Flexible photovoltaic device and production method

Abstract

The present invention provides a flexible photovoltaic device and a production method, which relate to the field of photovoltaic technology. The flexible photovoltaic device comprises a transparent polymer film, a front adhesive film, a battery string, a rear adhesive film, and a rear polymer film which are stacked in sequence; the front adhesive film is located on the front surface of the battery string; and the front surface of the transparent polymer film has a first nano-concave structure. The first nano-concave structure can effectively increase the luminous flux of visible light, thereby effectively increasing the utilization rate of light, increasing the photoelectric conversion efficiency, and increasing the power-to-weight ratio of the flexible photovoltaic device.

Description

Technical Field

[0001] The present invention relates to the field of photovoltaic technology, and in particular to a flexible photovoltaic device and a production method thereof. Background Art

[0002] At present, the aerospace and aviation fields are in urgent need of flexible photovoltaic devices with high power-to-weight ratio and flexibility to meet special environmental requirements.

[0003] The structure of existing flexible photovoltaic devices is usually as follows from front to back: front surface transparent polymer film / adhesive film / cell string / adhesive film / rear polymer film. Polymer film is generally used as packaging material to achieve flexibility and improve power-to-weight ratio.

[0004] However, the inventors discovered during the process of studying the above technology that the existing flexible photovoltaic devices have a relatively low power-to-weight ratio. Summary of the invention

[0005] The present invention provides a flexible photovoltaic device and a production method, aiming to solve the problem of low power-to-weight ratio of existing flexible photovoltaic devices.

[0006] According to a first aspect of the present invention, there is provided a flexible photovoltaic device, comprising: a transparent polymer film, a front adhesive film, a battery string, a rear adhesive film, and a rear polymer film stacked in sequence;

[0007] The front adhesive film is located on the front surface of the battery string;

[0008] The front surface of the transparent polymer film has a first nano-concave structure.

[0009] In the embodiment of the present invention, the first nano-concave structure on the front surface of the transparent polymer film can effectively increase the luminous flux of visible light, thereby effectively improving the utilization rate of light, improving the photoelectric conversion efficiency, and improving the power-to-weight ratio of the flexible photovoltaic device.

[0010] Optionally, the front surface of the rear polymer film has a second nano-concave structure.

[0011] Optionally, the flexible photovoltaic device further includes: a metal reflective layer; the metal reflective layer is deposited on the front surface of the rear polymer film, and after the metal reflective layer is deposited, the metal reflective layer does not fill the second nano-concave structure.

[0012] Optionally, the first nano-concave structures are evenly distributed on the front surface of the transparent polymer film.

[0013] Optionally, the concave depth of the first nano-concave structure in the transparent polymer film is 50nm-1um; and the size of the first nano-concave structure in a direction perpendicular to the stacking direction is 100nm-2um.

[0014] Optionally, the second nano-concave structures are evenly distributed on the front surface of the rear polymer film.

[0015] Optionally, the concave depth of the second nano-concave structure in the post-polymer film is 50 nm-1 um; and the size of the second nano-concave structure in a direction perpendicular to the stacking direction is 100 nm-2 um.

[0016] Optionally, the material of the metal reflective layer is selected from at least one of silver, copper, titanium and aluminum;

[0017] The thickness of the metal reflective layer is 10-100 nm.

[0018] Optionally, the transparent polymer film and the rear polymer film are made of at least one material selected from polyimide, ethylene-tetrachloroethylene copolymer, polytetrafluoroethylene, and polyethylene;

[0019] The light transmittance of the transparent polymer film is greater than or equal to 90%;

[0020] The refractive index of the transparent polymer film is 1.3-1.5;

[0021] The thickness of the transparent polymer film and the post-polymer film are both 20-100 um;

[0022] The materials of the front film and the back film are both selected from at least one of ethylene-vinyl acetate copolymer and polyethylene-octene co-elastomer;

[0023] The thickness of the front adhesive film and the back adhesive film are both 20-100 um.

[0024] Optionally, the battery string includes at least one solar cell;

[0025] The solar cell is selected from at least one of a silicon heterojunction solar cell, a flexible gallium arsenide solar cell, a flexible perovskite / silicon heterojunction stacked solar cell, a flexible copper indium gallium selenide solar cell, and a perovskite solar cell;

[0026] The thickness of the solar cell is 20-100um.

[0027] According to a second aspect of the present invention, there is also provided a method for producing a flexible photovoltaic device, comprising the following steps:

[0028] A monolayer of first nanospheres is disposed on the front surface of the transparent polymer film by using the LB method;

[0029] forming a first nano-concave structure at a position corresponding to the first nano-sphere on the front surface of the transparent polymer film;

[0030] The transparent polymer film, the front adhesive film, the battery string, the rear adhesive film, and the rear polymer film are stacked and laminated in sequence; the front adhesive film is located on the front surface of the battery string.

[0031] Optionally, before the step of sequentially stacking the transparent polymer film, the front adhesive film, the battery string, the rear adhesive film, and the rear polymer film, the method further comprises:

[0032] Using the LB method, a monolayer of second nanospheres is disposed on the front surface of the rear polymer film;

[0033] A second nano-concave structure is formed at a position corresponding to the second nano-sphere on the front surface of the rear polymer film.

[0034] Optionally, before the step of sequentially stacking the transparent polymer film, the front adhesive film, the battery string, the rear adhesive film, and the rear polymer film, the method further comprises:

[0035] Depositing a metal reflective layer on the front surface of the rear polymer film, wherein after depositing the metal reflective layer, the metal reflective layer does not fill the second nano-concave structure;

[0036] The step of sequentially stacking and laminating the transparent polymer film, the front adhesive film, the battery string, the rear adhesive film, and the rear polymer film comprises:

[0037] The transparent polymer film, the front adhesive film, the battery string, the rear adhesive film, and the rear polymer film on which the metal reflective layer is deposited are stacked and laminated in sequence.

[0038] Optionally, the step of forming a first nano-concave structure at a position corresponding to the first nano-sphere on the front surface of the transparent polymer film includes:

[0039] Laminating a transparent polymer film provided with a single layer of first nanospheres, wherein during the lamination process, the first nanospheres are used as a mold to transfer the surface shape of the first nanospheres to the front surface of the transparent polymer film, thereby forming the first nano-concave structure on the front surface of the transparent polymer film;

[0040] The first nanospheres located on the front surface of the transparent polymer film are removed, and the first nano-concave structures located on the front surface of the transparent polymer film are retained.

[0041] Optionally, the step of forming a second nano-concave structure at a position corresponding to the second nano-sphere on the front surface of the rear polymer film comprises:

[0042] Laminating a rear polymer film provided with a single layer of second nanospheres, wherein the second nanospheres are used as a mold to transfer the surface shape of the second nanospheres to the front surface of the rear polymer film, thereby forming the second nano-concave structure on the front surface of the rear polymer film;

[0043] The second nanospheres located on the front surface of the rear polymer film are removed, and the second nano-concave structures located on the front surface of the rear polymer film are retained.

[0044] Optionally, in the step of laminating the transparent polymer film provided with a single layer of first nanospheres, the lamination temperature is greater than or equal to the first glass transition temperature of the transparent polymer film and less than or equal to the sum of the first glass transition temperature and a temperature of 20° C.;

[0045] The first glass transition temperature of the transparent polymer film is greater than or equal to 180°C.

[0046] Optionally, in the step of laminating the rear polymer film provided with a single layer of second nanospheres, the lamination temperature is greater than or equal to the second glass transition temperature of the rear polymer film and less than or equal to the sum of the second glass transition temperature and 20° C.;

[0047] The second glass transition temperature of the post-polymer film is greater than or equal to 180°C.

[0048] Optionally, in the step of laminating the transparent polymer film provided with a single layer of first nanospheres, the lamination temperature is 180° C.-220° C. and the lamination pressure is one atmosphere.

[0049] Optionally, in the step of laminating the post-polymer film provided with a single layer of second nanospheres, the lamination temperature is 180° C.-220° C. and the lamination pressure is one atmosphere.

[0050] Optionally, the first nanosphere and the second nanosphere are both metal oxide nanospheres;

[0051] The particle diameters of the first nanosphere and the second nanosphere are both 100nm-2um.

[0052] Optionally, the first glass transition temperature of the transparent polymer film is greater than or equal to the sum of the third glass transition temperature of the front adhesive film and 20°C.

[0053] Optionally, the second glass transition temperature of the rear polymer film is greater than or equal to the sum of the fourth glass transition temperature of the rear adhesive film and 20°C.

[0054] Optionally, the material of the first nanosphere and the second nanosphere are both selected from at least one of silicon oxide, titanium oxide and aluminum oxide.

[0055] Optionally, in the step of removing the first nanospheres located on the front surface of the transparent polymer film, alkali or acid is used to remove the first nanospheres.

[0056] Optionally, in the step of depositing the metal reflective layer on the front surface of the rear polymer film, sputtering or electron beam evaporation is used for deposition.

[0057] The production method of the flexible photovoltaic device has the same or similar beneficial effects as the aforementioned flexible photovoltaic device. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0059] Figure 1 A schematic structural diagram of a first flexible photovoltaic device in an embodiment of the present invention is shown;

[0060] Figure 2 A schematic structural diagram of a second flexible photovoltaic device in an embodiment of the present invention is shown;

[0061] Figure 3 A schematic structural diagram of a third flexible photovoltaic device according to an embodiment of the present invention is shown;

[0062] Figure 4 A schematic diagram showing a step of forming a transparent polymer film having a first nano-concave structure in an embodiment of the present invention is shown;

[0063] Figure 5 A schematic diagram of the steps of forming a post-polymer film having a second nano-concave structure in an embodiment of the present invention is shown.

[0064] Description of the accompanying drawings:

[0065] 1-transparent polymer film, 11-first nano-concave structure, 12-first nano-sphere, 2-front adhesive film, 3-battery string, 4-rear adhesive film, 5-metal reflective layer, 6-rear polymer film, 61-second nano-sphere, 62-second nano-concave structure. DETAILED DESCRIPTION

[0066] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not 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.

[0067] In the embodiment of the present invention, referring to Figure 1 As shown, Figure 1 The schematic diagram of the structure of the first flexible photovoltaic device in the embodiment of the present invention is shown. The flexible photovoltaic device comprises: a transparent polymer film 1, a front adhesive film 2, a battery string 3, a rear adhesive film 4, and a rear polymer film 6 which are stacked in sequence. The front adhesive film 2 is located on the front surface of the battery string 3, and the rear adhesive film 4 is located on the rear of the battery string 3. The rear of the battery string 3 is opposite to the front surface.

[0068] The front surface of the transparent polymer film 1 has a first nano-concave structure 11, and the front surface of the transparent polymer film 1 is the surface of the transparent polymer film 1 away from the front adhesive film 2. The number of the first nano-concave structures 11 on the front surface of the transparent polymer film 1 is not specifically limited. The first nano-concave structures 11 are concave toward the rear of the transparent polymer film 1, and the first nano-concave structures 11 on the front surface of the transparent polymer film 1 can effectively increase the luminous flux of visible light, thereby effectively improving the utilization rate of light, improving the photoelectric conversion efficiency, and improving the power-to-weight ratio of the flexible photovoltaic device.

[0069] The first nano-concave structure 11 may be formed by: using the LB (Langmuir Blodgett) method to arrange a single layer of first nano-balls on the front surface of the transparent polymer film 1, laminating the transparent polymer film 1 provided with the single layer of first nano-balls, during the lamination process, using the first nano-balls as a mold, transferring the surface shape of the first nano-balls to the front surface of the transparent polymer film 1, and then removing the first nano-balls on the front surface of the transparent polymer film 1 to form the first nano-concave structure 11 on the front surface of the transparent polymer film 1. Through lamination, the first nano-balls have a stronger adhesion to the front surface of the transparent polymer film 1, and a more stable and uniform first nano-concave structure 11 can be obtained.

[0070] Figure 1 The structural schematic diagram of the flexible photovoltaic device shown can be applicable to all batteries and all components.

[0071] Optional, see Figure 2 As shown, Figure 2 The schematic diagram of the structure of the second flexible photovoltaic device in the embodiment of the present invention is shown. Figure 1On the basis of the above, in the flexible photovoltaic device, the front surface of the rear polymer film 6 has a second nano-concave structure, and the front surface of the rear polymer film 6 is the surface of the rear polymer film 6 close to the rear adhesive film 4. The number of the second nano-concave structures on the front surface of the rear polymer film 6 is not specifically limited. The second nano-concave structure is concave toward the rear of the rear polymer film 6. The second nano-concave structure on the front surface of the rear polymer film 6 can effectively improve the scattering of long-wave light passing through the battery string, effectively improve the light path, and then effectively improve the utilization rate of light, improve the photoelectric conversion efficiency, and improve the power-to-weight ratio of the flexible photovoltaic device.

[0072] The second nanometer concave structure may be formed by: using the LB method to set a single layer of second nanometer balls on the front surface of the rear polymer film 6, laminating the rear polymer film 6 provided with the single layer of second nanometer balls, during the lamination process, using the second nanometer balls as a mold, transferring the surface shape of the second nanometer balls to the front surface of the rear polymer film 6, and then removing the second nanometer balls located on the front surface of the rear polymer film 6 to form the second nanometer concave structure located on the front surface of the rear polymer film 6. Through lamination, the second nanometer balls have a stronger adhesion to the front surface of the rear polymer film 6, and a more stable and uniform second nanometer concave structure can be obtained.

[0073] Figure 2 The structural schematic diagram of the flexible photovoltaic device shown can be applicable to bifacial cells or bifacial modules.

[0074] Optional, see Figure 3 As shown, Figure 3 The third flexible photovoltaic device in the embodiment of the present invention is shown in the structural schematic diagram, which is applicable to double-sided cells and single-sided modules. The flexible photovoltaic device also includes: a metal reflective layer 5.

[0075] The metal reflective layer 5 is deposited on the front surface of the rear polymer film 6, and after the metal reflective layer 5 is deposited, the second nano-concave structure is not filled in the metal reflective layer 5. The unfilled second nano-concave structure can effectively improve the scattering of long-wave light passing through the battery string, effectively improve the light path, and the metal reflective layer 5 deposited on the front surface of the rear polymer film 6 can effectively improve the reflection of long-wave light passing through the battery string, effectively improve the light path, and then effectively improve the utilization rate of light, improve the photoelectric conversion efficiency, and improve the power-to-weight ratio of the flexible photovoltaic device.

[0076] Compared with the conventional nano-light trapping structure formed by a Nanoimprint method such as Emboss to form a specific nanostructure, the first nano-concave structure 11 and the second nano-concave structure in the embodiment of the present invention are simple in process, suitable for large-area preparation, and low in cost. At the same time, in the process of preparing the first nano-concave structure 11 and the second nano-concave structure, the existing lamination equipment can be used, and the process parameters and the equipment parameters are basically matched, without adding new process equipment.

[0077] Optional, see Figure 1 , Figure 3 As shown, the concave depth L1 of the first nano-concave structure 11 in the transparent polymer film 1 is 50nm-1um, and the dimension L2 of the first nano-concave structure 11 perpendicular to the stacking direction is 100nm-2um. The dimension of the first nano-concave structure 11 can be further adjusted within the above-mentioned dimension range to further increase the luminous flux of visible light.

[0078] Optionally, the second nano-concave structure has a concave depth of 50nm-1um in the rear polymer film 6, and a size of the second nano-concave structure perpendicular to the stacking direction is 100nm-2um. The size of the second nano-concave structure can be further adjusted within the above size range to further increase the luminous flux of visible light.

[0079] Optionally, the first nano-concave structures 11 are evenly distributed on the front surface of the transparent polymer film 1 , thereby further effectively improving the scattering of long-wave light passing through the battery string and effectively improving the light path.

[0080] Optionally, the second nano-concave structures are evenly distributed on the front surface of the rear polymer film 6, further effectively improving the scattering of long-wave light passing through the battery string and effectively improving the light path.

[0081] Optionally, the material of the metal reflective layer 5 is selected from at least one of silver, copper, titanium and aluminum. The metal reflective layer 5 formed by the above materials has a higher reflectivity and can more effectively enhance the reflection of long-wave light passing through the battery string.

[0082] Optionally, the thickness of the metal reflective layer 5 is 10-100 nm, and the thickness of the metal reflective layer 5 is the size of the metal reflective layer 5 in the stacking direction of the front adhesive film 2, the battery string 3, and the back adhesive film 4. The metal reflective layer 5 of the above thickness has a higher reflectivity and more effectively improves the reflection of long-wave light passing through the battery string.

[0083] Optionally, the materials of the transparent polymer film 1 and the rear polymer film 6 are both selected from at least one of polyimide (PI), ethylene-tetrachloroethylene copolymer (ETFE), polytetrafluoroethylene (PTFE), and polyethylene (PE).

[0084] Optionally, the light transmittance of the transparent polymer film 1 is greater than or equal to 90%, which increases the luminous flux of visible light. The light transmittance of the rear polymer film 6 is not specifically limited. The front adhesive film 2 also has good light transmittance.

[0085] Optionally, the refractive index of the transparent polymer film is 1.3-1.5, which increases the luminous flux of visible light. The thickness of the transparent polymer film 1 and the rear polymer film 6 are both 20-100 um, and the above thickness is the dimension in the stacking direction of the front film 2, the battery string 3, and the rear film 4.

[0086] Optionally, the materials of the front film 2 and the back film 4 are selected from at least one of ethylene-vinyl acetate copolymer (EVA) and polyethylene octene co-elastomer (POE). The thickness of the front film 2 and the back film 4 is 20-100um, and the above thickness is the dimension in the stacking direction of the front film 2, the battery string 3, and the back film 4.

[0087] Optionally, the battery string 3 includes at least one solar cell, and the solar cell is selected from at least one of a silicon heterojunction (SHJ) solar cell, a flexible gallium arsenide solar cell, a flexible perovskite / silicon heterojunction stacked solar cell, a flexible copper indium gallium selenide (CIGS) solar cell, and a perovskite solar cell. The thickness of the solar cell is 20-100um, and the above thickness is the dimension in the stacking direction of the front adhesive film 2, the battery string 3, and the back adhesive film 4. The first nano-concave structure 11, the second nano-concave structure, and the metal reflective layer 5 in the embodiment of the present invention can fully extend the optical path of visible light, improve the absorption of long-wave light by the solar cell, and fully compensate for the reduction in short-circuit current that may be caused by the thinning of the thickness of the solar cell, especially fully compensate for the reduction in short-circuit current that may be caused by the thinning of the thickness of the above solar cell.

[0088] The present invention also provides a method for producing a flexible photovoltaic device, the method comprising the following steps:

[0089] Step S1, disposing a single layer of first nanospheres on the front surface of a transparent polymer film by using the LB method.

[0090] In the embodiment of the present invention, the LB (Langmuir Blodgett) method specifically arranges the first nanospheres uniformly on the front surface of the transparent polymer film to form a single layer of the first nanospheres. Figure 4 As shown, Figure 4 A schematic diagram of the steps of forming a transparent polymer film having a first nano-concave structure in an embodiment of the present invention is shown. Figure 4 In the figure, the first step is located above the top arrow, and the first step is a schematic diagram of the result of step S1. In the first step, a single layer of first nanospheres 12 is disposed on the front surface of the transparent polymer film 1.

[0091] Optionally, the first nanospheres 12 are metal oxide nanospheres. The first nanospheres 12 made of the above material can obtain a relatively stable and uniform first nanostructure on the front surface of the transparent polymer film 1 .

[0092] Optionally, the material of the first nanospheres 12 is selected from at least one of silicon oxide, titanium oxide and aluminum oxide. The first nanospheres 12 of the above materials can obtain a relatively stable and uniform first nanostructure on the front surface of the transparent polymer film 1 .

[0093] Optional, see Figure 4 As shown, the particle size d1 of the first nanosphere 12 is 100nm-2um, and the first nanostructure formed on the front surface of the transparent polymer film 1 is more conducive to improving the luminous flux of visible light. A more specific particle size can be specifically selected according to the shape and size of the required light trapping structure.

[0094] Step S2, forming a first nano-concave structure at a position corresponding to the first nano-sphere on the front surface of the transparent polymer film.

[0095] The first nano-ball 12 may be pressed to form a first nano-concave structure at a position corresponding to the first nano-ball 12 on the front surface of the transparent polymer film 1 .

[0096] Optionally, the above step S2 may include: laminating a transparent polymer film provided with a single layer of first nanospheres, wherein during the lamination process, the first nanospheres are used as a mold, and the surface shape of the first nanospheres is transferred to the front surface of the transparent polymer film, so as to form the first nano-concave structure on the front surface of the transparent polymer film. The first nanospheres located on the front surface of the transparent polymer film are removed, and the first nano-concave structure located on the front surface of the transparent polymer film is retained.

[0097] Specifically, the process of laminating the transparent polymer film provided with a single layer of the first nanospheres can be performed using an existing laminator. Figure 4 In the second step, during the lamination process, the first nanosphere 12 is partially or completely pressed into the transparent polymer film 1 , and the first nanosphere 12 serves as a mold to transfer the surface shape of the first nanosphere 12 to the front surface of the transparent polymer film 1 .

[0098] Optionally, during lamination of the transparent polymer film provided with a single layer of first nanospheres, the lamination temperature is greater than or equal to the first glass transition temperature of the transparent polymer film 1, and less than or equal to the sum of the glass transition temperature of the transparent polymer film 1 and a temperature of 20°C. In other words, the lamination temperature needs to be greater than or equal to the glass transition temperature of the transparent polymer film 1, and needs to be less than or equal to the glass transition temperature of the transparent polymer film 1 + 20°C. In this case, the portion of the transparent polymer film 1 where the first nanospheres are not provided will hardly deform or will deform slightly, and will not affect the light transmittance of the transparent polymer film 1.

[0099] Optionally, during the lamination process of the transparent polymer film provided with a single layer of the first nanospheres, the lamination temperature can be further 180°C-220°C, and the lamination pressure is one atmosphere. Not only can better lamination be achieved on the existing laminator, but also the portion of the transparent polymer film 1 where the first nanospheres are not provided will hardly deform or will deform only slightly, and will not affect the transmittance of the transparent polymer film 1.

[0100] Optionally, the first glass transition temperature of the transparent polymer film 1 is greater than or equal to 180° C., so that during the lamination process on an existing laminator, better lamination can be achieved, and the portion of the transparent polymer film 1 where the first nanospheres are not provided will hardly deform or will deform slightly, and will not affect the transmittance of the transparent polymer film 1.

[0101] Optionally, the first glass transition temperature of the transparent polymer film 1 is greater than or equal to the sum of the third glass transition temperature of the front film 2 and 20°C. The first glass transition temperature of the transparent polymer film 1 is greater than or equal to the sum of the fourth glass transition temperature of the back film 4 and 20°C. The entire process is applicable to existing laminators, and during the lamination process, the size of the transparent polymer film 1 is relatively stable. It should be noted that whether the third glass transition temperature of the front film 2 is equal to the fourth glass transition temperature of the back film 4 is not specifically limited.

[0102] The first nanospheres 12 pressed into the front surface of the transparent polymer film 1 are removed, and the first nano-concave structures 11 located on the front surface of the transparent polymer film 1 are formed at the position where the first nanospheres 12 are removed in the transparent polymer film 1 . Figure 4 In the third step, a transparent polymer film having a first nano-concave structure is shown.

[0103] Optionally, in the step of removing the first nanospheres 12 located on the front surface of the transparent polymer film 1, an alkali or acid is used to remove the first nanospheres 12. The process of removing the first nanospheres 12 is simple and will not damage the transparent polymer film 1. One or more combinations of commonly used acids can be selected, or one or more combinations of commonly used alkalis can be selected. For example, NaOH is used to remove the first nanospheres 12, or HCl, HF, H 2 SO 4 The first nanosphere 12 is washed away by the acid combination.

[0104] Step S3, stacking and laminating the transparent polymer film, the front adhesive film, the battery string, the rear adhesive film, and the rear polymer film in sequence; the front adhesive film is located on the front surface of the battery string.

[0105] Transparent polymer film 1, front adhesive film 2, battery string 3, back adhesive film 4, and back polymer film 6 are stacked and laid on the laminator in sequence to complete the lamination of the device. During lamination, vacuum is first drawn, heated to 130℃-160℃, and then pressurized to 80±10kpa, so that the molten EVA or POE flows and fills the gap between the transparent polymer film 1, the back polymer film 6 and the solar cell under the action of extrusion, and the bubbles in the middle are discharged at the same time, so that the transparent polymer film 1, the back polymer film 6, and the solar cell are tightly bonded together through the adhesive film, and taken out after cooling and solidification, and the preparation of the flexible photovoltaic device is completed.

[0106] Optionally, before the above step S3, the method may further include the following steps S4, S5 and S6.

[0107] Step S4, disposing a single layer of second nanospheres on the front surface of the rear polymer film by LB method.

[0108] Step S4 is similar to step S1, and will not be described again to avoid repetition. Figure 5 As shown, Figure 5 A schematic diagram of the steps of forming a post-polymer film having a second nano-concave structure in an embodiment of the present invention is shown. Figure 5 In the figure, the first step is located above the top arrow, and the first step is a result of step S4. The second step is located below the top arrow. The third step is located below the middle arrow. The fourth step is located below the bottom arrow. In the first step, a single layer of second nanospheres 61 is provided on the front surface of the rear polymer film 6.

[0109] Optionally, the second nanospheres 61 are metal oxide nanospheres. The second nanospheres 61 made of the above material can obtain a relatively stable and uniform second nanostructure on the front surface of the rear polymer film 6 .

[0110] Optionally, the material of the second nanospheres 61 is selected from at least one of silicon oxide, titanium oxide and aluminum oxide. The second nanospheres 61 of the above materials can obtain a relatively stable and uniform second nanostructure on the front surface of the rear polymer film 6 .

[0111] Optional, see Figure 5 As shown, the particle size d2 of the second nanosphere 61 is 100nm-2um, and the second nanostructure formed on the front surface of the rear polymer film 6 is more conducive to improving the scattering of long-wave light passing through the battery string, effectively improving the light path. A more specific particle size can be specifically selected according to the shape and size of the required light trapping structure.

[0112] Step S5, forming a second nano-concave structure at a position corresponding to the second nano-sphere on the front surface of the rear polymer film.

[0113] The second nano-concave structure may be formed on the front surface of the rear polymer film 6 at a position corresponding to the second nano-ball 61 by pressing the second nano-ball.

[0114] Optionally, the above-mentioned step S5 can be specifically as follows: laminating a rear polymer film provided with a single layer of second nanospheres, during the lamination process, the second nanospheres are used as a mold to transfer the surface shape of the second nanospheres to the front surface of the rear polymer film, and form a second nano-concave structure on the front surface of the rear polymer film; removing the second nanospheres located on the front surface of the rear polymer film, and retaining the second nano-concave structure located on the front surface of the rear polymer film.

[0115] The lamination of the second polymer film provided with a single layer of nanospheres is similar to the lamination of the transparent polymer film provided with a single layer of the first nanospheres, and will not be described here in detail to avoid repetition. Figure 5 As shown in the second step, during the lamination process, the second nanosphere 61 is partially or completely pressed into the rear polymer film 6 , and the second nanosphere 61 serves as a mold to transfer the surface shape of the second nanosphere 61 to the front surface of the rear polymer film 6 .

[0116] Optionally, in laminating the rear polymer film provided with a single layer of second nanospheres, the lamination temperature is greater than or equal to the second glass transition temperature of the rear polymer film 6, and less than or equal to the sum of the glass transition temperature of the rear polymer film 6 and a temperature of 20° C. That is, the lamination temperature needs to be greater than or equal to the glass transition temperature of the rear polymer film 6, and needs to be less than or equal to the glass transition temperature of the rear polymer film 6+20° C. In this case, the portion of the rear polymer film 6 where the second nanospheres are not provided will hardly deform or will deform slightly.

[0117] Optionally, in the lamination of the post-polymer film provided with a single layer of second nanospheres, the lamination temperature can further be 180°C-220°C, and the lamination pressure is one atmosphere. Not only can better lamination be achieved on the existing laminator, but also the portion of the post-polymer film 6 where the second nanospheres are not provided will hardly deform or will deform only slightly.

[0118] Optionally, the second glass transition temperature of the rear polymer film 6 is greater than or equal to 180° C., so that during lamination on an existing laminator, better lamination can be achieved, and the portion of the rear polymer film 6 where the first nanospheres are not disposed will hardly deform or will deform slightly.

[0119] Optionally, the second glass transition temperature of the rear polymer film 6 is greater than or equal to the sum of the fourth glass transition temperature of the rear adhesive film 4 and 20° C. The second glass transition temperature of the rear polymer film 6 is greater than or equal to the sum of the third glass transition temperature of the front adhesive film 2 and 20° C. The entire process is applicable to existing laminators, and during the lamination process, the size of the rear polymer film 6 is relatively stable.

[0120] Removing the second nanosphere is similar to removing the first nanosphere, and will not be described here to avoid repetition. Figure 5 As shown in the third step, a rear polymer film 6 having a second nano-concave structure 62 is formed.

[0121] Optionally, in the step of removing the second nanospheres 61 located on the front surface of the rear polymer film 6, an alkali or acid is used to remove the second nanospheres 61. The process of removing the second nanospheres 61 is simple and will not damage the rear polymer film 6. One or more combinations of commonly used acids can be selected, or one or more combinations of commonly used alkalis can be selected. For example, NaOH is used to remove the second nanospheres 61, or HCl, HF, H 2 SO 4 The second nanosphere 61 is washed away by the acid combination.

[0122] Step S6, depositing a metal reflective layer on the front surface of the rear polymer film, wherein after the metal reflective layer is deposited, the metal reflective layer does not fill up the second nano-concave structure.

[0123] Reference Figure 5 As shown in the fourth step, after the metal reflective layer 5 is deposited, the metal reflective layer 5 does not fill the second nano-concave structure.

[0124] Optionally, the metal reflective layer may be deposited by sputtering or electron beam evaporation to deposit the metal reflective layer 5 on the front surface of the rear polymer film 6 , which is a simple process.

[0125] The above step S3 may be to stack and laminate the transparent polymer film, the front adhesive film, the battery string, the rear adhesive film, and the rear polymer film on which the metal reflective layer is deposited in sequence.

[0126] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific embodiments. The above-mentioned specific embodiments are merely illustrative and not restrictive. Under the enlightenment of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the purpose of the present invention and the claims, which all fall within the protection of the present invention.

Claims

1. A flexible photovoltaic device, characterized in that: include: A transparent polymer film, a front adhesive film, a battery string, a rear adhesive film, and a rear polymer film are sequentially stacked; The front adhesive film is located on the front surface of the battery string; The front surface of the transparent polymer film has a first nano-concave structure; Among them, the first nano-concave structure is formed by laminating the transparent polymer film provided with nanospheres. During the lamination process, the nanospheres are used as molds to transfer at least part of the outer surface shape of the nanospheres to the front surface of the transparent polymer film, and then the nanospheres located on the front surface of the transparent polymer film are removed.

2. The flexible photovoltaic device according to claim 1, characterized in that: The front surface of the rear polymer film has a second nano-concave structure.

3. The flexible photovoltaic device according to claim 2, characterized in that: The flexible photovoltaic device further includes: a metal reflective layer; the metal reflective layer is deposited on the front surface of the rear polymer film, and after the metal reflective layer is deposited, the metal reflective layer does not fill the second nano-concave structure.

4. The flexible photovoltaic device according to claim 1 or 2, characterized in that: The first nano-concave structures are evenly distributed on the front surface of the transparent polymer film.

5. The flexible photovoltaic device according to claim 1 or 2, characterized in that: The concave depth of the first nano-concave structure in the transparent polymer film is 50nm-1um; the size of the first nano-concave structure in a direction perpendicular to the stacking direction is 100nm-2um.

6. The flexible photovoltaic device according to claim 2, characterized in that: The second nano-concave structures are evenly distributed on the front surface of the rear polymer film.

7. The flexible photovoltaic device according to claim 2, characterized in that: The concave depth of the second nano-concave structure in the post-polymer film is 50nm-1um; the size of the second nano-concave structure in a direction perpendicular to the stacking direction is 100nm-2um.

8. The flexible photovoltaic device according to claim 3, characterized in that: The material of the metal reflective layer is selected from at least one of silver, copper, titanium and aluminum; The thickness of the metal reflective layer is 10-100 nm.

9. The flexible photovoltaic device according to any one of claims 1 to 3, characterized in that: The materials of the transparent polymer film and the rear polymer film are selected from at least one of polyimide, ethylene-tetrachloroethylene copolymer, polytetrafluoroethylene, and polyethylene; The light transmittance of the transparent polymer film is greater than or equal to 90%; The refractive index of the transparent polymer film is 1.3-1.5; The thickness of the transparent polymer film and the post-polymer film are both 20-100 um; The materials of the front film and the back film are both selected from at least one of ethylene-vinyl acetate copolymer and polyethylene-octene co-elastomer; The thickness of the front adhesive film and the back adhesive film are both 20-100 um.

10. The flexible photovoltaic device according to any one of claims 1 to 3, characterized in that: The battery string includes at least one solar cell; The solar cell is selected from at least one of a silicon heterojunction solar cell, a flexible gallium arsenide solar cell, a flexible perovskite / silicon heterojunction stacked solar cell, a flexible copper indium gallium selenide solar cell, and a perovskite solar cell; The thickness of the solar cell is 20-100um.

11. A method for producing a flexible photovoltaic device, characterized in that: The steps include: A monolayer of first nanospheres is disposed on the front surface of the transparent polymer film by using the LB method; forming a first nano-concave structure at a position corresponding to the first nano-sphere on the front surface of the transparent polymer film; The transparent polymer film, the front adhesive film, the battery string, the rear adhesive film, and the rear polymer film are sequentially stacked and laminated; the front adhesive film is located on the front surface of the battery string; Wherein, the step of forming a first nano-concave structure at a position corresponding to the first nano-sphere on the front surface of the transparent polymer film comprises: Laminating a transparent polymer film provided with a single layer of first nanospheres, wherein during the lamination process, the first nanospheres are used as a mold to transfer the surface shape of the first nanospheres to the front surface of the transparent polymer film, thereby forming the first nano-concave structure on the front surface of the transparent polymer film; The first nanospheres located on the front surface of the transparent polymer film are removed, and the first nano-concave structures located on the front surface of the transparent polymer film are retained.

12. The method for producing a flexible photovoltaic device according to claim 11, characterized in that: Before the step of sequentially stacking the transparent polymer film, the front adhesive film, the battery string, the rear adhesive film, and the rear polymer film, the method further comprises: Using the LB method, a monolayer of second nanospheres is disposed on the front surface of the rear polymer film; A second nano-concave structure is formed at a position corresponding to the second nano-sphere on the front surface of the rear polymer film.

13. The method for producing a flexible photovoltaic device according to claim 12, characterized in that: Before the step of sequentially stacking the transparent polymer film, the front adhesive film, the battery string, the rear adhesive film, and the rear polymer film, the method further comprises: Depositing a metal reflective layer on the front surface of the rear polymer film, wherein after depositing the metal reflective layer, the metal reflective layer does not fill the second nano-concave structure; The step of sequentially stacking and laminating the transparent polymer film, the front adhesive film, the battery string, the rear adhesive film, and the rear polymer film comprises: The transparent polymer film, the front adhesive film, the battery string, the rear adhesive film, and the rear polymer film on which the metal reflective layer is deposited are stacked and laminated in sequence.

14. The method for producing a flexible photovoltaic device according to claim 12, characterized in that: The step of forming a second nano-concave structure at a position corresponding to the second nano-sphere on the front surface of the rear polymer film comprises: Laminating a rear polymer film provided with a single layer of second nanospheres, wherein the second nanospheres are used as a mold to transfer the surface shape of the second nanospheres to the front surface of the rear polymer film, thereby forming the second nano-concave structure on the front surface of the rear polymer film; The second nanospheres located on the front surface of the rear polymer film are removed, and the second nano-concave structures located on the front surface of the rear polymer film are retained.

15. The method for producing a flexible photovoltaic device according to claim 11, characterized in that: In the step of laminating the transparent polymer film provided with a single layer of first nanospheres, the lamination temperature is greater than or equal to the first glass transition temperature of the transparent polymer film and less than or equal to the sum of the first glass transition temperature and 20° C.; The first glass transition temperature of the transparent polymer film is greater than or equal to 180°C.

16. The method for producing a flexible photovoltaic device according to claim 14, characterized in that: In the step of laminating the post-polymer film provided with a single layer of second nanospheres, the lamination temperature is greater than or equal to the second glass transition temperature of the post-polymer film and less than or equal to the sum of the second glass transition temperature and 20° C.; The second glass transition temperature of the post-polymer film is greater than or equal to 180°C.

17. The method for producing a flexible photovoltaic device according to claim 15, characterized in that: In the step of laminating the transparent polymer film provided with a single layer of first nanospheres, the lamination temperature is 180° C.-220° C. and the lamination pressure is one atmosphere.

18. The method for producing a flexible photovoltaic device according to claim 16, characterized in that: In the step of laminating the post-polymer film provided with a single layer of second nanospheres, the lamination temperature is 180° C.-220° C. and the lamination pressure is one atmosphere.

19. The method for producing a flexible photovoltaic device according to claim 12, characterized in that: The first nanosphere and the second nanosphere are both metal oxide nanospheres; The particle diameters of the first nanosphere and the second nanosphere are both 100nm-2um.

20. The method for producing a flexible photovoltaic device according to claim 15 or 17, characterized in that: The first glass transition temperature of the transparent polymer film is greater than or equal to the sum of the third glass transition temperature of the front adhesive film and 20°C.

21. The method for producing a flexible photovoltaic device according to claim 16 or 18, characterized in that: The second glass transition temperature of the rear polymer film is greater than or equal to the sum of the fourth glass transition temperature of the rear adhesive film and 20°C.

22. The method for producing a flexible photovoltaic device according to claim 12, characterized in that: The materials of the first nanosphere and the second nanosphere are both selected from at least one of silicon oxide, titanium oxide and aluminum oxide.

23. The method for producing a flexible photovoltaic device according to claim 11, characterized in that: In the step of removing the first nanospheres located on the front surface of the transparent polymer film, alkali or acid is used to remove the first nanospheres.

24. The method for producing a flexible photovoltaic device according to claim 13, characterized in that: In the step of depositing the metal reflective layer on the front surface of the rear polymer film, sputtering or electron beam evaporation is used for deposition.

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