Back contact battery, manufacturing method thereof and photovoltaic module

Abstract

The invention discloses a back contact battery, a manufacturing method thereof and a photovoltaic module, relates to the technical field of photovoltaic, and aims to enable the back contact battery to have a relatively low hot spot risk and improve the working reliability of the back contact battery. And meanwhile, the back contact battery has relatively high working efficiency in a forward voltage region. A back contact cell includes a semiconductor substrate, a first doped semiconductor portion, a second doped semiconductor portion, and a transparent conductive layer. In the reverse electric leakage area, the part, extending into the overlapping area from the second area, of the transparent conductive layer is a first transparent conductive part, and the first transparent conductive part is electrically connected with the first doped semiconductor part through the second doped semiconductor part. The width of the first transparent conductive part in the first direction is W1, the width of the overlapping area in the first direction is W2, and the ratio of W1 to W2 is larger than or equal to 10% and smaller than or equal to 90%.

Description

[0001] This application claims the priority of the Chinese patent filed with the China Patent Office on June 18, 2024, with application number 202410788218.1 and invention name “A back contact battery and its manufacturing method, photovoltaic module”, all contents of which are incorporated by reference in this application. Technical Field

[0002] The present invention relates to the technical field of photovoltaic modules, and in particular to a back contact cell and a manufacturing method thereof, and a photovoltaic module. Background Art

[0003] A back-contact cell refers to a solar cell in which the light-facing side of the cell has no electrode, and the positive and negative electrodes are arranged on the backlight side of the cell. This can reduce the shading of the electrode to the cell, increase the short-circuit current of the cell, and improve the energy conversion efficiency of the cell.

[0004] In actual use, bird droppings, leaves, sand and dust may fall onto the back-contact battery. The temperature of the battery cell will rise after being blocked, resulting in a hot spot effect. If the temperature of the hot spot exceeds a certain temperature value, it will cause problems such as delamination of the photovoltaic module, burning of the back panel, and cracking of the glass, thus causing the entire solar cell to be scrapped, and in severe cases, it may cause a fire risk. Summary of the invention

[0005] The object of the present invention is to provide a back contact cell and a manufacturing method thereof, and a photovoltaic module.

[0006] In order to achieve the above-mentioned purpose, in a first aspect, the present invention provides a back contact battery. The back contact battery comprises: a semiconductor substrate, a first doped semiconductor part, a second doped semiconductor part and a transparent conductive layer. The conductivity types of the second doped semiconductor part and the first doped semiconductor part are opposite. The semiconductor substrate comprises a first surface and a second surface opposite to each other. The first surface comprises a first region and a second region, and an overlapping region between the first region and the second region. Moreover, the first region, the overlapping region, and the second region are arranged along a first direction. The first doped semiconductor part is arranged in the first region and the overlapping region. The second doped semiconductor part is arranged on the second region and extends to cover the first doped semiconductor part of the overlapping region. The transparent conductive layer covers the second doped semiconductor part and the first doped semiconductor part. An insulating groove is provided in the transparent conductive layer to physically insulate the part of the transparent conductive layer corresponding to the first region from the part of the transparent conductive layer corresponding to the second region. Among them, at least part of the overlapping region is a reverse leakage region. Moreover, in the reverse leakage region, the part of the transparent conductive layer extending from the second region into the overlapping region is the first transparent conductive part, and the first transparent conductive part is electrically connected to the first doped semiconductor part through the second doped semiconductor part. The width of the first transparent conductive portion in the first direction is W1, the width of the overlapping region in the first direction is W2, and the ratio of W1 to W2 is greater than or equal to 10% and less than or equal to 90%.

[0007] In the case of adopting the above technical solution, when the back contact battery is in working state, the above first doped semiconductor part and the second doped semiconductor part can effectively shunt carriers, which is conducive to the formation of photocurrent. The transparent conductive layer covering the second doped semiconductor part and the first doped semiconductor part has a high conductivity, which can timely lead out the carriers collected by the first doped semiconductor part and the second doped semiconductor part, thereby reducing the carrier recombination rate. The above second doped semiconductor part is not only arranged on the second region, but also extends to cover the first doped semiconductor part of the overlapping region. Moreover, at least part of the overlapping region is a reverse leakage region, in which the part of the transparent conductive layer extending from the second region into the overlapping region (i.e., the first transparent conductive part) can be electrically connected to the first doped semiconductor part of the opposite conductivity type through the second doped semiconductor part. At this time, the part where the first doped semiconductor part and the second doped semiconductor part overlap each other forms a built-in diode structure with a lower reverse breakdown voltage. When the back contact battery is blocked, the leakage current is led out through the part where the first doped semiconductor part and the second doped semiconductor part overlap each other, and then through the first transparent conductive part and through the electrode in contact with it. Among them, it should be noted that, in the reverse leakage region, the above-mentioned first transparent conductive part is electrically connected to the first doped semiconductor part of the opposite conductivity type to itself through the second doped semiconductor part, and this electrical connection method does not include the electrical connection realized through the semiconductor substrate. It can be understood that the second doped semiconductor part and the first doped semiconductor part can be electrically connected through a tunneling mechanism or a thin dielectric layer. Secondly, in the back contact battery provided by the present invention, the insulating groove provided in the transparent conductive layer can physically insulate the part of the transparent conductive layer corresponding to the first area from the part of the transparent conductive layer corresponding to the second area, and the physical insulation means no contact, so as to prevent the back contact battery from having a short circuit problem.

[0008] In addition, in the back contact battery provided by the present invention, there is no need to set an insulating layer for separating the first doped semiconductor part and the second doped semiconductor part in the part where they overlap each other, which is beneficial to simplify the manufacturing process of the back contact battery while taking advantage of the electrical connection between the two in the reverse leakage area to reduce the risk of hot spots. Moreover, along the first direction, the larger the width of the first transparent conductive part set in the reverse leakage area, the smaller the transmission resistance of the leakage current in the first transparent conductive part, the greater the corresponding reduction in the reverse breakdown voltage, and the leakage loss of the back contact battery in the forward voltage area may be higher. On the contrary, along the first direction, the smaller the width of the first transparent conductive part set in the reverse leakage area, the larger the transmission resistance of the leakage current in the first transparent conductive part, the smaller the corresponding reduction in the reverse breakdown voltage, and the leakage loss of the back contact battery in the forward voltage area may be lower. Based on this, during the application process of the back contact battery provided by the present invention, it is only necessary to adjust the width W1 of the first transparent conductive part in the first direction and the width W2 of the overlapping area in the first direction to adjust the leakage loss and the reverse breakdown voltage, thereby reducing the risk of hot spots of the back contact battery while making the back contact battery have a higher working efficiency in the forward voltage area. Moreover, in the actual manufacturing process, it is only necessary to fine-tune the selective etching pattern used when forming the transparent conductive layer, without changing other manufacturing processes of the back contact battery, thereby improving the compatibility of the back contact battery provided by the present invention with the existing manufacturing process and reducing the manufacturing difficulty of the back contact battery provided by the present invention.

[0009] As a possible implementation scheme, the portion of the transparent conductive layer extending from the first region into the overlapping region is the second transparent conductive portion. The width of the second transparent conductive portion in the first direction is W3, and the ratio of W3 to W2 is less than or equal to 80%.

[0010] In the case of adopting the above technical solution, the second transparent conductive part is the part of the transparent conductive layer extending from the first area into the overlapping area. Under the spacing effect of the insulating groove, the leakage current will only pass through the first doped semiconductor part in the reverse leakage area and conduct to the first transparent conductive part of the opposite conductivity type to the first doped semiconductor part through the second doped semiconductor part, and rarely or even not through the second transparent conductive part in the reverse leakage area to the first transparent conductive part of the opposite conductivity type, so the existence of the second transparent conductive part has a low or even no effect on the reverse breakdown voltage. In addition, the first transparent conductive part, the second transparent conductive part and the insulating groove are all arranged in the overlapping area. In order to separate the parts of the transparent conductive layer corresponding to the first area and the second area, it can be understood that the width of the insulating groove in the first direction must meet the minimum spacing greater than or equal to the leakage prevention. In the above case, when the width of the second transparent conductive part in the first direction is W3, and the ratio of W3 to W2 is less than or equal to 80%, the width of the first transparent conductive part in the first direction can be adjusted to facilitate the setting of the width of the first transparent conductive part in the first direction, which is further conducive to balancing the reverse breakdown voltage and working efficiency corresponding to the back contact battery.

[0011] As a possible implementation scheme, the reverse leakage region is continuously distributed along the second direction, and the second direction intersects with the first direction. In this case, the portion of the transparent conductive layer extending from the second region into the overlapping region (i.e., the first transparent conductive portion) can be continuously distributed along the second direction, so that the pattern (only the pattern corresponding to the notch of the insulating groove) of the entire layer of transparent conductive material (the transparent conductive material is used to manufacture the transparent conductive layer) disposed on the first doped semiconductor portion and the second doped semiconductor portion is relatively simple, which is conducive to reducing the difficulty of patterning the back contact battery. At the same time, when the reverse leakage region is continuously distributed along the second direction, the leakage path between the first doped semiconductor portion and the second doped semiconductor portion is more evenly distributed, which is conducive to the heat generated when the back contact battery is blocked. Evenly distributed in the entire battery area, further improving the anti-burning ability of the back contact battery.

[0012] As a possible implementation scheme, when the reverse leakage regions are continuously distributed along the second direction, the ratio of W1 to W2 is greater than or equal to 10% and less than or equal to 70%.

[0013] In the case of adopting the above technical solution, it can be understood that in the reverse leakage region, the contact area between the first transparent conductive part and the second doped semiconductor part is proportional to the reverse breakdown voltage. When the reverse leakage region is continuously distributed along the second direction, the extension length of the first transparent conductive part along the second direction is fixed. At this time, the reverse breakdown voltage and the forward leakage loss can be regulated by adjusting the width of the first transparent conductive part along the first direction. Based on this, in this case, when the ratio of W1 to W2 is greater than or equal to 10% and less than or equal to 70%, it is beneficial to prevent the reverse breakdown voltage from being reduced due to the small ratio of W1 to W2, which makes the contact area between the first transparent conductive part and the second doped semiconductor part smaller; in addition, it can also prevent the forward leakage loss from being higher due to the large ratio of W1 to W2, which makes the contact area between the first transparent conductive part and the second doped semiconductor part larger, further facilitating the balance between the reverse breakdown voltage and the working efficiency corresponding to the back contact battery.

[0014] As a possible implementation scheme, the above-mentioned reverse leakage area is intermittently distributed along the second direction, and the second direction intersects with the first direction. Along the second direction, the first transparent conductive portion has a continuous area and a discontinuous area. In this case, another implementation method is provided for the distribution of the first transparent conductive portion along the second direction. At this time, not only can the reverse breakdown voltage and forward leakage loss of the back contact battery be regulated by adjusting the width of the first transparent conductive portion along the first direction, but also the reverse breakdown voltage and forward leakage loss of the back contact battery can be regulated by adjusting the length of the continuous area and the discontinuous area of ​​the first transparent conductive portion along the second direction, thereby improving the applicability of the back contact battery provided by the present invention in different application scenarios.

[0015] As a possible implementation scheme, when the reverse leakage area is intermittently distributed along the second direction, along the second direction, the ratio of the length of the discontinuous area to the length of the continuous area is less than or equal to 90%. In this case, when the back contact battery provided by the present invention is set in an installation environment with fewer obstructions such as bird droppings, leaves or dust, the ratio of the length of the discontinuous area to the length of the continuous area can be set within a larger range to increase the proportion of the discontinuous area in the reverse leakage area, thereby facilitating the reduction of the leakage loss of the back contact battery in the forward voltage area, and ensuring that the back contact battery has a higher working efficiency. When the back contact battery provided by the invention is set in an installation environment with more obstructions such as bird droppings, leaves or dust, the ratio of the length of the discontinuous area to the length of the continuous area can be set within a smaller range to increase the proportion of the continuous area in the reverse leakage area, thereby facilitating the reduction of the reverse breakdown voltage of the back contact battery, and ensuring that the back contact battery has a lower risk of hot spots. It can be seen that along the second direction, when the ratio of the length of the discontinuous zone to the length of the continuous zone is less than or equal to 90%, the length of the discontinuous zone and the length of the continuous zone can be set according to different environmental requirements to improve the applicability of the back contact battery provided by the present invention in different practical application scenarios.

[0016] As a possible implementation scheme, when the reverse leakage area is intermittently distributed along the second direction, the ratio of W1 to W2 is greater than or equal to 20% and less than or equal to 90%. Such a setting can improve the applicability of the back contact battery provided by the present invention in different practical application scenarios. Specifically, the application principle of the beneficial effect in this case is similar to the application principle of the beneficial effect of the ratio of W1 to W2 being greater than or equal to 10% and less than or equal to 70% when the reverse leakage area is continuously distributed along the second direction as described above, and will not be repeated here.

[0017] As a possible implementation scheme, when the reverse leakage area is intermittently distributed along the second direction, the ratio of the width of the continuous area to the length of the continuous area is greater than or equal to 1:500 and less than or equal to 5:1. Such a setting can improve the applicability of the back contact battery provided by the present invention in different practical application scenarios. Specifically, the application principle of the beneficial effect in this case is similar to the application principle of the beneficial effect of the ratio of W1 to W2 being greater than or equal to 10% and less than or equal to 70% when the reverse leakage area is continuously distributed along the second direction as described above, and will not be repeated here.

[0018] As a possible implementation scheme, when the reverse leakage area is intermittently distributed along the second direction, the portion of the transparent conductive layer disposed in the second area is the third transparent conductive portion. A notch is provided in the portion of the third transparent conductive portion corresponding to the discontinuous area.

[0019] In the case of adopting the above technical solution, the second doped semiconductor part is not only arranged on the second region, but also extends to cover the first doped semiconductor part on the overlapping region. At this time, the second doped semiconductor part can not only be located on the side of the first doped semiconductor part on the overlapping region away from the semiconductor substrate, but also on the sidewall of the first doped semiconductor part on the overlapping region. In addition, the transparent conductive layer is located on the first doped semiconductor part and the second doped semiconductor part. At this time, the transparent conductive layer can contact the second doped semiconductor part on the sidewall of the first doped semiconductor part arranged on the overlapping region. In this case, when the part of the transparent conductive layer arranged in the second region (i.e., the third transparent conductive part) corresponding to the part of the discontinuous region is provided with a notch, it can be ensured that the third transparent conductive part will not be electrically connected to the second doped semiconductor part in the discontinuous region, and it can be ensured that the contact area between the second doped semiconductor part and the transparent conductive layer in the reverse leakage region can be effectively adjusted by adjusting the length of the discontinuous region and the continuous region of the first transparent conductive part along the second direction, so as to achieve precise control of the reverse breakdown voltage and forward leakage loss of the back contact battery. At the same time, in the actual application manufacturing process, it is necessary to selectively etch the first transparent conductive part to achieve the discontinuous distribution of the reverse leakage area along the second direction. Based on this, when the third transparent conductive part adjacent to the first transparent conductive part is provided with a notch corresponding to the discontinuous area, it is not necessary to strictly control the etching accuracy in order to achieve the above-mentioned selective etching and accurately stop at the junction of the first transparent conductive part and the third transparent conductive part during the etching of the first transparent conductive part, which is conducive to reducing the manufacturing difficulty of the back contact battery.

[0020] As a possible implementation solution, the width of the notch in the first direction is less than or equal to 100 μm.

[0021] In the case of adopting the above technical solution, it can be understood that in the transparent conductive layer, the part (i.e., the third transparent conductive part) arranged on the side of the second doped semiconductor part away from the semiconductor substrate needs to guide the carriers collected in the part of the second doped semiconductor part corresponding to the second region to the corresponding electrode when the back contact battery is in the working state, and can reduce the contact barrier between the second doped semiconductor part and the corresponding electrode, and reduce the carrier transmission loss. Based on this, when the part of the third transparent conductive part corresponding to the spacer is provided with a notch, the carriers collected in the part of the second doped semiconductor part corresponding to the notch need to be transmitted to the third transparent conductive part through the adjacent part, and the transmission loss of the carriers collected in the part of the second doped semiconductor part corresponding to the notch is relatively high. In this case, when the width of the notch in the first direction is less than or equal to 100μm, the range of the notch is relatively small, which is conducive to controlling the transmission loss of the carriers collected in the second doped semiconductor part within a certain range while reducing the difficulty of selective etching, so as to ensure that the back contact battery has a high photoelectric conversion efficiency.

[0022] As a possible implementation scheme, the doping concentration of the dopant in the first doped semiconductor portion and / or the second doped semiconductor portion is greater than or equal to 1E19 cm -3 , and less than or equal to 5E20cm -3 .

[0023] In the case of adopting the above technical solution, the doping concentration of the dopant in at least one of the first doped semiconductor part and the second doped semiconductor part is within the above range, which can prevent the low field passivation effect on the semiconductor substrate caused by the low doping concentration of the dopant in the first doped semiconductor part and / or the second doped semiconductor part, and ensure that the first side of the back contact battery has a relatively low carrier recombination rate under normal working conditions; at the same time, it is also beneficial to make the first doped semiconductor part and / or the second doped semiconductor part have good conductivity, ensuring that the part of the first doped semiconductor part and / or the second doped semiconductor part in the reverse leakage region has a relatively low transmission resistance when the back contact battery is blocked, which is further beneficial to reduce the reverse breakdown voltage of the back contact battery. In addition, it can also prevent the difficulty of doping the intrinsic semiconductor layer used to manufacture the first doped semiconductor part and / or the second doped semiconductor part due to the high doping concentration of the dopant in the first doped semiconductor part and / or the second doped semiconductor part, which is beneficial to improve the yield of the back contact battery.

[0024] As a possible implementation solution, the thickness of the first doped semiconductor portion is greater than or equal to 50 nm and less than or equal to 200 nm.

[0025] In the case of adopting the above technical solution, the thickness of the first doped semiconductor part is within the above range, which can prevent the field passivation effect of the first doped semiconductor part from being low due to the small thickness of the first doped semiconductor part; it can also prevent the use of consumables for manufacturing the first doped semiconductor part from being large due to the large thickness of the first doped semiconductor part, which is conducive to controlling the manufacturing cost of the back contact battery. In addition, the thickness of the first doped semiconductor part will affect the docking height between the side of the first doped semiconductor part and the side of the second doped semiconductor part, and then affect the junction area of ​​the PN junction formed between the first doped semiconductor part and the second doped semiconductor part in the reverse leakage region. Based on this, when the thickness of the first doped semiconductor part is within the above range, it can also prevent the leakage current of the first doped semiconductor part and the second doped semiconductor part from being large in the side docking part due to the large thickness of the first doped semiconductor part, ensuring that the leakage loss and reverse breakdown voltage of the back contact battery can be effectively regulated by adjusting the width W1 of the first transparent conductive part in the first direction and the width W2 of the overlapping area in the first direction, so that the back contact battery has higher working performance and working reliability.

[0026] As a possible implementation solution, the degree of crystallization of the second doped semiconductor portion is less than or equal to 60%.

[0027] In the case of adopting the above technical solution, it can be understood that the degree of crystallization of the second doped semiconductor part will affect its own conductivity, and then affect the leakage loss of the back contact battery in the reverse leakage area, and the reverse breakdown voltage of the back contact battery when it is blocked. Based on this, when the degree of crystallization of the second doped semiconductor part is in the above range, the degree of crystallization of the second doped semiconductor part has a larger optional range. At this time, when the back contact battery provided by the present invention is set in an installation environment with fewer obstructions such as bird droppings, leaves or dust, the degree of crystallization of the second doped semiconductor part can be set in a smaller range to reduce the recombination rate of carriers of opposite conductivity types in the reverse leakage area between the first doped semiconductor part and the second doped semiconductor part, thereby facilitating the reduction of the leakage loss of the back contact battery in the forward voltage area, and ensuring that the back contact battery has a higher working efficiency. When the back contact battery provided by the invention is set in an installation environment with more obstructions such as bird droppings, leaves or dust, the degree of crystallization of the second doped semiconductor part can be set in a larger range to improve the conductivity of the second doped semiconductor part, thereby facilitating the reduction of the reverse breakdown voltage of the back contact battery, and ensuring that the back contact battery has a lower risk of hot spots. It can be seen from this that the degree of crystallization of the second doped semiconductor portion can be set according to different environmental requirements, thereby improving the applicability of the back contact cell provided by the present invention in different practical application scenarios.

[0028] As a possible implementation scheme, the thickness of the second doped semiconductor portion is greater than or equal to 5 nm and less than or equal to 50 nm. The application principle of the beneficial effect in this case is the same as the application principle of the beneficial effect of the thickness of the first doped semiconductor portion being greater than or equal to 50 nm and less than or equal to 200 nm as described above, and will not be repeated here.

[0029] As a possible implementation solution, the electrical conductivity of the second doped semiconductor portion is greater than or equal to 10E-5S / cm and less than or equal to 1S / cm.

[0030] In the case of adopting the above technical solution, it can be understood that the conductivity of the second doped semiconductor part directly affects its own conductivity. The conductivity of the second doped semiconductor part will affect the leakage loss of the back contact battery in the reverse leakage area, as well as the reverse breakdown voltage of the back contact battery when it is blocked. Based on this, when the conductivity of the second doped semiconductor part is within the above range, it can prevent the forward leakage loss of the back contact battery from being large due to the large conductivity of the second doped semiconductor part, which makes the conductivity of the second doped semiconductor part too high; in addition, it can also prevent the reverse breakdown voltage of the back contact battery from being high due to the small conductivity of the second doped semiconductor part, which makes the conductivity of the second doped semiconductor part too low, which is further conducive to achieving a balance between the reverse breakdown voltage and working efficiency of the back contact battery.

[0031] As a possible implementation solution, the semiconductor substrate is a silicon substrate.

[0032] As a possible implementation scheme, when the first doped semiconductor portion is formed on the first region and the overlapping region, the back contact cell further includes a first interface passivation layer located between the first doped semiconductor portion and the semiconductor substrate.

[0033] When the above-mentioned technical solution is adopted, the passivation contact structure composed of the first interface passivation layer and the first doped semiconductor part has an excellent interface passivation effect, and can realize the selective collection of carriers, reduce the carrier recombination rate in the first area and the overlapping area of ​​the first surface of the semiconductor substrate, and further improve the photoelectric conversion efficiency of the back contact battery.

[0034] As a possible implementation, the back contact battery further includes a second interface passivation layer, which is located between the second region of the first surface and the second doped semiconductor portion, and extends between the second doped semiconductor portion and the first doped semiconductor portion.

[0035] When the above technical solution is adopted, the passivation contact structure composed of the second interface passivation layer and the second doped semiconductor portion located on the second region can realize selective collection of carriers and reduce the carrier recombination rate in the second region of the first surface of the semiconductor substrate.

[0036] As a possible implementation solution, the thickness of the second interface passivation layer is greater than or equal to 2 nm and less than or equal to 20 nm.

[0037] When the above technical solution is adopted, the thickness of the second interface passivation layer will affect its own transmission resistance and passivation effect. Based on this, the thickness of the second interface passivation layer is within the above range, which is conducive to preventing the second interface passivation layer from having a poor passivation effect on the second region due to its small thickness, and ensuring that the surface of the second region has a low carrier recombination rate. It can also prevent the second interface passivation layer from having a large thickness, which makes its own transmission resistance large, resulting in a low carrier collection efficiency of the second doped semiconductor part under normal operation of the back contact battery, and a small reduction in the reverse breakdown voltage when the back contact battery is blocked, which is further conducive to achieving a balance between the reverse breakdown voltage and working efficiency of the back contact battery.

[0038] As a possible implementation scheme, when the doping concentration of the dopant in the first doped semiconductor portion is greater than or equal to 1E19 cm -3 , and less than or equal to 5E19cm -3 When the thickness of the second interface passivation layer is greater than or equal to 5 nm and less than or equal to 15 nm. Alternatively, when the doping concentration of the dopant in the first doped semiconductor portion is greater than 5E19 cm -3 , and less than or equal to 1E20cm -3 When the thickness of the second interface passivation layer is greater than or equal to 6 nm and less than or equal to 17 nm. Alternatively, when the doping concentration of the dopant in the first doped semiconductor portion is greater than 1E20 cm -3 , and less than or equal to 5E20cm -3 When the thickness of the second interface passivation layer is greater than or equal to 7 nm and less than or equal to 20 nm.

[0039] When the above technical solution is adopted, the doping concentration of the dopant in the first doped semiconductor part will affect its own conductivity. Specifically, within a certain range, the higher the doping concentration of the dopant in the first doped semiconductor part, the higher the conductivity of the first doped semiconductor part; on the contrary, the lower the doping concentration of the dopant in the first doped semiconductor, the lower the conductivity of the first doped semiconductor part. As for the above-mentioned second interface passivation layer, the thickness of the second interface passivation layer is related to its own passivation effect and transmission resistance. When the thickness of the second interface passivation layer is small, in the reverse leakage region, the leakage current between the first doped semiconductor part and the second doped semiconductor part is larger. Based on this, the back contact battery provided by the present invention is provided with a second interface passivation layer of corresponding thickness according to the different doping concentrations of the dopant in the first doped semiconductor part, so as to realize the reasonable regulation of the working efficiency and reverse breakdown voltage of the back contact battery, and ensure that the back contact battery has high working performance and working reliability.

[0040] As a possible implementation scheme, in the case where the back contact battery includes a first interface passivation layer and a second interface passivation layer, the first interface passivation layer and the first doped semiconductor portion constitute a first passivation contact structure, and the second interface passivation layer and the second doped semiconductor portion constitute a second passivation contact structure. Wherein, the first passivation contact structure and the second passivation contact structure have different passivation contact types; and / or, the thermal stability of the first passivation contact structure is greater than the thermal stability of the second passivation contact structure; and / or, the first passivation contact structure is a tunneling passivation contact structure; and / or, the second passivation contact structure is a heterogeneous contact structure.

[0041] In the case of adopting the above technical solution, when the passivation contact types of the first passivation contact structure and the second passivation contact structure are different, the passivation contact types of the first passivation contact structure and the second passivation contact structure can be respectively adjusted according to the requirements of different actual application scenarios, so as to improve the applicability of the back contact battery provided by the present invention in different application scenarios. For example: in the actual manufacturing process, after forming the first passivation contact structure in the first region and the overlapping region, and forming the second passivation contact structure with a whole layer, it is usually necessary to use a laser processing process to pattern the mask material with the whole layer, so as to form a mask layer for selectively etching the second passivation contact structure. In order to process all parts of the mask material corresponding to the first region, the heat of the laser radiation will be conducted to the first passivation contact structure. Because the heat of the laser is high, when the first passivation contact structure has a high thermal stability, the influence of the heat of the laser radiation on the first passivation contact structure can be reduced, and even the heat of the laser radiation will not affect the first passivation contact structure, thereby improving the yield of the back contact battery. The portion of the second passivation contact structure corresponding to the first area needs to be removed, and the laser processing process has a high precision. Therefore, the portion of the second passivation contact structure corresponding to the overlapping area and the second area will not be affected by heat, or the thermal impact will be small. At this time, the manufacturing process has lower requirements on the thermal stability of the second passivation contact structure, and the thermal stability of the second passivation contact structure can be set to be lower than the thermal stability of the first passivation contact structure.

[0042] In addition, when the first passivation contact structure is a tunnel passivation contact structure, since amorphous silicon materials are easy to form polycrystalline silicon or single crystal silicon at high temperatures, and the chemical properties of tunnel passivation materials and polycrystalline silicon at high temperatures are relatively stable, compared with heterogeneous contact structures, tunnel passivation contact structures are less sensitive to high-temperature laser thermal damage, and can reduce the impact on the passivation effect during the laser processing process, further increasing the process window and reducing the process difficulty. In addition, the heterogeneous contact structure has a passivation effect that is superior to the tunnel passivation contact structure, so when the second passivation contact structure is a heterogeneous contact structure, the carrier recombination rate at the interface between the semiconductor substrate and the second interface passivation layer can be further reduced, which is beneficial to improving the photoelectric conversion efficiency of the back contact battery.

[0043] As a possible implementation scheme, the back contact cell further includes a surface passivation layer disposed on the second side of the semiconductor substrate. The surface passivation layer includes an intrinsic semiconductor passivation layer and a silicon nitride passivation layer sequentially stacked along the thickness direction of the semiconductor substrate and disposed on the second side. The material of the intrinsic semiconductor passivation layer includes at least one of amorphous silicon, microcrystalline silicon and nanocrystalline silicon.

[0044] When the above technical solution is adopted, the intrinsic semiconductor passivation layer included in the surface passivation layer can be formed simultaneously when the interface passivation layer included in the heterogeneous contact structure is manufactured on the first side. The silicon nitride passivation layer included in the surface passivation layer can be formed simultaneously when the mask material for realizing the second passivation contact structure is manufactured on the first side, and there is no need to add additional operation steps to form the surface passivation layer, which is conducive to improving the manufacturing efficiency of the back contact battery.

[0045] As a possible implementation scheme, the cross-sectional area of ​​the above-mentioned insulating groove gradually decreases in the direction approaching the semiconductor substrate; and / or, in the transparent conductive layer, the thickness of each region along the first direction is the same for the part whose orthographic projection on the first surface does not overlap with the orthographic projection of the insulating groove on the first surface.

[0046] In the case of adopting the above technical solution, when the cross-sectional area of ​​the insulating groove gradually decreases in the direction close to the semiconductor substrate, the cross-sectional area at the bottom of the insulating groove is smaller than the cross-sectional area at the notch of the insulating groove. At this time, the thickness of the end of the transparent conductive layer close to the insulating groove gradually increases in the direction away from the insulating groove. Based on this, especially for the reverse leakage area, the leakage current flows from the edge of the transparent conductive layer to the corresponding electrode. At this time, the density of the leakage current at the edge of the transparent conductive layer is small, and almost all the leakage current in the part of the transparent conductive layer far away from its own edge area will pass through here, so the leakage current density of the part of the transparent conductive layer far away from its own edge area is large. In the above case, when the thickness of the end of the transparent conductive layer close to the insulating groove gradually increases in the direction away from the insulating groove, the thickness of the part of the transparent conductive layer far away from its own edge area is large, which is more conducive to the transmission of leakage current and is conducive to further reducing the risk of hot spots of back contact batteries. When the thickness of each region along the first direction of the transparent conductive layer whose orthographic projection on the first surface does not overlap with the orthographic projection of the insulating groove on the first surface is the same, it is beneficial for the transparent conductive layer to have a larger thickness in each region along the first direction away from its own edge region, which is not only beneficial for the transmission of leakage current when the back contact battery is blocked, but also beneficial for the back contact battery to extract the photocurrent generated in the forward voltage region, further improving the working performance of the back contact battery and reducing the risk of hot spots.

[0047] As a possible implementation solution, the crystallization degree of at least a portion of the second doped semiconductor portion located in the second region is greater than the crystallization degree of a portion of the second doped semiconductor portion corresponding to the first transparent conductive portion.

[0048] In the case of adopting the above technical solution, it can be understood that when the back contact battery is in normal working state, the part of the second doped semiconductor part located in the second region needs to collect and guide out the carriers of the corresponding conductive type generated in the semiconductor substrate to facilitate the formation of photocurrent. The part of the second doped semiconductor part corresponding to the first transparent conductive layer is electrically connected to the first doped semiconductor part of the opposite conductive type. When the back contact battery is in normal working state, the part of the second doped semiconductor part corresponding to the first transparent conductive layer will have leakage current with the first doped semiconductor part. Secondly, under the same other factors, when the degree of crystallization of the doped semiconductor part is smaller, the grains in the doped semiconductor part are smaller, and even the disorder of amorphous semiconductor materials is presented. The smaller the grains in the doped semiconductor part and / or the fewer the number of grains, the more interfaces between the grains in the doped semiconductor part, so the resistance of the grain interface will be larger. In the above case, when the crystallization degree of at least the part of the second doped semiconductor part located in the second region is set to be greater than the crystallization degree of the part of the second doped semiconductor part corresponding to the first transparent conductive part, the conductivity of at least the part of the second doped semiconductor part located in the second region will be greater, which is conducive to reducing the transmission loss of at least the part of the second doped semiconductor part located in the second region, and reducing the contact resistance between at least the part of the second doped semiconductor part located in the second region and the transparent conductive layer. The crystallization degree of the part of the second doped semiconductor part corresponding to the first transparent conductive part is relatively low, and the conductivity of the part of the second doped semiconductor part corresponding to the first transparent conductive part is relatively low, which is conducive to reducing the magnitude of the forward leakage current between the part of the second doped semiconductor part corresponding to the first transparent conductive layer and the first doped semiconductor part, and further improving the conversion efficiency of the back contact battery.

[0049] As a possible implementation, the crystallization degree of at least a portion of the second doped semiconductor portion located in the second region is greater than the crystallization degree of a portion of the second doped semiconductor portion located in the overlapping region. It can be understood that the first doped semiconductor portion is electrically connected to the second doped semiconductor portion in the overlapping region, and when the battery is working normally, reducing the crystallization degree of this portion can effectively and better reduce the forward leakage current.

[0050] As a possible implementation, the crystallization degree of at least part of the second doped semiconductor portion located in the second region is greater than the crystallization degree of the part of the second doped semiconductor portion covering the side wall; the side wall is located at the junction of the overlapping region and the second region.

[0051] In the case of adopting the above technical solution, it can be understood that, in the second doped semiconductor part, the part located on the side wall at the junction of the overlapping region and the second region is closer to the second region than the part corresponding to the second region. Based on this, when the crystallization degree of the part of the second doped semiconductor part covering the side wall at the junction of the overlapping region and the second region is relatively small, it is helpful to prevent the part of the second doped semiconductor part corresponding to the first transparent conductive part from being affected in the process of crystallization modification of at least the part of the second doped semiconductor part corresponding to the second region by laser processing or the like in the actual manufacturing process, thereby ensuring that the part of the second doped semiconductor part corresponding to the first transparent conductive part has a relatively small conductivity, and effectively controlling the forward leakage current between the part of the second doped semiconductor part corresponding to the first transparent conductive part and the first doped semiconductor part.

[0052] As a possible implementation scheme, the second doped semiconductor portion includes a high crystallization region and a low crystallization region; the crystallization degree of the portion of the second doped semiconductor portion located in the low crystallization region is less than the crystallization degree of the portion of the second doped semiconductor portion located in the high crystallization region; in the second doped semiconductor portion, at least the portion corresponding to the first transparent conductive portion is located in the low crystallization region, and at least the portion corresponding to the second region is located in the high crystallization region. The application principle of the beneficial effect in this case is similar to the application principle of the beneficial effect described above that the crystallization degree of at least the portion of the second doped semiconductor portion located in the second region is greater than the crystallization degree of the portion of the second doped semiconductor portion corresponding to the first transparent conductive portion, and will not be repeated here.

[0053] As a possible implementation scheme, the above-mentioned low crystallization zone is located in the overlapping area; or, along the first direction, one side edge of the above-mentioned low crystallization zone is located in the overlapping area, and the other side edge extends to the side wall, and the side wall is located at the junction of the overlapping area and the second area; or, along the first direction, one side edge of the above-mentioned low crystallization zone is located in the overlapping area, and the other side edge extends to the second area; or, the above-mentioned high crystallization zone corresponds to the entire second area.

[0054] In the case of adopting the above technical solution, since at least part of the overlapping region is the reverse leakage region, when the above low crystallization region is located in the overlapping region, it can ensure that the conductivity of the part of the second doped semiconductor part located in the reverse leakage region is relatively small, effectively control the magnitude of the forward leakage current between the second doped semiconductor part and the first doped semiconductor part in the reverse leakage region, and help improve the conversion efficiency of the back contact battery. In addition, when along the first direction, one side edge of the above low crystallization region is located in the overlapping region and the other side edge extends to the side wall located at the junction of the overlapping region and the second region, or when along the first direction, one side edge of the above low crystallization region is located in the overlapping region and the other side edge extends to the second region, it is beneficial to prevent the above operation from affecting the second doped semiconductor part located in the overlapping region while making at least part of the second region corresponding to the second region located in the high crystallization region by laser processing or the like, and ensure that the part of the second doped semiconductor part located in the overlapping region has a smaller conductivity while reducing the requirements for the processing accuracy. In addition, when the high crystallization region corresponds to the entire second region, the portion of the second doped semiconductor portion corresponding to the entire second region has a relatively high electrical conductivity, so that the portion of the second doped semiconductor portion corresponding to the entire second region has a high carrier collection efficiency, thereby improving the working efficiency of the back contact battery.

[0055] In a second aspect, the present invention provides a photovoltaic module, which includes a back-contact cell provided by the first aspect and various implementations thereof.

[0056] The beneficial effects of the second aspect of the present invention and its various implementations can be analyzed by referring to the beneficial effects of the first aspect and its various implementations, and will not be repeated here.

[0057] In a third aspect, the present invention provides a method for manufacturing a back-contact battery, the method for manufacturing a back-contact battery comprising: first, providing a semiconductor substrate. The semiconductor substrate comprises a first surface and a second surface opposite to each other. The first surface comprises a first region and a second region, and an overlapping region between the first region and the second region. The first region, the overlapping region, and the second region are arranged along a first direction. Next, a first doped semiconductor portion disposed in the first region and the overlapping region is formed. Next, a second doped semiconductor portion is formed disposed on the second region and extends to cover a portion of the first doped semiconductor portion corresponding to the overlapping region on a side away from the semiconductor substrate. The conductivity type of the second doped semiconductor portion is opposite to that of the first doped semiconductor portion. Next, a transparent conductive layer covering the second doped semiconductor portion and the first doped semiconductor portion is formed. An insulating groove is provided in the transparent conductive layer to separate a portion of the transparent conductive layer corresponding to the first region from a portion of the transparent conductive layer corresponding to the second region. Wherein, at least a portion of the overlapping region is a reverse leakage region. In the reverse leakage region, a portion of the transparent conductive layer extending from the second region into the overlapping region is a first transparent conductive portion, and the first transparent conductive portion is electrically connected to the first doped semiconductor portion through the second doped semiconductor portion. The width of the first transparent conductive portion in the first direction is W1, the width of the overlapping region in the first direction is W2, and the ratio of W1 to W2 is greater than or equal to 10% and less than or equal to 90%.

[0058] As a possible implementation scheme, forming a first doped semiconductor portion disposed in the first region and the overlapping region includes: forming a first doped semiconductor portion disposed on or within the first surface as a whole layer. Next, forming an insulating mask layer on a portion of the first doped semiconductor portion corresponding to the first region and the overlapping region. Next, under the protection of the insulating mask layer, removing a portion of the first doped semiconductor portion corresponding to the second region. Then, removing the insulating mask layer.

[0059] As a possible implementation scheme, after forming the transparent conductive layer, or while opening the insulating groove in the transparent conductive layer, the manufacturing method of the back contact battery further includes: selectively etching at least the first transparent conductive portion so that the first transparent conductive portion is intermittently distributed along the second direction. The second direction intersects the first direction.

[0060] As a possible implementation scheme, the above-mentioned formation of the first doped semiconductor part arranged in the first region and the overlapping region includes: forming a first doped semiconductor part arranged in a whole layer on or within the first surface; and using a laser etching process to selectively remove the portion of the first doped semiconductor part corresponding to the second region. And / or, the above-mentioned formation of the second doped semiconductor part arranged on the second region and extending to cover the portion of the first doped semiconductor part corresponding to the overlapping region on the side away from the semiconductor substrate includes: forming a second doped semiconductor part arranged in a whole layer on the first doped semiconductor part and the second region; and using a laser etching process to selectively remove the portion of the second doped semiconductor part corresponding to the first region. And / or, the above-mentioned formation of the transparent conductive layer covering the second doped semiconductor part and the first doped semiconductor part includes: forming a transparent conductive layer arranged in a whole layer on the first doped semiconductor part and the second doped semiconductor part; and using a laser etching process to open an insulating groove in the transparent conductive layer. In the above case, when manufacturing at least one of the first doped semiconductor part, the second doped semiconductor part and the transparent conductive layer, the laser etching process is used to directly selectively etch the corresponding film layer set in the entire layer, which can save the deposition process and removal process of the mask layer, reduce the manufacturing cost of the back contact battery, and improve the manufacturing efficiency of the back contact battery. In addition, only the selective etching pattern used in the laser etching process needs to be fine-tuned, and there is no need to change other manufacturing processes of the back contact battery, thereby improving the compatibility of the manufacturing method provided by the present invention with the existing manufacturing process and reducing the manufacturing difficulty.

[0061] The beneficial effects of the third aspect of the present invention and its various implementations can be analyzed by referring to the beneficial effects of the first aspect and its various implementations, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0063] Figure 1 A schematic longitudinal cross-sectional view of a first structure of a back contact battery provided by an embodiment of the present invention;

[0064] Figure 2 A schematic longitudinal cross-sectional view of a second structure of a back contact battery provided by an embodiment of the present invention;

[0065] Figure 3 A schematic longitudinal cross-sectional view of a third structure of a back contact battery provided by an embodiment of the present invention;

[0066] Figure 4 A schematic longitudinal cross-sectional view of a fourth structure of a back-contact battery provided by an embodiment of the present invention;

[0067] Figure 5 A schematic top view of a first structure of a back contact battery provided by an embodiment of the present invention on one side of the first surface;

[0068] Figure 6 A schematic top view of a second structure of a back contact battery provided by an embodiment of the present invention on one side of the first surface;

[0069] Figure 7 A schematic top view of a third structure of a back contact battery provided by an embodiment of the present invention on one side of the first surface;

[0070] Figure 8 Schematic diagram of the structure of the back contact battery provided in the embodiment of the present invention during the manufacturing process Figure 1 ;

[0071] Fig. 9 Schematic diagram of the structure of the back contact battery provided in the embodiment of the present invention during the manufacturing process Figure 2 ;

[0072] Fig.10 Schematic diagram of the structure of the back contact battery provided in the embodiment of the present invention during the manufacturing process Figure 3 ;

[0073] Fig.11 Schematic diagram of the structure of the back contact battery provided in the embodiment of the present invention during the manufacturing process Figure 4 ;

[0074] Fig.12 Schematic diagram of the structure of the back contact battery provided in the embodiment of the present invention during the manufacturing process Figure 5 ;

[0075] Fig.13 Schematic diagram of the structure of the back contact battery provided in the embodiment of the present invention during the manufacturing process Figure 6 ;

[0076] Fig.14 Schematic diagram of the structure of the back contact battery provided in the embodiment of the present invention during the manufacturing process Figure 7 ;

[0077] Fig.15 Schematic diagram of the structure of the back contact battery provided in the embodiment of the present invention during the manufacturing process Figure 8 ;

[0078] Fig.16 Schematic diagram of the structure of the back contact battery provided in the embodiment of the present invention during the manufacturing process Figure 9 ;

[0079] Fig.17 Schematic diagram of the structure of the back contact battery provided in the embodiment of the present invention during the manufacturing process Figure 10 ;

[0080] Fig.18 Schematic diagram of the structure of the back contact battery provided in the embodiment of the present invention during the manufacturing process Figure 10 one;

[0081] Fig.19 Schematic diagram of the structure of the back contact battery provided in the embodiment of the present invention during the manufacturing process Figure 10 two;

[0082] Fig. 20 Schematic diagram of the structure of the back contact battery provided in the embodiment of the present invention during the manufacturing process Figure 10 three.

[0083] Figure numerals: 11 is a semiconductor substrate, 12 is a first doped semiconductor portion, 13 is a second doped semiconductor portion, 14 is a transparent conductive layer, 15 is a first region, 16 is a second region, 17 is an overlapping region, 18 is an insulating groove, 19 is a first transparent conductive portion, 20 is a second transparent conductive portion, 21 is a continuous region, 22 is a discontinuous region, 23 is a third transparent conductive portion, 24 is a recess, 25 is a first electrode, 26 is a first interface passivation layer, 27 is a second interface passivation layer, 28 is a surface passivation layer, 29 is a second electrode, and 30 is an insulating mask layer. DETAILED DESCRIPTION

[0084] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present disclosure. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present disclosure.

[0085] Various structural schematic diagrams according to embodiments of the present disclosure are shown in the accompanying drawings. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may further design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0086] In the context of the present disclosure, when a layer / element is referred to as being "on" another layer / element, the layer / element may be directly on the other layer / element, or there may be an intermediate layer / element between them. In addition, if a layer / element is "on" another layer / element in one orientation, then when the orientation is reversed, the layer / element may be "under" the other layer / element. In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0087] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined. The meaning of "several" is one or more, unless otherwise clearly and specifically defined.

[0088] In a first aspect, an embodiment of the present invention provides a back contact battery. Figure 1As shown, the back contact cell provided by the embodiment of the present invention includes: a semiconductor substrate 11, a first doped semiconductor part 12, a second doped semiconductor part 13 and a transparent conductive layer 14. The conductivity types of the second doped semiconductor part 13 and the first doped semiconductor part 12 are opposite. The semiconductor substrate 11 includes a first surface and a second surface opposite to each other. The first surface includes a first region 15 and a second region 16, and an overlapping region 17 between the first region 15 and the second region 16. In addition, the first region 15, the overlapping region 17, and the second region 16 are arranged along a first direction. The first doped semiconductor part 12 is arranged on the first region 15 and the overlapping region 17. The second doped semiconductor part 13 is arranged on the second region 16 and extends to cover the first doped semiconductor part 12 of the overlapping region 17. The transparent conductive layer 14 covers the second doped semiconductor part 13 and the first doped semiconductor part 12. The transparent conductive layer 14 is provided with an insulating groove 18 to physically insulate the portion of the transparent conductive layer 14 corresponding to the first region 15 from the portion of the transparent conductive layer 14 corresponding to the second region 16. Among them, at least part of the overlapping region 17 is a reverse leakage region. Moreover, in the reverse leakage region, the portion of the transparent conductive layer 14 extending from the second region 16 into the overlapping region 17 is a first transparent conductive portion 19, and the first transparent conductive portion 19 is electrically connected to the first doped semiconductor portion 12 through the second doped semiconductor portion 13. The width of the first transparent conductive portion 19 in the first direction is W1, and the width of the overlapping region 17 in the first direction is W2, and the ratio of W1 to W2 is greater than or equal to 10% and less than or equal to 90%.

[0089] When the above technical solution is adopted, when the back contact battery is in working state, the above first doped semiconductor part and the second doped semiconductor part can effectively shunt the carriers, which is conducive to the formation of photocurrent. The transparent conductive layer covering the second doped semiconductor part and the first doped semiconductor part has a high conductivity, which can timely guide the carriers collected by the first doped semiconductor part and the second doped semiconductor part to reduce the carrier recombination rate. Figure 1As shown, the second doped semiconductor portion 13 is not only arranged on the second region 16, but also extends to cover the first doped semiconductor portion 12 in the overlapping region 17. Moreover, at least a portion of the overlapping region 17 is a reverse leakage region, in which the portion of the transparent conductive layer 14 extending from the second region 16 into the overlapping region 17 (i.e., the first transparent conductive portion 19) can be electrically connected to the first doped semiconductor portion 12 of the opposite conductivity type through the second doped semiconductor portion 13. At this time, the portion where the first doped semiconductor portion 12 and the second doped semiconductor portion 13 overlap each other forms a built-in diode structure with a lower reverse breakdown voltage. When the back contact battery is blocked, the leakage current (it should be emphasized that for the sake of convenience and clear description, when the embodiment of the present invention is When the transmission mode of the leakage current is mentioned, it not only includes its own transmission path, but also includes its own transmission direction, but it does not mean that the transmission direction of the leakage current can only be a single direction in the description. When the conductivity type of the first doped semiconductor part and the second doped semiconductor part changes, the transmission direction of the leakage current can also be opposite to the direction in the description, that is, in the embodiment of the present invention, only the transmission path of the leakage current is limited, and the transmission direction of the leakage current is not limited) through the overlapping part of the first doped semiconductor part 12 and the second doped semiconductor part 13, and then through the first transparent conductive part 19 and through the electrode in contact with it. It should be noted that in the reverse leakage region, the first transparent conductive part is electrically connected to the first doped semiconductor part of the opposite conductivity type through the second doped semiconductor part, and the electrical connection mode does not include the electrical connection realized through the semiconductor substrate. Secondly, in the back contact battery provided by the present invention, the insulating groove provided in the transparent conductive layer can physically insulate the part of the transparent conductive layer corresponding to the first region from the part of the transparent conductive layer corresponding to the second region, and the physical insulation means no contact to prevent the back contact battery from having a short circuit problem.

[0090] In addition, in the back contact battery provided by the embodiment of the present invention, there is no need to set an insulating layer for separating the first doped semiconductor part and the second doped semiconductor part 13 at the part where they overlap each other, which is beneficial to simplify the manufacturing process of the back contact battery while taking advantage of the electrical connection between the two in the reverse leakage area to reduce the risk of hot spots. Moreover, along the first direction, the larger the width of the first transparent conductive part set in the reverse leakage area, the smaller the transmission resistance of the leakage current in the first transparent conductive part, the greater the corresponding reduction in the reverse breakdown voltage, and the leakage loss of the back contact battery in the forward voltage area may be higher. On the contrary, along the first direction, the smaller the width of the first transparent conductive part set in the reverse leakage area, the larger the transmission resistance of the leakage current in the first transparent conductive part, the smaller the corresponding reduction in the reverse breakdown voltage, and the leakage loss of the back contact battery in the forward voltage area may be lower. Based on this, during the application process of the back contact battery provided by the present invention, it is only necessary to adjust the width W1 of the first transparent conductive portion 19 in the first direction and the width W2 of the overlapping area 17 in the first direction to adjust the leakage loss and the reverse breakdown voltage, thereby reducing the risk of hot spots of the back contact battery while making the back contact battery have a higher working efficiency in the forward voltage region. Moreover, in the actual manufacturing process, it is only necessary to fine-tune the selective etching pattern used when forming the transparent conductive layer 14, without changing other manufacturing processes of the back contact battery, thereby improving the compatibility of the back contact battery provided by the embodiment of the present invention with the existing manufacturing process and reducing the manufacturing difficulty of the back contact battery provided by the embodiment of the present invention.

[0091] In actual application, the embodiment of the present invention does not specifically limit the material and conductivity type of the semiconductor substrate. For example, the semiconductor substrate may be a silicon substrate. Alternatively, the semiconductor substrate may be a substrate made of any semiconductor material such as a germanium silicon substrate, a germanium substrate, or a gallium arsenide substrate.

[0092] Secondly, the semiconductor substrate includes a first surface and a second surface that are opposite to each other, the first surface of the semiconductor substrate corresponds to the backlight surface of the back contact battery, and the second surface of the semiconductor substrate corresponds to the light-facing surface of the back contact battery. Among them, the distribution of the first area, the second area and the overlapping area on the first surface can be determined according to the distribution of the first doped semiconductor part and the second doped semiconductor part formed on one side of the first surface. Specifically, since the first doped semiconductor part included in the back contact battery is arranged in the first area and the overlapping area, the distribution range of the first area and the overlapping area on the first surface can be determined according to the distribution requirements of the first doped semiconductor part in the actual application scenario. Since part of the area of ​​the second doped semiconductor part included in the back contact battery is arranged on the second area of ​​the first surface, the distribution range of the second area on the first surface can be determined according to the distribution requirements of the second doped semiconductor part on the semiconductor substrate in the actual application scenario.

[0093] It can be understood that the first region corresponds to the first emitter region, and the second region corresponds to the second emitter region; one of the first region and the second region is a P region, and the other is an N region, and the overlapping region is a PN overlapping region.

[0094] For example, the first region and the second region may be arranged alternately at intervals in a strip shape, or may be arranged alternately at intervals in a finger shape.

[0095] As for the arrangement direction of the first area, the overlapping area and the second area (i.e., the first direction), it can be determined according to the distribution of the first area, the second area and the overlapping area on the first surface, and is not specifically limited here. For example: when the first area and the second area are distributed alternately in strips, the first direction is parallel to the arrangement direction of the two adjacent strip areas. For another example: when the first area and the second area are distributed alternately in interdigitated shapes, the first direction is parallel to the arrangement direction of the two adjacent quasi-Feng-shaped areas.

[0096] In terms of surface morphology, Figure 1 and Figure 2 As shown, the first surface and the second surface of the semiconductor substrate 11 may be planes. Figure 3 As shown, the second surface of the semiconductor substrate 11 may also be a velvet surface to improve the light trapping effect of the second surface and improve the utilization rate of light by the semiconductor substrate 11. Secondly, the surface of the second region of the first surface may also be a velvet surface to increase the contact area between the second doped semiconductor portion 13 on the second region and the transparent conductive layer 14 on the second region, and to increase the contact area between the transparent conductive layer 14 on the second region and the corresponding electrode, which is conducive to reducing transmission loss.

[0097] For the first doped semiconductor portion, in terms of the conductivity type, the embodiment of the present invention does not specifically limit the conductivity type of the first doped semiconductor portion, as long as the conductivity types of the first doped semiconductor portion and the second doped semiconductor portion are opposite. Specifically, the conductivity type of the first doped semiconductor portion may be N-type, in which case the conductivity type of the second doped semiconductor portion is P-type; or the conductivity type of the first doped semiconductor portion may also be P-type, in which case the conductivity type of the second doped semiconductor portion is N-type.

[0098] In terms of the formation position, Figure 1 As shown, the first doped semiconductor portion 12 may be disposed on the first region 15 and the overlapping region 17 of the semiconductor substrate; or Figure 2 As shown, the first doped semiconductor portion 12 may also be disposed in the first region 15 and the overlapping region 17 of the semiconductor substrate. In this case, the first doped semiconductor portion 12 may be formed by diffusion or ion implantation.

[0099] When the first doped semiconductor portion is disposed on the first region and the overlapping region of the semiconductor substrate, the material of the first doped semiconductor portion may include any semiconductor material such as silicon, silicon germanium, germanium or gallium arsenide. In terms of the arrangement of the material, the crystal phase of the first doped semiconductor portion may be amorphous, microcrystalline, nanocrystalline, single crystal or polycrystalline.

[0100] Secondly, if Figure 1 As shown, the first doped semiconductor portion 12 may be directly disposed on the first region 15 and the overlapping region 17. Alternatively, as shown in FIG. Figure 3 As shown, the above-mentioned back contact cell may also include a first interface passivation layer 26 located between the first doped semiconductor part 12 and the semiconductor substrate 11. In this case, the passivation contact structure composed of the first interface passivation layer 26 and the first doped semiconductor part 12 has an excellent interface passivation effect, and can realize the selective collection of carriers, reduce the carrier recombination rate of the first region 15 and the overlapping region 17 of the first surface of the semiconductor substrate 11, and further improve the photoelectric conversion efficiency of the back contact cell. The material and thickness of the first interface passivation layer 26 can be set according to the material of the first doped semiconductor part 12 and actual needs, and are not specifically limited here. For example: when the material of the first doped semiconductor part is doped polycrystalline silicon, the first interface passivation layer is a tunneling passivation layer. For another example: when the material of the first doped semiconductor part includes at least one of doped amorphous silicon, doped microcrystalline silicon and doped nanocrystalline silicon, the first interface passivation layer is an intrinsic amorphous silicon layer, an intrinsic microcrystalline silicon layer, an intrinsic nanocrystalline silicon layer or a mixed layer of the above three.

[0101] Exemplarily, the thickness of the first doped semiconductor part can be greater than or equal to 50nm and less than or equal to 200nm. For example, the thickness of the first doped semiconductor part can be 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, 110nm, 120nm, 150nm, 180nm or 200nm, etc. In this case, the thickness of the first doped semiconductor part is within the above range, which can prevent the field passivation effect of the first doped semiconductor part from being low due to the small layer thickness of the first doped semiconductor part; it can also prevent the use of consumables for manufacturing the first doped semiconductor part from being large due to the large thickness of the first doped semiconductor part, which is beneficial to control the manufacturing cost of the back contact battery. In addition, the thickness of the first doped semiconductor part will affect the docking height between the side of the first doped semiconductor part and the side of the second doped semiconductor part, and then affect the junction area of ​​the PN junction formed between the first doped semiconductor part and the second doped semiconductor part in the reverse leakage region. Based on this, when the thickness of the first doped semiconductor part is within the above range, it can also prevent the leakage current of the first doped semiconductor part and the second doped semiconductor part in the side docking part from being large due to the larger docking height caused by the larger thickness of the first doped semiconductor part, and ensure that the leakage loss and reverse breakdown voltage of the back contact battery can be effectively regulated by adjusting the width W1 of the first transparent conductive part in the first direction and the width W2 of the overlapping area in the first direction, so that the back contact battery has higher working performance and working reliability.

[0102] For example, the doping concentration of the dopant in the first doped semiconductor portion may be greater than or equal to 1E19 cm -3 , and less than or equal to 5E20cm -3 For example, the doping concentration of the dopant in the first doped semiconductor portion may be 1E19 cm -3 、2E19cm -3 、4E19cm -3 、6E19cm -3 、8E19cm -3 、1E20cm -3 、3E20cm -3 or 5E20cm -3Etc. In this case, the doping concentration of the dopant in the first doped semiconductor part is within the above range, which can prevent the low field passivation effect on the semiconductor substrate due to the low doping concentration of the dopant in the first doped semiconductor part, and ensure that the first region and the overlapping region of the back contact battery have a relatively low carrier recombination rate under normal working conditions; at the same time, it is also beneficial to make the first doped semiconductor part have good conductivity, and ensure that the part of the first doped semiconductor part in the reverse leakage region has a relatively low transmission resistance when the back contact battery is blocked, which is further beneficial to reduce the reverse breakdown voltage of the back contact battery. In addition, it can also prevent the difficulty of doping the intrinsic semiconductor layer used to manufacture the first doped semiconductor part due to the high doping concentration of the dopant in the first doped semiconductor part, reduce the process difficulty, and help improve the yield of the back contact battery.

[0103] For the above-mentioned second doped semiconductor part, from the material aspect, the material of the second doped semiconductor part may include any semiconductor material such as silicon, silicon germanium, germanium or gallium arsenide. From the aspect of the arrangement of the material, the crystal phase of the second doped semiconductor part may be amorphous, microcrystalline, nanocrystalline, single crystal or polycrystalline, etc. As for the specific value of the crystallization rate of the second doped semiconductor part, it can be determined according to the actual application scenario and is not specifically limited here.

[0104] Exemplarily, the crystallization rate of the second doped semiconductor part can be less than or equal to 60%. For example: the crystallization rate of the second doped semiconductor part can be 0, 5%, 10%, 20%, 30%, 40%, 50% or 60%, etc. In this case, it can be understood that the crystallization rate of the second doped semiconductor part will affect its own conductivity, thereby affecting the leakage loss of the back contact battery in the reverse leakage area, and the reverse breakdown voltage of the back contact battery when it is blocked. Based on this, when the crystallization rate of the second doped semiconductor part is in the above range, the crystallization rate of the second doped semiconductor part has a larger optional range. At this time, in addition to regulating the leakage loss and reverse breakdown voltage of the back contact battery by adjusting the ratio range of W1 and W2, the total and precise regulation of the leakage loss and reverse breakdown voltage of the back contact battery can be achieved by adjusting the crystallization rate of the second doped semiconductor part, ensuring that the back contact battery has high working performance and working reliability.

[0105] In terms of conductivity, the conductivity of the second doped semiconductor portion directly affects its own conductivity. The conductivity of the second doped semiconductor portion affects the leakage loss of the back contact battery in the reverse leakage area and the reverse breakdown voltage of the back contact battery when it is blocked. Based on this, the conductivity between the first electrode 25 and the second doped semiconductor portion 13 can be determined according to the requirements for leakage loss and reverse breakdown voltage in actual application scenarios.

[0106] Exemplarily, the conductivity of the second doped semiconductor part is greater than or equal to 10E-5S / cm and less than or equal to 1S / cm. In this case, it is possible to prevent the back contact battery from having a large forward leakage loss due to the second doped semiconductor part having a large conductivity, and to prevent the back contact battery from having a high reverse breakdown voltage due to the second doped semiconductor part having a small conductivity, which is further conducive to achieving a balance between the reverse breakdown voltage and the working efficiency of the back contact battery.

[0107] In actual application, the conductive properties of different parts of the second doped semiconductor portion may be the same or different.

[0108] It can be understood that when the back contact battery is in normal working state, the part of the second doped semiconductor part located in the second area needs to collect and guide the carriers of the corresponding conductive type generated in the semiconductor substrate to facilitate the formation of photocurrent. The part of the second doped semiconductor part corresponding to the first transparent conductive layer is electrically connected to the first doped semiconductor part of the opposite conductive type (to reduce the risk of hot spots of the back contact battery). When the back contact battery is in normal working state, the part of the second doped semiconductor part corresponding to the first transparent conductive layer will have leakage current with the first doped semiconductor part. From the above content, it can be seen that the parts of the second doped semiconductor part located in different areas have different functions. Secondly, under the same other factors, when the degree of crystallization of the doped semiconductor part is smaller, the grains in the doped semiconductor part are smaller and / or the number of grains is smaller, and even the disorder of amorphous semiconductor materials is presented. The smaller the grains and / or the fewer the number of grains in the doped semiconductor part, the more interfaces between the grains in the doped semiconductor part, so the resistance of the grain interface will be larger. It can be seen that the degree of crystallization of the parts of the second doped semiconductor portion located in different areas will affect its own conductive properties. Therefore, the conductive properties and degree of crystallization of different parts of the second doped semiconductor portion can be determined according to the effects of the parts of the second doped semiconductor portion located in different areas in actual application scenarios, as well as the requirements for the conversion efficiency and hot spot risks of the back contact battery.

[0109] Illustratively, the degree of crystallization of at least a portion of the second doped semiconductor portion located in the second region may be greater than the degree of crystallization of a portion of the second doped semiconductor portion corresponding to the first transparent conductive portion.

[0110] It should be noted that the greater the degree of crystallization referred to in the embodiments of the present invention may refer to a greater crystallization rate, a larger grain size and / or a greater number of grains. For example: when the second doped semiconductor portion is a nanocrystalline silicon layer (the nanocrystalline silicon layer generally may still contain a part of amorphous silicon, which is difficult to avoid, and the content of the amorphous silicon portion is relatively small, which is known in the art), the degree of crystallization of at least a portion of the second doped semiconductor portion located in the second region is greater, and the portion has a greater crystallization rate and grain size than the portion of the second doped semiconductor portion corresponding to the first transparent conductive portion. For another example: when the second doped semiconductor portion is an amorphous silicon layer (the amorphous silicon layer may contain a small amount of nanocrystalline silicon, but the content of the nanocrystalline silicon portion is very small, for example, less than 5%, which is known in the art), the second doped semiconductor portion is located in at least a portion of the second region. The second doped semiconductor portion will generate lattice-ordered grains inside, so that its degree of crystallization is increased. The degree of crystallization of the portion of the second doped semiconductor portion corresponding to the first transparent conductive portion is smaller. At this time, the portion with a smaller degree of crystallization is still an amorphous silicon material, and there are no grains generated after laser treatment. In this case, the electrical conductivity of at least the portion of the second doped semiconductor portion located in the second region will be greater, which is conducive to reducing the transmission loss of at least the portion of the second doped semiconductor portion located in the second region, and reducing the contact resistance between at least the portion of the second doped semiconductor portion located in the second region and the transparent conductive layer. The crystallization degree of the portion of the second doped semiconductor portion corresponding to the first transparent conductive portion is relatively low, and the electrical conductivity of the portion of the second doped semiconductor portion corresponding to the first transparent conductive portion is relatively low, which is conducive to reducing the magnitude of the forward leakage current between the portion of the second doped semiconductor portion corresponding to the first transparent conductive layer and the first doped semiconductor portion, and further improving the conversion efficiency of the back contact battery.

[0111] In terms of range, only the portion of the second doped semiconductor portion located in the local range of the second region may have a relatively large degree of crystallization, or the portion of the second doped semiconductor portion located in the entire second region may have a relatively large degree of crystallization. The range of the portion with a relatively large degree of crystallization in the second doped semiconductor portion may be determined according to the method used in the actual manufacturing process to make different regions of the second doped semiconductor portion have different degrees of crystallization, and the actual manufacturing accuracy, and is not specifically limited here.

[0112] Secondly, the degree of crystallization of at least a portion of the second doped semiconductor portion located in the second region may be greater than the degree of crystallization of the portion of the second doped semiconductor portion corresponding to the first transparent conductive layer. It may also be that the degree of crystallization of at least a portion of the second doped semiconductor portion located in the second region is greater than the degree of crystallization of the portion of the second doped semiconductor portion located in the overlapping region. It may also be that the degree of crystallization of at least a portion of the second doped semiconductor portion located in the second region is not only greater than the degree of crystallization of the portion of the second doped semiconductor portion corresponding to the first transparent conductive portion, but also greater than the degree of crystallization of the portion of the second doped semiconductor portion covering the side wall, which is located at the junction of the overlapping region and the second region; in this case, it can be understood that, in the second doped semiconductor portion, the portion located on the side wall at the junction of the overlapping region and the second region is closer to the second region than the portion corresponding to the second region. Based on this, when the degree of crystallization of the portion of the second doped semiconductor portion covering the side wall at the junction of the overlapping region and the second region is relatively small, it is helpful to prevent the portion of the second doped semiconductor portion corresponding to the first transparent conductive portion from being affected during the crystallization modification of at least the portion of the second doped semiconductor portion corresponding to the second region by laser processing or the like during the actual manufacturing process, thereby ensuring that at least the portion of the second doped semiconductor portion corresponding to the first transparent conductive portion has a relatively small electrical conductivity, and effectively controlling the magnitude of the forward leakage current between the portion of the second doped semiconductor portion corresponding to the first transparent conductive portion and the first doped semiconductor portion.

[0113] In addition, it can be understood that the greater the degree of crystallization of at least a portion of the second doped semiconductor portion located in the second region, the greater the conductivity of the portion. The smaller the degree of crystallization of the portion of the second doped semiconductor portion corresponding to the first transparent conductive portion, the smaller the conductivity of the portion, and the higher the conversion efficiency of the back contact battery at this time. At the same time, the degree of reduction of the risk of hot spots will also be affected. Therefore, the difference between the degree of crystallization of at least a portion of the second doped semiconductor portion located in the second region and the degree of crystallization of the portion of the second doped semiconductor portion corresponding to the first transparent conductive portion can be determined according to the requirements for the conversion efficiency and hot spot risk of the back contact battery in the actual application scenario, and no specific limitation is made here.

[0114] Exemplarily, the difference between the crystallization rate of at least a portion of the second doped semiconductor portion located in the second region and the crystallization rate of the portion of the second doped semiconductor portion corresponding to the first transparent conductive portion may be greater than or equal to 40% and less than or equal to 80%. For example, the difference between the crystallization rate of at least a portion of the second doped semiconductor portion located in the second region and the crystallization rate of the portion of the second doped semiconductor portion corresponding to the first transparent conductive portion may be 40%, 42%, 45%, 50%, 55%, 60%, 65%, 70%, 75% or 80%, etc. In this case, the difference is within the above range, which is conducive to preventing the poor carrier collection efficiency of at least a portion of the second doped semiconductor portion located in the second region due to the small difference, and / or the high crystallization degree of the portion of the second doped semiconductor portion corresponding to the first transparent conductive portion, resulting in a large forward leakage current corresponding to the portion, thereby ensuring that the back contact battery has a high conversion efficiency. In addition, it can also prevent the high risk of hot spots in the back contact battery due to the large difference causing the second doped semiconductor part corresponding to the first transparent conductive part to have a lower degree of crystallization, thereby ensuring that the back contact battery has a higher ability to resist burning.

[0115] In actual application, the second doped semiconductor part may also include a high crystallization region and a low crystallization region; the crystallization degree of the portion of the second doped semiconductor part located in the low crystallization region is less than the crystallization degree of the portion of the second doped semiconductor part located in the high crystallization region. Based on this, in the second doped semiconductor part, at least the portion corresponding to the first transparent conductive part is located in the low crystallization region, and at least the portion corresponding to the second region is located in the high crystallization region. The application principle of the beneficial effect in this case is similar to the application principle of the beneficial effect described above that the crystallization degree of at least the portion of the second doped semiconductor part located in the second region is greater than the crystallization degree of the portion of the second doped semiconductor part corresponding to the first transparent conductive part, and will not be repeated here.

[0116] Among them, in terms of scope, the scope of the high crystallization area and the low crystallization area in the second doped semiconductor part can be determined according to the method used in the actual manufacturing process to make different regions of the second doped semiconductor part have different degrees of crystallization, and the actual manufacturing accuracy, and is not specifically limited here.

[0117] Specifically, the low crystallization region may be located in the overlapping region. In this case, the low crystallization region of the second doped semiconductor portion may correspond only to the portion of the second doped semiconductor portion corresponding to the first transparent conductive portion; or the low crystallization region may correspond to the entire overlapping region. The high crystallization region of the second doped semiconductor portion may correspond only to the portion of the second doped semiconductor portion located in a local area of ​​the second region; or the high crystallization region may correspond to the entire second region; or the high crystallization region may correspond not only to at least a portion of the second doped semiconductor portion located in the second region, but also to a portion of the second doped semiconductor portion located on the sidewall at the junction of the second region and the overlapping region.

[0118] Alternatively, along the first direction, one side edge of the low crystallization region is located in the overlapping region, and the other side edge extends to the side wall, and the side wall is located at the junction of the overlapping region and the second region. In this case, the high crystallization region of the second doped semiconductor portion may correspond to at least a partial portion of the second doped semiconductor portion located in the second region.

[0119] Alternatively, along the first direction, one side edge of the low crystallization region is located in the overlapping region, and the other side edge extends to the second region. In this case, the portion of the second doped semiconductor portion located in the high crystallization region only corresponds to the portion of the second doped semiconductor portion located in a local range of the second region.

[0120] In the case of adopting the above technical solution, since at least part of the overlapping region is the reverse leakage region, when the above low crystallization region is located in the overlapping region, it can ensure that the conductivity of the part of the second doped semiconductor part located in the reverse leakage region is relatively small, effectively control the magnitude of the forward leakage current between the second doped semiconductor part and the first doped semiconductor part in the reverse leakage region, and help improve the conversion efficiency of the back contact battery. In addition, when along the first direction, one side edge of the above low crystallization region is located in the overlapping region and the other side edge extends to the side wall located at the junction of the overlapping region and the second region, or when along the first direction, one side edge of the above low crystallization region is located in the overlapping region and the other side edge extends to the second region, it is beneficial to prevent the above operation from affecting the second doped semiconductor part located in the overlapping region while making at least part of the second region corresponding to the second region located in the high crystallization region by laser processing or the like, and ensure that the part of the second doped semiconductor part located in the overlapping region has a smaller conductivity while reducing the requirements for the processing accuracy. In addition, when the high crystallization region corresponds to the entire second region, the portion of the second doped semiconductor portion corresponding to the entire second region has a relatively high conductivity, so that the portion of the second doped semiconductor portion corresponding to the entire second region has a high carrier collection efficiency, thereby improving the working efficiency of the back contact battery. In addition, there are multiple examples of the division range of the low crystallization region and the high crystallization region in the second doped semiconductor portion, which is conducive to reducing the difficulty of the process and can also improve the applicability of the back contact battery provided by the embodiment of the present invention in different application scenarios.

[0121] As for the difference in the degree of crystallization between the low crystallization area and the high crystallization area in the second doped semiconductor part, it can be determined according to the requirements for the conversion efficiency and hot spot risk of the back contact battery in the actual application scenario. Specifically, the difference between the degree of crystallization of at least a portion of the second doped semiconductor part located in the second region and the degree of crystallization of the portion of the second doped semiconductor part corresponding to the first transparent conductive part can be referred to as described above, and will not be repeated here.

[0122] From the doping aspect, the embodiment of the present invention does not impose any specific limitation on the doping concentration of the dopant in the second doped semiconductor portion, as long as it can be applied to the back contact battery provided by the embodiment of the present invention.

[0123] For example, the doping concentration of the dopant in the second doped semiconductor portion may be greater than or equal to 1E19 cm -3 , and less than or equal to 5E20cm -3 For example, the doping concentration of the dopant in the second doped semiconductor portion may be 1E19 cm -3 、2E19cm -3 、4E19cm -3 、6E19cm -3 、8E19cm -3 、1E20cm -3 、3E20cm -3 or 5E20cm -3 Etc. In this case, the doping concentration of the dopant in the second doped semiconductor part is within the above range, which can prevent the low field passivation effect on the semiconductor substrate due to the low doping concentration of the dopant in the second doped semiconductor part, and ensure that the second region of the back contact battery has a relatively low carrier recombination rate under normal working conditions; at the same time, it is also beneficial to make the second doped semiconductor part have good conductivity, ensuring that the part of the second doped semiconductor part in the reverse leakage region has a relatively low transmission resistance when the back contact battery is blocked, which is further beneficial to reduce the reverse breakdown voltage of the back contact battery. In addition, it can also prevent the difficulty of doping the intrinsic semiconductor layer used to manufacture the second doped semiconductor part due to the high doping concentration of the dopant in the second doped semiconductor part, which is beneficial to improve the yield of the back contact battery.

[0124] In terms of layer thickness, the embodiment of the present invention does not specifically limit the thickness of the second doped semiconductor portion. Exemplarily, the thickness of the second doped semiconductor portion may be greater than or equal to 5nm and less than or equal to 50nm. For example, the thickness of the second doped semiconductor portion may be 5nm, 10nm, 15nm, 20nm, 30nm, 40nm or 50nm. The application principle of the beneficial effect in this case is the same as the application principle of the beneficial effect of the first doped semiconductor portion having a thickness greater than or equal to 50nm and less than or equal to 200nm as described above, and will not be repeated here.

[0125] In terms of the formation position, Figure 1 and Figure 2 As shown, the second doped semiconductor portion 13 may be directly disposed on the second region 16 and extend to cover the first doped semiconductor portion 12 in the overlapping region 17. Alternatively, as Figure 3As shown, the above-mentioned back contact battery may also include a second interface passivation layer 27, which is located between the second region 16 and the second doped semiconductor part 13 of the first surface, and extends between the second doped semiconductor part and the first doped semiconductor part. In this case, the passivation contact structure composed of the second interface passivation layer 27 and the part of the second doped semiconductor part 13 located on the second region 16 can realize the selective collection of carriers and reduce the carrier recombination rate of the second region 16 of the first surface of the semiconductor substrate 11. The material and thickness of the second interface passivation layer 27 can be set according to the material of the second doped semiconductor part 13 and actual needs, and are not specifically limited here. For example: when the material of the second doped semiconductor part is doped polycrystalline silicon, the second interface passivation layer is a tunneling passivation layer. For another example: when the material of the second doped semiconductor part includes doped amorphous silicon, doped microcrystalline silicon and doped nanocrystalline silicon, the second interface passivation layer is an intrinsic amorphous silicon layer, an intrinsic microcrystalline silicon layer, an intrinsic nanocrystalline silicon or a mixed layer of the above three.

[0126] As for the thickness of the second interface passivation layer, since the thickness of the second interface passivation layer will affect its own transmission resistance and passivation effect, and thus affect the forward leakage loss and reverse breakdown voltage of the back contact battery, the thickness of the second interface passivation layer can be determined according to the requirements for the forward leakage loss and reverse breakdown voltage of the back contact battery in the actual application scenario, and no specific limitation is made here.

[0127] Exemplarily, the thickness of the second interface passivation layer may be greater than or equal to 2nm and less than or equal to 20nm. For example, the thickness of the second interface passivation layer may be 2nm, 5nm, 8nm, 10nm, 12nm, 15nm, 18nm or 20nm, etc. In this case, based on this, the thickness of the second interface passivation layer is within the above range, which is conducive to preventing the second interface passivation layer from having a poor passivation effect on the second region due to its small thickness, and ensuring that the surface of the second region has a low carrier recombination rate. It can also prevent the second interface passivation layer from having a large transmission resistance due to its large thickness, which leads to a low carrier collection efficiency of the second doped semiconductor part under normal operation of the back contact battery, and a small reduction in the reverse breakdown voltage when the back contact battery is blocked, which is further conducive to achieving a balance between the reverse breakdown voltage and the working efficiency corresponding to the back contact battery.

[0128] In addition, the doping concentration of the dopant in the first doped semiconductor part will affect its own conductivity. Specifically, within a certain range, the higher the doping concentration of the dopant in the first doped semiconductor part, the higher the conductivity of the first doped semiconductor part; on the contrary, the lower the doping concentration of the dopant in the first doped semiconductor, the lower the conductivity of the first doped semiconductor part. As for the above-mentioned second interface passivation layer, as mentioned above, the thickness of the second interface passivation layer is related to its own passivation effect and transmission resistance. When the thickness of the second interface passivation layer is small, the leakage current between the first doped semiconductor part and the second doped semiconductor part is larger in the reverse leakage region. When the thickness of the second interface passivation layer is larger, the leakage loss in the forward voltage region of the back contact battery is lower, but the transmission resistance of the second interface passivation layer is larger. Based on this, the thickness of the second interface passivation layer that matches it can also be determined according to the range of the doping concentration of the dopant in the first doped semiconductor part in the actual application scenario.

[0129] For example, when the doping concentration of the dopant in the first doped semiconductor portion is greater than or equal to 1E19 cm -3 , and less than or equal to 5E19cm -3 When the thickness of the second interface passivation layer is greater than or equal to 5 nm and less than or equal to 15 nm, the thickness of the second interface passivation layer can be greater than or equal to 5 nm and less than or equal to 15 nm. -3 , and less than or equal to 5E19cm -3 When the thickness of the second interface passivation layer is 5 nm, 8 nm, 10 nm, 12 nm, 14 nm or 15 nm, etc.

[0130] Alternatively, when the doping concentration of the dopant in the first doped semiconductor portion is greater than 5E19 cm -3 , and less than or equal to 1E20cm -3 When the thickness of the second interface passivation layer is greater than or equal to 6 nm and less than or equal to 17 nm, the thickness of the second interface passivation layer can be greater than or equal to 6 nm and less than or equal to 17 nm. -3 , and less than or equal to 1E20cm -3 When the thickness of the second interface passivation layer is 6 nm, 8 nm, 9 nm, 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, 16 nm or 17 nm, etc.

[0131] Alternatively, when the doping concentration of the dopant in the first doped semiconductor portion is greater than 1E20 cm -3 , and less than or equal to 5E20cm -3 When the thickness of the second interface passivation layer is greater than or equal to 7 nm and less than or equal to 20 nm, the thickness of the second interface passivation layer can be greater than or equal to 7 nm and less than or equal to 20 nm. -3 , and less than or equal to 5E20cm-3 When the thickness of the second interface passivation layer is 7 nm, 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 16 nm, 18 nm or 20 nm, etc.

[0132] It is worth noting that the back-contact battery provided in the embodiment of the present invention is provided with a second interface passivation layer with corresponding thickness according to the different doping concentrations of the dopant in the first doped semiconductor part, so as to achieve reasonable regulation of the working efficiency and reverse breakdown voltage of the back-contact battery, thereby ensuring that the back-contact battery has higher working performance and working reliability.

[0133] In addition, when the back contact cell includes a first interface passivation layer and a second interface passivation layer, the first interface passivation layer and the first doped semiconductor portion constitute a first passivation contact structure, and the second interface passivation layer and the second doped semiconductor portion constitute a second passivation contact structure.

[0134] Among them, the passivation contact types of the first passivation contact structure and the second passivation contact structure can be the same. For example: the first passivation contact structure and the second passivation contact structure are both tunneling passivation contact structures or heterogeneous contact structures. Alternatively, the passivation contact types of the first passivation contact structure and the second passivation contact structure can also be different. For example: one of the first passivation contact structure and the second passivation contact structure is a tunneling passivation contact structure, and the other is a heterogeneous contact structure. In this case, when the passivation contact types of the first passivation contact structure and the second passivation contact structure are different, the passivation contact types of the first passivation contact structure and the second passivation contact structure can be adjusted respectively according to different actual application scenario requirements to improve the applicability of the back contact battery provided by the embodiment of the present invention in different application scenarios.

[0135] Secondly, the thermal stability of the above-mentioned first passivation contact structure can be greater than the thermal stability of the second passivation contact structure. In this case, in the actual manufacturing process, after the first passivation contact structure is formed in the first region and the overlapping region, and the second passivation contact structure with a whole layer is formed, it is usually necessary to use a laser processing process to pattern the mask material with the whole layer set to form a mask layer for selectively etching the second passivation contact structure. In order to process all parts of the mask material corresponding to the first region, the heat of the processing laser radiation will be conducted to the first passivation contact structure. Because the heat of the laser is relatively high, when the first passivation contact structure has a higher thermal stability, the influence of the heat of the laser radiation on the first passivation contact structure can be reduced, and the heat of the laser radiation will not even affect the first passivation contact structure, thereby improving the yield of the back contact battery. The portion of the second passivation contact structure corresponding to the first area needs to be removed, and the laser processing process has a high precision. Therefore, the portion of the second passivation contact structure corresponding to the overlapping area and the second area will not be affected by heat, or the thermal impact will be small. At this time, the manufacturing process has lower requirements on the thermal stability of the second passivation contact structure, and the thermal stability of the second passivation contact structure can be set to be lower than the thermal stability of the first passivation contact structure.

[0136] Of course, the first passivation contact structure and the second passivation contact structure may also have substantially the same thermal stability. Alternatively, in the actual manufacturing process, if the laser processing process is not used to pattern the mask material, but other low-temperature processes are used to selectively etch the mask material and the second passivation contact structure, the first passivation contact structure may also have relatively low thermal stability.

[0137] As for the specific types of the first passivation contact structure and the second passivation contact structure, they can be determined according to actual needs and are not specifically limited here.

[0138] Exemplarily, the first passivation contact structure may be a tunneling passivation contact structure. In this case, since amorphous silicon materials are easy to form polycrystalline silicon or monocrystalline silicon at high temperatures, and the chemical properties of tunneling passivation materials and polycrystalline silicon at high temperatures are relatively stable, compared with heterogeneous contact structures, tunneling passivation contact structures are less sensitive to high-temperature laser thermal damage, and can reduce the impact on the passivation effect during the laser processing process, further increasing the process window and reducing the process difficulty. In addition, in the actual manufacturing process, the manufacturing cost of the heterogeneous contact structure is higher than that of the tunneling passivation contact structure, and the tunneling passivation contact structure can be realized by a variety of processes such as low-pressure chemical vapor deposition, plasma chemical vapor deposition, physical chemical vapor deposition or plasma enhanced atomic layer deposition, which is easier to be compatible with the back contact battery process, while the heterogeneous contact structure needs to be manufactured using a plate-type plasma chemical vapor deposition device that supports a lower formation temperature. Based on this, when the first passivation contact structure is a tunneling passivation contact structure, it is beneficial to reduce the manufacturing cost, reduce the investment in plate-type plasma chemical vapor deposition equipment, and save production site area.

[0139] Exemplarily, the second passivation contact structure may be a heterogeneous contact structure. In this case, the heterogeneous contact structure has a passivation effect that is superior to that of the tunneling passivation contact structure. Therefore, when the second passivation contact structure is a heterogeneous contact structure, the carrier recombination rate at the interface between the semiconductor substrate and the second interface passivation layer can be further reduced, which is beneficial to improving the photoelectric conversion efficiency of the back contact battery. Specifically, the material of the intrinsic semiconductor passivation layer in the heterogeneous contact structure may include at least one of intrinsic amorphous silicon, intrinsic microcrystalline silicon, and intrinsic nanocrystalline silicon. The material of the doped semiconductor layer in the heterogeneous contact structure may include at least one of doped amorphous silicon, doped microcrystalline silicon, and doped nanocrystalline silicon.

[0140] It should be noted that the materials of the passivation contact structures of different passivation contact types are different, and the conductive properties of doped semiconductor materials of different conductive types are different. Therefore, the conductive type of the second passivation contact structure can be determined according to the passivation contact types of the first passivation contact structure and the second passivation contact structure.

[0141] Preferably, when the first passivation contact structure is a tunneling passivation contact structure and the second passivation contact structure is a heterogeneous contact structure, the conductivity type of the first passivation contact structure is N-type, and the second passivation contact structure is P-type. In this case, compared with P-type doped amorphous silicon or P-type doped microcrystalline silicon material, the contact resistance between the P-type doped polycrystalline silicon material and the electrode is higher and the field passivation effect is poorer. Therefore, when the conductivity type of the tunneling passivation contact structure is set to N-type and the conductivity type of the heterogeneous contact structure is set to P-type, the field passivation effect of the first tunneling passivation contact structure can be further improved, and the contact resistance between the first tunneling passivation contact structure and the electrode can be reduced, which is conducive to improving the electrical performance of the back contact battery.

[0142] For the above-mentioned transparent conductive layer, the embodiment of the present invention does not specifically limit the material and thickness of the transparent conductive layer. Exemplarily, the material of the transparent conductive layer may include at least one of fluorine-doped tin oxide, aluminum-doped zinc oxide, tin-doped indium oxide, tungsten-doped indium oxide, molybdenum-doped indium oxide, cerium-doped indium oxide and indium hydroxide.

[0143] Exemplarily, the thickness of the transparent conductive layer may be greater than or equal to 10 nm and less than or equal to 100 nm.

[0144] As for the insulating groove provided in the transparent conductive layer, the insulating groove is used to physically insulate the portion of the transparent conductive layer corresponding to the first area from the portion of the transparent conductive layer corresponding to the second area. Specifically, because the portion of the transparent conductive layer corresponding to the first area is ohmically connected to the first electrode, and the portion of the transparent conductive layer corresponding to the second area is ohmically connected to the second electrode, the two portions of the transparent conductive layer cannot be directly electrically connected, that is, the two portions of the transparent conductive layer must be physically insulated, that is, not in contact. Based on this, it can be understood that in order to prevent short circuits, the positions of both ends of the insulating groove can be located in the overlapping area, or the position of one end along the first direction can be located outside the overlapping area (of course, it can be understood that the reverse leakage area is excluded, because in the reverse leakage area, the transparent conductive layer must extend from the second area into the overlapping area).

[0145] In addition, if Figures 1 to 3 As shown, the insulating groove 18 may only penetrate the transparent conductive layer 14. Figure 4 As shown, when the second doped semiconductor portion 13 has a relatively low resistivity (such as the resistivity of the second doped semiconductor portion 13 is less than or equal to 0.01Ω·cm, specifically, when the second doped semiconductor portion 13 is a doped polysilicon layer and / or a doped single crystal silicon layer), the above-mentioned insulating groove 18 needs to penetrate not only the transparent conductive layer 14, but also needs to penetrate at least the second doped semiconductor portion 13, so as to prevent a short circuit caused by the electrical connection of the portion of the transparent conductive layer 14 corresponding to the first region 15 and the second region 16 through the second doped semiconductor portion 13 continuously arranged in the overlapping region 17. If the above-mentioned second interface passivation layer exists, in general, the second interface passivation layer does not need to be disconnected at the insulating groove; of course, in some processes, the second doped semiconductor portion 13 and the second interface passivation layer can also be disconnected together in the same process step).

[0146] As for the width of the insulating groove along the first direction, its range will not only affect the electrical insulation effect between the portions of the transparent conductive layer corresponding to the first area and the second area, but also affect the width of the first transparent conductive portion jointly arranged on the overlapping area along the first direction, thereby affecting the leakage loss and reverse breakdown voltage of the back contact battery. Therefore, it is set according to actual needs, as long as the ratio of the width W1 of the first transparent conductive portion in the first direction to the width W2 of the overlapping area in the first direction is greater than or equal to 10% and less than or equal to 90%.

[0147] Specifically, the ratio of the width W1 of the first transparent conductive portion in the first direction to the width W2 of the overlapping region in the first direction may be any value greater than or equal to 10% and less than or equal to 90%. For example, the ratio of W1 to W2 may be 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80% or 90%, etc.

[0148] Secondly, the cross-sectional areas of different regions of the insulating groove along the thickness direction of the semiconductor substrate may be the same. Alternatively, the cross-sectional area of ​​the insulating groove gradually decreases in the direction close to the semiconductor substrate. Specifically, when the cross-sectional area of ​​the insulating groove gradually decreases in the direction close to the semiconductor substrate, it may be gradually reduced in a linear manner, or it may be gradually reduced in other ways such as a parabola. In this way, the cross-sectional area at the bottom of the insulating groove is smaller than the cross-sectional area at the notch of the insulating groove, and the thickness of the end of the transparent conductive layer close to the insulating groove gradually increases in the direction away from the insulating groove. Based on this, especially for the reverse leakage area, the leakage current flows from the edge of the transparent conductive layer to the corresponding electrode. At this time, the density of the leakage current at the edge of the transparent conductive layer is small, and almost all the leakage current in the part of the transparent conductive layer away from its own edge area will pass through here, so the leakage current density of the part of the transparent conductive layer away from its own edge area is large. In the above case, when the thickness of the end of the transparent conductive layer close to the insulating groove gradually increases in the direction away from the insulating groove, the thickness of the part of the transparent conductive layer away from its own edge area is large, which is more conducive to the transmission of leakage current and is conducive to further reducing the risk of hot spots of back contact batteries.

[0149] In addition, in the transparent conductive layer, the thickness of each region along the first direction of the portion where the orthographic projection on the first surface does not overlap with the orthographic projection of the insulating groove on the first surface can be the same. In this case, it is beneficial to make each region along the first direction of the portion of the transparent conductive layer away from its own edge region have a larger thickness, which is not only beneficial to the transmission of leakage current when the back contact battery is blocked, but also beneficial to the back contact battery to extract the photocurrent generated in the forward voltage region, further improving the working performance of the back contact battery and reducing the risk of hot spots.

[0150] Alternatively, in the transparent conductive layer, the thickness of each region along the first direction of the portion whose orthographic projection on the first surface does not overlap with the orthographic projection of the insulating groove on the first surface may also be the same. For example, when the conductivity of the first doped semiconductor portion and the second doped semiconductor portion is different, the thickness of the transparent conductive layer disposed on one of the first doped semiconductor portion and the second doped semiconductor portion where the conductivity intersects may be greater than the thickness of the transparent conductive layer disposed on the other.

[0151] Secondly, if Figures 1 to 4 As shown, the portion of the transparent conductive layer 14 extending from the first region 15 into the overlapping region 17 is defined as the second transparent conductive portion 20. It can be understood that under the spacing effect of the insulating groove 18, the leakage current will only pass through the first doped semiconductor portion 12 in the reverse leakage region and be conducted through the second doped semiconductor portion 13 to the first transparent conductive portion 19 of the opposite conductivity type to the first doped semiconductor portion 12, so the existence of the second transparent conductive portion 20 has a low or even no effect on the reverse breakdown voltage. However, the first transparent conductive portion 19, the second transparent conductive portion 20 and the insulating groove 18 are all arranged in the overlapping region 17. In order to separate the portions of the transparent conductive layer 14 corresponding to the first region 15 and the second region 16, the width of the insulating groove 18 in the first direction needs to be greater than or equal to the minimum spacing for preventing leakage. Based on this, the width of the second transparent conductive portion 20 along the first direction will indirectly affect the leakage loss and reverse breakdown voltage of the back contact battery, so the width of the second transparent conductive portion 20 along the first direction can be set according to actual needs, and is not specifically limited here.

[0152] Exemplarily, the width of the second transparent conductive portion in the first direction is W3, and the ratio of W3 to W2 may be less than or equal to 80%. For example, the width of the second transparent conductive portion in the first direction is W3, and the ratio of W3 to W2 may be 0, 10%, 20%, 30%, 40%, 50%, 60%, 70% or 80%, etc. In this case, the width of the second transparent conductive portion in the first direction is W3, and the ratio of W3 to W2 has a large optional range. By adjusting the width of the second transparent conductive portion in the first direction, the width of the first transparent conductive portion in the first direction can be indirectly adjusted, which is further conducive to balancing the reverse breakdown voltage and working efficiency corresponding to the back contact battery.

[0153] In actual application, the embodiment of the present invention can adjust the contact area between the first transparent conductive part and the second doped semiconductor part by adjusting the ratio of the width W1 of the first transparent conductive part in the first direction to the width W2 of the overlapping area in the first direction, thereby adjusting the forward leakage loss and reverse breakdown voltage of the back contact battery. The size of the contact area between the first transparent conductive part and the second doped semiconductor part is not only related to the width W1 of the first transparent conductive part in the first direction, but also to the distribution of the reverse leakage area along the second direction.

[0154] Specifically, Figure 5 As shown, the reverse leakage region can be continuously distributed along the second direction, and the second direction intersects with the first direction. In this case, the extension length of the first transparent conductive portion 19 along the second direction is fixed, and the contact area between the first transparent conductive portion 19 and the second doped semiconductor portion is related to W1. Secondly, at this time, the portion of the transparent conductive layer extending from the second region into the overlapping region (i.e., the first transparent conductive portion 19) can be continuously distributed along the second direction, so that the pattern (only the pattern corresponding to the notch of the insulating groove) of the entire layer of transparent conductive material (the transparent conductive material is used to manufacture the above-mentioned transparent conductive layer) disposed on the first doped semiconductor portion and the second doped semiconductor portion is relatively simple, which is conducive to reducing the difficulty of patterning of the back contact battery. At the same time, when the reverse leakage region is continuously distributed along the second direction, the leakage path between the first doped semiconductor portion and the second doped semiconductor portion is more evenly distributed, so as to facilitate the heat generated when the back contact battery is blocked to be evenly distributed in the entire battery area, further improving the anti-burning ability of the back contact battery. It should be noted that the second direction can be any direction parallel to the first surface and different from the first direction. Preferably, the second direction is orthogonal to the first direction.

[0155] Or, if Figure 6As shown, the reverse leakage region can also be distributed discontinuously along the second direction, and the second direction intersects with the first direction. In addition, along the second direction, the first transparent conductive portion 19 has a continuous region 21 and a discontinuous region 22. That is, the continuous region of the first transparent conductive portion 19 is also the reverse leakage region, and the discontinuous region is the region between two adjacent reverse leakage regions; in this case, another implementation method is provided for the distribution of the first transparent conductive portion 19 along the second direction. At this time, the contact area between the first transparent conductive portion 19 and the second doped semiconductor portion is not only related to W1, but also to the length of the continuous region 21 and the discontinuous region 22 of the first transparent conductive portion 19 along the second direction. Based on this, not only can the reverse breakdown voltage and forward leakage loss of the back contact battery be regulated by adjusting the width of the first transparent conductive portion 19 along the first direction, but also the reverse breakdown voltage and forward leakage loss of the back contact battery can be regulated by adjusting the length of the continuous area 21 and the discontinuous area 22 of the first transparent conductive portion 19 along the second direction, thereby improving the applicability of the back contact battery provided by the embodiment of the present invention in different application scenarios. It should be noted that the above-mentioned second direction can be any direction parallel to the first surface and different from the first direction. Preferably, the second direction is orthogonal to the first direction.

[0156] In the case of the above content, according to actual needs, the ratio of W1 and W2 that affects the contact area between the first transparent conductive part and the second doped semiconductor part, as well as the distribution of the reverse leakage area along the second direction can be comprehensively adjusted to achieve precise control of the forward leakage loss and reverse breakdown voltage of the back-contact battery in actual application scenarios.

[0157] Exemplarily, when the reverse leakage region is continuously distributed along the second direction, the ratio of W1 to W2 can be greater than or equal to 10% and less than or equal to 70%. In this case, it is helpful to prevent the reverse breakdown voltage from being reduced due to the small ratio of W1 to W2, which makes the contact area between the first transparent conductive part and the second doped semiconductor part smaller; in addition, it can also prevent the forward leakage loss from being higher due to the large ratio of W1 to W2, which makes the contact area between the first transparent conductive part and the second doped semiconductor part larger, further facilitating the balance between the reverse breakdown voltage and the working efficiency of the back contact battery.

[0158] Exemplarily, in the case where the reverse leakage area is intermittently distributed along the second direction, the ratio of the length of the discontinuous area to the length of the continuous area along the second direction may be less than or equal to 90%. For example, the ratio of the length of the discontinuous area to the length of the continuous area may be 1%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80% or 90%, etc. In this case, when the back contact battery provided by the embodiment of the present invention is set in an installation environment with fewer obstructions such as bird droppings, leaves or dust, the ratio of the length of the discontinuous area to the length of the continuous area may be set within a larger range to increase the proportion of the discontinuous area in the reverse leakage area, thereby facilitating the reduction of the leakage loss of the back contact battery in the forward voltage area, and ensuring that the back contact battery has a higher working efficiency. When the back-contact battery provided by the embodiment of the invention is installed in an environment with many obstructions such as bird droppings, leaves or sand and dust, the ratio of the length of the discontinuous area to the length of the continuous area can be set within a smaller range to increase the proportion of the continuous area in the reverse leakage area, thereby facilitating the reduction of the reverse breakdown voltage of the back-contact battery and ensuring that the back-contact battery has a lower risk of hot spots. It can be seen that along the second direction, when the ratio of the length of the discontinuous area to the length of the continuous area is less than or equal to 90%, the length of the discontinuous area and the length of the continuous area can be set according to different environmental requirements, thereby improving the applicability of the back-contact battery provided by the embodiment of the invention in different practical application scenarios.

[0159] Exemplarily, when the reverse leakage area is intermittently distributed along the second direction, the ratio of W1 to W2 is greater than or equal to 20% and less than or equal to 90%. Such a setting can improve the applicability of the back contact battery provided by the present invention in different practical application scenarios. Specifically, the application principle of the beneficial effect in this case is similar to the application principle of the beneficial effect of the ratio of W1 to W2 being greater than or equal to 10% and less than or equal to 70% when the reverse leakage area is continuously distributed along the second direction, and will not be repeated here.

[0160] Exemplarily, when the reverse leakage area is intermittently distributed along the second direction, the ratio of the width of the continuous area to the length of the continuous area is greater than or equal to 1:500 and less than or equal to 5:1. Such a setting can improve the applicability of the back contact battery provided by the present invention in different practical application scenarios. Specifically, the application principle of the beneficial effect in this case is similar to the application principle of the beneficial effect of the ratio of W1 to W2 being greater than or equal to 10% and less than or equal to 70% when the reverse leakage area is continuously distributed along the second direction as described above, and will not be repeated here.

[0161] Secondly, in the actual application process, such as Figures 5 to 7 As shown in FIG. 1 , the portion of the transparent conductive layer disposed in the second region is defined as the third transparent conductive portion 23. Based on this, when the reverse leakage region is intermittently distributed along the second direction, as shown in FIG. Figure 6 As shown, the third transparent conductive portion 23 may completely cover the portion of the second doped semiconductor portion corresponding to the second region. Figure 7 As shown, the portion of the third transparent conductive portion 23 corresponding to the discontinuous region 22 may also be provided with a notch 24. In this case, the second doped semiconductor portion is not only arranged on the second region, but also extends to cover the first doped semiconductor portion on the overlapping region. At this time, the second doped semiconductor portion can not only be located on the side of the first doped semiconductor portion on the overlapping region away from the semiconductor substrate, but also on the sidewall of the first doped semiconductor portion on the overlapping region. In addition, the transparent conductive layer is located on the first doped semiconductor portion and the second doped semiconductor portion. At this time, the transparent conductive layer can contact the second doped semiconductor portion on the sidewall of the first doped semiconductor portion arranged on the overlapping region. In this case, when the portion of the transparent conductive layer disposed in the second region (i.e., the third transparent conductive portion 23) corresponding to the portion of the discontinuous region 22 is provided with a notch 24, it can be ensured that the third transparent conductive portion 23 will not be electrically connected to the second doped semiconductor portion in the discontinuous region 22, and it can be ensured that the contact area between the second doped semiconductor portion and the transparent conductive layer in the reverse leakage region can be effectively adjusted by adjusting the length of the discontinuous region 22 and the continuous region 21 of the first transparent conductive portion 19 along the second direction, so as to achieve precise control of the reverse breakdown voltage and forward leakage loss of the back contact battery. At the same time, in the actual application manufacturing process, it is necessary to selectively etch the first transparent conductive portion 19 to achieve discontinuous distribution of the reverse leakage region along the second direction. Based on this, when the portion of the third transparent conductive portion 23 adjacent to the first transparent conductive portion 19 corresponding to the discontinuity zone 22 is provided with a notch 24, there is no need to strictly control the etching accuracy in order to achieve the above-mentioned selective etching in order to precisely stop at the junction of the first transparent conductive portion 19 and the third transparent conductive portion 23 during the etching process of the first transparent conductive portion 19, which is beneficial to reducing the manufacturing difficulty of the back contact battery.

[0162] Specifically, in the case where the first transparent conductive part has multiple discontinuous areas along the second direction, the third transparent conductive part may be provided with a notch only in the portion corresponding to the individual discontinuous areas, or the third transparent conductive part may also be provided with a notch in the portion corresponding to each discontinuous area. As for the size of the notch, it can be understood that in the transparent conductive layer, the portion (i.e., the third transparent conductive part) arranged on the side of the second doped semiconductor part away from the semiconductor substrate needs to lead the carriers collected in the portion of the second doped semiconductor part corresponding to the second area to the corresponding electrode when the back contact battery is in a working state, and can reduce the contact barrier between the second doped semiconductor part and the corresponding electrode, thereby reducing the carrier transmission loss. Based on this, the width of the notch along the first direction can be determined according to the requirements for the transmission loss of carriers, the regulation of leakage current, and the actual manufacturing process in the actual application scenario, and is not specifically limited here.

[0163] Exemplarily, the width of the notch in the first direction may be less than or equal to 100 μm. For example, the width of the notch in the first direction may be 1 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 80 μm or 100 μm, etc. In this case, based on this, when the portion of the third transparent conductive portion corresponding to the spacer is provided with a notch, the carriers collected by the portion of the second doped semiconductor portion corresponding to the notch need to be transmitted to the third transparent conductive portion through the adjacent portion, and at this time, the transmission loss of the carriers collected by the portion of the second doped semiconductor portion corresponding to the notch is relatively high. In this case, when the width of the notch in the first direction is less than or equal to 100 μm, the range of the notch is relatively small, which is conducive to reducing the difficulty of selective etching while controlling the transmission loss of the carriers collected in the second doped semiconductor portion within a certain range, thereby ensuring that the back contact battery has a high photoelectric conversion efficiency.

[0164] In one example, if Figures 1 to 4 As shown, the back contact cell further includes a first electrode 25 disposed on a portion of the transparent conductive layer 14 corresponding to the second region 16, and a second electrode 29 disposed on a portion of the transparent conductive layer 14 corresponding to the first region 15, so as to respectively lead out the carriers collected by the portions of the transparent conductive layer 14 corresponding to the first region 15 and the second region 16. The materials of the first electrode 25 and the second electrode 29 may include any conductive material such as silver, aluminum, copper, titanium and nickel.

[0165] In one example, if Figure 3 As shown, the back contact cell further includes a surface passivation layer 28 disposed on the second side of the semiconductor substrate 11 to passivate the second side of the semiconductor substrate 11 and reduce the carrier recombination rate on the second side. The structure and material of the surface passivation layer 28 can be determined at least according to the requirements for the carrier recombination rate on the second side in the actual application scenario and the actual manufacturing process, and are not specifically limited here.

[0166] Exemplarily, the surface passivation layer may include an intrinsic semiconductor passivation layer and a silicon nitride passivation layer stacked in sequence along the thickness direction of the semiconductor substrate on one side of the second surface. The material of the intrinsic semiconductor passivation layer includes amorphous silicon and / or microcrystalline silicon. In this case, the intrinsic semiconductor passivation layer included in the surface passivation layer can be formed simultaneously when the interface passivation layer included in the heterogeneous contact structure is manufactured on the first side. The silicon nitride passivation layer included in the surface passivation layer can be formed simultaneously when the mask material for realizing the second passivation contact structure is manufactured on the first side, without adding additional operating steps to form the surface passivation layer, which is conducive to improving the manufacturing efficiency of the back contact battery.

[0167] The present invention also provides the following seven specific examples and two comparative examples for specifically illustrating the working performance of the back contact battery provided by the present invention:

[0168] Example 1

[0169] First, the silicon wafer is polished and cleaned. Specifically, the silicon wafer is put into a tank-type polishing and cleaning machine for polishing to remove the cutting damage layer of the silicon wafer. The polishing morphology of the first and second surfaces of the silicon wafer is regulated by controlling the temperature, time, and concentration of the chemical solution.

[0170] Next, the first deposition operation is performed. Specifically, a tunneling silicon oxide layer and an intrinsic polysilicon layer are sequentially deposited on one side of the first surface of the silicon wafer. The tunneling silicon oxide layer and the intrinsic polysilicon layer are both deposited using a low-pressure chemical vapor deposition furnace (LPCVD). In addition, the thickness of the tunneling silicon oxide layer is 1.4 nm, and the thickness of the intrinsic polysilicon is 120 nm.

[0171] Next, a phosphorus diffusion process is performed. Specifically, intrinsic polysilicon is doped by high-temperature diffusion to form an N-type polysilicon layer, and a phosphorus silicon glass layer is formed on the side of the N-type polysilicon layer away from the silicon wafer.

[0172] Next, the first wet etching operation is performed. Specifically, the function of this step is to remove the phosphorus silicon glass layer by using an HF solution. The concentration of the HF solution is 5%, and the etching time is 2 minutes.

[0173] Next, a second deposition operation is performed, wherein a silicon nitride layer with a thickness of 80 nm and a refractive index of 2.0 is deposited on one side of the first surface of the silicon wafer using a plasma chemical vapor deposition device.

[0174] Next, a first laser etching operation is performed. Specifically, a laser etching process is used to remove the portion of the silicon nitride layer corresponding to the second region and the portion of the N-type doped polysilicon layer corresponding to the second region. The laser used may be a 532 picosecond laser.

[0175] Next, a second wet etching operation is performed, which is used to form a pyramid velvet structure on the surface of the second region and the second face, while removing the silicon nitride layer deposited by the second deposition operation.

[0176] Next, a third deposition operation is performed. Specifically, a chemical vapor deposition process is used to sequentially form an intrinsic silicon layer and a P-type silicon layer in a whole layer on one side of the first surface of the silicon wafer. The thickness of the intrinsic silicon layer is 8nm. The thickness of the P-type silicon layer is 15nm, and the crystallization rate of the P-type silicon layer is 5%. At the same time, in this step, an intrinsic silicon layer and an anti-reflection layer are deposited on the second surface of the silicon wafer, and the anti-reflection layer is a silicon nitride layer with a thickness of 75nm.

[0177] Next, a second laser etching operation and a second wet etching operation are performed. Specifically, a laser etching process is used to remove the portion of the intrinsic silicon layer corresponding to the first region and the portion of the P-type silicon layer corresponding to the first region. The laser used is a 532 picosecond laser. Then, through a chain device, the second side of the semi-finished product is turned up and protected by a water film. And the first side of the semi-finished product is contacted with an HF solution to remove the oxide layer formed during the doping process of the P-type silicon layer and the silicon nitride layer that is plated around the first side during the third deposition operation.

[0178] Next, a transparent conductive layer is deposited entirely on one side of the first surface. The transparent conductive layer is an indium tin oxide layer with a thickness of 50 nm.

[0179] Next, the transparent conductive layer connecting the N region and the P region is isolated, and the intrinsic silicon layer and the P-type silicon layer above the overlapping region are isolated at the same time, so that the two polarity regions are completely structurally insulated. The isolation method adopts etching slurry isolation. The etching pattern at least makes part of the transparent conductive layer overlap across the P region and the overlapping region, and makes the transparent conductive layer on the N region and the P region physically insulated. The structure of the transparent conductive layer overlapping across the P region and the overlapping region is evenly distributed in the entire battery area, and the ratio of W1 to W2 is 90%.

[0180] Then, a metallization operation is performed. Specifically, a metal silver electrode is prepared on top of the two-electrode transparent conductive layer to realize the collection of carriers and the interconnection of the electrodes of the entire battery.

[0181] Example 2

[0182] The back contact battery provided in Example 2 has the same configuration as the back contact battery provided in Example 1 except that the ratio of W1 to W2 is 70%.

[0183] Example 3

[0184] The back contact battery provided in Example 3 has the same configuration as the back contact battery provided in Example 1 except that the ratio of W1 to W2 is 50%.

[0185] Example 4

[0186] The back contact battery provided in Example 4 has the same configuration as the back contact battery provided in Example 1 except that the ratio of W1 to W2 is 40%.

[0187] Example 5

[0188] The back contact battery provided in Example 5 has the same configuration as the back contact battery provided in Example 1 except that the ratio of W1 to W2 is 10%.

[0189] Example 6

[0190] The back contact cell provided in Example 6 has the same configuration as the back contact cell provided in Example 4 except that the crystallization rate of the P-type silicon layer is 0.

[0191] Example 7

[0192] The back contact cell provided in Example 7 is the same as the back contact cell provided in Example 4 except that the crystallization rate of the P-type silicon layer is 10%.

[0193] Comparative Example 1

[0194] The back contact battery provided in Comparative Example 1 has the same configuration as the back contact battery provided in Example 1 except that the ratio of W1 to W2 is 95%.

[0195] Comparative Example 2

[0196] The back contact battery provided in Comparative Example 2 has the same configuration as the back contact battery provided in Example 1 except that the ratio of W1 to W2 is 5%.

[0197] Table 1 Test parameters of back contact cells provided in Examples 1 to 7 and Comparative Examples 1 and 2

[0198]

[0199] It should be noted that the data in Table 1 are obtained by selecting 10,000 back-contact batteries as samples from each back-contact battery product line corresponding to Examples 1 to 7, and Comparative Examples 1 and 2. The efficiency data in the table is obtained by performing efficiency tests on 10,000 samples under each embodiment and calculating the average value. Among them, the back-contact batteries with an efficiency greater than 26% in the 10,000 samples under each embodiment are defined as batteries with efficiency grade A, and the efficiency grade A rate is calculated by dividing the number of batteries with efficiency grade A under each embodiment by 10,000. In addition, 10% of the 10,000 samples under each embodiment are subjected to a reverse breakdown voltage spot test, and the reverse breakdown voltage data in the table is obtained by calculating the average value. Among them, the back-contact batteries with a reverse breakdown voltage less than 11V in the 10,000 samples under each embodiment are defined as batteries with hot spot reliability grade A, and the hot spot reliability grade A rate is calculated by dividing the number of batteries with hot spot reliability grade A under each embodiment by 10,000.

[0200] In the above case, it can be seen from the data in Table 1 that the larger the ratio of the width W1 of the first transparent conductive portion along the first direction to the width W2 of the overlapping area along the first direction, the smaller the reverse breakdown voltage of the back contact battery. When the ratio of W1 to W2 is 95%, although the hot spot reliability A-level rate of the back contact battery is high, because the leakage loss in the forward voltage region is also high, the efficiency A-level rate of the back contact battery corresponding to Example 1 is very low and does not meet the working requirements. On the contrary, when the ratio of W1 to W2 is 5%, although the efficiency A-level rate of the back contact battery is high, because the leakage current in the reverse leakage region is small, the hot spot reliability A-level rate of the back contact battery corresponding to Example 2 is very low and does not meet the working requirements.

[0201] In addition, it can be seen from the data in Table 1 that the reverse breakdown voltage of the back contact cell decreases with the increase of the crystallization rate of the second doped semiconductor part. However, within a certain range, the efficiency and fill factor of the back contact cell increase with the increase of the crystallization rate of the second doped semiconductor part. When the crystallization rate of the second doped semiconductor part increases to a certain value, the efficiency and fill factor of the back contact cell decrease with the increase of the crystallization rate of the second doped semiconductor part.

[0202] In a second aspect, an embodiment of the present invention provides a photovoltaic module, which includes a back-contact cell provided by the first aspect and various implementations thereof.

[0203] The beneficial effects of the second aspect and its various implementations in the embodiments of the present invention can be analyzed with reference to the beneficial effects of the first aspect and its various implementations, and will not be repeated here.

[0204] In a third aspect, an embodiment of the present invention provides a method for manufacturing a back-contact battery. Figures 8 to 20 The manufacturing process is described in detail with reference to the cross-sectional view of the operation shown in FIG. 1 . Specifically, the manufacturing method of the back contact battery includes the following steps:

[0205] First, if Figure 8 As shown, a semiconductor substrate 11 is provided. The semiconductor substrate 11 includes a first surface and a second surface opposite to each other. The first surface includes a first region 15 and a second region 16, and an overlapping region 17 between the first region 15 and the second region 16. The first region 15, the overlapping region 17 and the second region 16 are arranged along a first direction.

[0206] Specifically, the material of the semiconductor substrate, and the distribution of the first region, the second region, and the overlapping region on one side of the first surface and other information can be referred to in the previous text and will not be described in detail here.

[0207] Next, if Fig.11As shown, a first doped semiconductor portion is formed and disposed in the first region 15 and the overlapping region 17. The first doped semiconductor portion can be disposed on the first region 15 and the overlapping region 17, or in the first region 15 and the overlapping region 17.

[0208] For example, Fig. 9 As shown, a first doped semiconductor portion may be formed as a whole layer on or within the first surface. Fig.10 As shown, an insulating mask layer 30 is formed on the first doped semiconductor portion 12 corresponding to the first region 15 and the overlapping region 17. Next, as shown in FIG. Fig.11 As shown, under the protection of the insulating mask layer 30, the portion of the first doped semiconductor portion 12 corresponding to the second region 16 is removed. Fig.13 As shown, the insulating mask layer is removed.

[0209] In the actual manufacturing process, a first doped semiconductor part arranged on or within the first surface can be formed by diffusion or doping source coating and other processes. Wherein, when a diffusion process is adopted and the material of the first doped semiconductor part includes silicon, after the first doped semiconductor part is formed, a doped silicon glass layer will also be formed on the side of the first doped semiconductor part away from the semiconductor substrate. In this case, the doped silicon glass layer can be patterned to form an insulating mask layer on the remaining part of the doped silicon glass layer on the first region and the overlapping region; or, after removing the doped silicon glass layer, an insulating mask layer can be formed on the part of the first doped semiconductor part corresponding to the first region and the overlapping region by deposition and laser etching processes (the material of the insulating mask layer can be set according to actual needs and is not specifically limited here. For example, the material of the insulating mask layer can include silicon nitride to perform hydrogen passivation treatment on the side of the first doped semiconductor part away from the semiconductor substrate). After forming the first doped semiconductor portion as a whole layer, without forming the above-mentioned doped silicon glass layer, an insulating mask layer can be directly formed on the portion of the first doped semiconductor portion corresponding to the first region and the overlapping region by deposition and laser etching processes.

[0210] Next, under the protection of the insulating mask layer, a process such as wet etching can be used to remove the portion of the first doped semiconductor portion corresponding to the second region. Then, the insulating mask layer is removed to ensure that in the manufactured back contact battery, the first doped semiconductor portion and the second doped semiconductor portion can be electrically connected in the reverse leakage region.

[0211] Alternatively, the above-mentioned formation of the first doped semiconductor portion arranged in the first region and the overlapping region may also include the steps of: forming a first doped semiconductor portion arranged as a whole layer on or within the first surface; and using a laser etching process to selectively remove the portion of the first doped semiconductor portion corresponding to the second region. The formation method of the first doped semiconductor portion arranged as a whole layer may refer to the above text. After the first doped semiconductor portion is formed, the portion of the first doped semiconductor portion corresponding to the second region may be directly and selectively removed by a laser etching process under the action of a mask of a corresponding mask plate, so as to save the deposition process and the removal process of the mask layer, reduce the manufacturing cost of the back contact battery, and improve the manufacturing efficiency of the back contact battery.

[0212] It should be noted that when the first doped semiconductor portion is disposed on the first region and the overlapping region, and the back contact battery further includes a first interface passivation layer, a process such as thermal oxidation or chemical vapor deposition can also be used to first form a first interface passivation material disposed in a whole layer on one side of the first surface. Then, before forming the first doped semiconductor portion disposed in a whole layer, the first interface passivation material can be selectively etched to remove the portion of the first interface passivation material corresponding to the second region to obtain the first interface passivation layer; or, after forming the first doped semiconductor portion disposed in a whole layer, the first doped semiconductor portion and the first interface passivation material can be selectively etched under the masking action of the same insulating mask layer.

[0213] For example, in the manufactured back contact battery, when the second surface of the semiconductor substrate and the surface of the second region of the first surface are velvet, Fig.12 As shown, before removing the insulating mask layer 30, the second region 16 and the second surface may be textured under the protection of the insulating mask layer 30, so that the second region 16 and the second surface form a textured surface. After the textured treatment, the insulating mask layer is removed.

[0214] Next, if Fig.16 As shown, a second doped semiconductor portion 13 is formed on the second region 16 and extends to cover a portion of the first doped semiconductor portion 12 on a side away from the semiconductor substrate 11 corresponding to the overlapping region 17. The second doped semiconductor portion 13 and the first doped semiconductor portion 12 have opposite conductivity types.

[0215] For example, Fig.14 As shown, a deposition process may be used to form a second doped semiconductor portion 13 disposed in a whole layer on the second region 16 and the first doped semiconductor portion 12. Then, as shown in FIG. Fig.15 As shown, a mask layer is formed on the portion of the second doped semiconductor portion 13 corresponding to the second region 16 and the overlapping region 17 by using deposition and laser etching or other etching processes. Fig.16As shown, under the masking effect of the mask layer, a process such as wet etching is used to remove the portion of the second doped semiconductor portion 13 corresponding to the first region 15. Next, as Fig.17 As shown, the mask layer is removed.

[0216] Alternatively, the above-mentioned formation of the second doped semiconductor portion disposed on the second region and extending to cover the portion of the first doped semiconductor portion corresponding to the overlapping region on the side away from the semiconductor substrate may also include the steps of: forming a second doped semiconductor portion disposed as a whole layer on the first doped semiconductor portion and the second region; and using a laser etching process to selectively remove the portion of the second doped semiconductor portion corresponding to the first region. The formation method of the second doped semiconductor portion disposed as a whole layer may refer to the above text. After the second doped semiconductor portion is formed, the portion of the second doped semiconductor portion corresponding to the first region may be directly and selectively removed by a laser etching process under the action of a mask of a corresponding mask plate, so as to save the deposition process and the removal process of the mask layer, thereby reducing the manufacturing cost of the back contact battery and improving the manufacturing efficiency of the back contact battery.

[0217] It should be noted that when the manufactured back contact battery also includes a second interface passivation layer, before forming the second doped semiconductor part, a process such as chemical vapor deposition can be used to form a second interface passivation material that is arranged on the second region and extends to cover the first doped semiconductor part. Then, before forming the second doped semiconductor part arranged in an entire layer, the second interface passivation material can be selectively etched to remove the portion of the second interface passivation material corresponding to the first region to obtain the second interface passivation layer; or, after forming the second doped semiconductor part arranged in an entire layer, the second doped semiconductor part and the second interface passivation material can be selectively etched under the masking action of the same mask layer.

[0218] Then, if Fig.18 and Fig.19 As shown, a transparent conductive layer 14 is formed covering the second doped semiconductor portion and the first doped semiconductor portion 12. An insulating groove 18 is provided in the transparent conductive layer 14 to separate the portion of the transparent conductive layer 14 corresponding to the first region 15 and the portion of the transparent conductive layer 14 corresponding to the second region 16. Among them, at least part of the overlapping region 17 is a reverse leakage region. In the reverse leakage region, the portion of the transparent conductive layer 14 extending from the second region 16 into the overlapping region 17 is a first transparent conductive portion 19, and the first transparent conductive portion 19 is electrically connected to the first doped semiconductor portion 12 through the second doped semiconductor portion 13. The width of the first transparent conductive portion 19 in the first direction is W1, and the width of the overlapping region 17 in the first direction is W2, and the ratio of W1 to W2 is greater than or equal to 10% and less than or equal to 90%.

[0219] For example, a physical vapor deposition process or the like can be used to form a whole layer of transparent conductive material disposed on the first doped semiconductor portion and the second doped semiconductor portion. Then, an insulating groove can be opened in the transparent conductive layer under the protection of a corresponding mask plate and by chemical etching slurry or laser etching or the like. The width of the insulating groove along the first direction and the ratio of the width W1 of the first transparent conductive layer in the first direction to the width W2 of the overlapping region in the first direction can be referred to in the previous text and will not be described in detail here.

[0220] Exemplarily, after forming the transparent conductive layer, or while opening the insulating groove in the transparent conductive layer, the manufacturing method of the back contact battery may further include the step of: selectively etching at least the first transparent conductive portion so that the first transparent conductive portion is intermittently distributed along the second direction. The second direction intersects with the first direction. The length of the continuous part and the discontinuous part of the first transparent conductive portion along the second direction, the width of the continuous part of the first transparent conductive portion along the second direction, and the specific orientation of the second direction can be referred to in the previous text and will not be repeated here.

[0221] In addition, at least the operation of selectively etching the first transparent conductive part can be performed while opening an insulating groove in the transparent conductive layer. At this time, the manufacture of the insulating groove and the execution of the selective etching can be realized through a mask plate, which is beneficial to improve the manufacturing efficiency of the back contact battery. Of course, the above two operations can also be performed separately. Secondly, when the third transparent conductive part of the manufactured back contact battery is provided with a notch at the discontinuous area corresponding to the first transparent conductive part, the etchant of the above selective etching operation also etches the part of the third transparent conductive part corresponding to the discontinuous area of ​​the first transparent conductive part to a certain extent. The width of the etching along the first direction can be referred to the previous text and will not be repeated here.

[0222] like Fig. 20 As shown, a screen printing process or the like can then be used to form a first electrode 25 on a portion of the transparent conductive layer 14 corresponding to the second region 16 , and a second electrode 29 on a portion of the transparent conductive layer 14 corresponding to the first region 15 .

[0223] The beneficial effects of the third aspect and its various implementations in the embodiments of the present invention can be analyzed with reference to the beneficial effects of the first aspect and its various implementations, and will not be repeated here.

[0224] In the above description, the technical details of the patterning and etching of each layer are not described in detail. However, those skilled in the art should understand that various technical means can be used to form layers, regions, etc. of desired shapes. In addition, in order to form the same structure, those skilled in the art can also design methods that are not completely the same as the methods described above. In addition, although the various embodiments are described above separately, this does not mean that the measures in the various embodiments cannot be used in combination to advantage.

[0225] The embodiments of the present disclosure are described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of the present disclosure. The scope of the present disclosure is defined by the appended claims and their equivalents. Without departing from the scope of the present disclosure, a person skilled in the art may make a variety of substitutions and modifications, which should all fall within the scope of the present disclosure.

Claims

1. A back contact battery, characterized in that: include: A semiconductor substrate, a first doped semiconductor portion, a second doped semiconductor portion and a transparent conductive layer; the second doped semiconductor portion and the first doped semiconductor portion have opposite conductivity types; The semiconductor substrate comprises a first surface and a second surface opposite to each other; the first surface comprises a first region, a second region, and an overlapping region between the first region and the second region; the first region, the overlapping region, and the second region are arranged along a first direction; The first doped semiconductor portion is disposed in the first region and the overlapping region; The second doped semiconductor portion is disposed on the second region and extends to cover the first doped semiconductor portion of the overlapping region; The transparent conductive layer covers the second doped semiconductor portion and the first doped semiconductor portion; An insulating groove is provided in the transparent conductive layer to physically insulate a portion of the transparent conductive layer corresponding to the first area from a portion of the transparent conductive layer corresponding to the second area; in, At least part of the overlapping region is a reverse leakage region; In the reverse leakage region, the portion of the transparent conductive layer extending from the second region into the overlapping region is a first transparent conductive portion, and the first transparent conductive portion is electrically connected to the first doped semiconductor portion through the second doped semiconductor portion; The width of the first transparent conductive portion in the first direction is W1, the width of the overlapping region in the first direction is W2, and the ratio of W1 to W2 is greater than or equal to 10% and less than or equal to 90%.

2. The back contact cell according to claim 1, characterized in that: The portion of the transparent conductive layer extending from the first region into the overlapping region is a second transparent conductive portion; a width of the second transparent conductive portion in the first direction is W3, and a ratio of W3 to W2 is less than or equal to 80%.

3. The back contact cell according to claim 1, characterized in that: The reverse leakage regions are continuously distributed along a second direction, and the second direction intersects with the first direction.

4. The back contact cell according to claim 3, characterized in that: The ratio of W1 to W2 is greater than or equal to 10% and less than or equal to 70%.

5. The back contact cell according to claim 1, characterized in that: The reverse leakage region is distributed discontinuously along a second direction, and the second direction intersects with the first direction; along the second direction, the first transparent conductive portion has a continuous region and a discontinuous region.

6. The back contact cell according to claim 5, characterized in that: Along the second direction, the ratio of the length of the discontinuous region to the length of the continuous region is less than or equal to 90%; and / or, The ratio of W1 to W2 is greater than or equal to 20% and less than or equal to 90%; and / or, A ratio of a width of the continuous region to a length of the continuous region is greater than or equal to 1:500 and less than or equal to 5:

1.

7. The back contact battery according to claim 5, characterized in that: The portion of the transparent conductive layer disposed in the second region is a third transparent conductive portion; a portion of the third transparent conductive portion corresponding to the discontinuous region is provided with a notch.

8. The back contact battery according to claim 7, characterized in that: The width of the notch in the first direction is less than or equal to 100 μm.

9. The back contact cell according to claim 1, characterized in that: The doping concentration of the dopant in the first doped semiconductor part and / or the second doped semiconductor part is greater than or equal to 1E19 cm -3 , and less than or equal to 5E20cm -3 and / or, The thickness of the first doped semiconductor portion is greater than or equal to 50 nm and less than or equal to 200 nm; and / or, The crystallization rate of the second doped semiconductor portion is less than or equal to 60%; and / or, The thickness of the second doped semiconductor portion is greater than or equal to 5 nm and less than or equal to 50 nm; and / or, The electrical conductivity of the second doped semiconductor portion is greater than or equal to 10E-5 S / cm and less than or equal to 1 S / cm.

10. The back contact cell according to claim 1, characterized in that: The semiconductor substrate is a silicon substrate; and / or, In the case where the first doped semiconductor portion is formed on the first region and the overlapping region, the back contact cell further comprises a first interface passivation layer between the first doped semiconductor portion and the semiconductor substrate; and or, The back contact cell further includes a second interface passivation layer, wherein the second interface passivation layer is located between the second region of the first surface and the second doped semiconductor portion, and extends between the second doped semiconductor portion and the first doped semiconductor portion.

11. The back contact cell according to claim 10, characterized in that: The thickness of the second interface passivation layer is greater than or equal to 2 nm and less than or equal to 20 nm; or, When the doping concentration of the dopant in the first doped semiconductor portion is greater than or equal to 1E19 cm -3 , and less than or equal to 5E19cm -3 When the thickness of the second interface passivation layer is greater than or equal to 5 nm and less than or equal to 15 nm; or When the doping concentration of the dopant in the first doped semiconductor portion is greater than 5E19 cm -3 , and less than or equal to 1E20cm -3 When the thickness of the second interface passivation layer is greater than or equal to 6 nm and less than or equal to 17 nm; or When the doping concentration of the dopant in the first doped semiconductor portion is greater than 1E20 cm -3 , and less than or equal to 5E20cm -3 When the thickness of the second interface passivation layer is greater than or equal to 7 nm and less than or equal to 20 nm.

12. The back contact cell according to claim 10, characterized in that: In the case where the back contact cell includes the first interface passivation layer and the second interface passivation layer, the first interface passivation layer and the first doped semiconductor portion constitute a first passivation contact structure, and the second interface passivation layer and the second doped semiconductor portion constitute a second passivation contact structure; wherein, The first passivation contact structure and the second passivation contact structure have different passivation contact types; and / or the thermal stability of the first passivation contact structure is greater than the thermal stability of the second passivation contact structure; and / or the first passivation contact structure is a tunneling passivation contact structure; and / or the second passivation contact structure is a heterogeneous contact structure.

13. The back contact battery according to any one of claims 1 to 12, characterized in that: The back contact battery also includes a surface passivation layer arranged on the second side of the semiconductor substrate; the surface passivation layer includes an intrinsic semiconductor passivation layer and a silicon nitride passivation layer stacked in sequence along the thickness direction of the semiconductor substrate on the second side; the material of the intrinsic semiconductor passivation layer includes at least one of amorphous silicon, microcrystalline silicon and nanocrystalline silicon.

14. The back contact battery according to any one of claims 1 to 12, characterized in that: The cross-sectional area of ​​the insulating groove gradually decreases in a direction approaching the semiconductor substrate; and / or, In the transparent conductive layer, regions along the first direction of a portion whose orthographic projection on the first surface does not overlap with the orthographic projection of the insulating groove on the first surface have the same thickness.

15. The back contact cell according to claim 1, characterized in that: The crystallization degree of at least a portion of the second doped semiconductor portion located in the second region is greater than the crystallization degree of a portion of the second doped semiconductor portion corresponding to the first transparent conductive portion.

16. The back contact cell according to claim 1, characterized in that: A degree of crystallization of at least a portion of the second doped semiconductor portion located in the second region is greater than a degree of crystallization of a portion of the second doped semiconductor portion located in the overlapping region.

17. The back contact cell according to claim 1, 15 or 16, characterized in that: The crystallization degree of at least a portion of the second doped semiconductor portion located in the second region is greater than the crystallization degree of a portion of the second doped semiconductor portion covering the sidewall; The side wall is located at the junction of the overlapping area and the second area.

18. The back contact cell according to claim 1, characterized in that The second doped semiconductor portion comprises a high crystallization region and a low crystallization region; the crystallization degree of the portion of the second doped semiconductor portion located in the low crystallization region is less than the crystallization degree of the portion of the second doped semiconductor portion located in the high crystallization region; In the second doped semiconductor portion, at least a portion corresponding to the first transparent conductive portion is located in the low crystallization region, and at least a portion corresponding to the second region is located in the high crystallization region.

19. The back contact cell according to claim 18, characterized in that The low crystallization region is located in the overlapping region; Alternatively, along the first direction, one side edge of the low crystallization region is located in the overlapping region, and the other side edge extends to the side wall; the side wall is located at the junction of the overlapping region and the second region. Or, along the first direction, one side edge of the low crystallization region is located in the overlapping region, and the other side edge extends to the second region; Alternatively, the highly crystallized region corresponds to the entire second region.

20. A photovoltaic module, characterized in that: Comprising a back contact battery as claimed in any one of claims 1 to 19.

21. A method for manufacturing a back contact battery, characterized in that: include: Providing a semiconductor substrate; The semiconductor substrate comprises a first surface and a second surface opposite to each other; the first surface comprises a first region, a second region, and an overlapping region between the first region and the second region; the first region, the overlapping region, and the second region are arranged along a first direction; forming a first doped semiconductor portion disposed in the first region and the overlapping region; forming a second doped semiconductor portion disposed on the second region and extending to cover a portion of the first doped semiconductor portion corresponding to the overlapping region on a side away from the semiconductor substrate; the second doped semiconductor portion and the first doped semiconductor portion have opposite conductivity types; forming a transparent conductive layer covering the second doped semiconductor portion and the first doped semiconductor portion; An insulating groove is provided in the transparent conductive layer to separate a portion of the transparent conductive layer corresponding to the first area from a portion of the transparent conductive layer corresponding to the second area; wherein at least a portion of the overlapping area is a reverse leakage area; In the reverse leakage region, the portion of the transparent conductive layer extending from the second region into the overlapping region is a first transparent conductive portion, and the first transparent conductive portion is electrically connected to the first doped semiconductor portion through the second doped semiconductor portion; the width of the first transparent conductive portion in the first direction is W1, and the width of the overlapping region in the first direction is W2, and the ratio of W1 to W2 is greater than or equal to 10% and less than or equal to 90%.

22. The method for manufacturing a back contact battery according to claim 21, characterized in that: The forming of a first doped semiconductor portion disposed in the first region and the overlapping region includes: forming a first doped semiconductor portion disposed entirely on or within the first surface; forming an insulating mask layer on a portion of the first doped semiconductor portion corresponding to the first region and the overlapping region; Under the protection of the insulating mask layer, removing a portion of the first doped semiconductor portion corresponding to the second region; The insulating mask layer is removed.

23. The method for manufacturing a back contact battery according to claim 21, characterized in that: The forming of the first doped semiconductor portion disposed in the first region and the overlapping region includes: forming a first doped semiconductor portion disposed on the first surface or within the first surface as a whole layer; and selectively removing a portion of the first doped semiconductor portion corresponding to the second region by a laser etching process; and / or, The forming of the second doped semiconductor portion disposed on the second region and extending to cover a portion of the first doped semiconductor portion on a side away from the semiconductor substrate corresponding to the overlapping region comprises: forming a whole layer of the second doped semiconductor portion disposed on the first doped semiconductor portion and the second region; and selectively removing a portion of the second doped semiconductor portion corresponding to the first region by a laser etching process; and / or, The forming of the transparent conductive layer covering the second doped semiconductor part and the first doped semiconductor part comprises: forming a transparent conductive layer entirely disposed on the first doped semiconductor part and the second doped semiconductor part; and using a laser etching process to open the insulating groove in the transparent conductive layer.

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