A functional film containing a back electrode and a thin-film photovoltaic module and a preparation method thereof

Abstract

The present invention relates to a functional film containing a back electrode, comprising a flexible substrate and a back electrode deposited on the upper surface of the flexible substrate, wherein a line is engraved on the back electrode to cut the back electrode into a plurality of back electrode strips, and a positive lead-out terminal and a negative lead-out terminal are respectively provided on the back electrode, and a positive busbar and a negative busbar are welded to the positive lead-out terminal and the negative lead-out terminal, respectively. The present invention also discloses a preparation method of the functional film, a thin-film photovoltaic module using the functional film, and a preparation method thereof. The present invention provides a busbar at the lead-out terminal of the back electrode, thereby avoiding damage to the positive and negative connection terminals of the module during the lamination process after the busbar is laid in the active area in the traditional process. At the same time, since the back electrode and the flexible substrate are prepared in advance and then laid on the second carrier transport layer, they are not restricted by the process sequence of preparing the thin-film photovoltaic module, shortening the time of preparing the thin-film photovoltaic module at that time and improving the production efficiency of the thin-film photovoltaic module.

Description

Technical Field

[0001] The present invention belongs to the technical field of photovoltaic module preparation, and in particular relates to a functional film containing a back electrode and a thin-film photovoltaic module and a preparation method thereof. Background Art

[0002] Adhesive films are frequently used in photovoltaic modules. They provide protection, high-temperature resistance, improved moisture tolerance, sound insulation, and enhanced mechanical strength. Thin-film photovoltaic modules are fragile due to the thin thickness of the functional layers, typically less than 1µm in total. This places relatively high demands on encapsulation technology. When conventional encapsulation films are applied directly to the back of the active area of a module and laminated using traditional processes, the hot-melt adhesive, the film's primary component, often shrinks due to temperature fluctuations, causing the module's back electrode to adhere to the film, ultimately resulting in significant performance degradation. Therefore, a flexible backing is often used to protect the module's back electrode from adhesion.

[0003] Typically, the back electrode is connected to an external junction box through a perforation on the back of the module. However, this packaging method is not suitable for thin-film photovoltaic modules, as the sealant (commonly silicone) used in the perforation does not have good moisture barrier properties. Using a busbar to run through the positive and negative electrodes of the cell and lead them out is one solution to the poor sealing of the junction box. However, when different modules need to be connected in series or parallel, the busbar cannot be directly welded to the film surface, so a back electrode lead-out terminal is required. However, after lamination, the protrusions of the busbar put long-term pressure on the positive and negative electrodes, accelerating damage to the film interface and reducing cell performance. Therefore, it is urgent to find new packaging methods to solve these problems.

[0004] On the other hand, in the existing thin film photovoltaic module preparation process, such as Figure 1 As shown, a first carrier transport layer 2', a light absorbing layer 3', and a second carrier transport layer 4' are sequentially prepared on a conductive substrate 1' that has undergone laser P1 cutting. Laser P2 cutting is then performed before the back electrode 5' is prepared. Laser P3 cutting is then performed. A flexible substrate 6' and adhesive film 7' are then applied to the back electrode 5'. Busbars (not shown) are applied to the positive and negative electrodes of the back electrode 5'. Butyl adhesive is applied around the module, followed by backplane glass 8'. The assembled components are then placed in a laminator for lamination to produce the finished thin-film photovoltaic module. This process has the following drawbacks:

[0005] 1. The busbars that contact the positive and negative ends of the back electrode will exert pressure on the positive and negative ends of the module after lamination, causing damage to the back electrode film layer and reducing battery performance;

[0006] 2. Each film layer of the module is prepared sequentially, which makes the whole process long and takes a long time to prepare the module. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a functional film containing a back electrode, a thin-film photovoltaic module, and a method for preparing the same. A busbar is provided at the lead-out end of the back electrode, thereby avoiding damage to the positive and negative terminal connections of the module during the lamination process after the busbar is applied to the active area in the traditional process. Furthermore, by pre-preparing the back electrode and flexible substrate and then applying them to the second carrier transport layer, the existing continuous process for preparing thin-film photovoltaic modules is divided into two steps, freeing the thin-film photovoltaic module from the process sequence, shortening the time required to prepare the thin-film photovoltaic module, and improving the production efficiency of the thin-film photovoltaic module.

[0008] The present invention is implemented in this way: a functional film containing a back electrode is provided, including a flexible substrate and a back electrode deposited on the upper surface of the flexible substrate. Lines are engraved on the back electrode to cut the back electrode into multiple back electrode strips. A positive lead-out terminal and a negative lead-out terminal are also provided on the back electrode, and a positive bus strip and a negative bus strip are respectively welded to the positive lead-out terminal and the negative lead-out terminal.

[0009] Furthermore, the positive bus strip and the negative bus strip are respectively welded to the positive electrode lead-out terminal and the negative electrode lead-out terminal by polymer, and the material of the polymer includes any one of polypropylene, polyethylene, polyvinyl chloride, polytetrafluoroethylene, polyethylene tetrafluoroethylene, polymethyl methacrylate, polyethylene terephthalate, polystyrene, polyimide, polyamide, nylon, polyvinyl alcohol and polylactic acid.

[0010] Furthermore, a back electrode protection film is adhered to the lower surface of the flexible substrate.

[0011] Furthermore, the material of the back electrode protective film includes any one of polyurethane, ethylene-vinyl acetate copolymer, ethylene octene copolymer and polyvinyl butyral.

[0012] The present invention is achieved by providing a method for preparing the functional film containing the back electrode as described above, comprising the following steps:

[0013] Step 1: depositing a back electrode on the upper surface of the flexible substrate, scribing the back electrode, and cutting the back electrode into a plurality of back electrode strips;

[0014] Step 2: Weld the positive busbar and the negative busbar onto the positive lead-out terminal and the negative lead-out terminal of the back electrode respectively.

[0015] Furthermore, step one further includes the following step: pasting a back electrode protection film on the lower surface of the flexible substrate.

[0016] The present invention is achieved by providing a thin-film photovoltaic module, whose internal structure includes, from bottom to top, a lower encapsulation glass, a flexible substrate, a back electrode, a second carrier transport layer, a light absorption layer, a first carrier transport layer, a front electrode layer and an upper encapsulation glass, and encapsulation glue is arranged on the sides of the lower encapsulation glass and the upper encapsulation glass, wherein the back electrode and the flexible substrate are the functional film containing the back electrode as described above, or are the functional film containing the back electrode prepared by the preparation method of the functional film containing the back electrode as described above, the functional film containing the back electrode is prepared in advance, and a P2 line is provided on the second carrier transport layer, and the line engraved on the back electrode corresponds to the P2 line of the second carrier transport layer.

[0017] Furthermore, a back electrode protection film is provided between the lower encapsulation glass and the flexible substrate, and the back electrode protection film is adhered to the lower surface of the flexible substrate.

[0018] The present invention is achieved by providing a method for preparing a thin-film photovoltaic module as described above, comprising the following steps:

[0019] Step 1: depositing a back electrode on the upper surface of the flexible substrate, scribing the back electrode, and cutting the back electrode into a plurality of back electrode strips;

[0020] Step 2: Welding a positive bus tape and a negative bus tape onto the positive electrode lead-out terminal and the negative electrode lead-out terminal of the back electrode, respectively, to obtain a functional film containing the back electrode;

[0021] Step 3: Prepare a front electrode layer on the upper encapsulation glass and scribe a P1 line on the front electrode layer;

[0022] Step 4: sequentially prepare a first carrier transport layer, a light absorbing layer, and a second carrier transport layer on the front electrode layer, and scribe a P2 line on the second carrier transport layer;

[0023] Step 5: Lay the functional film containing the back electrode prepared in step 2 on the second carrier transport layer, wherein the scribe line on the back electrode corresponds to the P2 scribe line of the second carrier transport layer, lay the lower encapsulation glass on it, and lay or apply encapsulation glue on its side;

[0024] Step 6: Place the laid components together into the laminator for lamination.

[0025] Furthermore, step 1 further includes the following step: pasting a back electrode protection film on the lower surface of the flexible substrate.

[0026] Compared with the prior art, the functional film containing the back electrode and the thin-film photovoltaic module and the preparation method thereof of the present invention pre-prepare the flexible substrate surface of the back electrode, and respectively weld the positive bus tape and the negative bus tape on the positive lead-in terminal and the negative lead-in terminal of the back electrode, and then lay them on the second carrier transport layer to enter the next packaging process. This not only avoids the damage to the positive and negative electrode connection terminals of the module caused by the lamination process after laying the bus tape in the active area in the traditional process, but also shortens the time for preparing the thin-film photovoltaic module at that time, thereby improving the production efficiency of the thin-film photovoltaic module. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of the internal structure of an existing thin-film photovoltaic module;

[0028] Figure 2 Schematic diagram of the internal structure of a preferred embodiment of the functional film containing a back electrode of the present invention;

[0029] Figure 3 Schematic diagram of a plan view of a functional film containing a back electrode of the present invention;

[0030] Figure 4 Schematic diagram of the internal structure of the thin-film photovoltaic module of the present invention;

[0031] Figure 5 This is a schematic diagram of the internal structure of a thin-film photovoltaic module according to embodiment 1 of the present invention;

[0032] Figure 6 This is a schematic diagram of the internal structure of the thin-film photovoltaic module embodiment 2 of the present invention. DETAILED DESCRIPTION

[0033] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0034] Please refer to Figure 2 as well as Figure 3 As shown, a preferred embodiment of the functional film containing a back electrode of the present invention includes a flexible substrate 1, a back electrode 2 deposited on the upper surface of the flexible substrate 1, and a back electrode protective adhesive film 3 attached to the lower surface of the flexible substrate 1. The thickness of the functional film containing the back electrode is 0.4 mm to 2 mm.

[0035] Lines are engraved on the back electrode 2 to cut the back electrode 2 into multiple back electrode strips 21. A positive lead-out terminal 22 and a negative lead-out terminal 23 are also provided on the back electrode 2. A positive busbar 4 and a negative busbar 5 are welded to the positive lead-out terminal 22 and the negative lead-out terminal 23 respectively.

[0036] The positive busbar 4 and negative busbar 5 are welded to the positive electrode lead terminal 22 and the negative electrode lead terminal 23, respectively, via a polymer 6. The polymer 6 can be made of any of polypropylene, polyethylene, polyvinyl chloride, polytetrafluoroethylene, polyethylene tetrafluoroethylene, polymethyl methacrylate, polyethylene terephthalate, polystyrene, polyimide, polyamide, nylon, polyvinyl alcohol, and polylactic acid. The melting temperature of the polymer 6 is between 100°C and 300°C. The positive busbar 4 and negative busbar 5 are made of tinned copper strips.

[0037] The material of the back electrode protection film 3 includes any one of polyurethane, ethylene-vinyl acetate copolymer, ethylene octene copolymer and polyvinyl butyral.

[0038] The material of the flexible substrate 1 includes any one of flexible Willow glass, polyimide, polyethylene terephthalate, and polyethylene tetrafluoroethylene.

[0039] The present invention also discloses a method for preparing the functional film containing the back electrode as described above, comprising the following steps:

[0040] Step 1: deposit a back electrode 2 on the upper surface of the flexible substrate 1 , adhere a back electrode protective film 3 on the lower surface of the flexible substrate 1 , scribe the back electrode 2 , and cut the back electrode 2 into a plurality of back electrode strips 21 .

[0041] Step 2: Weld the positive busbar 4 and the negative busbar 5 onto the positive lead-out terminal 22 and the negative lead-out terminal 23 of the back electrode 2 respectively.

[0042] Please refer to Figure 4 As shown, the present invention also discloses a thin-film photovoltaic module, whose internal structure, from bottom to top, includes a lower encapsulating glass 7, a back electrode protective adhesive film 3, a flexible substrate 1, a back electrode 2, a second carrier transport layer 8, a light absorbing layer 9, a first carrier transport layer 10, a front electrode layer 11, and an upper encapsulating glass 12. Encapsulating adhesive 13 is provided on the sides of the lower encapsulating glass 7 and the upper encapsulating glass 12 to seal the layers from the back electrode protective adhesive film 3 to the front electrode layer 11 between the lower encapsulating glass 7 and the upper encapsulating glass 12. The back electrode 2 and the flexible substrate 1 are the functional films containing the back electrode as described above, or are functional films containing the back electrode prepared using the method for preparing the functional films containing the back electrode as described above. The functional film containing the back electrode is pre-prepared, and a P2 scribe line is provided on the second carrier transport layer 8 to expose the bottom front electrode layer 11. The back electrode 2 of the functional film containing the back electrode is correspondingly applied to the surface of the second carrier transport layer 8, and the scribe line engraved on the back electrode 2 corresponds to the P2 scribe line of the second carrier transport layer 8.

[0043] Among them, thin-film photovoltaic modules include perovskite solar cell modules and organic solar cell modules.

[0044] The present invention also discloses a method for preparing the thin-film photovoltaic module as described above, comprising the following steps:

[0045] Step 1: Deposit a back electrode 2 on the upper surface of a flexible substrate 1 and adhere a back electrode protective film 3 to the lower surface of the flexible substrate 1. Scribe the back electrode 2 and cut it into a plurality of back electrode strips 21.

[0046] Step 2: Welding the positive bus tape 4 and the negative bus tape 5 onto the positive electrode lead-out terminal 22 and the negative electrode lead-out terminal 23 of the back electrode 2 respectively to obtain a functional film containing the back electrode.

[0047] Step 3: Prepare a front electrode layer 11 on the upper encapsulation glass 12 and scribe a P1 line on the front electrode layer 11 .

[0048] Step 4: sequentially prepare a first carrier transport layer 10 , a light absorption layer 9 and a second carrier transport layer 8 on the front electrode layer 11 , and scribe a P2 line on the second carrier transport layer 8 .

[0049] Step 5: Lay the functional film containing the back electrode prepared in step 2 on the second carrier transport layer 8, wherein the line engraved on the back electrode 2 corresponds to the P2 line of the second carrier transport layer 8, lay the lower encapsulation glass 7 on it, and lay or apply the encapsulation glue 13 on its side.

[0050] Step 6: Place the laid components together into the laminator for lamination.

[0051] The preparation method of the thin-film photovoltaic module has the following characteristics:

[0052] 1. The busbars are directly fixed to the positive and negative terminals of the back electrode to avoid damage to the active area film layer of the component during lamination.

[0053] 2. Directly using the pre-prepared functional film containing the back electrode when preparing and packaging components can save time in preparing the components at that time. This not only breaks the constraints of the existing process and increases the flexibility of preparing components, but also improves the production efficiency of preparing components.

[0054] The following further illustrates the method for preparing the functional film containing a back electrode and the thin-film photovoltaic module of the present invention with reference to specific examples.

[0055] Example 1

[0056] Please refer to Figure 5 As shown, the first embodiment of the method for preparing the functional film containing the back electrode and the thin-film photovoltaic module of the present invention, taking the thin-film perovskite solar cell module as an example, comprises the following steps:

[0057] Step 11: Prepare the hole transport layer of the perovskite solar cell. Laser-cut P1 lines are drawn on the upper encapsulating glass substrate 12 containing the front electrode layer 11 to separate the cells into 20 sub-cells. A TiO2 electron transport layer is applied as the first carrier transport layer 10, sintered at 500°C for half an hour, cooled to room temperature, and then coated with a PbI2 DMSO solution. The layer is then immersed in an MAI isopropanol solution for half a minute and annealed at 100°C for one hour to obtain the methylamine lead iodine light-absorbing layer 9. A 0.788M solution of Spiro-OMeTAD in chlorobenzene, a 0.0659M solution of 4-tert-butylpyridine, and a 0.018M solution of lithium bis(trifluoromethanesulfonyl)imide are applied to the surface to prepare a Spiro-OMeTAD hole transport layer as the second carrier transport layer 8. Laser-cut P2 lines are drawn on the Spiro-OMeTAD hole transport layer.

[0058] Step 12: Using a coating template, evaporate a 100nm thick gold electrode onto the flexible substrate 1 (flexible willow glass substrate) to serve as the back electrode 2 and the positive and negative lead terminals of the gold electrode. Laser-segment the entire gold electrode into 20 back electrode strips for the sub-cells.

[0059] Step 13: Cover the back electrode of the flexible willow substrate with a layer of willow substrate to protect it from scratches during lamination. Apply adhesive film to the side without the gold electrode, and PTFE film underneath. Lamination is performed at 90°C, a pressure of 60 kPa, and a lamination time of 5 minutes. After cooling, remove the top willow substrate and tear off the bottom PTFE film to obtain the EVA film with the gold electrode as the back electrode protective film 3.

[0060] Step 14: Secure the tinned copper strips as busbars to the positive and negative leads of the gold electrodes. Place the tinned copper strips at the ends of the positive and negative leads of the gold electrodes. Use a hot melt spray gun at 150°C to quickly spray molten polypropylene onto the connection between the tinned copper strips and the gold electrodes. Once the polypropylene cools, the tinned copper strips are secured to the EVA film containing the gold electrodes, resulting in a functional film containing the back electrode.

[0061] Step 15: Encapsulate the perovskite photovoltaic module with an EVA film containing gold electrodes. Place the functional film containing the back electrode, prepared in Step 14, with the gold electrode side facing the Spiro-OMeTAD hole transport layer, and align it at the laser cut line. Then, apply a layer of butyl rubber around the active area of the module, and place the backplane glass at the bottom. Both are then placed in a laminator for lamination. Lamination temperature: 100°C, pressure: 90 kPa, lamination time: 15 minutes.

[0062] Example 2

[0063] Please refer to Figure 6As shown, the second embodiment of the method for preparing the functional film containing the back electrode and the thin-film photovoltaic module of the present invention, taking the thin-film perovskite solar cell module as an example, comprises the following steps:

[0064] Step 21: Prepare the perovskite solar cell up to the hole transport layer. Laser-cut P1 lines are scribed on the upper encapsulating glass substrate 12 containing the ITO front electrode layer 11, dividing the cells into 20 sub-cells. Subsequently, a MoO3 hole transport layer is evaporated as the first carrier transport layer 10. PTB7:PC71BM is then evaporated as the light absorption layer 9 and a LiF electron transport layer is evaporated as the second carrier transport layer 8. Laser-cut P2 lines are then scribed on the LiF electron transport layer.

[0065] Step 22: Use a coating template to deposit a 100nm thick aluminum electrode onto the flexible substrate 1 (polyimide) to serve as the back electrode 2 and the positive and negative terminals of the aluminum electrode. Use a laser to separate the entire aluminum electrode into 20 back electrode strips for the sub-cells.

[0066] Step 23: Cover the polyimide substrate back electrode 2 with a piece of tempered glass to protect it from scratches during lamination. Apply adhesive film to the side without the aluminum electrode, and PTFE film underneath. Lamination is performed at 90°C, a pressure of 60 kPa, and a lamination time of 5 minutes. After cooling, remove the top tempered glass and tear off the bottom PTFE film. This will yield an EVA film with an aluminum electrode as the back electrode protective film 3.

[0067] Step 24: Secure the tinned copper strips as busbars to the positive and negative leads of the aluminum electrodes. Place the tinned copper strips at both ends of the positive and negative leads of the aluminum electrodes. Use a hot melt spray gun at 150°C to quickly spray molten polypropylene onto the connection between the tinned copper strips and the aluminum electrodes. After the polypropylene cools, the tinned copper strips are secured to the EVA film containing the aluminum electrodes, resulting in a functional film containing the back electrode.

[0068] Step 25: Encapsulate the perovskite photovoltaic module using an EVA film containing an aluminum electrode. Lay the functional film containing the back electrode, prepared in Step 24, with the aluminum electrode facing the LiF electron transport layer, and align it at the laser cut line. Then, apply a layer of butyl rubber around the active area of the module, and place the backsheet glass at the bottom. Both are then placed in a laminator for lamination. Lamination temperature: 100°C, pressure: 90 kPa, time: 15 minutes.

[0069] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A thin-film photovoltaic module, characterized in that: Its internal structure includes, from bottom to top, a lower encapsulation glass, a flexible substrate, a back electrode, a second carrier transport layer, a light absorption layer, a first carrier transport layer, a front electrode layer, and an upper encapsulation glass. Encapsulation glue is provided on the sides of the lower encapsulation glass and the upper encapsulation glass. The back electrode and the flexible substrate are functional films containing the back electrode. The functional film containing the back electrode is prepared in advance. A P2 scribe line is provided on the second carrier transport layer. The scribe line engraved on the back electrode corresponds to the P2 scribe line of the second carrier transport layer. The functional film containing the back electrode includes a flexible substrate and a back electrode deposited on the upper surface of the flexible substrate. Lines are engraved on the back electrode to cut the back electrode into multiple back electrode strips. A positive lead-out terminal and a negative lead-out terminal are also provided on the back electrode, and a positive bus strip and a negative bus strip are welded to the positive lead-out terminal and the negative lead-out terminal, respectively.

2. The thin-film photovoltaic module according to claim 1, wherein: A back electrode protection film is also provided between the lower packaging glass and the flexible substrate, and the back electrode protection film is adhered to the lower surface of the flexible substrate.

3. The thin-film photovoltaic module according to claim 1, wherein: The positive bus strip and the negative bus strip are respectively welded to the positive electrode lead-in terminal and the negative electrode lead-in terminal by polymer, and the material of the polymer includes any one of polypropylene, polyethylene, polyvinyl chloride, polytetrafluoroethylene, polyethylene tetrafluoroethylene, polymethyl methacrylate, polyethylene terephthalate, polystyrene, polyimide, polyamide, nylon, polyvinyl alcohol and polylactic acid.

4. The thin-film photovoltaic module according to claim 2, wherein: The material of the back electrode protective film includes any one of polyurethane, ethylene-vinyl acetate copolymer, ethylene octene copolymer and polyvinyl butyral.

5. A method for preparing a thin-film photovoltaic module according to claim 1, characterized in that: The steps include: Step 1: depositing a back electrode on the upper surface of the flexible substrate, scribing the back electrode, and cutting the back electrode into a plurality of back electrode strips; Step 2: Welding a positive bus tape and a negative bus tape onto the positive electrode lead-out terminal and the negative electrode lead-out terminal of the back electrode, respectively, to obtain a functional film containing the back electrode; Step 3: Prepare a front electrode layer on the upper encapsulation glass and scribe a P1 line on the front electrode layer; Step 4: sequentially prepare a first carrier transport layer, a light absorbing layer, and a second carrier transport layer on the front electrode layer, and scribe a P2 line on the second carrier transport layer; Step 5: Lay the functional film containing the back electrode prepared in step 2 on the second carrier transport layer, wherein the scribe line on the back electrode corresponds to the P2 scribe line of the second carrier transport layer, lay the lower encapsulation glass on it, and lay or apply encapsulation glue on its side; Step 6: Place the laid components together into the laminator for lamination.

6. The method for preparing a thin-film photovoltaic module according to claim 5, wherein: Step 1 also includes the following step: pasting a back electrode protection film on the lower surface of the flexible substrate.

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