Perovskite photovoltaic cell and method of making same and ald deposition apparatus

Abstract

This invention discloses a perovskite photovoltaic cell, its fabrication method, and an ALD deposition apparatus. The perovskite photovoltaic cell includes a conductive substrate, a metal anode, a hole transport layer, a perovskite light-absorbing layer, an electron transport layer, a hole blocking layer, and a metal cathode, stacked sequentially. The hole blocking layer comprises a first tin oxide layer bonded to the electron transport layer and a second tin oxide layer disposed between the first tin oxide layer and the metal cathode. The first tin oxide layer is an oxygen-rich tin oxide film deposited using a time-dependent ALD process; the second tin oxide layer is a highly crystalline tin oxide film deposited using a spatial ALD process; the thickness of the first tin oxide layer is less than the thickness of the second tin oxide layer. The perovskite photovoltaic cell of this application achieves a synergistic balance between the interface quality between the hole blocking layer and the electron transport layer and the fabrication efficiency of the hole blocking layer, which is beneficial for the widespread application of perovskite photovoltaic cells.

Description

Technical Field

[0001] This invention relates to the field of perovskite photovoltaic technology, and in particular to a perovskite photovoltaic cell, its preparation method, and an ALD deposition apparatus. Background Technology

[0002] With the continuous development of perovskite photovoltaic technology, perovskite photovoltaic cells and modules are widely recognized as an important development direction for next-generation high-efficiency photovoltaic technology due to their excellent photoelectric conversion efficiency, solution-processable characteristics, and low-cost fabrication advantages. In perovskite photovoltaic devices, the hole blocking layer plays a crucial role in electron extraction, hole blocking, interface passivation, and stability improvement. Its microstructure and fabrication process directly affect device efficiency and industrialization feasibility. Atomic layer deposition (ALD) technology, with its advantages of precise controllable atomic-level thickness and excellent film uniformity, has become an important technique for preparing tin oxide hole blocking layers.

[0003] Currently, tin oxide is commonly used as a hole-blocking layer in perovskite photovoltaic devices. The mainstream fabrication processes fall into two categories: Time-separated atomic layer deposition (ALD) achieves atomically precise growth, resulting in excellent film interface quality and fewer defects, which is beneficial for improving device efficiency. However, the deposition process is time-consuming and cannot be adapted for continuous production of large-size substrates such as G12. Spatial atomic layer deposition (SALD) offers advantages such as high throughput and large-area film formation, with outstanding mass production capabilities. However, due to limitations in the growth mechanism, it suffers from more film interface defects, and in C... 60 (Electron transport layer of perovskite photovoltaic cell) Hydrophobic surfaces are prone to nucleation delay, which ultimately leads to a decrease in the performance and stability of large-area devices.

[0004] Therefore, how to achieve both high-quality interface control and high-efficiency large-scale preparation of tin oxide hole blocking layers in perovskite photovoltaic cells is a technical problem that needs to be solved by those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to provide a perovskite photovoltaic cell, its preparation method, and an ALD deposition device, which can achieve both high-quality interface control of the tin oxide hole blocking layer and high-efficiency large-scale preparation, thus facilitating the widespread application of perovskite photovoltaic cells.

[0006] To solve the above-mentioned technical problems, the present invention provides a perovskite photovoltaic cell, comprising a conductive substrate, a metal anode, a hole transport layer, a perovskite light absorption layer, an electron transport layer, a hole blocking layer, and a metal cathode stacked sequentially.

[0007] The hole blocking layer comprises a first tin oxide layer that is bonded to the electron transport layer, and a second tin oxide layer disposed between the first tin oxide layer and the metal cathode.

[0008] The first tin oxide layer is an oxygen-rich tin oxide thin film deposited using a time-dependent ALD process;

[0009] The second tin oxide layer is a highly crystalline tin oxide thin film deposited using a spatial ALD process;

[0010] The thickness of the first tin oxide layer is less than the thickness of the second tin oxide layer.

[0011] In one embodiment, the grain size of the first tin oxide layer is smaller than the grain size of the second tin oxide layer.

[0012] In one embodiment, the hole blocking layer has a thickness of 8 nm to 12 nm; the first tin oxide layer has a film thickness of 2 nm to 4 nm; and the second tin oxide layer has a film thickness of 6 nm to 8 nm.

[0013] In one embodiment, the first tin oxide layer is oxygen-rich. Thin film; the second tin oxide layer is highly crystalline. film.

[0014] In one embodiment, the electron transport layer is C 60 layer.

[0015] A method for preparing a perovskite photovoltaic cell, comprising:

[0016] The pre-prepared main structure layer is placed in the ALD reaction chamber; wherein, the main structure layer includes a conductive substrate, a metal anode, a hole transport layer, a perovskite light absorption layer, and an electron transport layer stacked sequentially;

[0017] A first tin oxide layer is deposited on the electron transport layer using a time-dependent ALD process;

[0018] When the thickness of the first tin oxide layer reaches the target thickness range, the spatial ALD process is switched to deposit a second tin oxide layer on the first tin oxide layer.

[0019] A metal cathode is fabricated on a hole-blocking layer composed of the first tin oxide layer and the second tin oxide layer to obtain a perovskite photovoltaic cell.

[0020] In one embodiment, the electron transport layer is C 60 layer;

[0021] Accordingly, after placing the pre-prepared host structure layer in the ALD reaction chamber, and before depositing the first tin oxide layer on the electron transport layer using a time-based ALD process, the process further includes:

[0022] Water vapor is continuously introduced into the ALD reaction chamber for 15-30 seconds, followed by purging with high-purity nitrogen for at least 8 seconds to react with the C. 60 The surface of the layer is modified.

[0023] In one embodiment, a time-dependent ALD process is used to deposit a first tin oxide layer on the electron transport layer, including:

[0024] The ALD gas delivery assembly is controlled to deposit the first tin oxide layer on the electron delivery layer according to the time-type ALD process mode;

[0025] When the deposition time of the first tin oxide layer on the electron transport layer reaches the set time, the thickness of the currently deposited first tin oxide layer is detected by an online ellipsometry to obtain the current film thickness.

[0026] Determine whether the current film thickness has reached the target thickness range;

[0027] If the current film thickness does not reach the target thickness range, the ALD gas delivery assembly is controlled to redeposit the first tin oxide layer on the electron delivery layer according to the time-type ALD process mode until the film thickness of the first tin oxide layer reaches the target thickness range.

[0028] If the current film thickness reaches the target thickness range, the ALD gas delivery component is controlled to switch to a spatial ALD process mode to perform the operation of depositing a second tin oxide layer on the first tin oxide layer using a spatial ALD process.

[0029] An ALD deposition apparatus includes an ALD reaction chamber, an online ellipsomer, an ALD gas delivery assembly, and a control unit;

[0030] The ALD reaction chamber is used to accommodate the pre-prepared main structural layer; the main structural layer is the pre-structure layer of the perovskite photovoltaic cell without deposited hole blocking layer and metal cathode;

[0031] The online ellipsometer is installed inside the ALD reaction chamber and is communicatively connected to the control unit;

[0032] The control unit is used to control the ALD gas delivery assembly to deposit a first tin oxide layer on the electron transport layer of the main structure layer using a time-type ALD process, and to use the online ellipsometer to detect the film thickness of the first tin oxide layer. When the film thickness reaches the target thickness range, the control unit switches the ALD gas delivery assembly to deposit a second tin oxide layer on the first tin oxide layer using a space-type ALD process, so as to form a hole blocking layer formed by the first tin oxide layer and the second tin oxide layer.

[0033] In one embodiment, the ALD gas delivery assembly includes a spray plate disposed in the ALD reaction chamber, and a tin source storage unit, a nitrogen storage unit, and an oxygen source storage unit connected to the spray plate via a gas delivery pipe.

[0034] The spray plate includes multiple sets of repeating spray units, and each spray unit includes tin source spray port, nitrogen spray port, oxygen source spray port and nitrogen spray port arranged in sequence.

[0035] The present invention provides a perovskite photovoltaic cell, a method for its fabrication, and an ALD deposition apparatus. The perovskite photovoltaic cell includes a conductive substrate, a metal anode, a hole transport layer, a perovskite light-absorbing layer, an electron transport layer, a hole blocking layer, and a metal cathode, which are stacked sequentially. The hole blocking layer comprises a first tin oxide layer bonded to the electron transport layer and a second tin oxide layer disposed between the first tin oxide layer and the metal cathode. The first tin oxide layer is an oxygen-rich tin oxide thin film deposited using a time-dependent ALD process. The second tin oxide layer is a highly crystalline tin oxide thin film deposited using a space-dependent ALD process. The thickness of the first tin oxide layer is less than the thickness of the second tin oxide layer.

[0036] In the perovskite photovoltaic cell of this application, the hole blocking layer comprises an oxygen-rich tin oxide film deposited using a time-dependent ALD process and a highly crystalline tin oxide film deposited using a spatial ALD process. The oxygen-rich tin oxide film is directly bonded to the electron transport layer, effectively reducing the defect state density at the interface between the electron transport layer and the hole blocking layer, reducing carrier non-radiative recombination losses, and thus improving the open-circuit voltage of the photovoltaic cell. The highly crystalline tin oxide film effectively scatters and blocks the reverse migration of holes, forming a high hole barrier. Furthermore, the second tin oxide layer is deposited using a spatial ALD process, allowing the main thickness of the hole blocking layer to be completed quickly using the spatial ALD process, significantly reducing the time required for the time-dependent ALD process and thus greatly shortening the overall deposition time. Therefore, the first and second tin oxide layers in this application together form the hole blocking layer, achieving a synergistic balance between the interface quality between the hole blocking layer and the electron transport layer and the preparation efficiency of the hole blocking layer, which is beneficial for the widespread application of perovskite photovoltaic cells. Attached Figure Description

[0037] To more clearly illustrate the technical solutions of the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 A cross-sectional structural schematic diagram of a perovskite photovoltaic cell provided in an embodiment of this application;

[0039] Figure 2 A schematic diagram showing the comparison of tin oxide grains deposited by time-based ALD and space-based ALD processes, respectively.

[0040] Figure 3 SEM comparison images of tin oxide films deposited by three different processes provided in the embodiments of this application;

[0041] Figure 4 AFM comparison images of tin oxide films deposited by two different processes provided in the embodiments of this application;

[0042] Figure 5 A schematic flowchart illustrating the fabrication method of perovskite photovoltaic cells provided in the embodiments of this application;

[0043] Figure 6 This is a schematic cross-sectional view of the ALD deposition apparatus provided in an embodiment of this application.

[0044] In the attached figures: 11 is a conductive substrate, 12 is a metal anode, 13 is a hole transport layer, 14 is a perovskite light absorption layer, 15 is an electron transport layer, 16 is a hole blocking layer, 161 is a first tin oxide layer, 162 is a second tin oxide layer, 17 is a metal cathode, 21 is an ALD reaction chamber, 210 is a light-transmitting window, 22 is an ALD gas supply assembly, 220 is a spray plate, 221 is a tin source storage unit, 222 is a nitrogen storage unit, 223 is an oxygen source storage unit, 23 is a control unit, 24 is a transfer platform, and 25 is an online ellipsometer. Detailed Implementation

[0045] The core of this invention is to provide a perovskite photovoltaic cell, its preparation method, and an ALD deposition device, which achieves a synergistic balance between the interface quality between the hole blocking layer and the electron transport layer in the perovskite photovoltaic cell, as well as the preparation efficiency of the hole blocking layer, thus facilitating the widespread application of perovskite photovoltaic cells.

[0046] To enable those skilled in the art to better understand the present invention, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are merely 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.

[0047] like Figure 1 As shown, Figure 1 This is a cross-sectional structural diagram of a perovskite photovoltaic cell provided in an embodiment of this application.

[0048] In one specific embodiment of this application, the perovskite photovoltaic cell may include:

[0049] A conductive substrate 11, a metal anode 12, a hole transport layer 13, a perovskite light absorption layer 14, an electron transport layer 15, a hole blocking layer 16, and a metal cathode 17 are stacked sequentially.

[0050] The hole blocking layer 16 includes a first tin oxide layer 161 that is bonded to the electron transport layer 15, and a second tin oxide layer 162 disposed between the first tin oxide layer 161 and the metal cathode 17.

[0051] The first tin oxide layer 161 is an oxygen-rich tin oxide thin film deposited using a time-type ALD process;

[0052] The second tin oxide layer 162 is a highly crystalline tin oxide thin film deposited using a spatial ALD process;

[0053] The thickness of the first tin oxide layer 161 is less than the thickness of the second tin oxide layer 162.

[0054] In this embodiment, the conductive substrate 11 can be a transparent conductive oxide glass, such as FTO (fluorine-doped tin oxide) glass or ITO (indium-doped tin oxide) glass; the metal anode 12 and the metal cathode 17 can be prepared by magnetron sputtering, and the material can be gold, silver, aluminum, or transparent conductive oxide, etc.; the hole transport layer 13 can be an organic or inorganic hole transport material such as NiOx (inorganic nickel oxide), Spiro-OMeTAD, or PTAA. The perovskite light absorption layer 14 can be an ABX3 type perovskite material, wherein the A site can be Cs. + FA + (Formamidinium cation), MA + (Methylamine cation); the B site can be Pb 2+ The X bit can be I. - ,Br - Cl -Halogen anions; for example, the perovskite light-absorbing layer 14 can be such as FA 1-x MA x PbI3 or Cs 0.05 (FA 0.85 MA0.15) 0.95 Pb(I 0.85 Br 0.15 )3, etc.; In addition, the electron transport layer 15 in this embodiment can be C prepared by vapor deposition. 60 layer.

[0055] Based on this, the hole blocking layer 16 disposed between the electron transport layer 15 and the metal cathode 17 may be formed by a first tin oxide layer 161 and a second tin oxide layer 162; wherein, the first tin oxide layer 161 is an oxygen-rich tin oxide thin film deposited by a time-type ALD process.

[0056] The essential characteristic of the T-ALD process lies in its layer-by-layer atomic-level growth, with only about one atomic layer thickness deposited per cycle. The growth process is controlled by surface self-limiting chemical reactions. This growth mechanism determines that the first tin oxide layer 161 formed by T-ALD deposition has the advantages of fine and uniform grains, high density, and excellent step coverage. When the first tin oxide layer 161 is directly deposited on the surface of the electron transport layer 15, its atomic-level layer-by-layer growth mode can achieve precise nucleation and dense adhesion on the substrate surface, forming an ultra-thin capping layer without pinholes. The direct deposition of the first tin oxide layer 161 on the surface of the electron transport layer 15 provides a high-quality contact interface between the hole blocking layer 16 and the electron transport layer 15, avoiding the adverse effects of oxygen vacancy defects on the interface of the electron transport layer 15.

[0057] Furthermore, the first tin oxide layer 161 is an oxygen-rich tin oxide film, meaning that the ratio of oxygen atoms to tin atoms in the first tin oxide layer 161 is relatively high. This oxygen-rich tin oxide film is thus classified as oxygen-rich. Taking thin films as an example, that is In the region where the x-value is close to 2 or slightly above the stoichiometric ratio, this oxygen-rich tin oxide film contains abundant active oxygen species. Oxygen vacancies on the surface of the electron transport layer 15 and at adjacent interfaces are the main non-radiative recombination centers and key defect sources leading to device voltage loss. When the oxygen-rich tin oxide film is bonded to the electron transport layer 15, its abundant active oxygen species can migrate to the interface, filling the oxygen vacancy defects and achieving chemical passivation. Simultaneously, the oxygen-rich... The thin film itself has fewer intrinsic oxygen vacancies and a low defect state density. Therefore, in this embodiment, the oxygen-rich tin oxide thin film in the hole blocking layer 16 is in direct contact with the electron transport layer 15, which can achieve chemical passivation of the interface between the electron transport layer 15 and the hole blocking layer 16, effectively reducing the interface defect state density, reducing carrier non-radiative recombination loss, and helping to improve the open-circuit voltage of the perovskite photovoltaic cell.

[0058] Furthermore, the second tin oxide layer 162 is a highly crystalline tin oxide layer prepared using a spatial ALD deposition process. Due to its higher growth rate, the tin oxide film deposited by the SALD process allows for more time for grain growth, resulting in a highly crystalline film structure with large grains, specifically a highly crystalline SnO2 film. The high crystallinity of the highly crystalline tin oxide film means a high film density, clear and continuous grain boundaries, which can effectively scatter and block the reverse migration of holes, forming a high hole barrier. In addition, the dense crystalline film layer of this highly crystalline tin oxide film can act as a physical protective layer, preventing the inward diffusion of external water vapor molecules and the outward migration of internal lead ions.

[0059] In addition, the thickness of the first tin oxide layer 161 in the hole blocking layer 16 is less than the thickness of the second tin oxide layer 162. In practical applications, the thickness of the first tin oxide layer 161 in the hole blocking layer 16 should not exceed one-third of the total thickness of the hole blocking layer 16.

[0060] Taking a hole blocking layer 16 with a total thickness of 8nm~12nm as an example, the thickness of the first tin oxide layer 161 is 2nm~4nm, and the thickness of the second tin oxide layer 162 is 6nm~8nm. That is to say, in the hole blocking layer 16 of this embodiment, although the deposition speed of the first tin oxide layer 161 is relatively slow due to the use of time-type ALD process, the required deposition thickness is relatively thin, thus avoiding excessive deposition time for the first tin oxide layer 161. The second tin oxide layer 162 is relatively thicker and occupies the main thickness of the hole blocking layer 16, but because it is rapidly deposited using spatial ALD process, the overall deposition time of the entire hole blocking layer 16 is significantly shortened.

[0061] Furthermore, in this embodiment, the grain size of the first tin oxide layer 161 is much smaller than the grain size of the second tin oxide layer 162.

[0062] like Figure 2 As shown, Figure 2 A comparison of tin oxide grains deposited by time-dependent ALD process and tin oxide grains deposited by spatial ALD process clearly shows that the grain size of tin oxide deposited by time-dependent ALD process is much smaller than that of tin oxide deposited by spatial ALD process.

[0063] like Figure 3 As shown, in the SEM images of tin oxide films formed by a single spatial ALD process, the film grain size is relatively large, with many grain boundary gaps, which easily form charge recombination and water vapor permeation channels. In the SEM images of tin oxide films formed by a single temporal ALD process, the grains are fine and uniform, but the overall film density is insufficient, resulting in limited protective barrier capabilities. In the SEM images of composite tin oxide films formed by temporal and spatial ALD processes, the film combines the advantages of fine bottom-layer grains and dense top-layer grains, significantly reducing grain boundary gaps and exhibiting a continuous surface without obvious defects. This allows for simultaneous passivation of interface defects and efficient water vapor and ion barrier, effectively reducing non-radiative recombination at the device interface and improving the photoelectric conversion efficiency and long-term operational stability of photovoltaic modules formed by large-area perovskite photovoltaic cells.

[0064] like Figure 4 As shown, in the AFM (Atomic Force Microscope) image of the tin oxide thin film deposited by a single spatial ALD process, the film grains are coarse and undulating, with a root mean square roughness (RMS) as high as 10.36 nm. The rough surface is prone to generating a large number of interface contact defects, which exacerbates the nonradiative recombination of charge carriers. In the AFM image of the composite tin oxide thin film formed by time-type ALD and spatial ALD processes, the film grains are fine and uniform, the surface undulations are significantly reduced, and the RMS is only 7.38 nm. The flat and continuous film layer can achieve atomic-level adhesion with the lower electron transport layer 15, greatly reducing the interface defect sites and effectively suppressing charge recombination. At the same time, the flat film can improve the performance uniformity of photovoltaic modules formed by large-area perovskite photovoltaic cells.

[0065] As shown in Table 1 below, the hole blocking layer in the perovskite photovoltaic device corresponding to Comparative Example 1 in Table 1 is a tin oxide layer deposited using a time-type ALD process, and the hole blocking layer in the perovskite photovoltaic device corresponding to Comparative Example 2 is a tin oxide layer deposited using a spatial ALD process. The hole blocking layer in the perovskite photovoltaic device corresponding to Example 1 is formed by depositing a first tin oxide film layer using a time-type ALD process and then depositing a second tin oxide film layer using a spatial ALD process, as mentioned in the above embodiments of this application.

[0066] Table 1 Performance test data of perovskite photovoltaic devices

[0067] Comparative Example 1 258.21 26.348 69.82 18.80 Comparative Example 2 255.98 25.044 62.22 15.79 Example 1 260.8 27.66 64.52 18.42

[0068] As shown in Table 1 above, comparing the performance data of perovskite photovoltaic devices formed by three different processes for creating hole blocking layers, it is clear that the perovskite photovoltaic device formed by the hole blocking layer deposited using both time-based and space-based ALD processes in this application has comparable power generation performance to the perovskite photovoltaic device formed by depositing the hole blocking layer using only the time-based ALD process. However, the deposition efficiency of the hole blocking layer formed by using two different deposition processes in this application is significantly improved compared to using only the time-based ALD process. Therefore, this application can simultaneously achieve both power generation performance and deposition efficiency of perovskite photovoltaic cells.

[0069] Based on the above discussion, the hole blocking layer 16 in this embodiment consists of a first tin oxide layer 161 and a second tin oxide layer 162 sequentially deposited on the electron transport layer 15. The first tin oxide layer 161 establishes a high-quality interface contact and defect passivation with the electron transport layer 15, while the second tin oxide layer 162 undertakes the construction of a hole barrier and physical protection. Together, they constitute the complete function of the hole blocking layer 16. Furthermore, only the time-type ALD process with a slow deposition rate is used to deposit the ultra-thin first tin oxide layer 161, resulting in a short process time. The second tin oxide layer 162, which accounts for the majority of the thickness, is deposited using the space-type ALD process with a high deposition rate, thereby ensuring the overall deposition rate of the hole blocking layer 16. This achieves a balance between high-quality interface control and high-efficiency fabrication of the tin oxide thin film as the hole blocking layer 16.

[0070] In summary, the hole-blocking layer in this application comprises an oxygen-rich tin oxide film deposited using a time-dependent ALD process and a highly crystalline tin oxide film deposited using a spatial ALD process. The oxygen-rich tin oxide film is directly bonded to the electron transport layer, effectively reducing the defect state density at the interface between the electron transport layer and the hole-blocking layer, reducing non-radiative recombination losses of charge carriers, and thus improving the open-circuit voltage of the photovoltaic cell. The highly crystalline tin oxide film effectively blocks the reverse migration of holes, forming a high hole barrier. Furthermore, the second tin oxide layer is deposited using a spatial ALD process, allowing the main thickness of the hole-blocking layer to be rapidly achieved by the spatial ALD process, significantly reducing the time required for the time-dependent ALD process and thus greatly shortening the overall deposition time. Therefore, the first and second tin oxide layers in this application together form the hole-blocking layer, achieving a synergistic balance between the interface quality between the hole-blocking layer and the electron transport layer and the preparation efficiency of the hole-blocking layer, which is beneficial for the widespread application of perovskite photovoltaic cells.

[0071] In one embodiment of this application, a method for preparing a perovskite photovoltaic cell is also provided. It is understood that the method for preparing the perovskite photovoltaic cell can also be used to prepare the perovskite photovoltaic cell as described in any of the preceding claims.

[0072] like Figure 5 and Figure 6 As shown, Figure 5 A schematic flowchart illustrating the fabrication method of perovskite photovoltaic cells provided in the embodiments of this application; Figure 6 This is a schematic cross-sectional view of the ALD deposition apparatus provided in an embodiment of this application. The fabrication method of this perovskite photovoltaic cell may include:

[0073] S1: The pre-prepared main structure layer is placed in the ALD reaction chamber; wherein, the main structure layer includes a conductive substrate, a metal anode, a hole transport layer, a perovskite light absorption layer, and an electron transport layer stacked sequentially;

[0074] S2: A first tin oxide layer 161 is deposited on the electron transport layer using a time-dependent ALD process;

[0075] S3: When the thickness of the first tin oxide layer reaches the target thickness range, switch to the spatial ALD process to deposit the second tin oxide layer on the first tin oxide layer;

[0076] S4: A metal cathode is fabricated on the hole blocking layer 16, which is composed of the first tin oxide layer and the second tin oxide layer, to obtain a perovskite photovoltaic cell.

[0077] The process for preparing the main structural layer and metal cathode 17 in the perovskite photovoltaic cell in this embodiment can refer to the conventional preparation process. Therefore, this embodiment does not impose any specific limitations on this process.

[0078] After the main structural layer of the perovskite photovoltaic cell is formed, it can be placed in the ALD reaction chamber 21. The large-area substrate is then stably fixed at the equipment transfer station. After sealing the ALD reaction chamber 21, high-purity nitrogen is continuously introduced to replace the air in the chamber. The oxygen content and water vapor content in the chamber are controlled within 1 ppm. The deposition temperature in the chamber is maintained at around 100 ℃ throughout the process, with temperature fluctuations not exceeding ±2 ℃, to prevent thermal damage to the organic functional layer.

[0079] Furthermore, the electron transport layer 15 in this embodiment can be C 60 Accordingly, after obtaining the main structure of the perovskite photovoltaic cell in S1 above, and before performing S2 above, water vapor can be continuously introduced into the ALD reaction chamber 21 for 15s~30s, and then purged with high-purity nitrogen for no less than 8s to remove C. 60 The surface of the layer is modified. A small amount of water vapor is introduced into the ALD reaction chamber 21 to perform C… 60 Surface activation of the layer, with the activation time controlled between 5 and 10 seconds, utilizes water vapor in the hydrophobic C layer. 60Active sites are introduced on the surface of the layer to improve the problem of delayed tin oxide nucleation. After activation, high-purity nitrogen is purged for 10 seconds to remove residual water vapor from the cavity.

[0080] Based on this, in S2 of this embodiment, the process of depositing the first tin oxide layer 161 using a time-dependent ALD process may include:

[0081] Tetra(dimethylamino)tin (TDMASn) was used as the tin source precursor, deionized water as the oxygen source, and high-purity nitrogen as the carrier and purging gas. Different chemical gases were sequentially introduced into the ALD reaction chamber 21 containing the main structure using a cyclic process. The process parameters for a single cycle could be set as follows: the pulse width of the precursor was 3.0s~6.0s, the pulse width of the nitrogen purging was 10s~20s, the pulse width of the oxygen source (deionized water vapor) was 1.0s~3.0s, and the pulse width of the nitrogen purging was 10s~20s. That is to say, the process involves first introducing tin source precursor for 3.0s~6.0s, then introducing nitrogen gas for 10s~20s for purging, then introducing oxygen source gas (deionized water vapor) for 1.0s~3.0s, and then introducing nitrogen gas for 10s~20s for purging. After completing one cycle, the same process is repeated about 20~40 times, or the cycle is repeated for a set duration.

[0082] In another embodiment, the process of depositing and forming the first tin oxide layer 161 may further include:

[0083] S21: Control the ALD gas delivery assembly to deposit the first tin oxide layer on the electron transport layer according to the time-type ALD process mode;

[0084] S22: When the deposition time of the first tin oxide layer on the electron transport layer reaches the set time, the thickness of the currently deposited first tin oxide layer is detected by an online ellipsometry to obtain the current film thickness.

[0085] S33: Determine whether the current film thickness has reached the target thickness range;

[0086] S34: If the current film thickness has not reached the target thickness range, control the ALD gas delivery component to re-deposit the first tin oxide layer on the electron delivery layer according to the time-type ALD process mode until the film thickness of the first tin oxide layer reaches the target thickness range.

[0087] S35: If the current film thickness reaches the target thickness range, control the ALD gas transmission component to switch to the spatial ALD process mode to perform the operation of depositing a second tin oxide layer on the first tin oxide layer using the spatial ALD process.

[0088] In practical applications, linear ellipticity monitoring technology can be used to monitor and provide feedback on the thickness of the first tin oxide film in real time, thereby achieving atomic-level precise control of the film thickness. The thickness deviation between batches is less than 1%, meeting the requirements of large-area continuous production. The specific process is as follows:

[0089] When the online ellipsometry 25 detects that the film thickness of the first tin oxide layer 161 has reached the target thickness range, the control unit 23 receives the monitoring signal and outputs the process switching trigger signal; first, the time-type ALD gas path is closed, and the nitrogen isolation purging gas path is opened to continuously purge the chamber for 8s~15s to fully remove the residual precursors and reaction byproducts in the ALD reaction chamber 21; after the purging is completed, the equipment automatically switches the gas path and operating mode, and starts the spatial ALD process mode. The entire switching process takes about 12s in total, without opening the chamber or breaking the vacuum, to avoid the introduction of external impurities and interface contamination.

[0090] It is understood that in the above preparation method, each process parameter (such as precursor pulse time, purge time, deposition temperature, substrate moving speed, target film thickness, etc.) can be appropriately adjusted according to the specific size, equipment model and performance requirements of the actual perovskite photovoltaic cell, and this application does not impose any special restrictions on this.

[0091] After the time-based ALD process is completed, the system automatically switches to the space-based ALD process mode without breaking the vacuum. At this time, the main structural layer moves at a constant speed (e.g., 1 mm / s to 20 mm / s) within the ALD reaction chamber 21, reciprocating below the gas outlet. Different gases are output from the gas outlets within the ALD reaction chamber 21, arranged in a cyclical pattern according to the order of the tin source spray unit, N2 isolation zone, oxygen source spray unit, and N2 isolation zone. Specifically, the flow rate of the tin source precursor sprayed by the tin source spray unit can be 80 sccm to 120 sccm, the flow rate of nitrogen sprayed by the N2 isolation zone can be 150 sccm to 250 sccm, and the flow rate of deionized water vapor sprayed by the oxygen source spray unit can be 100 sccm to 150 sccm. When the linear ellipticity monitoring unit detects that the total film thickness of the hole-blocking layer 16 reaches 8 nm to 12 nm, the control unit 23 automatically cuts off the gas paths corresponding to the tin and oxygen sources, terminating the deposition of the hole-blocking layer 16.

[0092] After the hole blocking layer 16 is deposited, high-purity nitrogen can be continuously purged into the nitrogen isolation zone for about 3 minutes to remove residual gas and reaction byproducts in the ALD reaction chamber 21. Annealing and cooling can be carried out under a nitrogen atmosphere at 60℃~80℃ for 10 to 30 minutes to further improve the density of the gradient film and the interlayer bonding strength. The annealing temperature should not be too high to prevent thermal decomposition of the perovskite light absorption layer 14. Rapid cooling is strictly prohibited to prevent stress cracks in the film.

[0093] It is understood that the key to this embodiment lies in the sequential deposition of a first tin oxide layer 161 and a second tin oxide layer 162 on the electron transport layer 15 using time-type ALD and space-type ALD processes. The first tin oxide layer 161 is an oxygen-rich tin oxide film, while the second tin oxide layer 162 is a highly crystalline tin oxide film. The first tin oxide layer 161 and the second tin oxide layer 162 together form the hole blocking layer 16 in the perovskite photovoltaic cell. Furthermore, the film thickness of the first tin oxide layer 161 is less than the film thickness of the second tin oxide layer 162, thereby achieving a synergistic balance between the interface quality between the hole blocking layer 16 and the electron transport layer and the fabrication efficiency of the hole blocking layer 16 in the perovskite photovoltaic cell.

[0094] Based on the above discussion, such as Figure 6 As shown, this application also provides an embodiment of an ALD deposition apparatus, which may include:

[0095] ALD reaction chamber 21, ALD gas delivery assembly 22, online ellipsomer 25 and control unit 23;

[0096] ALD reaction chamber 21 is used to accommodate the pre-prepared main structural layer; the main structural layer is the pre-structure layer of the perovskite photovoltaic cell undeposited hole blocking layer 16 and metal cathode 17;

[0097] The online ellipsometer 25 is installed inside the ALD reaction chamber 21 and is communicatively connected to the control unit 23;

[0098] The control unit 23 controls the ALD gas delivery assembly 22 to deposit a first tin oxide layer 161 on the electron transport layer of the main structure layer using a time-type ALD process, and uses an online ellipsometry 25 to detect the film thickness of the first tin oxide layer. When the film thickness reaches the target thickness range, the control unit 23 switches the ALD gas delivery assembly 22 to deposit a second tin oxide layer 162 on the first tin oxide layer 161 using a space-type ALD process, so as to form a hole blocking layer 16 formed by the first tin oxide layer 161 and the second tin oxide layer 162.

[0099] In this embodiment, the ALD reaction chamber 21 is used to accommodate the pre-prepared main structure layer, which is the pre-structure layer of the perovskite photovoltaic cell before the hole blocking layer 16 and the metal cathode 17 are deposited, that is, the substrate on which the conductive substrate 11, the metal anode 12, the hole transport layer 13, the perovskite light absorption layer 14 and the electron transport layer 15 have been prepared.

[0100] The control unit 23 is communicatively connected to the ALD gas delivery assembly 22 and is specifically used to: control the ALD gas delivery assembly 22 to deposit a first tin oxide layer 161 on the electron transport layer 15 of the main structure layer according to the time-type ALD process mode; after the thickness of the first tin oxide layer 161 reaches a preset value, control the ALD gas delivery assembly 22 to switch to the space-type ALD process mode and deposit a second tin oxide layer 162 on the first tin oxide layer 161; finally, a hole blocking layer 16 is formed by the first tin oxide layer 161 and the second tin oxide layer 162.

[0101] Furthermore, the ALD reaction chamber 21 in this embodiment may be equipped with an online ellipsometer 25. For example... Figure 6 As shown, a light-transmitting window 210 can be provided on one side of the ALD reaction chamber 21, while an online ellipsometer 25 is provided on the other side of the ALD reaction chamber 21. Thus, an infrared monitoring light source located outside the ALD reaction chamber 21 is incident into the ALD reaction chamber 21 through the light-transmitting window 210. After being reflected by the first tin oxide layer 161, the infrared monitoring light is incident on the online ellipsometer 25. Based on the received light, the online ellipsometer 25 obtains monitoring data, thereby determining the data characterizing the film thickness.

[0102] The control unit 23 is connected to the online ellipticmeter 25. The online ellipticmeter 25 is integrated to realize real-time monitoring and feedback of film thickness. The control unit 23 automatically decides the timing of process switching based on the monitoring data without manual intervention, which effectively improves process repeatability and mass production stability.

[0103] In this embodiment, the control unit 23 can be an industrial computer, a programmable logic controller (PLC), or an embedded control system. It has a time-based ALD deposition program and a spatial ALD deposition program preset inside, as well as automatic switching logic between the two modes.

[0104] Based on this, the ALD gas delivery assembly 22 in this embodiment may include a spray plate 220 disposed in the ALD reaction chamber 21, and a tin source storage unit 221, a nitrogen storage unit 222 and an oxygen source storage unit 223 connected to the spray plate 220 through a gas delivery pipe.

[0105] The spray plate 220 includes multiple sets of repeating spray units, each of which includes tin source spray port, nitrogen spray port, oxygen source spray port and nitrogen spray port arranged in sequence.

[0106] In this embodiment, the spray plate has more than 220 sets of repeatedly arranged spray units, and each spray unit includes a tin source spray area arranged in sequence. Isolation area, oxygen spray area The spray nozzles are arranged in an isolation zone and circulate along the moving direction of the substrate (main structural layer) on the conveyor platform 24 on the spray plate 220. Each spray nozzle is linearly distributed, with a width adapted to the width of the substrate. The spray plate 220 is connected to each air source via independent gas supply pipes, and each pipe is equipped with a mass flow controller (MFC) and pneumatic valves to achieve precise control and rapid switching of gas flow.

[0107] In addition, the ALD deposition equipment may also include a vacuum pump group and an exhaust gas treatment system to maintain the vacuum level in the chamber and treat reaction byproducts; the oxygen content and water vapor content in the chamber can be controlled within 1 ppm to ensure the purity of the thin film deposition.

[0108] Based on the above discussion, when the first tin oxide layer 161 needs to be deposited on the main structural layer, the control unit 23 controls the conveying platform 24 carrying the main structural layer to remain stationary, and controls the spray nozzles of the tin source spraying unit, N2 isolation zone, and oxygen source spraying unit to perform pulse spraying of the corresponding gas source according to the requirements of the time-type ALD process. That is, the tin source spraying nozzle is controlled to spray the tin source precursor for 3.0s~6.0s, the nitrogen spraying nozzle is controlled to spray nitrogen for 10s~20s, the oxygen source spraying nozzle is controlled to continuously spray oxygen source (deionized water vapor) with a pulse width of 3.0s~6.0s, and the nitrogen spraying nozzle is controlled to spray nitrogen for 10s~20s. This process is repeated 20~40 times.

[0109] When a second tin oxide layer 162 needs to be deposited on the first tin oxide layer 161, the control unit 23 controls the conveying platform 24 to drive the main structural layer to move back and forth at a constant speed below the spray plate 220. The conveying speed is adjustable from 1 mm / s to 20 mm / s to meet the deposition requirements of thin films of different thicknesses.

[0110] It is understood that the ALD deposition equipment in this application is not limited to the specific structure described above. For example, the number of spray units, the arrangement, and the gas path connection of the spray plate 220 can all be adjusted according to actual process requirements, as long as the integration and automatic switching of time-based ALD process and space-based ALD process can be achieved.

[0111] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that the elements inherent in a process, method, article, or apparatus that includes a list of elements are included. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. Additionally, portions of the technical solutions provided in the embodiments of this application that are consistent with the implementation principles of corresponding technical solutions in the prior art have not been described in detail to avoid excessive elaboration.

[0112] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the present invention.

Claims

1. A perovskite photovoltaic cell, characterized in that, It includes a conductive substrate, a metal anode, a hole transport layer, a perovskite light absorption layer, an electron transport layer, a hole blocking layer, and a metal cathode, which are stacked sequentially. The hole blocking layer comprises a first tin oxide layer that is bonded to the electron transport layer, and a second tin oxide layer disposed between the first tin oxide layer and the metal cathode. The first tin oxide layer is an oxygen-rich tin oxide thin film deposited using a time-dependent ALD process; The second tin oxide layer is a highly crystalline tin oxide thin film deposited using a spatial ALD process; The thickness of the first tin oxide layer is less than the thickness of the second tin oxide layer.

2. The perovskite photovoltaic cell as described in claim 1, characterized in that, The grain size of the first tin oxide layer is smaller than that of the second tin oxide layer.

3. The perovskite photovoltaic cell as described in claim 1, characterized in that, The hole blocking layer has a thickness of 8nm to 12nm; the first tin oxide layer has a film thickness of 2nm to 4nm; and the second tin oxide layer has a film thickness of 6nm to 8nm.

4. The perovskite photovoltaic cell as described in claim 1, characterized in that, The first tin oxide layer is oxygen-rich. Thin film; the second tin oxide layer is a highly crystalline SnO2 thin film.

5. The perovskite photovoltaic cell as described in claim 1, characterized in that, The electron transport layer is C. 60 layer.

6. A method for preparing a perovskite photovoltaic cell, characterized in that, include: The pre-prepared main structure layer is placed in the ALD reaction chamber; wherein, the main structure layer includes a conductive substrate, a metal anode, a hole transport layer, a perovskite light absorption layer, and an electron transport layer stacked sequentially; A first tin oxide layer is deposited on the electron transport layer using a time-dependent ALD process; When the thickness of the first tin oxide layer reaches the target thickness range, the spatial ALD process is switched to deposit a second tin oxide layer on the first tin oxide layer. A metal cathode is fabricated on a hole-blocking layer composed of the first tin oxide layer and the second tin oxide layer to obtain a perovskite photovoltaic cell.

7. The method for preparing a perovskite photovoltaic cell as described in claim 6, characterized in that, The electron transport layer is C. 60 layer; Accordingly, after placing the pre-prepared host structure layer in the ALD reaction chamber, and before depositing the first tin oxide layer on the electron transport layer using a time-based ALD process, the process further includes: Water vapor is continuously introduced into the ALD reaction chamber for 15-30 seconds, followed by purging with high-purity nitrogen for at least 8 seconds to react with the C. 60 The surface of the layer is modified.

8. The method for preparing a perovskite photovoltaic cell as described in claim 6, characterized in that, A first tin oxide layer is deposited on the electron transport layer using a time-dependent ALD process, comprising: The ALD gas delivery assembly is controlled to deposit the first tin oxide layer on the electron delivery layer according to the time-type ALD process mode; When the deposition time of the first tin oxide layer on the electron transport layer reaches the set time, the thickness of the currently deposited first tin oxide layer is detected by an online ellipsometry to obtain the current film thickness. Determine whether the current film thickness has reached the target thickness range; If the current film thickness does not reach the target thickness range, the ALD gas delivery assembly is controlled to redeposit the first tin oxide layer on the electron delivery layer according to the time-type ALD process mode until the film thickness of the first tin oxide layer reaches the target thickness range. If the current film thickness reaches the target thickness range, the ALD gas delivery component is controlled to switch to a spatial ALD process mode to perform the operation of depositing a second tin oxide layer on the first tin oxide layer using a spatial ALD process.

9. An ALD deposition apparatus, characterized in that, Includes the ALD reaction chamber, online ellipsometer, ALD gas delivery assembly, and control unit; The ALD reaction chamber is used to accommodate the pre-prepared main structural layer; the main structural layer is the pre-structure layer of the perovskite photovoltaic cell without deposited hole blocking layer and metal cathode; The online ellipsometer is installed inside the ALD reaction chamber and is communicatively connected to the control unit; The control unit is used to control the ALD gas delivery assembly to deposit a first tin oxide layer on the electron transport layer of the main structure layer using a time-type ALD process, and to use the online ellipsometer to detect the film thickness of the first tin oxide layer. When the film thickness reaches the target thickness range, the control unit switches the ALD gas delivery assembly to deposit a second tin oxide layer on the first tin oxide layer using a space-type ALD process, so as to form a hole blocking layer formed by the first tin oxide layer and the second tin oxide layer.

10. The ALD deposition apparatus as described in claim 9, characterized in that, The ALD gas delivery assembly includes a spray plate disposed in the ALD reaction chamber, and a tin source storage unit, a nitrogen storage unit and an oxygen source storage unit connected to the spray plate via a gas delivery pipe. The spray plate includes multiple sets of repeating spray units, each of which includes a tin source spray port, a nitrogen spray port, an oxygen source spray port, and a nitrogen spray port arranged in sequence.

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