Solar cell with P-type TOPCon passivation structure and preparation method and application thereof

Abstract

The invention relates to a solar cell with a P-type TOPCon passivation structure and a preparation method and application thereof. The solar cell with the P-type TOPCon passivation structure sequentially comprises a silicon substrate, an aluminum oxide layer, a first boron-doped polycrystalline silicon layer, a silicon oxide layer, a second boron-doped polycrystalline silicon layer, a passivation layer and a metal electrode. The aluminum oxide layer is used as a tunneling oxide layer, so that selective passing of holes can be realized, and the efficiency of the solar cell is further improved. And a large amount of boron sources can be prevented from being doped into the silicon substrate in the junction pushing oxidation process, the recombination center of the silicon substrate is reduced, and the passivation performance is improved. Besides, compared with the nitrogen silicide layer, the silicon oxide layer has small obstruction on boron source doping diffusion, so that the boron source concentration of the first boron-doped polycrystalline silicon layer and the boron source concentration of the second boron-doped polycrystalline silicon layer are more balanced, and the problem that internal and external work functions of the tunneling oxide layer are not matched is avoided. The silicon oxide layer can be grown on the first boron-doped polycrystalline silicon layer without additional equipment investment, so that the manufacturing cost is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cells, and in particular to a solar cell with a P-type TOPCon passivation structure and a preparation method and application thereof. Background Art

[0002] In crystalline silicon solar cells, there is serious recombination in the metal-semiconductor contact area, which has become an important factor restricting the efficiency development of crystalline silicon solar cells. One of the biggest advantages of TOPCon passivated structure solar cells is that they have a tunneling oxide layer passivation contact structure (p-poly structure) consisting of a tunneling oxide layer and a doped polysilicon layer, which can significantly reduce the recombination in the metal contact area and have good contact performance, which can greatly improve the efficiency of solar cells.

[0003] The existing TOPCon passivation structure of solar cells is as follows Figure 1 As shown, it includes: a silicon oxide layer (tunnel oxide layer) 2, a doped polysilicon layer 3, a passivation layer 4 and a metal electrode 5 which are sequentially stacked on a silicon substrate 1. The metal electrode 5 penetrates the passivation layer 4 and contacts the doped polysilicon layer 3.

[0004] In addition, there is a double poly structure TOPCon passivation structure solar cell, its structure is as follows Figure 2 As shown, it includes: a silicon oxide layer (tunneling oxide layer) 2, a first boron-doped polysilicon layer 31, a nitride silicide layer 32, a second boron-doped polysilicon layer 33, a passivation layer 4 and a metal electrode 5 which are sequentially stacked on a silicon substrate 1.

[0005] It can be seen that the core structure of the solar cell with TOPCon passivation structure is an ultra-thin silicon oxide layer (tunneling oxide layer), which can utilize the quantum tunneling effect to allow electrons to pass smoothly and prevent holes from recombination. However, when this technology is applied to P-type TOPCon passivation structure solar cells, it ignores the positive charge characteristics of silicon oxide itself, which will inhibit the tunneling of holes and is not conducive to improving the efficiency of P-type TOPCon passivation structure solar cells. Moreover, for solar cells with TOPCon passivation structure with double poly structure, its silicide layer 32 cannot be completed during the growth of poly layer, and additional equipment investment is required. In addition, this film layer greatly hinders the doping of boron source from the outer layer into the inner layer. The concentration of inner poly boron source is low, resulting in mismatch between the internal and external work functions of the tunneling oxide layer. Summary of the invention

[0006] Based on this, it is necessary to provide a P-type TOPCon passivation structure solar cell and its preparation method and application to address the above problems, so as to enhance the selective passage of holes, optimize the internal and external work functions of the tunneling oxide layer and reduce the production cost.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is: a P-type TOPCon passivation structure solar cell, comprising: Silicon substrate; an aluminum oxide layer, wherein the aluminum oxide layer is disposed on the surface of the silicon substrate; a first boron-doped polysilicon layer, wherein the first boron-doped polysilicon layer is disposed on a surface of the aluminum oxide layer; a silicon oxide layer, wherein the silicon oxide layer is disposed on a surface of the first boron-doped polysilicon layer; a second boron-doped polysilicon layer, wherein the second boron-doped polysilicon layer is disposed on a surface of the silicon oxide layer; A passivation layer, wherein the passivation layer is disposed on a surface of the second boron-doped polysilicon layer; A metal electrode penetrates the passivation layer and contacts the second boron-doped polysilicon layer.

[0008] In one embodiment, the thickness of the aluminum oxide layer is 1.2nm-1.6nm.

[0009] In one embodiment, the thickness of the aluminum oxide layer is 1.4 nm.

[0010] In one embodiment, the thickness of the first boron-doped polysilicon layer is 60nm-80nm, the thickness of the silicon oxide layer is 1nm-3nm, and the thickness of the second boron-doped polysilicon layer is 100nm-120nm.

[0011] In one of the embodiments, in one of the embodiments, the thickness of the first boron-doped polysilicon layer is 70 nm, the thickness of the silicon oxide layer is 2 nm, and the thickness of the second boron-doped polysilicon layer is 110 nm.

[0012] Another embodiment discloses a method for preparing a solar cell with a P-type TOPCon passivation structure, the method comprising: providing a silicon substrate; Pre-treating the silicon substrate; performing alkaline polishing on the silicon substrate; forming an aluminum oxide layer on the surface of the silicon substrate; Depositing a first intrinsic amorphous silicon layer on the surface of the aluminum oxide layer; growing a silicon oxide layer on the surface of the first intrinsic amorphous silicon layer; Depositing a second intrinsic amorphous silicon layer on the surface of the silicon oxide layer; Performing boron diffusion on the first intrinsic amorphous silicon layer and the second intrinsic amorphous silicon layer to form a first boron-doped polysilicon layer and a second boron-doped polysilicon layer; forming a passivation layer on the surface of the second intrinsic amorphous silicon layer; A metal electrode is fabricated on the passivation layer.

[0013] In one embodiment, the process of forming an aluminum oxide layer on the surface of the silicon substrate includes: An aluminum oxide layer is formed on the surface of the silicon substrate by using a precursor containing an aluminum source and an oxygen source and utilizing LPCVD, PECVD, PEALD or APCVD.

[0014] In one embodiment, the thickness of the aluminum oxide layer is 1.2nm-1.6nm.

[0015] In one embodiment, the thickness of the first boron-doped polysilicon layer is 60nm-80nm, the thickness of the silicon oxide layer is 1nm-3nm, and the thickness of the second boron-doped polysilicon layer is 100nm-120nm.

[0016] The invention also discloses the application of the solar cell with the P-type TOPCon passivation structure in a photovoltaic module.

[0017] In the solar cell with a P-type TOPCon passivation structure disclosed in the present invention, an aluminum oxide layer is used as a tunneling oxide layer, which can realize the selective passage of holes, thereby improving the efficiency of the solar cell with a P-type TOPCon passivation structure. Due to the presence of the aluminum oxide layer, it is also possible to avoid a large amount of boron source doping into the silicon substrate during the push-junction oxidation process, reduce the recombination center of the silicon substrate, improve the passivation performance, and effectively improve the efficiency of the solar cell with a P-type TOPCon passivation structure from another perspective. In addition, the silicon oxide layer has less resistance to the diffusion of boron source doping than the nitride silicon layer, which makes the boron source concentration in the first boron-doped polysilicon layer and the second boron-doped polysilicon layer more balanced, thereby avoiding the problem of mismatch between the internal and external work functions of the tunneling oxide layer. Moreover, the silicon oxide layer can be grown on the first boron-doped polysilicon layer without the need for additional equipment investment, thereby reducing the production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic diagram of the structure of an existing P-type TOPCon passivation structure solar cell; Figure 2 A schematic diagram of another existing P-type TOPCon passivation structure solar cell; Figure 3 A schematic diagram of the structure of a solar cell with a P-type TOPCon passivation structure disclosed in an embodiment of the present invention.

[0019] In the figure: 1. silicon substrate; 2. silicon oxide layer (tunneling oxide layer); 3. doped polysilicon layer; 4. passivation layer; 5. metal electrode; 21. aluminum oxide layer; 31. first boron-doped polysilicon layer; 32. nitride silicide layer; 33. second boron-doped polysilicon layer; 321. silicon oxide layer. DETAILED DESCRIPTION

[0020] For ease of understanding of the present invention, the present invention will be described in more detail below. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the embodiments or examples described herein. On the contrary, the purpose of providing these embodiments or examples is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific implementation methods or embodiments, and are not intended to limit the present invention. The optional scope of the term "and / or" used herein includes any one of two or more related listed items, and also includes any and all combinations of related listed items, and the combinations include any two related listed items, any more related listed items, or all related listed items.

[0022] One embodiment of the present invention discloses a P-type TOPCon passivation structure solar cell, such as Figure 3 As shown, the P-type TOPCon passivation structure solar cell includes: Silicon substrate 1; An aluminum oxide layer 21, wherein the aluminum oxide layer 21 is disposed on the surface of the silicon substrate 1; A first boron-doped polysilicon layer 31, wherein the first boron-doped polysilicon layer 31 is disposed on the surface of the aluminum oxide layer 21; A silicon oxide layer 321, wherein the silicon oxide layer 321 is disposed on the surface of the first boron-doped polysilicon layer 31; A second boron-doped polysilicon layer 33, wherein the second boron-doped polysilicon layer 33 is disposed on the surface of the silicon oxide layer 321; A passivation layer 4, wherein the passivation layer 4 is disposed on the surface of the second boron-doped polysilicon layer 33; A metal electrode 5 , wherein the metal electrode 5 penetrates the passivation layer 4 and contacts the second boron-doped polysilicon layer 33 .

[0023] The aluminum oxide layer 21 is used as a tunneling oxide layer of the cell structure. The other overall structures of the solar cell with a P-type TOPCon passivation structure disclosed in this embodiment are not limited, and all types of solar cell structures with a P-type TOPCon passivation structure are applicable.

[0024] In the solar cell with a P-type TOPCon passivation structure disclosed in this embodiment, the aluminum oxide layer 21 is used as a tunneling oxide layer. Based on the characteristics of the aluminum oxide layer 21 itself, it can achieve selective passage of holes, thereby improving the efficiency of the solar cell with a P-type TOPCon passivation structure.

[0025] In addition, considering the segregation of boron sources in silicon and silicon oxide, a large amount of boron sources will exist in the tunneling oxide layer formed by silicon oxide in the prior art. Especially in the push-junction oxidation process, a large amount of boron sources will be doped into the silicon substrate, and the entry of excessive boron sources will lead to an increase in Auger recombination, and ultimately lead to a decrease in passivation performance.

[0026] The solar cell with a P-type TOPCon passivation structure disclosed in this embodiment is made of aluminum oxide to make a tunneling oxide layer. Since the boron source has a small segregation coefficient in aluminum oxide, a large amount of boron source will not accumulate in the tunneling oxide layer disclosed in this embodiment. Therefore, in the process of push-junction oxidation, a large amount of boron source can be prevented from being doped into the silicon substrate, reducing the recombination center of the silicon substrate, improving the passivation performance, and on the other hand, effectively improving the efficiency of the solar cell with a P-type TOPCon passivation structure.

[0027] In addition, the solar cell with a P-type TOPCon passivation structure disclosed in this embodiment is also a double poly structure. However, the difference from the prior art is that between the first boron-doped polysilicon layer 31 and the second boron-doped polysilicon layer 33 of the solar cell with a P-type TOPCon passivation structure disclosed in this embodiment is a silicon oxide layer 321. The silicon oxide layer 321 can be grown on the first boron-doped polysilicon layer 31 without the need for additional equipment investment, which can reduce its production cost. And the silicon oxide layer 321 has less resistance to the diffusion of boron source doping than the nitride silicide layer 32, which makes the boron source concentration in the first boron-doped polysilicon layer 31 and the second boron-doped polysilicon layer 33 more balanced, thereby avoiding the problem of mismatch between the work function inside and outside the tunneling layer.

[0028] In another embodiment, the thickness of the aluminum oxide layer is 1.2 nm-1.6 nm. Specifically, the thickness of the aluminum oxide layer can be 1.2 nm, 1.6 nm, 1.3 nm, 1.4 nm, 1.5 nm, etc., which can be determined according to actual conditions in specific applications or production processes, and is not specifically limited here.

[0029] In another embodiment, the thickness of the first boron-doped polysilicon layer 31 is 60nm-80nm, the thickness of the silicon oxide layer 321 is 1nm-3nm, and the thickness of the second boron-doped polysilicon layer 33 is 100nm-120nm. Specifically, the thickness of the first boron-doped polysilicon layer 31 is 70nm, the thickness of the silicon oxide layer 321 is 2nm, and the thickness of the second boron-doped polysilicon layer 33 is 110nm.

[0030] Another embodiment of the present invention discloses a method for preparing a solar cell with a P-type TOPCon passivation structure, the method comprising: A silicon substrate is provided.

[0031] The silicon substrate is pretreated. The pretreatment process includes but is not limited to the following steps: Texturing: The silicon substrate is cleaned with hot alkali and hydrogen peroxide, and the alkali is used to anisotropically corrode the silicon substrate to form a dense pyramid structure on the surface of the silicon substrate to reduce the reflection of sunlight.

[0032] Diffusion: After cleaning and texturing, the PN junction, the core structure of the solar cell, is made on the silicon substrate through a boron diffusion process, and sufficient boron source is deposited in the BSG layer (borosilicate glass layer) as a laser doping source.

[0033] SE: The high temperature of the laser is used to melt the boron and silicon in the BSG layer, so that the boron source diffuses into the silicon substrate to form a heavily doped area, while other areas remain unchanged, thus obtaining a selective emitter structure.

[0034] Thermal oxidation: Through tubular thermal oxidation, a silicon oxide film is grown on the emitter of the silicon substrate to repair the oxide layer lost after SE. It can isolate the alkali and silicon reaction during alkaline polishing, thereby protecting the PN junction.

[0035] BSG removal: Use chain-type PSG removal equipment, protect the BSG (borosilicate glass layer) on the front diffusion surface with a water film, and remove the BSG on the back non-diffusion surface with a roller and HF solution.

[0036] The silicon substrate is subjected to alkali polishing. That is, a high-concentration alkali solution is used to react with the surface of the silicon substrate without BSD on the non-diffusion surface to form a polished surface with high reflectivity. For the alkali polishing process, the present embodiment provides an alkaline solution containing 1.50%-2.70% alkali solution (such as NaOH, KOH, etc.), 1.20%-1.75% polishing additive, and 96.1%-96.75% water, the reaction time is 150s-350s, and the reaction temperature is 57°C-75°C.

[0037] An aluminum oxide layer is formed on the surface of the silicon substrate.

[0038] Specifically, the above process uses a precursor containing an aluminum source and an oxygen source, and utilizes LPCVD (low pressure chemical vapor deposition), PECVD (plasma enhanced chemical vapor deposition), PEALD (plasma enhanced atomic layer deposition) or APCVD (atmospheric pressure chemical vapor deposition) to form an aluminum oxide layer on the surface of the silicon substrate.

[0039] Taking the PECVD process as an example, H2O / O3 (water-oxygen mixture) and TMA (trimethylaluminum) are used as precursors. Specifically, the temperature is controlled at 280℃-310℃; the H2O / O3 pulse time is 6s-8s, the purge time is 12s-16s, and the process flow rate is 20sccm-25sccm; the TMA pulse time is 5.5s-7.5s, the purge time is 11s-14s, and the process flow rate is 22sccm-27sccm.

[0040] Preferably, the thickness of the aluminum oxide layer is controlled to be 1.2 nm-1.6 nm.

[0041] A first intrinsic amorphous silicon layer is deposited on the surface of the aluminum oxide layer.

[0042] A silicon oxide layer is grown on the surface of the first intrinsic amorphous silicon layer.

[0043] A second intrinsic amorphous silicon layer is deposited on the surface of the silicon oxide layer.

[0044] Boron is diffused into the first intrinsic amorphous silicon layer and the second intrinsic amorphous silicon layer to form a first boron-doped polysilicon layer and a second boron-doped polysilicon layer.

[0045] Among them, the deposition temperature of the first intrinsic amorphous silicon layer and the second intrinsic amorphous silicon layer is 550℃-570℃, the thickness of the first intrinsic amorphous silicon layer is 60nm-80nm, and the thickness of the second intrinsic amorphous silicon layer is 100nm-120nm; the preparation temperature of the silicon oxide layer is 590℃-610℃, and the thickness of the silicon oxide layer is 1nm-3nm; the deposition temperature of boron diffusion is 810℃-870℃, the deposition time is 400s-600s, the boron source flow rate is 100sccm-350sccm, the oxidation flow rate is 450sccm-1000sccm, the nitrogen flow rate is 2400sccm-3500sccm, the advancement temperature is 910℃-930℃, the time is 1000s-2000s, the oxidation temperature is 910℃-930℃, the time is 2000s-3000s, the oxidation flow rate is 18000sccm-25000sccm, and the doping concentration is 3e 19 -6e 19 .

[0046] A passivation layer is formed on the surface of the second boron-doped polysilicon layer. The passivation layer is a silicon oxide layer or a composite layer of silicon oxide and aluminum nitride, and its manufacturing method is also one of the processes such as LPCVD, PECVD, PEALD or APCVD.

[0047] A metal electrode is fabricated on the passivation layer, the doped polysilicon layer is exposed by laser grooving, and the metal electrode is fabricated by screen printing.

[0048] In the method for preparing a solar cell with a P-type TOPCon passivation structure disclosed in this embodiment, the aluminum oxide layer is used as a tunneling oxide layer, which can achieve the selective passage of holes, thereby improving the efficiency of the solar cell with the P-type TOPCon passivation structure. In addition, the tunneling oxide layer made of aluminum oxide can also avoid a large amount of boron source doping into the silicon substrate during the push-junction oxidation process, reduce the recombination center of the silicon substrate, improve the passivation performance, and effectively improve the efficiency of the solar cell with the P-type TOPCon passivation structure from another perspective.

[0049] At the same time, the solar cell with a P-type TOPCon passivation structure disclosed in this embodiment is also a dual-poly structure. However, the difference from the prior art is that the solar cell with a P-type TOPCon passivation structure disclosed in this embodiment has a silicon oxide layer between the first boron-doped polysilicon layer and the second boron-doped polysilicon layer. The silicon oxide layer can be grown on the first boron-doped polysilicon layer without the need for additional equipment investment, which can reduce its production cost. And the silicon oxide layer has less hindrance to the diffusion of boron source doping than the nitride silicide layer, which makes the boron source concentration in the first boron-doped polysilicon layer and the second boron-doped polysilicon layer more balanced, thereby avoiding the problem of mismatch between the work function inside and outside the tunneling layer.

[0050] The following four specific embodiments of P-type TOPCon passivation structure solar cells are compared to verify the advantages of the method disclosed in the present invention and the prepared P-type TOPCon passivation structure solar cells. The following embodiments only capture the key differences, and other parts that are the same or similar to the prior art are not repeated.

[0051] Embodiment 1: The silicon substrate is subjected to alkaline polishing by preparing an alkaline solution containing 2.70% alkaline solution (such as NaOH, KOH, etc.), 1.20% polishing additive, and 96.1% water, with a reaction time of 350 seconds and a reaction temperature of 75°C.

[0052] An aluminum oxide layer was formed on the surface of the silicon substrate. The reaction temperature was 310° C., the H2O pulse time was 8 s, the purge time was 16 s, the process flow rate was 25 sccm, the TMA pulse time was 7.5 s, the purge time was 14 s, the process flow rate was 27 sccm, and the thickness of the aluminum oxide layer was 1.6 nm.

[0053] A first intrinsic amorphous silicon layer is deposited on the surface of the aluminum oxide layer.

[0054] A silicon oxide layer is grown on the surface of the first intrinsic amorphous silicon layer.

[0055] A second intrinsic amorphous silicon layer is deposited on the surface of the silicon oxide layer.

[0056] Boron is diffused into the first intrinsic amorphous silicon layer and the second intrinsic amorphous silicon layer to form a first boron-doped polysilicon layer and a second boron-doped polysilicon layer.

[0057] Among them, the deposition temperature of the first intrinsic amorphous silicon layer and the second intrinsic amorphous silicon layer is 570°C, the thickness of the first intrinsic amorphous silicon layer is 80nm, and the thickness of the second intrinsic amorphous silicon layer is 120nm; the preparation temperature of the silicon oxide layer is 610°C, and the thickness of the silicon oxide layer is 3nm; the deposition temperature of the boron diffusion is 870°C, the deposition time is 600s, the boron source flow rate is 350sccm, the oxidation flow rate is 1000sccm, the nitrogen flow rate is 3500sccm, the advancement temperature is 930°C, the time is 2000s, the oxidation temperature is 930°C, the time is 3000s, the oxidation flow rate is 25000sccm, and the doping concentration is 6e 19 .

[0058] Embodiment 2: The silicon substrate is subjected to alkaline polishing by preparing an alkaline solution containing 1.50% alkaline solution (such as NaOH, KOH, etc.), 1.75% polishing additive, and 96.75% water, with a reaction time of 150 seconds and a reaction temperature of 57°C.

[0059] An aluminum oxide layer is formed on the surface of the silicon substrate. The reaction temperature is 280°C, the H2O pulse time is 6s, the purge time is 12s, the process flow rate is 20sccm, the TMA pulse time is 5.5s, the purge time is 11s, the process flow rate is 22sccm, and the aluminum oxide layer thickness is 1.2nm.

[0060] A first intrinsic amorphous silicon layer is deposited on the surface of the aluminum oxide layer.

[0061] A silicon oxide layer is grown on the surface of the first intrinsic amorphous silicon layer.

[0062] A second intrinsic amorphous silicon layer is deposited on the surface of the silicon oxide layer.

[0063] Boron is diffused into the first intrinsic amorphous silicon layer and the second intrinsic amorphous silicon layer to form a first boron-doped polysilicon layer and a second boron-doped polysilicon layer.

[0064] Among them, the deposition temperature of the first intrinsic amorphous silicon layer and the second intrinsic amorphous silicon layer is 550°C, the thickness of the first intrinsic amorphous silicon layer is 60nm, and the thickness of the second intrinsic amorphous silicon layer is 100nm; the preparation temperature of the silicon oxide layer is 590°C, and the thickness of the silicon oxide layer is 1nm; the deposition temperature of the boron diffusion is 810°C, the deposition time is 400s, the boron source flow rate is 100sccm, the oxidation flow rate is 450sccm, the nitrogen flow rate is 2400sccm, the advancement temperature is 910°C, the time is 1000s, the oxidation temperature is 910°C, the time is 2000s, the oxidation flow rate is 18000sccm, and the doping concentration is 3e 19 .

[0065] Embodiment three: The silicon substrate is subjected to alkaline polishing by preparing an alkaline solution containing 2.20% alkaline solution (such as NaOH, KOH, etc.), 1.40% polishing additive, and 96.4% water, with a reaction time of 220 seconds and a reaction temperature of 68°C.

[0066] An aluminum oxide layer is formed on the surface of the silicon substrate. The reaction temperature is 295°C, the H2O pulse time is 7s, the purge time is 14s, the process flow rate is 22sccm, the TMA pulse time is 6.5s, the purge time is 13s, the process flow rate is 24sccm, and the aluminum oxide layer thickness is 1.4nm.

[0067] A first intrinsic amorphous silicon layer is deposited on the surface of the aluminum oxide layer.

[0068] A silicon oxide layer is grown on the surface of the first intrinsic amorphous silicon layer.

[0069] A second intrinsic amorphous silicon layer is deposited on the surface of the silicon oxide layer.

[0070] Boron is diffused into the first intrinsic amorphous silicon layer and the second intrinsic amorphous silicon layer to form a first boron-doped polysilicon layer and a second boron-doped polysilicon layer.

[0071] Among them, the deposition temperature of the first intrinsic amorphous silicon layer and the second intrinsic amorphous silicon layer is 550°C, the thickness of the first intrinsic amorphous silicon layer is 70nm, and the thickness of the second intrinsic amorphous silicon layer is 110nm; the preparation temperature of the silicon oxide layer is 600°C, and the thickness of the silicon oxide layer is 2nm; the deposition temperature of the boron diffusion is 840°C, the deposition time is 500s, the boron source flow rate is 200sccm, the oxidation flow rate is 700sccm, the nitrogen flow rate is 2800sccm, the advancement temperature is 920°C, the time is 1500s, the oxidation temperature is 920°C, the time is 2500s, the oxidation flow rate is 21000sccm, and the doping concentration is 5e 19 .

[0072] Comparative Example 1: The silicon substrate was subjected to alkaline polishing. The reaction time was 220 s, the reaction temperature was 68°C, and the alkaline solution containing alkaline solution, polishing additive, and H2O was prepared to be 2.2%, 1.4%, and 96.4% respectively.

[0073] A tunneling oxide layer is formed on the surface of the silicon substrate at a deposition temperature of 600° C. and a controlled thickness of 1.4 nm. In this example, the tunneling oxide layer is a silicon oxide layer.

[0074] A first intrinsic amorphous silicon layer is deposited on the surface of the aluminum oxide layer.

[0075] A nitride silicon layer is grown on the surface of the first intrinsic amorphous silicon layer.

[0076] A second intrinsic amorphous silicon layer is deposited on the surface of the nitride silicon layer.

[0077] Boron is diffused into the first intrinsic amorphous silicon layer and the second intrinsic amorphous silicon layer to form a first boron-doped polysilicon layer and a second boron-doped polysilicon layer.

[0078] Among them, the deposition temperature of the first intrinsic amorphous silicon layer and the second intrinsic amorphous silicon layer is 550°C, the thickness of the first intrinsic amorphous silicon layer is 70nm, and the thickness of the second intrinsic amorphous silicon layer is 110nm; the deposition temperature of the nitride silicide layer is 600°C, and the thickness of the nitride silicide layer is 2nm; the deposition temperature of the boron diffusion is 840°C, the deposition time is 500s, the boron source flow rate is 200sccm, the oxidation flow rate is 700sccm, the nitrogen flow rate is 2800sccm, the advancement temperature is 920°C, the time is 1500s, the oxidation temperature is 920°C, the time is 2500s, the oxidation flow rate is 21000sccm, and the doping concentration is 5e 19 .

[0079] In this comparative example, the tunnel oxide layer and the double poly layer are prepared according to the prior art, which is different from the present invention in that the tunnel oxide layer of this embodiment is made of silicon oxide and the middle of the double poly is a silicide layer.

[0080] After 2 batch experiments, the cell iVoc and J0 are determined, see the table below:

[0081] It can be seen that the iVoc of the solar cell with a P-type TOPCon passivation structure manufactured by the method described in the embodiment of the present invention is significantly higher than that of the solar cell with a P-type TOPCon passivation structure manufactured by the method described in Comparative Example 1, and the J0 of the solar cell with a P-type TOPCon passivation structure manufactured by the method described in the embodiment of the present invention is also significantly lower than that of the solar cell with a P-type TOPCon passivation structure manufactured by the method described in Comparative Example 1. That is, the efficiency of the solar cell with a P-type TOPCon passivation structure manufactured by the method described in the embodiment of the present invention is significantly higher than that of the prior art.

[0082] Another embodiment of the present invention discloses an application of a solar cell with a P-type TOPCon passivation structure described in any of the above embodiments in a photovoltaic module. Specifically, the solar cell with a P-type TOPCon passivation structure disclosed in the embodiment of the present invention can be applied to any scene where solar cells can be used, such as power generation in power stations, outdoor lighting, self-contained power supplies, house roofs or exterior walls, and transportation vehicles.

[0083] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0084] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A P-type TOPCon passivation structure solar cell, characterized in that: include: Silicon substrate; an aluminum oxide layer, wherein the aluminum oxide layer is disposed on the surface of the silicon substrate; a first boron-doped polysilicon layer, wherein the first boron-doped polysilicon layer is disposed on a surface of the aluminum oxide layer; a silicon oxide layer, wherein the silicon oxide layer is disposed on a surface of the first boron-doped polysilicon layer; a second boron-doped polysilicon layer, wherein the second boron-doped polysilicon layer is disposed on a surface of the silicon oxide layer; A passivation layer, wherein the passivation layer is disposed on a surface of the second boron-doped polysilicon layer; A metal electrode penetrates the passivation layer and contacts the second boron-doped polysilicon layer.

2. The solar cell with a P-type TOPCon passivation structure according to claim 1, characterized in that: The thickness of the aluminum oxide layer is 1.2nm-1.6nm.

3. The solar cell with a P-type TOPCon passivation structure according to claim 2, characterized in that: The thickness of the aluminum oxide layer is 1.4 nm.

4. The solar cell with a P-type TOPCon passivation structure according to claim 1, characterized in that: The thickness of the first boron-doped polysilicon layer is 60nm-80nm, the thickness of the silicon oxide layer is 1nm-3nm, and the thickness of the second boron-doped polysilicon layer is 100nm-120nm.

5. The solar cell with a P-type TOPCon passivation structure according to claim 4, characterized in that: The thickness of the first boron-doped polysilicon layer is 70 nm, the thickness of the silicon oxide layer is 2 nm, and the thickness of the second boron-doped polysilicon layer is 110 nm.

6. A method for preparing a solar cell with a P-type TOPCon passivation structure, characterized in that: The preparation method comprises: providing a silicon substrate; Pre-treating the silicon substrate; performing alkaline polishing on the silicon substrate; forming an aluminum oxide layer on the surface of the silicon substrate; Depositing a first intrinsic amorphous silicon layer on the surface of the aluminum oxide layer; growing a silicon oxide layer on the surface of the first intrinsic amorphous silicon layer; Depositing a second intrinsic amorphous silicon layer on the surface of the silicon oxide layer; Diffusion of boron is performed on the first intrinsic amorphous silicon layer and the second intrinsic amorphous silicon layer to form a first boron-doped polysilicon layer and a second boron-doped polysilicon layer; forming a passivation layer on the surface of the second intrinsic amorphous silicon layer; A metal electrode is fabricated on the passivation layer.

7. The method for preparing a solar cell with a P-type TOPCon passivation structure according to claim 6, characterized in that: The process of forming an aluminum oxide layer on the surface of the silicon substrate comprises: An aluminum oxide layer is formed on the surface of the silicon substrate by using a precursor containing an aluminum source and an oxygen source and utilizing LPCVD, PECVD, PEALD or APCVD.

8. The method for preparing a solar cell with a P-type TOPCon passivation structure according to claim 6, characterized in that: The thickness of the aluminum oxide layer is 1.2nm-1.6nm.

9. The method for preparing a solar cell with a P-type TOPCon passivation structure according to claim 6, characterized in that: The thickness of the first boron-doped polysilicon layer is 60nm-80nm, the thickness of the silicon oxide layer is 1nm-3nm, and the thickness of the second boron-doped polysilicon layer is 100nm-120nm.

10. Use of a solar cell with a P-type TOPCon passivation structure according to any one of claims 1 to 5 in a photovoltaic module.

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