Method for reducing attenuation of heterojunction cell

Abstract

The invention relates to a method for reducing the attenuation of a heterojunction cell, and the method comprises the steps: carrying out the texturing, CVD (Chemical Vapor Deposition) and PVD (Physical Vapor Deposition) processing of a silicon wafer, and obtaining a heterojunction cell without a printed electrode; reflecting layers are deposited on the front face and the back face of the heterojunction cell without the electrodes respectively, and the reflecting layers reflect ultraviolet light with the wavelength smaller than 380 nm and block water vapor. In addition, the invention also relates to another method for reducing the attenuation of the heterojunction cell, and the method comprises the following steps: carrying out texturing, CVD (Chemical Vapor Deposition), PVD (Physical Vapor Deposition) and silk-screen printing processing on a silicon wafer to obtain a finished heterojunction cell; reflecting layers are deposited on the front face and the back face of the finished heterojunction cell respectively, and the reflecting layers reflect ultraviolet light with the wavelength smaller than 380 nm and block water vapor. According to the invention, the efficiency attenuation of the heterojunction cell caused by ultraviolet light and water vapor can be reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cells, and more particularly, to a method for reducing degradation of heterojunction cells. Background Art

[0002] Heterojunction cells have a simple structure and have gradually become the mainstream in the development of photovoltaic technology. Heterojunction cells are one of the solar cell routes that the photovoltaic industry has focused on in recent years. There are amorphous silicon (a-Si:H) passivation film layers on the front and back of heterojunction cells. The passivation effect of the passivation layer is mainly due to the presence of a large number of Si-H bonds in the film layer. However, during the use of heterojunction cells after they are packaged into components, the outdoor environment is often high temperature, high humidity and ultraviolet radiation. Some ultraviolet light, due to its short wavelength and high energy, will break the Si-H bonds in the heterojunction cell, thereby weakening the passivation effect, increasing defects, and further reducing the electrical performance of the heterojunction cell.

[0003] In addition, water vapor easily enters the edge of the heterojunction battery module, and EVA will hydrolyze to generate acetic acid. Acetic acid and Na in the glass + Can generate a large amount of free-moving Na + , Na on the glass surface + It will migrate to the battery surface through the packaging material and undergo an electrical corrosion reaction with the silver grid lines on the battery surface, thereby corroding the battery grid lines, resulting in low filling, high series resistance, and degradation of component performance.

[0004] In addition, the entire process of heterojunction battery preparation is currently a low-temperature process, and the entire preparation process generally does not exceed 250°C. Although this makes the preparation of heterojunction batteries low in energy consumption and low in cost, it is precisely because of its requirement for low temperature that the high-temperature process commonly used in the market cannot be used in heterojunction batteries. Since the high-temperature process will cause the hydrogen bonds in the film layer to break and the hydrogen ions to escape, the film layer will be damaged and the device performance will deteriorate sharply - the photoelectric conversion efficiency can be reduced by more than 5%, so the commonly used high-temperature process technology cannot be used in heterojunction batteries when preparing the film layer.

[0005] Therefore, it is urgent to design a solution that can solve the above-mentioned defects. Summary of the invention

[0006] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a method for reducing the attenuation of heterojunction cells. The present invention can, for example, use a hot wire CVD method to prepare a reflective layer (e.g., a silicon nitride layer or a silicon oxide and silicon nitride stack) on the surface of the heterojunction cell to block water vapor and reduce the damage of ultraviolet light to the heterojunction cell.

[0007] In order to solve the above technical problems or achieve the above objectives, the present invention adopts the following technical solutions:

[0008] According to one aspect of the present invention, there is provided a method for reducing attenuation of a heterojunction battery, comprising:

[0009] The silicon wafer is subjected to texturing, CVD and PVD process operations to obtain a heterojunction battery without printed electrodes;

[0010] Reflective layers are deposited on the front and back of a heterojunction battery without printed electrodes, respectively. The reflective layers reflect ultraviolet light with a wavelength less than 380nm and block water vapor.

[0011] In one embodiment of the present invention, the reflective layers are deposited on the front and back sides of the heterojunction cell without printed electrodes by hot-wire CVD.

[0012] In one embodiment of the present invention, the temperature range of the hot filament in the hot filament CVD is 1800-2200°C, and the deposition temperature does not exceed 200°C.

[0013] In one embodiment of the present invention, the reflective layer is a silicon nitride layer, or the reflective layer is a stacked layer of silicon oxide and silicon nitride.

[0014] In one embodiment of the present invention, the thickness of the reflective layer is set to an odd multiple of half the wavelength of ultraviolet light with a wavelength of 200-380 nm.

[0015] According to another aspect of the present invention, there is provided a method for reducing attenuation of a heterojunction battery, comprising:

[0016] The silicon wafer is processed by texturing, CVD, PVD and screen printing processes to obtain the finished heterojunction battery;

[0017] Reflective layers are deposited on the front and back of the finished heterojunction solar cell, respectively, and the reflective layers reflect ultraviolet light with a wavelength less than 380nm and block water vapor.

[0018] In one embodiment of the present invention, the reflective layers are deposited on the front and back sides of the finished heterojunction cell respectively by hot-filament CVD.

[0019] In one embodiment of the present invention, the temperature range of the hot filament in the hot filament CVD is 1800-2200°C, and the deposition temperature does not exceed 200°C.

[0020] In one embodiment of the present invention, the reflective layer is a silicon nitride layer, or the reflective layer is a stacked layer of silicon oxide and silicon nitride.

[0021] In one embodiment of the present invention, the thickness of the reflective layer is set to an odd multiple of half the wavelength of ultraviolet light with a wavelength of 200-380 nm.

[0022] According to another aspect of the present invention, there is provided a method for preparing a heterojunction battery, comprising:

[0023] The silicon wafer is textured to form a pyramid texture structure as a crystalline silicon substrate;

[0024] Depositing an intrinsic passivation layer and an N-type doping layer in sequence on the front side of the crystalline silicon substrate by CVD, and depositing an intrinsic passivation layer and a P-type doping layer in sequence on the back side of the crystalline silicon substrate by CVD;

[0025] Depositing a transparent conductive oxide layer on the N-type doped layer and the P-type doped layer respectively by PVD;

[0026] Reflective layers are deposited on the transparent conductive oxide layers on the front and back sides respectively, and the reflective layers reflect ultraviolet light with a wavelength less than 380nm and block water vapor;

[0027] Laser grooving the reflective layer to etch out the screen-printed pattern and expose the transparent conductive oxide layer;

[0028] The paste is screen-printed into the laser-grooved area and forms an ohmic contact with the transparent conductive oxide layer to form positive and negative electrodes.

[0029] In one embodiment of the present invention, the reflective layers are deposited on the transparent conductive oxide layers on the front and back sides respectively by hot-filament CVD.

[0030] In one embodiment of the present invention, the temperature range of the hot filament in the hot filament CVD is 1800-2200°C, and the deposition temperature does not exceed 200°C.

[0031] In one embodiment of the present invention, the reflective layer is a silicon nitride layer, or the reflective layer is a stacked layer of silicon oxide and silicon nitride.

[0032] In one embodiment of the present invention, the thickness of the reflective layer is set to an odd multiple of half the wavelength of ultraviolet light with a wavelength of 200-380 nm.

[0033] According to another aspect of the present invention, there is provided a method for preparing a heterojunction battery, comprising:

[0034] The silicon wafer is textured to form a pyramid texture structure as a crystalline silicon substrate;

[0035] Depositing an intrinsic passivation layer and an N-type doping layer in sequence on the front side of the crystalline silicon substrate by CVD, and depositing an intrinsic passivation layer and a P-type doping layer in sequence on the back side of the crystalline silicon substrate by CVD;

[0036] Depositing a transparent conductive oxide layer on the N-type doped layer and the P-type doped layer respectively by PVD;

[0037] Screen printing the paste onto the transparent conductive oxide layer and forming an ohmic contact with the transparent conductive oxide layer to form positive and negative electrodes;

[0038] Reflective layers are deposited on the transparent conductive oxide layers on the front and back sides after screen printing. The reflective layers reflect ultraviolet light with a wavelength less than 380nm and block water vapor.

[0039] In one embodiment of the present invention, the reflective layers are respectively deposited on the transparent conductive oxide layers on the front and back sides after screen printing by hot wire CVD.

[0040] In one embodiment of the present invention, the temperature range of the hot filament in the hot filament CVD is 1800-2200°C, and the deposition temperature does not exceed 200°C.

[0041] In one embodiment of the present invention, the reflective layer is a silicon nitride layer, or the reflective layer is a stacked layer of silicon oxide and silicon nitride.

[0042] In one embodiment of the present invention, the thickness of the reflective layer is set to an odd multiple of half the wavelength of ultraviolet light with a wavelength of 200-380 nm.

[0043] According to another aspect of the present invention, a heterojunction battery is provided. The heterojunction battery is prepared by using any one of the two preparation methods described above.

[0044] In one embodiment of the present invention, the prepared heterojunction battery is packaged as a component using EVA (ethylene-vinyl acetate copolymer), packaging glass and packaging glue.

[0045] The technical solution provided by the present invention has the following advantages compared with the prior art:

[0046] The design of the reflective layer in the heterojunction cell of the present invention can effectively eliminate the damage of outdoor ultraviolet light to Si-H bonds in the heterojunction cell, and can effectively block the invasion of water vapor, providing an additional protective barrier for the heterojunction cell, that is, the present invention can reduce the efficiency attenuation of the heterojunction cell caused by ultraviolet light and water vapor. In addition, the method of the present invention will not cause thermal damage and sputtering damage to the existing film layer of the heterojunction cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0048] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the description of the embodiments or the prior art are briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0049] Figure 1 A schematic flow chart of a method for reducing heterojunction battery attenuation provided by an embodiment of the present invention is shown;

[0050] Figure 2 A schematic flow chart of a method for reducing heterojunction battery attenuation provided by another embodiment of the present invention is shown;

[0051] Figure 3 A schematic flow chart of a method for preparing a heterojunction battery provided by an embodiment of the present invention is shown;

[0052] Figure 4 A schematic flow chart of a method for preparing a heterojunction battery provided by another embodiment of the present invention is shown. DETAILED DESCRIPTION

[0053] In order to more clearly understand the above-mentioned purposes, features and advantages of the present disclosure, the embodiments of the present disclosure will be further described below. It should be noted that the embodiments of the present disclosure and the features in the embodiments can be combined with each other without conflict.

[0054] In the following description, many specific details are set forth to facilitate a full understanding of the present disclosure, but the present disclosure may also be implemented in other ways different from those described herein; obviously, the embodiments in the specification are only part of the embodiments of the present disclosure, rather than all of the embodiments.

[0055] like Figure 1 As shown, an embodiment of the present invention provides a method for reducing attenuation of a heterojunction battery, comprising the following steps:

[0056] S10: performing texturing, CVD and PVD process operations on the silicon wafer to obtain a heterojunction battery without printed electrodes;

[0057] S11: Reflective layers are deposited on the front and back sides of the heterojunction battery without printed electrodes, respectively, and the reflective layers reflect ultraviolet light with a wavelength less than 380nm and block water vapor.

[0058] Through the above method of this embodiment, the present invention can reduce the efficiency attenuation of heterojunction cells caused by ultraviolet light and water vapor.

[0059] In the method of this embodiment: the reflective layer deposited in S11 is a silicon nitride layer, or a stack of silicon oxide and silicon nitride; the thickness of the deposited reflective layer is an odd multiple of half the wavelength of ultraviolet light with a wavelength of 200-380nm, that is, (2n+1)×λ / 2, where λ is the wavelength, ranging from 200-380nm, and n is an integer.

[0060] After the three processes of the heterojunction cell, namely, the velvet process - forming a pyramid velvet structure, the CVD (chemical vapor deposition) process - the intrinsic passivation layer, the N-type doping layer and the P-type doping layer, and the PVD (physical vapor deposition) - the TCO layer (transparent conductive oxide layer), a reflective layer (for example, a silicon nitride layer, or a stack of silicon oxide and silicon nitride) is prepared on the TCO layer. This reflective layer is only for short-wave ultraviolet light with a wavelength less than 380nm, and uses the principle of destructive interference of incident light, that is, when the phase difference between the two coherent light beams is an odd multiple of half the wavelength, the interference destructive phenomenon of light will occur. This is because when the phase difference is an odd multiple of half the wavelength, the peaks and troughs of the two light waves completely overlap, causing the light intensity to weaken or even disappear completely, thereby achieving the effect of effectively removing ultraviolet rays and improving the anti-ultraviolet attenuation effect of the heterojunction cell.

[0061] In addition, a silicon nitride reflective layer or a silicon oxide and silicon nitride stacked reflective layer that can reflect ultraviolet light with a wavelength less than 380nm is coated on both surfaces of the heterojunction battery, thereby eliminating the influence of ultraviolet rays on the electrical performance of the heterojunction battery. At the same time, since silicon nitride is a strong covalent bond compound with a very small diffusion coefficient, impurities and mobile ions are difficult to penetrate in the silicon nitride film layer, thereby effectively blocking the invasion of water vapor and metal ions, eliminating the attenuation of the heterojunction battery and improving stability.

[0062] In the method of this embodiment, a reflective layer is deposited on the front and back sides of a heterojunction battery without printed electrodes by hot-wire CVD, wherein the temperature range of the hot wire in the hot-wire CVD is 1800-2200°C and the deposition temperature does not exceed 200°C.

[0063] The preparation of the reflective layer can be carried out by the HoFCVD (hot wire CVD) method. The working principle of the HoFCVD equipment is that the process gas introduced decomposes on the surface of the hot wire at a temperature of about 1800-2200°C, and the generated active groups move to the surface of the substrate (textured silicon wafer) to react and deposit into a film. Although the temperature of the hot wire is as high as 1800-2200°C, the heat capacity of the process gas is very low. The process gas is catalytically decomposed after hitting the hot wire, and the temperature of the generated active groups is lower than 200°C when they reach the substrate surface. Therefore, the film layer will not be damaged after the substrate temperature exceeds 250°C.

[0064] It can be seen that through the method of this embodiment, on the one hand, the present invention can reduce the efficiency attenuation of the heterojunction battery due to ultraviolet and water vapor; on the other hand, the method of the present invention can use hot wire CVD to deposit the reflective layer without causing thermal damage and sputtering damage to the existing film layer of the heterojunction battery.

[0065] like Figure 2 As shown, Figure 1 Similar to the method of the embodiment shown, another embodiment of the present invention provides a method for reducing attenuation of a heterojunction battery, comprising the following steps:

[0066] S20: performing texturing, CVD, PVD and screen printing processes on the silicon wafer to obtain a finished heterojunction battery;

[0067] S21: Reflective layers are deposited on the front and back of the finished heterojunction solar cell respectively, and the reflective layers reflect ultraviolet light with a wavelength less than 380nm and block water vapor.

[0068] In this embodiment, the method of this embodiment is Figure 1 The methods of the embodiments shown differ only in the stage or timing of depositing the reflective layer. In this embodiment, after the heterojunction battery undergoes a texturing process - forming a pyramid velvet structure, a CVD (chemical vapor deposition) process - an intrinsic passivation layer, an N-type doping layer and a P-type doping layer, a PVD (physical vapor deposition) process - a TCO layer (transparent conductive oxide layer), and screen printing - forming an electrode, and after the four processes form a finished heterojunction battery, a reflective layer (for example, a silicon nitride layer, or a stack of silicon oxide and silicon nitride) is prepared.

[0069] In the method of this embodiment, the reflective layer deposited in S21 is a silicon nitride layer, or a stack of silicon oxide and silicon nitride. The thickness of the reflective layer is an odd multiple of half the wavelength of ultraviolet light with a wavelength of 200-380nm, that is, (2n+1)×λ / 2, where λ is the wavelength, ranging from 200-380nm, and n is an integer. That is, the reflective layer deposited in this embodiment is only for short-wave ultraviolet light with a wavelength less than 380nm, which can eliminate the influence of ultraviolet rays on the electrical performance of heterojunction batteries, and can also effectively block the invasion of water vapor and metal ions, eliminate the attenuation of heterojunction batteries, and improve stability.

[0070] In addition, in this embodiment, the hot wire CVD method is also used to prepare or deposit the reflective layer, thereby preventing thermal damage and sputtering damage to the existing film layers of the heterojunction battery.

[0071] like Figure 3 As shown, one embodiment of the present invention provides a method for preparing a heterojunction battery, comprising the following steps:

[0072] S30: Texturing the silicon wafer to form a pyramid texture structure as a crystalline silicon substrate;

[0073] S31: depositing an intrinsic passivation layer and an N-type doping layer in sequence on the front side of the crystalline silicon substrate by CVD, and depositing an intrinsic passivation layer and a P-type doping layer in sequence on the back side of the crystalline silicon substrate by CVD;

[0074] S32: depositing a transparent conductive oxide layer on the N-type doped layer and the P-type doped layer respectively by PVD;

[0075] S33: depositing reflective layers on the transparent conductive oxide layer on the front and back sides respectively, wherein the reflective layers reflect ultraviolet light with a wavelength less than 380 nm and block water vapor;

[0076] S34: laser grooving the reflective layer to etch out the screen-printed pattern and expose the transparent conductive oxide layer;

[0077] S35: Screen-printing the slurry into the laser-grooved area and forming an ohmic contact with the transparent conductive oxide layer to form positive and negative electrodes.

[0078] This embodiment involves a specific method for preparing a heterojunction battery. Figure 1 Corresponding to the method of the embodiment shown, the preparation method of the heterojunction battery includes the specific operation steps of texturing the silicon wafer, CVD deposition of the intrinsic passivation layer, the N-type doping layer and the P-type doping layer, and PVD deposition of the transparent conductive oxide layer TCO, and then depositing the reflective layer on the TCO, laser grooving the reflective layer, and finally screen printing to form the positive and negative electrodes. The heterojunction battery prepared in this embodiment is also coated with a silicon nitride reflective layer or a silicon nitride and silicon oxynitride laminated reflective layer that has a reflective effect on ultraviolet light with a wavelength less than 380nm, eliminating the influence of ultraviolet rays on the electrical properties of the heterojunction battery, and can also effectively block the invasion of water vapor and metal ions, eliminate the attenuation of the heterojunction battery, and improve stability.

[0079] In addition, the heterojunction battery prepared in this embodiment also adopts the hot wire CVD method to prepare or deposit the reflective layer, and the preparation of the heterojunction battery will not cause thermal damage and sputtering damage to the existing film layer of the heterojunction battery.

[0080] like Figure 4 As shown, another embodiment of the present invention provides a method for preparing a heterojunction battery, comprising the following steps:

[0081] S40: Texturing the silicon wafer to form a pyramid texture structure as a crystalline silicon substrate;

[0082] S41: depositing an intrinsic passivation layer and an N-type doping layer in sequence on the front side of the crystalline silicon substrate by CVD, and depositing an intrinsic passivation layer and a P-type doping layer in sequence on the back side of the crystalline silicon substrate by CVD;

[0083] S42: depositing a transparent conductive oxide layer on the N-type doped layer and the P-type doped layer respectively by PVD;

[0084] S43: screen-printing the slurry onto the transparent conductive oxide layer and forming an ohmic contact with the transparent conductive oxide layer to form positive and negative electrodes;

[0085] S44: Reflective layers are deposited on the transparent conductive oxide layers on the front and back sides after screen printing, respectively. The reflective layers reflect ultraviolet light with a wavelength less than 380 nm and block water vapor.

[0086] This embodiment involves another specific preparation method of a heterojunction battery. Figure 2 The method of the embodiment shown corresponds to the specific operation steps of texturing the silicon wafer, CVD deposition of the intrinsic passivation layer, the N-type doping layer and the P-type doping layer, PVD deposition of the transparent conductive oxide layer TCO and screen printing to form the electrode, and finally the step of depositing the reflective layer on the TCO of the finished heterojunction battery. The heterojunction battery prepared in this embodiment is coated with a silicon nitride reflective layer or a silicon nitride and silicon oxynitride stacked reflective layer that has a reflective effect on ultraviolet light with a wavelength less than 380nm after screen printing, which eliminates the influence of ultraviolet rays on the electrical properties of the heterojunction battery, and can also effectively block the invasion of water vapor and metal ions, eliminate the attenuation of the heterojunction battery cell, and improve stability. The heterojunction battery prepared in this embodiment also adopts the hot wire CVD method to prepare or deposit the reflective layer, and there will be no thermal damage and sputtering damage to the existing film layer of the heterojunction battery during the preparation of the heterojunction battery.

[0087] In addition, an embodiment of the present invention further provides a heterojunction battery, which can use the above Figure 3 or Figure 4 The heterojunction cell can be packaged by EVA, packaging glass and packaging glue.

[0088] The above technical solution of the present invention is described in detail below through specific embodiments.

[0089] Example 1

[0090] Step 1: After the texturing, CVD and PVD of the heterojunction structure solar cell, the front side (light-facing side, N-type side) is first deposited with a silicon nitride layer through the HoFCVD (hot wire CVD) equipment. The film thickness of the silicon nitride layer can be an odd multiple of half the wavelength of the ultraviolet light of 200-380nm, that is, (2n+1)×λ / 2, where λ is the wavelength, ranging from 200-380nm, and n is an integer.

[0091] Step 2: Take out the solar cell with heterojunction structure, turn it over and put it back into the HoFCVD equipment to deposit the silicon nitride layer on the back side (P-type side). The thickness of the silicon nitride layer can be an odd multiple of half the wavelength of ultraviolet light of 200-380nm, that is, (2n+1)×λ / 2, where λ is the wavelength, ranging from 200-380nm, and n is an integer.

[0092] Step 3: Laser groove the silicon nitride layers on both sides, and etch out the screen-printed pattern by laser to expose the TCO layer after the PVD process.

[0093] Step 4: Screen printing: Use a screen printer to screen print the slurry into the laser grooved area to form a good ohmic contact with the TCO layer to form positive and negative electrodes.

[0094] Step 5: Component packaging.

[0095] By using this embodiment 1, it has been tested that, on the one hand, the heterojunction battery after component packaging reduces the efficiency attenuation caused by ultraviolet light and water vapor, and on the other hand, the silicon nitride layer is prepared by the hot wire CVD method without causing thermal damage and sputtering damage to the existing film layer of the heterojunction battery.

[0096] Example 2

[0097] Step 1: After the texturing, CVD and PVD of the heterojunction structure solar cell, the front side (light-facing side, N-type side) is first deposited with silicon oxide and silicon nitride stacking by HoFCVD (hot wire CVD) equipment. The thickness of the stacking film can be an odd multiple of half the wavelength of 200-380nm ultraviolet light, that is, (2n+1)×λ / 2, where λ is the wavelength, ranging from 200-380nm, and n is an integer.

[0098] The second step: take out the solar cell with heterojunction structure, turn it over and put it back into the HoFCVD equipment for deposition of silicon oxide and silicon nitride stack on the back side (P-type side). The thickness of the stack can be an odd multiple of half the wavelength of ultraviolet light of 200-380nm, that is, (2n+1)×λ / 2, where λ is the wavelength, ranging from 200-380nm, and n is an integer.

[0099] Step 3: Laser groove the laminated layers on both sides, and etch out the screen-printed pattern by laser to expose the TCO layer after the PVD process.

[0100] Step 4: Screen printing: Use a screen printer to screen print the slurry into the laser grooved area to form a good ohmic contact with the TCO layer to form positive and negative electrodes.

[0101] Step 5: Component packaging.

[0102] By using this embodiment 2, it has been tested that, on the one hand, the heterojunction battery after component packaging also reduces the efficiency attenuation caused by ultraviolet light and water vapor, and on the other hand, the hot wire CVD method is used to prepare the silicon oxide and silicon nitride stack without causing thermal damage and sputtering damage to the existing film layer of the heterojunction battery.

[0103] Example 3

[0104] Step 1: After finishing the texturing, CVD, PVD and screen printing of the finished heterojunction battery, the front side (light-facing side, N-type side) is first deposited with a silicon nitride layer by the HoFCVD (hot wire CVD) device. The film thickness of the silicon nitride layer can be an odd multiple of half the wavelength of the ultraviolet light of 200-380nm, that is, (2n+1)×λ / 2, where λ is the wavelength, ranging from 200-380nm, and n is an integer.

[0105] Step 2: Take out the finished heterojunction battery, turn it over and put it back into the HoFCVD equipment to deposit the silicon nitride layer on the back (P-type surface). The thickness of the silicon nitride layer can be an odd multiple of half the wavelength of the ultraviolet light of 200-380nm, that is, (2n+1)×λ / 2, where λ is the wavelength, ranging from 200-380nm, and n is an integer.

[0106] Step 3: Weld the welding ribbon to destroy the film layer covering the battery grid line to form a good ohmic contact for component packaging.

[0107] By using this embodiment 3, it has been found through testing that, on the one hand, the heterojunction cell after the component packaging has been completed has reduced the efficiency attenuation caused by ultraviolet light and water vapor, and on the other hand, the silicon nitride layer is prepared by the hot wire CVD method, without causing thermal damage and sputtering damage to the existing film layer of the heterojunction cell. In addition, this embodiment can also protect the fine grid from being corroded and damaged by water and oxygen.

[0108] Example 4

[0109] Step 1: After finishing the texturing, CVD, PVD and screen printing, the finished heterojunction battery is first deposited with silicon oxide and silicon nitride on the front side (facing the light, N-type side) through the HoFCVD (hot wire CVD) equipment. The film thickness of the stack can be an odd multiple of half the wavelength of ultraviolet light of 200-380nm, that is, (2n+1)×λ / 2, where λ is the wavelength, ranging from 200-380nm, and n is an integer.

[0110] Step 2: Take out the finished heterojunction battery, turn it over and put it back into the HoFCVD equipment to deposit silicon oxide and silicon nitride on the back side (P-type side). The thickness of the stack can be an odd multiple of half the wavelength of ultraviolet light of 200-380nm, that is, (2n+1)×λ / 2, where λ is the wavelength, ranging from 200-380nm, and n is an integer.

[0111] Step 3: Weld the welding ribbon to destroy the film layer covering the battery grid line to form a good ohmic contact for component packaging.

[0112] By using this embodiment 4, it has been tested that, on the one hand, the heterojunction cell after the component packaging has been completed also reduces the efficiency attenuation caused by ultraviolet light and water vapor, and on the other hand, the hot wire CVD method is used to prepare the silicon oxide and silicon nitride stack, and no thermal damage and sputtering damage are caused to the existing film layer of the heterojunction cell. In addition, this embodiment can protect the fine grid from being corroded and damaged by water and oxygen.

[0113] It can be seen from the above-mentioned Examples 1-4 that the present invention uses the hot wire CVD method to prepare a silicon nitride layer or a reflective layer of a stack of silicon oxide and silicon nitride on the surface of a heterojunction battery. On the one hand, it can reduce the efficiency attenuation caused by ultraviolet light and water vapor, and on the other hand, it will not cause thermal damage and sputtering damage to the existing film layer of the heterojunction battery.

[0114] It should be noted that, in this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusions, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to the process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "including a..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0115] The above is only an embodiment of the present application, and the embodiment enables those skilled in the art to understand and implement the present application. Various modifications to the embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments described herein, but will conform to the widest scope consistent with the principles and features disclosed herein.

Claims

1. A method for reducing heterojunction battery attenuation, characterized in that: include: The silicon wafer is subjected to texturing, CVD and PVD process operations to obtain a heterojunction battery without printed electrodes; Reflective layers are deposited on the front and back of a heterojunction battery without printed electrodes, respectively. The reflective layers reflect ultraviolet light with a wavelength less than 380 nm and block water vapor.

2. The method for reducing heterojunction battery attenuation according to claim 1, characterized in that: The reflective layers were deposited on the front and back sides of the heterojunction cell without printed electrodes by hot-wire CVD.

3. The method for reducing heterojunction battery attenuation according to claim 2, characterized in that: The temperature range of the hot wire in hot wire CVD is 1800-2200℃, and the deposition temperature does not exceed 200℃.

4. The method for reducing heterojunction battery attenuation according to any one of claims 1 to 3, characterized in that: The reflective layer is a silicon nitride layer, or the reflective layer is a stacked layer of silicon oxide and silicon nitride.

5. The method for reducing heterojunction battery attenuation according to any one of claims 1 to 3, characterized in that: The thickness of the reflective layer is set to an odd multiple of half the wavelength of ultraviolet light with a wavelength of 200-380 nm.

6. A method for reducing heterojunction battery attenuation, characterized in that: include: The silicon wafer is processed by texturing, CVD, PVD and screen printing processes to obtain the finished heterojunction battery; Reflective layers are deposited on the front and back of the finished heterojunction solar cell, respectively, and the reflective layers reflect ultraviolet light with a wavelength less than 380nm and block water vapor.

7. The method for reducing heterojunction battery attenuation according to claim 6, characterized in that: The reflective layers are deposited on the front and back sides of the finished heterojunction cell by hot-wire CVD.

8. The method for reducing heterojunction battery attenuation according to claim 7, characterized in that: The temperature range of the hot wire in hot wire CVD is 1800-2200℃, and the deposition temperature does not exceed 200℃.

9. The method for reducing heterojunction battery attenuation according to any one of claims 6 to 8, characterized in that: The reflective layer is a silicon nitride layer, or the reflective layer is a stacked layer of silicon oxide and silicon nitride.

10. The method for reducing heterojunction battery attenuation according to any one of claims 6 to 8, characterized in that: The thickness of the reflective layer is set to an odd multiple of half the wavelength of ultraviolet light with a wavelength of 200-380 nm.

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