Patent Description:
Photovoltaic cells have good photoelectric conversion capabilities. Generally, texture treatment needs to be performed first in the process of preparing a photovoltaic cell, so that a front surface and a rear surface of a substrate have a texture structure. The texture structure has an important influence on absorption of incident light of the substrate, uniformity of film layers subsequently deposited on the substrate and contact performance with an interface of the substrate, thereby further affecting photoelectric conversion performance of the photovoltaic cell.

However, conventional photovoltaic cells have low photoelectric conversion efficiency.

Patent <CIT> discloses relevant technology regarding a solar cell and a photovoltaic module, which are at least conducive to improving photoelectric conversion efficiency of the photovoltaic cell. In this document, the photovoltaic cell comprises a substrate, wherein the substrate has a textured surface, with a plurality of first pyramid structures and a plurality of second pyramid structures disposed in metal pattern regions. A dimension of a bottom portion of each of the plurality of first pyramid structures is greater than a dimension of a bottom portion of each of the plurality of second pyramid structures.

Some embodiments of the present disclosure provide a photovoltaic cell and a photovoltaic module, which are at least conducive to improving photoelectric conversion efficiency of the photovoltaic cell.

The present invention provides a photovoltaic cell including: a substrate, wherein the substrate has a front surface with a plurality of metal pattern regions and a plurality of non-metal pattern regions; a plurality of first pyramid structures and a plurality of second pyramid structures disposed in each of the plurality of metal pattern regions, wherein a one-dimensional dimension of a bottom portion of each of the plurality of first pyramid structures is greater than a one-dimensional dimension of a bottom portion of each of the plurality of second pyramid structures in a same direction; a plurality of third pyramid structures and a plurality of fourth pyramid structures disposed in each of the plurality of non-metal pattern regions, wherein a one-dimensional dimension of a bottom portion of each of the plurality of third pyramid structures is greater than a one-dimensional dimension of a bottom portion of each of the plurality of fourth pyramid structures in the same direction; and wherein an area proportion of the plurality of first pyramid structures on a portion of the front surface of the substrate in each respective metal pattern region is greater than an area proportion of the plurality of third pyramid structures on a portion of the front surface of the substrate in each respective non-metal pattern region; a first tunneling layer and a first doped conductive layer formed only in each respective metal pattern region and stacked on the portion of the front surface of the substrate in each respective metal pattern region in a direction away from the substrate; and a second tunneling layer and a second doped conductive layer stacked on a rear surface of the substrate in a direction away from the substrate.

In some embodiments, the area proportion of the plurality of first pyramid structures on the portion of the front surface of the substrate in each respective metal pattern region is greater than an area proportion of the plurality of second pyramid structures on the portion of the front surface of the substrate in each respective metal pattern region.

In some embodiments, the area proportion of the plurality of first pyramid structures on the portion of the front surface of the substrate in each respective metal pattern region is in a range of <NUM> % to <NUM>%, and the area proportion of the plurality of second pyramid structures on the portion of the front surface of the substrate in each respective metal pattern region is in a range of <NUM> % to <NUM>%.

In some embodiments, the one-dimensional dimension of the bottom portion of each of the plurality of first pyramid structures is in a range of <NUM> to <NUM>, and the one-dimensional dimension of the bottom portion of each of the plurality of second pyramid structures is less than <NUM>.

In some embodiments, a thickness of the first tunneling layer is in a range of <NUM> to <NUM>, and a thickness of the first doped conductive layer is in a range of <NUM> to <NUM>.

In some embodiments, the first doped conductive layer includes first doping elements, the first doping elements have been annealed and activated to obtain activated first doping elements, and an activation rate of the first doping elements in the first doped conductive layer is in a range of <NUM> % to <NUM>%.

In some embodiments, a concentration of the activated first doping elements is in a range of <NUM><NUM>atom/cm<NUM> to <NUM> × <NUM><NUM>atom/cm<NUM>.

In some embodiments, a height from top to bottom of each of the plurality of first pyramid structures is not less than a height of from top to bottom of each of the plurality of second pyramid structures.

In some embodiments, the area proportion of the plurality of third pyramid structures on the portion of the front surface of the substrate in the respective non-metal pattern region is greater than an area proportion of the plurality of fourth pyramid structures on the portion of the front surface of the substrate in the respective non-metal pattern region.

In some embodiments, the area proportion of the plurality of third pyramid structures on the portion of the front surface of the substrate in each respective non-metal pattern region is in a range of <NUM> % to <NUM>%, and the area proportion of the plurality of fourth pyramid structures on the portion of the front surface of the substrate in each respective non-metal pattern region is in a range of <NUM> % to <NUM>%.

In some embodiments, the one-dimensional dimension of the bottom portion of each of the plurality of third pyramid structures is in a range of <NUM> to <NUM>, and a one-dimensional dimension of the bottom portion of each of the plurality of fourth pyramid structures is less than <NUM>.

In some embodiments, a reflectivity of the portion of the front surface of the substrate in each respective non-metal pattern region is in a range of <NUM> % to <NUM>%.

In some embodiments, the photovoltaic cell further includes a first passivation layer, wherein a first portion of the first passivation layer is disposed on a surface of the first doped conductive layer away from the substrate, and a second portion of the first passivation layer is disposed on the portion of the front surface of the substrate in each respective non-metal pattern region.

In some embodiments, the first portion of the first passivation layer is not flush with the second portion of the first passivation layer.

In some embodiments, the photovoltaic cell further includes a first electrode disposed in each respective metal pattern region and electrically connected to the first doped conductive layer.

In some embodiments, the photovoltaic cell further includes a diffusion region disposed inside a portion of the substrate in each respective metal pattern region, wherein a top portion of the diffusion region is in contact with the first tunneling layer, and a doping element concentration of the diffusion region is greater than a doping element concentration of the substrate.

In some embodiments, a doping element type of the first doped conductive layer is the same as a doping element type of the substrate, and a doping element type of the second doped conductive layer is different from the doping element type of the first doped conductive layer.

In some embodiments, the substrate includes an N-type substrate.

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

Some embodiments of the present disclosure provide a photovoltaic module including: at least one cell string, each of the at least one cell string formed by a plurality of photovoltaic cells according to the above embodiments which are electrically connected; at least one encapsulation layer, each of the at least one encapsulation layer configured to cover a surface of a respective cell string; and at least one cover plate, each of the at least one cover plate configured to cover a surface of a respective encapsulation layer facing away from the respective cell string.

One or more embodiments are described as examples with reference to the corresponding figures in the accompanying drawings, and the examples do not constitute a limitation to the embodiments. The figures in the accompanying drawings do not constitute a proportion limitation unless otherwise stated.

It is seen from BACKGROUND that, generally, conventional photovoltaic cells have low photoelectric conversion efficiency.

It is found that reasons for the low photoelectric conversion efficiency of the conventional photovoltaic cells are at least the following. First, a diffusion process is usually used to convert a portion of a substrate to an emitter on a front surface of the substrate, and doping elements in the emitter are of different types from those in the substrate such that the emitter forms a PN junction with the substrate. However, this kind of structure causes carrier recombination of a portion of the front surface of the substrate in a metal pattern region to be too large, thereby affecting an open-circuit voltage and conversion efficiency of the photoelectric cell. Secondly, for a texture surface of the substrate, a morphology of each texture structure of the texture surface is usually concerned, but dimension arrangement of overall texture structures is less concerned. In fact, the dimension arrangement of the overall texture structures has a great influence on the uniformity of film deposition on the surface of the substrate and the quality of bonding between the film layers and the texture surface. For example, when the quality of bonding between the film layers and the texture surface is poor, a contact surface between the film layers and the surface of the substrate may be uneven, thereby increasing the interface defects on the surface of the substrate, which further affects the mobility of the carriers and results in poor photoelectric conversion performance of the photovoltaic cell.

In the photovoltaic cell provided in the embodiments of the present disclosure, an area proportion of a plurality of first pyramid structures with larger dimensions in a respective metal pattern region is greater than an area proportion of a plurality of third pyramid structures with larger dimensions in a respective non-metal pattern region, so that uniformity of dimensions of pyramid structures in the metal pattern region is higher and roughness of the pyramid structures in the metal pattern region is greater, compared to those of pyramid structures in the non-metal pattern region. In this way, in an actual operation of depositing a first tunneling layer and a first doped conductive layer, deposition probabilities at different positions of the metal pattern region are similar to each other, so that uniformity of thicknesses of the deposited first tunneling layer and the deposited first doped conductive layer is improved, thereby reducing defects at an interface between the first tunneling layer and the front surface of the substrate, and improving mobility of carriers in the substrate to the first doped conductive layer.

In addition, the area proportion of the plurality of third pyramid structures with the larger dimensions in the non-metal pattern region is relatively small, i.e., the number of the third pyramid structures and the fourth pyramid structures per unit area in the non-metal pattern region is larger, and diffuse reflection effect on the incident light is generated between adjacent third pyramid structures or between a third pyramid structure and a fourth pyramid structure adjacent to each other, so that the reflectivity of the incident light is reduced. Moreover, the first doped conductive layer is not provided on a portion of the front surface of the substrate in the non-metal pattern region, so that absorption of the incident light in the non-metal pattern region is greatly increased. In the embodiments of the present disclosure, based on the structure in which the first tunneling layer and the first doped conductive layer are disposed only on the portion of the front surface of the substrate in the metal pattern region, dimension arrangement of the first pyramid structures and the second pyramid structures in the metal pattern region and dimension arrangement of the third pyramid structures and the fourth pyramid structures in the non-metal pattern region are designed to improve the mobility of the carriers while increasing the utilization of the incident light by the substrate, so that transmission efficiency of the carriers is improved while the absorption and utilization of the incident light by the front surface are improved.

Various embodiments of the present disclosure are described in detail below with reference to the accompanying drawings. Those of ordinary skill in the art should appreciate that many technical details have been proposed in various embodiments of the present disclosure for the better understanding of the present disclosure. However, the technical solutions claimed in the present disclosure are able to be realized even without these technical details and various changes and modifications based on the following embodiments.

<FIG> is a schematic cross-sectional view of a photovoltaic cell according to an embodiment of the present disclosure.

Referring to <FIG>, the photovoltaic cell includes a substrate <NUM> having a front surface with a plurality of metal pattern regions and a plurality of non-metal pattern regions, a plurality of first pyramid structures <NUM> and a plurality of second pyramid structures <NUM> disposed in each of the plurality of metal pattern regions, a plurality of third pyramid structures <NUM> and a plurality of fourth pyramid structures <NUM> disposed in each of the plurality of non-metal pattern region, a first tunneling layer <NUM> and a first doped conductive layer <NUM> stacked on a portion of the front surface of the substrate <NUM> in a respective metal pattern region, and a second tunneling layer <NUM> and a second doped conductive layer <NUM> stacked on a rear surface of the substrate <NUM> in a direction away from the substrate <NUM>. A dimension of a bottom portion of each of the plurality of first pyramid structures <NUM> is greater than a dimension of a bottom portion of each of the plurality of second pyramid structures <NUM>. A dimension of a bottom portion of each of the plurality of third pyramid structures <NUM> is greater than a dimension of a bottom portion of each of the plurality of fourth pyramid structures <NUM>. An area proportion of the plurality of first pyramid structures <NUM> on the portion of the front surface of the substrate in the respective metal pattern region (i.e., a proportion of an area occupied by the plurality of first pyramid structures <NUM> in the respective metal pattern region) is greater than an area proportion of the plurality of third pyramid structures <NUM> on the portion of the front surface of the substrate in the respective non-metal pattern region (i.e., a proportion of an area occupied by the plurality of third pyramid structures <NUM> in the respective non-metal pattern region).

In the embodiments of the present disclosure, dimension arrangement of the plurality of first pyramid structures <NUM> and the plurality of second pyramid structures <NUM> in the metal pattern region and dimension arrangement of the plurality of third pyramid structures <NUM> and the plurality of fourth pyramid structures <NUM> in the non-metal pattern region are designed based on the structure in which the first tunneling layer <NUM> and the first doped conductive layer <NUM> are disposed only on the portion of the front surface of the substrate <NUM> in the metal pattern region. An area proportion of the plurality of first pyramid structures <NUM> with larger dimensions in the metal pattern region is arranged to be large, so that uniformity of dimensions of the pyramid structures in the metal pattern region is higher and the roughness of the pyramid structures in the metal pattern region is larger. In this way, in actual operations of depositing the first tunneling layer <NUM> and the first doped conductive layer <NUM>, deposition probabilities at different positions of the metal pattern region are close to each other, and uniformity of thicknesses of the deposited first tunneling layer <NUM> and the deposited first doped conductive layer <NUM> is improved, so that a contact interface between the first tunneling layer <NUM> and the substrate <NUM> is relatively flat, i.e., a probability of occurrence of voids at the contact interface between the first tunneling layer <NUM> and the substrate <NUM> is small, thereby reducing defects at an interface between the first tunneling layer <NUM> and the substrate <NUM>, and improving mobility of carriers in the substrate <NUM> to the first doped conductive layer <NUM>. In addition, since the portion of the front surface of the substrate <NUM> in the metal pattern region has large roughness, a contact area between the first tunneling layer <NUM> and the front surface of the substrate <NUM> is increased, thereby providing a larger tunneling channel for the carriers and further improving the mobility of the carriers.

The area proportion of the plurality of third pyramid structures <NUM> with the larger dimensions in the non-metal pattern region is arranged to be relatively small, so that the number of the third pyramid structures <NUM> and the fourth pyramid structures <NUM> per unit area is larger, thereby enhancing the diffuse reflection effect on the incident light, and reducing the reflectivity on the incident light. In addition, the first doped conductive layer <NUM> is not provided on the portion of the front surface of the substrate <NUM> in the non-metal pattern region, which avoids parasitic absorption of the incident light by the first doped conductive layer <NUM>, thereby greatly increasing absorption of the incident light in the non-metal pattern region. In this way, the utilization of the incident light by the substrate <NUM> is increased while the mobility of the carriers is improved.

The substrate <NUM> is configured to receive the incident light and generate photogenerated carriers. In some embodiments, the substrate <NUM> may be a silicon substrate, and a material of the silicon substrate may include at least one of monocrystalline silicon, polysilicon, amorphous silicon, and microcrystalline silicon. In some embodiments, the material of the substrate <NUM> may also be silicon carbide, an organic material, or multicomponent compounds. The multicomponent compounds include, but are not limited to, materials such as perovskite, gallium arsenide, cadmium telluride, copper indium selenium, and the like.

In some embodiments, the substrate <NUM> has doping elements, and a type of the doping elements includes N-type or P-type. The N-type elements may be group V elements such as phosphorus (P), bismuth (Bi), antimony (Sb), arsenic (As), or the like. The P-type elements may be group III elements such as boron (B), aluminum (Al), gallium (Ga), indium (In), or the like. For example, when the substrate <NUM> is a P-type substrate, the type of the doping elements in the substrate <NUM> is P-type. In some embodiments, when the substrate <NUM> is an N-type substrate, the type of the doping elements in the substrate <NUM> is N-type.

Both the front and rear surfaces of the substrate <NUM> may be configured to receive incident or reflected light. The first tunnel layer <NUM> and the first doped conductive layer <NUM> on the front surface of the substrate <NUM> are configured to constitute a passivation contact structure on the front surface of the substrate <NUM>, and the second tunnel layer <NUM> and the second doped conductive layer <NUM> on the rear surface of the substrate <NUM> are configured to constitute a passivation contact structure on the rear surface of the substrate <NUM>. The passivation contact structures are respectively provided on the front surface and the rear surface of the substrate <NUM> so that the photovoltaic cell is formed as a double-sided tunnel oxide passivated contact (TOPCON) cell. In this way, the passivation contact structures formed on the front surface and the rear surface of the substrate <NUM> are capable of reducing carrier recombination on both the front surface and the rear surface of the substrate <NUM>, which greatly reduces loss of the carriers of the photovoltaic cell as compared with forming the passivation contact structure on only one surface of the substrate <NUM>, thereby increasing an open-circuit voltage and a short-circuit current of the photovoltaic cell. In the embodiments of the present disclosure, the first tunneling layer <NUM> and the first doped conductive layer <NUM> are disposed only on the portion of the front surface of the substrate <NUM> in the metal pattern region, so that the parasitic absorption of the incident light by the first doped conductive layer <NUM> is reduced, and the absorption and utilization of the incident light in the non-metal pattern region are improved.

By forming the passivation contact structures, the recombination of the carriers on the surface of the substrate <NUM> is reduced, so that the open-circuit voltage of the photovoltaic cell is increased, and thus improving the photoelectric conversion efficiency of the photovoltaic cell.

The first tunneling layer <NUM> and the second tunneling layer <NUM> are configured to achieve interface passivation of the surface of the substrate <NUM>, which realizes a chemical passivation effect. Specifically, state density of the interface defects of the surface of the substrate <NUM> is reduced by saturating suspension bonds of the surface of the substrate <NUM>, thereby reducing recombination centers of the surface of the substrate <NUM>. The presence of the first tunneling layer <NUM> and the second tunneling layer <NUM> allows the majority of carriers to be tunneled through the surface of the substrate <NUM> into the substrate <NUM>, thereby enabling selective transmission of the carrier. Specifically, the majority of carriers to be tunneled through a contact interface between the first tunneling layer <NUM> and the substrate <NUM> and a contact interface between the second tunneling layer <NUM> and the substrate <NUM> into the substrate <NUM>.

In the embodiments of the present disclosure, the area proportion of the plurality of first pyramid structures <NUM> with the larger dimensions in the metal pattern region is arranged to be greater than the area proportion of the plurality of third pyramid structures <NUM> with the larger dimensions in the non-metal pattern region, so that uniformity of dimensions of pyramid structures on the portion of the front surface of the substrate <NUM> in the metal pattern region is higher and roughness of the pyramid structures on the portion of the front surface of the substrate <NUM> in the metal pattern region is greater. In this way, on the one hand, the uniformity of the actually deposited first tunneling layer <NUM> is improved, thereby improving the flatness of the contact interface between the first tunneling layer <NUM> and the substrate <NUM>. On the other hand, the contact area between the first tunneling layer <NUM> and the front surface of the substrate <NUM> is larger such that more carriers are able to be tunneled into the substrate <NUM> through the contact interface between the first tunneling layer <NUM> and the substrate <NUM>. In this way, the mobility of the carriers is improved while the low reflectivity of the incident light by the portion of the front surface of the substrate <NUM> in the non-metal pattern region is maintained, so that the open-circuit voltage and the short-circuit current of the photovoltaic cell are greatly improved, thus improving the photoelectric conversion performance of the photovoltaic cell.

In some embodiments, the plurality of first pyramid structures <NUM> may be tetrahedron, approximately tetrahedron, pentahedron, approximately pentahedron, or the like. In some embodiments, the plurality of second pyramid structures <NUM> may be tetrahedron, approximately tetrahedron, pentahedron, approximately pentahedron, or the like.

In some embodiments, an area proportion of the plurality of first pyramid structures <NUM> on the portion of the front surface of the substrate <NUM> in the respective metal pattern region is greater than an area proportion of the plurality of second pyramid structures <NUM> on the portion of the front surface of the substrate <NUM> in the respective metal pattern region (i.e., a proportion of an area occupied by the plurality of second pyramid structures <NUM> in the respective metal pattern region). That is, in the embodiments of the present disclosure, dimension arrangement of the plurality of first pyramid structures <NUM> and the plurality of second pyramid structures <NUM> in the portion of the front surface of the substrate <NUM> in the metal pattern region is designed so that the plurality of first pyramid structures <NUM> with the larger dimensions are predominant on the portion of the front surface of the substrate <NUM> in the metal pattern region. Since the dimensions of the plurality of first pyramid structures <NUM> are larger, the number of the first pyramid structures <NUM> required for the same area is less than that of the second pyramid structures <NUM> in the case of setting the area proportion of the plurality of second pyramid structures <NUM> with the smaller dimensions to be greater, thereby making it easier to achieve uniformity of the dimensions. Moreover, since the number of the first pyramid structures <NUM> is small, the damage of the texture structures (i.e., pyramid structures) to the front surface of the substrate <NUM> is reduced, thereby reducing the interface state defects on the front surface of the substrate <NUM> and reducing the generation of the carrier recombination center. That is, not only the uniformity of the dimensions of the texture structures on the portion of the front surface of the substrate <NUM> in the metal pattern region is larger than that of the texture structures on the portion of the front surface of the substrate <NUM> in the non-metal pattern region, but also the uniformity of the dimensions of the texture structures in the metal pattern region is further increased, so that the flatness of the contact interface between the first tunneling layer <NUM> and the substrate <NUM> is improved, and the contact area between the first tunneling layer <NUM> and the front surface of the substrate <NUM> is increased, thereby reducing the interface state defects of the substrate <NUM>, and improving the mobility of carriers.

In some embodiments, the area proportion of the plurality of first pyramid structures <NUM> on the portion of the front surface of the substrate <NUM> in the respective metal pattern region is in a range of <NUM>% to <NUM>%, such as <NUM>%~<NUM>%, <NUM>%~<NUM>%, <NUM>%~<NUM>%, <NUM>%~<NUM>%, <NUM>%~<NUM>%, <NUM>%~<NUM>%, or the like. The area proportion of the plurality of second pyramid structures <NUM> on the portion of the front surface of the substrate <NUM> in the respective metal pattern region is in a range of <NUM>% to <NUM>%, such as <NUM>%~<NUM>%, <NUM>%~<NUM>%, <NUM>%~<NUM>%, <NUM>%~<NUM>%, <NUM>%~<NUM>%, <NUM>%~<NUM>%, or the like. That is, the area proportion of the plurality of first pyramid structures <NUM> on the portion of the front surface of the substrate <NUM> in the metal pattern region is close to <NUM>, so that high uniformity of the dimensions of the texture structures on the portion of the front surface of the substrate <NUM> in the metal pattern region is realized, and high uniformity of the thicknesses of the first tunneling layer <NUM> and the first doped conductive layer <NUM> is realized in the actual operations of depositing the first tunneling layer <NUM> and the first doped conductive layer <NUM>, so that interface defects at the interface between the first tunneling layer <NUM> and the substrate <NUM> are reduced, and the generation of the carrier recombination center at the interface is reduced. In addition, within this range, the roughness of the portion of the front surface of the substrate <NUM> in the metal pattern region is greatly improved, and further, the contact area between the first tunneling layer <NUM> and the front surface of the substrate <NUM> is greatly increased, so that the mobility of carriers is improved while the utilization of the incident light in the non-metal pattern region is improved, thereby improving the photoelectric conversion performance of the photovoltaic cell.

Referring to <FIG>, it should be noted that the number of the first pyramid structures <NUM> and the number of the second pyramid structures <NUM> on the portion of the front surface of the substrate <NUM> in the metal pattern region are plural. There may be slight dimensional differences between different first pyramid structures <NUM> and between different second pyramid structures <NUM>, but an overall dimension of each first pyramid structure <NUM> is approximately close, and an overall dimension of each second pyramid structure <NUM> is approximately close. In the embodiment of the present disclosure, the dimensions of the plurality of first pyramid structures <NUM>, the plurality of second pyramid structures <NUM>, the plurality of third pyramid structures <NUM>, and the plurality of fourth pyramid structures <NUM> are average dimensions within a sampling region. Specifically, in some embodiments, a one-dimensional dimension of a bottom portion of the first pyramid structure <NUM> may be in a range of <NUM> to <NUM>, such as <NUM>~<NUM>, <NUM>~<NUM>, <NUM>~<NUM>, <NUM>~<NUM>, <NUM>~<NUM>, <NUM>~<NUM>, <NUM>, <NUM>, <NUM>~<NUM>, <NUM>~<NUM>, <NUM>~<NUM>, or <NUM>~<NUM>. A one-dimensional dimension of a bottom portion of the second pyramid structure <NUM> may be less than <NUM>, such as <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or the like. Within this range, not only the roughness of the portion of the front surface of the substrate <NUM> in the metal pattern region is increased, but also the number of the first pyramid structures <NUM> is reduced while keeping the area proportion of the plurality of first pyramid structures <NUM> unchanged, thereby reducing dimensional unevenness caused by the slight dimensional differences between the different first pyramid structures <NUM>. In addition, the dimensions of the second pyramid structures <NUM> are small, so that the roughness of the portion of the front surface of the substrate <NUM> in the metal pattern region where the second pyramid structures <NUM> are disposed is small, so that roughness of a surface of the first doped conductive layer <NUM> deposited on this portion of the front surface of the substrate <NUM> is small, thereby making the surface of the first doped conductive layer <NUM> deposited on this portion have a strong reflection effect on the incident light, which is conducive to reducing the parasitic absorption of the incident light by the first doped conductive layer <NUM>. That is, dimension arrangement of the first pyramid structure <NUM> with the larger dimensions and the second pyramid structures <NUM> with the smaller dimensions on the portion of the front surface of the substrate <NUM> in the metal pattern region is designed, so that the parasitic absorption of the incident light by the first doped conductive layer <NUM> is reduced while improving the mobility of carriers.

It should be understood that the fact that the one-dimensional dimension of the bottom portion of the first pyramid structure <NUM> is larger than the one-dimensional dimension of the bottom portion of the second pyramid structure <NUM> herein means that the one-dimensional dimension of the bottom portion of the first pyramid structure <NUM> is larger than the one-dimensional dimension of the bottom portion of the second pyramid structure <NUM> in the same direction, and the fact that the one-dimensional dimension of the bottom portion of the third pyramid structure <NUM> is larger than the one-dimensional dimension of the bottom portion of the fourth pyramid structure <NUM> means that the one-dimensional dimension of the bottom portion of the third pyramid structure <NUM> is larger than the one-dimensional dimension of the bottom portion of the fourth pyramid structure <NUM> in the same direction.

In some embodiments, a height from top to bottom of each first pyramid structure <NUM> is not less than a height from top to bottom of each second pyramid structure <NUM>. Specifically, in some embodiments, the height from top to bottom of each first pyramid structure <NUM> is greater than the height from top to bottom of each second pyramid structure <NUM>, so that a concave-convex degree of the front surface of the substrate <NUM> where the first pyramid structures <NUM> are disposed is greater than a concave-convex degree of the front surface of the substrate <NUM> where the second pyramid structures <NUM> are disposed, so that a specific surface area of the front surface of the substrate <NUM> where the first pyramid structures <NUM> are disposed is large, thereby further increasing the contact area between the first tunneling layer <NUM> and the front surface of the substrate <NUM>, and improving the mobility of carriers. Meanwhile, the front surface of the substrate <NUM> where the second pyramid structures <NUM> are disposed is designed to have a small concave-convex degree, so that the surface of the first doped conductive layer <NUM> facing the second pyramid structures <NUM> has a higher reflectivity to the incident light, thereby reducing the parasitic absorption of the incident light by the first doped conductive layer <NUM>.

Specifically, in some embodiments, the height from top to bottom of the first pyramid structure <NUM> may be <NUM>~<NUM>, <NUM>~<NUM>, <NUM>~<NUM>, <NUM>~<NUM>, <NUM>~<NUM>, <NUM>~<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>~<NUM>, <NUM>~<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>~<NUM>, or the like. The height from top to bottom of the second pyramid structure <NUM> may not be greater than <NUM>, such as <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or the like.

The first doped conductive layer <NUM> and the second doped conductive layer <NUM> are configured for field passivation, which makes minority carriers escape from the interface and reduces a concentration of the minority carriers, so that a carrier recombination rate at the interface of the substrate <NUM> is low, and the open-circuit voltage, the short-circuit current and the filling factor of the photovoltaic cell are large, thereby improving the photoelectric conversion performance of the photovoltaic cell.

It should be understood that, during actual formation of the first tunneling layer <NUM> and the first doped conductive layer <NUM>, the smaller the thicknesses of the first tunneling layer <NUM> and the first doped conductive layer <NUM>, the more similar the topographies of a top surface of the first tunneling layer <NUM> and a top surface of the first doped conductive layer <NUM> are to the topographies of the first pyramid structures <NUM> and the second pyramid structures <NUM> on the front surface of the substrate <NUM>. Conversely, as the thicknesses of the first tunneling layer <NUM> and the first doped conductive layer <NUM> increase, the difference between the topographies of the top surface of the first tunneling layer <NUM> and the first doped conductive layer <NUM> and the topographies of the first pyramid structures <NUM> and the second pyramid structures <NUM> on the front surface of the substrate <NUM> increases, and the roughness of the top surface of the first tunneling layer <NUM> and the top surface of the first doped conductive layer <NUM> decreases. Based on this, in some embodiments, the thickness of the first tunneling layer <NUM> may be in a range of <NUM> to <NUM>, such as <NUM>~<NUM>, <NUM>~<NUM>, <NUM>~<NUM>, <NUM>~<NUM>, <NUM>~<NUM>, <NUM>~<NUM>, <NUM>~<NUM>, <NUM>~<NUM>, <NUM>~<NUM>, or the like. The thickness of the first doped conductive layer <NUM> may be in a range of <NUM> to <NUM>, such as <NUM>~<NUM>, <NUM>~<NUM>, <NUM>~<NUM>, <NUM>~<NUM>, <NUM>~<NUM>, <NUM>~<NUM>, or the like. Within this range, the thicknesses of the first tunneling layer <NUM> and the first doped conductive layer <NUM> are large, so that the roughness of the top surface of the first doped conductive layer <NUM> is small, and thus the degree of reflection of the first doped conductive layer <NUM> on the incident light is large. In this way, on the one hand, the parasitic absorption of the incident light by the first doped conductive layer <NUM> is reduced, and on the other hand, the incident light reflected by the top surface of the first doped conductive layer <NUM> is able to be diffracted to the portion of the front surface of the substrate <NUM> in the non-metal pattern region via the surrounding environment, and then absorbed and utilized again, thereby improving secondary utilization of the incident light. Moreover, within this range, the thicknesses of the first tunneling layer <NUM> and the first doped conductive layer <NUM> are not excessively large, so that a problem of mechanical damage to the front surface of the substrate <NUM> caused by excessive stress due to the excessive thicknesses of the first tunneling layer <NUM> and the first doped conductive layer <NUM> is prevented, thereby reducing the interface state defects of the front surface of the substrate <NUM>.

In addition, providing the thickness of the first tunneling layer <NUM> within this range makes the thickness of the first tunneling layer <NUM> match with the dimensions of the first pyramid structures <NUM> and the second pyramid structures <NUM>, so that the contact interface between the first tunneling layer <NUM> and the front surface of the substrate <NUM> is relatively flat when the first tunneling layer <NUM> reaches this thickness range in the actual operation of depositing the first tunneling layer <NUM>, thereby reducing the interface defects of the substrate <NUM>, and improving the mobility of carriers.

It should be understood that, in an actual operation of doping the first doped conductive layer <NUM>, the doping elements are diffused into the first doped conductive layer <NUM> through a diffusion process. The larger the thickness of the first doped conductive layer <NUM>, the longer the diffusion path of the doping elements, and the smaller the thickness of the first doped conductive layer <NUM>, the shorter the diffusion path of the doping elements. When the diffusion path of the doping elements is excessively short, the doping elements may be accumulated at the interface of the substrate <NUM>, and the doping elements accumulated at the interface of the substrate <NUM> may not be easily activated during an annealing process, so that a 'dead layer' is generated. The presence of the 'dead layer' affects the number and rate of carriers transmitting from the substrate <NUM> to the first doped conductive layer <NUM>, thereby affecting the photoelectric conversion performance of the photovoltaic cell.

From the above, it is seen that an activation rate of the first doping elements in the first doped conductive layer <NUM> is related to the thickness of the first doped conductive layer <NUM>. Based on this, in some embodiments, when the thickness of the first doped conductive layer <NUM> is in a range of <NUM> to <NUM>, the first doped conductive layer <NUM> is provided to include the first doping elements, the first doping elements have been annealed and activated to obtain activated first doping elements, and the activation rate of the first doping elements in the first doped conductive layer <NUM> is in a range of <NUM>% to <NUM>%, such as <NUM>%~<NUM>%, <NUM>%~<NUM>%, <NUM>%~<NUM>%, <NUM>%~<NUM>%, <NUM>%~<NUM>%, or the like. Within this range, the activation rate of the first doping elements is matched with the thickness of the first doped conductive layer <NUM> to prevent excessive first doping elements from accumulating at the interface of the substrate <NUM> and forming the 'dead layer'.

In some embodiments, a concentration of the activated first doping elements is in a range of <NUM>×<NUM><NUM>atom/cm<NUM> to <NUM>×<NUM><NUM>atom/cm<NUM>, such as <NUM>×<NUM><NUM>atom/cm<NUM>~<NUM>×<NUM><NUM>atom/cm<NUM>, <NUM>×<NUM><NUM>atom/cm<NUM>~<NUM>×<NUM><NUM>atom/cm<NUM>, <NUM>×<NUM><NUM>atom/cm<NUM>~<NUM>×<NUM><NUM>atom/cm<NUM>, <NUM>×<NUM><NUM>atom/cm<NUM>~<NUM>× <NUM><NUM>atom/cm<NUM>, <NUM>×<NUM><NUM>atom/cm<NUM>~<NUM>×<NUM><NUM>atom/cm<NUM>, or the like. Within this range, on the one hand, the concentration of the first doping elements is not excessively large, so that the concentration of the first doping elements totally implanted into the first doped conductive layer <NUM> in actual operations is not excessively large, and thus the first doping elements are prevented from excessively accumulating at the interface of the substrate <NUM>. On the other hand, within this range, the concentration of the first doping elements is also not excessively small, which helps to maintain a low square resistance of the first doping conductive layer <NUM>, improve ohmic contact between the first doping conductive layer <NUM> and a metal electrode, and reduce recombination loss of the metal contact, thereby improving the ability of the metal electrode to collect the carriers.

The area proportion of the third pyramid structures <NUM> with the larger dimensions in the non-metal pattern region is smaller as compared with the area proportion of the first pyramid structures <NUM> with the larger dimensions in the metal pattern region, so that the number of the third pyramid structures <NUM> and the fourth pyramid structures <NUM> per unit area is larger. When the incident light is irradiated between adjacent third pyramid structures <NUM>, between adjacent third pyramid structure <NUM> and fourth pyramid structure <NUM>, or between adjacent fourth pyramid structures <NUM>, the incident light is repeatedly reflected by side surfaces of the third pyramid structures <NUM> or side surfaces of the fourth pyramid structures <NUM>, and finally irradiated into the substrate <NUM>, i.e., the diffuse reflection effect on the incident light is enhanced, thereby reducing the reflectivity of the incident light. Moreover, the first doped conductive layer <NUM> is not provided on the portion of the surface of the substrate <NUM> in the non-metal pattern region, so that absorption of the incident light in the non-metal pattern region is greatly increased. In this way, the utilization of the incident light by the substrate <NUM> is improved while increasing the mobility of carriers.

In some embodiments, the third pyramid structures <NUM> may be tetrahedron, approximately tetrahedron, pentahedron, or approximately pentahedron. In some embodiments, the fourth pyramid structures <NUM> may be tetrahedron, approximately tetrahedron, pentahedron, or approximately pentahedron.

In some embodiments, the area proportion of the third pyramid structures <NUM> on the portion of the front surface of the substrate <NUM> in the respective non-metal pattern region is greater than the area proportion of the fourth pyramid structures <NUM> on the portion of the front surface of the substrate <NUM> in the respective non-metal pattern region. That is, dimension arrangement of the third pyramid structures <NUM> and the fourth pyramid structures <NUM> on the portion of the front surface of the substrate <NUM> in the non-metal pattern region is designed in the embodiments of the present disclosure, so that the third pyramid structures <NUM> with the larger dimensions are predominant on the portion of the front surface of the substrate <NUM> in the non-metal pattern region. In this way, compared with that the fourth pyramid structures <NUM> with the smaller dimensions are predominant on the portion of the front surface of the substrate <NUM> in the non-metal pattern region, the number of the third pyramid structures <NUM> and the fourth pyramid structures <NUM> per unit area on the portion of the front surface of the substrate <NUM> in the non-metal pattern region is smaller, so that damage to the front surface of the substrate <NUM> caused by the third pyramid structure <NUM> and the fourth pyramid structure <NUM> is reduced, thereby reducing the interface state defects of the portion of the front surface of the substrate <NUM> in the non-metal pattern region. It is seen that since the first tunneling layer <NUM> and the first doped conductive layer <NUM> are not provided in the non-metal pattern region, the passivation effect on the portion of the front surface of the substrate <NUM> in the non-metal pattern region is weak. Therefore, the interface state defects of the portion of the front surface of the substrate <NUM> in the non-metal pattern region is reduced, thereby reducing the carrier recombination of the portion of the front surface of the substrate <NUM> in the non-metal pattern region, which plays an important role in ensuring the passivation performance of the portion of the front surface of the substrate <NUM> in the non-metal pattern region. Therefore, it is ensured that the carrier recombination of the portion of the front surface of the substrate <NUM> in the non-metal pattern region is not serious while reducing the reflection of the incident light, thereby facilitating the overall photoelectric conversion performance of the photovoltaic cell.

In some embodiments, the area proportion of the third pyramid structures <NUM> on the portion of the front surface of the substrate <NUM> in the respective non-metal pattern region is in a range of <NUM>% to <NUM>%, such as <NUM>%~<NUM>%, <NUM> %~<NUM>%, <NUM>%~<NUM>%, <NUM>%~<NUM>%, or the like. The area proportion of the fourth pyramid structures on the portion of the front surface of the substrate <NUM> in the respective non-metal pattern region is in a range of <NUM>% to <NUM>%, such as <NUM>%~<NUM>%, <NUM>%~<NUM>%, <NUM>%~<NUM>%, <NUM>%~<NUM>%, or the like. Within this range, the area proportion of the third pyramid structures <NUM> is larger than that of the fourth pyramid structures <NUM>, so that the number of the third pyramid structures <NUM> and the fourth pyramid structures <NUM> per unit area is prevented from causing large damage to the portion of the front surface of the substrate <NUM> in the non-metal pattern region and causing excessive defects of the portion of the front surface of the substrate <NUM> in the non-metal pattern region, and less carrier recombination on the portion of the front surface of the substrate <NUM> in the non-metal pattern region is maintained. In addition, within this range, the area proportion of the third pyramid structures <NUM> is not excessively large as compared with that of the fourth pyramid structures <NUM>, so that the number of the third pyramid structures <NUM> and the fourth pyramid structures <NUM> per unit area on the portion of the front surface of the substrate <NUM> in the non-metal pattern region is larger, which is conducive to enhancing the diffuse reflection effect on the incident light, thereby reducing the reflectivity of the incident light in the non-metal region.

Referring to <FIG>, it should be noted that the number of the third pyramid structures <NUM> and the number of the fourth pyramid structures <NUM> on the portion of the front surface of the substrate <NUM> in the non-metal pattern region are plural. There may be slight dimensional differences between different third pyramid structures <NUM> and between different fourth pyramid structures <NUM>, but an overall dimension of each third pyramid structure <NUM> is approximately close, and an overall dimension of each fourth pyramid structure <NUM> is approximately close. Specifically, in some embodiments, a one-dimensional dimension of a bottom portion of the third pyramid structure <NUM> is in a range of <NUM> to <NUM>, such as <NUM>-<NUM>, <NUM>~<NUM>, <NUM>~<NUM>, <NUM>~<NUM>, <NUM>~<NUM>, <NUM>~<NUM>, <NUM>-<NUM>, <NUM>~<NUM>, <NUM>~<NUM>, <NUM>~<NUM>, <NUM>-<NUM>, <NUM>~<NUM>, or the like. A one-dimensional dimension of a bottom portion of the fourth pyramid structure <NUM> is less than <NUM>, such as <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or the like.

It is seen that the dimensions of the first pyramid structures <NUM> are similar to the dimensions of the third pyramid structures <NUM>, and the dimensions of the second pyramid structures <NUM> are similar to the dimensions of the fourth pyramid structures <NUM>. That is, in the embodiments of the present disclosure, dimension arrangement of the first pyramid structures <NUM> and the second pyramid structures <NUM> in the metal pattern region as well as the third pyramid structures <NUM> and the fourth pyramid structures <NUM> in the non-metal pattern region is designed, so that the area proportion of the dimensions of the first pyramid structures <NUM> with the larger dimensions in the metal pattern region is relatively large, and the area proportion of the third pyramid structures <NUM> with the larger dimensions in the non-metal pattern region is relatively small, thereby improving the mobility of carriers in the double-sided TOPCON cell while improving the utilization of the incident light.

A specific dimension relationship between the first pyramid structures <NUM> and the third pyramid structures <NUM> and a specific dimension relationship between the second pyramid structures <NUM> and the fourth pyramid structures <NUM> are not limited in the embodiments of the present disclosure. The one-dimensional dimension of the bottom portion of the first pyramid structure <NUM> and the one-dimensional dimension of the bottom portion of the third pyramid structure <NUM> are within the range of <NUM> to <NUM>, and the one-dimensional dimension of the bottom portion of the second pyramid structure <NUM> and the one-dimensional dimension of the bottom portion of the fourth pyramid structure <NUM> are less than <NUM>, so that the damage of the first pyramid structures <NUM>, the second pyramid structures <NUM>, the third pyramid structures <NUM>, and the fourth pyramid structures <NUM> to the front surface of the substrate <NUM> is reduced, and the defect state density of the entire front surface of the substrate <NUM> is reduced, which is conducive to keeping a low carrier recombination rate at the interface of the substrate <NUM>.

In some embodiments, the height from top to bottom of the third pyramid structure <NUM> may be in a range of <NUM> to <NUM>, such as <NUM>~<NUM>, <NUM>~<NUM>, <NUM>~<NUM>, <NUM>~<NUM>, <NUM>~<NUM>, <NUM>-<NUM>, <NUM>~<NUM>, <NUM>~<NUM>, <NUM>~<NUM>, <NUM>~<NUM>, <NUM>~<NUM>, <NUM>~<NUM>, or the like. The height from top to bottom of the fourth pyramid structure <NUM> may not be greater than <NUM>, such as <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or the like.

In some embodiments, the reflectivity of the portion of the front surface of the substrate <NUM> in the respective non-metal pattern region is in a range of <NUM>% to <NUM>%, such as <NUM>%~<NUM>%, <NUM> %~<NUM>%, <NUM>%~<NUM>%, <NUM>%~<NUM>%, <NUM>%~<NUM>%, <NUM>%~<NUM>%, <NUM>%~<NUM>%, or the like. Within this range, the reflectivity of the portion of the front surface of the substrate <NUM> in the non-metal pattern region is low, which is conducive to enhancing the utilization of the incident light by the portion of the front surface of the substrate <NUM> in the non-metal pattern region, thereby increasing the number of carriers, the short-circuit current and the open-circuit voltage, and improving the photoelectric conversion performance of the photovoltaic cell.

In some embodiments, the photovoltaic cell further includes a first passivation layer <NUM>, a first portion of the first passivation layer <NUM> is disposed on a surface of the first doped conductive layer <NUM> away from the substrate <NUM>, and a second portion of the first passivation layer <NUM> is disposed on the portion of the front surface of the substrate <NUM> in the respective non-metal pattern region. The first passivation layer <NUM> has a good passivation effect on the front surface of the substrate <NUM>. For example, the first passivation layer <NUM> may chemically passivate the suspension bonds on the front surface of the substrate <NUM>, reduce the defect state density of the front surface of the substrate <NUM>, and suppress the carrier recombination on the front surface of the substrate <NUM>. The first portion of the first passivation layer <NUM> is directly in contact with the front surface of the substrate <NUM> such that there is no first tunneling layer <NUM> and first doped conductive layer <NUM> between the first portion of the first passivation layer <NUM> and the substrate <NUM>, thereby reducing the parasitic absorption of the incident light by the first doped conductive layer <NUM>.

In some embodiments, the first portion of the first passivation layer <NUM> is not flush with the second portion of the first passivation layer <NUM>. Specifically, a top surface of the first portion of the first passivation layer <NUM> may be lower than a top surface of the second portion of the first passivation layer <NUM>, so that a thickness of the first portion disposed on the front surface of the substrate <NUM> is not excessively thick, thereby preventing the front surface of the substrate <NUM> from generating more carrier recombination centers due to too many interface state defects on the front surface of the substrate <NUM> which are generated from the stress damage caused by the large thickness of the first portion to the front surface of the substrate <NUM>. In addition, the area proportion of the third pyramid structures <NUM> with the larger dimensions on the portion of the front surface of the substrate <NUM> in the non-metal pattern region is smaller than that of the first pyramid structures <NUM> with the larger dimensions on the portion of the front surface of the substrate <NUM> in the metal pattern region the metal pattern region, so that the concave-convex degree of the portion of the front surface of the substrate <NUM> in the non-metal pattern region is not excessively large. Thus, in the actual operation of depositing the first passivation layer <NUM>, the concave-convex degree of the surface of the first passivation layer <NUM> is not excessively large, which improves the flatness of the first passivation layer <NUM>, thereby improving the passivation performance of the first passivation layer <NUM>.

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

In some embodiments, a plurality of platform protrusion structures <NUM> are provided on the rear surface of the substrate <NUM>. A one-dimensional dimension of a bottom portion of each platform protrusion structure <NUM> is greater than the one-dimensional dimension of the bottom portion of the first pyramid structure <NUM> and greater than the one-dimensional dimension of the bottom portion of the third pyramid structure <NUM>, and a height from top to bottom of the platform protrusion structure <NUM> is smaller than the height of the first pyramid structure <NUM> and smaller than the height of the third pyramid structure <NUM>. Specifically, the platform protrusion structure <NUM> includes a base portion of a pyramid structure (i.e., a bottom portion of the pyramid structure that does not contain a spire).

That is, the concave-convex degree of the pyramid structures disposed on the front surface of the substrate <NUM> is greater than the concave-convex degree of the platform convex structures disposed on the rear surface of the substrate <NUM>, so that the roughness of the front surface of the substrate <NUM> is greater than the roughness of the rear surface of the substrate <NUM>. In this way, in some embodiments, since the front surface of the substrate <NUM> receives more incident light, the front surface of the substrate <NUM> is provided with pyramid structures having larger specific surface areas in order to enhance the absorption capability of the front surface of the substrate <NUM> to the incident light, which enhances the diffuse reflection effect on the front surface of the substrate <NUM> is enhanced, so that the utilization of the incident light by the front surface of the substrate <NUM> is greater. Since the rear surface of the substrate <NUM> receives less incident light, the rear surface of the substrate <NUM> is provided with the platform protrusion structures <NUM> so that the roughness of the rear surface of the substrate <NUM> is smaller than the roughness of the front surface of the substrate <NUM>. That is, the rear surface of the substrate <NUM> is relatively flat as compared with the front surface of the substrate <NUM>, so that the second tunneling layer <NUM>, the second doped conductive layer <NUM>, and the second passivation layer <NUM> formed on the rear surface of the substrate <NUM> have flat morphologies, and the second tunneling layer <NUM>, the second doped conductive layer <NUM>, and the second passivation layer <NUM> are able to be uniformly formed on the rear surface of the substrate <NUM>, which is conducive to improving the passivation effect of the second tunneling layer <NUM>, the second doped conductive layer <NUM>, and the second passivation layer <NUM> on the rear surface of the substrate <NUM>, thus reducing the defect state density of the rear surface. In this way, the photoelectric conversion performance of the photovoltaic cell is improved as a whole by improving the utilization of the incident light and the passivation effect on the substrate <NUM>.

In some embodiments, the photovoltaic cell further includes a second passivation layer <NUM> for covering a surface of the second doped conductive layer <NUM> away from the substrate <NUM>. The second passivation layer <NUM> has a good passivation effect on the rear surface of the substrate <NUM>, which reduces the defect state density on the rear surface of the substrate <NUM>, and suppresses the carrier recombination on the rear surface of the substrate <NUM>. In some embodiments, the second passivation layer <NUM> may be a single-layer structure. In some embodiments, the second passivation layer <NUM> may also be a multi-layer structure. In some embodiments, the material of the second passivation layer <NUM> may be at least one of silicon oxide, aluminum oxide, silicon nitride, or silicon oxynitride.

In some embodiments, a doping element type of the first doped conductive layer <NUM> is the same as a doping element type of the substrate <NUM>, and a doping element type of the second doped conductive layer <NUM> is different from the doping element type of the first doped conductive layer <NUM>. That is, the second doped conductive layer <NUM> forms a PN junction with the substrate <NUM>, and the first doped conductive layer <NUM> on the front surface does not form a PN junction with the substrate <NUM>, so that the formation of the PN junction is avoided leading to serious carrier recombination in preset regions of the front surface. In addition, both the second tunneling layer <NUM> and the second doped conductive layer <NUM> are disposed on the entire rear surface of the substrate <NUM>, so that an area of the PN junction formed between the second doped conductive layer <NUM> and the substrate <NUM> is large, so that the number of the photogenerated carriers is large, and concentrations of the carriers in the second doped conductive layer <NUM> and in the substrate <NUM> are increased.

Specifically, in some embodiments, the substrate <NUM> is an N-type substrate. Based on this, the first doped conductive layer <NUM> may be provided as an N-type doped conductive layer, and the second doped conductive layer <NUM> may be provided as a P-type doped conductive layer. The P-type second doped conductive layer <NUM> forms a PN junction with the N-type substrate <NUM>, thereby forming the rear junction (i.e., the PN junction formed on the rear surface of the substrate <NUM>).

Since the rear junction is formed on the rear surface of the substrate <NUM>, the rear surface of the substrate <NUM> is provided with a flat morphology such that the second tunneling layer <NUM> is able to be formed more closely to the rear surface of the substrate <NUM>, so that the photogenerated carriers generated by the PN junction are smoothly transmitted into the substrate <NUM>, thereby further improving the transmission efficiency of the carriers.

In some embodiments, the substrate <NUM> may also be a P-type semiconductor substrate, the first doped conductive layer <NUM> is a P-type doped conductive layer, and the second doped conductive layer <NUM> is an N-type doped conductive layer.

In some embodiments, the material of the first doped conductive layer <NUM> includes at least one of silicon carbide, amorphous silicon, microcrystalline silicon, or polycrystalline silicon. In some embodiments, the second doped conductive layer <NUM> includes at least one of silicon carbide, amorphous silicon, microcrystalline silicon, or polycrystalline silicon.

In some embodiments, the photovoltaic cell further includes a first electrode <NUM> disposed in the respective metal pattern region and electrically connected to the first doped conductive layer <NUM>. The PN junction formed on the rear surface of the substrate <NUM> is used to receive the incident light and generate photogenerated carriers, and the generated photogenerated carriers are transmitted from the substrate <NUM> to the first doped conductive layer <NUM> and then to the first electrode <NUM> for collecting the photogenerated carriers. Since the doping element type of the first doped conductive layer <NUM> is the same as the doping element type of the substrate <NUM>, recombination loss of the metal contact between the first electrode <NUM> and the first doped conductive layer <NUM> is reduced, so that the carrier contact recombination between the first electrode <NUM> and the first doped conductive layer <NUM> is reduced, and the short-circuit current and the photoelectric conversion performance of the photovoltaic cell are improved.

In some embodiments, the photovoltaic cell further includes a diffusion region <NUM> disposed inside a portion of the substrate <NUM> in the respective metal pattern region, a top portion of the diffusion region <NUM> is in contact with the first tunneling layer <NUM>, and a doping element concentration of the diffusion region <NUM> is greater than a doping element concentration of the substrate <NUM>. The diffusion region <NUM> may serve as a channel for carrier transmission, and the diffusion region <NUM> is formed only in the portion of the substrate <NUM> in the metal pattern region, so that carriers in the substrate <NUM> are easily transmitted into the doped conductive layer through the diffusion region <NUM>, i.e., the diffusion region <NUM> functions as a channel for carrier transmission. In addition, since the diffusion region <NUM> is provided only in the portion of the substrate <NUM> in the metal pattern region, the carriers in the substrate <NUM> are able to be concentratedly transmitted to the diffusion region <NUM> and then to the first doped conductive layer <NUM> via the diffusion region <NUM>, so that the carrier concentration of the first doped conductive layer <NUM> is greatly increased. It should be noted that in the embodiments of the present disclosure, the diffusion region <NUM> is not provided in the portion of the substrate <NUM> in the non-metal pattern region, so that the carrier concentration of the portion of the front surface of the substrate <NUM> in the non-metal pattern region is not excessively large, and serious carrier recombination on the portion of the front surface of the substrate <NUM> in the non-metal pattern region is avoided. Moreover, the carriers in the substrate <NUM> is also prevented from being transmitted to the portion of the front surface of the substrate <NUM> in the non-metal pattern region, thereby avoiding excessive carrier recombination due to the `dead layer' generated on the portion of the front surface of the substrate <NUM> in the non-metal pattern region caused by accumulation of the carriers on the portion of the front surface of the substrate <NUM> in the non-metal pattern region, thereby improving the overall photoelectric conversion performance of the photovoltaic cell.

In some embodiments, the photovoltaic cell further includes a second electrode <NUM> disposed on the rear surface of the substrate <NUM>, the second electrode <NUM> penetrates through the second passivation layer <NUM> and electrically contacts the second doped conductive layer <NUM>.

In the photovoltaic cell provided in the above embodiments, the area proportion of the first pyramid structures <NUM> with larger dimensions in the metal pattern region are set to be greater, so that the uniformity of dimensions of pyramid structures in the metal pattern region is higher as compared with that of pyramid structures in the non-metal pattern region. In this way, in the actual operation of depositing the first tunnel layer <NUM> and the first doped conductive layer <NUM>, the uniformity of thicknesses of the deposited first tunnel layer <NUM> and first doped conductive layer <NUM> is improved, the interface defects at the interface between the first tunnel layer <NUM> and the front surface of the substrate <NUM> is reduced, and the mobility of carriers in the substrate <NUM> to the first doped conductive layer <NUM> is improved. In addition, the area proportion of the third pyramid structures <NUM> with the larger dimensions in the non-metal pattern region is relatively small, so that the number of the third pyramid structures <NUM> and the fourth pyramid structures <NUM> per unit area in the non-metal pattern region is larger, the reflectivity of the incident light is low. Moreover, the first doped conductive layer <NUM> is not provided on a portion of the front surface of the substrate <NUM> in the non-metal pattern region, so that absorption of the incident light in the non-metal pattern region is greatly increased.

Accordingly, some embodiments of the present disclosure further provide a photovoltaic module. As shown in <FIG>, the photovoltaic module includes at least one cell string each formed by a plurality of photovoltaic cells <NUM> provided in the above embodiments which are electrically connected, at least one encapsulation layer <NUM> each for covering a surface of a respective cell string, and at least one cover plate <NUM> each for covering a surface of a respective encapsulation layer <NUM> facing away from the respective cell string. The photovoltaic cells <NUM> are electrically connected in whole or in pieces to form a plurality of cell strings electrically connected in series and/or in parallel.

Specifically, in some embodiments, the plurality of cell strings may be electrically connected to each other by conductive tapes <NUM>. The encapsulation layer <NUM> covers the front surface and the rear surface of the photovoltaic cell <NUM>. Specifically, the encapsulation layer <NUM> may be an organic encapsulation adhesive film such as an ethylene-vinyl acetate copolymer (EVA) adhesive film, a polyethylene octene co-elastomer (POE) adhesive film, a polyethylene terephthalate (PET) adhesive film, or the like. In some embodiments, the cover plate <NUM> may be a glass cover plate, a plastic cover plate, or the like having a light transmitting function. Specifically, the surface of the cover plate <NUM> facing towards the encapsulation layer <NUM> may be a concavo-convex surface, thereby increasing utilization of the incident light. Although the present disclosure is disclosed in the above embodiments, the present disclosure is not intended to limit the claims. Any person skilled in the art may make several possible changes and modifications without departing from the concept of the present disclosure. Therefore, the protection scope of the present disclosure shall be subject to the scope defined in the claims of the present disclosure.

Claim 1:
A photovoltaic cell comprising:
a substrate (<NUM>), wherein the substrate has a front surface with a plurality of metal pattern regions and a plurality of non-metal pattern regions;
a plurality of first pyramid structures (<NUM>) and a plurality of second pyramid structures (<NUM>) disposed in each of the plurality of metal pattern regions, wherein a one-dimensional dimension of a bottom portion of each of the plurality of first pyramid structures is greater than a one-dimensional dimension of a bottom portion of each of the plurality of second pyramid structures in a same direction;
a plurality of third pyramid structures (<NUM>) and a plurality of fourth pyramid structures (<NUM>) disposed in each of the plurality of non-metal pattern regions, wherein a one-dimensional dimension of a bottom portion of each of the plurality of third pyramid structures is greater than a one-dimensional dimension of a bottom portion of each of the plurality of fourth pyramid structures in the same direction; and wherein an area proportion of the plurality of first pyramid structures on a portion of the front surface of the substrate in each respective metal pattern region is greater than an area proportion of the plurality of third pyramid structures on a portion of the front surface of the substrate in each respective non-metal pattern region;
a first tunneling layer (<NUM>) and a first doped conductive layer (<NUM>) formed only in each respective metal pattern region and stacked on the portion of the front surface of the substrate in each respective metal pattern region in a direction away from the substrate; and
a second tunneling layer (<NUM>) and a second doped conductive layer (<NUM>) stacked on a rear surface of the substrate in a direction away from the substrate.