Patent Description:
Photovoltaic cells are semiconductor devices that convert solar energy to electrical energy and are used to obtain clean, safe and renewable energy resources. The manufacture of the photovoltaic cells has received extensive attention due to their importance to reduce environmental pollution.

In a conventional process of the production and manufacture of the photovoltaic cell, in order to track processing information of the photovoltaic cell, it is usually necessary to form a marked region for constituting an identification code region on a surface of a substrate, and identify the identification code region constituted by the marked region to obtain the processing information and monitoring parameter information in the processing of the photovoltaic cell. However, generally, the marked region formed on the surface of the substrate affects reflectivity of incident light on the surface of the substrate and the marked region and damages the surface of the substrate, thereby reducing photoelectric conversion efficiency of the photovoltaic cell.

Patent Application <CIT> discloses a solar cell including a semiconductor substrate having a marking of recesses formed in a surface of the semiconductor substrate capable of increasing the area of active region while increasing the marking reading rate by enhancing the contrast between a marked region and other region.

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

The invention provides a photovoltaic cel according to claim <NUM> and including: a substrate; a marked region on a surface of the substrate, where the marked region is configured to mark product information of the photovoltaic cell; a first texture structure in the marked region on the surface of the substrate, where the first texture structure includes at least one first protrusion structure and at least one second protrusion structure, a respective first protrusion structure of the at least one first protrusion structure has a recessed top surface recessing toward a bottom surface of the respective first protrusion structure, and a respective second protrusion structure of the at least one second protrusion structure includes a pyramid structure; and a second texture structure disposed on a part of the surface of the substrate outside the marked region, wherein the second texture structure includes at least one third protrusion structure, and a respective third protrusion structure of the at least one third protrusion structure includes a pyramid structure.

In the invention, the respective first protrusion structure includes a bottom portion of a pyramid structure under the recessed top surface.

In some embodiments, an included angle between a side wall of the respective first protrusion structure and the bottom surface of the respective first protrusion structure is in a range of <NUM>° to <NUM>°.

In the invention, the recessed top surface of the respective first protrusion structure is lower than a top end of a respective second protrusion structure of at least one second protrusion structure adjacent to the respective first protrusion structure in a direction of the substrate toward the first texture structure.

In some embodiments, the recessed top surface of the respective first protrusion structure includes one of a hemispherical recessed surface and a conical recessed surface.

In some embodiments, a ratio of a minimum distance to a maximum distance from the recessed top surface of the respective first protrusion structure to the bottom surface of the respective first protrusion structure in a direction of the substrate toward the first texture structure to is not greater than <NUM>%.

In some embodiments, a minimum distance from the recessed top surface of the respective first protrusion structure to the bottom surface of the respective first protrusion structure in a direction of the substrate toward the first texture structure is in a range of <NUM> to <NUM>.

In some embodiments, the first texture structure includes a plurality of second protrusion structures, and the plurality of second protrusion structures are disposed around the at least one first protrusion structure.

In some embodiments, the first texture structure includes a plurality of first protrusion structures spaced apart, and at least one of the at least one second protrusion structure is disposed between adjacent first protrusion structures.

In some embodiments, at least one of the at least one second protrusion structure includes a first pyramid structure, and a distance between a top end of the first pyramid structure and the surface of the substrate in a direction of the substrate toward the first texture structure is in a range of <NUM> to <NUM>.

In some embodiments, at least one of the at least one second protrusion structure includes a second pyramid structure, a top end of the second pyramid structure is lower than the top end of the first pyramid structure, and the second pyramid structure is adjacent to at least one first pyramid structure.

In some embodiments, the second pyramid structure includes an inclined portion, a side wall of the inclined portion is inclined with respect to the surface of the substrate, and a height of the inclined portion is in a range of <NUM> to <NUM> in the direction of the substrate toward the first texture structure.

The invention also provides a method for forming the photovoltaic cell according to claim <NUM> and including: providing a substrate; forming a marked region on a surface of the substrate; forming a first texture structure in the marked region on the surface of the substrate, where the first texture structure includes at least one first protrusion structure and at least one second protrusion structure, a respective first protrusion structure of the at least one first protrusion structure includes a recessed top surface recessing toward a bottom surface of the respective first protrusion structure, and a respective second protrusion structure of the at least one second protrusion structure includes a pyramid structure; forming a second texture structure on a part of the surface of the substrate outside the marked region, where the second texture structure includes at least one third protrusion structure, and a respective third protrusion structure of the at least one third protrusion structure includes a pyramid structure.

In some embodiments, forming the marked region includes forming the marked region on the surface of the substrate using a laser.

In some embodiments, a wavelength of the laser is <NUM>, a pulse duration of the laser is in a range of 10ns to 100ns, a pulse repetition frequency of the laser is in a range of <NUM> to <NUM>, and a power percentage of the laser is in a range of <NUM>% to <NUM>%.

The invention also provides a photovoltaic module according to claim <NUM> and including: a cell string including a plurality of photovoltaic cells, where each of the plurality of photovoltaic cells is according to the above embodiments or is formed according to the above embodiments; an encapsulation layer configured to cover a surface of the cell string; and a cover plate configured to cover a surface of the encapsulation layer away from the 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. Elements with the same reference numerals in the accompanying drawings are represented as similar elements, and the figures in the accompanying drawings do not constitute a proportion limitation unless otherwise stated.

It is seen from BACKGROUND that, generally, reflectivity of incident light on the surface of the substrate may be affected when the marked region is formed on the surface of the substrate, thereby reducing the photoelectric conversion efficiency of the photovoltaic cell.

In order to solve the above problem, embodiments of the present disclosure provide a photovoltaic cell, which includes a marked region on the surface of the substrate and a non-marked region other than the marked region. A texture surface in the marked region is a first texture structure, a texture surface in the non-marked region is a second texture structure, and a top surface of a first protrusion structure in the first texture structure is a recessed surface, which is conducive to improving a light limiting effect of the first texture structure, reducing light reflectivity, thereby increasing density of photogenerated carriers in the substrate and improving the photoelectric conversion efficiency of the photovoltaic cell.

<FIG> is a top view of a substrate of a photovoltaic cell according to an embodiment of the present disclosure. <FIG> is a schematic cross-sectional view of a first texture structure of a photovoltaic cell according to an embodiment of the present disclosure. <FIG> is a schematic cross-sectional view of a second texture structure of a photovoltaic cell according to an embodiment of the present disclosure. <FIG> is another schematic cross-sectional view of a first projection structure in a photovoltaic cell according to an embodiment of the present disclosure. <FIG> is another schematic cross-sectional view of a first texture structure in a photovoltaic cell according to an embodiment of the present disclosure. <FIG> is a graph showing comparison between reflectivity of a photovoltaic cell according to an embodiment of the present disclosure and reflectivity of a conventional photovoltaic cell. <FIG> is another schematic cross-sectional view of a photovoltaic cell according to an embodiment of the present disclosure. <FIG> is still another schematic cross-sectional view of a photovoltaic cell according to an embodiment of the present disclosure.

Various embodiments of the present disclosure are described below in detail 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 in order to enable the reader to better understand the embodiments of the present disclosure. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solutions provided in the embodiments of the present disclosure are still able to be realized.

Referring to <FIG>, in the embodiments of the present disclosure, a photovoltaic cell includes a substrate <NUM>, a marked region <NUM> on a surface of the substrate <NUM>, a first texture structure <NUM> in a marked region on the surface of the substrate, and a second texture structure <NUM> disposed on a part of the surface of the substrate <NUM> outside the marked region <NUM>. The marked region <NUM> is configured to mark product information of the photovoltaic cell such that the product information can be tracked. The first texture structure <NUM> includes at least one first protrusion structure <NUM> and at least one second protrusion structure <NUM>, a respective first protrusion structure <NUM> of the at least one first protrusion structure <NUM> includes a recessed top surface recessing toward a bottom surface of the respective first protrusion structure <NUM>, and a respective second protrusion structure <NUM> of the at least one second protrusion structure <NUM> includes a pyramid structure. In some embodiments, the recessed top surface of the first protrusion structure <NUM> is a concave surface facing away from the substrate <NUM>. The second texture structure <NUM> includes at least one third protrusion structure <NUM>, and a respective third protrusion structure <NUM> of the third protrusion structure <NUM> includes the pyramid structure.

In some embodiments, the surface of the substrate <NUM> is a light receiving surface of the photovoltaic cell, i.e., a surface facing towards incident light, and the marked region <NUM> is disposed on the light receiving surface. The first texture structure <NUM> and the second texture structure <NUM> are disposed on the same surface of the substrate <NUM>. Furthermore, the substrate <NUM> has two opposite surfaces. In some embodiments, the photovoltaic cell is a single-sided cell, one surface of the substrate <NUM> serves as a light receiving surface and the other surface serves as a backlight surface, and correspondingly, the first texture structure <NUM> and second texture structure <NUM> are disposed on the light receiving surface of the substrate <NUM>. In some embodiments, the photovoltaic cell is a double-sided cell, both the two opposite surfaces of the substrate <NUM> serve as light receiving surfaces, and correspondingly, the marked region <NUM> may be disposed on at least one of the two opposite surfaces of the substrate <NUM>, i.e., the first texture structure <NUM> and the second texture structure <NUM> may be disposed on one of the surfaces of the substrate <NUM>. Alternatively, the marked region <NUM> may be disposed on the two opposite surfaces of the substrate <NUM>, i.e., both the first texture structure <NUM> and the second texture structure <NUM> are disposed on the two opposite surfaces of the substrate <NUM> respectively. In some embodiments, the substrate <NUM> may be a silicon substrate <NUM>, and a material of the silicon substrate <NUM> may include single crystal silicon, polysilicon, amorphous silicon, microcrystalline silicon, etc. In some embodiments, the material of the substrate <NUM> may also be a carbon element, an organic material, and a plurality of compounds including gallium arsenide, cadmium telluride, copper indium selenium, etc..

In the marked region <NUM>, an identification code pattern is formed, and then the identification code pattern is scanned so as to identify processing information and monitoring parameter information of the photovoltaic cell, which is conducive to tracing the processing process of the photovoltaic cell. Furthermore, even if a passivation film is subsequently formed on the substrate <NUM>, the marked region <NUM> covered with the transparent passivation film layer does not obstruct reading of the identification code pattern. The identification code pattern may be a one-dimensional graphic code, a two-dimensional graphic code, or a three-dimensional graphic code. In some embodiments, the identification code may also be in the form of a character, a data matrix, a bar code, etc..

In some embodiments, the marked region <NUM> may be disposed between grid electrodes that are disposed on the surface of the substrate <NUM>, and the marked region <NUM> does not overlap with the grid electrodes. In some embodiments, the marked region <NUM> may partially overlap with the grid electrodes formed on the surface of the substrate <NUM>. The number of grid electrodes overlapped with the marked region <NUM> is in a range of <NUM> to <NUM>, preferably in a range of <NUM> to <NUM>. The marked region <NUM> and the grid electrodes thus provided are able to ensure effective current collection by the gate electrodes and minimize damage to the surface of the substrate <NUM>.

Referring to <FIG>, the light receiving surface of the substrate <NUM> excluding the marked region <NUM> is defined as a non-marked region <NUM>. The first texture structure <NUM> constitutes a texture surface of the marked region <NUM>, the second texture structure <NUM> constitutes a texture surface of the non-marked region <NUM>, and the first texture structure <NUM> disposed in the marked region <NUM> not only ensures that the surface of the substrate <NUM> has the identification code pattern for tracing the information of the photovoltaic cell, but also facilitates reducing the reflectivity of the incident light received by the photovoltaic cell. This is because the top surface of the first protrusion structure <NUM> in the first texture structure <NUM> has a recessed surface compared with the first texture structure <NUM> being the pyramid structure, the presence of the recessed surface enables the first texture structure <NUM> to reflect light multiple times, thereby enhancing the light limiting effect of the first texture structure <NUM> and reducing the reflectivity of the light. Specifically, when light is incident on a first region of the recessed surface of the first protrusion structure <NUM>, part of the light is transmitted through the first protrusion structure <NUM> into the substrate <NUM>, and the remaining part of the light is reflected through the recessed surface to form reflected light. The reflected light reaches a second region of the recessed surface when propagating, part of the reflected light is transmitted through the first protrusion structure <NUM> into the substrate <NUM>, and the remaining part of the reflected light is reflected again to form reflected light. The reflected light reaches the recessed surface again when propagating, so that multiple times of transmission of the light is realized so as to increase an absorption rate of the light, thereby increasing the light limiting effect and reducing the reflectivity of the light. It should be understood that the second region and the first region may be different regions of the same recessed surface, or may be different regions of different recessed surfaces of different first protrusion structure <NUM>. The second texture structure <NUM> also has a good light limiting effect relative to the surface of the smooth substrate <NUM>.

From the above, it is seen that the texture surface formed by the second texture structure <NUM> and the first texture structure <NUM> on the light receiving surface of the substrate <NUM> satisfies the requirement of the product information for marking the photovoltaic cell while enabling the entire surface of the substrate <NUM> to have a better light limiting effect, which is conducive to improving absorption and utilization of the incident light by the photovoltaic cell.

The first texture structure <NUM> is composed of at least one first protrusion structure <NUM> and at least one second protrusion structure <NUM> connected to each other, and the at least one first protrusion structure <NUM> and the at least one second protrusion structure <NUM> are continuously disposed in a direction perpendicular to a direction of the substrate <NUM> toward the first texture structure <NUM>. Furthermore, the first protrusion structure <NUM> and the second protrusion structure <NUM> may be disposed in such a manner that a plurality of contiguous first protrusion structures <NUM> and a plurality of contiguous second protrusion structures <NUM> are connected, or the at least one first protrusion structure <NUM> and the at least one second protrusion structures <NUM> are disposed irregularly and connected to each other.

In some embodiments, referring to <FIG> and <FIG>, the first protrusion structure <NUM> is adjacent to at least one second protrusion structure <NUM>, and the recessed top surface of the first protrusion structure <NUM> is lower than the top end of the second protrusion structure <NUM> adjacent to the first protrusion structure <NUM> in a direction of the substrate <NUM> toward the first texture structure <NUM>. The advantages of such configuration include, on the one hand, that since the second protrusion structure <NUM> adjacent to the first protrusion structure <NUM> is higher than the first protrusion structure <NUM>, the reflected light formed after the incident light is reflected through the recessed surface easily reaches the side wall of the second protrusion structure <NUM>, so that the reflected light is reflected on the side wall of the second protrusion structure <NUM>, the reflected light is incident on the recessed surface again to be transmitted into the substrate <NUM> through the first protrusion structure <NUM>, and part of the reflected light is able to be transmitted to the recessed surface again after the reflection as described above, thereby further improving the absorption rate of the light and the light limiting effect. On the other hand, the incident light from the outside reaches the side wall of the second protrusion structure <NUM> to form the reflected light, since the first protrusion structure <NUM> is shorter than the second protrusion structure <NUM>, the reflected light is easily transmitted to the recessed surface so as to be transmitted into the substrate <NUM>, thereby further improving the absorption rate of the light.

In some embodiments, with continued reference to <FIG>, the first texture structure <NUM> may include a plurality of second protrusion structures <NUM>, and the plurality of second protrusion structures <NUM> are disposed around the at least one first protrusion structure <NUM>. The plurality of second protrusion structures <NUM> may be disposed around one first protrusion structure <NUM>, and the plurality of second protrusion structures <NUM> may be disposed around the plurality of first protrusion structures <NUM>.

In some embodiments, the first texture structure <NUM> may include a plurality of spaced apart first protrusion structures <NUM> with at least one second protrusion structure <NUM> disposed between adjacent first protrusion structures <NUM>. For example, a plurality of second protrusion structures <NUM> are provided between the adjacent first protrusion structures <NUM>.

In some embodiments, referring to <FIG> and <FIG>, the first protrusion structure <NUM> includes a bottom portion of a pyramid structure under the recessed top surface.

Accordingly, the first protrusion structure <NUM> has a side surface inclined with respect to the surface of the substrate <NUM>, so that the received incident light is able to be reflected again onto the substrate <NUM>, which increases absorption of the incident light by the substrate <NUM>. In some embodiments, the first protrusion structure <NUM> may also be a conical structure having a recessed surface at a top portion.

In some embodiments, referring to <FIG> and <FIG>, the top surface of the first protrusion structure <NUM> may be a hemispherical recessed surface, and accordingly, the top surface of the first protrusion structure <NUM> may have a circular arc shape in cross-section perpendicular to the surface of the substrate <NUM>. In some embodiments, the top surface of the first protrusion structure <NUM> may also be a conical recessed surface, and accordingly, the top surface of the first protrusion structure <NUM> has a triangular shape in cross-section perpendicular to the surface of the substrate <NUM>. It is understood that the top surface of the first protrusion structure <NUM> may be a recessed surface of another shape as long as it is possible to realize multiple reflection of the incident light on the recessed surface.

Referring to <FIG> and <FIG>, an included angle between the side wall of the first protrusion structure <NUM> and the bottom surface of the first protrusion structure <NUM> is denoted as A1, and the included angle A1 may be in a range of <NUM>° to <NUM>°. Preferably, the included angle A1 between the side wall of the first protrusion structure <NUM> and the bottom surface of the first protrusion structure <NUM> is in a range of <NUM>° to <NUM>°, e.g., <NUM>°, <NUM>°, <NUM>°, etc..

In some embodiments, referring to <FIG> and <FIG>, a ratio of a minimum distance H2 to a maximum distance H1 from the recessed top surface to the bottom surface of the same first protrusion structure <NUM> in the direction of the substrate <NUM> toward the first texture structure <NUM> is not greater than <NUM>%. For example, the ratio of H2 to H1 may be <NUM>%, <NUM>%, <NUM>%, <NUM>%, etc..

In some embodiments, referring to <FIG> and <FIG>, the minimum distance H2 from the recessed top surface of the first protrusion structure <NUM> to the bottom surface of the first protrusion structure <NUM> in the direction of the substrate <NUM> toward the first texture structure <NUM> may be in a range of <NUM> to <NUM>, preferably in a range of <NUM> to <NUM>. For example, H2 is <NUM>, the ratio of H2 to H1 is <NUM>%, and H1 is calculated as <NUM>.

The second protrusion structure <NUM> may be a pyramid structure having a tip. In some embodiments, the first texture structure <NUM> may include a plurality of connected second protrusion structures <NUM>, interface points of adjacent second protrusion structures <NUM> are spaced from the surface of the substrate <NUM>. That is, the plurality of second protrusion structures <NUM> may be divided into a base portion constituted by the second protrusion structures <NUM> connecting to form an integral body and a plurality of inclined portions on the base portion, and side walls of the inclined portions are inclined with respect to the surface of the substrate <NUM>. In some embodiments, the sidewalls of the at least one second protrusion structure <NUM> may also be adjacent to the surface of the substrate <NUM>.

In some embodiments, referring to <FIG>, the at least one second protrusion structure <NUM> is a first pyramid structure, and a distance H3 between a top end of the first pyramid structure and the surface of the substrate <NUM> in the direction of the substrate <NUM> toward the first texture structure <NUM> may be in a range of <NUM> to <NUM>, preferably, H3 may be in a range of <NUM> to <NUM>. For example, H3 is <NUM>, <NUM>, <NUM>, etc..

In some embodiments, the at least one second protrusion structure <NUM> is a second pyramid structure, a top end of the second pyramid structure is lower than the top end of the first pyramid structure, and the second pyramid structure is adjacent to at least one first pyramid structure. The second protrusion structure <NUM> provided with the first pyramid structure and the second pyramid structure is able to increase an area of the region in which the second protrusion structure <NUM> receives the incident light as compared to the second protrusion structure <NUM> provided with the pyramid structure having the same height, thereby further improving the absorption rate of the incident light.

Referring to <FIG>. in some embodiments, the second pyramid structure includes an inclined portion, the sidewall of the inclined portion is inclined with respect to the surface of the substrate <NUM>, and a height H4 of the inclined portion in the direction of the substrate <NUM> toward the first texture structure <NUM> may be in a range of <NUM> to <NUM>, preferably in a range of <NUM> to <NUM>. For example, the height H4 of the inclined portion is <NUM>, <NUM>, <NUM>, etc..

Referring to <FIG>, the second texture structure <NUM> is composed of a plurality of third protrusion structures <NUM> disposed continuously in a direction perpendicular to a direction of the substrate <NUM> toward the second texture structure <NUM>. Since the third projection structure <NUM> is the pyramid structure, the third projection structure <NUM> also has an inclined side wall, so as to reduce the reflectivity of the substrate <NUM> to the incident light. In some embodiments, a maximum distance from the third protrusion structure <NUM> to the surface of the substrate <NUM> in the direction of the substrate <NUM> toward the second texture structure <NUM> may be about <NUM>, and a maximum angle of the tip of the pyramid structure may be about <NUM>°. In some embodiments, the third protrusion structure <NUM> may also be a pyramid structure of other sizes or a tapered structure of other shapes.

In addition, since the surface of the substrate <NUM> at the non-marked region <NUM> where the second texture structure <NUM> is not formed may be a smooth surface, and the surface of the substrate <NUM> in the marked region <NUM> where the first texture structure <NUM> is not formed may be a surface having a recess, the third protrusion structure <NUM> is different from the second protrusion structure <NUM>. The difference is that the bottom surface of the pyramid structure of the third protrusion structure <NUM> is lower than the bottom surface of the pyramid structure of the second protrusion structure <NUM>.

The second texture structure <NUM> is connected to the first texture structure <NUM> to form a light receiving surface of the substrate <NUM>. In some embodiments, the connection between the first texture structure <NUM> and the second texture structure <NUM> may be a connection between the second protrusion structure <NUM> and the third protrusion structure <NUM>. In such a connection mode, on the one hand, the surface of the substrate <NUM> has a continuous texture surface, and absorption of the incident light by the substrate <NUM> is increased. On the other hand, since the bottom surface of the pyramid structure of the third protrusion structure <NUM> is lower than the bottom surface of the pyramid structure of the second protrusion structure <NUM>, a contacted side surface having a large area is also able to be formed at a connection position of the third protrusion structure <NUM> and the second protrusion structure <NUM>, which is conducive to improving the absorption effect of the substrate <NUM> to the incident light. It should be appreciated that in some embodiments, as shown in <FIG>, the connection between the first texture structure <NUM> and the second texture structure <NUM> may be the connection between the first protrusion structure <NUM> and the third protrusion structure <NUM>, which also provides a continuous texture surface for the surface of the substrate <NUM>, thereby improving the photoelectric conversion efficiency of the photovoltaic cell.

In some embodiments, referring to <FIG>, the photovoltaic cell may further include an emitter <NUM>, an antireflection layer <NUM>, a passivation layer <NUM>, a first electrode <NUM>, and a second electrode <NUM>. It should be appreciated that the substrate <NUM> has a texture surface as a light receiving surface and that a surface of the substrate <NUM> opposite the light receiving surface may be a backlight surface. The emitter <NUM> may be disposed on the light receiving surface of the substrate <NUM>, and a doping element of the emitter <NUM> may be a P-type doping element (such as boron, aluminum, gallium, indium, thallium, etc.) or an N-type doping element (such as phosphorus, arsenic, antimony, bismuth, etc.). Furthermore, a PN junction is formed between the substrate <NUM> and the emitter <NUM>. For example, the emitter <NUM> includes the N-type doping element, and the substrate <NUM> includes the P-type doping element. The emitter <NUM> includes the P-type doping element, and the substrate <NUM> includes the N-type doping element. The antireflection layer <NUM> is disposed on a surface of the emitter <NUM> away from the substrate <NUM>, and plays a role of antireflection of the incident light, i.e., to reduce the reflectivity of the substrate <NUM> to the incident light. The passivation layer <NUM> is disposed on the backlight surface of the substrate <NUM> to play a role of passivation protection. The first electrode <NUM> is disposed on the light receiving surface of the substrate <NUM> and penetrates the antireflection layer <NUM> to be electrically connected to the emitter <NUM>. The second electrode <NUM> is disposed on the backlight surface of the substrate <NUM> and penetrates the passivation layer <NUM> to be electrically connected to the substrate <NUM>.

Referring to <FIG>, a topography of the first protrusion structure <NUM> and a topography of the second protrusion structure <NUM> in a conventional photovoltaic cell are both conventional pyramid structures having tips. The abscissa in <FIG> shows a wavelength of the incident light, and the ordinate in <FIG> shows the reflectivity of the texture surface the photovoltaic cell. It is seen from <FIG> that the reflectivity of the photovoltaic cell provided in the embodiment of the present disclosure is lower than that of the conventional photovoltaic cell. Therefore, the technical solution provided in the embodiment of the present disclosure is able to increase the absorption of the incident light, and improve reduction of cell efficiency due to the damage of the marked region <NUM>.

The photovoltaic cell provided in the above embodiments has the marked region <NUM> on the surface of the substrate <NUM> for receiving the incident light, and the marked region <NUM> is configured to constitute the identification code pattern, and the identification code pattern is scanned so that the processing information of the photovoltaic cell is able to be quickly obtained, which is conducive to improving information integration and information tracing in the production process of the photovoltaic cell. The texture surface disposed on the surface of the substrate <NUM> includes the first texture structure <NUM> in the marked region <NUM> and the second texture structure <NUM> at the non-marked region <NUM>, the first protrusion structure <NUM> and the second protrusion structure <NUM> are connected to form the first texture structure <NUM>, and the third protrusion structures <NUM> are connected to form the second texture structure <NUM>. Since the first protrusion structure <NUM>, the second protrusion structure <NUM> and the third protrusion structure <NUM> have the effect of reducing the reflectivity, the first texture structure <NUM> and the second texture structure <NUM> also have the effect of reducing the reflectivity. Thus, the surface of the substrate <NUM> formed by the first texture structure <NUM> and the second texture structure <NUM> has a better light limiting effect, which is conducive to increasing the photoelectric conversion efficiency of the photovoltaic cell.

Accordingly, embodiments of the present disclosure further provide a method for forming a photovoltaic cell, which is able to be used to form the photovoltaic cell provided in the above embodiments. It should be noted that the same or corresponding parts with the above embodiments may be described in detail with reference to the above embodiments, and details will not be described below.

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

Referring to <FIG>, the method for forming the photovoltaic cell includes providing a substrate <NUM>, forming a marked region <NUM> on a surface of the substrate <NUM>, forming a first texture structure <NUM> in the marked region <NUM> of the surface of the substrate <NUM>, and forming a second texture structure <NUM> on a part of the surface of the substrate <NUM> outside the marked region <NUM>. The first texture structure <NUM> includes at least one first protrusion structure <NUM> and at least one second protrusion structure <NUM>, a respective first protrusion structure <NUM> of the at least one first protrusion structure <NUM> has a recessed top surface recessing toward a bottom surface of the respective first protrusion structure <NUM>, and a respective second protrusion structure <NUM> of the at least one second protrusion structure <NUM> includes a pyramid structure. The second texture structure <NUM> includes at least one third protrusion structure <NUM>, and a respective third protrusion structure <NUM> of the third protrusion structure <NUM> includes a pyramid structure.

Referring to <FIG>, the substrate <NUM> has two opposite surfaces, i.e., a front surface and a rear surface of the substrate <NUM>, respectively. The front surface of the substrate <NUM> is defined as a light receiving surface. Referring to <FIG>, the marked region <NUM> is formed on the front surface of the substrate <NUM>. It should be appreciated that, in some embodiments, the rear surface of the substrate <NUM> is defined as the light receiving surface and the surface of the substrate <NUM> forming the marked region <NUM> may also be the rear surface.

Referring to <FIG>, the marked region <NUM> may be a recess or a line of connected recesses, which constitutes an identification code pattern for identifying information of the photovoltaic cell, and the substrate <NUM> of each independent photovoltaic cell has an independent and unique identification code pattern, and the information of the identification code pattern is identified and analyzed by photographing the identification code pattern, which is conducive to tracing the processing information and monitoring parameter information of the photovoltaic cell.

In some embodiments, an operation of forming the marked region <NUM> includes forming the marked region <NUM> on the surface of the substrate <NUM> using a laser.

When using the laser to form the marked region <NUM>, the shape and depth of the recesses formed on the surface of the substrate <NUM> are more easily controlled, thereby controlling subsequent forming of a specific structure of the texture surface, so as to form the first protrusion structure <NUM> and the second protrusion structure <NUM> having better light limiting effects. It should be appreciated that, in some embodiments, the marked region <NUM> may also be formed by plasma etching, high energy particle impact, chemical etching, etc..

In some embodiments, a wavelength of the laser forming the marked region <NUM> is <NUM>, a pulse duration of the laser is in a range of 10ns to 100ns, a pulse repetition frequency of the laser is in a range of <NUM> to <NUM>, and a power percentage of the laser is in a range of <NUM>% to <NUM>%.

The size of the recesses formed after the laser processing determines the size of the second protrusion structure <NUM> (as shown in <FIG>) and the angle of the recessed surface of the first protrusion structure <NUM> at the top (as shown in <FIG>) in a subsequent texture making process. Through the marked region <NUM> formed by the laser having the above parameters, the first texture structure <NUM> having the first protrusion structure <NUM> and the second protrusion structure <NUM> (as shown in <FIG>) is formed after the texture making, which is able to reduce the reflectivity of the incident light by <NUM>% as compared to the texture surface formed without the laser treatment, thereby forming the photovoltaic cell with higher efficiency.

Referring to <FIG>, after the surface of the substrate <NUM> is coded, a texture surface is formed by texture making. The purpose of texture making is that the substrate <NUM> of the photovoltaic cell is processed through a plurality of processes such as slicing, grinding, chamfering, polishing, and the like, and a lot of impurities such as particles, metal particles, silicon dust or organic matter are adsorbed on the surface of the substrate <NUM>. Before further diffusion or other processing, texture making is required to eliminate various pollutants, remove a mechanical damage layer on the surface of the substrate <NUM>, and obtain a texture surface capable of capturing more photons.

In some embodiments, the texture making method may be using an alkali solution to etch, the alkali solution includes a solution containing NaOH, KOH, TMAH, etc. Since recesses of different degrees are formed in the marked region <NUM> on the surface of the substrate <NUM>, when the alkali solution performs anisotropic etching on crystal planes, a crystal plane having recesses is etched to form a pyramid structure. As the etching proceeds, a small texture is formed on the surface of the pyramid structure to form the second protrusion structure <NUM>. In the non-etching crystal plane, the recess is remained to form a protrusion structure having a recessed top surface, i.e., the first protrusion structure <NUM>. The third protrusion structure <NUM> is formed on the surface of the substrate <NUM> excluding the marked region <NUM>. In some embodiments, the texture making method may be at least one of electrochemical texture making, reactive ion etching texture making, laser texture making, and mask texture making.

With continued reference to <FIG>, after the texture making, the texture surface formed in the marked region <NUM> is the first texture structure <NUM>, and the texture surface formed on the surface of the substrate <NUM> excluding the marked region <NUM> is the second texture structure <NUM>. The first texture structure <NUM> includes the first protrusion structure <NUM> and the second protrusion structure <NUM>, and the second texture structure <NUM> includes the third protrusion structure <NUM>. The first protrusion structure <NUM> having a recessed top surface, the second protrusion structure <NUM> having an inclined side surface, and the third protrusion structure <NUM> enable the first texture structure <NUM> and the second texture structure <NUM> on the surface of the substrate <NUM> to have a better light limiting effect, thereby being able to capture more photons and improving the photoelectric conversion efficiency of the photovoltaic cell. For specific shapes of the first texture structure <NUM>, the second texture structure <NUM>, the first protrusion structure <NUM>, the second protrusion structure <NUM>, and the third protrusion structure <NUM>, the above embodiments may be referred to, and details are not described herein.

Referring to <FIG>, in some embodiments, the processing method of the photovoltaic cell may further include forming an emitter <NUM>, an antireflection layer <NUM>, a passivation layer <NUM>, a first electrode <NUM>, and a second electrode <NUM> on the substrate <NUM> of the photovoltaic cell.

The method for forming the photovoltaic cell provided in the above embodiments is able to trace the processing information of each individual photovoltaic cell by forming the marked region <NUM> on the surface of the substrate <NUM> using the laser. When the marked region <NUM> is formed using the laser, the surface of the substrate <NUM> having recesses is formed, and the surface of the substrate <NUM> having the recesses may form the first texture structure <NUM> in subsequent texture making. In addition, the second texture structure <NUM> is formed after texturing making of the surface of the substrate which has not been subjected to the laser treatment. The first texture structure <NUM> is provided with the first protrusion structure <NUM> and the second protrusion structure <NUM> connected to each other, and the second texture structure <NUM> is provided with the third protrusion structures <NUM> connected to each other. Since the first protrusion structure <NUM>, the second protrusion structure <NUM>, and the third protrusion structure <NUM> have good light limiting effects, both the first texture structure <NUM> and the second texture structure <NUM> have an effect of reducing reflectivity. Thus, the surface of the substrate <NUM> formed by the first texture structure <NUM> and the second texture structure <NUM> is able to reduce the reflectivity of the incident light and improve the photoelectric conversion efficiency of the photovoltaic cell.

Accordingly, embodiments of the present disclosure further provide a photovoltaic module including the photovoltaic cell having the marked region <NUM> provided in the above embodiments. <FIG> is a schematic structural diagram of a photovoltaic module according to an embodiment of the present disclosure.

Referring to <FIG>, the photovoltaic module includes a cell string <NUM> including a plurality of photovoltaic cells, an encapsulation layer <NUM> configured to cover a surface of the cell string <NUM>, and a cover plate <NUM> configured to cover a surface of the encapsulation layer <NUM> away from the cell string <NUM>. The plurality of photovoltaic cells are electrically connected to form a plurality of cell strings <NUM> in a form of a whole piece or a plurality of pieces.

In the photovoltaic module provided in the above embodiments, since the texture surface of the photovoltaic cell has a better light limiting effect, the photovoltaic cell has better photoelectric performance, so that the photovoltaic module has higher photoelectric conversion efficiency.

Claim 1:
A photovoltaic cell, comprising:
a substrate (<NUM>) having a surface with a marked region (<NUM>) and a non-marked region (<NUM>), the marked region (<NUM>) comprising a first texture structure (<NUM>) constituting an identification code pattern for marking product information of the photovoltaic cell;
wherein the first texture structure (<NUM>) formed in the marked region (<NUM>) includes at least one first protrusion structure (<NUM>) and at least one second protrusion structure (<NUM>), and wherein each first protrusion structure (<NUM>) includes a truncated pyramid having a recessed top surface recessing toward a bottom surface of the truncated pyramid, and each second protrusion structure (<NUM>) includes a pyramid structure, wherein the recessed top surface of each truncated pyramid (<NUM>) is lower than a top end of at least one second protrusion structure (<NUM>) adjacent to the truncated pyramid (<NUM>) in a direction toward the substrate (<NUM>); and
a second texture structure (<NUM>) formed in the non-marked region (<NUM>), wherein the second texture structure (<NUM>) includes at least one third protrusion structure (<NUM>), and each third protrusion structure (<NUM>) includes a pyramid structure.