An all-inorganic perovskite solar cell based on the interfacial modification of 2-amino-5-bromoacetophenone and its preparation method

Abstract

The present invention discloses an all-inorganic perovskite solar cell based on the interfacial modification of 2-amino-5-bromoacetophenone and its preparation method. The all-inorganic perovskite cell includes an anode substrate, an electron transport layer and a modification layer, a perovskite light-absorbing layer, an interfacial modification layer, a hole transport layer and a cathode layer. The perovskite light-absorbing layer is CsPbI2Br, the interfacial modification layer is 2-amino-5-bromoacetophenone, and the hole transport layer is Spiro-OMeTAD. The present invention uses 2-amino-5-bromoacetophenone to modify the interface between the CsPbI2Br perovskite light-absorbing layer and the Spiro-OMeTAD hole transport layer to reduce the infiltration of moisture and the degradation of perovskite, improve the morphology of the CsPbI2Br perovskite thin film, enhance the black-phase stability of the CsPbI2Br perovskite thin film at room temperature, passivate interface defects, inhibit interface non-radiative recombination losses, and improve the device performance of perovskite solar cells. At the same time, the method of the present invention is simple and easy to implement, has a low cost, is suitable for large-scale preparation, and has important research and application values.

Description

Technical Field

[0001] The present invention belongs to the technical field of the preparation of solar cells, and relates to a fully inorganic perovskite solar cell and a preparation method thereof, in particular to a fully inorganic perovskite solar cell based on the interfacial modification of 2-amino-5-bromoacetophenone and a preparation method thereof. Background Art

[0002] The development history of fully inorganic perovskite solar cells can be traced back to 2012 at the earliest. Chen et al. first reported an inorganic perovskite solar cell based on CsSnI 3 , and the measured power conversion efficiency (PCE) was 0.9%. With the development of the efficiency of CsSnI 3 -based cells being hindered, this component was gradually replaced by CsPbX 3 (X = I, Br, Cl) materials. In 2023, the research team of Professor Liu Shengzhong found that -SH in (3-mercaptopropyl)trimethoxysilane (MPTS) can strongly interact with undercoordinated Pb 2+ on the perovskite surface, effectively reducing interfacial charge recombination. Therefore, under 100 mW cm -2 illumination, after surface treatment with MPTS, the power conversion efficiency of inverted inorganic CsPbI 3-x Br x PSCs was significantly improved, from 19.0% to 21.0%. CsPbI 2 Br perovskite solar cells are considered to be a new generation of photovoltaic devices with great potential due to their excellent thermal stability and appropriate trade-off between light absorption and phase stability, and have become an ideal choice for fully inorganic perovskite solar cells. However, the fully inorganic CsPbI 2 Br perovskite solar cell has the problem of interfacial non-radiative recombination (NRR) loss, which leads to the attenuation of the stability and efficiency of the battery, restricting its industrial application.

[0003] Interfacial defects are an important source of interfacial non-radiative recombination, increasing the possibility of water intrusion into layer-by-layer prepared CsPbI 2 Br PSCs. At the interface where the electron transport layer (ETL) or hole transport layer (HTL) contacts the perovskite, problems such as band bending, carrier recombination, charge accumulation, and ion migration are also likely to occur, resulting in serious interfacial non-radiative recombination losses, reducing the open-circuit voltage of fully inorganic perovskite solar cells, and leading to a decrease in the performance of fully inorganic perovskite solar cells. Therefore, the present invention provides a fully inorganic perovskite solar cell based on the interfacial modification of 2-amino-5-bromoacetophenone and a preparation method thereof, using 2-amino-5-bromoacetophenone to modify CsPbI 2The interface between the Br perovskite light-absorbing layer and the Spiro-OMeTAD hole transport layer to reduce moisture infiltration and perovskite degradation, and improve CsPbI 2 the morphology of the Br perovskite film, and enhance CsPbI 2 the black-phase stability of the Br perovskite film at room temperature, passivate interface defects, inhibit interface non-radiative recombination losses, and improve the performance of perovskite solar cells. Summary of the Invention

[0004] To solve the above problems, the present invention provides a fully inorganic perovskite solar cell based on 2-amino-5-bromoacetophenone interface modification and a preparation method thereof.

[0005] The technical solution adopted by the present invention is as follows:

[0006] A fully inorganic perovskite solar cell based on 2-amino-5-bromoacetophenone interface modification, including an anode substrate, an electron transport layer and a modification layer, a perovskite light-absorbing layer, an interface modification layer, a hole transport layer and a cathode layer. The perovskite light-absorbing layer is CsPbI 2 Br, the interface modification layer is 2-amino-5-bromoacetophenone (hereinafter referred to as 2A5B), and the hole transport layer is Spiro-OMeTAD.

[0007] Further, the anode substrate is conductive glass FTO, and the electron transport layer and the modification layer are SnO 2 / SnCl 2 film, that is, between the electron transport layer SnO 2 film and the perovskite light-absorbing layer is modified by SnCl 2 film, and the cathode layer is Au.

[0008] The preparation method of the above-mentioned fully inorganic perovskite solar cell based on 2-amino-5-bromoacetophenone interface modification includes the following steps: After the anode substrate is surface-treated, the electron transport layer and the modification layer, the perovskite light-absorbing layer, the interface modification layer and the hole transport layer are sequentially spin-coated, and then the cathode layer is prepared to obtain a fully inorganic perovskite solar cell with 2-amino-5-bromoacetophenone interface modification.

[0009] Further, the surface treatment step of the anode substrate is: ultrasonically clean with acetone, absolute ethanol, and deionized water for at least 30 minutes in sequence, then vacuum dry, and then use ultraviolet ozone to clean for at least 30 minutes. Preferably, the specification of the anode substrate conductive glass FTO is 20mm*25mm, the sheet resistance is 14Ω, and the light transmittance ≥90%.

[0010] Further, the preparation steps of the electron transport layer and the modification layer are:

[0011] Dissolve SnO2 The hydrocolloid dispersion is mixed with deionized water in a certain volume ratio and stirred evenly, and then filtered to obtain a SnO 2 precursor solution; The SnO 2 precursor solution is spin-coated on the anode substrate and annealed;

[0012] Dissolve SnCl 2 in absolute ethanol to obtain a SnCl 2 / absolute ethanol solution. Spin-coat the SnCl 2 / absolute ethanol solution on the annealed SnO 2 film, and then perform gradient annealing, and then use ultraviolet ozone to clean for at least 30 min to obtain an electron transport layer and a modification layer, denoted as FTO / SnO 2 / SnCl 2 film. The FTO / SnO 2 / SnCl 2 film is a planar structure, with good chemical stability and electrical properties, and can provide a uniform and flat surface for the deposition of the CsPbI 2 Br perovskite film.

[0013] Furthermore, the volume ratio of the SnO 2 hydrocolloid dispersion to deionized water is 1:2 to 1:4; the spin-coating speed of the SnO 2 precursor solution is 2000 to 4000 rpm, and the spin-coating time is 15 s to 60 s; the annealing temperature is 70 to 200 °C, and the annealing time is 10 to 90 min; the concentration of the SnCl 2 / absolute ethanol solution is 0.005 to 0.014 mol / L, the spin-coating speed is 2500 to 4500 rpm, and the spin-coating time is 25 to 45 s; the first-step annealing temperature of the gradient annealing is 70 to 120 °C, and the time is 6 to 15 min; the second-step annealing temperature is 140 to 200 °C, and the time is 30 to 90 min.

[0014] Furthermore, the preparation steps of the perovskite light-absorbing layer are as follows:

[0015] Spin-coat the CsPbI 2 Br precursor solution on the electron transport layer and the modification layer. The spin-coating is divided into two stages. The spin-coating speed in the first stage is 700 to 1200 rpm, and the spin-coating time is 6 to 15 seconds; the spin-coating speed in the second stage is 1000 to 2000 rpm, and the spin-coating time is 90 to 150 seconds; then anneal at a temperature of 70 to 100 °C for 2 to 6 minutes, and then anneal at a temperature of 130 to 160 °C for 1 to 6 minutes to obtain a CsPbI 2 Br perovskite film, that is, the perovskite light-absorbing layer, denoted as FTO / SnO 2 / SnCl 2 / CsPbI 2 Br thin film. By means of spin coating in stages and temperature gradient annealing, it helps to improve the quality of the CsPbI 2 Br perovskite thin film, improve the film coverage, crystallinity, grain size and distribution uniformity, and reduce the defect density.

[0016] Furthermore, the preparation steps of the interface modification layer are as follows:

[0017] Dissolve 2-amino-5-bromoacetophenone in isopropanol to obtain a 2-amino-5-bromoacetophenone / isopropanol solution. Spin coat the 2-amino-5-bromoacetophenone / isopropanol solution on the perovskite light-absorbing layer and perform annealing treatment to obtain the interface modification layer, denoted as FTO / SnO 2 / SnCl 2 / CsPbI 2 Br / 2A5B thin film. Interface modification of the CsPbI 2 Br perovskite thin film with 2-amino-5-bromoacetophenone can increase the grain size and crystallinity of the perovskite, enhance the film stability, and improve the optoelectronic properties of the film. Specifically, the interaction between the interface modifier 2A5B and the CsPbI 2 Br perovskite thin film can effectively control the growth rate and crystal structure of the perovskite grains, thereby improving the quality and performance of the film.

[0018] Furthermore, the concentration of the 2-amino-5-bromoacetophenone / isopropanol solution is 1 mg / mL to 5 mg / mL, the spin coating speed is 2500 to 4500 rpm, and the spin coating time is 20 to 50 seconds; the annealing temperature is 70 to 100 °C, and the annealing time is 1 to 3 minutes. When performing interface modification, it is necessary to pay attention to the control of the spin coating amount (volume) of the modifier. Too small a spin coating amount (volume) will result in many grain boundary defects, a rough and uneven surface, and poor crystallinity of the film; too large a spin coating amount will cause blurred grain boundaries and smaller grain sizes in the film, thus affecting the optical properties of the film. Only when an appropriate amount of 2-amino-5-bromoacetophenone is spin coated can a CsPbI 2 Br perovskite thin film with the best performance be obtained. This thin film has the characteristics of larger grain size, fewer grain boundary defects, smooth, dense and high crystallinity, and at the same time has the best room temperature phase stability, optical stability and optical properties. Therefore, when preparing all-inorganic perovskite solar cells, spin coating an appropriate amount of 2-amino-5-bromoacetophenone for interface modification can improve the room temperature phase stability of the film, thereby improving the performance of all-inorganic perovskite solar cells. The present invention provides a feasible approach for the preparation of high-performance all-inorganic perovskite solar cells, which is of great significance for the research and application of optoelectronic devices.

[0019] Furthermore, the preparation steps of the hole transport layer and the cathode layer are as follows:

[0020] Spin-coat the Spiro-OMeTAD solution on the interface modification layer at a spin-coating speed of 2500 - 4500 rpm for 20 - 40 seconds to obtain the hole transport layer; evaporate Au on the hole transport layer for 3 - 6 min with a vacuum degree of 1×10 -4 Pa - 9×10 -4 Pa.

[0021] The beneficial effects of the present invention are as follows:

[0022] The present invention uses 2-amino-5-bromoacetophenone to modify the interface between the CsPbI 2 Br perovskite light-absorbing layer and the Spiro-OMeTAD hole transport layer. The O atom in C=O of 2A5B and the N atom in the -NH 2 group will form coordination bonds with the uncoordinated Pb 2 on the surface of CsPbI 2+ / Cs + to passivate defects and inhibit non-radiative recombination at the interface; the H atom in the -NH 2 group has a hydrogen bond interaction with the free I 2 / Br - ions on the surface of CsPbI - Br to inhibit the migration of halides and stabilize the perovskite structure; the 2A5B interface modification helps to form a dipole interlayer between the CsPbI 2 Br perovskite light-absorbing layer and the hole transport layer, improve the interface energy level matching, enhance the built-in electric field, thereby promoting the transport and collection of charges, and improving the performance of the all-inorganic perovskite solar cell. By introducing the 2A5B interface modification layer, the present invention can reduce the infiltration of moisture and the degradation of perovskite, improve the morphology of the CsPbI 2 Br perovskite thin film, enhance the black-phase stability of the CsPbI 2 Br perovskite thin film at room temperature, passivate interface defects, inhibit non-radiative recombination loss at the interface, and further improve the performance of the perovskite solar cell. At the same time, the method of the present invention is simple and easy to implement, with low cost, suitable for large-scale preparation, and has important research and application value. Description of the Drawings

[0023] Figure 1 FESEM images of FTO / SnO 2 / SnCl 2 / CsPbI 2 Br / 2A5B thin films modified with different mass concentrations of 2A5B in the embodiments of the present invention: (a) 0 mg / mL; (b) a 1mg / mL; (c) a 2 mg / mL; (d) a 3 mg / mL; (e) a 4 mg / mL; (f) a 5 mg / mL.

[0024] Figure 2 X-ray diffraction patterns of FTO / SnO 2 / SnCl 2 / CsPbI 2 Br / 2A5B thin films with different mass concentrations of 2A5B modification in the examples of the present invention.

[0025] Figure 3 UV-visible absorption spectra of FTO / SnO 2 / SnCl 2 / CsPbI 2 Br / 2A5B thin films with different mass concentrations of 2A5B modification in the examples of the present invention.

[0026] Figure 4 UV-visible absorption spectra of FTO / SnO 2 / SnCl 2 / CsPbI 2 Br / 2A5B thin films stored for 0 - 90 min: (a) 0 mg / mL; (b) a 1 mg / mL; (c) a 2 mg / mL; (d) a 3 mg / mL; (e) a 4 mg / mL; (f) a 5 mg / mL.

[0027] Figure 5 Optical photos of FTO / SnO 2 / SnCl 2 / CsPbI 2 Br / 2A5B thin films stored for 0 - 90 min in the examples of the present invention.

[0028] Figure 6 (a) Water contact angles of unmodified FTO / SnO 2 / SnCl 2 / CsPbI 2 Br thin films; (b) Water contact angles of 2A5B-modified FTO / SnO 2 / SnCl 2 / CsPbI 2 Br / 2A5B thin films in the examples of the present invention.

[0029] Figure 7 In the embodiments of the present invention, (a) PL spectra of FTO / SnO 2 / SnCl 2 / CsPbI 2 Br / 2A5B thin films modified with different mass concentrations of 2A5B; (b) TRPL spectra of unmodified and 2A5B-modified FTO / SnO 2 / SnCl 2 / CsPbI 2 Br / 2A5B thin films.

[0030] Figure 8 In the embodiments of the present invention, (a) Fourier transform infrared spectra of 2A5B and CsPbI 2 Br / 2A5B; X-ray photoelectron spectra of CsPbI 2 Br and CsPbI 2 Br / 2A5B thin films; (b) Pb 4f; (c) Cs 3d; (d) I 3d; (e) Br 3d.

[0031] Figure 9 In the embodiments of the present invention, a schematic diagram of the bonding model of 2A5B and CsPbI 2 Br.

[0032] Figure 10 In the embodiments of the present invention, J-V curves of all-inorganic perovskite solar cells modified with different mass concentrations of 2A5B.

[0033] Figure 11 In the embodiments of the present invention, PCE stability of all-inorganic perovskite solar cells modified with different mass concentrations of 2A5B. Detailed implementation manners

[0034] The technical solutions of the present invention will be further clearly and detailedly described below in conjunction with the accompanying drawings and specific embodiments.

[0035] Example 1

[0036] (1) Select a conductive glass FTO with a specification of 20mm*25mm, a sheet resistance of 14Ω, and a light transmittance ≥90% as the anode substrate. Ultrasonically treat the FTO conductive glass with acetone, absolute ethanol, and deionized water for 30 minutes respectively, dry it in a vacuum drying oven at 60°C for 1h, and then treat it in an ultraviolet ozone cleaning machine for 30 minutes.

[0037] (2) Mix a SnO 2 hydrosol dispersion liquid and deionized water in a volume ratio of 1:2 and stir evenly. Filter it using a polytetrafluoroethylene filter head to obtain SnO 2Precursor solution. 120 μL of SnO 2 The precursor solution was spin-coated onto the anode substrate at a rotational speed of 3000 rpm for 30 seconds, and then placed on a constant-temperature heating stage and annealed at 140 °C for 15 minutes, denoted as FTO / SnO 2 film.

[0038] SnCl 2 was dissolved in absolute ethanol to prepare a SnCl 2 / absolute ethanol solution with a concentration of 0.008 mol / L. 120 μL of the 0.008 mol / L SnCl 2 / absolute ethanol solution was spin-coated onto the FTO / SnO 2 film at a spin-coating speed of 3000 rpm for 30 s, and gradient annealing was carried out. The first step of the gradient annealing had an annealing temperature of 80 °C and an annealing time of 12 min; the second step had an annealing temperature of 180 °C and an annealing time of 80 min, and then it was treated in an ultraviolet ozone cleaner for 30 minutes to obtain the FTO / SnO 2 / SnCl 2 film.

[0039] (3) CsI, PbI 2 , PbBr 2 were dissolved in DMSO and heated with stirring at a constant temperature of 110 °C for 2 h to prepare a CsPbI 2 Br precursor solution with a concentration of 1 mol / L. 120 μL of the CsPbI 2 Br precursor solution was spin-coated onto the FTO / SnO 2 / SnCl 2 film. The spin-coating was divided into two stages: the first stage had a spin-coating speed of 900 rpm and a spin-coating time of 12 s; the second stage had a spin-coating speed of 1600 rpm and a spin-coating time of 100 s. Then, it was treated by the method of temperature gradient annealing, annealed at 70 °C for 5 min, and then annealed at 150 °C for 3 min to obtain the perovskite light-absorbing layer, denoted as FTO / SnO 2 / SnCl 2 / CsPbI 2 Br film.

[0040] (4) 2-Amino-5-bromoacetophenone was dissolved in isopropanol to prepare a i (i = 1 - 5, 1 ≤ a 1 < a 2 < a 3 < a 4 < a 52-Amino-5-bromoacetophenone / isopropanol solution with a concentration of 5 mg / mL. Take 120 μL of the 2-amino-5-bromoacetophenone / isopropanol solution and spin-coat it on the perovskite light-absorbing layer at a spin-coating speed of 3000 rpm for 30 seconds. Then anneal it at 80 °C for 3 minutes to obtain an interfacial modification layer, denoted as FTO / SnO 2 / SnCl 2 / CsPbI 2 Br / 2A5B thin film.

[0041] (5) Take 40 μL of Spiro-OMeTAD solution and spin-coat it on the interfacial modification layer at a spin-coating speed of 3000 rpm for 30 seconds to obtain a hole transport layer, denoted as FTO / SnO 2 / SnCl 2 / CsPbI 2 Br / 2A5B / Spiro-OMeTAD thin film.

[0042] (6) Evaporate Au on the hole transport layer for 5 minutes with a vacuum degree of 5×10 -4 PaPa to obtain a fully inorganic perovskite solar cell based on 2-amino-5-bromoacetophenone interfacial modification.

[0043] Figure 1 Shows the FESEM images of FTO / SnO 2 / SnCl 2 / CsPbI 2 Br / 2A5B thin films modified with different mass concentrations of 2A5B. The results show that the surface grain boundaries of CsPbI 2 Br perovskite without 2A5B modification are blurred, there are many defects, the crystallinity is poor, and the grain size is small; as the concentration of the 2A5B modifier increases continuously, the film morphology gradually becomes dense and flat, and the grain boundaries gradually become clear; while as the concentration of the 2A5B modifier further increases to 5 mg / mL, the grain boundaries gradually become blurred again, and the grain size also decreases. This indicates that appropriate 2A5B modification is beneficial to improving the quality of CsPbI 2 Br perovskite thin films.

[0044] Figure 2 Shows the X-ray diffraction patterns of FTO / SnO 2 / SnCl 2 / CsPbI 2 Br / 2A5B thin films modified with different concentrations of 2A5B. It can be seen from Figure 2 that the unmodified CsPbI 2The diffraction peak intensities of the Br thin film corresponding to the (100), (110), and (200) crystal planes of the α-phase are relatively low. As the concentration of 2A5B increases continuously, the intensities of these diffraction peaks increase significantly, and the enhancement of the (100) crystal plane is the most prominent.

[0045] Figure 3 Shows the ultraviolet-visible absorption spectra of FTO / SnO 2 / SnCl 2 / CsPbI 2 Br / 2A5B thin films. The results show that the band gap values of the samples at different modifier concentrations are between 1.8899 eV and 1.8982 eV. From Figure 3 It can be seen that when the concentration of 2A5B increases continuously from 0 mg / mL, the absorption edge redshifts from 653.24 nm to 656.13 nm, and the band gap decreases from 1.8982 eV to 1.8899 eV. In the wavelength range of 600 nm to 700 nm, the absorbance gradually increases, indicating enhanced light absorption performance. However, when the concentration of 2A5B increases to 5 mg / mL, the absorption edge blueshifts from 656.13 nm to 654.67 nm, the band gap increases to 1.8941 eV, and in the wavelength range of 600 nm to 700 nm, the absorbance gradually decreases. These experimental results are consistent with the XRD and SEM results, indicating that the modification with an appropriate concentration of 2A5B improves the crystallinity, reduces the defect density, and enhances the light absorption performance of the material.

[0046] Figure 4 Shows the ultraviolet-visible absorption spectra of FTO / SnO 2 / SnCl 2 / CsPbI 2 Br / 2A5B thin films stored for 0 - 90 min, Figure 5 Shows the optical photographs of FTO / SnO 2 / SnCl 2 / CsPbI 2 Br / 2A5B thin films stored for 0 - 90 min. The results show that within 0 - 90 min, compared with the pure CsPbI 2 Br perovskite film (see attachment Figure 4 (a)), the decrease in absorbance of the absorption curve of the 2A5B-modified CsPbI 2 Br perovskite film in the wavelength range of 600 nm - 700 nm can be ignored (see attachment Figure 4 (e)). At the same time, the 2A5B-modified CsPbI 2 Br perovskite film maintains the darkest tone within 0 - 90 minutes, while the pure CsPbI 2The photoactivity of the black phase of the Br perovskite film disappears very quickly. This confirms that the CsPbI 2 perovskite film modified with a proper concentration of 2A5B has good optical stability and black-phase stability.

[0047] Figure 6 Shows the water contact angles of (a) the unmodified CsPbI 2 Br film; (b) the 2A5B-modified FTO / SnO 2 / SnCl 2 / CsPbI 2 Br / 2A5B film. The results show that after 2A5B modification, the water contact angle of the perovskite film increases from 55.2° to 61.4°. This is due to the hydrophobicity of the benzene ring and bromine substituents, which can prevent the entry and diffusion of water and effectively improve the moisture resistance of the all-inorganic perovskite.

[0048] Figure 7 Shows the PL spectra of (a) the FTO / SnO 2 / SnCl 2 / CsPbI 2 Br / 2A5B film modified with different concentrations of 2A5B; (b) the TRPL spectra of the unmodified and 2A5B-modified FTO / SnO 2 / SnCl 2 / CsPbI 2 Br / 2A5B perovskite film. As can be seen from Figure 7 (a), the emission peak positions of all samples are around 660 nm. Compared with pure CsPbI 2 Br, the emission peak position of the 2A5B-modified sample has a certain red shift. Combining with the analysis results of the UV-visible absorption spectrum, this can be attributed to the narrowing of the band gap of the perovskite film caused by 2A5B modification. Figure 7 (b) is the time-resolved photoluminescence (TRPL) spectra of the unmodified and 2A5B-modified CsPbI 2 Br films. It can be seen that the average carrier lifetime τ 2 of the 2A5B-modified CsPbI ave (0.86 ns) is longer than the average carrier lifetime τ 2 of the pure CsPbI ave (0.77 ns) film. This indicates that 2A5B modification inhibits the non-radiative recombination caused by defects, and the carrier recombination probability is lower, which is crucial for improving the photovoltaic conversion efficiency.

[0049] Figure 8 Shows the Fourier transform infrared spectra of (a) 2A5B and CsPbI 2 Br / 2A5B; CsPbI2 Br and CsPbI 2 X-ray photoelectron spectroscopy of Br / 2A5B thin films; (b) Pb 4f; (c) Cs 3d; (d) I 3d; (e) Br 3d.

[0050] Figure 9 Shows the bonding model diagram of 2A5B and CsPbI 2 Br. According to the analysis results of FTIR spectra and XPS spectra, we can conclude that 2A5B and CsPbI 2 Br bonding mechanism diagram. From Figure 9 It can be seen that Pb 2+ / Cs + ions form coordination bonds with the O atoms on the C=O group and the N atoms in the -NH 2 group in 2A5B respectively, passivate interface defects, and inhibit interface non-radiative recombination. In addition, the H atoms in the -NH 2 group in 2A5B can interact with I 2 in the all-inorganic CsPbI - / Br - ions in the perovskite through hydrogen bonds, inhibit the migration of halide ions, and stabilize the perovskite structure. The synergistic effect of coordination bonds and hydrogen bonds passivates the surface defects of the perovskite thin film, improves the quality of the perovskite thin film, and enhances the stability of the perovskite structure. In addition, the π-conjugated structure of the benzene ring and the electric dipole moment of the bromine substituent in 2A5B can also promote the charge transport in the device.

[0051] Figure 10 Shows the J-V curves of all-inorganic perovskite solar cells modified with different mass concentrations of 2A5B. It can be seen that the interface modification of 2A5B significantly improves the V OC , J SC , FF of all-inorganic perovskite cells, and finally improves the PCE; when the concentration of 2A5B increases continuously from 0 mg / mL, the open-circuit voltage (V OC ) increases from 1.04 V to 1.18 V; the short-circuit current density (J SC ) increases from 16.20 mA / cm 2 to 17.70 mA / cm 2 ; the fill factor (FF) increases from 0.50 to 0.61, and the PCE increases from 8.36% to 12.63%. As the concentration of 2A5B increases to 5 mg / mL, although V OC increases from 1.18 V to 1.23 V; but J SC decreases from 17.70 mA / cm 2 to 16.06 mA / cm 2; FF decreased from 0.61 to 0.60, and PCE decreased from 12.63% to 11.75%. The results indicate that CsPbI 2 Br PSCs with appropriate concentrations of 2A5B modification have better photovoltaic performance.

[0052] Figure 11 The PCE stability of all-inorganic perovskite solar cells modified with different mass concentrations of 2A5B was demonstrated. The results show that the air stability of all-inorganic perovskite solar cells has been significantly improved after 2A5B modification. When the concentration of the modifier increases continuously from 0 mg / mL, the stability of all-inorganic perovskite cells gradually increases. However, when the concentration of the modifier continues to increase to 5 mg / mL, the stability of all-inorganic perovskite cells decreases again. Among them, the CsPbI 4 Br all-inorganic perovskite solar cells modified with a concentration of a 2 mg / mL of 2A5B have the best stability, maintaining about 70% of the initial efficiency after 40 days, while the unmodified PSCs only retain 20% of the initial efficiency.

[0053] In summary, the present invention successfully improves the performance of all-inorganic perovskite cells by introducing a 2A5B interfacial modifier between the CsPbI 2 Br perovskite light-absorbing layer and the hole transport layer interface. This method provides a new approach for the preparation of highly efficient and stable all-inorganic CsPbI 2 Br perovskite solar cells, promotes the commercialization process of all-inorganic perovskite solar cells, and has important application potential and research value.

[0054] Example 2

[0055] (1) Select a conductive glass FTO with a specification of 20mm * 25mm, a sheet resistance of 14Ω, and a light transmittance ≥ 90% as the anode substrate. Ultrasonically treat the FTO conductive glass with acetone, absolute ethanol, and deionized water for 30 minutes respectively, dry it in a vacuum drying oven at 60°C for 1h, and then treat it in an ultraviolet ozone cleaning machine for 30 minutes.

[0056] (2) Mix the SnO 2 hydrocolloid dispersion and deionized water in a volume ratio of 1:3 and stir evenly. Filter it using a polytetrafluoroethylene filter head to obtain the SnO 2 precursor solution. Spin-coat 130 μL of the SnO 2 precursor solution onto the anode substrate at a rotation speed of 3000 rpm for 30 seconds, and then place it on a constant temperature heating table and anneal it at 150°C for 14 minutes to obtain the FTO / SnO 2 film.

[0057] Mix SnCl2 Dissolve it in absolute ethanol to prepare a SnCl solution with a concentration of 0.01 mol / L 2 / absolute ethanol solution. Take 130 μL of 0.01 mol / L SnCl 2 / absolute ethanol solution and spin-coat it onto the FTO / SnO 2 film. The spin-coating speed is 3500 rpm and the spin-coating time is 35 s. Perform gradient annealing. The first annealing temperature for gradient annealing is 90 °C and the annealing time is 10 min; the second annealing temperature is 190 °C and the annealing time is 80 min. Then, treat it in an ultraviolet ozone cleaner for 30 minutes to obtain FTO / SnO 2 / SnCl 2 film.

[0058] (3) Dissolve an appropriate amount of CsI, PbI 2 , PbBr 2 in DMSO and heat and stir at a constant temperature of 100 °C for 2 h to prepare a CsPbI 2 Br precursor solution with a concentration of 1.3 mol / L. Take 130 μL of the CsPbI 2 Br precursor solution and spin-coat it onto the FTO / SnO 2 / SnCl 2 film. The spin-coating is divided into two stages: the spin-coating speed in the first stage is 1000 rpm and the spin-coating time is 10 s; the spin-coating speed in the second stage is 1400 rpm and the spin-coating time is 110 s. Then, perform treatment by the method of temperature gradient annealing, anneal at 80 °C for 4 min, and then anneal at 150 °C for 3 min to obtain a perovskite light-absorbing layer, denoted as FTO / SnO 2 / SnCl 2 / CsPbI 2 Br film.

[0059] (4) Dissolve 2-amino-5-bromoacetophenone in isopropanol to prepare a 2-amino-5-bromoacetophenone / isopropanol solution with a concentration of 2 mg / mL. Take 130 μL of the 2A5B / isopropanol solution with a concentration of 2 mg / mL and spin-coat it on the perovskite light-absorbing layer. The spin-coating speed is 3000 rpm and the time is 30 s. Then, anneal at 80 °C for 3 min to obtain an interfacial modification layer, denoted as FTO / SnO 2 / SnCl 2 / CsPbI 2 Br / 2A5B film.

[0060] (5) Take 50 μL of the Spiro-OMeTAD solution and spin-coat it on the interfacial modification layer. The spin-coating speed is 3500 rpm and the time is 30 s to obtain a hole transport layer, denoted as FTO / SnO 2 / SnCl 2 / CsPbI 2 Br / 2A5B / Spiro-OMeTAD thin film.

[0061] (6) Evaporate Au on the hole transport layer for 5 min with a vacuum degree of 5×10 -4 PaPa to obtain a fully inorganic perovskite solar cell with 2-amino-5-bromoacetophenone interface modification.

[0062] The above are only the preferred embodiments of the present invention. Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make many possible changes and modifications to the technical solution of the present invention, or modify it into an equivalent embodiment with equivalent changes, without departing from the scope of the technical solution of the present invention. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the protection of the technical solution of the present invention.

Claims

1. An all-inorganic perovskite solar cell based on 2-amino-5-bromoacetophenone interface modification, characterized in that: It includes an anode substrate, an electron transport layer and a modification layer, a perovskite light absorbing layer, an interface modification layer, a hole transport layer and a cathode layer, wherein the perovskite light absorbing layer is CsPbI2Br, the interface modification layer is 2-amino-5-bromoacetophenone, and the hole transport layer is Spiro-OMeTAD; The preparation steps of the interface modification layer are: 2-amino-5-bromoacetophenone is dissolved in isopropanol to obtain a 2-amino-5-bromoacetophenone / isopropanol solution, and the 2-amino-5-bromoacetophenone / isopropanol solution is spin-coated on a perovskite light-absorbing layer, and annealed to obtain an interface modification layer; the concentration of the 2-amino-5-bromoacetophenone / isopropanol solution is 1 mg / mL to 5 mg / mL, the spin-coating speed is 2500 to 4500 rpm, the spin-coating time is 20 to 50 seconds, the annealing temperature is 70 to 100°C, and the annealing time is 1 to 3 minutes.

2. The all-inorganic perovskite solar cell based on 2-amino-5-bromoacetophenone interface modification according to claim 1, characterized in that: The anode substrate is conductive glass FTO, the electron transport layer and the modification layer are SnO2 / SnCl2 thin films, that is, the SnO2 thin film of the electron transport layer and the perovskite light absorption layer are modified by SnCl2 thin film, and the cathode layer is Au.

3. The method for preparing an all-inorganic perovskite solar cell based on 2-amino-5-bromoacetophenone interface modification according to claim 1, characterized in that: The following steps are involved: After surface treatment, the anode substrate is spin-coated in sequence to prepare an electron transport layer and a modification layer, a perovskite light absorption layer, an interface modification layer and a hole transport layer, and then the cathode layer is prepared to obtain a 2-amino-5-bromoacetophenone interface modified all-inorganic perovskite solar cell.

4. The method for preparing an all-inorganic perovskite solar cell based on 2-amino-5-bromoacetophenone interface modification according to claim 3, characterized in that: The surface treatment steps of the anode substrate are: ultrasonic cleaning with acetone, anhydrous ethanol and deionized water for at least 30 minutes respectively, then vacuum drying, and then cleaning with ultraviolet ozone for at least 30 minutes.

5. The method for preparing an all-inorganic perovskite solar cell based on 2-amino-5-bromoacetophenone interface modification according to claim 3, characterized in that: The preparation steps of the electron transport layer and the modified layer are as follows: The SnO2 hydrocolloid dispersion liquid and deionized water are mixed in a certain volume ratio and stirred evenly, and filtered to obtain a SnO2 precursor solution; the SnO2 precursor solution is spin-coated onto an anode substrate and annealed; SnCl2 is dissolved in anhydrous ethanol to obtain a SnCl2 / anhydrous ethanol solution, and the SnCl2 / anhydrous ethanol solution is spin-coated on the annealed SnO2 film, and then gradient annealing is performed, and then ultraviolet ozone cleaning is used for at least 30 minutes to obtain an electron transport layer and a modification layer.

6. The method for preparing an all-inorganic perovskite solar cell based on 2-amino-5-bromoacetophenone interface modification according to claim 5, characterized in that: The volume ratio of the SnO2 hydrocolloid dispersion to deionized water is 1:2~1:4; the spin coating speed of the SnO2 precursor solution is 2000~4000 rpm, and the spin coating time is 15s~60s; the annealing temperature is 70~200℃, and the annealing time is 10~90 min; the concentration of the SnCl2 / anhydrous ethanol solution is 0.005~0.014 mol / L, the spin coating speed is 2500~4500 rpm, and the spin coating time is 25~45s; the first step annealing temperature of the gradient annealing is 70~120℃, and the time is 6~15 min; the second step annealing temperature is 140~200℃, and the time is 30~90 min.

7. The method for preparing an all-inorganic perovskite solar cell based on 2-amino-5-bromoacetophenone interface modification according to claim 3, characterized in that: The preparation steps of the perovskite light absorbing layer are as follows: The CsPbI2Br precursor solution is spin-coated on the electron transport layer and the modification layer. The spin coating is divided into two stages. The spin coating speed in the first stage is 700-1200 rpm and the spin coating time is 6-15 seconds. The spin coating speed in the second stage is 1000-2000 rpm and the spin coating time is 90-150 seconds. Then, the solution is annealed at 70-100°C for 2-6 minutes and then annealed at 130-160°C for 1-6 minutes to obtain a perovskite light absorbing layer.

8. The method for preparing an all-inorganic perovskite solar cell based on 2-amino-5-bromoacetophenone interface modification according to claim 3, characterized in that: The preparation steps of the hole transport layer and the cathode layer are as follows: The Spiro-OMeTAD solution was spin-coated on the interface modification layer at a speed of 2500-4500 rpm for 20-40 seconds to obtain a hole transport layer. Au was evaporated on the hole transport layer for 3-6 minutes at a vacuum degree of 1×10 -4 Pa ~9×10 -4 Pa, and obtained an all-inorganic perovskite solar cell based on 2-amino-5-bromoacetophenone interface modification.

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