Perovskite thin film for flexible indoor photovoltaic module and preparation method and application of perovskite thin film

Abstract

The invention discloses a perovskite thin film for a flexible indoor photovoltaic module and a preparation method and application of the perovskite thin film, and belongs to the technical field of photovoltaic modules. The technical problem to be solved is to provide a perovskite precursor film and a photovoltaic module which are high in crystallinity, good in hydrophobicity, high in weak light energy conversion efficiency and high in stability through combination of material design and process optimization. The key point of the technical scheme is that the preparation method of the perovskite thin film comprises the following steps: preparing a perovskite precursor solution, wherein the preparation raw materials of the perovskite precursor solution comprise a thiocyanogen-containing additive; coating a flexible substrate with the perovskite precursor solution, and removing the solvent to obtain a perovskite intermediate phase film; and performing first-stage infrared radiation annealing on the perovskite intermediate phase thin film, and performing second-stage high-temperature annealing on the perovskite intermediate phase thin film with the front face facing upwards or downwards.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic module technology, and more specifically, to perovskite thin films for flexible indoor photovoltaic modules, their preparation methods, and applications. Background Technology

[0002] For understanding the technical content of this invention: Perovskite solar cells have become a hot topic in next-generation photovoltaic technology research in recent years due to their advantages such as solution-processability, tunable bandgap, high light absorption coefficient, and rapid improvement in power conversion efficiency. Among them, flexible perovskite photovoltaic devices have broad application prospects in indoor low-light environments, providing continuous and stable energy for IoT terminals, wearable electronic devices, and low-power sensors. Compared to traditional silicon-based photovoltaic devices, flexible perovskite photovoltaic modules offer advantages such as light weight, bendability, and adaptability to complex surfaces, making them more suitable for various commercial applications such as portable electronic products, smart homes, and environmental monitoring nodes. With the rapid popularization of IoT and smart devices, indoor photovoltaics is considered a key technological path to achieve "energy self-sufficiency" and reduce battery replacement and maintenance costs; therefore, flexible indoor photovoltaic modules have enormous market potential and industrial value in the future. Relevant patent documents retrieved: The document, published in China, with publication number CN106784328A and publication date May 31, 2017, discloses the chemical formula of the perovskite polycrystalline thin film as ABX3. The preparation method includes the following steps: (1) preparation of perovskite precursor solution, in which the halide of B and the monovalent cation salt of X are dissolved in a solvent containing oxygen groups to form a perovskite precursor solution; (2) coating the perovskite precursor solution obtained in step (1) onto a substrate to form a perovskite precursor thin film, and adding a second solvent to the surface of the film during the film formation process, wherein the second solvent contains an antisolvent that is insoluble in the perovskite precursor solution; (3) crystallizing the perovskite precursor thin film obtained in step (2) to obtain a high-performance perovskite polycrystalline thin film.

[0003] In the existing technologies described above, perovskite precursor solutions typically involve dissolving lead halide salts and organic / inorganic halides in solvent systems such as N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO), followed by spin coating or blade coating processes to deposit perovskite films. To obtain highly crystalline and dense films, annealing is usually required to promote phase transformation and grain growth in the precursor. However, these conventional techniques still have significant shortcomings, which are even more pronounced when prepared in air, such as the wide bandgap composition often relying on a high proportion of Br. - Or mixed cations (such as FA) + Cs + I is more likely to occur in the air. - / Br- Phase separation or phase transition leads to instability in energy level structure and optical properties; and Br - Organic cations readily absorb moisture and decompose, while wide-bandgap perovskite lattice stability is relatively weak, making them more prone to degradation under the influence of air moisture and oxygen. Furthermore, the crystallization kinetics of wide-bandgap components are demanding, requiring long and high-temperature conventional thermal annealing, which not only makes phase separation difficult to avoid but may also introduce additional defects, particularly unfavorable under atmospheric conditions. These problems severely limit the efficiency and long-term stability of flexible indoor photovoltaic devices, hindering their further application and commercialization in low-light indoor environments.

[0004] Relevant non-patent literature retrieved: The journal or book title is "The 4th Symposium on Novel Solar Cells," and the document title is "Two-Step Annealing Method Improves the Efficiency and Repeatability of Perovskite Solar Cells," published on May 27-28, 2017. This document discloses commonly used methods for preparing perovskite thin films, including one-step spin coating, two-step methods, dual-source co-evaporation, and vapor-phase assisted solution methods. Among these, the "solvent engineering method," developed based on the one-step solution method, has been widely used to prepare high-efficiency perovskite solar cells (PSCs). This method involves adding DMSO to a precursor solution (MAI+PbI2) and adding antisolvents such as chlorobenzene or toluene during spin coating to form a uniform and transparent mesophase MAI-PbI2-DMSO film, which is then annealed at 100°C to obtain a black perovskite film. Currently, research on this process mainly focuses on the preparation and related mechanisms of the mesophase film, with less research on its post-processing. The commonly used direct 100°C annealing method for the mesophase film can cause problems such as uneven perovskite grain size and poor device repeatability. Improving the post-processing technology of the "solvent engineering method" to control the perovskite reaction process and crystallization rate is key to the controllable preparation of high-quality perovskite films and the improvement of device efficiency and repeatability.

[0005] Therefore, how to improve solution stability and film quality by introducing appropriate functional additives into the precursor solution, and combine this with an optimized annealing process to achieve compatibility with flexible substrates and improved performance in low light conditions, has become an urgent problem to be solved in this field. Summary of the Invention

[0006] The purpose of this invention is to provide: A perovskite thin film for flexible indoor photovoltaic modules, its preparation method and application, and related technologies, to solve technical problems such as providing a perovskite precursor thin film with high crystallinity, good hydrophobicity, high energy conversion efficiency in weak light and high stability, and photovoltaic modules, or combinations thereof.

[0007] Terminology Explanation: Unless otherwise defined, all technical terms in this document have the same meanings as commonly understood by one of ordinary skill in the art to which the subject matter of the claims pertains. Unless otherwise stated, all patents, patent inventions, and publications cited in this document are incorporated herein by reference in their entirety. If multiple definitions exist for terms in this document, the definitions in this chapter shall prevail.

[0008] It should be understood that the above brief description and the following detailed description are exemplary and for illustrative purposes only, and do not limit the subject matter of the invention in any way. In this invention, the singular is used in conjunction with the plural unless otherwise specifically stated. It should also be noted that, unless otherwise stated, the use of “or” or “or” means “and / or”. Furthermore, the use of the term “comprising” and other forms such as “including,” “containing,” and “contains” are not limiting.

[0009] The definitions of standard chemical terms can be found in the reference "GB / T 4937 series 'Mechanical and Climate Test Methods for Semiconductor Devices'".

[0010] Unless otherwise stated, conventional methods within the scope of the art, such as mixing methods, shall be used.

[0011] Unless specifically defined herein, the use of all commercially available products herein employs standard techniques. For example, it may be carried out using the manufacturer's instructions for use with the kit, or in accordance with methods known in the art or the description of this invention. The techniques and methods described herein can generally be implemented according to conventional methods well known in the art, based on the descriptions in the various summary and more specific documents cited and discussed in this specification.

[0012] In a first aspect, the present invention provides: a method for preparing a perovskite thin film for flexible indoor photovoltaic modules, comprising the following steps: S1: Prepare a perovskite precursor solution, wherein the raw materials for preparing the perovskite precursor solution include thiocyanate-containing additives; S2: The perovskite precursor solution is coated on a flexible substrate, and the solvent is removed to obtain a perovskite mesophase film. S3: Perform the first stage of infrared radiation annealing on the perovskite mesophase film, and then perform the second stage of high-temperature annealing on the perovskite mesophase film with the front side facing up or down.

[0013] In step S1, the raw materials for preparing the perovskite precursor solution include: Perovskite materials, with the chemical formula Cs 0.2 FA 0.8 PbI x Br 3-x (2≥x≥1.4); Mixed solvents, including N,N-dimethylformamide (DMF), N-ethylpyrrolidone (NEP) and N-methylpyrrolidone (NMP); Thiocyanate-containing additives are selected from at least one of potassium thiocyanate (KSCN), gallium thiocyanate (GASCN), rubidium thiocyanate (RbSCN), and lead thiocyanate (Pb(SCN)2).

[0014] The concentration of perovskite material in the perovskite precursor solution is 1.0-1.5 mol / L.

[0015] The volume ratio of DMF, NEP and NMP is 8-10:0.3-0.5:0.5-0.7.

[0016] Any point value or any range of two points within the above range can achieve the technical effect of the present invention. For example, the volume ratio of DMF, NEP and NMP includes, but is not limited to, 8:0.3:0.5, 9:0.4:0.6, 10:0.5:0.7, or any range of two points within the range of 8-10:0.3-0.5:0.5-0.7.

[0017] More preferably, the volume ratio of DMF, NEP and NMP is 9:0.4:0.6.

[0018] Preferably, the thiocyanate-containing additive is at least one of KSCN or RbSCN.

[0019] More preferably, the thiocyanate-containing additive is KSCN and RbSCN.

[0020] More preferably, the molar ratio of KSCN to RbSCN is 1-3:1-3. Any point value or any range of two points within the above range can achieve the technical effect of this invention. For example, the molar ratio of KSCN to RbSCN includes, but is not limited to, 1:1, 1:2, 1:3, 2:1, 2:2, 2:3, 3:1, 3:2, 3:3, or any range of two points within the range of 1-3:1-3.

[0021] More preferably, the molar ratio of KSCN to RbSCN is 1:1.

[0022] Preferably, the concentration of the thiocyanate-containing additive is 2 mol%-4 mol% of the perovskite precursor solution. Any point value or any range of two points within the above range can achieve the technical effect of the present invention. For example, the concentration of the thiocyanate-containing additive includes, but is not limited to, 2 mol%, 2.1 mol%, 2.2 mol%, 2.3 mol%, 2.4 mol%, 2.5 mol%, 2.6 mol%, 2.7 mol%, 2.8 mol%, 2.9 mol%, 3.0 mol%, 3.1 mol%, 3.2 mol%, 3.3 mol%, 3.4 mol%, 3.5 mol%, 3.6 mol%, 3.7 mol%, 3.8 mol%, 3.9 mol%, 4.0 mol%, or any range of two points within the range of 2-4 mol%.

[0023] More preferably, the concentration of the thiocyanate-containing additive is 4 mol of the perovskite precursor solution.

[0024] In step S1, the preparation of the perovskite precursor solution includes the following steps: mixing the perovskite material and the mixed solvent, and then adding a thiocyanate-containing additive to obtain the perovskite precursor solution.

[0025] Preferably, in step S3, the wavelength of the infrared radiation annealing is 800-1200nm, the power is 300-500W, the temperature is 80-120℃, and the time is 1-5min.

[0026] Any point value or any range of two point values ​​within the above range can achieve the technical effect of the present invention. For example, wavelengths include, but are not limited to, 800nm, 850nm, 900nm, 950nm, 1000nm, 1050nm, 1100nm, 1150nm, 1200nm, or any range of two point values ​​within the range of 800-1200nm. The power rating includes, but is not limited to, 300W, 310W, 320W, 330W, 340W, 350W, 360W, 370W, 380W, 390W, 400W, 410W, 420W, 430W, 440W, 450W, 460W, 470W, 480W, 490W, 500W, or any range of values ​​formed by any two points within the range of 300-500W; Temperatures include, but are not limited to, 80℃, 81℃, 82℃, 83℃, 84℃, 85℃, 86℃, 87℃, 88℃, 89℃, 90℃, 91℃, 92℃, 93℃, 94℃, 95℃, 96℃, 97℃, 98℃, 99℃, 100℃, 101℃, 102℃, 103℃, 104℃, 105℃, 106℃, 107℃, 108℃, 109℃, 110℃, 111℃, 112℃, 113℃, 114℃, 115℃, 116℃, 117℃, 118℃, 119℃, 120℃, or a range of values ​​consisting of any two points within the range of 80-120℃; The time includes, but is not limited to, 1 min, 2 min, 3 min, 4 min, 5 min, or a range of values ​​consisting of any two points within the range of 1-5 min; Preferably, in step S3, the high-temperature annealing temperature is 140-170℃, and the time is 8-20 minutes. Any point value or any range of two points within the above range can achieve the technical effect of this invention. For example, the temperature includes, but is not limited to, 140℃, 141℃, 142℃, 143℃, 144℃, 145℃, 146℃, 147℃, 148℃, 149℃, 150℃, 151℃, 152℃, 153℃, 154℃, 155℃, 156℃, 157℃, 158℃, 159℃, 160℃, 161℃, 162℃, 163℃, 164℃, 165℃, 166℃, 167℃, 168℃, 169℃, 170℃, or any range of two points within the 140-170℃ range. The time includes, but is not limited to, 8 min, 9 min, 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, 16 min, 17 min, 18 min, 19 min, 20 min, or a range of values ​​consisting of any two points within the range of 8 to 20 min.

[0027] Secondly, the present invention provides a perovskite thin film for flexible indoor photovoltaic modules prepared by the preparation method described above.

[0028] Thirdly, the present invention provides an application of the perovskite thin film for flexible indoor photovoltaic modules prepared by the above-described preparation method in the preparation of flexible perovskite solar cell modules.

[0029] Preferably, the method for fabricating the flexible perovskite solar cell module includes the following steps: (1) P1 etching was performed on a flexible ITO substrate using a red nanosecond laser to separate multiple sub-cells from the bottom. The substrate was then ultrasonically cleaned with detergent, water, and ethanol for 8-12 minutes in sequence, and dried with an air gun. (2) Place the cleaned flexible substrate in a magnetron sputtering apparatus. Sputtering power: 1800-2200W, argon: 380-420sccm, oxygen: 1-3sccm. Sputter for 3 cycles at room temperature to obtain a 20nm thick NiO. x Hole transport layer; (3) Assemble the monolayer as a Me-4PACz solution with a concentration of 0.1-2 mg / mL and ethanol as the solvent. Deposit NiO into the Me-4PACz solution using the slit coating method. x On the transport layer, the coating speed is 4-6 mm / s, the liquid injection speed is 7-9 μL / s, the gap is 80-120 μm; annealing at 90-110℃ for 8-12 min yields Me-4PACz film. (4) The perovskite thin film described above is prepared by the perovskite solution described above; (6) A 15 nm C2O4 layer was gradually deposited on the surface of the perovskite active layer using thermal evaporation and ALD in-situ atomic deposition. 60 and 25 nm SnO x Subsequently, a green picosecond laser was used to perform P2 etching to remove the electron transport layer, perovskite active layer, self-assembled monolayer and hole transport layer in the P2 region, which serves as the interconnection region between the metal top electrode and the flexible ITO bottom electrode. (7) Using thermal evaporation method on SnO after P2 is applied x A 150nm copper electrode is deposited on the surface, and then a green picosecond laser is used to etch the P3 region to cut off the P3 metal region, separating multiple sub-cells from the top to obtain a large-area flexible perovskite solar cell module.

[0030] The present invention has at least the following beneficial effects: 1. The core innovation of this invention lies in achieving controllable film formation and high stability of flexible indoor photovoltaic perovskite thin films through a combination of material design and process optimization. Firstly, specific thiocyanate-containing additives are introduced into the perovskite precursor solution, utilizing SCN... - The directional migration characteristics under infrared light heating conditions effectively regulate grain boundaries and promote vertical orientation growth of thin films. Meanwhile, SCN... - Able to occupy I - Vacancies are created, thereby slowing down the crystallization process, inhibiting phase segregation, reducing the density of trapped states, and blocking water adsorption sites, laying the foundation for obtaining high-quality thin films.

[0031] 2. Secondly, this invention proposes a unique infrared pre-annealing process. Under infrared light irradiation in the 800-1200 nm band, the precursor film is selectively heated for 1-5 minutes at 80-120°C, causing rapid heating of the perovskite phase and solvent evaporation, while simultaneously maintaining the substrate temperature below 50°C to avoid thermal damage to the flexible substrate. This process not only shortens the film formation time but also effectively avoids the moisture adsorption window, ensuring the film formation quality in air.

[0032] 3. Furthermore, this invention employs an inverted annealing process, in which the thin film is placed face down on a heating plate with a certain distance maintained, ensuring that the heating direction is consistent with the crystal growth direction. Compared to the traditional face-up annealing method, this method avoids the problem of simultaneous crystallization from top to bottom due to the temperature gradient being opposite to the solvent evaporation direction, thereby significantly reducing the formation of grain boundaries and defects. During the annealing process, perovskite crystals can grow rapidly, and adjacent small crystals merge into large grains under the drive of Ostwald ripening. The non-photoactive phase can also be completely transformed into the photoactive phase, thus obtaining a dense, highly crystalline perovskite thin film with complete phase transformation.

[0033] 4. Furthermore, this inverted annealing process can effectively alleviate the internal stress caused by the difference in thermal expansion coefficients between the perovskite and the substrate, thereby improving the structural stability of the film. Thus, this invention not only enables the preparation of highly crystalline, hydrophobic perovskite films at low temperatures, but also significantly improves the low-light energy conversion efficiency and long-term operational stability of flexible indoor photovoltaic devices, demonstrating superior overall performance compared to existing technologies. Attached Figure Description

[0034] Figure 1 This is a scanning electron microscope image of the perovskite thin film prepared in Example 1 of the present invention.

[0035] Figure 2 This is a scanning electron microscope image of the perovskite thin film prepared in Comparative Example 2 of the present invention.

[0036] Figure 3 This is a schematic diagram of the structure of a flexible large-area indoor perovskite solar cell module prepared according to an embodiment of the present invention. Detailed Implementation

[0037] The following non-limiting embodiments are intended to enable those skilled in the art to gain a more comprehensive understanding of the present invention, but do not limit the invention in any way. The following content is merely an exemplary description of the scope of protection claimed by the present invention, and those skilled in the art can make various changes and modifications to the present invention based on the disclosed content, and such changes should also fall within the scope of protection claimed by the present invention.

[0038] The present invention will be further described below by way of specific embodiments. Unless otherwise specified, all instruments, devices, equipment, reagents, products, etc., used in the embodiments of the present invention are obtained through conventional commercial means.

[0039] Example 1 A method for preparing perovskite thin films for flexible indoor photovoltaic modules Preparation of perovskite precursor solution: Cs was added to a mixed solvent with a volume ratio of DMF:NEP:NMP = 9:0.4:0.6. 0.2 FA 0.8 PbI x Br 3-x (2≥x≥1.4), the concentration of perovskite material in the perovskite precursor solution is 0.8 mol / L-1.5 mol / L. After mixing evenly, 2 mol% RbSCN and 2 mol% KSCN additives are added and mixed evenly to obtain the perovskite precursor solution.

[0040] The perovskite precursor solution prepared in Example 1 was coated onto a flexible substrate using a slit coating method. A VCD-assisted solvent evaporation was then used to obtain a perovskite mesophase film. The film was immediately transferred to an infrared furnace (wavelength 1000 nm) for the first stage of low-temperature pre-annealing. The residual solvent (DMF / NEP / NMP) was rapidly evaporated by controlling the furnace power to 400 W and the temperature at 100°C for 3 minutes. In the second stage, the perovskite mesophase film was placed face down on a heating plate for high-temperature annealing at 150°C for 15 minutes to obtain the perovskite film.

[0041] The surface morphology of perovskite films was tested using scanning electron microscopy (SEM), such as... Figure 1 As shown. A perovskite thin film, SCN, prepared by introducing additives and employing a novel annealing process. - Under infrared light heating, the film migrates directionally to the grain boundaries, promoting vertical orientation growth and reducing grain boundary defects; and by occupying I... - Vacancies delay the crystallization process and suppress phase segregation, thereby reducing the density of trapped states and blocking moisture adsorption sites. The grain size is significantly increased, grain boundaries and pores are reduced, and perovskite transformation is more complete, which is conducive to the transport of photogenerated carriers and thus improves device efficiency.

[0042] Example 2 A method for preparing perovskite thin films for flexible indoor photovoltaic modules Preparation of perovskite precursor solution: Cs was added to a mixed solvent with a volume ratio of DMF:NEP:NMP = 9:0.4:0.6. 0.2 FA 0.8 PbI x Br3-x (2≥x≥1.4), after mixing evenly, add 2 mol% RbSCN and 2 mol% KSCN additives to the perovskite precursor solution, mix evenly, and obtain the perovskite precursor solution.

[0043] The perovskite precursor solution prepared in Example 2 was coated onto a flexible substrate using a slit coating method. A VCD-assisted solvent evaporation was then used to obtain a perovskite mesophase film. The film was immediately transferred to an infrared furnace (wavelength 800 nm) for the first stage of low-temperature pre-annealing. The residual solvent (DMF / NEP / NMP) was rapidly evaporated by controlling the furnace power to 500 W and the temperature at 80°C for 1 min. In the second stage, the perovskite mesophase film was placed face-up on a heating plate for high-temperature annealing at 140°C for 8 min to obtain the perovskite film.

[0044] Example 3 A method for preparing perovskite thin films for flexible indoor photovoltaic modules Preparation of perovskite precursor solution: Cs was added to a mixed solvent with a volume ratio of DMF:NEP:NMP = 9:0.4:0.6. 0.2 FA 0.8 PbI x Br 3-x (2≥x≥1.4), after mixing evenly, add 1 mol% RbSCN and 3 mol% KSCN additives to the perovskite precursor solution, mix evenly, and obtain the perovskite precursor solution.

[0045] The perovskite precursor solution prepared in Example 3 was coated onto a flexible substrate using a slit coating method. A VCD-assisted solvent evaporation was then used to obtain a perovskite mesophase film. The film was immediately transferred to an infrared furnace (wavelength 1200 nm) for the first stage of low-temperature pre-annealing. The residual solvent (DMF / NEP / NMP) was rapidly evaporated by controlling the furnace power to 300 W and the temperature at 120°C for 5 minutes. In the second stage, the perovskite mesophase film was placed face down on a heating plate for high-temperature annealing at 170°C for 20 minutes to obtain the perovskite film.

[0046] Example 4 A method for preparing perovskite thin films for flexible indoor photovoltaic modules Preparation of perovskite precursor solution: Cs was added to a mixed solvent with a volume ratio of DMF:NEP:NMP = 9:0.4:0.6. 0.2 FA 0.8 PbI x Br 3-x(2≥x≥1.4), after mixing evenly, add 3mol% RbSCN and 1mol% KSCN additives to the perovskite precursor solution, mix evenly, and obtain the perovskite precursor solution.

[0047] The perovskite precursor solution prepared in Example 4 was coated onto a flexible substrate using a slit coating method. A VCD-assisted solvent evaporation was then used to obtain a perovskite mesophase film. The film was immediately transferred to an infrared furnace (wavelength 1000 nm) for the first stage of low-temperature pre-annealing. The residual solvent (DMF / NEP / NMP) was rapidly evaporated by controlling the furnace power to 400 W and the temperature at 100°C for 3 minutes. In the second stage, the perovskite mesophase film was placed face down on a heating plate for high-temperature annealing at 150°C for 15 minutes to obtain the perovskite film.

[0048] Example 5 A method for preparing perovskite thin films for flexible indoor photovoltaic modules Preparation of perovskite precursor solution: Cs was added to a mixed solvent with a volume ratio of DMF:NEP:NMP = 9:0.4:0.6. 0.2 FA 0.8 PbI x Br 3-x (2≥x≥1.4), after mixing evenly, add 4 mol% RbSCN additive to the perovskite precursor solution, mix evenly, and obtain the perovskite precursor solution.

[0049] The perovskite precursor solution prepared in Example 5 was coated onto a flexible substrate using a slit coating method. A VCD-assisted solvent evaporation was then used to obtain a perovskite mesophase film. The film was immediately transferred to an infrared furnace (wavelength 1000 nm) for the first stage of low-temperature pre-annealing. The residual solvent (DMF / NEP / NMP) was rapidly evaporated by controlling the furnace power to 400 W and the temperature at 100°C for 3 minutes. In the second stage, the perovskite mesophase film was placed face down on a heating plate for high-temperature annealing at 150°C for 15 minutes to obtain the perovskite film.

[0050] Example 6 A method for preparing perovskite thin films for flexible indoor photovoltaic modules Preparation of perovskite precursor solution: Cs was added to a mixed solvent with a volume ratio of DMF:NEP:NMP = 9:0.4:0.6. 0.2 FA 0.8 PbI x Br 3-x(2≥x≥1.4), after mixing evenly, add 4mol% KSCN additive to the perovskite precursor solution, mix evenly, and obtain the perovskite precursor solution.

[0051] The perovskite precursor solution prepared in Example 6 was coated onto a flexible substrate using a slit coating method. A VCD-assisted solvent evaporation was then used to obtain a perovskite mesophase film. The film was immediately transferred to an infrared furnace (wavelength 1000 nm) for the first stage of low-temperature pre-annealing. The residual solvent (DMF / NEP / NMP) was rapidly evaporated by controlling the furnace power to 400 W and the temperature at 100°C for 3 minutes. In the second stage, the perovskite mesophase film was placed face down on a heating plate for high-temperature annealing at 150°C for 15 minutes to obtain the perovskite film.

[0052] Comparative Example 1 A method for preparing perovskite thin films for flexible indoor photovoltaic modules Preparation of perovskite precursor solution: Cs was added to a mixed solvent with a volume ratio of DMF:NEP:NMP = 9:0.4:0.6. 0.2 FA 0.8 PbI x Br 3-x (2≥x≥1.4), after mixing evenly, add 2 mol% methylamine thiocyanate (MASCN) and 2 mol% formamidinium thiocyanate (FASCN) additives to the perovskite precursor solution, mix evenly, and obtain the perovskite precursor solution.

[0053] The perovskite precursor solution prepared in Comparative Example 1 was used as the raw material, and the rest was the same as in Example 1.

[0054] Comparative Example 2 A method for preparing perovskite thin films for flexible indoor photovoltaic modules Preparation of perovskite precursor solution: Cs was added to a mixed solvent with a volume ratio of DMF:NEP:NMP = 9:0.4:0.6. 0.2 FA 0.8 PbI x Br 3-x (2≥x≥1.4), mix thoroughly to obtain a perovskite precursor solution.

[0055] The surface morphology of perovskite thin films was tested using SEM, such as... Figure 2 As shown, the pristine perovskite film without additives has small and uneven grains, and exhibits significant Br segregation on the surface. This indicates that the film has poor crystallization quality in air and contains numerous defects, which affect the lifetime of photogenerated carriers and reduce the performance of perovskite solar cell devices.

[0056] The perovskite precursor solution prepared in Comparative Example 2 was used as the raw material, and the rest was the same as in Example 1.

[0057] Comparative Example 3 A method for preparing perovskite thin films for flexible indoor photovoltaic modules Preparation of perovskite precursor solution: Cs was added to a mixed solvent with a volume ratio of DMF:NEP:NMP = 9:0.4:0.6. 0.2 FA 0.8 PbI x Br 3-x (2≥x≥1.4), after mixing evenly, add 2 mol% RbSCN and 2 mol% KSCN additives to the perovskite precursor solution, mix evenly, and obtain the perovskite precursor solution.

[0058] The perovskite precursor solution prepared in Comparative Example 3 was coated onto a flexible substrate using a slit coating method. A perovskite mesophase film was obtained by solvent evaporation assisted by a VCD. Subsequently, the perovskite mesophase film was placed face up on a hot plate for high-temperature annealing at 150°C for 15 minutes to obtain the perovskite active layer film.

[0059] Comparative Example 4 A method for preparing perovskite thin films for flexible indoor photovoltaic modules Preparation of perovskite precursor solution: Cs was added to a mixed solvent with a volume ratio of DMF:NEP:NMP = 9:0.4:0.6. 0.2 FA 0.8 PbI x Br 3-x (2≥x≥1.4), after mixing evenly, add 2 mol% RbSCN and 2 mol% KSCN additives to the perovskite precursor solution, mix evenly, and obtain the perovskite precursor solution.

[0060] The perovskite precursor solution prepared in Comparative Example 4 was coated onto a flexible substrate using a slit coating method. A VCD-assisted solvent evaporation was then used to obtain a perovskite mesophase film. The film was immediately transferred to an infrared furnace (wavelength 1000 nm) for the first stage of low-temperature pre-annealing. The residual solvents (DMF / NEP / NMP) were rapidly evaporated by controlling the furnace power to 400 W and the temperature at 60°C for 3 minutes. In the second stage, the perovskite mesophase film was placed face down on a heating plate for high-temperature annealing at 100°C for 7 minutes to obtain the perovskite film.

[0061] Application example: Using the perovskite thin films prepared in Examples 1-6 and Comparative Examples 1-4 as raw materials, flexible perovskite solar cell modules were prepared, including the following steps: (1) P1 etching was performed on a flexible ITO substrate using a red nanosecond laser to separate multiple sub-cells from the bottom. The substrate was then ultrasonically cleaned with detergent, water, and ethanol for 10 minutes in sequence, and then dried with an air gun. (2) The cleaned flexible substrate was placed in a magnetron sputtering apparatus with a sputtering power of 2000W, argon gas of 400sccm, and oxygen gas of 2sccm. Three cycles of sputtering at room temperature were performed to obtain a 20nm thick NiO. x Hole transport layer; (3) Assemble the monolayer as a Me-4PACz solution with a concentration of 0.1-2 mg / mL and ethanol as the solvent. Deposit NiO into the Me-4PACz solution using the slit coating method. x On the transport layer, the coating speed was 5 mm / s, the liquid injection speed was 8 μL / s, the gap was 100 μm; annealing at 100℃ for 10 min yielded the Me-4PACz film. (4) The perovskite films prepared in Examples 1-5 and Comparative Examples 1-4 were used as raw materials respectively; (6) 15 nm C60 and 25 nm SnO were progressively deposited on the active layer surface of the perovskite thin film using thermal evaporation and ALD in-situ atomic deposition methods. x Subsequently, a green picosecond laser was used for P2 etching to remove the electron transport layer, perovskite active layer, self-assembled monolayer, and hole transport layer in the P2 region, which serves as the interconnection region between the metal top electrode and the flexible ITO bottom electrode; (7) Using thermal evaporation method on SnO after P2 is applied x A 150nm copper electrode is deposited on the surface, and then a green picosecond laser is used to etch the P3 region to cut off the P3 metal region, separating multiple sub-cells from the top to obtain a large-area flexible perovskite solar cell module.

[0062] The prepared component measures 10 × 10 cm. 2 The aperture area is 88.47 cm². 2 , structure as Figure 3 As shown.

[0063] The test results are shown in Table 1 below: Table 1. Test Results

[0064] The device performance was tested by simulating low indoor light illumination under LED illumination conditions of 3000K and 200 lux, and the current density-voltage curves were obtained. JV(Curve). The results show that, in Example 1, the flexible perovskite solar cell module prepared by introducing RbSCN and KSCN additives and using infrared light wave furnace pre-annealing and high-temperature annealing processes achieved an efficiency of 38.95%. The significant improvement in device efficiency indicates that the above-mentioned novel process achieved synergistic regulation of the crystallization kinetics of flexible perovskite thin films, effectively delaying excessively rapid crystallization, suppressing phase separation, and filling the I... - Vacancies are reduced, thereby decreasing defect states and moisture adsorption sites, ultimately effectively improving the quality of perovskite films. Comparative Example 1 uses MASCN and FASCN, disclosed in the prior art, as thiocyanate-containing additives. Due to the organic cations (MA...) in MASCN and FASCN... + FA + The large size of the SCN makes it prone to steric hindrance, hindering its operation. - Targeted migration and I - Vacancy filling; and these organic cations have poor thermal stability and are prone to decomposition during infrared light heating, leading to SCN... - The effective concentration decreases, and byproducts are generated, introducing new defect sites. This prevents the achievement of grain boundary regulation and phase stability enhancement, resulting in a significant decrease in the device's photoelectric conversion efficiency. Comparative Example 2 did not add any thiocyanate-containing additives to the perovskite precursor solution. The perovskite film crystallization process lacked defect passivation and grain boundary regulation, leading to an excessively rapid crystallization rate and uneven grain size. - The density of defects such as vacancies is high, and the film orientation is random with insufficient phase stability, resulting in a basic level of photoelectric conversion efficiency. Comparative Example 3 introduces a 2 mol% RbSCN and 2 mol% KSCN composite thiocyanate additive into the perovskite precursor solution, but does not employ a novel two-step annealing process, only using a single annealing method. Although SCN... - While it can achieve partial defect passivation, it lacks the directional migration driving force provided by infrared light wave heating, and cannot fully exert its grain boundary regulation and vertical orientation growth promotion effects. The improvement in thin film crystallization quality and structural stability is limited, and the device efficiency is not optimal.

[0065] Comparative Example 4 introduced the same 2 mol% RbSCN and 2 mol% KSCN composite thiocyanate additive as in Example 1 into the perovskite precursor solution, and also employed a novel two-step annealing process combining an infrared wave furnace and an annealing furnace. However, the annealing parameters (such as infrared wave heating temperature / time and annealing furnace heating temperature / time) were adjusted to outside the effective parameter range set in this invention; since the annealing parameters are crucial for ensuring the SCN... - Key conditions for directional migration efficiency, thin film crystallization kinetics matching, and structural stability; when parameters deviate from their effective range, infrared light wave heating cannot provide SCN. -Providing precise directional migration drive, subsequent annealing processes also struggle to synergistically achieve regular grain growth and sufficient defect passivation, leading to SCN... - The defect passivation effect and the synergistic effect of the novel two-step annealing process are completely ineffective. The perovskite film still has many grain boundary defects, disordered orientation, and obvious phase segregation. In the end, the photoelectric conversion efficiency of the module is greatly reduced. This further confirms the necessity of the annealing parameter range set in this invention to achieve high photoelectric conversion efficiency and highlights the core technical value of the novel two-step annealing process under precise parameter control.

[0066] Application Example 2 Further preparations were made with dimensions of 35×35 cm. 2 The effective area is 900cm² 2 For large-area modules, performance testing was conducted on the devices. By simulating low-light indoor illumination, current density-voltage curves (JV curves) were obtained under LED illumination conditions of 3000K and 200 lux. The obtained photovoltaic performance parameters are shown in Table 2.

[0067] Table 2. Test Results

[0068] The results show that, under the same additive system and process logic, the efficiency disadvantage trend of each comparative example remains significant—the comparative example without additives suffers from insufficient defect passivation, while the comparative example with additives but without the corresponding annealing process suffers from SCN. - In contrast, comparative examples with insufficient directional migration and parameter deviations, due to process synergy failures, all exhibited problems such as poor film uniformity, accumulation of grain boundary defects, and insufficient phase stability, leading to a further decline in the efficiency of large-area modules. However, in Example 1, in a 35×35cm² large-area fabrication scenario, the synergistic effect of introducing a 2 mol% RbSCN + 2 mol% KSCN composite additive and a novel two-step annealing process using an infrared light wave furnace and an annealing furnace effectively solved key problems such as uneven crystallization, defect enrichment, and orientation disorder that are prone to occur in large-area fabrication. This not only maintained the high efficiency advantage of small-sized modules but also achieved high-quality and controllable growth of large-area thin films due to the compatibility of the process and additives, ultimately demonstrating an excellent photoelectric conversion efficiency of 38.59%. This fully verifies the reliability and practicality of the technical solution of this invention in the process of module size scaling.

[0069] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, and is not intended to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention do not depart from the essence and scope of the technical solution of the present invention.

Claims

1. A method for preparing a perovskite thin film for flexible indoor photovoltaic modules, characterized in that, Includes the following steps: S1: Prepare a perovskite precursor solution, wherein the raw materials for preparing the perovskite precursor solution include thiocyanate-containing additives; S2: The perovskite precursor solution is coated on a flexible substrate, and the solvent is removed to obtain a perovskite mesophase film. S3: Perform the first stage of infrared radiation annealing on the perovskite mesophase film, and then perform the second stage of high-temperature annealing on the perovskite mesophase film with the front side facing up or down.

2. The preparation method according to claim 1, characterized in that, In step S1, the raw materials for preparing the perovskite precursor solution include: Perovskite materials, with the chemical formula Cs 0.2 FA 0.8 PbI x Br 3-x (2≥x≥1.4); Mixed solvents, including N,N-dimethylformamide, N-ethylpyrrolidone, and N-methylpyrrolidone; Thiocyanate-containing additives are selected from at least one of potassium thiocyanate, gallium thiocyanate, rubidium thiocyanate, and lead thiocyanate.

3. The preparation method according to claim 2, characterized in that, The volume ratio of N,N-dimethylformamide, N-ethylpyrrolidone, and N-methylpyrrolidone is 9:0.4:0.

6.

4. The preparation method according to claim 2, characterized in that, The thiocyanate-containing additive is at least one of potassium thiocyanate or rubidium thiocyanate.

5. The preparation method according to claim 4, characterized in that, The molar ratio of potassium thiocyanate to rubidium thiocyanate is 1-3:1-3.

6. The preparation method according to claim 5, characterized in that, The molar ratio of potassium thiocyanate to rubidium thiocyanate is 1:

1.

7. The preparation method according to claim 2, characterized in that, The concentration of the thiocyanate-containing additive is 2 mol%-4 mol of the perovskite precursor solution.

8. The preparation method according to claim 7, characterized in that, The concentration of the thiocyanate-containing additive is 4 mol of the perovskite precursor solution.

9. The preparation method according to claim 1, characterized in that, In step S1, the preparation of the perovskite precursor solution includes the following steps: mixing the perovskite material and the mixed solvent, and then adding a thiocyanate-containing additive to obtain the perovskite precursor solution.

10. The preparation method according to claim 1, characterized in that, In step S3, the infrared radiation annealing has a wavelength of 800-1200nm, a power of 300-500W, a temperature of 80-120℃, and a time of 1-5min.

11. The preparation method according to claim 1, characterized in that, In step S3, the high-temperature annealing temperature is 140-170℃ and the time is 8-20 minutes.

12. The perovskite thin film for flexible indoor photovoltaic modules prepared by the preparation method according to any one of claims 1-11.

13. The application of the perovskite thin film for flexible indoor photovoltaic modules prepared by the preparation method according to any one of claims 1-11 in the preparation of flexible perovskite solar cell modules.

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