Solar cell and photovoltaic module

Abstract

The invention provides a solar cell and a photovoltaic module, and belongs to the technical field of solar cells. The solar cell includes: a semiconductor substrate; a tunneling oxide layer located on at least one surface of the semiconductor substrate; the doped polycrystalline silicon layer is positioned on one surface, far away from the semiconductor substrate, of the tunneling oxide layer; wherein at least one part of the surface, far away from the tunneling oxide layer, of the doped polycrystalline silicon layer is provided with silicon-containing convex particles. The photovoltaic module provided by the invention comprises the solar cell. According to the invention, the silicon-containing protruding particles are formed on at least one part of the surface, far away from the tunneling oxide layer, of the doped polycrystalline silicon layer, so that the light trapping effect of at least one surface of the solar cell is improved, and the double-sided rate of the solar cell is further improved.

Description

[0001] This application claims the filing date of September 13, 2024, the application number is 202411287736.1, and the invention name is priority of solar cells and photovoltaic modules. All the contents recorded in the prior application are cited in this application by reference. Technical Field

[0002] At least one embodiment of the present application relates to a solar cell, and more particularly to a solar cell and a photovoltaic module. Background Art

[0003] The tunneling oxide passivation contact structure (TOPCon structure) consists of an ultra-thin tunneling oxide layer and a doped polysilicon layer. This structure can be applied to various types of cells to form different cell types, such as TOPCon solar cells, local TOPCon solar cells, tunneling back contact solar cells (TBC solar cells), or a back contact solar cell with a TOPCon structure in one area (BC solar cell).

[0004] Before the high-temperature thin film deposition process, the silicon substrate surface is polished by etching process. During polishing, the tower base structure is formed on the surface of the silicon substrate. Although the tower base structure is conducive to the formation of good tunneling passivation and contact after the deposition of the polysilicon thin film, the tower base structure weakens the light trapping effect on the cell surface, so the bifaciality of the solar cell is low. Summary of the invention

[0005] In view of this, in order to improve the bifaciality of solar cells, the present application provides a solar cell and a photovoltaic module.

[0006] According to an embodiment of one aspect of the present application, a solar cell is provided, comprising: a semiconductor substrate; a tunneling oxide layer located on at least one surface of the semiconductor substrate; a doped polysilicon layer located on a side of the tunneling oxide layer away from the semiconductor substrate; wherein at least a portion of the surface of the doped polysilicon layer away from the tunneling oxide layer has silicon-containing protruding particles.

[0007] According to an embodiment of the present application, silicon-containing protruding particles are provided on the surface of the doped polysilicon layer at least at a position close to a corner or an edge of the semiconductor substrate.

[0008] According to an embodiment of the present application, the surface of the doped polysilicon layer away from the tunneling oxide layer also has a plurality of undulating structures; the height of the silicon-containing protruding particles is greater than the height of the undulating structures.

[0009] According to an embodiment of the present application, the doped polysilicon layer includes a plurality of first doped polysilicon layers and a plurality of second doped polysilicon layers alternately distributed along a first direction, wherein one of the first doped polysilicon layer and the second doped polysilicon layer is N-type, and the other of the first doped polysilicon layer and the second doped polysilicon layer is P-type; the surface of the first doped polysilicon layer and / or the second doped polysilicon layer has silicon-containing protruding particles.

[0010] According to an embodiment of the present application, at least one surface of a semiconductor substrate has a non-pyramid-shaped texture structure, the non-pyramid-shaped texture structure includes multiple substructures, and the doped polysilicon layer on the top surface of the substructure has silicon-containing protruding particles; the distribution density of the silicon-containing protruding particles on the N-type doped polysilicon layer located on the top surface of the substructure is greater than the distribution density of the silicon-containing protruding particles on the P-type doped polysilicon layer located on the top surface of the substructure.

[0011] According to an embodiment of the present application, at least one surface of the semiconductor substrate has a non-pyramid texture structure, the non-pyramid texture structure includes a plurality of substructures, the doped polysilicon layer on the top surface of the substructure has silicon-containing protruding particles; the distribution density of the silicon-containing protruding particles of the doped polysilicon layer on the top surface of at least one substructure is 0.1 to 0.5 per μm 2 .

[0012] According to an embodiment of the present application, at the same cross-sectional length, the number of protruding particles is less than the number of undulating structures.

[0013] According to an embodiment of the present application, the above-mentioned solar cell further includes:

[0014] The passivation anti-reflection layer is located on the surface of the doped polysilicon layer away from the semiconductor substrate; wherein the height of the silicon-containing protruding particles is greater than the thickness of the passivation anti-reflection layer, and / or the height of the silicon-containing protruding particles is less than 3 times the thickness of the passivation anti-reflection layer.

[0015] In some embodiments, the doped polysilicon layer includes a plurality of first doped polysilicon layers and a plurality of second doped polysilicon layers alternately spaced along a first direction, wherein one of the first doped polysilicon layers and the second doped polysilicon layers is N-type, and the other of the first doped polysilicon layers and the second doped polysilicon layers is P-type;

[0016] At least a portion of the surface of the N-type doped polysilicon layer away from the tunneling oxide layer has a plurality of pit structures, and / or at least a portion of the surface of the P-type doped polysilicon layer away from the tunneling oxide layer has a plurality of pit structures.

[0017] In some embodiments, at least one surface of the semiconductor substrate has a non-pyramid texture structure, the non-pyramid texture structure includes multiple sub-structures, the doped polysilicon layer on the top surface of the sub-structure has multiple pit structures, and the distribution density of the pit structures on the top surface of the sub-structure is 50,000 / mm²~300,000 / mm².

[0018] In some embodiments, at least one surface of the semiconductor substrate has a non-pyramid texture structure, and the non-pyramid texture structure includes a plurality of substructures.

[0019] The N-type doped polysilicon layer on the top surface of at least a portion of the substructure has a plurality of pit structures on its surface away from the tunneling oxide layer, and the P-type doped polysilicon layer on the top surface of at least a portion of the substructure has a plurality of pit structures on its surface away from the tunneling oxide layer;

[0020] The distribution density of the pit structures of the N-type doped polysilicon layer on the top surface of the substructure is greater than the distribution density of the pit structures of the P-type doped polysilicon layer on the top surface of the substructure.

[0021] In some embodiments, the solar cell further comprises: a passivation anti-reflection layer located on a surface of the doped polysilicon layer away from the semiconductor substrate;

[0022] Wherein, the pit structure is filled with a passivation anti-reflection layer.

[0023] According to an embodiment of the present application, the silicon-containing protruding particles include at least one of the C element, the N element and the O element.

[0024] According to an embodiment of the present application, the silicon-containing protruding particles include a third main group element and / or a fifth main group element.

[0025] According to the embodiments of the present application, the height of the silicon-containing protruding particles ranges from 150 nm to 450 nm;

[0026] The length of the undulating structure in a direction parallel to the surface of the semiconductor substrate 1 is 70 nm to 500 nm;

[0027] The height of the undulating structure is 20nm~60nm.

[0028] According to an embodiment of another aspect of the present application, a photovoltaic assembly is provided, comprising the above-mentioned solar cell.

[0029] According to an embodiment of the present application, the photovoltaic module includes a welding strip, which is suitable for electrically connecting two adjacent solar cells. In the planar direction of at least one surface of the semiconductor substrate, there is a gap between the welding strip and the doped polysilicon layer having silicon-containing protruding particles.

[0030] According to the solar cell provided by the above-mentioned embodiment of the present application, silicon-containing protruding particles are formed on at least a portion of the surface of the doped polysilicon layer away from the tunneling oxide layer to improve the light trapping effect of at least one surface of the solar cell, thereby improving the bifaciality of the solar cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings of the embodiments will be briefly introduced below. Obviously, the drawings in the following description only relate to some embodiments of the present application, rather than limiting the present application.

[0032] Figure 1 is a cross-sectional schematic diagram of a back-contact solar cell according to an embodiment of the present application;

[0033] Figure 2 A scanning electron microscope image of a surface of a doped polysilicon layer near an edge of a semiconductor substrate according to an embodiment of the present application;

[0034] Figure 3 Another scanning electron microscope image of the surface of the doped polysilicon layer near the edge of the semiconductor substrate according to an embodiment of the present application;

[0035] Figure 4A is another scanning electron microscope image of the surface of the doped polysilicon layer near the edge of the semiconductor substrate according to an embodiment of the present application;

[0036] Figure 4B Provided in the embodiments of this application Figure 4A A height test diagram of the surface of the doped polysilicon layer;

[0037] Figure 5 is another scanning electron microscope image of the surface of the doped polysilicon layer near the edge of the semiconductor substrate according to an embodiment of the present application;

[0038] Figure 6 A scanning electron microscope image of a side view of a surface of a doped polysilicon layer near an edge of a semiconductor substrate according to an embodiment of the present application;

[0039] Figure 7 is a cross-sectional schematic diagram of a TOPCon solar cell according to an embodiment of the present application;

[0040] Figure 8 is another scanning electron microscope image of the surface of the doped polysilicon layer near the edge of the semiconductor substrate according to an embodiment of the present application;

[0041] Fig. 9A for Figure 8 SEM images of some areas in the

[0042] Fig. 9B for Fig. 9AFigure 2. EDS test result of one site in the image.

[0043] Description of reference numerals:

[0044] 1- semiconductor substrate;

[0045] 2-Tunneling through the oxide layer;

[0046] 3- doped polysilicon layer;

[0047] 31-small population area;

[0048] 32-multiple sub-areas;

[0049] 33-Isolation area;

[0050] 34-a first doped polysilicon layer;

[0051] 35-a second doped polysilicon layer;

[0052] 4- non-electrode collection area;

[0053] 10- a first electrode;

[0054] 20- a second electrode;

[0055] 5-Emitter;

[0056] 6- first passivation layer;

[0057] 7- second passivation layer;

[0058] 30- a third electrode;

[0059] 40 - fourth electrode. DETAILED DESCRIPTION

[0060] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. However, the present application can be implemented in different forms and should not be construed as being limited to the embodiments proposed herein. On the contrary, providing these embodiments will make the application thorough and complete, and fully convey the scope of the present application to those skilled in the art. In the accompanying drawings, for clarity, the sizes and relative sizes of layers and regions may be exaggerated, and the same reference numerals represent the same elements throughout.

[0061] The terms used herein are only for describing specific embodiments and are not intended to limit the present application. The terms "include", "comprising", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0062] In the related technology, the bifaciality of solar cells is improved from two perspectives: tower base optimization and grid line design. From the perspective of tower base optimization, it is mainly to control the polishing effect to prepare a more finely divided tower base with a larger adjacent height difference on the semiconductor substrate (silicon substrate). This method improves the light trapping effect on the surface of the battery, but the tower base with fine and large height differences is prone to reduce the uniformity of the subsequent deposited film (tunneling the oxide layer and the polysilicon layer), which in turn leads to tunneling, passivation and contact problems. From the perspective of grid line design, it is mainly to narrow the width of the main grid and the auxiliary grid. This method can improve light absorption, but the increase in the aspect ratio of the grid line will put more requirements on the slurry formability. At the same time, thinner grid lines will also increase the contact resistance of the battery cell.

[0063] In view of this, it is necessary to provide a solar cell and a photovoltaic module to address the technical problem of urgently needing to improve the bifaciality of solar cells in the relevant technology.

[0064] Figure 1 A schematic cross-sectional view of a back-contact solar cell provided in an embodiment of the present application.

[0065] According to an exemplary embodiment of the present application, the present application provides a solar cell, referring to Figure 1 or Figure 5 As shown, including:

[0066] A semiconductor substrate 1;

[0067] A tunneling oxide layer 2 is located on at least one surface of the semiconductor substrate 1;

[0068] The doped polysilicon layer 3 is located on a side of the tunneling oxide layer 2 away from the semiconductor substrate 1 ; wherein at least a portion of the surface of the doped polysilicon layer 3 away from the tunneling oxide layer 2 has silicon-containing protruding particles.

[0069] According to the embodiments of the present application, reference Figure 1 As shown, the solar cell is, for example, a back contact solar cell. The semiconductor substrate 1 has a first surface and a second surface opposite to each other, and the tunneling oxide layer 2 is located on the second surface of the semiconductor substrate 1. In this embodiment, the second surface is the back side of the back contact solar cell.

[0070] In some embodiments, the surface of the doped polysilicon layer 3 away from the tunneling oxide layer 2 further has a plurality of undulating structures; the height of the silicon-containing protruding particles is greater than the height of the undulating structures.

[0071] In some embodiments, the surface of the doped polysilicon layer 3 away from the tunneling oxide layer 2 further has a plurality of undulating structures; the width of the silicon-containing protruding particles is smaller than the width of the undulating structures.

[0072] According to an embodiment of the present application, the undulating structure may be, for example, a silicon grain. The length of the undulating structure in a direction parallel to the surface of the semiconductor substrate 1 is 70 nm to 500 nm, for example, 70 nm, 100 nm, 150 nm, 200 nm, 500 nm. The height of the undulating structure is 20 nm to 60 nm, for example, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm.

[0073] According to an embodiment of the present application, the surface of the doped polysilicon layer 3 away from the tunneling oxide layer 2 has a plurality of undulating structures, and the height of the undulating structures is generally small, that is, the undulation of the undulating structures is too gentle, and it is difficult to improve the light trapping effect through the undulating structures. The contribution of the undulating structures to the bifaciality of the battery is limited.

[0074] According to the embodiment of the present application, the surface of the doped polysilicon layer 3 away from the tunnel oxide layer 2 has a plurality of undulating structures, and the width of the undulating structures is generally wide, that is, the undulation of the undulating structures is too slow, and it is difficult to improve the light trapping effect through the undulating structures, and the contribution of the undulating structures to the bifaciality of the battery is limited. The present application improves the light trapping effect of the doped polysilicon layer and the bifaciality of the battery by using silicon-containing protruding particles with a higher height and / or a narrower width; at the same time, it does not destroy the tunnel passivation effect of the doped polysilicon layer, and improves the photoelectric conversion effect of the battery.

[0075] refer to Figure 3 The black dots and Figure 6 The white particles shown represent silicon-containing protrusion particles. The silicon-containing protrusion particles have a partially spherical structure, such as a hemispherical shape; the height of the silicon-containing protrusion particles (approximately the radius of the silicon-containing protrusion particles) is 150nm~450nm, for example, 150nm, 200nm, 300nm, 400nm, 450nm, but is not limited to the values ​​listed.

[0076] According to the embodiments of the present application, the height of the silicon-containing protruding particles is between 150nm and 450nm, which can achieve a good light trapping effect. If the height of the silicon-containing protruding particles is too small, for example, less than 150nm, the sunlight cannot be refracted multiple times in the silicon-containing protruding particles and the side walls of the tower base, making it difficult to achieve the light trapping effect. If the silicon-containing protruding particles are too large, the film quality of the doped polysilicon will be reduced, which is not conducive to the photoelectric conversion efficiency of the battery.

[0077] According to an embodiment of the present application, at least a portion of the surface of the doped polysilicon layer 3 of the solar cell away from the tunneling oxide layer 2 has silicon-containing protruding particles, Figure 4B As shown, there are two high protrusions on the surface of the doped polysilicon layer ( Figure 4B The area pointed by the arrow in the figure corresponds to Figure 4A Two silicon-containing protruding particles on the surface of the doped polysilicon layer ( Figure 4AThe arrows in the figure point to two black dots. This indicates that the surface of the doped polysilicon layer away from the tunneling oxide layer has silicon-containing protruding particles. Figure 6 The white dots shown are silicon-containing protruding particles, the height of the silicon-containing protruding particles is greater than the height of the undulating structure, and the height of the silicon-containing protruding particles is close to the height of the pyramid structure (the height of the pyramid structure used for light trapping is usually less than 1 μm). The incident sunlight is refracted multiple times by the silicon-containing protruding particles, and more sunlight is incident on the semiconductor substrate 1, increasing the light trapping effect of the above-mentioned at least one surface of the solar cell, thereby improving the bifaciality of the solar cell.

[0078] According to an embodiment of the present application, silicon-containing protruding particles are present on the surface of the doped polysilicon layer 3 at least at a position close to a corner or an edge of the semiconductor substrate 1 .

[0079] According to an embodiment of the present application, the distance between the silicon-containing protruding particles and the edge of the semiconductor substrate 1 is less than 3 mm, for example, 1 mm, 2 mm, or 3 mm, but is not limited to the values ​​listed.

[0080] refer to Figure 2 As shown, the second surface of the semiconductor substrate 1 has a non-pyramid texture structure, and the non-pyramid texture structure includes a plurality of substructures (such as Figure 2 As shown in the rectangle in the figure, the tunneling oxide layer 2 and the doped polysilicon layer 3 are sequentially deposited on the second surface of the semiconductor substrate 1. A plurality of silicon-containing protruding particles (such as Figure 2 ).

[0081] It should be noted that since the silicon-containing protruding particles will cause the refractive index of the incident light to change, having too many silicon-containing protruding particles on a large area may cause color difference problems in the battery cell. Specifically, the silicon-containing protruding particles cause the surface of the doped polysilicon layer to be rougher, so that the doped polysilicon layer reflects light of different wavelengths differently, causing color difference problems in the battery cell. Therefore, by controlling the silicon-containing protruding particles within a suitable range (the silicon-containing protruding particles are within 3mm from the edge of the semiconductor substrate 1), it is possible to increase the light trapping effect on the battery surface and improve the bifaciality of the battery, while avoiding the problem of kicked-off chips during the process and appearance defects of the final battery product due to color difference problems.

[0082] According to the embodiments of the present application, reference Figure 1 As shown, the back-contact solar cell includes two non-electrode collecting regions 4 located on the second surface of the semiconductor substrate 1, and an electrode collecting region located between the two non-electrode collecting regions 4, the electrode collecting region includes a plurality of minority carrier regions 31 and a plurality of majority carrier regions 32 alternately distributed along a first direction, and an isolation region 33 is provided between the minority carrier regions 31 and the majority carrier regions 32.

[0083] According to an embodiment of the present application, the doped polysilicon layer 3 includes a first doped polysilicon layer 34 and a second doped polysilicon layer 35; wherein the first doped polysilicon layer 34 for collecting and conducting minority carriers is arranged in the minority region 31; the second doped polysilicon layer 35 for collecting and conducting majority carriers is arranged in the majority region 32, wherein the first doped polysilicon layer 34 and the second doped polysilicon layer 35 have opposite conductivity types, one of the first doped polysilicon layer 34 and the second doped polysilicon layer 35 is N-type, and the other of the first doped polysilicon layer 34 and the second doped polysilicon layer 35 is P-type. For example, the conductivity type of the first doped polysilicon layer 34 may be N-type, in which case the conductivity type of the second doped polysilicon layer 35 is P-type; or, the conductivity type of the first doped polysilicon layer 34 may be P-type, in which case the conductivity type of the second doped polysilicon layer 35 is N-type.

[0084] According to an embodiment of the present application, the semiconductor substrate 1 may be an N-type semiconductor substrate or a P-type semiconductor substrate. The conductivity type of the semiconductor substrate 1 is the same as the conductivity type of the second doped polysilicon layer 35 .

[0085] In the embodiment of the present application, the semiconductor substrate 1 is N-type, the first doped polysilicon layer 34 is P-type, and the second doped semiconductor layer 35 is N-type.

[0086] According to an embodiment of the present application, the surface of the first doped polysilicon layer 34 and / or the second doped polysilicon layer 35 has silicon-containing protruding particles.

[0087] According to an embodiment of the present application, the surface of the first doped polysilicon layer 34 has silicon-containing protruding particles.

[0088] According to an embodiment of the present application, the surface of the second doped polysilicon layer 35 has silicon-containing protruding particles.

[0089] According to an embodiment of the present application, the surfaces of the first doped polysilicon layer 34 and the second doped polysilicon layer 35 both have silicon-containing protruding particles.

[0090] In some embodiments, at least a portion of the surface of the N-type doped polysilicon layer away from the tunneling oxide layer has a plurality of protruding structures, which can increase the effective light absorption of the N-type doped polysilicon layer and improve the bifaciality of the solar cell; and the protruding structures can increase the contact area between the N-type doped polysilicon layer and the metal electrode, which is beneficial to reducing the contact resistance. In addition, the surface of the P-type doped polysilicon layer away from the tunneling oxide layer does not have a protruding structure, and the surface of the P-type doped polysilicon layer is smoother, which is beneficial to achieve a better tunneling passivation effect.

[0091] In some embodiments, according to the actual performance requirements of the solar cell, the surface of the N-type doped polysilicon layer may not have a protruding structure; the surface of the P-type doped polysilicon layer may have a plurality of protruding structures on at least a portion of the surface away from the tunneling oxide layer 2. For the N-type substrate, the P-type doped polysilicon layer serves as the emitter region, and its surface has a plurality of protruding structures, which increases the light absorption of the P-type region, excites more carriers, improves the double-sidedness, and further reduces the contact resistance of the P region.

[0092] According to an embodiment of the present application, surfaces of at least two first doped polysilicon layers 34 have silicon-containing protruding particles.

[0093] According to an embodiment of the present application, surfaces of at least two second doped polysilicon layers 35 have silicon-containing protruding particles.

[0094] According to the embodiment of the present application, the surface of the first doped polysilicon layer 34 and / or the second doped polysilicon layer 35 has silicon-containing protruding particles, and the incident light will be refracted multiple times at the silicon-containing protruding particles, and then more light will be incident on the surface of the semiconductor substrate 1. Therefore, the more doped polysilicon layers with silicon-containing protruding particles there are, the more the light trapping effect of the second surface of the battery can be increased, and the bifaciality of the battery can be improved.

[0095] According to an embodiment of the present application, at least one surface of the semiconductor substrate 1 has a non-pyramid-shaped texture structure, the non-pyramid-shaped texture structure includes multiple sub-structures, and the doped polysilicon layer on the top surface of the substructure has silicon-containing protruding particles; the distribution density of the silicon-containing protruding particles on the N-type doped polysilicon layer located on the top surface of the substructure is greater than the distribution density of the silicon-containing protruding particles on the P-type doped polysilicon layer located on the top surface of the substructure.

[0096] According to the embodiments of the present application, usually in the manufacturing process of the back-contact solar cell, the doping concentration of the doped polysilicon layer in the N-type region is higher than the doping concentration of the doped polysilicon layer in the P-type region, and the N-type region will cause more serious Auger recombination. By controlling the distribution density of the silicon-containing protrusion particles on the N-type doped polysilicon layer to be greater than the distribution density of the silicon-containing protrusion particles located on the P-type doped polysilicon layer, the light trapping effect of the N-type region can be increased, the loss of Auger recombination in the N-type region can be compensated, and the difference in light trapping effects between the N-type region and the P-type region can be narrowed, which is beneficial to increase the number of carriers collected in the N-type region, thereby improving the photoelectric conversion efficiency of the back-contact solar cell.

[0097] According to an embodiment of the present application, at least one surface of the semiconductor substrate 1 has a non-pyramid texture structure, the non-pyramid texture structure includes a plurality of substructures, the doped polysilicon layer on the top surface of the substructure has silicon-containing protruding particles; the distribution density of the silicon-containing protruding particles of the doped polysilicon layer on the top surface of at least one substructure is 0.1 to 0.5 per μm 2For example, it can be 0.1 / μm 2 , 0.2 / μm 2 , 0.3 / μm 2 , 0.4 / μm 2 , 0.5 / μm 2 , but not limited to the values ​​listed above. The top surface refers to the complete polygon or complete arc structure that can be observed in the top view of the battery product, corresponding to the concave surface of the silicon substrate facing the inside of the silicon substrate.

[0098] According to an embodiment of the present application, at the same cross-sectional length, the number of protruding particles distributed is less than the number of undulating structures distributed. Figure 5 As shown, under the same magnification and the same window length, the distribution number of the undulating structure is greater than the distribution number of the silicon-containing protruding particles.

[0099] It should be noted that the doped polysilicon layer on the bottom, top and side surfaces of the substructure of the non-pyramid texture structure can be distributed with silicon-containing protruding particles. For the convenience of characterization, this application selects the top surface of the substructure to quantify the distribution density of the silicon-containing protruding particles.

[0100] According to the embodiments of the present application, the back of the solar cell has a tower base structure and silicon-containing protruding particles. The incident sunlight will be refracted multiple times at the silicon-containing protruding particles and the side walls of the tower base, so that more sunlight is incident on the surface of the semiconductor substrate. Therefore, the doped polysilicon layer with denser silicon protruding particles will further increase the light trapping effect on the back of the cell and improve the bifaciality of the solar cell.

[0101] In some embodiments, at least a portion of the surface of the doped polysilicon layer 3 away from the tunneling oxide layer 2 has a plurality of pit structures, which can improve the light trapping effect of the at least one surface of the solar cell, thereby improving the bifaciality of the solar cell.

[0102] Among them, at least a portion of the surface of the N-type doped polysilicon layer and / or the P-type doped polysilicon layer has a plurality of pit structures. That is to say, at least a portion of the surface of the N-type doped polysilicon layer away from the tunneling oxide layer 2 has a plurality of pit structures, and the surface of the P-type doped polysilicon layer away from the tunneling oxide layer 2 has no pit structures; or, the surface of the N-type doped polysilicon layer away from the tunneling oxide layer 2 has no pit structures, and at least a portion of the surface of the P-type doped polysilicon layer away from the tunneling oxide layer 2 has pit structures; or, both the N-type doped polysilicon layer and the P-type doped polysilicon layer have a plurality of pit structures on at least a portion of the surface away from the tunneling oxide layer 2, and the distribution density of the pit structures contained in the two is different.

[0103] In some embodiments, the depth of the pit structure is 80 nm to 150 nm, for example, 80 nm, 100 nm, 120 nm, 130 nm, or 150 nm, but is not limited to the above values.

[0104] In some embodiments, reference Figure 5 As shown, the surface of the doped polysilicon layer near the edge of the semiconductor substrate has a dot-shaped or line-shaped pit structure, wherein the depth of the pit structure is less than the thickness of the doped polysilicon layer.

[0105] In some embodiments, the length of the pit structure in a direction parallel to the surface of the semiconductor substrate 1 is 150 nm to 630 nm, for example, 150 nm, 200 nm, 300 nm, 500 nm, 630 nm, but is not limited to the listed values.

[0106] According to the embodiments of the present application, the depth of the pit structure is greater than the height of the undulating structure, that is, the undulation of the pit structure is greater than the undulation of the undulating structure, and the pit structure is closer to the height of the pyramid (the height of the pyramid structure used for trapping light is usually less than 1 μm), further improving the light trapping effect and increasing the double-sided rate.

[0107] In some embodiments, at least a portion of the surface of the N-type doped polysilicon layer away from the tunneling oxide layer 2 has a plurality of pit structures, wherein the depth of the pit structure is greater than the height of the undulating structure. In addition, the surface of the P-type doped polysilicon layer away from the tunneling oxide layer 2 does not have a pit structure.

[0108] In the embodiment of the present application, at least a portion of the surface of the N-type doped polysilicon layer away from the tunneling oxide layer has a plurality of pit structures, and the pit structures can increase the effective light absorption of the N-type doped polysilicon layer and improve the bifaciality of the solar cell; and the pit structures can increase the contact area between the N-type doped polysilicon layer and the metal electrode, which is beneficial to reduce the contact resistance. In addition, the surface of the P-type doped polysilicon layer away from the tunneling oxide layer does not have a pit structure, and the surface of the P-type doped polysilicon layer is smoother, which is beneficial to achieve a better tunneling passivation effect.

[0109] For the convenience of characterization, the present application selects the top surface of the substructure of the non-pyramid-shaped texture structure to quantify the distribution density of the pit structure.

[0110] In some embodiments, the distribution density of the pit structure on the top surface of the substructure is 50,000 / mm² to 300,000 / mm², that is, the distribution density of the pit structure of the N-type doped polysilicon layer or the pit structure of the P-type doped polysilicon layer can be selected from the above range. It should be noted that if the distribution density of the pit structure is too large, the tunneling passivation effect of the passivation contact structure (the passivation contact structure includes the tunneling oxide layer and the doped polysilicon layer) will be reduced; if the distribution density of the pit structure is too small, a sufficient light trapping effect cannot be achieved. The pit structure with a specific distribution density of the present application will not significantly reduce the tunneling passivation effect of the passivation contact structure while achieving the light trapping effect.

[0111] In some embodiments, according to the actual performance requirements of the solar cell, the surface of the N-type doped polysilicon layer can be set to have no pit structure; at least a portion of the surface of the P-type doped polysilicon layer away from the tunneling oxide layer 2 has multiple pit structures, wherein the depth of the pit structure of the P-type doped polysilicon layer is greater than the height of the undulating structure.

[0112] According to an embodiment of the present application, for an N-type substrate, a P-type doped polysilicon layer serves as an emitter region, and its surface has a plurality of pit structures, which increases the light absorption of the P-type region, excites more carriers, improves the double-sidedness, and further reduces the contact resistance of the P region.

[0113] In some embodiments, at least a portion of the surface of the N-type doped polysilicon layer away from the tunneling oxide layer 2 has a plurality of pit structures, and at least a portion of the surface of the P-type doped polysilicon layer away from the tunneling oxide layer 2 also has a plurality of pit structures; that is, at least a portion of the substructure has a plurality of pit structures on the surface of the N-type doped polysilicon layer on the top surface, and at least a portion of the substructure has a plurality of pit structures on the surface of the P-type doped polysilicon layer on the top surface; wherein the distribution density of the pit structures of the N-type doped polysilicon layer on the top surface of the substructure is greater than the distribution density of the pit structures of the P-type doped polysilicon layer on the top surface of the substructure.

[0114] In the embodiments of the present application, the doping concentration of the doped polysilicon layer in the N-type region is usually higher than the doping concentration of the doped polysilicon layer in the P-type region. The N-type region will cause more serious Auger recombination. By controlling the distribution density of the pit structure on the N-type doped polysilicon layer to be greater than the distribution density of the pit structure on the P-type doped polysilicon layer, the light trapping effect of the N-type region can be increased, the loss of Auger recombination in the N-type region can be compensated, and the difference in light trapping effects between the N-type region and the P-type region can be narrowed, which is beneficial to increasing the number of carriers collected in the N-type region, thereby improving the photoelectric conversion efficiency of the back-contact solar cell.

[0115] In some embodiments, the above-mentioned solar cell also includes: a passivation anti-reflection layer, located on the surface of the doped polysilicon layer 3 away from the semiconductor substrate 1; wherein the height of the silicon-containing protruding particles is greater than the thickness of the passivation anti-reflection layer, and / or the height of the silicon-containing protruding particles is less than 3 times the thickness of the passivation anti-reflection layer.

[0116] According to an embodiment of the present application, after a passivation anti-reflection layer is deposited on the doped polysilicon layer 3, since at least a portion of the surface of the doped polysilicon layer 3 away from the tunneling oxide layer 2 has silicon-containing protruding particles, protruding particles are also formed on at least a portion of the surface of the deposited passivation anti-reflection layer.

[0117] According to the embodiments of the present application, the silicon-containing protruding particles have a certain height, which increases the contact area with the passivation anti-reflection layer, further increases the area of ​​the passivation anti-reflection layer, and improves light absorption; further, the height of the protruding particles is less than 3 times the thickness of the passivation anti-reflection layer, and the protruding particles are not easy to be too high. If they are too high, it will affect the uniformity of the film layer of the passivation anti-reflection layer and reduce the passivation effect.

[0118] According to an embodiment of the present application, the passivation anti-reflection layer includes a stack of aluminum oxide and one or more of silicon nitride, silicon oxide or silicon oxynitride, and the thickness of the passivation anti-reflection layer refers to the total thickness of the stack.

[0119] For example, the thickness of the aluminum oxide / silicon nitride stack is 100 nm, of which the thickness of aluminum oxide is 5 nm and the thickness of silicon nitride is 95 nm. The particle size of the protruding particles is about 300-400 nm, and the height of the protruding particles is 150-200 nm.

[0120] According to the embodiments of the present application, a passivation anti-reflection layer is deposited on the doped polysilicon layer, so that the pit structure of the doped polysilicon layer is filled with the passivation layer, and the surface of the passivation layer also has a pit structure, so that the surface area of ​​the passivation layer can be increased, thereby improving the passivation effect of the passivation layer. For example: the pit structure of the doped polysilicon layer is filled with a passivation anti-reflection layer such as an aluminum oxide / silicon nitride stack.

[0121] According to an embodiment of the present application, the silicon-containing protruding particles include at least one of the C element, the N element and the O element.

[0122] According to the embodiments of the present application, the silicon-containing protruding particles of the doped polysilicon layer have C elements and / or N elements, which can improve the flexibility of the solar cell.

[0123] According to the embodiments of the present application, the silicon-containing protruding particles of the doped polysilicon layer have the O element, which can improve the conductivity of the doped polysilicon layer and thus reduce the contact resistance.

[0124] According to an embodiment of the present application, the silicon-containing protrusion particles include third main group elements and / or fifth main group elements, wherein the content of the third main group elements and / or fifth main group elements of the silicon-containing protrusion particles is greater than the content of the third main group elements and / or fifth main group elements of the tunneling oxide layer corresponding to the same doping region, and the content of the third main group elements and / or fifth main group elements of the tunneling oxide layer corresponding to the same doping region is greater than the content of the third main group elements and / or fifth main group elements of the semiconductor substrate corresponding to the same doping region, so as to further reduce the contact resistance, and reduce the recombination of photogenerated carriers in the semiconductor substrate on the basis of forming tunneling passivation characteristics by the doped polysilicon layer and the tunneling oxide layer.

[0125] According to the embodiments of the present application, the content of the doped O element, N element, C element, the third main group element and / or the fifth main group element is lower than the content of the silicon element. By controlling the content of the doped element to be lower than the content of the silicon element, it is possible to avoid the recombination of photogenerated carriers with defects caused by excessive doping elements, thereby reducing the minority carrier lifetime.

[0126] According to an embodiment of the present application, the silicon-containing protruding particles, for example, contain Si element, N element, C element, O element, and P element, wherein the content of Si element is 53.11 at.%, the content of C element is 17.93 at.%, the content of N element is 22.26 at.%, the content of O element is 6.3 at.%, and the content of P element is 0.4 at.%.

[0127] According to the embodiments of the present application, by introducing C element, O element and IIIA / VA group elements into silicon-containing protruding particles, the light trapping effect of the silicon-containing protruding particles can be increased, and the contact resistance can be reduced, thereby improving the photoelectric conversion efficiency of solar cells.

[0128] According to an embodiment of the present application, the front and back isolation regions 33 of the back contact solar cell have a pyramid structure. The height of the silicon-containing protruding particles is smaller than the height of the pyramid of the back isolation region 33 of the back contact solar cell, and is also smaller than the height of the pyramid structure of the front of the back contact solar cell.

[0129] According to the embodiments of the present application, the surface of the silicon-containing protruding particles is rough, which can further increase the light trapping effect on the surface of the doped polysilicon layer having the silicon-containing protruding particles and improve the bifaciality of the battery.

[0130] According to an embodiment of the present application, the above-mentioned solar cell also includes a first electrode 10, which is located on a surface of the first doped polysilicon layer 34 away from the semiconductor substrate 1; and a second electrode 20, which is located on a surface of the second doped polysilicon layer 35 away from the semiconductor substrate 1.

[0131] According to the embodiments of the present application, silicon-containing protruding particles are formed on at least a portion of the surface of the doped polysilicon layer of the BC solar cell while maintaining the original tower base morphology and grid line geometry. During the light incident process, the incident light will be refracted multiple times between the silicon-containing protruding particles and the tower base, so that more incident light reaches the semiconductor substrate, which can increase the light trapping effect on the back of the BC solar cell, thereby improving the bifaciality of the BC solar cell. Maintaining the original tower base and grid line features can maintain the passivation and contact effects of the battery, and with the silicon-containing protruding particles on the surface of the doped polysilicon layer, good passivation, contact and light trapping effects of the BC solar cell can be achieved.

[0132] refer to Figure 7 As shown, according to an embodiment of the present application, the solar cell may be a double-sided contact solar cell, for example, a TOPCon solar cell.

[0133] According to an embodiment of the present application, a tunneling oxide passivation contact structure composed of a tunneling oxide layer 2 and a doped polysilicon layer 3 can be formed on at least one surface of the semiconductor substrate 1. For example, the tunneling oxide passivation contact structure is formed on one surface or two surfaces of the semiconductor substrate 1; the tunneling oxide passivation contact structure is formed on a local area of ​​at least one surface of the semiconductor substrate 1. That is to say, the present application is also applicable to local TOPCon solar cells, TBC solar cells, or BC cells with a TOPCon structure in one area, etc., as long as they have a TOPCon structure.

[0134] According to the embodiments of the present application, reference Figure 7 As shown, the semiconductor substrate 1 has a first surface and a second surface opposite to each other, and a tunneling oxide passivation contact structure composed of a tunneling oxide layer 2 and a doped polysilicon layer 3 is formed on the second surface of the semiconductor substrate 1 .

[0135] According to an embodiment of the present application, the TOPCon solar cell also includes an emitter 5 and a first passivation layer 6 located on the first surface of the semiconductor substrate 1; and a second passivation layer 7 located on the second surface of the semiconductor substrate 1; wherein the first passivation layer 6 and the second passivation layer 7 realize a passivation anti-reflection function.

[0136] According to an embodiment of the present application, the TOPCon solar cell further includes a third electrode 30 located on the first surface of the semiconductor substrate 1 and a fourth electrode 40 located on the second surface of the semiconductor substrate 1 .

[0137] Cleaning removes the electrodes and passivation layer of the solar cell, exposing the doped polysilicon layer under the electrode. Figure 8 As shown, the surface of the exposed doped polysilicon layer has silicon-containing protruding particles (such as Figure 8 ).

[0138] refer to Figure 8 , Figure 9A~Figure 9B As shown, the electrode and passivation layer of the solar cell were cleaned and removed, and it was observed that silicon-containing protruding particles remained on the surface of the doped polysilicon layer under the electrode. EDS test was performed on any site of the doped polysilicon layer, and the EDS test results showed that the composition of the silicon-containing protruding particles was silicon.

[0139] According to an exemplary embodiment of the present application, the present application provides a method for manufacturing a solar cell, including: operation S01 to operation S03.

[0140] In operation S01 , a semiconductor substrate 1 is polished to obtain a semiconductor substrate 1 having a tower base structure on both the first surface and the second surface.

[0141] According to an embodiment of the present application, an initial silicon wafer cut with diamond wire is polished to obtain a semiconductor substrate 1 having a tower base structure on both the first surface and the second surface.

[0142] According to an embodiment of the present application, the width of the tower base structure is 5μm~50μm, for example, it can be 5μm, 10μm, 20μm, 40μm, 50μm, but not limited to the listed values; the height difference between adjacent tower bases is 0.2μm~8μm, for example, it can be 0.2μm, 1μm, 2μm, 4μm, 5μm, 6μm, 8μm, but not limited to the listed values.

[0143] In operation S02 , a tunneling oxide layer 2 is deposited on at least one surface of a semiconductor substrate 1 .

[0144] According to an embodiment of the present application, the tunneling oxide layer 2 is SiO2 with a thickness of 1-5 nm.

[0145] In operation S03 , a doped polysilicon layer 3 is deposited on a surface of the tunneling oxide layer 2 away from the semiconductor substrate 1 , wherein at least a portion of the surface of the doped polysilicon layer 3 away from the tunneling oxide layer 2 has silicon-containing protruding particles.

[0146] According to the embodiment of the present application, a low pressure chemical vapor deposition (LPCVD) method is used to deposit the doped polysilicon layer 3. Specifically, after the tunneling oxide layer 2 is deposited, the semiconductor substrate 1 having a tower base structure on the surface is sent into a tube furnace for thin film deposition, and a doped polysilicon layer 3 having silicon-containing protruding particles on the surface is obtained under the conditions of high source quantity, high temperature and high pressure.

[0147] According to an embodiment of the present application, the silane flow rate is 100 sccm~1000 sccm, for example, it can be 100 sccm, 200 sccm, 500 sccm, 800 sccm, 1000 sccm, but is not limited to the listed values.

[0148] According to an embodiment of the present application, the deposition temperature of the high temperature thin film deposition is 500°C~700°C, for example, it can be 500°C, 550°C, 600°C, 650°C, 700°C, but is not limited to the listed values.

[0149] According to an embodiment of the present application, the pressure of high-pressure thin film deposition is 50-400 mTorr, for example, 50 mTorr, 100 mTorr, 200 mTorr, 300 mTorr, 400 mTorr, but is not limited to the values ​​listed.

[0150] According to the embodiments of the present application, when the amount of silane is sufficient, the deposition temperature is high and the deposition pressure is high during the thin film deposition process, the deposition rate is high, so the silane cannot decompose and react instantly, resulting in a decrease in the continuity and uniformity of thin film deposition and growth, and silicon-containing particles will exist in the doped polysilicon layer after deposition.

[0151] According to an embodiment of the present application, during the process of depositing a doped polysilicon layer, the deposition temperature and silane gas flow rate of the doped polysilicon layer located near the edge of the semiconductor substrate are increased, so that silicon-containing protruding particles are present on the surface of the doped polysilicon layer located at a position near one corner and one edge of the semiconductor substrate.

[0152] According to an exemplary embodiment of the present application, the present application provides a photovoltaic assembly, including the above-mentioned solar cell.

[0153] According to an embodiment of the present application, silicon-containing protruding particles are formed on at least a portion of the surface of the doped polysilicon layer away from the tunneling oxide layer to improve the surface light trapping effect of the solar cell. The solar cell with improved surface light trapping effect is manufactured into a photovoltaic module to improve the bifaciality of the photovoltaic module.

[0154] According to an embodiment of the present application, at least a portion of a surface of a doped polysilicon layer of at least one solar cell in a photovoltaic module facing away from the tunneling oxide layer has silicon-containing protruding particles.

[0155] According to an embodiment of the present application, at least two solar cells in a photovoltaic module have silicon-containing protruding particles on at least a portion of the surface of the doped polysilicon layer facing away from the tunneling oxide layer.

[0156] According to an embodiment of the present application, the photovoltaic module includes a welding ribbon, which is suitable for electrically connecting two adjacent solar cells. On the second surface of the semiconductor substrate 1, there is a gap between the welding ribbon and the doped polysilicon layer 3 having silicon-containing protruding particles.

[0157] According to the embodiments of the present application, the soldering ribbon may be parallel or perpendicular to the extension direction of the doped polysilicon layer, and the soldering ribbon does not block the doped polysilicon layer having silicon-containing protruding particles, and does not affect the improvement of the bifaciality of the solar cell.

[0158] The ordinal numbers used in the specification and claims, such as "first", "second", "third", etc., to modify the corresponding elements, do not themselves mean that the elements have any ordinal numbers, nor do they represent the order of one element and another element, or the order in the manufacturing method. The use of these ordinal numbers is only used to clearly distinguish a component with a certain name from another component with the same name.

[0159] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above description is only a specific embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A solar cell, characterized in that: include: Semiconductor substrate (1); A tunneling oxide layer (2) located on at least one surface of the semiconductor substrate (1); A doped polysilicon layer (3) located on a side of the tunneling oxide layer (2) away from the semiconductor substrate (1); Wherein, at least a portion of the surface of the doped polysilicon layer (3) away from the tunneling oxide layer (2) has silicon-containing protruding particles.

2. The solar cell according to claim 1, characterized in that: Silicon-containing protruding particles are present on the surface of the doped polysilicon layer (3) at least at a position close to a corner or an edge of the semiconductor substrate (1).

3. The solar cell according to claim 1, characterized in that The doped polysilicon layer (3) further comprises a plurality of undulating structures on a surface away from the tunneling oxide layer (2); The height of the silicon-containing protruding particles is greater than the height of the undulating structure.

4. The solar cell according to claim 1, characterized in that The doped polysilicon layer (3) comprises a plurality of first doped polysilicon layers (34) and a plurality of second doped polysilicon layers (35) which are alternately distributed along a first direction, wherein one of the first doped polysilicon layers (34) and the second doped polysilicon layers (35) is of N type, and the other of the first doped polysilicon layers (34) and the second doped polysilicon layers (35) is of P type; The surface of the first doped polysilicon layer (34) and / or the second doped polysilicon layer (35) has silicon-containing protruding particles.

5. The solar cell according to claim 4, characterized in that: The at least one surface of the semiconductor substrate (1) has a non-pyramid texture structure, the non-pyramid texture structure comprises a plurality of substructures, and the doped polysilicon layer on the top surface of the substructure has silicon-containing protruding particles; The distribution density of the silicon-containing protruding particles on the N-type doped polysilicon layer on the top surface of the substructure is greater than the distribution density of the silicon-containing protruding particles on the P-type doped polysilicon layer on the top surface of the substructure.

6. The solar cell according to claim 1, characterized in that The at least one surface of the semiconductor substrate (1) has a non-pyramid texture structure, the non-pyramid texture structure comprises a plurality of substructures, and the doped polysilicon layer on the top surface of the substructure has silicon-containing protruding particles; The distribution density of the silicon-containing protruding particles of the doped polysilicon layer on the top surface of at least one of the substructures is 0.1-0.5 / μm 2 .

7. The solar cell according to claim 3, characterized in that: At the same cross-sectional length, the distribution number of the protruding particles is smaller than the distribution number of the undulating structures.

8. The solar cell according to claim 1, characterized in that Also includes: A passivation anti-reflection layer, located on a surface of the doped polysilicon layer (3) away from the semiconductor substrate (1); Wherein, the height of the silicon-containing protruding particles is greater than the thickness of the passivation anti-reflection layer, and / or the height of the silicon-containing protruding particles is less than 3 times the thickness of the passivation anti-reflection layer.

9. The solar cell according to claim 1, characterized in that: The doped polysilicon layer (3) comprises a plurality of first doped polysilicon layers and a plurality of second doped polysilicon layers that are alternately distributed along a first direction, wherein one of the first doped polysilicon layer and the second doped polysilicon layer is of N type, and the other of the first doped polysilicon layer and the second doped polysilicon layer is of P type; At least a portion of the surface of the N-type doped polysilicon layer away from the tunneling oxide layer (2) has a plurality of pit structures, and / or at least a portion of the surface of the P-type doped polysilicon layer away from the tunneling oxide layer (2) has a plurality of pit structures.

10. The solar cell according to claim 9, characterized in that: The at least one surface of the semiconductor substrate (1) has a non-pyramid texture structure, the non-pyramid texture structure comprises a plurality of substructures, the doped polysilicon layer on the top surface of the substructure has a plurality of pit structures, The distribution density of the pit structure located on the top surface of the substructure is 50,000 / mm² to 300,000 / mm².

11. The solar cell according to claim 9, characterized in that: The at least one surface of the semiconductor substrate (1) has a non-pyramid texture structure, wherein the non-pyramid texture structure comprises a plurality of substructures. The N-type doped polysilicon layer on the top surface of at least a portion of the substructure has a plurality of pit structures on its surface away from the tunneling oxide layer (2), and the P-type doped polysilicon layer on the top surface of at least a portion of the substructure has a plurality of pit structures on its surface away from the tunneling oxide layer (2); The distribution density of the pit structures of the N-type doped polysilicon layer on the top surface of the substructure is greater than the distribution density of the pit structures of the P-type doped polysilicon layer on the top surface of the substructure.

12. The solar cell according to claim 9, characterized in that: Also includes: A passivation anti-reflection layer, located on a surface of the doped polysilicon layer (3) away from the semiconductor substrate (1); The pit structure is filled with the passivation anti-reflection layer.

13. The solar cell according to claim 1, characterized in that The silicon-containing protruding particles include at least one of C element, N element and O element.

14. The solar cell according to claim 1 or 13, characterized in that: The silicon-containing protruding particles include a third main group element and / or a fifth main group element.

15. The solar cell according to claim 1, characterized in that The height of the silicon-containing protruding particles ranges from 150 nm to 450 nm; The length of the undulating structure in a direction parallel to the surface of the semiconductor substrate (1) is 70 nm to 500 nm; The height of the undulating structure is 5nm~60nm.

16. A photovoltaic module, characterized in that: Comprising the solar cell according to any one of claims 1 to 15.

17. The photovoltaic module according to claim 16, characterized in that: The photovoltaic module includes a welding strip, and the welding strip is suitable for electrically connecting two adjacent solar cells. In the planar direction of at least one surface of the semiconductor substrate (1), there is a gap between the welding strip and the doped polysilicon layer (3) having silicon-containing protruding particles.

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