A modification method of a full-textured perovskite / crystalline silicon laminated solar cell

Abstract

This invention discloses a modification method for a fully textured perovskite / crystalline silicon tandem solar cell. The method involves a two-step annealing process using a vacuum-assisted two-step method. The inorganic compound film deposited in the first step is annealed using a mixed solvent vapor composed of a good solvent and a poor solvent. Since the good solvent can react with lead ions in the inorganic compound film to form intermediate complexes, it helps to delay the crystallization of the perovskite polycrystalline film during the second thermal annealing, thereby improving the crystallinity of the perovskite polycrystalline film. Simultaneously, the presence of the poor solvent in the mixed solvent vapor annealing ensures that the inorganic compound layer from the first step covers the entire textured surface of the crystalline silicon base cell, thus guaranteeing the excellent performance of the final fully textured perovskite / crystalline silicon tandem solar cell. This modification method is expected to promote the industrialization of fully textured perovskite / crystalline silicon tandem solar cells.

Description

Technical Field

[0001] This invention belongs to the field of solar cell technology, specifically relating to a modification method for a fully textured perovskite / crystalline silicon tandem solar cell, which can significantly improve the repeatability of the perovskite top cell fabrication process. Background Technology

[0002] Organic-inorganic metal halide perovskite solar cells (PSCs) have attracted considerable interest over the past decade, with single-junction perovskite solar cells now achieving a photoelectric conversion efficiency (PCE) exceeding 25%. Their tunable bandgap and low fabrication cost make them well-suited for pairing with crystalline silicon cells to create high-efficiency perovskite / crystalline silicon tandem solar cells. In this structure, high-energy photons are absorbed in the perovskite top cell, while low-energy photons are absorbed in the crystalline silicon bottom cell. The appropriate combination of these two materials can reduce heat loss, theoretically achieving a PCE exceeding 33%.

[0003] In recent years, perovskite polycrystalline thin films have typically been prepared using liquid-phase methods, mainly including coating a precursor solution onto a substrate (such as spin coating or blade coating) and annealing the wet film. Controlling the chemical state of the perovskite precursor solution and the coating process can regulate the nucleation and growth kinetics of the crystals, thereby significantly improving the crystallinity of the film. Among all control methods, solvent engineering of the precursor is the most commonly used and effective approach; strongly polar (good) solvents can react with Pb... 2+ Coordination occurs, which in turn affects the crystallization rate. The use of weakly polar (poor) solvents can reduce the residue of strong solvents, thus reducing the intensity of coordination. However, currently commercially available crystalline silicon solar cells have large textured surfaces on both sides, typically at the micrometer scale. Traditional liquid-phase methods cannot prepare high-quality perovskite polycrystalline films on these textured substrates, which greatly limits the development of perovskite / crystalline silicon tandem solar cells.

[0004] For double-textured crystalline silicon bottom cells, the perovskite polycrystalline thin film light-absorbing layer in the perovskite top cell can be prepared using a vacuum-assisted two-step method. This method is simple and applicable regardless of whether the substrate is polished or textured, perfectly complementing the already industrialized crystalline silicon bottom cell production process. However, several significant challenges remain in preparing fully textured, high-efficiency perovskite / crystalline silicon tandem solar cells using the vacuum-assisted two-step method. This is primarily due to the inability of the first step, vacuum physical vapor deposition of inorganic compound films, to form the intermediate complexes used in the liquid phase method, leading to uncontrollable crystallization of the perovskite polycrystalline thin film in the top cell. Therefore, the perovskite polycrystalline thin film prepared by the vacuum-assisted two-step method exhibits poor reproducibility, resulting in the final performance of the fully textured perovskite / crystalline silicon tandem solar cell falling far short of theoretical values, leaving considerable room for improvement. Optimizing the quality of the first step, the inorganic compound film, in the vacuum-assisted two-step method to approximate the preparation effect of the liquid phase method is crucial for optimizing the entire preparation process. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, the present invention provides a modification method for a fully textured perovskite / crystalline silicon tandem solar cell.

[0006] The fully textured perovskite / crystalline silicon tandem solar cell of the present invention consists of three parts: a double-sided textured heterocrystalline silicon bottom cell, a nanocrystalline silicon tunneling composite layer, and a perovskite top cell. The nanocrystalline silicon tunneling composite layer is made of p-type nanocrystalline silicon and is prepared on the crystalline silicon bottom cell by plasma-enhanced chemical vapor deposition.

[0007] The fully textured perovskite / crystalline silicon tandem solar cell of this invention, in terms of the order of fabrication, consists of: a back silver electrode, a back indium tin oxide transparent electrode, p-type amorphous silicon, intrinsic amorphous silicon, a micron-scale textured intrinsic monocrystalline silicon wafer, intrinsic amorphous silicon, n-type amorphous silicon, a p-type nanocrystalline silicon tunneling composite layer, a hole transport layer of 2,2,7,7-tetratetra(N,N-di-p-tolyl)amino-9,9-spirodifluorene (spiro-TTB), a perovskite polycrystalline thin film, a passivation layer of LiF, and an electron transport layer of C. 60 The structure consists of a protective SnO2 layer, a front indium tin oxide transparent electrode, an antireflection layer MgF2, and a front silver grid line electrode. The commercially available double-textured heterocrystalline silicon solar cell with an undeposited indium tin oxide transparent electrode on the n-type amorphous silicon surface is used. This cell includes a back silver electrode, a back indium tin oxide transparent electrode, a back p-type amorphous silicon, a back intrinsic amorphous silicon, a micron-textured intrinsic monocrystalline silicon wafer, a front intrinsic amorphous silicon, and a front n-type amorphous silicon, serving as the crystalline silicon bottom cell. Other components include a hole transport layer (spiro-TTB), a perovskite polycrystalline thin film, a passivation layer (LiF), and an electron transport layer (C). 60 The perovskite top cell consists of a protective layer SnO2, a front indium tin oxide transparent electrode, a front silver grid electrode, and an antireflection layer MgF2.

[0008] The top and bottom surfaces of crystalline silicon bottom solar cells exhibit commercially available micron-scale textured morphologies. Each layer of the fabricated thin film must maintain this textured morphology to achieve optimal optical control. In perovskite top solar cells, the perovskite polycrystalline thin film is prepared using a vacuum-assisted two-step method. The first step involves the vapor-phase co-deposition of lead iodide and cesium bromide using a thermal evaporation vacuum deposition apparatus, forming a mixed inorganic compound film of lead iodide and cesium bromide. To form a vapor complex similar to that of the liquid-phase method, the sample with the deposited inorganic compound film is placed in a sealed container, and a certain flow rate of a good / bad solvent mixed vapor is introduced. The preferred good solvent is one of dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), or methylpyrrolidone (NMP), while the bad solvent is chlorobenzene. The mixing (volume) ratio, flow rate, and vapor introduction time of the two solvent vapors can adjust the Pb content in the first inorganic compound film. 2+ The strength of the interaction between ions and a good solvent. This can generally be observed from the color of the inorganic compound film. When the film color suddenly fades, it indicates that a sufficient amount of good solvent has reacted with Pb. 2+ When ions react to form a vapor complex, solvent vapor annealing should be stopped immediately, and the sample should be quickly removed from the sealed container. The second step involves liquid-phase coating of an ethanol solution of a binary mixed organic ammonium salt (formamidinium hydroiodate and formamidinium hydrobromide) onto the inorganic compound film. Thermal annealing is then performed in humid air. After the second annealing, the final perovskite polycrystalline film is obtained.

[0009] In the fabrication process of the perovskite polycrystalline thin film in the fully textured perovskite / crystalline silicon tandem solar cell, the first step involves physical vapor deposition of inorganic compounds using a vacuum thermal evaporation device, replacing the traditional liquid phase method. By adding an additional solvent vapor annealing process, the inorganic compound film obtained through physical deposition is annealed, successfully introducing good solvent molecules and achieving results close to those of the liquid phase method. Then, a formamidinium-based organic ammonium salt solution, mixed in a certain proportion, is coated onto the inorganic compound film through liquid phase deposition. After thermal annealing at approximately 50% relative humidity and 150°C for 20–40 minutes, the perovskite polycrystalline thin film is completed. The first step of solvent annealing improves its crystallinity, including grain size and crystal orientation, and suppresses the formation of pores in the perovskite polycrystalline thin film, significantly improving the crystallinity quality of the perovskite polycrystalline thin film grown on the textured crystalline silicon substrate.

[0010] Furthermore, the hole transport layer spiro-TTB, the passivation layer LiF, and the electron transport layer C 60 The antireflection layer MgF2, the front silver grid line electrode and the back silver electrode were deposited by thermal evaporation vacuum deposition equipment, the protective layer SnO2 was deposited by atomic layer deposition equipment, and the nanocrystalline silicon tunneling composite layer was prepared by plasma-enhanced chemical vapor deposition.

[0011] Mechanism of the invention:

[0012] In the vacuum-assisted two-step growth of perovskite polycrystalline thin films in textured perovskite / crystalline silicon tandem solar cells, we know that while the physical deposition of inorganic compounds in the first step solves the conformality problem on the textured silicon wafer, the physical deposition process cannot effectively control the crystallinity of the perovskite film, resulting in poor performance of perovskite solar cells prepared by the vacuum method. In contrast, the liquid-phase two-step method commonly uses a good solvent to dissolve inorganic materials such as lead iodide, and after coating with this liquid phase, a first layer of inorganic compound film is obtained. The large amount of residual good solvent molecules in this film can form vapor complexes with the lead halides in the inorganic compound, thereby slowing down the crystallization rate of the perovskite polycrystalline film, promoting uniform crystallization, and ultimately obtaining a high-efficiency perovskite cell. To obtain a perovskite film similar to that prepared by the liquid-phase method, annealing the first layer of inorganic compound film with solvent vapor has become an effective strategy. The combined use of good and bad solvents can reduce the vapor concentration of good solvent molecules, thereby reducing the damage to the shape of the first inorganic compound film. This ensures that the perovskite polycrystalline film still has good shape retention, guaranteeing the performance of the final fully textured perovskite / crystalline silicon tandem solar cell.

[0013] Compared with the prior art, the beneficial effects of the present invention are:

[0014] 1) The two-step method for preparing perovskite polycrystalline thin films proposed in this invention is simple and easy to operate. The solvent annealing process can be achieved by adjusting the vapor of a good solvent / poor solvent mixture, which can meet the needs of different perovskite material systems and is compatible with the preparation of perovskite thin films on different substrates.

[0015] 2) This invention provides an effective solution for the preparation of high-efficiency fully textured perovskite / crystalline silicon tandem solar cells. The vacuum-assisted two-step method, due to the physical deposition in the first step, is not easy to control the crystallization kinetics of perovskite polycrystalline thin films, thus laying the foundation for performance gains and large-area high-efficiency preparation of perovskite top cells. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of the fully textured perovskite / crystalline silicon tandem solar cell described in this invention; the names of each part are as follows: 10, back silver electrode; 20, back indium tin oxide transparent electrode; 30, back p-type amorphous silicon; 40, back intrinsic amorphous silicon; 50, micron-scale textured intrinsic monocrystalline silicon wafer; 60, front intrinsic amorphous silicon; 70, front n-type amorphous silicon; 80, p-type microcrystalline silicon tunneling composite layer; 90, hole transport layer spiro-TTB; 100, two-dimensional / three-dimensional hybrid heterojunction perovskite light-absorbing layer; 110, passivation layer LiF; 120, electron transport layer C. 60; 130, Protective layer SnO2; 140, Front indium tin oxide transparent electrode; 150, Front silver grid line electrode; 160, Antireflection layer MgF2;

[0017] Figure 2 These are scanning electron microscope images of the perovskite polycrystalline thin films prepared in Example 1 and Comparative Example 1 of the present invention;

[0018] Figure 3 The IV characteristic curves of the fully textured perovskite / crystalline silicon tandem solar cells prepared in Example 1 and Comparative Example 1 of the present invention under AM1.5G illumination are shown.

[0019] Figure 4 These are scanning electron microscope images of the perovskite polycrystalline thin films prepared in Example 2 and Comparative Example 2 of the present invention.

[0020] Figure 5 The IV characteristic curves of the fully textured perovskite / crystalline silicon tandem solar cells prepared in Example 2 and Comparative Example 2 of this invention under AM1.5G illumination are shown. Detailed Implementation

[0021] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. The following embodiments are only used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0022] Please see Figure 1 This invention relates to a fully textured perovskite / crystalline silicon tandem solar cell, which comprises, from bottom to top, a crystalline silicon bottom cell and a perovskite top cell. The crystalline silicon bottom cell is based on commercially available double-textured heterocrystalline silicon. The perovskite polycrystalline thin film in the perovskite top cell is prepared by a two-step method of two annealing processes. The crystalline silicon bottom cell and the perovskite top cell are connected by a p-type nanocrystalline silicon tunneling composite layer 80.

[0023] Comparative Example 1: The first fully textured perovskite / crystalline silicon tandem solar cell treated with solvent vapor annealing.

[0024] (1) A commercially available double-sided textured heterocrystalline silicon solar cell with no indium tin oxide transparent electrode deposited on the n-type amorphous silicon surface was selected as the bottom cell of the tandem solar cell. A 15nm nanocrystalline silicon layer was deposited on the heterocrystalline silicon n-type amorphous silicon as a tunneling composite layer using a plasma-enhanced chemical vapor deposition device.

[0025] (2) A hole transport layer spiro-TTB with a thickness of 25 nm was deposited on nanocrystalline silicon as a tunneling composite layer in a thermal evaporation vacuum deposition equipment at an evaporation rate of 0.02 nm / s. Then, the first step of the vacuum-assisted two-step method for preparing the perovskite light absorption layer was carried out: lead iodide and cesium bromide were co-evaporated using a thermal evaporation vacuum deposition equipment, and the ratio of the vapor deposition rate of lead iodide and cesium bromide was controlled at 1:0.05. A mixed inorganic compound film of lead iodide and cesium bromide with a total thickness of 380 nm was obtained on the hole transport layer.

[0026] (3) Prepare an ethanol solution of formamidin hydrobromide and formamidin hydroiodide at a mass ratio of 1:4 (formamidin molar concentration of 0.49M). Use this solution to spin-coat the surface of the inorganic compound film prepared in step (2) in a glove box. The spin coater rotates at 3000 rpm for 30 seconds. Immediately afterwards, place it on a 150°C hot plate in a 50% relative humidity environment for annealing for 30 minutes to obtain an unoptimized perovskite polycrystalline film. From Figure 2 Comparing the scanning electron microscope image of the surface in Example 1, it can be seen that the perovskite grains in this film are relatively small and there are many pores.

[0027] (4) A passivation layer of LiF with a thickness of 0.8 nm was deposited on the surface of the pure three-dimensional perovskite light-absorbing layer using a thermal evaporation vacuum deposition apparatus. Following this, an electron transport layer of C with a thickness of 15 nm was deposited using the same apparatus. 60 .

[0028] (5) Using atomic layer deposition equipment in C 60 A 18nm SnO2 layer was deposited on the surface as a protective layer, and then a 90nm thick indium tin oxide transparent electrode (indium oxide to tin oxide mass ratio of 97:3) was deposited on the SnO2 surface using physical vapor deposition.

[0029] (6) Finally, a 200 nm thick front-side silver grid electrode is deposited on the indium tin oxide transparent electrode from step (5) using a thermal evaporation vacuum deposition apparatus. (The silver grid electrode consists of a main grid and a fine grid, with the effective area of ​​the main grid being 1 cm².) 2 And a 100nm thick antireflection layer of MgF2. From Figure 3 Comparing the IV characteristic curves of the tandem solar cell in Example 1 under AM1.5G illumination, we can see that the open-circuit voltage is 1.63V and the current density is 18.12mA / cm². 2 The fill factor is 68%, and the photoelectric conversion efficiency is 20.1%.

[0030] Example 1

[0031] An embodiment of a method for simultaneously improving the open-circuit voltage and stability of a fully textured perovskite / crystalline silicon tandem solar cell includes the following steps:

[0032] (1) A commercially available double-sided textured heterocrystalline silicon solar cell with no indium tin oxide transparent electrode deposited on the n-type amorphous silicon surface was selected as the bottom cell of the tandem solar cell. A 15nm nanocrystalline silicon layer was deposited on the heterocrystalline silicon n-type amorphous silicon as a tunneling composite layer using a plasma-enhanced chemical vapor deposition device.

[0033] (2) A hole transport layer spiro-TTB with a thickness of 25 nm was deposited on nanocrystalline silicon as a tunneling composite layer in a thermal evaporation vacuum deposition equipment at an evaporation rate of 0.02 nm / s. Then, the first step of the vacuum-assisted two-step method for preparing the perovskite light absorption layer was carried out: lead iodide and cesium bromide were co-evaporated using a thermal evaporation vacuum deposition equipment, and the ratio of the vapor deposition rate of lead iodide and cesium bromide was controlled at 1:0.05. A mixed inorganic compound film of lead iodide and cesium bromide with a total thickness of 380 nm was obtained on the hole transport layer.

[0034] (3) The inorganic compound film prepared in step (2) is placed in a sealed container, and a flow rate of 10 is introduced. -3 m 3 A mixture of dimethyl sulfoxide and chlorobenzene vapors with a volume ratio of 1:5 was introduced. After 3 minutes of vapor introduction, the solvent vapor annealing was stopped, and the sample was quickly removed from the sealed container.

[0035] (4) Prepare an ethanol solution of formamidin hydrobromide and formamidin hydroiodide mixed in a mass ratio of 1:4 (formamidin molar concentration of 0.49M). Use this solution to spin-coat the surface of the inorganic compound film prepared in step (3) in a glove box. The spin coater rotates at 3000 rpm for 30 seconds. Immediately afterwards, place it on a 150°C hot plate in a 50% relative humidity environment for annealing for 30 minutes to obtain an unoptimized perovskite polycrystalline film. From Figure 2 The scanning electron microscope image of the perovskite polycrystalline thin film surface shows that the perovskite grains are large and dense.

[0036] (5) A passivation layer of LiF with a thickness of 0.8 nm was deposited on the surface of the pure three-dimensional perovskite light-absorbing layer using a thermal evaporation vacuum deposition apparatus. Following this, an electron transport layer of C with a thickness of 15 nm was deposited using the same apparatus. 60 .

[0037] (6) Using atomic layer deposition equipment in C 60A 18nm SnO2 layer was deposited on the surface as a protective layer, and then a 90nm thick indium tin oxide transparent electrode (indium oxide to tin oxide mass ratio of 97:3) was deposited on the SnO2 surface using physical vapor deposition.

[0038] (7) Finally, a 200 nm thick front-side silver grid line electrode is deposited on the indium tin oxide transparent electrode from step (6) using a thermal evaporation vacuum deposition apparatus. (The silver grid line electrode consists of a main grid and a fine grid, with the effective area of ​​the main grid being 1 cm².) 2 And a 100nm thick antireflection layer of MgF2. From Figure 3 The IV characteristic curves of the tandem solar cell in Example 1 under AM1.5G illumination show an open-circuit voltage of 1.82V and a current density of 19.70mA / cm². 2 The fill factor was 77%, and the photoelectric conversion efficiency was 27.6%. Compared with Control Example 1, the multilayer solar cell showed significant improvements in all aspects of its performance parameters.

[0039] Comparative Example 2: A second type of fully textured perovskite / crystalline silicon tandem solar cell treated with solvent vapor annealing.

[0040] (1) A commercially available double-sided textured heterocrystalline silicon solar cell with no indium tin oxide transparent electrode deposited on the n-type amorphous silicon surface was selected as the bottom cell of the tandem solar cell. A 15nm nanocrystalline silicon layer was deposited on the heterocrystalline silicon n-type amorphous silicon as a tunneling composite layer using a plasma-enhanced chemical vapor deposition device.

[0041] (2) A hole transport layer spiro-TTB with a thickness of 25 nm was deposited on nanocrystalline silicon as a tunneling composite layer in a thermal evaporation vacuum deposition equipment at an evaporation rate of 0.02 nm / s. Then, the first step of the vacuum-assisted two-step method for preparing the perovskite light absorption layer was carried out: lead iodide and cesium bromide were co-evaporated using a thermal evaporation vacuum deposition equipment, and the ratio of the vapor deposition rate of lead iodide and cesium bromide was controlled at 1:0.07. A mixed inorganic compound film of lead iodide and cesium bromide with a total thickness of 490 nm was obtained on the hole transport layer.

[0042] (3) Prepare an ethanol solution of formamidin hydrobromide and formamidin hydroiodide mixed in a mass ratio of 1:4 (formamidin molar concentration of 0.58M). Use this solution to spin-coat the surface of the inorganic compound film prepared in step (2) in a glove box. The spin coater rotates at 3000 rpm for 30 seconds. Immediately afterwards, place it on a 150°C hot plate in a 50% relative humidity environment for annealing for 30 minutes to obtain an unoptimized perovskite polycrystalline film. From Figure 4 The scanning electron microscope image of the surface in Example 2 shows that the perovskite grains in this film are relatively small and not dense.

[0043] (4) A passivation layer of 1 nm thick, LiF, was deposited on the surface of the pure three-dimensional perovskite light-absorbing layer using a thermal evaporation vacuum deposition apparatus. Following this, an electron transport layer of 12 nm thick, C, was deposited using the same apparatus. 60 .

[0044] (5) Using atomic layer deposition equipment in C 60 A 20nm SnO2 layer was deposited on the surface as a protective layer, and then a 100nm thick indium tin oxide transparent electrode (indium oxide to tin oxide mass ratio of 97:3) was deposited on the SnO2 surface using physical vapor deposition.

[0045] (6) Finally, a 200 nm thick front-side silver grid electrode is deposited on the indium tin oxide transparent electrode from step (5) using a thermal evaporation vacuum deposition apparatus. (The silver grid electrode consists of a main grid and a fine grid, with the effective area of ​​the main grid being 1 cm².) 2 And a 100nm thick antireflection layer of MgF2. From Figure 5 Comparing the IV characteristic curves of the tandem solar cell in Example 2 under AM1.5G illumination, we can see that the open-circuit voltage is 1.65V and the current density is 18.52mA / cm². 2 The fill factor is 70%, and the photoelectric conversion efficiency is 21.4%.

[0046] Example 2

[0047] An embodiment of a method for simultaneously improving the open-circuit voltage and stability of a fully textured perovskite / crystalline silicon tandem solar cell includes the following steps:

[0048] (1) A commercially available double-sided textured heterocrystalline silicon solar cell with no indium tin oxide transparent electrode deposited on the n-type amorphous silicon surface was selected as the bottom cell of the tandem solar cell. A 15nm nanocrystalline silicon layer was deposited on the heterocrystalline silicon n-type amorphous silicon as a tunneling composite layer using a plasma-enhanced chemical vapor deposition device.

[0049] (2) A hole transport layer spiro-TTB with a thickness of 25 nm was deposited on nanocrystalline silicon as a tunneling composite layer in a thermal evaporation vacuum deposition equipment at an evaporation rate of 0.02 nm / s. Then, the first step of the vacuum-assisted two-step method for preparing the perovskite light absorption layer was carried out: lead iodide and cesium bromide were co-evaporated using a thermal evaporation vacuum deposition equipment, and the ratio of the vapor deposition rate of lead iodide and cesium bromide was controlled at 1:0.07. A mixed inorganic compound film of lead iodide and cesium bromide with a total thickness of 490 nm was obtained on the hole transport layer.

[0050] (3) The inorganic compound film prepared in step (2) is placed in a sealed container, and a flow rate of 10 is introduced. -2 m3 A mixture of methylpyrrolidone and chlorobenzene vapors was introduced at a volume ratio of 1:10. After 1 minute of vapor introduction, the solvent vapor annealing was stopped, and the sample was quickly removed from the sealed container.

[0051] (4) Prepare an ethanol solution of formamidin hydrobromide and formamidin hydroiodide mixed in a mass ratio of 1:4 (formamidin molar concentration of 0.58M). Use this solution to spin-coat the surface of the inorganic compound film prepared in step (3) in a glove box. The spin coater rotates at 3000 rpm for 30 seconds. Immediately afterwards, place it on a 150°C hot plate in a 50% relative humidity environment for annealing for 30 minutes to obtain an unoptimized perovskite polycrystalline film. From Figure 4 The scanning electron microscope image of the perovskite polycrystalline thin film surface shows that the perovskite grains are large and dense.

[0052] (5) A passivation layer of LiF with a thickness of 1 nm was deposited on the surface of the pure three-dimensional perovskite light-absorbing layer using a thermal evaporation vacuum deposition apparatus. Immediately afterwards, an electron transport layer of C with a thickness of 12 nm was deposited using the same thermal evaporation vacuum deposition apparatus. 60 .

[0053] (6) Using atomic layer deposition equipment in C 60 A 20nm SnO2 layer was deposited on the surface as a protective layer, and then a 100nm thick indium tin oxide transparent electrode (indium oxide to tin oxide mass ratio of 97:3) was deposited on the SnO2 surface using physical vapor deposition.

[0054] (7) Finally, a 200 nm thick front-side silver grid line electrode is deposited on the indium tin oxide transparent electrode from step (6) using a thermal evaporation vacuum deposition apparatus. (The silver grid line electrode consists of a main grid and a fine grid, with the effective area of ​​the main grid being 1 cm².) 2 And a 100nm thick antireflection layer of MgF2. From Figure 5 The IV characteristic curves of the tandem solar cell in Example 2 under AM1.5G illumination show an open-circuit voltage of 1.84V and a current density of 19.75mA / cm². 2 The fill factor was 78%, and the photoelectric conversion efficiency was 28.3%. Compared with Control Example 2, the multilayer solar cell showed significant improvements in all aspects of its performance parameters.

[0055] The above embodiments are merely some preferred embodiments of the present invention and are only used to illustrate the principles and improvements of the present invention. They should not be used to limit the scope of patent protection of the present invention. Those skilled in the art can make various changes, improvements, and refinements to the present invention beyond the spirit and scope of the invention. The additional functions in these improvements can be individual or combined in any way, and these changes, improvements, and refinements should also be considered within the scope of protection of this patent.

Claims

1. A method for modifying a fully textured perovskite / crystalline silicon tandem solar cell, characterized in that: The fully textured perovskite / crystalline silicon tandem solar cell consists of three parts: a double-sided textured heterocrystalline silicon bottom cell, a nanocrystalline silicon tunneling composite layer, and a perovskite top cell. The perovskite polycrystalline thin film in the perovskite top cell is prepared using a two-step annealing method. In the first step, an inorganic compound film is physically deposited on the tunneling composite layer using a thermal evaporation device, and a flow rate of 10... -4 -10 -2 m 3 The first step involves annealing the perovskite polycrystalline film using a mixture of good and bad solvent vapors. The second step involves coating the organic ammonium salt onto the treated inorganic compound film using a liquid-phase method, followed by thermal annealing to complete the preparation of the perovskite polycrystalline film. In the first step of the perovskite top-cell solar cell, an inorganic compound film is deposited. Lead iodide and cesium bromide are co-evaporated using a thermal evaporation vacuum deposition apparatus. The deposition rate ratio of lead iodide to cesium bromide is adjusted to between 1:0.04 and 1:0.08, resulting in an inorganic compound film with a total thickness of 300-800 nm. The first annealing process in the perovskite top-cell solar cell involves placing the sample with the deposited inorganic compound film in a sealed container and introducing a mixture of good and bad solvent vapors. The good solvents are dimethyl sulfoxide and N,N-dimethylformyl. The sample is prepared by mixing an amine or a methylpyrrolidone, with chlorobenzene as the unsuitable solvent, in a volume ratio of 10:1 to 1:

10. After introducing steam for 1-10 minutes, the solvent vapor is stopped for annealing, and the sample is quickly removed from the sealed container. The second step of depositing the organic ammonium salt in the perovskite polycrystalline thin film of the perovskite top solar cell is carried out by liquid phase coating, including any one of spin coating, coating, blade coating, and spray coating. The organic ammonium salt solution is an ethanol solution of formamidinium hydrobromide and formamidinium hydroiodide mixed in a mass ratio of 1:

4. The second annealing of the perovskite polycrystalline thin film in the perovskite top solar cell is carried out by thermal annealing. The sample coated with organic ammonium salt is quickly placed in an environment with a relative humidity of about 50% and thermally annealed on a hot stage at 150°C for 20-40 minutes to complete the preparation of the perovskite polycrystalline thin film.

2. The modification method for a fully textured perovskite / crystalline silicon tandem solar cell according to claim 1, characterized in that: According to the preparation sequence, the perovskite top solar cell consists of a hole transport layer, a perovskite polycrystalline thin film prepared by a two-step annealing process, a passivation layer, an electron transport layer, a protective layer, a front indium tin oxide transparent electrode, a front silver grid line electrode, and an antireflection layer.

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