Crystalline silicon solar cell and photovoltaic module

Abstract

The utility model relates to a crystalline silicon solar cell and a photovoltaic module. The barrier layer covers the passivation layer, and the barrier layer is rich in hydrogen and can effectively prevent hydrogen from escaping, so that the hydrogen passivation capability of the film layer structure is improved, and the film layer structure has excellent passivation performance. Meanwhile, as the metal electrode is arranged between the passivation layer and the barrier layer, namely, the metal electrode is in direct contact with the transparent conductive oxide of the passivation layer, the contact resistance is small, the surface defects are few, and the local windowing is performed on the barrier layer, so that the extraction of current is ensured, and the high-quality electrode contact is realized. In the windowing process, due to blocking of the metal electrode, the passivation layer below the surface of the metal electrode cannot be damaged, the passivation performance of the crystalline silicon solar cell can be greatly improved, hydrogen-induced attenuation of the crystalline silicon solar cell in passivation contact can be effectively eliminated, the conversion efficiency of the crystalline silicon solar cell is improved, and the service life of the crystalline silicon solar cell is prolonged. And the use reliability of the crystalline silicon solar cell is greatly improved.

Description

Technical Field

[0001] The present application relates to the field of photovoltaic technology, and in particular to crystalline silicon solar cells and photovoltaic modules. Background Art

[0002] Energy conservation is a topic of great concern in today's society. The development and use of new environmentally friendly clean energy can provide great help to the global energy shortage problem. Solar energy is the most abundant energy in the world. Making good use of solar energy and developing efficient and stable solar cells can greatly alleviate the global energy crisis. In the future development of science and technology and production and life, solar cells will play an increasingly important role.

[0003] For crystalline silicon solar cells, there are a large number of unsaturated dangling bonds on the surface of crystalline silicon due to the termination of the ordered lattice structure. These dangling bonds will increase the defect state density on the surface of crystalline silicon, thereby causing serious photogenerated carrier recombination, which is not conducive to photoelectric conversion efficiency. Therefore, it is necessary to reduce interface recombination by depositing a passivation film.

[0004] In the related art, the passivation performance of the passivation film layer is poor, which affects the conversion efficiency of the crystalline silicon solar cell. Utility Model Content

[0005] Based on this, it is necessary to provide a crystalline silicon solar cell to address the problem of poor passivation performance of existing crystalline silicon solar cells.

[0006] A crystalline silicon solar cell, comprising:

[0007] Crystalline silicon substrate;

[0008] A passivation layer, deposited on the surface of the crystalline silicon substrate;

[0009] A metal electrode is deposited on a surface of the passivation layer away from the crystalline silicon substrate;

[0010] A barrier layer, deposited on the surface of the passivation layer and the metal electrode; the barrier layer is used to provide hydrogen to passivate the dangling bonds on the surface of the crystalline silicon substrate and to prevent the hydrogen in the passivation layer from escaping;

[0011] Wherein, a window is provided in the region of the barrier layer corresponding to the metal electrode, so that the metal electrode can conduct current.

[0012] In one embodiment, the thickness of the barrier layer is 10nm-150nm.

[0013] In one of the embodiments, the barrier layer includes at least one of silicon oxide, aluminum oxide, silicon nitride and silicon oxynitride.

[0014] In one of the embodiments, the crystalline silicon solar cell further includes a tunneling oxide layer deposited between the crystalline silicon substrate and the passivation layer.

[0015] In one embodiment, the thickness of the tunnel oxide layer is 1 nm to 3 nm.

[0016] In one of the embodiments, the crystalline silicon solar cell further includes a diffusion layer deposited between the crystalline silicon substrate and the tunneling oxide layer.

[0017] In one of the embodiments, the square resistance of the passivation layer is 100 Ω / sq-1000 Ω / sq; and the thickness of the passivation layer is 10 nm-50 nm.

[0018] In one embodiment, the passivation layer comprises at least one of zinc oxide, hydrogenated zinc oxide, aluminum-doped zinc oxide and boron-doped zinc oxide.

[0019] In one of the embodiments, the line width of the metal electrode is 10 μm-50 μm, and the height of the metal electrode is 0.1 μm-10 μm.

[0020] A photovoltaic module, comprising:

[0021] A battery string, comprising a plurality of crystalline silicon solar cells as described above;

[0022] A packaging film is stacked on the surface of the battery string;

[0023] The cover plate is stacked on the surface of the packaging film away from the battery string.

[0024] The above-mentioned crystalline silicon solar cell includes a crystalline silicon substrate, a passivation layer, a metal electrode and a barrier layer. The metal electrode is deposited on the surface of the passivation layer away from the crystalline silicon substrate, and the barrier layer is deposited on the surface of the passivation layer and the metal electrode, and a window is opened in the area of ​​the barrier layer corresponding to the metal electrode. By covering the barrier layer on the passivation layer, the barrier layer is rich in hydrogen and can effectively block the escape of hydrogen, thereby improving the hydrogen passivation ability of the film structure and making it have excellent passivation performance. At the same time, since the metal electrode is arranged between the passivation layer and the barrier layer, that is, the metal electrode is in direct contact with the transparent conductive oxide of the passivation layer, the contact resistance is small and the surface defects are few. By partially opening the window of the barrier layer, the current is drawn out and high-quality electrode contact is achieved. In the process of opening the window, due to the blocking of the metal electrode, the passivation layer under the surface of the metal electrode will not be damaged, which can not only greatly improve the passivation performance of the crystalline silicon solar cell, but also effectively eliminate the purpose of hydrogen-induced attenuation of the crystalline silicon solar cell with passivation contact, thereby improving the conversion efficiency of the crystalline silicon solar cell and greatly improving the reliability of the use of the crystalline silicon solar cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic diagram of a crystalline silicon solar cell provided in the first embodiment of the present application.

[0026] Figure 2 A schematic diagram of a crystalline silicon solar cell provided in the second embodiment of the present application.

[0027] Reference numerals: 100, crystalline silicon solar cell; 110, crystalline silicon substrate; 120, tunneling oxide layer; 130, passivation layer; 140, metal electrode; 150, barrier layer; 151, window; 160, diffusion layer. DETAILED DESCRIPTION

[0028] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0029] In the description of the present application, it should be understood that if the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. appear, the orientation or position relationship indicated by these terms is based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0030] In addition, if the terms "first" or "second" appear, these terms are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, if the term "plurality" appears, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0031] In this application, unless otherwise clearly specified and limited, if the terms "installed", "connected", "connected", "fixed" and the like appear, these terms should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integrated connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0032] In the present application, unless otherwise clearly specified and limited, if there is a description that a first feature is "above" or "below" a second feature, etc., or similar descriptions appear, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "above" and "above" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being "below", "below" and "below" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0033] It should be noted that if an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. If an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. If any, the terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used in this application are for illustrative purposes only and do not represent the only implementation method.

[0034] See also Figure 1 As shown, a crystalline silicon solar cell 100 provided in one embodiment of the present application includes a crystalline silicon substrate 110, a passivation layer 130, a metal electrode 140 and a barrier layer 150, wherein the passivation layer 130 is deposited on the surface of the crystalline silicon substrate 110; the metal electrode 140 is deposited on the surface of the passivation layer 130 away from the crystalline silicon substrate 110; the barrier layer 150 is deposited on the surface of the passivation layer 130 and the metal electrode 140; the barrier layer 150 is used to provide hydrogen to passivate the dangling bonds on the surface of the crystalline silicon substrate 110 and to prevent the hydrogen in the passivation layer 130 from escaping; and the barrier layer 150 is provided with a window 151 in the area corresponding to the metal electrode 140, so that the metal electrode 140 can conduct current.

[0035] The above-mentioned crystalline silicon solar cell 100, by covering the barrier layer 150 on the passivation layer 130, the barrier layer 150 is rich in hydrogen and can effectively block the escape of hydrogen, thereby improving the hydrogen passivation ability of the film structure, and making it have excellent passivation performance. At the same time, since the metal electrode 140 is arranged between the passivation layer 130 and the barrier layer 150, that is, the metal electrode 140 is in direct contact with the transparent conductive oxide of the passivation layer 130, the contact resistance is small, the surface defects are few, and the current is drawn out by partially opening the window of the barrier layer 150, and high-quality electrode contact is achieved. In the process of opening the window, due to the blocking of the metal electrode 140, the passivation layer 130 under the surface of the metal electrode 140 will not be damaged, which can not only greatly improve the passivation performance of the crystalline silicon solar cell, but also effectively eliminate the purpose of hydrogen-induced attenuation of the crystalline silicon solar cell with passivation contact, thereby improving the conversion efficiency of the crystalline silicon solar cell and greatly improving the reliability of the crystalline silicon solar cell. This can greatly improve the passivation performance of the crystalline silicon solar cell and effectively eliminate the hydrogen-induced attenuation of the crystalline silicon solar cell, thereby effectively improving the reliability and cell efficiency of the photovoltaic module made using the crystalline silicon solar cell during long-term use.

[0036] Among them, laser etching, plasma etching and other methods can be used to remove the area of ​​the barrier layer 150 corresponding to the metal electrode 140, which can not only retain the barrier layer 150, reduce the introduction of impurities, and improve the passivation performance; but also ensure the extraction of current and provide high-quality electrode contact.

[0037] like Figure 1 As shown, in some embodiments, the barrier layer 150 covers the passivation layer 130 and the metal electrode 140. The barrier layer 150 is made of a dense insulating material, including but not limited to one or more combinations of silicon oxide, aluminum oxide, silicon nitride, and silicon oxynitride. The barrier layer 150 is used to provide free hydrogen that can passivate the dangling bonds on the silicon surface, and the hydrogen is redistributed in the passivation layer 130 and the barrier layer 150 through a thermal annealing process to activate the passivation performance. In addition, the hydrogen in the passivation layer 130 can also be blocked from escaping, which plays a role in improving the stability of the passivation structure. Among them, the film thickness of the barrier layer 150 is 10nm-150nm, and the annealing temperature is 400-550℃.

[0038] In some embodiments, the crystalline silicon substrate may include one or more of monocrystalline silicon, polycrystalline silicon, amorphous silicon or microcrystalline silicon. The crystalline silicon substrate has doping elements, and the doping element type is N-type or P-type. The N-type element may be phosphorus, bismuth, antimony or arsenic, and the P-type element may be boron, aluminum, gallium or indium. Preferably, the crystalline silicon substrate is N-type doped. The resistivity of the crystalline silicon substrate may be 0.1Ω·cm-20Ω·cm.

[0039] In some embodiments, the front and back sides of the crystalline silicon substrate may be textured to form a textured structure on the front and back sides. The textured structure may be a pyramid-shaped structure. The inclined surface of the pyramid-shaped structure may increase the reflection of the incident light, thereby increasing the internal reflection of the incident light, reducing optical losses, and helping to improve the photoelectric conversion efficiency of solar cells. The textured treatment may include solution textured treatment, laser textured treatment, and reactive ion etching textured treatment. When the material of the crystalline silicon substrate is single crystal silicon, the solution of the solution textured treatment is a mixed solution of an alkaline solution and an alcohol solution; when the material of the crystalline silicon substrate is polycrystalline silicon, the solution of the solution textured treatment is an acid solution.

[0040] In some embodiments, an emitter may be formed on the front surface. The crystalline silicon substrate and the emitter form a PN junction, for example, the crystalline silicon substrate has a P-type doping element, and the emitter has an N-type doping element. In other embodiments, the emitter may be regarded as a part of the crystalline silicon substrate, or as an extension of the crystalline silicon substrate. In addition, the surface of the emitter may be set as a pyramid velvet surface to reduce the reflection of light on the emitter surface, increase the absorption and utilization rate of light, and improve the conversion efficiency of the solar cell.

[0041] In some embodiments, the emitter can be formed on the front side by ion diffusion. First, a film layer containing a diffusion source is formed on the surface of the crystalline silicon substrate, and then ion diffusion is performed by a diffusion device to form a PN junction. The diffusion device may include a lateral quartz tube or a chain diffusion furnace. In other embodiments, the emitter can be formed by laser doping.

[0042] In some embodiments, an alkaline solution or an acidic solution can be used for polishing so that the back of the crystalline silicon substrate is a polished surface. The polished surface can increase the internal reflection of light, reduce the carrier surface recombination rate, and improve the photoelectric conversion efficiency of the battery. It is understandable that when the back is polished, the degree of polishing of the polished surface can be controlled by controlling the process parameters of the polishing process, that is, the degree of etching of the velvet structure on the back. In a specific example, the back of the crystalline silicon substrate is a complete plane, that is, there is no obvious protruding structure. In another specific example, there are still some platform protruding structures on the back of the crystalline silicon substrate. The platform protruding structure can be regarded as a velvet structure after a part of the thickness is etched, and the top surface of the velvet structure constitutes a platform.

[0043] like Figure 1 As shown, in some embodiments, the thickness of the passivation layer 130 is 10nm-50nm. The passivation layer 130 includes at least one of zinc oxide, hydrogenated zinc oxide, aluminum-doped zinc oxide and boron-doped zinc oxide, forming a transparent conductive passivation contact layer, which has both field effect passivation and chemical passivation. In one embodiment, the square resistance of the passivation layer 130 is 100Ω / sq-1000Ω / sq;.

[0044] like Figure 2 As shown, in one embodiment, the metal electrode 140 is disposed between the passivation layer 130 and the barrier layer 150, including but not limited to one or more combinations of silver, copper, aluminum, titanium, and nickel. The metal electrode 140 is used to form an ohmic contact with the passivation layer 130 to lead out the current of the crystalline silicon solar cell. Furthermore, the line width of the metal electrode 140 is 10μm-50μm, and the height of the metal electrode 140 is 0.1μm-10μm. The preparation method of the metal electrode 140 includes but is not limited to screen printing, laser transfer, electroplating, thermal evaporation and electron beam evaporation, and the process temperature at the crystalline silicon substrate is 50℃-300℃.

[0045] See also Figure 1 As shown, in one embodiment, the crystalline silicon solar cell 100 further includes a tunneling oxide layer 120 deposited between the crystalline silicon substrate 110 and the passivation layer 130. Figure 2 As shown, the tunnel oxide layer 120 can be respectively arranged on the front and back sides of the crystalline silicon substrate 110. The tunnel oxide layer 120 includes at least one of silicon oxide, titanium oxide and aluminum oxide. The tunnel oxide layer 120 can passivate the defects on the surface of the crystalline silicon and promote the recombination of photogenerated carriers, thereby improving the fill factor and photoelectric conversion efficiency of the solar cell. In one embodiment, the thickness of the tunnel oxide layer 120 is 1nm to 3nm.

[0046] In some embodiments, a tunneling oxide layer can be formed on the surface of a crystalline silicon substrate by thermal oxidation. The tunneling oxide layer formed by thermal oxidation has good stability and compactness, can reduce the dangling bonds on the surface of the crystalline silicon substrate, thereby reducing the interface state density between the surface of the crystalline silicon substrate and the tunneling oxide layer, and can well control interface traps and fixed charges, which is beneficial to improving the passivation effect of the tunneling oxide layer. In other embodiments, a tunneling oxide layer can be deposited by plasma enhanced chemical vapor deposition using silane and nitrous oxide. The silicon oxide formed by plasma enhanced chemical vapor deposition has a faster growth rate, and the deposited tunneling oxide layer is also thicker.

[0047] See also Figure 2 As shown, in one embodiment, the crystalline silicon solar cell 100 further includes a diffusion layer 160 deposited between the crystalline silicon substrate 110 and the tunnel oxide layer 120. By providing the diffusion layer 160 to form a PN junction, when sunlight irradiates the PN junction, electron-hole pairs are generated on both sides of the junction, and then separated and form a current under the action of the built-in electric field; at the same time, the junction depth can also be controlled, thereby optimizing the current-voltage characteristics of the battery; and to some extent, the series resistance can also be reduced, the fill factor and energy conversion efficiency of the battery can be improved, and the energy conversion efficiency and stability of the crystalline silicon solar cell can be improved.

[0048] like Figure 2 As shown, in some embodiments, a tunneling oxide layer 120, a passivation layer 130, a metal electrode 140 and a barrier layer 150 are sequentially stacked on the front side and the back side of the crystalline silicon substrate 110 respectively.

[0049] In some embodiments, the crystalline silicon solar cell can be a single-sided cell, with the front side being the light-receiving side to absorb incident light and the back side being the backlight side. In other embodiments, the solar cell can also be a double-sided cell, with both the front and back sides being the light-receiving sides.

[0050] Furthermore, an embodiment of the present application also provides a photovoltaic module (not shown), including a battery string (not shown), a packaging film (not shown) and a cover plate (not shown). The battery string includes a plurality of crystalline silicon solar cells 100 as described above, wherein the plurality of crystalline silicon solar cells can be electrically connected in series and / or in parallel. The packaging film is stacked on the surface of the battery string; the cover plate is stacked on the surface of the packaging film away from the battery string.

[0051] The packaging film is used to bond the battery string and the cover plate. In some embodiments, the material of the packaging film may include ethylene vinyl acetate (EVA), polyvinyl butyral (PVB), etc. The packaging film can protect the battery string and prevent the external environment from affecting the performance of the battery string, and has a certain bonding strength.

[0052] In some embodiments, the cover plate can be made of glass. Glass has a low water permeability. The use of a glass cover plate can effectively prevent water vapor in the external environment from entering the photovoltaic module through the cover plate, thereby reducing the corrosion of the battery string by water vapor and reducing the hydrolysis of the packaging film by water vapor, which can improve the service life of the photovoltaic module to a certain extent. In other embodiments, the cover plate can also be composed of a composite film composed of multiple layers of polymer films that are rolled and bonded together, including a fluorine-containing film or a glass substitute thereof, a PET (polyethylene terephthalate) layer, and an EVA adhesive layer film. Since the photovoltaic module uses the film layer structure of the above embodiment, it can improve the reliability of the use of the photovoltaic module and the photoelectric conversion efficiency.

[0053] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0054] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims.

Claims

1. A crystalline silicon solar cell, characterized in that: The crystalline silicon solar cell comprises: A crystalline silicon substrate (110); A passivation layer (130) deposited on the surface of the crystalline silicon substrate (110); A metal electrode (140) is deposited on a surface of the passivation layer (130) facing away from the crystalline silicon substrate (110); A barrier layer (150) is deposited on the surface of the passivation layer (130) and the metal electrode (140); the barrier layer (150) is used to provide hydrogen for passivating dangling bonds on the surface of the crystalline silicon substrate (110) and to prevent hydrogen in the passivation layer (130) from escaping; The barrier layer (150) is provided with a window (151) in a region corresponding to the metal electrode (140), so that the metal electrode (140) can conduct current.

2. The crystalline silicon solar cell according to claim 1, characterized in that: The thickness of the barrier layer (150) is 10nm-150nm.

3. The crystalline silicon solar cell according to claim 1, characterized in that: The crystalline silicon solar cell further comprises a tunneling oxide layer (120) deposited between the crystalline silicon substrate (110) and the passivation layer (130).

4. The crystalline silicon solar cell according to claim 3, characterized in that: The thickness of the tunnel oxide layer (120) is 1 nm to 3 nm.

5. The crystalline silicon solar cell according to claim 3, characterized in that: The crystalline silicon solar cell further comprises a diffusion layer (160) deposited between the crystalline silicon substrate (110) and the tunnel oxide layer (120).

6. The crystalline silicon solar cell according to claim 1, characterized in that: The square resistance of the passivation layer (130) is 100Ω / sq-1000Ω / sq; and the thickness of the passivation layer (130) is 10nm-50nm.

7. The crystalline silicon solar cell according to claim 1, characterized in that: The line width of the metal electrode (140) is 10 μm-50 μm, and the height of the metal electrode (140) is 0.1 μm-10 μm.

8. A photovoltaic module, characterized in that: include: A cell string comprising a plurality of crystalline silicon solar cells as claimed in claim 7; A packaging film is stacked on the surface of the battery string; The cover plate is stacked on the surface of the packaging film away from the battery string.

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