CN218585994U

CN218585994U - Solar cell and photovoltaic module

Info

Publication number: CN218585994U
Application number: CN202222394261.9U
Authority: CN
Inventors: 毛杰; 王钊; 郑霈霆; 杨洁; 张昕宇
Original assignee: Zhejiang Jinko Solar Co Ltd; Jinko Solar Co Ltd
Current assignee: Zhejiang Jinko Solar Co Ltd; Jinko Solar Co Ltd
Priority date: 2022-09-08
Filing date: 2022-09-08
Publication date: 2023-03-07
Anticipated expiration: 2032-09-08

Abstract

The embodiment of the utility model provides a relate to solar cell technical field, in particular to solar cell and photovoltaic module, solar cell includes: the substrate is provided with a first surface and a second surface which are opposite; the first tunneling layer and the first doped conducting layer are positioned on the preset region of the first surface and are sequentially arranged along the direction departing from the substrate, and the doping element type of the first doped conducting layer is the same as that of the substrate; the second tunneling layer and the second doped conducting layer are positioned on the second surface and are sequentially arranged in the direction departing from the substrate, and the doping element types of the second doped conducting layer are different from those of the first doped conducting layer. The embodiment of the utility model provides a be favorable to improving solar cell's photoelectric conversion efficiency.

Description

Solar cell and photovoltaic module

Technical Field

The embodiment of the utility model provides a relate to the solar cell field, in particular to solar cell and photovoltaic module.

Background

The solar cell has better photoelectric conversion capability, and in a tunnel oxide passivation contact cell (TOPCON), a tunnel oxide layer and a doped conducting layer are prepared on one surface of a substrate and are used for inhibiting the carrier recombination on the surface of the substrate in the solar cell and enhancing the passivation effect on the substrate. The tunneling oxide layer has a good chemical passivation effect, and the doped conductive layer has a good field passivation effect. In addition, in order to transmit and collect photogenerated carriers generated by the solar cell, a metal front electrode is also prepared on the surface of the substrate and is in electrical contact with the doped conductive layer, so that the metal front electrode can collect the carriers in the doped conductive layer.

However, the current solar cell has a problem of low photoelectric conversion efficiency.

SUMMERY OF THE UTILITY MODEL

The embodiment of the utility model provides a solar cell photovoltaic module has at least to do benefit to the photoelectric conversion efficiency who improves solar cell.

An embodiment of the utility model provides a solar cell, include: a substrate having opposing first and second surfaces; the first tunneling layer and the first doped conducting layer are positioned on the preset region of the first surface and are sequentially arranged along the direction departing from the substrate, and the doping element type of the first doped conducting layer is the same as that of the substrate; the second tunneling layer and the second doped conducting layer are positioned on the second surface and are sequentially arranged in the direction departing from the substrate, and the doping element type of the second doped conducting layer is different from that of the first doped conducting layer.

In addition, still include: the diffusion region is located in the substrate aligned to the preset region, the top of the diffusion region is in contact with the first tunneling layer, and the concentration of doping elements of the diffusion region is greater than that of the substrate.

In addition, the ratio of the thickness of the diffusion region to the thickness of the substrate is 2 × 10 ^-4 ～1.5×10 ^-3 。

In addition, the ratio of the thickness of the diffusion region to the thickness of the first doped conductive layer is 0.5 to 8.

In addition, the depth of the diffusion region is 50nm to 300nm.

In addition, the ratio of the width of the diffusion region to the width of the substrate is 0.01 to 0.15.

In addition, the width of the diffusion region is 20 μm to 200 μm.

In addition, the preset region corresponds to a metal pattern region, a first electrode is arranged on the metal pattern region, and the first electrode is electrically connected with the first doped conducting layer.

In addition, the first surface of the substrate is also provided with a non-metal pattern area, the first surface of the metal pattern area is provided with a first roughness, the first surface of the non-metal pattern area is provided with a second roughness, and the first roughness is greater than the second roughness.

In addition, the first surface of the metal pattern region includes: the one-dimensional size of the bottom of the first pyramid structure is larger than that of the bottom of the second pyramid structure, and the occupied area of the first surface of the first pyramid structure aligned with the metal pattern area is a first occupied ratio; the first surface of the non-metal pattern region includes: the non-metal pattern area of the third pyramid structure is aligned with the non-metal pattern area, the occupied area of the first surface of the third pyramid structure is a second occupied ratio, and the first occupied ratio is larger than the second occupied ratio.

In addition, still include: the first passivation layer covers the first surface of the substrate, and the second passivation layer covers the surface of the first doped conducting layer.

In addition, the first portion of the first passivation layer is not flush with the second portion of the first passivation layer at the top surface.

In addition, the method also comprises the following steps: a second passivation layer covering the surface of the second doped conductive layer.

In addition, the first surface of the substrate is provided with a pyramid structure, the second surface of the substrate is provided with a platform protruding structure, the height dimension of the pyramid structure is larger than that of the platform protruding structure, and the one-dimensional dimension of the bottom of the pyramid structure is smaller than that of the bottom of the platform protruding structure.

In addition, the thickness of the first doped conducting layer is not more than that of the second doped conducting layer.

In addition, the substrate is an N-type substrate.

Correspondingly, the embodiment of the utility model provides a photovoltaic module is still provided, including the battery cluster, the battery cluster is formed by connecting a plurality of above-mentioned solar cell of any item; and the cover plate is used for covering the surface of the packaging layer far away from the battery string.

The embodiment of the utility model provides a technical scheme has following advantage at least:

the embodiment of the utility model provides an among the solar cell's technical scheme, on the first surface of basement, only in the regional first tunnel layer of formation and the first doping conducting layer of predetermineeing, so, can reduce the absorption of the incident light of first doping conducting layer to shining to the first surface. In addition, the second tunneling layer and the second doped conducting layer are arranged on the whole second surface, and the concentration of the doping element of the second doped conducting layer is different from that of the doping element of the substrate, so that a PN junction is formed between the second doped conducting layer and the substrate, that is, the first doped conducting layer of the first surface and the substrate do not form a PN junction, and the problem that the formed PN junction causes serious carrier recombination in the preset region of the first surface can be avoided. In addition, the second doped conducting layer covers the second surface of the substrate, so that the area of the formed PN junction is larger, more photon-generated carriers can be generated, and the number of carrier transmission is increased. By forming the passivation contact structures on the first surface and the second surface, the problem of serious carrier recombination of the first surface and the second surface can be solved, and the double-sided rate of the solar cell is improved.

Drawings

One or more embodiments are illustrated by corresponding figures in the drawings, which are not to be construed as limiting the embodiments, unless expressly stated otherwise, and the drawings are not to scale.

Fig. 1 is a schematic cross-sectional view of a solar cell according to an embodiment of the present invention;

fig. 2 is a schematic cross-sectional view of another solar cell according to an embodiment of the present invention;

fig. 3 is a schematic cross-sectional view of another solar cell according to an embodiment of the present invention;

fig. 4 is a schematic cross-sectional view of another solar cell according to an embodiment of the present invention;

fig. 5 is a schematic structural diagram of a photovoltaic module according to another embodiment of the present invention.

Detailed Description

As is clear from the background art, the current solar cell has a problem of low photoelectric conversion efficiency.

Analysis finds that one of the reasons for the low photoelectric conversion efficiency of the current solar cell is that a diffusion process is usually adopted to convert part of the substrate into an emitter on the surface of the substrate, and the emitter has a doping element different from the substrate, so as to form a PN junction with the substrate without diffusion. However, such a structure would cause excessive carrier recombination in the metal pattern region of the substrate surface, thereby affecting the open circuit voltage and conversion efficiency of the solar cell.

The embodiment of the utility model provides a solar cell through all forming passivation contact structure on first surface and second surface, can improve the serious problem of first surface and second surface carrier complex, promotes solar cell's two-sided rate. The first tunneling layer and the first doped conducting layer are formed on the first surface of the substrate only in the preset area, and absorption of incident light irradiated to the first surface by the first doped conducting layer is reduced. The second tunneling layer and the second doped conducting layer are arranged on the whole second surface, the second doped conducting layer and the substrate form a PN junction, and the second doped conducting layer covers the second surface of the substrate, so that the area of the formed PN junction is larger, more photon-generated carriers can be generated, the number of carrier transmission is increased, and the short-circuit current and the open-circuit voltage of the solar cell are improved.

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, it will be appreciated by those of ordinary skill in the art that in the various embodiments of the invention, numerous technical details are set forth in order to provide a better understanding of the invention. However, the claimed invention can be practiced without these specific details and with various changes and modifications based on the following embodiments.

Fig. 1 is a schematic cross-sectional structure diagram of a solar cell according to an embodiment of the present invention.

Referring to fig. 1, the solar cell includes: a substrate 100, the substrate 100 having a first surface and a second surface opposite to each other; a first tunneling layer 110 and a first doped conductive layer 120 located on a predetermined region of the first surface and sequentially arranged along a direction departing from the substrate 100, wherein a doping element type of the first doped conductive layer 120 is the same as a doping element type in the substrate 100; a second tunneling layer 130 and a second doped conductive layer 140 sequentially disposed on the second surface along a direction away from the substrate 100, wherein a doping element type of the second doped conductive layer 140 is different from a doping element type of the first doped conductive layer 120.

The first tunneling layer 110 and the first doped conductive layer 120 are formed only in a predetermined region on the first surface of the substrate 100, so that the absorption of the incident light irradiated to the first surface by the first doped conductive layer 120 can be reduced. The second tunneling layer 130 and the second doped conductive layer 140 are disposed on the second surface, and the concentration of the doping element of the second doped conductive layer 140 is different from that of the substrate 100, so as to form a PN junction with the substrate 100. That is, the first doped conductive layer 120 on the first surface and the substrate 100 do not form a PN junction, so that a problem that the formed PN junction causes a serious carrier recombination in a predetermined region of the first surface can be avoided. In addition, the second tunneling layer 130 and the second doped conductive layer 140 on the second surface cover the second surface of the substrate 100 entirely, so that the area of the PN junction formed by the second doped conductive layer 140 and the substrate 100 is larger, the number of generated photogenerated carriers is larger, and the carrier concentration of the carriers in the second doped conductive layer 140 and the substrate 100 is increased.

The substrate 100 is used for receiving incident light and generating photo-generated carriers, and in some embodiments, the substrate 100 may be a silicon substrate, and a material of the silicon substrate may include at least one of monocrystalline silicon, polycrystalline silicon, amorphous silicon, or microcrystalline silicon. In other embodiments, the material of the substrate 100 may also be silicon carbide, an organic material, or a multi-component compound. The multi-element compound may include, but is not limited to, perovskite, gallium arsenide, cadmium telluride, copper indium selenide, and like materials.

Both the first surface and the second surface of the substrate 100 may be used to receive incident light or reflected light. In some embodiments, when the first surface is a front surface of the substrate 100, the second surface may be a back surface of the substrate 100; in other embodiments, when the first surface is the back surface of the substrate 100, the second surface may be the front surface of the substrate 100.

The first tunneling layer 110 and the first doped conductive layer 120 on the first surface of the substrate 100 are used to form a passivation Contact structure on the first surface of the substrate 100, the second tunneling layer 130 and the second doped conductive layer 140 on the second surface of the substrate 100 are used to form a passivation Contact structure on the second surface of the substrate 100, and passivation Contact structures are disposed on the first surface and the second surface of the substrate 100, so that the solar cell forms a dual-sided TOPCON (Tunnel Oxide passive Contact) cell. Thus, the passivation contact structures on the first surface and the second surface of the substrate 100 can reduce the recombination of carriers on both the first surface and the second surface of the substrate 100, and compared with the passivation contact structure formed on only one of the surfaces of the substrate 100, the carrier loss of the solar cell is greatly reduced, thereby increasing the open-circuit voltage and the short-circuit current of the solar cell.

The first doped conductive layer 120 and the second doped conductive layer 140 are used for performing a field passivation function, so that a carrier recombination rate at an interface of the substrate 100 is low, an open-circuit voltage, a short-circuit current and a fill factor of the solar cell are large, and a photoelectric conversion performance of the solar cell is improved. In some embodiments, the material of first and second doped

conductive layers

120 and 140 comprises at least one of silicon carbide, amorphous silicon, microcrystalline silicon, or polycrystalline silicon.

In some embodiments, the thickness of the first doped conductive layer 120 is not greater than the thickness of the second doped conductive layer 140. The first doped conductive layer 120 is disposed on the first surface of the substrate 100 aligned with the predetermined region, so that the overall volume of the first doped conductive layer 120 is smaller, thereby reducing the parasitic absorption of the first doped conductive layer 120 to incident light. The thickness of the first doped conductive layer 120 is smaller, so that the absorption of the first doped conductive layer 120 to incident light can be further reduced, the absorption and utilization of the first surface of the substrate 100 to incident light can be further increased, and the carrier concentration can be increased.

In addition, in some embodiments, the doping element concentration of the first doped conducting layer 120 is greater than that of the substrate 100, so that the fermi level difference exists between the first doped conducting layer 120 and the substrate 100, and an energy band is bent on the first surface of the substrate 100, so that the passage of minority carriers can be effectively blocked, the transmission of majority carriers cannot be influenced, and the selective mobile phone of the carriers does not further enhance the carrier collection capability. Based on this, the thickness of the first doped conductive layer 120 is smaller than the thickness of the second doped conductive layer 140, and when the amounts of the doping elements in the first doped conductive layer 120 and the second doped conductive layer 140 are the same, the volume of the first doped conductive layer 120 is smaller, so that the concentration of the doping element in the first doped conductive layer 120 is larger than that of the doping element in the first doped conductive layer 120, which can form a larger difference in fermi level between the first doped conductive layer 120 and the substrate 100, further block the passage of minority carriers, and improve the carrier transport selectivity.

In some embodiments, the predetermined region corresponds to a metal pattern region on which the first electrode 160 is disposed, and the first electrode 160 is electrically connected to the first doped conductive layer 120. The first electrode 160 is used to collect photogenerated carriers in the first doped conductive layer 120. Since the doping element type of the first doped conductive layer 120 is the same as the doping element type of the substrate 100, the metal contact recombination loss between the first electrode 160 and the first doped conductive layer 120 is reduced, and further the carrier contact recombination between the first electrode 160 and the first doped conductive layer 120 can be reduced, thereby improving the short-circuit current and the photoelectric conversion performance of the solar cell. In some embodiments, the first surface is a front surface, and the first electrode 160 is disposed on the first surface side of the substrate 100 aligned with the metal pattern region, so that the first electrode 160 can be used as a front surface electrode to reduce metal contact recombination in the first doped conductive layer 120 of the front surface. The metal pattern region is defined as an electrode region.

In some embodiments, the substrate 100 has a doping element therein, the type of the doping element is N-type or P-type, the N-type element may be a group v element such As phosphorus (P), bismuth (Bi), antimony (Sb), or arsenic (As), and the P-type element may be a group iii element such As boron (B), aluminum (Al), gallium (Ga), or indium (In). For example, when the substrate 100 is a P-type substrate 100, the type of the doped element therein is P-type. Alternatively, when the substrate 100 is an N-type substrate 100, the type of the internal doping element is N-type.

Specifically, in some embodiments, the substrate 100 is an N-type substrate 100. Accordingly, the first doped conductive layer 120 can be an N-type doped conductive layer, and the second doped conductive layer 140 can be a P-type doped conductive layer. The P-type second doped conductive layer 140 forms a PN junction with the N-type substrate 100, thereby forming a back junction. The doping element type of the first doped conducting layer 120 is the same as the doping element type of the substrate 100, so when the first electrode 160 is disposed in electrical contact with the first doped conducting layer 120 on the first surface of the substrate 100, the metal contact recombination between the first doped conducting layer 120 and the first electrode 160 is small, and thus the contact recombination of carriers can be reduced, and the transmission loss of current can be reduced.

In other embodiments, the substrate 100 may also be a P-type silicon substrate, the first doped conductive layer 120 is a P-type doped conductive layer, and the second doped conductive layer 140 is an N-type doped conductive layer.

Referring to fig. 2, in some embodiments, further comprising: and a diffusion region 150, wherein the diffusion region 150 is located in the substrate 100 aligned with the predetermined region, a top of the diffusion region 150 contacts the first tunneling layer 110, and a concentration of a doping element of the diffusion region 150 is greater than a concentration of a doping element of the substrate 100.

In addition, the diffusion region 150 is formed only in the substrate 100 where the predetermined region is aligned, the diffusion region 150 may serve as a heavily doped region, and carriers in the substrate 100 may be more easily transferred into the doped conductive layer through the diffusion region 150, i.e., the diffusion region 150 functions as a carrier transfer channel. The diffusion region 150 is not disposed in the substrate 100 aligned with the non-predetermined region, so that the carrier concentration of the first surface of the substrate 100 aligned with the non-predetermined region is not too high, and the problem of serious carrier recombination occurring on the first surface of the substrate 100 aligned with the non-predetermined region is prevented. In addition, since the diffusion region 150 is only disposed in the substrate 100 aligned with the predetermined region, carriers in the substrate 100 can be intensively transferred to the diffusion region 150 and then transferred to the first doped conductive layer 120 through the diffusion region 150, so that the carrier concentration in the first doped conductive layer 120 can be greatly increased.

In some embodiments, when the predetermined region corresponds to the metal pattern region, the diffusion region 150 is located in the substrate 100 aligned with the metal pattern region, and the first electrode is electrically contacted with the first doped conducting layer 120, so that carriers in the first doped conducting layer 120 are collected along the first electrode, thereby enhancing the current collecting capability of the first electrode.

In some embodiments, the ratio of the thickness d1 of the diffusion region 150 to the thickness d2 of the substrate 100 is set to 2 × 10 ^-4 ～1.5×10 ^-3 For example, it may be 2 × 10 ^-4 ～5×10 ^-4 、5×10 ^-4 ～8×10 ^-4 、8×10 ^-4 ～1×10 ^-3 Or 1 × 10 ^-3 ～1.5×10 ^-3 . In this range, the ratio of the thickness of the diffusion region 150 to the thickness of the substrate 100 is not too large, so that it is possible to prevent the problem that the area ratio of the diffusion region 150 in the substrate 100 is large due to the too deep depth of the diffusion region 150, which results in the too large doping concentration of the substrate 100 as a whole. On the other hand, in this range, the ratio of the thickness of the diffusion region 150 to the thickness of the substrate 100 is not too small, so that it is possible to ensure a good carrier transport effect of the diffusion region 150.

In some embodiments, the diffusion region 150 has a depth of 50nm to 300nm, and may be, for example, 50nm to 100nm, 100nm to 150nm, 150nm to 200nm, 200nm to 250nm, or 250nm to 300nm. In this range, the diffusion region 150 may form a high-low junction with the substrate 100, so that carriers located in the diffusion region 150 form a potential barrier, thereby improving carrier transport efficiency. In addition, in this range, the depth of the diffusion region 150 is not too deep, so that the problem of serious carrier recombination on the first surface of the substrate 100 due to the excessive depth of the diffusion region 150 causing the excessive doping concentration of the substrate 100 can be prevented.

In some embodiments, the ratio of the width L1 of the diffusion region 150 to the width L2 of the substrate 100 is 0.01 to 0.15, and may be, for example, 0.01 to 0.03, 0.03 to 0.05, 0.05 to 0.08, 0.08 to 0.1, 0.1 to 0.13, or 0.13 to 0.15. It is understood that, when the ratio of the width of the diffusion region 150 to the width of the substrate 100 is larger, the occupied area of the diffusion region 150 in the substrate 100 is larger. Accordingly, the ratio of the width of the diffusion region 150 to the width of the substrate 100 is set within this range, so that the width of the diffusion region 150 is not too large compared to the width of the substrate 100, thereby preventing the problem that the occupied area of the diffusion region 150 in the substrate 100 is too large due to the too large width of the diffusion region 150, which causes too many carrier recombination on the first surface of the substrate 100. On the other hand, in this range, the width of the diffusion region 150 and the width of the substrate 100 are not too large. The width of the diffusion region 150 is matched with the width of the metal pattern region, so that the substrate 100 can better absorb and utilize incident light while the diffusion region 150 is ensured to serve as a carrier transport channel. Based on this, in particular, in some embodiments, diffusion region 150 the width of diffusion region 150 is 20 μm to 200 μm, and may be, for example, 20 μm to 50 μm, 50 μm to 80 μm, 80 μm to 120 μm, 120 μm to 150 μm, or 150 μm to 200 μm. It is noted that the width of the diffusion region 150 and the width of the substrate 100 referred to herein refer to the ratio of the widths of the diffusion region 150 and the substrate 100 along the same direction.

In some embodiments, the ratio of the thickness of the diffusion region 150 to the thickness of the first doped conductive layer 120 is 0.5 to 8, and may be, for example, 0.5 to 1, 1 to 2, 2 to 3, 3 to 5, 5 to 6.5, 6.5 to 8. Within this range, the thickness of the first doped conductive layer 120 is not too small compared to the thickness of the diffusion region 150, and is even larger compared to the thickness of the diffusion region 150, so that the difference of the fermi level formed between the first doped conductive layer 120 and the diffusion region 150 is larger, and the selective collection of carriers by the first doped conductive layer 120 is enhanced. On the other hand, in this range, the thickness of the first doped conductive layer 120 is not too large compared to the thickness of the diffusion region 150, so that stress damage to the substrate 100 due to the excessive thickness of the first doped conductive layer 120 can be prevented, which increases the defect at the interface of the substrate 100 and causes more recombination centers on the first surface of the substrate 100.

Referring to fig. 3, in some embodiments, the first surface of the substrate 100 further has a non-metal pattern region, the first surface of the metal pattern region has a first roughness, and the first surface of the non-metal pattern region has a second roughness, the first roughness being greater than the second roughness. The non-metal pattern region 2 is a region of the first surface of the substrate 100 except for the metal pattern region 1. The roughness of the first surface of the substrate 100 aligned with the metal pattern region 1 is relatively large, so that the first tunneling layer 110 and the first doped conductive layer 120 formed on the first surface of the substrate 100 aligned with the metal pattern region 1 have the same or similar features as the first surface of the substrate 100 aligned with the metal pattern region 1, that is, the roughness of the first surface of the substrate 100 aligned with the metal pattern region 1 is also relatively large, so that the contact area between the first electrode 160 on the first surface of the substrate 100 aligned with the metal pattern region 1 and the first surface of the substrate 100 is relatively large, which is beneficial to reducing the contact resistance between the first electrode 160 and the first surface of the substrate 100. In other words, the width of the first electrode 160 may be set to be smaller under the condition that the contact resistance between the first electrode 160 and the first surface of the substrate 100 is kept unchanged, so that the shielding of the first electrode 160 to incident light may be reduced, and the absorption capability of the substrate 100 to the incident light may be improved.

Specifically, in some embodiments, the first surface of the metal pattern region includes: the metal pattern structure comprises a first pyramid structure 11 and a second pyramid structure 12, wherein the one-dimensional size of the bottom of the first pyramid structure 11 is larger than that of the bottom of the second pyramid structure 12, and the occupied area of the first surface, aligned with the metal pattern region, of the first pyramid structure 11 is a first occupied ratio; the first surface of the non-metal pattern region includes: the one-dimensional size of the bottom of the third pyramid structure is larger than that of the bottom of the fourth pyramid structure, the occupied area of the first surface of the third pyramid structure aligned with the nonmetal pattern area is a second occupation ratio, and the first occupation ratio is larger than the second occupation ratio. That is, the ratio of the first pyramid structures 11 with larger size on the first surface of the substrate 100 aligned with the metal pattern area is larger than the ratio of the third pyramid structures with larger size on the first surface of the substrate 100 aligned with the non-metal pattern area. In other words, the first pyramid structures 11 with larger size are larger on the first surface of the substrate 100 aligned with the metal pattern area, and the third pyramid structures with larger size are smaller on the first surface of the substrate 100 aligned with the non-metal pattern area, and the larger pyramid structures will result in larger roughness, so that the roughness of the metal pattern area is larger than that of the non-metal pattern area.

Through setting up the first surface of base 100 that aligns in the metal pattern region, the great first pyramid structure 11 of size accounts for than great, and at the first surface of base 100 that the nonmetal pattern region aligns, the great third pyramid structure of size accounts for than less, not only can realize that the roughness in metal pattern region is greater than the roughness in nonmetal pattern region, can also guarantee that no matter be metal pattern region or the first surface of base 100 that the nonmetal pattern region aligns all has better antireflection effect.

In some embodiments, further comprising: a first passivation layer 170, wherein a first portion of the first passivation layer 170 covers the first surface of the substrate 100, and a second portion of the first passivation layer 170 covers the surface of the first doped conductive layer 120. The first passivation layer 170 may perform a good passivation effect on the first surface of the substrate 100, and suppress carrier recombination on the first surface of the substrate 100. The first passivation layer 170 of the first portion is directly in contact with the first surface of the substrate 100, so that the first tunneling layer 110 and the first doped conductive layer 120 are not disposed between the first passivation layer 170 of the first portion and the substrate 100, and thus, the parasitic absorption problem of the incident light by the first doped conductive layer 120 can be reduced. And the first tunneling layer 110 and the first doped conductive layer 120 are not disposed on the first surface of the substrate 100 in consideration of the alignment of the first passivation layer 170 of the first portion. Therefore, the diffusion region 150 is not disposed in the substrate 100 aligned with the first passivation layer 170 of the first portion, so that the carrier concentration of the first surface of the substrate 100 contacting the first passivation layer 170 of the first portion is not too high, and the problem of carrier recombination occurring on the first surface of the substrate 100 of the first portion can be prevented.

In some embodiments, the first electrode 160 electrically contacts the first doped conductive layer 120 through the first passivation layer 170.

In some embodiments, the first portion of the first passivation layer 170 is not flush with the second portion of the first passivation layer 170 top surface. Specifically, the top surface of the first passivation layer 170 may be lower than the top surface of the second portion of the first passivation layer 170, so that the thickness of the first portion on the first surface of the substrate 100 is not too thick, and the first surface of the substrate 100 is prevented from being damaged by stress due to the larger thickness of the first portion, thereby causing the problem of generating more interface state defects and generating more carrier recombination centers on the first surface of the substrate 100.

In some embodiments, the first passivation layer 170 may be a single layer structure, and in other embodiments, the first passivation layer 170 may also be a multi-layer structure. In some embodiments, the material of the first passivation layer 170 may be at least one of silicon oxide, aluminum oxide, silicon nitride, or silicon oxynitride.

In some embodiments, further comprising: and a second passivation layer 180, wherein the second passivation layer 180 covers the surface of the second doped conductive layer 140. The second passivation layer 180 is used for performing a good passivation effect on the second surface of the substrate 100, reducing the defect state density of the second surface of the substrate 100, and better inhibiting carrier recombination on the second surface of the substrate 100. In some embodiments, the second passivation layer 180 may have a single-layer structure, and in other embodiments, the second passivation layer 180 may have a multi-layer structure. In some embodiments, the material of the second passivation layer 180 may be at least one of silicon oxide, aluminum oxide, silicon nitride, or silicon oxynitride.

In some embodiments, further comprising: and a second electrode 190, wherein the second electrode 190 is located on a second surface of the substrate 100, and the second electrode 190 penetrates through the second passivation layer 180 to electrically contact the second doped conductive layer 140.

Referring to fig. 4, in some embodiments, the first surface of the substrate 100 has the pyramid structures 10, the second surface of the substrate 100 has the mesa protrusion structures 13, the height dimension of the pyramid structures is greater than the height dimension of the mesa protrusion structures 13, and the one-dimensional dimension of the bottoms of the pyramid structures 10 is smaller than the one-dimensional dimension of the bottoms of the mesa protrusion structures 13. The raised platform structure 13 is a pyramid base portion of the pyramid structure, i.e., a structure remaining after removing the pyramid tip of the pyramid structure. That is, the degree of the unevenness of the pyramid structure on the first surface of the substrate 100 is greater than the degree of the unevenness of the mesa protrusion structure on the second surface of the substrate 100, so that the roughness of the first surface of the substrate 100 is greater than that of the second surface of the substrate 100. In some embodiments, since the first surface of the substrate 100 receives more incident light, in order to enhance the absorption capability of the first surface of the substrate 100 for the incident light, the first surface of the substrate 100 is provided with the pyramid structure 10, and the pyramid structure 10 has a larger specific surface area, so that the diffuse reflection effect of the incident light on the first surface of the substrate 100 can be enhanced, and the utilization rate of the first surface of the substrate 100 for the incident light is larger. Since the second surface of the substrate 100 receives less incident light, the second surface of the substrate 100 may be provided with the mesa protrusion structures 13, so that the roughness of the second surface of the substrate 100 is less than that of the first surface of the substrate 100. That is, compared to the first surface of the substrate 100, the second surface of the substrate 100 has a relatively flat profile, so that the second tunneling layer 130, the second doped conductive layer 140 and the second passivation layer 180 formed on the second surface of the substrate 100 have a flat profile, and can be uniformly formed on the second surface of the substrate 100, which is beneficial to improving the passivation effect of the second tunneling layer 130, the second doped conductive layer 140 and the second passivation layer 180 on the second surface of the substrate 100, and further reducing the defect state density of the second surface. Therefore, the efficiency of utilizing incident light rays is improved, the passivation effect on the substrate 100 is improved, and the photoelectric conversion performance of the solar cell is improved integrally.

Since the back junction is formed on the second surface of the substrate 100, the second surface of the substrate 100 is configured to have a relatively flat shape, so that the second tunneling layer 130 and the second surface of the substrate 100 can be bonded more tightly, and the photo-generated carriers generated by the PN junction can be smoothly transmitted into the substrate 100, thereby further improving the transmission efficiency of the carriers.

In some embodiments, the pyramid structure 10 may include a first pyramid structure 11 on the first surface of the substrate 100 aligned with the metal pattern region and a second pyramid structure 12 on the first surface of the substrate 100 aligned with the non-metal pattern region.

In the solar cell provided by the embodiment, the passivation contact structures are formed on the first surface and the second surface, so that the problem of serious carrier recombination of the first surface and the second surface can be solved, and the double-sided rate of the solar cell is improved. In the first surface of the substrate 100, the first tunneling layer 110 and the first doped conductive layer 120 are formed only in a predetermined region, so as to reduce absorption of the first doped conductive layer 120 to incident light irradiated to the first surface. The second tunneling layer 130 and the second doped conductive layer 140 are disposed on the entire second surface, and the second doped conductive layer 140 and the substrate 100 form a PN junction, so that the area of the formed PN junction is larger, more photon-generated carriers can be generated, the number of carrier transmissions is increased, and the short-circuit current and the open-circuit voltage of the solar cell are improved.

Correspondingly, the embodiment of the present invention provides on the other hand still a photovoltaic module, refer to fig. 5, include: a battery string formed by connecting a plurality of solar cells 101 provided in the above embodiments; the packaging layer 102, the packaging layer 102 is used for covering the surface of the battery string; and the cover plate 103 is used for covering the surface of the packaging layer 102 far away from the battery string. The solar cells 101 are electrically connected in a single piece or in multiple pieces to form a plurality of cell strings, and the plurality of cell strings are electrically connected in series and/or in parallel.

Specifically, in some embodiments, multiple strings of cells may be electrically connected therebetween by conductive straps 104. The encapsulation layer 102 covers the first surface and the second surface of the solar cell 101, and specifically, the encapsulation layer 102 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, or a polyethylene terephthalate (PET) adhesive film. In some embodiments, the cover plate 103 may be a glass cover plate, a plastic cover plate, or the like, which has a light-transmitting function. Specifically, the surface of the cover plate 103 facing the encapsulation layer 102 may be a concave-convex surface, so as to increase the utilization rate of incident light.

Although the preferred embodiments of the present invention have been described above, it should be understood that they are not intended to limit the scope of the claims, and that various changes and modifications may be made by those skilled in the art without departing from the spirit and scope of the invention.

It will be understood by those skilled in the art that the foregoing embodiments are specific examples of the invention, and that various changes in form and details may be made therein without departing from the spirit and scope of the invention in practice. Various changes and modifications may be effected therein by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A solar cell, comprising:

a substrate having opposing first and second surfaces;

the first tunneling layer and the first doped conducting layer are positioned on the preset region of the first surface and are sequentially arranged along the direction departing from the substrate, and the doping element type of the first doped conducting layer is the same as that of the substrate;

the second tunneling layer and the second doped conducting layer are positioned on the second surface and are sequentially arranged in the direction departing from the substrate, and the doping element type of the second doped conducting layer is different from that of the first doped conducting layer.

2. The solar cell of claim 1, further comprising: the diffusion region is located in the substrate aligned to the preset region, the top of the diffusion region is in contact with the first tunneling layer, and the concentration of doping elements of the diffusion region is greater than that of the substrate.

3. The solar cell of claim 2, wherein the ratio of the thickness of the diffusion region to the thickness of the substrate is 2 x 10 ^-4 ～1.5×10 ^-3 。

4. The solar cell of claim 2, wherein a ratio of a thickness of the diffusion region to a thickness of the first doped conductive layer is 0.5 to 8.

5. The solar cell according to claim 3 or 4, wherein the depth of the diffusion region is 50nm to 300nm.

6. The solar cell of claim 2, wherein a ratio of a width of the diffusion region to a width of the substrate is 0.01 to 0.15.

7. The solar cell of claim 6, wherein the diffusion region has a width of 20 μm to 200 μm.

8. The solar cell of claim 1, wherein the predetermined region corresponds to a metal pattern region on which a first electrode is disposed, the first electrode being electrically connected to the first doped conductive layer.

9. The solar cell of claim 8, wherein the substrate first surface further comprises a non-metal pattern region, wherein the first surface of the metal pattern region comprises a first roughness, wherein the first surface of the non-metal pattern region comprises a second roughness, and wherein the first roughness is greater than the second roughness.

10. The solar cell of claim 9, wherein the first surface of the metal pattern region comprises: the metal pattern structure comprises a first pyramid structure and a second pyramid structure, wherein the one-dimensional size of the bottom of the first pyramid structure is larger than that of the bottom of the second pyramid structure, and the occupied area of the first surface of the first pyramid structure, which is aligned with the metal pattern region, is a first occupation ratio;

the first surface of the non-metal pattern region includes: the structure comprises a third pyramid structure and a fourth pyramid structure, wherein the one-dimensional size of the bottom of the third pyramid structure is larger than that of the bottom of the fourth pyramid structure, the occupied area of the first surface, aligned to a non-metal pattern area, of the third pyramid structure is a second occupied ratio, and the first occupied ratio is larger than the second occupied ratio.

11. The solar cell according to claim 1 or 9, further comprising: and a first passivation layer, wherein a first part of the first passivation layer covers the first surface of the substrate, and a second part of the first passivation layer covers the surface of the first doped conductive layer.

12. The solar cell of claim 11, wherein the first portion of the first passivation layer is not flush with the second portion of the first passivation layer at a top surface.

13. The solar cell of claim 1, further comprising: a second passivation layer covering the surface of the second doped conductive layer.

14. The solar cell of claim 13, wherein the first surface of the substrate has pyramid structures, the second surface of the substrate has mesa protrusion structures, the pyramid structures have a height dimension greater than the mesa protrusion structures, and the pyramid structures have a bottom dimension smaller than the mesa protrusion structures.

15. The solar cell of claim 1, wherein the thickness of the first doped conductive layer is not greater than the thickness of the second doped conductive layer.

16. The solar cell of claim 1, wherein the substrate is an N-type substrate.

17. A photovoltaic module, comprising:

a battery string formed by connecting a plurality of the solar cells according to any one of claims 1 to 16;

an encapsulation layer for covering a surface of the battery string;

and the cover plate is used for covering the surface of the packaging layer, which is far away from the battery string.