Solar cell, preparation method thereof and photovoltaic module

Abstract

The invention provides a solar cell and a preparation method thereof, and a photovoltaic module, the solar cell comprises a flexible substrate, and a first transmission layer, a liquid crystal layer, a perovskite layer and a second transmission layer which are sequentially arranged on the flexible substrate, and holes are distributed in the liquid crystal layer and form a mesh porous structure; and the bending resistance and the photoelectric conversion efficiency of the flexible perovskite solar cell are improved.

Description

Technical Field

[0001] This application relates to the field of solar cells, and more particularly to a solar cell and its preparation method, and a photovoltaic module. Background Technology

[0002] Perovskite solar cells are devices that convert solar energy into electrical energy, and they have attracted widespread attention due to their excellent photoelectric properties.

[0003] Flexible perovskite solar cells are a type of perovskite solar cell based on flexible material substrates, offering advantages such as thinness and shapeability. However, current flexible perovskite solar cells suffer from low photoelectric conversion efficiency and low bending resistance, limiting their further development. Summary of the Invention

[0004] To address the aforementioned technical problems, this application discloses a solar cell and its fabrication method, as well as a photovoltaic module, to improve the bending resistance and photoelectric conversion efficiency of flexible perovskite solar cells.

[0005] In a first aspect, this application provides a solar cell, including a flexible substrate and a first transport layer, a liquid crystal layer, a perovskite layer and a second transport layer sequentially disposed on the flexible substrate, wherein the liquid crystal layer has pores distributed in it and forms a mesh-like porous structure.

[0006] In some embodiments of this application, the number of holes is 10,000 per 1 cm. 2 ~20,000 pieces / 1cm 2 .

[0007] In some embodiments of this application, the thickness of the liquid crystal layer is 3μm to 10μm.

[0008] In some embodiments of this application, the perovskite layer further includes an intermediate phase formed by the coordination of acid radical ions with perovskite metal ions, wherein the acid radical ions are generated by the decomposition of bianionic compounds during the formation of the perovskite layer.

[0009] In some embodiments of this application, the bianionic compound includes at least one of acetamide hydrochloride and dodecyl 2-(dimethylamino)propionate hydrochloride.

[0010] In some embodiments of this application, the first transport layer is an electron transport layer and the second transport layer is a hole transport layer;

[0011] Alternatively, the first transport layer may be a hole transport layer, and the second transport layer may be an electron transport layer.

[0012] In some embodiments of this application, the solar cell further includes a first conductive layer located between the flexible substrate and the first transport layer.

[0013] In some embodiments of this application, the solar cell further includes a second conductive layer and an electrode, wherein the second conductive layer is located on the side of the flexible substrate opposite to the first conductive layer, and the electrode is located on the side of the second transport layer opposite to the perovskite layer.

[0014] In some embodiments of this application, the liquid crystal elastomer material in the liquid crystal layer includes at least one of polyethylene glycol diacrylate and mercapto-acrylate.

[0015] In some embodiments of this application, the flexible substrate is made of at least one of polyethylene terephthalate and polyethylene naphthalate.

[0016] Secondly, this application provides a method for fabricating a solar cell as described in the first aspect, comprising the following steps:

[0017] A flexible substrate having a first conductive layer and a second conductive layer is provided;

[0018] A first transport layer, a liquid crystal layer, a perovskite layer, a second transport layer, and an electrode are sequentially fabricated on the surface of the first conductive layer of the flexible substrate.

[0019] The fabrication process of the liquid crystal layer includes:

[0020] A microsphere template is prepared on the surface of the first transport layer;

[0021] A liquid crystal elastomer material is applied to the microsphere template, and the liquid crystal elastomer material is deposited on the surface of the first transport layer through the gaps between the microspheres;

[0022] Remove the microsphere template and form the liquid crystal layer with a mesh-like porous structure on the surface of the first transport layer.

[0023] In some embodiments of this application, the microspheres in the microsphere template are silica microspheres, and the average particle size of the silica microspheres is 1 μm to 10 μm.

[0024] In some embodiments of this application, the preparation process of the perovskite layer includes:

[0025] A perovskite precursor solution containing perovskite material and the aforementioned bis-anionic compound is spin-coated onto the surface of the liquid crystal layer, and after annealing, the perovskite layer is obtained.

[0026] In some embodiments of this application, the molar concentration of the bis-anionic compound in the perovskite precursor solution is 0.003 mol / L to 0.01 mol / L.

[0027] Thirdly, this application provides a photovoltaic module, which includes a solar cell as described in the first aspect, or the photovoltaic module includes a solar cell prepared by the preparation method described in the second aspect.

[0028] Compared with the prior art, this application has at least the following beneficial effects:

[0029] The solar cell and its fabrication method, as well as the photovoltaic module provided in this application, include a flexible substrate and a first transport layer, a liquid crystal layer, a perovskite layer, and a second transport layer sequentially disposed on the flexible substrate. The liquid crystal layer contains pores, forming a mesh-like porous structure. This mesh-like porous structure allows the perovskite material in contact with the perovskite layer to fill the pores, thereby improving the adhesion between the perovskite layer and the liquid crystal layer. Furthermore, it exhibits good elasticity; during bending of the flexible substrate, the deformation of the pores absorbs the stress generated by bending, making the perovskite layer less prone to cracking during bending and thus less susceptible to damage. This improves the bending resistance and photoelectric conversion efficiency of the flexible perovskite solar cell. The solar cell of this application is more suitable for applications such as large-area, high-efficiency flexible perovskite photovoltaic devices and wearable devices. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a schematic diagram of the structure of a solar cell in one embodiment of this application;

[0032] Figure 2 This is a schematic diagram of the structure of the liquid crystal layer in one embodiment of this application;

[0033] Figure 3 This is a schematic diagram of the structure of a solar cell in another embodiment of this application;

[0034] Figure 4 This is a schematic diagram of the structure of a solar cell in another embodiment of this application;

[0035] Figure 5This is a schematic diagram of the structure of the solar cell in the fourth embodiment of this application;

[0036] Figure 6 This is a scanning electron microscope (SEM) image of the silica microsphere template in Example 2 of this application;

[0037] Figure 7 This is a SEM image of the liquid crystal layer in Embodiment 1 of this application.

[0038] Explanation of reference numerals in the attached drawings: Flexible substrate-1, First conductive layer-2, First transport layer-3, Liquid crystal layer-4, Perovskite layer-5, Second transport layer-6, Electrode-7, Second conductive layer-8, Hole-41. Detailed Implementation

[0039] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0040] In this application, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0041] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0042] Furthermore, the terms "installation," "setup," "equipped with," "connection," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0043] Furthermore, the terms "first," "second," etc., are primarily used to distinguish different devices, elements, or components (which may be the same or different in specific type and construction), and are not intended to indicate or imply the relative importance or quantity of the indicated devices, elements, or components. Unless otherwise stated, "a plurality of" means two or more.

[0044] The technical solution of this application will be further described below with reference to the embodiments and accompanying drawings.

[0045] The flexible perovskite solar cells of related technologies suffer from poor interface quality between the perovskite layer and the flexible substrate due to the low interfacial adhesion of the perovskite layer and the large deformation of the flexible substrate. This results in poor bending mechanical stability of the flexible perovskite solar cells. When the perovskite film is bent, its crystal structure will be twisted and deformed, and the crystal lattice will be distorted. These distortions will affect the migration of charge carriers and energy transfer processes in the perovskite layer, thereby affecting the photoelectric conversion efficiency of the solar cell.

[0046] In view of this, firstly, this application provides a solar cell, which can be a flexible perovskite solar cell. For example... Figure 1 As shown, the solar cell includes a flexible substrate 1 and a first transport layer 3, a liquid crystal layer 4, a perovskite layer 5, and a second transport layer 6 sequentially disposed on the flexible substrate 1. Furthermore, the solar cell also includes a first conductive layer 2 and an electrode 7. The first conductive layer 2 is located between the flexible substrate 1 and the first transport layer 3, and the electrode 7 is located on the side of the second transport layer 6 facing away from the perovskite layer 5. (Reference) Figure 2 The liquid crystal layer 4 has holes 41 distributed in it, forming a mesh-like porous structure. The flexible substrate 1 of this application can be made of a flexible material with high insulation; the first conductive layer can be formed of conductive materials such as indium tin oxide (ITO) or fluorine-doped tin oxide (FTO).

[0047] The solar cell of this application features a liquid crystal layer with a mesh-like porous structure. This structure allows the perovskite material at the contact points with the liquid crystal layer to fill the pores, improving adhesion between the perovskite and liquid crystal layers. Furthermore, this liquid crystal layer exhibits good elasticity, absorbing stress generated during bending of the flexible substrate through the deformation of the pores, preventing stress concentration in the perovskite layer, and reducing the likelihood of cracking. This makes the perovskite layer less susceptible to damage during bending, thus improving the bending resistance and photoelectric conversion efficiency of the flexible perovskite solar cell. Moreover, compared to liquid crystal layers without a mesh-like porous structure, this application reduces the amount of liquid crystal elastomer used at the same thickness, thereby lowering manufacturing costs. Since large-area flexible perovskite photovoltaic devices are more susceptible to bending, and wearable devices are more prone to bending during wear, the solar cell of this application is more suitable for applications such as large-area, high-efficiency flexible perovskite photovoltaic devices and wearable devices.

[0048] In one alternative implementation, the number of holes is 10,000 per 1 cm. 2 ~20,000 pieces / 1cm 2 .

[0049] In this application, the liquid crystal layer can be observed along its thickness direction using a scanning electron microscope at a magnification of 200K to obtain a SEM image of the liquid crystal layer. Among these, 1 cm... 2 The region can be any pre-selected area in the SEM image of the liquid crystal layer, for example, a 1cm × 1cm rectangular area. When the number of holes per unit area is too small (e.g., less than 10,000 per 1cm),... 2 The perovskite material has a small contact area with the first transport layer, which affects the photoelectric conversion efficiency. Furthermore, when the number of pores per unit area is excessive (e.g., more than 20,000 pores / cm), the efficiency is also affected. 2 This can affect the strength of the liquid crystal elastomer, which is detrimental to improving the bending resistance of solar cells. When the number of holes per unit area is within the above range, the liquid crystal layer exhibits good elasticity, which is beneficial to improving the bending resistance of solar cells while enabling them to have excellent photoelectric conversion efficiency.

[0050] In one optional embodiment, the average diameter of the pores is 0.5 μm to 1 μm. When the average diameter of the pores is too small (e.g., less than 0.5 μm), the number of pores per unit area is too large, affecting the strength of the liquid crystal elastomer; when the average diameter of the pores is too large (e.g., greater than 1 μm), the number of pores per unit area is reduced, resulting in a smaller contact area between the perovskite material and the first transport layer, affecting the photoelectric conversion efficiency. By controlling the average diameter of the pores within the above range, it is beneficial to improve the bending resistance of the solar cell while enabling it to have excellent photoelectric conversion efficiency.

[0051] In one optional embodiment, the thickness of the liquid crystal layer is 3 μm to 10 μm. By adjusting the thickness of the liquid crystal layer within the above range, while improving the bending resistance of the liquid crystal elastomer, the transport distance of charge carriers in contact with the perovskite material and the first transport layer from the perovskite layer to the first transport layer remains relatively short, thus preventing the charge carriers from recombinizing.

[0052] The inventors discovered that the perovskite layer affects the photoelectric conversion efficiency of solar cells, and the film quality of the perovskite layer mainly depends on the nucleation and growth process of the perovskite material. In an optional embodiment, the perovskite layer also includes an intermediate phase formed by the coordination of acid radical ions generated from the decomposition of a dianionic compound with perovskite metal ions. During the formation of the perovskite layer, this phase can reduce the preferential precipitation of PbI2, resulting in a slower and more uniform nucleation and growth rate of perovskite grains. The acid radical ions, generated from the decomposition of the dianionic compound during the formation of the perovskite layer, play a regulatory role in the nucleation and preferential growth of perovskite grains.

[0053] The inventors discovered that because perovskite materials crystallize rapidly during film formation, existing perovskite layers are more prone to defects such as vacancies, interstitial spaces, grain boundaries, and dangling bonds at interfaces. This leads to a decrease in carrier mobility, electron collection efficiency, and hole collection efficiency at the interfaces between the perovskite layer and the first transport layer, and at the second transport layer. Therefore, the perovskite layer of this application also includes a bi-anionic compound. The bi-anions in this type of compound induce preferred orientation growth of perovskite grains, thereby reducing lattice defects in the perovskite layer and improving carrier mobility, electron collection efficiency, and hole collection efficiency at the interfaces between the perovskite layer and the first transport layer, and at the second transport layer. Furthermore, while reducing lattice defects in the perovskite layer, the bi-anionic compound of this application, through synergistic interaction with the liquid crystal layer of this application, simultaneously improves the initial photoelectric conversion efficiency and the photoelectric conversion efficiency after bending of the solar cell; that is, it simultaneously improves the bending resistance and photoelectric conversion efficiency of the solar cell.

[0054] In an optional embodiment, the bianionic compound includes at least one of acetamide hydrochloride and dodecyl 2-(dimethylamino)propionate hydrochloride. The acetamide hydrochloride described above has a Cl... - and -CH3COO - Bianionic, dodecyl 2-(dimethylamino)propionate hydrochloride has Cl - and -COO - Bi-anion. Exemplarily, during the crystallization process of perovskite materials, the Cl in dodecyl 2-(dimethylamino)propionate hydrochloride... - It can induce the formation of an intermediate transition phase, which then transforms into an α-phase perovskite structure. During annealing, Cl... - It can evaporate in the form of hydrogen chloride gas; the -COO in it - The group as a Lewis base and Pb in perovskite materials 2+ Coordination is used to reduce defects in the perovskite lattice. It is evident that this application utilizes two anions (i.e., di-anions) to induce preferred orientation growth of perovskite grains, reducing lattice defects, achieving larger grain sizes, providing abundant carrier migration channels, and improving carrier mobility, electron collection efficiency, and hole collection efficiency at the interfaces between the perovskite and the first and second transport layers. This effectively extends carrier lifetime and further enhances the photoelectric performance of flexible perovskite solar cells.

[0055] In one alternative implementation, such as Figure 3 As shown, the first transport layer 3 is an electron transport layer, and the second transport layer 6 is a hole transport layer. This structure is a formal perovskite solar cell structure; or, as... Figure 4 As shown, the first transport layer 3 is a hole transport layer, and the second transport layer 6 is an electron transport layer. This structure is an inverted perovskite solar cell structure. The liquid crystal layer of this application can be applied to both conventional perovskite solar cell structures and inverted perovskite solar cell structures, thus broadening the application scenarios of perovskite solar cells.

[0056] In one alternative implementation, such as Figure 5 As shown, the solar cell also includes a second conductive layer 8 and an electrode 7. The second conductive layer 8 is located on the side of the flexible substrate 1 facing away from the first conductive layer 2, and the electrode 7 is located on the side of the second transport layer 6 facing away from the perovskite layer 5. The second conductive layer can be formed using conductive materials such as ITO or FTO. The second conductive layer can enhance its conductivity. Depositing a layer of conductive ITO or FTO material on the outermost layer can improve the corrosion resistance of the glass and extend the service life of the perovskite solar cell.

[0057] In one optional embodiment, the liquid crystal elastomer material in the liquid crystal layer includes at least one of polyethylene glycol diacrylate and mercapto-acrylate, preferably polyethylene glycol diacrylate. Polyethylene glycol diacrylate has the advantages of good biocompatibility and biodegradability, and can undergo polymerization under heating, light, and radiation by using a certain amount of initiator. During the polymerization reaction, the molecular arrangement is locked, thereby forming an ordered liquid crystal layer, which can provide higher surface energy and nucleation density, thus promoting the nucleation and crystallization process of the perovskite layer. Polyethylene glycol diacrylate and mercapto-acrylate can optimize the charge collection efficiency of the first and second transport layers, suppress carrier recombination at the bottom interface, and enhance the flexibility of the flexible perovskite solar cell by utilizing the stretchability of the liquid crystal elastomer itself.

[0058] This application does not impose any particular restrictions on the material of the flexible substrate, as long as the solar cell of this application can be obtained. In one optional embodiment, the material of the flexible substrate includes at least one of polyethylene terephthalate (PET) and polyethylene naphthalate (PEN).

[0059] Secondly, this application provides a method for fabricating a solar cell as described in the first aspect, comprising the following steps:

[0060] A flexible substrate having a first conductive layer and a second conductive layer is provided;

[0061] A first transport layer, a liquid crystal layer, a perovskite layer, a second transport layer, and an electrode are sequentially fabricated on the surface of the first conductive layer of a flexible substrate.

[0062] The preparation process of the liquid crystal layer includes:

[0063] Microsphere templates were prepared on the surface of the first transport layer;

[0064] Liquid crystal elastomer material is applied to a microsphere template, and the liquid crystal elastomer material is deposited on the surface of the first transport layer through the gaps between the microspheres.

[0065] The microsphere template is removed, and a liquid crystal layer with a mesh-like porous structure is formed on the surface of the first transport layer.

[0066] The flexible substrate in this application can be a transparent flexible substrate, such as PET film or PEN film. This application does not impose any particular limitation on the thickness of the flexible substrate; the thickness can be adjusted according to actual needs. For example, the thickness of the flexible substrate can be 50 μm without special restriction. The flexible substrate can be rinsed with deionized water, then blown clean with compressed air, and treated with ultraviolet ozone for 8–10 minutes. The ultraviolet light and ozone oxidize and remove grease and organic matter from the substrate surface, achieving a cleaning effect.

[0067] The first and second conductive layers of this application can be ITO layers or FTO layers. The aforementioned ITO or FTO layers with a thickness of 130 nm to 160 nm can be formed on the front and back sides of a flexible substrate by magnetron sputtering. The sheet resistance of the deposited surface is 20 ohm / sq to 50 ohm / sq, and the transmittance is 80 to 90%.

[0068] This application does not impose any particular limitations on the preparation methods of the first transport layer, the perovskite layer, and the second transport layer. For example, in the preparation of a formal perovskite solar cell, tin dioxide (SnO2) can be spin-coated onto the surface of the first conductive layer to form an electron transport layer with a thickness of 18 nm to 24 nm, serving as the first transport layer; perovskite material can be spin-coated onto the surface of the first transport layer to form a perovskite layer with a thickness of 450 nm to 550 nm; and hole transport layer material can be spin-coated onto the surface of the perovskite layer to form a hole transport layer with a thickness of 25 nm to 35 nm, serving as the second transport layer.

[0069] This application can form a liquid crystal layer with a network porous structure based on the template method. The liquid crystal layer prepared by the template method has the advantage of uniform distribution of the network porous structure, which enables the liquid crystal layer to absorb the stress generated by bending more fully, and makes the perovskite layer attached to it less prone to cracking during bending.

[0070] In one optional embodiment, the microspheres in the microsphere template are silica microspheres with an average particle size of 1 μm to 10 μm, which is beneficial for obtaining a liquid crystal layer with the pore size range of this application. The silica microspheres can be easily removed by reacting with hydrofluoric acid, and the hydrofluoric acid does not react with the flexible substrate, conductive layer, transport layer, and perovskite layer, thus not affecting the performance of the solar cell. In the microsphere template of this application, the silica microspheres can be single-layer or multi-layer self-assembled.

[0071] In one optional embodiment, the perovskite layer preparation process includes:

[0072] A perovskite precursor solution containing perovskite material and a bi-anionic compound was spin-coated onto the surface of a liquid crystal layer, and then annealed to obtain the perovskite layer.

[0073] In one optional embodiment, the molar concentration of the dianion compound in the perovskite precursor solution is 0.003 mol / L to 0.01 mol / L. The concentration of the dianion compound in the perovskite precursor solution should not be too low or too high. When the concentration is too low, it cannot induce preferred orientation growth of perovskite grains, resulting in more lattice defects. When the concentration is too high, it leads to a violent synthesis reaction, causing poor uniformity in perovskite grain size, smaller grains, and more lattice / grain boundary defects. This application, by controlling the concentration of the dianion compound in the perovskite precursor solution within the above-mentioned range, can effectively promote uniform growth of perovskite grains, reduce interface defects, and improve the photoelectric conversion efficiency of solar cells.

[0074] This application does not impose any particular restrictions on the method of controlling the number of holes per unit area, the particle size of the holes, or the thickness of the liquid crystal layer, as long as the liquid crystal layer of this application can be obtained. For example, the number of holes per unit area in the liquid crystal layer can be controlled by controlling the number of microspheres in the microsphere template, the particle size of the holes in the liquid crystal layer can be controlled by controlling the particle size of the microspheres, and the thickness of the liquid crystal layer can be controlled by controlling the spin coating time.

[0075] The solar cell fabrication method provided in this application is based on a template method to form a liquid crystal layer with a mesh-like porous structure. This liquid crystal layer not only improves the adhesion between the perovskite layer and the liquid crystal layer, but also absorbs the stress generated by bending. Furthermore, this application can conveniently control the pore-related parameters of the liquid crystal layer by adjusting the number and particle size of microspheres in the template, thereby obtaining a liquid crystal layer with the structure of this application. It has the advantages of simple fabrication process and easy parameter adjustment. In addition, this application can also save the amount of liquid crystal elastomer used, thereby reducing manufacturing costs and making it suitable for large-scale manufacturing of flexible perovskite solar cells.

[0076] Thirdly, this application provides a photovoltaic module, which includes a solar cell as described in the first aspect, or the photovoltaic module includes a solar cell prepared by the preparation method described in the second aspect.

[0077] This application also provides a photovoltaic module for converting received light energy into electrical energy and transmitting it to an external load. The photovoltaic module includes: at least one cell string, which is composed of multiple solar cells connected together; an encapsulating film for covering the surface of the cell string; and a cover plate for covering the surface of the encapsulating film facing away from the cell string.

[0078] Example

[0079] The solar cells, their fabrication methods, and photovoltaic modules of this application will be further described below with reference to more specific embodiments.

[0080] Example 1

[0081] <Preparation of the first and second conductive layers>

[0082] After rinsing a PET substrate with dimensions of 20cm×20cm and a thickness of 100μm with deionized water, it was blown clean with compressed air and treated with ultraviolet ozone for 10 minutes. Then, an ITO layer with a thickness of 150nm was deposited on the front and back sides of the PET substrate by magnetron sputtering, serving as the first and second conductive layers. The sheet resistance of the deposited surface was 30 ohm / sq, and the light transmittance was 90%.

[0083] <Preparation of Electron Transport Layer>

[0084] The electron transport layer precursor solution was spin-coated onto the surface of the first conductive layer of a PET substrate at a spin speed of 3000 rpm for 40 s, followed by annealing at 100℃ for 30 min to form a 20 nm thick SnO2 electron transport layer, which serves as the first transport layer. The electron transport layer precursor solution was prepared by dissolving 1 g of SnO2 colloidal nanoparticles in 50 mL of deionized water and stirring for 10 h.

[0085] <Preparation of Liquid Crystal Layer>

[0086] Add 20 mL of ammonia (5 wt%) and 10 mL of deionized water to 100 mL of anhydrous ethanol and stir magnetically for 20 min to ensure homogeneity. Then add a mixture of 3 g of tetraethyl orthosilicate (TEOS) and 15 mL of ethanol. React in a water bath at room temperature for 12 h. Separate the silica microspheres using a high-speed centrifuge and wash them three times with anhydrous ethanol. Place the washed silica microspheres in an oven and dry them at 80 °C for 2 h to obtain silica microsphere powder with an average particle size of 7 μm. Then add the silica microsphere powder to a mixture of 35 mL of anhydrous ethanol and 15 mL of deionized water and disperse it ultrasonically for 30 min to prepare a silica microsphere suspension. Spin-coat the silica microsphere suspension onto the electron transport layer at a spin speed of 3000 rpm for 150 s. Allow the solvent to evaporate naturally to form a silica microsphere template.

[0087] A liquid crystal elastomer solution was prepared by mixing polyethylene glycol diacrylate monomer, crosslinking agent thiol, and photoinitiator Omnirad TPO in a molar ratio of 88:8:2 and then dissolving it in toluene. The solution had a concentration of 1 mg / mL. The solution was then spin-coated onto a silica microsphere template at 4000 rpm for 400 s. After spin-coating, the solution was annealed at 90 °C for 10 min to evaporate the solvent. The temperature was then gradually reduced from 90 °C to 50 °C and held for 5 min to allow the liquid crystal elastomer to enter the nematic phase. Finally, the solution was irradiated with 365 nm ultraviolet light for 10 min to crosslink under in-situ photothermal conditions, resulting in the initial structure of the liquid crystal layer.

[0088] The substrate with the above-described initial liquid crystal layer structure was immersed in a 0.1 mol / L hydrofluoric acid solution for 30 min, allowing the silica microspheres in the silica microsphere template to react and decompose. The substrate was then washed three times each with deionized water and anhydrous ethanol, and dried in an oven at 80°C for 60 min to obtain a liquid crystal layer with a network porous structure. The thickness of the liquid crystal layer, the number of pores per unit area, and the average diameter of the pores are shown in Table 1.

[0089] <Preparation of Perovskite Layer>

[0090] Formamidinium hydroiodide (FAI), cesium iodide (CsI), and lead iodide (PbI₂) were dissolved in a molar ratio of 0.9:0.1:1 in a mixed solvent consisting of 85 mL of N,N-dimethylformamide (DMF) and 15 mL of dimethyl sulfoxide (DMSO) to prepare a FA solution with a molar concentration of 1 mol / L. 0.9 Cs 0.1 A PbI3 perovskite precursor solution, also known as the first perovskite precursor solution, was spin-coated onto the liquid crystal layer. The spin-coating process consisted of two stages: the first stage involved a spin-coating speed of 1500 rpm and a spin-coating time of 10 s; the second stage involved a spin-coating speed of 4500 rpm and a spin-coating time of 30 s. Following this, an annealing process was performed at 125°C for 30 min, forming a perovskite layer with a thickness of 500 nm.

[0091] <Preparation of Hole Transport Layer>

[0092] A hole transport layer precursor solution was drop-added onto the surface of a perovskite layer using a pipette and then spin-coated at 3000 rpm for 30 seconds. After spin-coating, the layer was annealed at 150°C for 40 minutes to obtain a hole transport layer with a thickness of 25 nm. This hole transport layer serves as the second transport layer. The hole transport layer material in the hole transport layer precursor solution is Spiro-MeOTAD.

[0093] <Electrode Preparation>

[0094] A 100 nm thick layer of silver was deposited on the surface of the hole transport layer as an electrode.

[0095] Examples 2 to 5

[0096] Except for the section on "Preparation of Liquid Crystal Layer", which adjusts the relevant process parameters according to Table 1 to control the thickness of the liquid crystal layer, the number of holes per unit area, and the average diameter of the holes, the rest is the same as in Example 1.

[0097] Example 6

[0098] Except for the addition of the bianionic compound dodecyl 2-(dimethylamino)propionate hydrochloride in the <Preparation of Perovskite Layer>, the rest is the same as in Example 1.

[0099] <Preparation of Perovskite Layer>

[0100] Formamidinium hydroiodide (FAI), cesium iodide (CsI), and lead iodide (PbI₂) were dissolved in a molar ratio of 0.9:0.1:1 in a mixed solvent consisting of 85 mL of N,N-dimethylformamide (DMF) and 15 mL of dimethyl sulfoxide (DMSO) to prepare a FA solution with a molar concentration of 1 mol / L. 09 Cs 01 A PbI3 perovskite precursor solution, i.e., the first perovskite precursor solution, was prepared by adding an aqueous solution of the dianionic compound dodecyl 2-(dimethylamino)propionate hydrochloride (with a molar concentration of 0.05 mol / L in the aqueous solution) to the first perovskite precursor solution and stirring for 10 h to obtain a second perovskite precursor solution, wherein the molar concentration of dodecyl 2-(dimethylamino)propionate hydrochloride in the second perovskite precursor solution is 0.005 mol / L. The second perovskite precursor solution was then spin-coated onto a liquid crystal layer in two stages: the first stage was spin-coating at 1500 rpm for 10 s, and the second stage was spin-coating at 4500 rpm for 30 s. An annealing process was then performed at 125 °C for 30 min to form a perovskite layer with a thickness of 500 nm.

[0101] Examples 7 to 9

[0102] Except for adjusting the molar concentration of the bianionic compound in the perovskite precursor solution according to Table 2 in the <Preparation of Perovskite Layer> section, the rest is the same as in Example 6.

[0103] Example 10

[0104] Except for replacing dodecyl 2-(dimethylamino)propionate hydrochloride with acetamide hydrochloride in the <Preparation of Perovskite Layer>, the rest is the same as in Example 6.

[0105] Comparative Example 1

[0106] Except for the omission of the microsphere template preparation in the <Preparation of Liquid Crystal Layer> section, and the direct preparation of the liquid crystal layer on the electron transport layer, so that the prepared liquid crystal layer does not have a network porous structure, the rest is the same as in Example 1.

[0107] Table 1. Preparation parameters of Examples 1-5 and Comparative Example 1

[0108]

[0109] In Table 1, " / " indicates that no relevant preparation parameters exist.

[0110] Table 2 Preparation parameters for Examples 1, 6 to 10

[0111] Types of bianionic compounds Bianionic compound content (mol / L) Example 1 / / Example 6 Dodecyl 2-(dimethylamino)propionate hydrochloride 0.005 Example 7 Dodecyl 2-(dimethylamino)propionate hydrochloride 0.003 Example 8 Dodecyl 2-(dimethylamino)propionate hydrochloride 0.008 Example 9 Dodecyl 2-(dimethylamino)propionate hydrochloride 0.01 Example 10 Acetamide hydrochloride 0.005

[0112] In Table 2, " / " indicates that no relevant preparation parameters exist.

[0113] Performance testing:

[0114] Initial photoelectric conversion efficiency test:

[0115] The IV test of the perovskite solar cell was conducted under standard test conditions, namely an illumination intensity of 1000 W / m. 2 The initial photoelectric conversion efficiency of the solar cells was obtained by testing the current (I)-voltage (V) of the solar cells in each embodiment and comparative example under AM1.5G spectral conditions using a solar simulator (model: WAVELABS SINUS-300).

[0116] Electroconversion efficiency test after 5000 bends:

[0117] Using the standard four-point bending method, with a bending radius of 5mm, the flexible calcium titanium solar cell was bent 5000 times and then placed in a solar simulator (model: WAVELABS SINUS-300) to test the current (I)-voltage (V) of the solar cell, thus obtaining the photoelectric conversion efficiency of the solar cell after bending.

[0118] Table 3 Performance data for each embodiment and comparative example

[0119]

[0120]

[0121] As can be seen from Examples 1 to 5 and Comparative Example 1, the photoelectric conversion efficiency of the solar cell in Comparative Example 1 after 5000 bends is significantly lower than the initial photoelectric conversion efficiency. This may be because the liquid crystal layer of Comparative Example 1 does not have a mesh-like porous structure, so its elasticity is poor. During the bending process, it cannot absorb the stress generated by bending, causing the perovskite layer to crack and be damaged during bending, thus affecting the photoelectric conversion efficiency of the solar cell. Furthermore, the initial photoelectric conversion efficiency of Comparative Example 1 is also low, which may be due to the low adhesion between its perovskite layer and liquid crystal layer, affecting the carrier mobility at the interface, thereby affecting the photoelectric conversion efficiency of the solar cell. In contrast, the photoelectric conversion efficiency of the solar cell in Example 1 of this application only decreases slightly after 5000 bends compared to the initial photoelectric conversion efficiency, indicating that the bending resistance of the solar cell in this application is significantly improved.

[0122] As can be seen from Examples 1 and 6-9, by further introducing a dual-anion compound during the preparation of the perovskite layer, the initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 5000 bends of the solar cell are significantly improved. Therefore, this application, through the joint improvement of the liquid crystal layer and the perovskite layer, can synergistically improve the bending resistance of the solar cell.

[0123] As can be seen from Examples 6 and 10, the use of the dual anion compound of this application is beneficial to improving the bending resistance of solar cells.

[0124] Figure 6 This is a SEM image of the silica microsphere template in Example 2 of this application; Figure 7 This is a SEM image of the liquid crystal layer in Embodiment 1 of this application. Figure 6 As can be seen, the silica microspheres are relatively uniformly distributed in the template, and there are gaps between the silica microspheres. These gaps can be used to fill the liquid crystal elastomer, thereby forming a liquid crystal elastomer after the silica microsphere template is removed. Figure 7 The liquid crystal layer shown has a mesh-like porous structure.

[0125] The above provides a detailed description of a solar cell and its preparation method, as well as a photovoltaic module disclosed in this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the technical solutions and core inventive points of the embodiments of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A solar cell, characterized in that, It includes a flexible substrate and a first transport layer, a liquid crystal layer, a perovskite layer, and a second transport layer sequentially disposed on the flexible substrate, wherein, The liquid crystal layer contains holes that form a mesh-like porous structure.

2. The solar cell according to claim 1, characterized in that, The number of holes is 10,000 per 1 cm. 2 ~20,000 pieces / 1cm 2 .

3. The solar cell according to claim 1, characterized in that, The average diameter of the holes is 0.5 μm to 1 μm.

4. The solar cell according to claim 1, characterized in that, The thickness of the liquid crystal layer is 3μm to 10μm.

5. The solar cell according to claim 1, characterized in that, The perovskite layer also includes an intermediate phase formed by the coordination of acid radical ions with perovskite metal ions. The acid radical ions are generated by the decomposition of bi-anionic compounds during the formation of the perovskite layer.

6. The solar cell according to claim 5, characterized in that, The bianionic compound includes at least one of acetamide hydrochloride and dodecyl 2-(dimethylamino)propionate hydrochloride.

7. The solar cell according to any one of claims 1 to 6, characterized in that, The first transport layer is an electron transport layer, and the second transport layer is a hole transport layer; Alternatively, the first transport layer may be a hole transport layer, and the second transport layer may be an electron transport layer.

8. The solar cell according to any one of claims 1 to 6, characterized in that, The solar cell further includes a first conductive layer, which is located between the flexible substrate and the first transport layer.

9. The solar cell according to any one of claims 8, characterized in that, The solar cell further includes a second conductive layer and an electrode. The second conductive layer is located on the side of the flexible substrate opposite to the first conductive layer, and the electrode is located on the side of the second transport layer opposite to the perovskite layer.

10. The solar cell according to any one of claims 1 to 6, characterized in that, The liquid crystal elastomer material in the liquid crystal layer includes at least one of polyethylene glycol diacrylate and mercapto-acrylate.

11. The solar cell according to any one of claims 1 to 6, characterized in that, The flexible substrate is made of at least one of polyethylene terephthalate and polyethylene naphthalate.

12. A method for preparing a solar cell according to any one of claims 1 to 11, characterized in that, Includes the following steps: A flexible substrate having a first conductive layer and a second conductive layer is provided; A first transport layer, a liquid crystal layer, a perovskite layer, a second transport layer, and an electrode are sequentially fabricated on the surface of the first conductive layer of the flexible substrate. The fabrication process of the liquid crystal layer includes: A microsphere template is prepared on the surface of the first transport layer; A liquid crystal elastomer material is applied to the microsphere template, and the liquid crystal elastomer material is deposited on the surface of the first transport layer through the gaps between the microspheres; Remove the microsphere template and form the liquid crystal layer with a mesh-like porous structure on the surface of the first transport layer.

13. The preparation method according to claim 12, characterized in that, The microspheres in the microsphere template are silica microspheres, and the average particle size of the silica microspheres is 1 μm to 10 μm.

14. The preparation method according to claim 12, characterized in that, The preparation process of the perovskite layer includes: A perovskite precursor solution containing perovskite material and the aforementioned bis-anionic compound is spin-coated onto the surface of the liquid crystal layer, and after annealing, the perovskite layer is obtained.

15. The preparation method according to claim 14, characterized in that, In the perovskite precursor solution, the molar concentration of the bis-anionic compound is 0.003 mol / L to 0.01 mol / L.

16. A photovoltaic module, characterized in that, The photovoltaic module comprises the solar cell according to any one of claims 1 to 11, or the photovoltaic module comprises the solar cell prepared by the preparation method according to any one of claims 12 to 15.

Images