Perovskite / crystalline silicon tandem solar cell and packaging method and application thereof

Abstract

The application provides a perovskite / crystalline silicon laminated solar cell and an encapsulation method and application thereof, and relates to the technical field of solar cells.The perovskite / crystalline silicon laminated solar cell provided by the application is composed of a heterojunction crystalline silicon bottom cell, an indium tin oxide composite layer and a perovskite top cell; the perovskite top cell comprises, from bottom to top, a nickel oxide hole transport layer, a perovskite light absorption layer, a polymer interface encapsulation layer, a fullerene electron transport layer, a tin dioxide buffer layer, a front indium tin oxide transparent electrode, a front silver grid electrode and a magnesium fluoride anti-reflection layer. By introducing a linear thermoplastic resin interface encapsulation layer containing hydroxyl between the perovskite light absorption layer and the electron transport layer, the linear thermoplastic resin has the characteristic of thermoplasticity, so that the attenuation caused by the change of thermal stress can be relieved, and the long-term operation stability of the device is improved; meanwhile, the coordination between the hydroxyl in the resin and the defect sites of the perovskite realizes persistent chemical passivation, and the photoelectric performance of the device is improved.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, and in particular to a perovskite / crystalline silicon tandem solar cell, its packaging method, and its application. Background Technology

[0002] Solar energy, as a renewable energy source, has become an important part of human energy utilization in the face of increasing fossil fuel shortages. Solar cells used for utility-scale power generation are one of the key technologies that promise to effectively replace traditional fossil fuels and ensure an abundant supply of clean electricity. Among them, tandem solar cells, with their high theoretical photoelectric conversion efficiency (PCE), are increasingly regarded as a key technology for the transition to renewable energy. Perovskite materials, due to their tunable bandgap, have become a promising candidate for the top cell in tandem solar cells. Perovskite / crystalline silicon tandem solar cells are considered one of the most promising and popular photovoltaic technologies, with their PCE increasing from an initial 13.7% to 34.85%, currently the highest efficiency record for this type of cell globally.

[0003] However, due to the poor structural stability of organic-inorganic metal halide perovskites, perovskite / crystalline silicon tandem solar cells can experience severe structural phase transitions and aging degradation under external stresses such as high temperature, light, oxygen, humidity, mechanical stress, and potential, leading to deterioration in device performance. In addition, due to the huge difference in thermal expansion coefficients between perovskite and crystalline silicon, significant thermal stress is generated during the temperature cycling of the device. This stress accelerates the decomposition of perovskite materials, which seriously hinders their commercialization and large-scale deployment.

[0004] To mitigate the instability issues of perovskite / crystalline silicon tandem solar cells, numerous strategies have been explored, including compositional engineering and additive engineering of the perovskite active layer, modification or replacement of charge transport layer materials, interface passivation layer engineering, and even device encapsulation. Among these, small-molecule passivators containing specific functional groups have been widely used for chemical passivation of perovskite surfaces. While these can temporarily passivate surface defects, these small molecules are prone to volatilization and decomposition during long-term operation, potentially poisoning the interface and causing negative effects. Traditional external encapsulation strategies, while blocking water and oxygen, are only temporary solutions and cannot address existing defects and stress issues within the device. Therefore, a solution is urgently needed to improve these problems. Summary of the Invention

[0005] The purpose of this invention is to provide a perovskite / crystalline silicon tandem solar cell, its packaging method, and its application.

[0006] In a first aspect, the present invention provides a perovskite / crystalline silicon tandem solar cell, comprising three parts: a heterogeneous crystalline silicon bottom cell, an indium tin oxide composite layer, and a perovskite top cell; the perovskite top cell sequentially includes a nickel oxide hole transport layer, a perovskite light absorption layer, a polymer interface encapsulation layer, a fullerene electron transport layer, a tin dioxide buffer layer, a front indium tin oxide transparent electrode, a front silver grid electrode, and a magnesium fluoride antireflection layer; the polymer interface encapsulation layer is made of a linear thermoplastic resin material containing hydroxyl groups.

[0007] Optionally, the linear thermoplastic resin material includes at least one of linear thermoplastic phenoxy resin and linear thermoplastic polyether glycol resin; the softening point of the linear thermoplastic resin material is 70℃-150℃.

[0008] Optionally, the heterocrystalline silicon base cell is a heterocrystalline silicon solar cell with a random pyramidal textured surface on its surface; the size of the pyramidal textured surface is 0.5μm-5μm.

[0009] Secondly, the present invention also provides a method for encapsulating any of the above-mentioned optional perovskite / crystalline silicon tandem solar cells, comprising the following steps:

[0010] (1) Dissolve the linear thermoplastic resin material containing hydroxyl groups in an organic solvent to prepare a solution with a concentration of 1 mg / mL-10 mg / mL;

[0011] (2) The solution prepared in step (1) is deposited on the surface of the perovskite light absorption layer in the perovskite top cell using a dynamic liquid phase coating method.

[0012] (3) Annealing is performed at a temperature of 70℃-150℃ to form a polymer interface encapsulation layer.

[0013] Optionally, the dynamic liquid phase coating method includes dynamic spin coating or dynamic spray coating.

[0014] Optionally, the organic solvent is an alcohol solvent; the alcohol solvent includes isopropanol.

[0015] Optionally, the perovskite light-absorbing layer is prepared by deposition on a heterogeneous crystalline silicon substrate with a pyramidal textured surface using a one-step solution method or a vacuum-assisted two-step method, followed by annealing.

[0016] Thirdly, the present invention also provides an application of any of the above-mentioned optional perovskite / crystalline silicon tandem solar cells in a photovoltaic power generation system.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] (1) The perovskite / crystalline silicon tandem solar cell provided by the present invention introduces a linear thermoplastic resin interface encapsulation layer containing hydroxyl groups between the perovskite light absorption layer and the electron transport layer, thereby achieving internal interface encapsulation with both durable chemical passivation and efficient stress release capabilities, fundamentally solving the technical problem that small molecule passivators are prone to failure and cannot alleviate thermal stress.

[0019] (2) The perovskite / crystalline silicon tandem solar cell provided by the present invention utilizes the hydroxyl groups on the linear thermoplastic resin molecular chain, whose lone pair electrons of oxygen atoms interact with the undercoordinated lead ions (Pb) in the perovskite. 2+ Stable coordination interactions occur, effectively passivating surface defects, enhancing interfacial bonding, and inhibiting the growth of metallic lead (Pb). 0 The formation of this process significantly improves the photoelectric performance and stability of perovskite / crystalline silicon tandem solar cells.

[0020] (3) The perovskite / crystalline silicon tandem solar cell provided by the present invention utilizes the high flexibility of linear thermoplastic resin polymer chains, low melting temperature and glass transition temperature, and the characteristic that materials with specific softening points between 70°C and 150°C can be selected to match the thermal annealing temperature of the perovskite light absorption layer. This can effectively release residual strain in the perovskite and suppress lattice distortion caused by phase transition. Furthermore, the linear thermoplastic resin can soften and flow when heated and return to solid state after cooling, exhibiting good toughness and processability. This alleviates the interfacial stress between the perovskite light absorption layer and the electron transport layer, which is beneficial to the long-term operational stability of the device under periodic lattice strain.

[0021] Mechanism of action of this invention:

[0022] To address the two main issues affecting the long-term stability of perovskite / crystalline silicon tandem solar cells: First, the perovskite light-absorbing layer has many defects on its surface, and small molecule passivation is prone to failure after long-term operation; second, the thermal expansion coefficients of perovskite and crystalline silicon materials differ greatly, and the thermal stress present during long-term operation leads to material degradation, which mainly originates at the interface between the perovskite light-absorbing layer and the electron transport layer.

[0023] This invention proposes a method for introducing a polymer interface encapsulation layer into perovskite / crystalline silicon tandem solar cells. For the first time, a linear thermoplastic resin material containing hydroxyl groups is used at the interface between the perovskite light-absorbing layer and the electron transport layer. The thermoplastic properties of the linear thermoplastic resin provide excellent mechanical toughness, which can greatly eliminate the accumulation of thermal stress during device operation, alleviate the attenuation caused by thermal stress changes, and avoid the key problem of passivation failure of small-molecule passivation materials under thermal stress, thus improving the long-term operational stability of the tandem solar cell. Furthermore, by forming a stable polymer interface encapsulation layer through dynamic liquid-phase coating, the hydroxyl groups in the polymer resin can passivate surface defects, improve the interfacial bonding force between the perovskite light-absorbing layer and the electron transport layer, suppress interfacial non-radiative recombination losses, and improve carrier transport, thereby enhancing the photoelectric performance of the device. Attached Figure Description

[0024] Figure 1 This is a structural diagram of the perovskite / crystalline silicon tandem solar cell prepared in Example 1.

[0025] Figure 2 The graph shows the JV test results of the perovskite / crystalline silicon tandem solar cells prepared in Example 1 and Comparative Example 1 of this invention.

[0026] Figure 3 The PCE evolution diagrams for the perovskite / crystalline silicon tandem solar cells prepared in Example 1 and Comparative Example 1 of this invention under maximum power point tracking at 40-60% relative humidity, 25°C air environment, and continuous illumination with 1 times the solar light intensity are shown. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, 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. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by those skilled in the art to which this invention pertains.

[0028] This invention provides a perovskite / crystalline silicon tandem solar cell, comprising three parts: a heterogeneous crystalline silicon bottom cell, an indium tin oxide (ITO) composite layer, and a perovskite top cell. The perovskite top cell sequentially includes a nickel oxide hole transport layer, a perovskite light absorption layer, a polymer interface encapsulation layer, a fullerene electron transport layer, a tin dioxide buffer layer, a front ITO transparent electrode, a front silver grid electrode, and a magnesium fluoride antireflection layer. The polymer interface encapsulation layer is made of a linear thermoplastic resin containing hydroxyl groups. In essence, this invention introduces a hydroxyl-containing linear thermoplastic resin interface encapsulation layer between the perovskite light absorption layer and the electron transport layer. On the one hand, this utilizes the coordination of the hydroxyl groups in the resin with the perovskite defect sites to achieve durable chemical passivation, improving the device's photoelectric performance. On the other hand, the linear thermoplastic resin also possesses thermoplastic properties, which can alleviate degradation caused by thermal stress changes and improve the long-term operational stability of the device.

[0029] In some embodiments, the linear thermoplastic resin material used includes at least one of linear thermoplastic phenoxy resin and linear thermoplastic polyether glycol resin; the softening point of the linear thermoplastic resin material used is 70°C-150°C.

[0030] Specifically, linear thermoplastic resin molecules have high polymer chain flexibility and low melting and glass transition temperatures. By selecting linear thermoplastic phenoxy resin and linear thermoplastic polyether glycol resin materials with specific softening points between 70°C and 150°C and matching them with the thermal annealing temperature of the perovskite light absorption layer, residual strain in the perovskite can be effectively released and lattice distortion caused by phase transition can be suppressed.

[0031] In some embodiments, the heterocrystalline silicon base cell used is a heterocrystalline silicon solar cell with a random pyramid textured surface; wherein the size of the pyramid textured surface is 0.5μm-5μm.

[0032] The present invention also provides a method for encapsulating perovskite / crystalline silicon tandem solar cells in any of the above embodiments, comprising the following steps:

[0033] (1) Dissolve the linear thermoplastic resin material containing abundant hydroxyl groups in an organic solvent to prepare a solution with a concentration of 1 mg / mL-10 mg / mL;

[0034] (2) The solution prepared in step (1) is deposited on the surface of the perovskite light absorption layer in the perovskite top cell using a dynamic liquid phase coating method.

[0035] (3) Annealing is performed at a temperature of 70℃-150℃ to form a polymer interface encapsulation layer.

[0036] In some embodiments, the dynamic liquid phase coating method employed includes dynamic spin coating or dynamic spray coating.

[0037] In fact, by forming an interface encapsulation layer through dynamic liquid phase coating technology (dynamic spin coating / dynamic spray coating), the coating process can be optimized according to the size of the pyramid textured surface of the heterogeneous crystalline silicon substrate, ensuring the formation of a uniform, shape-preserving, high-quality thin film on a complex three-dimensional substrate, thus guaranteeing the universality of the process and the repeatability of high-performance devices.

[0038] Specifically, the method for preparing the polymer interface encapsulation layer can be selected based on the size of the pyramid textured surface of the heterocrystalline silicon base cell; when the size of the pyramid textured surface of the heterocrystalline silicon base cell is less than 1 micrometer, dynamic spin coating is preferred; when the size of the pyramid textured surface of the heterocrystalline silicon base cell is greater than 1 micrometer, dynamic spray coating is preferred.

[0039] In some embodiments, the organic solvent used is an alcohol solvent; specifically, isopropanol is preferred.

[0040] In some embodiments, the perovskite light-absorbing layer is prepared by deposition on a heterogeneous crystalline silicon substrate with a pyramidal textured surface using a one-step solution method or a vacuum-assisted two-step method, followed by annealing.

[0041] Specifically, when the pyramid textured surface size of the heterocrystalline silicon substrate is less than 1 micrometer, a one-step solution method is preferred, in which a 1.7M perovskite precursor solution is prepared and the perovskite light-absorbing layer is prepared by spin coating or slot coating. When the pyramid textured surface size of the heterocrystalline silicon substrate is greater than 1 micrometer, a vacuum-assisted two-step method is preferred, in which lead iodide and cesium bromide are first co-deposited by vacuum technology, and then they are reacted with formamidinium halide in the liquid phase to prepare a conformally conformal perovskite light-absorbing layer covering the pyramid textured surface.

[0042] The present invention also provides an application of perovskite / crystalline silicon tandem solar cells in any of the above embodiments in a photovoltaic power generation system.

[0043] Example 1

[0044] This embodiment 1 provides a method for fabricating a perovskite / crystalline silicon tandem solar cell, including the following steps:

[0045] S1. Fabrication of heterogeneous crystalline silicon bottom cell: An intrinsic monocrystalline silicon wafer with a resistivity of 1-5 ohms, a thickness of 150 μm, and a pyramid texture size of 0.5 μm was selected. 7 nm of intrinsic amorphous silicon was grown on both the front and back sides of the intrinsic monocrystalline silicon wafer using plasma-enhanced chemical vapor deposition (PECVD). A 6 nm thick n-type amorphous silicon film was deposited on the intrinsic amorphous silicon grown on the front side, and an 8 nm thick p-type amorphous silicon film was deposited on the intrinsic amorphous silicon grown on the back side. An 80 nm thick indium tin oxide (ITO) transparent electrode was deposited on the p-type amorphous silicon film using magnetron sputtering. A 200 nm thick back silver electrode was deposited on the ITO transparent electrode using thermal evaporation vacuum deposition equipment to obtain the heterogeneous crystalline silicon bottom cell.

[0046] S2. Fabrication of the composite layer: The heterocrystalline silicon bottom cell with its front side facing down is placed in a custom mask. In a magnetron sputtering device, the mask is placed on a carrier to deposit 15nm indium tin oxide as a composite layer. The composite layer connects the heterocrystalline silicon bottom cell and the perovskite top cell.

[0047] S3, Fabrication of perovskite top solar cells:

[0048] S31. Preparation of hole transport layer of perovskite top cell: The selected hole transport material is nickel oxide. The nickel oxide thin film is prepared by magnetron sputtering and the film thickness is 10 nm.

[0049] S32. Preparation of the perovskite light-absorbing layer for the perovskite top solar cell: Cesium iodide, methylamine iodate, formamidinium iodate, formamidinium bromate, lead iodide, and lead bromide were dissolved in a solvent of DMF (N,N-dimethylformamide) and DMSO (dimethyl sulfoxide) in a molar ratio of 0.05:0.55:0.20:0.75:0.25:0.25 to prepare the required perovskite precursor solution. In a nitrogen glove box, the conductive substrate with the nickel oxide hole transport layer obtained in step S31 was placed on a spin coater. 75 μL of the perovskite precursor solution was spin-coated onto the hole transport layer at a spin speed of 2000 r / min for 45 s. At 10 s of spin coating time, 200 μL of ethyl acetate was added as an antisolvent. After spin coating, the perovskite light-absorbing layer was annealed at 110℃ for 20 min to obtain the perovskite light-absorbing layer.

[0050] S33. Preparation of the polymer interface encapsulation layer for perovskite top battery: Linear thermoplastic phenoxy resin was dissolved in isopropanol to prepare a solution with a concentration of 2 mg / mL. The preparation method was dynamic spin coating, with a spin coating speed of 5000 r / min and a spin coating time of 30 s. After spin coating, the solution was annealed at 9℃ for 5 minutes to obtain the linear thermoplastic phenoxy resin interface encapsulation layer.

[0051] S34. Fabrication of the electron transport layer and buffer layer of the perovskite top cell: A 10 nm layer of C was deposited on the surface of the polymer interface encapsulation layer using a thermal evaporation device at a deposition rate of 0.2 Å / s. 60 As an electron transport layer (belonging to the fullerene electron transport layer), it is transferred to an atomic layer deposition device and deposited for 150 cycles using tin and water sources to obtain a tin dioxide buffer layer with a thickness of 20 nm.

[0052] S35. Fabrication of the top electrode of the perovskite top cell: A 50 nm thick indium tin oxide transparent electrode was deposited on the surface of the SnO2 buffer layer using magnetron sputtering. Then, a 400 nm thick silver grid electrode was deposited on the front side using thermal evaporation. Finally, a 100 nm thick magnesium fluoride antireflection layer was deposited. The resulting perovskite / crystalline silicon tandem solar cell is shown in the diagram below. Figure 1 As shown.

[0053] Compare with Example 1

[0054] This Comparative Example 1 provides a method for preparing a perovskite / crystalline silicon tandem solar cell. The difference from Example 1 is that the preparation of the polymer interface encapsulation layer in step S33 is not performed, resulting in a perovskite / crystalline silicon tandem solar cell without a polymer interface encapsulation layer.

[0055] Performance verification

[0056] (1) Verification of photoelectric performance of perovskite / crystalline silicon tandem solar cells

[0057] The performance of the solar cells in Example 1 and Control Example 1 was tested using a solar simulator, and the results are as follows: Figure 2 As shown. Comparing the current-voltage curves of the perovskite / crystalline silicon tandem solar cell without an interface encapsulation layer in Example 1, it can be seen that the short-circuit current density is 20.27 mA / cm². 2 The open-circuit voltage was 1.917V, the fill factor was 73.76%, and the power conversion efficiency (PCE) was 28.66%. In Example 1, the short-circuit current density of the perovskite / crystalline silicon tandem solar cell with a linear thermoplastic phenoxy resin interface encapsulation layer was 20.40 mA / cm². 2 The open-circuit voltage was 1.972V, the fill factor was 74.78%, and the photoelectric conversion efficiency (PCE) was 30.09%. Compared with Comparative Example 1, the open-circuit voltage and fill factor of the stacked device in Example 1 were significantly improved, thereby enhancing the photoelectric performance.

[0058] (2) Stability verification of perovskite / crystalline silicon tandem solar cells

[0059] The long-term stability of the solar cells in Example 1 and Control Example 1 was tested using a solar cell stability testing system. The results are as follows: Figure 3 As shown. In the long-term stability test, based on the ISOS-L-1 test standard, the perovskite / crystalline silicon tandem solar cells in Example 1 and Control Example 1 were subjected to a maximum power point tracking test under continuous 1x sunlight irradiation in an air environment of 25°C and 40-60% relative humidity. The results showed that the photoelectric conversion efficiency of the perovskite / crystalline silicon tandem solar cell without an interface encapsulation layer in Control Example 1 retained only 48% of the initial value after 1000 hours; the photoelectric conversion efficiency of the perovskite / crystalline silicon tandem solar cell in Example 1 with a linear thermoplastic phenyloxy resin interface encapsulation layer retained 80% of the initial value after 1000 hours, indicating that the tandem device with a linear thermoplastic phenyloxy resin interface encapsulation layer has better long-term stability.

[0060] While embodiments of the present invention have been described in detail above, it will be apparent to those skilled in the art that various modifications and variations can be made to these embodiments. However, it should be understood that such modifications and variations fall within the scope and spirit of the invention as set forth in the claims. Furthermore, the invention described herein may have other embodiments and can be implemented or carried out in various ways.

Claims

1. A perovskite / crystalline silicon tandem solar cell, characterized in that, The perovskite / crystalline silicon tandem solar cell comprises three parts: a heterogeneous crystalline silicon bottom cell, an indium tin oxide composite layer, and a perovskite top cell. The perovskite top cell, from bottom to top, includes a nickel oxide hole transport layer, a perovskite light absorption layer, a polymer interface encapsulation layer, a fullerene electron transport layer, a tin dioxide buffer layer, a front indium tin oxide transparent electrode, a front silver grid electrode, and a magnesium fluoride antireflection layer. The polymer interface encapsulation layer is made of a linear thermoplastic resin containing hydroxyl groups. The heterogeneous crystalline silicon bottom cell is a heterogeneous crystalline silicon solar cell with a random pyramidal textured surface. The size of the pyramidal textured surface is 0.5 μm-5 μm. The encapsulation method of the perovskite / crystalline silicon tandem solar cell is characterized by the following steps: (1) Dissolve the linear thermoplastic resin material containing hydroxyl groups in an organic solvent to prepare a solution with a concentration of 1 mg / mL-10 mg / mL; (2) The solution prepared in step (1) is deposited on the surface of the perovskite light absorption layer in the perovskite top cell using a dynamic liquid phase coating method. (3) Annealing is performed at a temperature of 70℃-150℃ to form a polymer interface encapsulation layer.

2. The perovskite / crystalline silicon tandem solar cell according to claim 1, characterized in that, The linear thermoplastic resin material includes at least one of linear thermoplastic phenoxy resin and linear thermoplastic polyether glycol resin; the softening point of the linear thermoplastic resin material is 70℃-150℃.

3. The perovskite / crystalline silicon tandem solar cell according to claim 1, characterized in that, The dynamic liquid phase coating method includes dynamic spin coating or dynamic spray coating.

4. The perovskite / crystalline silicon tandem solar cell according to claim 1, characterized in that, The organic solvent is an alcohol solvent; the alcohol solvent includes isopropanol.

5. The perovskite / crystalline silicon tandem solar cell according to claim 1, characterized in that, The perovskite light-absorbing layer is prepared by deposition on a heterogeneous crystalline silicon substrate with a pyramidal textured surface using a one-step solution method or a vacuum-assisted two-step method, followed by annealing.

6. An application of the perovskite / crystalline silicon tandem solar cell as described in any one of claims 1-5 in a photovoltaic power generation system.

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