A film layer structure for a crystalline silicon solar cell and a preparation method, cell, module and system thereof

Abstract

The application relates to the photovoltaic technical field and discloses a film layer structure for a crystalline silicon solar cell, a preparation method of the film layer structure, a cell, an assembly and a system. The film layer structure comprises a crystalline silicon substrate, a carrier selective layer and a hydrogen content regulation structure are sequentially arranged on the front surface of the crystalline silicon substrate, and a carrier selective layer and a hydrogen content regulation structure are sequentially arranged on the back surface of the crystalline silicon substrate; the carrier selective layer is a homogenous structure or a passivation contact structure, and the conductive type of the carrier selective layer is N type or P type; the hydrogen content regulation structure comprises a first hydrogen barrier layer, a hydrogen-rich layer and a second hydrogen barrier layer which are sequentially arranged on the surface of the carrier selective layer and used for regulating the hydrogen content entering the carrier selective layer, the hydrogen-rich layer provides hydrogen, and the second hydrogen barrier layer blocks hydrogen from escaping into air. The film layer structure regulates the hydrogen content through structural design, greatly improves the passivation performance of the crystalline silicon solar cell, and effectively eliminates hydrogen-induced attenuation.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic technology, specifically to a film structure for crystalline silicon solar cells, its preparation method, cells, modules, and systems. Background Technology

[0002] Crystalline silicon has a large number of dangling bonds on its surface, which increase the defect state density and consequently the interfacial recombination. Therefore, passivation films such as silicon nitride and aluminum oxide are deposited to reduce interfacial recombination. Passivation is mainly divided into chemical passivation and field passivation. The fixed charge on the passivation film can induce band bending on the surface of crystalline silicon, thereby establishing an electric field to repel minority carriers from reaching the interface and participating in the recombination process; this is called field passivation. The passivation film contains a large amount of hydrogen (i.e., [H]), which can effectively saturate the dangling bonds on the surface of crystalline silicon and reduce the defect state density; this is called chemical passivation. Therefore, [H] in the passivation film plays an important role in reducing surface recombination in crystalline silicon.

[0003] With the development of solar cell technology, cells employing passivated contact structures, such as TOPCon cells (also known as passivated contact cells) with tunneling oxide layers and doped polycrystalline silicon layers, and heterojunction (SHJ) cells with intrinsic amorphous silicon layers and doped amorphous silicon layers, are highly favored by the market. Therefore, these cells with passivated contact structures are expected to become the mainstream crystalline silicon solar cells after P-type PERC cells. Passivated contact structures themselves possess excellent passivation performance, with extremely low defect state density at their interfaces. Consequently, their interface recombination rate is generally less than 1 cm / s, eliminating the need to saturate the dangling bonds on their surface with [H]. Therefore, for crystalline silicon solar cells with passivated contact structures, a large amount of [H] present in passivation films such as silicon nitride and aluminum oxide will enter the bulk region of crystalline silicon during thermal processes (such as the sintering process of metal pastes). New research from the University of New South Wales (UNSW) shows that excess [H] can combine with boron or phosphorus in crystalline silicon, forming new defect states or recombination centers under photothermal conditions. This leads to a decrease in the efficiency of crystalline silicon solar cells, a phenomenon known as "photothermal degradation" (LeTID). Because LeTID is directly related to excess [H], it is also called "hydrogen-induced degradation".

[0004] In industrialized crystalline silicon solar cells, the metal electrodes are primarily formed sequentially through screen printing of metal paste and rapid sintering. Research shows that, for example, SiN... x The [H] content in the passivation film is generally 10. 22 cm -3 During the high-temperature sintering process of metal pastes, such as SiN... x The content of [H] decomposed in the passivation film is 10. 16cm -3 One-tenth of the [H] from the decomposition enters the crystalline silicon, therefore the total [H] content entering the crystalline silicon is 10. 15 cm -3 The bulk defects in N-type crystalline silicon are generally below 10. 11 cm -3 Therefore, some of the introduced [H] can passivate defects in crystalline silicon, while some "excessive" [H] will generate new recombination centers in crystalline silicon, inducing LeTID formation, which leads to a severe decrease in the efficiency of crystalline silicon solar cells. Moreover, multiple LeTID studies have demonstrated that excessive [H] in crystalline silicon is the main cause of LeTID, and there is a positive correlation between the [H] content released from monolayer silicon nitride and aluminum oxide, as well as aluminum oxide / silicon nitride stacked films, and the degree of efficiency degradation of crystalline silicon solar cells.

[0005] Based on this, existing technologies, such as the solar cell film structure disclosed in publication CN216161746U, achieve LeTID resistance by sequentially depositing a fourth and fifth passivation layer on a P-type crystalline silicon substrate in a direction away from the N-type emitter. However, in crystalline silicon solar cells, the passivation film, in addition to passivation performance, also has an anti-reflection effect, requiring a specific film thickness to achieve the optimal anti-reflection effect, such as industrialized SiN... x The optimal antireflection thickness is 70~80nm; moreover, the passivation film is an insulating material, and its thickness will also affect the contact performance between the metal electrode and silicon; therefore, in crystalline silicon solar cells, the thickness of the passivation film is usually fixed, and it is not feasible to control the [H] content by adjusting the thickness of the passivation film, and its control effect is poor. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a film structure for crystalline silicon solar cells, its preparation method, cell, module and system. It controls the hydrogen content through structural design, which can greatly improve the passivation performance of crystalline silicon solar cells and effectively eliminate hydrogen-induced degradation. Based on this, the present invention discloses a film structure for a crystalline silicon solar cell, comprising a crystalline silicon substrate, wherein a carrier selective layer and a hydrogen content regulating structure are sequentially disposed on the front surface of the crystalline silicon substrate, and a carrier selective layer and a hydrogen content regulating structure are sequentially disposed on the rear surface of the crystalline silicon substrate; the carrier selective layer is a homogeneous structure or a passivated contact structure, and the conductivity type of the carrier selective layer is N-type or P-type; the hydrogen content regulating structure comprises a first hydrogen barrier layer for regulating the hydrogen content entering the carrier selective layer, a hydrogen-rich layer for providing hydrogen, and a second hydrogen barrier layer for preventing hydrogen from escaping into the air, which are sequentially stacked on the surface of the carrier selective layer.

[0007] Preferably, the first hydrogen barrier layer and the second hydrogen barrier layer are intrinsic amorphous silicon layers or intrinsic polycrystalline silicon layers prepared by physical vapor deposition.

[0008] More preferably, when the carrier selective layer is a homogeneous structure, the thickness of the first hydrogen barrier layer is less than the thickness of the second hydrogen barrier layer.

[0009] More preferably, when the carrier selective layer is a passivated contact structure, the thickness of the first hydrogen barrier layer is greater than the thickness of the second hydrogen barrier layer.

[0010] More preferably, the thickness of both the first hydrogen barrier layer and the second hydrogen barrier layer is less than or equal to 100 nm.

[0011] Preferably, the hydrogen-rich layer is a stacked structure formed by one or more of the following films: aluminum oxide film, silicon nitride film, silicon oxynitride film, and titanium oxide film; the total thickness of the hydrogen-rich layer is 50~150 nm.

[0012] Preferably, the homogeneous structure is a single-crystal doped layer prepared by thermal diffusion or ion implantation; the single-crystal doped layer is of P-type or N-type conductivity, and has a sheet resistance of 10~500Ω / sq and a junction depth of 0.3~3μm.

[0013] Preferably, the passivation contact structure includes a tunneling oxide layer and a heavily doped polycrystalline silicon layer stacked on the surface of the tunneling oxide layer.

[0014] More preferably, the tunneling oxide layer is made of silicon oxide, titanium oxide, or aluminum oxide, and the thickness of the tunneling oxide layer is 0.5~3.0 nm; The heavily doped polycrystalline silicon layer has an N-type or P-type conductivity, a thickness of 30~600 nm, and a doping concentration of 0.1~8.0E+20cm. -3 .

[0015] Preferably, the crystalline silicon substrate is an N-type crystalline silicon substrate.

[0016] This invention discloses a method for preparing a film structure for crystalline silicon solar cells, comprising the following preparation steps: S1. Carrier selective layers are prepared on both the front and back surfaces of a crystalline silicon substrate; S2. Hydrogen content control structures are prepared on the carrier selectivity layers on both the front and back surfaces of a crystalline silicon substrate.

[0017] The present invention also discloses a crystalline silicon solar cell, including the film structure for a crystalline silicon solar cell described above, and a metal electrode that forms an ohmic contact with the carrier selective layer.

[0018] The present invention also discloses a photovoltaic module, comprising a front panel, a front encapsulation layer, a cell, a back encapsulation layer and a back panel arranged sequentially from top to bottom, wherein the cell is a crystalline silicon solar cell as described above in the present invention.

[0019] The present invention also discloses a photovoltaic system, including one or more photovoltaic modules, wherein the photovoltaic module is one of the photovoltaic modules described above in the present invention.

[0020] Compared with the prior art, the present invention has at least the following beneficial effects: The crystalline silicon solar cell film structure of the present invention has the following advantages: 1) For crystalline silicon with good passivation performance at the interface, such as a passivation contact structure with low interface defect states, less [H] is required. Therefore, placing the first hydrogen barrier layer between the passivation contact structure and the hydrogen-rich layer can absorb and block most of the hydrogen from entering the interface and bulk region of the crystalline silicon, thus preventing "hydrogen-induced degradation"; 2) For crystalline silicon with insufficient interface passivation, such as a homogeneous structure with high interface defect states (e.g., a heavily doped emitter or back surface field), more [H] is required. During sintering, 9 / 10 of the hydrogen will escape from the hydrogen-rich layer into the air. Therefore, placing the second hydrogen barrier layer on top of the hydrogen-rich layer can absorb and block hydrogen from escaping into the air, thereby effectively reducing its defect state density and improving passivation performance. Therefore, the film structure for crystalline silicon solar cells of the present invention regulates the hydrogen content by combining the hydrogen content regulation structure on the carrier selective layer (which is a homogeneous structure or a passivated contact structure). This not only greatly improves the passivation performance of crystalline silicon solar cells, but also effectively eliminates hydrogen-induced degradation of crystalline silicon solar cells with passivated contacts. This significantly improves the reliability of crystalline silicon solar cells and is of great significance for improving their efficiency. Attached Figure Description

[0021] Figure 1 This is a schematic cross-sectional view of the hydrogen content control structure on the front surface of a film structure for crystalline silicon solar cells according to the present invention.

[0022] Figure 2 This is a schematic diagram of the cross-sectional structure of sample 1 in the experimental group of Example 2.

[0023] Figure 3 This is a schematic diagram of the cross-sectional structure of sample 2 in the experimental group of Example 3.

[0024] Figure 4 This is a schematic diagram of the cross-sectional structure of sample 3 in the experimental group of Example 4.

[0025] Figure 5 This is a schematic diagram of the cross-sectional structure of sample 1, the standard control group of Comparative Example 1.

[0026] Figure 6 This is a schematic diagram of the cross-sectional structure of sample 2, the standard control group of Comparative Example 2.

[0027] Figure 7 This is a schematic diagram of the cross-sectional structure of sample 3, the standard control group of Comparative Example 3.

[0028] Figure 8 This is a graph showing the passivation performance test data of the samples from Comparative Example 1 and Example 2.

[0029] Figure 9 This is a graph showing the passivation performance test data of the samples from Comparative Example 2 and Example 3.

[0030] Figure 10 This is a graph showing the passivation performance test data of the samples from Comparative Example 3 and Example 4.

[0031] Figure 11 This is a graph showing the change in power of the samples in Comparative Example 3 and Example 4 relative to the initial value as LeTID cycling increases.

[0032] Reference numerals in the attached figures: 11 crystalline silicon substrate, 12 first carrier selective layer, 131 tunneling oxide layer, 132 doped polycrystalline silicon layer, 14 aluminum oxide film, 15 hydrogen-rich layer, 161 first hydrogen barrier layer, and 162 second hydrogen barrier layer. Detailed Implementation

[0033] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0034] Example 1 This embodiment describes a film structure for a crystalline silicon solar cell. See [link to relevant documentation]. Figure 1-4 The crystalline silicon substrate 11 includes a carrier selective layer and a hydrogen content control structure sequentially disposed on the front surface of the crystalline silicon substrate 11, and a carrier selective layer and a hydrogen content control structure sequentially disposed on the rear surface of the crystalline silicon substrate 11.

[0035] The carrier selective layer is either a homogeneous structure or a passivated contact structure, and its conductivity type is either N-type or P-type.

[0036] Specifically, in this embodiment, the homogeneous structure is a single-crystal doped layer fabricated using thermal diffusion or ion implantation. The single-crystal doped layer has a P-type or N-type conductivity, a sheet resistance of 10–500 Ω / sq, and a junction depth of 0.3–3 μm. Compared to passivated contact structures, this homogeneous structure exhibits poor passivation performance and a higher defect state density on its surface.

[0037] Specifically, the passivation contact structure in this embodiment includes a tunneling oxide layer 131 and a heavily doped polysilicon layer 132 stacked on the surface of the tunneling oxide layer 131 (the surface of the tunneling oxide layer 131 refers to the front and / or back surfaces of the tunneling oxide layer 131). The tunneling oxide layer 131 is made of silicon oxide, titanium oxide, or aluminum oxide, and its thickness is 0.5~3.0 nm. The heavily doped polysilicon layer 132 has an N-type or P-type conductivity, and its thickness is 30~600 nm with a doping concentration of 0.1~8.0E+20cm. -3 The passivated contact structure itself has good passivation performance and its interface has a low defect state density.

[0038] Both the homogeneous structure and the passivated contact structure mentioned above can form good ohmic contact with the metal electrodes in crystalline silicon solar cells and have good conductivity.

[0039] For crystalline silicon solar cells, by setting a suitable structure, the [H] content at the interface and bulk region of crystalline silicon can be controlled to ensure interface passivation while controlling the diffusion of a suitable amount of [H] into crystalline silicon to prevent hydrogen-induced degradation and reduced cell efficiency. This is of great significance for improving passivation performance and preventing hydrogen-induced degradation and reduced cell efficiency.

[0040] Based on this, the hydrogen content control structure in this embodiment includes a first hydrogen barrier layer 161, a hydrogen-rich layer 15, and a second hydrogen barrier layer 162 sequentially stacked on the surface of the carrier selective layer; the first hydrogen barrier layer 161 is used to control the hydrogen content entering the carrier selective layer, and the second hydrogen barrier layer 162 is used to prevent hydrogen from escaping into the air.

[0041] Specifically, the hydrogen-rich layer 15 is used to provide hydrogen. The hydrogen-rich layer 15 is a stacked structure formed by one or more of the following films: aluminum oxide film, silicon nitride film, silicon oxynitride film, and titanium oxide film. The total thickness of the hydrogen-rich layer 15 is 50~150nm.

[0042] The applicant discovered through testing that the intrinsic silicon thin layer (i.e., undoped intrinsic amorphous silicon or intrinsic polycrystalline silicon layer) formed by physical vapor deposition (PVD) methods such as magnetron sputtering, thermal evaporation, and electron beam deposition contains a large number of dangling bonds, with a dangling bond density reaching 10. 19 ~10 20 cm -3It can adsorb a large amount of [H] to saturate its dangling bonds and also block the flow of [H], making it a natural [H] storage structure and [H] blocking structure. Furthermore, the intrinsic silicon thin layer deposited by PVD, like the crystalline silicon substrate 11, is a semiconductor; changing its thickness will not affect the sintering characteristics, contact performance, or anti-reflection effect of the passivation film of the metal paste. Based on this, the first hydrogen barrier layer 161 and the second hydrogen barrier layer 162 in this embodiment are intrinsic amorphous silicon layers or intrinsic polycrystalline silicon layers prepared by physical vapor deposition.

[0043] Furthermore, the applicant also controls the [H] content in the interface and bulk region of crystalline silicon by adjusting the thickness of the intrinsic silicon thin layer formed by PVD. Specifically, the thickness of the first hydrogen barrier layer 161 and the second hydrogen barrier layer 162 is less than or equal to 100 nm. By limiting the thickness of the first hydrogen barrier layer 161 and the second hydrogen barrier layer 162, on the one hand, it can prevent the defect state density reduction effect of the carrier selective layer from being insignificant due to the excessive thickness of the first hydrogen barrier layer 161 and the second hydrogen barrier layer 162, thus ensuring the passivation performance of the carrier selective layer; on the other hand, it can prevent excessive hydrogen from entering the carrier selective layer and forming new defect states or recombination centers due to the excessive thickness of the first hydrogen barrier layer 161 and the second hydrogen barrier layer 162, thereby causing severe hydrogen-induced decay.

[0044] Furthermore, the applicant has further achieved precise control over the [H] content in the interface and bulk region of crystalline silicon by adjusting the thickness of the intrinsic silicon thin layer formed by PVD, thereby enabling crystalline silicon to have better passivation performance and effectively eliminate hydrogen-induced degradation. Specifically, when the carrier selective layer is a homogeneous structure, the thickness of the first hydrogen barrier layer 161 is made smaller than the thickness of the second hydrogen barrier layer 162. In this case, the thicker second hydrogen barrier layer 162 can better adsorb and block hydrogen from escaping from the hydrogen-rich layer 15 into the air, retaining more hydrogen in the film structure for crystalline silicon solar cells. Moreover, since the thickness of the first hydrogen barrier layer 161 is smaller, its hydrogen-blocking effect is not as good as that of the thicker second hydrogen barrier layer 162. Therefore, more retained hydrogen can pass through the thinner first hydrogen barrier layer 161 and enter the homogeneous structure with a higher surface defect state density, thereby greatly reducing the defect state density of the homogeneous structure and greatly improving its passivation performance. When the carrier selective layer is a passivated contact structure, the thickness of the first hydrogen barrier layer 161 is greater than the thickness of the second hydrogen barrier layer 162. In this case, the thinner second hydrogen barrier layer 162 can only adsorb and block a small portion of the hydrogen in the hydrogen-rich layer 15 from escaping into the air. Therefore, only a small amount of hydrogen will remain in the film structure for the crystalline silicon solar cell. Moreover, since the thickness of the first hydrogen barrier layer 161 is larger, the thicker first hydrogen barrier layer 161 has a better hydrogen blocking effect than the thinner second hydrogen barrier layer 162. Therefore, only a smaller amount of retained hydrogen will pass through the thicker first hydrogen barrier layer 161 and enter the passivated contact structure with a lower surface defect state density. This can effectively prevent the formation of new defect states or recombination centers due to excessive hydrogen entering the passivated contact structure, thereby effectively preventing hydrogen-induced degradation.

[0045] The film structure for crystalline silicon solar cells in this embodiment has the following advantages: 1) For crystalline silicon with good passivation performance at the interface, such as a passivation contact structure with low interface defect states, less [H] is required. Therefore, placing the first hydrogen barrier layer 161 between the passivation contact structure and the hydrogen-rich layer 15 can absorb and block most of the hydrogen from entering the interface and bulk region of the crystalline silicon, thus preventing "hydrogen-induced degradation"; 2) For crystalline silicon with insufficient interface passivation, such as a homogeneous structure with high interface defect states (e.g., a heavily doped emitter or back surface field), more [H] is required. During sintering, 9 / 10 of the hydrogen will escape from the hydrogen-rich layer 15 into the air. Therefore, placing the second hydrogen barrier layer 162 on top of the hydrogen-rich layer 15 can absorb and block hydrogen from escaping into the air, thereby effectively reducing its defect state density and improving passivation performance. Therefore, the film structure for crystalline silicon solar cells in this embodiment regulates the hydrogen content by combining the hydrogen content regulation structure on the carrier selective layer (which is a homogeneous structure or a passivated contact structure). This not only greatly improves the passivation performance of crystalline silicon solar cells but also effectively eliminates hydrogen-induced degradation in passivated contact crystalline silicon solar cells. This significantly improves the reliability of crystalline silicon solar cells and is of great significance for improving their efficiency.

[0046] Furthermore, the applicant discovered through testing that, compared to P-type crystalline silicon substrates, this hydrogen content control structure has a better effect on controlling the hydrogen content of the film structure for crystalline silicon solar cells using N-type crystalline silicon substrates, thus achieving superior passivation performance and better eliminating hydrogen-induced degradation. Therefore, the crystalline silicon substrate 11 is preferably an N-type crystalline silicon substrate, in which the carrier selective layer on the front surface of the N-type crystalline silicon substrate has a P-type conductivity, while the carrier selective layer on the rear surface of the N-type crystalline silicon substrate has an N-type conductivity.

[0047] This embodiment provides a method for preparing a film structure for a crystalline silicon solar cell, comprising the following preparation steps: Step 1: Prepare carrier-selective layers on both the front and back surfaces of the crystalline silicon substrate 11; Step 2: Prepare hydrogen content control structures on the carrier selectivity layers on both the front and back surfaces of the crystalline silicon substrate 11 to obtain the film structure for the crystalline silicon solar cell.

[0048] This embodiment of a crystalline silicon solar cell includes the film structure for crystalline silicon solar cells described above, and a metal electrode forming an ohmic contact with the carrier selective layer. Thus, applying this film structure to a crystalline silicon solar cell significantly improves the passivation performance of the solar cell and effectively eliminates hydrogen-induced degradation, thereby effectively improving the reliability and efficiency of the photovoltaic module made using this solar cell during long-term use.

[0049] A photovoltaic module according to this embodiment includes a front panel, a front encapsulation layer, a cell, a back encapsulation layer, and a back panel arranged sequentially from top to bottom. The cell is a crystalline silicon solar cell as described above in this embodiment.

[0050] This embodiment also discloses a photovoltaic system, including one or more photovoltaic modules, wherein the photovoltaic module is one of the photovoltaic modules described above in this embodiment.

[0051] Example 2 The crystalline silicon solar cell, photovoltaic module, and photovoltaic system described in this embodiment are all based on Embodiment 1, except that: This embodiment provides a film structure for a crystalline silicon solar cell, the structure of which and its preparation method specifically include: Step 1: Fabrication of the carrier selectivity layer A second carrier selective layer is prepared on the front and back surfaces of the crystalline silicon substrate 11: N-type single crystal silicon with a resistivity of 0.3~5.0Ω•cm and a thickness of 160μm is selected as the substrate, the crystalline silicon substrate 11 is subjected to damage removal treatment and polishing, and then the second carrier selective layer is formed on both the front and back surfaces of the crystalline silicon substrate 11.

[0052] In the crystalline silicon solar cell film structure of this embodiment, the second carrier selectivity layer includes a tunneling oxide layer 131 and a doped polycrystalline silicon layer 132 sequentially deposited on the surface of the crystalline silicon substrate 11; the tunneling oxide layer 131 is a silicon oxide layer, and the thickness of the tunneling oxide layer 131 is 1.0~2.0 nm; the doped polycrystalline silicon layer 132 is a phosphorus-doped polycrystalline silicon layer with a thickness of 100~150 nm, and the doping concentration of the phosphorus-doped polycrystalline silicon layer is 2.0~3.0E+20cm. -3 .

[0053] Step 2: Fabrication of film structure for crystalline silicon solar cells A first hydrogen barrier layer 161, a hydrogen-rich layer 15, and a second hydrogen barrier layer 162 are deposited sequentially on the second carrier selective layers on the front and rear surfaces of the crystalline silicon substrate 11.

[0054] In the crystalline silicon solar cell film structure of this embodiment, the first hydrogen barrier layer 161 is an intrinsic silicon thin film with a thickness of 20 nm obtained by physical vapor deposition (PVD), the hydrogen-rich layer 15 is a silicon nitride film with a thickness of 60-85 nm, and the second hydrogen barrier layer 162 is an intrinsic silicon thin film with a thickness of 5 nm deposited by PVD. Thus, as shown... Figure 2 The crystalline silicon solar cell film structure shown in this embodiment is referred to as experimental sample 1.

[0055] Example 3 The crystalline silicon solar cell, photovoltaic module, and photovoltaic system described in this embodiment are all based on Embodiment 1, except that: This embodiment provides a film structure for a crystalline silicon solar cell, the structure of which and its preparation method specifically include: Step 1: Fabrication of the carrier selectivity layer A first carrier selective layer 12 is prepared on the front and back surfaces of a single-crystal silicon substrate 11: an N-type single-crystal silicon with a resistivity of 0.3~5.0Ω•cm and a thickness of 160μm is selected as the substrate. The silicon substrate 11 is subjected to a damage removal process and texturing. Then, the silicon substrate 11 is placed in a boron diffusion furnace for boron doping, so as to form the first carrier selective layer 12 on both the front and back surfaces of the silicon substrate 11.

[0056] In the crystalline silicon solar cell film structure of this embodiment, the first carrier selectivity layer 12 is a P-type single crystal doped layer, and the sheet resistance of the P-type single crystal doped layer is 100~150Ω / sq.

[0057] Step 2: Fabrication of film structure for crystalline silicon solar cells On the first carrier selective layer 12 on the front and back surfaces of the crystalline silicon substrate 11, an aluminum oxide film 14 with a thickness of 0.5~5.0 nm is first deposited using the ALD method, and then a first hydrogen barrier layer 161, a hydrogen-rich layer 15, and a second hydrogen barrier layer 162 are deposited sequentially.

[0058] In the crystalline silicon solar cell film structure of this embodiment, the first hydrogen barrier layer 161 is a 5nm thick intrinsic silicon thin film deposited by PVD, the hydrogen-rich layer 15 is a 60-85nm thick silicon nitride film, and the second hydrogen barrier layer 162 is a 30nm thick intrinsic silicon thin film deposited by PVD. Thus, as shown... Figure 3 The crystalline silicon solar cell film structure shown in this embodiment is referred to as experimental sample 2. Example 4 The crystalline silicon solar cell, photovoltaic module, and photovoltaic system described in this embodiment are all based on Embodiment 1, except that: This embodiment provides a film structure for a crystalline silicon solar cell, the structure of which and its preparation method specifically include: Step 1: Fabrication of the carrier selectivity layer A first carrier selective layer 12 and a second carrier selective layer are fabricated on the front and rear surfaces of a monocrystalline silicon substrate 11, respectively. An N-type monocrystalline silicon substrate with a resistivity of 0.3–5.0 Ω•cm and a thickness of 160 μm is selected as the substrate. The substrate 11 undergoes a damage removal process and texturing. Then, the substrate 11 is placed in a boron diffusion furnace for boron doping, thereby forming the first carrier selective layer 12 on both the front and rear surfaces of the substrate 11. In the film structure for crystalline silicon solar cells of this embodiment, the first carrier selective layer 12 is a P-type monocrystalline doped layer, and the sheet resistance of the P-type monocrystalline doped layer is 100–150 Ω / sq.

[0059] Then, the first carrier selective layer 12 on the rear surface of the crystalline silicon substrate 11 is removed by etching, and a second carrier selective layer is then formed on the rear surface of the crystalline silicon substrate 11. In the film structure for crystalline silicon solar cells of this embodiment, the second carrier selective layer includes a tunneling oxide layer 131 and a doped polycrystalline silicon layer 132 sequentially deposited on the rear surface of the crystalline silicon substrate 11; the tunneling oxide layer 131 is a silicon oxide layer, and the thickness of the tunneling oxide layer 131 is 1.0~2.0 nm; the doped polycrystalline silicon layer 132 is a phosphorus-doped polycrystalline silicon layer with a thickness of 100~150 nm, and the doping concentration of the phosphorus-doped polycrystalline silicon layer is 2.0~3.0E+20cm. -3 .

[0060] Step 2: Fabrication of film structure for crystalline silicon solar cells On the first carrier selective layer 12 on the front surface of the crystalline silicon substrate 11, an aluminum oxide film 14 with a thickness of 0.5~5.0 nm is first deposited using the ALD method, and then a first hydrogen barrier layer 161, a hydrogen-rich layer 15, and a second hydrogen barrier layer 162 are deposited sequentially to obtain a hydrogen content control structure located on the front surface of the first carrier selective layer 12.

[0061] In the crystalline silicon solar cell film structure of this embodiment, in the hydrogen content control structure located on the front surface of the first carrier selective layer 12, the first hydrogen barrier layer 161 is an intrinsic silicon thin film with a thickness of 5 nm deposited by PVD, the hydrogen-rich layer 15 is a silicon nitride film with a thickness of 60~85 nm, and the second hydrogen barrier layer 162 is an intrinsic silicon thin film with a thickness of 30 nm deposited by PVD.

[0062] Then, a first hydrogen barrier layer 161, a hydrogen-rich layer 15, and a second hydrogen barrier layer 162 are successively deposited on the second carrier selective layer on the rear surface of the crystalline silicon substrate 11, thereby obtaining a hydrogen content control structure located on the rear surface of the second carrier selective layer.

[0063] In this embodiment of the crystalline silicon solar cell film structure, in the hydrogen content control structure located on the rear surface of the second carrier selectivity layer, the first hydrogen barrier layer 161 is a 20nm thick intrinsic silicon thin film prepared by PVD, the hydrogen-rich layer 15 is a 60-85nm thick silicon nitride film, and the second hydrogen barrier layer 162 is a 5nm thick intrinsic silicon thin film deposited by PVD. Thus, as shown... Figure 4 The crystalline silicon solar cell film structure shown in this embodiment is referred to as experimental sample 3.

[0064] Comparative Example 1 This comparative example describes a film structure for a crystalline silicon solar cell and its preparation method, as well as a crystalline silicon solar cell, photovoltaic module, and photovoltaic system, all based on Example 2. The difference between this example and Example 2 is as follows: After fabricating the carrier-selective layer, a passivation film serving as a hydrogen-rich layer 15 is deposited on both the front and rear surfaces of the crystalline silicon substrate 11 using plasma-enhanced chemical vapor deposition (PECVD). This passivation film is a silicon nitride film with a total thickness of 60–85 nm. Figure 5 The crystalline silicon solar cell film structure shown in this comparative example is referred to as standard control sample 1.

[0065] Comparative Example 2 This comparative example describes a film structure for a crystalline silicon solar cell and its preparation method, as well as a crystalline silicon solar cell, photovoltaic module, and photovoltaic system, all based on Example 3. The difference between this example and Example 3 is as follows: After fabricating the carrier-selective layer, passivation films are deposited on both the front and rear surfaces of the first carrier-selective layer 12 on the crystalline silicon substrate 11. These passivation films consist of an alumina film 14 and a silicon nitride film sequentially deposited on the surface of the first carrier-selective layer 12. The specific deposition process is as follows: first, an alumina film 14 with a thickness of 0.5–5.0 nm is deposited using atomic layer deposition (ALD); then, a silicon nitride film with a thickness of 60–85 nm is deposited using PECVD. This silicon nitride film serves as the hydrogen-rich layer 15. Thus, the desired result is... Figure 6 The crystalline silicon solar cell film structure shown in this comparative example is referred to as standard control sample 2. Comparative Example 3 This comparative example describes a film structure for a crystalline silicon solar cell and its preparation method, as well as a crystalline silicon solar cell, photovoltaic module, and photovoltaic system, all based on Example 4. The difference between this example and Example 4 is that: After the carrier selective layer is prepared, a passivation film is first deposited on the first carrier selective layer 12 on the front surface of the crystalline silicon substrate 11. The passivation film consists of an aluminum oxide film 14 and a silicon nitride film deposited sequentially on the front surface of the first carrier selective layer 12. The specific deposition process is as follows: first, an aluminum oxide film 14 with a thickness of 0.5~5.0 nm is deposited by ALD method, and then a silicon nitride film with a thickness of 60~85 nm is deposited by PECVD method. The silicon nitride film serves as a hydrogen-rich layer 15.

[0066] Then, a passivation film is deposited on the second carrier-selective layer on the rear surface of the crystalline silicon substrate 11; this passivation film is a silicon nitride film with a thickness of 60-85 nm deposited by PECVD, and this silicon nitride film serves as the hydrogen-rich layer 15. Thus, as shown... Figure 7 The crystalline silicon solar cell film structure shown in this comparative example is referred to as standard control sample 3.

[0067] Performance testing 1. Passivation performance test of the film structure for crystalline silicon solar cells in Example 2 and Comparative Example 1: After sample preparation, to further illustrate the regulatory effect of the crystalline silicon solar cell film structure obtained in Example 2 (i.e., experimental group sample 1) on the hydrogen content in crystalline silicon, a Sinton WCT-120 minority carrier lifetime tester was used to test the passivation performance of the standard control group sample 1 and the experimental group sample 1 before and after high-temperature sintering. The passivation performance is generally measured using the open-circuit voltage (iV). oc ) indicates that its data results are as follows Figure 8 As shown.

[0068] It can be seen that the hidden open-circuit voltage iV of the two groups of samples before sintering oc The values ​​were the same, both at 735 mV. However, the standard control group sample 1 (i.e., the crystalline silicon solar cell film structure of Comparative Example 1) without a hydrogen content regulation structure showed a lower iV after sintering. oc The voltage decreased by 5mV. It can be seen that during the sintering process, excess hydrogen in the passivation film entered the surface and bulk regions of its crystalline silicon-passivation contact structure (i.e., the second carrier selective layer), resulting in the formation of new defect states or recombination centers in the bulk region of the passivation contact structure. Therefore, the passivation performance of the standard control group sample 1 showed photothermal decay.

[0069] Meanwhile, experimental group sample 2 (i.e., the crystalline silicon solar cell film structure of Example 2) with hydrogen content regulation structure, after sintering, iV ocThe voltage increased by 7 mV; this proves that in the film structure for crystalline silicon solar cells in Example 2, the hydrogen content regulation structure can effectively control the [H] content at the interface and in the bulk region from the hydrogen-rich layer 15 into the crystalline silicon passivation contact structure (i.e., the second carrier selective layer), thereby effectively improving the passivation effect of the N-type passivation contact structure and effectively avoiding photothermal decay, thus effectively improving the reliability and cell efficiency of crystalline silicon solar cells.

[0070] 2. Passivation performance test of the film structure for crystalline silicon solar cells in Example 3 and Comparative Example 2: After sample preparation, to further illustrate the regulatory effect of the crystalline silicon solar cell film structure obtained in Example 3 (i.e., experimental group sample 2) on the hydrogen content in crystalline silicon, a Sinton WCT-120 minority carrier lifetime tester was used to test the passivation performance of the standard control group sample 2 and the experimental group sample 2 before and after high-temperature sintering. The passivation performance is generally measured using the open-circuit voltage (iV). oc ) indicates that its data results are as follows Figure 9 As shown.

[0071] It can be seen that the hidden open-circuit voltage iV of the two groups of samples before sintering oc The values ​​were the same, both at 701 mV. However, the standard control group sample 2 (i.e., the crystalline silicon solar cell film structure of Comparative Example 2) without a hydrogen content regulation structure showed a higher iV after sintering. oc The voltage increased by only 3 mV; while experimental group sample 2 (i.e., the crystalline silicon solar cell film structure of Example 3) with hydrogen content regulation structure increased by 3 mV after sintering. oc It increased by 9mV.

[0072] It is known that the boron-diffused emitter-P-type single crystal doped layer (i.e., the first carrier selective layer 12) does not belong to the passivation contact structure. Therefore, there is a large number of defect state densities on its surface, which require a large amount of hydrogen for passivation. In the standard control sample 2 without a hydrogen content control structure, 90% of the hydrogen in its passivation film escapes into the air during the sintering process. Therefore, its defect state density reduction effect is limited, and thus the passivation performance of the standard control sample 2 is poor.

[0073] In the experimental sample 2 of Example 3 with the hydrogen content control structure, the hydrogen content control structure effectively prevents hydrogen from escaping from the oxygen-rich layer into the air, which can passivate a large number of defect states on the surface of the P-type single crystal doped layer, thereby effectively reducing its defect state density and improving passivation performance. This proves that in the film structure for crystalline silicon solar cells in Example 3, the hydrogen content control structure can effectively control the [H] content from the hydrogen-rich layer 15 to the interface and bulk region of crystalline silicon, thereby effectively improving the passivation effect of the P-type single crystal doped layer.

[0074] 3. Passivation performance test of the film structure for crystalline silicon solar cells in Example 4 and Comparative Example 3: After sample preparation, to further illustrate the regulatory effect of the crystalline silicon solar cell film structure obtained in Example 4 (i.e., experimental group sample 3) on the hydrogen content in crystalline silicon, a Sinton WCT-120 minority carrier lifetime tester was used to test the passivation performance of the standard control group sample 2 and the experimental group sample 2 before and after high-temperature sintering. Passivation performance is generally measured using the open-circuit voltage (iV). oc ) indicates that its data results are as follows Figure 10 As shown.

[0075] It can be seen that the hidden open-circuit voltage iV of the two groups of samples before sintering oc The values ​​were the same, both at 712 mV. However, the standard control group sample 3 (i.e., the crystalline silicon solar cell film structure of Comparative Example 3) without a hydrogen content regulation structure showed a higher iV after sintering. oc The voltage only increased to 714 mV (an increase of 2 mV); while the experimental group sample 3 (i.e., the crystalline silicon solar cell film structure of Example 4) with hydrogen content regulation structure, after sintering, the voltage increased to 714 mV (an increase of 2 mV); oc The voltage increased to 721 mV (an increase of 7 mV). This demonstrates that in the crystalline silicon solar cell film structure of Example 4, this hydrogen content regulation structure can effectively control the [H] content at the interface and bulk region from the hydrogen-rich layer 15 to the crystalline silicon, thereby effectively improving the passivation effect of the TOPCon cell.

[0076] 4. Photothermal degradation test of the film structure for crystalline silicon solar cells in Example 4 and Comparative Example 3: To further illustrate the effect of the hydrogen content regulation structure in the crystalline silicon solar cell film structure obtained in Example 4 (i.e., experimental sample 3) on the regulation of hydrogen content in crystalline silicon, the metallized standard control group sample 3 and experimental sample 3 cells were encapsulated into photovoltaic modules. Four rounds of photothermal degradation LeTID cycle tests were conducted on the photovoltaic modules to measure the change in power relative to the initial value. Each LeTID test lasted 162 hours at a temperature of 75±3℃, and the applied current was the difference between the short-circuit current and the maximum power point current. The test data results are as follows: Figure 11 As shown.

[0077] As can be seen, the power of the standard control group sample 3 without the hydrogen content regulation structure decreased by 0.19% after 2-3 rounds of LeTID compared to the initial value; while the power of the experimental group sample 3 with the hydrogen content regulation structure steadily increased by 0.52% after 4 rounds of LeTID compared to the initial value. This proves that the hydrogen content regulation structure in the film structure for crystalline silicon solar cells of the present invention can achieve the purpose of eliminating hydrogen-induced degradation of passivated contact solar cells, improving the reliability of cells and photovoltaic modules, and improving the power generation efficiency of photovoltaic modules.

[0078] Although preferred embodiments of the present invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the embodiments of the present invention.

[0079] The technical solution provided by the present invention has been described in detail above. Specific examples have been used to illustrate the principle and implementation of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the idea of ​​the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A film structure for a crystalline silicon solar cell, characterized in that, The device includes a crystalline silicon substrate, wherein a carrier selective layer and a hydrogen content regulating structure are sequentially disposed on the front surface of the crystalline silicon substrate, and a carrier selective layer and a hydrogen content regulating structure are sequentially disposed on the rear surface of the crystalline silicon substrate; the carrier selective layer is a homogeneous structure or a passivated contact structure, and the conductivity type of the carrier selective layer is N-type or P-type; the hydrogen content regulating structure includes a first hydrogen barrier layer for regulating the hydrogen content entering the carrier selective layer, a hydrogen-rich layer for providing hydrogen, and a second hydrogen barrier layer for preventing hydrogen from escaping into the air, which are sequentially stacked on the surface of the carrier selective layer; The first hydrogen barrier layer and the second hydrogen barrier layer are intrinsic amorphous silicon layers or intrinsic polycrystalline silicon layers prepared by physical vapor deposition. The hydrogen-rich layer is a stacked structure formed by one or more of the following: aluminum oxide film, silicon nitride film, silicon oxynitride film, and titanium oxide film.

2. The film structure for a crystalline silicon solar cell according to claim 1, characterized in that, When the carrier selective layer is a homogeneous structure, the thickness of the first hydrogen barrier layer is less than the thickness of the second hydrogen barrier layer.

3. The film structure for a crystalline silicon solar cell according to claim 1, characterized in that, When the carrier selective layer is a passivated contact structure, the thickness of the first hydrogen barrier layer is greater than the thickness of the second hydrogen barrier layer.

4. A film structure for a crystalline silicon solar cell according to any one of claims 1-3, characterized in that, The thickness of both the first hydrogen barrier layer and the second hydrogen barrier layer is less than or equal to 100 nm.

5. The film structure for a crystalline silicon solar cell according to claim 1, characterized in that, The total thickness of the hydrogen-rich layer is 50~150 nm.

6. The film structure for a crystalline silicon solar cell according to claim 1, characterized in that, The homogeneous structure is a single-crystal doped layer prepared by thermal diffusion or ion implantation; the single-crystal doped layer is of P-type or N-type conductivity, and has a sheet resistance of 10~500Ω / sq and a junction depth of 0.3~3μm.

7. The film structure for a crystalline silicon solar cell according to claim 1, characterized in that, The passivated contact structure includes a tunneling oxide layer and a heavily doped polycrystalline silicon layer stacked on the surface of the tunneling oxide layer.

8. The film structure for a crystalline silicon solar cell according to claim 7, characterized in that, The tunneling oxide layer is made of silicon oxide, titanium oxide, or aluminum oxide, and its thickness is 0.5~3.0 nm. The heavily doped polycrystalline silicon layer has an N-type or P-type conductivity, a thickness of 30~600 nm, and a doping concentration of 0.1~8.0E+20cm. -3 .

9. The film structure for a crystalline silicon solar cell according to claim 1, characterized in that, The crystalline silicon substrate is an N-type crystalline silicon substrate.

10. A method for preparing a film structure for a crystalline silicon solar cell according to any one of claims 1-9, characterized in that, The preparation steps include the following: S1. Carrier selective layers are prepared on both the front and back surfaces of a crystalline silicon substrate; S2. Hydrogen content control structures are prepared on the carrier selectivity layers on both the front and back surfaces of a crystalline silicon substrate.

11. A crystalline silicon solar cell, characterized in that, It includes a film structure for a crystalline silicon solar cell as described in any one of claims 1-9, and a metal electrode that forms an ohmic contact with the carrier selective layer.

12. A photovoltaic module, comprising, from top to bottom, a front panel, a front encapsulation layer, a cell, a rear encapsulation layer, and a back panel, characterized in that: The battery is a crystalline silicon solar cell as described in claim 11.

13. A photovoltaic system comprising one or more photovoltaic modules, characterized in that: The photovoltaic module is the photovoltaic module described in claim 12.

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