Preparation method of annealing-free mixed oriented perovskite thin film and device
By forming a mixed-oriented two-dimensional perovskite layer at room temperature through spin-coating of an organic ammonium halide solution without annealing, the problems of crystal structure damage and functional layer defects caused by high-temperature annealing are solved, thereby improving the stability and efficiency of perovskite photovoltaic devices.
Patent Information
- Application Number
- CN202610184441.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-02-09
- Publication Date
- 2026-05-15
AI Technical Summary
In existing fabrication processes, high-temperature annealing damages the three-dimensional perovskite crystal structure, affecting interfacial chemical stability and charge transport. This makes it difficult to balance the requirements of charge transport and interfacial barrier, and microscopic defects in the functional layer limit device performance.
An anneal-free method was used to spin-coat a wet liquid film with an organic ammonium halide solution at room temperature. The film was then crystallized in situ by solvent evaporation to form a mixed-oriented two-dimensional perovskite layer. Combined with functional layer composition control and optimization, an anneal-free mixed-oriented perovskite thin film was prepared.
It improves the device's resistance to damp heat and its photoelectric conversion efficiency, reduces the interface series resistance, and enhances its chemical stability and charge transport capability.
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Figure CN122054904A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of solar photovoltaic technology, specifically to a method for preparing an anneal-free mixed-oriented perovskite thin film and device. Background Technology
[0002] Organic-inorganic hybrid perovskite solar cells have become a research hotspot in the photovoltaic field due to their excellent photoelectric conversion efficiency and low fabrication cost. To further improve the long-term stability of devices under humid and hot environments, constructing a two-dimensional perovskite layer on the surface of a three-dimensional perovskite light-absorbing layer to form a two-dimensional / three-dimensional heterojunction structure is currently the mainstream strategy. However, existing fabrication processes and film structures still face the following technical bottlenecks: In the conventional fabrication of two-dimensional / three-dimensional heterojunctions, high-temperature thermal annealing is usually required after spin-coating the organic ammonium salt layer to induce the crystallization of the two-dimensional perovskite material. Since the underlying three-dimensional perovskite light-absorbing layer is highly temperature-sensitive, the secondary heating process can easily damage the crystal structure of the three-dimensional perovskite surface, inducing lattice thermal stress and even causing surface component decomposition. This, in turn, reduces the chemical stability of the interface and affects the final performance of the device.
[0003] The introduction of bulk organic ammonium salts into two-dimensional perovskite layers imparts hydrophobicity but also leads to anisotropic charge transport characteristics. Common two-dimensional perovskite films tend to form layered structures parallel to the substrate orientation. This orientation causes the insulating organic spacer layer to block the longitudinal transport path of charge carriers, significantly increasing the series resistance at the interface and limiting the device's fill factor and short-circuit current. While a single vertically oriented structure is beneficial for charge transport, it is difficult to effectively block ion migration while maintaining surface passivation, making it difficult to simultaneously meet the dual requirements of charge transport and interface barrier.
[0004] The performance of perovskite photovoltaic devices is also limited by microscopic defects in each functional layer. During the crystallization process, uncoordinated lead or halogen vacancies are easily generated at grain boundaries and surfaces in three-dimensional perovskite light-absorbing layers, forming nonradiative recombination centers. Existing fabrication processes still need optimization in terms of functional layer composition control and bandgap matching to further suppress nonradiative recombination losses. Summary of the Invention
[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing an anneal-free mixed-oriented perovskite thin film and device, comprising the following steps: Step S1: Clean the surface of the indium tin oxide / fluorine-doped tin oxide conductive glass substrate to obtain a clean indium tin oxide conductive glass substrate. Step S2: An electron transport layer is prepared on the clean indium tin oxide / fluorine-doped tin oxide conductive glass substrate. Step S3: Prepare a three-dimensional perovskite light-absorbing layer on the electron transport layer; Step S4: Perform non-annealed surface post-treatment on the three-dimensional perovskite light-absorbing layer: spin-coat an organic ammonium halide solution onto the surface of the three-dimensional perovskite light-absorbing layer to form a wet liquid film. Keep it in a static state and do not perform thermal annealing. Utilize the natural evaporation of the solvent in the wet liquid film as the crystallization driving force to cause the organic ammonium halide in the organic ammonium halide solution to react in situ with the surface components of the three-dimensional perovskite light-absorbing layer and crystallize. After the solvent has completely evaporated, a two-dimensional perovskite layer with a mixed orientation structure is formed on the surface of the three-dimensional perovskite light-absorbing layer. Step S5: Prepare a hole transport layer on the two-dimensional perovskite layer; Step S6: Deposit a metal top electrode on the hole transport layer to obtain a perovskite photovoltaic device.
[0006] Preferably, in step S4, the organoammonium halide solution is a 4-methylbenzylammonium iodide solution; the 4-methylbenzylammonium iodide solution is prepared by dissolving the 4-methylbenzylammonium iodide solute in isopropanol solvent.
[0007] Preferably, in step S4, the specific process of the non-annealed surface post-treatment is as follows: the 4-methylbenzylammonium iodide solution is dropped onto the surface of the three-dimensional perovskite light-absorbing layer, and the 4-methylbenzylammonium iodide solution is spread on the surface of the three-dimensional perovskite light-absorbing layer by spin coating to form the wet liquid film; the wet liquid film is kept in a static state under nitrogen atmosphere at room temperature until the isopropanol solvent completely evaporates.
[0008] Preferably, in step S4, the two-dimensional perovskite layer with a mixed orientation structure comprises parallel-oriented crystals and vertically oriented crystals; the layered lattice plane of the parallel-oriented crystals is parallel to the surface of the three-dimensional perovskite light-absorbing layer, the layered lattice plane of the vertically oriented crystals is perpendicular to the surface of the three-dimensional perovskite light-absorbing layer, and the vertically oriented crystals are dispersed and embedded between the parallel-oriented crystals.
[0009] Preferably, step S3 is specifically carried out as follows: preparing a lead salt precursor solution, wherein the solutes of the lead salt precursor solution include lead iodide and potassium iodide; preparing an amine salt precursor solution, wherein the solutes of the amine salt precursor solution include formamidinium iodide and methylammonium chloride; depositing the lead salt precursor solution on the surface of the electron transport layer and annealing it to form a lead salt film; depositing the amine salt precursor solution on the lead salt film and performing a thermal annealing crystallization process to generate the three-dimensional perovskite light-absorbing layer composed of potassium-doped formamidinium-methylammonium mixed cationic perovskite crystals.
[0010] Preferably, in step S3, the solvent of the lead salt precursor solution is a mixed solvent of N,N-dimethylformamide and dimethyl sulfoxide; the solvent of the amine salt precursor solution is isopropanol; and the temperature of the thermal annealing crystallization process for generating the three-dimensional perovskite light-absorbing layer is 150 degrees Celsius.
[0011] Preferably, step S2 is specifically carried out as follows: a hydrogen peroxide-modified tin dioxide precursor solution is prepared by mixing tin dioxide colloidal solution, deionized water, and hydrogen peroxide in a preset volume ratio; the hydrogen peroxide-modified tin dioxide precursor solution is spin-coated onto the indium tin oxide conductive glass substrate; the spin-coated liquid film is annealed at 150 degrees Celsius to form the electron transport layer with a thickness of 20 nanometers.
[0012] Preferably, the specific process of S5 is as follows: preparing a hole transport layer precursor solution, the hole transport layer precursor solution comprising a solvent, and 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene, 4-tert-butylpyridine and lithium bis(trifluoromethanesulfonate)imide dissolved in the solvent; spin-coating the hole transport layer precursor solution onto the surface of the two-dimensional perovskite layer, and forming the hole transport layer after the solvent evaporates.
[0013] Preferably, the specific process of step S6 is as follows: using physical vapor deposition, gold is thermally evaporated onto the surface of the hole transport layer as a metal source to form the metal top electrode with a thickness of 80 nanometers.
[0014] Preferably, a perovskite photovoltaic device is prepared by the above-described method for preparing an anneal-free mixed-orientation perovskite thin film and device. The perovskite photovoltaic device comprises, from bottom to top, an indium tin oxide conductive glass substrate, an electron transport layer, a three-dimensional perovskite light-absorbing layer, a two-dimensional perovskite layer, a hole transport layer, and a metal top electrode. The two-dimensional perovskite layer covers the surface of the three-dimensional perovskite light-absorbing layer, and the two-dimensional perovskite layer exhibits a mixed orientation structure in which parallel-oriented crystals and vertically oriented crystals coexist.
[0015] This invention provides a method for preparing anneal-free mixed-oriented perovskite thin films and devices. It offers the following advantages: (1) In this invention, a 4-methylbenzylammonium iodide solution is spin-coated onto the surface of a three-dimensional perovskite light-absorbing layer and kept static at room temperature without heating. The natural evaporation of isopropanol solvent is used as the driving force for crystallization, causing the 4-methylbenzylammonium iodide molecules to react in situ with the surface components and crystallize. This kinetically controlled film formation method eliminates the thermal stress damage that traditional annealing processes may cause to the underlying three-dimensional perovskite light-absorbing layer, prevents secondary decomposition of the perovskite crystal structure, and thus ensures the chemical stability of the heterojunction interface.
[0016] (2) The two-dimensional perovskite layer prepared by this invention exhibits a unique hybrid orientation structure, which resolves the contradiction between interface passivation and charge transport. In this structure, parallel-oriented crystals construct a physical isolation barrier on the surface of the three-dimensional perovskite light-absorbing layer, effectively blocking the outward migration of internal ions and passivating dangling bond defects on the surface. At the same time, vertically oriented crystals are dispersed and embedded between the parallel-oriented crystals, forming a charge transport channel that runs through the longitudinal section of the two-dimensional perovskite layer. This structure significantly improves the device's resistance to damp heat and ensures the longitudinal conduction of charge carriers between the three-dimensional perovskite light-absorbing layer and the hole transport layer, reducing the interfacial series resistance.
[0017] (3) This invention optimizes the film quality and bandgap matching of each functional layer by controlling the precursor composition. Potassium iodide and methylammonium chloride are introduced into the preparation of the three-dimensional perovskite light-absorbing layer to generate a dense potassium-doped three-dimensional perovskite light-absorbing layer, which effectively improves the crystal quality. In conjunction with the electron transport layer prepared by using hydrogen peroxide-modified tin dioxide precursor solution, the oxidizing property of hydrogen peroxide is used to improve the surface defect states of the tin oxide film. The synergistic effect of the above functional layers reduces the non-radiative recombination centers inside the device and improves the carrier extraction efficiency, thereby improving the overall photoelectric conversion efficiency of the perovskite photovoltaic device. Attached Figure Description
[0018] Figure 1 This is a schematic diagram of the preparation method of the present invention; Figure 2 This invention does not have a two-dimensional morphological image; Figure 3 This is a morphological diagram of a two-dimensional surface treatment with distinct two-dimensional layers and mixed orientations, as presented in this invention. Detailed Implementation
[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0020] Please see Figure 1 This invention provides a method for preparing an anneal-free mixed-orientation perovskite thin film and device. This method involves a combination of physical deposition and chemical reaction on an indium tin oxide / fluorine-doped tin oxide conductive glass substrate to prepare a perovskite photovoltaic device. The specific preparation process includes the following steps: Step S1: Clean the surface of the indium tin oxide conductive glass substrate by using a cleaning agent, deionized water, acetone and ethanol to perform ultrasonic cleaning on the indium tin oxide conductive glass substrate. After cleaning, use nitrogen gas flow to dry the indium tin oxide conductive glass substrate to obtain a clean indium tin oxide conductive glass substrate.
[0021] Step S2: Prepare an electron transport layer by spin-coating a hydrogen peroxide-modified tin dioxide precursor solution onto a cleaned indium tin oxide conductive glass substrate. Anneal the spin-coated liquid film at a preset temperature to evaporate the solvent and form a dense electron transport layer on the surface of the indium tin oxide conductive glass substrate.
[0022] Step S3: A three-dimensional perovskite light-absorbing layer is prepared on the electron transport layer. A lead salt precursor solution is deposited on the surface of the electron transport layer and annealed to obtain a lead salt film. An amine salt precursor solution is deposited on the lead salt film, so that the amine salt precursor solution comes into contact with the lead salt film and reacts. Through a thermal annealing crystallization process, a three-dimensional perovskite light-absorbing layer is generated.
[0023] Step S4: Perform a non-annealed surface post-treatment on the three-dimensional perovskite light-absorbing layer. Spin-coat a 4-methylbenzylammonium iodide solution onto the surface of the three-dimensional perovskite light-absorbing layer to form a liquid film. Keep it in a static state at room temperature without heating, allowing the isopropanol solvent in the 4-methylbenzylammonium iodide solution to evaporate naturally. As the solvent evaporates, the 4-methylbenzylammonium iodide molecules react in situ with the surface components of the three-dimensional perovskite light-absorbing layer and crystallize. After the solvent has completely evaporated, a two-dimensional perovskite layer with a mixed orientation structure is formed on the surface of the three-dimensional perovskite light-absorbing layer. In the two-dimensional perovskite layer, parallel-oriented crystals and vertically oriented crystals coexist.
[0024] Step S5: Prepare a hole transport layer on the two-dimensional perovskite layer by spin-coating a hole transport layer precursor solution containing dopants onto the surface of the two-dimensional perovskite layer to form a solid hole transport layer.
[0025] Step S6: Deposit a metal top electrode on the hole transport layer. Using a physical vapor deposition process, heat from the metal source is evaporated onto the surface of the hole transport layer to form a metal top electrode, thus obtaining a perovskite photovoltaic device. The perovskite photovoltaic device consists of an indium tin oxide conductive glass substrate, an electron transport layer, a three-dimensional perovskite light-absorbing layer, a two-dimensional perovskite layer, a hole transport layer, and a metal top electrode, from bottom to top.
[0026] The surface cleaning treatment of the indium tin oxide conductive glass substrate described in step S1 specifically includes: The indium tin oxide / fluorine-doped tin oxide conductive glass substrate was cleaned with a cleaning agent, followed by rinsing with deionized water to remove residual cleaning agent.
[0027] The rinsed indium tin oxide conductive glass substrate was placed in an ultrasonic cleaner and ultrasonically cleaned in sequence with acetone, ethanol and deionized water.
[0028] After cleaning, the indium tin oxide conductive glass substrate was dried with nitrogen gas to obtain a clean indium tin oxide conductive glass substrate.
[0029] For step S2, the electron transport layer is prepared as follows: First, a hydrogen peroxide-modified tin dioxide precursor solution is prepared. A 15wt% tin dioxide colloidal solution, deionized water, and hydrogen peroxide are added to a container at a volume ratio of 1:4:1 and stirred evenly at room temperature. Then, an indium tin oxide conductive glass substrate is fixed on a spin coater, and the precursor solution is added dropwise. The spin coater is set to a speed of 4000 rpm and a time of 30 seconds to form a wet film. Finally, the substrate is placed on a heating stage and annealed at 150 degrees Celsius for 30 minutes to form an electron transport layer with a thickness of 20 nanometers.
[0030] For step S3, a three-dimensional perovskite light-absorbing layer is prepared: First, a precursor solution is prepared by dissolving lead iodide and potassium iodide (molar concentrations of 1.5M and 0.087M, respectively) in a DMF:DMSO (9:1) mixed solvent to obtain a lead salt precursor solution. Separately, 180 mg of formamidinium iodide and 29.5 mg of methylammonium chloride are dissolved in 2 mL of isopropanol to obtain an amine salt precursor solution. During preparation, the lead salt precursor solution is first spin-coated onto the electron transport layer and annealed at 70°C for 1 minute to obtain a lead salt film. After cooling, the amine salt precursor solution is spin-coated and annealed at 150°C for 12 minutes in an environment with a relative humidity of 35%. After the reaction is completed, a potassium-doped three-dimensional perovskite light-absorbing layer with a thickness of approximately 800 nm is generated.
[0031] Regarding the non-annealed surface post-treatment described in step S4, the specific spin coating operation is as follows: The indium tin oxide conductive glass substrate with the three-dimensional perovskite light-absorbing layer was transferred to a nitrogen glove box, and subsequent steps were all performed under a nitrogen atmosphere. Specifically: A solution of 4-methylbenzylammonium iodide was added dropwise to the surface of the three-dimensional perovskite light-absorbing layer.
[0032] The spin coating parameters are set as follows: spin speed 4000 rpm, time 30 seconds, and acceleration 9999 rpm.
[0033] Spin coating is initiated, and the 4-methylbenzylammonium iodide solution is uniformly spread on the surface of the three-dimensional perovskite light-absorbing layer. When spin coating is completed, a wet 4-methylbenzylammonium iodide solution film is formed on the three-dimensional perovskite light-absorbing layer.
[0034] Regarding the transformation of the wet liquid film in step S4, the indium tin oxide conductive glass substrate on which the wet liquid film is formed is kept in a static state.
[0035] During this static drying process, no external heat source of any kind is applied to the indium tin oxide conductive glass substrate, and no thermal annealing is performed.
[0036] The natural evaporation of isopropanol solvent inside the wet liquid film is used as the driving force for crystallization. The isopropanol solvent is gradually removed from the wet liquid film under nitrogen atmosphere at room temperature.
[0037] As the isopropanol solvent continues to evaporate, the concentration of 4-methylbenzyl ammonium iodide solute in the wet liquid film increases, and the high concentration of 4-methylbenzyl ammonium iodide undergoes an in-situ chemical reaction with the components on the surface of the three-dimensional perovskite light-absorbing layer.
[0038] After the isopropanol solvent has completely evaporated, the wet liquid film is transformed into a solid two-dimensional perovskite layer, which covers the surface of the three-dimensional perovskite light-absorbing layer.
[0039] The two-dimensional perovskite layer formed by the natural evaporation kinetics of the solvent exhibits a mixed-orientation crystal structure. The two-dimensional perovskite layer contains crystal phases parallel to the surface of the three-dimensional perovskite light-absorbing layer and crystal phases perpendicular to the surface of the three-dimensional perovskite light-absorbing layer.
[0040] Furthermore, the two-dimensional perovskite layer prepared in step S4 exhibits a specific spatial orientation distribution characteristic in its crystal structure, and the two-dimensional perovskite layer forms a continuous cover on the surface of the three-dimensional perovskite light-absorbing layer.
[0041] The two-dimensional perovskite layer contains a predominant proportion of horizontally oriented crystal domains. The inorganic framework layered plane of the horizontally oriented crystal domains is parallel to the surface of the three-dimensional perovskite light-absorbing layer. The horizontally oriented crystal domains construct a physical isolation barrier on the surface of the three-dimensional perovskite light-absorbing layer, passivating the dangling bond defects on the surface of the three-dimensional perovskite light-absorbing layer and preventing internal ions from migrating outward.
[0042] The two-dimensional perovskite layer also contains a minor proportion of vertically oriented crystal domains. The inorganic framework layered plane of the vertically oriented crystal domains is perpendicular to the surface of the three-dimensional perovskite light-absorbing layer. The vertically oriented crystal domains are dispersed among the horizontally oriented crystal domains, forming a charge transport channel that runs through the longitudinal section of the two-dimensional perovskite layer.
[0043] The hybrid orientation structure formed by natural volatilization kinetics achieves synergy of interface functions. Horizontally oriented crystal domains maintain the chemical stability of the interface, while vertically oriented crystal domains ensure the longitudinal conduction of charge carriers between the three-dimensional perovskite light-absorbing layer and the subsequent functional layers, thereby reducing the interfacial series resistance.
[0044] Furthermore, regarding the preparation of the hole transport layer described in step S5, a hole transport layer precursor solution is deposited on the surface of a two-dimensional perovskite layer, with the two-dimensional perovskite layer serving as a deposition substrate to support the hole transport layer. The prepared hole transport layer precursor solution is dropped into the central region of the two-dimensional perovskite layer, and the spin coating equipment is started to spin coat the hole transport layer precursor solution.
[0045] Under centrifugal force, the hole transport layer precursor solution spreads on the surface of the two-dimensional perovskite layer, filling the microstructure of the two-dimensional perovskite layer surface and forming a continuous liquid film. By keeping the indium tin oxide conductive glass substrate stationary, the chlorobenzene solvent and acetonitrile solvent in the liquid thin film evaporate naturally. After the solvents have completely evaporated, a solid hole transport layer is formed above the two-dimensional perovskite layer.
[0046] The hole transport layer formed is 100 nanometers thick and completely covers the two-dimensional perovskite layer, thus constructing a charge transport medium between the two-dimensional perovskite layer and the subsequent metal top electrode.
[0047] Furthermore, regarding the fabrication of the metal top electrode described in step S6, a conductive contact is constructed on the surface of the hole transport layer using a thermal evaporation process.
[0048] An indium tin oxide conductive glass substrate with a hole transport layer is fixed on the sample holder of a vacuum evaporation coating equipment. Gold is selected as the source material for the metal top electrode, and the gold material is loaded into the evaporation source crucible.
[0049] The vacuum system is activated to evacuate the coating chamber. Once the vacuum level in the coating chamber reaches the preset deposition standard, the heating program is activated to heat the evaporation source crucible.
[0050] Gold materials melt and vaporize under the action of thermal energy, generating a directional flow of gold atom vapor. The gold atom vapor is deposited on the outer surface of the hole transport layer. Gold atoms are adsorbed, nucleated and grow into islands on the surface of the hole transport layer, eventually connecting to form a continuous metal film.
[0051] The deposition rate and cumulative thickness are monitored in real time by a film thickness monitor. When the metal film thickness reaches 80 nanometers, heating and deposition operations are stopped, and a metal top electrode with a thickness of 80 nanometers is formed on the hole transport layer.
[0052] The metal top electrode serves as the back electrode of the perovskite photovoltaic device, and together with the indium tin oxide conductive glass substrate at the bottom, they form a charge collection circuit, completing the overall fabrication of the perovskite photovoltaic device.
[0053] The perovskite photovoltaic devices obtained through the above fabrication process exhibit a multi-layer solid-state stacked structure. The functional layers of the perovskite photovoltaic device are sequentially bonded along the vertical direction to form a complete charge generation and transport circuit. The indium tin oxide conductive glass substrate serves as the mechanical support and bottom light incident window of the device. The electron transport layer is attached to the conductive surface of the indium tin oxide conductive glass substrate. The electron transport layer is a dense tin dioxide thin film with a physical thickness of 30 nanometers.
[0054] The three-dimensional perovskite light-absorbing layer is located above the electron transport layer. The three-dimensional perovskite light-absorbing layer is composed of potassium-doped formamidinium-methylammonium mixed cationic perovskite crystals, and its physical thickness is 800 nanometers.
[0055] The two-dimensional perovskite layer is located on the upper surface of the three-dimensional perovskite light-absorbing layer. The two-dimensional perovskite layer is an organic-inorganic hybrid layered structure based on 4-methylbenzylammonium iodide. The two-dimensional perovskite layer exhibits mixed orientation characteristics in physical morphology.
[0056] The mixed orientation feature is characterized by the two-dimensional perovskite crystal containing both parallel orientation components and vertical orientation components in its spatial arrangement. The layered lattice plane of the parallel orientation component is parallel to the surface of the three-dimensional perovskite light-absorbing layer, while the layered lattice plane of the vertical orientation component is perpendicular to the surface of the three-dimensional perovskite light-absorbing layer. The vertical orientation component is dispersed and embedded between the parallel orientation components.
[0057] A hole transport layer covers the two-dimensional perovskite layer, filling the microscopic undulations on the surface of the two-dimensional perovskite layer. The hole transport layer is a doped Spiro-OMeTAD amorphous thin film with a physical thickness of 100 nanometers. The metal top electrode is located on the surface of the hole transport layer and serves as the back contact electrode of the device. The metal top electrode is a gold thin film with a physical thickness of 80 nanometers. The metal top electrode is connected to the bottom indium tin oxide conductive glass substrate through an external circuit to realize the output of photoelectric conversion energy.
[0058] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A method for preparing an anneal-free mixed-oriented perovskite thin film and device, characterized in that, Includes the following steps: Step S1: Clean the surface of the indium tin oxide / fluorine-doped tin oxide conductive glass substrate to obtain a clean indium tin oxide conductive glass substrate. Step S2: An electron transport layer is prepared on the clean conductive glass substrate. Step S3: Prepare a three-dimensional perovskite light-absorbing layer on the electron transport layer; Step S4: Perform non-annealed surface post-treatment on the three-dimensional perovskite light-absorbing layer: spin-coat an organic ammonium halide solution onto the surface of the three-dimensional perovskite light-absorbing layer to form a wet liquid film. Keep it in a static state and do not perform thermal annealing. Utilize the natural evaporation of the solvent in the wet liquid film as the crystallization driving force to cause the organic ammonium halide in the organic ammonium halide solution to react in situ with the surface components of the three-dimensional perovskite light-absorbing layer and crystallize. After the solvent has completely evaporated, a two-dimensional perovskite layer with a mixed orientation structure is formed on the surface of the three-dimensional perovskite light-absorbing layer. Step S5: Prepare a hole transport layer on the two-dimensional perovskite layer; Step S6: Deposit a metal top electrode on the hole transport layer to obtain a perovskite photovoltaic device.
2. The method for preparing an anneal-free mixed-oriented perovskite thin film and device according to claim 1, characterized in that: In step S4, the organic ammonium halide solution is a 4-methylbenzyl ammonium iodide solution; the 4-methylbenzyl ammonium iodide solution is prepared by dissolving the 4-methylbenzyl ammonium iodide solute in isopropanol solvent.
3. The method for preparing an anneal-free mixed-oriented perovskite thin film and device according to claim 1, characterized in that: In step S4, the specific process of the non-annealed surface post-treatment is as follows: the 4-methylbenzylammonium iodide solution is dropped onto the surface of the three-dimensional perovskite light-absorbing layer, and the 4-methylbenzylammonium iodide solution is spread on the surface of the three-dimensional perovskite light-absorbing layer by spin coating to form the wet liquid film; the wet liquid film is kept in a static state under nitrogen atmosphere at room temperature until the isopropanol solvent is completely evaporated.
4. The method for preparing an anneal-free mixed-oriented perovskite thin film and device according to claim 1, characterized in that: In step S4, the two-dimensional perovskite layer with a mixed orientation structure includes parallel-oriented crystals and vertically oriented crystals; the layered lattice plane of the parallel-oriented crystals is parallel to the surface of the three-dimensional perovskite light-absorbing layer, the layered lattice plane of the vertically oriented crystals is perpendicular to the surface of the three-dimensional perovskite light-absorbing layer, and the vertically oriented crystals are dispersed and embedded between the parallel-oriented crystals.
5. The method for preparing an anneal-free mixed-oriented perovskite thin film and device according to claim 1, characterized in that: The specific process of step S3 is as follows: prepare a lead salt precursor solution, wherein the solutes of the lead salt precursor solution include lead iodide and potassium iodide; prepare an amine salt precursor solution, wherein the solutes of the amine salt precursor solution include formamidinium iodide and methylamine chloride; deposit the lead salt precursor solution on the surface of the electron transport layer and anneal it to form a lead salt film; The amine salt precursor solution is deposited on the lead salt film, and then subjected to a thermal annealing crystallization process to generate the three-dimensional perovskite light-absorbing layer composed of potassium-doped formamidinium-methylammonium mixed cationic perovskite crystals.
6. The method for preparing an anneal-free mixed-oriented perovskite thin film and device according to claim 5, characterized in that: In step S3, the solvent of the lead salt precursor solution is a mixed solvent of N,N-dimethylformamide and dimethyl sulfoxide; the solvent of the amine salt precursor solution is isopropanol; and the temperature of the thermal annealing crystallization process for generating the three-dimensional perovskite light-absorbing layer is 150 degrees Celsius.
7. The method for preparing an anneal-free mixed-oriented perovskite thin film and device according to claim 1, characterized in that: The specific process of step S2 is as follows: a hydrogen peroxide-modified tin dioxide precursor solution is prepared by mixing tin dioxide colloidal solution, deionized water and hydrogen peroxide in a preset volume ratio; the hydrogen peroxide-modified tin dioxide precursor solution is spin-coated onto the indium tin oxide conductive glass substrate; the spin-coated liquid film is annealed at 150 degrees Celsius to form the electron transport layer with a thickness of 20 nanometers.
8. The method for preparing an anneal-free mixed-oriented perovskite thin film and device according to claim 1, characterized in that: The specific process of step S5 is as follows: Prepare a hole transport layer precursor solution, which includes a solvent and 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene, 4-tert-butylpyridine and lithium bis(trifluoromethanesulfonate)imide dissolved in the solvent; spin-coat the hole transport layer precursor solution onto the surface of the two-dimensional perovskite layer, and form the hole transport layer after the solvent evaporates.
9. The method for preparing an anneal-free mixed-oriented perovskite thin film and device according to claim 1, characterized in that: The specific process of step S6 is as follows: using physical vapor deposition, gold is thermally evaporated onto the surface of the hole transport layer as a metal source to form the metal top electrode with a thickness of 80 nanometers.
10. A perovskite photovoltaic device, characterized in that, The perovskite photovoltaic device is prepared by the method of any one of claims 1 to 9 for the preparation of an annealed mixed-orientation perovskite thin film and device; the perovskite photovoltaic device comprises, from bottom to top: an indium tin oxide / fluorine-doped tin oxide conductive glass substrate, an electron transport layer, a three-dimensional perovskite light-absorbing layer, a two-dimensional perovskite layer, a hole transport layer, and a metal top electrode; wherein, the two-dimensional perovskite layer covers the surface of the three-dimensional perovskite light-absorbing layer, and the two-dimensional perovskite layer exhibits a mixed orientation structure in which parallel-oriented crystals and vertical-oriented crystals coexist.