A crystalline silicon solar cell and a method of manufacturing the same

Abstract

The application discloses a crystalline silicon solar cell and a preparation method thereof, and relates to the technical field of solar cells. The preparation method comprises the following steps: performing cutting treatment on a whole crystalline silicon solar cell to prepare a plurality of split crystalline silicon solar cells with at least one split surface; performing one-time annealing treatment on the split surface of each split crystalline silicon solar cell, the one-time annealing treatment is that the split surface of the split crystalline silicon solar cell is placed on a heating table to prepare a silicon oxide / aluminum oxide composite passivation layer with a thickness of any value in a range of 1 nm to 20 nm; placing the split surface subjected to the one-time annealing treatment on a platform coated with a passivation liquid to perform passivation treatment, and preparing a re-passivation layer with a thickness of any value in a range of 1 nm to 50 nm; and placing the re-passivation layer on a heating table to perform two-time annealing treatment, and preparing the crystalline silicon solar cell. The preparation method has the advantages of low preparation cost, high process compatibility and excellent passivation effect, and can realize industrialization.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of solar cells, in particular to a crystalline silicon solar cell and a preparation method thereof. BACKGROUND

[0002] The crystalline silicon solar cell has high conversion efficiency, mature process and good stability. In the prior art, with the continuous increase of the power of the assembly and the increase of the size of the cell piece, the whole piece of the crystalline silicon solar cell inevitably needs to be mechanically cut in the links of piece preparation and interconnection welding. However, mechanical cutting will form micro-cracks, debris and lattice damage layer at the edge of the cell piece, resulting in high surface state density, increased carrier recombination rate in the area, and further causing problems such as increased recombination current density, reduced open circuit voltage and uneven cell light emission, which seriously affect the photoelectric conversion performance and long-term reliability.

[0003] In order to repair the defects introduced by cutting, the prior art usually adopts the way of thermal annealing or surface passivation treatment. For example, high-temperature annealing is used to promote silicon surface reconstruction and oxide film generation, or atomic deposition process is used to deposit or organic material is used to coat aluminum oxide, silicon nitride and other passivation layers to reduce the surface recombination rate.

[0004] However, the annealing process in the prior art is difficult to balance the cost and adaptability, that is, the traditional oven, sintering furnace or light injection annealing method needs to heat the whole cell piece as a whole, which not only has high energy consumption and complex process, but also has significant differences on different types of crystalline silicon cells, such as HJT (Heterojunction with Intrinsic Thin-layer Solar Cell, intrinsic thin-layer heterojunction crystalline silicon solar cell), PERC (Passivated Emitter and Rear Cell, passivated emitter and rear cell) and TOPCon (Tunnel Oxide Passivated Contact Solar Cell, tunnel oxide passivated contact solar cell), that is, slight deviation of annealing temperature or time will cause degradation of crystal structure or thin film layer, resulting in significant decrease of cell performance. In addition, although the atomic deposition process can realize high-quality aluminum oxide film passivation, it depends on vacuum equipment and high-purity precursors, resulting in high production cost. Although the organic passivation material (such as Nafion) has a simple process, it is difficult to meet the long-term reliability requirements of industrial production due to the lack of thermal stability and mechanical strength.

[0005] Therefore, how to realize efficient and uniform passivation repair of the crack surface while maintaining low cost and high compatibility, and how to balance the stability of the crystal structure and the improvement of the photoelectric performance have become technical problems to be solved in the field. SUMMARY

[0006] One object of the first aspect of the present application is to provide a preparation method of a crystalline silicon solar cell, which solves the technical problem of high cost and small scope of application of edge cutting and passivation treatment of the crystalline silicon solar cell in the prior art.

[0007] Another object of the first aspect of the present application is to further improve the photoelectric performance of the crystalline silicon solar cell.

[0008] An object of the second aspect of the present application is to provide a crystalline silicon solar cell prepared by the above preparation method.

[0009] According to the object of the first aspect of the present application, the present application provides a preparation method of a crystalline silicon solar cell, comprising:

[0010] cutting the whole crystalline silicon solar cell to prepare a plurality of split crystalline silicon solar cells with at least one split surface;

[0011] performing one-time annealing treatment on the split surface of each of the split crystalline silicon solar cells, the one-time annealing treatment being placing the split crystalline silicon solar cell on a heating table and making the split surface adhere to the heating surface of the heating table, to prepare a silicon oxide / aluminum oxide composite passivation layer with a thickness of any value in the range of 1nm-20nm, the top surface of the heating table being provided with an aluminum-based diffusion layer, the temperature of the one-time annealing treatment being any value in the range of 200℃-800℃, and the annealing time being any value in the range of 1s-30min;

[0012] placing the split crystalline silicon solar cell after the one-time annealing treatment on a platform coated with a passivation liquid to perform passivation treatment, to prepare a re-passivation layer with a thickness of any value in the range of 1nm-50nm;

[0013] placing the re-passivation layer on the heating table to perform secondary annealing treatment, to prepare the crystalline silicon solar cell; wherein,

[0014] the annealing temperature of the secondary annealing treatment is less than or equal to the annealing temperature of the one-time annealing treatment, the annealing time of the secondary annealing treatment is any value in the range of 20min-40min, and the pH of the passivation liquid is any value in the range of 3.0-5.0.

[0015] Optionally, the thickness of the silicon oxide in the silicon oxide / aluminum oxide composite passivation layer is any value in the range of 1.5nm-4.0nm.

[0016] Optionally, the annealing temperature of the secondary annealing treatment is any value in the range of 200℃-400℃.

[0017] Optionally, the treatment time of the passivation treatment is any value in the range of 30min-60min.

[0018] Optionally, the material of the re-passivation layer is aluminum oxide or titanium oxide.

[0019] Optionally, when the re-passivation layer is aluminum oxide, the passivation solution is a mixed solution of a trivalent aluminum salt solution and a bicarbonate solution.

[0020] Optionally, the aluminum salt compound in the trivalent aluminum salt solution is any one of aluminum sulfate, aluminum nitrate or aluminum chloride, and the bicarbonate in the bicarbonate solution is any one of potassium bicarbonate, sodium bicarbonate or ammonium bicarbonate.

[0021] Optionally, the concentration of the aluminum sulfate solution in the passivation solution is any one of 0.08 mol / L-0.09 mol / L, and the concentration of the sodium bicarbonate solution is any one of 0.2 mol / L-0.3 mol / L.

[0022] According to the second aspect of the present application, the present application also provides a crystalline silicon solar cell prepared by the preparation method of the crystalline silicon solar cell according to any one of the above.

[0023] Optionally, the crystalline silicon solar cell is any one of an HJT cell, a PERC cell and a TOPCon cell.

[0024] The present application prepares a composite passivation layer and a re-passivation layer on the split surface of a split crystalline silicon solar cell by sequentially performing a first annealing treatment, a passivation treatment and a second annealing treatment, so that the composite passivation layer and the re-passivation layer with a preset thickness are formed on the split surface. That is, the composite passivation layer is prepared by using a heating table to realize local edge annealing, and the re-passivation layer is prepared by using a passivation solution coating method, so that the cutting edge has a double structure of the composite passivation layer and the re-passivation layer. The micro-cracks and defects introduced by cutting are repaired, and the surface recombination inhibition capability and the passivation layer thermal stability are significantly improved, thereby improving the open-circuit voltage, the fill factor and the long-term reliability of the crystalline silicon solar cell. At the same time, the annealing treatment is performed by using a heating table to realize high-quality passivation repair of the cutting edge at low cost and simple process, and the stability of the crystal structure and the improvement of the electrical performance are considered. The aluminum-based diffusion layer of the heating table has high thermal conductivity but limited lateral thermal diffusion depth, so that the heating energy is concentrated in the range of 1mm-2mm of the cutting edge, and the temperature of the main structure of the crystalline silicon cell is almost unchanged, thereby avoiding structural degradation caused by high temperature, and having higher process compatibility and lower failure risk.

[0025] Further, the treatment time of the passivation treatment is any value between 30 min and 60 min, so as to ensure that the active components in the passivation solution fully react with the silicon surface to form a dense and continuous passivation film layer, thereby significantly reducing the interface state density and the surface recombination rate. That is, the growth and solidification process of the re-passivation layer is relatively controllable within the above time range, the film layer thickness and composition uniformity are good, the process cycle is reasonable, the continuous preparation of large-area crystalline silicon wafers is suitable, and the saturation of the silicon surface dangling bond and the stable formation of the Si-O / Al-O bond are promoted, the double effects of interface chemical passivation and charge passivation are improved, thereby improving the key indicators such as minority carrier lifetime and open-circuit voltage.

[0026] The above description is only a summary of the technical solutions of the present application. In order to more clearly understand the technical means of the present application, and to implement the content of the specification, the following will be described in detail with the preferred embodiments of the present application and with the aid of the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0027] Some specific embodiments of the present application will be described in detail hereinafter with reference to the accompanying drawings in an exemplary and non-limiting manner. The same reference signs in the drawings denote the same or similar components or parts. It should be understood by those skilled in the art that the drawings are not necessarily drawn to scale. In the drawings:

[0028] Figure 1 is a schematic flow chart of a preparation method of a crystalline silicon solar cell according to an embodiment of the present application;

[0029] Figure 2 is a schematic structural diagram of a crystalline silicon solar cell according to an embodiment of the present application;

[0030] Figure 3 is a scanning electron microscope image of an n-type monocrystalline silicon wafer according to an embodiment of the present application;

[0031] Figure 4 is an X-ray partial energy spectrum diagram of an n-type monocrystalline silicon wafer according to an embodiment of the present application;

[0032] Figure 5 is a scanning electron microscope image of a composite passivation layer according to an embodiment of the present application;

[0033] Figure 6 is an X-ray partial energy spectrum diagram of a composite passivation layer according to an embodiment of the present application;

[0034] Figure 7 is a scanning electron microscope image of a re-passivation layer prepared according to the present application under different passivation times;

[0035] Figure 8 is a hidden open-circuit voltage-time curve diagram of a re-passivation layer prepared according to the present application under different passivation times;

[0036] Figure 9 is a thickness-passivation time curve diagram of the re-passivation layer prepared according to different passivation times of the present application;

[0037] Figure 10 is a hidden open circuit voltage-annealing temperature curve diagram of the crystalline silicon solar cell prepared according to different annealing temperatures of the one-time annealing treatment of the present application;

[0038] Figure 11 is a hidden open circuit voltage-annealing temperature curve diagram of the crystalline silicon solar cell prepared according to different annealing temperatures of the two-time annealing treatment of the present application;

[0039] Figure 12 is a schematic structural diagram of the TOPCon cell in one embodiment of the present application;

[0040] Figure 13 is a schematic structural diagram of the HJT cell in one embodiment of the present application;

[0041] Figure 14 is a photoluminescence image of the crystalline silicon solar cell prepared according to the embodiment 1 and the comparative examples 3-5 of the present application;

[0042] Figure 15 is a hidden open circuit voltage test diagram of the crystalline silicon solar cell prepared according to the embodiment 1, the embodiment 3-5, and the comparative examples 1, 3-4 and 12-14 of the present application;

[0043] Figure 16 is a pseudo fill factor test diagram of the crystalline silicon solar cell prepared according to the embodiment 1, the embodiment 3-5, and the comparative examples 1, 3-4 and 12-14 of the present application.

[0044] Reference signs:

[0045] 100-crystalline silicon solar cell, 10-split crystalline silicon solar cell, 20-composite passivation layer, 30-re-passivation layer, 200-TOPCon cell, 210-first silicon nitride layer, 220-n-type doped polysilicon layer, 230-silicon oxide layer, 240-first n-type monocrystalline silicon layer, 250-highly doped p-type silicon layer, 260-aluminum oxide layer, 270-second silicon nitride layer, 300-HJT cell, 310-first transparent conductive layer, 320-p-type monocrystalline silicon layer, 330-first intrinsic amorphous silicon layer, 340-n-type crystalline silicon layer, 350-second intrinsic amorphous silicon layer, 360-second n-type monocrystalline silicon layer, 370-second transparent conductive layer. DETAILED DESCRIPTION

[0046] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0047] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, it should be noted that, for ease of description, only the parts relevant to this application are shown in the accompanying drawings, not the entire structure. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this application.

[0048] The terms “comprising” and “having”, and any variations thereof, used in this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such process, method, product, or apparatus.

[0049] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0050] Figure 1 This is a schematic flowchart illustrating a method for fabricating a crystalline silicon solar cell according to an embodiment of the present invention. Figure 2 This is a schematic structural diagram of a crystalline silicon solar cell according to an embodiment of the present invention. Figure 3 This is a scanning electron microscope image of an n-type single-crystal silicon wafer according to an embodiment of the present invention. Figure 4 This is a partial X-ray energy spectrum of an n-type single-crystal silicon wafer according to an embodiment of the present invention. Figure 5 This is a scanning electron microscope image of a composite passivation layer according to an embodiment of the present invention. Figure 6 This is a partial X-ray energy spectrum of a composite passivation layer according to an embodiment of the present invention. Figure 7 These are scanning electron microscope (SEM) images of the repassivation layers prepared under different passivation times according to the present invention. Figure 8 This is a hidden open-circuit voltage-time curve of the repassivation layer prepared at different passivation times according to the present invention. Figure 9 This is a graph showing the thickness-passivation time of the repassivation layer prepared according to different passivation times based on the present invention.Figure 10 is a hidden open-circuit voltage- annealing temperature curve diagram of a crystalline silicon solar cell prepared according to the present application by a one-time annealing treatment at different annealing temperatures, Figure 11 is a hidden open-circuit voltage- annealing temperature curve diagram of a crystalline silicon solar cell prepared according to the present application by a two-time annealing treatment at different annealing temperatures.

[0051] It should be noted that in order to provide a passivation treatment method suitable for various crystalline silicon solar cells 100 and low cost, the inventors have tried various annealing methods and passivation treatment methods, such as multiple optimization of annealing methods such as oven, sintering furnace, light injection combined with annealing temperature and annealing time, and the crystalline silicon solar cells 100 prepared thereby will have technical problems such as reduced recombination current density, uneven light emission at the edge of the cell, and significantly reduced cell performance. In addition, when depositing a passivation layer on the cleaved surface of the crystalline silicon solar cell 100, the inventors also tried to immerse the cleaved surface directly in a passivation solution using a solution method, however, this deposition method can reduce the preparation cost to a certain extent, but due to the micro-cracks, damage layer and high surface roughness on the cleaved surface, the surface state density is much higher than that of the main surface, that is, the rough cleaved surface makes it difficult for the passivation solution to wet and form a continuous, non-porous passivation film, and the passivation film may be too thick at the protrusions of the cleaved surface and too thin at the depressions or even not covered. In addition, even if a passivation film is formed on the cleaved surface, the huge surface area below the cleaved surface and the severe lattice damage mean that there are a large number of dangling bonds that need to be purified, and conventional solution methods such as spin coating or brushing are difficult to provide a sufficient amount of purifying material to completely neutralize all these defects, resulting in low passivation efficiency.

[0052] During the related experiments, the inventors found that directly placing the cleaved surface of the crystalline silicon solar cell 100 on a heating table for annealing treatment can improve the photoelectric conversion efficiency of the crystalline silicon solar cell 100 to a certain extent, and at the same time, combining the deposition of the passivation layer with the passivation solution and a large number of experimental verifications can further optimize the photoelectric performance of the crystalline silicon solar cell 100.

[0053] As shown in Figure 1 , the present application provides a preparation method of a crystalline silicon solar cell 100, comprising:

[0054] Step S100: cutting the whole crystalline silicon solar cell to prepare a plurality of split crystalline silicon solar cells 10 having at least one cleaved surface;

[0055] Step S200: sequentially performing a one-time annealing treatment on the cleaved surface of each split crystalline silicon solar cell 10, wherein the one-time annealing treatment comprises placing the split crystalline silicon solar cell 10 on a heating table and making the cleaved surface adhere to the heating surface of the heating table, to prepare a silicon oxide / aluminum oxide composite passivation layer 20 having a thickness of any value in the range of 1 nm to 20 nm (see Figure 2), the top surface of the heating table is provided with an aluminum-based diffusion layer, the temperature of the first annealing treatment is any value in the range of 200-800°C, and the annealing time is any value in the range of 1s-30min;

[0056] Step S300: placing the once-annealed split-crystal silicon solar cell 10 on a platform coated with a passivation liquid to perform a passivation treatment, thereby preparing a re-passivation layer 30 with a thickness of any value in the range of 1-50nm (see Figure 2

[0057] Step S400: placing the re-passivation layer 30 on a heating table to perform a second annealing treatment, thereby preparing a crystalline silicon solar cell 100; wherein the annealing temperature of the second annealing treatment is less than or equal to the annealing temperature of the first annealing treatment, the annealing time of the second annealing treatment is any value in the range of 20-40min, and the pH of the passivation liquid is any value in the range of 3.0-5.0.

[0058] In the method for preparing the crystalline silicon solar cell 100 in this embodiment, first, the whole crystalline silicon solar cell is cut by a cutting process to form a plurality of split-crystal silicon solar cells 10, and each split-crystal silicon solar cell 10 is subjected to a first annealing treatment, a passivation treatment, and a second annealing treatment. That is, after one split-crystal silicon solar cell 10 is subjected to a first annealing treatment, a passivation treatment, and a second annealing treatment on one of its split surfaces, the remaining split surfaces are subjected to a first annealing treatment, a passivation treatment, and a second annealing treatment, and after all split surfaces of one split-crystal silicon solar cell 10 are subjected to a first annealing treatment, a passivation treatment, and a second annealing treatment, a crystalline silicon solar cell 100 is prepared. Here, each split-crystal silicon solar cell 10 has at least one split surface. That is, when each whole crystalline silicon solar cell includes two split-crystal silicon solar cells 10, each split-crystal silicon solar cell 10 has one split surface after cutting. When each whole crystalline silicon solar cell includes four split-crystal silicon solar cells 10, the cutting method is vertical cutting, that is, on the basis of two split pieces, the middle split piece is further split, and the four obtained split-crystal silicon solar cells 10 on the outer sides each have one split surface, and the two split-crystal silicon solar cells 10 in the middle each have two split surfaces.

[0059] In other embodiments, after all split surfaces of the plurality of split-crystal silicon solar cells 10 are subjected to a first annealing treatment, the passivation treatment and the second annealing treatment are performed on all split surfaces subjected to the first annealing treatment.

[0060] ​In the preparation method of the crystalline silicon solar cell 100 in this embodiment, first, the cleavage surface of the split crystalline silicon solar cell 10 is placed on a heating table with an aluminum-based diffusion layer on the top surface to perform a first annealing treatment. By controlling the annealing temperature and annealing time, a silicon oxide / aluminum oxide composite passivation layer 20 with a thickness ranging from 1 nm to 20 nm is prepared. Then, the cleavage surface after the first annealing treatment is placed on a platform coated with a passivation liquid to perform a passivation treatment, and a re-passivation layer 30 with a thickness of any value ranging from 1 nm to 50 nm is prepared. Next, the re-passivation layer 30 is placed on a heating table to perform a second annealing treatment, and by controlling the annealing temperature and annealing time, the crystalline silicon solar cell 100 is prepared. Here, the thickness of the composite passivation layer 20 can be 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, or 20 nm, or any other value within the range of 1 nm to 20 nm. The thickness of the re-passivation layer 30 can be 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, 16 nm, 17 nm, 18 nm, 19 nm, 20 nm, 25 nm, or 50 nm, or any other value within the range of 1 nm to 50 nm.

[0061] In this embodiment, by sequentially performing a first annealing treatment to prepare a composite passivation layer 20, a passivation treatment to prepare a re-passivation layer 30, and a second annealing treatment on the cleavage surface of the split crystalline silicon solar cell 10, a composite passivation layer 20 and a re-passivation layer 30 with a predetermined thickness are formed only on the cleavage surface. That is, the heating table is used to achieve edge local annealing to prepare the composite passivation layer 20, and the preparation of the re-passivation layer 30 is achieved by coating the passivation liquid, so that the cutting edge has a dual structure of the composite passivation layer 20 and the re-passivation layer 30. This not only repairs the micro-cracks and defects introduced by cutting, but also significantly improves the surface recombination inhibition capability and the passivation layer thermal stability, thereby improving the open-circuit voltage, fill factor, and long-term reliability of the crystalline silicon solar cell 100. At the same time, the annealing treatment using the heating table achieves high-quality passivation repair of the cutting edge at low cost and simple process, taking into account the stability of the crystal structure and the improvement of electrical performance. Moreover, the aluminum-based diffusion layer of the heating table has high thermal conductivity but limited lateral heat diffusion depth, so that the heating energy is concentrated only within 1 mm to 2 mm of the cutting edge, without affecting the temperature of the main structure of the crystalline silicon solar cell, thereby avoiding structural degradation caused by high temperature, and having higher process compatibility and lower failure risk.

[0062] As Figures 3 to 6As shown, the composite passivation layer 20 formed after the first annealing treatment contains abundant silicon element and the content of oxygen element and aluminum element is higher than that of the n-type monocrystalline silicon wafer without annealing treatment, indicating that the composite passivation layer 20 after the first annealing treatment forms a composite passivation layer of abundant silicon oxide and aluminum oxide.

[0063] In the embodiment, the crack surface is placed on the heating table with an aluminum-based diffusion layer on the top surface for the first annealing treatment. The local heat conduction characteristics of the heating table are used to perform directional heating only on the cutting edge region, thereby repairing the lattice damage and stress concentration introduced by cutting without affecting the main body region of the battery, ensuring the lattice integrity and stability of the main body of the crystalline silicon. Moreover, by controlling the first annealing temperature and time, a silicon oxide / aluminum oxide composite passivation layer 20 is induced to form on the surface of the crack surface, so that the composite passivation layer 20 has both the chemical passivation ability of silicon oxide and the field effect passivation characteristics of aluminum oxide, effectively inhibiting the surface recombination at the cutting edge and improving the carrier lifetime and open circuit voltage. By coating the passivation liquid on the platform and performing passivation treatment on the crack surface after the first annealing, a uniform re-passivation layer 30 can be further formed on the surface of the composite passivation layer 20. The thickness of the re-passivation layer 30 is moderate, not only compensating for the micro-cracks and passivation layer gaps caused by laser cutting, but also promoting the migration of hydrogen atoms in aluminum oxide to the interface in the subsequent second annealing, thereby realizing the interface re-passivation effect. In addition, through the second annealing treatment, the hydroxyl groups and residual organic ligands in the passivation liquid can be decomposed, and the atomic rearrangement between the aluminum oxide and silicon oxide interfaces can be promoted, forming stable Al-O-Si bonds and improving the thermal stability and long-term illumination reliability of the re-passivation layer 30. That is, the embodiment adopts a combination of local annealing of the heating table and surface treatment of the passivation liquid, without the need for expensive laser annealing or tube furnace heat treatment equipment. Not only does it simplify the process flow and reduce energy costs, but it also realizes directional passivation of the edge region, significantly reducing the thermal stress and structural warping problems caused by full wafer heating.

[0064] In step S200, the thickness of the composite passivation layer 20 is set to any value in the range of 1 nm to 20 nm, and the thickness of the silicon oxide is in the range of 1.5 nm to 4 nm, i.e., the thickness of the silicon oxide in the composite passivation layer 20 can be adjusted by controlling the annealing time and annealing temperature. The thickness of the silicon oxide can be 1.5 nm, 2 nm, 2.5 nm, 3 nm, 3.5 nm, or 4 nm, or any other value in the range of 1.5 nm to 4 nm. In this embodiment, when the thickness of the composite passivation layer 20 is in the above range, the subsequent liquid deposition of the aluminum oxide or titanium oxide passivation layer exhibits better deposition uniformity and passivation performance. Specifically, when the thickness of the silicon oxide as an interface layer is in the range of 1.5 nm to 4 nm, it can effectively block charge tunneling and also not completely isolate charge interaction, thereby forming a charge-coupled enhanced field effect passivation with the subsequent re-passivation layer 30, and charges can still accumulate at the silicon oxide / aluminum oxide interface to enhance the field effect passivation. Moreover, the silicon oxide also functions as a hydrogen diffusion channel and buffer layer, which helps to uniformly distribute hydrogen at the interface and improves the chemical passivation effect. In addition, the ultra-thin composite passivation layer 20 has low surface roughness and good chemical stability after annealing, providing uniform nucleation sites for subsequent liquid deposition, improving the density and adhesion of the deposited layer, and the aluminum oxide surface forms an oxygen-rich terminal after annealing, which is beneficial to the adsorption and condensation reaction of the liquid solution and promotes the uniform deposition of the re-passivation layer 30. In other embodiments, an increase in the thickness of the silicon oxide will reduce the overall fixed charge density and affect the field effect passivation effect.

[0065] In this embodiment, when the thickness of the silicon oxide or aluminum oxide exceeds the above range, the deposition effect of the subsequent passivation layer and the overall passivation performance decrease, i.e., an excessively thick silicon oxide will significantly reduce the probability of charge tunneling, causing the fixed charges in the re-passivation layer 30 to fail to effectively couple to the silicon surface, and the field effect passivation is weakened. At the same time, the role of silicon oxide as a hydrogen diffusion barrier is enhanced, hindering the diffusion of hydrogen to the interface during annealing, resulting in insufficient passivation of interface defects and a decrease in chemical passivation effect. An excessively thick aluminum oxide will introduce a large compressive stress during annealing, causing lattice distortion at the interface and even inducing microcracks or blistering, which destroys the continuity of the subsequent deposited layer. Moreover, the aluminum oxide may have uneven charge distribution after annealing, with a local charge density that is too high, resulting in an unstable surface barrier and affecting the electrochemical behavior during the subsequent liquid deposition of the re-passivation layer 30. Furthermore, an excessively thick composite layer can enhance the surface chemical inertness, making it difficult for the liquid precursor to effectively adsorb, reducing the deposition rate, and causing uneven nucleation, ultimately forming a loose or porous passivation layer.

[0066] In step S200, the temperature of the primary annealing treatment is any value between 200℃ and 800℃, and the annealing time is any value between 1s and 30min. That is, the temperature of the primary annealing treatment can be 200℃, 250℃, 300℃, 350℃, 400℃, 450℃, 500℃, 600℃, 700℃, or 800℃, or any other value between 200℃ and 800℃. The annealing time can be 1s, 30s, 1min, 2min, 3min, 4min, 5min, 10min, 15min, 20min, 25min, or 30min, or any other value between 1s and 30min. In this embodiment, by setting the temperature and annealing time of the primary annealing treatment within the above ranges, not only can the thickness of the composite passivation layer 20 and silicon oxide be controlled, but the passivation effect, stress release, and structural stability can also be considered, thereby significantly improving the carrier lifetime and electrical performance stability of the crystalline silicon solar cell 100.

[0067] like Figure 10 As shown, the hidden open-circuit voltage of the crystalline silicon solar cell 100 prepared under different annealing temperatures after a single annealing treatment is different. Among them, the hidden open-circuit voltage of the crystalline silicon solar cell 100 without a single annealing treatment is the lowest, and the hidden open-circuit voltage of the crystalline silicon solar cell 100 prepared at an annealing temperature of 250℃ is the highest.

[0068] In step S300, by setting the thickness of the repassivation layer 30 to any value between 1 nm and 50 nm, a high negative fixed charge density and excellent chemical passivation effect can be obtained while ensuring that the repassivation layer 30 continuously covers the crack surface. This significantly reduces the carrier recombination rate at the crack surface and improves the open-circuit voltage and edge stability of the crystalline silicon solar cell 100. When the thickness is less than 1 nm, passivation is insufficient; when the thickness exceeds 50 nm, film stress and increased contact resistance are easily introduced.

[0069] In step S400, the annealing temperature of the secondary annealing process is less than or equal to the annealing temperature of the primary annealing process, and the annealing time can be 20 min, 25 min, 30 min, 35 min, or 40 min, or any other value within the range of 20 min to 40 min, so that the secondary annealing process provides sustained energy, improves the film density, and improves the interface, so that the atoms can perform viscous flow or very local rearrangement, thereby reducing micropores and defects, reducing the density of pinholes and defects, adjusting the bond length and bond angle of Si-O, Si-N, etc. to a more stable state, optimizing the chemical bond between the re-passivation layer 30 and the silicon substrate, and reducing the interface state density. In other embodiments, a too high secondary annealing temperature can cause the p-n junction depth in the crystalline silicon solar cell 100 to change, the doping atoms to diffuse excessively, the electrical performance of the cell to deteriorate, and the film to crystallize, which often introduces grain boundaries and reduces the passivation quality. It can also cause excessive aggregation and escape of hydrogen, which can damage the passivation effect, and unnecessary high-temperature heat budget can activate body metal impurities, form new recombination centers, and reduce the body minority carrier lifetime.

[0070] In this embodiment, the annealing time of the secondary annealing process is too short, and the densification and hydrogen stabilization processes described above cannot be fully completed, and the effect is not good. If the annealing time is too long, it is not cost-effective and can have similar risks as high temperatures.

[0071] In this embodiment, the pH of the passivation solution can be 3.0, 3.5, 4.0, 4.5, or 5.0, or any other value within the range of 3.0 to 5.0, so that the reaction rate of each component in the passivation solution remains stable, and a continuous and dense re-passivation layer precursor film can be uniformly generated on the fracture surface, avoiding interface corrosion caused by excessive acidity or coarse precipitation caused by excessive alkalinity, thereby improving the flatness and interface bonding strength of the passivation layer.

[0072] In a further embodiment, the annealing temperature of the secondary annealing process is any value within the range of 200°C to 400°C, i.e., the annealing temperature of the secondary annealing process can be 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, 270°C, 280°C, 290°C, 300°C, 320°C, 340°C, 360°C, 380°C, or 400°C, or any other value within the range of 200°C to 400°C, to achieve the best thermal matching under the thermal stability requirements of different types of crystalline silicon solar cells 100. That is, when the two annealing temperatures are equal, the internal stress and charge distribution of the re-passivation layer can be further homogenized. When the secondary annealing temperature is lower, it can effectively avoid cracks or peeling of the composite passivation layer 20 due to high-temperature reheating, while promoting the removal of hydroxyl groups within the film and the rearrangement of the interface structure, thereby obtaining a more dense and thermally stable passivation structure, and significantly improving the carrier lifetime and device stability at the fracture surface.

[0073] As shown in Figure 11 , the open-circuit voltages of the crystalline silicon solar cells 100 prepared under different annealing temperature conditions of the secondary annealing process are different, wherein the open-circuit voltage of the crystalline silicon solar cell 100 without the secondary annealing process is the lowest, and the open-circuit voltage of the crystalline silicon solar cell 100 prepared when the annealing temperature is 250°C is the highest.

[0074] In a further embodiment, the treatment time of the passivation process is any value in the range of 30min-60min, i.e. the treatment time of the passivation process can be 30min, 35min, 40min, 45min, 50min, 55min or 60min, or any other value in the range of 30min-60min. In this embodiment, the time range of the passivation process described above can ensure that the active components in the passivation solution fully react with the silicon surface to form a dense and continuous passivation film layer, thereby significantly reducing the interface state density and the surface recombination rate. That is, the growth and solidification process of the re-passivation layer 30 is relatively controllable in the above-mentioned time range, the film layer thickness and composition uniformity are good, at the same time, the process cycle is reasonable, which is suitable for continuous preparation of large-area crystalline silicon wafers, and can also promote the saturation of the silicon surface dangling bond and the stable formation of Si-O / Al-O bond, improve the dual role of interface chemical passivation and charge passivation, thereby improving the key indicators such as minority carrier lifetime and open-circuit voltage.

[0075] As shown in Figure 7 , a and b respectively represent scanning electron microscope images of different magnifications when the passivation time of the re-passivation layer is 1h, and c and d respectively represent scanning electron microscope images of different magnifications when the passivation time of the re-passivation layer is 4h, it can be known from Figure 7 that when the passivation time is 1h, the thin film thickness of the re-passivation layer obtained is moderate, flat and dense, and the agglomeration is less, while too long passivation time will make the thin film too thick and crack, the thin film appears protrusions, and the agglomeration is serious.

[0076] As shown in Figure 8 , a, b and c respectively represent the crystalline silicon solar cells 100 prepared by no annealing process, only passivation process and passivation process followed by secondary annealing process, it can be known from the figure that the performance of the crystalline silicon solar cells 100 prepared by the passivation process in the range of 30min-45min is better.

[0077] In other embodiments, if the passivation time is less than 30min, the film layer may not be formed completely, and the passivation effect is insufficient, while if the time is greater than 60min, it may lead to excessive densification of the film layer structure, stress accumulation or component peroxide, thereby increasing the potential barrier of the carrier passing through the interface and reducing the passivation performance.

[0078] As shown in Figure 9As shown, the thickness of the re-passivation layer 30 linearly increases with the increase of passivation time. As can be seen from the figure, the film thickness of the re-passivation layer 30 is about 15 nm when the deposition time is 30-45 min.

[0079] In a further embodiment, the material of the re-passivation layer 30 is aluminum oxide or titanium oxide, which is flexibly matched according to the type of the battery, so as to realize comprehensive optimization of chemical passivation, charge passivation and optical regulation, thereby significantly improving the surface passivation performance of the battery and the photoelectric conversion efficiency.

[0080] In a further embodiment, when the re-passivation layer 30 is aluminum oxide, the passivation solution is a mixed solution of trivalent aluminum salt solution and bicarbonate solution. The trivalent aluminum salt undergoes hydrolysis reaction in the presence of bicarbonate to generate hydroxy aluminum complex or aluminum hydroxide deposition:

[0081] Al 3+ + 3HCO3 − → Al (OH) 3↓ + 3CO2↑

[0082] The above reaction can be carried out at a low temperature of less than 100°C, so that the re-passivation layer 30 can be deposited on the surface layer of the crack in a mild and controllable chemical manner, thereby avoiding thermal damage to the structure of the crystalline silicon solar cell 100 caused by high temperature.

[0083] In the present embodiment, the Al (OH) 3 generated by the hydrolysis reaction is dehydrated and converted into an aluminum oxide re-passivation layer 30 with uniform structure and strong interfacial adhesion in subsequent secondary annealing treatment, which can effectively cover the microcracks and defects of the crack, prevent interfacial carrier recombination, and form a continuous passivation barrier layer, thereby significantly improving the surface passivation performance. In addition, the bicarbonate ions in the mixed solution play a buffering and weak base catalysis role, which can stabilize the pH of the solution and avoid the problem of rapid precipitation of aluminum salt alone hydrolysis, thereby improving the uniformity of the aluminum oxide film, maintaining the smooth transition of the interfacial chemical bond, and reducing the interfacial stress and microcracks. Here, the passivation solution does not require vacuum deposition equipment, and the preparation of the aluminum oxide layer can be realized by coating, spraying or immersion, which is suitable for low-cost and large-area process application of edge passivation of the crystalline silicon solar cell 100 after slicing, and has high compatibility with the secondary annealing process.

[0084] In a further embodiment, the aluminum salt compound in the trivalent aluminum salt solution is any one of aluminum sulfate, aluminum nitrate or aluminum chloride, and the bicarbonate in the bicarbonate solution is any one of potassium bicarbonate, sodium bicarbonate or ammonium bicarbonate. In this embodiment, by limiting the aluminum salt to be aluminum sulfate, aluminum nitrate or aluminum chloride, and the bicarbonate to be potassium bicarbonate, sodium bicarbonate or ammonium bicarbonate, an optimal balance can be achieved in terms of reaction rate, pH buffering, film density and interfacial adhesion, and an aluminum oxide re-passivation layer 30 with uniform density, strong interfacial adhesion, excellent passivation performance and low process cost can be obtained, significantly improving the passivation quality of the fractured surface of the crystalline silicon solar cell 100 and the overall photoelectric conversion efficiency.

[0085] In a further embodiment, the concentration of the aluminum sulfate solution in the passivation solution is any one of 0.08 mol / L to 0.09 mol / L, i.e. the concentration of the aluminum sulfate solution can be 0.08 mol / L, 0.081 mol / L, 0.082 mol / L, 0.083 mol / L, 0.084 mol / L, 0.085 mol / L, 0.086 mol / L, 0.087 mol / L, 0.088 mol / L or 0.09 mol / L, or any other value within the range of 0.08 mol / L to 0.09 mol / L, and the concentration of the sodium bicarbonate solution is any one of 0.2 mol / L to 0.3 mol / L, i.e. the concentration of the sodium bicarbonate solution can be 0.2 mol / L, 0.21 mol / L, 0.22 mol / L, 0.23 mol / L, 0.24 mol / L, 0.25 mol / L, 0.26 mol / L, 0.27 mol / L, 0.28 mol / L, 0.29 mol / L or 0.3 mol / L, or any other value within the range of 0.2 mol / L to 0.3 mol / L. In this embodiment, by controlling the concentration of the aluminum sulfate solution to be 0.08 mol / L to 0.09 mol / L and the concentration of the sodium bicarbonate solution to be 0.2 mol / L to 0.3 mol / L, an optimal balance can be achieved in terms of reaction rate, film density, solution stability and passivation performance, thereby preparing an aluminum oxide re-passivation layer 30 with smooth surface, controllable thickness, strong interfacial adhesion and excellent electrical passivation performance.

[0086] In this embodiment, the passivation time, pH value and the concentration range of aluminum sulfate and sodium bicarbonate of the re-passivation layer 30 have a clear synergistic effect, i.e. within the specified passivation time range, the aluminum ions and bicarbonate ions in the solution can react at a moderate rate to form a dense Al(OH)3 or Al2O3 transition layer, providing a uniform nucleation interface for the formation of the aluminum oxide re-passivation layer 30, and when the pH is controlled in the range of weak acid to neutral, Al(OH)3 can be effectively inhibited from being converted into Al2O3, and the Al2O3 transition layer can be effectively converted into the aluminum oxide re-passivation layer 30, thereby obtaining an aluminum oxide re-passivation layer 30 with uniform density, strong interfacial adhesion and excellent passivation performance. 3＋The porous structure formed by fast precipitation can avoid the hydrolysis or peeling of the passivation layer under alkaline conditions, so that the generated re-passivation layer 30 is dense and has strong adhesion. Moreover, the ratio range of aluminum sulfate and sodium bicarbonate ensures the slow release balance of Al 3＋ and HCO3 - in the system, so that the reaction rate and the film growth rate are matched, and the passivation layer cracking or pinhole defects caused by local supersaturation are prevented. The synergistic control of the three makes the formed re-passivation layer 30 have high density, good interface adhesion and excellent corrosion resistance, which significantly improves the stability and overall corrosion resistance of the subsequent re-passivation layer 30. In other embodiments, if any parameter exceeds the above range, problems such as loose film layer, poor adhesion or increased surface roughness may occur.

[0087] The application also provides a crystalline silicon solar cell 100 prepared according to the preparation method of the crystalline silicon solar cell 100 of any one of the above. As for the preparation method of the crystalline silicon solar cell 100, it will not be repeated here.

[0088] In a further embodiment, the crystalline silicon solar cell 100 is any one of an HJT cell, a PERC cell or a TOPCon cell. In this embodiment, the above preparation method is applicable to any one of the HJT cell, the PERC cell or the TOPCon cell, has significant structural adaptability and process compatibility, and can realize edge defect repair, interface passivation enhancement, recombination rate inhibition and structure stability improvement in different crystalline silicon solar cell 100 systems, thereby realizing the synergistic technical effects of efficiency improvement, yield improvement and cost reduction.

[0089] Figure 12 is a schematic structural diagram of a TOPCon cell according to an embodiment of the application, Figure 13 is a schematic structural diagram of an HJT cell according to an embodiment of the application.

[0090] As shown in Figure 12 , in this embodiment, the TOPCon cell 200 includes a first silicon nitride layer 210, an n-type doped polysilicon layer 220, a silicon oxide layer 230, a first n-type monocrystalline silicon layer 240, a highly doped p-type silicon layer 250, an aluminum oxide layer 260 and a second silicon nitride layer 270 arranged in a stack from bottom to top, the composite passivation layer 20 is formed on the side wall edge between the first silicon nitride layer 210 and the second silicon nitride layer 270, and the re-passivation layer 30 is formed on the side of the composite passivation layer 20 away from the stack structure and covers the side walls of the first silicon nitride layer 210 and the second silicon nitride layer 270.

[0091] As shown in Figure 13As shown, in the embodiment, the HJT cell 300 includes, from bottom to top, a first transparent conductive layer 310, a p-type monocrystalline silicon layer 320, a first intrinsic amorphous silicon layer 330, an n-type crystalline silicon layer 340, a second intrinsic amorphous silicon layer 350, a second n-type monocrystalline silicon layer 360, and a second transparent conductive layer 370, the composite passivation layer 20 is formed on the side wall edge between the first transparent conductive layer 310 and the second transparent conductive layer 370, and the re-passivation layer 30 is formed on the side of the composite passivation layer 20 away from the stack structure and covers the side walls of the first silicon nitride layer 210 and the second silicon nitride layer 270.

[0092] The technical solutions of the present application will be further described below in combination with specific embodiments.

[0093] In some embodiments, in the preparation method of the crystalline silicon solar cell 100, first, the cleavage surface of the crystalline silicon solar cell 10 is placed on a heating table with an aluminum-based diffusion layer on the top surface for a first annealing treatment, the temperature of the first annealing treatment is any value in the range of 200-800°C, and the annealing time is any value in the range of 1s-30min, by controlling the annealing temperature and the annealing time, a silicon oxide / aluminum oxide composite passivation layer 20 with a thickness in the range of 1-20nm is prepared, then the cleavage surface after the first annealing treatment is placed on a platform coated with a passivation liquid for passivation treatment, the passivation liquid is a mixed solution of a trivalent aluminum salt solution and a bicarbonate solution, a re-passivation layer 30 with a thickness of any value in the range of 1-50nm is prepared, then the re-passivation layer 30 is placed on a heating table for a second annealing treatment, the annealing temperature of the second annealing treatment is any value in the range of 200-400°C, the annealing time of the second annealing treatment is any value in the range of 20-40min, the pH of the passivation liquid is any value in the range of 3.0-5.0, and by controlling the annealing temperature and the annealing time, the crystalline silicon solar cell 100 is prepared.

[0094] Embodiment 1

[0095] First, the cleaved surface of the split crystal silicon solar cell 10 is placed on a heating table provided with an aluminum-based diffusion layer on the top surface to perform a first annealing process, that is, the split crystal silicon solar cell 10 is placed on the heating table, and the cleaved surface is attached to the heating surface of the heating table. The split crystal silicon solar cell 10 is a TOPCon cell 200, the temperature of the first annealing process is 250°C, and the annealing time is 30 min. By controlling the annealing temperature and the annealing time, a silicon oxide / aluminum oxide composite passivation layer 20 with a thickness of 10 nm is prepared. Then, the cleaved surface after the first annealing process is placed on a platform coated with a passivation liquid to perform a passivation process. The passivation liquid is a mixed solution of an aluminum sulfate solution and a sodium bicarbonate solution, and a re-passivation layer 30 with a thickness of 15 nm is prepared. Then, the re-passivation layer 30 is placed on a heating table to perform a second annealing process. The annealing temperature of the second annealing process is lower than that of the first annealing process, that is, the temperature of the second annealing process is 200°C, the annealing time of the second annealing process is 30 min, the pH of the passivation liquid is 3.75, and by controlling the annealing temperature and the annealing time, a crystalline silicon solar cell 100 is prepared.

[0096] Example 2

[0097] Example 2 differs from Example 1 only in that the split crystal silicon solar cell 10 is an HJT cell 300.

[0098] Example 3

[0099] Example 3 differs from Example 1 only in that the annealing temperature of the second annealing process is 150°C.

[0100] Example 4

[0101] Example 4 differs from Example 1 only in that the annealing temperature of the second annealing process is 250°C.

[0102] Example 5

[0103] Example 5 differs from Example 1 only in that the annealing temperature of the second annealing process is 300°C.

[0104] Comparative Example 1

[0105] Comparative Example 1 differs from Example 1 only in that the passivation process is not performed.

[0106] Comparative Example 2

[0107] Comparative Example 2 differs from Example 2 only in that the passivation process is not performed.

[0108] Comparative Example 3

[0109] Comparative Example 3 differs from Example 1 only in that the second annealing process is not performed after depositing the re-passivation layer 30.

[0110] Comparative Example 4

[0111] Comparative Example 4 differs from Example 1 only in that the post-cutting annealing, passivation, and secondary annealing processes are not performed.

[0112] Comparative Example 5

[0113] Comparative Example 5 differs from Example 1 in that the monocrystalline silicon solar cell is not subjected to the cutting process.

[0114] Comparative Example 6

[0115] Comparative Example 6 differs from Example 1 only in that the annealing method for the primary and secondary annealing processes is box-type dark annealing.

[0116] Comparative Example 7

[0117] Comparative Example 7 differs from Example 1 only in that the annealing method for the primary and secondary annealing processes is sintering furnace annealing.

[0118] Comparative Example 8

[0119] Comparative Example 8 differs from Example 1 only in that the annealing method for the primary and secondary annealing processes is vacuum drying oven annealing.

[0120] Comparative Example 9

[0121] Comparative Example 9 differs from Example 1 only in that the annealing method for the primary and secondary annealing processes is green picosecond laser annealing.

[0122] Comparative Example 10

[0123] Comparative Example 10 differs from Example 1 only in that the annealing method for the primary and secondary annealing processes is infrared continuous laser annealing.

[0124] Comparative Example 11

[0125] Comparative Example 11 differs from Example 1 only in that the annealing method for the primary and secondary annealing processes is infrared nanosecond laser annealing.

[0126] Comparative Example 12

[0127] Comparative Example 12 differs from Example 1 only in that the deposition of the re-passivation layer 30 is not performed and the annealing temperature for the secondary annealing process is 150°C.

[0128] Comparative Example 13

[0129] Comparative Example 13 differs from Example 1 only in that the deposition of the re-passivation layer 30 is not performed and the annealing temperature for the secondary annealing process is 250°C.

[0130] Comparative Example 14

[0131] Comparative Example 14 differs from Example 1 only in that the deposition of the re-passivation layer 30 is not performed and the annealing temperature of the secondary annealing process is 300°C.

[0132] Comparative Example 15

[0133] Comparative Example 15 differs from Example 1 only in that the aluminum-based diffusion layer is replaced by a ceramic substrate.

[0134] The optoelectronic properties of the crystalline silicon solar cells 100 prepared in Example 1 and Example 2 were first tested, and the test results are shown in Tables 1 and 2. The SunsVoc test of the TOPCon cell and the HJT cell was performed under the STC conditions specified in the IEC 60904 series of standards:

[0135] Test temperature: 25°C;

[0136] Spectrum: AM1.5;

[0137] Light intensity range: 0.01 suns-2 suns;

[0138] Bulk resistivity: 0.5 Ω·cm;

[0139] Sample type: n-type;

[0140] Instrument model: Sinton SunsVoc-MX.

[0141] When the SunsVoc test was performed on the TOPCon cell or the HJT cell, it was performed under the above-mentioned STC conditions, and the thickness and the cell area of the cell device to be tested were input (the thickness of the TOPCon cell was 120 μm, and the area was 192 cm 2 , the thickness of the HJT cell was 120 μm, and the area was 220 cm 2 ). The corresponding Voc-light intensity curve was obtained, and the pseudo I-V curve and the hidden open circuit voltage in Table 3 were obtained according to the Voc-light intensity curve.

[0142] The IV curve test of the TOPCon cell and the HJT cell was performed under the STC conditions specified in the IEC 60904 series of standards:

[0143] Test temperature: 25°C;

[0144] Spectrum: AM1.5;

[0145] Light intensity: 1 suns;

[0146] Resistivity: 1 Ω·cm;

[0147] Sample type: n-type;

[0148] Instrument model: Sinton FCT650.

[0149] When the IV curve test is performed on the TOPCon cell or the HJT cell, the above STC condition is performed, and the thickness and the cell area of the cell device to be tested are input (the thickness of the TOPCon cell is 120 μm, and the area is 192 cm 2 The thickness of the HJT cell is 120 μm, and the area is 220 cm 2 ), the corresponding I-V curve is obtained, the open circuit voltage, the short circuit current, the photoelectric conversion efficiency, the measured fill factor and the series resistance in Table 1 and Table 2 are obtained according to the I-V curve, and the pseudo fill factor is obtained in combination with the above pseudo I-V curve.

[0150]

[0151]

[0152] As shown in Table 1 and Table 2, the open circuit voltage and the quasi-steady-state photovoltage of the cut silicon solar cell 10 in the TOPCon cell 200 prepared in Example 1 and the HJT cell 300 prepared in Example 2 after the first annealing treatment, the passivation treatment and the second annealing treatment are obviously higher than the photoelectric performance of the silicon solar cell 100 prepared in Comparative Example 1 and Comparative Example 2 without passivation treatment, which indicates that the passivation treatment cooperates with the first annealing treatment and the second annealing treatment to improve the overall photoelectric performance of the silicon solar cell 100.

[0153] In addition, as shown in Table 1, the short circuit current, the measured fill factor and the photoelectric conversion efficiency of Example 1 are obviously higher than those of Comparative Example 15, which indicates that the aluminum-based diffusion layer during the first annealing treatment provides aluminum elements during the formation of the composite passivation layer 20 to further improve the passivation effect of the crack surface and improve the photoelectric performance of the silicon solar cell 100.

[0154] Figure 14 is a photoluminescence image of the silicon solar cell prepared according to Example 1 and Comparative Examples 3-5 of the present application, Figure 15 is a hidden open circuit voltage test diagram of the silicon solar cell prepared according to Example 1, Example 3-5 and Comparative Examples 1, Comparative Examples 3-4 and Comparative Examples 12-14 of the present application, Figure 16 is a pseudo fill factor test diagram of the silicon solar cell prepared according to Example 1, Example 3-5 and Comparative Examples 1, Comparative Examples 3-4 and Comparative Examples 12-14 of the present application.

[0155] Then, the photoluminescence test is performed on the silicon solar cell prepared according to Example 1 and Comparative Examples 3-5, and the test results as shown in Figure 14 are obtained.

[0156] like Figure 14 As shown, (a), (b), (c), and (d) are photoluminescence images corresponding to Comparative Example 5, Comparative Example 4, Comparative Example 3, and Example 1, respectively. Observing the changes in luminescence intensity in the edge region, it can be seen that the edges of the cut cells in Comparative Examples 3-5 are significantly darker, while the edge luminescence of the cells in Example 1 is more uniform, and the dark area is reduced, that is, the high recombination area of ​​charge carriers in the cell is reduced. This indicates that the crystalline silicon solar cell prepared by the passivation treatment combined with the first annealing treatment and the second annealing treatment in Example 1 has a higher photoelectric conversion efficiency.

[0157] The open-circuit voltage of the crystalline silicon solar cells prepared in Example 1 and Comparative Examples 6-11 was tested, and the test results are shown in Table 3.

[0158]

[0159] As shown in Table 3, the open-circuit voltage difference of the crystalline silicon solar cell 100 prepared in Example 1 before and after passivation is 2.09mV, which is significantly higher than that of Comparative Examples 6-11. This means that the photoelectric performance of the crystalline silicon solar cell 100 prepared in Example 1 is better than that of Comparative Examples 6-11, indicating that the annealing effect of the heating stage is significantly better than other annealing methods.

[0160] The photoelectric performance of the crystalline silicon solar cells 100 prepared in Examples 1, 3-5, 1, 3-4, and 12-14 was tested, and the results were as follows: Figure 15 and Figure 16 The test results are shown.

[0161] like Figure 15 and Figure 16 As shown, the crystalline silicon solar cells 100 prepared in Examples 1 and 3-5, after undergoing a first annealing treatment, a passivation treatment, and a second annealing treatment, showed an increase in open-circuit voltage of 2.3 mV and a 0.5% increase in pseudo-fill factor. This indicates that the combined first annealing treatment, passivation treatment, and second annealing treatment in this embodiment can significantly improve the photoelectric performance of the crystalline silicon solar cells 100.

[0162] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above 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.

[0163] The above embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the patent. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, several modifications and improvements can be made, which are within the scope of protection of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A method of fabricating a crystalline silicon solar cell, characterized by, The preparation method comprises the following steps: cutting the whole crystal silicon solar cell to obtain a plurality of split crystal silicon solar cells with at least one split surface; carrying out a first annealing treatment on the split surface of each split crystal silicon solar cell, wherein the split crystal silicon solar cell is placed on a heating table, and the split surface is attached to the heating surface of the heating table, to obtain a silicon oxide / aluminum oxide composite passivation layer with a thickness of any value in the range of 1 nm-20 nm, the top surface of the heating table is provided with an aluminum-based diffusion layer, the temperature of the first annealing treatment is any value in the range of 200℃-800℃, and the annealing time is any value in the range of 1 s-30 min; placing the split crystal silicon solar cell subjected to the first annealing treatment on a platform coated with a passivation liquid to carry out a passivation treatment, to obtain a re-passivation layer with a thickness of any value in the range of 1 nm-50 nm; carrying out a second annealing treatment on the re-passivation layer on the heating table, to obtain the crystal silicon solar cell; wherein the annealing temperature of the second annealing treatment is less than or equal to the annealing temperature of the first annealing treatment, the annealing time of the second annealing treatment is any value in the range of 20 min-40 min, and the pH of the passivation liquid is any value in the range of 3.0-5.

0.

2. The preparation method of the crystal silicon solar cell according to claim 1, wherein the thickness of the silicon oxide in the silicon oxide / aluminum oxide composite passivation layer is any value in the range of 1.5 nm-4.0 nm.

3. The preparation method of the crystal silicon solar cell according to claim 2, wherein the annealing temperature of the second annealing treatment is any value in the range of 200℃-400℃.

4. The preparation method of the crystal silicon solar cell according to claim 3, wherein the treatment time of the passivation treatment is any value in the range of 30 min-60 min.

5. The preparation method of the crystal silicon solar cell according to any one of claims 1-4, wherein the material of the re-passivation layer is aluminum oxide or titanium oxide.

6. The preparation method of the crystal silicon solar cell according to claim 5, wherein when the re-passivation layer is aluminum oxide, the passivation liquid is a mixed solution of a trivalent aluminum salt solution and a bicarbonate solution.

7. The preparation method of the crystal silicon solar cell according to claim 6, wherein the aluminum salt compound in the trivalent aluminum salt solution is any one of aluminum sulfate, aluminum nitrate or aluminum chloride, and the bicarbonate in the bicarbonate solution is any one of potassium bicarbonate, sodium bicarbonate or ammonium bicarbonate.

8. The preparation method of the crystal silicon solar cell according to claim 7, wherein the concentration of the aluminum sulfate solution in the passivation liquid is any value in the range of 0.08 mol / L-0.09 mol / L, and the concentration of the sodium bicarbonate solution is any value in the range of 0.2 mol / L-0.3 mol / L. The crystal silicon solar cell is prepared by the preparation method of the crystal silicon solar cell according to any one of claims 1-8.

10. The crystal silicon solar cell according to claim 9, wherein ​ ​ ​ ​ ​ 9. A crystalline silicon solar cell, characterized by, ​ ​ The crystalline silicon solar cell is any one of an HJT cell, a PERC cell, and a TOPCon cell. The crystalline silicon solar cell is any one of an HJT cell, a PERC cell, and a TOPCon cell.

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