Back contact cell, preparation method of back contact cell and photovoltaic module

Abstract

The invention relates to a back contact cell, a preparation method of the back contact cell and a photovoltaic module. The substrate has a first surface including first regions and second regions arranged alternately. The tunneling layer is arranged in the first region, and the first doped semiconductor layer is arranged on the side, away from the substrate, of the tunneling layer. The doped field region is located in the first region, and the doped field region and the first doped semiconductor layer are both provided with first doped elements. The second region is provided with a groove which is recessed relative to the first region, one part of the amorphous layer is arranged on the second region, and the other part of the amorphous layer is arranged on the side, away from the substrate, of the first doped semiconductor layer. The second doped semiconductor layer is arranged on one side, far away from the substrate, of the amorphous layer and is provided with a second doped element which is different from the first doped element in doping type. The depth of the doped field region is smaller than that of the groove. Therefore, the passivation performance of the first region can be improved, the passivation performance of the second region can also be considered, and the passivation performance of the back contact battery can be improved on the whole.

Description

Technical Field

[0001] This application relates to the field of solar cell technology, and in particular to back contact cells, methods for preparing back contact cells, and photovoltaic modules. Background Technology

[0002] Back contact batteries (BC batteries) are a type of solar cell technology that integrates all positive and negative metal contacts on the back side.

[0003] In related technologies, improving the passivation performance of back contact batteries has become one of the future development directions. Summary of the Invention

[0004] Therefore, it is necessary to provide a back contact battery, a method for preparing a back contact battery, and a photovoltaic module to improve the passivation performance of the back contact battery.

[0005] According to a first aspect of this application, a back-contact battery is provided, comprising a substrate, a tunneling layer, a first doped semiconductor layer, a doped field region, an amorphous layer, and a second doped semiconductor layer. The substrate has a first surface and a second surface disposed opposite to each other along a first direction; the first surface includes alternating first and second regions. The tunneling layer is disposed in the first region, and the first doped semiconductor layer is disposed on the side of the tunneling layer away from the substrate. The doped field region is located in the first region, and both the doped field region and the first doped semiconductor layer have a first doping element. The second region has a groove recessed relative to the first region, a portion of the amorphous layer is disposed in the second region, and another portion of the amorphous layer is disposed on the side of the first doped semiconductor layer away from the substrate. The second doped semiconductor layer is disposed on the side of the amorphous layer away from the substrate and has a second doping element of a different doping type than the first doping element. The depth of the doped field region is less than the depth of the groove.

[0006] In one embodiment, the sum of the thickness of the tunneling layer, the thickness of the first doped semiconductor layer, and the depth of the doped field region is less than the depth of the trench.

[0007] In one embodiment, the ratio of the depth of the groove to the depth of the doped field region is 5-100.

[0008] In one embodiment, the depth of the doped field region is 100nm-1000nm.

[0009] In one embodiment, the depth of the groove is 1μm-10μm.

[0010] In one embodiment, the doping concentration of the first dopant element in the first doped semiconductor layer is greater than the doping concentration of the first dopant element in the doped field region.

[0011] In one embodiment, the doped field region includes a first doped sub-region and a second doped sub-region; along a first direction, the first doped sub-region is disposed closer to the first surface than the second doped sub-region; the doping concentration of the first doped element in the first doped sub-region is greater than the doping concentration of the first doped element in the second doped sub-region.

[0012] In one embodiment, the doped field region further includes a third doped sub-region located between the first doped sub-region and the second doped sub-region along a first direction; the doping concentration of the first doped element in the first doped sub-region is greater than the doping concentration of the first doped element in the third doped sub-region, and the doping concentration of the first doped element in the third doped sub-region is greater than the doping concentration of the first doped element in the second doped sub-region.

[0013] In one embodiment, the doping concentration of the first dopant element in the tunneling layer is greater than the doping concentration of the first dopant element in the doped field region; and / or, the doping concentration of the first dopant element in the tunneling layer is greater than the doping concentration of the first dopant element in the first doped semiconductor layer.

[0014] In one embodiment, the ratio of the doping concentration of the first dopant element in the doped field region to the doping concentration of the second dopant element in the second doped semiconductor layer is 0.1-10.

[0015] In one embodiment, the first doped semiconductor layer and the second doped semiconductor layer have different crystal phases.

[0016] In one embodiment, the first doped semiconductor layer includes a middle portion and edge portions located on both sides of the middle portion; a portion of the amorphous layer is disposed on the side of the edge portions away from the substrate; the doping concentration of the first dopant element in the middle portion is greater than the doping concentration of the first dopant element in the edge portions.

[0017] In one embodiment, the back contact battery further includes a first transparent conductive layer and a second transparent conductive layer, wherein the first transparent conductive layer is disposed on the side of the first doped semiconductor layer away from the substrate and is electrically connected to the first doped semiconductor layer; and / or, the second transparent conductive layer is disposed on the side of the second doped semiconductor layer away from the substrate and is electrically connected to the second doped semiconductor layer.

[0018] In one embodiment, the back contact battery further includes a first electrode, which is disposed on the side of the first transparent conductive layer away from the first doped semiconductor layer, and the first electrode does not contact the doped field region.

[0019] In one embodiment, the second region has a first pyramidal structure and the second face has a second pyramidal structure; the size of the first pyramidal structure is smaller than the size of the second pyramidal structure.

[0020] In one embodiment, the back contact battery further includes a first passivation layer and a first antireflection layer disposed on the second side.

[0021] According to a second aspect of this application, a method for fabricating a back-contact battery is provided, comprising: providing a substrate; wherein the substrate has a first surface and a second surface disposed opposite to each other along a first direction, the first surface including alternating first regions and second regions; forming an initial tunneling layer on the first surface; forming a first semiconductor layer on the side of the initial tunneling layer away from the substrate; diffusing a first doping element into the first semiconductor layer to form an initial doped field region disposed on the first surface; forming a groove on the second region, and removing the portions of the initial tunneling layer, the first semiconductor layer, and the initial doped field region located in the second region to obtain a tunneling layer, a first doped semiconductor layer, and a doped field region; forming an amorphous layer; and forming a second doped semiconductor layer disposed on the side of the amorphous layer away from the substrate; wherein a portion of the amorphous layer is disposed on the second region, and another portion of the amorphous layer is disposed on the side of the first doped semiconductor layer away from the substrate; the second doped semiconductor layer has a second doping element of a different doping type than the first doping element. The depth of the doped field region is less than the depth of the groove.

[0022] In one embodiment, in the step of diffusing the first dopant element into the first semiconductor layer, the diffusion temperature of the first dopant element is 700°C-1000°C; and / or, the diffusion time of the first dopant element is 5 min-60 min.

[0023] According to a third aspect of this application, a photovoltaic module is provided, including a back contact battery of any of the above embodiments.

[0024] In the technical solution of this application, the doped field region has a first doping element. Since the doped field region is located in the first region, the first doping element can be used to repair surface defects of the substrate. Furthermore, the doped field region can increase the carrier concentration in the first region of the substrate, thereby enabling the doped field region to form a conductive region. This reduces the resistance of the back contact cell. Simultaneously, the doped field region also reduces the probability of carrier recombination and, in conjunction with the tunneling layer, forms field-effect passivation, thereby improving the passivation performance of the back contact cell. In addition, in this application, the tunneling layer is only located in the first region; therefore, it can be understood that the groove shape in the second region... In the case of forming after the first doped semiconductor layer, in order to remove the portion of the second region that is made of the same material as the tunneling layer and the first doped semiconductor layer, the portion of the second region that is made of the same material as the doped field region is also removed, thereby forming a groove. In the first direction, the bottom wall of the groove is located closer to the second surface than the doped field region. Therefore, the probability of the first doping element used to dop the first doped semiconductor layer remaining in the portion of the substrate corresponding to the second region can be reduced. In this way, the passivation performance of the first region can be improved while the passivation performance of the second region can also be taken into account. Overall, the passivation performance of the back contact battery can be improved. Attached Figure Description

[0025] Figure 1 A schematic diagram of the back contact battery in one embodiment of this application is shown.

[0026] Figure 2 The diagram shows the trend of the doping concentration versus depth of the first doped element in the back contact battery according to an embodiment of this application.

[0027] Figure 3 It shows Figure 1 An enlarged schematic diagram of a local structure.

[0028] Figure 4 A schematic diagram of the structure of the substrate, initial tunneling layer, first semiconductor layer, initial doped field region and phosphosilicate glass in one embodiment of this application is shown.

[0029] Figure 5 This illustration shows a step of the preparation method of a back contact battery according to an embodiment of the present application.

[0030] Figure 6 This illustration shows another step in the preparation method of the back contact battery according to one embodiment of the present application.

[0031] Figure 7 This illustration shows a process diagram of another step in the preparation method of the back contact battery according to an embodiment of this application.

[0032] Figure 8 A schematic diagram of the structure of the substrate, initial tunneling layer, first semiconductor layer, initial doped field region and phosphosilicate glass in another embodiment of this application is shown.

[0033] Figure 9 A schematic diagram of the structure of a photovoltaic module according to an embodiment of this application is shown.

[0034] Figure label:

[0035] Substrate 110, first surface 111, first region 1111, second region 1112, second surface 112, tunneling layer 121, initial tunneling layer 1210, tunneling portion 1211, blocking portion 1212, first doped semiconductor layer 122, first semiconductor layer 1220, middle portion 1221, edge portion 1222, doped field region 123, initial doped field region 1230, first doped sub-region 1231, second doped sub-region 1232, third doped sub-region 1233, amorphous layer 131, initial amorphous layer 1310, second doped semiconductor layer 132, second semiconductor layer 1320, first transparent conductive layer 141, second transparent conductive layer 142, first electrode 151, second electrode 152, first passivation layer 161, first antireflection layer 162, phosphosilicate glass 170, mask layer 180;

[0036] Battery string 10;

[0037] Encapsulation layer 20;

[0038] First cover plate 31, second cover plate 32. Detailed Implementation

[0039] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0040] In the description of this application, it should be understood that if terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" appear, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0041] Furthermore, where the terms "first" and "second" appear, these terms are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, where the term "multiple" appears, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0042] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0043] In this application, unless otherwise expressly specified and limited, the use of descriptions such as "above" or "below" the second feature indicates that the first and second features are in direct contact or indirect contact via an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. Similarly, "below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0044] It should be noted that if an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. If an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. If so, the terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this application are for illustrative purposes only and do not represent the only possible implementation.

[0045] In the accompanying drawings, the thicknesses of layers, films, regions, substrates, etc., are exaggerated for clarity. Throughout the specification, the same reference numerals refer to the same elements. It should be understood that when an element such as a layer, film, region, or substrate is referred to as being "on" another element, it may be directly on the other element or there may be intervening elements. Conversely, when an element is referred to as being "directly on" another element, there are no intervening elements.

[0046] Those within the measurement tolerance or manufacturing error range shall be considered substantially identical.

[0047] To improve the passivation performance of back contact batteries, this application designs a back contact battery, a method for preparing a back contact battery, and a photovoltaic module.

[0048] Figure 1 A schematic diagram of the back contact battery in one embodiment of this application is shown.

[0049] Please see Figure 1 One embodiment of this application provides a back contact battery, which includes a substrate 110, a tunneling layer 121, a first doped semiconductor layer 122, a doped field region 123, an amorphous layer 131, and a second doped semiconductor layer 132.

[0050] The substrate 110 has a first surface 111 and a second surface 112 disposed opposite to each other along a first direction F1. The first surface 111 includes alternating first regions 1111 and second regions 1112. A tunneling layer 121 is disposed on the first region 1111, and a first doped semiconductor layer 122 is disposed on the side of the tunneling layer 121 away from the substrate 110. A doped field region 123 is located in the first region 1111. Both the doped field region 123 and the first doped semiconductor layer 122 have a first doped element. A second region 1112 has a groove recessed relative to the first region 1111. A portion of an amorphous layer 131 is disposed on the second region 1112, and another portion of the amorphous layer 131 is disposed on the side of the first doped semiconductor layer 122 away from the substrate 110. A second doped semiconductor layer 132 is disposed on the side of the amorphous layer 131 away from the substrate 110, and the second doped semiconductor layer 132 has a second doped element of a different doping type than the first doped element. The depth of the doped field region 123 is less than the depth of the groove.

[0051] The substrate 110 can be made of a semiconductor material. Optionally, common semiconductor materials include, but are not limited to, single-crystal silicon, polycrystalline silicon, silicon germanide, silicon carbide, gallium arsenide, indium gallium arsenide, perovskite, cadmium telluride, or copper indium selenide; the substrate 110 can also be a sapphire substrate, a silicon-on-insulator substrate, or a germanium-on-insulator substrate.

[0052] The first side 111 is usually the back side, so the first side 111 can also be called the back side; however, with the development of back contact battery technology, the first side 111 may also receive the energy of sunlight, mainly from the light reflected or scattered by the surrounding environment.

[0053] The second side 112 is usually the light-receiving surface (the light-receiving surface specifically refers to the side surface on the back contact battery that is mainly used to receive sunlight). The second side 112 can also be called the front side.

[0054] At least a portion of the first surface 111 and the second surface 112 may employ a textured structure to increase the light absorption area and photocurrent, thereby improving the efficiency of the solar cell.

[0055] Figure 1 The second surface 112 is shown to have a textured structure, and the second region 1112 of the first surface 111 is also shown to have a textured structure. This textured structure can be a pyramidal textured structure, which can not only reduce the reflectivity of the second surface 112 and the second region 1112, but also form a light trap, thereby improving the conversion efficiency of the back contact battery.

[0056] In the second region 1112, the textured structure is located on the bottom wall of the groove, which helps to improve the light trapping effect of the second region 1112, thereby further increasing the density of photogenerated carriers. Here, the bottom wall of the groove refers to the part of the groove wall that is disposed opposite to the second surface 112 along the first direction F1.

[0057] The first region 1111 may have a polished structure. Setting the first region 1111 as a polished structure is beneficial to improving the uniformity of the tunneling layer 121 located in the first region 1111. That is, the thickness of each region in the tunneling layer 121 is not significantly different, thereby improving the passivation effect of the first region 1111.

[0058] The first region 1111 may refer to the region on the first surface 111 that is disposed opposite to the first doped semiconductor layer 122 along the first direction F1, or it can be understood as the region where the orthogonal projection of the first doped semiconductor layer 122 is located on the first surface 111. That is, the first region 1111 and the first doped semiconductor layer 122 are stacked along the first direction F1.

[0059] The second region 1112 may refer to the region where the first surface 111 is disposed opposite to a part of the second doped semiconductor layer 132 along the first direction F1, or it can be understood as the region where the orthogonal projection of a part of the second doped semiconductor layer 132 is located on the first surface 111, that is, a part of the second doped semiconductor layer 132 and the second region 1112 are stacked along the first direction F1.

[0060] The first region 1111 and the second region 1112 can be arranged alternately along a preset direction, which can be perpendicular to the first direction F1.

[0061] It is possible that one of the first dopant element and the second dopant element is of the P-type doping type, and the other of the first dopant element and the second dopant element is of the N-type doping type. For example, the first dopant element is of the N-type doping type, and the second dopant element is of the P-type doping type.

[0062] For example, the first dopant element may be one of antimony, phosphorus, arsenic and bismuth, and the second dopant element may be boron, aluminum or gallium.

[0063] The tunneling layer 121 is used to passivate the interface of the first region 1111 of the first surface 111 of the substrate 110, achieving the effect of chemical passivation. Specifically, by saturating the dangling bonds of the first region 1111 of the first surface 111, the interface trapped state density of the first region 1111 of the first surface 111 is reduced, thereby reducing the carrier recombination rate of the first region 1111 of the first surface 111.

[0064] The material of the tunneling layer 121 can be a dielectric material, such as at least one of silicon oxide, amorphous silicon, polycrystalline silicon, silicon carbide, silicon nitride, silicon oxynitride, aluminum oxide, or titanium oxide.

[0065] In the embodiments of this application, the tunneling layer 121 can be formed using low-pressure chemical vapor deposition (LPCVD). Of course, other processes such as thermal oxidation, plasma oxidation, or nitric acid oxidation can also be used to fabricate the tunneling layer 121, and no specific limitation is made here.

[0066] In the embodiments of this application, the thickness of the tunneling layer 121 can be 0.1nm-5nm. For example, the thickness of the tunneling layer 121 can be 0.1nm, 0.3nm, 0.5nm, 1nm, 2nm, 3nm, 4nm, or 5nm, etc. No specific limitation is made here.

[0067] By controlling the thickness of the tunneling layer 121, it is possible to achieve a certain passivation effect while also facilitating the diffusion of the first dopant element into the substrate 110 to form the doped field region 123.

[0068] The material of the first doped semiconductor layer 122 may be doped polycrystalline silicon including a first doping element and a second doping element, and the first doped semiconductor layer 122 may also include at least one element selected from oxygen, carbon and nitrogen.

[0069] The thickness of the first doped semiconductor layer 122 can be 80nm-240nm.

[0070] For example, the thickness of the first doped semiconductor layer 122 can be 80nm, 100nm, 140nm, 180nm, 200nm, or 240nm, etc. No specific limitation is made here.

[0071] The doped field region 123 is formed when the first doped element diffuses through the tunneling layer 121 to the first region 1111 during the process of doping the first doped semiconductor layer 122. The doped field region 123 is located within the substrate 110.

[0072] The doped field region 123 refers to the region within the substrate 110 where the doping concentration of the first doped element is relatively high. Within the substrate 110, the region extending from the surface of the first region 1111 toward the center of the substrate 110 at a first depth is the doped field region 123, and the first depth is the depth of the doped field region 123.

[0073] It is possible that the first depth corresponding to the middle region and the edge region of the doped field region 123 is the same, or it is possible that the first depth corresponding to the middle region and the edge region of the doped field region 123 is different; no specific restrictions are imposed here.

[0074] It is understood that the doping concentration of the first dopant element in the doping field region 123 is greater than the doping concentration of the first dopant element in the other regions of the substrate 110 excluding the doping field region 123.

[0075] It can be that the average doping concentration of the first dopant element in the doping field region 123 is greater than the doping concentration of the first dopant element in the other regions of the substrate 110 excluding the doping field region 123; or it can be that the average doping concentration of the first dopant element in the doping field region 123 is greater than the average doping concentration of the first dopant element in the other regions of the substrate 110 excluding the doping field region 123.

[0076] The average doping concentration of the first dopant element in the doping field region 123 refers to the average doping concentration of the first dopant element in different depth regions of the doping field region 123.

[0077] The average doping concentration of the first doped element in the remaining regions of the substrate 110, excluding the doped field region 123, refers to the average doping concentration of the first doped element in the remaining regions of the substrate 110, excluding the doped field region 123, at different depths.

[0078] Under the same test conditions (such as the same sputtering rate and the same ion beam parameters), the doping concentration of the first dopant element in the doped field region 123 and the doping concentration of the first dopant element in the other regions of the substrate 110 excluding the doped field region 123 can be detected by secondary ion mass spectrometry (SIMS). The depth distribution curve, surface distribution image and / or line scan spectrum corresponding to the first dopant element can be obtained. From these, the average doping concentration or integral doping amount of the first dopant element can be extracted, thereby obtaining the relationship between the doping concentration of the first dopant element in the doped field region 123 and the doping concentration of the first dopant element in the other regions of the substrate 110 excluding the doped field region 123.

[0079] Figure 2 A trend graph showing the relationship between the doping concentration and depth of the first dopant element in the back contact cell is presented. Figure 2In the diagram, the horizontal axis represents depth D, and the vertical axis represents the doping concentration C of the first dopant element. Figure 2 The document presents trend curves of doping concentration and depth of the first doped element in the first doped semiconductor layer 122, tunneling layer 121 and doped field region 123. However, it does not indicate the specific values ​​of the doping concentration of the first doped element in the first doped semiconductor layer 122, tunneling layer 121 and doped field region 123, nor does it indicate the specific values ​​of the depths corresponding to the first doped semiconductor layer 122, tunneling layer 121 and doped field region 123.

[0080] Figure 2 The depth distribution curve corresponding to the first dopant element can be obtained by sputtering layer by layer from the outside to the inside of the back contact cell using secondary ion mass spectrometry (SIMS). Figure 2 Based on the corresponding depth distribution curve, the depth D is also the sputtering depth of the ion beam in secondary ion mass spectrometry (SIMS).

[0081] from Figure 2 It can be seen that the doping concentration of the first dopant element in the doping field region 123 is greater than the doping concentration of the first dopant element in the other regions of the substrate 110 excluding the doping field region 123.

[0082] Based on, for example Figure 2 The SIMS test results shown indicate that the start and end points of the doped field region 123 are determined by the trend of the doping concentration of the first dopant element, thereby obtaining the thickness (depth) of the doped field region 123.

[0083] It should be noted that, Figure 2 The trend curves corresponding to a portion of the base 110 are shown in the figure.

[0084] Since the doping concentration of the first dopant element in the doped field region 123 is greater than that in the other regions of the substrate 110 excluding the doped field region 123, a high-low junction can be formed between the doped field region 123 and the other regions of the substrate 110 excluding the doped field region 123. In the high-low junction, there is a built-in electric field, which helps to effectively collect carriers, reduces recombination, and improves the open-circuit voltage and fill factor.

[0085] Can be combined Figure 2To understand this, the depth (first depth) of the doped field region 123 can be the distance in the first direction F1 from the side of the doped field region 123 away from the tunneling layer 121 to the side of the doped field region 123 near the tunneling layer 121. Alternatively, the depth of the doped field region 123 can be understood as approximately equal to its thickness. The depth of the doped field region 123 can be obtained by taking the average of the distances in the first direction F1 from the side of the doped field region 123 away from the tunneling layer 121 to the side of the doped field region 123 near the tunneling layer 121 a finite number of times.

[0086] The depth of the groove refers to the distance along the first direction F1 between the groove opening and the bottom wall of the groove. In this application, the groove is formed after the first doped semiconductor layer 122. The location of the groove opening corresponds to the position of the first doped semiconductor layer 122 away from the substrate 110. Therefore, the distance along the first direction F1 between the groove opening and the bottom wall of the groove is: the distance along the first direction F1 between the side of the first doped semiconductor layer 122 away from the substrate 110 and the bottom wall of the groove. When the amorphous layer 131 and the second doped semiconductor layer 132 are formed in a portion of the first region 1111 and the second region 1112, respectively, the groove depth can be obtained by calculating the average value of the distance between the side of the first transparent conductive layer 141 away from the second doped semiconductor layer 132 on the first region 1111 and the side of the second transparent conductive layer 142 away from the second doped semiconductor layer 132 on the second region 1112, measured a finite number of times.

[0087] For example, in one measurement, the distance between the side of the first transparent conductive layer 141 on the first region 1111 away from the second doped semiconductor layer 132 and the side of the second transparent conductive layer 142 on the second region 1112 away from the second doped semiconductor layer 132 is 'a'; in another measurement, the distance between the side of the first transparent conductive layer 141 on the first region 1111 away from the second doped semiconductor layer 132 and the side of the second transparent conductive layer 142 on the second region 1112 away from the second doped semiconductor layer 132 is 'b'; in yet another measurement, the distance between the side of the first transparent conductive layer 141 on the first region 1111 away from the second doped semiconductor layer 132 and the side of the second transparent conductive layer 142 on the second region 1112 away from the second doped semiconductor layer 132 is 'c'; the depth of the groove can be obtained by calculating the average of a, b, and c.

[0088] A cross-sectional image of the back-contact battery can be obtained using a scanning electron microscope (SEM), thereby measuring the distance between the side of the first transparent conductive layer 141 on the first region 1111 away from the second doped semiconductor layer 132 and the side of the second transparent conductive layer 142 on the second region 1112 away from the second doped semiconductor layer 132. Alternatively, other methods can be used to measure the distance between the side of the first transparent conductive layer 141 on the first region 1111 away from the second doped semiconductor layer 132 and the side of the second transparent conductive layer 142 on the second region 1112 away from the second doped semiconductor layer 132.

[0089] The amorphous layer 131 is used to electrically isolate the substrate 110 and the second doped semiconductor layer 132, and can also be used to electrically isolate the first doped semiconductor layer 122 and the second doped semiconductor layer 132.

[0090] The thickness of the amorphous layer 131 can be 7nm-20nm.

[0091] For example, the thickness of the amorphous layer 131 is 7 nm, 10 nm, 15 nm, 18 nm or 20 nm, etc.

[0092] This configuration can improve the passivation effect of the amorphous layer 131.

[0093] The material of the second doped semiconductor layer 132 includes doped amorphous silicon. Thus, the second doped semiconductor layer 132 can be formed by a low-temperature deposition process, which is more conducive to reducing the probability of the second doped element diffusing to the substrate 110, thereby improving the passivation effect of the second region 1112.

[0094] The thickness of the second doped semiconductor layer 132 can be 10nm-80nm.

[0095] For example, the thickness of the second doped semiconductor layer 132 can be 10nm, 20nm, 25nm, 30nm, 35nm, 45nm, 50nm, 65nm, 70nm, or 80nm, etc. No specific limitation is made here.

[0096] Since a portion of the amorphous layer 131 is located in the second region 1112, another portion of the amorphous layer 131 is located on the side of the first doped semiconductor layer 122 away from the tunneling layer 121.

[0097] This can be understood as follows: first, a tunneling layer 121 and a first doped semiconductor layer 122 are formed on the first region 1111, and then an amorphous layer 131 is formed on the first region 1111 and the second region 1112 respectively. In this way, the amorphous layer 131 can be used to better electrically isolate the first doped semiconductor layer 122 and the second doped semiconductor layer 132, and also make the groove of the second region 1112 formed after the first doped semiconductor layer 122.

[0098] The doped field region 123 has a first doped element. Since the doped field region 123 is located in the first region 1111, surface defects of the substrate 110 can be repaired using the first doped element. Furthermore, the doped field region 123 can increase the carrier concentration in the first region 1111 of the substrate 110, thereby enabling the doped field region 123 to form a conductive region. This reduces the resistance of the back contact cell. Simultaneously, the doped field region 123 also reduces the probability of carrier recombination and, in conjunction with the tunneling layer 121, forms field-effect passivation, thereby improving the passivation performance of the back contact cell. In addition, in this application, the tunneling layer 121 is only located in the first region 1111. Therefore, it can be understood that when the groove in the second region 1112 is formed after the first doped semiconductor layer 122, in order to remove the groove in the second region 1112... The portion of the material being the same as that of the tunneling layer 121 and the first doped semiconductor layer 122 is removed, and the portion of the material being the same as that of the doped field region 123 on the second region 1112 is also removed (i.e., the portion of the initial tunneling layer 1210, the first semiconductor layer 1220, and the initial doped field region 1230 located in the second region 1112 is removed), thereby forming a groove. In the first direction F1, the bottom wall of the groove is located closer to the second surface 112 than the doped field region 123. Therefore, the probability of the first doping element used to do the first doped semiconductor layer 122 remaining in the portion of the substrate 110 corresponding to the second region 1112 can be reduced. In this way, the passivation performance of the first region 1111 can be improved while the passivation performance of the second region 1112 can also be taken into account. Overall, the passivation performance of the back contact battery can be improved.

[0099] In addition, the density of the tunneling layer 121 is usually less than that of the amorphous layer 131. Thus, the denser amorphous layer 131 can reduce the probability of the second dopant element diffusing into the substrate 110, thereby improving the passivation performance of the second region 1112.

[0100] The thickness of the tunneling layer 121 can be measured using X-ray reflectance (XRR) combined with fitting software (such as X-RayCalc or GenX). Alternatively, the fitted value of the refractive index of the tunneling layer 121 can be obtained using XRR combined with fitting software. Then, the density of the tunneling layer 121 can be calculated based on the fitted value n of the refractive index and the theoretical value n0 of the refractive index of the tunneling layer 121. The density of the tunneling layer 121 is the percentage of (1-n) to (1-n0). When the material of the tunneling layer 121 is silicon dioxide, the theoretical value of its refractive index is 1.4584 g / cm³. 3 The fitted value n of the refractive index of tunnel layer 121 can be obtained by performing a finite number of measurements and fittings, and then taking the average value.

[0101] Similarly, the density of amorphous layer 131 can also be detected.

[0102] It should be noted that, since the tunneling layer 121 is located inside the amorphous layer 131, in order to improve the measurement accuracy of the tunneling layer 121, the back contact cell can be left undamaged first, and the density of the amorphous layer 131 located on the outer side can be measured; then, the back contact cell can be ground flat down to the first doped semiconductor layer 122 using chemical mechanical polishing, and then the density of the tunneling layer 121 can be measured.

[0103] In some embodiments, the sum of the thickness of the tunneling layer 121, the thickness of the first doped semiconductor layer 122, and the depth of the doped field region 123 is less than the depth of the trench.

[0104] Therefore, when the groove in the second region 1112 is formed after the first doped semiconductor layer 122, the bottom wall of the groove can be positioned closer to the second surface 112 than the doped field region 123 in the first direction F1. This can further reduce the probability that the first doping element used to dop the first doped semiconductor layer 122 remains in the portion of the substrate 110 corresponding to the second region 1112, thus improving the passivation performance of the back contact battery.

[0105] In some embodiments, the substrate 110 also has a first doping element.

[0106] Since the doped field region 123, the first doped semiconductor layer 122, and the substrate 110 are allowed to have the same first doping element, during the formation of the first doped semiconductor layer 122 and the doped field region 123, the first doping element used to dop the first doped semiconductor layer 122 diffuses into the substrate 110 through the tunneling layer 121 to form the doped field region 123. Furthermore, the process for forming the first doped semiconductor layer 122 and the doped field region 123 is no longer limited by the condition that "the first doping element cannot diffuse into the substrate 110", thereby expanding the process window. Moreover, the process for forming the doped field region 123 can be matched with the process for forming the first doped semiconductor layer 122, thereby improving mass production stability.

[0107] In some embodiments, the depth of the groove is less than the dimension of the second region 1112 along a predetermined direction.

[0108] Optionally, the ratio between the depth of the groove and the dimension of the second region 1112 along a preset direction is less than or equal to 0.1 and greater than or equal to 0.002.

[0109] For example, the ratio between the depth of the groove and the dimension of the second region 1112 along a preset direction is 0.002, 0.005, 0.01, 0.075, or 0.1, etc.

[0110] Thus, the wider groove is beneficial to improving the deposition uniformity of the amorphous layer 131 on the groove wall, thereby increasing the density of the amorphous layer 131, which can reduce the probability of the second dopant element diffusing to the substrate 110, thereby improving the passivation performance of the second region 1112.

[0111] In some embodiments, the second region 1112 has a first pyramidal structure, the second face 112 has a second pyramidal structure, and the size of the first pyramidal structure is smaller than the size of the second pyramidal structure.

[0112] It is possible that the second region 1112 has a first texture structure, the second surface 112 has a second texture structure, the first texture structure includes a first pyramid-shaped structure, and the second texture structure includes a second pyramid-shaped structure.

[0113] Alternatively, along the first direction F1, the size of the first pyramid-shaped structure may be smaller than the size of the second pyramid-shaped structure. Or, along a preset direction, the size of the first pyramid-shaped structure may be smaller than the size of the second pyramid-shaped structure. Another possibility is that, along both the first and preset directions, the size of the first pyramid-shaped structure is smaller than the size of the second pyramid-shaped structure.

[0114] Thus, the smaller size of the first pyramidal structure improves the deposition uniformity of the amorphous layer 131 on the trench wall, thereby increasing the density of the amorphous layer 131. This reduces the probability of the second dopant element diffusing into the substrate 110, thereby improving the passivation performance of the second region 1112 and forming a light trap, which in turn improves the conversion efficiency of the back contact cell.

[0115] In some embodiments, the amorphous layer 131 is made of amorphous silicon.

[0116] It is possible that the amorphous layer 131 is an amorphous silicon layer. Alternatively, the amorphous layer 131 may include multiple amorphous silicon layers.

[0117] Alternatively, the amorphous layer 131 may include multiple sublayers, one of which is an amorphous silicon layer, and another is a microcrystalline silicon layer. No specific restrictions are imposed here.

[0118] Since the amorphous silicon layer and the microcrystalline silicon layer have good density, the amorphous layer 131 can have high density, thereby reducing the probability of the second dopant element diffusing to the substrate 110, and thus improving the passivation contact performance of the second region 1112.

[0119] Furthermore, when the amorphous layer 131 comprises multiple sublayers and the materials of the multiple sublayers are different, the amorphous layer 131 can have a good passivation effect through the combination of multiple sublayers.

[0120] In some embodiments, the ratio of the depth of the groove to the depth of the doped field region 123 is 5-100.

[0121] For example, the ratio of the depth of the groove to the depth of the doped field region 123 is 5, 10, 30, 70 or 100, etc.

[0122] It is understood that the depth of the groove is much greater than the depth of the doped field region 123. Therefore, the deeper groove can be used to better reduce the probability that the first doping element used to dop the first doped semiconductor layer 122 remains in the portion of the substrate 110 corresponding to the second region 1112, thereby improving the passivation performance of the back contact battery.

[0123] In some embodiments, the depth of the doped field region 123 is on the nanometer scale, and the depth of the groove is on the micrometer scale.

[0124] The depth of the groove differs from the depth of the doped field region 123 by three orders of magnitude. Combined with the thickness of the tunneling layer 121 and the thickness of the first doped semiconductor layer 122, which is typically 80nm-245nm, the deeper groove can better reduce the probability of the first doping element used to dop the first doped semiconductor layer 122 remaining in the portion of the substrate 110 corresponding to the second region 1112, thereby improving the passivation performance of the back contact battery.

[0125] In some embodiments, the depth of the doped field region 123 is H1, where H1 is 100nm-1000nm.

[0126] "The depth of the doped field region 123 is 100nm-1000nm" means that the depth of the doped field region 123 is in the range of 100nm-1000nm.

[0127] For example, the depth of the doped field region 123 is 100nm, 200nm, 300nm, 400nm, 500nm, 600nm, 700nm, 800nm, 900nm or 1000nm, etc.

[0128] It is understandable that the doped field region 123 has a certain doping depth. The first doping element can effectively repair the internal defects of the substrate 110, while also increasing the carrier concentration in the first region 1111 of the substrate 110, thereby reducing the resistance of the back contact cell.

[0129] In some embodiments, H1 is 200nm-400nm.

[0130] For example, the depth of the doped field region 123 is 200 nm, 250 nm, 300 nm, 350 nm or 400 nm, etc.

[0131] Setting the depth of the doped field region 123 within a reasonable range, such as 200nm-400nm, helps to reasonably control the process window for forming the first doped semiconductor layer 122 and the doped field region 123.

[0132] In some embodiments, the depth of the groove is H2, and the value of H2 ranges from 1μm to 10μm.

[0133] "The depth of the groove is 1μm-10μm" means that the depth of the groove ranges from 1μm to 10μm.

[0134] For example, the depth of the groove is 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm or 10μm, etc.

[0135] Setting the depth of the groove within a reasonable range, such as 1μm-10μm, not only helps to expand the process window of the groove, but also avoids leakage.

[0136] In some embodiments, the value of H2 ranges from 4 μm to 10 μm. For example, the depth of the groove is 4 μm, 6 μm, 8 μm, or 10 μm.

[0137] Yes, the value of H2 can be in the range of 4μm-8μm.

[0138] In the case where the material corresponding to the tunneling layer 121 and the first doped semiconductor layer 122 on the second region 1112 is first removed by laser, and then the groove is formed by etching with an etchant, the depth of the groove is set within a reasonable range, such as 4μm-10μm. This not only helps to reduce etching damage, thereby improving the reliability of the back contact battery, but also reduces the probability that the first doping element used to dop the first doped semiconductor layer 122 remains in the part of the substrate 110 corresponding to the second region 1112, while also taking into account the process cost.

[0139] In some embodiments, the doping concentration of the first dopant element in the first doped semiconductor layer 122 is greater than the doping concentration of the first dopant element in the doped field region 123.

[0140] It is possible that the average doping concentration of the first doped element in the first doped semiconductor layer 122 is greater than the average doping concentration of the first doped element in the doped field region 123.

[0141] The average doping concentration of the first doped element in the first doped semiconductor layer 122 is the average doping concentration of the first doped element in different depth regions of the first doped semiconductor layer 122.

[0142] Similarly, under the same test conditions (such as the same sputtering rate and the same ion beam parameters, etc.), the doping concentration of the first dopant element in the first doped semiconductor layer 122 and the doping concentration of the first dopant element in the doped field region 123 can be detected by secondary ion mass spectrometry (SIMS) technology, thereby obtaining the relationship between the doping concentration of the first dopant element in the first doped semiconductor layer 122 and the doping concentration of the first dopant element in the doped field region 123.

[0143] from Figure 2 It can be seen that the doping concentration of the first doped element in the first doped semiconductor layer 122 is approximately greater than the doping concentration of the first doped element in the doped field region 123.

[0144] The first doping element has a high doping concentration in the first doped semiconductor layer 122, which can fully realize the effect of the first doped semiconductor layer 122 and help reduce the contact resistance of the back contact battery.

[0145] Furthermore, the doping concentration of the first doped element in the first doped semiconductor layer 122, the doping concentration of the first doped element in the doped field region 123, and the doping concentration of the first doped element in the remaining regions of the substrate 110 excluding the doped field region 123 tend to decrease, which can increase the conductivity of charge carriers and thus improve the working efficiency of the back contact battery.

[0146] In some embodiments, the doped field region 123 includes a first doped sub-region 1231 and a second doped sub-region 1232. Along the first direction F1, the first doped sub-region 1231 is disposed closer to the first surface 111 than the second doped sub-region 1232. The doping concentration of the first doped element in the first doped sub-region 1231 is greater than the doping concentration of the first doped element in the second doped sub-region 1232.

[0147] In other words, along the first direction F1, the first doped sub-region 1231 is located further away from the second surface 112 than the second doped sub-region 1232.

[0148] The first doped sub-region 1231 refers to a portion of the doped field region 123 that is located closer to the first surface 111 than the second doped sub-region 1232 along the first direction F1.

[0149] The second doped sub-region 1232 refers to a portion located along the first direction F1 on the doped field region 123 that is further away from the first surface 111 than the first doped sub-region 1231.

[0150] It is possible that the average doping concentration of the first doped element in the first doped sub-region 1231 is greater than the average doping concentration of the first doped element in the second doped sub-region 1232.

[0151] It is understandable that, along the direction from the first surface 111 to the second surface 112, the first doping element tends to decrease in the doping field region 123, which can increase the conductivity of charge carriers and thus improve the working efficiency of the back contact battery.

[0152] In some embodiments, the doped field region 123 further includes a third doped sub-region 1233 located along a first direction F1 between the first doped sub-region 1231 and the second doped sub-region 1232. The doping concentration of the first doped element in the first doped sub-region 1231 is greater than the doping concentration of the first doped element in the third doped sub-region 1233, and the doping concentration of the first doped element in the third doped sub-region 1233 is greater than the doping concentration of the first doped element in the second doped sub-region 1232.

[0153] It is possible that the average doping concentration of the first doped element in the first doped sub-region 1231 is greater than the average doping concentration of the first doped element in the third doped sub-region 1233, and the average doping concentration of the first doped element in the third doped sub-region 1233 is greater than the average doping concentration of the first doped element in the second doped sub-region 1232.

[0154] The third doped sub-region 1233 refers to the portion of the doped field region 123 located between the first doped sub-region 1231 and the second doped sub-region 1232 along the first direction F1.

[0155] It is understood that, along the direction from the first surface 111 to the second surface 112, the first dopant element has a decreasing trend in the doping field region 123 and has a concentration gradient. Therefore, the doping field region 123 can be used to better increase the conductivity of charge carriers, thereby improving the working efficiency of the back contact battery.

[0156] In one embodiment, the doping concentration of the first dopant element in the doping field region 123 is 1 × 10⁻⁶. 15 atom / cm 3 -1×10 22 atom / cm 3 .

[0157] For example, the doping concentration of the first dopant element in the doping field region 123 is 1 × 10⁻⁶. 15 atom / cm 3 1×10 16 atom / cm 3 1×10 17 atom / cm 3 1×10 18 atom / cm 3 1×10 19 atom / cm 3 1×10 20 atom / cm3 Or 1×10 22 atom / cm 3 wait.

[0158] In one embodiment, the doping concentration of the first dopant element in the remaining regions of the substrate 110, excluding the doped field region 123, is 1 × 10⁻⁶. 14 atom / cm 3 -1×10 17 atom / cm 3 .

[0159] For example, the doping concentration of the first dopant element in the remaining regions of the substrate 110, excluding the doped field region 123, is 1 × 10⁻⁶. 14 atom / cm 3 1×10 16 atom / cm 3 2×10 16 atom / cm 3 3×10 16 atom / cm 3 4×10 16 atom / cm 3 5×10 16 atom / cm 3 Or 1×10 17 atom / cm 3 wait.

[0160] In one embodiment, the doping concentration of the first dopant element in the first doped semiconductor layer 122 is 1×10⁻⁶. 18 atom / cm 3 -1×10 22 atom / cm 3 .

[0161] For example, the doping concentration of the first doped element in the first doped semiconductor layer 122 is 1 × 10⁻⁶. 18 atom / cm 3 1×10 20 atom / cm 3 2×10 20 atom / cm 3 3×10 20 atom / cm 3 4×10 20 atom / cm 3 5×10 20 atom / cm 3 Or 1×10 22 atom / cm 3 wait.

[0162] In one embodiment, the doping concentration of the first dopant element in the tunneling layer 121 is 1 × 10⁻⁶. 18 atom / cm 3 -1×10 22 atom / cm 3 .

[0163] For example, the doping concentration of the first dopant element in the tunneling layer 121 is 1 × 10⁻⁶. 18 atom / cm 3 1×10 19 atom / cm 3 2×10 20 atom / cm 3 2.5×10 20 atom / cm 3 3.1×10 20 atom / cm 3 Or 1×10 22 atom / cm 3 wait.

[0164] In some embodiments, the density of the tunneling layer 121 on the side near the substrate 110 is different from the density of the tunneling layer 121 on the side away from the substrate 110.

[0165] For example, the density of the tunneling layer 121 on the side closer to the substrate 110 is less than the density of the tunneling layer 121 on the side farther from the substrate 110. Or, for another example, the density of the tunneling layer 121 on the side closer to the substrate 110 is greater than the density of the tunneling layer 121 on the side farther from the substrate 110.

[0166] It is possible that the tunneling layer 121 includes multiple tunneling sublayers, with the tunneling sublayers disposed closer to the substrate 110 having a lower density, or the tunneling sublayers disposed closer to the substrate 110 having a higher density.

[0167] The tunneling sublayer with lower density may include a porous structure; for example, the material of the tunneling sublayer with lower density may include porous silicon nitride.

[0168] The material for the tunneling sublayer with higher density can be silicon dioxide.

[0169] On the one hand, the density of the tunneling layer 121 on the side near the substrate 110 and the density of the tunneling layer 121 on the side away from the substrate 110 are relatively small, which is conducive to the diffusion of the first dopant element into the substrate 110, thereby improving the carrier transport performance of the first region 1111. On the other hand, the first dopant element can also fill the pores in the tunneling layer 121, and the density of the tunneling layer 121 on the side near the substrate 110 and the density of the tunneling layer 121 on the side away from the substrate 110 are relatively large, so the passivation contact performance of the first region 1111 can also be taken into account.

[0170] In some embodiments, the doping concentration of the first dopant element in the tunneling layer 121 may be greater than the doping concentration of the first dopant element in the doped field region 123. Alternatively, the doping concentration of the first dopant element in the tunneling layer 121 may be greater than the doping concentration of the first dopant element in the remaining regions of the substrate 110 excluding the doped field region 123. Alternatively, the doping concentration of the first dopant element in the tunneling layer 121 may be greater than the doping concentration of the first dopant element in the doped field region 123, and also greater than the doping concentration of the first dopant element in the remaining regions of the substrate 110 excluding the doped field region 123, and also greater than the doping concentration of the first dopant element in the first doped semiconductor layer 122.

[0171] It is possible that the average doping concentration of the first doped element in the tunneling layer 121 is greater than the average doping concentration of the first doped element in the doped field region 123, and is greater than the average doping concentration of the first doped element in the other regions of the substrate 110 excluding the doped field region 123, and is greater than the average doping concentration of the first doped element in the first doped semiconductor layer 122.

[0172] The average doping concentration of the first dopant element in the tunneling layer 121 is the average doping concentration of the first dopant element in different depth regions of the tunneling layer 121.

[0173] from Figure 2 It can be roughly seen that the doping concentration of the first doped element in the tunneling layer 121 is greater than that in the first doped semiconductor layer 122, and greater than that in the doped field region 123, and greater than that in the other regions of the substrate 110 except for the doped field region 123.

[0174] Thus, the first doping element has a high doping concentration in the tunneling layer 121, which can enrich the first doping element in the tunneling layer 121. The first doping element can be used to fill the pores in the tunneling layer 121, thereby improving the passivation performance of the first region 1111.

[0175] Furthermore, the doping concentration of the first doped element in the first doped semiconductor layer 122, the doping concentration of the first doped element in the doped field region 123, and the doping concentration of the first doped element in the remaining regions of the substrate 110 excluding the doped field region 123 generally show a decreasing trend, which is beneficial to improving the conductivity of charge carriers in the first region 1111, thereby improving the working efficiency of the back contact battery.

[0176] In some embodiments, the back contact battery further includes a first transparent conductive layer 141, which is disposed on the side of the first doped semiconductor layer 122 away from the substrate 110 and is electrically connected to the first doped semiconductor layer 122.

[0177] The material of the first transparent conductive layer 141 includes at least one of indium tin oxide, tungsten-doped indium oxide, titanium-doped indium oxide, tin oxide, and aluminum-doped zinc oxide. The first transparent conductive layer 141 has light transmittance and conductivity, and has the functions of collecting and conducting current, as well as protecting the interface, which is beneficial to improving the photoelectric conversion efficiency and long-term stability of the back contact battery.

[0178] In some embodiments, the ratio of the doping concentration of the first dopant element in the doped field region 123 to the doping concentration of the second dopant element in the second doped semiconductor layer 132 is 0.1-10.

[0179] For example, the ratio of the doping concentration of the first dopant element in the doped field region 123 to the doping concentration of the second dopant element in the second doped semiconductor layer 132 is 0.1, 0.2, 0.5, 1, 2, 5, 8 or 10, etc.

[0180] It can be seen that the doping concentration of the first dopant element in the doped field region 123 is not much different from that of the second dopant element in the second doped semiconductor layer 132. In this way, the bulk recombination can be reduced and the open circuit voltage of the back contact battery can be increased, while minority carrier lifetime and lateral conductivity can also be taken into account, thereby improving the overall efficiency of the back contact battery.

[0181] In some embodiments, the doping concentration of the second dopant element in the second doped semiconductor layer 132 is 5 × 10⁻⁶. 15 atom / cm 3 -5×10 22 atom / cm 3 .

[0182] For example, the doping concentration of the second doped element in the second doped semiconductor layer 132 is 5 × 10⁻⁶. 15 atom / cm 3 5×10 16 atom / cm 3 5×1017 atom / cm 3 5×10 18 atom / cm 3 5×10 19 atom / cm 3 5×10 20 atom / cm 3 5×10 21 atom / cm 3 Or 5×10 22 atom / cm 3 wait.

[0183] Setting the doping concentration of the second doping element in the second doped semiconductor layer 132 within a suitable range is beneficial to improving the passivation contact performance of the second region 1112.

[0184] In some embodiments, the first doped semiconductor layer 122 and the second doped semiconductor layer 132 have different crystal phases.

[0185] The material of the first doped semiconductor layer 122 can be selected according to the conductivity requirements. For example, the material of the first doped semiconductor layer 122 is doped polycrystalline silicon including the first doping element and the second doping element, which helps to reduce the contact resistance of the back contact battery. It also makes it easier to select the material of the second doped semiconductor layer 132 according to the passivation requirements. For example, the material of the second doped semiconductor layer 132 includes doped amorphous silicon, which makes it easier to form the second doped semiconductor layer 132 at low temperature, thereby reducing the probability of the second doping element diffusing to the substrate 110, which helps to improve the passivation performance of the second region 1112.

[0186] In some embodiments, such as Figure 3 As shown, the first doped semiconductor layer 122 includes a middle portion 1221 and edge portions 1222 located on both sides of the middle portion 1221. A portion of the amorphous layer 131 is disposed on the side of the edge portions 1222 facing away from the substrate 110. The doping concentration of the first dopant element in the middle portion 1221 is greater than the doping concentration of the first dopant element in the edge portions 1222.

[0187] The middle part 1221 is the middle part of the first doped semiconductor layer 122.

[0188] The first region 1111 includes a metal region, and the middle portion 1221 is at least located in the metal region of the first region 1111. The metal region of the first region 1111 is the region on the first region 1111 that is disposed opposite to the first electrode 151. Typically, the width of the first region 1111 is greater than the width of the first electrode 151.

[0189] Wherein, the width of the first region 1111 is the dimension of the first region 1111 in the arrangement direction of the first region 1111 and the second region 1112, and the width of the first electrode 151 is the dimension of the first electrode 151 in the arrangement direction of the first region 1111 and the second region 1112.

[0190] The edge portion 1222 is a portion of the first doped semiconductor layer 122 that is close to the adjacent second region 1112 or close to the sidewall of the substrate 110.

[0191] Setting the doping concentration of the first dopant element in the middle portion 1221 to be greater than that in the edge portion 1222 is beneficial to reduce the contact resistance of the back contact battery, while also improving the passivation contact performance of the area of ​​the first region 1111 corresponding to the edge portion 1222.

[0192] In some embodiments, the back contact battery further includes a second transparent conductive layer 142, which is disposed on the side of the second doped semiconductor layer 132 away from the substrate 110 and is electrically connected to the second doped semiconductor layer 132.

[0193] The material of the second transparent conductive layer 142 includes at least one of indium tin oxide, tungsten-doped indium oxide, titanium-doped indium oxide, tin oxide, and aluminum-doped zinc oxide. The second transparent conductive layer 142 has light transmittance and conductivity, and has the functions of collecting and conducting current, as well as protecting the interface, which is beneficial to improving the photoelectric conversion efficiency and long-term stability of the back contact battery.

[0194] In some embodiments, the back contact battery further includes a first electrode 151, which is disposed on the side of the first transparent conductive layer 141 away from the first doped semiconductor layer 122, and the first electrode 151 does not contact the doped field region 123.

[0195] Since the first electrode 151 does not contact the doped field region 123, current can be collected using the first electrode 151 while also taking into account the passivation contact performance of the first region 1111.

[0196] In some embodiments, the back contact battery further includes a second electrode 152, which is disposed on the side of the second transparent conductive layer 142 away from the second doped semiconductor layer 132.

[0197] The second electrode 152 can be used to collect current.

[0198] In some embodiments, the back contact battery further includes a first passivation layer 161 and a first antireflection layer 162 disposed on the second surface 112.

[0199] The material of the first passivation layer 161 includes at least one of silicon oxide and aluminum oxide.

[0200] The first passivation layer 161 can reduce the minority carrier concentration of the second surface 112 by utilizing the passivation effect, suppress carrier recombination, and thereby improve the open-circuit voltage of the back contact battery.

[0201] The material of the first antireflective layer 162 includes at least one of silicon nitride or silicon oxynitride. The first antireflective layer 162 can reduce light reflection, increase light absorption, and improve the short-circuit current of the back contact battery.

[0202] This application also provides a method for preparing a back contact battery, including:

[0203] S10. Provide a substrate 110. The substrate 110 has a first surface 111, which includes alternating first regions 1111 and second regions 1112.

[0204] S20, an initial tunneling layer 1210 is formed on the first surface 111.

[0205] S30. A first semiconductor layer 1220 is formed on the side of the initial tunneling layer 1210 away from the substrate 110.

[0206] The deposition temperature of the first semiconductor layer 1220 can be 500℃-650℃.

[0207] For example, the deposition temperature of the first semiconductor layer 1220 is 500°C, 550°C, 600°C, or 650°C, etc.

[0208] The deposition temperature of the first semiconductor layer 1220 is set within a suitable range, such as 500℃-650℃. Under normal circumstances, this can improve the uniformity of the first semiconductor layer 1220 (when the first semiconductor layer 1220 is polycrystalline silicon, a suitable deposition temperature is conducive to the formation of fine-grained polycrystalline silicon), thereby giving the first doped semiconductor layer 122 good doping uniformity and good conductivity, which is beneficial to improving the passivation contact performance of the first region 1111.

[0209] S40, the first doped element is diffused to the first semiconductor layer 1220 to form an initial doped field region 1230 located at the first surface 111.

[0210] For example, the first dopant element is phosphorus.

[0211] Please refer to the following: Figure 4 The step of diffusing the first doped element into the first semiconductor layer 1220 includes:

[0212] S41, a phosphorus silica glass 170 is formed on the side of the first semiconductor layer 1220 away from the initial tunneling layer 1210.

[0213] S42, Phosphorus in the silicon phosphate glass 170 is diffused to the first semiconductor layer 1220.

[0214] Specifically, in the step of diffusing the first dopant element into the first semiconductor layer 1220, the diffusion temperature of the first dopant element is 700℃-1000℃, and the diffusion time of the first dopant element is 5min-60min.

[0215] For example, the diffusion temperature of the first dopant element is 700°C, 800°C, 900°C, or 1000°C, etc.

[0216] For example, the diffusion time of the first dopant element is 5 min, 10 min, 20 min, 40 min, or 60 min, etc.

[0217] A suitable diffusion temperature and a suitable diffusion time are beneficial for the diffusion of the first dopant element into the substrate 110, thereby increasing the doping concentration of the doped field region 123 and also improving the passivation contact performance of the first region 1111.

[0218] S50, a groove is formed on the second region 1112, and the portions of the initial tunneling layer 1210, the first semiconductor layer 1220, and the initial doped field region 1230 located in the second region 1112 are removed, resulting in a tunneling layer 121, a first doped semiconductor layer 122, and a doped field region 123. The depth of the doped field region 123 is less than the depth of the groove.

[0219] The step of forming a groove in the second region 1112 may include:

[0220] S51. A mask layer 180 is formed on the side of the phosphosilicate glass 170 away from the first semiconductor layer 1220.

[0221] S52, please refer to Figure 5 Using the mask layer 180, the portions of the phosphorus glass 170, the initial tunneling layer 1210, the first semiconductor layer 1220, and the initial doped field region 1230 that are not covered by the mask layer 180 are removed.

[0222] The second region 1112 and the second surface 112 of the first surface 111 can be textured using a first etching solution, so that the second region 1112 and the second surface 112 each have a textured structure. The portions of the initial tunneling layer 1210, the first semiconductor layer 1220, and the initial doped field region 1230 located in the second region 1112 can also be removed. During this process, the mask layer 180 and the retained phosphorus-silicon glass 170 can protect the first region 1111.

[0223] S53, please refer to the following: Figure 6The second region 1112 is etched with a second etching solution to form a groove in the second region 1112. The first etching solution and the second etching solution can be the same or different, and no specific limitation is made here.

[0224] In some embodiments, the first etchant and the second etchant are different. Using a second etchant that is different from the first etchant can make the size of the texture structure of the second region 1112 smaller than the size of the texture structure of the second surface 112, thereby improving the deposition uniformity of the subsequently deposited amorphous layer 131, thereby improving the density of the amorphous layer 131, thereby reducing the probability of the second dopant element diffusing to the substrate 110.

[0225] It should be noted that before the first doping element diffuses to the first semiconductor layer 1220, the substrate 110 is actually the initial substrate. That is, the first doping element used to dop the first semiconductor layer 1220 does not diffuse to the location in the initial substrate used to set the initial doping field region 1230.

[0226] In embodiments of this application, the method for preparing the back contact battery may further include:

[0227] S54, Remove the mask layer 180 and the phosphosilicate glass 170.

[0228] S55, please refer to Figure 6 A first passivation layer 161 is formed on the side of the second surface 112 away from the first surface 111.

[0229] S56. Please refer to the following: Figure 6 A first antireflection layer 162 is formed on the side of the first passivation layer 161 away from the substrate 110.

[0230] S57. Remove the antireflective material layer that is deposited synchronously with the first antireflective layer 162 and located on the first surface 111, and remove the passivation material layer that is deposited synchronously with the first passivation layer 161 and located on the first surface 111.

[0231] S60, an amorphous layer 131 is formed, and a second doped semiconductor layer 132 is formed on the side of the amorphous layer 131 away from the substrate 110. A portion of the amorphous layer 131 is disposed on the second region 1112, and another portion of the amorphous layer 131 is disposed on the side of the first doped semiconductor layer 122 away from the substrate 110. The second doped semiconductor layer 132 has a second doping element with a doping type different from that of the first doping element.

[0232] That is, a portion of the amorphous layer 131 is disposed on the second region 1112, and another portion of the amorphous layer 131 is disposed on the first region 1111.

[0233] For example, please refer to the following: Figure 7The steps of forming an amorphous layer 131 and forming a second doped semiconductor layer 132 disposed on the side of the amorphous layer 131 away from the substrate 110 include:

[0234] S61. An initial amorphous layer 1310 is formed on the first region 1111 and the second region 1112, respectively, and a second semiconductor layer 1320 is formed on the side of the initial amorphous layer 1310 away from the substrate 110. The second semiconductor layer 1320 includes a first portion located in the first region 1111, and the initial amorphous layer 1310 includes a second portion located in the first region 1111.

[0235] S62, Remove a portion of the first part and a portion of the second part to obtain an amorphous layer 131 and a second doped semiconductor layer 132.

[0236] In some embodiments, the deposition temperature of the initial amorphous layer 1310 is less than or equal to 200°C. Specifically, the deposition temperature of the initial amorphous layer 1310 may be greater than or equal to 100°C and less than or equal to 200°C.

[0237] For example, the deposition temperature of the initial amorphous layer 1310 is 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, or 200°C.

[0238] The initial amorphous layer 1310 is deposited at a lower temperature, which reduces the probability of the second dopant element diffusing into the substrate 110, thereby improving the passivation contact performance of the second region 1112.

[0239] In some embodiments, the deposition temperature of the second semiconductor layer 1320 is less than or equal to 200°C. Specifically, the deposition temperature of the second semiconductor layer 1320 may be greater than or equal to 100°C and less than or equal to 200°C.

[0240] For example, the deposition temperature of the second semiconductor layer 1320 is 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, or 200°C.

[0241] The second semiconductor layer 1320 is formed at a lower temperature, which reduces the probability of the second doped element diffusing to the substrate 110, thereby improving the passivation contact performance of the second region 1112.

[0242] The formation processes of the first transparent conductive layer 141, the first electrode 151, the second transparent conductive layer 142, and the second electrode 152 will not be described in detail.

[0243] In some embodiments, such as Figure 8As shown, the initial tunneling layer 1210 includes a tunneling portion 1211 located in a first region 1111 and a blocking portion 1212 located in a second region 1112. The density of the tunneling portion 1211 is less than the density of the blocking portion 1212.

[0244] The blocking portion 1212 corresponds to the portion of the initial tunnel layer 1210 located in the second region 1112.

[0245] The blocking part 1212 includes a dielectric material.

[0246] The blocking portion 1212 refers to the portion of the initial tunneling layer 1210 used to block the diffusion of the first doped element into the second region 1112.

[0247] The blocking portion 1212 can be used to reduce the probability of the first doped element diffusing into the second region 1112. Combined with the setting of the groove, the probability of the first doped element diffusing into the second region 1112 can be effectively reduced, thereby improving the passivation contact performance of the second region 1112.

[0248] In some embodiments, the tunneling portion 1211 is made of silicon dioxide, and the blocking portion 1212 includes an amorphous silicon layer and / or a microcrystalline silicon layer.

[0249] Thus, the amorphous silicon layer and the microcrystalline silicon layer have high density, which can effectively reduce the probability of the first dopant element diffusing into the second region 1112, thereby improving the passivation contact performance of the second region 1112.

[0250] This application also provides a photovoltaic module, which includes a back contact battery of any of the above embodiments or a back contact battery prepared by the preparation method of the back contact battery of any of the above embodiments.

[0251] Specifically, please refer to Figure 9 The photovoltaic module includes a cell string 10, an encapsulation layer 20, and a cover plate. The cell string 10 is formed by connecting the aforementioned back-contact cells. The encapsulation layer 20 covers the surface of the cell string 10. The cover plate covers the surface of the encapsulation layer 20 away from the cell string 10.

[0252] The encapsulation layer 20 may include a first encapsulating adhesive layer and a second encapsulating adhesive layer. The cover plate may include a first cover plate 31 and a second cover plate 32. Along the first direction F1, a portion of the first encapsulating adhesive layer is disposed on one side of the battery string 10, and a portion of the second encapsulating adhesive layer is disposed on the other side of the battery string 10. The first cover plate 31 is disposed on the side of the first encapsulating adhesive layer away from the battery string 10, and the second cover plate 32 is disposed on the side of the second encapsulating adhesive layer away from the battery string 10.

[0253] The materials of the first and second encapsulating layers can be at least one of ethylene-vinyl acetate copolymer (EVA) encapsulating layer, polyolefin elastomer (POE) encapsulating layer, or polyvinyl butyral (PVB) encapsulating layer.

[0254] The first cover plate 31 and the second cover plate 32 can be glass covers, plastic covers, or other covers with light-transmitting functions.

[0255] The photovoltaic module may also include a frame, a first cover plate 31, a first encapsulating layer, a cell string 10, a second encapsulating layer, and a second cover plate 32, which are laminated to form a laminate (during the lamination process, the first encapsulating layer and the second encapsulating layer are bonded to each other to form an encapsulation layer 20). The frame is arranged around the laminate, that is, the frame is arranged around the laminate. In this way, the frame can be used to protect the edges of the laminate, improve the overall mechanical strength of the photovoltaic module, and facilitate the transportation and installation of the photovoltaic module.

[0256] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above 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.

[0257] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A back-contact battery, characterized in that, include: The substrate has a first surface and a second surface disposed opposite to each other along a first direction; the first surface includes alternating first regions and second regions. A tunnel layer is located in the first region; A first doped semiconductor layer is disposed on the side of the tunneling layer away from the substrate; A doped field region is located in the first region; both the doped field region and the first doped semiconductor layer have a first doping element. An amorphous layer, wherein the second region has a groove recessed relative to the first region, a portion of the amorphous layer is disposed on the second region, and another portion of the amorphous layer is disposed on the side of the first doped semiconductor layer away from the substrate; and The second doped semiconductor layer is disposed on the side of the amorphous layer away from the substrate, and has a second doped element with a doping type different from that of the first doped element; The depth of the doped field region is less than the depth of the groove.

2. The back contact battery according to claim 1, characterized in that, The sum of the thickness of the tunneling layer, the thickness of the first doped semiconductor layer, and the depth of the doped field region is less than the depth of the groove.

3. The back contact battery according to claim 1, characterized in that, The ratio of the depth of the groove to the depth of the doped field region is 5-100.

4. The back contact battery according to claim 1, characterized in that, The depth of the doped field region is 100nm-1000nm.

5. The back contact battery according to claim 1, characterized in that, The depth of the groove is 1μm-10μm.

6. The back contact battery according to any one of claims 1-5, characterized in that, The doping concentration of the first doped element in the first doped semiconductor layer is greater than the doping concentration of the first doped element in the doped field region.

7. The back contact battery according to any one of claims 1-5, characterized in that, The doped field region includes a first doped sub-region and a second doped sub-region; along the first direction, the first doped sub-region is disposed closer to the first surface than the second doped sub-region; The doping concentration of the first dopant element in the first doped sub-region is greater than the doping concentration of the first dopant element in the second doped sub-region.

8. The back contact battery according to claim 7, characterized in that, The doped field region further includes a third doped sub-region located between the first doped sub-region and the second doped sub-region along the first direction; The doping concentration of the first dopant element in the first doped sub-region is greater than the doping concentration of the first dopant element in the third doped sub-region, and the doping concentration of the first dopant element in the third doped sub-region is greater than the doping concentration of the first dopant element in the second doped sub-region.

9. The back contact battery according to any one of claims 1-5, characterized in that, The doping concentration of the first dopant element in the tunneling layer is greater than the doping concentration of the first dopant element in the doped field region; and / or The doping concentration of the first dopant element in the tunneling layer is greater than the doping concentration of the first dopant element in the first doped semiconductor layer.

10. The back contact battery according to any one of claims 1-5, characterized in that, The ratio of the doping concentration of the first dopant element in the doped field region to the doping concentration of the second dopant element in the second doped semiconductor layer is 0.1-10.

11. The back contact battery according to any one of claims 1-5, characterized in that, The first doped semiconductor layer and the second doped semiconductor layer have different crystal phases.

12. The back contact battery according to any one of claims 1-5, characterized in that, The first doped semiconductor layer includes a central portion and edge portions located on both sides of the central portion; A portion of the amorphous layer is disposed on the side of the edge portion opposite to the substrate; The doping concentration of the first dopant element in the middle portion is greater than the doping concentration of the first dopant element in the edge portion.

13. The back contact battery according to any one of claims 1-5, characterized in that, The back contact battery also includes: A first transparent conductive layer is disposed on the side of the first doped semiconductor layer away from the substrate and is electrically connected to the first doped semiconductor layer; and / or A second transparent conductive layer is disposed on the side of the second doped semiconductor layer away from the substrate and is electrically connected to the second doped semiconductor layer.

14. The back contact battery according to claim 13, characterized in that, The back contact battery further includes a first electrode, which is disposed on the side of the first transparent conductive layer away from the first doped semiconductor layer, and the first electrode does not contact the doped field region.

15. The back contact battery according to any one of claims 1-5, characterized in that, The second region has a first pyramid-shaped structure, and the second face has a second pyramid-shaped structure; The size of the first pyramid-shaped structure is smaller than the size of the second pyramid-shaped structure.

16. The back contact battery according to any one of claims 1-5, characterized in that, The back contact battery also includes a first passivation layer and a first antireflection layer disposed on the second surface.

17. A method for preparing a back-contact battery, characterized in that, include: A substrate is provided; wherein the substrate has a first surface and a second surface disposed opposite to each other along a first direction, the first surface comprising alternating first regions and second regions; An initial tunneling layer is formed on the first surface; A first semiconductor layer is formed on the side of the initial tunneling layer away from the substrate; The first doping element is diffused into the first semiconductor layer to form an initial doped field region located on the first surface; A groove is formed in the second region, and the portions of the initial tunneling layer, the first semiconductor layer, and the initial doped field region located in the second region are removed to obtain the tunneling layer, the first doped semiconductor layer, and the doped field region. An amorphous layer is formed, and a second doped semiconductor layer is formed on the side of the amorphous layer away from the substrate; Wherein, a portion of the amorphous layer is disposed on the second region, and another portion of the amorphous layer is disposed on the side of the first doped semiconductor layer away from the substrate; The second doped semiconductor layer has a second doped element with a different doping type than the first doped element; The depth of the doped field region is less than the depth of the groove.

18. The method for preparing a back contact battery according to claim 17, characterized in that, In the step of diffusing the first dopant element into the first semiconductor layer, the diffusion temperature of the first dopant element is 700℃-1000℃; and / or, the diffusion time of the first dopant element is 5min-60min.

19. A photovoltaic module, characterized in that, Includes the back contact battery as described in any one of claims 1-16, or the back contact battery prepared by the method described in any one of claims 17-18.

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