Solar cell, battery module, and photovoltaic system

Abstract

The present disclosure is applicable to the technical field of solar cells, and provides a solar cell, a battery module, and a photovoltaic system. The solar cell comprises: a silicon substrate, the silicon substrate comprising a first area and a second area, and the first area and the second area being located on a same side or two opposite sides of the silicon substrate; a P-type doped polysilicon layer, at least formed on the first area; an N-type doped polysilicon layer, at least formed on the second area; a first electrode, being in contact with the P-type doped polysilicon layer; and a second electrode, being in contact with the N-type doped polysilicon layer, wherein the bonding strength between the second electrode and the N-type doped polysilicon layer is greater than that between the first electrode and the P-type doped polysilicon layer. In the solar cell of the present disclosure, the bonding strength between the second electrode and the N-type doped polysilicon layer is increased, so that the connection between the second electrode and the N-type doped polysilicon layer is more stable and reliable, and the second electrode maintains good ohmic contact with the N-type doped polysilicon layer, thereby improving the structural stability of the cell.

Description

Solar cell, cell assembly and photovoltaic system

[0001] Cross-reference to related applications

[0002] The present disclosure refers to the Chinese Patent Application No. 202411001585.9 entitled "Solar cell, cell assembly and photovoltaic system" filed on July 24, 2024, which is incorporated by reference in its entirety into the present disclosure. TECHNICAL FIELD

[0003] The present disclosure relates to the technical field of solar cells, in particular to a solar cell, a cell assembly and a photovoltaic system. BACKGROUND

[0004] Solar cells can convert sunlight into electrical energy by using the photovoltaic effect of semiconductors. Solar cells mainly include bifacial solar cells and back contact solar cells. Among them, the front surface of the back contact solar cell completely avoids the shading of the metal grid lines compared with the bifacial solar cell, eliminates the optical loss caused by the shading of the metal grid lines, and can greatly improve the conversion efficiency of the cell.

[0005] In the related art, the silicon substrate of the bifacial solar cell is provided with an N-type doped polysilicon layer on one side, and a P-type doped polysilicon layer on the other side. The first electrode of the bifacial solar cell contacts the P-type doped polysilicon layer, and the second electrode of the bifacial solar cell contacts the N-type doped polysilicon layer. The silicon substrate of the back contact solar cell is provided with an N-type doped polysilicon layer and a P-type doped polysilicon layer alternately on the back surface. The first electrode of the back contact solar cell contacts the P-type doped polysilicon layer, and the second electrode of the back contact solar cell contacts the N-type doped polysilicon layer. The conventional solar cell usually does not consider the relationship between the bonding force of the first electrode and the P-type doped polysilicon layer and the bonding force of the second electrode and the N-type doped polysilicon layer. There is a problem that the bonding force of the second electrode and the N-type doped polysilicon layer is small, which leads to unstable connection of the second electrode and poor stability of the cell structure. SUMMARY

[0006] The present disclosure provides a solar cell, which aims to solve the problem that the related art solar cell has a small bonding force between the second electrode and the N-type doped polysilicon layer, leading to unstable connection of the second electrode and poor stability of the cell structure.

[0007] The present disclosure is implemented in this way, providing a solar cell, comprising:

[0008] A silicon substrate, the silicon substrate comprising a first region and a second region, the first region and the second region being on the same side of the silicon substrate, or the first region and the second region being on opposite sides of the silicon substrate, respectively;

[0009] A P-doped polysilicon layer formed at least on the first region;

[0010] An N-doped polysilicon layer formed at least on the second region;

[0011] A first electrode disposed on a side of the P-doped polysilicon layer facing away from the silicon substrate and in contact with the P-doped polysilicon layer;

[0012] A second electrode disposed on a side of the N-doped polysilicon layer facing away from the silicon substrate and in contact with the N-doped polysilicon layer;

[0013] The second electrode has a greater bonding force with the N-doped polysilicon layer than the first electrode has with the P-doped polysilicon layer.

[0014] In some embodiments, the first electrode and the second electrode each comprise silver, glass frit, and an organic binder, and the first electrode has a greater total content of silver and glass frit than the second electrode.

[0015] In some embodiments, the N-doped polysilicon layer has a greater roughness on a surface facing away from the silicon substrate than the P-doped polysilicon layer has on a surface facing away from the silicon substrate.

[0016] In some embodiments, the first electrode has a smaller width than the second electrode.

[0017] In some embodiments, the first electrode has a smaller depth of penetration into the P-doped polysilicon layer than the second electrode has of penetration into the N-doped polysilicon layer.

[0018] In some embodiments, the first electrode has a depth of penetration into the P-doped polysilicon layer of 10-150 nm, and the second electrode has a depth of penetration into the N-doped polysilicon layer of 20-200 nm.

[0019] In some embodiments, the first electrode has a greater height than the second electrode.

[0020] In some embodiments, the first electrode has a height to depth of penetration into the P-doped polysilicon layer ratio of 10-100.

[0021] In some embodiments, the ratio of the height of the second electrode to the depth of the second electrode into the N-type doped polysilicon layer is 5-80.

[0022] In some embodiments, the solar cell further comprises:

[0023] a first passivation layer disposed on the side of the P-type doped polysilicon layer facing away from the silicon substrate, the first electrode contacting the P-type doped polysilicon layer through the first passivation layer;

[0024] a second passivation layer disposed on the side of the N-type doped polysilicon layer facing away from the silicon substrate, the second electrode contacting the N-type doped polysilicon layer through the second passivation layer.

[0025] In some embodiments, the solar cell is a back contact solar cell, and the first region and the second region are located on the same side of the silicon substrate.

[0026] In some embodiments, the solar cell is a bifacial solar cell, and the first region and the second region are located on opposite sides of the silicon substrate, respectively.

[0027] The present disclosure also provides a battery assembly comprising the solar cell described above.

[0028] The present disclosure also provides a photovoltaic system comprising the battery assembly described above.

[0029] The solar cell provided by the present disclosure sets a first region and a second region on a silicon substrate, sets a P-type doped polysilicon layer on the first region, and sets an N-type doped polysilicon layer on the second region. A first electrode contacts the P-type doped polysilicon layer, and a second electrode contacts the N-type doped polysilicon layer. The bonding force between the second electrode and the N-type doped polysilicon layer is greater than the bonding force between the first electrode and the P-type doped polysilicon layer. Thus, the bonding force between the second electrode and the N-type doped polysilicon layer is increased, and the connection between the second electrode and the N-type doped polysilicon layer is more stable and reliable. Thus, the second electrode and the N-type doped polysilicon layer maintain a good ohmic contact, and the stability of the battery structure is improved. BRIEF DESCRIPTION OF DRAWINGS

[0030] FIG. 1 is a cross-sectional view of a solar cell according to an embodiment of the present disclosure;

[0031] FIG. 2 is a cross-sectional view of a solar cell according to another embodiment of the present disclosure.

[0032] Main element symbol explanation: 1, silicon substrate; 2, P-type doped polysilicon layer; 3, N-type doped polysilicon layer; 4, first electrode; 5, second electrode; 6, first passivation layer; 7, second passivation layer; 8, first tunneling layer; 9, second tunneling layer; 10, isolation region; 11, first region; 12, second region; 101, light-receiving surface; 102, back surface; 15, first isolation region; 16, second isolation region. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and advantages of the present disclosure clearer, the present disclosure is further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present disclosure and do not limit the present disclosure.

[0034] The solar cell provided by the embodiment of the present disclosure is provided with a first region and a second region on a silicon substrate, a P-type doped polysilicon layer is arranged on the first region, and an N-type doped polysilicon layer is arranged on the second region. The first electrode is in contact with the P-type doped polysilicon layer, the second electrode is in contact with the N-type doped polysilicon layer, and the bonding force of the second electrode and the N-type doped polysilicon layer is greater than the bonding force of the first electrode and the P-type doped polysilicon layer. Thus, the bonding force of the second electrode and the N-type doped polysilicon layer is increased, the connection between the second electrode and the N-type doped polysilicon layer is more stable and reliable, and thus the second electrode and the N-type doped polysilicon layer can maintain good ohmic contact, and the stability of the cell structure is improved.

[0035] Embodiment one

[0036] Please refer to FIG. 1, the solar cell provided by the embodiment of the present disclosure comprises:

[0037] The silicon substrate 1 comprises a first region 11 and a second region 12, and the first region 11 and the second region 12 are located on the same surface of the silicon substrate 1;

[0038] The P-type doped polysilicon layer 2 is formed at least on the first region 11;

[0039] The N-type doped polysilicon layer 3 is formed at least on the second region 12;

[0040] The first electrode 4 is arranged on the side of the P-type doped polysilicon layer 2 away from the silicon substrate 1 and is in contact with the P-type doped polysilicon layer 2;

[0041] The second electrode 5 is arranged on the side of the N-type doped polysilicon layer 3 away from the silicon substrate 1 and is in contact with the N-type doped polysilicon layer 3;

[0042] The bonding force of the second electrode 5 and the N-type doped polysilicon layer 3 is greater than the bonding force of the first electrode 4 and the P-type doped polysilicon layer 2.

[0043] In the embodiments of the present disclosure, the solar cell is a back contact solar cell, the silicon substrate 1 includes a first surface and a second surface opposite to the first surface; one of the first surface and the second surface is a light-receiving surface 101 of the solar cell, and the other is a back surface 102 of the solar cell.

[0044] In the embodiments of the present disclosure, the first region 11 and the second region 12 are both multiple, and the first region 11 and the second region 12 are arranged alternately and spaced in the back surface 102. The adjacent first region 11 and the second region 12 are provided with an isolation region 10 for isolating the first region 11 and the second region 12, and the isolation region 10 can be a groove.

[0045] The solar cell provided by the embodiments of the present disclosure is provided with the first region 11 and the first region 11 on the silicon substrate 1, the P-type doped polysilicon layer 2 is arranged in the first region 11, the N-type doped polysilicon layer 3 is arranged in the second region 12, the first electrode 4 is in contact with the P-type doped polysilicon layer 2, the second electrode 5 is in contact with the N-type doped polysilicon layer 3, and the bonding force between the second electrode 5 and the N-type doped polysilicon layer 3 is greater than the bonding force between the first electrode 4 and the P-type doped polysilicon layer 2. Under the premise that the bonding force between the first electrode 4 and the P-type doped polysilicon layer 2 remains unchanged, by increasing the bonding force between the second electrode 5 and the N-type doped polysilicon layer 3, the connection between the second electrode 5 and the N-type doped polysilicon layer 3 is more stable and reliable, the second electrode 5 is prevented from falling off, the second electrode 5 and the N-type doped polysilicon layer 3 maintain good ohmic contact, the structural stability of the solar cell is improved, and the reliability of the solar cell in use is improved.

[0046] In the embodiments of the present disclosure, when the first electrode 4 and the second electrode 5 are prepared, the slurry composition of the first electrode 4 and the second electrode 5 can be controlled, the bonding effect of the slurry used by the second electrode 5 on the N-type doped polysilicon layer 3 is better than the bonding effect of the slurry used by the first electrode 4 on the P-type doped polysilicon layer 2, so that the bonding force between the second electrode 5 and the N-type doped polysilicon layer 3 is greater than the bonding force between the first electrode 4 and the P-type doped polysilicon layer 2; or, the roughness of the N-type doped polysilicon layer 3 away from the surface of the silicon substrate 1 can be controlled to be greater than the roughness of the P-type doped polysilicon layer 2 away from the surface of the silicon substrate 1, which can also further make the bonding force between the second electrode 5 and the N-type doped polysilicon layer 3 greater than the bonding force between the first electrode 4 and the P-type doped polysilicon layer 2.

[0047] As some optional embodiments of the present disclosure, the ratio of the bonding force between the second electrode 5 and the N-type doped polysilicon layer 3 to the bonding force between the first electrode 4 and the P-type doped polysilicon layer 2 is 1.01-2.

[0048] In the embodiment, the ratio of the bonding force between the second electrode 5 and the N-type doped polysilicon layer 3 to the bonding force between the first electrode 4 and the P-type doped polysilicon layer 2 is 1.01-2, so that the bonding force between the second electrode 5 and the N-type doped polysilicon layer 3 is greater than the bonding force between the first electrode 4 and the P-type doped polysilicon layer 2, and the difference between the bonding force between the second electrode 5 and the N-type doped polysilicon layer 3 and the bonding force between the first electrode 4 and the P-type doped polysilicon layer 2 is kept appropriate, the balance between the second electrode 5 and the first electrode 4 and the corresponding doped polysilicon layer is achieved, and the design of the solar cell is optimized.

[0049] As some optional embodiments of the present disclosure, the bonding force between the first electrode 4 and the P-type doped polysilicon layer 2 is 4-6 N, and the bonding force between the second electrode 5 and the N-type doped polysilicon layer 3 is 5-8 N. Of course, the bonding force between the first electrode 4 and the P-type doped polysilicon layer 2 and the bonding force between the second electrode 5 and the N-type doped polysilicon layer 3 can be set according to actual needs.

[0050] As some embodiments of the present disclosure, the first electrode 4 and the second electrode 5 each include silver, glass frit and organic binder, and the sum of the silver and glass frit contents in the first electrode 4 is greater than the sum of the silver and glass frit contents in the second electrode 5.

[0051] In the embodiment, since the sum of the silver and glass frit contents in the first electrode 4 is greater than the sum of the silver and glass frit contents in the second electrode 5, the organic binder content in the second electrode 5 is greater than the organic binder content in the first electrode 4, the organic binder content in the slurry of the second electrode 5 is higher, the bonding effect of the slurry used by the second electrode 5 on the N-type doped polysilicon layer 3 is better than the bonding effect of the slurry used by the first electrode 4 on the P-type doped polysilicon layer 2, and the bonding force between the second electrode 5 and the N-type doped polysilicon layer 3 is greater than the bonding force between the first electrode 4 and the P-type doped polysilicon layer 2.

[0052] In the embodiment, the slurry ratio of the first electrode 4 to the second electrode 5 can be set according to actual needs, as long as the sum of the silver and glass frit contents in the first electrode 4 is greater than the sum of the silver and glass frit contents in the second electrode 5, and the organic binder content in the second electrode 5 is greater than the organic binder content in the first electrode 4. For example, the ratio of the organic binder content in the second electrode 5 to the organic binder content in the first electrode 4 can be 1.01-2.

[0053] As some embodiments of the present disclosure, the roughness of the N-type doped polysilicon layer 3 away from the surface of the silicon substrate 1 is greater than the roughness of the P-type doped polysilicon layer 2 away from the surface of the silicon substrate 1.

[0054] In the embodiment, the N-type doped polysilicon layer 3 is in contact with the second electrode 5 away from the surface of the silicon substrate 1, and the P-type doped polysilicon layer 2 is in contact with the first electrode 4 away from the surface of the silicon substrate 1. Thus, by increasing the roughness of the N-type doped polysilicon layer 3 away from the surface of the silicon substrate 1, the contact between the second electrode 5 and the N-type doped polysilicon layer 3 can be more stable, thereby increasing the bonding force between the second electrode 5 and the N-type doped polysilicon layer 3, and making the connection between the second electrode 5 and the N-type doped polysilicon layer 3 more stable and reliable, and improving the stability of the battery structure.

[0055] As some optional embodiments of the present disclosure, the N-type doped polysilicon layer 3 is provided with a plurality of counterbores (not shown) away from the surface of the silicon substrate 1 for contacting the second electrode 5.

[0056] In the embodiment, the N-type doped polysilicon layer 3 is in contact with the second electrode 5 through the plurality of counterbores, which can increase the contact area between the second electrode 5 and the N-type doped polysilicon layer 3, and further increase the bonding force between the second electrode 5 and the N-type doped polysilicon layer 3. The counterbores can be circular counterbores.

[0057] As some optional embodiments of the present disclosure, the P-type doped polysilicon layer 2 is provided with a plurality of counterbores away from the surface of the silicon substrate 1 for contacting the first electrode 4, and the distribution density of the counterbores on the surface of the N-type doped polysilicon layer 3 is greater than that of the P-type doped polysilicon layer 2.

[0058] In the embodiment, by also providing a plurality of counterbores on the surface of the P-type doped polysilicon layer 2 away from the silicon substrate 1, the contact area between the first electrode 4 and the P-type doped polysilicon layer 2 can be increased, the bonding force between the first electrode 4 and the P-type doped polysilicon layer 2 can be increased, and the stability of the first electrode 4 can be improved. Moreover, the distribution density of the counterbores on the surface of the N-type doped polysilicon layer 3 is greater than that of the P-type doped polysilicon layer 2, so that the contact area between the second electrode 5 and the N-type doped polysilicon layer 3 is larger, the bonding force between the second electrode 5 and the N-type doped polysilicon layer 3 is increased, the connection between the second electrode 5 and the N-type doped polysilicon layer 3 is more stable and reliable, and the stability of the battery structure is improved.

[0059] As some embodiments of the present disclosure, the width d1 of the first electrode 4 is less than the width d2 of the second electrode 5.

[0060] In the embodiment, since the width d1 of the first electrode 4 is less than the width d2 of the second electrode 5, it can be understood that by increasing the width of the second electrode 5, the contact area between the second electrode 5 and the N-type doped polysilicon layer 3 can be larger, the bonding force between the second electrode 5 and the N-type doped polysilicon layer 3 can be increased, the connection between the second electrode 5 and the N-type doped polysilicon layer 3 can be more stable and reliable, and the stability of the battery structure can be improved.

[0061] As some embodiments of the present disclosure, the depth d3 of the first electrode 4 into the P-type doped polysilicon layer 2 is less than the depth d4 of the second electrode 5 into the N-type doped polysilicon layer 3.

[0062] In the embodiment, since the depth d3 of the first electrode 4 into the P-type doped polysilicon layer 2 is less than the depth d4 of the second electrode 5 into the N-type doped polysilicon layer 3, by increasing the depth of the second electrode 5 into the N-type doped polysilicon layer 3, the contact area of the second electrode 5 and the N-type doped polysilicon layer 3 can be increased, thereby increasing the bonding force between the second electrode 5 and the N-type doped polysilicon layer 3, making the connection between the second electrode 5 and the N-type doped polysilicon layer 3 more stable and reliable, and improving the stability of the battery structure.

[0063] As some embodiments of the present disclosure, the depth d3 of the first electrode 4 into the P-type doped polysilicon layer 2 is 10-150 nanometers; and the depth d4 of the second electrode 5 into the N-type doped polysilicon layer 3 is 20-200 nanometers.

[0064] In the embodiment, the depth d3 of the first electrode 4 into the P-type doped polysilicon layer 2 and the depth d4 of the second electrode 5 into the N-type doped polysilicon layer 3 can be set according to actual needs, and the two can be equal or not equal. In some embodiments, the depth d3 of the first electrode 4 into the P-type doped polysilicon layer 2 is less than the depth d4 of the second electrode 5 into the N-type doped polysilicon layer 3.

[0065] In the embodiment, the depth of the first electrode 4 into the P-type doped polysilicon layer 2 can be 10 nanometers, or 25 nanometers, or 30 nanometers, or 45 nanometers, or 58 nanometers, or 60 nanometers, or 80 nanometers, or 90 nanometers, or 100 nanometers, or 120 nanometers, or 135 nanometers, or 140 nanometers, or 146 nanometers, or 150 nanometers; and the depth of the second electrode 5 into the N-type doped polysilicon layer 3 can be 20 nanometers, or 25 nanometers, or 30 nanometers, or 45 nanometers, or 58 nanometers, or 60 nanometers, or 80 nanometers, or 90 nanometers, or 100 nanometers, or 120 nanometers, or 135 nanometers, or 140 nanometers, or 146 nanometers, or 150 nanometers, or 160 nanometers, or 170 nanometers, or 180 nanometers, or 190 nanometers, or 200 nanometers.

[0066] As some embodiments of the present disclosure, the height H1 of the first electrode 4 is greater than the height H2 of the second electrode 5.

[0067] In the embodiment, the height H1 of the first electrode 4 is the distance from the surface of the silicon substrate 1 to the end of the first electrode 4 away from the P-type doped polysilicon layer 2; and the height H2 of the second electrode 5 is the distance from the surface of the silicon substrate 1 to the end of the second electrode 5 away from the N-type doped polysilicon layer 3.

[0068] In the embodiment, the height H1 of the first electrode 4 is greater than the height H2 of the second electrode 5, because the depth H1 of the first electrode 4 into the P-type doped polysilicon layer 2 is less than the depth of the second electrode 5 into the N-type doped polysilicon layer 3.

[0069] In some embodiments of the present disclosure, the ratio of the height H1 of the first electrode 4 to the depth d3 of the first electrode 4 into the P-type doped polysilicon layer 2 is 10-100.

[0070] In the embodiment, the ratio of the height H1 of the first electrode 4 to the depth d3 of the first electrode 4 into the P-type doped polysilicon layer 2 can be 10, or 15, or 20, or 25, or 30, or 32, or 40, or 45, or 50, or 60, or 70, or 85, or 90, or 100.

[0071] In some embodiments of the present disclosure, the ratio of the height H2 of the second electrode 5 to the depth d4 of the second electrode 5 into the N-type doped polysilicon layer 3 is 5-80.

[0072] In the embodiment, the ratio of the height H2 of the second electrode 5 to the depth d4 of the second electrode 5 into the N-type doped polysilicon layer 3 can be 5, or 15, or 20, or 25, or 30, or 32, or 40, or 45, or 50, or 60, or 70, or 75, or 80.

[0073] In the embodiment, the ratio of the height H2 of the second electrode 5 to the depth d4 of the second electrode 5 into the N-type doped polysilicon layer 3 is less than the ratio of the height H1 of the first electrode 4 to the depth d3 of the first electrode 4 into the P-type doped polysilicon layer 2, so that the second electrode 5 is deeper into the N-type doped polysilicon layer 3, which is beneficial to increase the contact area of the second electrode 5 and the N-type doped polysilicon layer 3.

[0074] In some embodiments of the present disclosure, the present disclosure further comprises:

[0075] The first passivation layer 6 is arranged on the side of the P-type doped polysilicon layer 2 away from the silicon substrate 1, and the first electrode 4 contacts the P-type doped polysilicon layer 2 through the first passivation layer 6.

[0076] The second passivation layer 7 is arranged on the side of the N-type doped polysilicon layer 3 away from the silicon substrate 1, and the second electrode 5 contacts the N-type doped polysilicon layer 3 through the second passivation layer 7.

[0077] In the embodiment, the first passivation layer 6 and the second passivation layer 7 are at least one or a combination of multiple kinds of the following: an aluminum oxide film layer, a silicon oxide film layer, a silicon nitride film layer, a silicon carbide film layer, and a silicon oxynitride film layer. For example, in some embodiments, the first passivation layer 6 and the second passivation layer 7 can each include an aluminum oxide film layer and a silicon nitride film layer stacked in sequence.

[0078] As some embodiments of the present disclosure, the solar cell further comprises a first tunneling layer 8 arranged between the P-type doped polysilicon layer 2 and the surface of the silicon substrate 1, and a second tunneling layer 9 arranged between the N-type doped polysilicon layer 3 and the surface of the silicon substrate 1.

[0079] In the embodiment, the first tunneling layer 8 and the second tunneling layer 9 can be silicon oxide layers. By using the tunneling passivation of the first tunneling layer 8 and the second tunneling layer 9, the cell efficiency of the solar cell can be further improved.

[0080] Embodiment Two

[0081] Please refer to FIG. 2, the solar cell provided by the embodiments of the present disclosure comprises:

[0082] The silicon substrate 1 comprises a first region 11 and a second region 12, and the first region 11 and the second region 12 are located on opposite sides of the silicon substrate 1.

[0083] The P-type doped polysilicon layer 2 is formed at least on the first region 11.

[0084] The N-type doped polysilicon layer 3 is formed at least on the second region 12.

[0085] The first electrode 4 is arranged on the side of the P-type doped polysilicon layer 2 away from the silicon substrate 1 and in contact with the P-type doped polysilicon layer 2.

[0086] The second electrode 5 is arranged on the side of the N-type doped polysilicon layer 3 away from the silicon substrate 1 and in contact with the N-type doped polysilicon layer 3.

[0087] The binding force between the second electrode 5 and the N-type doped polysilicon layer 3 is greater than the binding force between the first electrode 4 and the P-type doped polysilicon layer 2.

[0088] In the embodiments of the present disclosure, the solar cell is a bifacial solar cell, and the first region 11 and the second region 12 are located on opposite sides of the silicon substrate 1.

[0089] Specifically, the silicon substrate 1 comprises a first surface and a second surface opposite to the first surface; one of the first surface and the second surface is a light-receiving surface 101 of the solar cell, and the other is a back surface 102 of the solar cell. In FIG. 2, the first region 11 is arranged on the back surface 102 of the silicon substrate 1 in sequence and at intervals, and the second region 12 is arranged on the light-receiving surface 101 of the silicon substrate 1 in sequence and at intervals. Of course, the first region 11 can also be arranged on the light-receiving surface 101 of the silicon substrate 1 in sequence and at intervals, and the second region 12 can also be arranged on the back surface 102 of the silicon substrate 1 in sequence and at intervals.

[0090] In the embodiments of the present disclosure, the first region 11 and the second region 12 are both multiple, and the first isolation region 15 is arranged between two adjacent first regions 11, and the second isolation region 16 is arranged between two adjacent second regions 12. Of course, the first isolation region 15 can not be arranged between two adjacent first regions 11, and the second isolation region 16 can not be arranged between two adjacent second regions 12.

[0091] As some embodiments of the present disclosure, the first surface of the silicon substrate 1 is provided with a plurality of first regions 11 and a plurality of first isolation regions 15, and the first regions 11 and the first isolation regions 15 are arranged alternately; the second surface of the silicon substrate 1 has a plurality of second regions 12 and a plurality of second isolation regions 16, and the second regions 12 and the second isolation regions 16 are arranged alternately; the P-type doped polysilicon layer 2 is arranged on the first region 11 and does not cover the first isolation region 15, and the N-type doped polysilicon layer 3 is arranged on the second region 12 and does not cover the second isolation region 16.

[0092] In the embodiments, the P-type doped polysilicon layer 2 only covers the first region 11 and does not cover the first isolation region 15, and the N-type doped polysilicon layer 3 only covers the second region 12 and does not cover the second isolation region 16. The first surface of the silicon substrate 1 is not fully covered by the P-type doped polysilicon layer 2, and the second surface of the silicon substrate 1 is not fully covered by the N-type doped polysilicon layer 3, which can effectively reduce the parasitic absorption of light by the P-type doped polysilicon layer 2 and the N-type doped polysilicon layer 3, and improve the conversion efficiency.

[0093] In some other embodiments, the first region 11 can cover the first surface entirely, and the second region 12 can cover the second surface entirely.

[0094] The solar cell provided by the embodiments of the present disclosure sets the first region 11 and the first region 11 on the silicon substrate 1, sets the P-type doped polysilicon layer 2 on the first region 11, sets the N-type doped polysilicon layer 3 on the second region 12, the first electrode 4 contacts the P-type doped polysilicon layer 2, the second electrode 5 contacts the N-type doped polysilicon layer 3, and the bonding force between the second electrode 5 and the N-type doped polysilicon layer 3 is greater than the bonding force between the first electrode 4 and the P-type doped polysilicon layer 2. By increasing the bonding force between the second electrode 5 and the N-type doped polysilicon layer 3, the connection between the second electrode 5 and the N-type doped polysilicon layer 3 is more stable and reliable, the second electrode 5 is prevented from falling off, the second electrode 5 and the N-type doped polysilicon layer 3 maintain good ohmic contact, the structural stability of the solar cell is improved, and the reliability of the solar cell in use is improved.

[0095] In the embodiments of the present disclosure, when the first electrode 4 and the second electrode 5 are prepared, the slurry components of the first electrode 4 and the second electrode 5 can be controlled, so that the binding force of the slurry adopted by the second electrode 5 to the N-type doped polysilicon layer 3 is greater than the binding force of the slurry adopted by the first electrode 4 to the P-type doped polysilicon layer 2, so that the binding tension of the second electrode 5 to the N-type doped polysilicon layer 3 is greater than the binding tension of the first electrode 4 to the P-type doped polysilicon layer 2; or, the roughness of the N-type doped polysilicon layer 3 away from the surface of the silicon substrate 1 can be controlled to be greater than the roughness of the P-type doped polysilicon layer 2 away from the surface of the silicon substrate 1, so that the binding tension of the second electrode 5 to the N-type doped polysilicon layer 3 is greater than the binding tension of the first electrode 4 to the P-type doped polysilicon layer 2.

[0096] As some optional embodiments of the present disclosure, the ratio of the binding tension of the second electrode 5 to the N-type doped polysilicon layer 3 to the binding tension of the first electrode 4 to the P-type doped polysilicon layer 2 is 1.01-2.

[0097] In the embodiments, the ratio of the binding tension of the second electrode 5 to the N-type doped polysilicon layer 3 to the binding tension of the first electrode 4 to the P-type doped polysilicon layer 2 is 1.01-2, so that the binding tension of the second electrode 5 to the N-type doped polysilicon layer 3 is greater than the binding tension of the first electrode 4 to the P-type doped polysilicon layer 2, and the binding tension of the second electrode 5 to the N-type doped polysilicon layer 3 and the binding tension of the first electrode 4 to the P-type doped polysilicon layer 2 can maintain a relatively appropriate difference, so that the balance of the binding tension of the second electrode 5 and the first electrode 4 to the corresponding doped polysilicon layer is realized, and the design of the solar cell is more optimized.

[0098] As some optional embodiments of the present disclosure, the binding tension of the first electrode 4 to the P-type doped polysilicon layer 2 is 4-6 N, and the binding tension of the second electrode 5 to the N-type doped polysilicon layer 3 is 5-8 N. Of course, the binding tension of the first electrode 4 to the P-type doped polysilicon layer 2 and the binding tension of the second electrode 5 to the N-type doped polysilicon layer 3 can be set according to actual needs.

[0099] As some embodiments of the present disclosure, the first electrode 4 and the second electrode 5 each include silver, glass frit and an organic binder, and the sum of the silver and glass frit contents in the first electrode 4 is greater than the sum of the silver and glass frit contents in the second electrode 5.

[0100] In the embodiment, the silver and glass frit content of the first electrode 4 is greater than the silver and glass frit content of the second electrode 5, so the organic binder content of the second electrode 5 is greater than the organic binder content of the first electrode 4, and the slurry used by the second electrode 5 has a higher organic binder content, so the binding effect of the slurry used by the second electrode 5 on the N-type doped polysilicon layer 3 is better than the binding effect of the slurry used by the first electrode 4 on the P-type doped polysilicon layer 2, and the binding force between the second electrode 5 and the N-type doped polysilicon layer 3 is greater than the binding force between the first electrode 4 and the P-type doped polysilicon layer 2.

[0101] In the embodiment, the slurry ratio of the first electrode 4 and the second electrode 5 can be set according to actual needs, as long as the silver and glass frit content of the first electrode 4 is greater than the silver and glass frit content of the second electrode 5, and the organic binder content of the second electrode 5 is greater than the organic binder content of the first electrode 4. For example, the ratio of the organic binder content of the second electrode 5 to the organic binder content of the first electrode 4 can be 1.01-2.

[0102] As some embodiments of the present disclosure, the roughness of the surface of the N-type doped polysilicon layer 3 away from the silicon substrate 1 is greater than the roughness of the surface of the P-type doped polysilicon layer 2 away from the silicon substrate 1.

[0103] In the embodiment, the surface of the N-type doped polysilicon layer 3 away from the silicon substrate 1 is in contact with the second electrode 5, and the surface of the P-type doped polysilicon layer 2 away from the silicon substrate 1 is in contact with the first electrode 4, so by increasing the roughness of the surface of the N-type doped polysilicon layer 3 away from the silicon substrate 1, the contact between the second electrode 5 and the N-type doped polysilicon layer 3 can be more stable, thereby increasing the binding force between the second electrode 5 and the N-type doped polysilicon layer 3, and making the connection between the second electrode 5 and the N-type doped polysilicon layer 3 more stable and reliable, and improving the stability of the battery structure.

[0104] As some optional embodiments of the present disclosure, the surface of the N-type doped polysilicon layer 3 away from the silicon substrate 1 is provided with a plurality of counterbores (not shown) for contacting the second electrode 5.

[0105] In the embodiment, the N-type doped polysilicon layer 3 contacts the second electrode 5 through the plurality of counterbores, which can increase the contact area between the second electrode 5 and the N-type doped polysilicon layer 3, and further increase the binding force between the second electrode 5 and the N-type doped polysilicon layer 3. The counterbores can be circular counterbores.

[0106] As some optional embodiments of the present disclosure, the surface of the P-type doped polysilicon layer 2 away from the silicon substrate 1 is provided with a plurality of counterbores for contacting the first electrode 4, and the distribution density of the counterbores on the surface of the N-type doped polysilicon layer 3 away from the silicon substrate 1 is greater than the distribution density of the counterbores on the surface of the P-type doped polysilicon layer 2 away from the silicon substrate 1.

[0107] In the embodiment, by arranging the plurality of counterbores on the P-type doped polysilicon layer 2 away from the surface of the silicon substrate 1, the contact area of the first electrode 4 and the P-type doped polysilicon layer 2 can be increased, the binding force of the first electrode 4 and the P-type doped polysilicon layer 2 can be increased, and the stability of the first electrode 4 can be improved. Moreover, the distribution density of the counterbores on the N-type doped polysilicon layer 3 away from the surface of the silicon substrate 1 is greater than the distribution density of the counterbores on the P-type doped polysilicon layer 2 away from the surface of the silicon substrate 1, the contact area of the second electrode 5 and the N-type doped polysilicon layer 3 is greater, the binding force of the second electrode 5 and the N-type doped polysilicon layer 3 is increased, the connection between the second electrode 5 and the N-type doped polysilicon layer 3 is more stable and reliable, and the stability of the battery structure is improved.

[0108] As some embodiments of the present disclosure, the width d1 of the first electrode 4 is less than the width d2 of the second electrode 5.

[0109] In the embodiment, since the width d1 of the first electrode 4 is less than the width d2 of the second electrode 5, it can be understood that by increasing the width of the second electrode 5, the contact area of the second electrode 5 and the N-type doped polysilicon layer 3 can be greater, the binding force of the second electrode 5 and the N-type doped polysilicon layer 3 can be increased, the connection between the second electrode 5 and the N-type doped polysilicon layer 3 can be more stable and reliable, and the stability of the battery structure can be improved.

[0110] As some embodiments of the present disclosure, the depth d3 of the first electrode 4 into the P-type doped polysilicon layer 2 is less than the depth d4 of the second electrode 5 into the N-type doped polysilicon layer 3.

[0111] In the embodiment, since the depth d3 of the first electrode 4 into the P-type doped polysilicon layer 2 is less than the depth d4 of the second electrode 5 into the N-type doped polysilicon layer 3, by increasing the depth of the second electrode 5 into the N-type doped polysilicon layer 3, the contact area of the second electrode 5 and the N-type doped polysilicon layer 3 can be greater, the binding force of the second electrode 5 and the N-type doped polysilicon layer 3 can be increased, the connection between the second electrode 5 and the N-type doped polysilicon layer 3 can be more stable and reliable, and the stability of the battery structure can be improved.

[0112] As some embodiments of the present disclosure, the depth d3 of the first electrode 4 into the P-type doped polysilicon layer 2 is 10-150 nanometers, and the depth d4 of the second electrode 5 into the N-type doped polysilicon layer 3 is 20-200 nanometers.

[0113] In the embodiment, the depth d3 of the first electrode 4 into the P-type doped polysilicon layer 2 and the depth d4 of the second electrode 5 into the N-type doped polysilicon layer 3 can be set according to actual needs, and the two can be equal or not equal. In some embodiments, the depth d3 of the first electrode 4 into the P-type doped polysilicon layer 2 is less than the depth d4 of the second electrode 5 into the N-type doped polysilicon layer 3.

[0114] The depth of the first electrode 4 into the P-type doped polysilicon layer 2 can be 10 nm, or 25 nm, or 30 nm, or 45 nm, or 58 nm, or 60 nm, or 80 nm, or 90 nm, or 100 nm, or 120 nm, or 135 nm, or 140 nm, or 146 nm, or 150 nm; and the depth of the second electrode 5 into the N-type doped polysilicon layer 3 can be 20 nm, or 25 nm, or 30 nm, or 45 nm, or 58 nm, or 60 nm, or 80 nm, or 90 nm, or 100 nm, or 120 nm, or 135 nm, or 140 nm, or 146 nm, or 150 nm, or 160 nm, or 170 nm, or 180 nm, or 190 nm, or 200 nm.

[0115] As some embodiments of the present disclosure, the height H1 of the first electrode 4 is greater than the height H2 of the second electrode 5.

[0116] In the present embodiment, the height H1 of the first electrode 4 is the distance from the surface of the silicon substrate 1 to the end of the first electrode 4 away from the P-type doped polysilicon layer 2; and the height H2 of the second electrode 5 is the distance from the surface of the silicon substrate 1 to the end of the second electrode 5 away from the N-type doped polysilicon layer 3.

[0117] In the present embodiment, the depth H1 of the first electrode 4 into the P-type doped polysilicon layer 2 is less than the depth of the second electrode 5 into the N-type doped polysilicon layer 3, so the height H1 of the first electrode 4 is greater than the height H2 of the second electrode 5.

[0118] As some embodiments of the present disclosure, the ratio of the height H1 of the first electrode 4 to the depth d3 of the first electrode 4 into the P-type doped polysilicon layer 2 is 10-100.

[0119] In the present embodiment, the ratio of the height H1 of the first electrode 4 to the depth d3 of the first electrode 4 into the P-type doped polysilicon layer 2 can be 10, or 15, or 20, or 25, or 30, or 32, or 40, or 45, or 50, or 60, or 70, or 85, or 90, or 100.

[0120] As some embodiments of the present disclosure, the ratio of the height H2 of the second electrode 5 to the depth d4 of the second electrode 5 into the N-type doped polysilicon layer 3 is 5-80.

[0121] In the present embodiment, the ratio of the height H2 of the second electrode 5 to the depth d4 of the second electrode 5 into the N-type doped polysilicon layer 3 can be 5, or 15, or 20, or 25, or 30, or 32, or 40, or 45, or 50, or 60, or 70, or 75, or 80.

[0122] In the embodiment, the ratio of the height H2 of the second electrode 5 to the depth d4 of the second electrode 5 into the N-type doped polysilicon layer 3 is less than the ratio of the height H1 of the first electrode 4 to the depth d3 of the first electrode 4 into the P-type doped polysilicon layer 2, so that the second electrode 5 is deeper into the N-type doped polysilicon layer 3, which is beneficial to increase the contact area of the second electrode 5 and the N-type doped polysilicon layer 3.

[0123] As some embodiments of the present disclosure, the solar cell further comprises:

[0124] The first passivation layer 6 is arranged on the side of the P-type doped polysilicon layer 2 away from the silicon substrate 1, and the first electrode 4 contacts the P-type doped polysilicon layer 2 through the first passivation layer 6.

[0125] The second passivation layer 7 is arranged on the side of the N-type doped polysilicon layer 3 away from the silicon substrate 1, and the second electrode 5 contacts the N-type doped polysilicon layer 3 through the second passivation layer 7.

[0126] In the embodiment, the first passivation layer 6 and the second passivation layer 7 are at least one of an aluminum oxide film layer, a silicon oxide film layer, a silicon nitride film layer, a silicon carbide film layer, a silicon oxynitride film layer, or a combination of multiple thereof, for example, in some embodiments, the first passivation layer 6 and the second passivation layer 7 can each include an aluminum oxide film layer and a silicon nitride film layer stacked in sequence.

[0127] As some embodiments of the present disclosure, the solar cell further comprises a first tunneling layer 8 arranged between the P-type doped polysilicon layer 2 and the surface of the silicon substrate 1, and a second tunneling layer 9 arranged between the N-type doped polysilicon layer 3 and the surface of the silicon substrate 1.

[0128] In the embodiment, the first tunneling layer 8 and the second tunneling layer 9 can be a silicon oxide layer, and the tunneling passivation effect of the first tunneling layer 8 and the second tunneling layer 9 can further improve the cell efficiency of the solar cell.

[0129] Embodiment three

[0130] The present disclosure further provides a battery assembly, which comprises the solar cell of the above-mentioned embodiment one or embodiment two. It should be noted that the battery assembly and the solar cell have the same or similar beneficial effects, and the related parts between the two can be referred to each other, and here will not be repeated in order to avoid repetition.

[0131] Embodiment four

[0132] The present disclosure further provides a photovoltaic system, which comprises the battery assembly of the above-mentioned embodiment three. It should be noted that the photovoltaic system and the solar cell have the same or similar beneficial effects, and the related parts between the two can be referred to each other, and here will not be repeated in order to avoid repetition.

[0133] The solar cell provided by the embodiment of the present disclosure is provided with a first region and a second region on a silicon substrate, a P-type doped polysilicon layer is arranged in the first region, and an N-type doped polysilicon layer is arranged in the second region; a first electrode is in contact with the P-type doped polysilicon layer, a second electrode is in contact with the N-type doped polysilicon layer, and the bonding force between the second electrode and the N-type doped polysilicon layer is greater than the bonding force between the first electrode and the P-type doped polysilicon layer, so that the bonding force between the second electrode and the N-type doped polysilicon layer is increased, the connection between the second electrode and the N-type doped polysilicon layer is more stable and reliable, and thus the second electrode and the N-type doped polysilicon layer can maintain a good ohmic contact, and the stability of the cell structure is improved.

[0134] The above only describes preferred embodiments of the present disclosure and is not intended to limit the present disclosure. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

1. A solar cell, comprising: a silicon substrate, the silicon substrate comprising a first region and a second region, the first region and the second region being on the same side of the silicon substrate, or the first region and the second region being on opposite sides of the silicon substrate, respectively; a P-doped polysilicon layer formed on at least the first region; an N-doped polysilicon layer formed on at least the second region; a first electrode disposed on a side of the P-doped polysilicon layer away from the silicon substrate and in contact with the P-doped polysilicon layer; a second electrode disposed on a side of the N-doped polysilicon layer away from the silicon substrate and in contact with the N-doped polysilicon layer; wherein a bonding force between the second electrode and the N-doped polysilicon layer is greater than a bonding force between the first electrode and the P-doped polysilicon layer.

2. The solar cell of claim 1, wherein, the first electrode and the second electrode each comprise silver, glass frit and an organic binder, and a total content of silver and glass frit in the first electrode is greater than a total content of silver and glass frit in the second electrode.

3. The solar cell of claim 1, wherein, a roughness of a surface of the N-doped polysilicon layer away from the silicon substrate is greater than a roughness of a surface of the P-doped polysilicon layer away from the silicon substrate.

4. The solar cell of claim 1, wherein, a width of the first electrode is less than a width of the second electrode.

5. The solar cell of claim 1, wherein, a depth of the first electrode into the P-doped polysilicon layer is less than a depth of the second electrode into the N-doped polysilicon layer.

6. The solar cell of claim 5, wherein, the depth of the first electrode into the P-doped polysilicon layer is 10-150 nm, and the depth of the second electrode into the N-doped polysilicon layer is 20-200 nm.

7. The solar cell of claim 1, wherein, a height of the first electrode is greater than a height of the second electrode.

8. The solar cell of claim 1, wherein, a ratio of the height of the first electrode to the depth of the first electrode into the P-doped polysilicon layer is 10-100.

9. The solar cell of claim 1, wherein, a ratio of the height of the second electrode to the depth of the second electrode into the N-doped polysilicon layer is 5-80.

10. The solar cell of claim 1, wherein, further comprising: a first passivation layer disposed on a side of the P-doped polysilicon layer away from the silicon substrate, the first electrode being in contact with the P-doped polysilicon layer through the first passivation layer; a second passivation layer disposed on a side of the N-doped polysilicon layer away from the silicon substrate, the second electrode being in contact with the N-doped polysilicon layer through the second passivation layer.

11. The solar cell of claim 1, wherein, the solar cell is a back contact solar cell, and the first region and the second region are on the same side of the silicon substrate.

12. The solar cell of claim 1, wherein, the solar cell is a bifacial solar cell, and the first region and the second region are on opposite sides of the silicon substrate, respectively. 13.A battery assembly, comprising the solar cell according to any one of claims 1-12. 14.A photovoltaic system, comprising the battery assembly according to claim 13.

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