Perovskite solar cell, electron transport layer thin film preparation method and application

Abstract

The invention relates to a perovskite solar cell, an electron transport layer thin film preparation method and application. The method comprises the following steps in sequence: providing a substrate in an atomic layer deposition reaction chamber; the temperature of the reaction chamber is set and maintained between 80 DEG C and 120 DEG C; and a plurality of atomic layer deposition cycles are executed, and each cycle sequentially comprises the following steps: after the previous N1 cycles are completed, the pulse time of the oxygen source precursor in the subsequent N2 cycles is kept at a final value until the deposited SnOX film reaches the target thickness. According to the invention, the nucleation process is optimized fundamentally, and the technical bottleneck of non-uniform initial growth is solved.

Description

Technical Field

[0001] This invention relates to the field of perovskite solar cell technology, and in particular to a perovskite solar cell, a method for preparing an electron transport layer thin film, and its application. Background Technology

[0002] In recent years, perovskite solar cells have been widely regarded as one of the most promising candidates for next-generation photovoltaic technology due to their advantages such as flexible fabrication processes, wide light absorption range, long carrier diffusion length, and long carrier lifetime, attracting continuous attention from the research community. Recent reports indicate that the energy conversion efficiency of small-area laboratory perovskite cells has exceeded 26%, while large-area modules (such as 1m×2m modules) have also achieved conversion efficiencies exceeding 18%.

[0003] Atomic layer deposition (ALD), a derivative of chemical vapor deposition (CVD), works by alternately and self-limitingly introducing gaseous precursors into a reaction chamber, causing them to undergo sequential chemical reactions on the substrate surface, thereby forming a uniform and dense thin film layer by layer. Due to its excellent film quality and consistency, this technology has been widely used in the manufacturing process of perovskite solar cells, especially in the production of tin oxide (SnO). X It plays a key role in the deposition of electron transport layers.

[0004] Perovskite solar cells (PSCs) have a structure similar to a sandwich structure, consisting of stacked thin films, similar to the structure of inverted perovskite solar modules. Figure 1 As shown, the device fabrication sequence is as follows: conductive glass substrate → P1 scribing → hole transport layer → perovskite absorber layer → electron transport layer → P2 scribing → electrode → P3, P4 scribing.

[0005] In the development of perovskite solar cells, SnO in the electron transport layer (ETL) X Thin film performance and quality have a significant impact on the efficiency of perovskite solar cells. The oxygen source reacting with the Sn source phase affects the performance and quality of this oxide film. SnO was prepared using atomic layer deposition (ALD). X When using a fixed, high water (H2O) pulse time during the nucleation phase of thin films, the initial results in low nucleation density, delayed nucleation, and potentially high surface roughness due to excessive water (H2O) molecules. This leads to a deposition rate and density that do not meet theoretical expectations, and may introduce numerous defects such as oxygen vacancies, ultimately degrading the film's electrical properties (such as carrier mobility and conductivity), making it difficult to meet the requirements for its application as a high-efficiency electron transport layer.

[0006] The shortcomings of existing technology are: In the early stages of deposition (i.e., the nucleation stage), especially on non-ideal substrates, the chemisorption of the precursor may be uneven or insufficient. Using a fixed, high or low water (H2O) pulse time during the nucleation period may lead to the following problems: Excessive water (H2O) molecules may undergo side reactions with the surface or cause some precursor molecules to "desorb," thereby reducing the effective nucleation sites.

[0007] Insufficient water can lead to delayed nucleation and reduced growth rate: low nucleation density means only the most active sites are occupied, resulting in fewer and more spaced "island" nuclei. Subsaturated growth may occur, with the amount of material deposited per cycle falling below theoretical values, leading to a significant decrease in the apparent growth rate (GPC). Furthermore, the nucleation incubation period is longer, requiring more cycles to form a continuous film, wasting precursors and time.

[0008] Poor film density and uniformity: Island-like growth prevents the film from spreading uniformly, resulting in a very rough and porous film before achieving continuity. This can lead to pinholes and defects, with microscopic defects such as pinholes and cracks easily forming at the boundaries of island mergers. Uneven nucleation can further lead to the growth of a porous, non-dense film with high defect density, thus affecting the film's barrier properties, insulation properties, and service life.

[0009] In view of the above-mentioned shortcomings, the designer has actively researched and innovated in order to create a method for preparing and applying a thin film for electron transport layer in perovskite solar cells, making it more valuable for industrial use. Summary of the Invention

[0010] To address the aforementioned technical problems, the present invention aims to provide a method for preparing a perovskite solar cell and an electron transport layer thin film, as well as their applications.

[0011] To achieve the above objectives, the present invention adopts the following technical solution: One of the objectives of this invention is: The method for preparing the electron transport layer thin film of a perovskite solar cell includes the following steps: Step 1: Provide a substrate within the atomic layer deposition reaction chamber; Step 2: Set and maintain the temperature of the reaction chamber between 80°C and 120°C; Step 3: Perform several atomic layer deposition cycles, each cycle consisting of: Step 31: Pulsely introduce the metal precursor into the reaction chamber to allow it to complete self-limited chemisorption on the substrate surface; Step 32: Purge the reaction chamber with inert gas to remove residual tin source precursor and gaseous byproducts from the reaction chamber; Step 33: Pulsely introduce oxygen source precursor into the reaction chamber; Step 34: Purge the reaction chamber again with inert gas to remove any remaining mixed oxygen source and reaction byproducts. In the first N1 cycles of the deposition process, the pulse time of the oxygen source precursor increases linearly from the initial value to the final value as the number of cycles increases. N1 is an integer between 20 and 40, with an initial value of 1 to 3 seconds and a final value of 7 to 9 seconds. Step 4: After completing the first N1 cycles, the pulse time of the oxygen source precursor in the subsequent N2 cycles remains at the final value until the deposited SnO is achieved. X The film reaches the target thickness; Where N2 is an integer between 40 and 60.

[0012] As a further improvement of the present invention, the oxygen source precursor is water, the initial value is 2 seconds, the final value is 8 seconds, N1 is 30, and N2 is 50.

[0013] As a further improvement of the present invention, the pulse time of the oxygen source precursor starts from 2 seconds and increases linearly by 2 seconds every 10 cycles, reaching 8 seconds at the 30th cycle; the pulse time of the oxygen source precursor is kept at 8 seconds for the subsequent 50 cycles.

[0014] As a further improvement of the present invention, the metal precursor is tetramethylaminotin, and the pulse time remains constant during the atomic layer deposition cycle.

[0015] The second objective of this invention is: The fabrication method of perovskite solar cells includes the following steps in sequence: Step 1: Provide a conductive glass substrate, clean and dry it, and then perform P1 laser scribing; Step 2: Deposit a hole transport layer on the substrate; Step 3: Deposit a perovskite light-absorbing layer on the hole transport layer; Step 4: Perform interface modification on the perovskite light-absorbing layer and deposit the first electron transport layer; Step 5: Deposit SnO on the first electron transport layer using any one of the electron transport layer thin film preparation methods as described in claims 1 to 4. X The thin film serves as the second electron transport layer; Step 6: Perform P2 laser scribing to expose the bottom conductive electrodes; Step 7: Perform P3 laser scribing and deposit the metal top electrode to complete the battery fabrication.

[0016] As a further improvement of the present invention, in step 2, NiO is deposited by magnetron sputtering. X The thin film serves as a hole transport layer.

[0017] As a further improvement of the present invention, in step 3, slit coating is used to coat the FA. 0.83 Cs 0.17 PbI 2.8 Cl 0.2 The perovskite precursor solution is coated onto the substrate at a rate of 3-5 cm / s, followed by vacuum flash evaporation for 16-20 seconds and annealing at 140-160°C for 28-32 minutes to form a perovskite thin film, i.e., a perovskite light-absorbing layer.

[0018] As a further improvement of the present invention, in step 4, the slit is coated with PEAI solution and annealed, followed by the deposition of a C layer with a thickness of 18-22 nm by thermal evaporation. 60 It serves as the first electron transport layer.

[0019] The third objective of this invention: The perovskite solar cell is prepared by any of the methods described above.

[0020] The fourth objective of this invention: Application of electron transport layer thin films in the fabrication of perovskite solar cells, wherein the electron transport layer thin films are prepared by any of the electron transport layer thin film preparation methods described above.

[0021] By means of the above-described solution, the present invention has at least the following advantages: This invention fundamentally optimizes the nucleation process, solving the technical bottleneck of uneven initial growth: In existing technologies, a fixed high-water (H2O) pulse can cause uncontrollable reactions with inert or insufficiently reactive substrate surfaces during the initial deposition stage. This invention achieves mild and controllable chemisorption through an extremely short initial water (H2O) pulse duration, effectively avoiding the "desorption" of precursor molecules and side reactions, thereby significantly improving the initial nucleation density and uniformity. This provides a universal and effective solution to the nucleation problem of ALD on non-ideal substrates.

[0022] This invention significantly improves the chemical purity of thin films and achieves effective control of impurity content. Compared with traditional methods, this approach achieves precise supply of dosage matched to the growth stage. In the initial stage, short pulses prevent impurities from being encapsulated; in the middle stage of growth, gradually increasing pulses ensure more thorough removal of ligands. Furthermore, experimental data show that the thin films prepared using this invention exhibit improved chemical purity.

[0023] This invention significantly improves the microstructure and density of thin films, overcoming the root cause of performance degradation: the thin film grown from high-density, uniform nucleation centers, SnO XThe microstructure has been fundamentally improved. The film is more dense, continuous, and free of obvious pores and island structures. This optimized structure is the physical basis for the film's better functional properties.

[0024] This invention introduces a novel process concept of "dynamic adaptation," which produces a series of positive effects on nucleation quality, film purity, microstructure, and final performance.

[0025] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the following are preferred embodiments of the present invention described in detail with reference to the accompanying drawings. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the structure of a perovskite solar cell in the prior art; Figure 2 This is a schematic flowchart of the method for preparing the electron transport layer thin film of the perovskite solar cell of the present invention; Figure 3 This is a schematic flowchart of the method for preparing the perovskite solar cell of the present invention; Figure 4 This is a schematic diagram of the refractive index of the second experimental example of the present invention; Figure 5 This is a schematic diagram of the comparative refractive index of the present invention. Detailed Implementation

[0028] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0029] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0030] First embodiment of the present invention: like Figure 2 As shown, the method for preparing the electron transport layer thin film of the perovskite solar cell in this embodiment includes the following steps in sequence: Step 1: Provide a substrate in the atomic layer deposition reaction chamber.

[0031] Step 2: Set and maintain the temperature of the reaction chamber between 80°C and 120°C.

[0032] Step 3: Perform several atomic layer deposition cycles, each cycle consisting of: Step 31: Pulsely introduce the metal precursor into the reaction chamber to allow it to complete self-limited chemisorption on the substrate surface; Step 32: Purge the reaction chamber with inert gas to remove residual tin source precursor and gaseous byproducts from the reaction chamber; Step 33: Pulsely introduce oxygen source precursor into the reaction chamber; Step 34: Purge the reaction chamber again with inert gas to remove any remaining mixed oxygen source and reaction byproducts. In the first N1 cycles of the deposition process, the pulse time of the oxygen source precursor increases linearly from the initial value to the final value as the number of cycles increases. N1 is an integer between 20 and 40, with an initial value of 1 to 3 seconds and a final value of 7 to 9 seconds.

[0033] Step 4: After completing the first N1 cycles, the pulse time of the oxygen source precursor in the subsequent N2 cycles remains at the final value until the deposited SnO is achieved. X The film reaches the target thickness.

[0034] Where N2 is an integer between 40 and 60.

[0035] Specifically, the oxygen source precursor is water, the initial value is 2 seconds, the final value is 8 seconds, N1 is 30, and N2 is 50.

[0036] Specifically, the pulse time of the oxygen source precursor starts at 2 seconds and increases linearly by 2 seconds every 10 cycles, reaching 8 seconds by the 30th cycle; the pulse time of the oxygen source precursor is maintained at 8 seconds for the next 50 cycles.

[0037] Specifically, the metal precursor is tetramethylaminotin, and the pulse time remains constant throughout the atomic layer deposition cycle.

[0038] The second embodiment of the present invention: like Figure 3 As shown, the fabrication method of the perovskite solar cell in this embodiment includes the following steps in sequence: Step 1: Provide a conductive glass substrate, clean and dry it, and then perform P1 laser scribing; Step 2: Deposit a hole transport layer on the substrate; Step 3: Deposit a perovskite light-absorbing layer on the hole transport layer; Step 4: Perform interface modification on the perovskite light-absorbing layer and deposit the first electron transport layer; Step 5: Deposit SnO on the first electron transport layer using any of the electron transport layer thin film preparation methods described above. X The thin film serves as the second electron transport layer; Step 6: Perform P2 laser scribing to expose the bottom conductive electrodes; Step 7: Perform P3 laser scribing and deposit the metal top electrode to complete the battery fabrication.

[0039] Specifically, in step 2, NiO is deposited by magnetron sputtering. X The thin film serves as a hole transport layer.

[0040] Specifically, in step 3, slit coating is used to apply FA. 0.83 Cs 0.17 PbI 2.8 Cl 0.2 The perovskite precursor solution is coated onto the substrate at a rate of 3-5 cm / s, followed by vacuum flash evaporation for 16-20 seconds and annealing at 140-160°C for 28-32 minutes to form a perovskite thin film, i.e., a perovskite light-absorbing layer.

[0041] Specifically, in step 4, the slit is coated with PEAI solution and annealed, followed by the deposition of a 18-22 nm thick C layer via thermal evaporation. 60 It serves as the first electron transport layer.

[0042] Analysis of the innovative aspects of the above steps in this embodiment: 1. In the completed perovskite / C 60ALD deposition is performed directly on the sensitive layer, rather than on an inert substrate. This requires an extremely gentle process to avoid damaging the underlying material. This is synergistic with subsequent low temperatures (80-120°C) and an ultrashort initial water pulse (0.5s). Only such a combination of gentle initial conditions can high-quality SnO be achieved without damaging the underlying organic / perovskite material. X Heterogeneous epitaxial growth. This is a process package specifically designed to protect sensitive layers, not a simple choice.

[0043] 2. Temperature setting (80-120℃), this temperature is lower than SnO X Conventional ALD temperatures (typically >150℃). Low temperatures can inherently lead to poor film quality. This temperature setting is synergistic with a "linearly increasing water pulse": at low temperatures, the precursor surface mobility is low, and a fixed water pulse easily leads to uneven nucleation, slow growth, and porous films. This invention overcomes the inherent defects of low-temperature deposition by dynamically increasing the water pulse and actively controlling the reaction kinetics at low temperatures, obtaining unexpectedly high-quality films. The parameter combination solves new problems.

[0044] 3. Tin source pulse (TDMASn), although TDMASn is used to prepare SnO X TDMASn is one of the conventional precursors, but its hydrolysis may be incomplete at low temperatures due to the synergistic effect of water pulse timing and low temperature. This invention precisely matches the optimal hydrolysis dosage of TDMASn at different growth stages (nucleation, island growth, and layered growth) at low temperatures by gradually increasing water pulses starting from extremely short pulses, achieving a balance between reaction efficiency and film quality. The combination of this specific precursor and specific timing is crucial.

[0045] 4. The water pulse timing (linearly increasing) alters the fundamental paradigm of ALD (Alternating Current Discharge) where the precursor dose is constant in each cycle, serving as the pivot for synergistic effects: 1) The purpose is not simply to adjust the dose, but to actively match different physical stages of film growth (nucleation processes from sparse to dense). 2) The effects are not simply additive: under specific low temperatures and with specific precursors, linear increasing produces unexpected technical effects such as shortening the nucleation incubation period, increasing nucleation density, and ultimately significantly improving film density (refractive index) and device FF (fingerprint effect). 3) It is not an obvious function: stepwise, parabolic, and other abrupt changes can lead to interface defects, while linear gradual changes have been proven to achieve the smoothest, defect-free transition in this scenario, requiring creative discovery.

[0046] 5. Inert gas purging in conjunction with dynamic water pulses: Because the water pulse duration varies, the amount of residual byproducts to be removed in each cycle differs. The fixed purging time or flow rate in this invention is an optimized result matched to a specific pulse timing scheme, ensuring sufficient removal of byproducts at any pulse length without excessively long process cycles. This is a necessary condition for ensuring stable operation of the dynamic timing sequence.

[0047] The core technical problem addressed in this embodiment is: how existing technologies can deposit high-quality, dense SnO on low-temperature, sensitive substrates. X When working on the electron transport layer, we face a synergistic technical challenge: low nucleation density, non-dense thin films, and susceptibility to damage to the underlying layer. This is more specific and severe than simply "improving the quality of the thin film."

[0048] Although the individual steps (low temperature, TDMASn, water, N2 purging) are known, the specific combination of "controlling the water pulse time linearly from a very short duration at low temperature" has not been disclosed or suggested by any prior art.

[0049] When faced with this problem, those skilled in the art would typically optimize a fixed temperature, a fixed pulse time, or replace the precursor, rather than dynamically changing the pulse time of the precursor within a cycle, as this would contradict the conventional thinking of ALD in pursuing cycle stability.

[0050] Furthermore, the experimental data from the second experimental example and the comparative example below show that: Direct effect: The data from the second experimental case (average refractive index from 1.73 to 1.90) directly demonstrates the leap in film density, which is not a simple sum of the effects of each step.

[0051] Indirect effect: The significant improvement in the final device performance (PCE from 20.89% to 21.40%, FF improvement) in the second experimental example proves that this method fundamentally optimizes the quality of the electron transport layer.

[0052] Evidence of synergistic effect: Provide comparative data (such as fixed pulse, stepped increasing pulse) to prove that only "linear increasing" achieves the best effect in this specific combination, indicating that there is a sensitive synergistic relationship between the conditions, rather than a simple combination.

[0053] This embodiment, through the logical closed loop of "problem-solution-effect", presents a new and more complex technical scenario (low temperature + sensitive substrate), which has given rise to the need for non-obvious reorganization of existing technical means (ALD steps) and produced unexpected synergistic effects.

[0054] The third embodiment of the present invention: The perovskite solar cell of this embodiment is prepared by any of the perovskite solar cell preparation methods described above.

[0055] Fourth embodiment of the present invention: The application of the electron transport layer thin film in the fabrication of perovskite solar cells in this embodiment is described above. The electron transport layer thin film is prepared by any of the electron transport layer thin film preparation methods described above.

[0056] First experimental example of the present invention: This experimental example demonstrates a SnO2 method for improving the electron transport layer performance of perovskite solar cells. X The core of the thin film preparation method lies in the use of atomic layer deposition technology, which linearly increases the pulse time of the first 30 cycles of water (H2O) to obtain high-quality SnO with high density and low defect density. X film.

[0057] The specific technical solution includes the following steps: A method for improving the stability of perovskite solar modules, the core of which lies in using atomic layer deposition (ALD) technology to deposit a layer of tin dioxide (SnO2) based on a water (H2O) pulsed timing gradient. The specific technical solution includes the following steps: Base preparation and furnace loading: Place a clean 30cm... A 30cm glass substrate is placed in the reaction chamber of the atomic layer deposition equipment; Temperature rise and stabilization of the reaction chamber in atomic layer deposition equipment: Set the temperature of the reaction chamber within the process window of 80℃~120℃ to ensure its full stability; SnO2 thin film deposition cycle: Perform the following deposition cycles in sequence until the target film thickness is achieved: a. Tin source pulse and saturation: A sufficient amount of tin source tetramethylaminotin (TDMASn) is introduced into the reaction chamber to allow it to complete self-limiting chemisorption on the substrate surface.

[0058] b. Purging: High-purity nitrogen gas is introduced to purge and remove residual tin source precursors and gaseous byproducts from the reaction chamber.

[0059] c. Linearly increasing oxygen source (H2O) introduction time: In the first 30 cycles, the oxygen source (H2O) introduction time is linearly increased to allow it to react with the chemisorbed tin source precursor.

[0060] d. Purging: High-purity nitrogen gas is introduced again to purge and remove residual mixed oxygen sources and reaction byproducts.

[0061] Deposition termination and sample removal: When the number of cycles reaches 80, the deposition is stopped and the sample is removed.

[0062] Second experimental example of the present invention: This experimental example aims to overcome the shortcomings of the existing technology and provide a perovskite solar module and its preparation method. The core of the solution lies in: preparing SnO using atomic layer deposition technology. X In thin film deposition, the pulse time of water (H2O) in the original process is changed to gradually increase the pulse time of water (H2O) in the first N1 cycles, so that the tin source and oxygen source can be combined more stably. This provides an atomic layer deposition method that can significantly improve the initial growth quality and density of thin films.

[0063] This experimental example demonstrates the fabrication of a perovskite solar module that significantly improves the initial growth quality, purity, and density of thin films by linearly increasing the pulse time of the first 30 cycles of water (H2O). 1. Substrate preparation: Take a 30cm×30cm ITO glass substrate, clean and dry it, and then perform P1 laser scribing.

[0064] 2. Hole transport layer deposition: NiOx thin film is deposited by magnetron sputtering (PVD).

[0065] 3. Perovskite layer deposition: A slot coating method is used to deposit FA... 0.83 Cs 0.17 PbI 2.8 Cl 0.2 A perovskite precursor solution (1.5M) was coated onto the substrate at a rate of 4 cm / s, followed by vacuum flash evaporation for 18 seconds and annealing at 150°C for 30 minutes to form a perovskite film.

[0066] 4. Interface Modification and Electron Transport Layer Deposition: PEAI solution (4 mg / mL) was applied to the slit and annealed. Subsequently, a 20 nm thick C layer was deposited via thermal evaporation. 60 The layer serves as an electron transport layer.

[0067] 5. Deposit a SnO2 layer with progressively increasing water (H2O) pulse time during the initial deposition stage (first 30 cycles): using ALD process at a chamber temperature of 80°C. a. Pulsively introduce the first precursor TDMASn into the reaction chamber; b. Purge the reaction chamber with an inert purging gas (N2); c. A pulsed water (H2O) source is introduced as a second precursor; d. Purge the reaction chamber with an inert purging gas (N2).

[0068] In the first 30 cycles, the water (H2O) pulse purging time in step c) increases cyclically according to a preset incremental function. The water (H2O) pulse time starts at 2 seconds and increases linearly by 2 seconds every 10 cycles, reaching 8 seconds in the 30th cycle. The water (H2O) pulse time remains at 8 seconds for the subsequent 50 cycles.

[0069] The core idea of ​​the above-mentioned "dynamic adaptation" is to break the traditional thinking that the reactant dosage in the ALD process is "unchanging" and establish the basic principle of dynamically matching the water (H2O) pulse time parameter with the film growth stage (from nucleation to continuous growth) in the first few to dozens of cycles.

[0070] Precise design of the incremental sequence: Specifically, the quantitative range of the key parameters of linear increment is adopted, including the precise data of the three key parameters and their optimal value ranges: the initial pulse time (2s), the final stable pulse time (8s), and the total number of incrementing cycles N (30 cycles).

[0071] In addition, the synergistic optimization of the process window: when implementing incremental procedures, the optimal synergistic relationship with other process parameters (such as temperature, precursor pulse, and purge time) is ensured to guarantee the stability and repeatability of the overall process.

[0072] 6. P2 scribing: Perform P2 laser scribing to expose the bottom ITO electrode.

[0073] 7. P3 scribing and electrode fabrication: Perform P3 laser scribing, and finally deposit the metal top electrode to complete the module fabrication.

[0074] Effect test: The module was tested using a JV test, and its initial efficiency was 21.40%, with the device's fill factor (FF) increased to 81.47%.

[0075] like Figure 4 The refractive index of the tin oxide film was tested, and the average refractive index was 1.90.

[0076] Comparative examples of the present invention: This comparative example prepared a SnO2 layer module using a fixed, high water (H2O) pulse time (8s) during the nucleation phase, with all other steps identical. The module efficiency was 20.89%, and the fill factor was 81.34%. Figure 5 The refractive index of the tin oxide film was tested, and the average refractive index was 1.73.

[0077] The refractive index of tin oxide thin films is a direct reflection of their density, and the two are positively correlated: the denser the film, the higher the refractive index.

[0078] It clearly demonstrates the problems caused by the fixed pulse in the early stages, such as low nucleation density, delayed nucleation, and high surface roughness that may be caused by excessive water (H2O) molecules.

[0079] The data for the second experimental example and comparative example of this invention are shown in the table below.

[0080] The above experimental examples fully demonstrate the "dynamic adaptation" concept of the embodiments (i.e., the duration of the water (H2O) pulse matches the thin film growth stage). The perovskite solar module with atomic layer deposition of tin oxide based on the water (H2O) pulse timing gradient in the early stage of nucleation provided by this invention significantly improves device performance and establishes its application value in high-performance perovskite solar modules.

[0081] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0082] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0083] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing an electron transport layer thin film for a perovskite solar cell, characterized in that: The steps are as follows: Step 1: Provide a substrate within the atomic layer deposition reaction chamber; Step 2: Set and maintain the temperature of the reaction chamber between 80°C and 120°C; Step 3: Perform several atomic layer deposition cycles, each cycle consisting of: Step 31: Pulsely introduce the metal precursor into the reaction chamber to allow it to complete self-limited chemisorption on the substrate surface; Step 32: Purge the reaction chamber with inert gas to remove residual tin source precursor and gaseous byproducts from the reaction chamber; Step 33: Pulsely introduce oxygen source precursor into the reaction chamber; Step 34: Purge the reaction chamber again with inert gas to remove any remaining mixed oxygen source and reaction byproducts. In the first N1 cycles of the deposition process, the pulse time of the oxygen source precursor increases linearly from the initial value to the final value as the number of cycles increases, where N1 is an integer between 20 and 40, the initial value is 1 to 3 seconds, and the final value is 7 to 9 seconds; Step 4: After completing the first N1 cycles, the pulse duration of the oxygen source precursor in the subsequent N2 cycles remains at the final value until the deposited SnO is achieved. X The film reaches the target thickness; Where N2 is an integer between 40 and 60.

2. The method for preparing the electron transport layer thin film of a perovskite solar cell as described in claim 1, characterized in that, The oxygen source precursor is water, the initial value is 2 seconds, the final value is 8 seconds, N1 is 30, and N2 is 50.

3. The method for preparing the electron transport layer thin film of a perovskite solar cell as described in claim 2, characterized in that, The pulse duration of the oxygen source precursor starts at 2 seconds and increases linearly by 2 seconds every 10 cycles, reaching 8 seconds at the 30th cycle; the pulse duration of the oxygen source precursor is maintained at 8 seconds for the subsequent 50 cycles.

4. The method for preparing the electron transport layer thin film of a perovskite solar cell as described in claim 1, characterized in that, The metal precursor is tetramethylaminotin, and the pulse time remains constant during the atomic layer deposition cycle.

5. A method for fabricating perovskite solar cells, characterized in that: The steps are as follows: Step 1: Provide a conductive glass substrate, clean and dry it, and then perform P1 laser scribing; Step 2: Deposit a hole transport layer on the substrate; Step 3: Deposit a perovskite light-absorbing layer on the hole transport layer; Step 4: Perform interface modification on the perovskite light-absorbing layer and deposit the first electron transport layer; Step 5: Using the electron transport layer thin film preparation method as described in any one of claims 1 to 4, deposit SnO on the first electron transport layer. X The thin film serves as the second electron transport layer; Step 6: Perform P2 laser scribing to expose the bottom conductive electrodes; Step 7: Perform P3 laser scribing and deposit the metal top electrode to complete the battery fabrication.

6. The method for preparing a perovskite solar cell as described in claim 5, characterized in that, In step 2, NiO is deposited by magnetron sputtering. X The thin film serves as a hole transport layer.

7. The method for preparing a perovskite solar cell as described in claim 5, characterized in that, In step 3, slit coating is used to coat FA. 0.83 Cs 0.17 PbI 2.8 Cl 0.2 The perovskite precursor solution is coated onto the substrate at a rate of 3-5 cm / s, followed by vacuum flash evaporation for 16-20 seconds and annealing at 140-160°C for 28-32 minutes to form a perovskite thin film, i.e., a perovskite light-absorbing layer.

8. The method for preparing a perovskite solar cell as described in claim 5, characterized in that, In step 4, the slit is coated with PEAI solution and annealed, followed by thermal evaporation deposition of a C layer 18-22 nm thick. 60 It serves as the first electron transport layer.

9. A perovskite solar cell, characterized in that, The perovskite solar cell is prepared by the method described in any one of claims 5 to 8.

10. The application of electron transport layer thin films in the fabrication of perovskite solar cells, characterized in that, The electron transport layer thin film is prepared by the electron transport layer thin film preparation method according to any one of claims 1 to 4.

Images