Electron transport layer, preparation method thereof and perovskite solar cell
By modifying and dispersing SnO2 nanoparticles with silane coupling agents, the problem of SnO2 nanoparticles easily agglomerating in organic solvents was solved, a high-quality electron transport layer was prepared, the performance and stability of perovskite solar cells were improved, the preparation process was simplified and the cost was reduced.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-28
- Publication Date
- 2026-03-13
AI Technical Summary
When preparing SnO2 electron transport layers using existing liquid-phase methods, SnO2 nanoparticles tend to agglomerate in perovskite-compatible organic solvents, leading to film defects, impairing device performance, and failing to meet the high requirements of commercial applications.
Aqueous SnO2 nanoparticles were grafted and modified with a silane coupling agent, and covalent bonds were formed through heating and stirring. They were then ultrasonically dispersed in a perovskite-compatible solvent and finally formed an electron transport layer by spin coating.
Stable dispersion of SnO2 nanoparticles in organic solvents was achieved, and a uniform and dense electron transport layer was prepared, which improved the photoelectric conversion performance and stability of the device, simplified the preparation process and reduced the cost.
Smart Images
Figure CN121665877A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of perovskite solar cell technology, and more particularly to an electron transport layer and its preparation method, and a perovskite solar cell. Background Technology
[0002] Inverted (pin) perovskite solar cells (PSCs) have become an important direction for the commercial application of perovskite solar cells due to their outstanding advantages such as low fabrication temperature, small hysteresis effect, and good stability. In the structure of this type of device, the electron transport layer is the core key component that determines the device performance and long-term stability, and its performance directly affects the charge transport efficiency and device lifetime. At present, commonly used organic electron transport materials in devices (such as methyl (6,6)-phenylcarbon-61-butyrate) generally suffer from insufficient stability and lower electron mobility compared to inorganic materials, making it difficult to meet the high requirements for device performance and reliability in commercial applications.
[0003] Inorganic metal oxides, especially tin oxide (SnO2), are widely recognized as ideal alternatives to organic electron transport materials due to their excellent electron mobility, high light transmittance, energy level structure matching that of perovskite light-absorbing layers, and outstanding chemical and photothermal stability. Currently, the mainstream technology for preparing SnO2 electron transport layers for pin-structured PSCs in the laboratory is atomic layer deposition (ALD). However, this technology suffers from significant drawbacks, including complex fabrication processes, extremely long production times, and high equipment investment costs, severely limiting its application in large-scale mass production. Liquid-phase methods (such as spin coating, blade coating, and inkjet printing) offer significant advantages in terms of low cost and high throughput, making them an ideal approach for the large-scale preparation of SnO2 electron transport layers. However, this technical approach faces key application bottlenecks: most commercially available SnO2 nanoparticle colloidal solutions are aqueous systems. Directly coating them using liquid-phase processes such as spin coating would damage the underlying perovskite light-absorbing layer. If SnO2 nanoparticles are dispersed in weakly polar organic solvents compatible with perovskite (such as chlorobenzene, isopropanol, etc.), two major challenges arise. First, SnO2 nanoparticles have a large specific surface area and high surface energy, making them prone to aggregation and sedimentation in organic solvents due to interfacial energy mismatch, thus failing to form a uniform dispersion system. Second, aggregated particles result in numerous defects and pinholes in the prepared film. These defects become charge recombination centers, severely impairing the photoelectric conversion performance of the device.
[0004] Therefore, developing a method that can stably disperse SnO2 nanoparticles in perovskite-compatible solvents and prepare high-quality SnO2 electron transport layers through liquid-phase processes is of great practical significance and application value for overcoming the technical bottlenecks in the large-scale production of inverted perovskite solar cells and promoting their industrialization process. Summary of the Invention
[0005] The purpose of this invention is to provide an electron transport layer and its preparation method, as well as a perovskite solar cell, in order to solve the technical problem that SnO2 nanoparticles tend to agglomerate in perovskite-compatible organic solvents during the preparation of SnO2 electron transport layers using existing liquid-phase methods, leading to thin film defects and impaired device performance.
[0006] To address the aforementioned technical problems, this invention first provides a method for preparing an electron transport layer, the method comprising the following steps: S10: A water-based SnO2 nanoparticle dispersion was mixed with a silane coupling agent and grafted under heating and stirring conditions. After the reaction was completed, SnO2 powder with surface grafted silane coupling agent was obtained by centrifugation, washing and drying. S20: Modified SnO2 powder is dispersed in an organic solvent compatible with the perovskite light-absorbing layer, and then ultrasonically treated to obtain an organic SnO2 dispersion. S30: SnO2 organic dispersion is coated onto a substrate by spin coating and then annealed to obtain an electron transport layer.
[0007] Preferably, in step S10, the heating temperature of the grafting modification reaction is 40–60°C, and the reaction time is 1–4 h.
[0008] Preferably, in step S10, the general structural formula of the silane coupling agent is Y-(CH2). n -Si-X3; Wherein, the Y group includes at least one of amino, mercapto, vinyl and epoxy groups, the X group includes methoxy or ethoxy groups, and n is a positive integer greater than or equal to 1.
[0009] Preferably, in step S20, the organic solvent includes at least one of chlorobenzene, isopropanol, and toluene; the ultrasonic treatment time is 10-20 min.
[0010] Preferably, in step S20, the concentration of modified SnO2 in the SnO2 organic dispersion is 1–4 mg / mL.
[0011] Preferably, in step S30, the substrate includes a hole transport layer and a perovskite light-absorbing layer stacked from bottom to top, and the electron transport layer is disposed on the perovskite light-absorbing layer.
[0012] Preferably, in step S30, the annealing temperature is 60–80°C and the annealing time is 5–30 min.
[0013] Accordingly, the present invention also provides a perovskite solar cell, which includes, from bottom to top, a transparent substrate, a conductive layer, a hole transport layer, a perovskite light-absorbing layer, an electron transport layer, and a back electrode; wherein the electron transport layer is prepared using any of the above preparation methods.
[0014] Preferably, the conductive layer is patterned fluorine-doped tin oxide, the hole transport layer is Me-4PACz material, and the perovskite light-absorbing layer is Cs. 0.05 FA 0.85 MA 0.11 PbI 2.97 Cl 0.03 A perovskite thin film with a gold back electrode. Preferably, the open-circuit voltage (VOC) of the perovskite solar cell is 1.18–1.20 V, and the short-circuit current density (JSC) is 26.1–26.5 mA / cm². -2 The fill factor (FF) is 82.5%–83.5%, and the photoelectric conversion efficiency (PCE) is 25.6%–26.5%.
[0015] The beneficial effects of this invention are as follows: Unlike the prior art, this invention provides an electron transport layer and its preparation method, as well as a perovskite solar cell. The preparation method involves grafting and modifying aqueous SnO2 nanoparticles with a silane coupling agent. The hydrolytic group at one end of the silane coupling agent molecule can form a covalent bond with the SnO2 surface, while the organic group at the other end of the silane coupling agent molecule is well compatible with perovskite-compatible organic solvents. This significantly reduces the surface energy of SnO2 nanoparticles and effectively inhibits their aggregation tendency in organic solvents to achieve stable dispersion. It also enables the formation of a uniform, dense SnO2 film with excellent electron transport performance on the perovskite light-absorbing layer through spin coating, while avoiding damage to the underlying perovskite active layer. This method efficiently solves the core technical problem of preparing SnO2 electron transport layers using liquid-phase methods. Attached Figure Description
[0016] Figure 1 A flowchart illustrating the method for fabricating an electron transport layer according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of a perovskite solar cell provided in an embodiment of the present invention. Detailed Implementation
[0017] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.
[0018] The primary objective of this invention is to overcome the deficiencies of existing technologies and provide a solution to address the core problems of poor dispersibility and easy agglomeration of SnO2 nanoparticles in organic solvents such as chlorobenzene and isopropanol. Another objective is to provide a method for preparing a high-quality SnO2 electron transport layer on a perovskite active layer using liquid-phase processes such as spin coating, based on the aforementioned stable dispersion system. The ultimate goal is to apply this SnO2 electron transport layer to inverted perovskite solar cells, replacing the unstable organic electron transport layer and the time-consuming ALD method for SnO2 preparation, thereby simultaneously improving device efficiency and long-term stability, while simplifying the preparation process and significantly reducing preparation costs.
[0019] Please see Figure 1 This invention first provides a method for preparing an electron transport layer, the method comprising the following steps: S10 involves mixing an aqueous SnO2 nanoparticle dispersion with a silane coupling agent and performing a grafting modification reaction under heating and stirring conditions. After the reaction is completed, the SnO2 powder with the surface grafted silane coupling agent is obtained by centrifugation, washing, and drying.
[0020] Specifically, step S10 involves a grafting modification reaction between a silane coupling agent and aqueous SnO2 nanoparticles. This process allows one end of the silane coupling agent to form a strong covalent bond with the SnO2 surface, while the other end successfully introduces an organic functional group compatible with organic solvents. Simultaneously, impurities are removed by centrifugation and washing, followed by drying and shaping. This effectively reduces the surface energy of the SnO2 nanoparticles and inhibits their aggregation tendency.
[0021] In step S10, the heating temperature for the grafting modification reaction is 40–60°C, and the reaction time is 1–4 h. The above heating temperature range provides suitable energy for the grafting reaction between the silane coupling agent and the aqueous SnO2 nanoparticles, ensuring that the two are efficiently combined to form a strong covalent bond. The reaction time of 1–4 h ensures that the silane coupling agent is fully grafted onto the SnO2 surface and effectively introduces organic functional groups compatible with organic solvents, while avoiding excessive reaction that could lead to particle agglomeration or waste of coupling agent.
[0022] In step S10, the general structural formula of the silane coupling agent is Y-(CH2)n-Si-X3 (n is a positive integer greater than or equal to 1), where: Y is a functional group that can interact or combine with the hydroxyl groups on the SnO2 surface, preferably amino (-NH2), mercapto (-SH), vinyl (-CH=CH2), or epoxy. These functional groups can form strong chemical bonds or strong interactions with the SnO2 surface. X is a hydrolyzable group, such as methoxy (-OCH3) or ethoxy (-OC2H5), whose hydrolysis produces silanol groups (-Si-OH), which can undergo a condensation reaction with the hydroxyl groups (-OH) on the SnO2 surface to form a strong Si-O-Sn covalent bond.
[0023] S20: Modified SnO2 powder is dispersed in an organic solvent compatible with the perovskite light-absorbing layer, and then ultrasonically treated to obtain an organic SnO2 dispersion.
[0024] Specifically, dispersing modified SnO2 powder in an organic solvent compatible with the perovskite light-absorbing layer avoids damage to the underlying perovskite light-absorbing layer. Simultaneously, the compatibility between the modified SnO2 surface silane coupling agent and the organic solvent provides a suitable environment for particle dispersion. Ultrasonic treatment further aids in the thorough and uniform dispersion of the modified SnO2 powder, ultimately yielding a SnO2 organic dispersion with controllable concentration, uniform dispersion, and long-term stability (no visible sedimentation after 24 hours of standing). This lays a crucial foundation for the subsequent preparation of a uniform and dense electron transport layer via spin coating.
[0025] In step S20, the organic solvent includes at least one of chlorobenzene, isopropanol, and toluene; the ultrasonic treatment time is 10–20 min.
[0026] Specifically, the aforementioned organic solvent ensures good compatibility with the perovskite light-absorbing layer to avoid damaging the underlying structure, and is also compatible with the silane coupling agent grafted onto the modified SnO2 surface, providing a suitable environment for particle dispersion. The ultrasonic treatment time of 10-20 minutes can effectively break up the slight aggregation of the modified SnO2 powder, promote its uniform dispersion in the organic solvent, and at the same time avoid damage to the particle structure or excessive solvent volatilization caused by prolonged ultrasonic treatment, ultimately obtaining a stable SnO2 organic dispersion that is compatible with perovskite.
[0027] In step S20, the concentration of modified SnO2 in the SnO2 organic dispersion is 1-4 mg / mL. The appropriate concentration of modified SnO2 can avoid defects caused by excessively low concentration leading to thin and discontinuous films during subsequent spin coating, and can also prevent excessively high concentration from causing the modified SnO2 particles to re-aggregate and destroy the dispersion stability.
[0028] S30: SnO2 organic dispersion is coated onto a substrate by spin coating and then annealed to obtain an electron transport layer.
[0029] Specifically, step S30 also includes: On a substrate where the hole transport layer and perovskite light-absorbing layer have been prepared, the SnO2 organic dispersion obtained in step S20 is coated by spin coating, followed by annealing to remove residual solvent, forming a dense, flat, and pinhole-free SnO2 electron transport layer.
[0030] In step S30, the annealing temperature is 60–80°C and the annealing time is 5–30 min. The annealing process can effectively remove residual solvents and ultimately form a dense, flat, and pinhole-free SnO2 electron transport layer. This film can ensure efficient electron transport, reduce charge recombination, and adapt to the existing structure of the substrate, laying the core structural foundation for improving the device efficiency and stability of inverted perovskite solar cells.
[0031] Please see Figure 2 The present invention also provides a perovskite solar cell, which includes, from bottom to top, a transparent substrate, a conductive layer, a perovskite light-absorbing layer, an electron transport layer and a back electrode; wherein the electron transport layer is prepared by any of the above preparation methods.
[0032] Specifically, the transparent substrate serves as a supporting framework and ensures efficient sunlight incidence; the conductive layer (positive electrode) is responsible for collecting holes and guiding them to the external circuit while maintaining light transmittance; the perovskite light-absorbing layer extracts and selectively transports holes from the perovskite light-absorbing layer to the conductive layer, blocking electron reverse migration and protecting the interface to reduce defects; the perovskite light-absorbing layer is the core, absorbing sunlight and generating photogenerated electron-hole pairs; the electron transport layer selectively transports electrons to the back electrode, blocking holes to avoid recombination; the back electrode (negative electrode) collects electrons and forms a current loop with the external circuit, ultimately realizing power output.
[0033] Specifically, the conductive layer is patterned fluorine-doped tin oxide, the hole transport layer is Me-4PACz ([4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphate) material, and the perovskite light-absorbing layer is Cs. 0.05 FA 0.85 MA 0.11 PbI 2.97 Cl 0.03 The perovskite thin film has an electron transport layer made of modified SnO2 obtained by the preparation method of this invention, and a back electrode made of gold.
[0034] In this embodiment of the invention, the hole transport layer has a thickness of 20–120 nm, the perovskite light-absorbing layer has a thickness of 400–600 nm, the electron transport layer has a thickness of 70–90 nm, and the back electrode has a thickness of 80–100 nm.
[0035] Specifically, the hole transport layer (20–120 nm) has a moderate thickness, ensuring uniform coverage to reduce interface defects and prevent non-radiative recombination of charge carriers, while also lowering hole transport resistance. The perovskite light-absorbing layer (400–600 nm) can fully absorb visible light to generate sufficient photogenerated charge carriers, while avoiding excessive thickness that would cause excessively long carrier migration distances and increased recombination probability. The electron transport layer (70–90 nm) can avoid pinhole defects and reduce electron transport resistance, enhancing electron transport and hole blocking effects. The back electrode (80–100 nm) ensures high conductivity for efficient electron extraction while also being lightweight and cost-effective, and protecting the inner layer materials. The synergistic adaptation of the thicknesses of each layer maximizes light absorption efficiency and charge carrier transport efficiency, reduces losses, and ensures structural stability, ultimately achieving high photoelectric conversion efficiency and long-term reliability of the perovskite solar cell.
[0036] The technical solution of this application will now be described in further detail with reference to specific embodiments.
[0037] Example 1: This embodiment 1 provides an electron transport layer and its preparation method. The electron transport layer is SnO2 modified with γ-aminopropyltriethoxysilane. The preparation method specifically includes the following steps: Step (1), surface grafting modification of SnO2 nanoparticles: γ-aminopropyltriethoxysilane (NH2(CH2)3Si(OC2H5)3) was added to an aqueous SnO2 nanoparticle dispersion and reacted at 50°C with stirring for 2 hours. After the reaction, SnO2 powder with γ-aminopropyltriethoxysilane grafted on its surface was obtained by centrifugation, washing and drying. Step (2), preparation of SnO2 organic dispersion: The modified SnO2 powder is dispersed in chlorobenzene and ultrasonically treated for 15 min to obtain SnO2 organic dispersion with controllable concentration, uniform dispersion and long-term stability (no visible sedimentation after standing for 24 h). The concentration of SnO2 organic dispersion is 2 mg / mL. Step (3): On the substrate where the hole transport layer and perovskite light-absorbing layer have been prepared, the SnO2 organic dispersion obtained in step (2) is coated by spin coating (rotation speed of 3000 rpm, spin coating time of 30 s), followed by annealing at 70°C for 5 min to remove residual solvent, forming a dense, flat, pinhole-free SnO2 electron transport layer with a thickness of 80 nm.
[0038] Example 2: Example 2 provides an electron transport layer and its preparation method. The electron transport layer is SnO2 modified with γ-aminopropyltriethoxysilane. The preparation method of Example 2 is roughly the same as that of Example 1, except that the concentration of SnO2 organic dispersion in step (2) is 4 mg / mL.
[0039] Example 3: This embodiment 3 provides an electron transport layer and its preparation method. The electron transport layer is SnO2 modified with γ-aminopropyltriethoxysilane. The preparation method of this embodiment 3 is roughly the same as that of embodiment 1, except that the concentration of SnO2 organic dispersion in step (2) is 1 mg / mL.
[0040] Example 4: This embodiment 4 provides an electron transport layer and its preparation method. The electron transport layer is SnO2 modified with γ-glycidoxypropyltrimethoxysilane. The preparation method of this embodiment 4 is roughly the same as that of embodiment 1, except that the silane coupling agent added to the aqueous SnO2 nanoparticle dispersion in step (1) is γ-glycidoxypropyltrimethoxysilane.
[0041] Example 5: Example 5 provides an electron transport layer and its preparation method. The electron transport layer is SnO2 modified with γ-glycidoxypropyltrimethoxysilane. The preparation method of Example 5 is roughly the same as that of Example 4, except that the concentration of SnO2 organic dispersion in step (2) is 1 mg / mL.
[0042] Example 6: This embodiment 6 provides an electron transport layer and its preparation method. The electron transport layer is SnO2 modified with γ-aminopropyltriethoxysilane. The preparation method of this embodiment 6 is roughly the same as that of embodiment 1, except that the modified SnO2 powder is dispersed in isopropanol in step (2).
[0043] Example 7: This embodiment 7 provides an electron transport layer and its preparation method. The electron transport layer is SnO2 modified with γ-aminopropyltriethoxysilane. The preparation method of this embodiment 7 is roughly the same as that of embodiment 1, except that the annealing time in step (3) is 10 min.
[0044] Comparative Example 1: Comparative Example 1 provides an electron transport layer prepared by a conventional process and its preparation method. The electron transport layer is SnO2 powder without modification by a silane coupling agent. The preparation method of the electron transport layer includes the following steps: Step (1), preparation of organic dispersion: SnO2 powder is dispersed in chlorobenzene and ultrasonically treated for 15 min to obtain an organic dispersion with controllable concentration, uniform dispersion and long-term stability (no visible sedimentation after standing for 24 h). The concentration of the organic dispersion is 2 mg / mL. Step (2): On the substrate where the hole transport layer and perovskite light-absorbing layer have been prepared, the organic dispersion obtained in step (1) is coated by spin coating (rotation speed of 3000 rpm and spin coating time of 30 s), followed by annealing at 70°C for 5 min to remove residual solvent and form an 80 nm electron transport layer.
[0045] Comparative Example 2: Comparative Example 2 provides an electron transport layer and its preparation method. The electron transport layer is a double-layer stacked structure formed by PCBM ((6,6)-phenylcarbon-61-methyl butyrate) material and BCP (bath copper spirit) material. The preparation method of Comparative Example 2 is roughly the same as that of Comparative Example 1, except that PCBM / BCP is dispersed in chlorobenzene in step (1).
[0046] Comparative Example 3: Comparative Example 3 provides an electron transport layer and its preparation method. The electron transport layer is a double-layer stacked structure formed by C60 (Buckminsterfullerene) material and BCP (bath copper spirit) material. The preparation method of Comparative Example 3 is roughly the same as that of Comparative Example 1, except that C60 / BCP is dispersed in chlorobenzene in step (1).
[0047] Comparative Example 4: Comparative Example 4 provides an electron transport layer and its preparation method. The electron transport layer is a three-layer stacked structure formed by C60 / SnO2 / BCP. SnO2 is prepared by atomic deposition (ALD). The preparation method of Comparative Example 4 is roughly the same as that of Comparative Example 1, except that C60 / SnO2 / BCP is dispersed in chlorobenzene in step (1).
[0048] Specifically, the electron transport layers provided in Examples 1-7 and Comparative Examples 1-4 were used to fabricate perovskite solar cells. These perovskite solar cells comprise, from bottom to top, a transparent substrate, a conductive layer, a perovskite light-absorbing layer, an electron transport layer, and a back electrode. The transparent substrate is a glass substrate, the conductive layer is patterned fluorine-doped tin oxide, and the hole transport layer is a Me-4PACz self-assembled material. The perovskite light-absorbing layer is a Cs layer with a thickness of approximately 600 nm.0.05 FA 0.85 MA 0.11 PbI 2.97 Cl 0.03 The perovskite thin film has an electron transport layer provided in Examples 1-7 and Comparative Examples 1-4, and a back electrode made of 90 nm gold.
[0049] Furthermore, the above-mentioned method for fabricating perovskite solar cells includes the following steps: Step (1) Preparation of the patterned conductive layer: The glass substrate with the fluorine-doped tin oxide conductive layer was etched for 15 s using zinc powder and 6 mol / L hydrochloric acid. Then, it was ultrasonically cleaned with deionized water, ethanol, acetone, and isopropanol for 15 min each. Subsequently, it was dried with nitrogen in a dry air environment and subjected to ultraviolet ozone treatment; the ultraviolet light wavelength was 185 nm, the power was 2250 W, and the irradiation time was 20 min, resulting in a clean, patterned, transparent conductive substrate with a fluorine-doped tin oxide conductive layer.
[0050] Step (2) Preparation of hole transport layer: 1.0 mg of Me-4PACz self-assembled material and 1 mL of ethanol were mixed to prepare hole transport layer solution; the hole transport layer solution was spin-coated onto the patterned fluorine-doped tin oxide conductive layer transparent conductive substrate at a speed of 4000 rpm for 30 s spin-coating time, and annealed at 100 °C for 10 min to obtain hole transport layer.
[0051] Step (3) Preparation of the perovskite light-absorbing layer: First, a perovskite precursor solution with a total concentration of 1.4 M was prepared using a mixture of dimethylformamide and dimethyl sulfoxide as solvent (volume ratio = 4:1) and cesium iodide, formamidinium iodide, lead iodide, and methylamine chloride as solutes (molar ratio = 0.05:0.95:1.05:0.12); second, the perovskite precursor solution was spin-coated onto the hole transport layer at a speed of 1000 rpm for 12 s, and then the speed was increased to 5000 rpm for 38 s. During the 38th to 40th s of the total spin-coating time, 150 μL of chlorobenzene was rapidly added dropwise onto the precursor solution film to obtain a perovskite mesophase film; finally, the perovskite mesophase film was annealed at 100 °C for 20 min to obtain Cs 0.05 FA 0.85 MA 0.11 PbI 2.97 Cl 0.03 The perovskite light-absorbing layer, made of perovskite thin film, has a thickness of approximately 600 nm. Step (4) Preparation of electron transport layer: Electron transport layer was prepared according to the preparation methods provided in Examples 1-7 and Comparative Examples 1-4; Step (5) Fabrication of perovskite solar cells: A vacuum evaporation apparatus with a pore area of 0.09 cm² was used. 2Using a photomask, a 90 nm gold back electrode is deposited on the electron transport layer at a rate of 1 Å / s to obtain a perovskite solar cell.
[0052] The electron transport layers obtained in Examples 1-7 and Comparative Examples 1-4 were used to fabricate multiple perovskite solar cells, and the cell performance of the above perovskite solar cells was tested. The specific test process is as follows: at AM1.5G (100mW / cm²), -2 Under simulated solar energy conditions at Wacom Denso Co., Ltd. (Japan), the current density-voltage (JV) curves of the perovskite solar cells prepared in Examples 1-7 and Comparative Examples 1-4 were measured using a Keithley 2400 digital source meter to obtain the open-circuit voltage V of the perovskite solar cells. OC Short-circuit current density J SC Information such as fill factor (FF) and photoelectric conversion efficiency (PCE) was measured. Measurements were performed using either a forward (-0.2 to 1.3 V) scan or a reverse (1.3 to -0.2 V) scan. The delay time and step voltage were set to 20 ms and 20 mV, respectively.
[0053] Specifically, the performance parameters of the multiple perovskite solar cells fabricated with electron transport layers obtained in Examples 1-7 and Comparative Examples 1-4 are shown in Table 1 below: Table 1 shows the pore area as 0.09 cm². 2 Perovskite solar cell performance parameters
[0054] As shown in Table 1, the perovskite solar cells prepared in Examples 1-7 using a SnO2 electron transport layer modified with a silane coupling agent have short-circuit current densities (Jsc) ranging from 26.1 to 26.5 mA / cm². -2 The open-circuit voltage (Voc) of the present invention is between 1.18 and 1.20 V, the fill factor (FF) is between 82.5% and 83.5%, and the photoelectric conversion efficiency (PCE) is between 25.5% and 26.5%. In contrast, the battery performance of Comparative Example 1 (unmodified SnO2), Comparative Example 2 (PCBM / BCP), Comparative Example 3 (C60 / BCP), and Comparative Example 4 (C60 / SnO2 / BCP) is significantly inferior. Specifically, the PCE of Comparative Example 1 is only 22.5%, and the PCE of Comparative Examples 2-4 is between 25.2% and 25.5%, with Voc and FF also generally lower than those of Examples 1-7. This fully demonstrates that the SnO2 electron transport layer prepared by modifying with a silane coupling agent in this invention significantly improves the current density, voltage, fill factor, and final photoelectric conversion efficiency of inverted perovskite solar cells, exhibiting comprehensive superiority over traditional organic electronic layers (C60, PCBM), unmodified SnO2 electronic layers, and composite electronic layers based on ALD technology.
[0055] Furthermore, the inverted perovskite solar cells prepared in Examples 1, 2, and 3 were subjected to aging tests based on the ISOS-L-3 aging protocol, operating continuously for 1200 hours. These tests were conducted on a solar cell light resistance testing system (Bunkoukeiki, Japan) under AM1.5G sunlight (100 mW cm⁻¹). -2 After aging, the Voc, Jsc, and FF of Comparative Examples 2 and 3 all decreased significantly, and the final device efficiency decreased to 55% and 61% of the original values, respectively. However, due to the more stable electronic layer structure, the photovoltaic parameters of Example 1 decreased significantly, and the device maintained an initial efficiency of over 94%. This indicates that the inverse perovskite solar cell based on a liquid-phase dispersed tin oxide electronic layer prepared in this invention has stronger stability.
[0056] Compared with existing technologies, the electron transport layer and its preparation method, as well as the perovskite solar cell and its preparation method provided by this invention, have the following advantages: First, this invention utilizes the "bridging effect" of silane coupling agents, where one end (X) is firmly bonded to the SnO2 surface through covalent bonds (Si-O-Sn), and the organic functional groups at the other end (Y) have excellent compatibility with target organic solvents such as chlorobenzene, which significantly reduces the surface energy of SnO2 nanoparticles, effectively inhibits their aggregation behavior in organic solvents, and achieves stable dispersion at the thermodynamic level. Secondly, the stable SnO2 organic dispersion provided by this invention ensures that a uniform, dense and continuous film can be formed on the perovskite light-absorbing layer through a simple spin coating process; the film has excellent electron transport performance and will not damage the underlying perovskite active layer. Third, this invention completely replaces unstable organic electron transport layers such as PCBM with inorganic SnO2, eliminating the stability risks caused by the degradation of organic materials at the source, and is expected to significantly extend the operating life of devices. Simplified process and reduced cost: Replacing the hours-long ALD process with a liquid-phase spin coating method that takes only a few minutes significantly improves preparation efficiency, lowers equipment requirements and energy consumption, and lays the foundation for industrialization.
[0057] Fourth, the preparation method provided by this invention is not only applicable to inverted perovskite solar cells, but can also be extended to other optoelectronic devices such as photodetectors and light-emitting diodes that require solution-based preparation of inorganic functional layers.
[0058] It should be noted that all the above embodiments belong to the same inventive concept, and the descriptions of each embodiment have different focuses. Where the description in a particular embodiment is not detailed, please refer to the description in other embodiments.
[0059] The above embodiments merely illustrate implementation methods of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.
Claims
1. A method for preparing an electron transport layer, characterized in that, The preparation method includes the following steps: S10, an aqueous SnO2 nanoparticle dispersion is mixed with a silane coupling agent and a grafting modification reaction is carried out under heating and stirring conditions. After the reaction is completed, the SnO2 powder with the silane coupling agent grafted on the surface is obtained by centrifugation, washing and drying. S20, the modified SnO2 powder is dispersed in an organic solvent compatible with the perovskite light-absorbing layer, and after ultrasonic treatment, an organic SnO2 dispersion is obtained. S30, the SnO2 organic dispersion is coated onto the substrate by spin coating, and after annealing, an electron transport layer is obtained.
2. The method for preparing an electron transport layer according to claim 1, characterized in that, In step S10, the heating temperature of the grafting modification reaction is 40–60°C, and the reaction time is 1–4 h.
3. The method for preparing an electron transport layer according to claim 1, characterized in that, In step S10, the general structural formula of the silane coupling agent is Y-(CH2). n -Si-X3; Wherein, the Y group includes at least one of amino, mercapto, vinyl and epoxy groups, the X group includes methoxy or ethoxy groups, and n is a positive integer greater than or equal to 1.
4. The method for preparing an electron transport layer according to claim 1, characterized in that, In step S20, the organic solvent includes at least one of chlorobenzene, isopropanol, and toluene; the ultrasonic treatment time is 10-20 min.
5. The method for preparing an electron transport layer according to claim 1, characterized in that, In step S20, the concentration of the modified SnO2 in the SnO2 organic dispersion is 1-4 mg / mL.
6. The method for preparing an electron transport layer according to claim 1, characterized in that, In step S30, the substrate includes a hole transport layer and a perovskite light-absorbing layer stacked from bottom to top, and the electron transport layer is disposed on the perovskite light-absorbing layer.
7. The method for preparing an electron transport layer according to claim 1, characterized in that, In step S30, the annealing temperature is 60–80°C and the annealing time is 5–30 min.
8. A perovskite solar cell, characterized in that, The perovskite solar cell comprises, from bottom to top, a transparent substrate, a conductive layer, a hole transport layer, a perovskite light-absorbing layer, an electron transport layer, and a back electrode; wherein the electron transport layer is prepared using the preparation method described in any one of claims 1 to 8.
9. The perovskite solar cell according to claim 8, characterized in that, The conductive layer is patterned fluorine-doped tin oxide, the hole transport layer is Me-4PACz material, and the perovskite light-absorbing layer is Cs. 0.05 FA 0.85 MA 0.11 PbI 2.97 Cl 0.03 A perovskite thin film, wherein the back electrode is gold.
10. The perovskite solar cell according to claim 9, characterized in that, The open-circuit voltage (VOC) of the perovskite solar cell is 1.18–1.20 V, and the short-circuit current density (JSC) is 26.1–26.5 mA / cm². -2 The fill factor (FF) is 82.5%–83.5%, and the photoelectric conversion efficiency (PCE) is 25.6%–26.5%.