Back contact battery, photovoltaic module and photovoltaic system

Abstract

The invention discloses a back contact cell, a photovoltaic module and a photovoltaic system.The back contact cell comprises first areas, second areas and isolation areas which are arranged on the shady face of a silicon substrate, the first areas and the second areas are alternately arranged, and the isolation areas are located between the first areas and the second areas; the first region comprises a first doped conductive layer, the second region comprises a second doped conductive layer, and the doping type of the first doped conductive layer is opposite to that of the second doped conductive layer; the side, close to the isolation area, of the first area is provided with a concave structure. According to the invention, efficient isolation of different doped regions on the back surface of the back contact cell can be realized, so that the photoelectric conversion efficiency of the back contact cell is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cells, and in particular to a back contact cell, a photovoltaic module and a photovoltaic system. Background Art

[0002] Interdigitated Back Contact (IBC) is a high-efficiency solar cell technology. The positive and negative metal electrodes of the IBC cell are arranged in a cross-finger manner on the backlight side of the cell. This design allows the front surface of the cell to be shielded by no metal grid lines, thereby maximizing the illuminated area and reducing optical losses, improving short-circuit current and overall photoelectric conversion efficiency. In order to prevent carriers from directly contacting the N-type doped region and the P-type doped region, resulting in the inability to effectively collect carriers, an isolation region needs to be set at the junction of the P-type doped region and the N-type doped region. As the size of the cell decreases, the N-type doped region and the P-type doped region are set more closely, and accordingly, the size of the isolation region is also reduced. However, if the isolation region is too narrow, it may not provide sufficient insulation protection, increasing the possibility of short circuits, thereby reducing the photoelectric conversion efficiency of the back contact cell. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a back contact cell, which can improve the isolation performance of different doping areas on the backlight surface of the back contact cell and the photoelectric conversion efficiency of the solar cell.

[0004] The technical problem to be solved by the present invention is also to provide a photovoltaic module including the above-mentioned back contact cell and a corresponding photovoltaic system.

[0005] In order to solve the above problems, the present invention discloses a back contact battery, comprising a first region, a second region and an isolation region arranged on the backlight surface of a silicon substrate, wherein the first region and the second region are arranged alternately, the isolation region is located between the first region and the second region, the first region includes a first doped conductive layer, the second region includes a second doped conductive layer, and the doping types of the first doped conductive layer and the second doped conductive layer are opposite;

[0006] A concave structure is provided on one side of the first region close to the isolation region.

[0007] As an improvement of the above technical solution, a discontinuous recessed structure is provided on one side of the first region close to the isolation region.

[0008] As an improvement of the above technical solution, a recessed structure is provided on one side of the second region close to the isolation region.

[0009] As an improvement of the above technical solution, a discontinuous recessed structure is provided on one side of the second region close to the isolation region.

[0010] As an improvement of the above technical solution, the recessed structure includes a first unit area and a first recessed structure, the first unit area is arranged around the first recessed structure, and the first recessed structure includes a pit and a protrusion arranged in the pit.

[0011] As an improvement of the above technical solution, the height of the protrusion is less than or equal to the depth of the pit.

[0012] As an improvement of the above technical solution, the shape of the protrusion includes a pyramid shape and / or a prism shape.

[0013] As an improvement of the above technical solution, the silicon substrate includes a light-facing surface and a backlight surface that are relatively arranged. Along the direction from the light-facing surface to the backlight surface, the protrusion includes a silicon substrate and a passivation layer, and the sidewall of the pit includes a passivation layer.

[0014] As an improvement of the above technical solution, along the direction from the light-facing surface to the backlight surface, the first unit area includes a silicon substrate, a tunneling layer, a doped conductive layer, and a passivation layer, and the silicon substrate, tunneling layer, doped conductive layer, and passivation layer are stacked in sequence.

[0015] As an improvement of the above technical solution, the passivation layer includes one or more of an aluminum oxide layer, a silicon nitride layer, a silicon oxide layer, and a silicon oxynitride layer.

[0016] As an improvement of the above technical solution, the tunneling layer includes one or more of a silicon oxide layer, a silicon carbide layer, a silicon nitride layer, and an aluminum oxide layer.

[0017] As an improvement of the above technical solution, the width of the bottom of the protrusion is 0.1 μm to 1.5 μm, and the height of the protrusion is 0.01 μm to 10 μm.

[0018] As an improvement of the above technical solution, the width of the pit opening is 0.1 μm to 2 μm, and the depth of the pit is 0.01 μm to 10 μm.

[0019] As an improvement of the above technical solution, the first doped conductive layer includes an extension portion extending and protruding above the isolation region;

[0020] The recessed structure includes a second unit area and a second recessed structure, the second unit area is arranged around the second recessed structure, and the second recessed structure penetrates the extension portion to form a hole.

[0021] As an improvement of the above technical solution, the back contact battery includes a passivation layer surrounding the extension portion, and the second recessed structure penetrates the extension portion and the passivation layer to form a hole.

[0022] As an improvement of the above technical solution, the width of the hole is 0.1 μm to 1.5 μm.

[0023] As an improvement of the above technical solution, the plurality of recessed structures form an isolation transition zone, and the width of the isolation transition zone is 5 μm to 30 μm.

[0024] As an improvement of the above technical solution, the width of the isolation transition zone is 10 μm to 15 μm.

[0025] As an improvement of the above technical solution, when the silicon substrate is an N-type silicon substrate, the first region is a P-type doped region, the second region is an N-type doped region, and n1 recessed structures are provided on the side of the P-type doped region close to the isolation region, and n2 recessed structures are provided on the side of the N-type doped region close to the isolation region, and n1≥n2.

[0026] As an improvement of the above technical solution, when the silicon substrate is a P-type silicon substrate, the first region is an N-type doped region, the second region is a P-type doped region, and n1 recessed structures are provided on the side of the P-type doped region close to the isolation region, and n2 recessed structures are provided on the side of the N-type doped region close to the isolation region, and n1≤n2.

[0027] As an improvement of the above technical solution, the back contact battery further includes a front passivation layer, a first electrode and a second electrode;

[0028] The front passivation layer is stacked on the front side of the silicon substrate;

[0029] The first electrode contacts the first doped conductive layer, and the second electrode contacts the second doped conductive layer.

[0030] Correspondingly, the present invention also discloses a method for preparing the above-mentioned back contact battery, comprising:

[0031] Providing a silicon substrate;

[0032] Forming a first doped conductive layer at least in a first region of the backlight surface of the silicon substrate, and forming a recessed structure on a surface of the first region;

[0033] forming a second doped conductive layer at least in the second region;

[0034] An isolation region is formed between the first region and the second region.

[0035] As an improvement of the above technical solution, the method for preparing the back contact battery includes:

[0036] Providing a silicon substrate;

[0037] Forming a first doped conductive layer at least in a first region of the backlight surface of the silicon substrate, and forming a recessed structure on a surface of the first region;

[0038] forming a second doped conductive layer at least in the second region, and forming a recessed structure on a surface of the second region;

[0039] An isolation region is formed between the first region and the second region.

[0040] As a possible manner, the recessed structure may be formed by laser direct etching and / or wet etching.

[0041] Correspondingly, the present invention also discloses a photovoltaic module, comprising the above-mentioned back contact cell.

[0042] Correspondingly, the present invention also discloses a photovoltaic system, including the above-mentioned photovoltaic module.

[0043] The implementation of the present invention has the following beneficial effects:

[0044] 1. The present invention sets a concave structure on the side of the first area of ​​the backlight surface of the back contact battery close to the isolation area to improve the isolation effect of the isolation area on the first area and the second area. In addition, the concave structure increases the contact area between the first area and the subsequently grown passivation layer, thereby improving the passivation effect.

[0045] 2. The present invention sets a concave structure on the side of the second area of ​​the backlight surface of the back contact battery close to the isolation area to improve the isolation effect of the isolation area on the first area and the second area. In addition, the concave structure increases the contact area between the second area and the subsequently grown passivation layer, thereby improving the passivation effect.

[0046] 3. The first recessed structure of the present invention includes a pit and a protrusion arranged in the pit. The bottom of the pit is formed on the silicon substrate, which can improve the isolation effect between the first area and the second area. The setting of the protrusion further increases the contact area with the subsequently deposited passivation layer, and the overall passivation performance is further improved.

[0047] 4. The first region of the present invention has an extension portion extending and protruding above the isolation region at the edge of the isolation region, thereby forming an isolation region with a small opening and a large interior, reducing the exchange of plasma with the outside world during the subsequent deposition of the passivation layer; a second recessed structure is provided in the extension portion, and the second recessed structure runs through the extension portion to increase the isolation and passivation performance of the extension portion. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 is a schematic structural diagram of a back contact battery provided by the present invention;

[0049] Figure 2 is a 3D micrograph of the backlight surface of the back contact battery provided by the present invention;

[0050] Figure 3 is a structural schematic diagram of a first recessed structure provided by an embodiment of the present invention;

[0051] Figure 4 is a schematic diagram of the dimensions of a first recessed structure provided in an embodiment of the present invention;

[0052] Figure 5 is a structural schematic diagram of a second recessed structure provided by an embodiment of the present invention;

[0053] Figure 6 is an electron microscope image of a concave structure provided by an embodiment of the present invention;

[0054] Figure 7 It is an electron microscope image of the first recessed structure provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0055] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is described in further detail below.

[0056] See also Figure 1 The present invention provides a back contact battery, comprising a first region 13, a second region 14 and an isolation region 15 arranged on a backlight surface 11 of a silicon substrate 1, wherein the first region 13 and the second region 14 are arranged alternately, wherein the first region 13 comprises a first doped conductive layer 161, and the second region 14 comprises a first doped conductive layer 162, and the doping types of the first doped conductive layer 161 and the second doped conductive layer 162 are opposite. Specifically, the first doped conductive layer may be opposite to or the same as the doping type of the silicon substrate, and the second doped conductive layer and the first doped conductive layer have opposite conductivity types, so that the backlight side of the back contact battery has a first region and a second region of opposite conductivity types, and an isolation region is arranged between the first region and the second region of opposite conductivity types, and the first region and the second region of opposite conductivity types are spaced apart to prevent the first region and the second region from contacting and causing a short circuit.

[0057] A recessed structure 17 is disposed on one side of the first region 13 close to the isolation region 15 .

[0058] Compared with the existing method of setting an isolation region between the first region and the second region, the present invention further provides a recessed structure on one side of the first region close to the isolation region, and the provision of the recessed structure can further increase the isolation between the first region and the second region. Due to the current reduction in battery structure, the interval between the first region and the second region with different doping types is also set to be smaller and smaller, and the requirements for the isolation region between the first region and the second region are also getting higher and higher. The provision of the recessed structure can increase the isolation effect of the first region and the second region under the condition of the same isolation region width. The provision of the recessed structure can also improve the light absorption effect, reduce the reflectivity of light, and more light generates carriers in the silicon substrate, thereby improving the photoelectric conversion efficiency of the battery. In addition, the provision of the recessed structure also increases the contact area between the first region and the passivation layer subsequently deposited on its surface, thereby improving the surface passivation effect of the passivation layer on the first region, and further improving the photoelectric conversion efficiency of the back contact battery.

[0059] In a preferred embodiment, Figure 2 As shown, a discontinuous recessed structure 17 is provided on one side of the first region 13 close to the isolation region 15, and a plurality of discontinuous recessed structures form an isolation transition region 171. The discontinuous distribution of the recessed structures can further improve the isolation effect between the first region and the second region. Specifically, the width L of the isolation transition region can be set at 5μm to 30μm, exemplarily 6μm, 8μm, 10μm, 15μm, 20μm or 25μm, but not limited thereto. More preferably, the width L of the isolation transition region is 10μm to 15μm. By controlling the width range of the isolation transition region, while improving the isolation performance, it will not adversely affect the performance of the first region and the second region itself, thereby ensuring the collection and transmission effect of carriers.

[0060] Correspondingly, a recessed structure may also be provided on the side of the second region 14 close to the isolation region 15, and the function of the recessed structure is the same as that of the recessed structure on the side of the first region 13 close to the isolation region 15. In a preferred embodiment, a discontinuous recessed structure is provided on the side of the second region close to the isolation region, and similarly, a plurality of discontinuous recessed structures form an isolation transition region, and the width of the isolation transition region is 5 μm to 30 μm, and more preferably, the width of the isolation transition region is 10 μm to 15 μm.

[0061] Specifically, Figure 3 , Figure 6 and Figure 7As shown, the recessed structure 17 includes a first unit region 172 and a first recessed structure 173, the first unit region 172 is arranged around the first recessed structure 173, the first recessed structure 173 includes a pit 174 and a protrusion 175 arranged in the pit 174. Specifically, the silicon substrate 1 includes a light-facing surface 11 and a backlight surface 12 arranged opposite to each other, along the direction from the light-facing surface to the backlight surface, the protrusion 175 includes a silicon substrate 1 and a passivation layer 18, the sidewall of the pit 174 includes the passivation layer 18, the first unit region 172 includes a silicon substrate 1, a tunneling layer 19, a doped conductive layer 16, and a passivation layer 18, and the silicon substrate 1, the tunneling layer 19, the doped conductive layer 16, and the passivation layer 18 are stacked in sequence. It should be noted that, on the first region, the doped conductive layer included in the first unit region is a first doped conductive layer, and on the second region, the doped conductive layer included in the first unit region is a second doped conductive layer. By forming a first recessed structure in the first region and / or the second region, and setting the bottom of the pit of the first recessed structure to the silicon substrate, the isolation effect between the first region and the second region can be improved, and then a passivation layer is covered on the first recessed structure. The setting of the protrusion further increases the contact area between the passivation layer and the first region and / or the second region, and the overall passivation performance is further improved.

[0062] The provision of the passivation layer can reduce the recombination of surface carriers. The passivation layer 18 covers the first region 13, the first region 14 and the isolation region 15. The passivation layer can passivate the side of the first doped conductive layer and the second doped conductive layer away from the silicon substrate, reduce the carrier recombination rate of the first doped conductive layer and the second doped conductive layer away from the silicon substrate, and further improve the photoelectric conversion efficiency of the back contact battery. The passivation layer can be one or more of an aluminum oxide layer, a silicon nitride layer, a silicon oxide layer, and a silicon oxynitride layer. Preferably, the passivation layer includes an aluminum oxide layer and a silicon nitride layer stacked in sequence.

[0063] The tunneling layer can be divided into a first tunneling layer and a second tunneling layer; the first tunneling layer is arranged between the silicon substrate in the first region and the first doped conductive layer; the second tunneling layer is arranged between the silicon substrate in the second region and the second doped conductive layer, the first tunneling layer and the second tunneling layer allow the majority carriers to tunnel into the first doped conductive layer while blocking the minority carriers from passing through, and then the majority carriers are transmitted through the first doped conductive layer and the second doped conductive layer and collected by the corresponding electrodes, reducing the recombination rate of carriers of different conductivity types at the surface of the first region or the second region, achieving excellent selective collection of carriers, and further improving the photoelectric conversion efficiency of the back contact battery. The first tunneling layer and the second tunneling layer can be one or more of a silicon oxide layer, a silicon carbide layer, a silicon nitride layer, and an aluminum oxide layer. Preferably, the first tunneling layer and the second tunneling layer are silicon oxide layers.

[0064] In a preferred embodiment, the height of the protrusion is less than or equal to the depth of the pit. More preferably, the height of the protrusion is less than the depth of the pit, which facilitates the subsequent deposition of the passivation layer. Specifically, the shape of the protrusion can be pyramidal and / or prism-shaped.

[0065] Understandably, the size of the protrusions and pits will also have a certain impact on the isolation effect and passivation performance, such as Figure 4 As shown, the width D1 of the bottom of the protrusion is 0.1μm to 1.5μm, and the height of the protrusion H1 is 0.01μm to 10μm. If H1 is less than 0.01μm, it is easy to cause a short circuit and reduce the yield; if H1 is greater than 10μm, it will affect the coverage of the subsequent passivation layer, thereby reducing the passivation effect. The width D2 at the opening of the pit is 0.1μm to 2μm, and the depth H2 of the pit is 0.01μm to 10μm. If D2 is less than 0.1μm, it will affect the passivation effect; if D2 is greater than 10μm, there will be copper residues, causing leakage. H2 that is too large or too small will affect the passivation effect. If H2 is less than 0.01μm, the hydrogen passivation of the silicon substrate by the subsequently deposited passivation layer will be weakened, reducing the yield; if H2 is greater than 10μm, the recombination of carriers on the surface of the silicon substrate is increased. By limiting the size of the protrusions and pits, the passivation performance and isolation performance of the battery can be improved without causing adverse effects on the collection and transmission of carriers. Moreover, controlling the size of the pits and protrusions within the scope of the present invention is conducive to the subsequent formation of a back passivation layer. The passivation layer can be completely filled into the first recessed structure, thereby improving the film formation quality of the passivation layer.

[0066] like Figure 5 and Figure 6 As shown, the first doped conductive layer 161 includes an extension portion 163 extending and protruding above the isolation region; the recessed structure 17 includes a second unit region 176 and a second recessed structure 177, the second unit region 176 is arranged around the second recessed structure 177, and the second recessed structure 177 passes through the extension portion 163 to form a hole 178.

[0067] In a preferred embodiment, the back contact battery includes a passivation layer 18 surrounding the extension portion 163, and the second recessed structure 177 penetrates the extension portion 163 and the passivation layer 18 to form a hole. The passivation layer surrounds the extension portion to further ensure the passivation performance. In an embodiment, the width D3 of the hole is 0.1μm to 1.5μm, and is exemplarily 0.2μm, 0.5μm, 0.8μm, 1μm, 1.1μm or 1.4μm, but is not limited thereto.

[0068] In addition to the above structure, the back contact battery also includes a front passivation layer, a first electrode and a second electrode. The front passivation layer is stacked on the front of the silicon substrate, and the front is not affected by the metal electrode shielding; the first electrode penetrates the passivation layer and contacts the first doped conductive layer, and the second electrode penetrates the passivation layer and contacts the second doped conductive layer. The materials of the first electrode and the second electrode can be one or more of silver, aluminum, copper, and nickel.

[0069] In a preferred embodiment, the number of recessed structures on one side of the doping region with a different doping type from the silicon substrate is greater than or equal to the number of recessed structures on the side with the same doping type as the silicon substrate, which improves the liquid diversion effect in subsequent processes and is beneficial to the cleaning of impurities such as metals, thereby improving the surface quality of the recessed structures; in addition, a greater number of recessed structures of the emitter is beneficial to current collection. It can be understood that when the silicon substrate is a P-type silicon substrate, the first doping region is an N-type doping region, the second doping region is a P-type doping region, and the side of the P-type doping region close to the isolation region is provided with n1 recessed structures, and the side of the N-type doping region close to the isolation region is provided with n2 recessed structures, n1≤n2, preferably, n1<n2. That is to say, when the silicon substrate is a P-type silicon substrate, the number of recessed structures on the side of the P-type doping region close to the isolation region is less than or equal to the number of recessed structures on the side of the N-type doping region. Correspondingly, when the silicon substrate is an N-type silicon substrate, the first doped region is a P-type doped region, the second doped region is an N-type doped region, and n1 recessed structures are provided on the side of the P-type doped region close to the isolation region, and n2 recessed structures are provided on the side of the N-type doped region close to the isolation region, n1≥n2, preferably, n1>n2. That is to say, when the silicon substrate is an N-type silicon substrate, the number of recessed structures on the side of the P-type doped region close to the isolation region is greater than or equal to the number of recessed structures on the side of the N-type doped region, the P-type doped region is an emitter, and setting more recessed structures in the P-type doped region is conducive to current collection.

[0070] Accordingly, the present invention also provides a method for preparing the above-mentioned back contact battery, comprising:

[0071] S1, providing a silicon substrate;

[0072] Specifically, the silicon substrate may be an N-type silicon substrate or a P-type silicon substrate, and the backlight surface of the silicon substrate has first regions and second regions that are alternately arranged.

[0073] S2, forming a first doped conductive layer at least in a first region of the backlight surface of the silicon substrate, and forming a recessed structure on a surface of the first region;

[0074] The first doped conductive layer may be disposed in or on the silicon substrate. Preferably, a first tunneling layer and a first doped conductive layer are disposed in a first region on the backlight surface of the silicon substrate. The first doped conductive layer may be a P-type doped conductive layer or an N-type doped conductive layer.

[0075] In a preferred embodiment, a first tunneling layer and a first doped conductive layer are formed on the backlight surface of the silicon substrate, and at least a portion of the first tunneling layer located on the second area is processed to remove at least a portion of the first tunneling layer located on the second area, and the processing is performed by laser direct etching and wet etching. After the processing, a recessed structure is formed on the surface of the first doped conductive layer.

[0076] S3, forming a second doped conductive layer at least in the second region;

[0077] The second doped conductive layer may be disposed in or on the silicon substrate. Preferably, a second tunneling layer and a second doped conductive layer are disposed in a second region on the backlight surface of the silicon substrate, and the second doped conductive layer has a doping type opposite to that of the first doped conductive layer.

[0078] In a preferred embodiment, a second tunneling layer and a second doped conductive layer are formed on the backlight surface of the silicon substrate and the first doped conductive layer, and at least a portion of the second tunneling layer located on the first doped conductive layer is processed to at least remove a portion of the second tunneling layer located on the first doped conductive layer, and the processing is performed by laser direct etching and wet etching. After the processing, a recessed structure is formed on the surface of the first doped conductive layer.

[0079] S4. Form an isolation region between the first region and the second region.

[0080] In a preferred embodiment, a portion of the second tunneling layer located between the first region and the second region is processed to remove the portion of the second tunneling layer located between the first region and the second region to form an isolation region, and the processing adopts laser direct etching and wet etching. After the processing, a recessed structure is formed on the surface of the second doped conductive layer.

[0081] Subsequently, a passivation layer is deposited on the first doped conductive layer, the second doped conductive layer and the isolation region to form a first electrode in contact with the first doped conductive layer and a second electrode in contact with the second doped conductive layer.

[0082] The present invention will be further described below with specific embodiments:

[0083] Example 1

[0084] This embodiment provides a back contact battery, including a P-type doped region, an N-type doped region and an isolation region arranged on the back of an N-type silicon substrate, the P-type doped region and the N-type doped region are arranged alternately, the isolation region is located between the P-type doped region and the N-type doped region, the P-type doped region includes a P-type doped conductive layer, and the N-type doped region includes an N-type doped conductive layer. A recessed structure is provided on one side of the P-type doped region close to the isolation region.

[0085] The recessed structure includes a first recessed structure and a first unit region arranged around the first recessed structure, and the first recessed structure includes a pit and a protrusion arranged in the pit. Specifically, in the direction from the light-facing surface of the silicon substrate to the backlight surface, the protrusion includes a silicon substrate and a passivation layer, and the sidewall of the pit includes a passivation layer. The first unit region includes a silicon substrate, a tunneling layer, a P-type doped conductive layer, and a passivation layer stacked in sequence. The width of the bottom of the protrusion is 0.1μm to 1.5μm, the height of the protrusion is 0.01μm to 10μm, the width at the opening of the pit is 0.1μm to 2μm, the depth of the pit is 0.01μm to 10μm, and the shape of the protrusion is pyramid-shaped.

[0086] Example 2

[0087] This embodiment provides a back contact battery, including a P-type doped region, an N-type doped region and an isolation region arranged on the back of an N-type silicon substrate, the P-type doped region and the N-type doped region are arranged alternately, the isolation region is located between the P-type doped region and the N-type doped region, the P-type doped region includes a P-type doped conductive layer, and the N-type doped region includes an N-type doped conductive layer. A recessed structure is provided on one side of the P-type doped region close to the isolation region.

[0088] The recessed structure includes a first recessed structure and a first unit region arranged around the first recessed structure, and the first recessed structure includes a pit and a protrusion arranged in the pit. Specifically, in the direction from the light-facing surface of the silicon substrate toward the backlight surface, the protrusion includes a silicon substrate and a passivation layer, and the sidewall of the pit includes a passivation layer. The first unit region includes a silicon substrate, a tunneling layer, a P-type doped conductive layer, and a passivation layer stacked in sequence. The width of the bottom of the protrusion is 0.3μm to 1.2μm, the height of the protrusion is 0.05μm to 2μm, the width at the opening of the pit is 0.5μm to 2μm, the depth of the pit is 0.1μm to 5μm, and the shape of the protrusion is pyramid-shaped.

[0089] Example 3

[0090] This embodiment provides a back contact battery, including a P-type doped region, an N-type doped region and an isolation region arranged on the back of an N-type silicon substrate, the P-type doped region and the N-type doped region are arranged alternately, the isolation region is located between the P-type doped region and the N-type doped region, the P-type doped region includes a P-type doped conductive layer, and the N-type doped region includes an N-type doped conductive layer. A recessed structure is provided on one side of the P-type doped region close to the isolation region.

[0091] The recessed structure includes a first recessed structure and a first unit region arranged around the first recessed structure, and the first recessed structure includes a pit and a protrusion arranged in the pit. Specifically, in the direction from the light-facing surface of the silicon substrate toward the backlight surface, the protrusion includes a silicon substrate and a passivation layer, and the sidewall of the pit includes a passivation layer. The first unit region includes a silicon substrate, a tunneling layer, a P-type doped conductive layer, and a passivation layer stacked in sequence. The width of the bottom of the protrusion is 0.3μm to 1.2μm, the height of the protrusion is 0.05μm to 2μm, the width at the opening of the pit is 0.5μm to 2μm, the depth of the pit is 0.1μm to 5μm, and the shape of the protrusion is pyramid-shaped.

[0092] The P-type doped conductive layer includes an extension portion extending and protruding above the isolation region. The recessed structure also includes a second recessed structure and a second unit region arranged around the second recessed structure. The second recessed structure penetrates the extension portion to form a hole. The width of the hole is 0.1μm to 1.5μm.

[0093] Example 4

[0094] This embodiment provides a back contact battery, including a P-type doped region, an N-type doped region and an isolation region arranged on the back of an N-type silicon substrate, the P-type doped region and the N-type doped region are arranged alternately, the isolation region is located between the P-type doped region and the N-type doped region, the P-type doped region includes a P-type doped conductive layer, and the N-type doped region includes an N-type doped conductive layer. A recessed structure is provided on one side of the P-type doped region close to the isolation region.

[0095] The recessed structure includes a first recessed structure and a first unit region arranged around the first recessed structure, and the first recessed structure includes a pit and a protrusion arranged in the pit. Specifically, in the direction from the light-facing surface of the silicon substrate toward the backlight surface, the protrusion includes a silicon substrate and a passivation layer, and the sidewall of the pit includes a passivation layer. The first unit region includes a silicon substrate, a tunneling layer, a P-type doped conductive layer, and a passivation layer stacked in sequence. The width of the bottom of the protrusion is 0.3μm to 1.2μm, the height of the protrusion is 0.05μm to 2μm, the width at the opening of the pit is 0.5μm to 2μm, the depth of the pit is 0.1μm to 5μm, and the shape of the protrusion is pyramid-shaped.

[0096] The P-type doped conductive layer includes an extension portion extending and protruding above the isolation region. The recessed structure also includes a second recessed structure and a second unit region arranged around the second recessed structure. The second recessed structure penetrates the extension portion to form a hole. The width of the hole is 0.5μm to 0.8μm.

[0097] Example 5

[0098] The present embodiment provides a back-contact battery, including a P-type doped region, an N-type doped region and an isolation region arranged on the back side of an N-type silicon substrate, the P-type doped region and the N-type doped region are alternately arranged, the isolation region is located between the P-type doped region and the N-type doped region, the P-type doped region includes a P-type doped conductive layer, and the N-type doped region includes an N-type doped conductive layer.

[0099] A recessed structure is provided on one side of the P-type doping region close to the isolation region.

[0100] The recessed structure includes a first recessed structure and a first unit region arranged around the first recessed structure, and the first recessed structure includes a pit and a protrusion arranged in the pit. Specifically, in the direction from the light-facing surface of the silicon substrate toward the backlight surface, the protrusion includes a silicon substrate and a passivation layer, and the sidewall of the pit includes a passivation layer. The first unit region includes a silicon substrate, a tunneling layer, a P-type doped conductive layer, and a passivation layer stacked in sequence. The width of the bottom of the protrusion is 0.3μm to 1.2μm, the height of the protrusion is 0.05μm to 2μm, the width at the opening of the pit is 0.5μm to 2μm, the depth of the pit is 0.1μm to 5μm, and the shape of the protrusion is pyramid-shaped.

[0101] The P-type doped conductive layer includes an extension portion extending and protruding above the isolation region. The recessed structure also includes a second recessed structure and a second unit region arranged around the second recessed structure. The second recessed structure penetrates the extension portion to form a hole. The width of the hole is 0.5μm to 0.8μm.

[0102] A first recessed structure is also provided on one side of the N-type doping region close to the isolation region. The number of the first recessed structures in the N-type doping region is less than the number of the first recessed structures in the P-type doping region. The rest is the same as in Embodiment 1.

[0103] The back contact cells prepared in Examples 1 to 5 were subjected to printed electrodes, sintered and alloyed, and then annealed to obtain finished solar cells. The photoelectric conversion efficiency of the finished solar cells was measured, and the results are shown in the following table.

[0104] Photoelectric conversion efficiency Example 1 26.68％ Example 2 26.72％ Example 3 26.75％ Example 4 26.77％ Example 5 26.79％

[0105] The above is a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A back contact battery, characterized in that: The method comprises a first region, a second region and an isolation region arranged on a backlight surface of a silicon substrate, wherein the first region and the second region are arranged alternately, the isolation region is located between the first region and the second region, the first region comprises a first doped conductive layer, the second region comprises a second doped conductive layer, and the doping types of the first doped conductive layer and the second doped conductive layer are opposite; A concave structure is provided on one side of the first region close to the isolation region.

2. The back contact cell according to claim 1, characterized in that A discontinuous recessed structure is provided on one side of the first region close to the isolation region.

3. The back contact cell according to claim 1, characterized in that A concave structure is provided on one side of the second region close to the isolation region.

4. The back contact cell according to claim 3, characterized in that A discontinuous recessed structure is provided on one side of the second region close to the isolation region.

5. The back contact battery according to any one of claims 1 to 4, characterized in that: The recessed structure includes a first unit area and a first recessed structure, the first unit area is arranged around the first recessed structure, and the first recessed structure includes a pit and a protrusion arranged in the pit.

6. The back contact cell according to claim 5, characterized in that The height of the protrusion is less than or equal to the depth of the pit.

7. The back contact cell according to claim 5, characterized in that The shape of the protrusions includes a pyramid shape and / or a prism shape.

8. The back contact cell according to claim 5, characterized in that The silicon substrate comprises a light-facing surface and a backlight surface which are arranged opposite to each other. In the direction from the light-facing surface to the backlight surface, the protrusion comprises a silicon substrate and a passivation layer, and the sidewall of the pit comprises a passivation layer.

9. The back contact cell according to claim 8, characterized in that Along the direction from the light-facing surface to the backlight surface, the first unit region includes a silicon substrate, a tunneling layer, a doped conductive layer, and a passivation layer, and the silicon substrate, the tunneling layer, the doped conductive layer, and the passivation layer are stacked in sequence.

10. The back contact cell according to claim 9, characterized in that The passivation layer includes one or more of an aluminum oxide layer, a silicon nitride layer, a silicon oxide layer, and a silicon oxynitride layer.

11. The back contact cell according to claim 9, characterized in that The tunneling layer includes one or more of a silicon oxide layer, a silicon carbide layer, a silicon nitride layer, and an aluminum oxide layer.

12. The back contact cell according to claim 5, characterized in that The width of the bottom of the protrusion is 0.1 μm to 1.5 μm, and the height of the protrusion is 0.01 μm to 10 μm.

13. The back contact cell according to claim 5, characterized in that The width of the pit opening is 0.1 μm to 2 μm, and the depth of the pit is 0.01 μm to 10 μm.

14. The back contact battery according to any one of claims 1 to 4, characterized in that: The first doped conductive layer includes an extension portion extending and protruding above the isolation region; The recessed structure includes a second unit area and a second recessed structure, the second unit area is arranged around the second recessed structure, and the second recessed structure penetrates the extension portion to form a hole.

15. The back contact cell according to claim 14, characterized in that The back contact battery includes a passivation layer surrounding the extension portion, and the second recessed structure penetrates the extension portion and the passivation layer to form a hole.

16. The back contact cell according to claim 15, characterized in that The width of the hole is 0.1 μm to 1.5 μm.

17. The back contact cell according to claim 2 or 4, characterized in that: The plurality of recessed structures form an isolation transition region, and the width of the isolation transition region is 5 μm to 30 μm.

18. The back contact cell according to claim 17, characterized in that The width of the isolation transition zone is 10 μm to 15 μm.

19. The back contact cell according to claim 1, characterized in that When the silicon substrate is an N-type silicon substrate, the first region is a P-type doped region, the second region is an N-type doped region, n1 recessed structures are provided on one side of the P-type doped region close to the isolation region, and n2 recessed structures are provided on one side of the N-type doped region close to the isolation region, and n1≥n2.

20. The back contact cell according to claim 1, characterized in that When the silicon substrate is a P-type silicon substrate, the first region is an N-type doped region, the second region is a P-type doped region, n1 recessed structures are provided on one side of the P-type doped region close to the isolation region, and n2 recessed structures are provided on one side of the N-type doped region close to the isolation region, and n1≤n2.

21. A photovoltaic module, characterized in that: Comprising a back contact battery as claimed in any one of claims 1 to 20.

22. A photovoltaic system, characterized in that: Comprising the photovoltaic module as claimed in claim 21.

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