Back-contact solar cell, cell module, and photovoltaic system

Abstract

The present disclosure is applicable to the technical field of solar cells, and provides a back-contact solar cell, a cell module, and a photovoltaic system. The back-contact solar cell comprises: a silicon substrate, wherein the back surface of the silicon substrate is provided with a P region and an N region; a first passivation contact structure, comprising a first passivation layer, a first P-type doped polysilicon layer, a first barrier layer, and a second P-type doped polysilicon layer; a second passivation contact structure, comprising a second passivation layer, a first N-type doped polysilicon layer, a second barrier layer, and a second N-type doped polysilicon layer. The doping concentration of a P-type dopant of the first P-type doped polysilicon layer is greater than the doping concentration of a P-type dopant of the second P-type doped polysilicon layer, and the doping concentration of an N-type dopant of the first N-type doped polysilicon layer is less than the doping concentration of an N-type dopant of the second N-type doped polysilicon layer. In the back-contact solar cell of the present disclosure, impurities that diffuse into the silicon substrate can be reduced, and the light transmittance of the P region can be improved, thereby improving the cell efficiency.

Description

Back contact solar cell, cell assembly and photovoltaic system

[0001] Cross-reference to related applications

[0002] The present disclosure refers to the Chinese Patent Application No. 202411087630.7 entitled "Back contact solar cell, cell assembly and photovoltaic system" filed on August 8, 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 back contact solar cell, a cell assembly and a photovoltaic system. BACKGROUND

[0004] The back contact solar cell is designed with positive / negative electrodes on the back of the cell. Compared with the bifacial solar cell, the front surface of the back contact solar cell completely avoids the shading of the metal grid lines, 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 back surface of the silicon substrate of the back contact solar cell is alternately provided with a P region and an N region, and the P region and the N region are respectively provided with a passivation contact structure; wherein the passivation contact structure of the P region is a combination of a single-layer P-type doped polysilicon layer and a single-layer passivation layer, and the passivation contact structure of the N region is also a combination of a single-layer N-type doped polysilicon layer and a single-layer passivation layer. However, since the passivation contact structures of the P region and the N region of the back contact solar cell are both combinations of a single-layer doped polysilicon layer and a single-layer passivation layer, impurities introduced in the preparation process of the back contact solar cell are easy to diffuse into the inside of the silicon substrate, resulting in poor passivation effect of the solar cell and affecting the efficiency of the solar cell. SUMMARY

[0006] The present disclosure provides a back contact solar cell, aiming to solve the problem of poor passivation effect and low cell efficiency of the related art back contact solar cell due to the passivation contact structure being a single-layer doped polysilicon layer and a single-layer passivation layer.

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

[0008] a silicon substrate, the back surface of the silicon substrate being provided with a P region and an N region;

[0009] a first passivation contact structure provided in the P region, the first passivation contact structure comprising a first passivation layer, a first P-type doped polysilicon layer, a first barrier layer and a second P-type doped polysilicon layer which are sequentially stacked on the back surface of the silicon substrate;

[0010] The second passivation contact structure is arranged in the N region and comprises a second passivation layer, a first N-type doped polysilicon layer, a second barrier layer and a second N-type doped polysilicon layer which are sequentially arranged on the back surface of the silicon substrate.

[0011] The doping concentration of the P-type dopant of the first P-type doped polysilicon layer is greater than the doping concentration of the P-type dopant of the second P-type doped polysilicon layer, and the doping concentration of the N-type dopant of the first N-type doped polysilicon layer is less than the doping concentration of the N-type dopant of the second N-type doped polysilicon layer.

[0012] In some embodiments, the ratio of the doping concentration of the P-type dopant of the first P-type doped polysilicon layer to the doping concentration of the P-type dopant of the second P-type doped polysilicon layer is 1-2 and not equal to 1.

[0013] In some embodiments, the ratio of the doping concentration of the P-type dopant of the first P-type doped polysilicon layer to the doping concentration of the P-type dopant of the second P-type doped polysilicon layer is 1.01-1.50.

[0014] In some embodiments, the doping concentration of the P-type dopant of the first P-type doped polysilicon layer is 3×10 19 -15×10 19 atoms / cm 3 .

[0015] In some embodiments, the ratio of the doping concentration of the N-type dopant of the first N-type doped polysilicon layer to the doping concentration of the N-type dopant of the second N-type doped polysilicon layer is 0.5-1.

[0016] In some embodiments, the doping concentration of the N-type dopant of the first N-type doped polysilicon layer is 0.5×10 20 -1.2×10 21 atoms / cm 3 .

[0017] In some embodiments, the semiconductor device further comprises:

[0018] The first electrode is arranged in the P region and contacts the second P-type doped polysilicon layer.

[0019] The second electrode is arranged in the N region and contacts the second N-type doped polysilicon layer.

[0020] In some embodiments, the thickness of the first P-type doped polysilicon layer is less than the thickness of the second P-type doped polysilicon layer.

[0021] In some embodiments, the thickness of the first N-type doped polysilicon layer is less than the thickness of the second N-type doped polysilicon layer.

[0022] In some embodiments, the ratio of the thickness of the second P-type doped polysilicon layer to the thickness of the first P-type doped polysilicon layer is 1-30.

[0023] In some embodiments, the ratio of the thickness of the second P-type doped polysilicon layer to the thickness of the first P-type doped polysilicon layer is 1.5-15.

[0024] In some embodiments, the sum of the thickness of the first P-type doped polysilicon layer and the thickness of the second P-type doped polysilicon layer is 80-210 nm.

[0025] In some embodiments, the sum of the thickness of the first N-type doped polysilicon layer and the thickness of the second N-type doped polysilicon layer is 60-200 nm.

[0026] In some embodiments, the sum of the thickness of the first P-type doped polysilicon layer and the thickness of the second P-type doped polysilicon layer is greater than the sum of the thickness of the first N-type doped polysilicon layer and the thickness of the second N-type doped polysilicon layer.

[0027] In some embodiments, the sum of the thickness of the first passivation layer and the thickness of the first barrier layer is 1.5-2.8 nm.

[0028] In some embodiments, the sum of the thickness of the first passivation layer and the thickness of the first barrier layer is greater than the sum of the thickness of the second passivation layer and the thickness of the second barrier layer.

[0029] In some embodiments, the thickness of the first barrier layer is greater than 0.8 nm.

[0030] In some embodiments, the ratio of the thickness of the second N-type doped polysilicon layer to the thickness of the first N-type doped polysilicon layer is 1-40.

[0031] In some embodiments, the ratio of the thickness of the second N-type doped polysilicon layer to the thickness of the first N-type doped polysilicon layer is 2-20.

[0032] In some embodiments, the first electrode enters the second P-type doped polysilicon layer and does not enter the first barrier layer, and the second electrode enters the second N-type doped polysilicon layer and does not enter the second barrier layer.

[0033] In some embodiments, the depth of the first electrode entering the second P-type doped polysilicon layer is greater than the depth of the second electrode entering the second N-type doped polysilicon layer.

[0034] In some embodiments, the total thickness of the first passivation layer, the first P-type doped polysilicon layer, the first barrier layer, and the second P-type doped polysilicon layer is greater than the total thickness of the second passivation layer, the first N-type doped polysilicon layer, the second barrier layer, and the second N-type doped polysilicon layer.

[0035] In some embodiments, the thickness of the second P-type doped polysilicon layer is greater than the thickness of the second N-type doped polysilicon layer.

[0036] In some embodiments, the thickness of the second N-type doped polysilicon layer is greater than the thickness of the first P-type doped polysilicon layer.

[0037] In some embodiments, the thickness of the first P-type doped polysilicon layer is greater than the thickness of the first N-type doped polysilicon layer.

[0038] In some embodiments, the thickness of the first passivation layer is greater than the thickness of the first barrier layer; and the thickness of the second passivation layer is greater than the thickness of the second barrier layer.

[0039] In some embodiments, the first passivation layer comprises one or a combination of boron or gallium containing silicon oxide, silicon oxynitride, silicon nitride; and the second passivation layer comprises one or a combination of phosphorus containing silicon oxide, silicon oxynitride, silicon nitride.

[0040] In some embodiments, the first barrier layer comprises one or a combination of boron or gallium containing silicon oxide, silicon oxynitride, silicon nitride, silicon carbide; and the second barrier layer comprises one or a combination of phosphorus containing silicon oxide, silicon oxynitride, silicon nitride, silicon carbide.

[0041] In some embodiments, the first passivation contact structure further comprises:

[0042] a third barrier layer disposed on a side of the second P-type doped polysilicon layer facing away from the silicon substrate.

[0043] In some embodiments, the thickness of the third barrier layer is less than the thickness of the first passivation layer.

[0044] In some embodiments, the first passivation contact structure further comprises:

[0045] a third P-type doped polysilicon layer disposed on a side of the third barrier layer facing away from the silicon substrate.

[0046] In some embodiments, the doping concentration of the P-type dopant of the second P-type doped polysilicon layer is greater than the doping concentration of the third P-type doped polysilicon layer.

[0047] In some embodiments, the second passivation contact structure further comprises:

[0048] a fourth barrier layer disposed on a side of the second N-type doped polysilicon layer facing away from the silicon substrate.

[0049] In some embodiments, the fourth barrier layer has a thickness less than that of the second passivation layer.

[0050] In some embodiments, the second passivation contact structure further comprises:

[0051] a third N-type doped polysilicon layer disposed on a side of the fourth barrier layer facing away from the silicon substrate.

[0052] In some embodiments, the third N-type doped polysilicon layer has a doping concentration of N-type dopants greater than that of the second N-type doped polysilicon layer.

[0053] The present disclosure also provides a battery assembly comprising the back contact solar cell described above.

[0054] The present disclosure also provides a photovoltaic system comprising the battery assembly described above.

[0055] The first passivation contact structure of the P region of the back contact solar cell provided by the present disclosure comprises a first passivation layer, a first P-type doped polysilicon layer, a first barrier layer, and a second P-type doped polysilicon layer stacked in sequence on the surface of the silicon substrate, and the second passivation contact structure of the N region comprises a second passivation layer, a first N-type doped polysilicon layer, a second barrier layer, and a second N-type doped polysilicon layer stacked in sequence on the surface of the silicon substrate. The first passivation contact structure uses the first passivation layer and the first barrier layer to jointly block the inward diffusion of impurities into the silicon substrate, and the second passivation contact structure uses the second passivation layer and the second barrier layer to jointly block the inward diffusion of impurities into the silicon substrate. This can significantly reduce the inward diffusion of impurities into the silicon substrate, avoid excessive impurities from diffusing into the interior of the silicon substrate, improve the passivation effect of the back contact solar cell, and thus improve the efficiency of the cell.

[0056] Furthermore, the first P-type doped polysilicon layer of the back contact solar cell of the present disclosure has a doping concentration of P-type dopants greater than that of the second P-type doped polysilicon layer, and the first N-type doped polysilicon layer has a doping concentration of N-type dopants less than that of the second N-type doped polysilicon layer. By reducing the doping concentration of P-type dopants of the second P-type doped polysilicon layer of the P region, the light transmittance of the second P-type doped polysilicon layer can be increased, thereby increasing the light transmittance of the P region, improving the utilization rate of sunlight by the back contact solar cell, and further improving the efficiency of the cell. BRIEF DESCRIPTION OF DRAWINGS

[0057] FIG. 1 is a cross-sectional view of a back contact solar cell according to an embodiment of the present disclosure;

[0058] FIG. 2 is a cross-sectional view of a back contact solar cell according to another embodiment of the present disclosure.

[0059] Main element symbol explanation: 1, silicon substrate; 2, first passivation contact structure; 3, second passivation contact structure; 4, first electrode; 5, second electrode; 11, P region; 12, N region; 13, isolation region; 101, back surface; 102, front surface; 21, first passivation layer; 22, first P-type doped polysilicon layer; 23, first barrier layer; 24, second P-type doped polysilicon layer; 25, third barrier layer; 26, third P-type doped polysilicon layer; 31, second passivation layer; 32, first N-type doped polysilicon layer; 33, second barrier layer; 34, second N-type doped polysilicon layer; 35, fourth barrier layer; 36, third N-type doped polysilicon layer. DETAILED DESCRIPTION

[0060] In order to make the purpose, technical scheme and advantages of the present disclosure clearer, the present disclosure will be 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.

[0061] The first passivation contact structure of the P region of the back contact solar cell provided by the present disclosure includes a first passivation layer, a first P-type doped polysilicon layer, a first barrier layer and a second P-type doped polysilicon layer which are sequentially stacked on the surface of the silicon substrate, and the second passivation contact structure of the N region includes a second passivation layer, a first N-type doped polysilicon layer, a second barrier layer and a second N-type doped polysilicon layer which are sequentially stacked on the surface of the silicon substrate. The first passivation contact structure blocks the impurity from diffusing into the silicon substrate by the first passivation layer and the first barrier layer, and the second passivation contact structure blocks the impurity from diffusing into the silicon substrate by the second passivation layer and the second barrier layer, so that the impurity diffusing into the silicon substrate can be reduced, the excessive impurity diffusing into the interior of the silicon substrate can be avoided, the passivation effect of the back contact solar cell can be improved, and thus the cell efficiency can be improved.

[0062] Furthermore, the doping concentration of the P-type dopant of the first P-type doped polysilicon layer of the back contact solar cell of the present disclosure is greater than the doping concentration of the P-type dopant of the second P-type doped polysilicon layer, and the doping concentration of the N-type dopant of the first N-type doped polysilicon layer is less than the doping concentration of the N-type dopant of the second N-type doped polysilicon layer. By reducing the doping concentration of the P-type dopant of the second P-type doped polysilicon layer of the P region, the light transmittance of the second P-type doped polysilicon layer can be increased, the amount of light transmitted by the P region can be increased, and thus the utilization rate of sunlight by the back contact solar cell can be improved, and the cell efficiency can be further improved.

[0063] Example one

[0064] Please refer to FIG. 1, the present embodiment provides a back contact solar cell, which comprises:

[0065] A silicon substrate 1 has a P-region 11 and an N-region 12 disposed on its back side 101.

[0066] The first passivation contact structure 2 is provided in the P region 11. The first passivation contact structure 2 includes a first passivation layer 21, a first P-type doped polysilicon layer 22, a first barrier layer 23, and a second P-type doped polysilicon layer 24, which are sequentially stacked on the back side of the silicon substrate 1.

[0067] The second passivation contact structure 3 is provided in the N region 12. The second passivation contact structure 3 includes a second passivation layer 31, a first N-type doped polysilicon layer 32, a second barrier layer 33, and a second N-type doped polysilicon layer 34, which are sequentially stacked on the back side of the silicon substrate 1.

[0068] The doping concentration of the P-type dopant in the first P-type doped polysilicon layer 22 is greater than that in the second P-type doped polysilicon layer 24, and the doping concentration of the N-type dopant in the first N-type doped polysilicon layer 32 is less than that in the second N-type doped polysilicon layer 34.

[0069] In this embodiment, the doping concentration of the P-type dopant is the average or peak value of the P-type dopant concentration, and the doping concentration of the N-type dopant is the average or peak value of the N-type dopant concentration, where the peak value is the maximum doping concentration value. In this embodiment, when comparing the doping concentrations of P-type and N-type dopant, the average doping concentration or the peak doping concentration is used for comparison. It can be understood that in some embodiments, the average doping concentration of the P-type dopant in any region of the first P-type doped polysilicon layer 22 is greater than the average doping concentration of the P-type dopant in any region of the second P-type doped polysilicon layer 24; the average doping concentration of the N-type dopant in any region of the first N-type doped polysilicon layer 32 is less than the average doping concentration of the N-type dopant in any region of the second N-type doped polysilicon layer 34.

[0070] In other embodiments, the peak doping concentration of the P-type dopant in any region of the first P-type doped polysilicon layer 22 is greater than the peak doping concentration of the P-type dopant in any region of the second P-type doped polysilicon layer 24; and the peak doping concentration of the N-type dopant in any region of the first N-type doped polysilicon layer 32 is less than the peak doping concentration of the N-type dopant in any region of the second N-type doped polysilicon layer 34.

[0071] In the embodiments of the present disclosure, the silicon substrate 1 is a P-type silicon substrate 1, and in other embodiments, the silicon substrate 1 is an N-type silicon substrate 1. The back surface 101 of the silicon substrate 1 is the back light surface of the back contact solar cell, and the front surface 102 of the silicon substrate 1 is the light surface of the back contact solar cell. The back surface 101 of the silicon substrate 1 is provided with a plurality of P regions 11 and a plurality of N regions 12, and the P regions 11 and the N regions 12 are alternately and spacedly arranged. The adjacent P regions 11 and the N regions 12 are provided with an isolation region 13. In some embodiments, the isolation region 13 is a groove, and in other embodiments, the isolation region 13 is a gap.

[0072] The first passivation contact structure 2 of the P region 11 of the back contact solar cell provided by the present disclosure includes a first passivation layer 21, a first P-type doped polysilicon layer 22, a first barrier layer 23, and a second P-type doped polysilicon layer 24 which are sequentially stacked on the surface of the silicon substrate 1. The second passivation contact structure 3 of the N region 12 includes a second passivation layer 31, a first N-type doped polysilicon layer 32, a second barrier layer 33, and a second N-type doped polysilicon layer 34 which are sequentially stacked on the surface of the silicon substrate 1. The first passivation contact structure 2 blocks the impurity from diffusing into the silicon substrate 1 by the first passivation layer 21 and the first barrier layer 23, and the second passivation contact structure 3 blocks the impurity from diffusing into the silicon substrate 1 by the second passivation layer 31 and the second barrier layer 33. Therefore, the impurity diffusion into the silicon substrate 1 can be reduced, and the excessive impurity diffusion into the silicon substrate 1 can be avoided. The passivation effect of the back contact solar cell can be obviously improved, and the cell efficiency can be improved.

[0073] In addition, the doping concentration of the P-type dopant of the first P-type doped polysilicon layer 22 is greater than the doping concentration of the P-type dopant of the second P-type doped polysilicon layer 24, and the doping concentration of the N-type dopant of the first N-type doped polysilicon layer 32 is less than the doping concentration of the N-type dopant of the second N-type doped polysilicon layer 34. Under the premise that the doping concentration of the P-type dopant of the first P-type doped polysilicon layer 22 is unchanged, the light transmittance of the second P-type doped polysilicon layer 24 of the P region 11 can be increased by reducing the doping concentration of the P-type dopant of the second P-type doped polysilicon layer 24, the light transmittance is increased, and the utilization rate of the back contact solar cell to sunlight is improved, and the cell efficiency is further improved.

[0074] In the embodiments of the present disclosure, the P-type dopant is specifically boron or gallium, and the N-type dopant is specifically phosphorus or arsenic. In other embodiments, the P-type dopant is boron, and the N-type dopant is phosphorus. In actual applications, the doping concentration of the P-type dopant is the doping concentration of the activated P-type dopant, and the doping concentration of the N-type dopant is the doping concentration of the activated N-type dopant. The doping concentrations of the activated P-type dopant and the activated N-type dopant are measured by using a spreading resistance profile (SRP) or an electrochemical capacitance-voltage method (ECV). Of course, in other embodiments, the doping concentration of the P-type dopant is the sum of the doping concentration of the activated P-type dopant and the doping concentration of the unactivated P-type dopant, and the doping concentration of the N-type dopant is the sum of the doping concentration of the activated N-type dopant and the doping concentration of the unactivated N-type dopant. The doping concentrations are measured by using secondary ion mass spectrometry (SIMS).

[0075] In actual applications, after the second P-type doped polysilicon layer 24 is prepared, high-temperature oxidation is performed on the second P-type doped polysilicon layer 24 to form an oxide layer. In some embodiments, the oxide layer is borosilicate glass. The oxide layer is used to extract part of the P-type dopant inside the second P-type doped polysilicon layer 24, and then the oxide layer is removed, so that the doping concentration of the P-type dopant of the first P-type doped polysilicon layer 22 is greater than the doping concentration of the P-type dopant of the second P-type doped polysilicon layer 24.

[0076] As some optional embodiments of the present disclosure, the first passivation layer 21, the first P-type doped polysilicon layer 22, the first barrier layer 23, and the second P-type doped polysilicon layer 24 are all doped with boron. The boron atom doping concentration of the first P-type doped polysilicon layer 22 is greater than the boron atom doping concentration of the second P-type doped polysilicon layer 24. The second passivation layer 31, the second N-type doped polysilicon layer 34, the second barrier layer 33, and the second N-type doped polysilicon layer 34 are all doped with phosphorus. The phosphorus atom doping concentration of the first N-type doped polysilicon layer 32 is less than the phosphorus atom doping concentration of the second N-type doped polysilicon layer 34.

[0077] As some embodiments of the present disclosure, the ratio of the doping concentration of the P-type dopant of the first P-type doped polysilicon layer 22 to the doping concentration of the P-type dopant of the second P-type doped polysilicon layer 24 is 1-2 and not equal to 1.

[0078] In the embodiments, the ratio of the doping concentration of the P-type dopant of the first P-type doped polysilicon layer 22 to the doping concentration of the P-type dopant of the second P-type doped polysilicon layer 24 is greater than 1 and less than 2, which can ensure good light transmission of the P region and facilitate the preparation of the first P-type doped polysilicon layer 22 and the second P-type doped polysilicon layer 24.

[0079] The ratio of the doping concentration of the P-type dopant of the first P-type doped polysilicon layer 22 to the doping concentration of the P-type dopant of the second P-type doped polysilicon layer 24 can be set according to actual needs. For example, the ratio of the doping concentration of the P-type dopant of the first P-type doped polysilicon layer 22 to the doping concentration of the P-type dopant of the second P-type doped polysilicon layer 24 can be 1.01, or 1.20, or 1.25, or 1.28, or 1.30, or 1.32, or 1.37, or 1.40, or 1.45, or 1.50, or 1.52, or 1.56, or 1.60, or 1.65, or 1.70, or 1.78, or 1.80, or 1.84, or 1.90, or 1.95, or 2.0.

[0080] As some embodiments of the present disclosure, the ratio of the doping concentration of the P-type dopant of the first P-type doped polysilicon layer 22 to the doping concentration of the P-type dopant of the second P-type doped polysilicon layer 24 is 1.01-1.50, which can further improve the light transmission effect of the P region 11 and facilitate the preparation of the first P-type doped polysilicon layer 22 and the second P-type doped polysilicon layer 24.

[0081] As some embodiments of the present disclosure, the doping concentration of the P-type dopant of the first P-type doped polysilicon layer 22 and the doping concentration of the P-type dopant of the second P-type doped polysilicon layer 24 are 3x10 19 -15x10 19 atoms / cm 3 .

[0082] In the present embodiment, the doping concentration of the P-type dopant of the first P-type doped polysilicon layer 22 and the doping concentration of the P-type dopant of the second P-type doped polysilicon layer 24 are both 3x10 19 -15x10 19 atoms / cm 3 , and only the condition that the doping concentration of the P-type dopant of the first P-type doped polysilicon layer 22 is greater than the doping concentration of the P-type dopant of the second P-type doped polysilicon layer 24 needs to be met. For example, the P-type dopant is boron, the doping concentration of the P-type dopant of the first P-type doped polysilicon layer 22 and the doping concentration of the boron atoms of the second P-type doped polysilicon layer 24 are 3x10 19 -15x10 19 atoms / cm 3 , and the doping concentration of the boron atoms of the first P-type doped polysilicon layer 22 is greater than the doping concentration of the boron atoms of the second P-type doped polysilicon layer 24.

[0083] As some embodiments of the present disclosure, the ratio of the doping concentration of the N-type dopant of the first N-type doped polysilicon layer 32 to the doping concentration of the N-type dopant of the second N-type doped polysilicon layer 34 is 0.5-1.

[0084] The ratio of the doping concentration of the N-type dopant of the first N-type doped polysilicon layer 32 to the doping concentration of the N-type dopant of the second N-type doped polysilicon layer 34 can be set according to actual needs, and the doping concentration of the N-type dopant of the first N-type doped polysilicon layer 32 is less than the doping concentration of the N-type dopant of the second N-type doped polysilicon layer 34. Of course, in some other embodiments, the doping concentration of the N-type dopant of the first N-type doped polysilicon layer 32 can also be equal to the doping concentration of the N-type dopant of the second N-type doped polysilicon layer 34. For example, the ratio of the doping concentration of the N-type dopant of the first N-type doped polysilicon layer 32 to the doping concentration of the N-type dopant of the second N-type doped polysilicon layer 34 can be 0.50, or 0.52, or 0.61, or 0.65, or 0.68, or 0.70, or 0.78, or 0.80, or 0.86, or 0.90, or 0.94, or 1.

[0085] As some embodiments of the present disclosure, the doping concentration of the N-type dopant of the first N-type doped polysilicon layer 32 to the doping concentration of the N-type dopant of the second N-type doped polysilicon layer 34 is 0.5×10 20 ~1.2×10 21 atoms / cm 3 .

[0086] In the present embodiment, the doping concentration of the N-type dopant of the first N-type doped polysilicon layer 32 to the doping concentration of the N-type dopant of the second N-type doped polysilicon layer 34 is 0.5×10 20 ~1.2×10 21 atoms / cm 3 , and the doping concentration of the N-type dopant of the first N-type doped polysilicon layer 32 is less than or equal to the doping concentration of the N-type dopant of the second N-type doped polysilicon layer 34. For example, the N-type dopant is phosphorus, and the doping concentration of the phosphorus atoms of the first N-type doped polysilicon layer 32 to the doping concentration of the phosphorus atoms of the second N-type doped polysilicon layer 34 is 0.5×10 20 ~1.2×10 21 atoms / cm 3 .

[0087] As some embodiments of the present disclosure, the present disclosure further comprises:

[0088] The first electrode 4 is arranged in the P region 11 and in contact with the second P-type doped polysilicon layer 24.

[0089] The second electrode 5 is arranged in the N region 12 and in contact with the second N-type doped polysilicon layer 34.

[0090] In the present embodiment, the first electrode 4 is in ohmic contact with the second P-type doped polysilicon layer 24, and the second electrode 5 is in ohmic contact with the second N-type doped polysilicon layer 34.

[0091] In this embodiment, the first passivation contact structure 2 of the P region 11 is provided with a first P-type doped polysilicon layer 22 and a second P-type doped polysilicon layer 24, the first P-type doped polysilicon layer 22 is used to achieve the original passivation effect, and the second P-type doped polysilicon layer 24 is used to achieve the current lateral transmission function and form an ohmic contact with the first electrode 4. The second passivation contact structure 3 of the N region 12 is provided with a first N-type doped polysilicon layer 32 and a second N-type doped polysilicon layer 34, the first N-type doped polysilicon layer 32 is used to achieve the original passivation effect, and the second N-type doped polysilicon layer 34 is used to achieve the current lateral transmission function and form an ohmic contact with the second electrode 5. Of course, in some other embodiments, the first electrode 4 is in contact with the first P-type doped polysilicon layer 22; and the second electrode 5 is in contact with the first N-type doped polysilicon layer 32.

[0092] As a preferred embodiment of the present disclosure, the first electrode 4 enters the second P-type doped polysilicon layer 24 and does not enter the first barrier layer 23, and the second electrode 5 enters the second N-type doped polysilicon layer 34 and does not enter the second barrier layer 33.

[0093] In this embodiment, the depth of the first electrode 4 entering the second P-type doped polysilicon layer 24 is less than the thickness of the second P-type doped polysilicon layer 24, the first electrode 4 only enters the second P-type doped polysilicon layer 24 and does not enter the first barrier layer 23, and the first electrode 4 only contacts the second P-type doped polysilicon layer 24, thereby avoiding damaging the first barrier layer 23, maintaining the good effect of the first barrier layer 23 in blocking the inward diffusion of impurities into the silicon substrate 1, avoiding the first electrode 4 paste entering the first barrier layer 23 and the first P-type doped polysilicon layer 22 to burn through the first passivation layer 21, avoiding the first electrode 4 directly contacting the silicon substrate 1, and improving the passivation effect of the battery.

[0094] In this embodiment, the depth of the second electrode 5 entering the second N-type doped polysilicon layer 34 is less than the thickness of the second N-type doped polysilicon layer 34, the second electrode 5 only enters the second N-type doped polysilicon layer 34 and does not enter the second barrier layer 33, and the second electrode 5 only contacts the second N-type doped polysilicon layer 34, thereby avoiding damaging the second barrier layer 33, maintaining the good effect of the second barrier layer 33 in blocking the inward diffusion of impurities into the silicon substrate 1, avoiding the second electrode 5 paste entering the second barrier layer 33 and the first N-type doped polysilicon layer 32 to burn through the second passivation layer 31, avoiding the second electrode 5 directly contacting the silicon substrate 1, and improving the passivation effect of the battery.

[0095] As some embodiments of the present disclosure, the depth of the first electrode 4 entering the second P-type doped polysilicon layer 24 is greater than the depth of the second electrode 5 entering the second N-type doped polysilicon layer 34.

[0096] In the embodiment, the depth of the first electrode 4 into the second P-type doped polysilicon layer 24 is greater than the depth of the second electrode 5 into the second N-type doped polysilicon layer 34, which can increase the contact area of the first electrode 4 with the second P-type doped polysilicon layer 24, enhance the contact effect of the first electrode 4 with the second P-type doped polysilicon layer 24, form a good ohmic contact between the second electrode 5 and the second P-type doped polysilicon layer 24, improve the conductive effect of the P region 11, and thus improve the conversion efficiency of the cell.

[0097] As some embodiments of the present disclosure, the thickness of the first P-type doped polysilicon layer 22 is less than the thickness of the second P-type doped polysilicon layer 24.

[0098] In the embodiment, the first passivation contact structure 2 of the P region 11 is provided with the first P-type doped polysilicon layer 22 and the second P-type doped polysilicon layer 24, the first P-type doped polysilicon layer 22 is used to achieve the original passivation effect, and the second P-type doped polysilicon layer 24 is used to achieve the current lateral transmission effect and the ohmic contact effect with the metal electrode, so that the thickness of the first P-type doped polysilicon layer 22 is thinned, the first P-type doped polysilicon layer 22 can achieve a good passivation effect, and the second P-type doped polysilicon layer 24 can achieve a good current lateral transmission effect and an ohmic contact effect with the metal electrode by thickening the second P-type doped polysilicon layer 24, and the doping concentration of the P-type dopant of the first P-type doped polysilicon layer 22 and the second P-type doped polysilicon layer 24 can be adjusted to adapt to the ohmic contact and passivation effect of the P region 11 of the back contact solar cell.

[0099] As some embodiments of the present disclosure, the thickness of the first N-type doped polysilicon layer 32 is less than the thickness of the second N-type doped polysilicon layer 34.

[0100] In the embodiment, the passivation contact structure of the N region 12 of the conventional back contact solar cell has only a single layer of N-type doped polysilicon layer, which plays the roles of passivation, current lateral transmission and ohmic contact with the metal electrode. In the embodiment of the present disclosure, the first passivation contact structure 2 of the N region 12 is provided with a first N-type doped polysilicon layer 32 and a second N-type doped polysilicon layer 34, the first N-type doped polysilicon layer 32 is used to realize the original passivation effect, and the second N-type doped polysilicon layer 34 is used to realize the roles of current lateral transmission and ohmic contact with the metal electrode. Therefore, the thickness of the first N-type doped polysilicon layer 32 is thinned, and the first N-type doped polysilicon layer 32 can realize good passivation effect. Since the thicker the second N-type doped polysilicon layer 34 is, the smaller the lateral transmission resistance is, the second N-type doped polysilicon layer 34 can realize good current lateral transmission and ohmic contact with the metal electrode by being thickened, and the doping concentration of the N-type dopant of the first N-type doped polysilicon layer 32 and the second N-type doped polysilicon layer 34 can be adjusted to adapt to the ohmic contact and passivation effect of the N region 12 of the back contact solar cell.

[0101] As some embodiments of the present disclosure, the ratio of the thickness of the second P-type doped polysilicon layer 24 to the thickness of the first P-type doped polysilicon layer 22 is 1-30.

[0102] In the embodiment, the ratio of the thickness of the second P-type doped polysilicon layer 24 to the thickness of the first P-type doped polysilicon layer 22 can be set according to actual needs; for example, the ratio of the thickness of the second P-type doped polysilicon layer 24 to the thickness of the first P-type doped polysilicon layer 22 can be 1, or 2, or 3, or 5, or 8, or 10, or 12, or 15, or 18, or 20, or 22, or 25, or 28, or 30.

[0103] As a preferred embodiment of the present disclosure, the ratio of the thickness of the second P-type doped polysilicon layer 24 to the thickness of the first P-type doped polysilicon layer 22 is 1.5-15.

[0104] In the embodiment, the ratio of the thickness of the second P-type doped polysilicon layer 24 to the thickness of the first P-type doped polysilicon layer 22 is 1.5-15, which ensures that the difference between the thickness of the second P-type doped polysilicon layer 24 and the thickness of the first P-type doped polysilicon layer 22 is in a more reasonable range, which can better adapt to the good ohmic contact of the second P-type doped polysilicon layer 24 and the good passivation effect of the first P-type doped polysilicon layer 22, and facilitate the preparation of the second P-type doped polysilicon layer 24 and the first P-type doped polysilicon layer 22.

[0105] As some embodiments of the present disclosure, the sum of the thickness of the first P-type doped polysilicon layer 22 and the thickness of the second P-type doped polysilicon layer 24 is greater than the sum of the thickness of the first N-type doped polysilicon layer 32 and the thickness of the second N-type doped polysilicon layer 34.

[0106] In the present embodiment, since the sum of the thickness of the first P-type doped polysilicon layer 22 and the thickness of the second P-type doped polysilicon layer 24 is greater than the sum of the thickness of the first N-type doped polysilicon layer 32 and the thickness of the second N-type doped polysilicon layer 34, the passivation effect of the P region 11 can be improved, thereby improving the cell efficiency; and the electrode of the P region 11 is also prevented from burning through the P-type doped polysilicon layer of the P region 11 to contact the silicon substrate 1, thereby improving the cell yield.

[0107] In some other embodiments, the sum of the thickness of the first P-type doped polysilicon layer 22 and the thickness of the second P-type doped polysilicon layer 24 can also be less than or equal to the sum of the thickness of the first N-type doped polysilicon layer 32 and the thickness of the second N-type doped polysilicon layer 34.

[0108] As some embodiments of the present disclosure, the sum of the thickness of the first P-type doped polysilicon layer 22 and the thickness of the second P-type doped polysilicon layer 24 is 80-210 nanometers.

[0109] In the present embodiment, the sum of the thickness of the first P-type doped polysilicon layer 22 and the thickness of the second P-type doped polysilicon layer 24 is set to be 80-210 nanometers, which can not only ensure that the first P-type doped polysilicon layer 22 and the second P-type doped polysilicon layer 24 have good ability to block the electrode from burning through, but also can block other impurities from entering the silicon substrate 1, thereby improving the passivation effect of the cell.

[0110] As some embodiments of the present disclosure, the sum of the thickness of the first N-type doped polysilicon layer 32 and the thickness of the second N-type doped polysilicon layer 34 is 60-200 nanometers.

[0111] In the present embodiment, the sum of the thickness of the first N-type doped polysilicon layer 32 and the thickness of the second N-type doped polysilicon layer 34 is set to be 60-200 nanometers, which can not only ensure that the first N-type doped polysilicon layer 32 and the second N-type doped polysilicon layer 34 have good ability to block the electrode from burning through, but also can block other impurities from entering the silicon substrate 1, thereby improving the passivation effect of the cell.

[0112] As some embodiments of the present disclosure, the ratio of the thickness of the second N-type doped polysilicon layer 34 to the thickness of the first N-type doped polysilicon layer 32 is 1-40.

[0113] In the embodiment, the ratio of the thickness of the second N-type doped polysilicon layer 34 to the thickness of the first N-type doped polysilicon layer 32 can be set according to actual needs; for example, the ratio of the thickness of the second N-type doped polysilicon layer 34 to the thickness of the first N-type doped polysilicon layer 32 can be 1, or 2, or 3, or 5, or 8, or 10, or 12, or 15, or 18, or 20, or 22, or 25, or 28, or 30, or 32, or 36, or 40.

[0114] As some embodiments of the present disclosure, the ratio of the thickness of the second N-type doped polysilicon layer 34 to the thickness of the first N-type doped polysilicon layer 32 is 2-20.

[0115] In the embodiment, the ratio of the thickness of the second N-type doped polysilicon layer 34 to the thickness of the first N-type doped polysilicon layer 32 is 2-20, which ensures that the difference between the thickness of the second N-type doped polysilicon layer 34 and the thickness of the first N-type doped polysilicon layer 32 is within a more reasonable range, which can better adapt to the good ohmic contact of the second N-type doped polysilicon layer 34 and the good passivation effect of the first N-type doped polysilicon layer 32, and facilitate the preparation of the second N-type doped polysilicon layer 34 and the first N-type doped polysilicon layer 32.

[0116] As some embodiments of the present disclosure, the thickness of the first passivation layer 21 is greater than the thickness of the first barrier layer 23; the thickness of the second passivation layer 31 is greater than the thickness of the second barrier layer 33.

[0117] In the embodiment, since the first barrier layer 23, which is relatively thinner than the first passivation layer 21, is arranged between the second P-type doped polysilicon layer 24 and the first P-type doped polysilicon layer 22, the first barrier layer 23 plays a certain mutual blocking role, so that a doping concentration difference is formed between the two P-type doped polysilicon layers, which can further improve the passivation effect of the passivation contact structure of the solar cell and improve the cell efficiency. Moreover, the thickness of the first passivation layer 21 is greater than the thickness of the first barrier layer 23, which can achieve a good passivation effect in a short time and facilitate processing.

[0118] In the embodiment, since the second barrier layer 33, which is relatively thinner than the second passivation layer 31, is arranged between the second N-type doped polysilicon layer 34 and the first N-type doped polysilicon layer 32, the second barrier layer 33 plays a certain mutual blocking role, so that a doping concentration difference is formed between the two N-type doped polysilicon layers, which can further improve the passivation effect of the passivation contact structure of the solar cell and improve the cell efficiency. Moreover, the thickness of the second passivation layer 31 is greater than the thickness of the second barrier layer 33, which can achieve a good passivation effect in a short time and facilitate processing.

[0119] As some embodiments of the present disclosure, the total thickness of the first passivation layer 21, the first P-type doped polysilicon layer 22, the first barrier layer 23 and the second P-type doped polysilicon layer 24 is greater than the total thickness of the second passivation layer 31, the first N-type doped polysilicon layer 32, the second barrier layer 33 and the second N-type doped polysilicon layer 34.

[0120] In the present embodiment, compared with the total thickness of the second passivation layer 31, the first N-type doped polysilicon layer 32, the second barrier layer 33 and the second N-type doped polysilicon layer 34, by increasing the total thickness of the first passivation layer 21, the first P-type doped polysilicon layer 22, the first barrier layer 23 and the second P-type doped polysilicon layer 24, the passivation effect of the P region 11 can be improved, and the cell efficiency is further improved.

[0121] In other embodiments, the total thickness of the first passivation layer 21, the first P-type doped polysilicon layer 22, the first barrier layer 23 and the second P-type doped polysilicon layer 24 can also be less than or equal to the total thickness of the second passivation layer 31, the first N-type doped polysilicon layer 32, the second barrier layer 33 and the second N-type doped polysilicon layer 34.

[0122] As some embodiments of the present disclosure, the thickness of the second P-type doped polysilicon layer 24 is greater than the thickness of the second N-type doped polysilicon layer 34, which facilitates controlling the total thickness of the first passivation contact structure 2 of the P region 11 to be greater than the total thickness of the second passivation contact structure 3 of the N region 12. In other embodiments, the thickness of the second P-type doped polysilicon layer 24 can also be less than the thickness of the second N-type doped polysilicon layer 34.

[0123] As some embodiments of the present disclosure, the thickness of the second N-type doped polysilicon layer 34 is greater than the thickness of the first P-type doped polysilicon layer 22, which facilitates further controlling the total thickness of the first passivation contact structure 2 of the P region 11 to be greater than the total thickness of the second passivation contact structure 3 of the N region 12.

[0124] As some embodiments of the present disclosure, the thickness of the first P-type doped polysilicon layer 22 is greater than the thickness of the first N-type doped polysilicon layer 32, which facilitates further controlling the total thickness of the first passivation contact structure 2 of the P region 11 to be greater than the total thickness of the second passivation contact structure 3 of the N region 12.

[0125] As some embodiments of the present disclosure, the sum of the thicknesses of the first passivation layer 21 and the first barrier layer 23 is 1.5-2.8 nanometers.

[0126] In the present embodiment, the sum of the thicknesses of the first passivation layer 21 and the first barrier layer 23 is set to 1.5-2.8 nanometers, which can achieve good passivation effect of the P region 11, improve the cell efficiency, and at the same time can make the P region have good contact effect, thereby improving the production yield of the back contact solar cell.

[0127] For example, the sum of the thicknesses of the first passivation layer 21 and the first barrier layer 23 can be 1.5 nm, or 1.6 nm, or 1.7 nm, or 1.8 nm, or 2.0 nm, or 2.1 nm, or 2.2 nm, or 2.3 nm, or 2.4 nm, or 2.5 nm, or 2.6 nm, or 2.7 nm, or 2.8 nm.

[0128] As some embodiments of the present disclosure, the thickness of the first barrier layer 23 is greater than 0.8 nm.

[0129] In the present embodiment, the thickness of the first barrier layer 23 is greater than 0.8 nm, which can achieve good barrier effect of the first barrier layer 23. For example, the thickness of the first barrier layer 23 can be 0.8 nm, or 0.9 nm, or 1.0 nm, or 1.2 nm, or 1.5 nm, or 2.0 nm.

[0130] As some embodiments of the present disclosure, the sum of the thicknesses of the first passivation layer 21 and the first barrier layer 23 is greater than the sum of the thicknesses of the second passivation layer 31 and the second barrier layer 33.

[0131] In the present embodiment, the sum of the thicknesses of the first passivation layer 21 and the first barrier layer 23 is set to be greater than the sum of the thicknesses of the second passivation layer 31 and the second barrier layer 33, that is, by increasing the sum of the thicknesses of the first passivation layer 21 and the first barrier layer 23, the passivation effect of the P region 11 can be improved, thereby improving the battery efficiency.

[0132] In some other embodiments, the sum of the thicknesses of the first passivation layer 21 and the first barrier layer 23 can also be less than or equal to the sum of the thicknesses of the second passivation layer 31 and the second barrier layer 33.

[0133] As some embodiments of the present disclosure, the first passivation layer 21 comprises one or a combination of boron or gallium-containing silicon oxide, boron or gallium-containing silicon oxynitride, and boron or gallium-containing silicon nitride; and the second passivation layer 31 comprises one or a combination of phosphorus-containing silicon oxide, silicon oxynitride, and silicon nitride.

[0134] In the present embodiment, the first passivation layer 21 adopts the above-mentioned material, which can achieve good barrier effect of the first passivation layer 21 and good passivation effect. The second passivation layer 31 also adopts the above-mentioned material, which can also achieve good barrier effect of the first passivation layer 21 and good passivation effect.

[0135] As some embodiments of the present disclosure, the first barrier layer 23 comprises one or a combination of boron or gallium-containing silicon oxide, silicon oxynitride, silicon nitride, and silicon carbide; and the second barrier layer 33 comprises one or a combination of phosphorus-containing silicon oxide, silicon oxynitride, silicon nitride, and silicon carbide.

[0136] In the embodiment, the first barrier layer 23 is boron or gallium containing silicon oxide, or boron or gallium containing silicon oxynitride, or boron or gallium containing silicon nitride, or boron or gallium containing silicon carbide; in other embodiments, the first barrier layer 23 is any combination of boron or gallium containing silicon oxide, silicon oxynitride, silicon nitride, silicon carbide. In some embodiments, the second barrier layer 33 is phosphorus containing silicon oxide, or phosphorus containing silicon oxynitride, or phosphorus containing silicon nitride, or phosphorus containing silicon carbide; in other embodiments, the second barrier layer 33 is any combination of phosphorus containing silicon oxide, silicon oxynitride, silicon nitride, silicon carbide.

[0137] As some embodiments of the present disclosure, the first passivation layer 21 and the second passivation layer 31 are both provided with holes (not shown), the first P-type doped polysilicon layer 22 contacts the silicon substrate 1 through the holes on the first passivation layer 21, and the first N-type doped polysilicon layer 32 contacts the silicon substrate 1 through the holes on the second passivation layer 31.

[0138] In the embodiment, the holes of the first passivation layer 21 vertically penetrate the first passivation layer 21, and the holes of the second passivation layer 31 vertically penetrate the second passivation layer 31. The silicon substrate 1 is further provided with an inner extension layer, the first P-type doped polysilicon layer 22 contacts the inner extension layer inside the silicon substrate 1 through the holes on the first passivation layer 21, and the first N-type doped polysilicon layer 32 contacts the inner extension layer inside the silicon substrate 1 through the holes on the second passivation layer 31. The first P-type doped polysilicon layer 22 contacts the silicon substrate 1 through the holes on the first passivation layer 21, and the first N-type doped polysilicon layer 32 contacts the silicon substrate 1 through the holes on the second passivation layer 31, which is conducive to reducing current loss and improving cell conversion efficiency.

[0139] In some embodiments, the holes of the first passivation layer 21 and the second passivation layer 31 are prepared by chemical etching, dry etching or thermal diffusion impact, etc., which are prepared according to actual needs, and are not specifically limited here. When the first passivation layer 21 and the second passivation layer 31 are observed from the top view angle, the first passivation layer 21 and the second passivation layer 31 present a porous structure, and when the first passivation layer 21 and the second passivation layer 31 are observed from the cross-sectional view angle, the first passivation layer 21 and the second passivation layer 31 show a multi-channel structure.

[0140] As some embodiments of the present disclosure, the first passivation layer 21 and the first barrier layer 23 are both provided with holes, and the hole density of the first passivation layer 21 is smaller than that of the first barrier layer 23.

[0141] In the embodiment, the first passivation layer 21 has a smaller hole density than the first barrier layer 23. In other words, the first passivation layer 21 has a smaller number of holes per unit area than the first barrier layer 23. As the first passivation layer 21 has a smaller hole density than the first barrier layer 23, the conductive performance of the first passivation layer 21 and the first barrier layer 23 is sequentially enhanced, which is conducive to improving the gettering effect of the silicon substrate 1 and the battery efficiency.

[0142] In some embodiments of the present disclosure, the first passivation layer 21 and the first barrier layer 23 are both provided with holes, and the first passivation layer 21 has a smaller average hole diameter than the first barrier layer 23.

[0143] In some embodiments, the holes of the first passivation layer 21 have the same diameter, and in other embodiments, the holes of the first passivation layer 21 have different diameters. Similarly, in some embodiments, the holes of the first barrier layer 23 have the same diameter, and in other embodiments, the holes of the first barrier layer 23 have different diameters. The average hole diameter of the first passivation layer 21 can be understood as the average hole diameter of all holes of the first passivation layer 21, and the average hole diameter of the first barrier layer 23 can be understood as the average hole diameter of all holes of the first barrier layer 23. By setting the average hole diameter of the first passivation layer 21 to be smaller than the average hole diameter of the first barrier layer 23, the passivation effect of the first passivation layer 21 on the back surface of the silicon substrate 1 is improved, which is conducive to improving the battery efficiency.

[0144] In some embodiments of the present disclosure, the second passivation layer 31 and the second barrier layer 33 are both provided with holes, and the second passivation layer 31 has a smaller hole density than the second barrier layer 33.

[0145] In the embodiment, the second passivation layer 31 has a smaller hole density than the second barrier layer 33. In other words, the second passivation layer 31 has a smaller number of holes per unit area than the second barrier layer 33. As the second passivation layer 31 has a smaller hole density than the second barrier layer 33, the conductive performance of the second passivation layer 31 and the second barrier layer 33 is sequentially enhanced, which is conducive to improving the gettering effect of the silicon substrate 1 and the battery efficiency.

[0146] In some embodiments of the present disclosure, the second passivation layer 31 and the second barrier layer 33 are both provided with holes, and the second passivation layer 31 has a smaller average hole diameter than the second barrier layer 33.

[0147] In some embodiments, the apertures of the second passivation layer 31 are of equal diameter, and in other embodiments, the apertures of the second passivation layer 31 are of unequal diameter; similarly, in some embodiments, the apertures of the second barrier layer 33 are of equal diameter, and in other embodiments, the apertures of the second barrier layer 33 are of unequal diameter. The average aperture diameter of the second passivation layer 31 can be understood as the average diameter of all the apertures of the second passivation layer 31; the average aperture diameter of the second barrier layer 33 can be understood as the average diameter of all the apertures of the second barrier layer 33. By setting the average aperture diameter of the second passivation layer 31 to be smaller than the average aperture diameter of the second barrier layer 33, the passivation effect of the second passivation layer 31 on the back surface of the silicon substrate 1 is improved, and the battery efficiency is improved.

[0148] As some embodiments of the present disclosure, the doping concentration of the P-type dopant of the first passivation layer 21 is smaller than the doping concentration of the P-type dopant of the first barrier layer 23, which is conducive to improving the ability of the first barrier layer 23 to block impurities from entering the silicon substrate 1. In other embodiments, the doping concentration of the first passivation layer 21 is greater than or equal to the doping concentration of the first barrier layer 23.

[0149] In other embodiments, the back surface of the second N-type doped polysilicon layer 34 further has a back surface passivation layer, such as a silicon nitride layer, superimposed on the surface away from the silicon substrate 1, to further improve the passivation effect of the battery.

[0150] Embodiment Two

[0151] Please refer to FIG. 2, on the basis of the first embodiment, the first passivation contact structure 2 further comprises:

[0152] The third barrier layer 25 is arranged on the surface of the second P-type doped polysilicon layer 24 away from the silicon substrate 1.

[0153] In this embodiment, the first electrode 4 passes through the third barrier layer 25 and contacts the second P-type doped polysilicon layer 24. By arranging the third barrier layer 25 on the surface of the second P-type doped polysilicon layer 24 away from the silicon substrate 1, the third barrier layer 25 can be used to block the inward diffusion of impurities into the silicon substrate 1, further block the inward diffusion of impurities into the silicon substrate 1, and the third barrier layer 25 can also be used to block the loss of doped atoms from the second P-type doped polysilicon layer 24, further improving the passivation effect of the battery.

[0154] As some embodiments of the present disclosure, the thickness of the third barrier layer 25 is smaller than the thickness of the first passivation layer 21.

[0155] In this embodiment, the thickness of the third barrier layer 25 is smaller than the thickness of the first passivation layer 21, so that the third barrier layer 25 is thicker than the first passivation layer 21, which can improve the passivation effect of the first passivation layer 21.

[0156] As some embodiments of the present disclosure, further comprising:

[0157] A third P-type doped polysilicon layer 26 is disposed on a side of the third barrier layer 25 facing away from the silicon substrate 1.

[0158] In the present embodiment, by adding the third P-type doped polysilicon layer 26, the passivation effect of the P region 11 can be further enhanced by the third P-type doped polysilicon layer 26. In some embodiments, the first electrode 4 directly contacts the third P-type doped polysilicon layer 26.

[0159] As some embodiments of the present disclosure, the doping concentration of the P-type dopant of the second P-type doped polysilicon layer 24 is greater than the doping concentration of the third P-type doped polysilicon layer 26.

[0160] In the present embodiment, since the doping concentration of the P-type dopant of the second P-type doped polysilicon layer 24 is greater than the doping concentration of the third P-type doped polysilicon layer 26, the light transmittance of the P region 11 can be improved, and both the passivation effect and the utilization of sunlight can be enhanced.

[0161] As some embodiments of the present disclosure, the second passivation contact structure 3 further comprises:

[0162] A fourth barrier layer 35 is disposed on a side of the second N-type doped polysilicon layer 34 facing away from the silicon substrate 1.

[0163] In the present embodiment, the second electrode 5 contacts the second N-type doped polysilicon layer 34 through the fourth barrier layer 35. By disposing the fourth barrier layer 35 on the surface of the second N-type doped polysilicon layer 34 facing away from the silicon substrate 1, the fourth barrier layer 35 can block the inward diffusion of impurities into the silicon substrate 1, further block the inward diffusion of impurities into the silicon substrate 1, and block the loss of N-type dopant atoms from the N-type doped polysilicon layer, further improving the passivation effect of the battery.

[0164] As some embodiments of the present disclosure, the thickness of the fourth barrier layer 35 is less than the thickness of the second passivation layer 31.

[0165] In the present embodiment, the thickness of the fourth barrier layer 35 is less than the thickness of the first passivation layer 21, so that the fourth barrier layer 35 is thicker than the second passivation layer 31, and the passivation effect of the first passivation layer 21 can be improved.

[0166] As some embodiments of the present disclosure, further comprising:

[0167] A third N-type doped polysilicon layer 36 is disposed on a side of the fourth barrier layer 35 facing away from the silicon substrate 1.

[0168] In the embodiment, the third N-type doped polysilicon layer 36 is added, and the third N-type doped polysilicon layer 36 can further enhance the passivation effect of the N region 12 of the cell.

[0169] In the embodiment, the second electrode 5 passes through the third N-type doped polysilicon layer 36 and the fourth barrier layer 35 to contact the second N-type doped polysilicon layer 34. Of course, in some embodiments, the second electrode 5 directly contacts the third N-type doped polysilicon layer 36.

[0170] As some embodiments of the present disclosure, the doping concentration of the N-type dopant of the third N-type doped polysilicon layer 36 is greater than the doping concentration of the N-type dopant of the second N-type doped polysilicon layer 34.

[0171] In other embodiments, the third P-type doped polysilicon layer 26 and the third N-type doped polysilicon layer 36 further have a stack structure of barrier layers and P-type doped polysilicon layers or N-type doped polysilicon layers, respectively, away from the surface of the silicon substrate 1, to further enhance the passivation effect of the cell.

[0172] In addition, in other embodiments, the third P-type doped polysilicon layer 26 and the third N-type doped polysilicon layer 36 further have a back passivation layer, such as a silicon nitride layer, away from the surface of the silicon substrate 1, to further enhance the passivation effect of the cell.

[0173] Embodiment Three

[0174] The present disclosure also provides a battery assembly including the back contact solar cell of the above-mentioned embodiment one or embodiment two. It should be noted that the battery assembly has the same or similar beneficial effects as the above-mentioned back contact solar cell, and the related parts between the two can be referred to each other. In order to avoid repetition, it will not be described here.

[0175] Embodiment Four

[0176] The present disclosure also provides a photovoltaic system including the battery assembly of the above-mentioned embodiment three. It should be noted that the photovoltaic system has the same or similar beneficial effects as the back contact solar cell, and the related parts between the two can be referred to each other. In order to avoid repetition, it will not be described here.

[0177] The first passivation contact structure 2 of the P region 11 of the back contact solar cell provided by the present disclosure comprises a first passivation layer 21, a first P-type doped polysilicon layer 22, a first barrier layer 23 and a second P-type doped polysilicon layer 24 which are sequentially stacked on the surface of the silicon substrate 1, and the second passivation contact structure 3 of the N region 12 comprises a second passivation layer 31, a first N-type doped polysilicon layer 32, a second barrier layer 33 and a second N-type doped polysilicon layer 34 which are sequentially stacked on the surface of the silicon substrate 1, the first passivation contact structure 2 blocks the impurity from diffusing into the silicon substrate 1 by the first passivation layer 21 and the first barrier layer 23, and the second passivation contact structure 3 blocks the impurity from diffusing into the silicon substrate 1 by the second passivation layer 31 and the second barrier layer 33, so that the impurity diffusing into the silicon substrate 1 can be reduced, the excessive impurity diffusing into the silicon substrate 1 can be avoided, the passivation effect of the back contact solar cell can be obviously improved, and the cell efficiency can be improved.

[0178] Moreover, the doping concentration of the P-type dopant of the first P-type doped polysilicon layer 22 is greater than the doping concentration of the P-type dopant of the second P-type doped polysilicon layer 24, and the doping concentration of the N-type dopant of the first N-type doped polysilicon layer 32 is less than the doping concentration of the N-type dopant of the second N-type doped polysilicon layer 34, by reducing the doping concentration of the P-type dopant of the second P-type doped polysilicon layer 24 of the P region 11, the light transmittance of the second P-type doped polysilicon layer 24 can be increased, so that the utilization rate of sunlight of the back contact solar cell can be improved, and the cell efficiency can be further improved.

[0179] The above only describes the preferred embodiments of the present disclosure and should not be used to limit the present disclosure, and any modifications, equivalent replacements and improvements made within the spirit and principle of the present disclosure should be included in the protection scope of the present disclosure.

Claims

1. A back contact solar cell, comprising: a silicon substrate, a back surface of the silicon substrate being provided with a P region and an N region; a first passivated contact structure provided at the P region, the first passivated contact structure comprising a first passivation layer, a first P-type doped polysilicon layer, a first barrier layer and a second P-type doped polysilicon layer which are sequentially stacked at the back surface of the silicon substrate; a second passivated contact structure provided at the N region, the second passivated contact structure comprising a second passivation layer, a first N-type doped polysilicon layer, a second barrier layer and a second N-type doped polysilicon layer which are sequentially stacked at the back surface of the silicon substrate; wherein a P-type dopant doping concentration of the first P-type doped polysilicon layer is greater than a P-type dopant doping concentration of the second P-type doped polysilicon layer, and an N-type dopant doping concentration of the first N-type doped polysilicon layer is less than an N-type dopant doping concentration of the second N-type doped polysilicon layer.

2. The back contact solar cell of claim 1, wherein, a ratio of the P-type dopant doping concentration of the first P-type doped polysilicon layer to the P-type dopant doping concentration of the second P-type doped polysilicon layer is 1-2 and not equal to 1.

3. The back contact solar cell of claim 1, wherein, a ratio of the P-type dopant doping concentration of the first P-type doped polysilicon layer to the P-type dopant doping concentration of the second P-type doped polysilicon layer is 1.01-1.

50.

4. The back contact solar cell of claim 1, wherein, The doping concentration of the P-type dopant of the first P-type doped polysilicon layer is 3x10 19 ~ 15x10 19 atoms / cm 3 .

5. The back contact solar cell of claim 1, wherein, a ratio of the N-type dopant doping concentration of the first N-type doped polysilicon layer to the N-type dopant doping concentration of the second N-type doped polysilicon layer is 0.5-1.

6. The back contact solar cell of claim 1, wherein, The doping concentration of the N-type dopant of the first N-type doped polysilicon layer and the doping concentration of the N-type dopant of the second N-type doped polysilicon layer are 0.5x10 20 ~1.2x10 21 atoms / cm 3 .

7. The back contact solar cell of claim 1, wherein, further comprising: a first electrode provided at the P region and in contact with the second P-type doped polysilicon layer; a second electrode provided at the N region and in contact with the second N-type doped polysilicon layer.

8. The back contact solar cell of claim 7, wherein, a thickness of the first P-type doped polysilicon layer is less than a thickness of the second P-type doped polysilicon layer.

9. The back contact solar cell of claim 7, wherein, a thickness of the first N-type doped polysilicon layer is less than a thickness of the second N-type doped polysilicon layer.

10. The back contact solar cell of claim 8, wherein, a ratio of the thickness of the second P-type doped polysilicon layer to the thickness of the first P-type doped polysilicon layer is 1-30.

11. The back contact solar cell of claim 8, wherein, a ratio of the thickness of the second P-type doped polysilicon layer to the thickness of the first P-type doped polysilicon layer is 1.5-15.

12. The back contact solar cell of claim 1, wherein, a sum of the thickness of the first P-type doped polysilicon layer and the thickness of the second P-type doped polysilicon layer is 80-210 nanometers.

13. The back contact solar cell of claim 1, wherein, a sum of the thickness of the first N-type doped polysilicon layer and the thickness of the second N-type doped polysilicon layer is 60-200 nanometers.

14. The back contact solar cell of claim 1, wherein, the sum of the thickness of the first P-type doped polysilicon layer and the thickness of the second P-type doped polysilicon layer is greater than the sum of the thickness of the first N-type doped polysilicon layer and the thickness of the second N-type doped polysilicon layer.

15. The back contact solar cell of claim 1, wherein, a sum of a thickness of the first passivation layer and a thickness of the first barrier layer is 1.5-2.8 nanometers.

16. The back contact solar cell of claim 1, wherein, the sum of the thickness of the first passivation layer and the thickness of the first barrier layer is greater than a sum of a thickness of the second passivation layer and a thickness of the second barrier layer.

17. The back contact solar cell of claim 1, wherein, the thickness of the first barrier layer is greater than 0.8 nanometers.

18. The back contact solar cell of claim 9, wherein, a ratio of the thickness of the second N-type doped polysilicon layer to the thickness of the first N-type doped polysilicon layer is 1-40.

19. The back contact solar cell of claim 9, wherein, The ratio of the thickness of the second N-type doped polysilicon layer to the thickness of the first N-type doped polysilicon layer is 2-20.

20. The back contact solar cell of claim 7, wherein, The first electrode enters the second P-type doped polysilicon layer and does not enter the first barrier layer, and the second electrode enters the second N-type doped polysilicon layer and does not enter the second barrier layer.

21. The back contact solar cell of claim 7, wherein, The depth of the first electrode entering the second P-type doped polysilicon layer is greater than the depth of the second electrode entering the second N-type doped polysilicon layer.

22. The back contact solar cell of claim 1, wherein, The total thickness of the first passivation layer, the first P-type doped polysilicon layer, the first barrier layer and the second P-type doped polysilicon layer is greater than the total thickness of the second passivation layer, the first N-type doped polysilicon layer, the second barrier layer and the second N-type doped polysilicon layer.

23. The back contact solar cell of claim 1, wherein, The thickness of the second P-type doped polysilicon layer is greater than the thickness of the second N-type doped polysilicon layer.

24. The back contact solar cell of claim 1, wherein, The thickness of the second N-type doped polysilicon layer is greater than the thickness of the first P-type doped polysilicon layer.

25. The back contact solar cell of claim 1, wherein, The thickness of the first P-type doped polysilicon layer is greater than the thickness of the first N-type doped polysilicon layer.

26. The back contact solar cell of claim 1, wherein, The thickness of the first passivation layer is greater than the thickness of the first barrier layer; and the thickness of the second passivation layer is greater than the thickness of the second barrier layer.

27. The back contact solar cell of claim 1, wherein, The first passivation layer comprises one or a combination of boron or gallium containing silicon oxide, silicon oxynitride, silicon nitride; and the second passivation layer comprises one or a combination of phosphorus containing silicon oxide, silicon oxynitride, silicon nitride.

28. The back contact solar cell of claim 1, wherein, The first barrier layer comprises one or a combination of boron or gallium containing silicon oxide, silicon oxynitride, silicon nitride, silicon carbide; and the second barrier layer comprises one or a combination of phosphorus containing silicon oxide, silicon oxynitride, silicon nitride, silicon carbide.

29. The back contact solar cell of claim 1, wherein, The first passivation contact structure further comprises: A third barrier layer is disposed on a side of the second P-type doped polysilicon layer facing away from the silicon substrate.

30. The back contact solar cell of claim 29, wherein, The thickness of the third barrier layer is less than the thickness of the first passivation layer.

31. The back contact solar cell of claim 29, wherein, The first passivation contact structure further comprises: A third P-type doped polysilicon layer is disposed on a side of the third barrier layer facing away from the silicon substrate.

32. The back contact solar cell of claim 31, wherein, The doping concentration of the P-type dopant of the second P-type doped polysilicon layer is greater than the doping concentration of the third P-type doped polysilicon layer.

33. The back contact solar cell of claim 1, wherein, The second passivation contact structure further comprises: A fourth barrier layer is disposed on a side of the second N-type doped polysilicon layer facing away from the silicon substrate.

34. The back contact solar cell of claim 33, wherein, The thickness of the fourth barrier layer is less than the thickness of the second passivation layer.

35. The back contact solar cell of claim 33, wherein, The second passivation contact structure further comprises: A third N-type doped polysilicon layer is disposed on a side of the fourth barrier layer facing away from the silicon substrate.

36. The back contact solar cell of claim 35, wherein, The doping concentration of the N-type dopant of the third N-type doped polysilicon layer is greater than the doping concentration of the N-type dopant of the second N-type doped polysilicon layer.

37. A battery assembly comprising the back contact solar cell of any one of claims 1-36.

38. A photovoltaic system comprising the battery assembly of claim 37.

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