Back contact solar cell and method for manufacturing the same

Abstract

The present invention relates to a back-contact solar cell and a method for making the same. The method for making the back-contact solar cell comprises: providing a substrate, the substrate comprising a substrate, a first tunneling material layer stacked on each surface of the substrate, a first doped polysilicon material layer and a first mask material layer; removing the portion of the first mask material layer corresponding to the second region and the isolation region, and cutting the substrate into at least two sub-substrates along the thickness direction; using a first acidic cleaning liquid to remove the portion of the first mask material layer corresponding to the side and the second surface of the sub-substrate, and cleaning the cut section; using a second alkaline cleaning liquid to remove the portion of the first tunneling material layer and the first doped polysilicon material layer corresponding to the second surface, the side, the second region and the isolation region of the sub-substrate, and cleaning the section to form a first passivation contact structure covering the first region. The back-contact solar cell and the method for making the same of the present invention have a high cell efficiency.

Description

Technical Field

[0001] The present invention relates to the field of photovoltaic technology, and in particular to a back-contact solar cell and a manufacturing method thereof. Background Art

[0002] In the manufacturing process of solar cells, in order to reduce the grid resistance loss during current transmission and increase the overall output power of the module, the whole solar cell will be cut into multiple smaller cells. When using laser to cut solar cells, the laser is usually used to locally cut and melt along the preset cutting position of the solar cell, and then the solar cell is divided into multiple smaller cells through the splitting process. However, laser damage will occur at the cross section of the cell obtained after cutting, and the laser damage will become the recombination center of photogenerated carriers, which will lead to a decrease in the photoelectric conversion efficiency of the solar cell after cutting. Summary of the invention

[0003] Based on this, it is necessary to provide a back-contact solar cell with higher efficiency and a method for manufacturing the same.

[0004] A first aspect of an embodiment of the present application provides a method for manufacturing a back-contact solar cell, comprising:

[0005] A substrate is provided, the substrate comprising a substrate, a first tunneling material layer, a first doped polysilicon material layer and a first mask material layer stacked on each surface of the substrate, wherein the substrate comprises a first surface and a second surface arranged opposite to each other and a side surface adjacent to the first surface and the second surface, and the first surface comprises a first region, a second region and an isolation region isolated between the first region and the second region;

[0006] removing the portion of the first mask material layer corresponding to the second region and the isolation region, and cutting the substrate into at least two sub-substrates along the thickness direction;

[0007] Using a first acid cleaning solution to remove the portion of the first mask material layer in the sub-substrate corresponding to the side surface and the second surface, and cleaning the cut section;

[0008] The first tunneling material layer and the first doped polysilicon material layer in the sub-substrate corresponding to the second surface, side surface, second area and isolation area are removed by using a second alkaline cleaning solution, and the cross section is cleaned to form a first passivation contact structure covering the first area.

[0009] In one embodiment, during the cutting process, a damage structure is formed on the cross section of the sub-substrate, the damage structure comprising a main body and an oxide layer covering the main body;

[0010] The step of cleaning the cut section with the first acid cleaning solution specifically includes: cleaning and removing the oxide layer with the first acid cleaning solution.

[0011] In one embodiment, the step of cleaning the cross section with the second alkaline cleaning solution specifically includes:

[0012] The main body in the damaged structure is at least partially removed by using a second alkaline cleaning solution.

[0013] In one embodiment, the thickness of the first mask material layer is 70 nm-80 nm.

[0014] In one embodiment, the second alkaline cleaning solution is an alkaline solution with a mass concentration of 8%-12%, and the cleaning time of the second alkaline cleaning solution is 200s-380s.

[0015] In one embodiment, in the step of cutting the substrate into at least two sub-substrates along the thickness direction, the cutting is performed from the second surface.

[0016] In one embodiment, after the step of forming the first passivation contact structure, the step further includes:

[0017] A second tunneling material layer and a second doped polysilicon material layer are sequentially stacked on each surface of the sub-substrate, and a second mask is formed at a position corresponding to the second area on the second doped polysilicon material layer;

[0018] Using a second mask, the second tunneling material layer and the second doped polysilicon material layer in the sub-substrate corresponding to the second surface, side surface, section, first area and isolation area are removed, and the section is cleaned again to form a second passivation contact structure covering the second area.

[0019] In one embodiment, the step of forming a second mask at a position corresponding to the second region on the second doped polysilicon material layer specifically includes:

[0020] forming a second mask material layer on a surface of the second doped polysilicon material layer facing away from the substrate;

[0021] The portion of the second mask material layer corresponding to the first area and the isolation area is removed by laser film opening, and the portion of the second mask material layer corresponding to the second surface and the side surface is removed by a third acid cleaning solution.

[0022] In one embodiment, the steps of removing the second tunneling material layer and the second doped polysilicon material layer in the sub-substrate corresponding to the second surface, the side surface, the cross section, the first region and the isolation region by using the second mask, and cleaning the cross section again specifically include:

[0023] The second tunneling material layer and the second doped polysilicon material layer in the sub-substrate corresponding to the second surface, side surface, section, first area and isolation area are removed using the fourth alkaline cleaning solution, and the section is cleaned again using the fourth alkaline cleaning solution.

[0024] In one embodiment, the thickness of the second mask is 70nm-80nm.

[0025] In one embodiment, after the step of forming the second passivation contact structure, the step further includes:

[0026] removing the second mask and the first mask material layer covering the surface of the first passivation contact structure;

[0027] In the sub-substrate, a first passivation layer and a second passivation layer are formed on the first surface side and the second surface side respectively, and a side passivation layer is also formed on the side surface and the cross section.

[0028] In one embodiment, the side passivation layer and the first passivation layer are formed in the same process; or the side passivation layer and the second passivation layer are formed in the same process.

[0029] A second aspect of an embodiment of the present application provides a back-contact solar cell, which is manufactured using the above-mentioned method for manufacturing a back-contact solar cell.

[0030] Beneficial effects of the above-mentioned back contact solar cell and its manufacturing method:

[0031] By cutting the substrate before the step of removing the portion of the first mask material layer corresponding to the side and the second surface in the sub-substrate using the first acidic cleaning liquid, and also using the first acidic cleaning liquid and the second alkaline cleaning liquid to clean the cut section, the cutting damage generated on the section can be removed as much as possible, and the influence of the cutting damage on the photoelectric conversion efficiency of the cell after cutting can be avoided. In addition, since the first acidic cleaning liquid and the second alkaline cleaning liquid used to clean the section are used to remove the first mask material layer, the first tunneling material layer and the first doped polysilicon material layer in the manufacturing process, respectively, the cleaning of the section can be carried out using the first acidic cleaning liquid and the second alkaline cleaning liquid that already exist in the process, without the need for additional cleaning liquids and cleaning processes, thereby saving the number of processes and reducing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A schematic diagram of the structure of a back-contact solar cell provided in an embodiment of the present application;

[0033] Figure 2 A schematic diagram of a process for manufacturing a back-contact solar cell provided in an embodiment of the present application;

[0034] Figure 3 A schematic diagram of the structure of a substrate in a method for manufacturing a back-contact solar cell provided in an embodiment of the present application;

[0035] Figure 4 A schematic diagram of opening the first mask material layer in the method for manufacturing a back-contact solar cell provided in an embodiment of the present application;

[0036] Figure 5 A schematic diagram of cutting a substrate in a method for manufacturing a back-contact solar cell provided in an embodiment of the present application;

[0037] Figure 6 A schematic diagram of using a first cleaning liquid to clean a sub-substrate in a method for manufacturing a back-contact solar cell provided in an embodiment of the present application;

[0038] Figure 7 A schematic diagram of using a second alkaline cleaning solution to clean a second sub-substrate in a method for manufacturing a back-contact solar cell provided in an embodiment of the present application.

[0039] Figure 8 A schematic diagram of forming a second tunneling material layer, a second doped polysilicon material layer, and a second mask material layer in a method for manufacturing a back-contact solar cell provided in an embodiment of the present application;

[0040] Fig. 9 A schematic diagram of forming a second mask in the method for manufacturing a back-contact solar cell provided in an embodiment of the present application;

[0041] Fig.10 A schematic diagram of using a fourth alkaline cleaning solution to clean a sub-substrate in a method for manufacturing a back-contact solar cell provided in an embodiment of the present application;

[0042] Fig.11 A schematic diagram of forming a first passivation contact structure in a method for manufacturing a back-contact solar cell provided in an embodiment of the present application;

[0043] Fig.12 A schematic diagram of forming a second tunneling material layer, a second doped polysilicon material layer, and a second mask material layer in a method for manufacturing a back-contact solar cell provided in an embodiment of the present application;

[0044] Fig.13 A schematic diagram of opening the second mask material layer in the method for manufacturing a back-contact solar cell provided in an embodiment of the present application;

[0045] Fig.14 A schematic diagram of cutting a substrate in a method for manufacturing a back-contact solar cell provided in an embodiment of the present application;

[0046] Fig.15A schematic diagram of removing the second mask material layer on one side and the side surface of the second surface in the method for manufacturing a back-contact solar cell provided in an embodiment of the present application.

[0047] Description of Figure Numbers:

[0048] 100, back contact solar cell; 101, substrate; 102, sub-substrate;

[0049] 10. substrate; 20. first passivation contact structure; 21. first tunneling oxide layer; 22. first doped polysilicon layer; 30. second passivation contact structure; 31. second tunneling oxide layer; 32. second doped polysilicon layer; 40. isolation trench; 41. velvet structure; 50. damage structure; 51. main body; 52. oxide layer;

[0050] 61, first passivation layer; 62, second passivation layer; 63, side passivation layer; 610, anti-reflection film layer; 620, passivation film layer;

[0051] 71. a first tunneling material layer; 72. a first doped polysilicon material layer; 73. a first mask material layer;

[0052] 81. a second tunneling material layer; 82. a second doped polysilicon material layer; 83. a second mask material layer; 84. a second mask;

[0053] 91. a first electrode; 92. a second electrode;

[0054] F, first side; S, second side; C, side; Q, cross section; Y, first zone; E, second zone; G, isolation zone. DETAILED DESCRIPTION

[0055] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention 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 invention. However, the present invention 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 invention, so the present invention is not limited by the specific embodiments disclosed below.

[0056] In the description of the present invention, it should be understood that 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" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0057] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0058] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral 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 the present invention can be understood according to specific circumstances.

[0059] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a 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. A first feature being "below", "below" or "below" a 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.

[0060] It should be noted that when 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. When 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. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used herein are for illustrative purposes only and are not intended to be the only implementation method.

[0061] The back contact solar cell of the embodiment of the present application is described below in conjunction with the accompanying drawings. In the present application, the back contact solar cell is a TBC cell as an example for description, and the back contact solar cell can also be other types of cells, and the back contact solar cell is other types of cases similar to this, which will not be repeated here.

[0062] Figure 1 A schematic diagram of the structure of a back-contact solar cell provided in an embodiment of the present application.

[0063] Reference Figure 1 The back-contact solar cell 100 provided in the embodiment of the present application can be manufactured using the method for manufacturing a back-contact solar cell described below.

[0064] The back-contact solar cell 100 of the embodiment of the present application includes: a substrate 10 , a first passivation contact structure 20 and a second passivation contact structure 30 , a first passivation layer 61 , a second passivation layer 62 , a side passivation layer 63 , and a first electrode 91 and a second electrode 92 .

[0065] The substrate 10 includes a first surface F and a second surface S that are arranged opposite to each other, and a side surface C and a cross section Q adjacent to the first surface F and the second surface S. The cross section Q is a cut surface formed by cutting. The first surface F includes a first region Y, a second region E, and an isolation region G isolated between the first region Y and the second region E. Here, the conductivity types of the doped polysilicon covered on the first region Y and the second region E are opposite. In the embodiment of the present application, the first region Y is a P region and the second region E is an N region for illustration.

[0066] The first passivation contact structure 20 and the second passivation contact structure 30 are respectively arranged in the first region Y and the second region E. An isolation groove 40 extending to the isolation region G and playing an insulating isolation role is arranged between adjacent first passivation contact structures 20 and the second passivation contact structures 30. The first passivation contact structure 20 includes a first tunneling oxide layer 21 and a first doped polysilicon layer 22 sequentially stacked in the first region Y, and the second passivation contact structure 30 includes a second tunneling oxide layer 31 and a second doped polysilicon layer 32 sequentially stacked in the second region E. The first doped polysilicon layer 22 can be doped with a P-type element, for example, and the second doped polysilicon layer 32 can be doped with an N-type element, that is, the doping element types of the first doped polysilicon layer 22 and the second doped polysilicon layer 32 are opposite. It should be noted that in the back-contact solar cell 100, the first passivation contact structure 20 and the second passivation contact structure 30 can be alternately arranged along a preset direction. Figure 1 In the figure, only two first passivation contact structures 20 and one second passivation contact structure 30 are illustrated, and the structural arrangements of the remaining first passivation contact structures 20 and the second passivation contact structures 30 are similar to this, and are not described in detail here.

[0067] Continue to refer to Figure 1 In the back contact solar cell 100, the first passivation layer 61 is arranged on the side of the first surface F, covering the surface of the first passivation contact structure 20, the isolation groove 40, and the second passivation contact structure 30 away from the substrate 10. The second passivation layer 62 covers the second surface S. The side passivation layer 63 covers the side C, and part of the side passivation layer 63 covers the section Q, which can effectively protect the cut section Q, increase the passivation effect of the section Q, alleviate the recombination generated on the section Q, and effectively reduce the cutting loss. In addition, the side passivation layer 63 is an insulating film layer, which can better avoid the occurrence of leakage on the back contact solar cell 100 corresponding to the section Q and the side C, thereby increasing the power output of the back contact solar cell 100 while improving the battery conversion efficiency.

[0068] In addition, the first passivation layer 61 , the second passivation layer 62 , and the side passivation layer 63 are all stacked layers of the anti-reflection film layer 610 and the passivation film layer 620 , and the passivation film layer 620 is closer to the substrate 10 than the anti-reflection film layer 610 .

[0069] Further, the first electrode 91 is provided on the first passivation layer 61 at a position corresponding to the first passivation contact structure 20, and is electrically connected to the first doped polysilicon layer 22, and the second electrode 92 is provided on the first passivation layer 61 at a position corresponding to the second passivation contact structure 30, and is electrically connected to the second doped polysilicon layer 32. In addition, in the embodiment of the present application, a velvet structure 41 is further provided on the second surface to improve the battery efficiency.

[0070] Figure 2A schematic flow chart of a method for manufacturing a back-contact solar cell provided in an embodiment of the present application.

[0071] The method for manufacturing a back-contact solar cell of this embodiment is used to manufacture the above-mentioned back-contact solar cell 100 .

[0072] Reference Figure 2-Figure 7 The method for manufacturing a back-contact solar cell according to an embodiment of the present application includes:

[0073] S10. Provide a substrate, the substrate comprising a substrate, a first tunneling material layer stacked on each surface of the substrate, a first doped polysilicon material layer and a first mask material layer, wherein the substrate comprises a first surface and a second surface arranged opposite to each other and a side surface adjacent to the first surface and the second surface, and the first surface comprises a first region, a second region and an isolation region isolated between the first region and the second region.

[0074] S20, removing the portion of the first mask material layer corresponding to the second region and the isolation region, and cutting the substrate into at least two sub-substrates along the thickness direction.

[0075] S30, using a first acid cleaning solution to remove the portion of the first mask material layer in the sub-substrate corresponding to the side surface and the second surface, and using the first acid cleaning solution to clean the cut section.

[0076] S40, using a second alkaline cleaning solution to remove portions of the first tunneling material layer and the first doped polysilicon material layer in the sub-substrate corresponding to the second surface, the side surface, the second region and the isolation region, and using the second alkaline cleaning solution to clean the cross section to form a first passivation contact structure covering the first region.

[0077] By cutting the substrate 101 before the step of removing the portion of the first mask material layer 73 corresponding to the side surface C and the second surface S in the sub-substrate 102 using the first acidic cleaning liquid, and also using the first acidic cleaning liquid and the second alkaline cleaning liquid to clean the cut section Q, the cutting damage on the section Q can be removed as much as possible, and the influence of the cutting damage on the photoelectric conversion efficiency of the cell after cutting can be avoided. In addition, since the first acidic cleaning liquid and the second alkaline cleaning liquid used to clean the section Q are used to remove the first mask material layer 73, the first tunneling material layer 71 and the first doped polysilicon material layer 72 in the manufacturing process, the cleaning of the section Q can be carried out using the first acidic cleaning liquid and the second alkaline cleaning liquid that already exist in the process, without the need for additional cleaning liquids and cleaning processes, thereby saving the number of processes and reducing costs.

[0078] It can be understood that in the step S20 of removing the portion of the first mask material layer 73 corresponding to the second region E and the isolation region G and cutting the substrate 101 into at least two sub-substrates 102 along the thickness direction, the following steps can be performed: Figure 4 , 5 As shown, after the portion of the first mask material layer 73 corresponding to the second area E and the isolation area G is removed, the substrate 101 is cut into at least two sub-substrates 102 along the thickness direction. Alternatively, the substrate 101 may be cut into at least two sub-substrates 102 along the thickness direction, and then the portion of the first mask material layer 73 corresponding to the second area E and the isolation area G is removed for each sub-substrate 102. In the following examples of the present application, the substrate 101 is cut into at least two sub-substrates 102 along the thickness direction after the portion of the first mask material layer 73 corresponding to the second area E and the isolation area G is removed as an example. The process of another case is similar to this and will not be repeated here. Of course, the location for cutting is the isolation area G to avoid affecting the battery performance.

[0079] In addition, the first mask material layer 73 may be formed simultaneously during the process of forming the first doped polysilicon material layer 72 . For example, when the doping element of the first doped polysilicon material layer 72 is boron, the first doped polysilicon material layer 72 may be BSG.

[0080] Reference Figure 4 , Figure 5 , the portion of the first mask material layer 73 corresponding to the second region E and the isolation region G is removed, for example, by a green picosecond laser. The substrate 101 is cut into at least two sub-substrates 102 along the thickness direction, for example, by laser, and the cutting process may include the steps of scribing and splitting. Of course, the cutting here is explained by cutting in half as an example, and the substrate 101 may also be cut into three or more sub-substrates 102 as needed. The case where the number of slices is other is similar to cutting in half, and will not be repeated here.

[0081] Here, the first acidic cleaning liquid may be, for example, an HF acid solution, and the second alkaline cleaning liquid may be, for example, a KOH solution.

[0082] In the embodiment of the present application, in the cutting process, refer to Figure 5 , a damaged structure 50 is formed on the cross section Q of the sub-substrate 102 , and the damaged structure 50 includes a main body 51 and an oxide layer 52 covering the main body 51 .

[0083] In step S30, the step of using the first acid cleaning solution to clean the cut section Q specifically includes: using the first acid cleaning solution to clean and remove the oxide layer.

[0084] With such arrangement, there is no need to add a new process to remove the oxide layer, and it can be completed by using the first cleaning liquid, which not only saves the number of processes but also reduces costs.

[0085] Further, refer to Figure 6 , Figure 7 In step S20, the step of cleaning the cross section Q with the second alkaline cleaning solution specifically includes: using the second alkaline cleaning solution to at least partially remove the main body 51 in the damaged structure 50. Of course, the second alkaline cleaning solution can completely remove the main body 51.

[0086] Since the first passivation contact structure 20 is formed by cleaning and etching with the second alkaline cleaning solution in this step, there is no need to add an additional process to clean the main body of the damaged structure. It only needs to be performed simultaneously with the cleaning and etching of the first tunneling material layer 71 and the first doped polysilicon material layer 72, which saves the number of processes and reduces costs.

[0087] In the embodiment of the present application, the thickness of the first mask material layer 73 is 70 nm-80 nm.

[0088] Since the second alkaline cleaning solution needs to clean the section Q, the required cleaning time is slightly longer than that of simply cleaning and etching the first tunneling material layer 71 and the first doped polysilicon material layer 72. If the thickness of the first mask material layer 73 is set to 70nm-80nm, that is, it is set thicker, the second alkaline cleaning solution can clean the section Q thoroughly while not etching the first doped polysilicon material layer 72 in the first region Y.

[0089] In the embodiment of the present application, the second alkaline cleaning solution is an alkaline solution with a mass concentration of 8%-12%, and the cleaning time of the second alkaline cleaning solution is 200s-380s. In specific implementation, the mass concentration can be preferably 10% or 10.5%. The cleaning time can be preferably 200s, 250s, or 300s. The alkaline solution can be a KOH solution.

[0090] In the embodiment of the present application, in step S20 , in the step of cutting the substrate 101 into at least two sub-substrates 102 along the thickness direction, the cutting is performed from the second surface S side.

[0091] Reference Figure 4 , Figure 5The cutting damage generated during the cutting process mostly occurs at the initial position of the cutting. Since the second surface S is covered with the first tunneling material layer 71, the first doped polysilicon material layer 72 and the first mask material layer 73, these film layers have a certain thickness and will be cleaned and removed by the second alkaline cleaning solution and the first acidic cleaning solution in the end. If the cutting is done on one side of the second surface S, part of the damage will be located in the first tunneling material layer 71, the first doped polysilicon material layer 72 and the first mask material layer 73 to be removed. Therefore, in the sub-substrate 102, the damaged part located on the substrate 10 will be reduced, which is more conducive to improving the overall performance of the battery.

[0092] In the present application, refer to Fig. 9 , after the step of forming the first passivation contact structure 20 in step S40, the following steps are further included:

[0093] A second tunneling material layer 81 and a second doped polysilicon material layer 82 are sequentially stacked on each surface of the sub-substrate 102 , and a second mask 84 is formed at a position corresponding to the second region E on the second doped polysilicon material layer 82 .

[0094] Reference Fig.10 , using the second mask 84, the second tunneling material layer 81 and the second doped polysilicon material layer 82 in the sub-substrate 102 corresponding to the second surface S, the side surface C, the section Q, the first region Y and the isolation region G are removed, and the section Q is cleaned again to form a second passivation contact structure 30 covering the second region E. In this step, the section Q is cleaned again to minimize the cutting damage on the section Q.

[0095] When implementing it, refer to Figure 8 , Fig. 9 The step of forming a second mask at a position corresponding to the second region E on the second doped polysilicon material layer 82 specifically includes:

[0096] A second mask material layer 83 is formed on the surface of the second doped polysilicon material layer 82 facing away from the substrate 10. At this time, the second mask material layer 83 can be formed together with the formation process of the second doped polysilicon material layer 82. For example, when the second doped polysilicon material layer 82 is doped with phosphorus, the second mask material layer 83 can be PSG.

[0097] The laser opening is used to remove the portion of the second mask material layer 83 corresponding to the first region Y and the isolation region G, and the third acid cleaning solution is used to remove the portion of the second mask material layer 83 corresponding to the second surface S and the side surface C. The third acid cleaning solution may be, for example, HF acid solution.

[0098] Furthermore, combined with Fig. 9 , Fig.10The steps of using the second mask 84 to remove the second tunneling material layer 81 and the second doped polysilicon material layer 82 in the sub-substrate 102 corresponding to the second surface S, the side surface C, the cross section Q, the first region Y and the isolation region G, and cleaning the cross section Q again specifically include:

[0099] The second tunneling material layer 81 and the second doped polysilicon material layer 82 in the sub-substrate 102 corresponding to the second surface S, the side surface C, the cross section Q, the first region Y and the isolation region G are removed by using the fourth alkaline cleaning solution, and the cross section Q is cleaned again by using the fourth alkaline cleaning solution, and the second tunneling material layer 81 and the second doped polysilicon material layer 82 in the second region E are retained. The fourth alkaline cleaning solution may be the same as the second alkaline cleaning solution, for example.

[0100] Similarly, the cleaning of the section Q utilizes the fourth alkaline cleaning solution that is originally used to etch the second tunneling material layer 81 and the second doped polysilicon material layer 82 , thereby avoiding the introduction of additional cleaning solutions and cleaning processes, and reducing costs.

[0101] In the embodiment of the present application, the thickness of the second mask 84 is 70nm-80nm.

[0102] Since the fourth alkaline cleaning solution needs to clean the section Q again, the required cleaning time is slightly longer than that of simply cleaning and etching the second tunneling material layer 81 and the second doped polysilicon material layer 82. If the thickness of the second mask 84 is set to 70nm-80nm, that is, it is set thicker, the fourth alkaline cleaning solution can clean the section Q thoroughly while not etching the second doped polysilicon material layer 82 in the second region E.

[0103] Of course, after cleaning with the fourth alkaline cleaning solution, the second surface S may be textured with the fifth cleaning solution to form a texture structure 41 on the second surface S. More photons may be absorbed. The fifth cleaning solution may be, for example, a 2% KOH solution, in which a texture additive is also added.

[0104] In the embodiment of the present application, after the step of forming the second passivation contact structure 30, the following steps are further included:

[0105] The second mask 84 and the first mask material layer 73 covering the surface of the first passivation contact structure 20 are removed.

[0106] Combination Figure 1 and Fig.10 In the sub-substrate 102, a first passivation layer 61 and a second passivation layer 62 are formed on the first surface F side and the second surface S side respectively, and a side passivation layer 63 is also formed on the side surface C and the cross section Q.

[0107] In this way, the section Q is also covered with the side passivation layer 63, which can effectively protect the cut section Q, increase the passivation effect of the section Q, alleviate the recombination generated on the section Q, and effectively avoid reducing the cutting loss. In addition, the side passivation layer 63 is an insulating film layer, which can better avoid the leakage of the back contact solar cell 100 corresponding to the section Q and the side C, thereby increasing the power output of the back contact solar cell 100 while improving the battery conversion efficiency.

[0108] In the embodiment of the present application, the side passivation layer 63 and the first passivation layer 61 are formed in the same process, or the side passivation layer 63 and the second passivation layer 62 are formed in the same process.

[0109] With such an arrangement, no additional passivation process is introduced during the passivation of the side surface C and the cross section Q, thereby reducing the cost of the passivation of the side surface C and the cross section Q.

[0110] As mentioned above, the first passivation layer 61 , the second passivation layer 62 , and the side passivation layer 63 are all stacked layers of the anti-reflection film layer 610 and the passivation film layer 620 . In the specific formation process, the passivation film layer 620 can be formed first, and then the anti-reflection film layer 610 is deposited on the passivation film layer 620 .

[0111] Of course, after the side passivation layer 63, the first passivation layer 61, and the second passivation layer 62 are formed, the steps of forming the first electrode 91 and the second electrode 92 are also included. Specifically, the first electrode 91 is formed on the first passivation layer 61 at a position corresponding to the first passivation contact structure 20, and the second electrode 92 is formed on a position corresponding to the second passivation contact structure 30. The first electrode 91 passes through the first passivation layer 61 to be electrically connected to the first doped polysilicon layer 22 in the first passivation contact structure 20, and the second electrode 92 passes through the first passivation layer 61 to be electrically connected to the second doped polysilicon layer 32 in the second passivation contact structure 30.

[0112] The following is a specific example to illustrate the method for manufacturing the back-contact solar cell of the present application.

[0113] Embodiment 1

[0114] (1) An N-type silicon substrate 10 is selected, double-sided polished in a 10% KOH solution to remove the damaged layer, and then cleaned using RCA1 and RCA2 solutions.

[0115] The composition of RCA1 (SC-1) is: NH4OH:H2O2:H2O=1:1:5.

[0116] The composition of RCA2 (SC-2) is: HCL: H2O2: H2O=1:1:5.

[0117] (2) Reference Figure 3, silicon oxide and intrinsic polysilicon are deposited on various surfaces of the substrate 10 by LPCVD, wherein silicon oxide is used as the first tunneling material layer 71, the thickness of silicon oxide is 1.2-2nm, and the thickness of intrinsic polysilicon is between 200-300 nm, and then boron diffusion is performed in a diffusion furnace to form a first boron-doped polysilicon material layer 72 of the intrinsic polysilicon, and 70-80 nm of borosilicate glass is formed on the surface of the first doped polysilicon material layer 72 as the first mask material layer 73.

[0118] (3) Reference Figure 4 , a green picosecond laser is used to selectively open the film on one side of the first surface F, and the opened film area is the second area E and the isolation area G. That is, the portion of the first mask material layer 73 corresponding to the second area E and the isolation area G is removed.

[0119] (4) Reference Figure 5 The substrate 101 is sliced ​​using a non-destructive laser device, and a cut is made on one side of the second surface S to form a section Q. A 3-5 mm laser burnt area is formed at the initial position of the cut, and a damaged structure 50 is formed on the laser burnt area. The remaining area not covered by the damaged structure 50 is smooth bare silicon that has not been passivated. Figure 6 , the first mask material layer 73 on the second surface S and the side surface C is removed by chain HF cleaning, and the oxide layer 52 on the section Q is cleaned and removed. Figure 7 , use the second alkaline cleaning solution to clean, remove the first tunneling material layer 71 and the first doped polysilicon material layer 72 in the sub-substrate 102 corresponding to the second surface S, the side surface C, the second region E and the isolation region G, and use the second alkaline cleaning solution to clean the cross section Q, clean and remove the main body 51 of the damaged structure, so as to form a first passivation contact structure 20 covering the first region Y. The mass concentration of the second alkaline cleaning solution is 10%, and the cleaning time is 300s.

[0120] (5) Through LPCVD Figure 7 The surface of the sub-substrate 102 shown in the figure is subjected to silicon oxide / intrinsic polysilicon deposition, and silicon oxide is used as the second tunneling material layer 81. The thickness of silicon oxide is 1.2-2nm, and the thickness of intrinsic polysilicon is between 200-300nm. Then phosphorus diffusion is performed in a diffusion furnace to form a second doped polysilicon material layer 82 and 70-80 nm phosphorus silicon glass as a second mask material layer 83 on the surface of the second tunneling material layer 81. Thus, the following is formed: Figure 8 The structure shown.

[0121] (6) Reference Fig. 9A green picosecond laser is used to selectively open the film on one side of the first surface F to remove the portion of the second mask material layer 83 corresponding to the first area Y and the isolation area G, and then chain HF is used as the third acidic cleaning liquid to remove the portion of the second mask material layer 83 corresponding to the second surface S, the side surface C, and the cross-section Q, thereby forming a second mask 84.

[0122] (7) Reference Fig.10 , using the fourth alkaline cleaning solution for cleaning, using the fourth alkaline cleaning solution to remove the second tunneling material layer 81 and the second doped polysilicon material layer 82 in the sub-substrate 102 corresponding to the second surface S, the side surface C, the section Q, the first region Y and the isolation region G, and using the fourth alkaline cleaning solution to clean the section Q again, and retain the second tunneling material layer 81 and the second doped polysilicon material layer 82 in the second region E. The fourth alkaline cleaning solution can be the same as the second alkaline cleaning solution, for example. In order to allow more photons to be absorbed by crystalline silicon, 2% KOH and a texturing additive are used as the fifth cleaning solution to texturize the second surface S to form a velvet structure 41, and a velvet structure is also formed in the isolation region G.

[0123] (9) Using HF acid solution to remove the second mask 84 and the first mask material layer 73 covering the surface of the first passivation contact structure 20. Figure 1 and Fig.10 In the sub-substrate 102, a first passivation layer 61 and a second passivation layer 62 are formed on the first surface F and the second surface S, respectively, and a side passivation layer 63 is also formed on the side surface C and the cross section Q. A first electrode 91 is formed on the first passivation layer 61 at a position corresponding to the first passivation contact structure 20, and a second electrode 92 is formed on a position corresponding to the second passivation contact structure 30. The first electrode 91 passes through the first passivation layer 61 to be electrically connected to the first doped polysilicon layer 22 in the first passivation contact structure 20, and the second electrode 92 passes through the first passivation layer 61 to be electrically connected to the second doped polysilicon layer 32 in the second passivation contact structure 30.

[0124] Embodiment 2

[0125] (1) An N-type silicon substrate 10 is selected, double-sided polished in a 10% KOH solution to remove the damaged layer, and then cleaned using RCA1 and RCA2 solutions.

[0126] The composition of RCA1 (SC-1) is: NH4OH:H2O2:H2O=1:1:5.

[0127] The composition of RCA2 (SC-2) is: HCL: H2O2: H2O=1:1:5.

[0128] (2) Reference Figure 3, silicon oxide and intrinsic polysilicon are deposited on various surfaces of the substrate 10 by LPCVD, wherein silicon oxide is used as the first tunneling material layer 71, the thickness of silicon oxide is 1.2-2nm, and the thickness of intrinsic polysilicon is between 200-300 nm, and then boron diffusion is performed in a diffusion furnace to form a first boron-doped polysilicon material layer 72 of the intrinsic polysilicon, and 70-80 nm of borosilicate glass is formed on the surface of the first doped polysilicon material layer 72 as the first mask material layer 73.

[0129] (3) Reference Figure 4 , a green picosecond laser is used to selectively open the film on one side of the first surface F, and the opened film area is the second area E and the isolation area G. That is, the portion of the first mask material layer 73 corresponding to the second area E and the isolation area G is removed.

[0130] (4) Reference Fig.11 , the first mask material layer 71 located on the second surface S and the side surface C is removed by cleaning with an acidic cleaning solution, such as a chain HF solution. And the first tunneling material layer 71 and the first doped polysilicon material layer 72 located on the second surface S, the side surface C, the second region E and the isolation region G are cleaned and removed by using a strong alkaline solution. Finally, the first tunneling material layer 71 and the first doped polysilicon material layer 72 in the first region Y are retained, thereby forming a first passivation contact structure 20.

[0131] (5) Silicon oxide / intrinsic polysilicon is deposited on each surface of the substrate 101 by LPCVD, with silicon oxide serving as the second tunneling material layer 81, wherein the thickness of silicon oxide is 1.2-2 nm, and the thickness of intrinsic polysilicon is between 200-300 nm. Then phosphorus diffusion is performed in a diffusion furnace to form a second doped polysilicon material layer 82 and 70-80 nm phosphorus silicon glass as the second mask material layer 83 on the surface of the second tunneling material layer 81. Thus, the following is formed: Fig.12 The structure shown.

[0132] (6) Reference Fig.13 , a green picosecond laser is used to selectively open the second mask material layer 83 to remove the portion of the second mask material layer 83 corresponding to the first region Y and the isolation region G.

[0133] Reference Fig.14 , the substrate 101 is cut using a non-destructive laser device to form a sub-substrate 102. A damaged structure 50 is formed on the laser burnt area at the initial cutting position of the section Q, and the remaining area not covered by the damaged structure 50 is smooth and unpassivated bare silicon. Fig.15 The second mask material layer 83 on the second surface S and the side surface C is removed by chain HF cleaning to form a second mask 84, and the oxide layer 52 on the section Q is cleaned and removed.

[0134] (7) Recombination Fig.10 , use an alkaline cleaning solution to clean, remove the second tunneling material layer 81 and the second doped polysilicon material layer 82 in the sub-substrate 102 corresponding to the second surface S, the side surface C, the first region Y and the isolation region G, and use the alkaline cleaning solution to clean the cross section Q, clean and remove the main body 51 of the damaged structure, so as to form a first passivation contact structure 20 covering the first region Y. The mass concentration of the alkaline cleaning solution is 10%, and the cleaning time is 200s. In addition, a velvet structure 41 can be formed on the second surface S and the isolation region G.

[0135] (8) Using HF acid solution to remove the second mask 84 and the first mask material layer 73 covering the surface of the first passivation contact structure 20. Figure 1 and Fig.10 In the sub-substrate 102, a first passivation layer 61 and a second passivation layer 62 are formed on the first surface F and the second surface S, respectively, and a side passivation layer 63 is also formed on the side surface C and the cross section Q. A first electrode 91 is formed on the first passivation layer 61 at a position corresponding to the first passivation contact structure 20, and a second electrode 92 is formed on a position corresponding to the second passivation contact structure 30. The first electrode 91 passes through the first passivation layer 61 to be electrically connected to the first doped polysilicon layer 22 in the first passivation contact structure 20, and the second electrode 92 passes through the first passivation layer 61 to be electrically connected to the second doped polysilicon layer 32 in the second passivation contact structure 30.

[0136] Embodiment 3

[0137] In this embodiment, based on the second embodiment, the cleaning time of the alkaline cleaning solution in step (7) is replaced with 300 seconds.

[0138] Comparative Example 1

[0139] (1) Select an N-type Si substrate, double-sided polish it in a 10% KOH solution to remove the damaged layer, and then clean it with RCA1 and RCA2 solutions.

[0140] (2) Silicon oxide / intrinsic polysilicon is deposited on each surface of the substrate by LPCVD, where the thickness of the silicon oxide is 1.2-2 nm and the thickness of the intrinsic polysilicon is between 200-300 nm. Boron diffusion is then carried out in a diffusion furnace to form boron-doped polysilicon on the silicon oxide, and 40-50 nm of borosilicate glass is formed on the surface of the boron-doped polysilicon.

[0141] (3) Use a green picosecond laser to selectively open the film on the back of the substrate. The opening area is the N region and isolation region of the substrate. That is, the position of the borosilicate glass corresponding to the N region and isolation region is removed.

[0142] (4) Clean the borosilicate glass on the front and sides of the substrate with chain HF, and keep the position on the borosilicate glass corresponding to the P region. Polish in a strong alkaline solution to remove the silicon oxide and boron-doped polysilicon on the front and sides, N region and isolation region. Only the silicon oxide and boron-doped polysilicon covering the P region are retained to form a passivation contact structure of the P region.

[0143] (5) Silicon oxide / intrinsic polysilicon is deposited on each surface of the structure formed in step (4) by LPCVD, wherein the thickness of the silicon oxide is 1.2-2 nm and the thickness of the intrinsic polysilicon is between 200-300 nm, followed by phosphorus diffusion in a diffusion furnace to form phosphorus-doped polysilicon (n-type) from intrinsic polysilicon, and 40-50 nm of phosphorus-silicate glass is formed on the surface of the phosphorus-doped polysilicon.

[0144] (6) Use a green picosecond laser to selectively open the film on the back side. The opening area is the p-zone and the isolation zone. That is, the positions corresponding to the p-zone and the isolation zone on the phosphosilicate glass are removed. Then, the phosphosilicate glass on the front and side is cleaned by chain HF. Finally, the positions corresponding to the N-zone on the phosphosilicate glass are retained.

[0145] (7) Using the phosphosilicate glass in the above-mentioned reserved area as a mask, polish and remove the silicon oxide and phosphorus-doped polysilicon on the front, side, P region, and isolation region in a strong alkaline solution, while retaining the silicon oxide and phosphorus-doped polysilicon on the N region.

[0146] (8) In order to allow more photons to be absorbed by crystalline silicon, the front side is textured using 2% KOH and a texturing additive.

[0147] (9) HF cleaning removes the borosilicate glass and phosphosilicate glass on the back of the battery, and then aluminum oxide and silicon nitride are deposited. The aluminum oxide and silicon nitride are deposited on the front and back sides.

[0148] (10) Finally, metal grid lines are screen-printed, sintered at high temperature, and then light is injected to form a back-contact battery.

[0149] (11) The back contact battery is cut in half using a non-destructive laser to form a half-chip back contact battery.

[0150] Comparative Example 2

[0151] Based on the comparative example 1, this embodiment further adds a step of forming a stack of aluminum oxide and silicon nitride on the cut surface after step (11).

[0152] The back contact cells formed in the above-mentioned Example 1, Example 2, Example 3, Comparative Example 1 and Comparative Example 2 were tested for photoelectric performance under the condition of AM1.5, and the test results are recorded in Table 1. Among them,

[0153] PCE is the power conversion efficiency, JSC is the short-circuit current density, FF is the fill factor, and Voc is the open-circuit voltage.

[0154]

[0155] It can be seen from Table 1 that the back-contact solar cells manufactured by using the embodiment 1, embodiment 2, and embodiment 3 of the present application have a power conversion efficiency, a short-circuit current density, a fill factor, and an open-circuit voltage that are greater than the back-contact solar cells manufactured by the comparative example 1 and comparative example 2. Therefore, the back-contact solar cells manufactured by the manufacturing method of the back-contact solar cells of the embodiments of the present application have a higher efficiency.

[0156] The embodiments of the present application also provide a photovoltaic module and a photovoltaic system. The photovoltaic module includes at least one cell string, and the cell string includes at least two back-contact solar cells 100 as described above, and the back-contact solar cells 100 can be connected together by series welding.

[0157] The photovoltaic system includes the above-mentioned photovoltaic components. The photovoltaic system can be used in photovoltaic power stations, such as ground power stations, rooftop power stations, water power stations, etc. It can also be used in equipment or devices that use solar energy to generate electricity, such as user solar power supplies, solar street lights, solar cars, solar buildings, etc. Of course, it can be understood that the application scenarios of the photovoltaic system are not limited to this, that is to say, the photovoltaic system can be used in all fields that require solar energy to generate electricity. Taking the photovoltaic power generation system network as an example, the photovoltaic system may include a photovoltaic array, a junction box and an inverter. The photovoltaic array can be an array combination of multiple photovoltaic components. For example, multiple photovoltaic components can form multiple photovoltaic arrays. The photovoltaic array is connected to the junction box. The junction box can converge the current generated by the photovoltaic array. The converged current flows through the inverter and is converted into the alternating current required by the mains power grid. After that, it is connected to the mains network to realize solar power supply.

[0158] 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.

[0159] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for manufacturing a back contact solar cell, characterized in that: include: A substrate is provided, the substrate comprising a substrate, a first tunneling material layer, a first doped polysilicon material layer and a first mask material layer stacked on each surface of the substrate, wherein the substrate comprises a first surface and a second surface arranged opposite to each other and a side surface adjacent to the first surface and the second surface, the first surface comprises a first region, a second region and an isolation region isolated between the first region and the second region; removing the portion of the first mask material layer corresponding to the second region and the isolation region, and cutting the substrate into at least two sub-substrates along the thickness direction; Using a first acid cleaning solution to remove the portion of the first mask material layer in the sub-substrate corresponding to the side surface and the second surface, and cleaning the cut section; A second alkaline cleaning solution is used to remove portions of the first tunneling material layer and the first doped polysilicon material layer in the sub-substrate corresponding to the second surface, the side surface, the second region and the isolation region, and the cross section is cleaned to form a first passivation contact structure covering the first region.

2. The method for manufacturing a back contact solar cell according to claim 1, characterized in that: In the cutting process, a damaged structure is formed on the cross section of the sub-substrate, wherein the damaged structure includes a main body and an oxide layer covering the main body; The step of cleaning the cut section with the first acid cleaning solution specifically includes: cleaning and removing the oxide layer with the first acid cleaning solution.

3. The method for manufacturing a back contact solar cell according to claim 2, characterized in that: The step of cleaning the cross section with a second alkaline cleaning solution specifically includes: The main body in the damaged structure is at least partially removed by using the second alkaline cleaning solution.

4. The method for manufacturing a back contact solar cell according to claim 1, characterized in that: The thickness of the first mask material layer is 70nm-80nm.

5. The method for manufacturing a back contact solar cell according to claim 1, characterized in that: The second alkaline cleaning solution is an alkaline solution with a mass concentration of 8%-12%, and the cleaning time of the second alkaline cleaning solution is 200s-380s.

6. The method for manufacturing a back contact solar cell according to claim 1, characterized in that: In the step of cutting the substrate into at least two sub-substrates along the thickness direction, cutting is performed from one side of the second surface.

7. The method for manufacturing a back contact solar cell according to claim 1, characterized in that: After the step of forming the first passivation contact structure, the following steps are further included: Forming a second tunneling material layer and a second doped polysilicon material layer in sequence on each surface of the sub-substrate, and forming a second mask at a position corresponding to the second region on the second doped polysilicon material layer; Using the second mask, the second tunneling material layer and the second doped polysilicon material layer in the sub-substrate corresponding to the second surface, the side surface, the cross-section, the first region and the isolation region are removed, and the cross-section is cleaned again to form a second passivation contact structure covering the second region.

8. The method for manufacturing a back contact solar cell according to claim 7, characterized in that: The step of forming a second mask on the second doped polysilicon material layer at a position corresponding to the second region specifically includes: forming a second mask material layer on a surface of the second doped polysilicon material layer facing away from the substrate; The portion of the second mask material layer corresponding to the first area and the isolation area is removed by laser film opening, and the portion of the second mask material layer corresponding to the second surface and the side surface is removed by a third acid cleaning solution.

9. The method for manufacturing a back contact solar cell according to claim 7, characterized in that: The step of using the second mask to remove the second tunneling material layer and the second doped polysilicon material layer in the sub-substrate corresponding to the second surface, the side surface, the cross section, the first region and the isolation region, and cleaning the cross section again specifically includes: The second tunneling material layer and the second doped polysilicon material layer in the sub-substrate corresponding to the second surface, the side surface, the cross section, the first region and the isolation region are removed using a fourth alkaline cleaning solution, and the cross section is cleaned again using the fourth alkaline cleaning solution.

10. The method for manufacturing a back contact solar cell according to claim 9, characterized in that: The thickness of the second mask is 70nm-80nm.

11. The method for manufacturing a back contact solar cell according to claim 7, characterized in that: After the step of forming the second passivation contact structure, the step further includes: removing the second mask and the first mask material layer covering the surface of the first passivation contact structure; In the sub-substrate, a first passivation layer and a second passivation layer are formed on the first surface side and the second surface side respectively, and a side passivation layer is also formed on the side surface and the cross section.

12. The method for manufacturing a back contact solar cell according to claim 11, characterized in that: The side passivation layer and the first passivation layer are formed in the same process; or The side passivation layer and the second passivation layer are formed in the same process.

13. A back contact solar cell, characterized in that: The back-contact solar cell is manufactured using the method for manufacturing a back-contact solar cell as described in any one of claims 1 to 12.

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