A perovskite solar cell with an ionic liquid modified double interface and a preparation method and application thereof

Abstract

The application particularly relates to a perovskite solar cell with ion liquid modified double interfaces, a preparation method and application thereof. The perovskite solar cell with ion liquid modified double interfaces comprises a transparent conductive substrate, an electron transport layer or a hole transport layer, an ion liquid double interface modification layer, a perovskite light absorption layer, a hole transport layer or an electron transport layer and a top electrode layer which are sequentially stacked; the ion liquid double interface modification layer is one or more of imidazole cations and derivatives thereof. The ion liquid double interface modification layer promotes the extraction and transmission of the interface charge of the electron (hole) transport layer / perovskite light absorption layer, optimizes the energy level arrangement; meanwhile, the ion liquid double interface modification layer promotes the preferred vertical orientation growth of the perovskite grains, improves the grain size, reduces the surface grain boundary defects and significantly inhibits the non-radiative recombination center, so that the photoelectric performance of the perovskite solar cell is greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of optoelectronic materials and technology, specifically relating to a perovskite solar cell with an ionic liquid-modified dual interface, its preparation method, and its application. Background Technology

[0002] With the increasing development of heavy industry, non-renewable resources such as coal and oil are frequently running out of resources, and energy issues are increasingly becoming a bottleneck for international economic development. In addition, the improper use of non-renewable resources is causing environmental problems to become more and more serious, posing a great threat to human survival. Environmentally friendly and renewable resources such as solar energy are receiving increasing attention from humankind, and solar cells are an important way for human society to cope with the energy depletion crisis and solve environmental pollution problems.

[0003] Perovskite solar cells have become a hot research topic in the photovoltaic field due to their excellent photoelectric properties, such as tunable bandgap, low cost, and ease of operation. In just a few years, their photoelectric conversion efficiency has exceeded 25.5%. The key factors restricting the development of inorganic electron transport materials are the complex high-temperature preparation process and the low electron mobility. Research has shown that this high-temperature sintering process is unavoidable, while the electron mobility can be coordinated and optimized through elemental doping or interface modification, thereby achieving better energy level matching with the perovskite light-absorbing layer. This promotes charge extraction and transfer at the electron transport layer / perovskite light-absorbing layer interface, greatly improving the photovoltaic performance of perovskite solar cells.

[0004] Ionic liquids such as imidazoles, piperidines, and quaternary ammonium compounds have been widely used as interface modifiers in perovskite solar cells, demonstrating excellent performance in improving the quality of electron transport layer films and passivating Pb and I vacancy defects in perovskite films. The modified perovskite solar cells show significant improvements in photoelectric performance and environmental stability. This invention is the first to demonstrate that HSO4... - Anions and BMIM + The synergistic effect of cations in promoting perovskite grain growth, optimizing energy level arrangement, and facilitating interfacial charge extraction and transfer will improve the performance and stability of devices modified with ionic liquid interfaces compared to traditional perovskite solar cell structures. Summary of the Invention

[0005] The existing technologies suffer from problems such as low electron mobility in the inorganic electron transport layer and poor energy level alignment with the perovskite photoactive layer, leading to reduced film stability and device efficiency. The purpose of this invention is to provide an ionic liquid-modified perovskite solar cell with a dual interface, its fabrication method, and its applications.

[0006] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0007] An ionic liquid-modified perovskite solar cell includes a transparent conductive substrate, an electron transport layer or a hole-electron transport layer, an ionic liquid dual-interface modification layer, a perovskite light absorption layer, a hole transport layer or an electron transport layer, and a top electrode layer stacked sequentially.

[0008] The ionic liquid dual-interface modification layer is one or more of imidazole cations and their derivatives.

[0009] As a preferred embodiment, the transparent conductive substrate is one of ITO, FTO, PEN-based flexible conductive electrode, and PET-based flexible conductive electrode.

[0010] As a preferred embodiment, the electron transport layer is one or more of ZnO, TiO2, SnO2, Al2O3, ZrO2, and fullerene derivatives, with a thickness of 1-100 nm.

[0011] As a preferred embodiment, the hole transport layer is Spiro-OMeTAD, PEDOT:PSS, PTAA, or NiO. x One or more of CuSCN and NiCo2O4, with a thickness of 1-100 nm.

[0012] As a preferred embodiment, the perovskite light-absorbing layer is ABX. m Y 3-m Crystals, wherein A is an organic cation or Cs + B is Pb 2+ X and Y are I - ,Br - Cl - The different types in the range m is 0-3.

[0013] As a preferred embodiment, the top electrode is one of Au, Ag, Pt, Al, and carbon, with a thickness of 80-100 nm.

[0014] The present invention also provides a method for fabricating a perovskite solar cell as described in any of the preceding embodiments, comprising the following steps:

[0015] (1) Clean the conductive substrate to make it a transparent conductive substrate;

[0016] (2) An electron transport layer or hole transport layer is prepared on a transparent conductive substrate;

[0017] (3) Spin-coat the ionic liquid onto the electron transport layer or hole transport layer obtained in step (2) to obtain an ionic liquid layer;

[0018] (4) Spin-coating the perovskite precursor solution onto the ionic liquid layer to obtain an ionic liquid dual-interface modification layer and a perovskite light absorption layer.

[0019] (5) Prepare a hole transport layer or an electron transport layer on top of the perovskite light absorption layer;

[0020] (6) The hole transport layer or electron transport layer obtained in step (5) is thermally deposited to obtain the top electrode, and the top electrode is also thermally deposited on a transparent conductive substrate to obtain a perovskite solar cell.

[0021] As a preferred embodiment, the ionic liquid is prepared by dispersing 1-butyl-3-methylimidazolium cation and hydrogen sulfate anion in an organic solvent according to a stoichiometric ratio, with a concentration of 0.5-20 mg / mL.

[0022] As a preferred embodiment, in step (3), the ionic liquid is stirred at a low temperature of 15-30℃ for 30-120 min before spin coating, the spin coating parameters are 500-5000 rpm and the time is 5-60 s; after spin coating, it is annealed at 60-120℃ for 10-30 min.

[0023] The present invention also provides the application of perovskite solar cells as described in any of the preceding embodiments, for use as photovoltaic solar cells.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] This invention employs a dual-interface modification method using BMIMHSO4 ionic liquid to fabricate perovskite solar cells. Specifically, it improves the quality of both the electron (hole) transport layer and the perovskite light-absorbing layer thin film. The introduction of the ionic liquid interface layer promotes the extraction and transfer of charge at the electron (hole) transport layer / perovskite light-absorbing layer interface, optimizing the energy level arrangement. Simultaneously, it promotes the preferred vertical orientation growth of perovskite grains, increasing grain size, reducing surface grain boundary defects, and significantly suppressing non-radiative recombination centers, thereby greatly enhancing the photoelectric performance of the perovskite solar cell.

[0026] This invention provides a general approach to perovskite optimization. The ionic liquid's anions and cations have great tunability, allowing researchers to optimize the ionic liquid composition or functionalize the anions and cations according to actual application requirements, thereby further improving the photoelectric conversion efficiency and environmental stability of perovskite solar cells. Attached Figure Description

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

[0028] Figure 2 These are the current-voltage characteristic curves of perovskite solar cells prepared before BMIMHSO4 interface modification (Comparative Example 1) and after interface modification (Example 1) according to the present invention.

[0029] Figure 3These are scanning electron microscope (SEM) images of BMIMHSO4 before and after interface modification in Embodiment 1 of the present invention.

[0030] Figure 4 These are X-ray diffraction patterns of BMIMHSO4 before and after interface modification in Embodiment 1 of the present invention;

[0031] Figure 5 These are the time-resolved photoluminescence spectra of BMIMHSO4 before and after interface modification in Embodiment 1 of the present invention. Detailed Implementation

[0032] The technical solution of the present invention will be further explained and illustrated below through specific embodiments.

[0033] like Figure 1 As shown, the perovskite solar cell of the present invention comprises five functional layers, which, from bottom to top, are: a lower transparent conductive substrate layer, an electron transport layer / hole transport layer, an ion liquid dual-interface modification layer, a perovskite light absorption layer, a hole transport layer / electron transport layer, and a top electrode layer. Here, " / " means "or".

[0034] Among them, the electron transport layer, the ionic liquid dual-interface modification layer, the perovskite light absorption layer, and the hole transport layer were all prepared into films using a low-temperature solution method.

[0035] The high-efficiency and stable perovskite solar cell of the present invention is prepared by dissolving 1-butyl-3-methylimidazolium cation and hydrogen sulfate anion in an organic solution according to a stoichiometric ratio, i.e., BMIMHSO4, at a certain concentration ratio, to prepare an ionic liquid dispersion.

[0036] (2) The BMIMHSO4 ionic liquid monolayer acts on the electron transport layer or hole transport layer, improving the interface quality between the electron (hole) transport layer and the perovskite light absorption layer and optimizing the energy level arrangement, thereby improving the performance of the perovskite battery.

[0037] The specific preparation process includes the following steps:

[0038] Step 1) Cleaning the conductive substrate. First, clean the transparent conductive substrate sequentially with solvents such as detergent, acetone, ethanol, and isopropanol. After cleaning, dry the substrate on a heated stage and then clean it again with ultraviolet ozone before use.

[0039] Step 2) Prepare the electron transport layer or hole transport layer. On the transparent conductive substrate cleaned in Step 1), the precursor solution prepared from the electron transport layer or hole transport layer material is uniformly coated on the surface using a spin coating method. After spin coating, the substrate is thermally annealed at a certain temperature for 20-40 minutes.

[0040] Step 3) Prepare the BMIMHSO4 ionic liquid dispersion. Dissolve the ionic liquid in an organic solvent at a certain concentration and stir for 30-120 min at room temperature (15-30℃).

[0041] Step 4) Prepare the perovskite precursor solution. Prepare a perovskite precursor solution by dispersing a certain amount of perovskite components and stir at 50-150℃ for at least 30 minutes under light-protected conditions.

[0042] Step 5) Prepare the perovskite light-absorbing layer. The prepared perovskite precursor solution is coated onto the substrate treated in Step 3) using a one-step or two-step method. For the one-step spin coating method, approximately 300 μL of anti-solvent is rapidly dropped onto the center of the substrate 10-20 seconds before the end of the process to induce rapid crystallization. For the two-step spin coating method, the perovskite precursor solution is prepared separately, and the spin coating process does not require anti-solvent. The prepared perovskite film is then placed on a heating stage to promote perovskite crystallization.

[0043] Step 6) Prepare the hole transport layer or electron transport layer. After step 5) has cooled to room temperature, the precursor solution prepared from the hole transport layer or electron transport layer material is uniformly coated on the surface of the perovskite thin film using a spin coating method.

[0044] Step 7) Finally, a metal electrode is deposited by thermal evaporation.

[0045] The transparent conductive substrate in step 1) above is an indium-doped tin dioxide (ITO) or fluorine-doped tin dioxide (FTO) conductive glass substrate, or a flexible conductive substrate such as polyethylene terephthalate (PET) based flexible conductive electrode or polyethylene naphthalate (PEN) based flexible conductive electrode. The cleaning time is 20-30 minutes for each substrate, and the ultraviolet ozone treatment time is 45 minutes.

[0046] In step 2) above, the electron transport layer is one or more of ZnO, TiO2, SnO2, Al2O3, ZrO2, or fullerene derivatives, with a thickness of 1-100 nm. The function of the electron transport layer is to transport electrons, block holes, and prevent direct contact between the electrode and the perovskite light-absorbing layer. The hole transport layer is an organic material such as Spiro-OMeTAD, PEDOT:PSS, or PTAA, or an inorganic metal compound such as NiOx, CuSCN, or NiCo2O4, with a thickness of 1-100 nm. The function of the hole transport layer is to transport holes, block electrons, and prevent direct contact between the electrode and the perovskite light-absorbing layer.

[0047] In step 3) above, BMIMHSO4 ionic liquid is dissolved in an organic solvent at a concentration of 0.5-20 mg / ml to prepare a dispersion of ionic liquid. The dispersion is prepared by spin coating and annealed at 60-120℃ for 10-30 min to obtain an ionic liquid interface layer with a thickness of 1-20 nm.

[0048] Step 4) above uses a perovskite precursor solution with a crystal structure of ABX3 containing a perovskite structure as the main component, where A is an organic cation and Cs is an organic cation. + Etc., B is Pb 2+ X is I - ,Br - or Cl - One or more of them.

[0049] In step 5) above, the perovskite light-absorbing layer is prepared by a one-step continuous spin coating method or a two-step spin coating method. The heating temperature of the heating stage is 80-170℃, and the heating time is at least 10-40 minutes.

[0050] Step 6) above: The hole transport layer is an organic material such as Spiro-OMeTAD, PEDOT:PSS, PTAA, or NiO. x Inorganic metal compounds such as CuSCN and NiCo2O4, with a thickness of 1-100 nm, are used. The hole transport layer's function is to transport holes, block electrons, and prevent direct contact between the electrode and the perovskite light-absorbing layer. Alternatively, the electron transport layer can be one or more of ZnO, TiO2, SnO2, Al2O3, ZrO2, or fullerene derivatives, with a thickness of 1-100 nm. The electron transport layer's function is to transport electrons, block holes, and prevent direct contact between the electrode and the perovskite light-absorbing layer.

[0051] The metal electrode deposited in step 7) above is one of Au, Ag, Pt, Al or carbon, with a thickness of 80-100 nm.

[0052] Example 1:

[0053] The method for fabricating a perovskite solar cell in this embodiment includes the following steps:

[0054] 1) Commercial FTO was ultrasonically cleaned in detergent, acetone and ethanol for 20 min, then further cleaned with isopropanol. The FTO glass was then spin-coated at 5000 rpm for 20 s on a spin coater, annealed at 100℃ for 5 min, and then transferred to an ultraviolet ozone cleaning machine for 45 min.

[0055] 2) Preparation of electron transport layer. Electron transport layer precursor solutions were prepared: 75 mg / ml and 150 mg / ml isopropyl titanate / ethanol solutions were prepared respectively. The cleaned FTO glass was placed on a spin coater. The 75 mg / ml isopropyl titanate / ethanol solution was spin-coated at 2000 rpm for 20 seconds and annealed at 150°C for 30 minutes. Then, the 150 mg / ml isopropyl titanate / ethanol solution was spin-coated at 4000 rpm for 20 seconds and transferred to a high-temperature heating stage. The high-temperature heating stage was heated to 450°C at a rate of 5°C / min and annealed for 40 minutes.

[0056] 3) Preparation of ionic liquid interface layer. Preparation of ionic liquid dispersion: Prepare a BMIMHSO4 / ethanol ionic liquid dispersion with a concentration of 2 mg / ml, stir at 20℃ for 60 min to fully disperse the ionic liquid, spin coat at 3000 rpm for 30 s, and then anneal on a hot plate at 100℃ for 15 min. The thickness of the obtained BMIMHSO4 interface layer is 3 nm.

[0057] 4) Preparation of perovskite thin films. Preparation of the perovskite precursor solution: PbI₂ and MAI were dissolved in a 1:1 molar ratio in a 19:1 volume ratio mixture of DMF and DMSO. The mixture was heated and stirred at 60°C for 30 min to ensure complete dissolution. The perovskite precursor solution was then continuously spin-coated onto the ionic liquid interface layer at 2000 rpm for 10 s, 4000 rpm for 25 s. 300 μL of the antisolvent ethyl acetate was added dropwise 15 s before the end of the spin-coating process. The film was then annealed at 100°C for 30 min to obtain a smooth and uniform perovskite thin film.

[0058] 5) Preparation of the hole transport layer. Preparation of the hole transport layer precursor solution: Dissolve 72.3 mg of Spiro-OMeTAD in 1 ml of chlorobenzene; dissolve LiTFSI at a concentration of 520 mg / ml in acetonitrile solution; add 17.5 μL of lithium salt solution to the Spiro-OMeTAD solution; add 28.8 μL of TBP solution to the Spiro-OMeTAD solution; stir at room temperature for 2 h to allow complete oxidation of Spiro-OMeTAD; and spin coat at 4000 rpm for 30 s.

[0059] 6) Using a vacuum evaporation apparatus, an 80nm metal electrode Ag is deposited on the hole transport layer to obtain a perovskite solar cell.

[0060] The perovskite thin film and perovskite solar cell were tested and characterized, and the results showed that:

[0061] (1) The ionic liquid in this embodiment reduces interface trap state defects and carrier recombination centers, thus acting as an interface modifier and significantly improving the photoelectric performance of perovskite solar cells. Figure 2 It can be seen that improving the open-circuit voltage, short-circuit current, and fill factor of the device in practical applications is beneficial. (BMIMHSO4 interface modification before J) sc =22.82mA / cm 2 V oc =1.05V, FF=63.20%, PCE=15.14%; after modification J sc =23.56mA / cm 2 V oc =1.09V, FF=74.21%, PCE=19.05%. This improves the photoelectric response performance of perovskite solar cells.

[0062] (2) The ionic liquid in this embodiment promotes the grain growth of perovskite and rationally controls the morphology of the perovskite film. Figure 3 It is evident that reducing grain boundaries and shallow surface defects results in a smooth perovskite film, ultimately improving the photoelectric performance of perovskite solar cells.

[0063] (3) This embodiment exhibits excellent interface passivation and Pb and I ion vacancy passivation effects under the synergistic catalytic action of ionic liquids. Figure 4 It can be seen that the PbI2 peak was significantly suppressed, while the 110 peak intensity was greatly enhanced, indicating that the BMIMHSO4 interface modification is more conducive to the vertical crystallization growth of perovskite, and the crystal phase stability of perovskite is improved.

[0064] (4) The ionic liquid in this embodiment promotes the transfer of charge from the perovskite layer to the electron transport layer, and the charge carriers are greatly quenched. Figure 5 As can be seen, the modified decay lifetime is significantly reduced, indicating that the interface charge is greatly quenched, and the charge extraction and transport are faster, ultimately improving the photoelectric performance of the perovskite solar cell.

[0065] In summary, the ionic liquid in this embodiment is composed of 1-butyl-3-methylimidazolium (BMIM). + ) cations and hydrogen sulfate (HSO4) - The anionic composition acts on the electron (hole) transport layer / perovskite light absorption layer interface, optimizing the energy level arrangement of the electron (hole) transport layer, promoting the extraction and transport of interface charges / holes, and reducing interface carrier recombination centers. Simultaneously, it passivates Pb and I vacancy defects in the perovskite film, promotes vertical crystallization of perovskite grains, and improves its photoelectric performance and environmental stability, thereby enhancing the performance of perovskite solar cells. This process is simple, highly reproducible, can be prepared in the environment, and the ionic composition can be optimized according to actual application requirements to maximize the photoelectric performance of the perovskite film and achieve excellent device performance.

[0066] Example 2:

[0067] The method for fabricating a perovskite solar cell in this embodiment includes the following steps:

[0068] 1) Commercial ITO was ultrasonically cleaned in detergent, acetone and ethanol for 20 min, then further cleaned with isopropanol. The ITO glass was then spin-coated at 5000 rpm for 20 s on a spin coater, annealed at 100℃ for 5 min, and then transferred to an ultraviolet ozone cleaning machine for irradiation for 45 min.

[0069] 2) Preparation of the electron transport layer. Prepare the electron transport layer precursor solution: Prepare a SnO2 colloid / deionized water dilution solution (volume ratio 1:6, mass fraction 2.14 wt%), and then spin-coat it onto pre-cleaned ITO glass at 4000 rpm for 30 s. After spin-coating, heat-anneal at 150℃ for 30 min. After the glass substrate cools to room temperature, place the ITO glass substrate again in ultraviolet ozone for 15 min.

[0070] 3) Preparation of the ionic liquid interface layer. An ionic liquid dispersion was prepared. A BMIMHSO4 / ethanol ionic liquid dispersion with a concentration of 8 mg / ml was prepared, stirred at 20°C for 60 min to ensure complete dispersion of the ionic liquid, spin-coated at 3000 rpm for 30 s, and then annealed on a hot plate at 80°C for 30 min. The resulting BMIMHSO4 interface layer had a thickness of 7 nm.

[0071] 4) Preparation of perovskite thin films. Preparation of the perovskite precursor solution: MAX and PbX2 (where X is one of I, Br, or Cl) were dissolved in a 1:1 molar ratio in a 4:1 volume ratio mixture of DMF and DMSO. The mixture was heated and stirred at 60°C for 30 min to ensure complete dissolution. The perovskite precursor solution was then spin-coated onto the ionic liquid interface layer in two consecutive steps at 2000 rpm for 10 s and 4000 rpm for 25 s. 300 μL of the antisolvent ethyl acetate was added dropwise 12 s before the end of the spin-coating process. The film was then annealed at 100°C for 30 min to obtain a smooth and uniform perovskite thin film.

[0072] 5) Preparation of the hole transport layer. Prepare the hole transport layer precursor solution: Dissolve 65 mg of Spiro-OMeTAD in 1 ml of chlorobenzene; dissolve LiTFSI at a concentration of 170 mg / ml in acetonitrile solution; dissolve FK209 at a concentration of 150 mg / ml in acetonitrile solution; add 70 μL of lithium salt solution to the Spiro-OMeTAD solution; add 50 μL of FK209 solution to the Spiro-OMeTAD solution; add 20 μL of TBP solution to the Spiro-OMeTAD solution; stir at room temperature for 2 h to allow complete oxidation of Spiro-OMeTAD; and spin coat at 4000 rpm for 30 s.

[0073] 6) Using a vacuum evaporation apparatus, a 90nm metal electrode Ag is deposited on the hole transport layer to obtain a perovskite solar cell.

[0074] The perovskite solar cell with BMIMHSO4-modified dual interface was characterized by relevant tests, and the results were similar to those in Example 1. Compared with the control cell, the perovskite solar cell with BMIMHSO4-modified dual interface exhibits higher energy conversion efficiency and charge transfer efficiency.

[0075] Example 3:

[0076] The method for fabricating a perovskite solar cell in this embodiment includes the following steps:

[0077] 1) Cleaning the electrode. Commercial ITO was ultrasonically cleaned in detergent, acetone and ethanol for 20 min, and then further cleaned with isopropanol. The ITO glass was spin-coated at 5000 rpm for 20 s on a spin coater, annealed at 100℃ for 5 min, and then transferred to a UV ozone cleaning machine for 45 min.

[0078] 2) Preparation of the hole transport layer. First, a hole transport layer precursor solution was prepared by dissolving 290.8 mg of nickel nitrate hexahydrate in 10 mL of 2-methoxyethanol and stirring on a hot plate at 50 °C for 1 h. Then, 100 μL of acetylacetone was added, and stirring was continued overnight at room temperature to obtain a pale blue transparent solution. A spin-coating step was then performed at 3000 rpm for 45 s. After spin-coating, the solution was heat-treated on a hot plate at 150 °C for 60 min to obtain NiO. x Hole transport layer.

[0079] 3) Preparation of the ionic liquid interface layer. First, an ionic liquid dispersion was prepared. A 1-ethyl-3-methylimidazolium hydrogen sulfate [EMIMHSO4] / isopropanol solution with a concentration of 5 mg / ml was prepared and stirred at 20°C for 45 min to ensure sufficient dispersion of the ionic liquid. The solution was then spin-coated at 5000 rpm for 30 s and annealed on a hot plate at 80°C for 40 min. The resulting EMIMHSO4 interface layer had a thickness of 4 nm.

[0080] 4) Preparation of perovskite thin films. Preparation of perovskite precursor solutions: Lead halide (PbX2, where X is one of I, Br, or Cl), formamidinium hydrohalide (FAX), lead halide (PbY2, where Y is one of I, Br, or Cl, and is different from X), and methylammonium halide (MAY) were used as perovskite precursors with molar concentrations of 1.2 M, 1.1 M, 0.25 M, and 0.25 M, respectively. Cesium iodide (CsI) was dissolved in 1.8 M dimethyl sulfoxide (DMSO) stock solution and introduced into the precursor solution. CsI was then prepared in a mixed solvent of anhydrous DMF and anhydrous DMSO (volume ratio 4:1). 0.1 (FA a MA 1-a ) 0.9 Pb(X b Y 1-b 3 (a and b are constants greater than 0 and less than 1) Perovskite precursor solution. The solution was heated and stirred at 60℃ for 30 min to fully dissolve the perovskite precursor. Then, the perovskite precursor solution was continuously spin-coated onto the ionic liquid interface layer in one step at 2500 rpm for 10 s, 5000 rpm for 30 s. 300 μL of the antisolvent ethyl acetate was added dropwise 15 s before the end of the program, and then annealed at 150℃ for 30 min to obtain a smooth and uniform perovskite film.

[0081] 5) Preparation of the electron transport layer. An electron transport layer precursor solution was prepared, along with a 20 mg / ml PCBM / chlorobenzene solution. The mixture was stirred at 60°C for at least 24 hours and filtered before use. Additionally, a 0.5 mg / ml BCP / IPA solution was prepared. The electron transport layer material was prepared by spin-coating the PCBM solution at 2000 rpm for 30 seconds, followed by spin-coating the BCP solution at 5000 rpm for 30 seconds.

[0082] 6) Using a vacuum evaporation apparatus, a 100 nm metal electrode Ag is deposited on the electron transport layer to obtain a perovskite solar cell.

[0083] The perovskite solar cell with BMIMHSO4-modified dual interface was characterized by relevant tests, and the results were similar to those in Example 1. Compared with the control cell, the perovskite solar cell with BMIMHSO4-modified dual interface exhibits higher energy conversion efficiency and charge transfer efficiency.

[0084] Example 4:

[0085] The method for fabricating a perovskite solar cell in this embodiment includes the following steps:

[0086] 1) The commercial PET conductive flexible substrate was ultrasonically cleaned in detergent, acetone and ethanol for 20 min, and then further cleaned with isopropanol. The ITO glass was spin-coated at 5000 rpm for 20 s on a spin coater, annealed at 100℃ for 5 min, and then transferred to an ultraviolet ozone cleaning machine for 45 min.

[0087] 2) Preparation of the electron transport layer. First, prepare the electron transport layer precursor solution. Prepare a SnO2 colloid / deionized water dilution solution (2.14 wt%) with a volume ratio of 1:6, and then spin-coat it onto a pre-cleaned ITO glass substrate at 4000 rpm for 30 s. After spin-coating, heat-anneal at 150 °C for 30 min. After the glass substrate cools to room temperature, treat the ITO glass substrate again in ultraviolet ozone for 15 min.

[0088] 3) Preparation of the ionic liquid interface layer. Preparation of the ionic liquid dispersion: Prepare a 1 mg / ml 1-butyl-2,3-dimethylimidazolium bromide [BMMIMBr] / acetonitrile solution ionic liquid dispersion. Stir at 25°C for 60 min to ensure thorough dispersion of the ionic liquid. Spin-coat at 2000 rpm for 30 s, then anneal on a hot plate at 100°C for 30 min. The resulting BMMIMBr interface layer has a thickness of 2 nm.

[0089] 4) Preparation of the perovskite layer. Prepare the perovskite precursor solution: Dissolve MAX and PbX2 (where X is one of I, Br, or Cl) in a 1:1 molar ratio in a 9:1 volume ratio mixture of DMF and DMSO. Heat and stir at 60°C for 30 min to ensure complete dissolution. Then, spin-coat the perovskite precursor solution onto the ionic liquid interface layer in two consecutive steps at 2500 rpm for 10 s and 4500 rpm for 30 s. Add 300 μL of the antisolvent ethyl acetate 12 s before the end of the program, and then anneal at 100°C for 30 min to obtain a smooth and uniform perovskite film.

[0090] 5) Preparation of the hole transport layer. Preparation of the hole transport layer precursor solution: Dissolve 70 mg of Spiro-OMeTAD in 1 ml of chlorobenzene; dissolve LiTFSI at a concentration of 520 mg / ml in acetonitrile solution; add 17 μL of lithium salt solution to the Spiro-OMeTAD solution; add 28 μL of TBP solution to the Spiro-OMeTAD solution; stir at room temperature for 1.5 h to allow complete oxidation of Spiro-OMeTAD; and spin coat at 3000 rpm for 30 s.

[0091] 6) Using a vacuum evaporation apparatus, an 85nm metal electrode Ag is deposited on the electron transport layer to obtain a perovskite solar cell.

[0092] The perovskite solar cell with BMIMHSO4-modified dual interface was characterized by relevant tests, and the results were similar to those in Example 1. Compared with the control cell, the perovskite solar cell with BMIMHSO4-modified dual interface exhibits higher energy conversion efficiency and charge transfer efficiency.

[0093] Comparative Example 1:

[0094] The fabrication method of this comparative perovskite solar cell includes the following steps:

[0095] 1) Commercial FTO was ultrasonically cleaned in detergent, acetone and ethanol for 20 min, then further cleaned with isopropanol. The FTO glass was then spin-coated at 5000 rpm for 20 s on a spin coater, annealed at 100℃ for 5 min, and then transferred to an ultraviolet ozone cleaning machine for 45 min.

[0096] 2) Preparation of electron transport layer. Electron transport layer precursor solutions were prepared: 75 mg / ml and 150 mg / ml isopropyl titanate / ethanol solutions were prepared respectively. The cleaned FTO glass was placed on a spin coater. The 75 mg / ml isopropyl titanate / ethanol solution was spin-coated at 2000 rpm for 20 seconds and annealed at 150°C for 30 minutes. Then, the 150 mg / ml isopropyl titanate / ethanol solution was spin-coated at 4000 rpm for 20 seconds and transferred to a high-temperature heating stage. The high-temperature heating stage was heated to 450°C at a rate of 5°C / min and annealed for 40 minutes.

[0097] 3) Preparation of the perovskite layer. Preparation of the perovskite precursor solution: PbI₂ and MAI were dissolved in a 1:1 molar ratio in a 19:1 volume ratio mixture of DMF and DMSO. The mixture was heated and stirred at 60°C for 30 min to ensure complete dissolution. The perovskite precursor solution was then spin-coated onto the ion-liquid-modified electron transport layer in two consecutive steps at 2000 rpm for 10 s and 4000 rpm for 25 s. At 15 s in the second step, 300 μL of the antisolvent ethyl acetate was added dropwise. The mixture was then annealed at 100°C for 30 min to obtain a smooth and uniform perovskite film.

[0098] 4) Preparation of the hole transport layer. Preparation of the hole transport layer precursor solution: Dissolve 72.3 mg of Spiro-OMeTAD in 1 ml of chlorobenzene; dissolve LiTFSI at a concentration of 520 mg / ml in acetonitrile solution; add 17.5 μL of lithium salt solution to the Spiro-OMeTAD solution; add 28.8 μL of TBP solution to the Spiro-OMeTAD solution; stir at room temperature for 2 h to allow complete oxidation of Spiro-OMeTAD; and spin coat at 4000 rpm for 30 s.

[0099] 5) Using a vacuum evaporation apparatus, an 80nm metal electrode Ag is deposited on the hole transport layer to obtain a perovskite solar cell.

[0100] The final experimental results show that, compared with the perovskite with BMIMHSO4 modified dual interface in Example 1, the perovskite in this comparative example has a smaller crystal size and a weaker 110 peak intensity. The photoelectric conversion efficiency, interface charge extraction and transport of the constructed battery device are much lower than those of the BMIMHSO4 ionic liquid modified dual interface.

[0101] The above further demonstrates the effectiveness of the present invention. After modifying the perovskite with BMIMHSO4 interface, the extraction and transport of charge at the electron transport layer / perovskite layer interface are improved, the preferential vertical orientation growth of perovskite grains is promoted, the quality of the perovskite film is improved, and thus the efficiency and stability of perovskite solar cells are enhanced.

[0102] The perovskite solar cells described in the above embodiments can be applied to photovoltaic solar cells.

[0103] Given that there are numerous embodiments of the present invention and a large amount of experimental data for each embodiment, it is not appropriate to list and describe them one by one here. However, the content to be verified and the final conclusions obtained in each embodiment are similar.

[0104] The above description is merely a detailed explanation of preferred embodiments and principles of the present invention. For those skilled in the art, there may be changes in specific implementation methods based on the ideas provided by the present invention, and these changes should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a perovskite solar cell with an ionic liquid-modified dual interface, characterized in that, Includes the following steps: 1) Commercial FTO was ultrasonically cleaned in detergent, acetone and ethanol for 20 min, then further cleaned with isopropanol. The FTO glass was spin-coated at 5000 rpm for 20 s on a spin coater, annealed at 100 ℃ for 5 min, and then transferred to an ultraviolet ozone cleaning machine for 45 min. 2) Fabrication of the electron transport layer; Preparation of electron transport layer precursor solutions: Prepare isopropyl titanate / ethanol solutions with concentrations of 75 mg / ml and 150 mg / ml respectively. Place the cleaned FTO glass on a spin coater. Spin coat the 75 mg / ml isopropyl titanate / ethanol solution at 2000 rpm for 20 s and anneal at 150 °C for 30 min. Then spin coat the 150 mg / ml isopropyl titanate / ethanol solution at 4000 rpm for 20 s and transfer it to a high-temperature heating stage. The high-temperature heating stage is heated to 450 °C at a rate of 5 °C / min and annealed for 40 min. 3) Preparation of the ionic liquid interface layer; Preparation of ionic liquid dispersion: Prepare a BMIMHSO4 / ethanol ionic liquid dispersion with a concentration of 2 mg / ml. Stir at 20 °C for 60 min to fully disperse the ionic liquid. Spin coat at 3000 rpm for 30 s and then anneal on a hot plate at 100 °C for 15 min. The resulting BMIMHSO4 interface layer has a thickness of 3 nm. 4) Preparation of perovskite thin films; Preparation of perovskite precursor solution: PbI2 and MAI were dissolved in a mixture of DMF and DMSO with a volume ratio of 19:1 at a molar ratio of 1:

1. The mixture was heated and stirred at 60 °C for 30 min to ensure complete dissolution. The perovskite precursor solution was then continuously spin-coated onto the ionic liquid interface layer at 2000 rpm for 10 s, 4000 rpm for 25 s. 300 µL of the antisolvent ethyl acetate was added dropwise 15 s before the end of the program. The mixture was then annealed on a hot plate at 100 °C for 30 min to obtain a smooth and uniform perovskite film. 5) Prepare the hole transport layer; Preparation of hole transport layer precursor solution: Dissolve 72.3 mg Spiro-OMeTAD in 1 ml of chlorobenzene, dissolve LiTFSI in acetonitrile solution at a concentration of 520 mg / ml, add 17.5 μL of lithium salt solution to Spiro-OMeTAD solution, add 28.8 μL of TBP solution to Spiro-OMeTAD solution, stir at room temperature for 2 h to allow complete oxidation of Spiro-OMeTAD, and spin coat at 4000 rpm for 30 s; 6) Using a vacuum evaporation apparatus, an 80 nm metal electrode Ag was deposited on the hole transport layer to obtain a perovskite solar cell.

2. The application of the perovskite solar cell prepared by the method described in claim 1, characterized in that, Used as a photovoltaic solar cell.

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