Perovskite solar cell and preparation method thereof

Abstract

The invention discloses a perovskite solar cell and a preparation method thereof, and relates to the field of solar cells. The method comprises the steps that a substrate used for preparing the perovskite solar cell is provided, a hole transport layer is formed on the surface of the substrate, and a self-assembled monomolecular layer is formed on the hole transport layer; the preparation method comprises the following steps: preparing a perovskite precursor solution, and adding bis-(triphenylphosphino) ammonium chloride into the perovskite precursor solution; spin-coating the surface of the self-assembled monomolecular layer with the perovskite precursor solution, and inducing perovskite crystallization and film formation through an anti-solvent to form a perovskite layer; preparing a passivation layer on the perovskite layer; preparing an electron transport layer on the passivation layer; and preparing a metal electrode on the electron transport layer to obtain the perovskite solar cell. The invention aims to reduce the defects introduced in the process of preparing the perovskite solar cell by a solution and solve the problems of low efficiency and poor stability of the prepared perovskite solar cell.

Description

Technical Field

[0001] The present application belongs to the field of solar cells, and specifically relates to a perovskite solar cell and a method for preparing the same. Background Art

[0002] In recent years, perovskite solar cells have developed rapidly. Among them, inverted perovskite solar cells have the advantages of simple preparation process, small hysteresis effect, high compatibility with flexible substrates or laminated structures, and have broad application prospects.

[0003] However, when preparing the perovskite layer, the commonly used solution preparation method easily introduces body defects or surface defects. These defects hinder the preparation of high-efficiency perovskite solar cells, affect the stability and efficiency of perovskite solar cells, and make it difficult to achieve large-scale commercial preparation of perovskite solar cells. Summary of the invention

[0004] The present application provides a method for preparing a perovskite solar cell and an organic solar cell, aiming to passivate defects in a perovskite layer and solve the problems of poor stability and low efficiency of the prepared perovskite solar cell.

[0005] In a first aspect, the present application provides a method for preparing a perovskite solar cell, the method comprising:

[0006] A substrate for preparing a perovskite solar cell is provided, wherein a hole transport layer is formed on the surface of the substrate, and a self-assembled monomolecular layer is formed on the hole transport layer;

[0007] preparing a perovskite precursor solution, and adding bis-(triphenylphosphorane)ammonium chloride into the perovskite precursor solution;

[0008] The perovskite precursor solution is spin-coated onto the surface of the self-assembled monolayer, and the perovskite is induced to crystallize into a film by an anti-solvent to form a perovskite layer;

[0009] A passivation layer is prepared on the perovskite layer, and an electron transport layer is prepared on the passivation layer;

[0010] A metal electrode is prepared on the electron transport layer to obtain a perovskite solar cell.

[0011] In a second aspect, the present application provides a perovskite solar cell, which is prepared by using the above-mentioned method for preparing a perovskite solar cell.

[0012] The present application provides a method for preparing a perovskite solar cell and a perovskite solar cell. By adding bis-(triphenylphosphine) ammonium chloride (PPNC l) to a perovskite precursor solution, the crystallization time during the perovskite spin coating process is effectively prolonged, so that the perovskite film has a better crystallization tendency, and the impurities at the perovskite grain boundaries are reduced, so that the roughness of the perovskite film is reduced, the impurities are reduced, the grains are uniform and larger, and the defects are reduced, thereby improving the efficiency and stability of the perovskite solar cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0014] Figure 1 It is a flowchart of the steps of a method for preparing a perovskite solar cell provided in the present application;

[0015] Figure 2 This is a schematic diagram of the structure of a perovskite solar cell provided in an embodiment of the present application;

[0016] Figure 3a is the crystallization time diagram of the spin coating process of the perovskite film prepared without adding PPNC l;

[0017] Figure 3b is the crystallization time diagram of the annealing process of the perovskite film prepared without adding PPNC l;

[0018] Figure 3c is a crystallization time diagram of the spin coating process of the perovskite film in the embodiment of the present application;

[0019] Figure 3d is a crystallization time diagram of the perovskite film annealing process in an embodiment of the present application;

[0020] Figure 4a is an X-ray diffraction spectrum of the perovskite film prepared in the embodiment of the present application and without adding PPNC l at 10-45°;

[0021] Figure 4b is an X-ray diffraction spectrum of the perovskite film prepared in the embodiment of the present application and without adding PPNC l at 12-15°;

[0022] Figure 5a is a scanning electron microscopy image of a perovskite film prepared without adding PPNC l;

[0023] Figure 5bis a scanning electron microscope image of a perovskite film in an embodiment of the present application;

[0024] Figure 6 is a grain size distribution diagram of the perovskite film prepared in the embodiment of the present application and without adding PPNC l;

[0025] Figure 7a is the atomic force microscopy morphology of the perovskite film prepared without adding PPNC l;

[0026] Figure 7b is an atomic force microscope morphology image of the perovskite film in the embodiment of the present application;

[0027] Figure 8 Steady-state photoluminescence spectra of the perovskite film prepared in the embodiment of the present application and without adding PPNC l;

[0028] Fig. 9 is a time-resolved photoluminescence spectrum of the perovskite film prepared in the embodiment of the present application and without adding PPNC l;

[0029] Fig.10 is an open circuit voltage-light intensity graph of the perovskite solar cell prepared in the embodiment of the present application and without adding PPNC l;

[0030] Fig.11 is a Mott-Schottky curve diagram of the perovskite solar cell prepared in the embodiment of the present application and without adding PPNC l;

[0031] Fig.12 It is the electrochemical impedance spectrum and fitting curve equivalent circuit diagram of the perovskite solar cell prepared in the embodiment of the present application and without adding PPNC l;

[0032] Fig.13 is a graph showing the current density and voltage characteristics of the perovskite solar cell prepared in the embodiment of the present application and without adding PPNC l;

[0033] Fig.14 is an integral curve of the external quantum rate of the perovskite solar cell prepared in the embodiment of the present application and without adding PPNC l;

[0034] Fig.15 It is a normalized cell efficiency diagram of the perovskite solar cell prepared in the embodiment of the present application and without adding PPNC l. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0036] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0037] It should also be understood that the terms used in this application specification are only for the purpose of describing specific embodiments and are not intended to limit the application. As used in this application specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0038] It should be further understood that the term “and / or” used in the specification and appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0039] In conjunction with the accompanying drawings, some embodiments of the present application are described in detail below. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0040] In recent years, perovskite solar cells have developed rapidly. Among them, inverted perovskite solar cells have the advantages of simple preparation process, small hysteresis effect, high compatibility with flexible substrates or laminated structures, and have broad application prospects.

[0041] However, when preparing the perovskite layer, the commonly used solution preparation method easily introduces body defects or surface defects. These defects hinder the preparation of high-efficiency perovskite solar cells, affect the stability and efficiency of perovskite solar cells, and make it difficult to achieve large-scale commercial preparation of perovskite solar cells.

[0042] To solve the above problems, see Figure 1 , Figure 1 is a flowchart of the steps of a method for preparing a perovskite solar cell provided in the present application, such as Figure 1 As shown, the preparation method specifically includes: step S101 to step S105.

[0043] S101. Provide a substrate for preparing a perovskite solar cell, wherein a hole transport layer is formed on the surface of the substrate, and a self-assembled monolayer is formed on the hole transport layer.

[0044] The substrate is composed of a transparent conductive substrate, a hole transport layer, and a self-assembled monolayer. The transparent conductive substrate can be fluorine-doped tin oxide (FTO) conductive glass, indium tin oxide (ITO) conductive glass, or a flexible ITO conductive substrate; the hole transport layer material can be one of an inorganic p-type semiconductor material, an organic metal material, a polymer material, and an organic small molecule material; and the self-assembled monolayer material can be [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphoric acid (Me-4PACz) or [4-(3,6-dimethyl-7H-carbazole-9-yl)phenyl]phosphoric acid.

[0045] In the embodiments of the present application, ITO conductive glass is used as a transparent conductive substrate, the inorganic p-type semiconductor material nickel oxide (NiOx) is used as a hole transport layer material, Me-4PACz is used as a self-assembled single molecule material, and anhydrous ethanol is used as an organic solvent for a self-assembled single molecule solution.

[0046] In some embodiments, the present application also provides a method for preparing a substrate, specifically including: providing a transparent conductive substrate, cleaning the transparent conductive substrate, and plasma-treating the cleaned transparent conductive substrate; depositing a hole transport layer on the surface of the transparent conductive substrate after plasma treatment; depositing a self-assembled monolayer on the hole transport layer to obtain a substrate for preparing a perovskite solar cell.

[0047] Specifically, ITO conductive glass is selected as a transparent conductive substrate, and the ITO conductive glass is scrubbed with a cotton swab dipped in soapy water and rinsed with deionized water, and then the ITO conductive glass is ultrasonically cleaned in deionized water and ethanol for 20-40 minutes, and then the cleaned ITO conductive glass is placed in 70-90°C for vacuum drying for 6-18 hours, and then the surface of the ITO conductive glass is plasma treated for 2-4 minutes, and the plasma treatment time achieves the purpose of enhancing the surface wettability. A hole transport layer is deposited on the surface of the ITO conductive glass after the plasma treatment; a self-assembled monolayer is deposited on the hole transport layer to obtain a substrate for preparing a perovskite solar cell.

[0048] In some embodiments, the specific process of depositing a hole transport layer on the surface of a transparent conductive substrate treated with plasma includes: dissolving a hole transport layer material in deionized water to obtain a hole transport layer solution, spin coating the hole transport layer solution on the transparent conductive substrate treated with plasma, and performing thermal annealing to deposit a hole transport layer on the surface of the transparent conductive substrate treated with plasma.

[0049] Specifically, NiOx is selected as the hole transport layer material, and NiOx is ultrasonically dissolved in deionized water to obtain a NiOx dispersion, which is a hole transport layer solution, with a concentration of 10-20 mg / mL and an ultrasonic time of 5-15 min, and the ultrasonic time achieves the purpose of completely dissolving NiOx in deionized water. 60-100 μL of the NiOx dispersion is spin-coated on an ITO conductive glass at a spin-coating speed of 1500-2500 rpm for 20-40 s, and then transferred to a hot stage at 130-170° C. for annealing for 10-30 min to form a NiOx film, thereby preparing a NiOx hole transport layer.

[0050] In some embodiments, a specific process for depositing a self-assembled monolayer on a hole transport layer to obtain a substrate for preparing a perovskite solar cell includes: adding a self-assembled monomolecular material to an organic solvent, stirring to obtain a self-assembled monomolecular solution; spin coating the self-assembled monomolecular solution on the hole transport layer, thermally annealing to form a self-assembled monolayer on the hole transport layer, and obtaining a substrate for preparing a perovskite solar cell.

[0051] Specifically, Me-4PACz is selected as a self-assembled monomolecular material, and anhydrous ethanol is used as a solvent for the self-assembled monolayer. Me-4PACz is added to anhydrous ethanol and stirred to dissolve to obtain a Me-4PACz solution with a concentration of 0.4-0.6 mg / mL and a stirring time of 10-14 hours. The stirring time achieves the purpose of completely dissolving Me-4PACz in anhydrous ethanol. 80-120 μL of the Me-4PACz solution is spin-coated on the surface of the NiOx film at a spin-coating speed of 3000-5000 rpm and a spin-coating time of 20-40 seconds; then the solution is transferred to a hot stage for annealing at an annealing temperature of 80-100° C. and an annealing time of 5-15 minutes. The annealing treatment achieves the effect of anchoring Me-4PACz on the surface of the NiOx film, forming a Me-4PACz self-assembled monolayer, and obtaining a substrate for preparing a perovskite solar cell.

[0052] S102, preparing a perovskite precursor solution, and adding bis-(triphenylphosphorane)ammonium chloride into the perovskite precursor solution.

[0053] Specifically, a perovskite precursor solution can be provided, and the perovskite precursor solution is used to form a perovskite film to prepare a perovskite layer. In the embodiments of the present application, bis-(triphenylphosphorane)ammonium chloride is added to the perovskite precursor solution, that is, it can be understood that the perovskite precursor solution includes bis-(triphenylphosphorane)ammonium chloride.

[0054] In some embodiments, the present application also provides a method for preparing a perovskite precursor solution, comprising: adding a solute to a mixed solvent of dimethyl sulfoxide (DMSO) and N,N-dimethylformamide (DMF), stirring the mixture to dissolve the solute in the solvent, and preparing a mixed solution; adding methylamine hydrochloric acid (MAC l) to the mixed solution, stirring the mixture; adding bis-(triphenylphosphorane)ammonium chloride (PPNC l) to the mixed solution to which MAC l is added, stirring the mixture to completely dissolve PPNCl in the mixed solution; and aging the mixed solution to which PPNC l is added to obtain a perovskite precursor solution.

[0055] The solutes include lead iodide (Pb I2), formamidine hydroiodide (FAI), methylammonium iodide (MAI), and cesium iodide (Cs I). The chemical structure of bis-(triphenylphosphorane)ammonium chloride (PPNC l) is as follows:

[0056]

[0057] Specifically, Pb I2, FAI, MAI, and Cs I are added to a mixed solvent of DMSO and DMF, and stirred under light shielding at room temperature to dissolve the solute in the solvent to prepare a mixed solution, wherein the molar ratio of Pb I2, FAI, MAI, and Cs I in the mixed solution is 1.65:1.275:0.15:0.075, the volume ratio of DMSO and DMF is 1:4, and the stirring time is 8-16 hours. Subsequently, MAC I is added to the mixed solution and stirred for 1-3 hours, and the concentration of MAC I in the mixed solution is 11-13 mol%. Thereafter, PPNC I is added to the mixed solution with MAC I added and stirred, and the stirring process achieves the purpose of completely dissolving PPNC I in the mixed solution, and the concentration of PPNC I in the mixed solution is 0.5-1.5 mmol%. Finally, the mixed solution added with PPNC l was aged at room temperature for 2-6 hours to prepare a perovskite precursor solution with a final concentration of 1.5M.

[0058] S103, spin-coating the perovskite precursor solution onto the surface of the self-assembled monolayer, and inducing the perovskite to crystallize into a film through an anti-solvent to form a perovskite layer.

[0059] The perovskite precursor solution refers to a solution used to form a perovskite film to prepare a perovskite layer. The perovskite precursor solution in the embodiment of the present application is added with PPNC 1, that is, it can be understood that the perovskite precursor solution includes PPNC 1. The process of spin coating the perovskite precursor solution can adopt a one-step spin coating method or a two-step spin coating method. The anti-solvent can be one of chlorobenzene, ethyl acetate, and ether.

[0060] In the embodiments of the present application, the spin coating process adopts a two-step spin coating method, and chlorobenzene is selected as the anti-solvent.

[0061] In some embodiments, the spin coating process adopts a two-step method, that is, the perovskite precursor solution is spin-coated onto the surface of the self-assembled monolayer using a two-step spin coating method. The perovskite precursor solution is first spin-coated onto the surface of the self-assembled monolayer, which is called the first spin coating, and then the perovskite precursor solution is spin-coated onto the surface of the self-assembled monolayer again, which is called the second spin coating; the anti-solvent is added 5-8 seconds before the end of the second spin coating; and after the second spin coating, thermal annealing is performed to allow the perovskite to crystallize into a film to obtain a perovskite layer (Perovskite).

[0062] Among them, the spin coating speed and spin coating time of the first spin coating in the two-step spin coating method are both smaller than the spin coating speed and spin coating time of the second spin coating, so a perovskite layer with better effect can be obtained.

[0063] Specifically, 80-120 μL of the perovskite precursor solution is spin-coated onto the surface of the Me-4PACz self-assembled monolayer using a two-step spin coating method, 140-180 μL of chlorobenzene is quickly added 5-8 seconds before the second spin coating ends, and after the second spin coating ends, it is quickly transferred to a hot stage for annealing at a temperature of 100-120°C for 10-30 minutes, so that the perovskite crystallizes into a film to obtain a perovskite layer. In the two-step spin coating method, the first stage spin coating speed is 800-1200 rpm, the spin coating time is 5-15 seconds; the second stage spin coating speed is 4000-6000 rpm, and the spin coating time is 30-50 seconds.

[0064] S104, preparing a passivation layer on the perovskite layer, and preparing an electron transport layer on the passivation layer.

[0065] Among them, the method for preparing the passivation layer and the electron transport layer can be a spin coating method, a slit coating method, a thermal evaporation method, a magnetron sputtering method, and an atomic layer deposition method; the material for preparing the passivation layer can be an ammonium salt material, a Lewis acid, and a Lewis base; the material for preparing the electron transport layer can be one or more of fullerene, a fullerene derivative, and 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline.

[0066] In the examples of the present application, the passivation layer is prepared using an ammonium salt material, and the electron transport layer is prepared using a fullerene derivative and 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline.

[0067] In some embodiments, the present application also provides a method for preparing a passivation layer, comprising: adding an ammonium salt material to an organic solvent to dissolve the ammonium salt material in the organic solvent to obtain an ammonium salt material solution; cooling the substrate with a perovskite layer formed on the surface to room temperature; spin coating the ammonium salt material solution onto the perovskite layer, wherein the spin coating process achieves the purpose of passivating the surface defects of the perovskite film, and forming a passivation layer through thermal annealing.

[0068] Wherein, the ammonium salt material may be phenethylammonium bromide (PEABr), and the organic solvent may be isopropanol.

[0069] Specifically, PEABr is selected as the ammonium salt material and isopropanol is selected as the organic solvent, PEABr is added to isopropanol, the organic ammonium salt material is dissolved in the organic solvent, and a PEABr solution is obtained with a concentration of 0.5-1.5 mg / mL; the substrate with a perovskite layer formed on the surface is cooled to room temperature; the PEABr solution is added to the surface of the perovskite layer to passivate surface defects, the added volume of the PEABr solution is 60-100 μL, the spin coating speed is 3200-4800 rpm, the spin coating time is 20-40 s, and then it is immediately transferred to a hot stage, the annealing temperature is 80-120° C., and the annealing time is 5-15 min to form a passivation layer.

[0070] In some embodiments, the present application also provides a method for preparing an electron transport layer, including: adding an electron transport layer material to an organic solvent, stirring the organic solvent to obtain an electron transport layer solution; adding a hole blocking layer material to an organic solvent, stirring the organic solvent to obtain a hole blocking layer solution; first spin coating the electron transport layer solution on the passivation layer, and then spin coating the hole blocking layer solution, and waiting for the organic solvent to evaporate to form an electron transport layer.

[0071] Among them, the electron transport layer material can be a fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester (PCBM); the hole blocking layer material can be 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP), and the organic solvent can be chlorobenzene and isopropyl alcohol.

[0072] Specifically, PCBM is selected as the electron transport layer material, chlorobenzene is selected as the organic solvent of the electron transport layer solution, PCBM is added to chlorobenzene, and the chlorobenzene is stirred to obtain a PCBM solution with a concentration of 10-30 mg / mL and a stirring time of 8-16 hours; BCP is selected as the hole blocking layer material, isopropanol is selected as the organic solvent of the hole blocking layer solution, BCP is added to isopropanol, and the isopropanol is stirred to obtain a BCP solution with a concentration of 0.2-0.8 mg / mL and a stirring time of 8-16 hours; the PCBM solution is first spin-coated on the passivation layer, and then the BCP solution is spin-coated, and the isopropanol is volatilized to form an electron transport layer, the spin-coating speed of the electron transport layer material solution is 1600-2400 rpm, the spin-coating speed of the hole blocking material solution is 3200-4800 rpm, and the spin-coating time is 20-40s.

[0073] S105. Prepare a metal electrode on the electron transport layer to obtain a perovskite solar cell.

[0074] In the embodiments of the present application, silver electrodes are used as electrodes of perovskite solar cells.

[0075] In some embodiments, a vacuum coating machine is used to evaporate a metal electrode on the electron transport layer to prepare a perovskite solar cell.

[0076] Specifically, a vacuum coating machine is used, and when the vacuum degree in the chamber reaches a preset value, a silver electrode is evaporated on the electron transport layer to form a silver electrode. The evaporation rate is The electrode thickness is 80-120 nm, and a perovskite solar cell is prepared.

[0077] It should be noted that all solutions prepared in this application must be filtered through a 0.45 μm nylon filter membrane before use.

[0078] An embodiment of the present application also provides a perovskite solar cell, which is prepared using the method for preparing a perovskite solar cell provided by any of the above embodiments.

[0079] The following describes the method in conjunction with specific embodiments.

[0080] The present application provides a method for preparing a perovskite solar cell, and the method specifically includes: steps S201 to S205.

[0081] S201, providing I TO conductive glass, cleaning the I TO conductive glass, and plasma treating the cleaned I TO conductive glass; depositing a hole transport layer on the surface of the plasma-treated I TO conductive glass; depositing a self-assembled monolayer on the hole transport layer to obtain a substrate for preparing a perovskite solar cell.

[0082] The process of cleaning the I TO conductive glass includes: scrubbing the I TO conductive glass with a cotton swab dipped in soapy water and rinsing it with deionized water, then ultrasonically cleaning the I TO conductive glass in deionized water and ethanol in sequence, then placing the cleaned I TO conductive glass in a medium vacuum dryer, and then performing plasma treatment on the surface of the I TO conductive glass.

[0083] Among them, the specifications of I TO conductive glass are 20*16*0.7mm, the ultrasonic cleaning time is 30min, the vacuum drying temperature is 80°C, the vacuum drying time is 12h, and the plasma treatment time is 3min.

[0084] The hole transport layer is deposited on the surface of the plasma-treated ITO conductive glass, comprising: ultrasonically dissolving NiOx in deionized water to obtain a NiOx dispersion; spin-coating the NiOx dispersion on the ITO conductive glass, and then transferring the NiOx dispersion to a hot stage for annealing to form a NiOx film, thereby preparing the NiOx hole transport layer.

[0085] Among them, the ultrasonic time of NiOx dispersion is 10min, the concentration is 15mg / mL; the volume of spin-coated NiOx dispersion is 80μL, the spin-coating speed is 2000rpm, the spin-coating time is 30s, the annealing temperature is 150℃, and the annealing time is 20min.

[0086] A self-assembled monolayer is deposited on the hole transport layer, comprising: adding Me-4PACz to anhydrous ethanol and stirring to dissolve to obtain a Me-4PACz solution; spin-coating the Me-4PACz solution on the surface of a NiOx film; and then transferring the solution to a hot stage for annealing to anchor the Me-4PACz on the surface of the NiOx film to form a Me-4PACz self-assembled monolayer, thereby obtaining a substrate for preparing a perovskite solar cell.

[0087] The stirring time of the Me-4PACz solution was 12 h, the concentration was 0.5 mg / mL, the volume of the spin-coated Me-4PACz solution was 100 μL, the spin-coating speed was 4000 rpm, the spin-coating time was 30 s, the annealing temperature was 100° C., and the annealing time was 10 min.

[0088] S202, dissolving PbI2, FAI, MAI, and CsI in a mixed solvent of DMSO and DMF by shading and stirring to prepare a mixed solution; adding MAC1 to the mixed solution, and dissolving MAC1 in the mixed solution by stirring; adding PPNC1 to the mixed solution added with MAC1, and dissolving PPNC1 in the mixed solution by stirring; aging the mixed solution added with PPNC1 at room temperature to prepare a perovskite precursor solution.

[0089] The molar ratio of PbI2, FAI, MAI and CsI in the mixed solution is 1.65:1.275:0.15:0.075, the volume ratio of DMSO and DMF is 1:4, and the stirring time is 12h; the stirring time after adding MAC l is 2h, and the concentration of MAC l in the mixed solution is 12.5mol%; the concentration of PPNC l in the mixed solution is 1mmol%; the aging time is 4h, and the main component of the prepared perovskite precursor solution is Cs 0.05 FA 0.85 MA 0.1 Pb I3, final concentration is 1.5M.

[0090] S203. Use a two-step spin coating method to spin coat the perovskite precursor solution onto the surface of the Me-4PACz self-assembled monolayer. Quickly add chlorobenzene 5 seconds before the end of the second spin coating to induce the perovskite to crystallize into a film. After the second spin coating, quickly transfer it to a hot stage for annealing to form a perovskite layer.

[0091] Among them, in the two-step spin coating method, the spin coating speed in the first stage is 1000 rpm, and the spin coating time is 10 s; the spin coating speed in the second stage is 5000 rpm, and the spin coating time is 40 s; the added volume of the perovskite precursor solution is 100 μL, the added volume of chlorobenzene is 110 μL, the annealing temperature is 110°C, and the annealing time is 20 min.

[0092] S204, spin-coating the PEABr solution on the perovskite layer to prepare a passivation layer; and spin-coating the PCBM solution and the BCP solution on the passivation layer to prepare an electron transport layer.

[0093] The passivation layer is prepared by spin coating a PEABr solution on the perovskite layer, comprising: dissolving PEABr in isopropanol to obtain a PEABr solution; after the substrate with the perovskite layer formed on the surface is cooled to room temperature, the PEABr solution is spin coated on the perovskite layer, and then immediately transferred to a hot stage to form a passivation layer.

[0094] Among them, the PEABr concentration is 1 mg / mL, the spin coating volume is 80 μL, the spin coating speed is 4000 rpm, the spin coating time is 30 s, the annealing temperature is 100° C., and the annealing time is 10 min.

[0095] The electron transport layer is prepared by spin coating a PCBM solution and a BCP solution on the passivation layer respectively, including: stirring and dissolving the PCBM in chlorobenzene to obtain a PCBM solution; stirring and dissolving the BCP in isopropanol to obtain a BCP solution; spin coating the PCBM solution on the passivation layer, and then spin coating the BCP solution, and wait for the isopropanol to volatilize to form the electron transport layer.

[0096] Among them, the concentration of PCBM solution is 20 mg / mL, and the stirring time is 12 h; the concentration of BCP solution is 0.5 mg / mL, and the stirring time is 12 h; the spin coating speed of PEABr solution is 2000 rpm, the spin coating speed of PCBM solution is 4000 rpm, and the spin coating time is 30 s.

[0097] S205. Using a vacuum coating machine, evaporate a silver electrode on the electron transport layer to obtain a perovskite solar cell.

[0098] The vacuum degree in the vacuum coating machine chamber is 1x10 -5 Pa, the evaporation rate is The electrode thickness is 100nm, and the active area of ​​the perovskite solar cell is 0.06cm 2 .

[0099] The schematic diagram of the structure of the perovskite solar cell prepared according to step S201 to step S205 is as follows Figure 2 As shown, from bottom to top, they are transparent conductive substrate (ITO), hole transport layer (NiO X ), self-assembled monolayer (Me-4PACz), perovskite layer (perovskite), passivation layer (PEABr), electron transport layer (PCBM, BCP), electrode (Ag). It should be noted that Figure 2 The structure of the perovskite solar cell shown further includes a glass substrate (G l ass), wherein the transparent conductive substrate (ITO) is obtained by forming an indium tin oxide film on the glass substrate.

[0100] See also Figure 3a , 3b , 3c, 3d, Figure 3a , 3b They are the crystallization time diagrams of the spin coating process and annealing process of the perovskite film prepared without adding PPNC l (control group); Figure 3c , 3d They are respectively the crystallization time diagrams of the spin coating and annealing processes of the perovskite film in the embodiments of the present application.

[0101] Compared with the crystallization time of the perovskite film prepared in the control group during the spin coating process and the annealing process, it was found that the crystallization time of the perovskite film in the embodiment of the present application was delayed from 0.5s to 5.2s during the spin coating process, which is conducive to the formation of larger grains of perovskite, so that the perovskite film has better crystallinity and fewer defects.

[0102] See also Figure 4a and 4b , Figure 4a The X-ray diffraction (XRD) spectrum of the perovskite film prepared in the embodiment of the present application and the X-ray diffraction XRD spectrum of the perovskite film prepared without adding PPNC l (control group) are shown; Figure 4b yes Figure 4a A partial enlarged view of .

[0103] like Figure 4b As shown, after X-ray irradiation, compared with the perovskite film prepared in the control group, it was found that the intensity of the scattered light intensity peak (001) of the perovskite film prepared in the embodiment of the present application was enhanced, and the intensity of the Pb I2 impurity peak was reduced, indicating that the perovskite film prepared in the embodiment of the present application has better crystal orientation.

[0104] See also Figure 5a and Figure 5b , Figure 5a is a scanning electron microscope (SEM) image of the perovskite film prepared without adding PPNC l (control group), Figure 5b It is a SEM spectrum diagram of the perovskite film in the embodiment of the present application.

[0105] like Figure 5a and 5b As shown, there are many Pb I2 impurities at the grain boundaries of the perovskite film prepared in the control group, and the grain size of the perovskite is uneven, and the average grain size is small. However, the impurities at the grain boundaries of the perovskite film prepared in the embodiment of the present application are significantly reduced, and the grain size is uniform.

[0106] See also Figure 6 , Figure 6 The grain size distribution diagram of the perovskite film prepared in the embodiment of the present application and the grain size distribution diagram of the perovskite film prepared without adding PPNC l (control group) are shown.

[0107] like Figure 6 As shown, compared with the grain size of the perovskite film prepared in the control group, the average grain size of the perovskite film prepared in the embodiment of the present application is significantly increased, the average grain size increases from 800nm ​​to 1037.5nm, and the grain size is uniform.

[0108] See also Figure 7aand Figure 7b , Figure 7a is the atomic force microscopy (AFM) morphology of the perovskite film prepared without adding PPNC l (control group); Figure 7b This is an AFM morphology image of the perovskite film in the embodiment of the present application.

[0109] like Figure 7a and Figure 7b As shown, compared with the average roughness of the perovskite film prepared in the control group, the average roughness of the surface of the perovskite film in the embodiment provided by the present application is reduced from 17.6nm to 15.9nm. It can be seen that the perovskite film in the embodiment of the present application is more uniform and dense.

[0110] See also Figure 8 , Figure 8 The steady-state photoluminescence spectrum of the perovskite film prepared in the example of the present application and the steady-state photoluminescence spectrum of the perovskite film prepared without adding PPNC l (control group) are shown.

[0111] Compared with the fluorescence intensity of the perovskite film prepared in the control group, it was found that after the fluorescence was irradiated to the surface of the perovskite film, the fluorescence intensity of the perovskite film prepared in the example of the present application was enhanced.

[0112] See also Fig. 9 , Fig. 9 The time-resolved photoluminescence spectrum of the perovskite film prepared in the example of the present application and the time-resolved photoluminescence spectrum of the perovskite film prepared without adding PPNC l (control group) are shown.

[0113] Compared with the average carrier lifetime of the perovskite film prepared in the control group, it was found that after fluorescence was irradiated to the surface of the perovskite film, the average carrier lifetime of the perovskite film prepared in the embodiment of the present application increased, and the average carrier lifetime increased from 1129.83ns to 1724.18ns.

[0114] Combination Figure 8 and Fig. 9 It can be seen that the embodiments provided in the present application can reduce the surface defects and non-radiative recombination of the perovskite film.

[0115] See also Fig.10 , Fig.10 The open circuit voltage-light intensity diagram of the perovskite solar cell prepared in the embodiment of the present application and the open circuit voltage-light intensity diagram of the perovskite solar cell prepared without adding PPNC l (control group) are shown.

[0116] like Fig.10As shown, as the light intensity increases, the open circuit voltage of the perovskite solar cells prepared in the examples of the present application and the control group increases linearly. Under any same light intensity, compared with the open circuit voltage of the perovskite film prepared in the control group, it is found that the open circuit voltage of the perovskite solar cells prepared in the examples of the present application is greater than the open circuit voltage of the perovskite solar cells prepared in the control group. The slope of the fitted straight line of the perovskite solar cell in the control group is 1.46kT / q, and the slope of the fitted straight line of the perovskite solar cell in the example is 1.26kT / q.

[0117] See also Fig.11 , Fig.11 The Mott-Schottky curve of the perovskite solar cell prepared in the embodiment of the present application and the Mott-Schottky curve of the perovskite solar cell prepared without adding PPNC l (control group) are shown.

[0118] Compared with the built-in electric field strength of the perovskite solar cell prepared in the control group, it was found that the built-in electric field strength of the perovskite solar cell prepared in the embodiment of the present application increased from 0.94V to 0.97V.

[0119] Combination Fig.10 and Fig.11 It can be seen that the increase in the open circuit voltage of the perovskite solar cell prepared in the embodiment of the present application is related to the increase in the built-in electric field strength.

[0120] See also Fig.12 , Fig.12 The electrochemical impedance spectrum and the equivalent circuit diagram of the fitting curve of the perovskite solar cell prepared in the embodiment of the present application, and the electrochemical impedance spectrum and the equivalent circuit diagram of the fitting curve of the perovskite solar cell prepared without adding PPNC l (control group) are shown.

[0121] Compared with the series resistance Rs and parallel resistance Rrec of the perovskite solar cell prepared in the control group, it is found that the series resistance Rs of the perovskite solar cell prepared in the embodiment of the present application is smaller and the parallel resistance Rrec is larger. It can be seen that the perovskite solar cell in the embodiment of the present application can enhance the charge extraction capability and inhibit charge recombination.

[0122] See also Fig.13 , Fig.13 The current density and voltage characteristic (JV) curve of the perovskite solar cell prepared in the embodiment of the present application and the JV curve of the perovskite solar cell prepared without adding PPNC l (control group) are shown.

[0123] Depend on Fig.13 The photovoltaic performance of the embodiment and the control group can be extracted and shown in Table 1.

[0124] Table 1

[0125] <![CDATA[V OC (V)]]> <![CDATA[J SC (mA / cm 2 )]]> FF(%) PCE(%) Control group 1.14 24.94 77.73 22.12 Example 1.18 25.44 83.39 25.11

[0126] As shown in Table 1, the photovoltaic performance of the solar cell prepared in the embodiment of the present application is improved; compared with the photovoltaic performance of the control group, the open circuit voltage V OC , short circuit current density J SC and fill factor FF reached 1.18V and 25.44mA / cm 2 , 83.39%, 25.11%, and the photoelectric conversion efficiency PCE increased to 25.11%. It can be seen that the preparation method of the perovskite solar cell proposed in the embodiment of the present application can significantly improve the photovoltaic performance of the perovskite solar cell.

[0127] See also Fig.14 , Fig.14 The external quantum rate integral curve of the perovskite solar cell prepared in the embodiment of the present application and the external quantum rate integral curve of the perovskite solar cell prepared without adding PPNC l (control group) are shown.

[0128] like Fig.14 As shown, the integrated current of the perovskite solar cell prepared in the control group is 24.25 mA / cm 2 The integrated current of the perovskite solar cell prepared in the embodiment is 24.39 mA / cm 2 , the integrated current value is close to the current density value obtained from the battery efficiency test.

[0129] See also Fig.15 , Fig.15 The normalized cell efficiency of the perovskite solar cell prepared in the embodiment of the present application and the normalized cell efficiency of the perovskite solar cell prepared without adding PPNC l (control group) are shown.

[0130] The normalized cell efficiency of the perovskite solar cells prepared in the examples and control groups of the present application was obtained by testing at a temperature of 25±5°C, a nitrogen environment, and under packaging conditions. Fig.15 As shown, in the range of 0-3000h, the normalized efficiency of the perovskite solar cell gradually decreases. Compared with the normalized efficiency of the perovskite cell in the control group, the normalized efficiency of the perovskite solar cell in the embodiment is significantly increased at any time point within 0-3000h; the unpackaged perovskite solar cell prepared in the embodiment provided by the present application can be stored for about 3000h in a nitrogen environment at a temperature of 25°C, the efficiency of the perovskite solar cell in the control group is reduced to 80% of the initial efficiency, while the efficiency of the perovskite solar cell in the embodiment can maintain 95.8% of the initial efficiency.

[0131] From the above results, it can be seen that the preparation method of the perovskite solar cell proposed in the embodiment of the present application can prolong the crystallization time of the perovskite film, thereby reducing impurities at the perovskite grain boundaries, increasing the average grain size of the perovskite film, improving the density of the perovskite film, and reducing the surface defects of the perovskite film, thereby improving the stability and efficiency of the perovskite solar cell.

[0132] The above are only specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed in the present application, and these modifications or replacements should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A method for preparing a perovskite solar cell, characterized in that: The method comprises: A substrate for preparing a perovskite solar cell is provided, wherein a hole transport layer is formed on the surface of the substrate, and a self-assembled monomolecular layer is formed on the hole transport layer; preparing a perovskite precursor solution, and adding bis-(triphenylphosphorane)ammonium chloride into the perovskite precursor solution; The perovskite precursor solution is spin-coated onto the surface of the self-assembled monolayer, and the perovskite is induced to crystallize into a film by an anti-solvent to form a perovskite layer; A passivation layer is prepared on the perovskite layer, and an electron transport layer is prepared on the passivation layer; A metal electrode is prepared on the electron transport layer to obtain a perovskite solar cell.

2. The preparation method according to claim 1, characterized in that Preparing a perovskite precursor solution, comprising: Adding a solute into a mixed solvent of dimethyl sulfoxide and N,N-dimethylformamide, stirring the mixture to dissolve the solute in the solvent, and preparing a mixed solution, wherein the solute includes lead iodide, formamidine hydroiodide, methyl ammonium iodide, and cesium iodide; Add methylamine hydrochloric acid to the mixed solution and stir; Adding bis-(triphenylphosphorane)ammonium chloride to the mixed solution to which methylamine hydrochloric acid is added, and stirring the mixture to completely dissolve the bis-(triphenylphosphorane)ammonium chloride in the mixed solution; The mixed solution to which bis-(triphenylphosphorane)ammonium chloride is added is subjected to an aging treatment to obtain a perovskite precursor solution.

3. The preparation method according to claim 1, characterized in that The perovskite precursor solution is spin-coated onto the surface of the self-assembled monolayer, and the perovskite is induced to crystallize into a film by an anti-solvent to form a perovskite layer, comprising: The perovskite precursor solution is spin-coated onto the surface of the self-assembled monolayer using a two-step spin coating method, wherein the spin coating speed and the spin coating time of the first spin coating are both smaller than the spin coating speed and the spin coating time of the second spin coating; Add anti-solvent 5-8 seconds before the end of the second spin coating; After the second spin coating is completed, a thermal annealing treatment is performed to crystallize the perovskite into a film to obtain a perovskite layer.

4. The preparation method according to claim 1, characterized in that A passivation layer is prepared on the perovskite layer, comprising: Adding an ammonium salt material into an organic solvent to dissolve the ammonium salt material in the organic solvent to obtain an ammonium salt material solution; Waiting for the substrate with the perovskite layer formed on the surface to cool to room temperature; The ammonium salt material solution is spin-coated onto the perovskite layer and subjected to thermal annealing to form a passivation layer.

5. The preparation method according to claim 1, characterized in that An electron transport layer is prepared on the passivation layer, comprising: adding an electron transport layer material into an organic solvent and stirring the organic solvent to obtain an electron transport layer solution; adding a hole blocking layer material into an organic solvent and stirring the organic solvent to obtain a hole blocking layer solution; First, the electron transport layer solution is spin-coated on the passivation layer, and then the hole blocking layer solution is spin-coated, and the electron transport layer is formed after the solvent evaporates.

6. The preparation method according to claim 1, characterized in that A metal electrode is prepared on the electron transport layer, including: A vacuum coating machine is used to evaporate metal electrodes on the electron transport layer to prepare perovskite solar cells.

7. The preparation method according to claim 1, characterized in that Provided is a substrate for preparing a perovskite solar cell, comprising: Providing a transparent conductive substrate, cleaning the transparent conductive substrate, and performing plasma treatment on the cleaned transparent conductive substrate; Depositing a hole transport layer on the surface of the plasma-treated transparent conductive substrate; A self-assembled monolayer is deposited on the hole transport layer to obtain a substrate for preparing a perovskite solar cell.

8. The preparation method according to claim 7, characterized in that Depositing a hole transport layer on the surface of a transparent conductive substrate after plasma treatment, comprising: dissolving a hole transport layer material in deionized water to obtain a hole transport layer solution; The hole transport layer solution is spin-coated on the transparent conductive substrate treated with plasma, and the hole transport layer is formed on the transparent conductive substrate through thermal annealing.

9. The preparation method according to claim 7, characterized in that Depositing a self-contained monolayer on the hole transport layer includes: Adding the self-assembled single molecule material into an organic solvent and stirring the mixture to obtain a self-assembled single molecule solution; The self-assembled monomolecular solution is spin-coated on the hole transport layer, and subjected to thermal annealing to form a self-assembled monomolecular layer on the hole transport layer.

10. A perovskite solar cell, characterized in that: Prepared by the preparation method of any one of claims 1 to 9 for a perovskite solar cell.

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