Perovskite solar cell based on fluorine-chlorine synergistic effect and preparation method thereof

Abstract

The application discloses a perovskite solar cell based on fluorine-chlorine synergistic effect, comprising a glass substrate, an electron transport layer, a perovskite light-absorbing layer obtained by coating and annealing of a perovskite precursor solution containing 3-fluoro-4-chloroaniline iodide, a hole transport layer and a metal electrode which are stacked in sequence. The 2D / 3D perovskite thin film treated by 3-F-4-ClAnI not only shows a highly ordered crystal structure, but also significantly improves the photoelectric performance of the 2D / 3D perovskite solar cell; and the synergistic effect of C-F and C-Cl groups optimizes the optimal Pb-I-Pb torsion angle and significantly enhances the coordination of Pb 2+ Compared with the unmodified FAPbI3, the stability of the perovskite thin film device treated by 3-F-4-ClAnI is significantly enhanced, the non-radiative recombination is effectively inhibited, the interface charge extraction is improved, and the device has superior long-term stability at room temperature.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of solar cell preparation, and particularly relates to a perovskite solar cell based on fluorine-chlorine synergistic effect and a preparation method thereof. BACKGROUND

[0002] Organic-inorganic hybrid perovskite (OIHPS) as a star semiconductor material has significant advantages in the next generation of photovoltaic devices. Due to its excellent performance such as suitable band gap, high carrier mobility and strong light absorption coefficient, it becomes the most potential candidate for photovoltaic devices. However, the traditional three-dimensional perovskite prepared by using organic cations (such as CH3NH 3+ , CH (NH2) 2+ , Cs + ) is difficult to cope with serious non-radiation caused by deep defects, resulting in very poor environmental stability of the traditional three-dimensional perovskite material, which is easy to decompose in ultraviolet irradiation, high temperature and water environment, and further leads to a substantial reduction in the performance of light-emitting devices.

[0003] In recent years, two-dimensional perovskite has been proved as a potential strategy to improve the humidity and heat stability and photoelectric performance of perovskite solar cells, in which F or Cl containing organic ammonium salt is widely used. For example, CN202210534746.5 discloses a carbon-based inorganic perovskite solar cell passivated by ammonium fluoride salt and a preparation method thereof, which effectively passivates the surface defects of the inorganic perovskite light-absorbing layer by using ammonium fluoride salt, optimizes the interface energy level arrangement, and can significantly improve the hydrophobicity of the inorganic perovskite light-absorbing layer while inhibiting the non-radiative recombination of charges, thereby improving the efficiency and humidity stability of the device. Although the strong electronegativity of fluorine atom can absorb electrons and induce more positive charge accumulation on the -NH 3+ side, the change of fluorine position also changes the electron density distribution on the benzene ring. Chinese patent CN202211487944.7 discloses a method for efficiently passivating a wide-bandgap perovskite of lead iodide by pure chlorine two-dimensional perovskite and a solar cell thereof, although Cl ion can be easily combined into the perovskite lattice, has a stronger Pb-Cl bond, and provides effective passivation, thereby reducing photovoltaic performance. However, due to the limited passivation effect of chlorine element and the mutual influence of electron cloud density around halogen atoms. Therefore, the existing perovskite solar cell has limited photoelectric conversion efficiency, and it is necessary to develop a perovskite solar cell with higher photoelectric conversion efficiency and a preparation method thereof, which has very important significance for promoting the preparation of high-efficiency and stable perovskite solar cells. SUMMARY

[0004] Therefore, the present application provides a perovskite solar cell, which solves the problems of low photoelectric conversion efficiency and poor stability of the existing perovskite solar cell.

[0005] The application adopts a perovskite solar cell based on fluorine-chlorine synergistic effect, comprising glass substrate, electron transport layer, perovskite light-absorbing layer, hole transport layer and metal electrode which are stacked in sequence, wherein the perovskite light-absorbing layer is obtained by coating and annealing of perovskite precursor solution containing 3-fluoro-4-chloroanilinium iodide.

[0006] Preferably, the amount of 3-fluoro-4-chloroanilinium iodide is 2.7-5.5 mg.

[0007] The application adopts a preparation method of perovskite solar cell based on fluorine-chlorine synergistic effect, comprising the following steps: (1) glass substrate preparation: taking FTO glass substrate, sequentially cleaning with detergent, deionized water, acetone and isopropanol, drying and ozone treatment to obtain; (2) electron transport layer preparation: taking SnO2 colloid precursor, coating on FTO glass substrate and annealing to obtain;

[0008] (3) perovskite light-absorbing layer preparation: taking perovskite precursor solution containing 3-fluoro-4-chloroanilinium iodide, spin coating on the electron transport layer and annealing to obtain;

[0009] (4) hole transport layer preparation: taking 2,2',7,7'-tetrakis[n,n-bis (4-methoxyphenyl) amino]-9,9'-spirobifluorene solution, depositing on the perovskite light-absorbing layer to obtain hole transport layer;

[0010] (5) metal electrode preparation: using mask plate to obtain Au electrode by thermal evaporation in vacuum chamber, finally obtaining a perovskite solar cell based on fluorine-chlorine synergistic effect.

[0011] Preferably, in step (3), 548.6 mg of lead iodide, 77.07 mg of lead bromide, 190.12 mg of formamidinium iodide, 21.84 mg of methylammonium bromide and 4.2 mg of 3-F-4-ClAnI are dissolved in DMF / DMSO mixed solvent, then 34 μL of CsI stock solution with a concentration of 519 mg / mL is added and stirred to prepare perovskite precursor solution, then 80 uL of perovskite precursor solution is deposited on SnO2 film at a speed of 2000 rpm for 10 s, then 0.2 mL of chlorobenzene is added on the spin substrate at a speed of 6000 rpm for 45 s, 15 s before the end of the second spin coating, and then annealing at 110℃ for 60 min to obtain perovskite light-absorbing layer.

[0012] Preferably, in step (3), the perovskite precursor solution is prepared by weighing 1202 mg of formamidinium lead iodide and 33.76 mg of methylammonium chloride, 4.2 mg of 3-F-4-ClAnI and 8.21 mg of methylamine lead bromide into 1 mL of a mixed solvent of DMF and DMSO, taking 80 uL of the perovskite precursor solution to be coated on the prepared SnO2 substrate at a speed of 5500 rpm, dropping in 0.12 mL of ether as an anti-solvent during the spin coating process, and then annealing at a temperature of 150°C, and spin coating 4 mg / mL of octylammonium iodide on the perovskite film to obtain.

[0013] Preferably, in step (3), the concentration of 3-F-4-ClAnI in the perovskite precursor solution is 0.1-0.2 mol / mL.

[0014] Preferably, in step (4), the 2,2',7,7'-tetrakis[n,n-bis(4-methoxyphenyl)amino]-9,9'-spirobifluorene solution further comprises a lithium bis-trifluoromethanesulfonimide stock solution, tributyl phosphate and chlorobenzene.

[0015] The present application provides a preparation method of a perovskite solar cell based on the synergistic effect of fluorine and chlorine. The perovskite light-absorbing layer is treated with 3-fluoro-4-chloroaniline iodide. It is found that the 2D / 3D perovskite film treated with 3-F-4-ClAnI not only exhibits the highest ordered crystal structure, but also significantly improves the photoelectric performance of the 2D / 3D perovskite solar cell (from 19.54% to 22.30%; from 23.27% to 24.74%); the synergistic effect of C-F and C-Cl groups optimizes the optimal Pb-I-Pb torsion angle, and the synergistic effect between F and Cl atoms significantly enhances the coordination effect of Pb 2+ Compared with the unmodified FAPbI3, the stability of the perovskite cell modified by 3-F-4-ClAnI is significantly enhanced, the non-radiative recombination is effectively inhibited, the interface charge extraction is improved, and the perovskite cell has superior long-term stability at room temperature (after 700 h of maximum power point tracking, the initial efficiency is maintained at 86.0%). BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 A schematic diagram of the formation of a perovskite solar film modified by 3-F-4-ClAnI;

[0017] Figure 2 A PL intensity diagram of the front / rear of the FA / MA (n=2) perovskite single crystal and the perovskite film of Example One;

[0018] Figure 3SEM images of perovskite films prepared for Example 1 and Comparative Example 1;

[0019] Figure 4 Humidity stability test of perovskite cells for Example 1 and Comparative Example 1 under ambient conditions (RH: 50±10%, 25℃) without encapsulation, wherein Control represents Comparative Example 1 and Target represents Example 1;

[0020] Figure 5 Steady-state PL intensity images of perovskite films modified with 3-F-4-ClAnI at different concentrations;

[0021] Figure 6 J-V curve images of 3-F-4-ClAnI modified FAPbI3 devices prepared for Example 2 and standard FAPbI3 prepared for Comparative Example 3.

[0022] Figure 7 Stability test images of standard devices prepared for Comparative Example 1 and 3-F-4-ClAnI modified devices prepared for Example 1 operated at 35℃ for 700 h. DETAILED DESCRIPTION

[0023] The principles and features of the present application are described below in conjunction with the accompanying drawings, which are presented only for the purpose of explanation and are not intended to limit the scope of the present application.

[0024] 3-Fluoro-4-chloroanilinium iodide (3-F-4-ClAnI), 3-chloro-4-fluoroanilinium iodide (3-Cl-4-FAnI), 3,4-dichloroanilinium iodide (34-ClAnI) and 3,4-difluoroanilinium iodide (3,4-FAnI) can be purchased or prepared according to existing methods.

[0025] Example 1: A perovskite solar cell based on the synergistic effect of fluorine and chlorine, comprising a glass substrate, an electron transport layer, a perovskite light-absorbing layer, a hole transport layer and a metal electrode which are sequentially stacked. The specific preparation method comprises the following steps:

[0026] (1) Glass substrate preparation: Take the FTO glass substrate and clean it with detergent, deionized water, acetone and isopropanol for 15 minutes, then dry and treat with UV ozone for 20 min, and then store it for use;

[0027] (2) Electron transport layer preparation: Take 80 uL of diluted SnO2 colloid precursor (mass fraction of 15% SnO2 and volume ratio of water is 1:3) and spin-coat it on the cleaned FTO glass substrate at 4000 rpm for 30 s, then anneal it on a hot plate at 150℃ for 30 min to obtain the electron transport layer.

[0028] (3) Perovskite light-absorbing layer preparation: Perovskite light-absorbing layer deposition was carried out in a glove box filled with N2. 548.6 mg of lead iodide, 77.07 mg of lead bromide, 190.12 mg of formamidinium iodide, 21.84 mg of methylammonium bromide, and 4.2 mg of 3-F-4-ClAnI were dissolved in 1 mL of a DMF / DMSO (v / v=4:1) mixed solvent, and then 34 μL of a CsI stock solution (519 mg of CsI dissolved in 1 mL of DMSO) was added and stirred for 2 h to prepare a perovskite precursor solution. Then, 80 uL of the perovskite precursor solution was deposited on the SnO2 film at a speed of 2000 rpm for 10 s, and then at a speed of 6000 rpm for 45 s. At 15 s before the end of the second spin coating, 0.2 mL of anti-solvent chlorobenzene was added to the spin substrate, and then annealing was performed at 110°C for 60 min to obtain a Cs 0.05 MA 0.16 FA 0.79 Pb(I 0.83 Br 0.17 )3 perovskite material (schematic diagram of crystal growth as shown in Figure 1 , indicating that it formed a 2D / 3D perovskite crystal), wherein the concentration of 3-F-4-ClAnI in the perovskite precursor solution was 0.15 mol / mL.

[0029] (4) Hole transport layer preparation: 72.3 mg of 2,2',7,7'-tetrakis[n,n-bis(4-methoxyphenyl)amino]-9,9'-spirobifluorene (Spiro-OMeTAD), 35 μL of a lithium bis(trifluoromethanesulfonyl)imide stock solution (260 mg of Li-TFSI added to 1 mL of acetonitrile), 30 μL of tributylphosphite (t-BP), and 1 mL of chlorobenzene were prepared into a spin coating solution, and 80 uL of the spin coating solution was deposited on the prepared perovskite light-absorbing layer at a speed of 3000 rpm for 30 s to obtain.

[0030] (5) Metal electrode preparation: An Au electrode with a thickness of 100 nm was obtained by using a mask plate to perform thermal evaporation in a vacuum chamber (1 × 10 -4 Pa). The preparation of the above (2), (3 and (4)) was carried out in a film applicator.

[0031] Example Two: The difference between Example Two and Example One is that the preparation of perovskite light-absorbing layer is different: 1202 mg of formamidinium lead iodide and 33.76 mg of methylammonium chloride, 4.2 mg of 3-F-4-ClAnI and 8.21 mg of methylamine lead bromide are weighed and dissolved in 1 mL of mixed solvent of DMF and DMSO (v / v = 4:1) to prepare a perovskite precursor solution, 80 uL of the perovskite precursor solution is used to coat the prepared SnO2 substrate at a speed of 5500 rpm for 50 s, 0.12 mL of ether is added as an anti-solvent at 13 s before the end of the spin coating, and then the perovskite film is annealed at a temperature of 150°C for 15 min, and then 4 mg / mL of octylammonium iodide (isopropyl alcohol as solvent) is spin-coated on the perovskite film at a speed of 3000 rpm for 30 s.

[0032] Examples Three to Five: The difference between Examples Three to Five and Example One is that the amount of 3-F-4-ClAnI single crystal added in step (3) is 1.4 mg, 2.7 mg and 5.5 mg, respectively, and the concentration of 3-F-4-ClAnI in the perovskite precursor solution is 0.05 mg / mL, 0.10 mg / mL and 0.20 mg / mL, respectively.

[0033] Comparative Example One: The difference between Comparative Example One and Example One is that no 3-F-4-ClAnI is added in step (3).

[0034] Comparative Example Two: The difference between Comparative Example Two and Example One is that 3-chloro-4-fluoroaniline iodide (3-Cl-4-FAnI), 3,4-dichloroaniline iodide (3,4-ClAnI) and 3,4-difluoroaniline iodide (3,4-FAnI) are respectively used to replace 3-fluoro-4-chloroaniline iodide (3-F-4-ClAnI) in the same molar amount. The J-V curve of the prepared device of the perovskite solar cell prepared in Example One and Comparative Example One is tested, as shown in Table 1, the modification of the perovskite light-absorbing layer with 3-F-4-ClAnI significantly enhances the coordination effect of Pb 2+ based on the synergistic effect of C-F and C-Cl groups, and a higher photoelectric conversion efficiency is obtained (from 19.54% to 22.30%).

[0035] Table 1: Comparison of photoelectric conversion efficiency of perovskite solar cells prepared in Example One, Comparative Example One and Comparative Example Two

[0036] Item Comparative Example 1 Example 1 3,4-FAnI 3,4-ClAnI 3-Cl-4-FAnI Photoelectric conversion efficiency (PCE) 19.54% 22.30% 21.41% 20.67% 19.90%

[0037] Comparative Example Three: The difference between Comparative Example Three and Example Two is that no 3-F-4-ClAnI is added in step (3), and the other steps are the same.

[0038] The perovskite solar cells prepared in Examples 1-5 and Comparative Examples 1-2 were tested for performance, and the results are as follows:

[0039] (1) Steady-state PL spectra of FA-based (n=2, 3-F-4ClAn2FAPb2I7) and MA-based (n=2, 3-F-4ClAn2MAPb2I7) 2D perovskite single crystals prepared by 3-F-4ClAnI salt, and steady-state PL spectra of 2D / 3D perovskite thin films treated by 3-F-4-ClAnI at the beginning of thermal annealing with front and backside excitation on glass, as shown in Figure 2 , it can be inferred that the FA-based 2D template with n=2 is first formed on the gas / liquid interface, and immediately templates the epitaxial growth of the 3D perovskite thin film as a skeleton, indicating a top-down growth direction, forming a 2D / 3D perovskite thin film.

[0040] (2) The perovskite thin films prepared in Example 1 and Comparative Example 1 were tested by scanning electron microscopy, as shown in Figure 3 The SEM images show that the perovskite thin film of Comparative Example 1 shows a highly disordered film quality, residual PbI2 and small grain size (300 nm), and the cross-sectional scanning electron microscope (SEM) image of Example 1 shows overall particles from top to bottom (400 nm) without obvious voids, and well-stacked vertical perovskite particles can transport carriers without crossing grain boundaries (GB), thereby promoting carrier migration and suppressing non-radiative recombination. It is shown that the 2D / 3D perovskite thin film treated by 3-F-4-ClAnI exhibits the highest ordered crystal structure, significantly improving the photoelectric performance of the 2D / 3D perovskite solar cell (PSC).

[0041] (3) Humidity stability test of the perovskite cells of Example 1 and Comparative Example 1 under ambient conditions (RH: 50±10%, 25°C) without encapsulation, where Control represents Comparative Example 1 and Target represents Example 1, and the results are shown in Figure 4 After 1000 h of exposure in a dark environment with high humidity (RH=50±10%, T=25°C), the PCE retention rate of Example 1 was 91.6%, while the PCE retention rate of Comparative Example 1 was only 51.2%, thus the stability of the 3-F-4-ClAnI perovskite device was significantly enhanced compared to the unmodified FAPbI3, effectively suppressing non-radiative recombination, improving interface charge extraction, and allowing long-term storage under ambient conditions, with potential for application.

[0042] (4) The steady-state PL intensity maps of the 3-F-4-ClAnI modified perovskite films prepared in Example 1, Examples 3-5, respectively, are shown in FIG. 2. Figure 5 As shown in the results, the blue shift of the perovskite film prepared in Example 1 is more obvious and the PL intensity is the highest, indicating that the perovskite film prepared in Example 1 has the lowest defect density and the best film quality.

[0043] (5) The J-V curves of the standard sample FAPbI3 prepared in Comparative Example 3 and the 3-F-4-ClAnI modified FAPbI3 device prepared in Example 2 are shown in FIG. 3. Figure 6 It is shown that, by using a different coating method and raw material than Example 1, the photoelectric conversion efficiency of the 3-F-4-ClAnI modified perovskite film relative to the original standard sample is also significantly improved (from 23.27% to 24.74%), indicating that the 3-F-4-ClAnI modified perovskite film is also applicable to different experimental schemes, and indirectly verifies that, under the modification of 3-F-4-ClAnI, the Pb-I-Pb torsion angle of the perovskite film is optimal, and the Pb + halide interaction between the uncoordinated Pb 2+ and the 3,4-An 2+ halide also plays an important role in strengthening the stability of the 2D / 3D perovskite.

[0044] (6) The stability of the perovskite solar cell devices prepared in Example 1 and Comparative Example 1 was tested

[0045] As shown in FIG. 4, Figure 7 after 700 hours of maximum power point tracking under 35° continuous illumination, the devices of the standard sample of Comparative Example 1 and the device modified by 3-F-4-ClAnI in Example 1 maintained 40.3% and 86.0% of the initial efficiency, respectively. It is shown that the molecule forms a stable 2D / 3D perovskite film, which improves the stability of the overall device.

[0046] In summary, by using the preparation method of the perovskite solar cell based on the fluorine-chlorine synergistic effect provided by the present application, the 3-F-4-ClAnI is used to modify the perovskite light absorption layer, it is found that the 2D / 3D perovskite film treated by 3-F-4-ClAnI not only exhibits the highest ordered crystal structure, but also significantly improves the photoelectric performance of the 2D / 3D perovskite solar cell (PSC); and the synergistic effect of the C-F and C-Cl groups optimizes the optimal Pb-I-Pb torsion angle, and the synergistic effect between the F and Cl atoms significantly enhances the Pb 2+The coordination effect of the 3-F-4-ClAnI ligand. Compared with the unmodified FAPbI3, the stability of the 3-F-4-ClAnI perovskite film is significantly enhanced, the non-radiative recombination is effectively inhibited, the interface charge extraction is improved, and the film has superior long-term stability at room temperature and high temperature.

[0047] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A perovskite solar cell based on the synergistic effect of fluorine and chlorine, comprising a glass substrate, an electron transport layer, a perovskite light-absorbing layer, a hole transport layer, and a metal electrode stacked sequentially, characterized in that, The perovskite light-absorbing layer is obtained by coating and annealing a perovskite precursor solution containing 3-fluoro-4-chloroaniline iodide.

2. The perovskite solar cell based on the synergistic effect of fluorine and chlorine according to claim 1, characterized in that, The dosage of the 3-fluoro-4-chloroaniline iodide is 2.7-5.5 mg.

3. A method for fabricating a perovskite solar cell based on the synergistic effect of fluorine and chlorine, characterized in that, Includes the following steps: (1) Glass substrate preparation: FTO glass substrate was cleaned in sequence with detergent, deionized water, acetone and isopropanol, then dried and treated with ozone to obtain the substrate. (2) Electron transport layer preparation: SnO2 colloidal precursor was coated on FTO glass substrate and annealed to obtain the electron transport layer. (3) Preparation of perovskite light-absorbing layer: Take the perovskite precursor solution containing 3-fluoro-4-chloroaniline iodide, spin-coat it on the electron transport layer and anneal it to obtain SnO2 film; (4) Hole transport layer preparation: 2,2',7,7'-tetrakis[n,n-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene solution was deposited on the perovskite light-absorbing layer to obtain the hole transport layer; (5) Metal electrode preparation: Au electrode was obtained by thermal evaporation in a vacuum chamber using a mask template, and finally a perovskite solar cell based on the synergistic effect of fluorine and chlorine was obtained.

4. The method for preparing a perovskite solar cell based on the synergistic effect of fluorine and chlorine according to claim 3, characterized in that, In step (3), 548.6 mg of lead iodide, 77.07 mg of lead bromide, 190.12 mg of formamidinium iodide, 21.84 mg of methylammonium bromide and 4.2 mg of 3-F-4-ClAnI were dissolved in a DMF / DMSO mixed solvent. Then, 34 μL of CsI stock solution with a concentration of 519 mg / mL was added and stirred to prepare a perovskite precursor solution. Then, 80 μL of the perovskite precursor solution was deposited on a SnO2 film at a speed of 2000 rpm for 10 s, followed by deposition at a speed of 6000 rpm for 45 s. 15 s before the end of the second spin coating, 0.20 mL of chlorobenzene was dropped onto the spin substrate, and then annealed at 110 °C for 60 min to obtain a perovskite light-absorbing layer.

5. The method for preparing a perovskite solar cell based on the synergistic effect of fluorine and chlorine according to claim 3, characterized in that, In step (3), 1202 mg of formamidinium lead triiodide, 33.76 mg of methylammonium chloride, 4.2 mg of 3-F-4-ClAnI, and 8.21 mg of methylamine lead bromide were weighed and dissolved in a mixed solvent of 1 mL DMF and DMSO to prepare a perovskite precursor solution. 80 μL of the perovskite precursor solution was coated onto the prepared SnO2 film at a speed of 5500 rpm. The coating was repeated twice. After the spin coating, 0.12 mL of diethyl ether was added as an antisolvent. The film was then annealed at 150 °C. Finally, 4 mg / mL octyl iodide was spin-coated onto the perovskite film to obtain the final product.

6. The method for preparing a perovskite solar cell based on the synergistic effect of fluorine and chlorine according to claim 3, characterized in that, In step (3), the concentration of 3-F-4-ClAnI in the perovskite precursor solution is 0.1-0.2 mol / mL.

7. The method for preparing a perovskite solar cell based on the synergistic effect of fluorine and chlorine according to claim 4, characterized in that, In step (4), the 2,2',7,7'-tetra[n,n-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene solution also contains lithium bis(trifluoromethanesulfonyl)imide stock solution, tributyl phosphate and chlorobenzene.

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