Battery and photovoltaic module

Abstract

The utility model discloses a battery and a photovoltaic assembly, the battery comprises a substrate, the substrate comprises a texturing sheet, a diffusion layer, an aluminum oxide layer and a front silicon nitride layer, and the diffusion layer, the aluminum oxide layer and the front silicon nitride layer are sequentially superposed on the front surface of the texturing sheet in a direction deviating from the texturing sheet; one end of the front electrode is located on the diffusion layer, the other end of the front electrode protrudes out of the surface of the front silicon nitride layer, the front electrode comprises a silver electrode and a conductive material, and the silver electrode extends from the diffusion layer to the aluminum oxide layer; one part of the conductive material is located on the front silicon nitride layer and is connected with the silver electrode, and the other part of the conductive material protrudes out of the surface of the front silicon nitride layer; and the back electrode is formed on the back surface of the substrate. The battery provided by the utility model is high in photoelectric efficiency and reliable in welding.

Description

Technical Field

[0001] The utility model relates to the technical field of photovoltaics, and in particular to a battery and a photovoltaic module. Background Art

[0002] In related technologies, the connection between solar cells has diversity. For example, the connection can be carried out by welding between a solder ribbon and an electrode, or by filling a conductive paste or a conductive adhesive between a conductive strip and an electrode. The above connection methods are all carried out between the surface of the solar cell, the electrode and the conductive strip. There are many defects in this connection method. For example: 1) Part of the incident light is easily blocked or scattered, resulting in light loss; 2) The contact area between the conductive strip and the electrode is small, and the connection is likely to fail during the transportation or further assembly of the module; 3) The contact area of the electrode is small, resulting in a large ohmic resistance during the carrier collection process and large current loss; 4) The connection between the solder ribbon and the electrode point is carried out step by step, and surface oxidation exists, which easily causes poor welding; 5) After the battery is manufactured, processes such as series soldering and lamination of solar cells are still required. During the lamination process, the mechanical property differences of different materials lead to the risk of stress accumulation; 6) The conductive strip is laid on the surface of the solar cell, affecting the appearance of the module. Summary of the Utility Model

[0003] The utility model aims to solve at least one of the technical problems existing in the prior art. For this reason, an object of the utility model is to provide a battery with high photoelectric efficiency and reliable structure.

[0004] Another object of the utility model is to provide a photovoltaic module.

[0005] According to an embodiment of the first aspect of the utility model, the utility model provides a battery, including: a substrate, the substrate includes a texturing sheet, a diffusion layer, an alumina layer, and a front silicon nitride layer, the diffusion layer, the alumina layer, and the front silicon nitride layer are sequentially stacked in a direction away from the texturing sheet on the front of the texturing sheet; a front electrode, one end of the front electrode is located in the diffusion layer, and the other end protrudes from the surface of the front silicon nitride layer, the front electrode includes a silver electrode and a conductive material, the silver electrode extends from the diffusion layer to the alumina layer, a part of the conductive material is located in the front silicon nitride layer and is connected to the silver electrode, and another part of the conductive material protrudes from the surface of the front silicon nitride layer; a back electrode, the back electrode is formed on the back of the substrate.

[0006] For the battery according to the present utility model, one end of the front electrode is located in the diffusion layer, and the other end protrudes from the surface of the front silicon nitride layer. The front electrode includes a silver electrode and a conductive material. The silver electrode extends from the diffusion layer to the alumina layer. A part of the conductive material is located in the front silicon nitride layer and is connected to the silver electrode, and the other part of the conductive material protrudes from the surface of the front silicon nitride layer. With such a setting, the front electrode includes a silver electrode and a conductive material. The silver electrode extends from the diffusion layer to the alumina layer and is embedded inside the substrate, which can prevent the front electrode from covering the surface of the battery, partially blocking the incident light or causing scattering of the incident light, thereby improving the optical conversion efficiency of the battery. The other end of the conductive material protrudes from the front of the substrate, facilitating the welding of the electrode. In this way, the silver electrode is only provided in the diffusion layer and the alumina layer, greatly saving the consumption of silver paste and reducing the cost. Secondly, a part of the conductive material is located in the front silicon nitride layer and is in contact with the silver electrode. In this way, the bonding area between the conductive material and the silver electrode is inside the substrate, which can enhance the bonding force between the conductive material and the silver electrode and improve the mechanical properties of the solder joint. Further, the welding between the front electrode and other battery components is realized through the part of the conductive material protruding from the front of the substrate, which has good corrosion resistance, high safety and reliable welding.

[0007] According to some embodiments of the present utility model, the substrate further includes:

[0008] A tunneling oxide layer - poly layer and a back silicon nitride layer, and the tunneling oxide layer - poly layer and the back silicon nitride layer are sequentially stacked on the back of the textured wafer in a direction away from the textured wafer.

[0009] According to some embodiments of the present utility model, in the width direction of the front electrode, the size of the conductive material is larger than the size of the silver electrode.

[0010] According to some embodiments of the present utility model, in the width direction of the front electrode, the size of the conductive material in the front silicon nitride layer is r 1 , the r 1 satisfies: 15μm ≤ r 1 ≤ 25μm.

[0011] According to some embodiments of the present utility model, the back electrode is distributed in a dot pattern or a line pattern on the back of the substrate.

[0012] According to some embodiments of the present utility model, the conductive material is a conductive paste or a conductive polymer material.

[0013] According to an embodiment of the second aspect of the present utility model, the present utility model provides a photovoltaic module, including: the battery according to the embodiment of the first aspect of the present utility model, and the battery includes the back electrode;

[0014] Backplane, the backplane includes a body portion and a third groove formed on the body portion, and the back electrode is close to the surface where the third groove is located and is disposed corresponding to the third groove.

[0015] According to some embodiments of the present invention, it further includes: a low-temperature solder paste portion, the low-temperature solder paste portion is disposed in the third groove, one end of the low-temperature solder paste portion is connected to the bottom of the third groove, and the other end extends in the depth direction of the third groove toward a direction away from the bottom of the third groove;

[0016] A medium-temperature solder paste portion, the medium-temperature solder paste portion is disposed on the surface of the back electrode.

[0017] According to some embodiments of the present invention, the backplane is a metal plate.

[0018] According to some embodiments of the present invention, the metal plate is an aluminum plate.

[0019] According to some embodiments of the present invention, in the depth direction of the third groove, the size of the low-temperature solder paste portion accounts for 50% to 80% of the depth of the third groove; and / or

[0020] The thickness of the metal plate is d 1 , wherein, the d 1 satisfies: 250μm ≤ d 1 ≤ 350μm; and / or

[0021] The depth of the third groove is d 2 , wherein, the d 2 satisfies: 150μm ≤ d 2 ≤ 200μm;

[0022] The thickness of the medium-temperature solder paste portion is d 4 , wherein, the d 4 satisfies: 80μm ≤ d 4 ≤ 100μm.

[0023] Additional aspects and advantages of the present invention will be given in part in the following description, become apparent in part from the following description, or be understood through the practice of the present invention. Description of the Drawings

[0024] Figure 1 is a process flow chart of a method for preparing a battery according to a specific embodiment of the present invention;

[0025] Figure 2 is according to the present invention Figure 1 a schematic diagram of the structure of one of the steps;

[0026] Figure 3is according to the present utility model Figure 1 is a schematic diagram of the structure of one of the steps;

[0027] Figure 4 is according to the present utility model Figure 1 is a schematic diagram of the structure of one of the steps;

[0028] Figure 5 is according to the present utility model Figure 1 is a schematic diagram of the structure of one of the steps;

[0029] Figure 6 is according to the present utility model Figure 1 is a schematic diagram of the structure of one of the steps;

[0030] Figure 7 is according to the present utility model Figure 1 is a schematic diagram of the structure of one of the steps;

[0031] Figure 8 is according to the present utility model Figure 1 is a schematic diagram of the structure of one of the steps;

[0032] Figure 9 is according to the present utility model Figure 1 is a schematic diagram of the structure of one of the steps;

[0033] Figure 10 is according to the present utility model Figure 1 is a schematic diagram of the structure of one of the steps;

[0034] Figure 11 is according to the present utility model Figure 1 is a schematic diagram of the structure of one of the steps;

[0035] Figure 12 is according to the present utility model Figure 1 is a schematic diagram of the structure of one of the steps;

[0036] Figure 13 is according to the present utility model Figure 1 is a schematic diagram of the structure of one of the steps;

[0037] Figure 14 is according to the present utility model Figure 1 is a schematic diagram of the structure of one of the steps;

[0038] Figure 15 is according to the present utility model Figure 1 is a schematic diagram of the structure of one of the steps;

[0039] Figure 16 is according to the present utility model Figure 1Schematic diagram of the structure of one of the steps;

[0040] Figure 17 is according to the present utility model Figure 1 Schematic diagram of the structure of one of the steps;

[0041] Figure 18 Schematic diagram of the battery structure according to another embodiment of the present utility model;

[0042] Figure 19 Schematic diagram of the battery structure according to still another embodiment of the present utility model (back electrode);

[0043] Figure 20 Schematic diagram of the battery structure according to yet another embodiment of the present utility model (back electrode);

[0044] Figure 21 Schematic diagram of the structure of a photovoltaic module according to an embodiment of the present utility model.

[0045] 100: Battery; 200: Photovoltaic module;

[0046] 1: Textured wafer; 2: First groove; 21: First opening; 22: Second opening; 4: Mask layer; 5: Diffusion layer; 6: Alumina layer; 7: Front-side silicon nitride layer; 8: Tunneling oxide layer - poly layer; 9: Back-side silicon nitride layer; 10: Silver electrode; 11: Conductive material; 12: Second groove; 13: Back electrode; 14: Backplane; 15: Borosilicate glass mask layer; 16: Phosphosilicate glass mask layer. Detailed implementation manners

[0047] Next, in conjunction with the appended Figures 18 - 20 The battery 100 of the embodiment of the present utility model will be described in detail.

[0048] In conjunction with Figure 18 , for the battery 100 according to the first aspect embodiment of the present utility model, the battery 100 includes a substrate, a front electrode, and a back electrode 13.

[0049] Wherein, the substrate includes a textured wafer 1, a diffusion layer 5, an alumina layer 6, and a front-side silicon nitride layer 7, and the diffusion layer 5, the alumina layer 6, and the front-side silicon nitride layer 7 are sequentially stacked in a direction away from the textured wafer 1 on the front side of the textured wafer 1.

[0050] Among them, one end of the front electrode is located in the diffusion layer 1, and the other end protrudes from the surface of the front silicon nitride layer 7. The front electrode includes a silver electrode 10 and a conductive material 11. The silver electrode extends from the diffusion layer 5 to the alumina layer 6. A part of the conductive material 11 is located in the front silicon nitride layer 7 and is connected to the silver electrode 10, and the other part of the conductive material 11 protrudes from the surface of the front silicon nitride layer 7. With such a setting, the front electrode includes a silver electrode 10 and a conductive material 11. The silver electrode 10 extends from the diffusion layer 5 to the alumina layer 6 and is embedded inside the substrate, which can prevent the front electrode from covering the surface of the battery 100, partially blocking the incident light or causing scattering of the incident light, thereby improving the optical conversion efficiency of the battery 100. The other end of the conductive material protrudes from the front of the substrate, facilitating the welding of the electrode. In this way, only the silver electrode 10 is provided in the diffusion layer 5 and the alumina layer 6, greatly saving the consumption of silver paste and reducing the cost. Among them, a pulse dropper can be used to drop silver paste at the bottom of the first groove 2. And by covering the bottom of the groove with silver paste to form the silver electrode 10, the conductive requirements of the grid line can be met. Secondly, a part of the conductive material 11 is located in the front silicon nitride layer 7 and is in contact with the silver electrode 10. In this way, the bonding area between the conductive material 11 and the silver electrode 10 is inside the substrate, which can enhance the bonding force between the conductive material 11 and the silver electrode 10 and improve the mechanical properties of the solder joint. Further, the welding between the front electrode and other components of the battery 100 is realized through the part of the conductive material 11 that protrudes from the front of the substrate, which has good corrosion resistance, high safety, and reliable welding.

[0051] Among them, the back electrode 13 is formed on the back of the substrate. With such a setting, by providing the back electrode 13, it is convenient to collect the back current, which is beneficial to improving the light conversion efficiency of the battery 100.

[0052] According to the battery 100 of the specific embodiment of the present utility model, one end of the front electrode is located in the diffusion layer 1, and the other end protrudes from the surface of the front silicon nitride layer 7. The front electrode includes a silver electrode 10 and a conductive material 11. The silver electrode extends from the diffusion layer 5 to the alumina layer 6. A part of the conductive material 11 is located in the front silicon nitride layer 7 and is connected to the silver electrode 10, and the other part of the conductive material 11 protrudes from the surface of the front silicon nitride layer 7. With such a setting, the front electrode includes the silver electrode 10 and the conductive material 11. The silver electrode 10 extends from the diffusion layer 5 to the alumina layer 6 and is embedded inside the substrate, which can prevent the front electrode from covering the surface of the battery 100, partially blocking the incident light or causing the scattering of the incident light, thereby improving the optical conversion efficiency of the battery 100. The other end of the conductive material protrudes from the front of the substrate, which is convenient for the welding of the electrode. In this way, only the silver electrode 10 is provided in the diffusion layer 5 and the alumina layer 6, which greatly saves the consumption of silver paste and the cost. Secondly, a part of the conductive material 11 is located in the front silicon nitride layer 7 and is in contact with the silver electrode 10. In this way, the bonding area between the conductive material 11 and the silver electrode 10 is inside the substrate, which can improve the bonding force between the conductive material 11 and the silver electrode 10 and improve the mechanical properties of the solder joint. Further, the welding between the front electrode and other components of the battery 100 is realized through the part of the conductive material 11 protruding from the front of the substrate, which has good corrosion resistance, high safety and reliable welding.

[0053] Combined Figure 18 , according to some embodiments of the present utility model, the substrate further includes a tunneling oxide layer - poly layer 8 and a back silicon nitride layer 9. The tunneling oxide layer - poly layer 8 and the back silicon nitride layer 9 are stacked in sequence on the back of the textured wafer 1 in a direction away from the textured wafer 1. Here, the textured wafer 1 can be obtained by texturing a silicon wafer. With such a setting, battery 100 components are provided. For example, the battery 100 components can be used to prepare a Topcon crystalline silicon battery 100.

[0054] According to some embodiments of the present utility model, in the width direction of the front electrode, the size of the conductive material 11 is larger than the size of the silver electrode 10. With such a setting, since the resistivity of the silver electrode 10 is less than that of the conductive material 11, and the size of the conductive material 11 is larger than the size of the silver electrode 10 in the width direction of the front electrode, it is beneficial to make the resistance of the front electrode consistent in the length direction and beneficial to improving the photoelectric conversion efficiency of the battery.

[0055] According to some embodiments of the present utility model, in the width direction of the front electrode, the size of the conductive material 11 in the front silicon nitride layer 7 is r 1 , r 1 satisfies: 15μm ≤ r 1 ≤ 25μm. With such a setting, if r 1Less than 15 μm, the size of the conductive material 11 in the front silicon nitride layer 7 is small, that is, in the width direction, the size of the front electrode is small, and the resistance of the front electrode may be large, affecting the light conversion efficiency of the battery 100; if r 1 Is greater than 25 μm, then in the width direction, the size of the conductive material 11 in the front silicon nitride layer 7 is large, and the area occupied on the surface of the battery 100 may be large, affecting the light conversion efficiency of the battery 100. By setting, r 1 Satisfies: 15 μm ≤ r 1 ≤ 25 μm, then in the width direction, the size of the conductive material 11 in the front silicon nitride layer 7 is appropriate, and the light conversion efficiency of the battery 100 is high. Optionally, r 1 Is 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, 21 μm, 22 μm, 23 μm, 24 μm or 25 μm, but not limited thereto. Among them, in order to embed the front electrode into the substrate, the position where the front electrode is embedded can be located by forming the first groove 2 on the front of the substrate, and the first groove 2 corresponds to the pattern of the front electrode. Specifically, combined with Figure 18, the first groove 2 includes a first opening 21 and a second opening 22. Among them, the opening of the first opening 21 is located on the front surface of the substrate, and the first opening 21 penetrates through the front surface silicon nitride layer 7 and the alumina layer 6 and extends into the interior of the diffusion layer 5. With such a setting, inside the substrate, a space for placing the silver electrode 10 and the conductive material 11 is provided, and the silver electrode 10 and the conductive material 11 can be placed in the first groove 2. The bonding site between the conductive material 11 and the silver electrode 10 is inside the substrate, which can improve the bonding force between the conductive material 11 and the silver electrode 10 and enhance the mechanical properties of the solder joint. And it can prevent the conductive material 11 from covering the surface of the battery 100, partially blocking the incident light or causing scattering of the incident light, thereby improving the optical conversion efficiency of the battery 100. And the laser etching opening has high precision and is easy to operate. Optionally, the first opening 21 is obtained by laser etching opening, and the power of the laser opening is 50-200W. In addition, the first opening 21 is located in the front surface silicon nitride layer 7, and is arranged radially from the outer periphery of the first opening 21 in a direction away from the first opening 21 and communicates with the first opening 21. With such a setting, on the one hand, it is convenient to place the silver electrode 10 and the conductive material 11 in the first groove 2, and the contact area between the conductive material 11 and other components of the battery 100 is increased through the second opening 22 on the periphery of the body part, thereby improving the welding reliability. At the same time, increasing the cross-sectional area of the conductive material 11 can reduce the resistance, thereby reducing the current loss, and further increasing the light conversion efficiency of the battery 100. On the other hand, the communicating first opening 21 and second opening 22 facilitate the formation of a dumbbell structure on both sides of the alumina layer 6. Specifically, in the area where the mask layer 4 and the front surface silicon nitride layer 7 are located, the size of the first groove 2 in the radial direction is enlarged through the second opening 22, increasing the accommodation space for the silver electrode 10, especially the conductive material 11. With such a setting, on the one hand, it is convenient to place the silver electrode 10 and the conductive material 11 in the first groove 2, and increase the cross-sectional area of the conductive material 11, reduce the resistance, thereby reducing the current loss, and further increasing the light conversion efficiency of the battery 100. On the other hand, during subsequent assembly, the contact area between the front protrusion and other components is increased, thereby improving the welding reliability. On the other hand, the front electrode 12 can be divided into a first part, a second part and a third part that are connected to each other. Among them, the first part is formed in the area where the alumina layer 6 is located. Since the radius of the first groove 2 in the area where the alumina layer 6 is located is smaller, the first part has a smaller radius along the radial direction of the groove; the second part is formed in the area where the mask layer 4 and the front surface silicon nitride layer 7 are located. Since the radius of the first groove 2 in the area where the second part is located is enlarged in the radial direction through the second opening 22, the radius of the second part (the end of the conductive material 11) is also larger; the third part is the silver electrode 10 formed in the area of the bottom of the first groove 2, that is, the diffusion layer 5, and the silver electrode 10 also forms a thick silver electrode 10 end after sintering.In this way, the second part and the third part with a larger radius are connected at both ends of the first part to form a dumbbell-shaped structure. Among them, the cross-sectional area of ​​the third part (the end of the thick silver electrode 10) is smaller than the cross-sectional area of ​​the second part (the end of the conductive material 11), and the resistivity of the silver electrode 10 is smaller than the resistivity of the conductive material 11. In this way, the resistance of the thick silver electrode 10 end is equivalent to the resistance of the conductive material 11 end, which is beneficial to improve the photoelectric conversion efficiency of the battery 100. In addition, the dumbbell-shaped structure is beneficial to increase the contact area between the silver paste and the substrate 1 and the contact area between the silver paste and the conductive paste, reduce the amount of silver paste, and reduce costs. Optionally, the method for obtaining the second opening 22 is wet chemical etching groove. Optionally, the groove can be selectively etched by wet chemical etching, and the operation is simple. Among them, during the etching process, due to the protective effect of aluminum oxide in the aluminum oxide layer 6 (AlOx layer), the etching mainly occurs in the aluminum oxide layer 6 (AlOx (Al. 2 O 3 Aluminum oxide) layer) outside the front silicon nitride layer 7 (SiNx (Si 3 N 4 ) film layer) area, and a very small amount occurs in the doped area of ​​the aluminum oxide layer 6. Among them, a pulse dropper can be used to drop silver paste at the bottom of the first groove 2. And by covering the bottom of the groove with silver paste to form a silver electrode 10, the conductive needs of the gate line can be met.

[0056] Combination Figure 19 and Figure 20 According to some embodiments of the present invention, the back electrode 13 is distributed in a dotted or linear manner on the back of the substrate. The shape and position of the back electrode 13 can be set as needed.

[0057] According to some embodiments of the utility model, the conductive material 11 is a conductive paste. In this way, the conductive paste (such as conductive solder paste) has good conductivity, safety and welding performance, and is relatively low in cost. In this way, the conductive material 11 is used to partially replace the silver paste as the front electrode, and the conductive material 11 welding wire is easier to weld, which can reduce energy consumption and accelerate the process. Among them, when the conductive material 11 is a conductive paste, the conductive paste can be printed on the silver electrode 10 by direct printing. Preferably, the conductive paste is a conductive solder paste.

[0058] Combination Figure 1 - Figure 17 According to some embodiments of the present invention, the present invention provides a method for preparing a battery 100, comprising the following steps:

[0059] Provide a substrate, the substrate including a front side and a back side; prepare a first trench 2 by grooving from the front side of the substrate towards the interior of the substrate to form a first trench 2 corresponding to the front gate pattern. With such a setting, through grooving, a space for placing silver paste and conductive material 11 is provided inside the substrate 1. For example, the silver paste and the conductive material 11 can be placed in the first trench 2, and the bonding area between the conductive material 11 and the silver paste is inside the coated substrate 1, which can enhance the bonding force between the conductive material 11 and the silver paste and improve the mechanical properties of the solder joints. It is easier to weld with the welding wire, reducing energy consumption; accelerating the manufacturing process; and it can prevent the silver paste and the conductive material 11 from covering the surface of the battery 100, partially blocking the incident light or causing scattering of the incident light, thereby improving the optical conversion efficiency of the battery 100.

[0060] Print a mask layer 4 on the area of the front side of the substrate outside the first trench 2. The method of printing the mask layer 4 is to adopt a wet slurry matching cleaning process step. With such a setting, through the wet INK slurry and the matching cleaning process, the unnecessary parts in the mask are removed, so that the structure and position of the mask match those of the first trench 2, preparing for further lithography to manufacture the battery 100.

[0061] Prepare a back electrode 13 by printing back gate lines on the back side of the substrate to form a back electrode 13. This step includes printing back gate lines on the back side of the substrate and drying them to form a back electrode 13. With such a setting, by providing the back electrode 13, the collection of the back current is facilitated, which is beneficial to improving the light conversion efficiency of the battery 100.

[0062] Prepare a front electrode. Lay a silver electrode 10 at the bottom of the first trench 2, then fill the first trench 2 with a conductive material 11 and make at least a part of the conductive material 11 protrude from the front side of the substrate to form a front protrusion, and cure the conductive material 11 to form a front electrode. With such a setting, first, only a small amount of silver paste is used by laying the silver electrode 10 only in the bottom area of the first trench 2, reducing the consumption of silver and saving costs. And by covering the bottom of the trench with the silver paste to form the silver electrode 10, the conductive requirements of the gate lines can be met. Secondly, a part of the conductive material 11 is in contact with the silver electrode 10 inside the first trench 2, so that the bonding area between the conductive material 11 and the silver electrode 10 is inside the substrate, which can enhance the bonding force between the conductive material 11 and the silver electrode 10 and improve the mechanical properties of the solder joints. Further, the welding between the front electrode and other components of the battery 100 is realized through the front protrusion, with good anti-corrosion performance, high safety and reliable welding.

[0063] According to the preparation method of the above-mentioned battery 100, a small amount of silver paste is spread over the bottom of the first groove 2 to form the silver electrode 10. In this way, when forming the positive electrode, only a small amount of silver paste is used in the bottom layer of the first groove 2, greatly reducing silver consumption and saving costs. Then, the conductive material 11 is printed on the silver electrode 10. In this way, the bonding area between the conductive material 11 and the silver electrode 10 is inside the substrate, which can improve the bonding force between the conductive material 11 and the silver electrode 10 and enhance the mechanical properties of the solder joints. Further, the conductive material 11 is filled into the first groove 2 and protrudes from one side surface to form a protrusion, which is the positive protrusion, and then the conductive material 11 is cured. With such a setting, it is convenient for welding between the conductive material 11 and other battery 100 components, and it has good corrosion resistance, high safety, and reliable welding.

[0064] Combine Figure 1 - Figure 3 , according to some embodiments of the present invention, the preparation of the substrate includes the following steps:

[0065] Prepare the textured wafer 1 by texturing the silicon wafer to obtain the textured wafer 1. With such a setting, a more obvious concave-convex surface effect is formed on the surface of the silicon wafer, increasing the number of refractions of light on the surface of the battery cell and increasing the absorption of light.

[0066] Prepare the diffusion layer 5 by performing high-temperature boron diffusion on the textured wafer 1 to form the diffusion layer 5. With such a setting, a boron diffusion layer can be doped from the surface to the inside of the textured wafer 1. Optionally, in order to meet the requirements of boron diffusion, the temperature of the boron diffusion process can be controlled at 800-950 degrees Celsius, the pressure can be 50-300 mbar, the boron source is boron trichloride, the volume flow rate of boron trichloride gas is 50-1000 sccm, and the deposition time is 30-2000 seconds. Further, in order to react silicon on the surface of the silicon wafer with oxygen to generate silicon dioxide and form an oxide layer on the surface of the silicon wafer, oxygen can be introduced during the boron diffusion process. For example, the volume flow rate of oxygen introduced into the diffusion furnace can be 500-5000 sccm, and the introduction time is 100-1000 seconds. In this way, the oxide layer has an adsorption effect on the boron source, causing the boron source to be adsorbed on the surface of the silicon wafer, which is beneficial to improving the uniformity of the boron source in the diffusion furnace. Among them, during the process of preparing the diffusion layer 5 in this step, boron diffusion layers 5 and boron-silicon glass mask layers 15 are formed on the front, back, and periphery of the textured wafer 1.

[0067] The first cleaning is to remove the boron diffusion layer on the back and outer peripheral side of the substrate and the boron diffusion layers 5 and boron-silicon glass mask layers 15 formed on the front, back, and periphery of the textured wafer 1. In this step, the boron diffusion layer and boron-silicon glass (BSG) mask on the back and both sides can be cleaned off by the alkali polishing cleaning method.

[0068] Prepare the tunneling oxide layer - poly layer 8. Use the Poly deposition process to sequentially deposit the tunneling oxide layer - poly layer 8 on the back of the substrate, and perform high-temperature annealing. In this step, first deposit a 1 - 2 nm tunneling oxide layer on the back of the textured wafer 1 using the poly deposition process, and then deposit one or more layers of phosphorus-doped amorphous silicon layers on the surface of the tunneling oxide layer; when depositing the phosphorus-doped amorphous silicon layer, control the flow rate of phosphine between 100 - 1500 sccm. Then, perform high-temperature (800 - 950 °C) annealing treatment to stimulate the inward diffusion of phosphorus in the tunneling oxide layer - poly layer 8 to form an n++ layer. Among them, during the deposition of the tunneling oxide layer - poly layer 8 in this step, the tunneling oxide layer - poly layer 8 and the phosphosilicate glass mask layer 16 are formed on the back and around the textured wafer 1.

[0069] Second cleaning, remove the tunneling oxide layer - poly layer 8 and the phosphosilicate glass mask layer 16 formed on the back and around the textured wafer 1. In this step, use the alkali polishing cleaning method again to clean the surrounding tunneling oxide layer - poly layer 8 and the back phosphosilicate glass (PSG) film layer; then, perform RCA standard cleaning method treatment to further clean the front BSG and the back PSG.

[0070] Prepare the alumina layer 6 and the front silicon nitride layer 7. Sequentially deposit the oxide layer 6 and the front silicon nitride layer 7 on the surface of the diffusion layer 5. In this step, after the RCA standard cleaning, the precursor is deposited and grown into a 3 - 8 nm alumina layer 6 (AlOx:H film) in the ALD equipment.

[0071] Prepare the back silicon nitride layer 9. Deposit the silicon nitride layer on the surface of the tunneling oxide layer - poly layer 8. In this step, further deposit a multi-layer back silicon nitride layer 9 (SiNx:H film) structure with a gradually changing refractive index on the surface of the PSG on the back of the silicon wafer.

[0072] Bond Figure 1 Figures 11 - 12According to some embodiments of the utility model, preparing the first groove 2 includes: forming a first opening 21 (laser opening) and forming a second opening 22 (wet etching groove). Among them, the first opening 21 is formed by laser etching on the front side of the substrate facing the inside of the substrate, and the first opening 21 penetrates the front silicon nitride layer 7 and the aluminum oxide layer 6, and extends to the inside of the diffusion layer 5. In this way, by etching the opening, a space is provided inside the substrate for the silver electrode 10 and the conductive material 11 to be placed, and the silver electrode 10 and the conductive material 11 can be placed in the first groove 2. The binding site of the conductive material 11 and the silver electrode 10 is inside the substrate, which can enhance the binding force between the conductive material 11 and the silver electrode 10 and improve the mechanical properties of the solder joint. And it can avoid the conductive material 11 covering the surface of the battery 100, partially blocking the incident light or causing the incident light to scatter, thereby improving the optical conversion efficiency of the battery 100. And the laser etching opening has high precision and simple operation. Optionally, the power of the laser opening is 50 to 200W. In addition, in the front silicon nitride layer 7, a second opening 22 is formed by chemical etching from the outer periphery of the first opening 21 in a radial direction away from the first opening 21, and the second opening 22 extends from the front of the substrate to the inside of the front silicon nitride layer 7. In this way, on the one hand, it is convenient to place the silver electrode 10 and the conductive material 11 in the first groove 2, and increase the contact area between the conductive material 11 and other battery 100 components through the second opening 22 on the periphery of the main body, thereby improving the reliability of welding. At the same time, increasing the cross-sectional area of ​​the conductive material 11 can reduce resistance, thereby reducing current loss, and then increasing the light conversion efficiency of the battery 100. On the other hand, the through first opening 21 and second opening 22 facilitate the formation of a dumbbell structure on both sides of the aluminum oxide layer 6. Among them, the method of etching and grooving is wet chemical etching and grooving. Optionally, the groove can be selectively etched by wet chemical etching, which is simple to operate. During the etching process, due to the protective effect of aluminum oxide in the aluminum oxide layer 6 (AlOx layer), the etching mainly occurs in the aluminum oxide layer 6 (AlOx (Al 2 O 3 Aluminum oxide) layer) outside the front silicon nitride layer 7 (SiNx (Si 3 N 4 ) film layer) area, and a very small amount occurs in the doped area of ​​the aluminum oxide layer 6.

[0073] Combination Figure 1 and Figure 14 According to some embodiments of the present invention, laying the silver electrode 10 at the bottom of the first groove 2 includes the following steps: using a pulse dropper to drop silver paste at the bottom of the first groove 2 until the silver paste completely covers the bottom of the first groove 2. In this way, the amount of silver paste added can be accurately controlled.

[0074] According to some embodiments of the utility model, the dripping speed is V, and V satisfies: 0.05mL / s≤V≤0.2mL / s. In this way, if V is less than 0.05mL / s, the dripping speed is slow, the dripping process is long, and the cost is high; if V is less than 0.2mL / s, the dripping speed is fast, which is not conducive to the uniform paving of the silver paste at the bottom of the first groove 2, and may affect the performance of the front electrode. By setting so that V satisfies 0.05mL / s≤V≤0.2mL / s, the dripping speed is appropriate, the cost is low, and the performance of the front electrode can be guaranteed.

[0075] According to some embodiments of the utility model, the conductive material 11 includes at least one of a conductive paste and a conductive polymer material. In this way, the conductive paste and the conductive polymer material have good conductivity, safety and welding performance. In this way, a conductive polymer and a conductive paste are used to replace the silver electrode 10 on one side surface of the substrate 1 (the front of the battery 100), and the welding wire is easier to weld, which can reduce energy consumption and accelerate the process. Among them, when the conductive material 11 is a conductive solder paste, the conductive solder paste is printed on the silver paste by direct printing. Preferably, the conductive paste is a conductive solder paste. When the conductive material 11 is a conductive polymer, it is printed on the silver paste in the form of inkjet printing.

[0076] According to some other embodiments of the present invention, curing the conductive material 11 includes: curing the conductive material 11 by heating with an infrared lamp. In this way, the heating method has high reliability and high safety.

[0077] Combination Figure 1 and Figure 13 According to some embodiments of the present invention, preparing the back electrode 13 includes: making a groove on the back of the substrate toward the inside of the substrate; forming a second groove 12 corresponding to the pattern of the back electrode 13; filling the second groove 12 with a conductive paste, with a portion of the conductive paste protruding from the back, and drying to form the back electrode 13. Such a configuration can prevent the conductive paste from covering the back of the battery 100, partially blocking the incident light or causing the incident light to scatter, thereby improving the optical conversion efficiency of the battery 100 (back).

[0078] Combination Figure 19 and Figure 20 According to some embodiments of the present invention, the protruding parts of the conductive paste are distributed in a dotted or linear manner on the back surface. In this way, the shape and position of the back surface grid can be set as needed.

[0079] According to some embodiments of the present invention, the method further includes: before preparing the back electrode 13, ozone is used to clean and passivate the groove area of ​​the second groove 12. Such a configuration facilitates the connection and conduction between the silver paste and the substrate.

[0080] According to some embodiments of the present invention, in combination with Figure 1 - Figure 17 , the present invention provides a method for preparing a Topcon crystalline silicon cell 100, comprising the following steps:

[0081] In combination with Figure 1 and Figure 2 , prepare the textured wafer 1 by texturing the silicon wafer to obtain the textured wafer 1;

[0082] In combination with Figure 1 and Figure 3 , prepare the diffusion layer 5 by performing high-temperature boron diffusion on the textured wafer 1 to form the diffusion layer 5;

[0083] In combination with Figure 1 and Figure 4 , perform the first cleaning to remove the diffusion layer 5 and the borosilicate glass mask layer 15 on the back and the outer peripheral side of the substrate;

[0084] In combination with Figure 1 、 Figure 5 and Figure 6 , prepare the tunneling oxide layer - poly layer 8 by sequentially depositing the tunneling oxide layer - poly layer 8 on the back of the substrate using a Poly deposition process and performing high-temperature annealing;

[0085] In combination with Figure 1 and Figure 7 , perform the second cleaning to remove the tunneling oxide layer - poly layer 8 and the phosphosilicate glass mask layer 16 on the back and the front of the substrate;

[0086] In combination with Figure 1 and Figure 8 , prepare the alumina layer 6 and the front-side silicon nitride layer 7 by sequentially depositing the alumina layer 6 and the front-side silicon nitride layer 7 on the surface of the diffusion layer 5;

[0087] In combination with Figure 1 and Figure 9 , prepare the back-side silicon nitride layer 9 by depositing the back-side silicon nitride layer 9 on the surface of the tunneling oxide layer - poly layer 8, and the above steps obtain the substrate;

[0088] In combination with Figure 1 and Figure 10 , prepare the first opening 21 by laser etching towards the inside of the substrate on the front of the substrate. The first opening 21 penetrates through the front-side silicon nitride layer 7 and the alumina layer 6 and extends into the inside of the diffusion layer 5;

[0089] In combination with Figure 1 and Figure 11 , print the mask layer 4 in the area outside the first groove 2 on the front of the substrate;

[0090] In combination with Figure 1 、Figure 12 and Figure 17 In the front-side silicon nitride layer 7, a second opening 22 is formed by chemically etching and grooving radially from the outer periphery of the first opening 21 in a direction away from the first opening 21. The second opening 22 extends from the front side of the substrate into the interior of the front-side silicon nitride layer 7. In this way, the first groove 2 corresponding to the front-side electrode pattern is formed;

[0091] Clean and passivate. The grooved area of the second groove 12 is cleaned and passivated using ozone.

[0092] Combine Figure 1 and Figure 13 to prepare the back-side electrode 13. The back-side grid lines are printed on the back side of the substrate and dried to form the back-side electrode 13;

[0093] Combine Figure 1 and Figure 14 to prepare the silver electrode 10. Silver paste is laid at the bottom of the first groove, and metallization is performed to form the silver electrode 10;

[0094] Combine Figure 1 and Figure 15 to print the conductive material 11. The first groove 2 is filled with the conductive material 11, and at least a part of the conductive material 11 protrudes from the front side of the substrate to form a front-side protrusion;

[0095] Combine Figure 1 and Figure 16 to cure the conductive material 11 to form the front-side electrode. Thus, the Topcon crystalline silicon cell 100 of an embodiment of the present invention is obtained.

[0096] According to the preparation method of the Topcon crystalline silicon cell of the specific embodiment of the present invention, when preparing the front-side electrode, only the bottom layer of the first groove 2 is filled with an appropriate amount of silver paste to form the silver electrode 10, which greatly saves the consumption of silver and reduces the cost; and the bonding area between the conductive material 11 and the silver paste electrode 10 is inside the substrate, which greatly improves the bonding force between the conductive material 11 and the silver paste electrode 10 and improves the mechanical properties of the solder joints. When preparing the first groove, by laser grooving, the first opening 21 is first opened on the alumina layer 6, and then, the second opening is formed by wet etching to form a dumbbell-shaped first groove 2 on both sides of the alumina layer 6, which is convenient for filling the front-side electrode material and controlling the conductivity of the front-side electrode.

[0097] Combine Figure 21 According to the embodiment of the second aspect of the present invention, the present invention provides a photovoltaic module 200, including: the cell 100 according to the embodiment of the first aspect of the present invention and a backplane 14. Wherein, the cell 100 includes a back-side electrode 13; the backplane 14 includes a body part and a third groove formed on the body part, and the back-side electrode 13 is close to the surface where the third groove is located and is correspondingly arranged with the third groove.

[0098] For the photovoltaic module 200 according to the specific embodiments of the present utility model, the integration of the backsheet 14 can significantly reduce the resistance of the backsheet 14, and reduce the heat loss and encapsulation loss of the photovoltaic module 200.

[0099] According to some embodiments of the present utility model, the photovoltaic module 200 further includes a low-temperature solder paste part and a medium-temperature solder paste part. Among them, the low-temperature solder paste part is arranged in the third groove, one end of the low-temperature solder paste part is connected to the bottom of the third groove, and the other end extends in the depth direction of the third groove away from the bottom of the third groove. With such an arrangement, since the back electrodes 13 correspond to the third grooves one by one, the low-temperature solder paste part forms a root-like bonding area in the backsheet 14, and the bonding sites between the back electrodes 13 and the low-temperature solder paste part are wrapped inside the backsheet 14, which can enhance the bonding force between the back electrodes 13 and the backsheet 14. In addition, the medium-temperature solder paste part is arranged on the surface of the back electrode 13. With such an arrangement, by arranging the medium-temperature solder paste part on the back electrode 13, the thickness of the back electrode 13 can be increased, and it is convenient to connect the back electrode 13 and the low-temperature solder paste part through the medium-temperature solder paste part. Optionally, the medium-temperature solder paste part is formed by printing a medium-temperature solder paste on the back electrode 13 and heating and curing it.

[0100] According to some embodiments of the present utility model, the backsheet 14 is a metal plate. With such an arrangement, the metal plate has good waterproofness and strong load-bearing capacity, thereby enhancing the waterproof vapor penetration performance and load-bearing performance of the backsheet 14, and the module is safer and more reliable.

[0101] According to some other embodiments of the present utility model, the metal plate is an aluminum plate. The aluminum plate is light in weight, low in cost, and convenient for assembly, thereby reducing the production cost of the backsheet 14.

[0102] According to some embodiments of the present utility model, in the depth direction of the third groove, the size of the low-temperature solder paste part accounts for 50% - 80% of the depth of the third groove. With such an arrangement, the low-temperature solder paste is arranged in the third groove, and the position of the raised area of the back electrode 13 corresponds to the third groove, and the solder paste forms a root-like bonding area in the lightweight aluminum plate. Optionally, the height of the low-temperature solder paste in the third groove accounts for 50%, 60%, 70% or 80% of the depth of the third groove. But it is not limited thereto. Preferably, the height of the low-temperature solder paste in the third groove accounts for 60% of the depth of the third groove.

[0103] According to some embodiments of the present utility model, the thickness of the metal plate is d 1 , where d 1 satisfies: 250μm ≤ d 1 ≤ 350μm. With such an arrangement, if d 1 is less than 250μm, the thickness of the metal plate is small, the reliability is poor, and it is not convenient to form the third groove on the metal plate; if d 1If it is greater than 350 μm, the thickness of the metal plate is relatively large, making the metal plate heavier and inconvenient for assembly and transportation. By setting such that d 1 satisfies 250 μm ≤ d 1 ≤ 350 μm, the thickness of the metal plate is appropriate, with strong reliability and convenient for assembly and transportation. Optionally, d 1 is 250 μm, 250 μm, 260 μm, 270 μm, 280 μm, 290 μm, 300 μm, 310 μm, 320 μm, 330 μm, 340 μm or 350 μm. But it is not limited thereto.

[0104] According to some embodiments of the present invention, the depth of the third groove is d 2 , wherein, d 2 satisfies: 150 μm ≤ d 2 ≤ 200 μm. With such a setting, if d 2 is less than 150 μm, the depth of the third groove is relatively small, the accommodating space for the low-temperature solder paste part is small, the size of the low-temperature solder paste part is small, and the reliability during connection is poor; if d 2 is greater than 200 μm, the depth of the third groove is relatively large, which requires a relatively large thickness of the metal plate and a relatively large size of the low-temperature solder paste part, resulting in a higher cost. By setting such that d 2 satisfies 150 μm ≤ d 2 ≤ 200 μm, the depth of the third groove is appropriate, and a low-temperature solder paste part with a suitable size can be set, and the reliability of component connection is high. Optionally, d 2 is 150 μm, 155 μm, 160 μm, 165 μm, 170 μm, 175 μm, 180 μm, 185 μm, 190 μm, 195 μm or 200 μm. But it is not limited thereto.

[0105] According to some embodiments of the present invention, the thickness of the medium-temperature solder paste part is d 4 , wherein, the d 4 satisfies: 80 μm ≤ d 4 ≤ 100 μm. With such a setting, if d 4 is less than 80 μm, the thickness of the medium-temperature solder paste part is relatively small, and the reliability of soldering of the medium-temperature solder paste part may be poor; if d 4 is greater than 100 μm, the thickness of the medium-temperature solder paste part is relatively large, resulting in a higher cost. And the thickness of the medium-temperature solder paste part needs to match the depth of the third groove and the height of the low-temperature solder paste part in the third groove, and the following conditions need to be satisfied: the depth of the third groove = the medium-temperature solder paste part + the height of the low-temperature solder paste part in the third groove. By setting such that d 4 satisfies 80 μm ≤ d 4≤100 μm. The thickness of the medium-temperature solder paste portion is appropriate, with strong soldering reliability and a high degree of matching with the depth of the third groove and the height of the low-temperature solder paste portion in the third groove. Optionally, d 4 is 80 μm, 85 μm, 90 μm, 95 μm or 100 μm. However, it is not limited thereto.

[0106] According to some other embodiments of the present invention, a conductive pattern is further formed on the body portion, and a buffer insulating glue is applied on the conductive pattern. With such a setting, the buffer insulating glue can provide a protective effect for the conductive pattern when the third groove is etched.

[0107] According to some other embodiments of the present invention, the thickness of the buffer insulating glue is d 3 , where d 3 satisfies: 10 μm ≤ d 3 ≤ 20 μm. With such a setting, if d 3 is less than 10 μm, the thickness of the buffer insulating glue is small, and the insulating protection performance of the buffer insulating glue may be poor; if d 3 is greater than 20 μm, the thickness of the buffer insulating glue is large, the total thickness of the integrated metal plate is thick, the cost is high, and it is not convenient for assembly. By setting d 3 to satisfy 10 μm ≤ d 3 ≤ 20 μm, the thickness of the buffer insulating glue is appropriate, with good insulating protection performance, and it is convenient for assembly and transportation. Optionally, d 2 is 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm or 20 μm. However, it is not limited thereto.

[0108] According to some embodiments of the present invention, the photovoltaic module 200 further includes: a front cover plate and welding wires. The front cover plate and the conductive material 11 are welded through the welding wires, and the welding between the welding wires and the conductive paste is easier, which can reduce the energy consumption during the assembly process of the photovoltaic module 200 and accelerate the manufacturing process of the photovoltaic module 200.

[0109] In the description of this specification, the description referring to terms such as "one embodiment", "some embodiments", "schematic embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example.

[0110] Although embodiments of the present utility model have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present utility model. The scope of the present utility model is defined by the claims and their equivalents.

Claims

1. A battery, characterized in that: include: A substrate, the substrate comprising a velvet sheet, a diffusion layer, an aluminum oxide layer, and a front silicon nitride layer, wherein the diffusion layer, the aluminum oxide layer, and the front silicon nitride layer are stacked in sequence on the front side of the velvet sheet in a direction away from the velvet sheet; a front electrode, one end of which is located in the diffusion layer, and the other end of which protrudes from the surface of the front silicon nitride layer, the front electrode comprising a silver electrode and a conductive material, the silver electrode extending from the diffusion layer to the aluminum oxide layer, a portion of the conductive material being located in the front silicon nitride layer and connected to the silver electrode, and another portion of the conductive material protruding from the surface of the front silicon nitride layer; A back electrode is formed on the back side of the substrate.

2. The battery according to claim 1, characterized in that The substrate further comprises: A tunneling oxide layer-poly layer and a back silicon nitride layer are sequentially stacked on the back side of the velvet sheet in a direction away from the velvet sheet.

3. The battery according to claim 1, characterized in that In a width direction of the front electrode, a size of the conductive material is larger than a size of the silver electrode.

4. The battery according to claim 3, characterized in that In the width direction of the front electrode, the size of the conductive material on the front silicon nitride layer is r1, and r1 satisfies: 15 μm≤r1≤25 μm.

5. The battery according to claim 1, characterized in that The back electrodes are distributed in a dotted or line-shaped manner on the back side of the substrate.

6. The battery according to claim 1, characterized in that The conductive material is conductive paste.

7. A photovoltaic module, characterized in that: include: The battery according to any one of claims 1 to 6, comprising the back electrode; The back plate comprises a main body and a third groove formed on the main body, and the back electrode is close to the surface where the third groove is located and is arranged corresponding to the third groove.

8. The photovoltaic module according to claim 7, characterized in that: Also includes: A low-temperature solder paste portion, wherein the low-temperature solder paste portion is disposed in the third groove, one end of the low-temperature solder paste portion is connected to the bottom of the third groove, and the other end of the low-temperature solder paste portion extends in a depth direction of the third groove in a direction away from the bottom of the third groove; A medium-temperature solder paste portion is provided on the surface of the back electrode.

9. The photovoltaic module according to claim 8, characterized in that: The back plate is a metal plate.

10. The photovoltaic module according to claim 9, characterized in that: The metal plate is an aluminum plate.

11. The photovoltaic module according to claim 9, characterized in that: In the depth direction of the third groove, the size of the low-temperature solder paste portion accounts for 50% to 80% of the depth of the third groove; and / or The thickness of the metal plate is d1, wherein d1 satisfies: 250 μm≤d1≤350 μm; and / or The depth of the third groove is d2, wherein d2 satisfies: 150 μm≤d2≤200 μm; The thickness of the medium-temperature solder paste portion is d4, wherein d4 satisfies: 80 μm≤d4≤100 μm.

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