A thin-film solar cell, a method for manufacturing the same, a photovoltaic module, and a power generation apparatus

Abstract

The embodiment of the present application provides a thin-film solar cell, a preparation method thereof, a photovoltaic module and a power generation equipment. The optical structure is arranged on the back of the thin-film solar cell, the optical structure comprises alternately arranged light conversion layers and distributed Bragg reflection layers, the light conversion layer can convert light which is not fully absorbed by the thin-film solar cell and is outside the absorbable wave band of the thin-film solar cell into light within the absorbable wave band, and the transmission direction of the light converted by the light conversion layer is adjusted through the distributed Bragg reflection layer, so that the thin-film solar cell absorbs the light, the optical utilization rate of the incident light of the thin-film solar cell is improved, the utilization rate of the light outside the absorbable wave band of the thin-film solar cell is improved, and then the overall output power of the thin-film solar cell is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, in particular to a thin-film solar cell, a preparation method thereof, a photovoltaic module and a power generation device. BACKGROUND

[0002] Solar energy is a renewable energy source, which has the advantages of being clean, safe and widely used, and plays an important role in long-term energy strategy. Photovoltaic power generation is a technology that converts light energy into electrical energy by using the photovoltaic effect of semiconductor materials. The core unit of photovoltaic power generation is a photovoltaic module. Common photovoltaic modules include single-sided cell modules and double-sided cell modules. The difference between the double-sided cell module and the single-sided cell module is that the double-sided cell module is packaged by a double-sided thin-film solar cell. The front side and the back side of the double-sided thin-film solar cell can both receive solar radiation and generate electrical energy. Therefore, the power generation efficiency of the double-sided cell module is greatly improved compared with the single-sided cell module.

[0003] Generally, the structure of the double-sided thin-film solar cell includes a front transparent electrode, a back transparent electrode and a light absorption conversion layer disposed between the front transparent electrode and the back transparent electrode. Since the front side and the back side of the double-sided thin-film solar cell are both transparent electrodes, when the thickness of the light absorption conversion layer is low, there is a situation that the long-wave band light in the absorption band cannot be fully absorbed, resulting in light waste. Moreover, due to the limitation of the band gap width of the light absorption conversion layer material, there is also a situation that infrared light cannot be fully utilized. SUMMARY

[0004] Embodiments of the present application provide a thin-film solar cell, a preparation method thereof, a photovoltaic module and a power generation device to improve the utilization rate of light.

[0005] In a first aspect, embodiments of the present application provide a thin-film solar cell, which includes a first transparent substrate, a cell structure located on the first transparent substrate, and an optical structure located on the cell structure. The cell structure is used to absorb light in a first wavelength range and generate electron-hole pairs by absorbing the light to form photo-generated carriers and generate photo-generated current. That is, the light in the first wavelength range is within the absorbable band of the cell structure.

[0006] Exemplarily, the battery structure can include: a first conductive layer, a first charge transport layer, a light absorption conversion layer, a second charge transport layer and a second conductive layer which are sequentially arranged on the first transparent substrate. Optionally, the materials of the first conductive layer and the second conductive layer can be both transparent conductive materials, and then the thin-film solar cell in the embodiment of the present application can include a double-sided thin-film solar cell. Wherein, L31 represents light in the first wavelength range in the front incident light, L32 represents light out of the first wavelength range in the front incident light, L31 and L32 are incident from one side of the first conductive layer, the light absorption conversion layer generates electron-hole pairs after absorbing L31, forms photo-generated carriers, and thus generates photo-generated current. L41 represents light in the first wavelength range in the back incident light, L42 represents light out of the first wavelength range in the back incident light, L41 and L42 are incident from one side of the second conductive layer, the light absorption conversion layer also generates electron-hole pairs after absorbing L41, forms photo-generated carriers, and also generates photo-generated current.

[0007] In addition, the optical structure includes: at least one light conversion layer and at least one distributed Bragg reflection layer which are alternately arranged; the film layer farthest from the battery structure in the optical structure is the distributed Bragg reflection layer. Wherein, the light conversion layer is used to convert the light incident thereon after passing through the battery structure into light in the first wavelength range. The distributed Bragg reflection layer is used to reflect the light incident thereon, so that the propagation direction of the reflected light is directed to the battery structure.

[0008] Based on this, due to the thickness of the light absorption conversion layer and the band gap of the material, the light L31 may not be fully absorbed by the light absorption conversion layer (for example, the light in the long wave band of the first wavelength is not fully absorbed by the light absorption conversion layer), so a part of the light (for example, the light in the long wave band of the first wavelength) may be incident on the light conversion layer after passing through the battery structure. And, the light L32 is not directly absorbed by the light absorption conversion layer, and this part of the light is also incident on the light conversion layer after passing through the battery structure. The light conversion layer converts the light incident on it after passing through the battery structure into light in the first wavelength range. That is, the light converted by the light conversion layer can be absorbed by the light absorption conversion layer, and the light conversion layer can convert the light incident on the front and not fully absorbed by the thin-film solar cell and outside the absorption band of the thin-film solar cell into light within the absorption band. And, among the light converted by the light conversion layer, a part of the light has a propagation direction pointing to the battery structure, and these lights pointing to the battery structure can be reabsorbed by the light absorption conversion layer to improve the output power of the thin-film solar cell. However, among the light converted by the light conversion layer, a part of the light has a propagation direction away from the battery structure, and these lights away from the battery structure can be directly incident on the distributed Bragg reflector, and through the action of the distributed Bragg reflector, the propagation direction of the light is changed, so that the propagation direction of the light points to the battery structure, and thus is reabsorbed by the light absorption conversion layer, further improving the output power of the thin-film solar cell.

[0009] Therefore, the thin-film solar cell provided by the embodiment of the present application sets the optical structure on the back of the thin-film solar cell, the optical structure includes the light conversion layer and the distributed Bragg reflector arranged alternately, the light conversion layer can convert the light not fully absorbed by the thin-film solar cell and outside the absorption band of the thin-film solar cell into light within the absorption band, and the transmission direction of the light converted by the light conversion layer is adjusted by the distributed Bragg reflector, so that the thin-film solar cell absorbs the light, improves the optical utilization rate of the incident light of the thin-film solar cell, and improves the utilization rate of the light outside the absorption band of the thin-film solar cell, thereby improving the overall output power of the thin-film solar cell.

[0010] In the embodiment of the present application, the thin-film solar cell can be any one of a cadmium telluride battery, a copper indium gallium selenide battery, a perovskite battery or an organic solar cell, as long as it includes a light absorption conversion layer, and the light absorption conversion layer generates an electron-hole pair after absorbing light, and generates a current. It belongs to the protection scope of the present application.

[0011] Optionally, the converted light of the light conversion layer has a wavelength range of a second wavelength range. Illustratively, the converted light of the light conversion layer can have the same wavelength range as the first wavelength range, i.e., the second wavelength range corresponding to the light conversion layer is the same as the first wavelength range. Alternatively, the converted light of the light conversion layer can also have a wavelength range within the first wavelength range, i.e., the first wavelength range contains the second wavelength range corresponding to the light conversion layer. For example, the first wavelength range can be 400nm to 800nm, and the second wavelength range corresponding to the light conversion layer can be 500nm to 600nm, or the second wavelength range corresponding to the light conversion layer can also be 480nm to 700nm. Of course, in actual applications, the first wavelength range and the second wavelength range can be determined according to the requirements of actual applications, which are not limited in the present application.

[0012] In some examples, the material of the light conversion layer can include up-conversion material. The up-conversion material is used to convert light with a wavelength greater than the maximum wavelength of the second wavelength range into light within the second wavelength range. In this way, the light conversion layer can absorb light with a wavelength range that includes light with a wavelength greater than the maximum wavelength of the second wavelength range, thereby converting light with a wavelength greater than the maximum wavelength of the second wavelength range into light within the second wavelength range. For example, when the second wavelength range is 500nm to 600nm, the up-conversion material is used to convert light with a wavelength greater than 600nm into light within the second wavelength range. Optionally, when the second wavelength range is 500nm to 600nm, the up-conversion material can convert light within a wavelength range of 600nm to 1100nm into light within the second wavelength range.

[0013] Illustratively, the up-conversion material includes but is not limited to up-conversion quantum dot material. Optionally, the up-conversion quantum dot material includes but is not limited to: NaYF4:Yb 3+ :Er 3+ quantum dot material (e.g., with an average size of 20nm), etc., which can also be a combination of multiple materials, and the material system is adjusted according to the wavelength conversion requirements, which are not limited in the present application.

[0014] Exemplarily, the material of the light conversion layer can further include a dispersant for dispersing the up-conversion quantum dot material, the dispersant including nanoparticles (e.g., SiO2) and a solvent, and a ratio between a concentration of the up-conversion quantum dot material in the dispersant and a concentration of the nanoparticles in the dispersant ranges from 0.01 to 0.1. Optionally, the ratio between the concentration of the up-conversion quantum dot material in the dispersant and the concentration of the nanoparticles in the dispersant ranges from 0.03 to 0.07. For example, the ratio between the concentration of the up-conversion quantum dot material in the dispersant and the concentration of the nanoparticles in the dispersant is 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, etc., which is not limited herein.

[0015] In some other examples, the material of the light conversion layer can include a down-conversion material. The down-conversion material is configured to convert light having a wavelength less than a minimum wavelength of the second wavelength range into light within the second wavelength range. In this way, the light conversion layer can be capable of absorbing light having a wavelength range including light having a wavelength less than the minimum wavelength of the second wavelength range, and converting the light having a wavelength less than the minimum wavelength of the second wavelength range into light within the second wavelength range. For example, when the second wavelength range is 500 nm to 600 nm, the down-conversion material is configured to convert light having a wavelength less than 500 nm into light within the second wavelength range. Optionally, when the second wavelength range is 500 nm to 600 nm, the down-conversion material can convert light having a wavelength within a range of 200 nm to 500 nm into light within the second wavelength range.

[0016] Exemplarily, the down-conversion material includes, but is not limited to, a down-conversion quantum dot material. Optionally, the down-conversion quantum dot material includes, but is not limited to, at least one of a rare earth ion-containing quantum dot (e.g., but not limited to, Sr2SiO4:Re 2+ ), a vanadate quantum dot, an indium phosphide quantum dot, a zinc sulfide quantum dot, and a perovskite quantum dot (e.g., but not limited to, CsPbBr3). Of course, the material system can be adjusted according to the wavelength conversion requirement, and the application is not limited to the down-conversion material.

[0017] Exemplarily, the material of the light conversion layer can further include a dispersant for dispersing the down-conversion quantum dot material, the dispersant including nanoparticles and a solvent, and a ratio between a concentration of the down-conversion quantum dot material in the dispersant and a concentration of the nanoparticles in the dispersant ranges from 0.01 to 0.1. Alternatively, the ratio between the concentration of the down-conversion quantum dot material in the dispersant and the concentration of the nanoparticles in the dispersant ranges from 0.03 to 0.07. For example, the ratio between the concentration of the down-conversion quantum dot material in the dispersant and the concentration of the nanoparticles in the dispersant is 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, etc., which is not limited herein.

[0018] In yet some examples, the material of the light conversion layer can include both the up-conversion material and the down-conversion material. In this way, the light conversion layer can not only absorb light with a wavelength range including light with a wavelength less than the minimum value of the second wavelength range, but also absorb light with a wavelength range including light with a wavelength greater than the maximum value of the second wavelength range, so as to increase the amount of light with the second wavelength range converted by the light conversion layer, and further increase the amount of light incident into the light absorption conversion layer, reduce light loss, and improve light utilization.

[0019] Exemplarily, the material of the light conversion layer can further include a dispersant for dispersing the quantum dot material (the quantum dot material herein includes the up-conversion quantum dot material and the down-conversion quantum dot material), the dispersant including nanoparticles and a solvent, and a ratio between a concentration of the quantum dot material in the dispersant and a concentration of the nanoparticles in the dispersant ranges from 0.01 to 0.1. Alternatively, the ratio between the concentration of the quantum dot material in the dispersant and the concentration of the nanoparticles in the dispersant ranges from 0.03 to 0.07. For example, the ratio between the concentration of the quantum dot material in the dispersant and the concentration of the nanoparticles in the dispersant is 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, etc., which is not limited herein.

[0020] In some possible implementations, the adjacent distributed Bragg reflection layer and the light conversion layer form a structure group, and the distributed Bragg reflection layer in the same structure group is located on a side of the light conversion layer away from the battery structure; in the same structure group, the wavelength range of the light converted by the light conversion layer is within the wavelength range of the light reflected by the distributed Bragg reflection layer. In this way, the distributed Bragg reflection layer can change the propagation direction of the light converted by the light conversion layer.

[0021] Exemplarily, the wavelength range of the light reflected by the distributed Bragg reflection layer is a third wavelength range. Alternatively, the third wavelength range is within the first wavelength range.

[0022] In some possible implementation manners, the distributed Bragg reflection layer comprises a plurality of first refractive index layers and a plurality of second refractive index layers; the refractive index of the first refractive index layer is greater than the refractive index of the adjacent second refractive index layer; the plurality of first refractive index layers and the plurality of second refractive index layers are arranged alternately, and the distributed Bragg reflection layer is in contact with the light conversion layer through the first refractive index layer. In this way, the distributed Bragg reflection layer can be formed by sequentially arranging the first refractive index layer and the second refractive index layer.

[0023] In some possible implementation manners, the refractive index of each first refractive index layer in the plurality of first refractive index layers in the same distributed Bragg reflection layer is the same. In this way, the design difficulty and the preparation difficulty can be reduced.

[0024] Optionally, the thickness of each first refractive index layer in the plurality of first refractive index layers can be the same. The thickness of the thin film of the first refractive index layer is determined by the central wavelength (for example, the central wavelength in the third wavelength range) of the reflected light and the refractive index, for example, the relationship among the thickness h1, the refractive index n1 and the central wavelength λ0 of the first refractive index layer satisfies h1*n1=λ0 / 4.

[0025] In some possible implementation manners, in the direction from the first transparent substrate to the battery structure, the refractive index of the first refractive index layer in the plurality of first refractive index layers in the same distributed Bragg reflection layer can sequentially increase. Alternatively, in the direction from the first transparent substrate to the battery structure, the refractive index of the first refractive index layer in the plurality of first refractive index layers in the same distributed Bragg reflection layer can sequentially decrease. In this way, the refractive index of different first refractive index layers can be adjusted.

[0026] In some possible implementation manners, the refractive index of each second refractive index layer in the plurality of second refractive index layers in the same distributed Bragg reflection layer is the same. In this way, the design difficulty and the preparation difficulty can be reduced.

[0027] Optionally, the thickness of each second refractive index layer in the plurality of second refractive index layers can be the same. The thickness of the thin film of the second refractive index layer is determined by the central wavelength (for example, the central wavelength in the third wavelength range) of the reflected light and the refractive index, for example, the relationship among the thickness h2, the refractive index n2 and the central wavelength λ0 of the second refractive index layer satisfies h2*n2=λ0 / 4.

[0028] In some possible embodiments, in the direction from the first transparent substrate to the battery structure, the refractive index of the second refractive index layers in the same distributed Bragg reflection layer increases in turn. Alternatively, in the direction from the first transparent substrate to the battery structure, the refractive index of the second refractive index layers in the same distributed Bragg reflection layer decreases in turn. In this way, the refractive index of different second refractive index layers can be adjusted.

[0029] In the embodiments of the present application, the refractive index of each first refractive index layer is the same, and the refractive index of each second refractive index layer is the same, which is used as an example for description. In this way, the distributed Bragg reflection layer can be formed by periodically and alternately arranging two kinds of thin films with different refractive indexes. Moreover, the bandwidth (e.g., the third wavelength range) of the reflected light reflected by the distributed Bragg reflection layer can be determined by the refractive index difference between the materials of the first refractive index layers and the second refractive index layers. For example, the greater the refractive index difference is, the greater the bandwidth of the reflected light is.

[0030] In some possible embodiments, the optical structure comprises one or more distributed Bragg reflection layers and one or more light conversion layers. When the optical structure comprises a plurality of distributed Bragg reflection layers, the wavelength range (i.e., the third wavelength range) of the reflected light corresponding to different distributed Bragg reflection layers can be different.

[0031] Optionally, in the direction from the first transparent substrate to the battery structure, the plurality of distributed Bragg reflection layers are defined as the first distributed Bragg reflection layer to the Qth distributed Bragg reflection layer, and the minimum value of the wavelength range (i.e., the third wavelength range) of the reflected light corresponding to the qth distributed Bragg reflection layer is not greater than the maximum value of the wavelength range (i.e., the third wavelength range) of the reflected light corresponding to the (q+1)th distributed Bragg reflection layer. Q is an integer greater than 1, and q is an integer, 1≤q≤Q.

[0032] For example, the minimum value of the third wavelength range corresponding to the qth distributed Bragg reflection layer is equal to the maximum value of the third wavelength range corresponding to the (q+1)th distributed Bragg reflection layer. For example, when Q=2, the third wavelength range corresponding to the second distributed Bragg reflection layer can be 480nm to 620nm, and the third wavelength range corresponding to the first distributed Bragg reflection layer can be 620nm to 800nm.

[0033] Optionally, the third wavelength ranges corresponding to different distributed Bragg reflection layers do not overlap with each other, i.e., there is no overlapping interval. For example, the third wavelength range corresponding to the second distributed Bragg reflection layer can be 480nm to 620nm, and the third wavelength range corresponding to the first distributed Bragg reflection layer can be 630nm to 800nm.

[0034] Alternatively, the third wavelength ranges corresponding to different distributed Bragg reflection layers can also be not completely identical. That is, the minimum value of the third wavelength range corresponding to the qth distributed Bragg reflection layer can also be less than the maximum value of the third wavelength range corresponding to the q+1th distributed Bragg reflection layer. For example, the third wavelength ranges corresponding to different distributed Bragg reflection layers can have partially overlapping intervals. For example, the third wavelength range corresponding to the 2nd distributed Bragg reflection layer can be 480nm to 620nm, and the third wavelength range corresponding to the 1st distributed Bragg reflection layer can be 600nm to 800nm.

[0035] In some possible embodiments, the light conversion layer is further configured to convert at least part of the wavelengths of the light incident from the side of the optical structure away from the battery structure into light in the first wavelength range. Illustratively, the light conversion layer is further configured to convert light in the fourth wavelength range into light in the second wavelength range. Here, the light in the fourth wavelength range is the light incident from the side of the optical structure away from the battery structure, and the fourth wavelength range is at least part of the wavelengths other than the second wavelength range in the full wavelength range. For example, due to the thickness of the light absorption conversion layer and the band gap width of the material thereof, light L41 is first incident on the light conversion layer, part of which is converted by the light conversion layer into light in the second wavelength range, and the other part of which is incident on the light absorption conversion layer through the light conversion layer. Moreover, light L42 is not directly absorbed by the light absorption conversion layer, and this part of light is also directly incident on the light conversion layer. The light conversion layer also converts the light directly incident thereon into light in the second wavelength range. Thus, the light conversion layer can convert the light incident from the back and not fully absorbed by the thin-film solar cell and outside the absorption wavelength range thereof into light within the absorption wavelength range thereof. Moreover, part of the light converted by the light conversion layer has a propagation direction pointing to the battery structure, and these lights can be re-absorbed by the light absorption conversion layer to improve the output power of the thin-film solar cell. However, part of the light converted by the light conversion layer has a propagation direction away from the battery structure, and these lights can be directly incident on the distributed Bragg reflection layer, and the propagation direction of these lights is changed by the distributed Bragg reflection layer so as to point to the battery structure, thereby being re-absorbed by the light absorption conversion layer to improve the output power of the thin-film solar cell.

[0036] In some possible implementation manners, the thin-film solar cell further includes a second transparent substrate, the optical structure is formed on the second transparent substrate, the cell structure is formed on the first transparent substrate, and the optical structure and the cell structure are bonded by an adhesive material. In this way, the optical structure can be prepared on the second transparent substrate, the cell structure can be prepared on the first transparent substrate, and the optical structure and the cell structure can be bonded by the adhesive material, so that the second transparent substrate on which the optical structure is formed and the first transparent substrate on which the cell structure is formed are bonded by the adhesive material to form the thin-film solar cell.

[0037] In some possible implementation manners, the optical structure can also be directly arranged on the cell structure.

[0038] In a second aspect, an embodiment of the present application provides a photovoltaic module, which can include a housing and the above-described thin-film solar cell provided by the embodiment of the present application, and the thin-film solar cell can be located in the housing. In this way, the thin-film solar cell can be protected by the housing, so that the reliability and safety of the photovoltaic module are improved.

[0039] In addition, the thin-film solar cells arranged in the housing are not limited to one, and there can be multiple thin-film solar cells, and the number of the thin-film solar cells arranged can be set according to actual needs, so that the power generation power of the photovoltaic module is improved.

[0040] In addition, the electrical connection relationship of each thin-film solar cell can be set as parallel connection, series connection, or a combination of series connection and parallel connection, and the electrical connection relationship of each thin-film solar cell can be set according to actual needs, which is not limited herein.

[0041] In addition, the cell structure in each thin-film solar cell includes multiple cell structures, and the multiple cell structures are connected in series. For example, for two adjacent cell structures, the first conductive layer of one of the two cell structures is connected to the second conductive layer of the other cell structure through a connecting part. In addition, the first conductive layers of different cell structures are provided with insulating materials, and the second conductive layers of different cell structures are also provided with insulating materials. In addition, for the connecting part and the cell structure in which the second conductive layer connected to the connecting part is located, the connecting part is also provided with insulating materials between the connecting part and the remaining film layers of the cell structure except the second conductive layer, so as to achieve the insulating effect.

[0042] In a third aspect, an embodiment of the present application provides a power generation device, which includes the above-described photovoltaic module provided by the embodiment of the present application and an inverter electrically connected to the photovoltaic module. Through the inverter, the direct-current signal output by the photovoltaic module can be converted into an alternating-current signal, and then the converted alternating-current signal can be integrated into a power grid for use.

[0043] The number of photovoltaic assemblies included in the power generation device is not limited to two, and can be one or more, which can be set according to actual needs, and is not limited herein.

[0044] In the embodiment of the present application, when a plurality of photovoltaic assemblies are provided, a plurality of inverters can be provided, and the photovoltaic assemblies and the inverters are one-to-one correspondingly arranged, so that the inverter converts and processes the direct current signal output by the corresponding photovoltaic assembly, thereby improving the conversion accuracy.

[0045] Of course, when a plurality of photovoltaic assemblies are provided, one inverter can be provided, and no diagram is given. At this time, the inverter is electrically connected to each photovoltaic assembly. At this time, the inverter can convert and process the direct current signal output by each photovoltaic assembly, thereby reducing the number of inverters and reducing the manufacturing cost of the power generation device.

[0046] In the embodiment of the present application, in addition to the photovoltaic assembly and the inverter, the power generation device can also include other structures that can be used to realize the function of the power generation device, which is not limited herein.

[0047] In a fourth aspect, the embodiment of the present application provides a preparation method of a thin-film solar cell, which can include: forming a cell structure on a first transparent substrate; the cell structure is used to absorb light in a first wavelength range; forming an optical structure on the cell structure; the optical structure includes: at least one light conversion layer and at least one distributed Bragg reflection layer arranged alternately; the film layer farthest from the cell structure in the optical structure is the distributed Bragg reflection layer; the light conversion layer is used to convert the light incident thereon after passing through the cell structure into light in the first wavelength range; and the distributed Bragg reflection layer is used to reflect the light incident thereon, so that the propagation direction of the reflected light is directed to the cell structure.

[0048] In some possible implementations, the optical structure can be directly formed on the cell structure. In some examples, the forming the optical structure on the cell structure can include: using a thin-film preparation process to form at least one light conversion layer and at least one distributed Bragg reflection layer arranged alternately on the cell structure to form the optical structure.

[0049] For example, taking the material of the light conversion layer as the up-conversion quantum dot material, the process of forming the light conversion layer includes but is not limited to: first, mixing the up-conversion quantum dot material NaYF4:Yb 3+ :Er 3A SiO2 nanoparticle dispersion solution (solvent: cyclohexane) of quantum dots (average size: 20 nm) is added dropwise to the surface of the second conductive layer of the battery structure. The ratio between the concentration of the upconversion quantum dot material in the dispersant and the concentration of the nanoparticles in the dispersant is 0.05, i.e., the ratio between the concentration of the upconversion quantum dot material in the dispersant and the concentration of the SiO2 nanoparticles in the dispersant is 1:20. Then, a spin coating or a blade coating method is used to form a light conversion layer film. Then, a hot stage including but not limited to a temperature of 150°C is used to cure the light conversion layer film.

[0050] The process of forming the distributed Bragg reflection layer includes but is not limited to: first, a first refractive index layer is formed on the first transparent substrate by using a SiO2 solution through a method including but not limited to a plasma-enhanced chemical vapor deposition method, a magnetron sputtering method, a spin coating method, or a blade coating method. Then, a second refractive index layer is formed on the first refractive index layer by using a SiN x solution through a method including but not limited to a plasma-enhanced chemical vapor deposition method, a magnetron sputtering method, a spin coating method, or a blade coating method. Then, the process of preparing the first refractive index layer and the second refractive index layer is repeated to form the first refractive index layer and the second refractive index layer that appear in turn to form a structure of SiO2 / SiN x / SiO2 / SiN x ……SiO2 / SiN x , forming the distributed Bragg reflection layer. The thickness of the first refractive index layer and the second refractive index layer is determined according to the central wavelength of the reflected light and the corresponding refractive index.

[0051] In some possible embodiments, the optical structure can also be formed on the second transparent substrate. In some examples, before the battery structure is formed on the second transparent substrate, the process further includes: forming at least one light conversion layer and at least one distributed Bragg reflection layer arranged alternately on the second transparent substrate by using a thin film preparation process to form the optical structure. And the process of forming the optical structure on the battery structure includes: using an adhesive material to bond the side surface of the second transparent substrate with the optical structure to the side surface of the first transparent substrate with the battery structure.

[0052] For example, the material of the light conversion layer is an upconversion quantum dot material, and the process of forming the light conversion layer includes but is not limited to: first, a mixture of the upconversion quantum dot material: NaYF4:Yb 3+ :Er 3+A SiO2 nanoparticle dispersion solution (solvent: cyclohexane) of quantum dots (average size: 20 nm) is dropped on the surface of the corresponding film layer. The ratio between the concentration of the up-conversion quantum dot material in the dispersant and the concentration of the nanoparticles in the dispersant is 0.05, i.e. the ratio between the concentration of the up-conversion quantum dot material in the dispersant and the concentration of the SiO2 nanoparticles in the dispersant is 1:20. Then, a spin coating or a blade coating method is used to form a light conversion layer film. Then, a hot stage including but not limited to a temperature of 150°C is used to cure the light conversion layer film.

[0053] The process of forming the distributed Bragg reflection layer includes but is not limited to: first, using SiN x The solution forms a second refractive index layer. Then, using a SiO2 solution, a first refractive index layer is formed by a plasma enhanced chemical vapor deposition method, a magnetron sputtering method, a spin coating method or a blade coating method. Then, the process of preparing the first refractive index layer and the second refractive index layer is repeated to form the first refractive index layer and the second refractive index layer that appear in turn, so that the structure of SiO2 / SiN x / SiO2 / SiN x ……SiO2 / SiN x appears, forming a distributed Bragg reflection layer. The thickness of the first refractive index layer and the second refractive index layer is determined according to the central wavelength of the reflected light and the corresponding refractive index. BRIEF DESCRIPTION OF DRAWINGS

[0054] Figure 1 is a schematic diagram of the structure of a thin-film solar cell in the prior art;

[0055] Figure 2 is a schematic diagram of the structure of another thin-film solar cell in the prior art;

[0056] Figure 3 is a schematic diagram of the structure of a thin-film solar cell in the prior art;

[0057] Figure 4 is a schematic diagram of the wavelength range corresponding to the light conversion layer and the distributed Bragg reflection layer in the embodiment of the present application;

[0058] Figure 5 is a schematic diagram of the structure of a thin-film solar cell in the embodiment of the present application;

[0059] Figure 6 is a flowchart of the preparation method of a thin-film solar cell in the embodiment of the present application;

[0060] Figure 7Structure diagram of another thin-film solar cell in the embodiment of the present application;

[0061] Figure 8 Structure diagram of another thin-film solar cell in the embodiment of the present application;

[0062] Figure 9 Structure diagram of another thin-film solar cell in the embodiment of the present application;

[0063] Figure 10 Structure diagram of another thin-film solar cell in the embodiment of the present application;

[0064] Figure 11 Structure diagram of a photovoltaic module in the embodiment of the present application;

[0065] Figure 12 Structure diagram of another photovoltaic module in the embodiment of the present application;

[0066] Figure 13 Structure diagram of another photovoltaic module in the embodiment of the present application;

[0067] Figure 14 Structure diagram of a power generation device in the embodiment of the present application.

[0068] Reference signs:

[0069] 1 - transparent substrate; 2 - first transparent electrode; 3 / 22 - first charge transport layer; 4 / 23 - light absorption conversion layer; 5 / 24 - second charge transport layer; 6 - second transparent electrode; 10 - first transparent substrate; 20 - cell structure; 30 - optical structure; 21 - first conductive layer; 25 - second conductive layer; 31 - light conversion layer; 32 / 33 - distributed Bragg reflection layer; 40 - second transparent substrate; 50 - adhesive material; 60 - insulating material; 70 - connecting portion; 100 - photovoltaic module; 200 - inverter; 300 - power grid; 321 -1 / 321 -2 / 321 -N / 331 -1 / 331 -2 / 331 -N - first refractive index layer; 322 -1 / 322 -2 / 322 -N / 332 -1 / 332 -2 / 332 -N - second refractive index layer; L11 - light in the absorbable wavelength band in front incident light; L12 - light in the non-absorbable wavelength band in front incident light; L21 - light in the absorbable wavelength band in back incident light; L22 - light in the non-absorbable wavelength band in back incident light; L31 - light in the first wavelength range in front incident light; L32 - light out of the first wavelength range in front incident light; L41 - light in the first wavelength range in back incident light, L42 - light out of the first wavelength range in back incident light; F1 / F2 - incident direction. DETAILED DESCRIPTION

[0070] In order to make the purposes, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings.

[0071] It should be noted that the same reference signs in the drawings of the present application represent the same or similar structures, and thus repeated descriptions thereof will be omitted. The expressions of position and direction described in the present application are described with reference to the drawings, but changes can also be made as needed, and the changes made are included in the protection scope of the present application. The drawings of the present application are only used to show the relative position relationship and do not represent the true proportion.

[0072] The embodiments of the present application provide a thin-film solar cell, a preparation method thereof, a photovoltaic module and a power generation device. The thin-film solar cell, the photovoltaic module and the power generation device can be applied to various scenes in which the solar cell can be applied, such as ground power stations and building integrated photovoltaics. Moreover, since the embodiments of the present application aim to improve the output power of the thin-film solar cell, the performance of the photovoltaic module and the power generation device formed by using the thin-film solar cell in the embodiments of the present application will also be better.

[0073] For the convenience of understanding, the wavelength of light mentioned in the present application refers to the wavelength of light in a vacuum.

[0074] Figure 1 An example of a structure of a thin-film solar cell in the prior art is shown. Figure 2 Another example of a structure of a thin-film solar cell in the prior art is shown.

[0075] Reference Figure 1 With Figure 2 In the prior art, a double-sided thin-film solar cell generally comprises a first transparent electrode 2, a first charge transport layer 3, a light absorption conversion layer 4, a second charge transport layer 5 and a second transparent electrode 6 which are sequentially arranged on a transparent substrate 1. Among them, L11 represents light in the absorbable wave band in the front incident light, L12 represents light in the non-absorbable wave band in the front incident light, L11 and L12 are incident from one side of the transparent substrate 1 (such as the direction indicated by the arrow F1 in Figure 1 ), the light absorption conversion layer 4 generates electron-hole pairs after absorbing L11, forms photo-generated carriers, and thus generates photo-generated current. L21 represents light in the absorbable wave band in the back incident light, L22 represents light in the non-absorbable wave band in the back incident light, L21 and L22 are incident from one side of the second transparent electrode 6 (such as the direction indicated by the arrow F2 in Figure 1 ), the light absorption conversion layer 4 also generates electron-hole pairs after absorbing L21, forms photo-generated carriers, and also generates photo-generated current.

[0076] However, referring to Figure 1 , since both the front side and the back side of the bifacial thin-film solar cell are transparent electrodes, when the thickness of the light absorption conversion layer 4 is low, there is a case where the light in the absorption bands L11 and L21 (especially long-wavelength light) cannot be fully absorbed, resulting in light waste. Moreover, due to the factor of the band gap width of the light absorption conversion layer material, there is also a case where L12 and L22 (such as longer-wavelength light) cannot be fully utilized. There is a large amount of longer-wavelength light in the front-side incident light and the back-side incident light. If these wasted lights can be fully utilized, the output power of the bifacial thin-film solar cell can be effectively improved.

[0077] In order to fully utilize the light, referring to Figure 2 , the main method at present is to increase the thickness of the light absorption conversion layer 4, which means that the optical path of the incident light in the light absorption conversion layer 4 is increased, which is beneficial to the full absorption of light. However, due to the increase of the thickness of the light absorption conversion layer 4, the transport distance of the photo-generated carriers is increased, which has a higher requirement for the film quality of the light absorption conversion layer 4 and a higher requirement for the diffusion length of the carriers. When the film quality of the light absorption conversion layer 4 is poor, especially the crystallinity is poor, there are a large number of charge traps caused by defects in the light absorption conversion layer 4 film, which causes the diffusion distance of the carriers to decrease, which is not conducive to improving the output power of the cell, and further causes the overall performance of the cell to decrease.

[0078] Moreover, increasing the thickness of the light absorption conversion layer 4 does not change the band gap of the material, so the light with longer wavelength cannot be absorbed and utilized, and there is still a large amount of light waste, which is not conducive to improving the output power of the cell, and further causes the overall performance of the cell to decrease.

[0079] The embodiment of the present application provides a thin-film solar cell, which can improve the optical utilization rate of incident light and improve the overall output power of the thin-film solar cell.

[0080] Figure 3 An exemplary structure schematic diagram of a thin-film solar cell in the embodiment of the present application is shown.

[0081] Referring to Figure 3 , the thin-film solar cell in the embodiment of the present application comprises a first transparent substrate 10, a cell structure 20 located on the first transparent substrate 10, and an optical structure 30 located on the cell structure 20. The cell structure 20 is used to absorb light in a first wavelength range and generate electron-hole pairs through the absorbed light to form photo-generated carriers and generate photo-generated current. That is, the light in the first wavelength range is light within the absorbable band of the cell structure 20.

[0082] Exemplarily, the first transparent substrate 10 can include a glass substrate. Of course, the first transparent substrate 10 can also be provided as other transparent substrates, which are not limited herein.

[0083] Exemplarily, referring to Figure 3 , the battery structure 20 includes: a first conductive layer 21, a first charge transport layer 22, a light absorption conversion layer 23, a second charge transport layer 24 and a second conductive layer 25 which are sequentially arranged on the first transparent substrate 10. Optionally, the materials of the first conductive layer 21 and the second conductive layer 25 can be both provided as transparent conductive materials, and then the thin-film solar cell in the embodiment of the present application can include a double-sided thin-film solar cell. Wherein, L31 represents light within the first wavelength range in the front incident light, L32 represents light outside the first wavelength range in the front incident light, L31 and L32 are incident from one side of the first conductive layer 21 (such as the direction indicated by the arrow F1 in Figure 3 , the incident direction of L31 and L32), the light absorption conversion layer 23 generates electron-hole pairs after absorbing L31, forms photo-generated carriers, and thus generates photo-generated current. L41 represents light within the first wavelength range in the back incident light, L42 represents light outside the first wavelength range in the back incident light, L41 and L42 are incident from one side of the second conductive layer 25 (such as the direction indicated by the arrow F2 in Figure 3 , the incident direction of L41 and L42), the light absorption conversion layer 23 also generates electron-hole pairs after absorbing L41, forms photo-generated carriers, and also generates photo-generated current.

[0084] Exemplarily, the optical structure 30 is directly arranged on the battery structure 20, that is, the optical structure 30 is directly formed on the battery structure 20 and is not connected through an adhesive material. Optionally, the optical structure 30 includes: one or more light conversion layers and one or more distributed Bragg reflection layers, and the light conversion layers and the distributed Bragg reflection layers are sequentially and alternately arranged. Figure 3 Taking the optical structure 30 including one light conversion layer and one distributed Bragg reflection layer as an example.

[0085] Exemplarily, referring to Figure 3 , the optical structure 30 includes: a light conversion layer 31 and a distributed Bragg reflection layer 32. Wherein, the light conversion layer 31 is located between the distributed Bragg reflection layer 32 and the second conductive layer 25, and the distributed Bragg reflection layer 32 is the farthest film layer from the battery structure 20 in the optical structure 30. Wherein, the light conversion layer 31 is used to convert the light incident thereon after passing through the battery structure 20 into light within the first wavelength range, and the distributed Bragg reflection layer 32 is used to reflect the light incident thereon, so that the propagation direction of the reflected light is directed to the battery structure 20.

[0086] Optionally, the light conversion layer 31 and the DBR layer 32 can be combined as one structure group, and the wavelength range of the light converted by the light conversion layer 31 is within the wavelength range of the light reflected by the DBR layer 32. For example, the light conversion layer 31 is used to convert the light incident on it after passing through the battery structure 20 into light within a second wavelength range, and the DBR layer 32 is used to reflect light within a third wavelength range, so that the propagation direction of the reflected light is directed towards the battery structure 20. Moreover, the second wavelength range and the third wavelength range are both within the first wavelength range, and the second wavelength range corresponding to the light conversion layer 31 is within the third wavelength range corresponding to the DBR layer 32.

[0087] With reference to Figure 3 Due to the thickness of the light absorption conversion layer 23 and the band gap width of its material, the light L31 can not be fully absorbed by the light absorption conversion layer 23 (for example, the light in the long-wave band of the first wavelength can not be fully absorbed by the light absorption conversion layer 23), so a part of the light (for example, the light in the long-wave band of the first wavelength) can be incident on the light conversion layer 31 after passing through the battery structure 20. Moreover, the light L32 is not directly absorbed by the light absorption conversion layer 23, and this part of light is also incident on the light conversion layer 31 after passing through the battery structure 20. The light conversion layer 31 converts the light incident on it after passing through the battery structure 20 into light within a second wavelength range. Since the second wavelength range is within the first wavelength range, i.e., the light converted by the light conversion layer 31 can be absorbed by the light absorption conversion layer 23, the light conversion layer 31 can convert the light incident on the front surface and not fully absorbed by the thin-film solar cell and outside the absorbable wavelength range of the thin-film solar cell into light within the absorbable wavelength range. Moreover, a part of the light converted by the light conversion layer 31 has a propagation direction directed towards the battery structure 20, and these lights directed towards the battery structure 20 can be reabsorbed by the light absorption conversion layer 23 to improve the output power of the thin-film solar cell. However, a part of the light converted by the light conversion layer 31 has a propagation direction away from the battery structure 20, and these lights away from the battery structure 20 can be directly incident on the DBR layer 32, and the propagation direction of these lights is changed by the DBR layer 32, so that the propagation direction of these lights is directed towards the battery structure 20, thereby being reabsorbed by the light absorption conversion layer 23, further improving the output power of the thin-film solar cell.

[0088] The embodiment of the present application provides a thin-film solar cell. The optical structure is arranged on the back of the thin-film solar cell, the optical structure comprises alternately arranged light conversion layers and distributed Bragg reflection layers, the light conversion layer can convert light which is not fully absorbed by the thin-film solar cell and is outside the absorbable wave band of the thin-film solar cell into light within the absorbable wave band, and the transmission direction of the light converted by the light conversion layer is adjusted through the distributed Bragg reflection layer, so that the thin-film solar cell is absorbed, the optical utilization rate of incident light of the thin-film solar cell is improved, the utilization rate of light outside the absorbable wave band of the thin-film solar cell is improved, and the overall output power of the thin-film solar cell is improved.

[0089] In the embodiment of the present application, the thin-film solar cell can be any one of a cadmium telluride cell, a copper indium gallium selenide cell, a perovskite cell or an organic solar cell, as long as the thin-film solar cell comprises a light absorption conversion layer, and the light absorption conversion layer generates an electron-hole pair after absorbing light to generate current, which belongs to the protection scope of the present application.

[0090] In the embodiment of the present application, the light conversion layer is further used to convert at least part of the wavelength of the light incident from the side of the optical structure away from the cell structure into light within the first wavelength range. Exemplarily, the light conversion layer 31 is further used to convert light within the fourth wavelength range into light within the second wavelength range. The light within the fourth wavelength range is light incident from the side of the optical structure 30 away from the cell structure 20, and the fourth wavelength range is at least part of the wavelengths in the full wavelength range except the second wavelength range. Refer to Figure 3 Due to the thickness of the light absorption conversion layer 4 and the band gap width of the material, the light L41 is first incident on the light conversion layer 31, part of the light is converted by the light conversion layer 31 into light within the second wavelength range, and the other part of the light is incident on the light absorption conversion layer 23 through the light conversion layer 31. Moreover, the light L42 is not directly absorbed by the light absorption conversion layer 23, and this part of the light is also directly incident on the light conversion layer 31. The light conversion layer 31 also converts the light directly incident thereon into light within the second wavelength range. Then, the light conversion layer 31 can convert the light incident from the back and not fully absorbed by the thin-film solar cell and outside the absorbable wave band of the thin-film solar cell into light within the absorbable wave band. Moreover, part of the light converted by the light conversion layer 31 has a propagation direction pointing to the cell structure 20, and these lights pointing to the cell structure 20 can be re-absorbed by the light absorption conversion layer 23 to improve the output power of the thin-film solar cell. However, part of the light converted by the light conversion layer 31 has a propagation direction away from the cell structure 20, and these lights away from the cell structure 20 can be directly incident on the distributed Bragg reflection layer 32, the propagation direction of these lights is changed through the action of the distributed Bragg reflection layer 32, so that the propagation direction of these lights points to the cell structure 20, and then these lights are re-absorbed by the light absorption conversion layer 23 to improve the output power of the thin-film solar cell.

[0091] The thin film solar cell provided by the embodiment of the present application can be set as a double-sided thin film solar cell. The embodiment of the present application mainly aims at the optical loss of the double-sided thin film solar cell, and proposes an optical structure composed of a light conversion layer and a distributed Bragg reflector on the back of the double-sided thin film solar cell to improve the optical utilization of the directly incident light and the utilization of the light of the wavelength outside the absorbable wavelength. The light of the wavelength will be converted into the light that can be absorbed by the double-sided thin film solar cell after passing through the light conversion layer, and the transmission direction of the light is adjusted through the distributed Bragg reflector, thereby improving the overall output power of the double-sided thin film solar cell.

[0092] Optionally, the wavelength range of the light converted by the light conversion layer 31 can be the same as the first wavelength range, that is, the second wavelength range corresponding to the light conversion layer 31 is the same as the first wavelength range. Alternatively, the wavelength range of the light converted by the light conversion layer 31 can also be within the first wavelength range, that is, the first wavelength range contains the second wavelength range corresponding to the light conversion layer 31. For example, the first wavelength range can be 400nm to 800nm, the second wavelength range corresponding to the light conversion layer 31 can be 500nm to 600nm, or the second wavelength range corresponding to the light conversion layer 31 can also be 480nm to 700nm. Of course, in actual application, the first wavelength range and the second wavelength range can be determined according to the actual application requirements, and the present application does not make any limitation in this regard.

[0093] Optionally, Figure 4 An exemplary diagram of the wavelength range corresponding to the light conversion layer and the distributed Bragg reflector in the embodiment of the present application is shown. Referring to Figure 4 , the second wavelength range corresponding to the light conversion layer 31 (such as the range of the emitted light shown by the solid curve in Figure 4 ) is located in the third wavelength range corresponding to the distributed Bragg reflector 32 (such as the range of the emitted light shown by the dashed curve in Figure 4The third wavelength range corresponding to the distributed Bragg reflector layer 32 is located within the first wavelength range. For example, when the second wavelength range corresponding to the light conversion layer 31 is the same as the first wavelength range, the third wavelength range corresponding to the distributed Bragg reflector layer 32 can be the same as the first wavelength range. Alternatively, when the first wavelength range contains the second wavelength range corresponding to the light conversion layer 31, the third wavelength range corresponding to the distributed Bragg reflector layer 32 can contain the second wavelength range corresponding to the light conversion layer 31. For example, the first wavelength range can be 400 nm to 800 nm, the second wavelength range corresponding to the light conversion layer 31 can be 500 nm to 600 nm, and the third wavelength range corresponding to the distributed Bragg reflector layer 32 can be 480 nm to 620 nm. Of course, in actual applications, the first wavelength range, the second wavelength range, and the third wavelength range can be determined according to the requirements of actual applications, and the present application does not limit this.

[0094] In some examples, the material of the light conversion layer can include up-conversion material. The up-conversion material is used to convert light with a wavelength greater than the maximum wavelength of the second wavelength range into light within the second wavelength range. In this way, the wavelength range of light that can be absorbed by the light conversion layer can include light with a wavelength greater than the maximum wavelength of the second wavelength range, so as to convert light with a wavelength greater than the maximum wavelength of the second wavelength range into light within the second wavelength range. For example, referring to Figure 4 , when the second wavelength range is 500 nm to 600 nm, the up-conversion material is used to convert light with a wavelength greater than 600 nm into light within the second wavelength range. Alternatively, referring to Figure 4 , when the second wavelength range is 500 nm to 600 nm, the up-conversion material can convert light within a wavelength range of 600 nm to 1100 nm into light within the second wavelength range.

[0095] For example, the up-conversion material includes but is not limited to up-conversion quantum dot material. Alternatively, the up-conversion quantum dot material includes but is not limited to: NaYF4:Yb 3+ :Er 3+ quantum dot material (for example, with an average size of 20 nm), and the like, which can also be a combination of multiple materials, and the material system is adjusted according to the wavelength conversion requirements, and the present application does not limit the up-conversion material.

[0096] Exemplarily, the material of the light conversion layer can further include a dispersant for dispersing the up-conversion quantum dot material, the dispersant including nanoparticles (e.g., SiO2) and a solvent, and a ratio between a concentration of the up-conversion quantum dot material in the dispersant and a concentration of the nanoparticles in the dispersant ranges from 0.01 to 0.1. Optionally, the ratio between the concentration of the up-conversion quantum dot material in the dispersant and the concentration of the nanoparticles in the dispersant ranges from 0.03 to 0.07. For example, the ratio between the concentration of the up-conversion quantum dot material in the dispersant and the concentration of the nanoparticles in the dispersant is 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, etc., which is not limited herein.

[0097] In some other examples, the material of the light conversion layer can include a down-conversion material. The down-conversion material is configured to convert light having a wavelength less than a minimum wavelength of the second wavelength range into light within the second wavelength range. In this way, the light conversion layer can be capable of absorbing light having a wavelength range including light having a wavelength less than the minimum wavelength of the second wavelength range, and converting the light having a wavelength less than the minimum wavelength of the second wavelength range into light within the second wavelength range. For example, referring to Figure 4 , when the second wavelength range is 500 nm to 600 nm, the down-conversion material is configured to convert light having a wavelength less than 500 nm into light within the second wavelength range. Optionally, referring to Figure 4 , when the second wavelength range is 500 nm to 600 nm, the down-conversion material can convert light having a wavelength within a range of 200 nm to 500 nm into light within the second wavelength range.

[0098] Exemplarily, the down-conversion material includes, but is not limited to, a down-conversion quantum dot material. Optionally, the down-conversion quantum dot material includes, but is not limited to, at least one of a rare earth ion-containing quantum dot (e.g., but not limited to, Sr2SiO4:Re 2+ ), a vanadate quantum dot, an indium phosphide quantum dot, a zinc sulfide quantum dot, and a perovskite quantum dot (e.g., but not limited to, CsPbBr3). Of course, the material system can be adjusted according to the wavelength conversion requirement, and the application is not limited to the down-conversion material.

[0099] Exemplarily, the material of the light conversion layer can further include a dispersant for dispersing the down-conversion quantum dot material, the dispersant including nanoparticles and a solvent, and a ratio between a concentration of the down-conversion quantum dot material in the dispersant and a concentration of the nanoparticles in the dispersant ranges from 0.01 to 0.1. Alternatively, the ratio between the concentration of the down-conversion quantum dot material in the dispersant and the concentration of the nanoparticles in the dispersant ranges from 0.03 to 0.07. For example, the ratio between the concentration of the down-conversion quantum dot material in the dispersant and the concentration of the nanoparticles in the dispersant is 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, etc., which is not limited herein.

[0100] In yet some examples, the material of the light conversion layer can include both the up-conversion material and the down-conversion material. In this way, the wavelength range of the light that can be absorbed by the light conversion layer can include light with a wavelength less than the minimum value of the second wavelength range and light with a wavelength greater than the maximum value of the second wavelength range, thereby increasing the amount of light in the second wavelength range converted, and further increasing the amount of light incident into the light absorption conversion layer, reducing light loss, and improving light utilization.

[0101] Exemplarily, the material of the light conversion layer can further include a dispersant for dispersing the quantum dot material (the quantum dot material herein includes the up-conversion quantum dot material and the down-conversion quantum dot material), the dispersant including nanoparticles and a solvent, and a ratio between a concentration of the quantum dot material in the dispersant and a concentration of the nanoparticles in the dispersant ranges from 0.01 to 0.1. Alternatively, the ratio between the concentration of the quantum dot material in the dispersant and the concentration of the nanoparticles in the dispersant ranges from 0.03 to 0.07. For example, the ratio between the concentration of the quantum dot material in the dispersant and the concentration of the nanoparticles in the dispersant is 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, etc., which is not limited herein.

[0102] Figure 5 Exemplarily, a specific structure schematic diagram of a thin-film solar cell in an embodiment of the present application is shown. Refer to Figure 5The distributed Bragg reflector layer 32 includes a plurality of first refractive index layers 321-1 to 321-N and a plurality of second refractive index layers 322-1 to 322-N. The number of the first refractive index layers is the same as the number of the second refractive index layers. The plurality of first refractive index layers 321-1 to 321-N and the plurality of second refractive index layers 322-1 to 322-N are arranged alternately. That is, the first refractive index layer 321-1 is in direct contact with the light conversion layer 31. The second refractive index layer 322-1 is on the first refractive index layer 321-1. The first refractive index layer 321-2 is on the second refractive index layer 322-1. The rest is similar and will not be repeated here.

[0103] In addition, the refractive index of the first refractive index layer is greater than the refractive index of the second refractive index layer adjacent to the first refractive index layer. For example, the refractive index of the first refractive index layer 321-2 is greater than the refractive index of the second refractive index layer 322-1 and the refractive index of the second refractive index layer 322-2. The rest is similar and will not be repeated here. In this way, the distributed Bragg reflector layer 32 can be formed by repeatedly arranging the first refractive index layer and the second refractive index layer.

[0104] The specific value of N is not limited in the present application, which can be determined according to the actual application requirements.

[0105] In some examples, the refractive index of each of the plurality of first refractive index layers in the same distributed Bragg reflector layer is the same. In this way, the design difficulty and the preparation difficulty can be reduced.

[0106] Optionally, the thickness of each of the plurality of first refractive index layers can be the same. The thickness of the thin film of the first refractive index layer is determined by the center wavelength (such as the center wavelength in the third wavelength range) of the reflected light and the refractive index. For example, the relationship between the thickness h1, the refractive index n1 and the center wavelength λ0 of the first refractive index layer satisfies the relationship: h1*n1 = λ0 / 4.

[0107] In other examples, in the direction from the first transparent substrate 10 to the battery structure 20 (such as the direction indicated by the arrow of F1), the refractive index of the first refractive index layer in the same distributed Bragg reflector layer can increase in turn. Alternatively, in the direction from the first transparent substrate 10 to the battery structure 20 (such as the direction indicated by the arrow of F1), the refractive index of the first refractive index layer in the same distributed Bragg reflector layer can decrease in turn. In this way, the refractive index of different first refractive index layers can be adjusted.

[0108] In some examples, the refractive index of each of the plurality of second refractive index layers in the same distributed Bragg reflector layer is the same. In this way, the design difficulty and the preparation difficulty can be reduced.

[0109] Optionally, the thickness of each of the plurality of second refractive index layers can be the same. The thickness of the thin film of the second refractive index layer is determined by the center wavelength of the reflected light (e.g., the center wavelength in the third wavelength range) and the refractive index thereof, for example, the thickness h2, the refractive index n2, and the center wavelength λ0 of the second refractive index layer satisfy the relationship: h2*n2=λ0 / 4.

[0110] In some examples, in the direction from the first transparent substrate 10 to the battery structure 20 (e.g., the direction indicated by the arrow of F1), the refractive index of the second refractive index layers in the same distributed Bragg reflection layer increases in turn. Alternatively, in the direction from the first transparent substrate 10 to the battery structure 20 (e.g., the direction indicated by the arrow of F1), the refractive index of the second refractive index layers in the same distributed Bragg reflection layer decreases in turn. In this way, the refractive index of different second refractive index layers can be adjusted.

[0111] In the embodiments of the present application, the refractive index of each first refractive index layer is the same, and the refractive index of each second refractive index layer is the same, which is used as an example for illustration. In this way, the distributed Bragg reflection layer can be formed by periodically alternating two different refractive index thin films. Moreover, the bandwidth (e.g., the third wavelength range) of the reflected light of the distributed Bragg reflection layer can be determined by the refractive index difference of the materials of the first refractive index layer and the second refractive index layer. For example, the greater the refractive index difference, the greater the bandwidth of the reflected light.

[0112] Figure 6 An example of a flowchart of a method for manufacturing a thin-film solar cell in the embodiments of the present application is shown. Referring to Figure 6 The method for manufacturing a thin-film solar cell provided in the embodiments of the present application includes:

[0113] S10, forming a battery structure on a first transparent substrate. The battery structure is used to absorb light in a first wavelength range.

[0114] In some examples, referring to Figure 5 The existing manufacturing method can be used to sequentially form the first conductive layer 21, the first charge transport layer 22, the light absorption conversion layer 23, the second charge transport layer 24, and the second conductive layer 25 on the first transparent substrate 10.

[0115] Optionally, the first conductive layer 21 and the second conductive layer 25 can be both transparent conductive materials. For example, the transparent conductive material can be a transparent conductive oxide (TCO), and optionally, the transparent conductive material can be indium tin oxide (ITO). The present application does not limit the specific material of the transparent conductive material, which can be determined according to the actual application requirements, and is not limited herein.

[0116] In the embodiments of the present application, the thin-film solar cell can be any one of a cadmium telluride cell, a copper indium gallium selenide cell, a perovskite cell, or an organic solar cell, and the material of the light absorption conversion layer can be selected according to the specific application form of the thin-film solar cell, and is not limited herein.

[0117] S20, forming an optical structure on the battery structure. The optical structure includes at least one light conversion layer and at least one distributed Bragg reflector layer arranged alternately. The film layer farthest from the battery structure in the optical structure is the distributed Bragg reflector layer. The thin film preparation process can be used to form the optical structure by forming at least one light conversion layer and at least one distributed Bragg reflector layer arranged alternately on the battery structure.

[0118] In some examples, taking the light conversion layer including the up-conversion quantum dot material as an example, step S20 includes:

[0119] First, referring to Figure 5 , the thin film preparation process is used to form the light conversion layer 31 on the surface of the second conductive layer 25 using the up-conversion quantum dot material. For example, first, the SiO2 nanoparticle dispersion liquid (solvent: cyclohexane) mixed with the up-conversion quantum dot material: NaYF4:Yb 3+ :Er 3+ quantum dots (average size: 20 nm) is added dropwise to the surface of the second conductive layer 25. The ratio between the concentration of the up-conversion quantum dot material in the dispersant and the concentration of the nanoparticles in the dispersant is 0.05, that is, the ratio of the concentration of the up-conversion quantum dot material in the dispersant to the concentration of the SiO2 nanoparticles in the dispersant is 1:20. Then, the light conversion layer film is formed by spin coating or blade coating and the like. Then, the light conversion layer film is cured by a temperature hot stage including but not limited to 150°C.

[0120] Then, referring to Figure 5The distributed Bragg reflector 32 is formed on the light conversion layer 31 by using a thin film preparation process. For example, first, a first refractive index layer 321-1 is formed on the light conversion layer 31 by using a SiO2solution through a plasma enhanced chemical vapor deposition method, a magnetron sputtering method, spin coating or blade coating, etc. Then, a second refractive index layer 322-1 is formed on the first refractive index layer 321-1 by using a SiN solution through a plasma enhanced chemical vapor deposition method, a magnetron sputtering method, spin coating or blade coating, etc. Then, the process of forming the first refractive index layer 321-1 and the second refractive index layer 322-1 is repeated to form the first refractive index layer and the second refractive index layer which appear alternately to form a structure of SiO2 / SiN x / SiO2 / SiN x / SiO2 / SiN x ……SiO2 / SiN x , and the distributed Bragg reflector 32 is formed. The thickness of the first refractive index layer and the second refractive index layer is determined according to the central wavelength of the reflected light and the corresponding refractive index.

[0121] Figure 7 Another structure of a thin film solar cell in the embodiment of the present application is exemplarily shown. Figure 8 Another structure of a thin film solar cell in the embodiment of the present application is exemplarily shown.

[0122] Referring to Figure 7 and Figure 8 , in the embodiment, the thin film solar cell comprises a first transparent substrate 10, a cell structure 20 on the first transparent substrate 10, and an optical structure 30 on the cell structure 20. The embodiment is a variation of the implementation in the above embodiment. Only the difference between the embodiment and the above embodiment is described below, and the same parts are not described herein.

[0123] In the embodiment of the present application, referring to Figure 7 and Figure 8 , the optical structure 30 comprises a distributed Bragg reflector 33, a light conversion layer 31, and a distributed Bragg reflector 32. The distributed Bragg reflector 33 directly contacts the second conductive layer 25, and the light conversion layer 31 is between the distributed Bragg reflector 33 and the distributed Bragg reflector 32.

[0124] For example, the third wavelength range corresponding to the distributed Bragg reflector 33 is different from the third wavelength range corresponding to the distributed Bragg reflector 32.

[0125] Optionally, the third wavelength ranges corresponding to different distributed Bragg reflection layers can be different in the sense that they are not exactly the same. For example, the third wavelength ranges corresponding to different distributed Bragg reflection layers can have a partially overlapping interval. For example, the third wavelength range corresponding to the distributed Bragg reflection layer 32 can be 480 nm to 620 nm, and the third wavelength range corresponding to the distributed Bragg reflection layer 33 can be 600 nm to 800 nm.

[0126] Optionally, in the direction (e.g., the direction indicated by the arrow F1) from the first transparent substrate 10 to the battery structure 20, the plurality of distributed Bragg reflection layers are defined as the 1st distributed Bragg reflection layer to the Qth distributed Bragg reflection layer, and the minimum value of the third wavelength range corresponding to the qth distributed Bragg reflection layer is not greater than the maximum value of the third wavelength range corresponding to the q+1th distributed Bragg reflection layer. Here, Q is an integer greater than 1, and q is an integer, 1≤q≤Q. The specific value of Q is not limited in the present application.

[0127] For example, the minimum value of the third wavelength range corresponding to the qth distributed Bragg reflection layer is equal to the maximum value of the third wavelength range corresponding to the q+1th distributed Bragg reflection layer. In the present application, Q=2 is taken as an example. For example, referring to FIG. 1, the third wavelength range corresponding to the distributed Bragg reflection layer 32 (i.e., the 2nd distributed Bragg reflection layer) can be 480 nm to 620 nm, and the third wavelength range corresponding to the distributed Bragg reflection layer 33 (i.e., the 1st distributed Bragg reflection layer) can be 620 nm to 800 nm. Figure 4 Figure 4 For example, the minimum value of the third wavelength range corresponding to the qth distributed Bragg reflection layer is equal to the maximum value of the third wavelength range corresponding to the q+1th distributed Bragg reflection layer. In the present application, Q=2 is taken as an example. For example, referring to FIG. 1, the third wavelength range corresponding to the distributed Bragg reflection layer 32 (i.e., the 2nd distributed Bragg reflection layer) can be 480 nm to 620 nm, and the third wavelength range corresponding to the distributed Bragg reflection layer 33 (i.e., the 1st distributed Bragg reflection layer) can be 620 nm to 800 nm. Figure 4 For example, the minimum value of the third wavelength range corresponding to the qth distributed Bragg reflection layer is equal to the maximum value of the third wavelength range corresponding to the q+1th distributed Bragg reflection layer. In the present application, Q=2 is taken as an example. For example, referring to FIG. 1, the third wavelength range corresponding to the distributed Bragg reflection layer 32 (i.e., the 2nd distributed Bragg reflection layer) can be 480 nm to 620 nm, and the third wavelength range corresponding to the distributed Bragg reflection layer 33 (i.e., the 1st distributed Bragg reflection layer) can be 620 nm to 800 nm.

[0128] For example, the minimum value of the third wavelength range corresponding to the qth distributed Bragg reflection layer is equal to the maximum value of the third wavelength range corresponding to the q+1th distributed Bragg reflection layer. In the present application, Q=2 is taken as an example. For example, referring to FIG. 1, the third wavelength range corresponding to the distributed Bragg reflection layer 32 (i.e., the 2nd distributed Bragg reflection layer) can be 480 nm to 620 nm, and the third wavelength range corresponding to the distributed Bragg reflection layer 33 (i.e., the 1st distributed Bragg reflection layer) can be 620 nm to 800 nm.

[0129] ​Optionally, the third wavelength ranges corresponding to different distributed Bragg reflection layers can also be not completely identical. That is, the minimum value of the third wavelength range corresponding to the qth distributed Bragg reflection layer can also be less than the maximum value of the third wavelength range corresponding to the q+1th distributed Bragg reflection layer. For example, the third wavelength ranges corresponding to different distributed Bragg reflection layers can have a partially overlapping interval. For example, the third wavelength range corresponding to the distributed Bragg reflection layer 32 (i.e., the 2nd distributed Bragg reflection layer) can be 480 nm to 620 nm, and the third wavelength range corresponding to the distributed Bragg reflection layer 33 (the 1st distributed Bragg reflection layer) can be 600 nm to 800 nm.

[0130] With reference to Figure 7 Due to the thickness of the light absorption conversion layer 4 and the band gap width of the material thereof, a part of the light L31 (e.g., the light in the long-wave band of the first wavelength) can not be sufficiently absorbed by the light absorption conversion layer 23, and this part of light can directly be incident on the distributed Bragg reflection layer 33, the propagation direction of the light is changed by the reflection of the distributed Bragg reflection layer 33, and the propagation direction of the light is directed to the battery structure 20, so that the light is absorbed by the light absorption conversion layer 23 again. In addition, the light L32 is not directly absorbed by the light absorption conversion layer 23, and this part of light is incident on the light conversion layer 31. The light conversion layer 31 converts the light into light in the second wavelength range. The light conversion layer 31 can convert the light incident from the front and not sufficiently absorbed by the thin-film solar cell and outside the absorbable wavelength band of the thin-film solar cell into light within the absorbable wavelength band. In addition, a part of the light converted by the light conversion layer 31 has a propagation direction directed to the battery structure 20, and the light directed to the battery structure 20 can be absorbed by the light absorption conversion layer 23 again to improve the output power of the thin-film solar cell. However, a part of the light converted by the light conversion layer 31 has a propagation direction away from the battery structure 20, and the light away from the battery structure 20 can directly be incident on the distributed Bragg reflection layer 32, the propagation direction of the light is changed by the action of the distributed Bragg reflection layer 32, and the propagation direction of the light is directed to the battery structure 20, so that the light is absorbed by the light absorption conversion layer 23 again to improve the output power of the thin-film solar cell.

[0131] With reference to Figure 7Due to the thickness of the light absorption conversion layer 4 and the bandgap of its material, a portion of the light L41 is incident on the light conversion layer 31, which converts this light into light within the second wavelength range. Another portion passes through the light conversion layer 31 and is incident on the light absorption conversion layer 23. Furthermore, light L42 is not directly absorbed by the light absorption conversion layer 23; this portion is incident on the light conversion layer 31, which converts it into light within the second wavelength range. Thus, the light conversion layer 31 can convert back-incident light that is not fully absorbed by the thin-film solar cell and is outside its absorbable wavelength range into light within its absorbable wavelength range. Moreover, a portion of the light converted by the light conversion layer 31 propagates towards the cell structure 20. This light directed towards the cell structure 20 can be absorbed again by the light absorption conversion layer 23 to improve the output power of the thin-film solar cell. However, some of the light converted by the light conversion layer 31 has a propagation direction that deviates from the battery structure 20. This light that deviates from the battery structure 20 can be directly incident on the distributed Bragg reflector layer 32. Through the action of the distributed Bragg reflector layer 32, the propagation direction of this light is changed so that it points towards the battery structure 20, and is then absorbed again by the light absorption conversion layer 23 to improve the output power of the thin-film solar cell.

[0132] In this embodiment, the distributed Bragg reflector layer 32 includes a plurality of alternating first refractive index layers 321-1 to 321-N and a plurality of second refractive index layers 322-1 to 322-N. Its implementation can refer to the above embodiment, and will not be repeated here.

[0133] For example, refer to Figure 7 and Figure 8 The distributed Bragg reflector layer 33 includes multiple alternating first refractive index layers 321-1 to 321-K and multiple second refractive index layers 322-1 to 322-K. The number of first and second refractive index layers is the same, and the multiple first refractive index layers 321-1 to 321-K and multiple second refractive index layers 322-1 to 322-K are alternately arranged. That is, the first refractive index layer 331-1 is in direct contact with the second conductive layer 25, the second refractive index layer 332-1 is located on the first refractive index layer 331-1, and the first refractive index layer 331-2 is located on the second refractive index layer 332-1. The rest are similar and can be deduced sequentially, without further details. Furthermore, the first refractive index of the first refractive index layer is greater than the second refractive index of its adjacent second refractive index layer. For example, the first refractive index of the first refractive index layer 331-2 is greater than the second refractive index of the second refractive index layer 332-1 and the second refractive index of the second refractive index layer 332-2. The same principle applies to the others, and will not be elaborated upon here. In this way, a distributed Bragg reflector layer 33 can be formed by repeatedly setting the first and second refractive index layers.

[0134] The specific value of K is not limited in the present application, which can be determined according to the requirements of actual application.

[0135] In the present embodiment, the first refractive index layers 321-1 to 321-K and the second refractive index layers 322-1 to 322-K in the distributed Bragg reflection layer 33 can refer to the implementation of the first refractive index layers 321-1 to 321-N and the second refractive index layers 322-1 to 322-N in the above embodiment, which will not be repeated here.

[0136] The bandwidth (such as the third wavelength range) of the reflected light reflected by the distributed Bragg reflection layers 32 and 33 can be determined by the refractive index difference of the materials of the first refractive index layers and the second refractive index layers. For example, the greater the refractive index difference, the greater the bandwidth of the reflected light.

[0137] In order to prepare Figure 8 The corresponding flowchart of the preparation method can refer to Figure 6 , wherein step S10 can refer to the description of the preparation method above.

[0138] Step S20 is to form an optical structure on the battery structure.

[0139] In some examples, taking the example that the light conversion layer includes up-conversion quantum dot material, step S20 includes:

[0140] First, referring to Figure 8 , a distributed Bragg reflection layer 33 is formed on the second conductive layer 25 by using a thin film preparation process. For example, first, a first refractive index layer 331-1 is formed on the second conductive layer 25 by using a SiO2 solution through a method such as plasma-enhanced chemical vapor deposition, magnetron sputtering, spin coating or blade coating. Then, a second refractive index layer 332-1 is formed on the first refractive index layer 331-1 by using a SiN x solution through a method such as plasma-enhanced chemical vapor deposition, magnetron sputtering, spin coating or blade coating. Then, the process of preparing the first refractive index layer 331-1 and the second refractive index layer 332-1 is repeated to form the first refractive index layer and the second refractive index layer that appear in turn, so as to form a structure of SiO2 / SiN x / SiO2 / SiN x ……SiO2 / SiN x , forming the distributed Bragg reflection layer 33. The thickness of the first refractive index layer and the second refractive index layer is determined according to the central wavelength of the reflected light and the corresponding refractive index.

[0141] Then, referring to Figure 8The light conversion layer 31 is formed on the surface of the second refractive layer 332-K by using a thin film preparation process and using the up-conversion quantum dot material. For example, first, the up-conversion quantum dot material NaYF4:Yb 3+ :Er 3+ and SiO2nanoparticle dispersion liquid (solvent: cyclohexane) with an average size of 20 nm are mixed, and then dropped on the surface of the second refractive layer 332-K. The ratio between the concentration of the up-conversion quantum dot material in the dispersion agent and the concentration of the nanoparticle in the dispersion agent is 0.05, i.e., the ratio between the concentration of the up-conversion quantum dot material in the dispersion agent and the concentration of the SiO2nanoparticle in the dispersion agent is 1:20. Then, the light conversion layer film is formed by using a spin coating or a blade coating method. After that, the light conversion layer film is cured by using a hot stage including but not limited to a temperature of 150 °C.

[0142] After that, referring to Figure 8 , the distributed Bragg reflector layer 32 is formed on the light conversion layer 31 by using a thin film preparation process. For example, first, the first refractive layer 321-1 is formed on the light conversion layer 31 by using a SiO2solution through a plasma enhanced chemical vapor deposition method, a magnetron sputtering method, a spin coating or a blade coating method. After that, the second refractive layer 322-1 is formed on the first refractive layer 321-1 by using a SiN x solution through a plasma enhanced chemical vapor deposition method, a magnetron sputtering method, a spin coating or a blade coating method. After that, the process of preparing the first refractive layer 321-1 and the second refractive layer 322-1 is repeated to form the first refractive layer and the second refractive layer which appear alternately to form a structure of SiO2 / SiN x / SiO2 / SiN x ……SiO2 / SiN x , forming the distributed Bragg reflector layer 32. The thickness of the first refractive layer and the second refractive layer is determined according to the central wavelength of the reflected light and the corresponding refractive index.

[0143] Figure 9 Another structure schematic diagram of the thin film solar cell in the embodiment of the present application is exemplarily shown. Figure 10 Another specific structure schematic diagram of the thin film solar cell in the embodiment of the present application is exemplarily shown.

[0144] Referring to Figure 9 and Figure 10In the embodiment, the thin-film solar cell comprises a first transparent substrate 10, a cell structure 20 on the first transparent substrate 10, and an optical structure 30 on the cell structure 20. The optical structure 30 comprises a distributed Bragg reflector 33, a light conversion layer 31, and a distributed Bragg reflector 32. The embodiment is a variation of the implementation in the above embodiment. The differences between the embodiment and the above embodiment are described below, and the same parts are not described herein.

[0145] With reference to Figure 9 With Figure 10 In the embodiment, the thin-film solar cell further comprises a second transparent substrate 40. The optical structure 30 is formed on the second transparent substrate 40, the cell structure 20 is formed on the first transparent substrate 10, and the optical structure 30 and the cell structure 20 are bonded together by an adhesive 50. In this way, the optical structure 30 can be prepared on the second transparent substrate 40, the cell structure 20 can be prepared on the first transparent substrate 10, and the optical structure 30 and the cell structure 20 can be bonded together by the adhesive 50. That is, the adhesive 50 is used to bond the side surface of the second transparent substrate 40 with the optical structure 30 to the side surface of the first transparent substrate 10 with the cell structure 20, so that the second transparent substrate 40 with the optical structure 30 is bonded to the first transparent substrate 10 with the cell structure 20, and the thin-film solar cell is formed.

[0146] For example, the second transparent substrate 40 can comprise a glass substrate. Of course, the second transparent substrate 40 can also be other transparent substrates, which are not limited herein.

[0147] For example, the second transparent substrate 40 can comprise a glass substrate. Of course, the second transparent substrate 40 can also be other transparent substrates, which are not limited herein. Figure 10 For example, the second transparent substrate 40 can comprise a glass substrate. Of course, the second transparent substrate 40 can also be other transparent substrates, which are not limited herein. Figure 6 The step S10 can refer to the description of the preparation method above.

[0148] Before the step S20, the method further comprises: forming the optical structure 30 by forming at least one light conversion layer and at least one distributed Bragg reflector alternately on the second transparent substrate 40 by a thin-film preparation process. The process can be performed simultaneously with the step S10 or before the step S10, which is not limited herein.

[0149] First, referring to Figure 10 The distributed Bragg reflector 32 is formed on the second transparent substrate 40 by a thin-film preparation process. For example, first, SiN xThe solution forms a second refractive index layer 322-N on the second transparent substrate 40. Then, a first refractive index layer 321-N is formed on the second refractive index layer 322-N by using a SiO2 solution through a method such as plasma enhanced chemical vapor deposition, magnetron sputtering, spin coating, or blade coating. Then, the process of preparing the first refractive index layer 331-N and the second refractive index layer 332-N is repeated to form the first refractive index layer and the second refractive index layer that appear in turn to form a structure of SiO2 / SiN x / SiO2 / SiN x …SiO2 / SiN x …SiO2 / SiN

[0150] Then, referring to Figure 10 , a film preparation process is used to form a light conversion layer 31 on the surface of the first refractive index layer 321-1 by using an up-conversion quantum dot material. Exemplarily, first, a SiO2 nanoparticle dispersion liquid (solvent: cyclohexane) mixed with an up-conversion quantum dot material: NaYF4:Yb 3+ :Er 3+ quantum dots (average size: 20 nm) is added dropwise on the surface of the first refractive index layer 321-1. The ratio between the concentration of the up-conversion quantum dot material in the dispersant and the concentration of the nanoparticles in the dispersant is 0.05, i.e., the ratio between the concentration of the up-conversion quantum dot material in the dispersant and the concentration of the SiO2 nanoparticles in the dispersant is 1:20. Then, a light conversion layer film is formed by using a method such as spin coating or blade coating. Then, the light conversion layer film is cured by using a hot stage including but not limited to a temperature of 150°C.

[0151] Then, referring to Figure 10 , a film preparation process is used to form a light conversion layer 31 on the surface of the first refractive index layer 321-1 by using an up-conversion quantum dot material. Exemplarily, first, a SiO2 nanoparticle dispersion liquid (solvent: cyclohexane) mixed with an up-conversion quantum dot material: NaYF4:Yb x :Er x quantum dots (average size: 20 nm) is added dropwise on the surface of the first refractive index layer 321-1. The ratio between the concentration of the up-conversion quantum dot material in the dispersant and the concentration of the nanoparticles in the dispersant is 0.05, i.e., the ratio between the concentration of the up-conversion quantum dot material in the dispersant and the concentration of the SiO2 nanoparticles in the dispersant is 1:20. Then, a light conversion layer film is formed by using a method such as spin coating or blade coating. Then, the light conversion layer film is cured by using a hot stage including but not limited to a temperature of 150°C. x …SiO2 / SiN xThe optical structure 30 is formed by the first refractive index layer and the second refractive index layer, and forms a distributed Bragg reflection layer 33. The thickness of the first refractive index layer and the second refractive index layer is determined according to the central wavelength of the reflected light and the corresponding refractive index.

[0152] Step S20 is to form the optical structure on the battery structure.

[0153] In some examples, step S20 includes Figure 10 The second transparent substrate 40 having the optical structure 30 is bonded to the first transparent substrate 10 having the battery structure 20 by using the bonding material 50.

[0154] Figure 11 An exemplary structure diagram of a photovoltaic module in an embodiment of the present application is shown. Figure 12 An exemplary structure diagram of another photovoltaic module in an embodiment of the present application is shown. Figure 13 An exemplary structure diagram of another photovoltaic module in an embodiment of the present application is shown.

[0155] Referring to Figure 11 to Figure 13 The photovoltaic module provided by the embodiment of the present application can include a housing and the above-mentioned thin-film solar cell provided by the embodiment of the present application. The thin-film solar cell can be located in the housing. In this way, the thin-film solar cell can be protected by the housing, avoiding the interference of the external environment, and improving the reliability and safety of the photovoltaic module.

[0156] In addition, the thin-film solar cells arranged in the housing are not limited to one, and there can be multiple thin-film solar cells. The number of thin-film solar cells in the housing can be set according to actual needs to improve the power generation power of the power generation equipment. In addition, the electrical connection relationship of the thin-film solar cells can be set as parallel connection, series connection, or a combination of series connection and parallel connection. The electrical connection relationship can be set according to actual needs, which is not limited herein.

[0157] Referring to Figure 11 to Figure 13 The battery structure 20 in each thin-film solar cell is multiple, and the multiple battery structures 20 are connected in series. For example, for two adjacent battery structures 20, the first conductive layer 21 of one of the two battery structures 20 is connected to the second conductive layer 25 of the other battery structure 20 through the connecting part 70. In addition, the first conductive layers 21 of different battery structures 20 have the insulating material 60 therebetween, and the second conductive layers 25 of different battery structures 20 also have the insulating material 60 therebetween. In addition, for the connecting part 70 and the battery structure 20 in which the second conductive layer 25 and the connecting part 70 are located, the connecting part 70 also has the insulating material 60 between the connecting part 70 and the remaining film layers of the battery structure 20 except the second conductive layer 25, to achieve the insulation effect.

[0158] Exemplarily, referring to Figure 11 to Figure 13 , the embodiments of the optical structure 30 can refer to the above-mentioned embodiments, which are not repeated here.

[0159] Figure 14 Exemplarily, a structure schematic diagram of a power generation device in the embodiment of the present application is shown. Referring to Figure 14 , the power generation device provided in the embodiment of the present application can include the above-mentioned photovoltaic module 100 provided in the embodiment of the present application, and an inverter 200 electrically connected with the photovoltaic module 100. Through the inverter 200, the direct current signal output by the photovoltaic module 100 can be converted into an alternating current signal, and then the converted alternating current signal can be incorporated into a power grid 300 for use.

[0160] The number of the photovoltaic module 100 included in the power generation device is not limited to Figure 14 two as shown in the embodiment, but can be one or more, which can be set according to actual needs, and is not limited here.

[0161] In the embodiment of the present application, as Figure 14 shown, when the photovoltaic module 100 is provided with multiple, the inverter 200 can be provided with multiple, and the photovoltaic module 100 and the inverter 200 are one-to-one correspondingly arranged, so as to realize the conversion processing of the direct current signal output by the corresponding arranged photovoltaic module 100 by the inverter 200, so as to improve the conversion accuracy.

[0162] Of course, when the photovoltaic module is provided with multiple, the inverter can be provided with one, which is not shown in the figure. At this time, the inverter is electrically connected with each photovoltaic module. At this time, the inverter can convert the direct current signal output by each photovoltaic module, so as to reduce the number of inverter settings and reduce the manufacturing cost of the power generation device.

[0163] In the embodiment of the present application, in addition to the photovoltaic module and the inverter, the power generation device can also include other structures that can be used to realize the function of the power generation device, which is not limited here.

[0164] In the embodiment of the present application, the power generation device can be but is not limited to a ground power station or a photovoltaic building integrated device.

[0165] Although the preferred embodiments of the present application have been described, those skilled in the art can make further changes and modifications to the embodiments once they know the basic creative concept. Therefore, the appended claims are intended to be interpreted as including all changes and modifications falling within the scope of the present application.

[0166] It is apparent that a person skilled in the art can make various modifications and variations to the embodiments of the application without departing from the spirit and scope of the application. Therefore, the application is intended to cover the modifications and variations of this application provided they come within the scope of the appended claims and their equivalents.

Claims

1. A thin-film solar cell, characterized in that, include: First transparent substrate; A battery structure, located on the first transparent substrate, is used to absorb light in a first wavelength range; An optical structure is located on the side of the battery structure opposite to the first transparent substrate. The optical structure includes: a first distributed Bragg reflection layer, a light conversion layer, and a second distributed Bragg reflection layer. The light conversion layer is located between the first distributed Bragg reflection layer and the second distributed Bragg reflection layer, and the first distributed Bragg reflection layer is located between the light conversion layer and the battery structure. The second transparent substrate is located on the side of the optical structure opposite to the battery structure; The light conversion layer is used to convert light incident on it after passing through the battery structure and the first distributed Bragg reflector layer into light in the first wavelength range, and to convert light incident on it after passing through the second distributed Bragg reflector layer into light in the first wavelength range. The first distributed Bragg reflector layer is used to reflect light within the first third wavelength range, so that the propagation direction of the reflected light is directed towards the battery structure; The second distributed Bragg reflector layer is used to reflect light in a second and third wavelength range, so that the propagation direction of the reflected light is directed towards the battery structure; The first third wavelength range and the second third wavelength range do not overlap at least partially, and the first third wavelength range and the second third wavelength range are respectively located within the first wavelength range; The thin-film solar cell is a double-sided thin-film solar cell. The side of the cell structure facing the first transparent substrate is the front side of the double-sided thin-film solar cell, and the side of the cell structure facing away from the optical structure is the back side of the double-sided thin-film solar cell.

2. The thin-film solar cell according to claim 1, characterized in that, The distributed Bragg reflector layer includes multiple first refractive index layers and multiple second refractive index layers; the refractive index of the first refractive index layer is greater than the refractive index of the adjacent second refractive index layer. The plurality of first refractive index layers and the plurality of second refractive index layers are alternately arranged, and the distributed Bragg reflector layer contacts the light conversion layer through the first refractive index layer.

3. The thin-film solar cell according to claim 2, characterized in that, In the same distributed Bragg reflector layer, the refractive indices of the plurality of first refractive index layers are the same; And / or, in the same distributed Bragg reflector layer, the refractive indices of the plurality of second refractive index layers are the same.

4. The thin-film solar cell according to any one of claims 1-3, characterized in that, The wavelength range of the light converted by the light conversion layer is within the wavelength range of the light reflected by the second distributed Bragg reflector layer.

5. The thin-film solar cell according to any one of claims 1-3, characterized in that, The second distributed Bragg reflector and the first distributed Bragg reflector reflect light in different wavelength ranges.

6. The thin-film solar cell according to claim 5, characterized in that, The minimum wavelength range of light reflected by the first distributed Bragg reflector is not greater than the maximum wavelength range of light reflected by the second distributed Bragg reflector.

7. The thin-film solar cell according to any one of claims 1-3, characterized in that, The light conversion layer is also used to convert at least a portion of the wavelengths of light incident from the side of the optical structure away from the battery structure into light within the first wavelength range.

8. The thin-film solar cell according to any one of claims 1-3, characterized in that, The wavelength range of the light converted by the light conversion layer is the second wavelength range; The material of the light conversion layer includes: upconversion material and / or downconversion material; The upconversion material is used to convert light with a wavelength greater than the maximum value of the second wavelength range into light within the second wavelength range; The downconversion material is used to convert light with a wavelength smaller than the minimum wavelength of the second wavelength range into light within the second wavelength range.

9. The thin-film solar cell according to any one of claims 1-3, characterized in that, The optical structure is formed on the second transparent substrate, the battery structure is formed on the first transparent substrate, and the optical structure and the battery structure are bonded together using an adhesive material.

10. A photovoltaic module, characterized in that, include: The housing, and the thin-film solar cell as described in any one of claims 1-9; The thin-film solar cell is disposed inside the housing; The thin-film solar cell has multiple battery structures, and the multiple battery structures are connected in series sequentially.

11. A power generation device, characterized in that, include: The photovoltaic module as described in claim 10 and the inverter electrically connected to the photovoltaic module; The inverter is used to convert the DC signal output by the photovoltaic module into an AC signal.

12. A method for preparing a thin-film solar cell, characterized in that, include: A battery structure is formed on a first transparent substrate; The battery structure is used to absorb light in a first wavelength range; An optical structure is formed on the battery structure; The optical structure includes: a first distributed Bragg reflector layer, a light conversion layer, and a second distributed Bragg reflector layer; the light conversion layer is located between the first and second distributed Bragg reflector layers, and the first distributed Bragg reflector layer is located between the light conversion layer and the battery structure; wherein, the light conversion layer is used to convert light incident upon it after passing through the battery structure and the first distributed Bragg reflector layer into light within a first wavelength range, and to convert light incident upon it after passing through the second distributed Bragg reflector layer into light within the first wavelength range; the first distributed Bragg reflector layer is used to reflect light within a first third wavelength range, such that the propagation direction of the reflected light points towards the battery structure; the second distributed Bragg reflector layer is used to reflect light within a second third wavelength range, such that the propagation direction of the reflected light points towards the battery structure; the first third wavelength range and the second third wavelength range do not overlap at least partially, and the first third wavelength range and the second third wavelength range are respectively located within the first wavelength range. A second transparent substrate is formed on the side of the optical structure opposite to the battery structure; The thin-film solar cell is a double-sided thin-film solar cell. The side of the cell structure facing the first transparent substrate is the front side of the double-sided thin-film solar cell, and the side of the cell structure facing away from the optical structure is the back side of the double-sided thin-film solar cell.

13. The preparation method according to claim 12, characterized in that, Before forming the optical structure on the battery structure, the method further includes: The optical structure is formed on a second transparent substrate using a thin-film fabrication process. The formation of the optical structure on the battery structure includes: An adhesive material is used to bond the side surface of the second transparent substrate having the optical structure to the side surface of the first transparent substrate having the battery structure.

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