Perovskite thin film solar cell and preparation method thereof

Abstract

The invention discloses a perovskite thin-film solar cell and a preparation method thereof, and the solar cell is characterized in that thiopyrimidine is added into a perovskite precursor, the effective time of a perovskite precursor solution can exceed one month, and the efficiency and stability of a perovskite material are improved; and a more stable and efficient perovskite thin-film solar cell is obtained through assembly. The perovskite light absorption layer is prepared from the thiopyrimidine, so that the crystallization process of the perovskite thin film can be improved, and the defect density in the perovskite can be reduced at the same time. Compared with a standard perovskite solar cell, the thiopyrimidine greatly improves the performance of the perovskite solar cell.

Description

Technical Field

[0001] This invention belongs to the field of solar cell technology, specifically relating to a perovskite thin-film solar cell and its preparation method. Background Technology

[0002] Since their initial report in 2009, perovskite solar cells (PSCs) have rapidly become a research focus in the photovoltaic field due to their advantages such as high absorption coefficient, tunable bandgap, and low manufacturing cost. Currently, their laboratory-certified efficiency has exceeded 26%, approaching the level of crystalline silicon cells, demonstrating enormous commercial potential. The extensive research on perovskite solar cells (PSCs) is attributed to their superior photoelectric performance and the economic feasibility of solution processing methods. The precursor plays a crucial role in controlling the formation of the optically preferred phase. The composition of the precursor directly affects the crystallization process of perovskite, thus influencing the photoelectric conversion efficiency (PCE) and stability of PSCs. However, uncontrolled complex reactions within the precursor can adversely affect the morphology, grain size, crystallinity, and trapped state density of the perovskite film, posing a significant challenge to the development of high-performance PSCs.

[0003] Perovskite precursors are typically prepared by dissolving lead halides (such as PbI₂) and organic ammonium salts (such as formamidinium iodide (FAI) and methylamine iodide (MAI)) in polar solvents (such as DMF and DMSO). However, the DMF / DMSO mixed solvent system is prone to multiple side reactions during storage and processing: iodide ions (I₂)... - Oxidation: I in solution - H, which is easily hydrolyzed by oxygen or solvents, + Oxidized to iodine molecules (I2) and iodide tri-antions (I3) - These oxidation products not only act as non-radiative recombination centers, reducing device efficiency, but also catalyze organic cations (such as FA). + MA + The deprotonation reaction of ) produces neutral methylamine (MA) 0 ) and formamidin condensation byproducts, such as N-methylformamidin cation (MFA) + ), N,N-dimethylformamidinium cation (DMFA) + These factors, such as the presence of solvents, lead to an imbalance in the stoichiometry of perovskite. More seriously, the solvent can also participate in the aging reaction, accelerating the degradation of the perovskite. DMF is easily hydrolyzed into dimethylamine (DMA) and formic acid (FAD) in the presence of trace amounts of moisture. DMA is strongly alkaline (pK... α ≈10.7) further accelerates MA + Deprotonation (MA) + →MA 0 +H +FAD is involved in the oxidation of DMSO. - The process involves a synergistic deterioration of the reaction chain: the above reactions form a vicious cycle—I₂ catalyzes the decomposition of organic cations, the released H₂O further promotes the hydrolysis of DMF, and the hydrolysis products DMA and FAD further exacerbate the DMSO-driven I₂ decomposition. - Oxidation process. Studies show that after the precursor solution in the DMF / DMSO mixed solvent is stored at 25°C for 30 days, the device efficiency decreases by more than 35%.

[0004] To address the precursor degradation problem, existing research mainly employs the following strategies, but significant shortcomings remain: Reducing additives: such as benzene-1,3-dithiol (BDT), which can reduce I₂ to I₂. - However, its acidity (pKα≈6.5) may accelerate I - Oxidation of ions in DMSO. Solvent engineering: Phenylhydrazine hydrochloride (BHC) is used in 2-ME solvent and may not be suitable for mainstream DMF / DMSO mixed solution systems.

[0005] In large-scale production, perovskite precursors require long-term storage, transportation, and multiple coating processes. Studies have shown that commercial-grade precursor solutions require at least 30 days of storage stability (efficiency degradation ≤10%), while DMF / DMSO precursor solutions under current technologies generally cannot be pre-prepared for storage. Furthermore, degradation products (such as I2, MFA)... + DMFA + This can introduce pinholes, PbI2 residues, and grain boundary defects into the film, leading to increased leakage current in the device. Furthermore, MFA... + DMFA + Large cations entering the crystal lattice cause lattice distortion, ultimately affecting the lifespan of the module. Given these challenges, there is an urgent need to develop a multifunctional additive capable of simultaneously blocking Ig. - It oxidizes and stabilizes organic cations and regulates crystallization kinetics. Summary of the Invention

[0006] The purpose of this section is to summarize some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of this application to avoid obscuring the purpose of this section, the abstract and the title of the invention, and such simplifications or omissions should not be used to limit the scope of the present invention.

[0007] In view of the problems existing in the above and / or prior art, the present invention is proposed.

[0008] Therefore, the purpose of this invention is to overcome the shortcomings of the prior art and provide a perovskite thin-film solar cell.

[0009] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a perovskite thin-film solar cell, characterized in that: the perovskite thin-film solar cell comprises a thiopyrimidine-modified perovskite light-absorbing layer, a substrate, an electron transport layer, a hole transport layer, and a top electrode;

[0010] The perovskite has an ABX3 type structure, with the A-site selected from methylamine (MA). + or formamidin FA + B is selected from Pb 2+ or Sn 2+ The X position is iodine I. - ;

[0011] The thiopyrimidine is one of 2-thiouracil (Th), 5-methyl-2-thiouracil (ThM), or 6-methyl-2-thiouracil (MZU).

[0012] As a preferred embodiment of the perovskite thin-film solar cell of the present invention, the perovskite material includes one of FAMAPbI3, FAPbI3, and CsMAFAPbI3.

[0013] In a preferred embodiment of the perovskite thin-film solar cell of the present invention, the thickness of the perovskite light-absorbing layer containing thiopyrimidine is 500-800 nm.

[0014] Another objective of this invention is to overcome the shortcomings of the prior art and provide a method for preparing a perovskite thin-film solar cell, characterized by comprising:

[0015] An electron transport layer was fabricated on the surface of an FTO substrate;

[0016] Prepare a perovskite light-absorbing layer containing thiopyrimidine on the surface of the electron transport layer: Mix the perovskite precursor solution with the thiopyrimidine solution to prepare a composite light-absorbing layer on the surface of the electron transport layer.

[0017] A hole transport layer and a top electrode are fabricated on the surface of a perovskite light-absorbing layer containing thiopyrimidine to obtain a perovskite solar cell.

[0018] As a preferred embodiment of the preparation method described in this invention, the electron transport layer is prepared on the surface of the FTO substrate, and the preparation method includes blade coating, spin coating, spray coating, chemical bath deposition, and atomic force deposition.

[0019] In a preferred embodiment of the preparation method described in this invention, a thiopyrimidine-containing perovskite light-absorbing layer is prepared on the surface of the electron transport layer, wherein a thiopyrimidine-containing perovskite precursor solution is spin-coated onto the electron transport layer.

[0020] In a preferred embodiment of the preparation method described in this invention, the rotational speed of the spin coating is 3000-5000 r / s, the acceleration is 1000-6000 r / s, and the spin coating time is 25-35 s.

[0021] As a preferred embodiment of the preparation method described in this invention, the spin coating is followed by annealing at 100–150°C for 50–70 min.

[0022] As a preferred embodiment of the preparation method described in this invention, the solvent of the perovskite precursor solution includes one or a mixture of two or more of N,N-dimethylformamide and dimethyl sulfoxide.

[0023] Another objective of this invention is to overcome the shortcomings of the prior art and provide an application of perovskite thin-film solar cells.

[0024] Beneficial effects of this invention:

[0025] Thiopyrimidines generate dimers via dehydrogenation, reducing I2 and I3. - Inhibit methylamine (MA) + ) and formamidin (FA + The deprotonation reaction reduces byproduct formation and lowers the risk of chemical degradation of the perovskite precursor, improving device reproducibility and stability. Simultaneously, during perovskite crystallization and growth, it reacts with free lead ions (Pb). 2+ The formation of coordination bonds effectively regulates the crystallization kinetics, resulting in a denser and more uniform microstructure of the perovskite film. This reduces grain boundary defects and ion migration channels, thereby enhancing the stability of device operation. This chemical regulation strategy also leads to a significant improvement in open-circuit voltage, fill factor, and photoelectric conversion efficiency, enabling perovskite solar cells to maintain high efficiency while possessing excellent long-term stability. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0027] Figure 1 This is a schematic diagram of the basic structure of the perovskite solar cell of the present invention;

[0028] Figure 2 The in-situ UV-Vis absorption spectra of films prepared by aging the perovskite precursor solutions of Example 1 and Comparative Example 1 at different times during the initial annealing stage are shown.

[0029] Figure 3 Scanning electron microscope (SEM) images of the thin film surfaces prepared by aging the perovskite precursor solutions of Example 1 and Comparative Example 1 of the present invention for different times.

[0030] Figure 4 Based on Example 1 of this invention, different amounts of 2-thiouracil are introduced into the perovskite photoactive layer PSCs (a)V OC Distribution map; (b)J SC Distribution plot; (c) FF distribution plot; (d) PCE distribution plot;

[0031] Figure 5 X-ray photoelectron spectroscopy (XPS) characterization of the perovskite precursor solution thin films of Example 1 and Comparative Example 1 of the present invention: (a) Pb 4f Orbital energy spectrum, (b)I 3d Orbital energy spectrum;

[0032] Figure 6 The JV test results are for the PSC devices of Embodiment 1 and Comparative Example 1 of this invention;

[0033] Figure 7 The efficiency distribution of the control group and experimental group devices of the PSC devices of Example 1 and Comparative Example 1 of the present invention under different aging times;

[0034] Figure 8 The PSC devices of Embodiment 1 and Comparative Example 1 of the present invention were subjected to exposure to sunlight (100mW cm⁻¹) in an ambient air environment at 30°C and a relative humidity of 25±5%. -2 The maximum power point output (MPPT) tracking diagram of the package control and the target device;

[0035] Figure 9 The JV test results are for the PSC devices of Embodiment 2 and Comparative Example 2 of this invention;

[0036] Figure 10 The efficiency distribution of the control group and experimental group devices of the PSC devices of Example 2 and Comparative Example 2 of the present invention under different aging times;

[0037] Figure 11 The JV test results are for the PSC devices of Embodiment 3 and Comparative Example 3 of this invention;

[0038] Figure 12 The efficiency distribution of the control group and experimental group devices of the PSC devices of Example 3 and Comparative Example 3 of the present invention under different aging times. Detailed Implementation

[0039] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0040] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0041] Secondly, the term "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in various places throughout this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive of other embodiments.

[0042] All raw materials and reagents used in the embodiments of this invention are commercially available conventional products.

[0043] All operations in the embodiments of the present invention are performed under nitrogen or argon protection.

[0044] The performance testing method used in this embodiment of the invention:

[0045] (1) UV-vis spectroscopy test: In-situ UV-vis spectroscopy test can be dynamically monitored by a UV-Vis spectrophotometer: The mixture of molecular sieve and solvent is placed in a quartz in-situ reaction cell, the wavelength scanning range is set, and the absorbance change is recorded in real time using time-driven mode or full-spectrum scanning mode; Before the test, the baseline needs to be calibrated with pure solvent, and scattering correction or centrifugation pretreatment is enabled for turbid samples. The concentration of dissolved substances is quantitatively analyzed by combining the characteristic peak intensity change with the standard curve, and parameters such as temperature and stirring rate are recorded simultaneously to correlate the color change kinetic process.

[0046] (2) SEM testing: Scanning electron microscope is used. The specific process includes sample preparation, instrument parameter setting and testing procedure: The sample needs to be conductive (non-conductive material is sprayed with a 5-10nm gold / platinum layer), and the size is controlled within 1cm. 2 After cleaning and drying, the sample is fixed; during testing, the accelerating voltage (5-20kV), working distance (5-10mm), and detector (secondary electrons for morphology imaging, backscattered electrons for compositional contrast) are set, and the sample is vacuum-evacuated to ≤10. -3 After Pa, the observation area is located at low magnification and the focal length and astigmatism are adjusted. Finally, a high-magnification image of the surface microstructure (resolution up to 1-5 nm) is acquired. EDS energy dispersive spectroscopy or EBSD can be selected for elemental distribution and crystal orientation analysis.

[0047] (3) XPS test: X-ray photoelectron spectrometer is used. The specific process includes the following steps: The sample needs to be cleaned and dried and fixed on conductive tape or pressed into a block. Non-conductive samples need to be counteracted by using a low-energy electron gun or charge neutralizer to cancel the charging effect. When testing, monochromatic Al Kα rays (1486.6eV) are selected. The analyzer pass energy is set to 20-100eV, the scan step size is 0.05-1.0eV, and the binding energy range usually covers 0-1200eV to capture the characteristic peaks of C1s, O 1s and target elements. Before the test, the instrument is calibrated with a standard sample (such as Au 4f7 / 2, 84.0eV). When acquiring high-resolution spectra, multiple scans (5-20 times) are used to improve the signal-to-noise ratio. Data analysis is performed using professional software (such as CasaXPS) for peak fitting, element quantification and chemical state analysis.

[0048] (4) JV curve test: Using a solar simulator, the test steps are as follows: First, calibrate the simulator light source to AM1.5G spectrum (100mW / cm²). 2 To ensure irradiation uniformity (<±2%), the battery sample was fixed on a temperature-controlled stage (25℃) and covered with a mask to limit the effective illumination area. The battery electrodes were connected using a four-probe method, and the voltage scan range (typically from -0.1 to 1.2V) and scan rate (10-100mV / s) were set. The current density (J) and voltage (V) data were recorded synchronously using a source meter. Before testing, the sample needed to be stabilized in the dark for 5 minutes to eliminate transient response. Bidirectional scanning in both forward and reverse directions was used to verify repeatability. Finally, the open-circuit voltage (Voc), short-circuit current (Jsc), fill factor (FF), and photoelectric conversion efficiency (PCE) were fitted using software.

[0049] (5) MPPT curve test: The solar cell IV characteristic test system was used. The test steps are as follows: First, the simulator was calibrated to the AM1.5G standard spectrum (1000W / m). 2 The battery temperature is stabilized (25±0.5℃) using a temperature control station, and the electrodes are connected using a four-probe method. A dynamic load scanning mode is set, and the output voltage is automatically adjusted in steps of 10-50mV within the 0-Voc range. Each voltage point is held for 20-200ms to ensure steady-state current reading (compensating for capacitance effect), and current-voltage data is recorded synchronously. The power curve is calculated in real time using a built-in algorithm, and the maximum power point (Pmax) is locked. After testing, repeatability is verified (deviation <2% for 3 cycles of scanning). Data analysis requires correction of light intensity spatial uniformity (>98%) and spectral matching degree (A+ level). The final output is the power-voltage (PV) curve and key parameters (MPPT efficiency, fill factor, etc.).

[0050] Example 1

[0051] This embodiment prepares a formal perovskite solar cell with a light-absorbing layer containing a 2-thiourea pyrimidine stabilizer, specifically including the following steps:

[0052] (1) Substrate pretreatment:

[0053] The FTO conductive glass was patterned using a nanosecond laser with an area of ​​1.5cm × 2cm. Then, the FTO glass was ultrasonically cleaned three times sequentially with pure water containing detergent, deionized water, and anhydrous ethanol. After cleaning, it was dried and placed in a dry, clean container for later use.

[0054] (2) Fabrication of the electron transport layer:

[0055] SnO2 thin films were prepared by chemical bath deposition, and the preparation process is as follows:

[0056] ①Preparation of SnCl2 mother liquor:

[0057] Add 400 mL of pure water to a clean SnCl2 bottle and refrigerate until needed. Slowly add 5 mL of concentrated HCl to the prepared pure water, then add 5 g of urea and stir until dissolved. Dissolve 1.096 g of SnCl2·2H2O in the solution, and finally add 100 μL of mercaptoacetic acid. Shake well and store in the refrigerator until needed.

[0058] ②Preparation of SnO2 thin films:

[0059] Take 20 mL of the stock solution into a clean glass container, then add 100 mL of pure water and shake well to dilute. Remove the cleaned FTO glass. Place the FTO glass into a container containing the diluent and heat in a 90°C oven for 180 minutes.

[0060] Anneal at 170℃ for 60 minutes, and after cooling to room temperature, store in a clean container for later use.

[0061] (3) Preparation of perovskite precursors containing 2-thiourea pyrimidine stabilizer:

[0062] ① Preparation of perovskite precursor solution:

[0063] Dissolve 240.76 mg FAI (formamidinium hydroiodide), 691.52 mg Pbl2 and 33.76 mg MACl (methylamine hydrochloride) in 1 ml DMF / DMSO (v / v = 4:1) to prepare a pristine perovskite precursor solution. Then add 0.2 mg 2-thiouracil (Th) to obtain a perovskite precursor solution with a stabilizer.

[0064] ② Preparation of perovskite light-absorbing layer containing 2-thiouracil:

[0065] Transfer the substrate and the perovskite precursor solution containing 2-thiouracil to a nitrogen glove box (glove box temperature not exceeding 25°C), and filter the perovskite precursor solution containing 2-thiouracil for later use.

[0066] Using a pipette, a suitable amount of perovskite solution containing 2-thiouracil was evenly coated onto the substrate. The spin coater program was set as follows: Step 1: 1000 rpm, acceleration 1000 rpm / s, rotation for 10 s; Step 2: 5000 rpm, acceleration 1000 rpm / s, rotation for 30 s. At the 15th second before the end of Step 2, 100 μL of ethyl acetate (EA) was rapidly added. After the spin coater finished rotating, a wet film was obtained. The wet film was transferred to a hot plate at 100°C for annealing for 60 minutes, then removed and cooled before being stored in a clean container for later use.

[0067] (4) Preparation of the hole transport layer:

[0068] Preparation of Spiro-OMeTAD solution: Weigh 520 mg of Li-TFSI powder and dissolve it in 1 mL of ACN solvent. Shake well, filter, and prepare a Li salt solution for later use. Weigh 300 mg of Co-TFSI and dissolve it in 1 mL of acetonitrile (ACN) solvent. Shake well, filter, and prepare a Co salt solution for later use. Weigh 73 mg of Spiro-OMeTAD powder and add 1 mL of chlorobenzene (CBZ), 18 μL of Li salt solution, 29 μL of Co salt solution, and 30 μL of 4-tert-butylpyridine (tBP). Seal the solution and place it in a shaker to shake until completely dissolved.

[0069] Transfer the prepared Spiro-OMeTAD solution to a nitrogen glove box. Using a pipette, take an appropriate amount of Spiro-OMeTAD solution and spin-coat it onto the annealed perovskite film. Spin-coating parameters: rotation speed 3000 rpm, acceleration 3000 rpm / s, time 30 s. After the hole transport layer is prepared, transfer the semiconductor device to a drying cabinet.

[0070] (5) Preparation of metal electrodes:

[0071] The metal electrode used in the formal structure of the perovskite solar cell is gold (Au). The semiconductor device is transferred onto a substrate in a vapor deposition apparatus, and an Au film with a thickness of approximately 80 nm is deposited in a vacuum vapor deposition apparatus to obtain the complete perovskite device.

[0072] Using a formal structure of FTO / SnO2 / perovskite / spiro-OMeTAD / Au, the effect of solution placement on the device performance of the corresponding PSC was investigated. Compared with the reference device with a maximum PCE of 23.99%, the device based on the 2-thiouracil precursor has a higher PCE. The resulting perovskite solar cell device with a 2-thiouracil stabilizer in the absorber layer has a PCE of 25.13%, a fill efficiency (FF) of 0.84, an open-circuit voltage (Voc) of 1.181 V, and a short-circuit current (Jsc) of 25.31 mA / cm². -2 After 30 days of solution incubation, the average efficiency of the device based on the 2-thiouracil precursor remained at 94.78%, the highest value at the initial test (25.13%), while the reference device only maintained 64.22% of the initial value.

[0073] Example 2

[0074] This embodiment prepares a trans-perovskite solar cell with a light-absorbing layer containing a 6-methyl-2-thioureapyrimidine stabilizer, specifically including the following steps:

[0075] (1) Substrate pretreatment:

[0076] The ITO glass was cut into 2cm x 2cm pieces using a glass cutter and then patterned using a nanosecond laser. The ITO glass was then ultrasonically cleaned three times sequentially with pure water containing detergent, deionized water, and anhydrous ethanol. After cleaning, it was dried and placed in a dry, clean container for later use.

[0077] (2) Weigh 0.5 mg of SAM (MeO-2PACz or MeO-4PACz or Poly-4PACz) and dissolve it in 1 ml of isopropanol (IPA) and stir until completely dissolved.

[0078] The SAM solution was coated onto ITO at a speed of 4000 rpm and an acceleration of 1000 rpm / s for 30 seconds, and then annealed at 100°C for 10 minutes before being removed.

[0079] (3) Weigh 100 μL of Al2O3 dispersion into 2 mL of IPA.

[0080] The Al2O3 / IPA solution was coated onto the SAM layer at a speed of 6000 rpm, an acceleration of 3000 rpm / s, and a spin coating time of 30 s. Then, it was annealed on a hot plate at 120℃ for 10 min.

[0081] (4) Preparation of perovskite precursors containing 6-methyl-2-thiouracil stabilizer:

[0082] Dissolve 12.08 mg MAI (methylamine hydroiodide), 19.75 mg CsI (cesium iodide), 235.25 mg FAI, 714.57 mg Pbl2 and 13.5 mg MACl in 1 ml DMF / DMSO (4:1 v / v) to prepare a raw perovskite precursor solution. Then add 0.15 mg 6-methyl-2-thiouracil to obtain a perovskite precursor solution with a stabilizer.

[0083] (5) Preparation of a perovskite light-absorbing layer containing 6-methyl-2-thiouracil:

[0084] Transfer the substrate and the 6-methyl-2-thiouracil perovskite precursor solution to a nitrogen glove box (glove box temperature not exceeding 22℃). Filter the 6-methyl-2-thiouracil perovskite precursor solution for later use. Using a pipette, take an appropriate amount of the 6-methyl-2-thiouracil perovskite solution and evenly coat it onto the substrate. Set the spin coater program as follows: Step 1: Rotate at 1000 rpm with an acceleration of 1000 rpm / s for 10 seconds. Step 2: Rotate at 5000 rpm with an acceleration of 1000 rpm / s for 30 seconds. After a 5-second countdown, add 150 μL of the antisolvent EA. Then anneal at 60℃ for 10 minutes, followed by annealing at 100℃ for 30 minutes.

[0085] (6) Dissolve 20 mg PCBM in 1 mL CBZ to obtain PCBM solution. Spin-coat the PCBM solution onto a PVK substrate at a speed of 3000 rpm, an acceleration of 1500 rpm / s, and a spin coating time of 30 s, and then anneal at 70 °C for 5 min.

[0086] (7) BCP (7nm) was sequentially deposited in a vacuum evaporation apparatus. ) and Ag(120nm, After that, the device was fabricated, and a complete perovskite solar cell was obtained.

[0087] (8) The device performance of the corresponding PSC was studied using the inverse structure of ITO / SAM / Al2O3 / perovskite / PCBM / BCP / Ag. Compared with the reference device with a maximum PCE of 24.04%, the device based on the 6-methyl-2-thiouracil precursor has a higher PCE. The obtained perovskite solar cell device with 6-methyl-2-thiouracil stabilizer in the absorber layer has a PCE of 25.36%, a fill efficiency FF of 0.84, an open-circuit voltage Voc of 1.178V, and a short-circuit current Jsc of 25.75mA / cm. -2 After 30 days of solution incubation, the average efficiency of the device based on the 6-methyl-2-thiouracil precursor remained at 92.2%, the highest value at the initial test (25.37%), while the reference device only maintained 49.99% of the initial value.

[0088] Example 3

[0089] This embodiment prepares an inverted perovskite solar cell with a light-absorbing layer containing a 5-methyl-2-thiouracil stabilizer, specifically including the following steps:

[0090] Steps (1), (6), (7), and (8) are the same as in Example 2. Steps (4), (5), and (8) are as follows:

[0091] (4) Preparation of perovskite precursor containing 5-methyl-2-thiouracil stabilizer: Dissolve 12.08 mg MAI (methylamine hydroiodide), 19.75 mg CsI (cesium iodide), 235.25 mg FAI, 714.57 mg Pbl2 and 13.5 mg MACl in 1 ml DMF / DMSO (4:1 v / v) to prepare the original perovskite precursor solution, and then add 0.16 mg 5-methyl-2-thiouracil to obtain the perovskite precursor solution with stabilizer;

[0092] (5) Preparation of the perovskite absorber layer containing 5-methyl-2-thiouracil: Transfer the substrate and the perovskite precursor solution containing 5-methyl-2-thiouracil to a nitrogen glove box (glove box temperature not exceeding 22℃), and filter the perovskite precursor solution containing 5-methyl-2-thiouracil for later use. Use a pipette to take an appropriate amount of the perovskite solution containing 5-methyl-2-thiouracil and evenly coat it onto the substrate. Set the spin coater program as follows: Step 1: Rotate at a speed of 1000 rpm and an acceleration of 1000 rpm / s for 10 s. Step 2: Rotate at 5000 rpm and an acceleration of 1000 rpm / s for 30 s. After the countdown of 5 s, drop 150 μL of antisolvent EA. Then anneal at 60℃ for 10 minutes, and then anneal at 100℃ for 30 minutes.

[0093] (8) The device performance of the corresponding PSC was studied using the inverse structure of ITO / SAM / Al2O3 / perovskite / PCBM / BCP / Ag. Compared with the reference device with a maximum PCE of 23.87%, the device based on the 5-methyl-2-thiouracil precursor has a higher PCE. The obtained perovskite solar cell device with 5-methyl-2-thiouracil stabilizer in the light-absorbing layer has a PCE of 25.06%, a fill efficiency FF of 0.837, an open-circuit voltage Voc of 1.18V, and a short-circuit current Jsc of 25.37mA / cm. -2 After 30 days of solution incubation, the average efficiency of the device based on the 5-methyl-2-thiouracil precursor remained at 92.21%, the highest value at the initial test (25.04%), while the reference device only maintained 61.36% of the initial value.

[0094] Comparative Example 1

[0095] This comparative example is a formal perovskite solar cell prepared using a common perovskite photoactive layer. The preparation method is the same as in Example 1, except that no modifying material, namely 2-thiouracil, was used.

[0096] Comparative Example 2

[0097] This comparative example is a formal perovskite solar cell prepared using a common perovskite photoactive layer. The preparation method is the same as in Example 2, except that no modifying material, namely 6-methyl-2-thiouracil, was used.

[0098] Comparative Example 3

[0099] This comparative example is a formal perovskite solar cell prepared using a common perovskite photoactive layer. The preparation method is the same as in Example 3, except that no modifying material, namely 5-methyl-2-thiouracil, was used.

[0100] Performance testing

[0101] Figure 2 The in-situ UV-Vis spectra of the films prepared for different aging times in Example 1 and Comparative Example 1 of this invention are shown in the following figures at the initial annealing stage: (a) fresh solution, (b) solution aged for 10 days, and (c) solution aged for 20 days. As the aging time of the perovskite precursor solution increases, the crystallization rate gradually slows down. For Comparative Example 1, the initial crystallization peaks at 0, 10, and 20 days are 21.4 seconds, 24.7 seconds, and 26.3 seconds, respectively. The addition of Th caused the start time of the first stage of small grain growth to be earlier than that of the control sample, and the initial crystal adjustment time was longer. After aging for 30 days, the crystallization rate of the solution containing Th stabilizer was close to that of the control sample prepared from the fresh solution, indicating that Th effectively delayed the aging process of the precursor solution.

[0102] Figure 3 To compare the SEM morphology of films prepared for different aging times in Example 1 and Comparative Example 1 of this invention, the addition of the Th precursor stabilizer resulted in the disappearance of excess PbI2 particles at the perovskite grain boundaries, an increase in surface grain size, and a smoother surface, which is beneficial for the deposition of the HTL layer and charge transport between interfaces. As the solution aging time increased, the morphological differences between the control and experimental groups became increasingly significant: the control sample initially showed scattered PbI2 particles, which then appeared in patches as the solution aged. The control film prepared after 30 days of aging showed pores, while the experimental sample only showed a small amount of PbI2 precipitation. This indicates that Th effectively delayed the precursor solution aging process.

[0103] Figure 4The figures show (a) VOC distribution, (b) JSC distribution, (c) FF distribution, and (d) PCE distribution of perovskite solar cells with different amounts of 2-thiouracil introduced into the perovskite photoactive layer in Example 1 of this invention (except for the amount of 2-thiouracil, the other steps and conditions are the same as in Example 1). The performance of each parameter is shown in the figures. It was found that when the stabilizer concentration is below 0.5%, it has a positive effect on device performance. However, when the stabilizer concentration is excessive, it will greatly degrade device performance. When the stabilizer concentration is 0.2%, the device performance is the best, achieving a champion PCE of 25.13%, with a VOC of 1.181V and a JSC of 25.31mA cm⁻¹. -2 The photoelectric efficiency (FF) is 84.0%, which is a significant improvement compared to the highest photoelectric conversion efficiency (PCE = 23.99%) of the control group.

[0104] Figure 5 XPS analysis of the perovskite thin films of Example 1 and Comparative Example 1 of the present invention, wherein (a) Pb4f orbital energy spectrum, (b) I 3d Orbital energy spectrum. The binding energy peaks at 143.47 eV and 138.61 eV in the control group film prepared from fresh solution correspond to Pb, respectively. 2+ The 4f5 / 2 and 4f7 / 2 orbitals, with two shoulder peaks at 141.75 eV and 136.85 eV, belong to the 4f5 / 2 and 4f7 / 2 orbitals of metallic Pb0. After solution aging, the Pb0 / Pb ratio in the control group film... 2+ The proportion increased from 3.40% to 7.85%. The Pb0 signal of films prepared from both fresh and aged precursor solutions in the experimental group decreased significantly, by 0.61% and 0.68%, respectively, indicating that Th and Pb... 2+ The coordination effect inhibits the formation of metallic lead (PbO), thereby delaying the degradation of the film.

[0105] Figure 6 The JV test results are for the PSCs (perovskite solar cells) in Example 1 and Comparative Example 1 of this invention. Due to the hysteresis effect, efficiency comparisons of perovskite solar cells are generally more direct by comparing RS data. The perovskite solar cell device has a PCE of 25.13%, a fill efficiency FF of 0.840, an open-circuit voltage Voc of 1.181V, and a short-circuit current Jsc of 25.31mA. -2 Therefore, it can be concluded that 2-thiouracil-modified perovskite solar cells exhibit better photoelectric performance in small-area PSCs.

[0106] Figure 7The diagram shows the efficiency distribution of PSCs in Examples 1 and 1 of this invention at different aging times for the control and experimental groups. (a) shows the efficiency distribution of PSCs aged in Th-free solutions for different times; (b) shows the efficiency distribution of PSCs aged in Th-containing solutions for different times. With prolonged aging time, the PCE of the control group devices decreased significantly, with an average lifetime of only 64.22% of the initial value after 30 days. In contrast, the PCE of the experimental group devices only showed a slight decrease, with an average lifetime reaching 94.78% of the initial value. This indicates that Th can effectively stabilize the precursor solution by inhibiting the degradation of A-site salts and the oxidation of I-.

[0107] Figure 8 This document describes the MPPT tracking test results of the PSCs in Embodiment 1 and Comparative Example 1 of this invention under encapsulated conditions. Encapsulation involves first soldering wires to both the positive and negative electrodes, then completely covering the metal electrode portion with a glass slide, placing it in a mold, and pouring AB glue over it. The wires are kept outside the glue, and the battery portion is encapsulated once curing is complete, minimizing the influence of water and oxygen. Testing is conducted via external wires. To further evaluate the long-term operational stability of the device, it was tested in ambient air at 30°C and 255% relative humidity under a single exposure to sunlight (100 mW cm⁻¹). -2 MPPT tracking was performed on the device. Comparative Example 1 decayed to 41.32% of the initial PCE after 1000 hours. However, after 1000 hours of continuous MPPT tracking, Example 1 maintained 87.8% of the initial PCE. This indicates that Th significantly improves the thermal and optical stability of PSCs.

[0108] Figure 9 The JV test results for the PSCs (perovskite solar cells) in Example 2 and Comparative Example 2 of this invention are shown. Due to the hysteresis effect, efficiency comparisons of perovskite solar cells are generally more direct by comparing RS data. The perovskite solar cell device has a PCE of 25.36%, a fill efficiency FF of 0.836, an open-circuit voltage Voc of 1.178V, and a short-circuit current Jsc of 25.75mA. -2 Therefore, it can be concluded that, among small-area PSCs, perovskite solar cells modified with 6-methyl-2-thiouracil exhibit better photoelectric performance.

[0109] Figure 10 The table shows the efficiency distribution of the control group and experimental group devices of PSCs in Example 2 and Comparative Example 2 of this invention under different aging times. As the aging time increases, the PCE of the control group device decreases significantly, and the average lifetime after 30 days is only 61.36% of the initial value; while the PCE of the experimental group device only shows a slight decrease, and the average lifetime reaches 92.21% of the initial value. This shows that MZU can effectively stabilize the precursor solution by inhibiting the degradation of A-site salt and the oxidation of I-.

[0110] Figure 11 The JV test results for the PSCs (perovskite solar cells) in Example 3 and Comparative Example 3 of this invention are shown. Due to the hysteresis effect, efficiency comparisons of perovskite solar cells are generally more direct by comparing RS data. The perovskite solar cell device has a PCE of 25.06%, a fill efficiency FF of 0.837, an open-circuit voltage Voc of 1.180V, and a short-circuit current Jsc of 25.21mAcm. -2 Therefore, it can be concluded that, among small-area PSCs, perovskite solar cells modified with 5-methyl-2-thiouracil exhibit better photoelectric performance.

[0111] Figure 12 The table shows the efficiency distribution of the control and experimental groups of PSCs in Examples 3 and 3 of this invention under different aging times. With prolonged aging time, the PCE of the control group devices decreased significantly, with an average lifetime of only 49.99% of the initial value after 30 days; while the PCE of the experimental group devices only showed a slight decrease, with an average lifetime reaching 92.20% of the initial value. This indicates that ThM inhibits the degradation of A-site salts and I... - Oxidation can effectively stabilize the precursor solution.

[0112] This invention employs the formal structure of FTO / SnO2 / perovskite / spiro-OMeTAD / Au to investigate the effect of solution placement on the device performance of the corresponding PSC. Compared to the reference device with a maximum PCE of 23.99%, the device based on the 2-thiouracil precursor has a higher PCE. The resulting perovskite solar cell device with a 2-thiouracil stabilizer in the absorber layer has a PCE of 25.13%, a fill efficiency (FF) of 0.84, and an open-circuit voltage (Vo). oc The voltage is 1.181V, and the short-circuit current Jsc is 25.31mA / cm. -2 After 30 days of solution incubation, the average efficiency of the device based on the 2-thiouracil precursor remained at 94.78%, the highest value at the initial test (25.13%), while the reference device only maintained 64.22% of the initial value.

[0113] This invention also employs an inverse structure of ITO / SAM / Al2O3 / perovskite / PCBM / BCP / Ag to investigate the device performance of the corresponding PSC. Compared to the reference device with a maximum PCE of 23.87%, the device based on the 5-methyl-2-thiouracil precursor has a higher PCE. The resulting perovskite solar cell device with a 5-methyl-2-thiouracil stabilizer in the absorber layer has a PCE of 25.06%, a fill efficiency (FF) of 0.837, and an open-circuit voltage (Vo). oc The voltage is 1.18V, and the short-circuit current Jsc is 25.37mA / cm. -2After 30 days of solution incubation, the average efficiency of the device based on the 5-methyl-2-thiouracil precursor remained at 92.21%, the highest value at the initial test (25.06%), while the reference device only maintained 61.36% of the initial value.

[0114] This invention involves adding thiopyrimidine to a precursor solution to prepare a perovskite light-absorbing layer. The unique molecular structure of thiopyrimidine (containing S and O coordination sites and a suitable pKα value) exhibits the potential to synergistically suppress side reaction chains, thereby mitigating the aforementioned harmful side reactions. The open-circuit voltage, cell efficiency, and stability of the resulting perovskite solar cell are improved through assembly with electron transport materials, hole transport materials, conductive glass, and metal electrodes.

[0115] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the present invention.

Claims

1. A perovskite thin-film solar cell, characterized in that: The perovskite thin-film solar cell includes a thiopyrimidine-modified perovskite light-absorbing layer, a substrate, an electron transport layer, a hole transport layer, and a top electrode. The perovskite has an ABX3 type structure, with the A-site selected from methylamine (MA). + or formamidin FA + B is selected from Pb 2+ or Sn 2+ The X position is iodine I. - ; The thiopyrimidine is one of 2-thiouracil (Th), 5-methyl-2-thiouracil (ThM), or 6-methyl-2-thiouracil (MZU).

2. The perovskite thin-film solar cell as described in claim 1, characterized in that: The perovskite material includes one of FAMAPbI3, FAPbI3, and CsMAFAPbI3.

3. The perovskite thin-film solar cell as described in claim 1, characterized in that: The thickness of the perovskite light-absorbing layer containing thiopyrimidine is 500–800 nm.

4. The method for preparing a perovskite thin-film solar cell according to any one of claims 1 to 3, characterized in that: include, An electron transport layer was fabricated on the surface of an FTO substrate; Prepare a perovskite light-absorbing layer containing thiopyrimidine on the surface of the electron transport layer: Mix the perovskite precursor solution with the thiopyrimidine solution to prepare a composite light-absorbing layer on the surface of the electron transport layer. A hole transport layer and a top electrode are fabricated on the surface of a perovskite light-absorbing layer containing thiopyrimidine to obtain a perovskite solar cell.

5. The preparation method according to claim 4, characterized in that: The electron transport layer is prepared on the surface of the FTO substrate by methods including blade coating, spin coating, spray coating, chemical bath deposition, and atomic force deposition.

6. The preparation method according to claim 4, characterized in that: The process involves preparing a thiopyrimidine-containing perovskite light-absorbing layer on the surface of the electron transport layer, wherein a thiopyrimidine-containing perovskite precursor solution is spin-coated onto the electron transport layer.

7. The preparation method according to claim 6, characterized in that: The rotational coating process involves a rotational speed of 3000–5000 r / s, an acceleration of 1000–6000 r / s, and a spin coating time of 25–35 s.

8. The preparation method according to claim 6, characterized in that: The spin coating is followed by annealing at 100–150°C for 50–70 min.

9. The preparation method according to claim 4, characterized in that: The solvent of the perovskite precursor solution includes one or a mixture of two or more of N,N-dimethylformamide and dimethyl sulfoxide.

10. Application of the perovskite thin-film solar cell prepared by the preparation method according to any one of claims 4 to 9.

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