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.

<CIT> relates to a solar cell and a photovoltaic module, and the solar cell comprises a substrate which is provided with a front surface and a back surface which are opposite to each other; the front surface of the substrate has a plurality of metal pattern regions, and a plurality of first pyramid structures is disposed in each of the plurality of metal pattern regions; the front surface passivation layer is located on the front surface of the substrate; the passivation contact structure penetrates through a partial region of the front surface passivation layer and is in contact with the front surface of the substrate; the first transparent conductive layer covers the surface of the front passivation layer and the surface of the passivation contact structure; the front electrode is positioned on the surface of the first transparent conductive layer and is opposite to the passivation contact structure; the back surface passivation layer is located on the back surface of the substrate; the second transparent conductive layer is located on the surface, away from the substrate, of the back passivation layer; and the back electrode is located on the surface of the second transparent conductive layer, and the embodiment of the utility model is at least beneficial to improving the photoelectric conversion efficiency of the solar cell.

<CIT> relates to the photovoltaic field, and provides a solar cell and a photovoltaic module, and the solar cell comprises a substrate, the substrate is provided with a front surface and a back surface which are opposite, the back surface comprises a first region and a second region adjacent to the first region, the substrate of the first region is internally provided with a doping element, and the doping element is N-type or P-type; in the first direction, the width of the first protruding structure of the first area is smaller than that of the second protruding structure of the second area, the first protruding structure comprises a platform protruding structure, and the top face of the platform protruding structure is a polygonal plane; the tunneling dielectric layer is positioned on the back surface of the substrate; the doped conductive layer is located on the surface of the tunneling dielectric layer, and the type of a doped element in the doped conductive layer is the same as that of a doped element in the first region; the back electrode is arranged along the first direction, the back electrode corresponds to the substrate in the first region, the back electrode is in contact with the doped conductive layer, and at least the photoelectric conversion efficiency of the solar cell can be improved.

<CIT> relates to a layer structure for solar cells, preferably for high-temperature solar cells, with tunnel oxide passivated contacts on the front side or on the front and rear of the solar cells, consisting of at least one tunnel oxide layer, in particular a silicon oxide layer SiOx with x C <NUM>-<NUM> or an alumina layer AlOx with x C1-<NUM>, and a µc-SiCx(n) layer, having x ≥ <NUM>, preferably ≥ <NUM> to <NUM>, wherein (n) = n-doped, and wherein the µc-SiCx(n) in an advantageous embodiment is a hydrated µc-SiCx:H (n) layer. The layer structure according to the invention can preferably be configured as a front-side contact of a solar cell, preferably a high-temperature solar cell. The invention further relates to a method for producing the layer structure and a solar cell containing the layer structure according to the invention as front or as front and rear contact.

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 having a front surface and a rear surface opposite to each other, wherein the front surface of the substrate has a plurality of metal pattern regions; a plurality of first pyramid structures disposed in each of the plurality of metal pattern regions; a plurality of platform protrusion structures disposed on the rear surface of the substrate, wherein a height of each of the plurality of first pyramid structures is greater than a height of each of the plurality of platform protrusion structures, and a one-dimensional dimension of a bottom portion of each of the plurality of first pyramid structures is less than a one-dimensional dimension of a bottom portion of each of the plurality of the platform protrusion structures; a first tunneling layer and a first doped conductive layer stacked on a portion of the front surface of the substrate in a respective metal pattern region in a direction away from the substrate, wherein the first tunneling layer and the first doped conductive layer are formed only in the metal pattern region, wherein a doping element type of the first doped conductive layer is the same as a doping element type of the substrate; and a second tunneling layer and a second doped conductive layer stacked on the rear surface of the substrate in a direction away from the substrate, wherein 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 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 a height from top to bottom of each of the plurality of first pyramid structures is in a range of <NUM> to <NUM>.

In some embodiments, an included angle between a respective one of bevel edges of a respective first pyramid structure and a bottom portion of the respective first pyramid structure is in a range of <NUM>° to <NUM>°.

In some embodiments, a length of each of the bevel edges of the respective first pyramid structure 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 platform protrusion structures is in a range of <NUM> to <NUM>, and a height from top to bottom of each of the plurality of platform protrusion structures is in a range of <NUM> to <NUM>.

In some embodiments, an included angle between a respective one of bevel edges of a respective platform protrusion structure and a bottom portion of the respective platform protrusion structure is in a range of <NUM>° to <NUM>°.

In some embodiments, a length of each of the bevel edges of the respective platform protrusion structure is in a range of <NUM> to <NUM>.

In some embodiments, the photovoltaic cell further includes a plurality of second pyramid structures disposed in each of the plurality of metal pattern regions, wherein an area proportion of the plurality of first pyramid structures on a portion of the front surface of the substrate in a 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 the respective metal pattern region, and an included angle between a respective one of bevel edges of a respective second pyramid structure and a bottom portion of the respective second pyramid structure is in a range of <NUM>° to <NUM>°.

In some embodiments, a one-dimensional dimension of a bottom portion of each of the plurality of second pyramid structures is not greater than <NUM>, and a height from top to bottom of each of the plurality of second pyramid structures is not greater than <NUM>.

In some embodiments, the front surface of the substrate has a plurality of non-metal pattern regions, and the photovoltaic cell further includes 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 dimension of a bottom portion of each of the plurality of third pyramid structures is greater than a dimension of a bottom portion of each of the plurality of fourth pyramid structures, an area proportion of the plurality of third pyramid structures on a portion of the front surface of the substrate in a respective non-metal pattern region is less than the area proportion of the plurality of first pyramid structures on the portion of the front surface of the substrate in the respective metal pattern region.

In some embodiments, an included angle between a respective one of bevel edges of a respective third pyramid structure and a bottom portion of the respective third pyramid structure is in a range of <NUM>° to <NUM>°, and an included angle between a respective one of bevel edges of a respective fourth pyramid structure and a bottom portion of the respective fourth pyramid structure is in a range of <NUM>° to <NUM>°.

In some embodiments, a length of each of the bevel edges of the respective third pyramid structure is in a range of <NUM> to <NUM>, and a length of each of the bevel edges of the respective fourth pyramid structure is in a range of <NUM> to <NUM>.

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

In some embodiments, 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 the 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 second passivation layer disposed on a surface of the second doped conductive layer away from the substrate.

In some embodiments, the photovoltaic cell further includes a first electrode disposed in the 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 the 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, the substrate includes an N-type silicon substrate.

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 an undiffused portion of 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, in the conventional photovoltaic cells, the texture structures on the front surface of the substrate and the rear surface of the substrate greatly affect the incident light and the quality of the film layers deposited on the surface of the substrate, and utilization of the incident light and the performance of the film layers play an important role in the photoelectric conversion performance of the photovoltaic cell.

In the photovoltaic cell provided in the embodiments of the present disclosure, a plurality of first pyramid structures are provided in each of a plurality of metal pattern regions of a front surface of a substrate, a plurality of platform protrusion structures are disposed on a rear surface of the substrate, a height of each first pyramid structure is greater than a height of each platform raised structure, and a dimension of a bottom portion of each first pyramid structure is less than a dimension of a bottom portion of each second pyramid structure. In this way, the roughness of the front surface is greater than the roughness of the rear surface, so that a reflectivity of the incident light on the front surface is less than a reflectivity of the incident light on the rear surface. On the one hand, the absorption of the incident light by the front surface is enhanced. On the other hand, in order to reduce parasitic absorption of the incident light by a first doped conductive layer, a first tunneling layer and the first doped conductive layer are formed only in the metal pattern region. Based on this, the roughness of a portion of the front surface of the substrate in the metal pattern region is large, and a contact area between the first tunneling layer and the front surface of the substrate and a contact area between the first doped conductive layer and the front surface of the substrate are increased, so as to provide a large tunneling channel for carriers in the substrate, thereby improving utilization of the incident light by the substrate without reducing the mobility of carriers. In addition, since the second doped conductive layer and the substrate form a PN junction, the roughness of the rear surface is relatively small, so that the second tunneling layer and the second doped conductive layer disposed on the rear surface have greater flatness. Thus, a contact interface between the second tunneling layer and the rear surface of the substrate has a good morphology, the defect state density of the rear surface of the substrate is reduced, and a probability of recombination of photogenerated carriers on the rear surface of the substrate is reduced, so that the mobility of the photogenerated carriers to the substrate is increased, which is conducive to improving a concentration of the carriers, thereby improving photoelectric conversion performance of the photovoltaic cell.

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 and a rear surface opposite to each other, the front surface of the substrate <NUM> having a plurality of metal pattern regions, a plurality of first pyramid structures <NUM> disposed in each of the plurality of metal pattern regions, a plurality of platform protrusion structures <NUM> disposed on the rear surface of the substrate <NUM>, 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 in a direction away from the substrate <NUM>, and a second tunneling layer <NUM> and a second doped conductive layer <NUM> stacked on the rear surface of the substrate <NUM> in a direction away from the substrate <NUM>. A height each of the plurality of first pyramid structures <NUM> is greater than a height of each of the plurality of platform protrusion structures <NUM>, and a one-dimensional dimension of a bottom portion of each of the plurality of first pyramid structures <NUM> is less than a one-dimensional dimension of a bottom portion of each of the plurality of the platform protrusion structures <NUM>. A doping element type of the first doped conductive layer <NUM> is the same as a doping element type of the substrate <NUM>. 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>.

In the embodiments of the present disclosure, dimensions and shapes of the texture structures (i.e., the pyramid structures) on the portion of the front surface of the substrate <NUM> in the metal pattern region are different so that the roughness of the front surface of the substrate <NUM> is greater than the roughness of the rear surface. On the one hand, the reflectivity of the incident light on the front surface of the substrate <NUM> is smaller than the reflectivity of the incident light on the rear surface of the substrate <NUM>, so that the absorption and utilization of the incident light by the front surface of the substrate <NUM> are enhanced.

On the other hand, in order to reduce the parasitic absorption of the incident light by the first doped conductive layer <NUM>, the first tunneling layer <NUM> and the first doped conductive layer <NUM> are formed only in the metal pattern region. Based on this, the roughness of the portion of the front surface of the substrate <NUM> in the metal pattern region is large, so that a specific surface area of the texture structure on the portion of the front surface of the substrate <NUM> in the metal pattern area is large. In this way, the contact area between the first tunneling layer <NUM> and the front surface of the substrate <NUM> and the contact area between the first doped conductive layer <NUM> and the front surface of the substrate <NUM> are increased. It should be understood that the first tunneling layer <NUM> and the first doped conductive layer <NUM> have passivation effects, which are able to reduce the defect state density at the interface of the surface of the substrate <NUM>, so that carriers in the substrate <NUM> is able to be tunneled into the first doped conductive layer <NUM> through a contact interface between the first tunneling layer <NUM> and the substrate <NUM> to achieve selective transmission of the carriers. It is seen that the tunneling channel of the carriers from the substrate <NUM> to the first doped conductive layer <NUM> is increased by increasing the contact area between the first tunneling layer <NUM> and the substrate <NUM>, so that the transmission efficiency of the carriers is improved, the concentration of carriers in the first doped conductive layer <NUM> is increased, and the short-circuit current and the open-circuit voltage are increased, thereby improving the utilization of the incident light by the substrate <NUM> while greatly reducing the mobility of the carriers.

In addition, since the second doped conductive layer <NUM> forms the PN junction with the substrate <NUM>, the PN junction is configured to generate photogenerated carriers, and the generated photogenerated carriers are transmitted into the substrate <NUM> and then transmitted from the substrate <NUM> into the first doped conductive layer <NUM>. Therefore, the roughness of the rear surface is configured to be small, so that the second tunneling layer <NUM> and the second doped conductive layer <NUM> provided on the rear surface have greater flatness, thus the contact interface between the second tunneling layer <NUM> and the rear surface of the substrate <NUM> has a good morphology. In this way, the defect state density of the rear surface of the substrate <NUM> is reduced, and the probability of the recombination of the photogenerated carriers generated by the PN junction on the rear surface of the substrate <NUM> is reduced, so that the mobility of the photogenerated carriers to the substrate <NUM> is improved, which is conducive to improving the concentration of the carriers, thereby improving photoelectric conversion performance of the photovoltaic cell.

The substrate <NUM> is configured to receive the incident light and generate the 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.

Specifically, in some embodiments, the substrate <NUM> is an N-type silicon 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 a rear junction (i.e., the PN junction formed on the rear surface of the substrate <NUM>).

In some embodiments, the substrate <NUM> may also be a P-type silicon 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.

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 first pyramid structures <NUM> are provided in the metal pattern region of the front surface of the substrate <NUM>, and the platform protrusion structures <NUM> are disposed on the rear surface of the substrate <NUM>. In this way, the roughness of the front surface is greater than the roughness of the rear surface, so that the mobility of carriers in the first tunneling layer <NUM> is not reduced while improving the utilization of the incident light by the substrate <NUM>. The roughness of the rear surface is configured to be small, so that the second tunneling layer <NUM> and the second doped conductive layer <NUM> provided on the rear surface have greater flatness, and the probability of the recombination of the photogenerated carriers generated by the PN junction on the rear surface of the substrate <NUM> is reduced, thereby improving the mobility of the photogenerated carriers to the substrate <NUM>. That is, the photoelectric conversion performance of the photovoltaic cell is improved as a whole by providing the texture structure on the front surface to match the film layer structure on the front surface of the substrate <NUM> and providing the texture structure on the rear surface of the substrate <NUM> to match the film layer structure on the rear surface of the substrate <NUM>.

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 should be noted that the dimensions of the plurality of first pyramid structures <NUM> and the plurality of second pyramid structures <NUM> are average dimensions within a sampling region.

In some embodiments, the dimension of the bottom portion of the first 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. The height from top to bottom of the first 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>, <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 first pyramid structures <NUM> unchanged, so that dimensional unevenness caused by slight dimensional differences between different first pyramid structures <NUM> is reduced.

Referring to <FIG>, in some embodiments, an included angle θ<NUM> between a respective one of bevel edges of a respective first pyramid structure <NUM> and a bottom portion of the respective first 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>°, or the like. Within this range, the bevel edges of the respective first pyramid structure <NUM> are less inclined with respect to the bottom portion of the respective first pyramid structure <NUM>, so that the portion of the front surface of the substrate <NUM> on which the first pyramid structures <NUM> are disposed has large roughness, thus the uniformity of the first tunneling layer <NUM> and the first doped conductive layer <NUM> deposited on the surface of the first pyramid structure <NUM> is high, which is conducive to improving the flatness of a contact interface between the first tunneling layer <NUM> and the front surface of the substrate <NUM>, reducing the interface state defect of the substrate <NUM>, and improving the mobility of carriers.

It should be understood that the larger the length of each bevel edge of the first pyramid structure <NUM>, the larger an area of each side surface of the first pyramid structure <NUM>, so that the contact area of the first pyramid structure <NUM> with the first tunneling layer <NUM> is larger. Based on this, in some embodiments, the length of each bevel edge of the first 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>, or the like. Within this range, the contact area between the first tunneling layer <NUM> and the front surface of the substrate <NUM> is increased while ensuring that the portion of the front surface of the substrate <NUM> on which the first pyramid structures <NUM> are disposed has large roughness, thereby further increasing the tunneling channel of the carriers and improving the mobility of the carriers.

Referring to <FIG>, and <FIG>, in some embodiments, a plurality of second pyramid structures <NUM> are disposed in each of the plurality of metal pattern regions, an area proportion of the plurality of first pyramid structures <NUM> on a portion of the front surface of the substrate <NUM> in a 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, and an included angle θ<NUM> between a respective one of bevel edges of a respective second pyramid structure <NUM> and a bottom portion of the respective second 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>°, or the like. The dimension of the second pyramid structure <NUM> is small, so that the roughness of the portion of the front surface of the substrate <NUM> in the metal pattern region on which the second pyramid structures <NUM> are disposed is small. In this way, the roughness of the surface of the first doped conductive layer <NUM> deposited on the portion of the front surface of the substrate <NUM> is small, thus the surface of the first doped conductive layer <NUM> deposited on the portion of the front surface of the substrate <NUM> has 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, both the first pyramid structures <NUM> and the second pyramid structures <NUM> are provided on the portion of front surface of the substrate <NUM> in the metal pattern region, which reduces the parasitic absorption of the incident light by the first doped conductive layer <NUM> while improving the mobility of carriers.

In some embodiments, a one-dimensional dimension of a bottom portion of each of the plurality of second pyramid structures <NUM> is not greater than <NUM>, and a height from top to bottom of each of the plurality of second pyramid structures <NUM> is not greater than <NUM>. Within this range, the portion of the front surface of the substrate <NUM> on which the second pyramid structures <NUM> are disposed has small roughness, so that a top surface of the first doped conductive layer <NUM> aligned with the second pyramid structures <NUM> has small roughness, which is conducive to reducing the parasitic absorption of the incident light by the first doped conductive layer <NUM>.

Referring to <FIG>, in some embodiments, the front surface of the substrate <NUM> further includes a plurality of non-metal pattern regions, and a plurality of third pyramid structures <NUM> and a plurality of fourth pyramid structures <NUM> are disposed in each of the plurality of non-metal pattern regions. 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>, and an area proportion of the plurality of third pyramid structures <NUM> on a portion of the front surface of the substrate <NUM> in a respective non-metal pattern region is less than 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. 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.

In some embodiments, the area proportion of the plurality of 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 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>%, or <NUM>%~<NUM>%. Within this range, the diffuse reflection effect on the portion of the front surface of the substrate <NUM> in the non-metal pattern region is improved while ensuring that the contact interface between the portion of the front surface of the substrate <NUM> in the metal pattern region and the first tunneling layer <NUM> has a good morphology, thereby improving the utilization of the incident light.

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 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. In should be noted that the dimensions of the plurality of third pyramid structures <NUM> and the plurality of fourth pyramid structures <NUM> are average dimensions within a sampling region.

Referring to <FIG>, in some embodiments, both the front surface of the substrate <NUM> and the rear surface of the substrate <NUM> serve as light receiving surfaces, when the incident light is irradiated to either the front surface of the substrate <NUM> or the rear surface of the substrate <NUM>, part of the incident light is reflected by the surface of the substrate <NUM>. Specifically, when the incident light is irradiated to one surface of the substrate <NUM>, the reflected part of the incident light is diffracted to the other surface of the substrate <NUM> through an encapsulation structure covering an outer surface of the photovoltaic cell or the surrounding environment, so as to be re-absorbed and used. For example, due to the low roughness of the rear surface of the substrate <NUM>, the reflectivity of the rear surface of the substrate <NUM> is large, so that the incident light irradiated to the rear surface of the substrate <NUM> are easily diffracted to the front surface of the substrate <NUM>, thus the incident light is re-absorbed and used by the front surface of the substrate <NUM>.

That is, the incident light irradiated to the front surface of the substrate <NUM> is incident into the substrate <NUM> after multiple reflections between adjacent third pyramid structures <NUM>, between the third pyramid structure <NUM> and the fourth pyramid structure <NUM>, and between adjacent fourth pyramid structures <NUM>. The more the number of reflection times of the incident light, the less the incident light emitted to the external of the photovoltaic cell, i.e., the more the incident light incident into the substrate <NUM>. The number of reflection times and the reflection angle of the incident light between adjacent third pyramid structures <NUM>, between the third pyramid structure <NUM> and the fourth pyramid structure <NUM>, and between adjacent fourth pyramid structures <NUM> is related to the angle between the bevel edge of the third pyramid structure <NUM> and the bottom portion of the third pyramid structure <NUM> and the angle between the bevel edge of the fourth pyramid structures <NUM> and the bottom portion of the fourth pyramid structure <NUM>.

Referring to <FIG>, in some embodiments, an included angle θ<NUM> between a respective one of bevel edges of a respective third pyramid structure <NUM> and a bottom portion of the respective third pyramid structure <NUM> is in a range of <NUM>° to <NUM>°, such as <NUM>°~<NUM>°, <NUM>°~<NUM>°, <NUM>°~<NUM>°, <NUM>°~<NUM>°, <NUM>°~<NUM>°, or the like. In some embodiments, an included angle θ<NUM> between a respective one of bevel edges of a respective fourth pyramid structure <NUM> and a bottom portion of the respective fourth pyramid structure <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 included angle range, the number of times of the incident light irradiated to the portion of the front surface of the substrate <NUM> in the non-metal pattern region and the incident light diffracted to the front surface of the substrate <NUM> again from the rear surface of the substrate <NUM> reflecting between the adjacent third pyramid structures <NUM>, between the third pyramid structure <NUM> and the fourth pyramid structure <NUM> or between the adjacent fourth pyramid structures <NUM> is large, so that the amount of the incident light emitted to the external of the photovoltaic cell is reduced. In addition, since the area proportion of the third pyramid structures <NUM> with the larger dimensions in the non-metal pattern region is larger, a total number of the third pyramid structures <NUM> and the fourth pyramid structures <NUM> per unit area is greater than that of the first pyramid structures <NUM> and the second pyramid structures <NUM> per unit area in the metal pattern region, so that the diffuse reflection effect of the non-metal pattern region is enhanced and the utilization of the incident light is improved.

It should be understood that, when the length of each bevel edge of the third pyramid structure <NUM> and the length of each bevel edge of the fourth pyramid structure <NUM> are larger, reflection paths of the incident light on the side surfaces of the third pyramid structure <NUM> and the fourth pyramid structure <NUM> are longer, so that the number of reflection times is increased, and the probability that the incident light is emitted to the external of the photovoltaic cell is reduced. Based on this, in some embodiments, a length of each of the bevel edges of the respective 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>, or the like. In some embodiments, a length of each of the bevel edges of the respective fourth pyramid structure 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 number of reflection times of the incident light between the third pyramid structure <NUM> and the fourth pyramid structure <NUM>, between the adjacent third pyramid structures <NUM>, and between the adjacent fourth pyramid structures <NUM> is increased, and the absorption and utilization of the incident light by the portion of the front surface of the substrate <NUM> in the non-metal pattern region are improved.

In some embodiments, the one-dimensional dimension of the bottom portion of each of the plurality of platform protrusion structures <NUM> 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. In some embodiments, a height from top to bottom of each of the plurality of platform protrusion structures is in a range of <NUM> to <NUM>, such as <NUM>~<NUM>, <NUM>~<NUM>, <NUM>~<NUM>, <NUM>~<NUM>, <NUM>~<NUM>, or the like. Specifically, referring to <FIG>, the platform protrusion structure <NUM> may be a base portion of a pyramid structure, i.e., a remaining portion of the pyramid structure after a spire of the pyramid structure is removed. Within this range, the height from top to bottom of the platform protrusion structure <NUM> is large, so that the portion of the rear surface of the substrate <NUM> on which the platform protrusion structures <NUM> are disposed is able to maintain a certain roughness, thus the reflectivity of the incident light on the rear surface of the substrate <NUM> is not excessively large as well as the utilization of the incident light by the rear surface of the substrate <NUM> is not excessively small while ensuring that the second tunneling layer <NUM> and the second doped conductive layer <NUM> formed on the rear surface of the substrate <NUM> have good flatness and uniformity, which is conducive to increasing the open-circuit voltage and the short-circuit current of the photovoltaic cell. In addition, the dimension of the bottom portion of the platform protrusion structure <NUM> is larger than that of the first pyramid structure <NUM> on the front surface of the substrate <NUM>, the height of the platform protrusion structure <NUM> is less than the height of the first pyramid structure <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>. Moreover, within this range, the height of the platform protrusion structure <NUM> is much smaller than the one-dimensional dimension of the bottom portion of the platform protrusion structure <NUM>, so that a morphology of the rear surface of the substrate <NUM> is nearly flat compared to that of the front surface of the substrate <NUM>, thus the second tunneling layer <NUM> and the second doped conductive layer <NUM> formed on the rear surface of the substrate <NUM> have better uniformity of thicknesses, and the contact surface between the second tunneling layer <NUM> and the rear surface of the substrate <NUM> has a good and flat morphology. In this way, the defect state density of the rear surface of the substrate <NUM> is reduced, so that the mobility of photogenerated carriers generated by the PN junction formed by the second doped conductive layer <NUM> and the substrate <NUM> is increased, the concentration of carriers in the substrate <NUM> is increased, and the open-circuit voltage and the short-circuit current are increased, thereby improving the photoelectric conversion efficiency of the photovoltaic cell.

It should be appreciated that, in the process of the incident light being reflected from the rear surface of the substrate <NUM> and then diffracted to the front surface of the substrate <NUM>, the path of the incident light is closely related to the angle between the platform protrusion structures <NUM> on the rear surface of the substrate <NUM> and the angle between the adjacent third pyramid structures <NUM> on the front surface of the substrate <NUM>, the angle between the adjacent fourth pyramid structures <NUM>, and the angle between the third pyramid structure <NUM> and the fourth pyramid structure <NUM>. Therefore, the angle between the platform protrusion structures <NUM> is adjusted so that the probability that the incident light reflected by the rear surface of the substrate <NUM> is diffracted to the front surface of the substrate <NUM> is large. Based on this, referring to <FIG>, in some embodiments, an included angle θ<NUM> between a respective one of bevel edges of a respective platform protrusion structure <NUM> and a bottom portion of the respective platform protrusion 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>°. Within this range, the angle between bevel edges of the two adjacent platform protrusion structures <NUM> on the rear surface of the substrate <NUM> is matched with the angle between bevel edges of the two adjacent third pyramid structures <NUM> on the front surface of the substrate <NUM>, the angle between bevel edges of the adjacent fourth pyramid structures <NUM> or the angle between the third pyramid structure <NUM> and the fourth pyramid structure <NUM>, so that the probability that the incident light reflected by the rear surface of the substrate <NUM> is diffracted to the front surface of the substrate <NUM> is high, and an incidence angle of the diffracted incident light on side surfaces of the third pyramid structure <NUM> or side surfaces of the fourth pyramid structure <NUM> is within an appropriate range, so that the reflectivity of the incident light diffracted to the front surface of the substrate <NUM> is reduced and the secondary utilization of the incident light by the substrate <NUM> is improved.

In some embodiments, a length of each of the bevel edges of the respective platform protrusion 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>, or the like. Within this range, a surface area of the platform protrusion structure <NUM> is increased while keeping the height of the platform protrusion structure <NUM> unchanged, which is conducive to increasing the contact area between the second tunneling layer <NUM> and the rear surface of the substrate <NUM> and increasing the tunneling channel of the carriers, thereby further improving the mobility of the carriers.

In some embodiments, a reflectivity of the portion of the front surface of the substrate 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. In some embodiments, a reflectivity of the rear surface of the substrate 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. Since the texture structures on the portion of the front surface of the substrate <NUM> in the non-metal pattern region are the third pyramid structures <NUM> and the fourth pyramid structures <NUM>, the reflectivity of the portion of the front surface of the substrate <NUM> in the non-metal pattern region is much smaller than the reflectivity of the rear surface of the substrate <NUM>, 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, increasing the short-circuit current and the open-circuit voltage, and improving the photoelectric conversion performance of the photovoltaic cell. However, in practical application, the incident light irradiated to the rear surface of the substrate <NUM> is less than the incident light irradiated to the front surface of the substrate <NUM>. In this way, the rear surface of the substrate <NUM> with high reflectivity is provided, which improves the flatness of the rear surface of the substrate <NUM>, so that uniformity and flatness of the second tunneling layer <NUM> and the second doped conductive layer <NUM> formed on the rear surface of the substrate <NUM> are improved, thereby improving the mobility of carriers. Moreover, even if the reflectivity of the rear surface of the substrate <NUM> is high, based on the arrangement of the included angle between the bevel edge and the bottom portion of the platform protrusion structure <NUM>, the arrangement of the included angle between the bevel edge and the bottom portion of the third pyramid structure <NUM> on the front surface of the substrate <NUM>, and the arrangement of the included angle between the bevel edge and the bottom portion of the fourth pyramid structure <NUM> on the rear surface of the substrate <NUM>, the probability that the incident light reflected from the rear surface of the substrate <NUM> is diffracted again to the front surface of the substrate <NUM> is high, so that the incident light is able to be used by the front surface of the substrate <NUM> with a low reflectivity, and the utilization of the incident light is increased while the mobility of carriers is improved.

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 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, 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>. Due to the small concave-convex degree of the platform protrusion structures <NUM> on the rear surface of the substrate <NUM>, the second passivation layer <NUM> deposited on the rear surface of the substrate <NUM> has high flatness, thereby improving the passivation performance of the second passivation layer <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, 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.

Referring to <FIG>, 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 first pyramid structures <NUM> are provided on the portion of the front surface of the substrate <NUM> in the metal pattern region, and the platform protrusion structures <NUM> are provided on the rear surface of the substrate <NUM>, so that the roughness of the front surface is greater than the roughness of the rear surface. In this way, on the one hand, the absorption of the incident light by the front surface is enhanced. On the other hand, a contact area between the first tunneling layer <NUM> and the front surface of the substrate <NUM> and a contact area between the first doped conductive layer <NUM> and the front surface of the substrate <NUM> are increased, so as to provide a large tunneling channel for carriers in the substrate, thereby improving utilization of the incident light by the substrate <NUM> without reducing the mobility of carriers. In addition, since the second doped conductive layer <NUM> and the substrate <NUM> form a PN junction, the roughness of the rear surface is relatively small, so that the second tunneling layer <NUM> and the second doped conductive layer <NUM> disposed on the rear surface have greater flatness. Thus, a contact interface between the second tunneling layer <NUM> and the rear surface of the substrate <NUM> has a good morphology, the defect state density of the rear surface of the substrate <NUM> is reduced, and a probability of recombination of photogenerated carriers on the rear surface of the substrate <NUM> is reduced, so that the mobility of the photogenerated carriers to the substrate <NUM> is increased, which is conducive to improving a concentration of the carriers, thereby improving photoelectric conversion performance of the photovoltaic cell.

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>) having a front surface and a rear surface opposite to each other, wherein the front surface of the substrate (<NUM>) has a plurality of metal pattern regions;
a plurality of first pyramid structures (<NUM>) disposed in each of the plurality of metal pattern regions;
a plurality of platform protrusion structures (<NUM>) disposed on the rear surface of the substrate (<NUM>), wherein a height of each of the plurality of first pyramid structures (<NUM>) is greater than a height of each of the plurality of platform protrusion structures (<NUM>), and a one-dimensional dimension of a bottom portion of each of the plurality of first pyramid structures (<NUM>) is less than a one-dimensional dimension of a bottom portion of each of the plurality of the platform protrusion structures (<NUM>);
a respective first tunneling layer (<NUM>) and a respective first doped conductive layer (<NUM>) stacked on a portion of the front surface of the substrate (<NUM>) in each respective metal pattern region of the plurality of metal pattern regions in a direction away from the substrate (<NUM>), wherein the respective first tunneling layer (<NUM>) and the respective first doped conductive layer (<NUM>) are formed only in the respective metal pattern region, wherein a doping element type of the respective first doped conductive layer (<NUM>) is the same as a doping element type of the substrate (<NUM>); and
a second tunneling layer (<NUM>) and a second doped conductive layer (<NUM>) stacked on the rear surface of the substrate (<NUM>) in a direction away from the substrate (<NUM>), wherein 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>).