SOLAR CELL AND PHOTOVOLTAIC MODULE

Disclosed are a solar cell and a photovoltaic module. The solar cell includes a substrate, having a first surface and a second surface opposite to the first surface. The first surface includes a metal pattern region and a non-metal pattern region. The first surface is uneven and has a first maximum height with respect to the second surface in the non-metal pattern region and a second maximum height with respect to the second surface in the metal pattern region, and the first maximum height is lower than the second maximum height. The solar cell includes at least one passivation contact structure, covering the first surface and including a tunneling layer and a doped conductive layer stacked in a direction away from the substrate.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to Chinese Patent Application No. CN 202211587601.8, entitled “SOLAR CELL AND PHOTOVOLTAICMODULE,” filed on Dec. 7, 2022, which is incorporated herein by reference in its entirety.

TECHNIC FIELD

The various embodiments of the present disclosure relate to the field of solar cells, and in particular to a solar cell and a photovoltaic module.

BACKGROUND

Solar cells have excellent photoelectric conversion capability. In a tunnel oxide passivated contact (TOPCON) cell, a tunneling oxide layer and a doped conductive layer are prepared on one surface of a substrate to suppress carrier recombination at the surface of the substrate in the solar cell and enhance the passivation effect on the substrate. The tunneling oxide layer has good chemical passivation effect and the doped conductive layer has good field passivation effect. The tunneling oxide layer further provides a tunneling channel for the carriers which tunnels through the tunneling oxide layer to the substrate, achieving selective transport of the carriers and improving a fill factor of the solar cell. In this way, good photoelectric conversion performance of the solar cell can be realized.

However, the existing solar cells have the problem of low photoelectric conversion efficiency.

SUMMARY

According to embodiments of the present disclosure, a solar cell and a photovoltaic module are provided, to at least contribute to improve the photoelectric conversion efficiency of the solar cell.

Some embodiments of the present disclosure provide a solar cell. The solar cell includes a substrate, having a first surface and a second surface opposite to the first surface. The first surface includes a metal pattern region and a non-metal pattern region. The first surface is uneven and has a first maximum height with respect to the second surface in the non-metal pattern region and a second maximum height with respect to the second surface in the metal pattern region, and the first maximum height is lower than the second maximum height. The solar cell includes at least one passivation contact structure, covering the first surface and including a tunneling layer and a doped conductive layer stacked in a direction away from the substrate.

In some embodiments, a height difference between the first maximum height and the second maximum height is in a range of 0.2 μm to 10 μm.

In some embodiments, the first surface has a first texture structure in the metal pattern region and a second texture structure in the non-metal pattern region, and a roughness of the first texture structure is greater than a roughness of the second texture structure.

In some embodiments, the first texture structure includes a pyramid structure; the second texture structure includes a platform embossed structure, a height of the pyramid structure is greater than a height of the platform embossed structure, and a one-dimensional size of a bottom surface of the pyramid structure is less than a one-dimensional size of a bottom surface of the platform embossed structure. The height of the pyramid structure is a height from a tip of the pyramid structure to a bottom of the pyramid structure and the height of the platform embossed structure is a height from a bottom of the platform embossed structure to a top surface of the platform embossed structure.

In some embodiments, the height of the pyramid structure is in a range of 0.1μ to 5 μm, and the one-dimensional size of the bottom surface of the pyramid structure is in a range of 0.01 μm to 6 μm.

In some embodiments, the height of the platform embossed structure is in a range of 0.002 μm to 1 μm, and the one-dimensional size of the bottom surface of the platform embossed structure is in a range of 0.01 μm to 1000 μm.

In some embodiments, the first surface further includes a transitional region adjacent to the metal pattern region and the non-metal pattern region. The transitional region has a height not lower than the first maximum height and not higher than the second maximum height, the height of the transitional region is a height at any point of the transitional region and relative to the second surface and the at least one passivation contact structure is covered on the transitional region.

In some embodiments, there is an included angle in a range of 90° to 160° between the transitional region and the non-metal pattern region.

In some embodiments, the first surface has a third texture structure in the transitional region and the third texture structure has a roughness less than the roughness of the first texture structure.

In some embodiments, the third texture structure includes a plurality of triangular-prism-shaped embossed structures adjacent to each other, and each of the plurality of triangular-prism-shaped embossed structures has a sectional shape of triangular or triangle-like in a direction perpendicular to the transitional region.

In some embodiments, the at least one passivation contact structure includes a first passivation contact structure, over the metal pattern region. The first passivation contact structure includes a first tunneling layer and a first doped conductive layer stacked in the direction away from the substrate. The at least one passivation contact structure includes a second passivation contact structure, including first portion and second portion adjacent to each other. The first portion covers a top surface and side surfaces of the first passivation contact structure, and the second portion covers the remaining region of the first surface other than the metal pattern region. The second passivation contact structure includes a second tunneling layer and a second doped conductive layer stacked in the direction away from the substrate.

In some embodiments, the first passivation contact structure includes a plurality of sub-first passivation contact structures sequentially stacked in the direction away from the substrate, and each of the plurality of sub-first passivation contact structures includes a first tunneling sub-layer and a first doped conductive sub-layer sequentially stacked in the direction away from the substrate.

In some embodiments, the second passivation contact structure includes a plurality of sub-second passivation contact structures sequentially stacked in the direction away from the substrate, and each of the plurality of sub-second passivation contact structures includes a second tunneling sub-layer and a second doped conductive sub-layer sequentially stacked in the direction away from the substrate.

In some embodiments, the first passivation contact structure includes a plurality of sub-first passivation contact structures sequentially stacked in the direction away from the substrate, and each of the plurality of sub-first passivation contact structures includes a first tunneling sub-layer and a first doped conductive sub-layer sequentially stacked in the direction away from the substrate. The second passivation contact structure includes a plurality of sub-second passivation contact structures sequentially stacked in the direction away from the substrate, and each of the plurality of sub-second passivation contact structures includes a second tunneling sub-layer and a second doped conductive sub-layer sequentially stacked in the direction away from the substrate. The plurality of sub-first passivation contact structures and the plurality of sub-second passivation contact structures are alternately stacked in the direction away from the substrate.

In some embodiments, the solar cell further includes a first electrode, which is electrically connected with the first doped conductive layer.

In some embodiments, a concentration of a doped element in the first doped conductive layer is greater than or equal to a concentration of a doped element in the second doped conductive layer.

In some embodiments, a thickness of the first doped conductive layer is greater than or equal to a thickness of the second doped conductive layer.

In some embodiments, a material of the first doped conductive layer includes at least one of amorphous silicon, polycrystalline silicon and silicon carbide, and a material of the second doped conductive layer includes at least one of amorphous silicon, polycrystalline silicon and silicon carbide.

In some embodiments, a thickness of the first tunneling layer is less than or equal to a thickness of the second tunneling layer.

In some embodiments, a material of the first tunneling layer is different from a material of the second tunneling layer.

In some embodiments, the material of the first tunneling layer includes at least one of silicon oxide, aluminum oxide, silicon nitride, silicon oxynitride, amorphous silicon, or polycrystalline silicon; the material of the second tunneling layer includes at least one of silicon oxide, aluminum oxide, silicon nitride, silicon oxynitride, amorphous silicon, or polycrystalline silicon.

Some embodiments of the present disclosure provide a photovoltaic module, including a plurality of cell strings, each formed by connecting a plurality of solar cells. Each of the plurality of solar cells is the solar cell as mentioned above. The photovoltaic module includes encapsulation layers, configured to cover surfaces of the plurality of cell strings, and cover plates, configured to cover surfaces of the encapsulation layers away from the plurality of cell strings.

The technical solutions provided by the embodiments of the present disclosure at least have the following advantages.

In the technical solutions of the solar cell provided by the embodiments of the present disclosure, the first surface is disposed to be lower in height at non-metal pattern region than that at the metal pattern region, that is, the substrate surface in the non-metal pattern region and the substrate surface in the metal pattern region form a step structure. Compared with the substrate surface which is a smooth surface, the step structure can increase a surface area of the first surface of the substrate, so as to increase a contact area of the passivation contact structure with the first surface of the substrate. In this way, in a case of keeping the passivation contract structure over the non-metal pattern region relatively smooth, a tunneling channel for the carriers can be enlarged and the tunneling efficiency of the carriers can thus be increased. In addition, since the step structure is disposed at a junction between the metal pattern region and the non-metal pattern region, the area of the passivation contact structure covered on the junction can be increased. Further, since the junction is adjacent to the metal pattern region, the carriers in the passivation contact structure at the junction can be transported to the passivation contact structure over the metal pattern region over a shorter distance, contributing to increase the collection capability for the carriers.

DETAILED DESCRIPTION OF THE EMBODIMENTS

As mentioned in the background, the existing solar cells have the problem of low photoelectric conversion efficiency.

Analysis shows that one of the reasons for the low photoelectric conversion efficiency of the existing solar cells is that: a substrate has a metal pattern region and a non-metal pattern region; for a substrate surface of the metal pattern region, a roughness is to be increased so as to increase a contact area between a metal electrode and a doped conductive layer, whereas for a substrate surface of the non-metal pattern region, a roughness is to be reduced so as to increase a smoothness of a contact interface between the passivation contact structure and the substrate, contributing to improve a passivation performance of the passivation contact structure. The carriers in the substrate are tunneled to the doped conductive layer via the tunneling layer in the passivation contact structure, and then transported through the doped conductive layer to the metal electrode for collection. When the area of the tunneling layer is larger, a larger tunneling channel can be provided for the tunneling of the carriers, so as to increase the tunneling efficiency of the carriers. But, since the substrate surface of the non-metal pattern region is set smoothed, the roughness of the substrate surface of the non-metal pattern region is smaller, such that the surface area of the substrate surface of the non-metal pattern region is made smaller, thereby decreasing the area of the tunneling layer on the substrate surface of the non-metal pattern region, and resulting in that the carrier transport efficiency cannot be further improved.

An embodiment of the present disclosure provides a solar cell. In the solar cell, a non-metal pattern region of a first surface is disposed to be lower than a metal pattern region of the first surface, that is, the non-metal pattern region and the metal pattern region of the first surface form an uneven step structure. Compared with a substrate which has a smooth surface, the step structure can increase a surface area of the first surface of the substrate, so as to increase a surface area of the passivation contact structure covered on the first surface of the substrate. In this way, in a case of keeping the passivation contract structure over the non-metal pattern region relatively smooth, a tunneling channel for the carriers is enlarged and the tunneling efficiency of the carriers is thus increased.

Detailed descriptions will be made below to the embodiments of the present disclosure in combination with accompanying drawings. However, persons of ordinary skill in the art may understand, in the embodiments of the present disclosure, many technical details are proposed to help readers to better understand the present disclosure. Without these technical details and various changes and modifications based on the following embodiments, the technical solutions claimed by the present disclosure can still be implemented.

FIG.1is a schematic diagram illustrating a sectional structure of a first type of solar cell according to an embodiment of the present disclosure.

By referring toFIG.1, the solar cell includes a substrate100. The substrate has a first surface. The first surface includes a metal pattern region10and a non-metal pattern region11which are arranged in a spacing. The first surface has a height in the non-metal pattern region11lower than a height in the metal pattern region10. The solar cell includes a passivation contact structure110, covered on the first surface. The passivation contact structure110includes a tunneling layer111and a doped conductive layer112which are stacked in a direction away from the substrate.

Compared with the fact that the substrate100has a smooth surface, the non-metal pattern region11of the first surface is made lower than the metal pattern region10of the first surface to increase a surface area of the first surface of the substrate100, so as to increase a contact area of the passivation contact structure110with the first surface of the substrate100. In this way, in a case of keeping the passivation contact structure110over the non-metal pattern region11relatively smooth, a tunneling channel of the carriers can be enlarged and the tunneling efficiency of the carriers can be improved. Further, since the passivation contact structure110over the non-metal pattern region is smooth, passivation capability of the non-metal pattern region11of the first surface can be enhanced, and the short-circuit current and the open-circuit voltage can be increased, contributing to improve the photoelectric conversion performance of the solar cell.

Furthermore, a height difference between the non-metal pattern region11of the first surface and the metal pattern region10of the first surface forms a step structure. In addition, since the step structure is disposed at a junction between the metal pattern region10and the non-metal pattern region11, the area of the passivation contact structure110covered on the junction can be increased. Further, since the junction is adjacent to the metal pattern region10, the carriers in the passivation contact structure110at the junction can be transported to the passivation contact structure110over the metal pattern region10over a shorter distance. contributing to increase the collection capability for the carriers.

Furthermore, the non-metal pattern region11of the first surface is disposed lower than the metal pattern region10of the first surface, which is equivalent to increasing a surface area of the first surface in a height direction. Without increasing a cross sectional arca of the first surface of the substrate10, the area of the passivation contact structure110can be increased. Thus, when the solar cells are assembled to form a photovoltaic module, a large assembling density of the photovoltaic module can be maintained, which is favorable for maintaining a high assembly power. The height direction herein refers to a direction perpendicular to the first surface. The cross sectional area herein refers to a sectional area in a direction parallel to the first surface of the substrate100.

It is to be noted that the height in the non-metal pattern region11of the first surface and the height in the metal pattern region10of the first surface herein both are relative to a second surface of the substrate100. That is, the substrate has a thickness in the non-metal pattern region11less than a thickness in the metal pattern region10.

The substrate100is configured to receive incident light and generate photo-generated carriers. In some embodiments, the substrate100may be a silicon substrate, and a material of the silicon substrate may include at least one of monocrystalline silicon, polycrystalline silicon, amorphous silicon or microcrystalline silicon. In some embodiments, the material of the substrate100may alternatively be silicon carbide, organic material or poly-compound. The poly-compound may include, but not limited to, perovskite, gallium arsenide, cadmium telluride and copper indium diselenide and the like.

In some embodiments, the solar cell is a Tunnel Oxide Passivated Contact (TOPCON) cell, the substrate100has a second surface opposite to the first surface, and the first surface and the second surface of the substrate100both may be configured to receive incident light or reflective light. In some embodiments, the substrate100has a doped element, and the type of the doped element is N type or P type. The N type element may be V group element such as phosphorus (P) element, bismuth (Bi) element, antimony (Sb) element, or arsenic (As) element, and the P type element may be III group element such as boron (B) element, aluminum (Al) element, gallium (Ga) element or indium (In) element. For example, when the substrate100is a P type substrate, the type of the doped element in the substrate is P type; or, when the substrate100is a N type substrate, the type of the doped element in the substrate is N type.

In some embodiments, the solar cell further includes a first electrode130which is electrically connected with the doped conductive layer112.

The first electrode130may be in electrical contact with the doped conductive layer112. The photo-generated carriers from the substrate100are transported to the doped conductive layer112and then transported to the first electrode130. The first electrode130is configured to collect the photo-generated carriers. The first electrode130is disposed in the metal pattern region10.

In some embodiments, the height difference d between the non-metal pattern region11of the first surface and the metal pattern region10of the first surface is 0.2 μm to 10 μm, for example, may be 0.2 μm to 0.5 μm, 0.5 μm to lum, lum to 1.5 μm, 1.5 μm to 2 μm, 2 μm to 2.5 μm, 2.5 μm to 3 μm, 3 μm to 3.1 μm, 3.1 μm to 3.2 μm, 3.2 μm to 3.5 μm, 3.5 μm to 3.8 μm, 3.8 μm to 3.9 μm, 3.9 μm to 4 μm, 4 μm to 4.5 μm, 4.5 μm to 5 μm, 5 μm to 5.5 μm, 5.5 μm to 6 μm, 6 μm to 6.5 μm, 6.5 μm to 7 μm, 7 μm to 7.5 μm, 7.5 μm to 8 μm, 8 μm to 8.5 μm, 8.5 μm to 9 μm or 9 μm to 10 μm. Within this height range, the height difference d between the non-metal pattern region11of the first surface and the metal pattern region10of the first surface can be set larger, which contributes to increase the surface area of the first surface, and further increase the area of the tunneling layer111in the passivation contact structure110, thus providing a larger tunneling channel for the carriers and enhancing the transport of the carriers. On the other hand, the height difference d between the non-metal pattern region11of the first surface and the metal pattern region10of the first surface cannot be excessively large, which avoids the problem of an increased defect state density of the first surface of the substrate100resulting from excessive loss of the substrate100in an actual process of forming the height difference, thereby ensuring less carrier recombination at the first surface of the substrate100, and contributing to increase the fill factor of the solar cell.

By referring toFIGS.2and3, in some embodiments, the first surface has a first texture structure13in the metal pattern region10, and a second texture structure14in the non-metal pattern region11. The first texture structure13has a roughness greater than a roughness of the second texture structure14. The roughness of the first texture structure13is set larger so that the surface area of the metal pattern region10of the first surface can be increased, and further, the passivation contact structure110over the metal pattern region10of the first surface can continue the morphology in the metal pattern region10of the first surface. That is, a top surface of the passivation contact structure110in the metal pattern region also has a larger roughness, which increases the surface area of the passivation contact structure110, and further increases the contact area between the first electrode130in the passivation contact structure110and the passivation contact structure110. In this way, a contact resistance of the first electrode130can be reduced, and the carrier transport performance can be improved.

Since the step structure is formed on the first surface of the substrate100, the surface area of the first surface of the substrate100is increased in the height direction. Thus, by setting the roughness of the second texture structure14smaller, the surface of the non-metal pattern region11is made smoother. Hence, in a process of preparing the passivation contact structure110by a deposition process, the tunneling layer111and the doped conductive layer112deposited in the non-metal pattern region11of the first surface can uniformly cover the first surface, such that the morphologies of the tunneling layer111and the doped conductive layer112are smooth. Therefore, an interface morphology between the tunneling layer111and the first surface can be optimized to reduce an interface state density of the non-metal pattern region11of the first surface. This not only contributes to reduce recombination of the carriers at the non-metal pattern region11of the first surface but also can increase the tunneling capability of the carriers, thereby increasing the number of transported carriers and improving the photoelectric conversion performance of the solar cell.

In some embodiments, as shown inFIG.2, the first texture structure13includes a pyramid structure. The second texture structure14includes a platform embossed structure. In some embodiments, a height h1of the pyramid structure is greater than a height h2of the platform embossed structure, and a one-dimensional size L1of a bottom surface of the pyramid structure is less than an one-dimensional size L2of a bottom surface of the platform embossed structure.

The pyramid structure has a large specific surface area. The pyramid structure is included in the first texture structure, so as to further increase the surface area of the passivation contact structure110located in the metal pattern region10and the contact area of the passivation contact structure110with the first electrode, and to reduce a contact resistance.

In some embodiments, the pyramid structure may be a tetrahedron, an approximate tetrahedron, pentahedron or an approximate pentahedron or the like. The platform embossed structure is a base portion of the pyramid structure, namely, a remaining bottom structure obtained by removing a pyramid tip from the pyramid structure. In some embodiments, the second texture structure14may also be a platform-like embossed structure, a top surface of which may be a plane or an inclined surface and a bottom surface may be a polygonal plane, for example, may be a quadrilateral plane or a pentagonal plane.

In some embodiments, the height h1of the pyramid structure is 0.1 μm to 5 μm, for example, may be 0.1 μm to 0.2 μm, 0.2 μm to 0.5 μm, 0.5 μm to 1 μm, 1 μm to 1.5 μm, 1.5 μm to 2 μm, 2 μm to 2.5 μm, 2.5 μm to 3 μm, 3 μm to 3.5 μm, 3.5 μm to 4 μm, 4 μm to 4.5 μm or 4.5 μm to 5 μm. In some embodiments, the one-dimensional size L1of the bottom surface of the pyramid structure is 0.01 μm to 6 μm, for example, may be 0.01 μm to 0.05 μm, 0.05 μm to 0.08 μm, 0.08 μm to 0.1 μm, 0.1 μm to 0.2 μm, 0.2 μm to 0.5 μm, 0.5 μm to 1 μm, 1 μm to 1.5 μm, 1.5 μm to 2 μm, 2 μm to 2.5 μm, 2.5 μm to 3 μm, 3 μm to 3.5 μm, 3.5 μm to 4 μm, 4 μm to 4.5 μm, 4.5 μm to 5 μm, 5 μm to 5.5 μm or 5.5 μm to 6 μm. Within the ranges, the height of the pyramid structure can be set larger and the one-dimensional size of the bottom surface of the pyramid structure can be set smaller, such that the surface area of the pyramid structure can be increased so as to ensure a larger area of the passivation contact structure110over the metal pattern region10of the first surface, reduce a contact resistance between the first electrode130and the passivation contact structure110, and improve the collection capability of the first electrode130for the carriers. Further, within the ranges, the height of the pyramid structure cannot be excessively large and the one-dimensional size of the bottom surface of the pyramid structure cannot be excessively small, so that the following problem can be avoided: the passivation contact structure110deposited in the metal pattern region10of the first surface has a lower smoothness due to excessively large roughness of the first texture structure13, which further leads to poor surface passivation capability of the passivation contact structure110in the metal pattern region10.

The one-dimensional size of the bottom surface of the pyramid structure refers to an average value by performing averaging on the one-dimensional sizes of the bottom surfaces of the pyramid structures in a randomly-designated zone within the metal pattern region10. The height of the pyramid structure refers to an average value obtained by performing averaging on the heights of the pyramid structures in a randomly-designated zone within the metal pattern region10.

The one-dimensional size of the bottom surface of the platform embossed structure refers to an average value obtained by performing averaging on the one-dimensional sizes of the bottom surfaces of the platform embossed structures in a randomly-designated zone within the non-metal pattern region11. The height of the platform embossed structure refers to a mean value obtained by performing averaging on the heights of the platform embossed structures in a randomly-designated zone within the non-metal pattern region11.

By referring toFIG.4, in some embodiments, the first surface includes: a transitional region12adjacent to the metal pattern region10and the non-metal pattern region11. A height of the transitional region12is not lower than the height in the non-metal pattern region11and not higher than the height in the metal pattern region10. The passivation contact structure110is covered on the transitional region12. The transitional region12adjoins both the metal pattern region10and the non-metal pattern region11respectively. The metal pattern region10, the non-metal pattern region11and the transitional region12form a step structure. Due to presence of the transitional region12, the area of the first surface is increased so as to increase the area of the passivation contact structure110on the first surface, thereby providing a larger tunneling channel and transport channel for the carriers and improving the carrier transport capability.

Since the transitional region12is disposed adjacent to the metal pattern region10, when the passivation contact structure110is covered on the transitional region12, the passivation contact structure110on the transitional region12is also adjacent to the metal pattern region10. Hence, the carriers in the passivation contact structure110on the transitional region12can be transported to the first electrode130over a shorter distance, thereby reducing the transport loss and improving the number of transported carriers.

In some embodiments, the transitional region is disposed inclined relative to the non-metal pattern region, such that the passivation contact structure110covered on the transitional region12is inclined relative to the passivation contact structure110in the non-metal pattern region. Compared with increasing the surface area of the non-metal pattern region of the first surface by increasing the roughness of the non-metal pattern region of the first surface to increase the surface area of the passivation contact structure110, increasing the area of the passivation contact structure110by disposing the step structure on the first surface of the substrate100is more conducive to improving the carrier transport efficiency. The reason is that, if the roughness of the non-metal pattern region of the first surface is increased, the part of the increased area of the passivation contact structure110is still located in the non-metal pattern region of the first surface, and the transport distance of the carriers between the passivation contact structure110and the first electrode130is not shortened. Since the transitional region12is adjacent to the metal pattern region, the carriers in the passivation contact structure110covered on the transitional region12can be transported to the first electrode130over a shorter distance, thus reducing the transport loss and improving the carrier transport efficiency.

In some embodiments, the transitional region12may be perpendicular to both the metal pattern region10of the first surface and the non-metal pattern region11of the first surface.

In some embodiments, the transitional region12may alternatively be inclined relative to the non-metal pattern region11and the metal pattern region10. Hence, in a case of keeping the height difference between the non-metal pattern region11and the metal pattern region10unchanged, as compared with the fact that the transitional region12is perpendicular to the metal pattern region10and the non-metal pattern region11, the area of the passivation contact structure110on the transitional region12is increased, which provides a larger tunneling channel and transport channel for the carriers.

Based on the above considerations, in some embodiments, there is an included angle between the non-metal pattern region11and the transitional region12. The included angle θ is in a range of 90° to 160°, for example, may be 90° to 95°, 95° to 100°, 100° to 105°, 105° to 110°, 110° to 115°, 115° to 120°, 120° to 125°, 125° to 130°, 130° to 135°, 135° to 140°, 140° to 145°, 145° to 150°, 150° to 155° or 155° to 160°. Within this range, the transitional region can be inclined relative to the non-metal pattern region11such that the transitional region12has a larger surface area, which increases the area of the passivation contact structure110on the transitional region12, thereby providing a larger tunneling channel for the carriers and increasing the carrier tunneling probability.

By referring toFIG.5, in some embodiments, the transitional region has a third texture structure15, which has a roughness less than the roughness of the first texture structure13. By disposing the third texture structure15on the transitional region12, the surface area of the transitional region12can be further increased so as to increase the area of the passivation contact structure110on the transitional region12.

In some embodiments, the third texture structure includes a plurality of triangular-prism-shaped embossed structures adjacent to each other. each of the plurality of triangular-prism-shaped embossed structures has a sectional shape of triangular or triangle-like in a direction perpendicular to the transitional region12. There are three edges on sides of each of the plurality of triangular-prism-shaped embossed structures, where two edges are located on the transitional region12and the remaining one protrudes out of the transitional region12. The plurality of triangular-prism-shaped embossed structures stretch across the transitional region12in a direction pointing from the non-metal pattern region11to the metal pattern region10. In this way, the surface area of the third texture structure15is increased. It may be easily found that the sides of the triangular-prism-shaped embossed structures form the transitional region12. The sides of the triangular-prism-shaped embossed structures are smooth and across the transitional region12, such that the passivation contact structure110deposited on the transitional region12is smooth, which is conducive to the tunneling of the carriers. Further, the third texture structure15disposed on the transitional region12can further increase the area of the passivation contact structure110.

The doped conductive layer112has the effect of field passivation, such that minority carriers escape from an interface so as to reduce a concentration of the minority carriers. Thus, the carrier recombination rate at the interface of the substrate100can be reduced, and an open circuit voltage, a short circuit current and a fill factor of the solar cell can be increased, thereby improving the photoelectric conversion performance of the solar cell.

The tunneling layer111is configured to perform interface passivation on the first surface to achieve the effect of chemical passivation. Specifically, by using dangling bonds of the saturated first surface, an interface defect state density of the first surface can be decreased so as to lessen the recombination centers of the first surface.

As shown inFIG.6, in some embodiments, the tunneling layer includes at least one first tunneling layer21and at least one second tunneling layer31. The doped conductive layer includes at least one first doped conductive layer22and at least one second doped conductive layer32. The passivation contact structure includes a first passivation contact structure20located over the metal pattern region10of the first surface. The first passivation contact structure20includes at least one first tunneling layer21and at least one first doped conductive layer22stacked in a direction away from the substrate100. The passivation contact structure includes a second passivation contact structure30, including first portion and second portion adjacent to each other. The first portion covers side surfaces and a top surface of the first passivation contact structure20, and the second portion covers the remaining first surface other than the metal pattern region10of the first surface. The second passivation contact structure30includes at least one second tunneling layer31and at last one second doped conductive layer32stacked in the direction away from the substrate100.

The second passivation contact structure20covers not only the non-metal pattern region but also the transitional region12. Thus, the second passivation contact structure30is a continuous film layer which can improve the transverse transport performance of the carriers in the second passivation contact structure30, thereby contributing to transport the carriers.

In some embodiments, the first electrode130penetrates through the second passivation contact structure30to be in electrical contact with the first doped conductive layer22so as to collect carriers transported in the second doped conductive layer32and the first doped conductive layer22.

Since the first passivation contact structure20and the second passivation contact structure30are disposed in the metal pattern region10of the first surface at the same time, a probability that the first electrode130penetrates through the first passivation contact structure20and the second passivation contact structure30to the substrate100can be reduced in an actual process of preparing the first electrode130, thereby reducing generation of the carrier recombination centers.

Furthermore, since the second passivation contact structure30covers the first passivation contact structure20and the remaining surface of the first surface other than the surface covered by the first passivation contact structure, namely, the first passivation contact structure20does not contact incident light directly, and the probability that the first electrode130penetrates through to the substrate100can be further reduced without increasing the parasitic absorption of the first passivation contact structure20for incident light. Further, in order to reduce the parasitic absorption of the second passivation contact structure30for incident light, the thickness of the second doped conductive layer32may be set smaller, so as to improve the parasitic utilization rate of the substrate100for incident light.

That is, in the stacked first passivation contact structure20and second passivation contact structure30, the second passivation contact structure30is configured to achieve the effect of reducing the parasitic absorption for incident light and improving transverse transport of the carriers, and the first passivation contact structure20is configured to reduce the probability that the metal electrode penetrates through to the substrate100, thereby entirely improving the photoelectric conversion performance of the solar cell.

In some embodiments, the first passivation contact structure20may only include one first tunneling layer21and one first doped conductive layer22, and the first tunneling layer21is in direct contact with the first surface.

By referring toFIG.7, in some embodiments, the first passivation contact structure20may alternatively include a plurality of sub-first passivation contact structures23sequentially stacked in a direction away from the substrate100, and each sub-first passivation contact structure23includes a first tunneling layer21and a first doped conductive layer22sequentially stacked in the direction away from the substrate100. That is, the first passivation contact structure20may include a plurality of first tunneling layers21and a plurality of first doped conductive layers22, which are alternately stacked.FIG.7shows two sub-first passivation contact structures23.

In some embodiments, the second passivation contact structure30may only include one second tunneling layer31and one second doped conductive layer32, where the second tunneling layer31covers a top surface of the first passivation contact structure20and the non-metal pattern region11of the first surface. In some embodiments, when the second passivation contact structure30only includes one second tunneling layer31and one second doped conductive layer32, the first passivation contact structure20may include a plurality of sub-first passivation contact structures23or only include one first tunneling layer21and one first doped conductive layer22.

By referring toFIG.8, in some embodiments, the second passivation contact structure30may include a plurality of sub-second passivation contact structures33sequentially stacked in a direction away from the substrate100, and each sub-second passivation contact structure33includes a second tunneling layer31and a second doped conductive layer32sequentially stacked in the direction away from the substrate100. That is, the second passivation contact structure30may include a plurality of second tunneling layers31and a plurality of second doped conductive layers32, which are alternately stacked.FIG.8shows two sub-second passivation contact structures33.

By referring toFIG.8, in some embodiments, when the second passivation contact structure30includes a plurality of sub-second passivation contact structures33, the first passivation contact structure20may include a plurality of sub-first passivation contact structures23.

In some embodiments, when the second passivation contact structure30includes a plurality of sub-second passivation contact structures33, the first passivation contact structure20may only include one first tunneling layer21and one first doped conductive layer22, as long as the second passivation contact structure30can wrap the first passivation contact structure20.

In some embodiments, a plurality of first passivation contact structures20and a plurality of second passivation contact structures30are disposed, where the plurality of first passivation contact structures20and the plurality of second passivation contact structures30are alternately stacked in a direction away from the substrate100. Each second passivation contact structure30covers the top surface and the side surfaces of a respective first passivation contact structure20, the second passivation contact structure30close to the substrate100covers the non-metal pattern region11of the first surface, and the remaining second passivation contact structures30cover the top surface of a neighboring second passivation contact structure30. In other words, as shown inFIG.9, two sub-first passivation contact structures23and two sub-second passivation contact structures33are alternately stacked in the direction away from the substrate100.

Alternatively, in other words, tunneling layers and doped conductive layers included in the first and second passivation contact structures may include one layer or multiple sub-layers, as long as the first and second passivation contact structures are stacked to increase the thickness of the passivation contact structure. The detailed illustration is as follows.

In some embodiments, the first passivation contact structure20may only include one first tunneling layer21and one first doped conductive layer22, and the second passivation contact structure30may only include one second tunneling layer31and one second doped conductive layer32, as shown inFIG.6.

In some embodiments, the first passivation contact structure20includes a plurality of sub-first passivation contact structures23sequentially stacked in the direction away from the substrate100, and each of the plurality of sub-first passivation contact structures23includes a first tunneling sub-layer21and a first doped conductive sub-layer22sequentially stacked in the direction away from the substrate.FIG.7shows two sub-first passivation contact structures, and the second passivation contact structure33only including one second tunneling layer31and one second doped conductive layer32.

In some embodiments, the first passivation contact structure20includes a plurality of sub-first passivation contact structures23sequentially stacked in the direction away from the substrate100, and each of the plurality of sub-first passivation contact structures23includes a first tunneling sub-layer21and a first doped conductive sub-layer22sequentially stacked in the direction away from the substrate. The second passivation contact structure30includes a plurality of sub-second passivation contact structures33sequentially stacked in the direction away from the substrate100, and each of the plurality of sub-second passivation contact structures33includes a second tunneling sub-layer31and a second doped conductive sub-layer32sequentially stacked in the direction away from the substrate.FIG.8shows two sub-first passivation contact structures and two sub-second passivation contact structures sequentially stacked, andFIG.9shows two sub-first passivation contact structures and two sub-second passivation contact structures alternately stacked.

When there are a plurality of sub-first passivation contact structures23and/or a plurality of sub-second passivation contact structures33, correspondingly, there are a plurality of first tunneling sub-layers, a plurality of first doped conductive sub-layers, a plurality of second tunneling sub-layers, a plurality of second doped conductive sub-layers, respectively. In the preparing process of the solar cell, the plurality of sub-layers are considered as a whole, and the configurations for concentration of doping elements, thickness and material in the following embodiments apply to the embodiments concerning about single layer and the plurality of sub-layers.

In some embodiments, a concentration of a doped element in the first doped conductive layer22is greater than or equal to a concentration of a doped element in the second doped conductive layer32. In some embodiments, the concentration of the doped element in the first doped conductive layer22and the concentration of the doped element in the second doped conductive layer32both are greater than a concentration of the doped element in the substrate100, such that the first doped conductive layer22and the second doped conductive layer32form a heavily-doped region relative to the substrate100. The heavily-doped region and the substrate100form a high-low junction which enables the carriers to generate a barrier effect. Thus, the transport rate and the number of the carriers transported from the substrate100to the first doped conductive layer22and the second doped conductive layer32are increased, and hence the first electrode130can collect the carriers effectively.

In some embodiments, the concentration of the doped element in the first doped conductive layer22may be greater than the concentration of the doped element in the second doped conductive layer32. The first doped conductive layer22is located in the metal pattern region10and in electrical contact with the first electrode130. By setting the concentration of the doped element in the first doped conductive layer22larger, the barrier effect of the carriers can be further enhanced, so as to increase a tunneling probability of the carriers in the substrate100as well as the carrier concentration of the first doped conductive layer22, helping the first electrode130to collect more carriers.

The second doped conductive layer32covers the non-metal pattern region11of the first surface. By setting the concentration of the doped element in the second doped conductive layer32less, generation of auger recombination at the non-metal pattern region11of the first surface can be lessened, so as to reduce recombination of the carriers at the non-metal pattern region11of the first surface and improve the passivation effect on the non-metal pattern region11of the first surface, helping to further increase the number of the transported carriers as well as the open circuit voltage and the short circuit current.

In some embodiments, the concentration of the doped element in the first doped conductive layer22is in a range of 5×1018atoms/cm3to 1×1021atoms/cm3, for example, may be 5×1018atoms/cm3to 7×1018atoms/cm3, 7×1018atoms/cm3to 9×1018atoms/cm3, 9×1018atoms/cm3to 1×1019atoms/cm3, 1×1019atoms/cm3to 5×1019atoms/cm3. 5×1019atoms/cm3to 1×1020atoms/cm3, 1×1020atoms/cm3to 5×1020atoms/cm3or 5×1020atoms/cm3to 1×1021atoms/cm3. In some embodiments, the concentration of the doped element of the second doped conductive layer32is 5×1018atoms/cm3to 9×1020atoms/cm3, for example, may be 5×1018atoms/cm3to 7×1018atoms/cm3. 7×1018atoms/cm3to 1×1019atoms/cm3, 1×1019atoms/cm3to 5×1019atoms/cm3. 5×1019atoms/cm3to 9×1019atoms/cm3. 9×1019atoms/cm3to 1×1020atoms/cm3, 1×1020atoms/cm3to 5×1020atoms/cm3or 5×1020atoms/cm3to 9×1020atoms/cm3. Within the above range, the concentration of the doped element in the first doped conductive layer22may be set to larger to increase the tunneling capability of the carriers in the substrate100corresponding to the metal pattern region10, and improve the collection capability of the first electrode130for the carriers. Further, the concentration of the doped element in the second doped conductive layer32may be set to be within the above range, such that the doping concentration of the second doped conductive layer32is smaller, which ensures the surface passivation capability of the second doped conductive layer32on the non-metal pattern region11of the first surface.

In some embodiments, the concentration of the doped element in the first doped conductive layer22may be equal to the concentration of the doped element in the second doped conductive layer32.

In some embodiments, a thickness of the first doped conductive layer22is greater than or equal to a thickness of the second doped conductive layer32. In some embodiments, the thickness of the first doped conductive layer22is greater than the thickness of the second doped conductive layer32. By setting the thickness of the first doped conductive layer22larger, the probability that the first electrode130penetrates through to the substrate100can be reduced, and the contact area of the first doped conductive layer22with the first electrode130can be increased. Thus, the contact resistance can be reduced, and the transport loss of transporting the carriers to the first electrode130can be diminished, contributing to enhance the collection capability of the first electrode130for the carriers. By setting the thickness of the second doped conductive layer32smaller, the parasitic absorption of the second doped conductive layer32for incident light can be reduced, and the absorption utilization rate of the substrate100for incident light can be improved, thereby improving the photoelectric conversion performance.

In some embodiments, the thickness of the first doped conductive layer22is in a range of 5 nm to 500 nm, for example, may be 5 nm to 10 nm, 10 nm to 50 nm, 50 nm to 80 nm, 80 nm to 100 nm, 100 nm to 150 nm, 150 nm to 200 nm, 200 nm to 250 nm, 250 nm to 300 nm, 300 nm to 350 nm, 350 nm to 400 nm, 400 nm to 450 nm or 450 nm to 500 nm. In some embodiments, the thickness of the second doped conductive layer32is in a range of 1 nm to 200 nm, for example, may be 1 nm to 5 nm, 5 nm to 10 nm, 10 nm to 30 nm, 30 nm to 50 nm, 50 nm to 80 nm, 80 nm to 100 nm, 100 nm to 130 nm, 130 nm to 150 nm, 150 nm to 170 nm, 170 nm to 185 nm or 185 nm to 200 nm. Within the above range, the thickness of the first doped conductive layer22may be set larger, which can effectively reduce the probability that the first electrode130penetrates through the first doped conductive layer22. Within the above range, the thickness of the second doped conductive layer32may be set smaller, which can reduce the parasitic absorption of the second doped conductive layer32for incident light. In this way, the absorptivity of the substrate100for incident light can be improved.

In some embodiments, the thickness of the first doped conductive layer22may be equal to the thickness of the second doped conductive layer32.

In some embodiments, a material of the first doped conductive layer22includes at least one of amorphous silicon, polycrystalline silicon, and silicon carbide, and a material of the second doped conductive layer32includes at least one of amorphous silicon, polycrystalline silicon, and silicon carbide. In some embodiments, the material of the first doped conductive layer22may be same as the material of the second doped conductive layer32. In some embodiments, the material of the first doped conductive layer22may alternatively be different from the material of the second doped conductive layer32.

In some embodiments, a thickness of the first tunneling layer21may be less than or equal to a thickness of the second tunneling layer31. In some embodiments, the thickness of the first tunneling layer21may be less than the thickness of the second tunneling layer31. The first tunneling layer21is in direct contact with the first surface at the metal pattern region10to achieve tunneling of majority carriers and selective transport of the carriers. Due to the smaller thickness of the first tunneling layer21, the carriers in the substrate100corresponding to the metal pattern region10can more easily pass through the first tunneling layer21, thereby increasing the tunneling probability of the carriers and further increasing the transport efficiency of the carriers. Furthermore, since the first tunneling layer21has a smaller thickness, when the first tunnel layer21is deposited actually, the first tunneling layer21obtained by depositing has a high uniformity, which can improve a contact section morphology between the first tunneling layer21and the first surface, facilitating the tunneling of the carriers.

The thickness of the second tunneling layer31is set larger, which makes it difficult for the conductive paste for forming the first electrode130to burn through the second tunneling layer31during the process of preparing the first electrode130. In this way, the probability that the first electrode130penetrates through to the substrate100can be further reduced, and the generation of the carrier recombination centers can be lessened.

In some embodiments, the thickness of the first tunneling layer21is in a range of 0.1 nm to 5 nm, for example, may be 0.1 nm to 0.5 nm, 0.5 nm to 0.8 nm, 0.8 nm to 1 nm, 1 nm to 1.5 nm, 1.5 nm to 2 nm, 2 nm to 2.5 nm, 2.5 nm to 3 nm, 3 nm to 3.5 nm, 3.5 nm to 4 nm, 4 nm to 4.5 nm or 4.5 nm to 5 nm; the thickness of the second tunneling layer31is in a range of 0.2 nm to 10 nm, for example, may be 0.2 nm to 0.5 nm, 0.5 nm to 0.8 nm, 0.8 nm to 1.2 nm, 1.2 nm to 2 nm, 2 nm to 2.5 nm, 2.5 nm to 3 nm, 3 nm to 3.5 nm, 3.5 nm to 4 nm, 4 nm to 4.5 nm, 4.5 nm to 5 nm, 5 nm to 6 nm, 6 nm to 7 nm, 7 nm to 8 nm, 8 nm to 9 nm or 9 nm to 10 nm. Within the above range, on one hand, the thickness of the first tunneling layer21may be set smaller, which contributes to enhance the tunneling of the carriers in the substrate100corresponding to the metal pattern region10; further, within the above range, the thickness of the first tunneling layer21cannot be excessively small, which can prevent the problem of formation of cavities in a deposition process due to small thickness.

Within the above range, the thickness of the second tunneling layer31may be set larger, and the probability that the first electrode130burns through to the substrate100can be reduced by adjusting the thickness of the second tunneling layer31to be larger.

In some embodiments, the thickness of the first tunneling layer21may be same as the thickness of the second tunneling layer31.

In some embodiments, the material of the first tunneling layer21is different from the material of the second tunneling layer31. By making the materials of the first tunneling layer21and the second tunneling layer31different, the respective functions of the first tunneling layer21and the second tunneling layer31can be enhanced. For example, the tunneling effect of the first tunneling layer21for the carriers can be enhanced and the blocking effect of the second tunneling layer31for the turning-through of the first electrode130can be enhanced.

In some embodiments, the material of the first tunneling layer21includes at least one of silicon oxide, aluminum oxide, silicon nitride, silicon oxynitride, amorphous silicon or polycrystalline silicon. In some embodiments, the material of the second tunneling layer31includes at least one of silicon oxide, aluminum oxide, silicon nitride, silicon oxynitride, amorphous silicon or polycrystalline silicon.

In some embodiments, a pinhole density of the material of the first tunneling layer21is less than a pinhole density of the material of the second tunneling layer31. Due to smaller pinhole density of the material of the first tunneling layer21, the probability that the carriers pass through the first tunneling layer21can be increased. Due to the larger pinhole density of the material of the second tunneling layer31, the burning-through capability of the conductive paste for preparing the first electrode130can be further reduced, and the probability that the first electrode130penetrates the first passivation contact structure20can be decreased, and the defect state density of the second tunneling layer31can be reduced, and thus the passivation performance of the second tunneling layer31for the non-metal pattern region11of the first surface can be improved. In view of this, in some embodiments, the material of the first tunneling layer21may be silicon nitride and the material of the second tunneling layer31may be silicon oxide.

In some embodiments, the solar cell further includes a first passivation layer140which is located on a surface of the second passivation contact structure30away from the substrate100. The first passivation layer140can achieve passivation effect on the first surface, for example, achieve good chemical passivation on dangling bonds of the first surface, so as to reduce a defect state density of the first surface and suppress the carrier recombination at the first surface.

In some embodiments, the first passivation layer140may be a single-layer structure. In some embodiments, the first passivation layer140may a be multi-layer structure. In some embodiments, a material of the first passivation layer140may be at least one of silicon oxide, aluminum oxide, silicon nitride, or silicon oxynitride.

In some embodiments, the first electrode130may penetrate through the first passivation layer140and the second passivation contact structure30to be in electrical contact with the first doped conductive layer22.

In some embodiments, the solar cell further includes an emitter150which is located on the second surface of the substrate100. The emitter150is contrary to the substrate100in the type of doped element and forms a PN junction with the substrate100. In some embodiments, a material of the emitter150may be same as the material of the substrate100.

In some embodiments, the solar cell further includes a second passivation layer160, which is located on a surface of the emitter150away from the substrate100. The second passivation layer160is configured to achieve good passivation effect on the second surface of the substrate100, reduce the defect state density of the second surface and suppress the carrier recombination at the back surface of the substrate100well. The second passivation layer160can also achieve good anti-reflection effect, contributing to reduce reflection of incident light and improve the utilization rate of incident light.

In some embodiments, the second passivation layer160may be a single-layer structure. In some embodiments, the second passivation layer160may also be a multi-layer structure. In some embodiments, a material of the second passivation layer160may be at least one of silicon oxide, aluminum oxide, silicon nitride, or silicon oxynitride.

In some embodiments, the solar cell further includes a second electrode170, which is located on the second surface of the substrate100. The second electrode170penetrates through the second passivation layer160to be in electrical contact with the emitter150.

In the solar cell provided by the embodiments of the present disclosure, the non-metal pattern region11of the first surface is disposed to be lower than the metal pattern region10of the first surface, that is, a step structure is formed by the non-metal pattern region11and the metal pattern region10. Compared with the substrate100surface which is a smooth surface, the step structure can increase a surface area of the first surface of the substrate100, so as to increase a surface area of the passivation contact structure110covered on the first surface of the substrate. In this way, in a case of keeping the passivation contract structure110of the non-metal pattern region11relatively smooth, a tunneling channel for the carriers can be enlarged and the tunneling efficiency of the carriers can be thus increased.

According to another aspect of embodiments of the present disclosure, a photovoltaic module is provided. As shown inFIG.10, the photovoltaic module includes a plurality of cell strings. Each of the plurality of cell strings is formed by connecting a plurality of solar cells101, each of which is provided by the above embodiments. The photovoltaic module includes encapsulation layers102, configured to cover surfaces of the plurality of cell strings. The photovoltaic module includes cover plates, configured to cover surfaces of the encapsulation layers102away from the plurality of cell strings. The plurality of solar cells are electrically connected in the form of an entire sheet or multiple split sheets, so as to form the plurality of cell strings which are electrically connected by series connection and/or parallel connection.

Specifically, in some embodiments, two neighboring cell strings in the plurality of cell strings may be electrically connected by a conductive band104. The encapsulation layers102cover the first surface and the back surface of the solar cells101. Specifically, the encapsulation layer102may be an organic encapsulation glue film such as an ethylene-vinyl acetate copolymer (EVA) glue film, a polyolyaltha olfin elastomer (POE) glue film, or a polyethylene terephthalate (PET) glue film or a polyvinyl butyral resin (PVB) or the like. In some embodiments, the cover plate103may be a glass cover plate or a plastic cover plate or a cover plate having a light transmission function. Specifically, a surface of the cover plate103facing toward the encapsulation layer102may be an uneven surface for increasing a utilization rate of incident light.

The above descriptions are made as above with preferred embodiments, but these embodiments are not intended to limit the claims. Without departing from the application idea of the present disclosure, those skilled in the art can make several possible changes and modifications. Thus, the scope of protection of the present disclosure shall be defined by the appended claims.

Persons of ordinary skill in the art may understand that, the above embodiments are specific embodiments for implementation of the present disclosure and may be changed in form or details without departing from the spirit and scope of the present disclosure in practical applications. Those skilled in the art can make various changes and modifications within the spirit and scope of the present disclosure. Thus, the scope of protection of the present disclosure shall be defined by the claims.