Laminated photovoltaic device and method of production

Abstract

The invention provides a laminated photovoltaic device and a production method, and relates to the technical field of photovoltaics. The laminated photovoltaic device comprises an upper-layer battery unit, a lower-layer battery unit, an insulating layer and a middle series structure, the upper-layer cell unit is a thin film solar cell; the lower-layer battery unit is provided with a light-facing surface and a backlight surface which are oppositely arranged, and a side surface connected with the light-facing surface and the backlight surface; and the insulating layer at least wraps the side surface of the lower-layer battery unit. The insulating layer is wrapped on the side surface of the lower-layer battery unit, so that the coating or winding plating of the thin film solar cell on the lower side surface of the thin film solar cell is positioned on the insulating layer and is not in contact with the side surface of the lower-layer battery unit, and the direct coating or winding plating of the thin film solar cell on the side surface of the lower-layer battery unit is avoided; the short circuit of the upper and lower layers of battery units is reduced to a great extent, and the power generation efficiency and the production yield of the laminated photovoltaic device can be improved. The production process is simple, and the production cost is low.

Description

Multilayer photovoltaic devices and manufacturing methods

[0001] This application is a divisional application. The parent application was filed on August 31, 2020, with application number 202010899582.7 and the invention title is: Multilayer Photovoltaic Device and Manufacturing Method. Technical Field

[0002] This invention relates to the field of photovoltaic technology, and in particular to a multilayer photovoltaic device and its manufacturing method. Background Technology

[0003] Multilayer photovoltaic devices can divide sunlight into multiple bands. From the front to the back, solar cell units with gradually decreasing band gaps absorb sunlight of different energies to reduce energy loss in the visible light band and improve photoelectric conversion efficiency.

[0004] However, in tandem photovoltaic devices, those with thin-film solar cells as the upper cell unit typically have low power generation efficiency and poor production yield. Summary of the Invention

[0005] This invention provides a tandem photovoltaic device and its manufacturing method, aiming to solve the problems of low power generation efficiency and poor production yield of tandem photovoltaic devices with thin-film solar cells as the upper battery unit.

[0006] According to a first aspect of the present invention, a tandem photovoltaic device is provided, comprising: an upper battery cell, a lower battery cell, and an intermediate series structure located between the upper battery cell and the lower battery cell; the upper battery cell is a thin-film solar cell; the lower battery cell has a light-facing surface and a back-lighting surface disposed opposite to each other, and a side surface connecting the light-facing surface and the back-lighting surface; the tandem photovoltaic device further comprises an insulating layer at least wrapped around the side surface of the lower battery cell.

[0007] In this application, an insulating layer is wrapped around the side of the lower battery cell, so that the coating or coating of the thin-film solar cell on its lower side is located on the insulating layer and does not come into contact with the side of the lower battery cell. This avoids direct coating or coating of the thin-film solar cell on the side of the lower battery cell, which greatly reduces the short circuit between the upper and lower battery cells and can improve the power generation efficiency and production yield of the tandem photovoltaic device. Moreover, the manufacturing process is simple and the production cost is low.

[0008] Optionally, the insulating layer further extends to at least a portion of the side surface of the first layer; the first layer is a layer with charge carrier conductivity in the intermediate series structure, or the first layer is a layer with charge carrier conductivity in the portion of the upper battery cell near the intermediate series structure.

[0009] Optionally, the insulating layer extends and covers the edge region of the light-facing side of the lower battery cell; and / or, the insulating layer extends and covers the edge region of the backlight side of the lower battery cell.

[0010] Optionally, the insulating layer extends and covers the edge region of the light-facing side of the first layer; and / or, the insulating layer extends and covers the edge region of the backlight side of the first layer.

[0011] Optionally, the first layer is a lower transmission layer close to the lower battery cell.

[0012] Optionally, the upper battery cell includes a buffer layer; the insulating layer also extends to wrap around at least a portion of the sides of the buffer layer.

[0013] Optionally, the tandem photovoltaic device further includes a lower functional film located on the back surface of the lower battery cell, the lower functional film including a back transmission layer; the insulating layer also extends to wrap around at least a portion of the side surface of the back transmission layer.

[0014] Optionally, the thickness of the insulating layer is greater than or equal to 10 nm; the insulating layer is a single layer or multiple layers.

[0015] Optionally, the insulating layer is disposed on the light-facing surface of the lower battery cell; the insulating layer disposed on the light-facing surface of the lower battery cell has at least one through hole, and each through hole is filled with conductive material; the insulating layer disposed on the light-facing surface of the lower battery cell and the conductive material filled in the through hole form the intermediate series structure.

[0016] Optionally, the insulation strength of the insulating layer is greater than or equal to 3MV / cm.

[0017] Optionally, when the lower battery cell is a crystalline silicon solar cell, the insulating layer is at least one of the following: silicon oxide layer, silicon nitride layer, silicon oxyfluoride layer, silicon oxycarbonate layer, aluminum oxide layer, aluminum fluoride layer, aluminum oxynitride layer, and magnesium fluoride layer.

[0018] Optionally, the side insulating layer includes a silicon oxide layer, an aluminum oxide layer, and a silicon nitride layer stacked sequentially, wherein the silicon oxide layer is in contact with the lower battery cell.

[0019] According to a second aspect of the present invention, a method for manufacturing a tandem photovoltaic device is provided, comprising the following steps: providing a lower battery cell; the lower battery cell having a light-facing surface and a back-lighting surface disposed opposite to each other, and a side surface connecting the light-facing surface and the back-lighting surface; obtaining an insulating layer at least covering the side surface of the lower battery cell by deposition or growth; fabricating an intermediate series structure on the light-facing surface of the lower battery cell; depositing an upper battery cell on the light-facing surface of the intermediate series structure; wherein the lower battery cell is a thin-film solar cell.

[0020] The production method of the above-mentioned tandem photovoltaic device has the same or similar beneficial effects as the aforementioned tandem photovoltaic device. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 shows a schematic diagram of the structure of the first type of stacked photovoltaic device in an embodiment of the present invention; Figure 2 shows a schematic diagram of the structure of the second type of stacked photovoltaic device in an embodiment of the present invention; Figure 3 shows a schematic diagram of the structure of the third type of stacked photovoltaic device in an embodiment of the present invention; Figure 4 shows a schematic diagram of the structure of the fourth type of stacked photovoltaic device in an embodiment of the present invention; Figure 5 shows a schematic diagram of the structure of the fifth type of stacked photovoltaic device in an embodiment of the present invention; Figure 6 shows a schematic diagram of the structure of the sixth type of stacked photovoltaic device in an embodiment of the present invention.

[0023] Explanation of the numbers in the attached figures: 1-lower battery cell, 2-insulating layer, 3-upper battery cell, 31-lower transport layer, 32-upper transport layer, 33-substrate of upper battery cell, 4-intermediate series structure, 5-upper functional film, 6-lower functional film, 7-top electrode, 8-bottom electrode. Detailed Implementation

[0024] The inventors of this application have discovered that the main reason for the low power generation efficiency and poor production yield of stacked photovoltaic devices with thin-film solar cells as the upper battery unit is that thin-film solar cells are prone to being coated or coated on the side of the lower battery unit, which can lead to short circuits between the upper and lower battery units.

[0025] In an embodiment of the present invention, referring to FIG1, FIG1 shows a schematic diagram of the structure of a first type of stacked photovoltaic device according to an embodiment of the present invention. The stacked photovoltaic device includes: a lower battery cell 1, an upper battery cell 3, an insulating layer 2, and an intermediate series structure 4 located between the upper battery cell 3 and the lower battery cell 1. The intermediate series structure 4 is used to connect the upper battery cell 3 and the lower battery cell 1 in series to form the stacked photovoltaic device. The upper battery cell 3 is a thin-film solar cell, which may include amorphous silicon thin-film solar cells, amorphous silicon carbide thin-film solar cells, copper indium gallium selenide sulfur thin-film solar cells, cadmium telluride thin-film solar cells, gallium arsenide solar cells, perovskite solar cells, organic thin-film solar cells, quantum dot thin-film solar cells, group III-V solar cells, etc., and the present invention does not specifically limit the types of cells.

[0026] It is understood that the upper battery cell 3 and the lower battery cell 1 have different bandgap widths, and the bandgap of the upper battery cell 3 is larger than that of the lower battery cell 1. For example, the bandgap width of the upper battery cell 3 is 1.5-2.3 eV. In this embodiment of the invention, the number of upper battery cells, lower battery cells, and intermediate series structures included in the tandem photovoltaic device are not specifically limited. The upper and lower battery cells can be electrically and optically adapted to achieve the best effect.

[0027] The light-facing surface of the upper battery cell 3 can have one or more functional layers such as a transmission layer, passivation layer, window layer, antireflection layer, and light-trapping layer. The light-facing surface of the upper battery cell 3 can be a planar surface, a textured surface, a nano-light-trapping structure, or other structures.

[0028] The lower-layer cell 1 can be a crystalline silicon cell. The doping type of the silicon substrate material in the lower-layer cell 1 is not limited; it can be a front-side pn junction or a back-side pn junction structure, and it can be a single-sided or double-sided structure. The light-facing surface of the lower-layer cell 1 can be a planar structure or have a light-trapping structure. The light-facing surface of the lower-layer cell 1 can have one or more functional structures such as transport layers, passivation layers, and buffer layers. The back-lighting surface of the lower-layer cell 1 can also have one or more functional structures such as transport layers, passivation layers, and buffer layers. For example, the lower-layer cell 1 can have a TOPCon (Tunnel Oxide Passivated Contact) structure, a PERC (Passivated Emitter and Rear Contact) structure, a PERT (Passivated Emitter and Rear Totally-diffused) structure, a PERL (Passivated Emitter and Rear Locally-diffused) structure, an Al-BSF structure, a SHJ structure, a POLO structure, a DASH structure, etc. The lower-layer cell 1 can employ deep junction or shallow junction processes.

[0029] Understandably, the intermediate series structure 4 is transparent, allowing light to pass through the wavelengths remaining after absorption by the upper battery cells. This transparent wavelength range can be determined based on the wavelengths remaining after absorption by the adjacent upper battery cells. For example, the transparent wavelength range can be the wavelengths remaining after absorption by the adjacent upper battery cells. The intermediate series structure 4 serves to connect the upper and lower battery cells in series and can be a single or multiple structure, employing structures such as metal series connection, transparent transport layer, composite layer, or tunnel junction. For instance, the intermediate series structure 4 can be a transparent conductive film.

[0030] The lower battery unit 1 has a light-facing surface and a back-light-facing surface arranged opposite each other, as well as a side surface connecting the light-facing surface and the back-light-facing surface. The light-facing surface of the lower battery unit 1 is the surface of the lower battery unit 1 closest to the upper battery unit 3. The number of side surfaces included in the lower battery unit 1 is not specifically limited. For example, if the lower battery unit 1 is a cuboid, then the lower battery unit 1 includes 4 side surfaces.

[0031] Without the insulating layer 2, the coating or wrapping of the thin-film solar cell on its lower side has a significant impact on the side of the lower cell unit 1, easily leading to a short circuit between the upper cell unit 3 and the lower cell unit 1. This results in low power generation efficiency and poor production yield of the tandem photovoltaic device. Referring to Figure 1, the insulating layer 2 is wrapped around all sides of the lower cell unit 1, so that the coating or wrapping of the thin-film solar cell on its lower side is located on the insulating layer 2 and does not come into contact with the side of the lower cell unit 1. This avoids direct coating or wrapping of the thin-film solar cell on the side of the lower cell unit 1, greatly reducing the short circuit between the upper cell unit 3 and the lower cell unit 1, and improving the power generation efficiency and production yield of the tandem photovoltaic device. Furthermore, during the production process of this tandem photovoltaic device, it is only necessary to set an insulating layer on the side of the lower battery cell before depositing the upper battery cell on the light-facing surface of the intermediate series structure. Other processes do not need to be changed, and there is no need to perform operations such as scribing isolation, edge cutting or cleaning on the side of the tandem photovoltaic device. This will not cause dead zones at the edges of the tandem photovoltaic device, making the production process simple and the production cost low.

[0032] The tandem photovoltaic device shown in Figure 1 can have an insulating layer 2 placed on the side of the lower battery cell 1 after the lower battery cell 1 is fabricated and before the upper battery cell 3 is deposited. The thin-film solar cell is coated or wrapped around the insulating layer 2 on its lower side without contacting the side of the lower battery cell 1.

[0033] The material of insulating layer 2 is selected from insulating or dielectric materials, which have good electrical insulation properties, and is made by deposition or growth processes.

[0034] Optionally, the edge region of the light-facing side of the lower battery cell 1 is the area near the side of the light-facing side of the lower battery cell 1. The edge region of the backlight side of the lower battery cell 1 is the area near the side of the backlight side of the lower battery cell 1. The insulating layer 2 extends and covers the edge region of the light-facing side of the lower battery cell 1, and / or the insulating layer 2 extends and covers the edge region of the backlight side of the lower battery cell 1, thereby improving the coverage effect of the insulating layer 2 on the lower battery cell 1 and further reducing the risk of short circuit between the upper battery cell 3 and the lower battery cell 1. It should be noted that the size of the edge region of the light-facing side of the lower battery cell 1 covered by the insulating layer 2 is determined according to actual needs. Similarly, the size of the edge region of the backlight side of the lower battery cell 1 covered by the insulating layer 2 is determined according to actual needs.

[0035] Optionally, in the tandem photovoltaic device, the insulating layer 2 further extends and wraps around at least a portion of the side surface of the first layer; this first layer is a layer with charge carrier conductivity in the intermediate series structure 4, or, the first layer is a layer with charge carrier conductivity in the portion of the upper battery cell 3 closest to the intermediate series structure 4. Charge carriers include electrons and holes. The layer with charge carrier conductivity can be: a layer with electron conductivity, and / or a layer with hole conductivity. The coating or wrapping of the thin-film solar cell on its lower side surface is located on the insulating layer and does not contact the side surface of the layer with charge carrier conductivity, avoiding direct coating or wrapping of the thin-film solar cell on the side surface of the layer with charge carrier conductivity, which greatly improves the power generation efficiency and production yield of the tandem photovoltaic device. Furthermore, the manufacturing process is simple and the production cost is low.

[0036] The insulating layer extends and covers at least a portion of the sides of the first layer, which can be: the insulating layer 2 extends and covers all sides of the entire first layer having charge carrier conductivity. Alternatively, the insulating layer 2 extends and covers all sides of a portion of the first layer having charge carrier conductivity, while the insulating layer 2 is not covered on the remaining portions of the first layer having charge carrier conductivity. Or, the insulating layer 2 can be: the insulating layer 2 covers a portion of the sides of the first layer having charge carrier conductivity, while the insulating layer 2 is not covered on the remaining portions of the first layer having charge carrier conductivity.

[0037] Optionally, the edge region of the light-facing side of the first layer is the area near the side of the light-facing side of the first layer. The edge region of the back-facing side of the first layer is the area near the side of the back-facing side of the first layer. The insulating layer 2 extends and covers the edge region of the light-facing side of the first layer, and / or, the insulating layer 2 extends and covers the edge region of the back-facing side of the first layer. That is, the insulating layer 2 also extends and covers the edge regions of the upper and lower surfaces of the first layer or the edge region of the interlayer interface. This results in a better coating effect of the insulating layer 2 on the layer with charge carrier conduction capability, further improving the power generation efficiency and production yield of the tandem photovoltaic device. It should be noted that the size of the edge region of the insulating layer 2 extending to the light-facing side of the first layer is determined according to actual needs. Similarly, the size of the edge region of the insulating layer 2 extending to the back-facing side of the first layer is determined according to actual needs.

[0038] For example, referring to Figure 2, Figure 2 shows a schematic diagram of the structure of the second type of stacked photovoltaic device in an embodiment of the present invention. In Figure 2, the first layer can be the lower transmission layer 31 of the upper battery cell 3. The insulating layer 2 is disposed on all sides of the lower battery cell 1, and extends to cover the intermediate series structure 4 and all sides of the lower transmission layer 31 of the upper battery cell 3. The insulating layer 2 also extends to cover all sides of the lower functional film 6, and extends to cover the edge regions of the light-facing side and the back-light-facing side of the lower transmission layer 31. At the same time, the insulating layer 2 also extends to cover the edge regions of the light-facing side and the back-light-facing side of the lower functional film 6.

[0039] The tandem photovoltaic device shown in Figure 2 can be fabricated by depositing an insulating layer 2 on the entire side surface of the lower functional film 6, the lower battery cell 1, the intermediate series structure 4, and the lower transport layer 31, as well as the edge regions of the light-facing and back-facing surfaces of the lower transport layer 31, and the edge regions of the back-facing and light-facing surfaces of the lower functional film 6. Then, the substrate 33 of the upper battery cell is deposited on the light-facing surface of the lower transport layer 31. The thin-film solar cell is coated or wrapped around the insulating layer on its lower side surface and does not contact the side surface of the lower transport layer 31, the intermediate series structure 4, the lower battery cell 1, or the lower functional film 6.

[0040] All or part of the sides of the intermediate series structure 4 typically have carrier conductivity. Referring to Figure 3, which shows a schematic diagram of the third type of tandem photovoltaic device according to an embodiment of the present invention. Optionally, the insulating layer 2 extends to wrap around all or part of the sides of the intermediate series structure 4. Figure 3 shows the insulating layer 2 extending to wrap around all the sides of the intermediate series structure 4 in addition to wrapping around all the sides of the lower battery cell 1. The thin-film solar cell's coating or wrapping on its lower side is located on the insulating layer, and does not contact the sides of the intermediate series structure 4 with carrier conductivity, or has minimal contact area, greatly improving the power generation efficiency and production yield of the tandem photovoltaic device. Furthermore, the manufacturing process is simple and the production cost is low.

[0041] The tandem photovoltaic device shown in Figure 3 can be fabricated by first placing an insulating layer 2 on the entire side of the lower battery cell 1 and the intermediate series structure 4 after fabricating the lower battery cell 1 and the intermediate series structure 4. Then, the upper battery cell 3 is deposited on the light-facing surface of the intermediate series structure 4. The thin-film solar cell is coated or wrapped around the insulating layer on its lower side and does not come into contact with the side of the lower battery cell 1 and the intermediate series structure 4, which greatly improves the power generation efficiency and production yield of the tandem photovoltaic device. Moreover, the manufacturing process is simple and the production cost is low.

[0042] Figure 4 shows a schematic diagram of the fourth type of tandem photovoltaic device according to an embodiment of the present invention. Referring to Figure 4, the upper battery cell 3 includes a lower transport layer 31 near the lower battery cell 1. The lower transport layer 31 serves to separate and transport charge carriers from the upper battery cell. In this embodiment of the present invention, the material of the lower transport layer 31 is not specifically limited. For example, the material of the lower transport layer 31 can be titanium oxide. The insulating layer 2 also extends and wraps around all sides of the lower transport layer 31. Alternatively, the insulating layer 2 also extends and wraps around a portion of the sides of the lower transport layer 31. The thin-film solar cell is coated or coated around its lower side on the insulating layer and does not contact the side of the lower transport layer 31, which has charge carrier conduction capability, or the contact area with it is small, which greatly improves the power generation efficiency and production yield of the tandem photovoltaic device. Moreover, the manufacturing process is simple and the production cost is low. As shown in Figure 4, the insulating layer 2 not only covers all sides of the lower battery cell 1, but also covers all sides of the intermediate series structure 4, and covers all sides of the upper battery cell 3 near the lower transmission layer 31 of the lower battery cell 1.

[0043] The tandem photovoltaic device shown in Figure 4 can have an insulating layer 2 deposited on the entire side of the lower battery cell 1, intermediate series structure 4, and lower transmission layer 31, after the lower battery cell 1, intermediate series structure 4, and lower transmission layer 31. Then, the substrate 33 of the upper battery cell is deposited on the light-facing surface of the lower transmission layer 31. The thin-film solar cell is coated or wrapped around the insulating layer on its lower side, without contacting the side of the lower battery cell 1, intermediate series structure 4, and lower transmission layer 31. This significantly improves the power generation efficiency and production yield of the tandem photovoltaic device. Furthermore, the manufacturing process is simple and the production cost is low.

[0044] It should be noted that, in addition to covering all sides of the lower battery unit 1, the insulating layer 2 may not cover the sides of the intermediate series structure 4, but may instead cover all or part of the sides of the lower transmission layer 31 of the upper battery unit 3 near the lower battery unit 1.

[0045] The lower transmission layer 31 included in the upper battery cell 3 can be one or more layers shared by the upper battery cell 3 and the intermediate series structure 4. In this embodiment of the invention, no specific limitation is made. An intermediate series structure 4 may not be specifically provided between the upper battery cell 3 and the lower battery cell 1; some layers of the upper battery cell 3 can simultaneously perform the function of the intermediate series structure 4. In this embodiment of the invention, no specific limitation is made.

[0046] Optionally, the upper battery cell includes a buffer layer that serves as a lattice fitter. An insulating layer is also wrapped around all sides of the buffer layer, or partially wrapped around its sides. The thin-film solar cell's coating or wrapping on its lower side is located on the insulating layer, avoiding contact with the sides of the buffer layer which has charge carrier conductivity, or minimizing contact area. This significantly improves the power generation efficiency and production yield of the tandem photovoltaic device. Furthermore, the manufacturing process is simple and the production cost is low.

[0047] Optionally, referring to Figure 2, the tandem photovoltaic device further includes a lower functional film 6 located on the back surface of the lower battery cell. The lower functional film, located on the back surface of the lower battery cell, serves to collect and transport charge carriers, passivate the surface, and reduce reflection. The lower functional film 6 includes a back transport layer, which is located on the back surface of the lower battery cell and functions as a charge carrier transport layer. The insulating layer 2 extends and wraps around all sides of the back transport layer, or the insulating layer 2 extends and wraps around a portion of the back transport layer. The thin-film solar cell's coating or wrapping on its lower side is located on the insulating layer and does not contact the side of the back transport layer with charge carrier conduction capability, or the contact area is minimal, greatly improving the power generation efficiency and production yield of the tandem photovoltaic device. Furthermore, the manufacturing process is simple and the production cost is low. The lower functional film 6 may also include a back passivation layer and a back anti-reflection layer, etc.

[0048] For example, referring to Figure 5, which shows a schematic diagram of the fifth type of stacked photovoltaic device according to an embodiment of the present invention, the lower functional film 6 includes a back-side transmission layer. An insulating layer 2 extends and wraps around all sides of the back-side transmission layer. Simultaneously, the insulating layer 2 extends to the back-light surface of the lower functional film 6 and also extends and covers the light-facing surface of the intermediate series structure 4. In the stacked photovoltaic device shown in Figure 5, both the light-facing and back-light surfaces of the lower battery cell 1 are light-trapping structures, and the remaining layers are adapted to the light-trapping structures of the light-facing and back-light surfaces of the lower battery cell 1. The tandem photovoltaic device shown in Figure 5 can be fabricated by depositing an insulating layer 2 on the entire side surface of the lower functional film 6, the lower battery cell 1, and the intermediate series structure 4, as well as on the edge region of the light-facing side of the intermediate series structure 4 and the edge region of the backlight side of the lower functional film 6, after fabricating the lower functional film 6, the lower battery cell 1, and the intermediate series structure 4. Then, the upper battery cell 3 is deposited on the light-facing side of the intermediate series structure 4. The thin-film solar cell is coated or wrapped around the insulating layer on its lower side surface, without contacting the sides of the lower functional film 6, the lower battery cell 1, and the intermediate series structure 4. This significantly improves the power generation efficiency and production yield of the tandem photovoltaic device. Furthermore, the manufacturing process is simple and the production cost is low.

[0049] Optionally, referring to Figure 1, the thickness d of the insulating layer 2 is a dimension parallel to the light-facing surface of the upper battery cell 1. The thickness d of the insulating layer 2 is greater than or equal to 10 nm, and the insulating layer 2 is a single or multi-layer structure. The insulating layer 2 with the above-mentioned dimensions has good insulation effect. A thickness of only nm is required to achieve excellent electrical insulation effect. In tandem photovoltaic devices, the insulating layer 2 occupies little space, which is conducive to making full use of the area within the tandem photovoltaic device.

[0050] Optionally, referring to Figure 6, which shows a schematic diagram of the sixth type of stacked photovoltaic device according to an embodiment of the present invention, an insulating layer 2 is disposed on the light-facing surface of the lower battery cell 1. The insulating layer 2 disposed on the light-facing surface of the lower battery cell 1 has at least one through-hole 41, and each through-hole 41 is filled with conductive material. The insulating layer 2 disposed on the light-facing surface of the lower battery cell 1 and the conductive material filled in the through-hole 41 form an intermediate series structure 4. The conductive material in the through-hole 41 is a metallic structure or a transparent conductive material. Therefore, the area of ​​the light-facing surface of the lower battery cell 1, except for the through-hole 41, and the side surface of the lower battery cell 1 are all covered with the insulating layer 2. The thin-film solar cell is coated or coated on its lower side surface on the insulating layer, which greatly improves the power generation efficiency and production yield of the stacked photovoltaic device. Moreover, the manufacturing process is simple and the production cost is low.

[0051] Optionally, the insulation strength of insulation layer 2 is greater than or equal to 3MV / cm, and the insulation effect of insulation layer 2 is good.

[0052] Optionally, if the lower battery cell 1 is a crystalline silicon solar cell, the insulating layer 2 is silicon oxide (such as SiO2). x ) layer, silicon nitride (such as SiN) x ) layer, silicon oxyfluoride (such as SiOF) layer, silicon oxycarbonate (such as SiOC) layer, aluminum oxide (such as Al2O3) layer, aluminum fluoride (such as AlF) layer x The insulating layer 2 is selected from at least one of the following: an aluminum oxynitride (e.g., AlON) layer, and a magnesium fluoride (e.g., MgF2) layer. The above materials exhibit good electrical insulation properties, and the preparation process of the insulating layer 2 is similar to that of the passivation layer in a crystalline silicon solar cell. Existing production processes or equipment for the passivation layer of crystalline silicon solar cells can be directly used, without the need for additional equipment or processes, thus simplifying the process. It should be noted that the value of x in the chemical formula can be selected appropriately by those skilled in the art based on the actual situation.

[0053] For example, if the lower cell unit 1 is a crystalline silicon solar cell, the insulating layer 2 is a single layer of silicon nitride material with a thickness of 100 nm. As another example, if the lower cell unit 1 is a crystalline silicon solar cell, the insulating layer 2 is a single layer of aluminum oxide material with a thickness of 30 nm.

[0054] Optionally, when the lower battery cell 1 is a crystalline silicon solar cell, the insulating layer 2 includes a silicon oxide layer, an aluminum oxide layer, and a silicon nitride layer stacked sequentially. The silicon oxide layer is in contact with the lower battery cell. That is, during the fabrication of the insulating layer 2, the silicon oxide layer is first deposited on the side of the lower battery cell 1, then the aluminum oxide layer, and finally the silicon nitride layer. This insulating layer not only provides good electrical insulation but also utilizes existing crystalline silicon solar cell fabrication processes. Furthermore, the order of the three layers in the insulating layer conforms to the order of crystalline silicon solar cell fabrication, thus simplifying the fabrication process and increasing efficiency. The thickness of the three layers is not specifically limited; the total thickness of the three layers can be greater than or equal to 10 nm. For example, a silicon oxide layer of approximately 2 nm, an aluminum oxide layer of approximately 30 nm, and a silicon nitride layer of approximately 100 nm can all be fabricated using a deposition method.

[0055] The present invention also provides a method for manufacturing a tandem photovoltaic device, specifically including the following steps: Step S1, providing a lower battery cell; the lower battery cell has a light-facing surface and a back-lighting surface arranged opposite to each other, and a side surface connecting the light-facing surface and the back-lighting surface.

[0056] Step S2: Obtain an insulating layer at least covering the sides of the lower battery cell by deposition or growth.

[0057] Step S3: Prepare an intermediate series structure on the light-facing surface of the lower battery cell.

[0058] Step S4: Deposit the upper battery cell on the light-facing surface of the intermediate series structure; the lower battery cell is a thin-film solar cell.

[0059] The growth method can be epitaxial growth, and this is not specifically limited in this embodiment of the invention. The fabrication method of this tandem photovoltaic device can refer to the relevant description of the aforementioned tandem photovoltaic device, and has the same or similar beneficial effects as the aforementioned tandem photovoltaic device. To avoid repetition, it will not be described again here.

[0060] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A tandem photovoltaic device, characterized in that, The stacked photovoltaic device includes: an upper battery cell, a lower battery cell, and an intermediate series structure located between the upper battery cell and the lower battery cell; the upper battery cell is a thin-film solar cell; the lower battery cell has a light-facing surface and a back-lighting surface disposed opposite to each other, and a side surface connecting the light-facing surface and the back-lighting surface; the stacked photovoltaic device also includes an insulating layer at least wrapped around the side surface of the lower battery cell.

2. The tandem photovoltaic device according to claim 1, characterized in that, The insulating layer also extends to at least a portion of the side surface of the first layer; the first layer is a layer with charge carrier conductivity in the intermediate series structure, or the first layer is a layer with charge carrier conductivity in the portion of the upper battery cell near the intermediate series structure.

3. The tandem photovoltaic device according to claim 1 or 2, characterized in that, The insulating layer extends and covers the edge region of the light-facing side of the lower battery cell; and / or, the insulating layer extends and covers the edge region of the backlight side of the lower battery cell.

4. The tandem photovoltaic device according to claim 2, characterized in that, The insulating layer extends and covers the edge region of the light-facing side of the first layer; and / or, the insulating layer extends and covers the edge region of the backlight side of the first layer.

5. The tandem photovoltaic device according to claim 2, characterized in that, The first layer is the lower transmission layer that is close to the lower battery cell.

6. The tandem photovoltaic device according to claim 2, characterized in that, The upper battery cell includes a buffer layer; the insulating layer also extends to wrap around at least a portion of the sides of the buffer layer.

7. The tandem photovoltaic device according to claim 1 or 2, characterized in that, The tandem photovoltaic device further includes a lower functional film located on the back surface of the lower battery cell, the lower functional film including a back transmission layer; the insulating layer also extends to wrap around at least a portion of the side surface of the back transmission layer.

8. The tandem photovoltaic device according to claim 1 or 2, characterized in that, The thickness of the insulating layer is greater than or equal to 10 nm; the insulating layer is a single layer or multiple layers.

9. The tandem photovoltaic device according to claim 1 or 2, characterized in that, The insulating layer is disposed on the light-facing surface of the lower battery cell; the insulating layer disposed on the light-facing surface of the lower battery cell has at least one through hole, and each through hole is filled with conductive material; the insulating layer disposed on the light-facing surface of the lower battery cell and the conductive material filled in the through hole form the intermediate series structure.

10. The tandem photovoltaic device according to claim 1 or 2, characterized in that, The insulation strength of the insulation layer is greater than or equal to 3MV / cm.

11. The tandem photovoltaic device according to claim 1 or 2, characterized in that, When the lower battery cell is a crystalline silicon solar cell, the insulating layer is at least one of the following: silicon oxide layer, silicon nitride layer, silicon oxyfluoride layer, silicon oxycarbonate layer, aluminum oxide layer, aluminum fluoride layer, aluminum oxynitride layer, and magnesium fluoride layer.

12. The tandem photovoltaic device according to claim 11, characterized in that, The side insulating layer includes a silicon oxide layer, an aluminum oxide layer, and a silicon nitride layer stacked sequentially, wherein the silicon oxide layer is in contact with the lower battery cell.

13. A method for manufacturing a tandem photovoltaic device, characterized in that, The method includes the following steps: providing a lower battery cell; the lower battery cell having a light-facing surface and a back-light surface disposed opposite to each other, and a side surface connecting the light-facing surface and the back-light surface; obtaining an insulating layer at least covering the side surface of the lower battery cell by deposition or growth; fabricating an intermediate series structure on the light-facing surface of the lower battery cell; depositing an upper battery cell on the light-facing surface of the intermediate series structure; the lower battery cell being a thin-film solar cell.

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