N-p-toluenesulfonyl-L-arginine modification-based perovskite thin film, preparation method thereof and solar cell

Abstract

The invention belongs to the technical field of photoelectric materials, and particularly relates to a perovskite thin film based on N-p-toluenesulfonyl-L-arginine modification, a preparation method of the perovskite thin film and a solar cell. N-p-toluenesulfonyl-L-arginine is added into a CsPbI2Br perovskite precursor solution, and a CsPbI2Br perovskite thin film grows by adopting stage spin coating and gradient annealing. Through the interaction between the N-p-toluenesulfonyl-L-arginine and the CsPbI2Br perovskite thin film, the light absorption performance, the luminescence performance, the room-temperature black phase stability, the air stability and the optical stability of the CsPbI2Br perovskite thin film are remarkably improved, so that the photoelectric conversion efficiency and the stability of a device are remarkably improved. The material system shows excellent characteristics in photovoltaic power generation application, the thin film prepared based on the technology can effectively improve the energy conversion efficiency of photoelectric devices such as solar cells and the like, a feasible technical path is provided for industrial application of new-generation efficient solar cells, and the material system has remarkable market application value and industrial prospects.

Description

Technical Field

[0001] This invention belongs to the field of optoelectronic materials technology, and in particular relates to a perovskite thin film modified with N-p-toluenesulfonyl-L-arginine, its preparation method and solar cell. Background Technology

[0002] Since the beginning of the 21st century, the accelerated pace of global industrialization has led to a dramatic increase in the consumption of traditional energy sources, resulting in increasingly severe environmental pollution problems. Among numerous clean energy solutions, solar energy has become a research focus due to its wide availability and diverse conversion methods. In recent years, perovskite materials have demonstrated enormous potential in the photovoltaic field. Thanks to their excellent photoelectric properties, the photoelectric conversion efficiency (PCE) of perovskite solar cells (PSCs) has jumped from an initial 3.8% to 27.3%, approaching the 27.6% level of mainstream crystalline silicon technology, showcasing tremendous industrialization prospects. However, its commercialization still faces key challenges such as black-phase instability and poor environmental stability.

[0003] Additive engineering, by introducing functional molecules into the precursor solution to regulate the crystallization kinetics and defect states of perovskite, has become a core strategy for solving the aforementioned problems. For example, Liu Shengzhong's research team used the green additive fumaric acid to add to the perovskite precursor solution to prepare a highly stable and efficient perovskite solar cell. The addition of fumaric acid not only stabilized the octahedral framework of the perovskite crystal and improved the long-term stability of the device, but also passivated defects. Compared with the control device, the modified device showed a 6.7% increase in photoelectric conversion efficiency.

[0004] This demonstrates that additive engineering plays a crucial role in the optimization of perovskite thin films. By precisely controlling crystal growth kinetics and defect state density, the overall performance of CsPbI2Br devices can be significantly improved.

[0005] This invention employs N-p-toluenesulfonyl-L-arginine as a functional additive. First, by controlling the crystallization process, a thin film with large grain size and low defect density is obtained. Second, the energy levels of the perovskite are optimized to improve the interfacial energy level matching between the perovskite and the charge transport layer. Finally, the phase stability, air stability, and optical stability of the thin film are enhanced, effectively suppressing nonradiative recombination and improving the photoelectric conversion efficiency of the device, thereby improving device stability. This multifunctional additive strategy not only solves the common problems of black-phase instability in CsPbI2Br thin films and low photoelectric conversion efficiency in perovskite solar cells, but also provides a new material modification approach for realizing efficient and stable perovskite optoelectronic devices. Summary of the Invention

[0006] The purpose of this invention is to provide a perovskite thin film modified with N-p-toluenesulfonyl-L-arginine, its preparation method, and a solar cell. By passivating grain boundary defects with N-p-toluenesulfonyl-L-arginine, the quality of the CsPbI2Br perovskite thin film is improved, thereby enhancing the stability and photoelectric conversion efficiency of the CsPbI2Br perovskite solar cell.

[0007] To achieve the above objectives, the present invention provides a perovskite film modified with N-p-toluenesulfonyl-L-arginine, which is obtained by adding N-p-toluenesulfonyl-L-arginine to a CsPbI2Br perovskite precursor solution and growing it by staged spin coating and gradient annealing.

[0008] Its preparation method includes the following steps: S1 is prepared by adding N-p-toluenesulfonyl-L-arginine to a CsPbI2Br perovskite precursor solution and dissolving it completely to obtain a mixture. S2 uses FTO conductive glass covered with a planar SnO2 / SnCl2 thin film as a substrate. The mixture obtained in S1 is spin-coated onto the substrate in a single film-forming stage, and then CsPbI2Br all-inorganic perovskite thin film is grown by gradient annealing.

[0009] Preferably, the N-p-toluenesulfonyl-L-arginine has an average molecular weight of 128.15. The FTO conductive glass has dimensions of 20 mm × 20 mm, a sheet resistance of 14 Ω, and a light transmittance ≥90%.

[0010] Preferably, the CsPbI2Br perovskite precursor solution in S1 is prepared by dissolving CsI, PbI2, and PbBr2 in a dimethyl sulfoxide organic solution.

[0011] Preferably, the concentration of the CsPbI2Br perovskite precursor solution in S1 is 1.0–2.0 mol / L, i.e., the Cs concentration. The mass percentage concentration of N-p-toluenesulfonyl-L-arginine in the mixture is 2 wt%–8 wt%.

[0012] This invention effectively improves the room-temperature phase stability of perovskite films by controlling the amount of N-toluenesulfonyl-L-arginine added, providing a feasible approach for preparing high-quality, stable perovskite films. Insufficient addition leads to increased grain boundary defects, poor crystallinity, and unsatisfactory air and optical stability. Excessive addition causes film stacking, making the film uneven, and also increases grain boundary defects, thus affecting the film's optical properties. Only with an appropriate amount of N-toluenesulfonyl-L-arginine can a CsPbI₂Br perovskite film with optimal performance be obtained. CsPbI₂Br perovskite films with an appropriate amount of N-toluenesulfonyl-L-arginine exhibit larger grain size, fewer grain boundary defects, dense and smooth texture, and high crystallinity, while also possessing good room-temperature black phase stability, air stability, and optical properties. This results in CsPbI₂Br perovskite devices with an optimal PCE of 12.15%. This invention is of great significance for the research and application of optoelectronic devices.

[0013] Preferably, the dissolution in S1 is carried out by stirring under constant temperature heating, and after dissolution, the solution is filtered through a polytetrafluoroethylene filter.

[0014] Preferably, the constant temperature heating for dissolving in S1 is 80℃~120℃, and the stirring time for dissolving is 0.5~5h.

[0015] Preferably, the amount of the spin-coated perovskite precursor mixture in stage S2 is 100µL~150µL.

[0016] Preferably, the spin coating in S2 includes a first-stage spin coating and a second-stage spin coating. The spin coating speed of the first stage is 500-900 rpm and the spin coating time of the first stage is 10-16 s. The spin coating speed of the second stage is 800-1400 rpm and the spin coating time of the second stage is 80-140 s.

[0017] This invention improves the quality of perovskite films by performing spin coating in stages, thereby enhancing the film's coverage, uniformity, and crystallinity.

[0018] Preferably, in S2, the gradient annealing is performed by first annealing at a temperature of 50~90℃ for 2~8 min, and then annealing at 105~155℃ for 1~6 min.

[0019] This invention improves the quality of perovskite films by employing gradient temperature annealing, thereby increasing film coverage, crystallinity, grain size, and uniformity of size distribution, and reducing defect density.

[0020] By using the above-mentioned perovskite thin film modified based on N-p-toluenesulfonyl-L-arginine, high-performance CsPbI2Br perovskite solar cells can be further obtained.

[0021] Preferably, a hole transport layer can be prepared on the film prepared in S2, for example, 25~75μL of Spiro-OMeTAD can be spin-coated at a spin-coating speed of 2500~4500rpm and a spin-coating time of 10~40s.

[0022] Furthermore, electrodes can be fabricated on the prepared hole transport layer, for example, an Ag electrode with a thickness of 60~100 nm can be deposited on Spiro-OMeTAD.

[0023] This invention effectively passivates grain boundary defects and reduces grain boundaries in CsPbI₂Br perovskite precursor solutions by adding N-p-toluenesulfonyl-L-arginine organic additives, thereby hindering water penetration and perovskite degradation and promoting uniform grain growth. Consequently, the room-temperature black phase stability, air stability, and optical stability of CsPbI₂Br films are significantly improved, while the photoelectric conversion efficiency of the devices is also enhanced.

[0024] Mechanism of the invention: This invention selects N-p-toluenesulfonyl-L-arginine (Tos-Arg) as an organic additive, with the following molecular structure. Because the O atom in the S=O group, the O atom in the C=O group, and the N atom in the C=N group of the Tos-Arg molecule participate in the interaction with Cs... + / Pb 2+ The coordination process; the H atom in the N–H group of Tos-Arg reacts with the halide anion Br. - / I - Hydrogen bonds are formed between them. This bonding between Tos-Arg and CsPbI₂Br can improve film quality and enhance phase stability, optical stability, and air stability. Therefore, adding an appropriate mass percentage concentration of N-p-toluenesulfonyl-L-arginine can improve the morphology, structure, light absorption properties, luminescence properties, room temperature black phase stability, air stability, and optical stability of CsPbI₂Br perovskite films. N-p-Toluenesulfonyl-L-arginine molecular structure The beneficial effects of this invention are: (1) The present invention uses FTO conductive glass covered with a planar SnO2 / SnCl2 thin film as a substrate. The planar SnO2 / SnCl2 thin film has good chemical stability and electrical properties.

[0025] (2) In this invention, N-p-toluenesulfonyl-L-arginine additive is introduced into the CsPbI2Br perovskite precursor solution to form a composite system, which improves the structural stability, room temperature black phase stability, air stability and optical stability; increases the grain size, reduces the density of grain boundary defects, improves the crystallinity of perovskite and the compactness and flatness of the film, and enhances the optical performance.

[0026] (3) The present invention also optimizes the preparation conditions and parameters so that the prepared CsPbI2Br perovskite thin film has excellent performance and can be applied to the field of solar cells.

[0027] (4) The present invention provides a method for improving the performance of perovskite thin films and devices based on N-p-toluenesulfonyl-L-arginine organic additives. The preparation process is simple and easy to implement, and the cost is low. It has important research and application value.

[0028] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0029] Figure 1 These are field emission scanning electron microscope images of Embodiment 1 and Comparative Example 1 of the present invention; Figure 2 These are the X-ray diffraction patterns of Embodiment 1 and Comparative Example 1 of the present invention; Figure 3 These are the UV-Vis absorption spectra of optical stability of Embodiment 1 and Comparative Example 1 of the present invention; Figure 4 These are the ultraviolet-visible absorption spectra of Example 1 and Comparative Example 1 of the present invention; Figure 5 These are the fluorescence spectra of Example 1 and Comparative Example 1 of the present invention; Figure 6 These are the Fourier transform infrared spectra of the samples from Example 1 and Comparative Example 1 of this invention; Figure 7 These are the X-ray photoelectron spectra (XPS) of the samples from Example 1 and Comparative Example 1 of this invention. Figure 8 These are color change graphs of air stability of Embodiment 1 and Comparative Example 1 of the present invention after being stored in air for 0 to 90 minutes; Figure 9 These are the TRPL spectra of Embodiment 1 and Comparative Example 1 of the present invention; Figure 10 These are the Voc and light intensity regression curves of Embodiment 1 and Comparative Example 1 of the present invention; Figure 11 These are the JV curves of Embodiment 1 and Comparative Example 1 of the present invention; Figure 12These are the EIS diagrams and equivalent circuit diagrams of Embodiment 1 and Comparative Example 1 of the present invention; Figure 13 These are IPCE diagrams of Embodiment 1 and Comparative Example 1 of the present invention; Figure 14 The ultraviolet photoelectron spectroscopy (UPS) test of the sample in Example 1 and Comparative Example 1 of this invention; Figure 15 These are the photoelectric conversion efficiency (PCE) graphs for Embodiment 1 and Comparative Example 1 of the present invention. Detailed Implementation

[0030] The present invention will be further described below with reference to the accompanying drawings and embodiments. Unless otherwise defined, the technical or scientific terms used in this invention should be understood in their ordinary sense by those skilled in the art. Unless otherwise specified, the raw materials used in this invention are all commercially available products conventional in the art. The features mentioned above or in the specific examples mentioned in this invention can be combined arbitrarily, and these specific embodiments are only used to illustrate the invention and are not intended to limit the scope of the invention.

[0031] Example 1 CsI, PbI2, and PbBr2 were dissolved in dimethyl sulfoxide solution to obtain a CsPbI2Br perovskite precursor solution with a Cs concentration of 1.0 mol / L. Then, a was added to the CsPbI2Br perovskite precursor solution. i (i=1~6, a1=2<a2<a3<a4<a5<a6=8) wt% N-p-toluenesulfonyl-L-arginine was heated and stirred at 110℃ for 1 hour until completely dissolved to obtain a mixture. 125 μL of this mixture was dropwise added to an FTO / SnO2 / SnCl2 film substrate treated with UV ozone, and spin-coated in two stages: the first stage spin-coating speed was 800 rpm for 12 s; the second stage spin-coating speed was 1000 rpm for 100 s. Then, gradient annealing was performed, first at 60℃ for 4 min, and then at a higher temperature of 125℃ for 2 min, to obtain the FTO / SnO2 / SnCl2 / CsPbI2Br film. 50 μL of Spiro-OmeTAD was spin-coated onto the prepared FTO / SnO2 / SnCl2 / CsPbI2Br film at a spin-coating speed of 3000 rpm for 30 s. An Ag electrode was then deposited under vacuum to obtain a perovskite solar cell with a device structure of FTO / SnO2 / SnCl2 / CsPbI2Br / Spiro-OmeTAD / Ag.

[0032] Comparative Example 1 Based on Example 1, the difference from Example 1 is that N-p-toluenesulfonyl-L-arginine was not added, and all other aspects are the same as in Example 1.

[0033] Characterization experiments were performed on the CsPbI₂Br perovskite thin films and devices prepared in Example 1 and Comparative Example 1. The sample with N-p-toluenesulfonyl-L-arginine addition of 'a' at 5 wt% in Example 1 was designated CsPbI₂Br-Tos-Arg, and the sample in Comparative Example 1 was designated CsPbI₂Br. The following detailed description is in conjunction with the accompanying drawings: Figure 1 These are field emission scanning electron microscope images of Embodiment 1 and Comparative Example 1 of the present invention. Figure 1 Image (a) in the image is a field emission scanning electron microscope image of the CsPbI2Br perovskite thin film without Tos-Arg in Comparative Example 1. Figure 1 (bg) Field emission scanning electron microscope images of CsPbI2Br perovskite films with different concentrations of Tos-Arg added in Example 1; Figure 1 (hn) is for Figure 1 (ag) Corresponding grain size statistics. In Comparative Example 1, the thin film has blurred grain boundaries, poor crystallinity, and a small grain size of 522.78 nm. In contrast, the Tos-Arg modified thin film in Example 1 has clear grain boundaries, and the grain size increases from 522.78 nm to 948.21 nm, with a uniform grain size distribution, dense and smooth film, and good crystallinity. This indicates that adding an appropriate concentration of Tos-Arg is beneficial for improving the quality of CsPbI2Br perovskite thin films, thereby enhancing the photoelectric performance of photovoltaic devices.

[0034] Figure 2 The X-ray diffraction patterns are of the CsPbI2Br perovskite films of Comparative Example 1 (without Tos-Arg) and Example 1 (with Tos-Arg). The diffraction peaks at 14.9°, 20.9°, and 29.5° correspond to the (100), (110), and (200) crystal planes of the α-phase CsPbI2Br perovskite, respectively. Figure 2 The unmodified sample showed the disappearance of the (110) diffraction peak corresponding to the α-phase CsPbI2Br perovskite crystal plane, and exhibited numerous impurity peaks. In contrast, the CsPbI2Br-Tos-Arg CsPbI2Br perovskite film showed significantly higher diffraction peak intensities corresponding to the (100), (110), and (200) crystal planes of the α-phase CsPbI2Br perovskite compared to the unmodified sample, with no impurity peaks. These results indicate that the addition of Tos-Arg significantly improves the crystallinity of the CsPbI2Br perovskite film. Furthermore, no shift in diffraction peaks was observed, suggesting that the Tos-Arg additive did not alter the perovskite structure.

[0035] Figure 3This is the UV-Vis absorption spectrum of CsPbI2Br films with different concentrations of Tos-Arg added in Example 1 of the present invention within 90 minutes. Figure 3 (a) and (f) show the UV-Vis absorption spectra of CsPbI2Br perovskite films of Comparative Example 1 (without Tos-Arg) and Example 1 (CsPbI2Br-Tos-Arg), respectively. Figure 3 As can be seen, the absorbance of Comparative Example 1 sample decreased significantly in the 500-850 nm range after 10 min, with a red shift in the absorption edge. After 40 min, the absorption edge no longer matched the characteristic absorption edge of CsPbI₂Br, indicating that CsPbI₂Br decomposed. In contrast, the Tos-Arg modified sample in Example 1 maintained the characteristic absorption edge of CsPbI₂Br from 0 to 90 min. With increasing time, the absorbance of the sample in the 500-850 nm range did not decrease significantly and remained stable. The CsPbI₂Br-Tos-Arg sample, in particular, exhibited the best optical stability. This indicates that the addition of Tos-Arg effectively improved the quality of the CsPbI₂Br film, resulting in better surface coverage and crystallinity.

[0036] Figure 4 Table 1 shows the UV-Vis absorption spectra of CsPbI₂Br films modified with different concentrations of Tos-Arg in Example 1 of this invention. Table 1 shows the absorption edge and band gap values ​​corresponding to the UV-Vis absorption spectra. As can be seen from the data in Table 1, the band gap of the samples at different concentrations is within the range of 1.892 eV to 1.898 eV. Figure 4 It can be seen that as the Tos-Arg concentration increases to a5wt%, the absorption edge redshifts from 653.27nm to 655.22nm, and the light absorption performance improves accordingly. However, as the concentration further increases from a5wt% to a6wt%, the absorption edge blueshifts from 655.22nm to 654.17nm, the bandgap increases from 1.892eV to 1.895eV, and the light absorption performance decreases accordingly. Experimental results show that the sample obtained by adding Tos-Arg in Example 1, compared to Comparative Example 1, exhibits improved light absorption performance.

[0037] Table 1. Absorption edge and band gap values ​​corresponding to UV-Vis absorption spectra Figure 5 The fluorescence spectra of CsPbI₂Br films in Comparative Example 1 (without Tos-Arg) and Example 1 (with different concentrations of Tos-Arg) are shown in Figure 1. Figure 5It can be seen that the fluorescence emission intensity (PL) of the perovskite film increased compared to the CsPbI₂Br film without Tos-Arg after adding different concentrations of Tos-Arg. This indicates that the addition of appropriate concentrations of Tos-Arg can effectively reduce the defect concentration, improve the crystallinity of the perovskite film, thereby increasing the generation of photogenerated carriers and reducing their recombination efficiency. In particular, after adding 5wt% a, the CsPbI₂Br film exhibited the highest fluorescence emission peak intensity in the 640 nm-700 nm wavelength range.

[0038] Figure 6 These are Fourier transform infrared spectra of the Tos-Arg additive sample and the CsPbI2Br-Tos-Arg sample from Example 1 of this invention. Figure 6 The tensile vibration peak of C=O in the Tos-Arg carboxyl group appears at 1670 cm⁻¹. -1 At this location, the stretching vibration peak of C=O in the CsPbI2Br-Tos-Arg carboxyl group shifts to 1660 cm⁻¹. -1 The asymmetric vibration peak of the S=O group of the Tos-Arg sulfonic acid group appears at 1348 cm⁻¹. -1 The S=O asymmetric vibration peak of the sulfonic acid group in CsPbI2Br-Tos-Arg shifts to 1333 cm⁻¹. -1 The C=N and NH tensile vibration peaks in the Tos-Arg guanidine group appear at 1645 cm⁻¹. -1 3190cm -1 The C=N stretching vibration peak of the guanidinyl group in CsPbI2Br-Tos-Arg shifted to 1636 cm⁻¹. -1 At this location, the NH tensile vibration peak in CsPbI2Br-Tos-Arg shifts to 3181 cm⁻¹. -1 Experimental results show that the functional groups S=O, C=O, C=N, and NH in Tos-Arg can interact with CsPbI₂Br. This interaction between Tos-Arg and CsPbI₂Br can, on the one hand, improve the room-temperature α-phase stability of perovskite. On the other hand, it can effectively passivate perovskite defects, improve the quality of perovskite films, and suppress ion migration and non-radiative recombination.

[0039] Figure 7 These are X-ray photoelectron spectroscopy (XPS) spectra of Embodiment 1 and Comparative Example 1 of the present invention. Figure 7 (a)–(d) are the XPS spectra of unmodified CsPbI₂Br and CsPbI₂Br-Tos-Arg, respectively. Figure 7As shown in (a), the characteristic peaks of Pb4f7 / 2 and Pb4f5 / 2 in the unmodified CsPbI2Br film are located at binding energies of 140.91 eV and 145.75 eV, respectively. However, in the Tos-Arg modified sample of Example 1, the characteristic peaks of Pb4f7 / 2 and Pb4f5 / 2 shift to 139.69 eV and 145.62 eV, respectively, both moving towards lower binding energies. Furthermore, the intensity of the Pb4f characteristic peak is significantly reduced. The results indicate that Tos-Arg may bind to the uncoordinated Pb in CsPbI2Br. 2+ Coordination occurs. Figure 7 (b) shows that the characteristic peaks of Cs 3d5 / 2 and Cs 3d3 / 2 in the unmodified CsPbI2Br film are located at binding energies of 725.73 eV and 739.77 eV, respectively. After the addition of Tos-Arg, the characteristic peaks of Cs 3d5 / 2 and Cs 3d3 / 2 shift to 725.30 eV and 739.31 eV, respectively, also shifting towards lower binding energies. The results indicate that Tos-Arg may also bind with uncoordinated Cs + Coordination occurs. Combined with FTIR spectroscopy results, it can be further inferred that the O atoms in the S=O group, the O atoms in the C=O group, and the N atoms in the C=N group of the Tos-Arg molecule may participate in coordination with Cs. + / Pb 2+ The coordination process. For example... Figure 7 As shown in (c), the Br 3d characteristic peak in the unmodified CsPbI2Br film is located at 72.33 eV, while after Tos-Arg modification, it shifts to 71.94 eV, indicating a shift towards lower binding energy; Figure 7 (d) The two peaks of I 3d shifted from 618.85 eV to 620.08 eV and from 630.39 eV to 631.56 eV, respectively, towards higher binding energies. This indicates that Tos-Arg binds to Br in CsPbI2Br. - / I - Chemical bonding also exists between them. Combined with FTIR analysis results, it can be further inferred that the H atom in the N–H group of Tos-Arg interacts with the halide anion Br. - / I - Hydrogen bonds formed between them.

[0040] Figure 8 The images show CsPbI₂Br films of Comparative Example 1 (without N-p-toluenesulfonyl-L-arginine) and CsPbI₂Br films of Example 1 (with different concentrations of N-p-toluenesulfonyl-L-arginine) stored in air (25°C, 38% RH) for 0–90 min. Figure 8As can be seen, after 90 minutes of storage at an ambient temperature of 25℃ and a humidity of 38%RH, the CsPbI2Br film with N-p-toluenesulfonyl-L-arginine additive in the perovskite precursor exhibited a lower degree of fading compared to Comparative Example 1. The results indicate that the CsPbI2Br film with added N-p-toluenesulfonyl-L-arginine effectively improves air stability and room temperature black phase stability compared to the film without additive, and effectively inhibits the erosion of the perovskite film by moisture and oxygen in the air.

[0041] Figure 9 The time-resolved photoluminescence (TRPL) decay curves of CsPbI₂Br films with and without Tos-Arg are shown, and the corresponding decay kinetic parameters are listed in Table 1. From the TRPL curve fitting data in Table 2, it can be seen that the average carrier lifetime (τ) of the CsPbI₂Br film with Tos-Arg is... ave The lifetime of the photogenerated carriers was 58.18 ns, significantly longer than that of the unmodified CsPbI2Br film (46.64 ns). This result indicates that the introduction of Tos-Arg effectively passivates the defect states in the film, suppresses nonradiative recombination, and thus improves the lifetime of photogenerated carriers.

[0042] Table 2 TRPL curve fitting data To investigate the efficiency loss mechanism of perovskite solar cells under actual operating conditions, this study compared and tested the open-circuit voltage (V) of CsPbI2Br devices with and without Tos-Arg under different light intensities. oc ),like Figure 10 As shown. By analyzing V oc The relationship between light intensity and the behavior of charge recombination can be effectively evaluated by examining the behavior caused by interface defects. The results show that, compared to the unmodified control device, the device modified with Tos-Arg exhibits significantly lower Vc at all light intensities. oc Loss. V oc The relationship between V and light intensity (I) can be expressed as V oc =nkTln(I) / q, where n is the ideality factor, k is the Boltzmann constant, T is the temperature, and q is the elementary charge. Ideally, when carriers in the device only diffuse and do not recombine, n = 1; while n > 1 indicates trap-assisted nonradiative recombination. Experimentally, the n value for the unmodified device was 1.94, while the n value for the Tos-Arg-modified device decreased to 1.427. This change in n value indicates that the introduction of Tos-Arg effectively suppresses the trap-assisted recombination process. Therefore, it can be concluded that the addition of an appropriate amount of Tos-Arg can improve device performance by passivating defects and reducing nonradiative recombination losses.

[0043] Figure 11 Table 3 shows the JV curves of Example 1 and Comparative Example 1 of this invention. Table 3 displays the photovoltaic performance parameters of the CsPbI2Br perovskite solar cells of Comparative Example 1 (without N-p-toluenesulfonyl-L-arginine) and Example 1 (with different concentrations of N-p-toluenesulfonyl-L-arginine). From... Figure 11 As shown in Table 3, the CsPbI₂Br device with Tos-Arg added has a higher V0 compared to the pure CsPbI₂Br device. oc It can be increased from 0.83 V to 1.01 V, J sc From 15.49 mA / cm 2 It can be increased to 19.84 mA / cm² 2 The FF can be increased from 0.46 to 0.59, and the PCE can be significantly improved from 9.60% to 12.15%. The above experimental results show that adding Tos-Arg to CsPbI2Br perovskite solar cells can improve photovoltaic performance.

[0044] Table 3 Photovoltaic performance parameters of perovskite solar cells Figure 12 Electrochemical impedance spectroscopy (EIS) was used to investigate the effect of Tos-Arg additive on charge transport and recombination processes in CsPbI2Br perovskite solar cells. The fitted parameters are shown in Table 4. The results indicate that the charge transport impedance (Ro) of the device with Tos-Arg additive significantly increases. trans The charge transport impedance (R) is 369.1 Ω, significantly lower than that of the unmodified control group (503.2 Ω). The lower R... trans The value typically reflects more efficient charge transport and better conductivity, thereby increasing the short-circuit current density of the device (J). sc ).

[0045] Table 4 EIS plot fitting parameters Figure 13 The incident monochromatic light-electron conversion efficiency (IPCE) spectra of CsPbI2Br perovskite solar cells with and without Tos-Arg are presented. The results show that the IPCE peak of the unmodified device is only 77.96%, with an integrated current density of 15.26 mA / cm². 2 The short-circuit current density obtained from the JV test (Jsc = 15.49 mA / cm²) is compared with that obtained from the JV test. 2The results were consistent; however, the Tos-Arg modified device showed an increased IPCE peak of 81.8% and a corresponding increase in integrated current density to 19.46 mA / cm². 2 The integrated current result is compared with the short-circuit current density obtained from the JV test (J sc =19.84 mA / cm 2 The results are consistent. The experimental data above show that the introduction of an appropriate amount of Tos-Arg effectively improves the photocurrent response of CsPbI2Br perovskite solar cells across the entire spectral range, enhances the quantum conversion efficiency of the device, and thus improves the overall photovoltaic performance of the device.

[0046] Figure 14 Ultraviolet photoelectron spectroscopy (UPS) was performed on CsPbI2Br films with and without Tos-Arg, and the results were obtained. Figure 14 (a) Cutoff edge (E) cutoff )and Figure 14 (b) starting edge (E) onset The results and band structure parameters are shown in Table 5. Furthermore, the corresponding energy level diagram is plotted in 14(c), which more intuitively demonstrates the effect of Tos-Arg addition on the energy levels of the CsPbI2Br perovskite material. The ET of the thin film was analyzed. cutoff Maximum valence band energy (E) VBM ) and E onset Using formula E VBM = 21.22 - (E) cutoff - E onset Calculate the Eo of pure CsPbI2Br and CsPbI2Br with Tos-Arg added. CBM E VBM Value. Using E VBM and E CBM These values ​​were used to plot the energy levels of the PSCs (see Figure 14(c)). From Figure 14 As can be seen in (c), when Tos-Arg is added, the CsPbI2Br film clearly exhibits E VBM The upward shift results in a 0.34 eV reduction in the energy level difference between the perovskite layer and the HTL. This favorable energy level transfer indicates that the addition of Tos-Arg can modulate the energy level mismatch between the perovskite layer and the HTL, thereby promoting the transport and extraction of photogenerated holes and improving device performance.

[0047] Table 5 Energy level parameters of perovskite solar cells Figure 15The power conversion efficiency (PCE) stability test results of CsPbI₂Br solar cells with different concentrations of Tos-Arg are shown. Figure 15 As shown, the introduction of Tos-Arg significantly improved the air stability of the device. Specifically, after 360 hours of storage in air at 23°C and 11.2% relative humidity, the CsPbI2Br solar cell without Tos-Arg completely decomposed, while the CsPbI2Br solar cell with Tos-Arg showed significantly improved air stability. In particular, the CsPbI2Br solar cell corresponding to the CsPbI2Br-Tos-Arg sample still maintained approximately 50% of its initial PCE after 792 hours of storage. This enhanced air stability can be attributed to the interaction between the S=O, C=O, and C=N functional groups in Tos-Arg and the Pb in CsPbI2Br. 2 + / Cs + The coordination between ions, and the interaction between its N-H groups and the Br in perovskite. - / I - Hydrogen bonding between the ions effectively inhibits the migration of halide ions, enhances the structural stability of perovskite materials, and thus significantly improves the long-term stability and reliability of devices.

[0048] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. 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 still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A perovskite thin film modified with N-p-toluenesulfonyl-L-arginine, characterized in that it is N-p-toluenesulfonyl-L-arginine was added to a CsPbI2Br perovskite precursor solution, and CsPbI2Br perovskite films were grown by staged spin coating and gradient annealing.

2. The method for preparing perovskite thin films based on N-p-toluenesulfonyl-L-arginine modification as described in claim 1, characterized in that, Includes the following steps: S1. N-p-toluenesulfonyl-L-arginine was added to a CsPbI2Br perovskite precursor solution and completely dissolved to obtain a mixture. S2 uses FTO conductive glass covered with a planar SnO2 / SnCl2 thin film as a substrate. The mixture obtained in S1 is spin-coated onto the substrate in stages, and then CsPbI2Br perovskite thin film is grown by gradient annealing.

3. The method for preparing perovskite thin films based on N-p-toluenesulfonyl-L-arginine modification according to claim 2, characterized in that: The mass percentage concentration of N-p-toluenesulfonyl-L-arginine in the S1 mixture is 2wt%~8wt%.

4. The method for preparing perovskite thin films based on N-p-toluenesulfonyl-L-arginine modification according to claim 1, characterized in that: The dissolution described in S1 is carried out under constant temperature heating and stirring conditions, and after dissolution is completed, it is filtered with a polytetrafluoroethylene filter.

5. The method for preparing perovskite thin films based on N-p-toluenesulfonyl-L-arginine modification according to claim 3, characterized in that: The constant temperature heating described in S1 is 80℃~120℃, and the stirring time for dissolution is 0.5~5h.

6. The method for preparing perovskite thin films based on N-p-toluenesulfonyl-L-arginine modification according to claim 1, characterized in that: The amount of the spin-coated perovskite precursor mixture used in the S2 stage is 100µL~150µL.

7. The method for preparing perovskite thin films based on N-p-toluenesulfonyl-L-arginine modification according to claim 1, characterized in that: The S2 spin coating process includes a first-stage spin coating and a second-stage spin coating. The spin coating speed for the first stage is 500–900 rpm, and the spin coating time for the first stage is 10–16 s. The spin coating speed for the second stage is 800–1400 rpm, and the spin coating time for the second stage is 80–140 s.

8. The method for preparing perovskite thin films based on N-p-toluenesulfonyl-L-arginine modification according to claim 1, characterized in that: In S2, gradient annealing involves first annealing at 50-90℃ for 2-8 minutes, and then annealing at 105-155℃ for 1-6 minutes.

9. A perovskite solar cell, characterized in that, Contains the perovskite thin film as described in claim 1.

10. The perovskite solar cell according to claim 9, characterized in that, A hole transport layer and an electrode are sequentially disposed on the perovskite thin film.

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