CN106298984A - Solar cell - Google Patents

Abstract

A solar cell comprises a silicon substrate, an emitter layer, a plurality of first electrodes, a passivation layer and a plurality of second electrodes. The silicon substrate has a light receiving surface and a back surface. The emitter layer is formed under the light receiving surface. The plurality of first electrodes are positioned on the light receiving surface. The passivation layer is located on the back surface and provided with a plurality of linear openings. The second electrodes are respectively positioned in the linear openings and contact the back surface. The plurality of second electrodes are arranged in a plurality of columns along the extending direction and in a plurality of rows along an arrangement direction perpendicular to the extending direction. Each second electrode has a length a in the extending direction. The first distance B is maintained between any two adjacent second electrodes in the same row. 200 microns < B < 1400 microns, and 2 < A/B < 5. And maintaining a second spacing P between any two adjacent rows of second electrodes, wherein P is less than or equal to 1000 microns.

Description

Solar battery

technical field

The present invention relates to a solar cell, and more particularly to an emitter passivated and rear electrode solar cell (PERC).

Background technique

Under the circumstances of the shortage of petrochemical energy and the increasing demand for energy, the development of renewable energy (Renewable energy) has become one of the very important topics in recent years. Renewable energy generally refers to sustainable and non-polluting natural energy, such as solar energy, wind energy, water conservancy energy, tidal energy or biomass energy, among which the development of solar energy is very important and popular in the research of energy development in recent years part of the

A solar cell is a photovoltaic device for energy conversion, among which emitter passivated and back electrode solar cells have attracted much attention due to their high conversion efficiency. The main difference between emitter passivation and back electrode solar cells compared with traditional solar cells is that emitter passivation and back electrode solar cells use passivation technology to passivate the front emitter and back to reduce surface defects. The front emitter generally chooses silicon oxide (SiO ₂ ) as the passivation layer, while the back side generally chooses silicon oxide or aluminum oxide (Al ₂ O ₃ ) as the passivation layer.

In detail, the method of emitter passivation and back electrode formation of the back electrode of solar cells is usually to open holes in the passivation layer by means of laser to form electrode contact positions, and then screen print non-penetrating aluminum glue on the back Or it is plated with aluminum by physical vapor deposition (PVD), and finally it is co-sintered with silver screen printing on the front side to form an electrode, which is printed and sintered with aluminum paste on the back side of the traditional solar cell to form a comprehensive backside electric field (BSF ) are different. Since emitter passivation and back electrode solar cells are only partially opened on the back, a local back electric field (Local BSF) can eventually be formed and a large area of passivation layer can be retained. On the other hand, compared with conventional solar cells, emitter passivation and back electrode solar cells increase the area of the passivation layer passivation on the back side, thus effectively reducing the rate of carrier recombination on the back side.

Since the passivation layer on the back of the emitter passivation and back electrode solar cell is designed with partial openings, and the back electrode is in contact with the back of the substrate through the plurality of openings, the purpose of conducting current can be achieved. Although the design of the local contact between the back electrode and the back of the substrate can increase the passivation area of the passivation layer and reduce the recombination of carriers, it also leads to the reduction of the contact area between the back electrode and the back of the substrate, which in turn causes the problem of increased resistance. . Therefore, how to obtain a better balance point to effectively improve the photoelectric conversion efficiency has become one of the problems to be solved urgently.

Contents of the invention

The invention provides a solar cell, which can effectively improve the photoelectric conversion efficiency.

The invention provides a solar cell, which includes a silicon substrate, an emitter layer, a plurality of first electrodes, a passivation layer, and a plurality of second electrodes. The silicon substrate has a light-receiving surface and a back surface opposite to the light-receiving surface. The emitter layer is formed on the light receiving surface. The plurality of first electrodes are located on the light receiving surface. The passivation layer is located on the back side and has a plurality of linear openings. The plurality of second electrodes are respectively located in the plurality of linear openings and contact the back surface. Each second electrode has an extension direction. The plurality of second electrodes are arranged in multiple columns along the extending direction, and arranged in multiple rows along the arrangement direction perpendicular to the extending direction. The length of each second electrode in the extending direction is A. A first distance B is maintained between any two adjacent second electrodes in the same row, wherein 200 μm≦B≦1400 μm, and 2≦A/B≦5. A second distance P is maintained between any two adjacent rows of the plurality of second electrodes, wherein P≦1000 microns.

In an embodiment of the present invention, A:B=4:1, and 800 μm≦B≦1000 μm, and P≦800 μm.

In an embodiment of the present invention, any two adjacent rows of the plurality of second electrodes and the plurality of first spacings are staggered with each other in the arrangement direction.

In an embodiment of the present invention, the above solar cell further includes a plurality of heavily doped regions formed on the back side. The positions of the plurality of heavily doped regions correspond to the positions of the plurality of second electrodes respectively.

In an embodiment of the present invention, the above-mentioned solar cell further includes a connecting electrode formed on the passivation layer. The connecting electrodes are electrically connected to the plurality of second electrodes.

The invention also proposes a solar cell, which includes a silicon substrate, an emitter layer, a plurality of first electrodes, a passivation layer, and a back electrode. The silicon substrate has a light-receiving surface and a back surface opposite to the light-receiving surface. The emitter layer is formed on the light receiving surface. The plurality of first electrodes are located on the light receiving surface. The passivation layer is located on the back side and has a plurality of linear openings. Each linear opening has an extending direction. The plurality of linear openings are arranged in multiple rows along the extending direction, and arranged in multiple rows along the arrangement direction perpendicular to the extending direction. The length of each linear opening is A in the extending direction. A first interval B is maintained between any two adjacent linear openings in the same row, wherein 200 μm≦B≦1400 μm, and 2≦A/B≦5. A second pitch P is maintained between any two adjacent rows of the plurality of linear openings, wherein P≦1000 microns. The back electrode is located on the passivation layer and extends into the plurality of linear openings to contact the back.

In an embodiment of the present invention, any two adjacent rows of the plurality of linear openings and the plurality of first pitches are staggered with each other in the arrangement direction.

In an embodiment of the present invention, the above-mentioned solar cell further includes a plurality of heavily doped regions formed on the back side. The positions of the plurality of heavily doped regions correspond to the positions of the plurality of linear openings respectively.

Based on the above, the second electrode of the solar cell of the present invention adopts the arrangement of dotted line local electrodes, wherein the second electrode has an extension direction. The second electrodes are arranged in multiple columns along the extending direction and in multiple rows along the arrangement direction perpendicular to the extending direction, wherein the length of each second electrode in the extending direction is A. A first distance B is maintained between any two adjacent second electrodes in the same row, and a second distance P is maintained between any two adjacent second electrodes in the same row.

Specifically, 200 μm≦B≦1400 μm, and the length A and the first distance B conform to the relationship: 2≦A/B≦5. On the other hand, P≦1000 microns, so by adjusting the size of the first distance B to determine the value range of the length A, and while determining the value range of the length A by adjusting the size of the first distance B, change the value range of the length A The size of the two distances P can be used to obtain a better range of parameter design such as the length A, the first distance B, and the second distance P, so as to effectively improve the photoelectric conversion efficiency of the solar cell.

In order to make the above-mentioned features and advantages of the present invention more comprehensible, the following specific embodiments are described in detail together with the accompanying drawings.

Description of drawings

1 is a partial bottom view of a solar cell according to an embodiment of the present invention;

Fig. 2 is the schematic cross-sectional view of the solar cell of Fig. 1 along the line I-I;

FIG. 3 is a schematic partial cross-sectional view of a solar cell according to another embodiment of the present invention.

Explanation of reference signs

100: solar cell

130: second electrode

150: passivation layer

151: linear opening

A: Length

B: first spacing

D1: Extension direction

D2: Arrangement direction

P: second pitch

detailed description

FIG. 1 is a partial bottom view of a solar cell according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view of the solar cell in FIG. 1 along line I-I. Please refer to FIG. 1 and FIG. 2. In this embodiment, the solar cell 100 is, for example, an emitter-passivated and back-electrode solar cell, which may include a photoelectric conversion layer 110, a plurality of first electrodes 120, and a plurality of second electrodes 130. . The photoelectric conversion layer 110 may be a semiconductor stack structure of a PN junction formed by stacking a P-type semiconductor layer and an N-type semiconductor layer, or a semiconductor layer of a PIN junction formed by stacking a P-type semiconductor layer, an essential layer, and an N-type semiconductor layer. stack structure.

In detail, the photoelectric conversion layer 110 may include a silicon substrate 111 and an emitter layer 112 . The silicon substrate 111 has a light-receiving surface 111a and a back surface 111b opposite to the light-receiving surface 111a. The first electrode 120 is located on the light receiving surface 111a, and the second electrode 130 is located on the back surface 111b. On the other hand, the emitter layer 112 is formed at the light receiving surface 111a. The silicon substrate 111 is made of, for example, P-type silicon crystal, and the silicon substrate 111 is doped with a phosphorus doped layer on the light receiving surface 111 a as the emitter layer 112 . In this embodiment, the emitter layer 112 is located in the silicon substrate 111 and is close to the light receiving surface 111a. That is, the emitter layer 112 is located under the light-receiving surface 111 a of the silicon substrate 111 , but the invention is not limited thereto. For example, in other embodiments, the emitter layer can also be formed on the silicon substrate by deposition. That is, the emitter layer is located on the light-receiving surface of the silicon substrate. In another embodiment, the silicon substrate may also be made of N-type silicon crystal, and a boron doped layer is doped on the light-receiving surface of the silicon substrate as the emitter layer.

In this embodiment, the solar cell 100 further includes an anti-reflection layer 140 . The anti-reflection layer 140 is located above the light receiving surface 111 a and connected to the emitter layer 112 . The material of the anti-reflection layer 140 may include silicon nitride, silicon oxide, titanium dioxide, magnesium fluoride, or a combination thereof, and is formed on the emitter layer 112 by, for example, physical vapor deposition, chemical vapor deposition, or other suitable processes.

After the anti-reflection layer 140 is formed on the emitter layer 112, the first electrode 120 may be formed by, for example, electroplating, screen printing or physical vapor deposition. Taking electroplating or physical vapor deposition as an example to make the first electrode 120, in order to make the first electrode 120 contact the emitter layer 112, before making the first electrode 120, it is necessary to use anti-reflection methods such as laser in advance. The layer 140 forms an opening through which the first electrode 120 can pass and be accommodated. Taking the first electrode 120 made by screen printing as an example, the conductive paste formed on the anti-reflection layer 140 (the material that can be used to form the first electrode 120 ) can burn through the anti-reflection layer 140 during high-temperature sintering. Finally, the cured first electrode 120 can be in contact with the emitter layer 112 . Generally speaking, the material of the first electrode 120 can be silver, aluminum or silver-aluminum mixture, and the first electrode 120 of this embodiment is made of conductive silver paste, for example.

As shown in FIG. 2 , the solar cell 100 further includes a passivation layer 150 . A passivation layer 150 is located on the rear surface 111b. That is, the passivation layer 150 and the anti-reflection layer 140 are located on opposite sides of the photoelectric conversion layer 110 . In this embodiment, the passivation layer 150 may be composed of an amorphous silicon layer or at least one dielectric layer. Taking the passivation layer 150 formed by multiple dielectric layers as an example, the materials selected for the multiple dielectric layers may be different, partially or completely the same. Generally, the material of the dielectric layer can be silicon dioxide, silicon nitride, aluminum oxide, titanium dioxide or a combination of the above materials. The passivation layer 150 can be formed on the back surface 111b of the silicon substrate 111 by using, for example, physical vapor deposition, chemical vapor deposition or other suitable processes. After the passivation layer 150 is formed on the silicon substrate 111, a plurality of linear openings 151 arranged in parallel can be formed on the passivation layer 150 by laser drilling or drawing lines, and the plurality of linear openings 151 A portion of the rear surface 111b is exposed. Afterwards, the second electrode 130 is formed on the back surface 111 b exposed by the linear opening 151 , for example, by means of electroplating, screen printing, or physical vapor deposition. To put it another way, the second electrode 130 is correspondingly disposed in the linear opening 151 and contacts the back surface 111b of the silicon substrate 111 , wherein the material of the second electrode 130 can be silver, aluminum or a silver-aluminum mixture. In this embodiment, when the silicon substrate 111 is made of P-type silicon, for example, the material used to make the second electrode 130 is, for example, aluminum paste. Therefore, after the sintering process is completed, a plurality of P-type heavily doped regions 170 of Al-Si alloy can be formed synchronously on the back surface 111b of the silicon substrate 111 corresponding to the plurality of linear openings 151. A potential difference is generated between the plurality of heavily doped regions 170 and the silicon substrate 111 , thereby forming a plurality of local back electric field (LBSF) effects. The positions of the plurality of heavily doped regions 170 and the local back electric field are in one-to-one correspondence with the positions of the plurality of second electrodes 130 , as shown in FIG. 2 . In another embodiment, when the silicon substrate 111 is made of N-type silicon crystal, it can be doped with other related materials such as phosphorus by using the diffusion doping process, and the back surface of the silicon substrate 111 111b forms a plurality of N-type heavily doped regions distributed at intervals, and the plurality of phosphorus-doped N-type heavily doped regions will generate a potential difference with the silicon substrate, thereby forming a plurality of local back electric fields. As a result, the material of the second electrode 130 can be silver, aluminum or silver-aluminum mixture or other materials. The above-mentioned first electrode 120 or second electrode 130 can be completed using screen printing or CVD, PVD and other deposition techniques.

As shown in FIG. 1 , each second electrode 130 is, for example, a strip electrode and has an extending direction D1. The plurality of second electrodes 130 are arranged in a plurality of columns along the extending direction D1, and arranged in a plurality of rows along an arrangement direction D2 perpendicular to the extending direction D1. The length of each second electrode 130 in the extending direction D1 is A. A first distance B is maintained between any two adjacent second electrodes 130 in the same row. In this embodiment, 200 μm≦B≦1400 μm, and 2≦A/B≦5. On the other hand, any two rows of adjacent second electrodes 130 maintain a second pitch P, where P≦1000 microns.

Specifically, any two adjacent rows of the plurality of second electrodes 130 and the plurality of first intervals B are staggered with each other in the arrangement direction D2. That is, one second electrode 130 in one row corresponds to the position of one first interval B in another adjacent row. In this way, the positions of the two first distances B in different adjacent rows will not be directly adjacent to each other, so as to prevent the carriers in the silicon substrate 111 near the first distance B from moving to the second electrode 130 If the distance is too long, the problem of current collection is not smooth, which is conducive to the improvement of power generation efficiency.

In short, the second electrodes 130 are, for example, arranged in a dotted-line local electrode configuration. Since the length A and the first distance B conform to the relational expression: 2≦A/B≦5, the value range of the length A can be determined by adjusting the size of the first distance B. In addition, in this embodiment, the value range of the length A can be determined by adjusting the size of the first distance B, and at the same time, the size of the second distance P can be changed, so as to obtain parameters such as the length A, the first distance B, and the second distance P. better range of design. In this way, the photoelectric conversion efficiency of the solar cell 100 can be effectively improved.

In order to illustrate the meaning of the present invention more clearly, the parameter design proposed by the present invention can also be defined by a plurality of linear openings 151 formed on the passivation layer 150, because the second electrodes 130 respectively fill the linear openings. In the hole 151, the shapes and contours of the aforementioned two are substantially coincident.

As shown in FIG. 1 , each linear opening 151 has an extending direction D1. The plurality of linear openings 151 are arranged in a plurality of rows along the extending direction D1 and arranged in a plurality of rows along an arrangement direction D2 perpendicular to the extending direction D1. The length of each linear opening 151 in the extending direction D1 is A. As shown in FIG. A first distance B is maintained between any two adjacent linear openings 151 in the same row. 200 microns≦B≦1400 microns, and 2≦A/B≦5. A second pitch P is maintained between any two rows of adjacent linear openings 151 , wherein P≦1000 μm.

Specifically, any two adjacent rows of the plurality of linear openings 151 and the plurality of first intervals B are staggered with each other along the arrangement direction D2. That is, one linear opening 151 in one row corresponds to the position of a first distance B in another adjacent row, so as to enhance the plurality of first spacings B filled in the plurality of linear openings 151. The effect of the current collection of the two electrodes 130 . Under the layout of the aforementioned linear openings 151, the positions of the two first distances B in different adjacent rows will not directly correspond to each other, so as to avoid causing carriers near the first distance B in the silicon substrate 111 If the distance to be moved to the second electrode 130 is too far, the problem of current collection will not be smooth, which is beneficial to the improvement of power generation efficiency.

Several experimental examples will be listed below to verify the effectiveness of the present invention. The comparison basis of the following experimental data is based on electrodes in the form of traditional non-dashed lines (that is, electrodes that are purely straight lines in the direction of extension or electrodes in the form of linear openings that are single straight lines in the direction of extension), and the second The pitches P are designed to be 1000 microns and 800 microns respectively.

Experimental Example 1: Under the design conditions of the second spacing P equal to 1000 microns, and the ratio between the length A and the first spacing B being 2:1, 4:1, and 5:1, the photoelectric conversion of the solar cell 100 efficiency, and the results are shown in Table 1 below.

Table I

Experimental Example 2: The photoelectric conversion of the solar cell 100 under the design conditions that the second pitch P is equal to 800 microns, and the ratios between the length A and the first pitch B are 2:1, 4:1, and 5:1, respectively. efficiency, and the results are shown in Table 2 below.

Table II

It can be seen from Table 1 and Table 2 that when the ratio between the length A and the first distance B (ie A:B) is increased from 2:1 to 4:1, the photoelectric conversion efficiency of the solar cell 100 can be significantly improved. promote. However, when the ratio between the length A and the first distance B (ie, A:B) continues to increase to 5:1, the photoelectric conversion efficiency of the solar cell 100 is approximately restored to the level when A:B=2:1. In addition, when the first distance B is increased from 200 microns to 1600 microns, the photoelectric conversion efficiency of the solar cell 100 of Experimental Example 1 can approach the peak within the interval range of the first distance B greater than or equal to 400 microns and less than or equal to 1200 microns, while The photoelectric conversion efficiency of the solar cell 100 of Experimental Example 2 can approach the peak value within the range of the first distance B greater than or equal to 400 microns and less than or equal to 1000 microns. After the first distance B is greater than 1400 microns, the length A and the first distance B The photoelectric conversion efficiencies of the solar cells 100 with the ratios of 2:1, 4:1 and 5:1 are roughly restored to the level when the first distance B is equal to 200 micrometers. Therefore, the photoelectric conversion efficiency of the solar cell 100 can be effectively improved by designing the configuration parameters of the second electrode 130 as P≦1000 μm, 200 μm≦B≦1400 μm, and 2≦A/B≦5.

Other embodiments are listed below for illustration. It must be noted here that the following embodiments use the component numbers and partial content of the previous embodiments, wherein the same numbers are used to denote the same or similar components, and descriptions of the same technical content are omitted. For the description of omitted parts, reference may be made to the foregoing embodiments, and the following embodiments will not be repeated.

FIG. 3 is a schematic partial cross-sectional view of a solar cell according to another embodiment of the present invention. Please refer to FIG. 3 , the solar cell 100A shown in FIG. 3 is substantially similar to the solar cell 100 shown in FIG. 2 . The connection electrode 160 is electrically connected to the plurality of second electrodes 130 , wherein the connection electrode 160 and the plurality of second electrodes 130 can form a back electrode 180 . This FIG. 3 is for explaining that the connecting electrodes 160 are generally still provided on the back of FIG. 2 , so as to constitute the back electrodes 180 that can fully transmit power outward.

Since the connecting electrode 160 is, for example, fully covered on the passivation layer 150 to contact the second electrode 130 in each linear opening 151, the second electrodes 130 in each linear opening 151 can be connected to each other through the connecting electrode 160. Electrically connected, so as to collect photo-generated carriers from the silicon substrate 111 and transmit them to the outside. Generally speaking, the material of the connecting electrode 160 can be silver, aluminum or silver-aluminum mixture, and the material of the connecting electrode 160 in this embodiment is, for example, aluminum paste.

In another embodiment, the connection electrode 160 does not entirely cover the passivation layer 150 , and thus a part of the passivation layer 150 may be exposed. In other words, as long as the second electrodes 130 can be electrically connected to each other, the connection electrodes 160 can also be formed on the passivation layer 150 in strips, strips, or dendrites, so as to save material costs for making the connection electrodes 160 . In yet another embodiment, back silver electrodes (not shown in the figure) may also be formed on the back surface 111 b of the silicon substrate 111 , and the number of back silver electrodes depends on actual needs. The configuration of the back silver electrode can be fully floating only on the passivation layer 150 . That is, the back silver electrode is not in contact with the back surface 111b of the silicon substrate 111, or is in contact with the back surface 111b of the silicon substrate 111, wherein the back silver electrode is mainly used for ribbon welding.

To sum up, the second electrode of the solar cell of the present invention adopts the arrangement of dotted line local electrodes, wherein the second electrode has an extension direction. The second electrodes are arranged in multiple columns along the extending direction and in multiple rows along the arrangement direction perpendicular to the extending direction, wherein the length of each second electrode in the extending direction is A. A first distance B is maintained between any two adjacent second electrodes in the same row, and a second distance P is maintained between any two adjacent second electrodes in the same row.

Specifically, 200 μm≦B≦1400 μm, and the length A and the first distance B conform to the relationship: 2≦A/B≦5. On the other hand, P≦1000 μm. Therefore, the value range of the length A is determined by adjusting the size of the first distance B, and while the value range of the length A is determined by adjusting the size of the first distance B, the size of the second distance P is changed to obtain the length The optimal ranges of parameter design such as A, the first distance B and the second distance P can effectively improve the photoelectric conversion efficiency of the solar cell. Preferably, when P≦800 microns, the results under each set of parameters are usually better than P≦1000. In addition, when A:B=4:1, and the first spacing B is equal to 800 μm and 1000 μm, respectively, the second highest 0.16% and the highest 0.2% increase in efficiency are obtained experimentally. Therefore, when the conditions such as A:B=4:1, 800 μm≦B≦1000 μm, and P≦800 μm are satisfied, the solar cell can have a good power generation effect.

Although the present invention has been disclosed through the above-mentioned embodiments, it is not intended to limit the present invention. Any skilled person in the technical field with common knowledge may make some changes and modifications without departing from the spirit and scope of the present invention. modification, so the scope of protection of the present invention shall prevail as defined by the appended claims.

Claims (9)

1. A solar cell comprising: A silicon substrate having a light-receiving surface and a back surface opposite to the light-receiving surface; an emitter layer formed at the light-receiving surface; a plurality of first electrodes located on the light-receiving surface; a passivation layer on the back surface and having a plurality of linear openings; and A plurality of second electrodes are respectively located in the plurality of linear openings and contact the back surface, each of the second electrodes has an extension direction, and the plurality of second electrodes are arranged in a plurality of rows along the extension direction. and arranged in multiple rows along the arrangement direction perpendicular to the extension direction, wherein the length of each second electrode in the extension direction is A, A first distance B is maintained between any two adjacent second electrodes in the same row, wherein 200 microns≦B≦1400 microns, and 2≦A/B≦5, A second distance P is maintained between any two adjacent rows of the plurality of second electrodes, wherein P≦1000 microns. 2 . The solar cell according to claim 1 , wherein A:B=4:1, and 800 μm≦B≦1000 μm, and P≦800 μm. 3. The solar cell according to any one of claims 1 and 2, wherein any two adjacent rows of the plurality of second electrodes and the plurality of first spacings are mutually mutual in the arrangement direction staggered. 4. The solar cell according to any one of claims 1 and 2, further comprising: A plurality of heavily doped regions are formed on the back surface, and the positions of the plurality of heavily doped regions correspond to the positions of the plurality of second electrodes respectively. 5. The solar cell according to any one of claims 1 and 2, further comprising: A connection electrode formed on the passivation layer, the connection electrode is electrically connected to the plurality of second electrodes. 6. A solar cell comprising: A silicon substrate having a light-receiving surface and a back surface opposite to the light-receiving surface; an emitter layer formed at the light-receiving surface; a plurality of first electrodes located on the light-receiving surface; The passivation layer is located on the back surface and has a plurality of linear openings, each of the linear openings has an extending direction, and the plurality of linear openings are arranged in multiple rows along the extending direction, and Arranging in multiple rows along the arrangement direction perpendicular to the extension direction, wherein the length of each linear opening in the extension direction is A, A first distance B is maintained between any two adjacent linear openings in the same row, wherein 200 microns≦B≦1400 microns, and 2≦A/B≦5, A second pitch P is maintained between any two rows of adjacent linear openings, where P≦1000 microns; and The back electrode is located on the passivation layer and extends into the plurality of linear openings to contact the back surface. 7 . The solar cell according to claim 6 , wherein A:B=4:1, and 800 μm≦B≦1000 μm, and P≦800 μm. 8. The solar cell according to any one of claims 6 and 7, wherein any two adjacent rows of the plurality of linear openings and the plurality of first distances are mutually separated in the arrangement direction intertwined. 9. The solar cell according to any one of claims 6 and 7, further comprising: A plurality of heavily doped regions are formed on the back surface, and the positions of the plurality of heavily doped regions correspond to the positions of the plurality of linear openings respectively.