However, the described embodiments are only some embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0047] A stable and printable formamidinium perovskite ink comprises formamidinium perovskite, a low-volatility coordination solvent, a high-volatility non-coordination solvent, and a stabilizer; the stabilizer is an organic cesium salt that has good solubility in both the low-volatility coordination solvent and the high-volatility non-coordination solvent.

[0048] In the above solution, the organic cesium salt is one or more of cesium formate, cesium acetate, cesium trifluoroacetate, cesium propionate, cesium trifluoropropionate, cesium pentafluoropropionate, cesium butyrate, cesium trifluorobutyrate, cesium isobutyrate, cesium perfluoroisobutyrate, cesium perfluorobutyrate, cesium methanesulfonate, cesium pivalate, and cesium oxalate.

[0049] Figure 2 Photographs of the dissolution degree of 1 mmol of common Cs salts in 1 mL of ethylene glycol methyl ether (2-Me) and N,N-dimethylformamide (DMF) solvents respectively. From Figure 2 It can be seen that cesium carbonate (Cs2CO3) is insoluble in both (a) the volatile non-coordinating solvent 2-Me and (b) the low-volatility coordinating solvent; cesium hydrogen carbonate (CsHCO3) and cesium iodide (CsI) react in (a) 2-Me and are almost insoluble in (b) DMF; cesium methanesulfonate (C(CH3)3COOCs) and cesium oxalate (Cs2C2O4) are partially soluble in (a) 2-Me and almost insoluble in (b); while the organic cesium salts cesium formate (HCOOCs), cesium acetate (CH3COOCs), and cesium pivalate ((CH3)3CCOOCs) are completely soluble in (a) 2-Me and partially soluble in (b) DMF, and the organic cesium salt cesium trifluoroacetate (CF3COOCs, abbreviated as CsTFA) is completely soluble in both (a) 2-Me and (b) DMF, indicating that the organic cesium salt has excellent solubility in (a) 2-Me compared with traditional inorganic cesium salts.

[0050] In the above solution, the molar ratio of the stabilizer to formamidinium perovskite is 1:(10 - 1000). The molar concentration of formamidinium perovskite in the formamidinium perovskite ink is 0.1 M - 2.0 M; the volume ratio of the high-volatility non-coordinating solvent to the low-volatility coordinating solvent is (1 - 100):1.

[0051] In the above solution, the formamidinium perovskite has a ABX3 structure, where A consists of FA with a content of m + and other ions with a content of n, and the other ions are K + , Rb + , Cs + , MA + , EA + , GA + , RNH3 + or one or more of them, and 70% < m ≤ 100%, 0 ≤ n ≤ 30%; B is at least one of Pb 2+ , Sn 2+ ; X is at least one of Cl - , Br - , I - .

[0052] In the above scheme, the low-volatility coordination solvent is one or more of N-methylpyrrolidone (NMP), dimethyl sulfoxide (DMSO), dimethylacetamide (DMA), N,N-dimethylformamide (DMF), 1,3-dimethyl-2-imidazolinone (DMI), γ-butyrolactone (GBL), N,N-dimethylpropenylurea (DMPU), and hexamethylphosphoric triamine (HMPA).

[0053] In the above scheme, the highly volatile noncoordinating solvent is one or more of ethylene glycol methyl ether (2-Me), acetonitrile (ACN), tetrahydrofuran (THF), ethanol (EtOH), isopropanol (IPA), butanol (BA), isobutanol (iBA), tert-butanol (tBA), and 1,2-dimethoxyethane (DME).

[0054] Example 1

[0055] A stable and printable formamidinium-based perovskite ink and its photovoltaic module fabrication method: The photovoltaic module has a nip formal structure, which, from bottom to top, includes a glass substrate, an FTO conductive substrate (transparent conductive substrate), a SnO2 electron transport layer, a perovskite light-absorbing layer, a Spiro-OMeTAD hole transport layer, and a top electrode. The fabrication method of the photovoltaic module includes the following steps:

[0056] 1) Etching transparent conductive substrate: Use a laser to etch channels to separate the positive and negative electrodes in a small area of ​​2cm×2cm FTO conductive glass. Then, ultrasonically clean the etched glass in cleaning solution, pure water and ethanol for 15 minutes in sequence, and then blow it dry with a nitrogen gas gun to obtain a transparent conductive substrate.

[0057] 2) Preparation of SnO2 electron transport layer: Using chemical deposition, 1.25 g urea, 1.25 mL hydrochloric acid, 25 μL mercaptoacetic acid, and 275 mg SnCl2·2H2O were added to 100 mL deionized water and uniformly dispersed to obtain a solution. 20 mL of this solution was diluted 6 times and poured into a glass container. A transparent conductive substrate was UV-treated for 15 min and then immersed in the diluted solution. The glass container was placed in a 90 °C oven for 3 h for chemical bath deposition. After the reaction was completed, the substrate was rinsed with pure water, sonicated for 5 min, dried with nitrogen, and heated at 170 °C for 1 h to obtain a SnO2 electron transport layer with a thickness of 35 nm.

[0058] 3) Preparation of perovskite ink: Dissolve 246 mg CsTFA in 1 mL of ethylene glycol methyl ether (2-Me) solvent to prepare a 1 M CsTFA / 2-Me stabilizer solution; dissolve 461 mg lead iodide (PbI2), 20.25 mg methylamine chloride (MACl), and 172 mg formamidinium iodide (FAI) in a mixed solvent of 700 μL 2-Me and 96 μL N-methylpyrrolidone (NMP); then add 3% CsTFA / 2-Me stabilizer solution and mix thoroughly to prepare perovskite ink;

[0059] 4) Preparation of perovskite light-absorbing layer: The perovskite ink was dropped onto the tin dioxide (SnO2) electron transport layer by spin coating. The ink was spin coated at 5000 rpm for 60 s (acceleration of 1000 rpm) to form a thin film. The film was immediately placed on a hot stage at 70℃ for 1 min and then heated at 100℃ for 2 h under 30-40% RH conditions to obtain a 600 nm thick FAPbI3 perovskite light-absorbing layer.

[0060] 5) Preparation of hole transport layer: Spin coating method was used; 91.4 mg of 2,2',7,7'-tetratetra[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene (Spiro-OMeTAD) powder was dissolved in 1 mL of chlorobenzene, and then 21 μL of 520 mg / mL lithium bis(trifluoromethanesulfonyl)imide (Li-TFSI) / acetonitrile solution, 35.6 μL of 4-tert-butylpyridine and 15 μL of 300 mg / mL cobalt-based (III) bis(trifluoromethanesulfonyl)imide salt (FK209) / acetonitrile solution were added and mixed evenly; the solution was dropped onto the perovskite surface and spin-coated at 4000 rpm for 30 s (acceleration of 2000 rpm) to obtain a hole transport layer with a thickness of 200 nm;

[0061] 6) Preparation of top electrode: Place the sample that has completed the above operations in a vapor deposition apparatus and vapor deposit a 100 nm thick Au electrode under high vacuum; to obtain a high-efficiency and stable formamidinium-based perovskite photovoltaic module.

[0062] Comparative Example 1

[0063] Comparative Example 1 is basically the same as Example 1, except that 3% CsTFA / 2Me stabilizer solution was not added during the preparation of the perovskite ink.

[0064] Field emission scanning electron microscopy was performed on the perovskite light-absorbing thin films prepared in Example 1 and Comparative Example 1. The test results are shown in [Figure 1]. Figure 3 .from Figure 3 It can be seen that the perovskite film of Comparative Example 1 is dense and pore-free, with a grain size of about 800 nm and uneven size; the perovskite film of Example 1 has significantly larger grains, about 1000 nm, and uniform grain size, and has a better surface morphology.

[0065] The perovskite light-absorbing thin films prepared in Example 1 and Comparative Example 1 were subjected to X-ray diffraction tests. The test results are shown in [Figure 1]. Figure 4 .from Figure 4 It can be seen that the perovskite film of Comparative Example 1 still has some non-optically active perovskite phase (δ phase); while the perovskite film of Example 1 does not have δ phase and has a higher quality perovskite film, indicating that CsTFA stabilizer can significantly improve the quality of formamidinium perovskite film.

[0066] Photovoltaic modules prepared in Example 1 and Comparative Example 1 were tested for photoelectric conversion efficiency (JV): Under standard sunlight conditions using a solar simulator, the test mask area was 0.1444 cm². 2 The scanning speed was 10 mV / s, and the test JV results are shown in [link to JV test results]. Figure 5 .from Figure 5 It can be seen that the test efficiency of Comparative Example 1 is 20.01%, of which the open-circuit voltage (V) OC The voltage is 1.084V, and the short-circuit current density (J) is... SC The value is 24.68 mA / cm. 2 The fill factor (FF) was 74.8%; the test efficiency of Example 1 was 23.12%, of which V OC It is 1.157V, J SC 24.85 mA / cm 2 FF is 80.4%, V OC The improved performance and enhanced FF indicate that CsTFA stabilizer can significantly improve the performance of formamidinium-based perovskite photovoltaic modules.

[0067] Example 2

[0068] A stable and printable formamidinium-based perovskite ink and its photovoltaic module fabrication method: The photovoltaic module has a nip formal structure, which, from bottom to top, includes a glass substrate, an FTO conductive substrate (transparent conductive substrate), a SnO2 electron transport layer, a perovskite light-absorbing layer, a Spiro-OMeTAD hole transport layer, and a top electrode. The fabrication method of the photovoltaic module includes the following steps:

[0069] 1) Etching the transparent conductive substrate: The steps are the same as in Example 1;

[0070] 2) Preparation of SnO2 electron transport layer: The steps are the same as in Example 1;

[0071] 3) Preparation of perovskite ink: Dissolve 246 mg CsTFA in 1 mL of 2-Me solvent to prepare a 1 M CsTFA / 2-Me stabilizer solution; dissolve 484 mg PbI2, 20.25 mg MACl, and 172 mg FAI in a mixed solvent of 700 μL 2-Me, 300 μL tetrahydrofuran (THF), and 96 μL NMP, and then add 1% CsTFA / 2-Me stabilizer solution and mix thoroughly to prepare perovskite ink;

[0072] 4) Preparation of perovskite light-absorbing layer: The perovskite ink was dropped onto the SnO2 electron transport layer by spin coating. The mixture was spin coated at 5000 rpm for 60 s (acceleration of 1000 rpm) to form a thin film. The film was then immediately placed on a hot stage at 70℃ for 1 min and then heated at 100℃ for 2 h under 30-40% RH conditions to obtain a FAPbI3 perovskite light-absorbing layer with a thickness of 800 nm.

[0073] 5) Preparation of the hole transport layer: The steps are the same as in Example 1;

[0074] 6) Preparation of the top electrode: The steps are the same as in Example 1.

[0075] Field emission scanning electron microscopy was performed on the perovskite light-absorbing layer film of Example 2. The test results are shown in [Figure 2]. Figure 6 .from Figure 6 It can be seen that the perovskite film of Example 2 is dense and uniform with uniform grain size.

[0076] The photovoltaic module prepared in Example 2 was tested for photoelectric conversion efficiency (JV): Under standard sunlight conditions using a solar simulator, the test mask area was 0.1444 cm². 2 The scanning speed was 10 mV / s, and the test JV results are shown in [link to JV test results]. Figure 7 .from Figure 7 It can be seen that the test efficiency of Example 2 is 24.63%, where V OC 1.180V, J SC 24.78 mA / cm 2 The FF was 84.3%, indicating that CsTFA stabilizer can significantly improve the performance of formamidinium-based perovskite photovoltaic modules.

[0077] The photovoltaic module prepared in Example 2 was subjected to field emission scanning electron microscopy cross-section testing. The test results are shown in [Figure 1]. Figure 8 .from Figure 8 It can be seen that the cross-sectional morphology of the formamidinium-based perovskite photovoltaic module in Example 2 is dense, uniform, and free of pores.

[0078] Example 3

[0079] A stable and printable formamidinium-based perovskite ink and its photovoltaic module fabrication method: The photovoltaic module has a nip formal structure, which, from bottom to top, includes a glass substrate, an FTO conductive substrate (transparent conductive substrate), a SnO2 electron transport layer, a perovskite light-absorbing layer, a Spiro-OMeTAD hole transport layer, and a top electrode. The fabrication method of the photovoltaic module includes the following steps:

[0080] 1) Etching the transparent conductive substrate: The steps are the same as in Example 1;

[0081] 2) Preparation of SnO2 electron transport layer: The steps are the same as in Example 1;

[0082] 3) Preparation of perovskite ink: Dissolve 178 mg HCOOCs in 1 mL of 2-Me solvent to prepare a 1 M HCOOCs / 2-Me stabilizer solution; dissolve 484 mg PbI2, 20.25 mg MACl, and 172 mg FAI in a mixed solvent of 1000 μL 2-Me and 96 μL NMP, then add 2% HCOOCs / 2M-e stabilizer solution and mix thoroughly to prepare perovskite ink.

[0083] 4) Preparation of perovskite light-absorbing layer: The perovskite ink was dropped onto the SnO2 electron transport layer by spin coating. The mixture was spin coated at 5000 rpm for 60 s (acceleration of 1000 rpm) to form a thin film. The film was then immediately placed on a hot stage at 70℃ for 1 min and then heated at 100℃ for 2 h under 30-40% RH conditions to obtain a 700 nm thick FAPbI3 perovskite light-absorbing layer.

[0084] 5) Preparation of the hole transport layer: The steps are the same as in Example 1;

[0085] 6) Preparation of the top electrode: The steps are the same as in Example 1.

[0086] The photovoltaic module prepared in Example 3 was tested for photoelectric conversion efficiency (JV): Under standard sunlight conditions using a solar simulator, the test mask area was 0.1444 cm². 2 The scanning speed was 10 mV / s, and the test JV results are shown in [link to JV test results]. Figure 9 .from Figure 9 It can be seen that the test efficiency of Example 3 is 23.40%, where V OC 1.170V, J SC 24.62 mA / cm 2 FF was 81.3%.

[0087] Example 4

[0088] A stable and printable formamidinium-based perovskite ink and its photovoltaic module fabrication method: The photovoltaic module has a nip formal structure, which, from bottom to top, includes a glass substrate, an FTO conductive substrate (transparent conductive substrate), a SnO2 electron transport layer, a perovskite light-absorbing layer, a Spiro-OMeTAD hole transport layer, and a top electrode. The fabrication method of the photovoltaic module includes the following steps:

[0089] 1) Etching the transparent conductive substrate: The steps are the same as in Example 1;

[0090] 2) Preparation of SnO2 electron transport layer: The steps are the same as in Example 1;

[0091] 3) Preparation of perovskite ink: Dissolve 246 mg CsTFA in 1 mL of 2-Me solvent to prepare a 1 M CsTFA / 2-Me stabilizer solution; dissolve 484 mg PbI2, 20.25 mg MACl, and 172 mg FAI in a mixed solvent of 1200 μL 2-Me and 96 μL NMP, then add 3% CsTFA / 2-Me stabilizer solution and mix thoroughly to prepare perovskite ink.

[0092] 4) Preparation of perovskite light-absorbing layer: The perovskite ink was dropped onto the SnO2 electron transport layer by spin coating. The mixture was spin coated at 5000 rpm for 60 s (acceleration of 1000 rpm) to form a thin film. The film was immediately placed on a hot stage at 70℃ for 1 min and then heated at 100℃ for 2 h under 30-40% RH conditions to obtain a 300 nm thick FAPbI3 perovskite light-absorbing layer.

[0093] 5) Preparation of the hole transport layer: The steps are the same as in Example 1;

[0094] 6) Preparation of the top electrode: The steps are the same as in Example 1.

[0095] Field emission scanning electron microscopy was performed on the perovskite light-absorbing layer film of Example 4. The test results are shown in [Figure 4]. Figure 10 .from Figure 10 It can be seen that the perovskite film in Example 4 is dense and uniform with uniform grain size.

[0096] The photovoltaic module prepared in Example 4 was tested for photoelectric conversion efficiency (JV): Under standard sunlight conditions using a solar simulator, the test mask area was 0.1444 cm². 2 The scanning speed was 10 mV / s, and the test JV results are shown in [link to JV test results]. Figure 11 .from Figure 11 It can be seen that the test efficiency of Example 4 is 23.36%, where V OC 1.170V, J SC 24.06 mA / cm 2FF was 83.0%.

[0097] The photovoltaic module prepared in Example 4 was subjected to field emission scanning electron microscopy cross-section testing. The test results are shown in [Figure 4]. Figure 12 .from Figure 12 It can be seen that the cross-sectional morphology of the formamidinium-based perovskite photovoltaic module in Example 4 is dense, uniform, and free of pores.

[0098] Example 5

[0099] A stable and printable formamidinium-based perovskite ink and its photovoltaic module fabrication method: The photovoltaic module has a nip formal structure, which, from bottom to top, includes a glass substrate, an FTO conductive substrate (transparent conductive substrate), a SnO2 electron transport layer, a perovskite light-absorbing layer, a Spiro-OMeTAD hole transport layer, and a top electrode. The fabrication method of the photovoltaic module includes the following steps:

[0100] 1) Etching the transparent conductive substrate: The steps are the same as in Example 1;

[0101] 2) Preparation of SnO2 electron transport layer: The steps are the same as in Example 1;

[0102] 3) Preparation of perovskite ink: Dissolve 246 mg CsTFA in 1 mL of 2-Me solvent to prepare a 1 M CsTFA / 2-Me stabilizer solution; dissolve 484 mg PbI2, 20.25 mg MACl, and 172 mg FAI in a mixed solvent of 700 μL 2-Me and 96 μL NMP, then add 0.5% CsTFA / 2-Me stabilizer solution and mix thoroughly to prepare perovskite ink.

[0103] 4) Preparation of perovskite light-absorbing layer: The perovskite ink was dropped onto the SnO2 electron transport layer by spin coating. The mixture was spin coated at 5000 rpm for 60 s (acceleration of 1000 rpm) to form a thin film. The film was then immediately placed on a hot stage at 70℃ for 1 min and then heated at 100℃ for 2 h under 30-40% RH conditions to obtain a 700 nm thick FAPbI3 perovskite light-absorbing layer.

[0104] 5) Preparation of the hole transport layer: The steps are the same as in Example 1;

[0105] 6) Preparation of the top electrode: The steps are the same as in Example 1.

[0106] Field emission scanning electron microscopy was performed on the perovskite light-absorbing layer film of Example 5. The test results are shown in [Figure 5]. Figure 13 .from Figure 13 It can be seen that the perovskite film of Example 5 is dense and uniform with uniform grain size.

[0107] The photovoltaic module prepared in Example 5 was tested for photoelectric conversion efficiency (JV): under standard sunlight conditions using a solar simulator, the test mask area was 0.1444 cm². 2 The scanning speed was 10 mV / s, and the test JV results are shown in [link to JV test results]. Figure 14 .from Figure 14 It can be seen that the test efficiency of Example 5 is 24.28%, where V OC It is 1.171V, J SC 25.24 mA / cm 2 FF was 82.1%.

[0108] Example 6

[0109] A stable and printable formamidinium-based perovskite ink and its photovoltaic module fabrication method: The photovoltaic module has a nip formal structure, which, from bottom to top, includes a glass substrate, an FTO conductive substrate (transparent conductive substrate), a SnO2 electron transport layer, a perovskite light-absorbing layer, a Spiro-OMeTAD hole transport layer, and a top electrode. The fabrication method of the photovoltaic module includes the following steps:

[0110] 1) Etching transparent conductive substrate: A 6cm×6cm FTO conductive glass was etched with a laser to form P1. The etched glass was then ultrasonically cleaned in cleaning solution, pure water and ethanol for 15 minutes in sequence, and then dried with a nitrogen gas gun to obtain a transparent conductive substrate.

[0111] 2) Preparation of SnO2 electron transport layer: The steps are the same as in Example 1;

[0112] 3) Preparation of perovskite ink: Dissolve 246 mg CsTFA in 1 mL of 2-Me solvent to prepare a 1 M CsTFA / 2-Me stabilizer solution; dissolve 484 mg PbI2, 20.25 mg MACl, and 172 mg FAI in a mixed solvent of 1000 μL 2-Me and 96 μL NMP, then add 3% CsTFA / 2-Me stabilizer solution and mix thoroughly to prepare perovskite ink.

[0113] 4) Preparation of perovskite light-absorbing layer: The perovskite ink was dropped onto the SnO2 electron transport layer by spin coating. The mixture was spin coated at 5000 rpm for 60 s (acceleration of 1000 rpm) to form a thin film. The film was then immediately placed on a hot stage at 70℃ for 1 min and then heated at 100℃ for 2 h under 30-40% RH conditions to obtain a 700 nm thick FAPbI3 perovskite light-absorbing layer.

[0114] 5) Preparation of the hole transport layer: The steps are the same as in Example 1;

[0115] 6) Laser scribing etches the perovskite light-absorbing layer and hole transport layer to form P2, opening a pathway for connecting the top electrode of adjacent photovoltaic module sub-cells and the transparent conductive substrate.

[0116] 7) Preparation of the top electrode: The steps are the same as in Example 1;

[0117] 8) Fabricate formamidinium-based perovskite photovoltaic module sub-cells, laser scribing the top electrode to form P3, thereby disconnecting the top electrode connection of adjacent photovoltaic module sub-cells and realizing sub-cell series connection.

[0118] The photovoltaic module prepared in Example 6 was used for photoelectric conversion efficiency (JV) testing: under standard sunlight conditions using a solar simulator, the test mask area was 13.44 cm². 2 The scan speed was 50 mV / s, and the test JV results are shown in [link to JV test results]. Figure 15 .from Figure 15 It can be seen that the test efficiency of Example 6 is 21.72%, where V OC It is 8.209V, J SC 3.48 mA / cm 2 The FF is 76%. The 5cm × 5cm perovskite photovoltaic module prepared in Example 6 is shown in the image. Figure 16 .

[0119] Example 7

[0120] A stable and printable formamidinium-based perovskite ink and its photovoltaic module fabrication method: The photovoltaic module has a nip formal structure, which, from bottom to top, includes a glass substrate, an FTO conductive substrate (transparent conductive substrate), a SnO2 electron transport layer, a perovskite light-absorbing layer, a Spiro-OMeTAD hole transport layer, and a top electrode. The fabrication method of the photovoltaic module includes the following steps:

[0121] 1) Etching transparent conductive substrate: A large area of ​​20cm×20cm FTO conductive glass is etched with a laser to form P1. Then, the etched glass is ultrasonically cleaned in cleaning solution, pure water and ethanol for 15 minutes in sequence, and then dried with nitrogen gas gun to obtain transparent conductive substrate.

[0122] 2) Preparation of SnO2 electron transport layer: Chemical deposition method was used; 1.25g urea, 1.25mL hydrochloric acid, 25μL mercaptoacetic acid, and 275mg SnCl2·2H2O were added to 100mL deionized water and dispersed evenly; 60mL of this solution was diluted 6 times and poured into a glass container; a transparent conductive substrate was UV treated for 15min and then immersed in the diluted solution. The glass container was placed in a 90℃ oven for 3h for chemical bath deposition; after the reaction was completed, it was rinsed with pure water, sonicated for 5min, dried with nitrogen, and heated at 170℃ for 1h to obtain a SnO2 electron transport layer with a thickness of 35nm;

[0123] 3) Preparation of perovskite ink: Dissolve 246 mg CsTFA in 1 mL of 2-Me solvent to prepare a 1 M CsTFA / 2-Me stabilizer solution; dissolve 484 mg PbI2, 20.25 mg MACl, and 172 mg FAI in a mixed solvent of 1000 μL 2-Me and 96 μL NMP, and then add 3% CsTFA / 2-Me stabilizer solution and mix thoroughly to prepare perovskite ink;

[0124] 4) Preparation of the perovskite light-absorbing layer: A blade coating method was used; the distance between the blade and the substrate was set to 0.5 mm, the blade's feed speed to 2 mm / s, and the air pressure of the air knife to 0.2 MPa. The prepared perovskite ink was dropped onto the gap between the blade and the substrate, and a perovskite film was formed by blade coating. The film was placed on a hot stage at 100℃ and heated for 1 min, and then heated at 150℃ for 10 min under 30-40% RH conditions to obtain a 600 nm thick FAPbI3 perovskite light-absorbing layer.

[0125] 5) Preparation of the hole transport layer: A blade coating method was used. 91.4 mg of Spiro-OMeTAD powder was dissolved in 1 mL of chlorobenzene, followed by the addition of 21 μL of a 520 mg / mL lithium bis(trifluoromethanesulfonyl)imide (Li-TFSI) / acetonitrile solution, 35.6 μL of 4-tert-butylpyridine, and 15 μL of a 300 mg / mL cobalt-based (III) bis(trifluoromethanesulfonyl)imide salt (FK209) / acetonitrile solution. The mixture was thoroughly mixed. The distance between the blade and the substrate was set to 0.55 mm, and the blade's feeding speed was 2 mm / s. The solution was then dropped onto the gap between the blade and the substrate, and a Spiro-OMeTAD film with a thickness of approximately 300 nm was formed by blade coating.

[0126] 6) Laser scribing etches the perovskite light-absorbing layer and hole transport layer to form P2, opening a pathway for connecting the top electrode of adjacent photovoltaic module sub-cells and the transparent conductive substrate.

[0127] 7) Preparation of the top electrode: The steps are the same as in Example 1;

[0128] 8) Fabricate formamidinium-based perovskite photovoltaic module sub-cells, laser scribing the top electrode to form P3, thereby disconnecting the top electrode connection of adjacent photovoltaic module sub-cells and realizing sub-cell series connection.

[0129] The photovoltaic module prepared in Example 7 was tested for photoelectric conversion efficiency (JV): under standard sunlight conditions using a solar simulator, the effective area tested was 310 cm². 2 The scan speed was 300 mV / s, and the test JV results are shown below. Figure 17 .from Figure 17 It can be seen that the test efficiency of Example 7 is 17.98%, where VOC 288.290V, J SC 0.91 mA / cm 2 The FF was 69.5%. The 20cm × 20cm perovskite photovoltaic module prepared in Example 7 was photographed. Figure 18 .

[0130] Example 8

[0131] A stable and printable formamidinium-based perovskite ink and its photovoltaic module fabrication method: The photovoltaic module has a pin-inverted structure, and its structure, from bottom to top, includes a glass substrate, an ITO conductive substrate (transparent conductive substrate), a self-assembled hole transport layer, a perovskite light-absorbing layer, and a C... 60 The photovoltaic module comprises a copper-based plasma transport layer (BCP) and a top electrode. The fabrication method includes the following steps:

[0132] 1) Etching transparent conductive substrate: Use a laser to etch channels to separate the positive and negative electrodes in a small area of ​​ITO conductive glass of 2cm×2cm. Then, ultrasonically clean the etched glass in cleaning solution, pure water and ethanol for 15 minutes in sequence, and then blow it dry with nitrogen gas gun to obtain transparent conductive substrate.

[0133] 2) Preparation of self-assembled hole transport layer: spin coating method was used; 0.5 mg MeO-2PACz was dissolved in 1000 μL of ethanol solvent; the prepared hole transport layer solution was dropped onto ITO glass substrate and spin coated at 3000 rpm for 30 s (acceleration of 3000 rpm), and then immediately placed on a 100℃ hot stage for 20 min to obtain a dense self-assembled hole transport layer;

[0134] 3) Preparation of perovskite ink: Spin coating method was used; 246 mg CsTFA was dissolved in 1 mL of 2-Me solvent to prepare a 1 M CsTFA / 2-Me stabilizer solution; 484 mg PbI2, 20.25 mg MACl, and 172 mg FAI were dissolved in a mixed solvent of 700 μL 2-Me and 96 μL NMP, and then 2% CsTFA / 2-Me stabilizer solution was added and mixed thoroughly to prepare perovskite ink;

[0135] 4) Preparation of perovskite light-absorbing layer: The perovskite ink was dropped onto the prepared self-assembled hole layer by spin coating. The mixture was spin coated at 5000 rpm for 60 s (acceleration of 1000 rpm) to form a thin film. The film was immediately placed on a 70℃ hot stage for 1 min and then heated at 100℃ for 2 h under 30-40% RH conditions to obtain a 600 nm thick FAPbI3 perovskite light-absorbing layer.

[0136] 5) Preparation of electron transport layer: Vapor deposition was used; the samples after the above operations were placed in a vapor deposition apparatus, and a 25 nm thick C layer was deposited under high vacuum. 60 and a 2nm thick BCP;

[0137] 6) Fabrication of the top electrode: After fabricating the above-mentioned electron transport layer, an Ag electrode with a thickness of 80 nm is deposited under high vacuum; thus, a highly efficient and stable formamidinium-based perovskite photovoltaic module is obtained.

[0138] The photovoltaic module prepared in Example 8 was tested for photoelectric conversion efficiency (JV): under standard sunlight conditions using a solar simulator, the test mask area was 0.058 cm². 2 The scanning speed was 10 mV / s, and the test JV results are shown in [link to JV test results]. Figure 19 .from Figure 19 It can be seen that the test efficiency of Example 8 is 19.53%, where V OC It is 1.084V, J SC 24.38 mA / cm 2 FF was 73.9%.

[0139] Example 9

[0140] A stable and printable formamidinium-based perovskite ink and its thin film preparation method: The photovoltaic module prepared from this ink has a nip formal structure, which, from bottom to top, includes a glass substrate, an FTO conductive substrate, and a perovskite light-absorbing layer. The preparation method of this thin film includes the following steps:

[0141] 1) Cleaning the transparent conductive substrate: A small area of ​​FTO conductive glass (2cm×2cm) was ultrasonically cleaned in cleaning solution, pure water, and ethanol for 15 minutes in sequence, and then dried with a nitrogen gas gun to obtain a transparent conductive substrate.

[0142] 2) Preparation of perovskite ink: Spin coating method was used; 178 mg CsCOOH was dissolved in 1 mL of 2-Me solvent to prepare a 1 M CsCOOH / 2-Me stabilizer solution; 461 mg lead iodide (PbI2), 20.25 mg methylamine chloride (MACl), and 172 mg formamidine iodide (FAI) were dissolved in a mixed solvent of 700 μL 2-Me and 96 μL NMP, and then 3% CsCOOH / 2-Me stabilizer solution was added and mixed thoroughly to prepare perovskite ink;

[0143] 4) Preparation of perovskite light-absorbing layer: spin coating method was used; the prepared perovskite ink was dropped onto a transparent conductive substrate and spin coated at 5000 rpm for 60 s (acceleration of 1000 rpm) to form a thin film. The film was immediately placed on a 70℃ hot stage for 1 min and then heated at 100℃ for 2 h under 30-40% RH conditions to obtain a 600 nm thick FAPbI3 perovskite light-absorbing layer.

[0144] Comparative Example 2

[0145] The only difference between Comparative Example 2 and Example 9 is that no 3% CsCOOH / 2-Me stabilizer solution was added during the preparation of the perovskite ink.

[0146] The perovskite light-absorbing thin films prepared in Example 9 and Comparative Example 2 were subjected to X-ray diffraction tests. The test results are shown in [Figure 1]. Figure 20 .from Figure 20 It can be seen that the perovskite film of Comparative Example 2 has a large amount of non-optically active perovskite phase (δ phase); while the perovskite film of Example 9 only has a small amount of δ phase and has a higher intensity α phase, indicating that the CsCOOH stabilizer can significantly improve the quality of formamidinium perovskite film.

[0147] The above embodiments are merely examples for clear illustration and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations, and any obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A stable and printable formamidinium-based perovskite ink, characterized in that, It includes formamidinium perovskite, a low-volatility coordination solvent, a high-volatility non-coordination solvent, and a stabilizer; the stabilizer is an organic cesium salt that has good solubility in both the low-volatility coordination solvent and the high-volatility non-coordination solvent; The molar ratio of the stabilizer to the formamidine perovskite is 1:(10-1000); the molar concentration of the formamidine perovskite in the formamidine perovskite ink is 0.1 M-2.0 M; the volume ratio of the highly volatile noncoordinating solvent to the low-volatile coordinating solvent is (1-100):

1. The organic cesium salt is one or more of the following: cesium formate, cesium acetate, cesium trifluoroacetate, cesium propionate, cesium trifluoropropionate, cesium pentafluoropropionate, cesium butyrate, cesium trifluorobutyrate, cesium isobutyrate, cesium perfluoroisobutyrate, cesium perfluorobutyrate, cesium methanesulfonate, cesium neopentanoate, and cesium oxalate. The low-volatility coordination solvent is one or more of N-methylpyrrolidone, dimethyl sulfoxide, dimethylacetamide, N,N-dimethylformamide, 1,3-dimethyl-2-imidazolinone, γ-butyrolactone, N,N-dimethylpropenylurea, and hexamethylphosphoric triamine. The highly volatile noncoordinating solvent is one or more of ethylene glycol methyl ether, acetonitrile, tetrahydrofuran, ethanol, isopropanol, butanol, isobutanol, tert-butanol, and 1,2-dimethoxyethane.

2. The stable and printable formamidinium-based perovskite ink according to claim 1, characterized in that, The formamidinium perovskite has a ABX3 structure, where A consists of FA with a content of m + and other ions with a content of n. The other ions are K + , Rb + , Cs + , MA + , EA + , GA + , RNH3 + or one or more of them, and 70% < m ≤ 100%, 0 ≤ n ≤ 30%; B is at least one of Pb 2+ , Sn 2+ ; X is at least one of Cl - , Br - , I - .

3. A formamidinium-based perovskite photovoltaic module, characterized in that, include: The invention comprises a transparent conductive substrate, an electron transport layer, a perovskite light-absorbing layer, a hole transport layer, and a top electrode, wherein the perovskite light-absorbing layer is a formamidine-based perovskite film prepared by any one of the following processing methods: spin coating, blade coating, slot coating, spraying, or inkjet printing, as described in any one of claims 1-2. The structure of the formamidinium-based perovskite photovoltaic module includes a nip formal structure and a pin inverse structure.

4. The method for preparing a formamidinium-based perovskite photovoltaic module according to claim 3, characterized in that, Includes the following steps: 1) Use laser etching to etch a transparent conductive substrate; 2) Fabrication of a formamidinium-based perovskite photovoltaic module with a nip formal structure: An electron transport layer, a perovskite light-absorbing layer, and a hole transport layer are sequentially fabricated on the transparent conductive substrate obtained in step 1). The electron transport layer is prepared by chemical bath deposition or blade coating, while the hole transport layer is prepared by spin coating or blade coating. To prepare a pin-structured formamidinium-based perovskite photovoltaic module, a hole transport layer, a perovskite light-absorbing layer, and an electron transport layer are sequentially prepared on the conductive substrate obtained in step 1). The hole transport layer is prepared by spin coating or blade coating, and the electron transport layer is prepared by spin coating, blade coating, or vapor deposition. 3) The top electrode is prepared by vacuum evaporation, thus obtaining the formamidinium-based perovskite photovoltaic module.

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