Solar cell

Abstract

The utility model relates to the technical field of solar cells, and discloses a solar cell, which sequentially comprises a transparent protection layer, a current collection layer, a middle structure layer and a flexible substrate layer from top to bottom, and is characterized in that a main grid line of the current collection layer is exposed outside the solar cell; according to the utility model, the transparent protection layer is added on the surface of the flexible solar cell film layer, so that the cell film layer is isolated from water vapor and air, the cell film layer is effectively protected, the cell can be stored for a longer time before the cell is finally connected in series and packaged into an assembly, the service life of the cell is prolonged, and the production cost is reduced. Meanwhile, the phenomenon that the power generation performance is affected due to the fact that the battery pieces are scratched in the moving process is avoided; moreover, the transparent protective layer is made of a material with high light transmittance, so that the photoelectric conversion performance of the battery piece is not obviously influenced, the electrical property of the battery piece can be effectively maintained, and the electrical property stabilization time of the battery piece in the atmospheric environment is greatly prolonged.

Description

Technical Field

[0001] The utility model relates to the technical field of solar cells, in particular to a solar cell sheet. Background Art

[0002] In the environment of the continuous expansion of photovoltaic market installed capacity, crystalline silicon and thin film battery technology are constantly updated, and the new generation of solar cells - copper indium gallium selenide (CIGS) thin film solar cell technology is developing rapidly. CIGS thin film solar cells have a very broad development prospect, especially CIGS thin film solar cells with flexible materials as substrates, which have higher weight-to-power ratio, simple and convenient installation and disassembly, no hidden cracks, no hot spot phenomenon, and have more development potential.

[0003] CIGS thin-film solar cell materials are sensitive to water vapor and air oxidation. For film layers deposited on hard substrates such as glass, rapid lamination and packaging can be achieved after the cell is prepared. The cell film layer is less affected by environmental factors, and it is difficult for the cell efficiency to be affected by packaging factors. However, for film layers deposited on flexible substrates such as stainless steel foil and polyimide film, since the preparation process generally adopts a process of dividing a large cell into several small cells and then connecting them in series to form a component, before the cells are connected in series, the film layer will be exposed to the atmosphere for a long time, thereby being affected by environmental factors such as water vapor and oxygen, resulting in a decrease in cell performance and service life. In the prior art, after the preparation of flexible thin-film solar cells, there is also a solution of using a polymer transparent film for hot rolling for protection before lamination and packaging. This solution is to directly press the metal wire onto the surface of the cell as a grid for current collection. However, since the metal wire is easily peeled off during use, the connection reliability is reduced, which will increase the contact resistance and affect the current collection efficiency.

[0004] Therefore, how to maintain the power generation stability of flexible solar cells and extend their service life is an urgent problem to be solved by those skilled in the art. Utility Model Content

[0005] In view of this, the utility model provides a solar cell to solve the problem that the power generation performance and service life of the existing flexible solar cells are reduced due to long-term exposure to the air or movement before they are finally packaged in series to form a component, and the metal wire is directly pressed and attached to the surface of the cell as a grid to collect current, thereby affecting the current collection efficiency.

[0006] In order to solve the above technical problems, the utility model adopts the following technical solutions:

[0007] The utility model provides a solar cell sheet, which comprises a transparent protective layer, a current collection layer, an intermediate structure layer and a flexible substrate layer from top to bottom, and the main grid line of the current collection layer is exposed outside the solar cell sheet.

[0008] Preferably, the transparent protective layer has a visible light transmittance of ≥80% and a water vapor transmittance of ≤0.01 g / (m 2 ·24h).

[0009] Preferably, the transparent protective layer is made of epoxy resin adhesive material, and the thickness of the transparent protective layer is 10-200 μm.

[0010] Preferably, the transparent protective layer is made of an inorganic silicon-based material, and the thickness of the transparent protective layer is 0.5-100 μm.

[0011] Preferably, the flexible substrate layer is made of stainless steel foil or polyimide film, and the thickness of the flexible substrate layer is 15-150 μm.

[0012] Preferably, the thickness of the intermediate structural layer is 1.5-3 μm.

[0013] Preferably, the current collection layer is made of conductive silver paste, and the thickness of the current collection layer is 10-30 μm.

[0014] The utility model provides a solar cell, which has the following beneficial effects compared with the prior art:

[0015] The utility model adds a transparent protective layer on the surface of the flexible solar cell film layer to isolate the cell film layer from water vapor and air, thereby effectively protecting the cell film layer, so that the cell can be stored for a longer time before being finally packaged in series to form a component, thereby extending the service life of the cell and also preventing the cell from being scratched during movement and affecting the power generation performance; and, because the transparent protective layer of the utility model is made of a material with high light transmittance, the photoelectric conversion performance of the cell is not significantly affected, the electrical characteristics of the cell can be effectively maintained, and the electrical performance stability time of the cell in the atmospheric environment is greatly improved.

[0016] In addition, the utility model uses transparent materials to protect the cell film layer without changing the condition of using conductive silver paste to collect current, which can fully maintain the electrical performance of the cell and effectively avoid mechanical damage during subsequent processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0018] Figure 1 This is a schematic diagram of the external structure of the solar cell of the utility model;

[0019] Figure 2 It is a schematic diagram of the cross-sectional structure of the solar cell of the utility model.

[0020] In the figure: 100 - solar cell film layer, 110 - flexible substrate layer, 120 - intermediate structure layer, 130 - current collection layer, 131 - main grid line, 200 - transparent protective layer. DETAILED DESCRIPTION

[0021] The embodiments of the present invention are described in detail below, and the examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limitations on the present invention. If specific techniques or conditions are not indicated in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are followed. The reagents or instruments used that do not indicate the manufacturer are all conventional products that can be obtained commercially.

[0022] In one aspect of the utility model, the utility model provides a solar cell, which comprises a transparent protective layer 200, a current collection layer 130, an intermediate structure layer 120 and a flexible substrate layer 110 from top to bottom, and the visible light transmittance of the transparent protective layer 200 is ≥80%, and the water vapor transmittance is ≤0.01g / (m 2 ·24h). The current collection layer 130 , the intermediate structure layer 120 and the flexible substrate layer 110 together constitute the solar cell film layer 100 , and the transparent protective layer 200 covers the surface of the solar cell film layer 100 .

[0023] It is understandable that if the visible light transmittance is too low, the intensity of visible light passing through the transparent protective layer will be small, which will cause the photoelectric conversion efficiency of the solar cell to decrease; if the water vapor transmittance is too high, when stored in the atmospheric environment, the water vapor in the air will easily pass through the transparent protective layer to corrode the functional layer of the solar cell, causing the photoelectric conversion efficiency of the solar cell to decrease.

[0024] The utility model isolates the flexible thin-film solar cell film layer 100 from the atmosphere by adding a transparent protective layer 200, thereby extending the life of the cell before lamination and packaging, making it easier to separate and connect the front-end process of the cell and the back-end lamination and packaging process, and creating buffering conditions; in addition, by adding the transparent protective layer 200, the cell film layer can be fully protected to prevent it from being mechanically scratched and worn during the processes of testing, series connection and packaging.

[0025] Optionally, the transparent protective layer 200 is made of epoxy resin adhesive material, and the thickness of the transparent protective layer 200 is 10-200 μm, preferably 50-200 μm.

[0026] When the transparent protective layer 200 is made of epoxy resin glue material, the transparent protective layer 200 is formed by coating the epoxy resin glue material on the surface of the current collection layer 130 using screen printing technology and then curing it; or the transparent protective layer 200 is formed by spraying the epoxy resin glue material on the surface of the current collection layer 130 using electrostatic spraying technology and then curing it.

[0027] Optionally, the transparent protective layer 200 is made of inorganic material, and the thickness of the transparent protective layer 200 is 0.5-100 μm. Further, the inorganic material includes SiO2, Si3N4 or SiO x N y Any one or more of the .

[0028] When the transparent protective layer 200 is made of inorganic material, the transparent protective layer 200 is formed by depositing an inorganic material thin film on the surface of the current collection layer 130 using magnetron sputtering coating technology, that is, a transparent SiO2, Si3N4 or SiO2 is deposited on the surface of the current collection layer 130. x N y Thin film, high purity Si is used as target material during film coating, and a mixed gas of Ar, O2 and / or N2 is used as reaction gas. That is, Ar is essential in the reaction gas, and in addition to Ar, at least one gas of O2 and N2 is also included. For example, a mixed gas of Ar and O2 is used when preparing SiO2, a mixed gas of Ar and N2 is used when preparing Si3N4, and a mixed gas of SiO x N y A mixed gas of Ar, O2 and N2 is used.

[0029] The utility model adopts epoxy resin glue or inorganic silicon-based compounds as the transparent protective layer 200 of the flexible solar cell film layer 100, which can effectively maintain the electrical characteristics of the cell and prevent the cell from being mechanically damaged. The transparent protective layer 200 is prepared by screen printing, electrostatic spraying or magnetron sputtering, and the process is simple and convenient, easy to control and low in cost.

[0030] In addition, the main performance requirements of the transparent protective layer 200 of the utility model are the visible light transmittance and water vapor transmittance. The inherent characteristics of different materials and their preparation methods will affect these two indicators. For epoxy resin glue, the structural density after curing is weaker than that of inorganic Si-based thin film materials, so a thicker film layer is required to ensure that the water vapor transmittance meets the requirements, and generally speaking, the control accuracy of electrostatic spraying on film thickness is also weaker than that of magnetron sputtering. Therefore, when the transparent protective layer 200 adopts epoxy resin glue material, the thickness of the film layer is thicker, and when the transparent protective layer 200 adopts inorganic materials, only a thinner film layer is required to meet the requirements of the two indicators. However, considering that the manufacturing cost of using inorganic materials as the transparent protective layer 200 is relatively high and the thicker film layer will lead to a decrease in visible light transmittance, after comprehensive consideration and experimental verification, the visible light transmittance of the transparent protective layer 200 is limited to not less than 80%, and the water vapor transmittance is not more than 0.01g / (m 2 ·24h).

[0031] Optionally, the flexible substrate layer 110 is made of stainless steel foil or polyimide film, and the thickness of the flexible substrate layer 110 is 15-150 μm; the intermediate structure layer 120 is Mo / CIGS / CdS / ZnO / AZO, and the thickness of the intermediate structure layer 120 is 1.5-3 μm.

[0032] Optionally, the current collection layer 130 is formed of a conductive silver paste, and the main grid lines 131 of the current collection layer 130 are exposed outside the solar cell, and the thickness of the current collection layer 130 is 10-30 μm.

[0033] It can be understood that the exposure of the main grid line 131 can fully reveal the positive and negative lead parts of the battery cell on the flexible substrate without affecting the execution of subsequent processes. At the same time, the transparent protective layer 200 can fully protect the battery cell film layer without affecting the performance of the component after series connection, and avoid the movement of the battery cell from affecting the quality and aesthetics of the series connection of the component. In addition, under the condition of keeping the main grid line 131 fully exposed, the utility model can use conductive glue and tin-copper tape to connect the main grid line 131 part, which will not affect the current collection of the battery cell, so as to further ensure that the performance of the battery cell remains stable when stored for a long time.

[0034] In the prior art, after the preparation of the flexible thin-film solar cell is completed, there is also a scheme of using a polymer transparent film for hot rolling for protection before lamination packaging. This scheme is to directly press and attach the metal wire to the surface of the cell as a grid for current collection. However, since the metal wire is easy to peel off during use, the connection reliability is reduced, which will increase the contact resistance and affect the current collection efficiency. The utility model uses a transparent material to protect the cell film layer without changing the condition of using conductive silver paste to collect current, which can fully maintain the electrical performance of the cell and effectively avoid mechanical damage during subsequent processes.

[0035] On the other hand, the utility model also provides a method for preparing a solar cell of any of the above items, comprising the following steps: preparing an intermediate structure layer 120 on a flexible substrate layer 110 to form a battery device structure, forming a current collection layer 130 on the battery device structure, and the current collection layer 130 has a main grid line 131 led out, and forming a transparent protective layer 200 on the current collection layer 130 except the main grid line 131 area to obtain a solar cell.

[0036] The utility model directly adds a protective layer on the surface of the flexible thin-film solar cell sheet, which can be easily realized by sequentially adding it to the original cell sheet preparation process flow, with a high degree of process matching, and does not affect the subsequent packaging application of the cell chip. The production method is simple and convenient, with low cost, and is suitable for industrial production.

[0037] The utility model is described below by specific embodiments, and it will be appreciated by those skilled in the art that the following specific embodiments are only for illustrative purposes, and do not limit the scope of the utility model in any way. In addition, in the following embodiments, unless otherwise specified, the reagents and equipment used are all commercially available. If in the following embodiments, specific processing conditions and processing methods are not clearly described, then conditions and methods known in the art can be used to process.

[0038] Example 1

[0039] This embodiment provides a method for preparing a flexible copper indium gallium selenide thin film solar cell, comprising the following steps:

[0040] (1) A Mo / CI GS / CdS / ZnO / AZO film layer structure was prepared on a stainless steel foil substrate to form an intermediate structure layer, thereby completing the front-end process of a flexible CI GS thin-film solar cell and forming a complete battery device structure; then a current collection layer and a conductive silver paste main grid line were prepared by screen printing to collect current. The width of the main grid line was 2 mm, and the drying temperature after screen printing was 200°C for 20 min.

[0041] (2) Epoxy resin glue is used for secondary screen printing and drying and curing process, leaving the conductive silver paste main grid line area without printing, and the rest of the area is completely covered. The drying and curing temperature after screen printing is 70°C and the time is 60 minutes to form a transparent protective layer with a thickness of 150 μm, thereby protecting the film layer of the flexible copper indium gallium selenide thin-film solar cell.

[0042] (3) Connect the exposed main grid lines of the battery cell using conductive glue and tin-copper tape to draw out the current.

[0043] Table 1

[0044]

[0045]

[0046] As shown in Table 1, there are the performance parameters of the solar cell before being coated with epoxy resin glue, the performance parameters of the solar cell coated with epoxy resin glue after being left standing in an atmospheric environment at room temperature for 6 months, and the performance parameters of the solar cell not coated with epoxy resin glue after being left standing in an atmospheric environment at room temperature for 6 months. After the film layer of the solar cell coated with epoxy resin glue has been left standing for 6 months, the cell efficiency has changed very little, while after the film layer of the solar cell not coated with epoxy resin glue has been left standing for 6 months, the cell efficiency has changed greatly, indicating that the epoxy resin glue can effectively protect the surface of the cell without affecting the cell efficiency.

[0047] Example 2

[0048] This embodiment provides a method for preparing a flexible copper indium gallium selenide thin film solar cell, comprising the following steps:

[0049] (1) A Mo / CI GS / CdS / ZnO / AZO film layer structure was prepared on a stainless steel foil substrate to form an intermediate structure layer, thereby completing the front-end process of a flexible CI GS thin-film solar cell and forming a complete battery device structure; then a current collection layer and a conductive silver paste main grid line were prepared by screen printing to collect current. The width of the main grid line was 2 mm, and the drying temperature after screen printing was 200°C for 20 min.

[0050] (2) The conductive silver paste main grid line is covered with a mask, and then a SiO2 film layer is deposited on the surface of the cell by magnetron sputtering technology. The sputtering target is a high-purity Si target, the reaction gas is a mixture of Ar and O2, the sputtering pressure is 0.5-1Pa, and the thickness of the SiO2 film layer is 30μm, forming a transparent protective layer to protect the film layer of the flexible copper indium gallium selenide thin-film solar cell.

[0051] (3) Connect the exposed main grid lines of the battery cell using conductive glue and tin-copper tape to draw out the current.

[0052] Table 2

[0053]

[0054] Table 2 shows the performance parameters of the solar cell before the inorganic SiO2 film is deposited, the performance parameters of the solar cell after the inorganic SiO2 film is deposited when it is left standing in an atmospheric environment at room temperature for 6 months, and the performance parameters of the solar cell without the inorganic SiO2 film being deposited when it is left standing in an atmospheric environment at room temperature for 6 months. The cell efficiency of the solar cell with the inorganic SiO2 film deposited on it changes little after standing for 6 months, while the cell efficiency of the solar cell without the inorganic SiO2 film deposited on it changes greatly after standing for 6 months, indicating that the inorganic SiO2 film effectively protects the surface of the cell without affecting the cell efficiency.

[0055] In the description of this specification, the descriptions with reference to the terms "one embodiment", "another embodiment", "yet another embodiment", "some embodiments", "some specific embodiments", "some other specific embodiments", etc., mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment are included in at least one embodiment of the utility model. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples, unless they are contradictory. In addition, it should be noted that in this specification, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated.

[0056] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations of the present invention. Ordinary technicians in the field can change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A solar cell, characterized in that: The solar cell sheet comprises a transparent protective layer, a current collection layer, an intermediate structure layer and a flexible substrate layer in order from top to bottom, and the main grid line of the current collection layer is exposed outside the solar cell sheet.

2. The solar cell according to claim 1, characterized in that: The visible light transmittance of the transparent protective layer is ≥80%, and the water vapor transmittance is ≤0.01g / (m 2 ·24h).

3. The solar cell according to claim 1, characterized in that: The transparent protective layer is made of epoxy resin adhesive material, and the thickness of the transparent protective layer is 10-200 μm.

4. The solar cell according to claim 1, characterized in that: The transparent protective layer is made of inorganic silicon-based material, and the thickness of the transparent protective layer is 0.5-100 μm.

5. The solar cell according to claim 1, characterized in that: The flexible substrate layer is made of stainless steel foil or polyimide film, and the thickness of the flexible substrate layer is 15-150 μm.

6. The solar cell according to claim 1, characterized in that: The thickness of the intermediate structural layer is 1.5-3 μm.

7. The solar cell according to claim 1, characterized in that: The current collection layer is made of conductive silver paste, and the thickness of the current collection layer is 10-30 μm.

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