Double-sided flexible solar cell and preparation method thereof

Abstract

The invention discloses a double-sided flexible solar cell and a preparation method thereof. The solar cell sequentially comprises a flexible semitransparent photovoltaic cell, a curved surface reflector and a flexible photovoltaic cell from top to bottom, wherein the flexible semitransparent photovoltaic cell sequentially comprises a packaging layer, a second transparent electrode, an electron transport layer, a light absorption layer, a hole transport layer and a first transparent electrode from top to bottom; the curved-surface reflecting mirror comprises a curved-surface substrate, a high-reflectivity metal layer and a weather-resistant protective layer from top to bottom in sequence. The flexible photovoltaic cell is one of a perovskite solar cell, an organic solar cell, a CIGS solar cell, a dye-sensitized solar cell, a monocrystalline silicon solar cell, an amorphous silicon solar cell, a cadmium telluride thin film solar cell and a quantum dot solar cell. The double-sided flexible solar cell provided by the invention can solve a series of problems that a traditional flexible solar cell is low in solar spectrum utilization rate, insufficient in photovoltaic and photo-thermal system collaboration, poor in complex curved surface adaptability and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of flexible solar cells, and in particular to a double-sided flexible solar cell and a preparation method thereof. Background Art

[0002] With the continuous growth of global energy demand and the accelerated advancement of carbon neutrality goals, the research and development and application of clean energy technologies have become the focus of global attention. Among many renewable energy sources, solar energy has become the core area of ​​energy development due to its abundance and environmental friendliness. Photovoltaic power generation and photothermal utilization, as the two main ways of utilizing solar energy, each has its own advantages and limitations in practical applications. Photovoltaic power generation directly converts sunlight into electrical energy, with the characteristics of high efficiency and flexible application, but the scope of utilization of the solar spectrum is limited, especially the energy of infrared light cannot be fully converted. In addition, traditional photovoltaic cells have low utilization efficiency of scattered light and ground reflected light, and their performance is significantly limited in high latitudes, cloudy areas or complex environments. Photothermal systems are mainly used to collect infrared band energy of sunlight and generate electricity or store energy through thermal energy conversion, but their system design is complex and their ability to utilize ultraviolet and visible light is weak, resulting in insufficient overall utilization efficiency of the solar spectrum.

[0003] Traditional photovoltaic and solar thermal systems are usually deployed independently. Although they can complement each other in function, they occupy a lot of land resources, have high construction costs, and are difficult to integrate, which restricts their economic benefits in large-scale applications. To solve these problems, solar energy technology has gradually developed in the direction of integration and flexibility in recent years. On the one hand, by optimizing spectral selectivity technology, different bands of sunlight can be accurately separated and utilized to achieve the coordinated operation of photovoltaics and solar thermal. On the other hand, the development of flexible photovoltaic materials provides new possibilities for the integrated application of photovoltaics and solar thermal systems with complex curved structures. This technology is particularly important in scenarios such as trough and dish solar thermal power stations that need to adapt to complex reflective surfaces.

[0004] Although photovoltaic and solar thermal technologies have made great progress, the following problems still exist in terms of spectral utilization efficiency and system integration: 1. Insufficient coordination between existing photovoltaic and solar thermal systems. Currently, photovoltaic power generation and solar thermal collection systems are mostly designed independently, making it difficult to achieve comprehensive and efficient utilization of the solar energy spectrum, resulting in low energy utilization efficiency; 2. Low utilization of indirect light. Traditional photovoltaic systems mainly rely on direct light for power generation, and have limited utilization of scattered light, ground reflected light and ambient light, especially under non-ideal climatic conditions (such as cloudy environments). Efficiency is reduced; 3. Single functional limitation of solar thermal reflectors. Most existing solar thermal reflectors are only used for reflection. and heat collection, which have deficiencies in spectral selectivity regulation and thermal energy conduction efficiency; 4. Photovoltaic cells have poor adaptability to complex curved structures. The rigid structure of traditional photovoltaic cells makes it difficult for them to adapt to the curved shape of trough or dish reflectors, resulting in high installation complexity and incomplete coverage, affecting system performance; 5. The heat dissipation performance of photovoltaic and solar thermal systems is insufficient. The existing photovoltaic-solar thermal hybrid system is prone to heat accumulation under high-intensity radiation, resulting in reduced efficiency and even equipment damage; 6. Limitations on the utilization efficiency of trough and dish solar thermal power station systems. In the design of traditional trough and dish solar thermal power stations, the energy utilization method is single, and the power generation efficiency and thermal energy collection efficiency are not optimal.

[0005] Based on this background, the present invention is proposed. Summary of the invention

[0006] The purpose of the present invention is to provide a double-sided flexible solar cell and a preparation method thereof, which can solve a series of problems of traditional flexible solar cells, such as low solar spectrum utilization, insufficient synergy between photovoltaic and photothermal systems, and poor adaptability to complex curved surfaces.

[0007] The present invention provides a double-sided flexible solar cell, which comprises, from top to bottom, a flexible semi-transparent photovoltaic cell, a curved reflector, and a flexible photovoltaic cell, wherein the flexible semi-transparent photovoltaic cell comprises, from top to bottom, an encapsulation layer, a second transparent electrode, an electron transport layer, a light absorption layer, a hole transport layer, and a first transparent electrode; wherein the positions of the electron transport layer and the hole transport layer can be interchanged;

[0008] The curved reflector includes, from top to bottom, a curved substrate, a high reflectivity metal layer, and a weather-resistant protective layer;

[0009] The flexible photovoltaic cell is one of a perovskite solar cell, an organic solar cell, a copper indium gallium selenide solar cell, a dye-sensitized solar cell, a single crystal silicon solar cell, an amorphous silicon solar cell, a cadmium telluride thin film solar cell, and a quantum dot solar cell.

[0010] Furthermore, the material of the high reflectivity metal layer of the curved reflector is silver or aluminum, and the material of the weather-resistant protective layer is one of aluminum oxide, silicon dioxide, titanium dioxide, and polymer. Furthermore, the thickness of the high reflectivity metal layer is 20nm-500nm, and further 50-500nm; the thickness of the weather-resistant protective layer is 10nm-500nm, and further 30-300nm; the curved substrate is made of high-transmittance flexible glass with a thickness of 0.5-5cm.

[0011] Furthermore, the flexible photovoltaic cell is a perovskite solar cell, which includes, from top to bottom, a first transparent electrode, a hole transport layer, a light absorption layer, an electron transport layer, a second transparent electrode, and an encapsulation layer; wherein the positions of the electron transport layer and the hole transport layer of the flexible photovoltaic cell can be interchanged; the material band gap of the light absorption layer of the flexible semi-transparent photovoltaic cell is 1.65eV-2.30eV, and the material band gap of the light absorption layer of the flexible photovoltaic cell is 1.40eV-2.30eV. Furthermore, the material band gap of the light absorption layer of the flexible semi-transparent photovoltaic cell is 1.70eV, and the material band gap of the light absorption layer of the flexible semi-transparent photovoltaic cell is 1.50eV.

[0012] The present invention provides a method for preparing a double-sided flexible solar cell, comprising the following steps:

[0013] S1. Preparation of curved mirror

[0014] A high-reflectivity metal layer and a weather-resistant protective layer are sequentially prepared on the lower surface of the curved substrate to obtain the curved reflector;

[0015] S2. Prepare flexible semi-transparent photovoltaic cells and flexible photovoltaic cells, and paste the flexible semi-transparent photovoltaic cells and flexible photovoltaic cells on the upper and lower surfaces of the curved reflector; or directly prepare flexible semi-transparent photovoltaic cells and flexible photovoltaic cells on the upper and lower surfaces of the curved reflector; or directly prepare flexible semi-transparent photovoltaic cells or flexible photovoltaic cells on the upper or lower surface of the curved reflector, and then paste the prepared flexible photovoltaic cells or flexible semi-transparent photovoltaic cells on the curved reflector to obtain the double-sided flexible solar cell.

[0016] Furthermore, the preparation process of the flexible semi-transparent photovoltaic cell is as follows: a first transparent electrode, a hole transport layer, a light absorption layer, an electron transport layer, and a second transparent electrode are sequentially prepared on a transparent flexible substrate or the upper surface of a curved reflector, and finally encapsulated with a packaging material; the flexible substrate used in the preparation process of the flexible photovoltaic cell is transparent or opaque, and the rest of the preparation process is consistent with the flexible semi-transparent photovoltaic cell.

[0017] Furthermore, when flexible photovoltaic cells are directly prepared on the lower surface of the curved reflector, a thin glass sheet needs to be fixed on the lower surface of the curved reflector. The thickness of the thin glass sheet is 1mm-2cm, and the first transparent electrode, hole transport layer, light absorption layer, electron transport layer, second transparent electrode, and encapsulation layer are prepared on the thin glass sheet in sequence.

[0018] Furthermore, the preparation process of the flexible semi-transparent photovoltaic cell is as follows:

[0019] A. using one of polyethylene terephthalate, polyimide or polyethylene naphthalate as a raw material to prepare a transparent flexible substrate; when a flexible semi-transparent photovoltaic cell is directly prepared on the upper surface of a curved reflector, step A can be directly omitted;

[0020] B. depositing one of indium tin oxide, zinc aluminum oxide or fluorine-doped tin oxide on the flexible substrate to form a first transparent electrode;

[0021] C. depositing poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate or poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] on the first transparent electrode, and then annealing at 80-120° C. to form a hole transport layer;

[0022] D. depositing a perovskite film on the hole transport layer and annealing at 100-150°C to form a light absorption layer;

[0023] E. [6,6]-phenyl-C 61 - Methyl butyrate or nanocrystalline TiO2 solution is deposited on the light absorbing layer and annealed at 70-120°C to form an electron transport layer;

[0024] F. depositing at least one of indium tin oxide, zinc aluminum oxide, silver nanowires or graphene on the electron transport layer to form a second transparent electrode to obtain a battery main structure;

[0025] G. Prepare a packaging layer, and use packaging materials to package the outside of the battery main structure in a vacuum or nitrogen atmosphere to obtain a flexible semi-transparent photovoltaic cell.

[0026] Furthermore, when the prepared flexible semi-transparent photovoltaic cell or flexible photovoltaic cell is pasted on the surface of the curved reflector, the specific process is as follows:

[0027] First, rinse the surface of the curved reflector with industrial ethanol, isopropanol, and deionized water in turn, and finally blow dry or dry with nitrogen;

[0028] Then, the adhesive is evenly coated on the surface of the curved reflector to form an adhesive layer; the thickness of the adhesive layer is 100-200 μm, and the adhesive is a silicone adhesive or a UV curing adhesive;

[0029] Finally, place the flexible semi-transparent photovoltaic cell or the flexible photovoltaic cell on the adhesive layer and press it tightly.

[0030] Furthermore, the preparation process of the flexible photovoltaic cell also includes the following steps: after forming the light absorption layer, performing microstructure production on the surface of the light absorption layer, the microstructure production is performed by one or more of laser direct writing, nanoimprinting, and wet etching; and depositing a metal reflective layer on the back of the prepared flexible photovoltaic cell, and then coating a titanium dioxide protective layer on the metal reflective layer.

[0031] Furthermore, the preparation process of the curved reflector in step S1 is as follows:

[0032] S11. Preparing a high reflectivity metal layer and a weather-resistant protective layer on the lower surface of the curved substrate in sequence;

[0033] S12. Depositing a spectrally selective coating on the upper surface of the curved substrate, first depositing silicon dioxide or silicon nitride on the upper surface of the curved substrate to form an infrared transparent film; then alternately depositing high refractive index material layers and low refractive index material layers on the infrared transparent film to form an interference film, and finally forming a spectrally selective coating to obtain a curved reflector. The material of the high refractive index material layer is titanium dioxide, and the material of the low refractive index material layer is silicon dioxide or magnesium fluoride.

[0034] Furthermore, the preparation process of the curved reflector in step S1 is as follows:

[0035] S11. Prefabricate a heat-conducting channel or an embedded structure on a curved substrate, embed a heat-conducting material into the heat-conducting channel or the embedded structure, apply a thermal paste on the contact surface between the curved substrate and the heat-conducting material, and apply vacuum pressing;

[0036] S12. Preparing a high reflectivity metal layer and a weather-resistant protective layer on the lower surface of the curved substrate in sequence;

[0037] S13. Finally, a spectrally selective coating is prepared on the upper surface of the curved substrate to obtain the curved reflector.

[0038] Furthermore, the thermally conductive material is one of copper, graphene sheets or ceramic materials; the thermally conductive paste is silicone grease or carbon-based thermally conductive glue; the spectrally selective coating is a plurality of layers of silicon dioxide and titanium dioxide layers alternately arranged; the preparation process of the curved reflector also includes the following steps: using laser direct writing, nanoimprinting or etching to set a micro-nano structure array on the upper surface of the spectrally selective coating.

[0039] The present invention also provides an application of the above-mentioned double-sided flexible solar cell or the double-sided flexible solar cell prepared by the above-mentioned method in a trough-type solar thermal power generation system or a dish-type solar thermal power generation system.

[0040] In summary, compared with the prior art, the present invention has the following advantages:

[0041] The technical solution of the present invention integrates flexible semi-transparent photovoltaic cells, curved reflectors and flexible photovoltaic cells into one through a unique three-layer structural design, achieving efficient use of the solar spectrum in different bands. The upper flexible semi-transparent photovoltaic cells mainly absorb ultraviolet and visible light, and allow infrared light to pass through the curved reflectors in the middle layer for heat collection; the lower flexible photovoltaic cells use ground reflected light and ambient scattered light to generate electricity.

[0042] The double-sided flexible solar cell prepared by the present invention significantly improves the synergistic efficiency of photovoltaic and photothermal systems, increases the thermal energy conversion efficiency, significantly enhances the ability to capture indirect light, and effectively makes up for the shortcoming of existing photovoltaic technology in low utilization of scattered light and ground reflected light; the upper and lower layers of flexible batteries can adapt to the complex curved mirror structure of trough-type and dish-type photothermal power stations, further enhancing the adaptability of the flexible batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0044] Figure 1 It is a schematic diagram of the structure of a double-sided flexible solar cell in the present invention;

[0045] Figure 2 is a cross-sectional view of the flexible semi-transparent photovoltaic cell in Example 1 of the present invention;

[0046] Figure 3 is a cross-sectional view of the flexible photovoltaic cell in Example 1 of the present invention;

[0047] Figure 4 is a cross-sectional view of the curved reflector in Example 1 of the present invention;

[0048] Figure 5 is a cross-sectional view of a double-sided flexible solar cell in Example 2 of the present invention;

[0049] Figure 6 is a cross-sectional view of the curved reflector in Example 3 of the present invention;

[0050] Figure 7 A cross-sectional view of a flexible photovoltaic cell in Example 4 of the present invention

[0051] Figure 8 is a cross-sectional view of the curved reflector in Example 5 of the present invention;

[0052] Fig. 9 This is a schematic diagram of the application of the double-sided flexible solar cell in the present invention in a solar thermal power station.

[0053] Description: Among them Figure 2-8 The plan view is only for clearly showing the positional relationship between the curved reflector, the flexible semi-transparent photovoltaic cell or the layers of the flexible photovoltaic cell, and does not mean that the specific physical shape is a plane. The actual physical shape is the arc shape of conventional flexible batteries in the field.

[0054] Explanation of the reference numerals: 1-flexible semi-transparent photovoltaic cell; 101-flexible substrate; 102-first transparent electrode; 103-hole transport layer; 104-light absorption layer; 105-electron transport layer; 106-second transparent electrode; 107-encapsulation layer; 2-curved reflector; 201-curved substrate; 202-high reflectivity metal layer; 203-weather-resistant protective layer; 204-infrared transparent film; 205-interference film; 206-heat conduction channel; 207-thermal conductive material; 208-spectrally selective coating; 209-thin glass sheet; 3-flexible photovoltaic cell; 301-metal reflective layer; 302-titanium dioxide protective layer; 4-bracket; 5-collector. DETAILED DESCRIPTION

[0055] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0056] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0057] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined. In addition, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0058] Example 1

[0059] A double-sided flexible solar cell, such as Figure 1 As shown, from top to bottom, it includes a flexible semi-transparent photovoltaic cell 1, a curved reflector 2, and a flexible photovoltaic cell 3.

[0060] The flexible semi-transparent photovoltaic cell 1 includes, from top to bottom, an encapsulation layer 107 , a second transparent electrode 106 , an electron transport layer 105 , a light absorption layer 104 , a hole transport layer 103 , and a first transparent electrode 102 .

[0061] The curved reflector 2 includes, from top to bottom, a curved substrate 201 , a high reflectivity metal layer 202 , and a weather-resistant protective layer 203 .

[0062] The flexible photovoltaic cell 3 is a perovskite solar cell, which includes, from top to bottom, a first transparent electrode 102 , a hole transport layer 103 , a light absorption layer 104 , an electron transport layer 105 , a second transparent electrode 106 , and an encapsulation layer 107 .

[0063] In this embodiment, the flexible semi-transparent photovoltaic cell 1 and the flexible photovoltaic cell 3 are both provided with a flexible substrate 101. The positions of the electron transport layer 105 and the hole transport layer 103 of the flexible semi-transparent photovoltaic cell 1 and the flexible photovoltaic cell 3 can be interchanged.

[0064] The method for preparing the above-mentioned double-sided flexible solar cell has the following specific process:

[0065] S1. Preparation of curved mirror 2

[0066] The curved reflector 2 uses a combination of a high reflectivity metal layer 202 and a weather-resistant protective layer 203 to improve the reflection effect of unabsorbed light. The curved substrate 201 can be made of high-transmittance flexible glass with a thickness of 0.5-5 cm. The curved substrate 201 is cleaned and polished to remove oxides and impurities to ensure the adhesion of the coating. A silver or aluminum film is uniformly deposited on the lower surface of the finely polished curved substrate 201 using a vacuum evaporation or magnetron sputtering process to obtain a high reflectivity metal layer 202. Subsequently, a weather-resistant protective layer 203 (the material of the weather-resistant protective layer 203 is SiO2 or TiO2) is prepared on the lower surface of the high reflectivity metal layer 202 using chemical vapor deposition (CVD) or spin coating to enhance its corrosion resistance and durability. The thickness of the high reflectivity metal layer 202 may be 50-500 nm, more preferably 100-200 nm; the thickness of the weather-resistant protective layer 203 may be 30-300 nm, more preferably 80-100 nm. The structure of the prepared curved reflector is as follows: Figure 4 shown.

[0067] S2. Assembling bifacial flexible solar cells

[0068] S21. Preparation of flexible semi-transparent photovoltaic cells 1

[0069] A. Preparation of Flexible Substrate 101

[0070] Flexible substrate plays a vital role in the photovoltaic field. It is mainly used to carry the photovoltaic layer. In order to better play its role, the substrate needs to have excellent high light transmittance and excellent mechanical flexibility. In the preparation process, solution casting, hot pressing, electrospinning, melt extrusion and other processes are used. Melt extrusion method: First, one of the materials of polyethylene terephthalate (PET), polyimide (PI) or polyethylene naphthalate (PEN) is heated to a molten state. In this state, the material has good fluidity, which is convenient for subsequent processing operations. Then, the molten material is extruded into a film. In order to further enhance the mechanical properties of the film, it needs to be stretched. The stretching process makes the molecular structure of the film more orderly, thereby improving its strength and toughness. Subsequently, in order to enhance the adhesion between the film surface and the subsequent coating, the film surface is treated by plasma cleaning. Plasma cleaning can remove impurities and contaminants on the surface of the film, while activating the surface molecules, increasing the surface energy, and thus enhancing the bonding with the subsequent coating.

[0071] B. Preparation of the first transparent electrode 102

[0072] The first transparent electrode 102 is deposited on the flexible substrate 101 to collect carriers in the photovoltaic cell while ensuring high light transmittance. A material selected from indium tin oxide, zinc aluminum oxide or fluorine-doped tin oxide is deposited on the flexible substrate 101 by magnetron sputtering. In order to ensure the uniformity of the first transparent electrode 102, a multi-target rotation sputtering process can be used, and finally the conductivity and light transmittance of the film are enhanced by heat treatment.

[0073] C. Preparation of hole transport layer 103

[0074] The hole transport layer 103 is deposited on the first transparent electrode 102 to effectively transport holes generated by the light absorption layer 104 and prevent reverse electron transport. The hole transport material (one of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate and poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine]) is deposited on the first transparent electrode 102 by solution spin coating, and then annealed at 80-120°C to remove the solvent and enhance the stability of the layer.

[0075] D. Preparation of light absorbing layer 104

[0076] The light absorption layer 104 is deposited on the hole transport layer 103 and is the core component of the photovoltaic cell, responsible for converting sunlight into electron-hole pairs. The material band gap of the light absorption layer 104 is 1.65eV-2.30eV, and the optimal is 1.70eV. The perovskite and organic quantum dot precursor solutions are coated on the hole transport layer 103 by solution spin coating, slit coating and other methods, and a uniform perovskite film is formed by wet chemical deposition; then annealed at 100-150°C to form a well-crystallized perovskite light absorption layer 104.

[0077] E. Preparation of electron transport layer 105

[0078] The electron transport layer 105 is deposited on the light absorbing layer 104 to conduct the electrons generated in the light absorbing layer 104 to the electrode. [6,6]-phenyl-C 61 -methyl butyrate) or nanocrystalline TiO2 solution is deposited on the light absorbing layer 104 and low temperature annealing is performed at 70-120° C. to enhance the crystallinity and electron transport properties of the layer.

[0079] F. Preparation of the second transparent electrode 106

[0080] The second transparent electrode 106 is deposited on the electron transport layer 105 to collect electrons and conduct current while maintaining light transmittance. One of indium tin oxide, zinc aluminum oxide, silver nanowires or graphene is uniformly deposited on the electron transport layer 105 by magnetron sputtering or thermal evaporation. For graphene or silver nanowires, spin coating or spray coating is usually used, and the flexible substrate 101 is used for transfer process.

[0081] G. Preparation of encapsulation layer 107

[0082] The encapsulation layer 107 is used to protect the battery from moisture and oxygen in the environment and extend the battery life. The encapsulation material (the encapsulation material is one of ethylene-vinyl acetate, polyvinylidene fluoride, butyl rubber, and silicone) is heat-pressed in a vacuum or nitrogen atmosphere by a lamination process to tightly wrap the entire battery structure to prevent environmental factors from damaging the battery, thereby obtaining a flexible semi-transparent photovoltaic cell 1, the structure of which is as follows: Figure 2 shown.

[0083] S22. Preparation of flexible photovoltaic cells 3

[0084] The structure of the flexible photovoltaic cell 3 is as follows Figure 3 As shown, its preparation process is the same as that of the flexible semi-transparent photovoltaic cell 1, except that the band gap of the perovskite light absorption layer 104 is different. The band gap of the flexible photovoltaic cell 3 is 1.40eV-2.30eV, and the optimal is 1.5eV. Another difference is that the flexible substrate 101 of the flexible photovoltaic cell 3 can be transparent or opaque, and there is no requirement for transparency.

[0085] S23. Assemble and paste the prepared flexible semi-transparent photovoltaic cell 1 and flexible photovoltaic cell 3 onto the curved mirror 2

[0086] S231. Surface cleaning: First, rinse the upper and lower surfaces of the curved reflector 2 with industrial ethanol, isopropanol, and deionized water in sequence, and finally blow dry or bake with nitrogen.

[0087] S232. Adhesive layer coating: Evenly coat the adhesive (using high-performance silicone adhesive or UV curing adhesive) on the upper and lower surfaces of the curved reflector 2 to ensure that the battery can be firmly attached to the mirror surface. The coating thickness of the adhesive should be uniform, generally controlled between 100-200μm, to ensure sufficient adhesion and flatness of the battery. Wait for a few minutes after coating to allow the adhesive layer to dry slightly to a semi-cured state for subsequent pasting operations.

[0088] S234. Cell positioning: Place the prepared flexible semi-transparent photovoltaic cell 1 on the adhesive layer on the upper surface (inside of the bending direction) of the curved reflector 2, and place the flexible photovoltaic cell 3 on the adhesive layer on the lower surface (outside of the bending direction) of the curved reflector 2, and gradually bond them from one side to ensure that there are no bubbles between the cell and the surface of the curved reflector 2. During the bonding process, a roller or other flexible tool can be used for light pressure to ensure that the photovoltaic cell fits tightly on the curved surface and remains uniform.

[0089] S235. Compressing and curing: Use a vacuum pressing system and a roller press to compress the entire system, maintain uniform pressure, and ensure that the bonding between the cell and the curved reflector 2 is complete and firm. The pressing time is generally 30 minutes to 1 hour to ensure full adhesion; if a UV curing adhesive is used, the cell surface can be irradiated with a UV light source to quickly cure the adhesive; finally, a double-sided flexible solar cell is obtained, and its structure is as follows Figure 1 shown.

[0090] The preparation processes of the flexible semi-transparent photovoltaic cell 1, the curved reflector 2 and the flexible photovoltaic cell 3 in the present invention are all conventional techniques in the art.

[0091] Example 2

[0092] A double-sided flexible solar cell, such as Figure 5 As shown, from top to bottom, it includes: a flexible semi-transparent photovoltaic cell 1, a curved reflector 2, and a flexible photovoltaic cell 3.

[0093] The flexible semi-transparent photovoltaic cell 1 includes, from top to bottom, an encapsulation layer 107 , a second transparent electrode 106 , an electron transport layer 105 , a light absorption layer 104 , a hole transport layer 103 , and a first transparent electrode 102 .

[0094] The curved reflector 2 includes, from top to bottom, a curved substrate 201 , a high reflectivity metal layer 202 , and a weather-resistant protective layer 203 .

[0095] The flexible photovoltaic cell 3 includes, from top to bottom, a first transparent electrode 102 , a hole transport layer 103 , a light absorption layer 104 , an electron transport layer 105 , a second transparent electrode 106 , and an encapsulation layer 107 .

[0096] The method for preparing the above-mentioned double-sided flexible solar cell has the following specific process:

[0097] S1. Preparation of curved mirror 2

[0098] The curved substrate 201 is made of high-transmittance flexible glass with a thickness of 0.5-5 cm. Silver or aluminum is uniformly deposited on the finely polished curved substrate 201 by vacuum evaporation or magnetron sputtering to form a high-reflectivity metal layer 202. Subsequently, a weather-resistant protective layer 203 is prepared on the lower surface of the high-reflectivity metal layer 202 by chemical vapor deposition (CVD) or spin coating (the material of the weather-resistant protective layer 203 is SiO2 or TiO2). The thickness of the high-reflectivity metal layer 202 can be 50-500 nm, more preferably 100-200 nm. The thickness of the weather-resistant protective layer 203 can be 30-300 nm, more preferably 80-100 nm.

[0099] S2. On the upper surface of the curved reflector 2, a first transparent electrode 102, a hole transport layer 103, a light absorption layer 104, an electron transport layer 105, a second transparent electrode 106, and an encapsulation layer 107 are sequentially prepared to form a flexible semi-transparent photovoltaic cell 1, and a flexible photovoltaic cell 3 is prepared on the lower surface of the curved reflector 2; wherein the preparation method of the first transparent electrode 102, the hole transport layer 103, the light absorption layer 104, the electron transport layer 105, the second transparent electrode 106, and the encapsulation layer 107 is consistent with the preparation method in Example 1, and will not be repeated. The same layer of battery material can be prepared on the upper and lower surfaces of the curved reflector 2 at the same time, or one side can be prepared first and then the other side.

[0100] You can also choose to directly prepare the flexible semi-transparent photovoltaic cell 1 or the flexible photovoltaic cell 3 on the upper surface or the lower surface of the curved reflector 2, and then stick the prepared flexible photovoltaic cell 3 or the flexible semi-transparent photovoltaic cell 1 on the curved reflector 2 to obtain a double-sided flexible solar cell.

[0101] It should be noted that when the flexible photovoltaic cell 3 is directly prepared on the lower surface of the curved reflector 2, a thin glass sheet 209 needs to be fixed on the lower surface of the curved reflector 2. The thickness of the thin glass sheet 209 is 1 mm-2 cm. The first transparent electrode 102, the hole transport layer 103, the light absorption layer 104, the electron transport layer 105, the second transparent electrode 106, and the encapsulation layer 107 are prepared in sequence on the lower surface of the thin glass sheet 209.

[0102] Example 3

[0103] The technical solution in this embodiment is basically consistent with that in Embodiment 1 or Embodiment 2, except that: the curved reflector 2 is improved, and a spectrally selective coating is provided between the upper surface of the curved reflector 2 and the flexible semi-transparent photovoltaic cell 1.

[0104] The improved technical principle is as follows:

[0105] By designing a spectrally selective coating on the surface of the curved reflector 2, the transmission and reflection behaviors of light in different bands can be regulated: infrared light passes through the spectrally selective coating and is transmitted to the thermal energy collection system for thermal energy conversion; ultraviolet light and visible light that are not absorbed by the upper photovoltaic cells are efficiently reflected by the coating and reused.

[0106] Material and coating design

[0107] Spectrally selective coating materials, the basic coating materials use oxide or nitride materials, such as titanium dioxide, silicon oxide and silicon nitride; the curved substrate uses metals such as silver (Ag) or aluminum (Al) to enhance the reflective properties; multi-layer structure coating design: based on the principle of interference film, high refractive index (such as TiO2) and low refractive index (such as SiO2) materials are alternately deposited to form a multi-layer structure to optimize the spectral selectivity performance.

[0108] Functional layer design

[0109] Infrared transmission functional layer, adjust the refractive index and thickness of the coating to enable high transmission (transmittance greater than 90%) in the infrared light band (700-2500nm). Ultraviolet and visible light reflection functional layer, enhance the reflection characteristics through interference, and achieve high reflectivity (reflectivity greater than 95%) for light in the wavelength range of 300-700nm. Scattering enhancement coating, introduce micro-nano structure (such as nanoparticle coating or etching pattern) on the surface of the curved reflector to enhance the light scattering performance.

[0110] The specific preparation process is as follows:

[0111] S11. The curved substrate 201 is made of highly transparent flexible glass, with a thickness of 0.5-5 cm, and a metal layer of aluminum or silver is used to enhance the reflective properties; the curved substrate 201 is cleaned and polished to remove oxides and impurities to ensure the adhesion of the coating; a silver or aluminum film is uniformly deposited on the lower surface of the finely polished curved substrate 201 by vacuum evaporation or magnetron sputtering to obtain a high reflectivity metal layer 202. Subsequently, a weather-resistant protective layer 203 is prepared on the lower surface of the high reflectivity metal layer 202 by chemical vapor deposition (CVD) or spin coating. The thickness of the high reflectivity metal layer 202 can be 50-500 nm, more preferably 100-200 nm; the thickness of the weather-resistant protective layer 203 can be 30-300 nm, more preferably 80-100 nm.

[0112] S12. Preparation of Spectrally Selective Coating

[0113] A spectrally selective transflective layer is prepared on the upper surface of the curved substrate 201, wherein the spectrally selective transflective layer includes an infrared transmissive film 204 and an interference film 205;

[0114] An infrared transparent film 204 (the material is silicon dioxide or silicon nitride) is deposited on the upper surface of the curved substrate 201 by sol-gel method, atomic layer deposition (ALD) method, sputtering method, chemical vapor deposition or physical vapor deposition. The infrared transparent film 204 has good infrared light transmittance and mechanical durability, and the film thickness is 100-300nm. In order to enhance the reflection of ultraviolet light and visible light, a high refractive index material layer (made of TiO2) and a low refractive index material layer (made of SiO2 or magnesium fluoride) are sequentially deposited on the infrared transparent film 204 to form an interference film 205. The thickness of the high refractive index material layer is 30-100nm, and the thickness of the low refractive index material layer is 50-200nm. The design of alternating high and low refractive index is adopted to form an interference film 205 that can reflect ultraviolet light and visible light. The structure of the interference film 205 is 5-7 layers alternating, and the total thickness is controlled at 300-500nm. The interference film 205 is reflective in the ultraviolet and visible light bands, and the reflectivity can reach more than 90%.

[0115] S13. Using laser direct writing, nanoimprinting or etching technology, a micro-nano structure array (such as a conical, cylindrical or random pattern structure, structure size: micrometer or nanometer, optimized scattering angle and intensity) is formed on the surface of the spectrally selective coating, and finally a curved reflector 2 (the structure of the curved reflector 2 is as shown in FIG. Figure 6 shown).

[0116] Example 4

[0117] The technical solution in this embodiment is consistent with that in Embodiment 1, Embodiment 2 or Embodiment 3, except that: some improvements are made to the flexible photovoltaic cell 3 to improve its efficiency in capturing and utilizing light energy from multiple aspects. The technical principle of the improvement is as follows:

[0118] Back-facing design: Optimize the light absorption direction of the lower photovoltaic cells so that they can efficiently absorb scattered light from the environment and reflected light from the ground.

[0119] Microstructure surface treatment: Add micro-nano structures to the surface of the lower photovoltaic cell to enhance the ability to capture scattered light.

[0120] Reflective coating design: Add a high reflectivity coating on the back of the lower cell (i.e., the upper surface of the flexible photovoltaic cell 3 close to the curved reflector 2) to reflect the unabsorbed light back into the cell, thereby improving the recycling rate of light.

[0121] Material and structural design

[0122] Back-to-back design: The battery material uses high-efficiency flexible perovskite photovoltaic material with a wide spectral response range and good light absorption ability; transparent substrate: polyimide (PI) or polyethylene terephthalate (PET) with high light transmittance is selected as the substrate material to allow scattered light and reflected light to enter the lower battery.

[0123] Microstructured surface treatment: introducing nanopillar arrays, microcone structures, or randomly distributed pit patterns;

[0124] Material selection: Apply an anti-reflective coating (such as silicon dioxide SiO2) on the surface or directly etch the surface of the battery to enhance the light trapping effect.

[0125] Back reflective coating: Metal materials such as silver or aluminum are used as the reflective layer, which has high reflectivity and conductivity. A dielectric layer such as titanium dioxide or magnesium oxide is covered on the metal reflective layer as a reflection enhancement coating to improve the reflection efficiency and protect the stability of the coating.

[0126] Specific preparation process

[0127] The preparation of the flexible photovoltaic cell 3 in this embodiment is basically the same as that in Embodiment 1, except that:

[0128] (1) After the light absorbing layer 104 is prepared, a microstructure is fabricated on the lower surface of the light absorbing layer 104. The microstructure is fabricated in one or more of the following ways:

[0129] Laser direct writing, using laser to form nano patterns on the surface of the light absorbing layer 104 to improve the light trapping capability;

[0130] Nanoimprinting, which uses mold imprinting to quickly create micro-nano structures and improve the ability to capture scattered light;

[0131] Wet etching, by applying a mask and using an etching solution to prepare randomly distributed micro-holes or pits.

[0132] (2) Deposition of back reflective coating

[0133] The metal reflective layer 301 (Ag or Al) is deposited by magnetron sputtering with a thickness of about 50-100 nm. A titanium dioxide protective layer 302 is coated on the metal reflective layer 301 to enhance the reflective performance and extend the coating life. The structure of the prepared flexible photovoltaic cell 3 is as follows: Figure 7 shown.

[0134] Example 5

[0135] The technical solution in this embodiment is basically the same as any of the technical solutions in Embodiments 1-4, except that: the curved reflector 2 is improved, and the improvement principle is as follows: by embedding thermal conductive material in the curved reflector 2, the heat transfer path is optimized and the thermal energy collection efficiency is improved.

[0136] Efficient heat dissipation design: Thermally conductive materials quickly transfer heat to the thermal energy collection system to reduce heat loss.

[0137] Synergistic utilization of light and heat: while ensuring high optical reflectance performance, the heat dissipation and light-heat separation functions are integrated.

[0138] Material and structural design

[0139] Choice of thermal conductive material: copper or aluminum, which have high thermal conductivity (thermal conductivity coefficient is ~400W / (m·K) and ~237W / (m·K) respectively) and can be easily processed into complex structures; or carbon-based materials: graphene or carbon nanotubes, which have ultra-high thermal conductivity (thermal conductivity coefficient can reach ~2000W / (m·K)) and are suitable for enhancing heat conduction efficiency.

[0140] Filling material: High thermal conductivity ceramics (one of boron nitride, aluminum nitride or silicon carbide) are used, which are suitable as filling and reinforcement layers for metal and carbon-based materials, and have both thermal conductivity and high temperature resistance.

[0141] Multifunctional reflector structure design

[0142] Heat conduction channel: A high thermal conductivity material embedded channel is designed on the back side of the curved reflector (the lower surface of the curved reflector) to improve the heat dissipation efficiency by optimizing the geometric structure (such as honeycomb or striped distribution).

[0143] Channel arrangement: spaced apart to cover the high heat area of ​​the reflector and transfer heat evenly.

[0144] Thermal coupling interface: Add interface thermal conductive material (such as thermal conductive paste or thermal conductive adhesive film) between the thermal conductive material and the curved substrate to reduce thermal resistance and improve heat transfer efficiency.

[0145] The light-heat separation structure is designed with a layered structure. The upper layer is a spectrally selective coating for light separation; the lower layer is an embedded thermal conductive layer for heat dissipation and heat transfer.

[0146] Specific preparation process

[0147] S11. Substrate processing

[0148] The curved substrate 201 is made of high-transmittance flexible glass with a thickness of 0.5-5 cm. The curved substrate 201 is cleaned and polished to ensure the surface optical performance. A heat-conducting channel 206 or an embedded structure is prefabricated on the lower surface of the curved substrate 201 through laser cutting or CNC processing, and the heat-conducting material 207 is embedded in the prefabricated channel 206 or the embedded structure. A welding or hot pressing bonding process is used to ensure a firm connection. Interface treatment is performed by coating a thermal conductive paste on the contact surface between the curved substrate 201 and the heat-conducting material 207 to reduce the interface thermal resistance, and a vacuum pressing technology is used to ensure good adhesion between the embedded material and the substrate.

[0149] S12. A silver or aluminum film is uniformly deposited on the surface of the thermal conductive material 207 and the lower surface of the curved substrate 201 by vacuum evaporation or magnetron sputtering to obtain a high reflectivity metal layer 202; subsequently, a weather-resistant protective layer 203 is prepared on the lower surface of the high reflectivity metal layer 202 by chemical vapor deposition (CVD) or spin coating to enhance its corrosion resistance and durability. The thickness of the high reflectivity metal layer 202 can be 50-500nm, more preferably 100-200nm; the thickness of the weather-resistant protective layer 203 can be 30-300nm, more preferably 80-100nm.

[0150] S13. Prepare a spectrally selective coating 208 (such as the spectrally selective coating in Example 3 or a plurality of alternately arranged silicon dioxide layers and titanium dioxide layers) on the upper surface of the curved substrate 201 to obtain a curved reflector 2 (whose structure is as shown in FIG. Figure 8 shown).

[0151] Embodiments 3-5 provided by the present invention are all improvements based on Embodiments 1 and 2, and the technical solutions in each embodiment can be combined with each other.

[0152] The working principle of the double-sided flexible solar cell provided by the present invention is as follows: Fig. 9 As shown, when sunlight irradiates the flexible semi-transparent photovoltaic cell 1, ultraviolet light and visible light are absorbed by the flexible semi-transparent photovoltaic cell 1, and infrared light is reflected by the curved reflector 2 to the collector 5 and absorbed. The flexible photovoltaic cell 3 on the back can further absorb ambient light and ground reflected light. In addition, the sun tracking axis can adjust the direction of the photovoltaic cell to receive as much sunlight as possible. By integrating the upper and lower layers of photovoltaic cells on the curved reflector 2, the triple benefits of photovoltaic power generation and solar thermal utilization are achieved, greatly improving the overall energy utilization efficiency of the curved reflector type solar thermal power station.

[0153] The double-sided flexible solar cell prepared by the above method is applied in trough-type solar thermal power generation system and dish-type solar thermal power generation system, which helps to improve the utilization rate of the solar spectrum and significantly improve the synergistic utilization efficiency of photovoltaic power generation and solar thermal utilization, and has broad application prospects.

[0154] The present invention significantly improves the efficiency of light energy utilization through a unique three-layer structure design, spectral selective utilization, and deep coupling of photovoltaic and photothermal systems, and has obvious advantages over existing technologies. The innovative three-layer structure integrates flexible semi-transparent photovoltaic cells, curved reflectors, and lower-layer flexible photovoltaic cells into one, achieving efficient utilization of the solar spectrum in different bands. The upper-layer flexible semi-transparent photovoltaic cells mainly absorb ultraviolet and visible light, and allow infrared light to pass through the curved reflectors in the middle layer for heat collection; the lower-layer flexible photovoltaic cells use ground reflected light and ambient scattered light to generate electricity. Experiments have shown that this design increases the synergistic efficiency of photovoltaic and photothermal systems by 15% to 20%, the power generation per unit area is 18% higher than that of traditional systems, the thermal energy conversion efficiency is increased by about 12%, and the waste of solar energy resources is significantly reduced. The photoelectric conversion efficiency can reach more than 50%.

[0155] Through spectrally selective coating technology, the middle layer curved reflector not only has high transmittance for infrared light, but also can reflect unabsorbed ultraviolet light and visible light, maximizing the efficiency of spectral distribution. In addition, adding a metal reflective layer on the back of the lower flexible photovoltaic cell and introducing microstructure surface treatment technology significantly enhances the ability to capture indirect light, increasing the power generation efficiency of the lower flexible photovoltaic cell by 8%, effectively making up for the shortcoming of the existing photovoltaic technology in terms of low utilization of scattered light and ground reflected light.

[0156] The upper and lower layers of flexible photovoltaic cells provided by the present invention can adapt to the complex curved reflector structure of trough and dish-type solar thermal power stations. The three-layer design of the trough reflector optimizes the synergistic power generation mode of photovoltaic and solar thermal. When used in high-radiation areas, the overall light energy utilization efficiency is significantly improved; the application of dish-type reflectors further expands the comprehensive utilization potential of direct light and scattered light, and is suitable for deployment in complex terrain or high-scattered light environments. Data shows that the total light energy utilization efficiency of the present invention in actual tests is about 20% higher than that of conventional systems.

[0157] In addition, the present invention optimizes the heat transfer path by embedding thermal conductive materials in the curved reflector, effectively solving the efficiency loss problem caused by heat retention in traditional photothermal systems. Experimental measurements show that the surface temperature of the curved reflector prepared in Example 5 decreased by 10-15°C, the heat transfer efficiency increased by more than 20%, and the overall performance of the thermal energy collection system was significantly improved. This design takes into account both high efficiency and high adaptability, and is particularly suitable for large-scale deployment in areas with high radiation and high temperature differences. Compared with the prior art, the present invention not only optimizes the synergistic utilization mode of photovoltaics and photothermal, but also significantly improves the energy conversion efficiency and system operation stability, providing an innovative solution for the development of photovoltaic-photothermal coupling systems.

[0158] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A double-sided flexible solar cell, characterized in that: The flexible semi-transparent photovoltaic cell, the curved reflector, and the flexible photovoltaic cell are sequentially included from top to bottom. The flexible semi-transparent photovoltaic cell sequentially includes an encapsulation layer, a second transparent electrode, an electron transport layer, a light absorption layer, a hole transport layer, and a first transparent electrode; wherein the positions of the electron transport layer and the hole transport layer can be interchanged; The curved reflector includes, from top to bottom, a curved substrate, a high reflectivity metal layer, and a weather-resistant protective layer; The flexible photovoltaic cell is one of a perovskite solar cell, an organic solar cell, a copper indium gallium selenide solar cell, a dye-sensitized solar cell, a single crystal silicon solar cell, an amorphous silicon solar cell, a cadmium telluride thin film solar cell, and a quantum dot solar cell.

2. The double-sided flexible solar cell according to claim 1, characterized in that: The material of the high reflectivity metal layer of the curved reflector is silver or aluminum, and the material of the weather-resistant protective layer is one of aluminum oxide, silicon dioxide, titanium dioxide and polymer.

3. The double-sided flexible solar cell according to claim 1, characterized in that: The flexible photovoltaic cell is a perovskite solar cell, which includes, from top to bottom, a first transparent electrode, a hole transport layer, a light absorption layer, an electron transport layer, a second transparent electrode, and an encapsulation layer; wherein the positions of the electron transport layer and the hole transport layer of the flexible photovoltaic cell can be interchanged; the material band gap of the light absorption layer of the flexible semi-transparent photovoltaic cell is 1.65eV-2.30eV, and the material band gap of the light absorption layer of the flexible photovoltaic cell is 1.40eV-2.30eV.

4. A method for preparing a double-sided flexible solar cell according to claim 1, characterized in that: The following steps are involved: S1. Preparation of curved mirror A high-reflectivity metal layer and a weather-resistant protective layer are sequentially prepared on the lower surface of the curved substrate to obtain the curved reflector; S2. Prepare flexible semi-transparent photovoltaic cells and flexible photovoltaic cells, and paste the flexible semi-transparent photovoltaic cells and flexible photovoltaic cells on the upper and lower surfaces of the curved reflector; or directly prepare flexible semi-transparent photovoltaic cells and flexible photovoltaic cells on the upper and lower surfaces of the curved reflector; or directly prepare flexible semi-transparent photovoltaic cells or flexible photovoltaic cells on the upper or lower surface of the curved reflector, and then paste the prepared flexible photovoltaic cells or flexible semi-transparent photovoltaic cells on the curved reflector to obtain the double-sided flexible solar cell.

5. The preparation method according to claim 4, characterized in that: The preparation process of the flexible semi-transparent photovoltaic cell is as follows: a first transparent electrode, a hole transport layer, a light absorption layer, an electron transport layer, and a second transparent electrode are sequentially prepared on a transparent flexible substrate or an upper surface of a curved reflector, and finally encapsulated with an encapsulation material; The flexible substrate used in the preparation process of the flexible photovoltaic cell is transparent or opaque, and the rest of the preparation process is consistent with that of the flexible semi-transparent photovoltaic cell.

6. The preparation method according to claim 5, characterized in that: The preparation process of the flexible photovoltaic cell also includes the following steps: after forming the light absorption layer, a microstructure is produced on the surface of the light absorption layer, and the microstructure production is carried out by one or more methods selected from laser direct writing, nanoimprinting, and wet etching; and a metal reflective layer is deposited on the back of the prepared flexible photovoltaic cell, and then a titanium dioxide protective layer is coated on the metal reflective layer.

7. The preparation method according to claim 4, characterized in that: The preparation process of the curved reflector in step S1 is as follows: S11. Preparing a high reflectivity metal layer and a weather-resistant protective layer on the lower surface of the curved substrate in sequence; S12. Deposit a spectrally selective coating on the upper surface of the curved substrate. First, deposit silicon dioxide or silicon nitride on the upper surface of the curved substrate to form an infrared transparent film. Then, alternately deposit high refractive index material layers and low refractive index material layers on the infrared transparent film to form an interference film. Finally, a spectrally selective coating is formed to obtain a curved reflector.

8. The preparation method according to claim 4, characterized in that: The preparation process of the curved reflector in step S1 is as follows: S11. Prefabricate a heat-conducting channel or an embedded structure on a curved substrate, embed a heat-conducting material into the heat-conducting channel or the embedded structure, apply a thermal paste on the contact surface between the curved substrate and the heat-conducting material, and apply vacuum pressing; S12. Preparing a high reflectivity metal layer and a weather-resistant protective layer on the lower surface of the curved substrate in sequence; S13. Finally, a spectrally selective coating is prepared on the upper surface of the curved substrate to obtain the curved reflector.

9. The preparation method according to claim 8, characterized in that: The thermal conductive material is one of copper, graphene sheets or ceramic materials; the thermal conductive paste is silicone grease or carbon-based thermal conductive glue; the spectrally selective coating is a plurality of layers of silicon dioxide and titanium dioxide layers alternately arranged; The preparation process of the curved reflector also includes the following steps: using laser direct writing, nano-imprinting or etching to set a micro-nano structure array on the upper surface of the spectrally selective coating.

10. Use of a double-sided flexible solar cell as described in any one of claims 1 to 3 or a double-sided flexible solar cell prepared by the method described in claims 4 to 9 in a trough-type solar thermal power generation system or a dish-type solar thermal power generation system.

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