Solar cell and solar cell module

Abstract

A solar cell module, comprising a solar cell. The solar cell comprises a back intrinsic hydrogenated amorphous silicon layer and a doped layer which are sequentially arranged. The doped layer comprises P-type doped microcrystalline silicon layers and N-type non-doped layers which are arranged alternately and spaced apart. The surfaces of the P-type doped microcrystalline silicon layers and the N-type non-doped layers each are independent and sequentially stacked with a TCO layer and a metal electrode layer. The TCO layer on the surface of a P-type doped microcrystalline silicon layer is a composite TCO layer, and the composite TCO layer comprises a first TCO layer and a second TCO layer. The first TCO layer is adjacent to the P-type doped microcrystalline silicon layer, and the first TCO layer and the second TCO layer differ in light transmittance and resistivity.

Description

Solar cell and solar cell module

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office of China on January 30, 2024, with application number 202410141619.8 and titled “A Solar Cell, a Solar Cell Module,” the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present application relates to the technical field of photovoltaic devices, and in particular to a solar cell and a solar cell module. Background Art

[0004] Traditional heterojunction solar cells (HJTs) have good surface passivation and less recombination, resulting in a higher open-circuit voltage. This is due to the chemical passivation of the intrinsic hydrogenated amorphous silicon layer and the field-effect passivation of the doped amorphous silicon layer. However, the amorphous silicon layer has strong parasitic absorption of incident light, and the front metal electrode can also cause shading problems, resulting in a decrease in short-circuit current, thus preventing further efficiency improvements. Heterojunction back-contact cells (HBCs) place both the emitter and back field on the back of the cell, with only the intrinsic passivation layer and anti-reflection layer on the front, which greatly increases the light transmission effect. However, the emitter, back field and transparent conductive oxide (TCO) layer on the back of the cell are poorly contacted, resulting in a high series resistance.

[0005] Public content

[0006] In view of this, the present application provides a solar cell and a solar cell module, wherein the solar cell has a composite TCO layer structure, which improves the conductive properties of the TCO while ensuring the optical properties of the TCO layer, thereby obtaining a solar cell with better photoelectric performance.

[0007] In a first aspect, the present application provides a solar cell, comprising: a back intrinsic hydrogenated amorphous silicon layer; and a doped layer, wherein the back intrinsic hydrogenated amorphous silicon layer and the doped layer are arranged in sequence, the doped layer comprising a P-type doped microcrystalline silicon layer and an N-type non-doped layer which are alternately arranged and spaced apart, the surfaces of the P-type doped microcrystalline silicon layer and the N-type non-doped layer being independently and sequentially stacked with a TCO layer and a metal electrode layer; wherein the TCO layer on the surface of the P-type doped microcrystalline silicon layer is a composite TCO layer, the composite TCO layer comprising a first TCO layer and a second TCO layer, the first TCO layer being close to the P-type doped microcrystalline silicon layer, and the first TCO layer and the second TCO layer having different transmittance and resistivity.

[0008] Optionally, the light transmittance of the first TCO layer is greater than the light transmittance of the second TCO layer; and the resistivity of the first TCO layer is greater than the resistivity of the second TCO layer.

[0009] Optionally, the thickness of the composite TCO layer is 80 nm-120 nm.

[0010] Optionally, the composite TCO layer further includes a third TCO layer, and the first TCO layer, the second TCO layer and the third TCO layer are stacked in sequence.

[0011] Optionally, the thickness of the first TCO layer is 15 nm-30 nm, the thickness of the second TCO layer is 5 nm-20 nm, and the thickness of the third TCO layer is 30 nm-100 nm.

[0012] Optionally, a thickness ratio of the first TCO layer, the second TCO layer, and the third TCO layer is (0.15-1):(0.05-0.67):1.

[0013] Optionally, the light transmittance of the first TCO layer is 85%-92%, the light transmittance of the second TCO layer is 80%-85%, and the light transmittance of the third TCO layer is 85%-92%.

[0014] Optionally, the resistivity of the first TCO layer is 3×10 -3 Ω·cm-5×10 -3 Ω·cm, the resistivity of the second TCO layer is 8×10 -4 Ω·cm-3×10 -3 Ω·cm, the resistivity of the third TCO layer is 3×10 -3 Ω·cm-5×10 -3 Ω·cm.

[0015] Optionally, the first TCO layer, the second TCO layer and the third TCO layer each independently include one or more of SnOx, TiOx, LiFx, MgOx, and CsCO3.

[0016] Optionally, the first TCO layer and the third TCO layer include SnOx, wherein x is 1.75-1.85; and the second TCO layer includes SnOx, wherein x is 1.6-1.7.

[0017] Optionally, the TCO layer on the surface of the N-type non-doped layer is a fourth TCO layer, and the thickness of the fourth TCO layer is 80 nm-120 nm.

[0018] Optionally, the light transmittance of the fourth TCO layer is 85%-92%, and the resistivity of the fourth TCO layer is 3×10 -3 Ω·cm-5×10-3Ω·cm.

[0019] Optionally, the fourth TCO layer includes one or more of SnOx, TiOx, LiFx, MgOx, and CsCO3.

[0020] Optionally, the fourth TCO layer comprises SnOx, wherein x is 1.75-1.85.

[0021] Optionally, the N-type non-doped layer includes one or more of SnOx, TiOx, LiFx, MgOx, and CsCO3.

[0022] Optionally, the N-type non-doped layer includes SnOx, where x is 1.6-1.7.

[0023] Optionally, the solar cell includes a crystalline silicon substrate, which includes a back side and a front side that are relatively arranged, the back side is provided with the back side intrinsic hydrogenated amorphous silicon layer, and the front side is sequentially stacked with a front side velvet, a front side intrinsic hydrogenated amorphous silicon layer and an anti-reflection layer, and the front side velvet is close to the front side.

[0024] In a second aspect, the present application provides a solar cell assembly, which includes the solar cell described in the first aspect of the present application.

[0025] Through the above technical solution, the present application improves the overall conductivity of the composite TCO layer without affecting the optical performance by setting a composite TCO layer structure on the surface of the P-type doped microcrystalline silicon layer of the solar cell, thereby improving the photoelectric conversion efficiency of the solar cell.

[0026] Other features and advantages of the present application will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0028] FIG1 is a schematic diagram of a partial structure of a solar cell in one embodiment of the present application.

[0029] FIG2 is a schematic diagram of the complete structure of a solar cell in one embodiment of the present application.

[0030] FIG3 is a schematic block diagram of a solar cell assembly in one embodiment of the present application.

[0031] Explanation of the accompanying reference numerals: 200, solar cell module; 100, solar cell; 1, crystalline silicon substrate; 2, front velvet surface; 3, front intrinsic hydrogenated amorphous silicon layer; 4, front anti-reflection layer; 5, back intrinsic hydrogenated amorphous silicon layer; 6, P-type doped microcrystalline silicon layer; 7, first TCO layer; 8, second TCO layer; 9, third TCO layer; 10, metal electrode layer; 11, N-type non-doped layer; 12, fourth TCO layer; 13, composite TCO layer; 14, doped layer. DETAILED DESCRIPTION

[0032] The following is a clear and complete description of the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of this application.

[0033] The terms "first" and "second" in the specification and claims of this application may explicitly or implicitly refer to one or more of the features. Throughout the description of this application, unless otherwise specified, "plurality" means two or more. Furthermore, "and / or" in the specification and claims refers to at least one of the connected entities, and the character " / " generally indicates an "or" relationship between the connected entities.

[0034] As shown in FIG1 and with reference to FIG3 , the present application provides a solar cell 100 comprising a sequentially arranged back-side intrinsic hydrogenated amorphous silicon layer 5 and a doped layer 14. The doped layer 14 comprises alternating and spaced P-type doped microcrystalline silicon layers 6 and N-type undoped layers 11. The surfaces of the P-type doped microcrystalline silicon layers 6 and the N-type undoped layers 11 are independently and sequentially stacked with a TCO layer and a metal electrode layer 10. The TCO layer on the surface of the P-type doped microcrystalline silicon layer 6 is a composite TCO layer 13, comprising a first TCO layer 7 and a second TCO layer 8. The first TCO layer 7 is adjacent to the P-type doped microcrystalline silicon layer 6, and the first and second TCO layers 7 and 8 have different transmittances and resistivities.

[0035] The TCO layer allows light to pass through and enter the silicon wafer's absorption layer, thereby improving the cell's light absorption efficiency. It also conducts the collected current and transmits it to external circuits. Furthermore, the TCO layer reduces charge recombination losses, significantly impacting the photovoltaic performance of solar cell 100.

[0036] In one embodiment of the present application, the transmittance of the first TCO layer 7 is greater than the transmittance of the second TCO layer 8, and the resistivity of the first TCO layer 7 is greater than the resistivity of the second TCO layer 8. The transmittance of the first TCO layer 7 is 85%-92%, and the transmittance of the second TCO layer 8 is 80%-85%. The resistivity of the first TCO layer 7 is 3×10 -3 Ω·cm-5×10 -3 Ω·cm, the resistivity of the second TCO layer 8 is 8×10 -4 Ω·cm-3×10 -3 The first TCO layer 7 is in direct contact with the P-type doped microcrystalline silicon layer 6. Therefore, the first TCO layer 7 has a high light transmittance, a high resistivity, and a low conductivity, which is beneficial to the transport of carriers.

[0037] In one embodiment of the present application, the composite TCO layer 13 further includes a third TCO layer 9, that is, the composite TCO layer 13 includes a three-layer structure, specifically including a first TCO layer 7, a second TCO layer 8, and a third TCO layer 9 stacked in sequence, with the first TCO layer 7 being adjacent to the P-type doped microcrystalline silicon layer 6. In other words, the surface of the P-type doped microcrystalline silicon layer 6 is sequentially stacked with the first TCO layer 7, the second TCO layer 8, and the third TCO layer 9. The thickness of the composite TCO layer 13 is 80nm-120nm, preferably 100nm-110nm. Within this range, the thickness of the TCO layer can ensure both optical performance and electrical conductivity. In addition, the three-layer structure of the TCO layer further improves the electrical conductivity. In one embodiment of the present application, the thickness of the composite TCO layer 13 is 110nm.

[0038] In one embodiment of the present application, the thickness of the first TCO layer 7 is 15 nm to 30 nm, the thickness of the second TCO layer 8 is 5 nm to 20 nm, and the thickness of the third TCO layer 9 is 30 nm to 100 nm. The thickness ratio of the first TCO layer 7, the second TCO layer 8, and the third TCO layer 9 is (0.15-1):(0.05-0.67):1. This thickness adjustment of the layers of the composite TCO layer 13 improves electrical conductivity without significantly reducing light transmittance.

[0039] In one embodiment of the present application, a fourth TCO layer 12 and a metal electrode layer 10 are sequentially laminated on the surface of the N-type undoped layer 11. The thickness of the fourth TCO layer 12 is 80 nm to 120 nm, preferably 100 nm to 110 nm. The thickness of the fourth TCO layer 12 should be consistent with the thickness of the composite TCO layer 13. In other words, the thickness of the fourth TCO layer 12 is equal to the total thickness of the first TCO layer 7, the second TCO layer 8, and the third TCO layer 9. Within this thickness range, the fourth TCO layer 12 maintains both optical performance and electrical conductivity.

[0040] In one embodiment of the present application, the transmittance of the first TCO layer 7 is 85-92%, the transmittance of the second TCO layer 8 is 80-85%, and the transmittance of the third TCO layer 9 is 85-92%. These transmittances are specified at a wavelength of 400-1100 nm. In the composite TCO layer 13, the outer first and third TCO layers 7 and 9 have higher transmittances, while the middle second TCO layer 8 has lower resistivity. This helps increase the carrier concentration of the composite TCO layer 13 without significantly reducing transmittance.

[0041] In one embodiment of the present application, the resistivity of the first TCO layer 7 is 3×10 -3 Ω·cm-5×10 -3 Ω·cm, the resistivity of the second TCO layer 8 is 8×10 -4 Ω·cm-3×10 -3 Ω·cm, the resistivity of the third TCO layer 9 is 3×10 -3 Ω·cm-5×10 -3 In the composite TCO layer 13 , the second TCO layer 8 located in the middle has a lower resistivity, which is beneficial to improving the overall conductive performance of the composite TCO layer 13 .

[0042] In one embodiment of the present application, the fourth TCO layer 12 has a light transmittance of 85%-92% and a resistivity of 3×10 -3 Ω·cm-5×10 -3 Ω·cm. The transmittance here is also limited to the wavelength of 400nm-1100nm. When the resistivity of the fourth TCO layer is within this range, the conductive performance is good.

[0043] In one embodiment of the present application, the material of the N-type undoped layer 11 includes one or more of SnOx, TiOx, LiFx, MgOx, and CsCO3, and the material of the fourth TCO layer 12 includes one or more of SnOx, TiOx, LiFx, MgOx, and CsCO3. Preferably, the material of the N-type undoped layer 11 and the fourth TCO layer 12 is the same, and may preferably be SnOx. In one embodiment of the present application, the N-type undoped layer 11 and the fourth TCO layer 12 are both SnOx, but the oxygen vacancy content of the two is different. Specifically, the N-type undoped layer 11 includes SnOx, with x in the range of 1.6-1.7, and the fourth TCO layer 12 includes SnOx, with x in the range of 1.75-1.85. Oxygen vacancies refer to the detachment of oxygen atoms in a metal oxide to form vacancies. A high oxygen vacancy content results in a higher carrier concentration and better conductivity, but also produces significant parasitic absorption of light. A low oxygen vacancy content indicates that the film is fully oxidized and has good light transmittance, but its conductivity is poorer than that of a film with a high oxygen vacancy content. In this structure, the N-type undoped layer 11 has a low oxygen vacancy content to produce a smaller work function, which facilitates more efficient electron extraction. Because the N-type undoped layer 11 and the fourth TCO layer 12 are made of the same material, the interface contact between the N-type undoped layer 11 and the fourth TCO layer 12 is effectively improved, reducing the interface resistance and increasing the fill factor, thereby further improving the cell efficiency of the solar cell 100.

[0044] In one embodiment of the present application, the materials of the first TCO layer 7, the second TCO layer 8 and the third TCO layer 9 independently include one or more of SnOx, TiOx, LiFx, MgOx, and CsCO3. Furthermore, SnOx can be preferably used. The use of SnOx in the solar cell 100 facilitates the adjustment of the oxygen vacancy content.

[0045] In one embodiment of the present application, the materials of the first TCO layer 7, the second TCO layer 8, and the third TCO layer 9 are all SnOx, but with different oxygen vacancy contents. Specifically, the first TCO layer 7 and the third TCO layer 9 comprise SnOx with x in the range of 1.75-1.85, while the second TCO layer 8 comprises SnOx with x in the range of 1.6-1.7. The sputtering targets used to prepare the three TCO layers are the same, differing only in the process conditions. Specifically, when preparing the first TCO layer 7 and the third TCO layer 9, a higher oxygen flow rate leads to fewer oxygen vacancies and a lower carrier concentration, thereby reducing their parasitic absorption of incident light and increasing their light transmittance. When preparing the second TCO layer 8, a lower oxygen flow rate creates more oxygen vacancies and generates more carriers, thereby reducing the work function and enhancing its ability to extract carriers.

[0046] In general, the materials for the first, second, third, and fourth TCO layers 7, 8, 9, 12, and N-type undoped layer 11 are all preferably SnOx. However, the oxygen vacancy content of the first, third, and fourth TCO layers 7, 9, and 12 is consistent, with x ranging from 1.75 to 1.85. The oxygen vacancy content of the second TCO layer 8 and the N-type undoped layer 11 is consistent, with x ranging from 1.6 to 1.7. This structure helps maintain the overall photoelectric performance of the composite TCO layer 13 while also reducing the series resistance between the second TCO layer 8 and the N-type undoped layer 11, improving conductivity and ultimately boosting the photovoltaic conversion efficiency of the cell.

[0047] Metal electrode materials generally require high electrical conductivity, weldability, corrosion resistance, and stability. In one embodiment of the present application, the metal electrode layer 10 can be made of copper or silver. These materials can form good ohmic contact with the TCO layer, ensuring a long battery life. In one embodiment of the present application, the metal electrode layer 10 is a copper electrode.

[0048] In one embodiment of the present application, the P-type doped microcrystalline silicon layer 6 serves as a hole transport layer, and the N-type undoped layer 11 serves as an electron transport layer. The thickness of the N-type undoped layer 11 and the P-type doped microcrystalline silicon layer 6 are consistent, ranging from 5nm to 20nm, and the ratio of the width of the N-type undoped layer 11 to the P-type doped microcrystalline silicon layer 6 is 1:(2.8-3.2), preferably 1:3. Since the P-type doped microcrystalline silicon layer 6 and the N-type undoped layer 11 are both arranged on the same surface in the HBC battery, the carrier transmission path is lateral transmission. For the N-type silicon substrate, the majority carriers are electrons and the minority carriers are holes. When the P-type doped microcrystalline silicon layer 6 is arranged wider, the holes can move a shorter distance to reach. Therefore, the above structure is conducive to reducing the transmission distance of minority carriers, reducing lateral transmission resistance, while reducing minority carrier recombination and improving passivation.

[0049] Furthermore, as shown in FIG2 , the solar cell 100 is an HBC cell, comprising a crystalline silicon substrate 1. The crystalline silicon substrate 1 includes a backside and a frontside, oppositely disposed rear side. A rear side intrinsic hydrogenated amorphous silicon layer 5 is disposed on the rear side, while a front side velvet 2, a front side intrinsic hydrogenated amorphous silicon layer 3, and an anti-reflection layer 4 are sequentially laminated on the front side, with the front side velvet 2 being adjacent to the front side. A doped layer 14 is laminated on the surface of the rear side intrinsic hydrogenated amorphous silicon layer 5. The doped layer 14 comprises alternating and spaced P-type doped microcrystalline silicon layers 6 and N-type undoped layers 11. TCO layers and metal electrode layers 10 are independently and sequentially laminated on the surfaces of the P-type doped microcrystalline silicon layers 6 and the N-type undoped layers 11. The TCO layer on the surface of the P-type doped microcrystalline silicon layer 6 is a composite TCO layer 13 having a multilayer structure, comprising a first TCO layer 7, a second TCO layer 8, and a third TCO layer 9. The TCO layer on the surface of the N-type undoped layer 11 is a fourth TCO layer 12.

[0050] HBC cells are solar cells that utilize HJT's amorphous silicon thin-film technology in an interdigitated back contact (IBC) structure. Their structure features no metal electrodes blocking the front surface, and a cross-patterned arrangement of P and N regions on the back. Combining HJT and IBC technologies, HBC cells offer high short-circuit current and open-circuit voltage.

[0051] Specifically, the crystalline silicon substrate 1 serves as the base material of the cell, absorbing sunlight and generating current. The TCO layer 12 / composite TCO layer 13 allows light to pass through and enter the silicon wafer's absorption layer, thereby improving the cell's light absorption efficiency. It also conducts the collected current and transmits it to the external circuit. The anti-reflection layer 4 primarily reduces light reflection, thereby improving light absorption efficiency. By adding the anti-reflection layer 4 to the front of the cell, light reflection from the silicon wafer surface is reduced, allowing more light to enter and be absorbed within the wafer. This improves the cell's photoelectric conversion efficiency, thereby enhancing its performance. The front intrinsic hydrogenated amorphous silicon layer 3 and the back intrinsic hydrogenated amorphous silicon layer 5 function primarily in three aspects: 1. Passivation: The intrinsic hydrogenated amorphous silicon layer passivates the silicon wafer surface, reducing the surface recombination rate, thereby improving minority carrier lifetime. 2. Light trapping: This layer forms a pyramidal textured surface, reducing surface reflection and increasing the residence time of light on the silicon wafer surface, thereby improving photon utilization. 3. Improved open-circuit voltage: Due to the excellent passivation effect of this layer, the cell maintains a high open-circuit voltage. The main function of the front textured surface 2 is to improve light absorption efficiency and passivate the surface of the crystalline silicon substrate 1. The textured surface increases light scattering and reflection on the surface of the crystalline silicon substrate 1, allowing more light to enter and be absorbed. Furthermore, the textured surface provides a larger surface area, making the surface of the crystalline silicon substrate 1 rougher, which facilitates passivation. The passivation effect reduces the surface recombination rate, thereby improving the minority carrier lifetime and further enhancing the cell's photoelectric conversion efficiency. Therefore, the front velvet 2 plays an important optimization role in HBC cells, helping to improve the photoelectric performance and stability of the cells.

[0052] The present application also provides a method for preparing the above-mentioned solar cell, the specific process comprising the following steps:

[0053] (1) Select an N-type single crystal silicon wafer substrate for texturing and cleaning.

[0054] (2) Plasma enhanced chemical vapor deposition (PECVD) is used to deposit intrinsic hydrogenated amorphous silicon layers on the front and back sides of the single crystal silicon substrate, and then an anti-reflection layer is deposited on the front intrinsic hydrogenated amorphous silicon, and a P-type doped microcrystalline silicon layer is deposited on the back intrinsic hydrogenated amorphous silicon. The SnO2 planar target is sputtered by physical vapor deposition (PVD) to obtain SnO2 x During the sputtering process of the mask layer (i.e. the first TCO layer), a mixture of argon, oxygen and argon-hydrogen is introduced as the process gas, and SnO x The mask layer is prepared in the same way as the TCO layer in the subsequent steps. x The mask layer is also the first TCO layer above the P-type doped microcrystalline silicon layer in the entire cell structure.

[0055] (3) Laser etching of SnO x The mask layer and P-type doped microcrystalline silicon layer are deposited using PVD by sputtering a SnO2 planar target to obtain an N-type undoped layer and a fourth TCO layer. The second and third TCO layers are then sequentially formed on the first TCO layer using PVD by sputtering a SnO2 planar target. A mixture of argon, oxygen, and argon-hydrogen is introduced as the process gas during the sputtering process. During the deposition of the N-type undoped layer and the second TCO layer, a low oxygen flow rate is used to create more oxygen vacancies and generate more carriers, thereby reducing the work function and enhancing the carrier extraction capability. During the deposition of the fourth and third TCO layers, a high oxygen flow rate is used to reduce oxygen vacancies and carrier concentration, thereby reducing parasitic absorption of incident light and increasing light transmittance.

[0056] (4) Using an etching solution, wash away the TCO portion above the P-type doped microcrystalline silicon layer away from the crystalline silicon substrate, so that the surface of the composite TCO layer is flat and the thickness is between 100 nm and 110 nm.

[0057] (5) Copper electrodes are directly deposited on the surface of the TCO layer using electroplating to improve the interface contact between the electrode and TCO and reduce the contact resistance.

[0058] (6) Laser etching is used to prepare an insulating region between the region of the P-type doped microcrystalline silicon layer and the region of the N-type non-doped layer, and the width ratio of the P-type doped microcrystalline silicon layer to the N-type non-doped layer is set to 3:1.

[0059] The present application also provides a solar cell assembly 200 , which includes the above-mentioned solar cell 100 , as shown in FIG3 .

[0060] The effects of the technical solution of this application are further illustrated below through specific examples.

[0061] Example 1

[0062] The following HBC cell was prepared according to the above-mentioned method for preparing the solar cell 100 .

[0063] As shown in Figure 2, the HBC cell in this embodiment includes: an anti-reflection layer 4, a front intrinsic hydrogenated amorphous silicon layer 3, a front velvet surface 2, a crystalline silicon substrate 1, a back intrinsic hydrogenated amorphous silicon layer 5, a P-type doped microcrystalline silicon layer 6, an N-type non-doped layer 11, a fourth TCO layer 12, a composite TCO layer 13 (including a first TCO layer 7, a second TCO layer 8 and a third TCO layer 9) and a metal electrode layer 10.

[0064] The anti-reflection layer 4 is MgF2 with a thickness of 150nm; the front intrinsic hydrogenated amorphous silicon layer 13 is amorphous silicon (non-doped) material with a thickness of 5nm; the crystalline silicon substrate 1 is an N-type single crystal silicon wafer with a thickness of 120μm; the back intrinsic hydrogenated amorphous silicon layer 5 is amorphous silicon (non-doped) material with a thickness of 5nm; the P-type doped microcrystalline silicon layer 6 is boron-doped microcrystalline silicon with a thickness of 20nm; the N-type non-doped layer 11 is SnO 1.65 , with a thickness of 20 nm; the fourth TCO layer 12 is SnO 1.8 , with a thickness of 110nm; the first TCO layer 7 is SnO 1.8 , with a thickness of 40nm; the second TCO layer 8 is SnO 1.65 , with a thickness of 20nm; the third TCO layer 9 is SnO 1.8 , with a thickness of 50nm; the metal electrode layer 10 is a copper electrode with a thickness of 15μm.

[0065] Comparative Example 1

[0066] The structures of Comparative Example 1 are basically the same as those of Example 1. The difference is that the composite TCO layer 13 in the original Example 1 is a non-composite structure here, that is, a single-layer TCO layer is formed between the P-type doped microcrystalline silicon layer 6 and the metal electrode layer 10. The single-layer TCO layer is SnO 1.9 , with a thickness of 110nm. In addition, the N-type non-doped layer 11 is SnO 1.71 , with a thickness of 20 nm; the fourth TCO layer 12 is SnO 1.9 , with a thickness of 110nm.

[0067] Performance Testing

[0068] (1) Current density-voltage characteristic curve (JV) test

[0069] The device performance was tested using JV equipment. The specific parameters are shown in Table 1.

[0070] Table 1

[0071] The above test results show that the cell efficiency of Example 1 is significantly improved compared to Comparative Example 1. The solar cell with a composite TCO layer structure not only ensures light transmission performance but also improves electrical conductivity, thereby generally improving the photoelectric conversion capacity of the solar cell.

[0072] The above are preferred embodiments of the present application, but they should not be construed as limiting the scope of the present application. It should be noted that those skilled in the art may make improvements and modifications without departing from the principles of the present application, and such improvements and modifications are also considered to be within the scope of protection of the present application.

Claims

1. A solar cell (100), characterized in that: The solar cell (100) comprises: a backside intrinsic hydrogenated amorphous silicon layer (5); and A doped layer (14), the back intrinsic hydrogenated amorphous silicon layer (5) and the doped layer (14) are arranged in sequence, the doped layer (14) includes a P-type doped microcrystalline silicon layer (6) and an N-type non-doped layer (11) that are alternately arranged and spaced apart, the surfaces of the P-type doped microcrystalline silicon layer (6) and the N-type non-doped layer (11) are independently and sequentially stacked with a TCO layer and a metal electrode layer (10); wherein the TCO layer on the surface of the P-type doped microcrystalline silicon layer (6) is a composite TCO layer (13), the composite TCO layer (13) includes a first TCO layer (7) and a second TCO layer (8), the first TCO layer (7) is close to the P-type doped microcrystalline silicon layer (6), and the first TCO layer (7) and the second TCO layer (8) have different transmittance and resistivity.

2. The solar cell (100) according to claim 1, characterized in that The light transmittance of the first TCO layer (7) is greater than the light transmittance of the second TCO layer (8); and the resistivity of the first TCO layer (7) is greater than the resistivity of the second TCO layer (8).

3. The solar cell (100) according to claim 1 or 2, characterized in that The thickness of the composite TCO layer (13) is 80nm-120nm.

4. The solar cell (100) according to any one of claims 1 to 3, characterized in that The composite TCO layer (13) further includes a third TCO layer (9), and the first TCO layer (7), the second TCO layer (8) and the third TCO layer (9) are stacked in sequence.

5. The solar cell (100) according to claim 4, characterized in that The thickness of the first TCO layer (7) is 15 nm to 30 nm, the thickness of the second TCO layer (8) is 5 nm to 20 nm, and the thickness of the third TCO layer (9) is 30 nm to 100 nm.

6. The solar cell (100) according to claim 4 or 5, characterized in that The thickness ratio of the first TCO layer (7), the second TCO layer (8) and the third TCO layer (9) is (0.15-1):(0.05-0.67):

1.

7. The solar cell (100) according to any one of claims 4 to 6, characterized in that The light transmittance of the first TCO layer (7) is 85%-92%, the light transmittance of the second TCO layer (8) is 80%-85%, and the light transmittance of the third TCO layer (9) is 85%-92%.

8. The solar cell (100) according to any one of claims 4 to 7, characterized in that The resistivity of the first TCO layer (7) is 3×10 -3 Ω·cm-5×10 -3 Ω·cm, the resistivity of the second TCO layer (8) is 8×10 -4 Ω·cm-3×10 -3 Ω·cm, the resistivity of the third TCO layer (9) is 3×10 -3 Ω·cm-5×10 -3 Ω·cm.

9. The solar cell (100) according to any one of claims 4 to 8, characterized in that The first TCO layer (7), the second TCO layer (8) and the third TCO layer (9) each independently include one or more of SnOx, TiOx, LiFx, MgOx, and CsCO3.

10. The solar cell (100) according to claim 9, characterized in that The first TCO layer (7) and the third TCO layer (9) comprise SnOx, wherein x is 1.75-1.85; The second TCO layer (8) comprises SnOx, wherein x is 1.6-1.

7.

11. The solar cell (100) according to any one of claims 1 to 10, characterized in that The TCO layer on the surface of the N-type non-doped layer (11) is a fourth TCO layer (12), and the thickness of the fourth TCO layer (12) is 80 nm-120 nm.

12. The solar cell (100) according to claim 11, characterized in that The light transmittance of the fourth TCO layer (12) is 85%-92%, and the resistivity of the fourth TCO layer (12) is 3×10-3Ω·cm-5×10-3Ω·cm.

13. The solar cell (100) according to claim 11 or 12, characterized in that The fourth TCO layer (12) includes one or more of SnOx, TiOx, LiFx, MgOx, and CsCO3.

14. The solar cell (100) according to claim 13, characterized in that The fourth TCO layer (12) comprises SnOx, wherein x is 1.75-1.

85.

15. The solar cell (100) according to any one of claims 1 to 14, characterized in that The N-type non-doped layer (11) comprises one or more of SnOx, TiOx, LiFx, MgOx, and CsCO3.

16. The solar cell (100) according to claim 15, characterized in that The N-type non-doped layer (11) comprises SnOx, wherein x is 1.6-1.

7.

17. The solar cell (100) according to any one of claims 1 to 16, characterized in that The solar cell (100) comprises a crystalline silicon substrate (1), the crystalline silicon substrate (1) comprises a back surface and a front surface arranged opposite to each other, the back surface is provided with the back intrinsic hydrogenated amorphous silicon layer (5), the front surface is sequentially stacked with a front velvet surface (2), a front intrinsic hydrogenated amorphous silicon layer (3) and an anti-reflection layer (4), and the front surface velvet surface (2) is close to the front surface.

18. A solar cell assembly (200), characterized in that: Comprising a solar cell (100) according to any one of claims 1 to 17.

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