A crystalline silicon solar cell suitable for space radiation environment and a preparation method thereof

Abstract

The present application relates to the technical field of solar cells, in particular to a crystalline silicon solar cell, especially to a crystalline silicon solar cell suitable for space radiation environment and a preparation method thereof. The present application sets a TOPCon passivation contact structure in a local area of the front surface and / or the back surface, so that the enhanced structure precisely acts on the key area of carrier collection, realizes directional protection of the radiation sensitive area without overall replacement of the overall structure, more effectively slows down the performance attenuation of the battery in the space environment, and the present application sets a transition area between the TOPCon passivation contact structure and the diffusion doped area, so that the doping concentration, carrier concentration or interface state density presents a gradual or equivalent step distribution in space, alleviates the electrical abrupt change between different structure areas, improves the continuity of carrier transport, and further reduces the local recombination risk in the radiation environment.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, specifically to a crystalline silicon solar cell, and more particularly to a crystalline silicon solar cell suitable for space radiation environments and its preparation method. Background Technology

[0002] Crystalline silicon solar cells have long been widely used in the power systems of spacecraft such as satellites and space stations due to their advantages such as high material stability, mature manufacturing process, and rich experience in on-orbit applications. Among them, PERC structure crystalline silicon solar cells based on diffused junctions have demonstrated good reliability and engineering feasibility in both ground and space applications.

[0003] However, the space environment has significantly different physical characteristics compared to terrestrial applications. During the operation of spacecraft in orbit, solar cells will be exposed to high-energy electrons, protons, and other high-energy particle radiation for extended periods. These high-energy particles introduce displacement damage into crystalline silicon materials and their interfaces, generating numerous radiation-induced defects. This leads to a decrease in minority carrier lifetime, enhanced interface recombination, and consequently, a gradual decline in solar cell performance over time.

[0004] In existing diffused crystalline silicon solar cells (such as traditional PERC structures), selective carrier transport primarily relies on the diffused emitter structure and its surface passivation layer. While this type of structure effectively suppresses interfacial recombination under terrestrial application conditions, its passivation effect is easily affected by radiation-induced defects in the space radiation environment. Specifically, high-energy particle radiation introduces new defect states into the silicon surface / bulk region and the material interface, significantly increasing the interfacial state density and thus weakening the passivation effect of the passivation layer on carriers. Especially near the metal contact region, due to the high local electric field and carrier injection density, radiation-induced recombination is more pronounced, becoming one of the main sources of cell performance degradation.

[0005] The TOPCon technology proposed in recent years introduces an ultrathin tunneling silicon oxide layer between crystalline silicon and doped polycrystalline silicon, significantly reducing interfacial recombination rate while maintaining low contact resistance. However, existing TOPCon technologies are mostly applied to high-efficiency ground-based solar cells, typically in large-area or even full-area configurations, using primarily n-type silicon substrates, and are not specifically optimized for space radiation environments. Some existing technologies attempt to introduce localized TOPCon structures, but these often suffer from abrupt transitions between contact and non-contact areas, and insufficient radiation resistance in critical contact areas, making it difficult to effectively mitigate radiation-induced performance degradation while maintaining process maturity and structural reliability.

[0006] Therefore, there is an urgent need for a new technical solution that combines the advantages of traditional diffused crystalline silicon solar cell technology with optimization for key recombination mechanisms under space radiation environment. Summary of the Invention

[0007] The technical problem this invention aims to solve is that in existing diffused crystalline silicon solar cells (such as PERC structures), due to long-term exposure to space radiation, high-energy particles introduce a large number of radiation-induced defects into the silicon material and its interfaces, leading to interface recombination enhancement and a decrease in minority carrier lifetime. This, in turn, causes a significant decay in the cell's open-circuit voltage, short-circuit current, and fill factor over service time, severely impacting the long-term reliability of spacecraft power systems. While existing TOPCon technology offers passivation advantages, it is primarily designed for terrestrial efficiency and lacks structural optimization for the space radiation environment. Furthermore, full-area TOPCon solutions involve complex processes, over-reliance on hydrogen passivation, and pose a failure risk in the space environment.

[0008] To address the aforementioned technical problems, this invention provides a crystalline silicon solar cell suitable for space radiation environments and its preparation method.

[0009] The first aspect of this invention provides a crystalline silicon solar cell suitable for space radiation environments, comprising: p-type crystalline silicon substrate; A first local region and a first non-local region are disposed on the front side of the p-type crystalline silicon substrate, wherein the upper surfaces of the first local region and the first non-local region are not on the same horizontal plane. The second local region and the second non-local region are disposed on the back side of the p-type crystalline silicon substrate, and the upper surfaces of the second local region and the second non-local region are not on the same horizontal plane; A transition region is provided at the boundary between the first local region and the first non-local region and / or at the boundary between the second local region and the second non-local region, and the doping concentration and / or interface state density of the transition region are gradually distributed in the lateral direction; The first local region and / or the second local region include a tunneling silicon oxide layer and a doped polysilicon layer.

[0010] In some embodiments, the resistivity of the p-type crystalline silicon substrate is 0.5–5000 Ω·cm, and the thickness is 30–300 μm.

[0011] In some embodiments, the first local area and / or the second local area are TOPCon passivated contact structures.

[0012] In some embodiments, the doped polysilicon layer in the first local region is n + The doped polysilicon layer in the second local region is a p-type polysilicon layer. + Polycrystalline silicon layer.

[0013] In some embodiments, the first nonlocal region includes, from the inside out, an emitter layer and an anti-reflection passivation layer; the second nonlocal region includes, from the inside out, a p + Diffusion layer, anti-reflection passivation layer.

[0014] In some embodiments, the crystalline silicon solar cell further includes a contact metal, which is at least partially disposed in the TOPCon passivated contact structure.

[0015] In some embodiments, the first local area and / or the second local area are located directly below the metal contact area of ​​the crystalline silicon solar cell, the projection of the TOPCon passivation contact structure in the direction perpendicular to the p-type crystalline silicon substrate coincides with the metal contact area, and the coverage area of ​​the first local area or the second local area on the front and / or back accounts for 2 to 80% of the total surface area.

[0016] In some embodiments, the anti-reflection passivation layer comprises an Al2O3 layer and a SiN layer. x Layer or SiN x O γ At least one of the layers.

[0017] The second aspect of this invention provides a method for preparing a crystalline silicon solar cell, comprising the following steps: S1. Provide a p-type crystalline silicon substrate; S2. A locally doped polysilicon stack structure is formed on the front and / or back sides of the p-type crystalline silicon substrate. The region where the locally doped polysilicon stack structure is located constitutes a first local region and / or a second local region. The region where the locally doped polysilicon stack structure is not formed constitutes a first non-local region and / or a second non-local region. The locally doped polysilicon stack structure includes a tunneling oxide layer and a doped polysilicon layer. S3. A transition region is formed at the boundary between the first local region and the first non-local region and / or at the boundary between the second local region and the second non-local region, wherein the doping concentration of the transition region is gradually distributed in the lateral direction; S4. Perform diffusion doping in the first nonlocal region and / or the second nonlocal region; S5. Prepare the passivation layer and contact metal to obtain the final product.

[0018] In some embodiments, the locally doped polysilicon stacked structure in step S2 is formed by first forming a continuous tunneling oxide layer and a doped polysilicon layer on the front and / or back sides of the p-type crystalline silicon substrate, and then removing a portion of the tunneling oxide layer and the doped polysilicon layer by local etching. or, A tunneling oxide layer and a doped polycrystalline silicon layer are formed directly on localized areas of the front and / or back sides of the p-type crystalline silicon substrate using a selective deposition method.

[0019] In some embodiments, in step S4: phosphorus diffusion occurs in the first nonlocal region to form an n-type emitter layer; boron diffusion occurs in the second nonlocal region to form a p-type diffusion layer.

[0020] In some embodiments, the transition region in step S3 is formed by at least one of the following methods: lateral diffusion of the dopant during a subsequent heat treatment process; or, Gradual changes in deposition thickness or etching depth at the patterned boundary; or, Secondary light doping or ion implantation energy modulation.

[0021] Compared with the prior art, the present invention has the following beneficial technical effects: (1) Significantly reduces radiation-induced interface recombination in space. The present invention introduces TOPCon passivation contact structures in local areas on the front and / or back sides. Through the synergistic effect of the tunneling silicon oxide layer and the doped polycrystalline silicon layer, a more stable interface passivation and carrier selective transport path are formed in the key contact area. Compared with the existing schemes that only use diffusion structures, the present invention can effectively suppress metal recombination and radiation-induced interface recombination, and slow down the decline in minority carrier lifetime caused by radiation damage. (2) Targeted reinforcement of key contact areas is more in line with the characteristics of space radiation damage. The present invention sets TOPCon passivated contact structures only in local areas on the front and / or back (preferably at the corresponding positions of the metal contact areas), so that the reinforcement structure acts precisely on the key areas of carrier collection. Without replacing the entire structure, targeted protection of radiation-sensitive areas is achieved, which can more effectively slow down the performance degradation of the battery in the space environment; (3) Improve radiation resistance stability while maintaining the maturity of the diffusion structure. The present invention introduces a TOPCon passivated contact structure in a local area, while using a non-TOPCon region formed by diffusion doping in other areas. This improves the radiation resistance performance of key areas while maintaining the high compatibility of the overall structure with existing mature processes. Compared with existing solutions, the present invention does not need to be completely replaced with a full-area passivated contact structure to achieve higher long-term stability in the space radiation environment. (4) The transition region improves the electrical continuity between different structural regions. The present invention sets a transition region between the TOPCon passivated contact structure and the diffusion doped region, so that the doping concentration, carrier concentration or interface state density are gradually or equivalently stepped in space, which alleviates the electrical abrupt change between different structural regions, improves the continuity of carrier transport, and further reduces the risk of local recombination under radiation environment; (5) It helps to mitigate performance degradation during space service. In the space radiation environment, the present invention can more effectively suppress the impact of radiation-induced defects on the interface and contact area. The technical effects are as follows: compared with the existing diffusion-type scheme, the retention rate of key electrical parameters of the battery after irradiation is higher; the performance degradation rate with service time is reduced; and it helps to extend the effective service life of crystalline silicon solar cells for space use. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of the present invention.

[0023] Wherein: 1—p-type crystalline silicon substrate; 2—first localized region; 2-3—tunneling silicon oxide layer; 21—doped polycrystalline silicon layer (front side, n-type); 3—first non-localized region (front diffusion region); 31—emitter layer; 4—second localized region (back TOPCon region); 41—doped polycrystalline silicon layer (back side, p-type); 5—second non-localized region (back diffusion region); 51—p + Diffusion layer; 6—Transition region; 7—Contact metal / metal electrode; 32—Anti-reflection passivation layer; 321—SiN x Layer; 322—AlO x layer. Detailed Implementation

[0024] The present invention will be described in detail below with reference to the accompanying drawings, specific embodiments, and comparative examples. However, the scope of protection of the present invention is not limited to the following embodiments. Equivalent modifications made by those skilled in the art without departing from the concept of the present invention should fall within the scope of protection of the present invention.

[0025] Methods for fabricating locally doped polycrystalline silicon stacked structures: Method 1: First, a continuous tunneling silicon oxide layer 2-3 and doped polysilicon layers 21, 41 are formed on the front and / or back sides of the p-type crystalline silicon substrate 1. Then, a portion of the tunneling silicon oxide layer 2-3 and doped polysilicon layers 21, 41 are removed by local etching. The local etching can be wet chemical etching (such as HF or TMAH solution) or dry plasma etching.

[0026] Method 2: A tunneling silicon oxide layer 2-3 and doped polycrystalline silicon layers 21 and 41 are formed directly on a localized region of the front and / or back sides of a p-type crystalline silicon substrate 1 using selective deposition. Selective deposition can be achieved using mask-assisted deposition (e.g., using SiO2 or SiN). x Hard mask) or patterned deposition method (such as inkjet printing or laser direct writing). The doped polysilicon layers 21 and 41 can be formed by in-situ doping deposition (i.e., introducing dopant source gas simultaneously during deposition), diffusion doping (depositing intrinsic polysilicon and then diffusion), or ion implantation doping.

[0027] The transition region 6 can be prepared in the following ways: Method 1: Lateral diffusion effect of dopant in subsequent heat treatment: During annealing (temperature 800~1050℃, time 5~60 minutes), the dopant (phosphorus or boron) in the local TOPCon region diffuses laterally to the adjacent non-TOPCon diffusion region, forming a gradual distribution of dopant concentration.

[0028] Method 2: Gradual effect of deposition thickness or etching depth at patterned boundaries: During the deposition or etching process, by controlling process parameters (such as the shadow effect of mask edges, the angle dependence of etching rate, etc.), a gradual transition of thickness or depth is naturally formed at the patterned boundaries.

[0029] Method 3: Secondary light doping or ion implantation energy modulation treatment: After the formation of local TOPCon, additional doping distribution is introduced and regulated in the boundary region by secondary light doping or variable energy ion implantation.

[0030] Electrically, this transition region 6 exhibits a gradual or equivalent stepped distribution of doping concentration, carrier concentration, and / or interface state density, thereby achieving smooth carrier transport between different regions.

[0031] The height difference of transition region 6 is the height difference between the reference planes where the first local region 2 and the first non-local region 3 are located, or the height difference between the reference planes where the second local region 4 and the second non-local region 5 are located.

[0032] The diffusion doping method is as follows: Phosphorus diffusion occurs in the first nonlocal region 3 (using POCl3 as the diffusion source, diffusion temperature 800–900℃, diffusion time 20–60 minutes), forming an n-type emitter layer 31 with a sheet resistance of 80–150 Ω / □. Boron diffusion occurs in the second nonlocal region 5 (using BBr3 as the diffusion source, diffusion temperature 900–1050℃, diffusion time 30–90 minutes), forming a p-type emitter layer 31. + The diffusion layer 51 has a sheet resistance of 50–120 Ω / □.

[0033] Those skilled in the art will understand that the order of the steps in forming the locally doped polysilicon stacked structure and the steps in performing diffusion doping can be interchanged, and both can achieve the technical effects of the present invention. For example, diffusion doping can be performed first in the non-local region, and then the TOPCon structure can be formed in the local region; alternatively, the TOPCon structure can be formed first in the local region, and then diffusion doping can be performed in the non-local region.

[0034] Preparation method of anti-reflection passivation layer 32: The anti-reflection passivation layer 32 comprises aluminum oxide (Al2O3, thickness 5-15 nm) and silicon nitride (SiN). x (thickness 60-90 nm) or silicon oxynitride (SiN) x O γ At least one of the following (thickness 60–90 nm); the Al2O3 layer 322 can be formed by atomic layer deposition (ALD), SiN x Layer 321 can be formed by plasma-enhanced chemical vapor deposition (PECVD).

[0035] Preparation method of contact metal 7: The metal electrode 7 is formed above the TOPCon passivation contact structure by screen printing silver paste or silver-aluminum paste and then sintering at a temperature of 700–850°C. The projection of the TOPCon passivation contact structure in the direction perpendicular to the p-type crystalline silicon substrate 1 coincides with the metal contact region 7, ensuring that charge carriers are effectively collected by the metal electrode through the TOPCon passivation contact structure.

[0036] Example 1

[0037] Crystalline silicon solar cells for space applications with localized TOPCon passivated contacts on both the front and back sides.

[0038] A p-type single-crystal silicon substrate 1 with a resistivity of 2 Ω·cm and a thickness of 120 μm was selected.

[0039] S1. Surface Treatment

[0040] The p-type single-crystal silicon substrate 1 was cleaned and texturized. S2. Formation of a tunneling oxide layer and a doped polysilicon layer stack structure. Tunneling silicon oxide layers 2-3, with a thickness of 1-5 nm, are formed on the front and back sides of a p-type single-crystal silicon substrate 1, respectively, and intrinsic polycrystalline silicon and SiO are deposited on them. x The patterned intrinsic TOPCon structure was obtained by masking and wet chemical processing, with a polysilicon layer thickness of 30-400 nm. Through graphical processing, the TOPCon passivated contact structure is retained only in localized locations corresponding to the metal contact areas on the front and back sides; In this region, the first localized region 2 on the front side forms phosphorus atom doping through diffusion, resulting in n + Type-doped polycrystalline silicon layer 21; boron doping is formed by diffusion doping in the second localized region 4 on the back side, forming p + Type-doped polycrystalline silicon layer 41; the first localized region 2 on the front side has a coverage of approximately 15%, and the second localized region 4 on the back side has a coverage of approximately 30%; S3. Transition zone formation Between the TOPCon passivated contact structure on the front and back sides and the adjacent first nonlocal region 3 or second nonlocal region 5, through subsequent heat treatment (annealing temperature 800-950℃, time 10-30 minutes), a transition region 6 with a gradual distribution of doping concentration and interface state density is naturally formed by utilizing the lateral diffusion effect of dopants in doped polycrystalline silicon. The gradient width of the transition region is about 300-2000nm, and the height difference is 300-3000nm. S4. Formation of non-TOPCon areas In the first nonlocal region 3 on the front side, excluding the localized TOPCon passivated contact structure, n is formed through phosphorus diffusion. + Emitter layer 31; p is formed by boron diffusion in the second nonlocal region 5 on the back side. + Diffusion layer 51; S5. Device completed. An anti-reflection passivation layer 32 and a metal electrode 7 are formed on the front and back sides, respectively. The anti-reflection passivation layer 32 consists of AlO₂ from the inside to the outside. x Layer 322, SiN x Layer 321 completes the fabrication of crystalline silicon solar cells.

[0041] Example 2

[0042] An implementation method that only sets local TOPCon passivation contacts on the front side.

[0043] A p-type single-crystal silicon substrate 1 with a resistivity of 5 Ω·cm and a thickness of 100 μm was selected.

[0044] The preparation steps are basically the same as in Example 1, except that: an n-type TOPCon passivation contact structure is only set below the front contact metal 7 region, with a local TOPCon coverage of approximately 20% on the front side; no TOPCon passivation contact structure is set on the back side, but conventional diffusion doping and anti-reflection passivation layer 32 are used instead. The non-TOPCon region on the front side forms an n-type passivation layer through phosphorus diffusion. + Emitter layer 31; p-type electrode is formed on the back side via boron diffusion. + Diffusion layer 51.

[0045] Example 3

[0046] An implementation method that only provides localized TOPCon passivated contacts on the back side.

[0047] A p-type single-crystal silicon substrate 1 with a resistivity of 1 Ω·cm and a thickness of 300 μm was selected.

[0048] The preparation steps are basically the same as in Example 1, except that: a p-type TOPCon passivation contact structure is only set below the back contact metal 7 region, with a local TOPCon coverage of approximately 25% on the back side; the front side is the first non-localized region 3 formed by diffusion doping, without a TOPCon passivation contact structure. The front side is formed by phosphorus diffusion to form n... + Emitter layer 31; the second nonlocal region 5 on the back side forms p through boron diffusion. + Diffusion layer 51.

[0049] Example 4

[0050] Implementation of low-coverage local TOPCon passivation contacts (coverage 5%).

[0051] A p-type single-crystal silicon substrate 1 with a resistivity of 3 Ω·cm and a thickness of 110 μm was selected.

[0052] The preparation steps are basically the same as in Example 1, except that the TOPCon coverage of the front local area is about 5%, and the TOPCon coverage of the back local area is about 10%. The gradient width of the transition region is 500 nm.

[0053] Example 5

[0054] Implementation of high-coverage local TOPCon passivated contacts (70% coverage).

[0055] A p-type single-crystal silicon substrate (1) with a resistivity of 0.8 Ω·cm and a thickness of 80 μm was selected.

[0056] The preparation steps are basically the same as in Example 1, except that the coverage of the first local region 2 on the front side is about 70%, and the coverage of the first local region 4 on the back side is about 65%. The gradient width of the transition region 6 is 500 nm.

[0057] Comparative Example 1

[0058] Traditional PERC cell structure (without TOPCon passivated contact structure).

[0059] A p-type crystalline silicon substrate (resistivity 2 Ω·cm, thickness 120 μm) with the same parameters as in Example 1 was used. A phosphorus diffused emitter structure and SiN were formed on the front side. x Antireflection layer, with only Al2O3 / SiN on the back side. x The passivation layer and local metal contact structure are not provided. TOPCon passivation contact structure is not provided on the front or back, nor is a transition area provided.

[0060] Comparative Example 2

[0061] Local TOPCon batteries without transition regions.

[0062] The same p-type crystalline silicon substrate (resistivity 2 Ω·cm, thickness 120 μm) as in Example 1 was selected. TOPCon passivation contact structures (n-type on the front and p-type on the back, with the same coverage as in Example 1) were formed below the front and back metal contact areas, but the boundary between the contact structure and the diffusion doped region was abrupt, and no doping gradient or equivalent stepped transition region was formed.

[0063] The remaining conditions are the same as in Example 1.

[0064] Comparative Example 3

[0065] Full-area TOPCon contact structure.

[0066] The same p-type crystalline silicon substrate (resistivity 2 Ω·cm, thickness 120 μm) as in Example 1 was used. A full-area (approximately 100% coverage) TOPCon passivated contact structure was formed on both the front and back sides, without any non-TOPCon diffusion regions or transition regions.

[0067] The remaining conditions are the same as in Example 1.

[0068] Comparative Example 4

[0069] It features a full-area TOPCon on the front and a PERC structure on the back.

[0070] The same p-type crystalline silicon substrate (resistivity 2 Ω·cm, thickness 120 μm) as in Example 1 was used. A full-area (100% coverage) n-type TOPCon passivated contact structure was formed on the front side, and a PERC structure (Al₂O₃ / SiN) was used on the back side. x (Passivation layer, local metal contact), no transition area is set.

[0071] The remaining conditions are the same as in Example 1.

[0072] Comparative Example 5

[0073] Traditional BSF (back field) silicon solar cell structure.

[0074] A p-type crystalline silicon substrate (resistivity 2 Ω·cm, thickness 120 μm) with the same parameters as in Example 1 was used. A phosphorus diffused emitter structure and SiN were formed on the front side. x The antireflective layer uses an aluminum back field (Al-BSF) structure on the back side, and no TOPCon passivation contact structure is set on either the front or back side.

[0075] Performance Testing and Comparison

[0076] All the above samples were subjected to high-energy particle irradiation in the same simulated space radiation environment, and their electrical properties were tested before and after irradiation. The irradiation conditions were 1 MeV electron equivalent irradiation and a flux of 1 × 10¹. 5 cm - ².

[0077] The test results are shown in Table 1.

[0078] Table 1. Comparison of electrical performance of crystalline silicon solar cells with different structures before and after irradiation.

[0079] Results analysis: (1) Example 1 (front and back local TOPCon+ transition region) still maintains a high open-circuit voltage (0.668V) and short-circuit current density (39.2mA·cm) after irradiation. - The efficiency retention rate reached 94.4%, with a 2% (2%) and a fill factor (83.3%), making it the best overall performer among all samples.

[0080] (2) Although the initial efficiency of Example 4 (low coverage 5% / 10%) was slightly lower than that of Example 1 (21.79% vs 23.11%), its efficiency retention rate reached 95.3%, which was the highest among all samples. This shows that the local TOPCon structure with lower coverage has better radiation resistance under extreme radiation environment and can achieve the best long-term reliability with minimal structural modifications.

[0081] (3) Example 5 (high coverage 70% / 65%) achieved the highest initial efficiency (23.48%), but the efficiency retention rate after irradiation was relatively low (89.8%), indicating that although excessively high TOPCon coverage is beneficial to improving initial efficiency, it actually reduces long-term stability under space radiation environment. This verifies the rationality of controlling the coverage at 2-80% (preferably 5-70%) in this invention.

[0082] (4) The efficiency retention rate of Comparative Example 1 (traditional PERC) was only 82.3%, and the efficiency dropped sharply from 21.25% to 17.49% after irradiation, indicating that the traditional PERC structure has insufficient radiation resistance in the space radiation environment.

[0083] (5) The efficiency retention rate of Comparative Example 2 (local TOPCon without transition region) was 84.1%, which is better than that of conventional PERC, but significantly lower than that of Example 1 (94.4%). This indicates that in the absence of a transition region, the abrupt boundary between the local TOPCon structure and the diffused doping region becomes a weak link in the recombination enhancement during irradiation, weakening the radiation resistance advantage of the TOPCon structure.

[0084] (6) The efficiency retention rate of Comparative Example 3 (full-area TOPCon) was 85.1%. Although the initial efficiency was high (22.27%), the efficiency dropped to 18.96% after irradiation. This indicates that the long-term stability of the full-area TOPCon structure under space radiation environment is not ideal, which may be related to its over-reliance on hydrogen passivation and the degradation of hydrogen passivation effect under space environment.

[0085] (7) The efficiency retention rate of Comparative Example 4 (front full-area TOPCon + back PERC) was only 82.9%, which was comparable to Comparative Example 1. This indicates that the single-sided full-area TOPCon solution failed to effectively improve the overall radiation resistance of the battery, and the back PERC structure remained a weak link in the radiation damage.

[0086] (8) The efficiency retention rate of Comparative Example 5 (traditional BSF) was only 76.9%, and the initial efficiency and post-irradiation efficiency were the lowest among all samples, indicating that the traditional BSF structure can hardly meet the requirements of modern space missions for the long-term reliability of solar cells.

[0087] The above results indicate that placing a localized TOPCon passivated contact structure below the front and / or back metal contact areas, and forming a transition region with doping gradients or interface state gradients between it and the adjacent diffused doped regions, can effectively suppress irradiation-induced interface recombination enhancement, reduce carrier transport losses, and thus improve the electrical performance retention capability of crystalline silicon solar cells under space radiation environments. Furthermore, controlling the TOPCon coverage to 2–80% (preferably 5–70%) achieves the optimal balance between initial efficiency and long-term stability.

[0088] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A crystalline silicon solar cell suitable for space radiation environments, characterized in that, include: p-type crystalline silicon substrate (1); The first local region (2) and the first non-local region (3) are disposed on the front side of the p-type crystalline silicon substrate (1), and the upper surfaces of the first local region (2) and the first non-local region (3) are not on the same horizontal plane. The second local region (4) and the second non-local region (5) are disposed on the back side of the p-type crystalline silicon substrate (1), wherein the upper surfaces of the second local region (4) and the second non-local region (5) are not on the same horizontal plane. A transition region (6) is provided at the junction of the first local region (2) and the first non-local region (3) and / or at the junction of the second local region (4) and the second non-local region (5), wherein the doping concentration and / or interface state density of the transition region (5) are gradually distributed in the lateral direction; The first local region (2) and / or the second local region (3) includes a tunneling silicon oxide layer (2-3) and a doped polysilicon layer (21, 41).

2. The crystalline silicon solar cell according to claim 1, characterized in that, The p-type crystalline silicon substrate (1) has the following parameters: resistivity of 0.5 to 5000 Ω·cm and thickness of 30 to 300 μm.

3. The crystalline silicon solar cell according to claim 1, characterized in that, The first local area (2) and / or the second local area (3) are TOPCon passivated contact structures.

4. The crystalline silicon solar cell according to claim 2, characterized in that, The doped polysilicon layer (21) in the first local region (2) is n + The doped polysilicon layer (41) in the second local region (4) is a p-type polysilicon layer. + Polycrystalline silicon layer.

5. The crystalline silicon solar cell according to claim 1, characterized in that, The first nonlocal region (3) includes, from the inside out, an emitter layer (31) and an anti-reflection passivation layer (32); the second nonlocal region (5) includes, from the inside out, p + Diffusion layer (51), anti-reflection passivation layer (32).

6. The crystalline silicon solar cell according to claim 3, characterized in that, It also includes a contact metal (7), which is at least partially disposed in the TOPCon passivated contact structure.

7. The crystalline silicon solar cell according to claim 6, characterized in that, The first local area (2) and / or the second local area (3) are located directly below the metal contact area (7) of the crystalline silicon solar cell. The projection of the TOPCon passivation contact structure in the direction perpendicular to the p-type crystalline silicon substrate (1) coincides with the metal contact area (7), and the coverage area of ​​the first local area (2) or the second local area (3) on the front and / or back accounts for 2 to 80% of the total surface area.

8. The crystalline silicon solar cell according to claim 5, characterized in that, The anti-reflection passivation layer (32) comprises an Al2O3 layer and a SiN layer. x Layer or SiN x O γ At least one of the layers.

9. A method for preparing a crystalline silicon solar cell suitable for space radiation environment as described in any one of claims 1 to 8, characterized in that, The method includes the following steps: S1. Provide a p-type crystalline silicon substrate (1); S2. A locally doped polysilicon stack structure is formed on the front and / or back sides of the p-type crystalline silicon substrate (1). The region where the locally doped polysilicon stack structure is located constitutes a first local region (2) and / or a second local region (4). The region where the locally doped polysilicon stack structure is not provided constitutes a first non-local region (3) and / or a second non-local region (5). The locally doped polysilicon stack structure includes a tunneling oxide layer (2-3) and a doped polysilicon layer (21, 41). S3. A transition region (6) is formed at the junction of the first local region (2) and the first non-local region (3) and / or at the junction of the second local region (4) and the second non-local region (5), wherein the doping concentration of the transition region (6) is gradually distributed in the lateral direction; S4. Perform diffusion doping in the first nonlocal region (3) and / or the second nonlocal region (5); S5. Prepare the passivation layer (32) and the contact metal (7) to obtain the final product.

10. The preparation method according to claim 9, characterized in that, The locally doped polysilicon stacked structure described in step S2 is achieved through the following method: First, a continuous tunneling oxide layer (2-3) and a doped polysilicon layer (21, 41) are formed on the front and / or back sides of the p-type crystalline silicon substrate (1), and then a portion of the tunneling oxide layer (2-3) and the doped polysilicon layer (21, 41) are removed by local etching. or, A tunneling oxide layer (2-3) and a doped polycrystalline silicon layer (21, 41) are formed directly on a localized area of ​​the front and / or back side of the p-type crystalline silicon substrate (1) by selective deposition.

11. The preparation method according to claim 9, characterized in that, In step S4: Phosphorus diffusion occurs in the first nonlocal region (3) to form an n-type emitter layer (31). Boron diffusion occurs in the second nonlocal region (5) to form a p-type diffusion layer (51).

12. The preparation method according to claim 9, characterized in that, The transition region (6) described in step (3) is formed in the following manner: Lateral diffusion of dopants during subsequent heat treatment; or, Gradual changes in deposition thickness or etching depth at the patterned boundary; or, Secondary light doping or ion implantation energy modulation.

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