A wide band gap perovskite thin film, and a preparation method and application thereof

Abstract

The present application relates to a kind of wide band gap perovskite film and its preparation method and application, belong to perovskite technical field.The preparation method of the present application includes the following steps: S1, perovskite precursor is dissolved in organic solvent, to obtain perovskite precursor solution;S2, ionic liquid is dissolved in perovskite precursor solution, to obtain modified perovskite precursor solution;S3, modified perovskite precursor solution is coated on the surface of conductive substrate, and the wide band gap perovskite film is obtained by heat annealing.The multifunctional ionic liquid 1-benzyl-3-methyl imidazole hexafluorophosphate is introduced into the wide band gap perovskite precursor solution, the crystallization kinetics of the film is effectively controlled, the generation of residual lead iodide impurity phase is inhibited, the perovskite phase and interface defects are passivated, and the defect state density is reduced, so that the high-quality wide band gap perovskite film with high phase purity, strong crystallinity and low defect density is prepared.

Description

Technical Field

[0001] This invention belongs to the field of perovskite technology, and particularly relates to a wide-bandgap perovskite thin film, its preparation method and application. Background Technology

[0002] With the rapid development of electronic information and distributed Internet of Things (IoT) technologies, wearable electronic devices, wireless sensor nodes, and other low-power electronic devices are experiencing rapid iteration and widespread adoption. These devices are mostly deployed indoors and are characterized by low power consumption, high quantity, and fragmentation. Traditional power supply methods rely on periodic active charging or wired connections, making it difficult to achieve intervention-free, self-contained operation. Therefore, there is an urgent need to develop new energy supply technologies to overcome existing bottlenecks. Indoor photovoltaic technology, with its ability to directly convert indoor ambient light into electricity, has become one of the core technological paths to achieve self-powering of electronic devices, effectively providing a continuous and clean energy supply for low-power electronic devices.

[0003] Compared to standard outdoor sunlight, indoor light sources (such as LEDs and fluorescent lamps) have significantly different optical characteristics. Their spectral distribution is narrower, energy is more concentrated, and the light intensity is much lower than standard sunlight. This characteristic places special demands on the light absorption layer material of indoor photovoltaic devices, requiring optical absorption characteristics that are highly matched to the spectrum of the indoor light source and excellent low-light response capabilities. Among numerous photovoltaic materials, organic-inorganic hybrid perovskite materials have received widespread attention and in-depth research in the field of indoor photovoltaics due to their outstanding advantages such as tunable bandgap, high light absorption coefficient, excellent carrier transport performance, simple fabrication process, and low cost. Wide-bandgap perovskite materials, in particular, can precisely match the spectral distribution of indoor light sources due to their wider optical bandgap, reducing energy loss caused by low-energy photon absorption, and also helping to obtain higher open-circuit voltage in low-light environments. V oc It is widely recognized as an ideal light-absorbing layer material for constructing high-efficiency indoor perovskite photovoltaic devices.

[0004] Despite the significant advantages of wide-bandgap perovskite materials in indoor photovoltaics, their application in low-light indoor environments still faces key technological bottlenecks. Because the incident photon flux indoors is far lower than that of standard outdoor sunlight, the concentration of photogenerated carriers within the device is low. Under these conditions, the impact of various defects in the perovskite film bulk phase and interfaces on device performance is significantly amplified. Specifically, uncoordinated Pb in the film... 2+ Defects such as ions, halogen vacancies, and non-photoactive impurities readily form non-radiative recombination centers, significantly exacerbating recombination losses of photogenerated carriers and consequently increasing the open-circuit voltage of the device. V ocThe fill factor and photoelectric conversion efficiency (PCE) decrease significantly, which seriously affects the long-term operational stability of the device and limits its practical application and promotion.

[0005] For the specific application scenario of indoor low-light photovoltaics, the key to improving the performance and stability of wide-bandgap perovskite photovoltaic devices lies in improving the crystal quality of the thin film and reducing film defects. Specifically, it is necessary to focus on improving the crystal quality of wide-bandgap perovskite films, increasing the purity of the film phase, and effectively passivating bulk and interface defects to suppress trap-assisted recombination. Currently, the industry has adopted strategies such as additive engineering and interface modification to optimize perovskite films. Although these methods can improve film quality and device performance to some extent, they still have significant shortcomings in controlling the crystallization process of wide-bandgap perovskite films, suppressing the formation of residual lead iodide (PbI2), and synergistic passivation of bulk and interface defects. These methods are insufficient to achieve simultaneous improvement in device efficiency and stability, and cannot meet the actual application requirements of indoor low-light photovoltaics.

[0006] Therefore, there is an urgent need to develop a wide-bandgap perovskite thin film and perovskite photovoltaic device preparation method that is suitable for indoor low-light environments and can effectively improve the quality of thin films and device performance, so as to provide technical support for the continuous power supply of indoor low-power electronic devices and promote the industrial application of indoor photovoltaic technology. Summary of the Invention

[0007] Therefore, the technical problem to be solved by the present invention is to overcome the problems of insufficient phase purity and high defect state density of wide-bandgap perovskite thin films in the prior art, and the resulting low photoelectric conversion efficiency and limited operational stability of indoor photovoltaic devices.

[0008] To address the aforementioned technical problems, this invention provides a wide-bandgap perovskite thin film, its preparation method, and its applications. By introducing the multifunctional ionic liquid 1-benzyl-3-methylimidazolium hexafluorophosphate (BZMIMPF6) into the wide-bandgap perovskite precursor solution, the crystallization kinetics of the film are effectively regulated, the formation of residual lead iodide (PbI2) impurity phase is suppressed, and the perovskite bulk phase and interface defects are synergistically passivated, reducing the defect state density. This results in the preparation of a high-quality wide-bandgap perovskite thin film with high phase purity, strong crystallinity, and low defect density. Indoor photovoltaic devices based on this film can significantly suppress trap-assisted nonradiative recombination losses, effectively improve photoelectric conversion efficiency, open-circuit voltage, and long-term operational stability, and can be used as a self-powered power source in wearable electronic devices, wireless sensor nodes, and other low-power electronic devices.

[0009] The first objective of this invention is to provide a method for preparing a wide-bandgap perovskite thin film, comprising the following steps: S1. Dissolve the perovskite precursor in an organic solvent to obtain a perovskite precursor solution; S2. Dissolve the ionic liquid in the perovskite precursor solution described in S1 to obtain a modified perovskite precursor solution. S3. The modified perovskite precursor solution described in S2 is coated onto the surface of a conductive substrate, and the wide-bandgap perovskite film is obtained by thermal annealing.

[0010] In one embodiment of the present invention, in S1, the composition of the perovskite precursor satisfies the general formula Cs. x FA y MA 1-x-y Pb(I z Br 1-z 3, where 0≤x≤0.1, 0.6≤y≤0.9, and 0.7≤z≤0.9; And / or, the concentration of the perovskite precursor solution is 1.4 mol / L to 1.6 mol / L.

[0011] In one embodiment of the present invention, in S1, the organic solvent is obtained by mixing N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) in a volume ratio of (3.8-4.2):1.

[0012] In one embodiment of the present invention, in S2, the ionic liquid is 1-benzyl-3-methylimidazolium hexafluorophosphate; And / or, the concentration of the ionic liquid in the modified perovskite precursor solution is 1.0 mmol / L-5.0 mmol / L.

[0013] In one embodiment of the present invention, in S3, the conductive substrate is selected from FTO transparent conductive glass or ITO transparent conductive glass.

[0014] In one embodiment of the present invention, in S3, the spin coating speed is 3800rpm-4200rpm and the time is 38s-42s; And / or, the temperature of the heat annealing is 95℃-105℃, and the time is 28min-32min.

[0015] A second objective of this invention is to provide a wide-bandgap perovskite thin film, which is prepared by the method described above.

[0016] The third objective of this invention is to provide a wide-bandgap perovskite photovoltaic device, wherein the wide-bandgap perovskite photovoltaic device comprises one or more of the following sequentially disposed: a conductive substrate, a hole transport layer, a perovskite layer, a passivation layer, an electron transport layer, a hole blocking layer, and an electrode layer; wherein the perovskite layer is the wide-bandgap perovskite thin film.

[0017] In one embodiment of the present invention, the material of the hole transport layer is selected from [4-(3,6-dimethoxy-9H-carbazole-9-yl)butyl]phosphonic acid and / or (2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl)phosphonic acid; The material of the passivation layer is selected from phenothiazine iodide and / or ethylenediamine dihydroiodide; The electron transport layer is made of [6,6]-phenyl-C 61 methyl butyrate; The hole-blocking layer is made of 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline. The electrode layer is made of silver and / or copper.

[0018] In one embodiment of the present invention, the thickness of the hole transport layer is 1 nm-1.5 nm; The thickness of the perovskite layer is 500nm-600nm; The thickness of the passivation layer is 3nm-4nm; The thickness of the electron transport layer is 30nm-35nm; The thickness of the hole blocking layer is 5nm-5.5nm; The thickness of the electrode layer is 80nm-120nm.

[0019] The technical solution of the present invention has the following advantages compared with the prior art: (1) The preparation method of the present invention introduces the ionic liquid 1-benzyl-3-methylimidazolium hexafluorophosphate (BZMIMPF6) into the wide-bandgap perovskite precursor solution, which can effectively regulate the crystallization kinetics of the film, suppress the generation of residual lead iodide (PbI2) impurity phase, improve the crystallinity and phase purity of the film, and at the same time synergistically passivate perovskite bulk phase and surface defects, reduce defect state density, suppress trap-assisted nonradiative recombination, and prolong the lifetime of photogenerated carriers, thereby obtaining a high-quality wide-bandgap perovskite film with strong crystallinity, smooth surface, high phase purity and low defect density.

[0020] (2) The preparation method described in this invention is simple, mild, and highly operable, requiring no complex equipment or stringent processes, and is suitable for large-scale production needs.

[0021] (3) The wide-bandgap perovskite photovoltaic device described in this invention has a high open-circuit voltage and excellent photoelectric performance in indoor low-light environments, and has excellent long-term operational stability under continuous illumination, and can stably achieve long-term power output; the photovoltaic device can serve as a stable self-powered power source, providing clean and continuous energy supply for wearable electronic devices, wireless sensor nodes and other low-power electronic devices, effectively solving the problems of insufficient photoelectric conversion efficiency, poor operational stability and complex manufacturing process of existing indoor low-light photovoltaic devices, with outstanding technical advantages and broad prospects for industrial application. Attached Figure Description

[0022] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein: Figure 1 SEM images of the perovskite films prepared in Examples 1-5 and Comparative Example 1 of this invention; Figure 2 The PL spectra and TRPL attenuation curves of the perovskite thin films prepared in Examples 1-5 and Comparative Example 1 of this invention; Figure 3 The perovskite photovoltaic devices prepared in Examples 1-5 and Comparative Example 1 of this invention JV curve; Figure 4 The X-ray diffraction patterns of the perovskite thin films prepared in Example 1 and Comparative Example 1 of this invention are shown below. Figure 5 The results of DLCP testing are for the perovskite photovoltaic devices prepared in Example 1 and Comparative Example 1 of this invention. Figure 6 The results are MPP tracking tests of the perovskite photovoltaic devices prepared in Example 1 and Comparative Example 1 of this invention. Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. It should be understood that the specific embodiments are only used to explain the present invention, but the embodiments are not intended to limit the present invention.

[0024] In this invention, unless otherwise stated, the technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0025] In this invention, unless otherwise stated, the term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0026] In this invention, unless otherwise specified, the experimental methods used in the embodiments of this invention are conventional methods, and the materials and reagents used are commercially available unless otherwise specified. Example 1

[0027] The wide-bandgap perovskite photovoltaic device and its fabrication method in this embodiment specifically include the following steps: S1 and FTO transparent conductive glass were sequentially cleaned and dried with deionized water, and then subjected to a power density of 30mW / cm². 2 The product was subjected to ultraviolet ozone treatment for 9 minutes to complete the hydrophilic modification. S2. Dissolve the hole transport material [4-(3,6-dimethoxy-9H-carbazole-9-yl)butyl]phosphonic acid in anhydrous ethanol to prepare a hole transport layer solution with a concentration of 0.5 mg / mL; spin-coat the solution onto the surface of FTO transparent conductive glass at a spin speed of 4500 rpm and a spin time of 32 s; after spin-coating, heat-anneal at 100℃ for 10 min to form a hole transport layer with a thickness of 1.2 nm; S3. Dissolve 536 mg PbI₂, 131 mg PbBr₂, 192.6 mg FAI, 18.2 mg CsI, 23.5 mg MABr, and 12 mg MACl in a DMF / DMSO mixed solvent with a volume ratio of 4:1 to prepare a 1.5 mol / L perovskite precursor solution. The resulting perovskite composition is CsI. 0.04 (FA 0.74 MA 0.26 ) 0.96 Pb(I 0.80 Br 0.20 3; Add 1-benzyl-3-methylimidazolium hexafluorophosphate (BZMIMPF6) to the above perovskite precursor solution to a concentration of 3.0 mmol / L to obtain a modified perovskite precursor solution; spin-coat the modified perovskite precursor solution onto the surface of the hole transport layer at a spin-coating speed of 4000 rpm and a spin-coating time of 40 s. 8 s before the end of spin-coating, add 200 μL of chlorobenzene as an anti-solvent to the wet film. After spin-coating, heat-anneal at 100 °C for 30 min to form a wide-bandgap perovskite film with a thickness of 575 nm; Note that a trace amount of Cl is introduced for crystallization modulation of the perovskite film, and is not used as a limitation on the proportion of halogen elements in the final perovskite composition; S4. Dissolve the passivation material phenothiazine iodide in isopropanol to prepare a passivation layer solution with a concentration of 0.5 mg / mL; spin-coat the solution onto the surface of the wide-bandgap perovskite film at a spin speed of 4750 rpm for 28 s; after spin-coating, heat-anneal the film on a hot plate at 100°C for 10 min to form a passivation layer with a thickness of 3.5 nm. S5, Using electron transport material [6,6]-phenyl-C 61 methyl butyrate was dissolved in chlorobenzene to prepare an electron transport layer solution with a concentration of 20 mg / mL. The solution was spin-coated onto the surface of the passivation layer at a spin speed of 2500 rpm for 32 s. After spin-coating, the solution was heat-annealed on a hot plate at 70 °C for 10 min to form an electron transport layer with a thickness of 32 nm. S6. Dissolve the hole-blocking material 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline in isopropanol to prepare a hole-blocking layer solution with a concentration of 0.7 mg / mL; spin-coat the solution onto the surface of the electron transport layer at a spin speed of 4500 rpm for 25 s; after spin-coating, heat-anneal at 70 °C for 5 min to form a hole-blocking layer with a thickness of 5.2 nm. S7. A silver electrode layer with a thickness of 100 nm is deposited on the surface of the hole blocking layer by thermal evaporation at a rate of 0.05 nm / s to obtain a wide-bandgap perovskite photovoltaic device. Example 2

[0028] The process is basically the same as in Example 1, except that 1-benzyl-3-methylimidazolium hexafluorophosphate (BZMIMPF6) is added to the perovskite precursor solution to make its molar concentration 1.0 mmol / L, thereby obtaining a modified perovskite precursor solution. Example 3

[0029] The process is basically the same as in Example 1, except that 1-benzyl-3-methylimidazolium hexafluorophosphate (BZMIMPF6) is added to the perovskite precursor solution to make its molar concentration 2.0 mmol / L, thereby obtaining a modified perovskite precursor solution. Example 4

[0030] The process is basically the same as in Example 1, except that 1-benzyl-3-methylimidazolium hexafluorophosphate (BZMIMPF6) is added to the perovskite precursor solution to make its molar concentration 4.0 mmol / L, thus obtaining a modified perovskite precursor solution. Example 5

[0031] The process is basically the same as in Example 1, except that 1-benzyl-3-methylimidazolium hexafluorophosphate (BZMIMPF6) is added to the perovskite precursor solution to make its molar concentration 5.0 mmol / L, thus obtaining a modified perovskite precursor solution. Comparative Example 1

[0032] The process is basically the same as in Example 1, except that 1-benzyl-3-methylimidazolium hexafluorophosphate (BZMIMPF6) was not added to the perovskite precursor solution. Test Example 1

[0033] The morphology of the perovskite films prepared in Examples 1-5 and Comparative Example 1 was characterized using scanning electron microscopy (SEM), and the results are as follows: Figure 1 As shown. From Figure 1 It can be seen that the perovskite film prepared in Comparative Example 1 without the addition of the ionic liquid 1-benzyl-3-methylimidazolium hexafluorophosphate (BZMIMPF6) has a large number of blocky residues on its surface, with disordered grain arrangement and uneven morphology in some areas, resulting in low overall crystallinity and poor film uniformity. Compared with Comparative Example 1, the perovskite films prepared in Examples 1-5 with different concentrations of BZMIMPF6 showed significantly improved morphology, with denser and more uniform grains and a significant reduction in blocky residues. This indicates that BZMIMPF6 can effectively regulate the crystallization kinetics of wide-bandgap perovskites and suppress the formation of impurity phases. Improving the uniformity of film morphology: As the concentration of BZMIMPF6 gradually increased from 1.0 mmol / L to 5.0 mmol / L, the crystallinity quality of the film showed a trend of first optimization and then stabilization. Among them, Example 1 with a concentration of 3.0 mmol / L performed best, with the largest film grain size, the smoothest and most uniform surface, and no obvious residual impurity phase. This indicates that BZMIMPF6 has the most significant regulatory effect on the crystallization process at this concentration, and can prepare high-quality wide-bandgap perovskite films with high crystallinity, good phase purity, and few surface defects, laying a material foundation for improving the optoelectronic performance and stability of devices. Test Example 2

[0034] Steady-state photoluminescence (PL) tests were performed on the perovskite films prepared in Examples 1-5 and Comparative Example 1 using a xenon lamp (Xe 900) with an excitation wavelength of 405 nm, and time-resolved photoluminescence (TRPL) tests were performed using a 405 nm picosecond pulsed laser (EPL 405 nm). The results are as follows: Figure 2 As shown. From Figure 2As can be seen, compared with Comparative Example 1 without BZMIMPF6, the photoluminescence intensity of the wide-bandgap perovskite films prepared in Examples 1-5 with different concentrations of BZMIMPF6 was significantly improved. This indicates that the introduction of BZMIMPF6 effectively passivated the nonradiative recombination centers in the film, suppressed trap-assisted recombination, and thus reduced the nonradiative loss of photogenerated carriers. Simultaneously, the photogenerated carrier decay lifetime of the wide-bandgap perovskite films prepared in Examples 1-5 was significantly longer than that of Comparative Example 1, proving that BZMIMPF6 can effectively passivate bulk and surface defects in perovskite films and suppress defect-mediated degradation. The nonradiative recombination process extends the carrier lifetime. As the concentration of BZMIMPF6 increases from 1.0 mmol / L to 5.0 mmol / L, the luminescence intensity and carrier lifetime of the thin film show a trend of first increasing and then decreasing. Among them, Example 1 with a concentration of 3.0 mmol / L has the highest photoluminescence intensity, the longest carrier decay lifetime, and the most significant defect passivation effect. This further confirms that at this concentration, BZMIMPF6 can minimize the defect state density of wide-bandgap perovskite thin films and reduce nonradiative recombination losses, providing key support for improving the photoelectric conversion efficiency and stability of indoor photovoltaic devices. Test Example 3

[0035] The luminous intensity of the indoor LED light source was calibrated to 303 μW / cm² using a Spectra Light ILT950 spectrometer. 2 Under this LED light intensity, the perovskite photovoltaic devices prepared in Examples 1-5 and Comparative Example 1 were tested using a Keithley 2400 source meter. J - V Curve test, results as follows Figure 3 As shown. From Figure 3 It can be seen that the photoelectric conversion efficiency (PCE) of the Comparative Example 1 device without BZMIMPF6 is 38.62%. The PCEs of the devices in Examples 1-5 with different concentrations of BZMIMPF6 are 41.41%, 39.77%, 40.44%, 40.96%, and 40.57%, respectively. The efficiency of all examples is significantly higher than that of Comparative Example 1. Moreover, as the concentration of BZMIMPF6 increases, the PCE of the device shows a trend of first increasing and then decreasing. Among them, Example 1 with a BZMIMPF6 concentration of 3 mmol / L has the best photoelectric conversion efficiency, reaching 41.41%. This indicates that the introduction of BZMIMPF6 into the perovskite precursor solution can effectively regulate the crystal quality of the thin film, passivate defects, and suppress non-radiative recombination, thereby significantly improving the photoelectric performance of wide-bandgap perovskite photovoltaic devices in indoor low-light environments. Test Example 4

[0036] Using Cu Kα as the X-ray source, the perovskite films prepared in Example 1 and Comparative Example 1 were characterized by X-ray diffraction in θ-2θ scanning mode. The results are as follows: Figure 4 As shown. From Figure 4 As can be seen, compared with Comparative Example 1, the intensity of the characteristic diffraction peak of residual PbI2 in the perovskite film prepared in Example 1 is significantly reduced, and the characteristic peak of the main crystal phase of perovskite is sharper and has higher intensity. This indicates that the addition of BZMIMPF6 can effectively suppress the generation and enrichment of residual PbI2 impurity phase during the crystallization process of perovskite, improve the crystallinity and phase purity of the film, reduce the defect states and carrier recombination centers induced by impurity phase, and provide structural protection for achieving efficient and stable output of indoor photovoltaic devices. Test Example 5

[0037] The perovskite photovoltaic devices prepared in Example 1 and Comparative Example 1 were subjected to drive-level capacitance analysis spectroscopy (DLCP) using a semiconductor parameter analyzer (Keithley 4200A). The results are as follows: Figure 5 As shown. From Figure 5 As can be seen, compared with the Comparative Example 1 device without BZMIMPF6, the defect state density of Example 1 device with 3.0 mmol / L BZMIMPF6 is significantly reduced throughout the entire longitudinal depth range, which fully demonstrates that BZMIMPF6 can efficiently passivate defects in the bulk phase and surface interface of perovskite thin films and significantly reduce the number of trap-assisted nonradiative recombination centers. Test Example 6

[0038] Using 100mW / cm 2 The LED light source was used to conduct accelerated illumination stability tests at the maximum power point (MPP) of the perovskite photovoltaic devices prepared in Example 1 and Comparative Example 1 under an environment of 50℃ and 40% relative humidity. The tests used a perturbation observation method to determine and periodically update the maximum power point. The results are as follows: Figure 6 As shown. From Figure 6 As can be seen, the normalized photoelectric conversion efficiency of the Comparative Example 1 device without BZMIMPF6 decreased rapidly in the early stage of the test, dropping to about 50% of the initial value after about 100 hours. The device had poor operational stability and was prone to rapid performance degradation due to defect-induced nonradiative recombination and thin film structure deterioration during long-term operation. In contrast, the Example 1 device with 3.0 mmol / L BZMIMPF6 maintained 96% of the initial PCE after 700 hours of continuous illumination, demonstrating a significant improvement in stability.

[0039] In summary, BZMIMPF6 can regulate the crystallization kinetics of wide-bandgap perovskites, suppress the formation of residual PbI2 impurity phases, and improve the crystallinity and phase purity of the thin film. At the same time, it can synergistically passivate bulk phase and surface defects, reduce defect state density, suppress defect-mediated nonradiative recombination, and prolong carrier lifetime. This significantly improves the open-circuit voltage, fill factor, and photoelectric conversion efficiency of wide-bandgap perovskite photovoltaic devices in indoor low-light environments, enhances the long-term output stability and power supply reliability of the devices, and better meets the practical application requirements of indoor low-power electronic devices for long-term stable self-powering.

[0040] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a wide-bandgap perovskite thin film, characterized in that, Includes the following steps: S1. Dissolve the perovskite precursor in an organic solvent to obtain a perovskite precursor solution; S2. Dissolve the ionic liquid in the perovskite precursor solution described in S1 to obtain a modified perovskite precursor solution. S3. The modified perovskite precursor solution described in S2 is coated onto the surface of a conductive substrate, and the wide-bandgap perovskite film is obtained by thermal annealing.

2. The method for preparing a wide-bandgap perovskite thin film according to claim 1, characterized in that, In S1, the composition of the perovskite precursor satisfies the general formula Cs. x FA y MA 1-x-y Pb(I z Br 1-z 3, where 0≤x≤0.1, 0.6≤y≤0.9, and 0.7≤z≤0.9; And / or, the concentration of the perovskite precursor solution is 1.4 mol / L to 1.6 mol / L.

3. The method for preparing a wide-bandgap perovskite thin film according to claim 1, characterized in that, In S1, the organic solvent is obtained by mixing N,N-dimethylformamide and dimethyl sulfoxide in a volume ratio of (3.8-4.2):

1.

4. The method for preparing a wide-bandgap perovskite thin film according to claim 1, characterized in that, In S2, the ionic liquid is 1-benzyl-3-methylimidazolium hexafluorophosphate; And / or, the concentration of the ionic liquid in the modified perovskite precursor solution is 1.0 mmol / L-5.0 mmol / L.

5. The method for preparing a wide-bandgap perovskite thin film according to claim 1, characterized in that, In S3, the conductive substrate is selected from FTO transparent conductive glass or ITO transparent conductive glass.

6. The method for preparing a wide-bandgap perovskite thin film according to claim 1, characterized in that, In S3, the spin coating speed is 3800rpm-4200rpm and the time is 38s-42s; And / or, the temperature of the heat annealing is 95℃-105℃, and the time is 28min-32min.

7. A wide-bandgap perovskite thin film, characterized in that, The wide-bandgap perovskite thin film is prepared by the method described in any one of claims 1-6.

8. A wide-bandgap perovskite photovoltaic device, characterized in that, The wide-bandgap perovskite photovoltaic device comprises one or more of the following sequentially arranged components: a conductive substrate, a hole transport layer, a perovskite layer, a passivation layer, an electron transport layer, a hole blocking layer, and an electrode layer; wherein the perovskite layer is the wide-bandgap perovskite thin film as described in claim 7.

9. The wide-bandgap perovskite photovoltaic device according to claim 8, characterized in that, The material of the hole transport layer is selected from [4-(3,6-dimethoxy-9H-carbazole-9-yl)butyl]phosphonic acid and / or (2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl)phosphonic acid; The material of the passivation layer is selected from phenothiazine iodide and / or ethylenediamine dihydroiodide; The electron transport layer is made of [6,6]-phenyl-C 61 methyl butyrate; The hole-blocking layer is made of 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline. The electrode layer is made of silver and / or copper.

10. The wide-bandgap perovskite photovoltaic device according to claim 8, characterized in that, The thickness of the hole transport layer is 1nm-1.5nm; The thickness of the perovskite layer is 500nm-600nm; The thickness of the passivation layer is 3nm-4nm; The thickness of the electron transport layer is 30nm-35nm; The thickness of the hole blocking layer is 5nm-5.5nm; The thickness of the electrode layer is 80nm-120nm.

Images