A perc half-cell, method of making the same and photovoltaic system

Abstract

The application provides a perc half-cell and a preparation method thereof and a photovoltaic system, relates to the field of solar cells, and the method comprises the following steps: performing pretreatment on a silicon wafer to obtain a pretreated silicon wafer, cutting the pretreated silicon wafer to obtain two half-cells, and finally performing post-treatment on the half-cells to obtain a perc half-cell; the pretreatment comprises wet texturing and phosphorus diffusion on the N+ layer direction of the silicon wafer; and the post-treatment comprises alkali polishing on the N+ layer direction, the P+ layer direction and the cutting surface of the half-cells. Therefore, the solar cell is no longer affected by the efficiency loss caused by finished product laser cutting, and the power generation efficiency and power of the cell are improved.

Description

Technical Field

[0001] This application relates to the field of solar cells, and more particularly to a PERC half-cell cell, its preparation method, and a photovoltaic system. Background Technology

[0002] After conventional solar cells are manufactured, they are often cut into halves along the central axis for subsequent stringing to form photovoltaic panels. However, the mechanical damage caused during the cutting process is a significant issue. Friction and pressure between the cutting tool and the cell during cutting can damage the cut surface. If the tool is not sharp enough or the cutting parameters (such as speed and pressure) are improperly set, this damage will be exacerbated. Furthermore, the material and thickness of the cell also affect the quality of the cut surface. Harder cells or cells with uneven thickness are more prone to damage during cutting. This mechanical damage to the cut surface increases the recombination current of the cell, leading to a decrease in open-circuit voltage and consequently, a reduction in cell efficiency. On the other hand, the damaged layer may also become a weak point in the cell during long-term operation, making it more susceptible to failure or performance degradation. Cutting a full cell into half results in mechanical damage to the cut surface, leading to a reduction in the efficiency of the half-cell by approximately 0.2-0.4%.

[0003] Therefore, how to prevent solar cells from suffering efficiency losses due to laser cutting of finished products, and thus improve the power generation efficiency and power of the cells, has become an urgent problem to be solved. Summary of the Invention

[0004] The purpose of this application is to provide a PERC half-cell solar cell, its preparation method, and a photovoltaic system to solve the above-mentioned problems.

[0005] To achieve the above objectives, this application adopts the following technical solution:

[0006] This application provides a method for preparing a PERC half-cell battery, comprising: pre-treating a silicon wafer to obtain a pre-treated silicon wafer, then cutting the pre-treated silicon wafer to obtain two half-cell batteries, and finally post-treating the half-cell batteries to obtain a PERC half-cell battery.

[0007] The pretreatment includes wet texturing and phosphorus diffusion in the N+ layer direction of the silicon wafer;

[0008] The post-processing includes alkaline polishing of the N+ layer direction, P+ layer direction, and cut surface of the half-cell.

[0009] Optionally, the cutting is laser cutting, performed along the central axis of the silicon wafer.

[0010] Optionally, the error between the laser cutting line and the central axis of the silicon wafer shall not exceed 100 μm.

[0011] Optionally, during laser cutting, the laser power is 8-15W, the spot width is 30-60μm, and the cutting temperature is 50-70℃.

[0012] Optionally, the sharding method after laser cutting is thermal laser sharding.

[0013] Optionally, the silicon wafer is wet-textured using a texturing solution at 70-85°C for 80-150 seconds. The texturing solution comprises, by volume, 15-20 parts of 40% concentrated NaOH, 2-5 parts of texturing additives, and 400-500 parts of water. The texturing additives include 2-3% tridecyl ether, 0.5-2% acrylamide, 1-3% quaternary ammonium salt, 1-3% disodium tetraacetate, 3-4% alkyl glycoside, 0.3-0.5% sodium benzoate, with the balance being water.

[0014] Optionally, during the phosphorus diffusion process, phosphorus diffusion deposition is first carried out at a temperature of 770-795℃, a pressure of 60-120 mbar, a nitrogen flow rate carrying phosphorus oxychloride of 600-800 sccm / min, and an oxygen flow rate of 500-700 sccm / min for 10-20 min; then, the temperature is increased to 850-880℃, a pressure of 70-150 mbar, and a nitrogen flow rate of 2000-3000 sccm / min for 15-25 min.

[0015] Optionally, after the phosphorus diffusion, the silicon wafer needs to be chain-washed in the N+ layer direction with hydrofluoric acid of 6-15% by mass for 100-200 seconds to remove the phosphorus-silicon glass.

[0016] Optionally, the post-processing further includes cleaning the phosphosilicate glass in the P+ layer direction after alkaline polishing, performing a first reaction in the N+ layer direction of the half-cell to generate an aluminum oxide passivation layer, obtaining a first intermediate morphology; then performing a second reaction in the N+ layer direction of the first intermediate morphology to generate a first silicon nitride layer, obtaining a second intermediate morphology; then performing a third reaction in the P+ layer direction of the second intermediate morphology to generate a second silicon nitride layer, obtaining a third intermediate morphology; then printing a positive electrode and a back electrode on the third intermediate morphology, and sintering to obtain the PERC half-cell.

[0017] Optionally, the alkaline polishing is performed using a polishing slurry at a temperature of 70-80°C for 120-240 seconds. The polishing slurry comprises 12-20 L of NaOH, 2-5 L of additives, and 400-500 L of water. The additives include 3-5% surfactant, 1-2% defoamer, 2-4.5% sodium polystyrene sulfonate, 2-2.5% sodium citrate, 3-5% sodium dodecyl sulfonate and sodium benzoate, with the remainder being water. The surfactant includes sodium polyoxyethylene ether sulfate, and the defoamer includes polyacrylamide or polyvinylpyrrolidone.

[0018] Optionally, the phosphorosilicate glass in the P+ layer direction is cleaned with a cleaning solution for 120-180 seconds; the cleaning solution includes 100-150L of HF and 450-500L of water.

[0019] Optionally, the reaction conditions for the first reaction are: pressure 1600-2200 mtorr, radio frequency power 7000-10000 W, trimethylaluminum flow rate 40-80 sccm / min, nitrous oxide flow rate 4000-7000 sccm / min, and time 80-200 s.

[0020] Optionally, the reaction conditions for the second reaction are: silane flow rate 200-1800 sccm / min, ammonia flow rate 8500-12000 sccm / min, pressure 1500-1800 mtorr, and time 700-1100 s.

[0021] Optionally, the reaction conditions for the third reaction are: silane flow rate 1200-1800 sccm / min, ammonia flow rate 8500-12000 sccm / min, pressure 1500-1800 mtorr, and time 700-1000 s.

[0022] Optionally, the sintering temperature is 750-800℃ and the time is 30-60s.

[0023] Optionally, the thickness of the alumina passivation layer is 6-15 nm.

[0024] Optionally, the thickness of the first silicon nitride layer is 75-90 nm.

[0025] Optionally, the thickness of the second silicon nitride layer is 72-82 nm.

[0026] This application also provides a PERC half-cell battery, which is prepared according to the method for preparing the PERC half-cell battery.

[0027] This application also provides a photovoltaic system including the aforementioned PERC half-cell battery.

[0028] Compared with the prior art, the beneficial effects of this application include:

[0029] The method for preparing PERC half-cell cells provided in this application involves laser cutting of half-cells during the solar cell manufacturing process. By adjusting the laser process, the cutting is changed from finished cell cutting to pre-alkaline polishing cutting. On the one hand, the laser-induced cutting surface damage can be repaired by polishing during the alkaline polishing process, and the cutting edges are etched to remove the mechanical damage layer. On the other hand, after the cutting surface is polished, the alumina grown on the cutting surface can be passivated in the subsequent ALD and coating processes, so that the solar cell is no longer affected by the efficiency loss caused by finished cell laser cutting, thereby improving the power generation efficiency and power of the cell.

[0030] The PERC half-cell solar cells and photovoltaic systems provided in this application have excellent electrical performance and high efficiency. Attached Figure Description

[0031] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation on the scope of this application.

[0032] Figure 1 A schematic diagram of the structure of a PERC half-cell battery provided in the embodiment;

[0033] Figure 2 This is a photograph of the pere half-cell battery prepared in Example 1.

[0034] Key symbols: 100, silicon wafer; 101, N+ emitter; 102, first silicon nitride layer; 103, aluminum oxide passivation layer; 104, second silicon nitride layer; 105, diced surface. Detailed Implementation

[0035] As used in this article:

[0036] "Prepared from" is synonymous with "comprising". The terms "comprising", "including", "having", "containing", or any other variations thereof as used herein are intended to cover non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that includes the listed elements is not necessarily limited to those elements, but may include other elements not expressly listed or elements inherent to such composition, step, method, article, or apparatus.

[0037] The conjunction "composed of..." excludes any unspecified elements, steps, or components. If used in a claim, this phrase makes the claim closed, excluding materials other than those described, except for associated conventional impurities. When the phrase "composed of..." appears in a clause of the body of a claim rather than immediately following it, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0038] When a quantity, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pair of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually. For example, when the range “1–5” is disclosed, the described range should be interpreted as including ranges “1–4”, “1–3”, “1–2”, “1–2 and 4–5”, “1–3 and 5”, etc. When numerical ranges are described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within that range.

[0039] In these embodiments, unless otherwise specified, the portions and percentages are all by weight.

[0040] "Parts by mass" refers to the basic unit of measurement that expresses the mass ratio of multiple components. One part can represent any unit mass, such as 1g or 2.689g. If we say that component A has "a" parts by mass and component B has "b" parts by mass, it means the ratio of the mass of component A to the mass of component B is a:b. Alternatively, it can mean that the mass of component A is aK and the mass of component B is bK (K is any number representing a multiplier). It is important to understand that, unlike the number of parts by mass, the sum of the mass parts of all components is not limited to 100 parts.

[0041] "And / or" is used to indicate that one or both of the described situations may occur, for example, A and / or B includes (A and B) and (A or B).

[0042] To better explain the technical solution provided in this application, the technical solution will be described in its entirety before the embodiments.

[0043] In a first aspect, this application provides a method for preparing a PERC half-cell battery, comprising: pre-treating a silicon wafer to obtain a pre-treated silicon wafer, then cutting the pre-treated silicon wafer to obtain two half-cell batteries, and finally post-treating the half-cell batteries to obtain a PERC half-cell battery.

[0044] The pretreatment includes wet texturing and phosphorus diffusion in the N+ layer direction of the silicon wafer;

[0045] The post-processing includes alkaline polishing of the N+ layer direction, P+ layer direction, and cut surface of the half-cell.

[0046] In an optional embodiment, the cutting is laser cutting, performed along the central axis of the silicon wafer. The silicon wafer is laser-cut in half along its central axis to obtain two half-cells of the same size; the cut surfaces of the half-cells contain laser damage, which can be cleaned and polished in a subsequent alkaline polishing process.

[0047] In one optional embodiment, the error between the laser-cut line and the central axis of the silicon wafer does not exceed 100 μm.

[0048] In one optional embodiment, the laser cutting process uses a laser power of 8-15W, a spot width of 30-60μm, and a cutting temperature of 50-70℃.

[0049] Optionally, the power of the laser can be 8W, 9W, 10W, 11W, 12W, 13W, 14W, or 15W, or any value between 8 and 15W; the width of the laser spot can be 30μm, 35μm, 40μm, 45μm, 50μm, 55μm, or 60μm, or any value between 30 and 60μm; the cutting temperature can be 50℃, 55℃, 60℃, 65℃, or 70℃, or any value between 50 and 70℃.

[0050] In one optional implementation, the cleaving method after laser cutting is thermal laser cleaving.

[0051] In an optional embodiment, the silicon wafer is wet-textured using a texturing solution at 70-85°C for 80-150 seconds. The texturing solution comprises, by volume, 15-20 parts of 40% concentrated NaOH, 2-5 parts of texturing additives, and 400-500 parts of water. The texturing additives include 2-3% tridecyl ether, 0.5-2% acrylamide, 1-3% quaternary ammonium salt, 1-3% disodium tetraacetate, 3-4% alkyl glycosides, 0.3-0.5% sodium benzoate, with the balance being water.

[0052] Optionally, the reaction temperature of the texturing solution during wet texturing can be 70℃, 73℃, 76℃, 79℃, 82℃, 85℃, or any value between 70℃ and 85℃; the wet texturing time can be 80s, 90s, 100s, 110s, 120s, 130s, 140s, 150s, or any value between 80s and 150s.

[0053] In an optional embodiment, the phosphorus diffusion is first carried out at a temperature of 770-795°C, a pressure of 60-120 mbar, a nitrogen flow rate carrying phosphorus oxychloride of 600-800 sccm / min, and an oxygen flow rate of 500-700 sccm / min for 10-20 min; then the temperature is increased to 850-880°C, a pressure of 70-150 mbar, and a nitrogen flow rate of 2000-3000 sccm / min for 15-25 min.

[0054] Optionally, the temperature during phosphorus diffusion deposition can be 770℃, 775℃, 780℃, 785℃, 790℃, 795℃, or any value between 770℃ and 795℃; the reaction pressure can be 60mbar, 70mbar, 80mbar, 90mbar, 100mbar, 110mbar, 120mbar, or any value between 60mbar and 120mbar; the nitrogen flow rate carrying phosphorus oxychloride can be 600sccm / min, 650sccm / min, 700sccm / min, 750sccm / min, 800sccm / min, or 600sccm / min. The oxygen flow rate can be 500 sccm / min, 550 sccm / min, 600 sccm / min, 650 sccm / min, 700 sccm / min, or any value between 500 and 700 sccm / min; the phosphorus diffusion deposition time can be 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, 16 min, 17 min, 18 min, 19 min, 20 min, or any value between 10 and 20 min.

[0055] Optionally, the temperature during propulsion can be 850℃, 855℃, 860℃, 865℃, 870℃, 875℃, 880℃, or any value between 850℃ and 880℃; the pressure during propulsion can be 70mbar, 80mbar, 90mbar, 100mbar, 110mbar, 120mbar, 130mbar, 140mbar, 150mbar, or any value between 70mbar and 150mbar; the nitrogen flow rate can be 2000sccm / min, 2100sccm / min, 2200sccm / min, or 2300s. The speeds are 2400 sccm / min, 2500 sccm / min, 2600 sccm / min, 2700 sccm / min, 2800 sccm / min, 2900 sccm / min, 3000 sccm / min, or any value between 2000 and 3000 sccm / min; the propulsion time can be 15 min, 16 min, 17 min, 18 min, 19 min, 20 min, 21 min, 22 min, 23 min, 24 min, 25 min, or any value between 15 and 25 min.

[0056] In an optional embodiment, after the phosphorus diffusion, the silicon wafer needs to be chain-washed in the N+ layer direction with hydrofluoric acid of 6-15% by mass for 100-200 seconds to remove the phosphorus-silicon glass.

[0057] Optionally, when removing phosphosilicate glass, the mass fraction of the hydrofluoric acid can be 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, or any value between 6% and 15%; the chain pickling time can be 100s, 110s, 120s, 130s, 140s, 150s, 160s, 170s, 180s, 190s, 200s, or any value between 100% and 200s.

[0058] In an optional embodiment, the post-processing further includes cleaning the phosphosilicate glass in the P+ layer direction after alkaline polishing, performing a first reaction in the N+ layer direction of the half-cell to generate an aluminum oxide passivation layer, obtaining a first intermediate morphology; then performing a second reaction in the N+ layer direction of the first intermediate morphology to generate a first silicon nitride layer, obtaining a second intermediate morphology; then performing a third reaction in the P+ layer direction of the second intermediate morphology to generate a second silicon nitride layer, obtaining a third intermediate morphology; then printing a positive electrode and a back electrode on the third intermediate morphology, and sintering to obtain the PERC half-cell.

[0059] In an optional embodiment, the alkaline polishing is performed using a polishing slurry at a temperature of 70-80°C for 120-240 seconds. The polishing slurry comprises 12-20 L of NaOH, 2-5 L of additives, and 400-500 L of water. The additives include 3-5% surfactant, 1-2% defoamer, 2-4.5% sodium polystyrene sulfonate, 2-2.5% sodium citrate, 3-5% sodium dodecyl sulfonate and sodium benzoate, with the remainder being water. The surfactant includes sodium polyoxyethylene ether sulfate, and the defoamer includes polyacrylamide or polyvinylpyrrolidone.

[0060] By adjusting the laser process, the cutting of finished batteries is changed to cutting before alkaline polishing. On the one hand, the damage to the cutting surface caused by the laser can be repaired by polishing during the alkaline polishing process; on the other hand, after the cutting surface is polished, the alumina grown on the cutting surface can be passivated in the subsequent ALD and coating processes.

[0061] Optionally, the temperature during alkaline polishing can be 70℃, 71℃, 72℃, 73℃, 74℃, 75℃, 76℃, 77℃, 78℃, 79℃, 80℃, or any value between 70℃ and 80℃; the reaction time for alkaline polishing can be 120s, 130s, 140s, 150s, 160s, 170s, 180s, 190s, 200s, 210s, 220s, 230s, 240s, or any value between 120s and 240s.

[0062] In an optional embodiment, the phosphorosilicate glass in the P+ layer direction is cleaned with a cleaning solution for 120-180 seconds; the cleaning solution includes 100-150L of HF and 450-500L of water.

[0063] Optionally, the cleaning time can be 120s, 130s, 140s, 150s, 160s, 170s, 180s, or any value between 120 and 180s.

[0064] In an optional embodiment, the reaction conditions for the first reaction are: pressure 1600-2200 mtorr, radio frequency power 7000-10000 W, trimethylaluminum flow rate 40-80 sccm / min, nitrous oxide flow rate 4000-7000 sccm / min, and time 80-200 s. The function of this layer is that the alumina contains a large number of hydrogen bonds, which can provide sufficient hydrogen passivation to the back of the battery, while simultaneously passivating the cut surface.

[0065] Optionally, the pressure in the first reaction can be 1600 mbar, 1700 mbar, 1800 mbar, 1900 mbar, 2000 mbar, 2100 mbar, 2200 mbar, or any value between 1600 and 2200 mbar; the radio frequency power can be 7000 W, 8000 W, 9000 W, 10000 W, or any value between 7000 and 10000 W; the flow rate of trimethylaluminum can be 40 sccm / min, 50 sccm / min, 60 sccm / min, 70 sccm / min, 80 sccm / min, or any value between 40 and 80 sccm / min; the flow rate of nitrous oxide can be 4000 sccm / min, 5000 sccm / min, 6000 sccm / min, 7000 sccm / min, or any value between 4000 and 7000 sccm / min.

[0066] In an optional embodiment, the reaction conditions for the second reaction are: silane flow rate 200-1800 sccm / min, ammonia flow rate 8500-12000 sccm / min, pressure 1500-1800 mtorr, and time 700-1100 s.

[0067] Optionally, the silane flow rate in the second reaction can be 200 sccm / min, 400 sccm / min, 600 sccm / min, 800 sccm / min, 1000 sccm / min, 120 sccm / min, 1400 sccm / min, 1600 sccm / min, 1800 sccm / min, or any value between 200 and 1800 sccm / min; the ammonia flow rate can be 8500 sccm / min, 9000 sccm / min, 9500 sccm / min, 10000 sccm / min. The flow rate can be 10500 sccm / min, 11000 sccm / min, 11500 sccm / min, 12000 sccm / min, or any value between 8500 and 12000 sccm / min; the pressure can be 1500 mbar, 1600 mbar, 1700 mbar, 1800 mbar, or any value between 1500 and 1800 mbar; the reaction time can be 700 s, 800 s, 900 s, 1000 s, 1100 s, or any value between 700 and 1100 s.

[0068] In an optional embodiment, the reaction conditions for the third reaction are: silane flow rate 1200-1800 sccm / min, ammonia flow rate 8500-12000 sccm / min, pressure 1500-1800 mtorr, and time 700-1000 s.

[0069] Optionally, the flow rate of silane in the third reaction can be 1200 sccm / min, 1300 sccm / min, 1400 sccm / min, 1500 sccm / min, 1600 sccm / min, 1700 sccm / min, 1800 sccm / min, or any value between 1200 and 1800 sccm / min; the flow rate of ammonia can be 8500 sccm / min, 9000 sccm / min, 10000 sccm / min, or 10000 sccm / min. The pressure can be 1500 mbar, 1600 mbar, 1700 mbar, 1800 mbar, or any value between 1600 and 1800 mbar; the time can be 700 s, 800 s, 900 s, 1000 s, or any value between 700 and 1000 s.

[0070] In one optional embodiment, the sintering temperature is 750-800°C and the time is 30-60 seconds.

[0071] Optionally, the sintering temperature can be 750℃, 760℃, 770℃, 780℃, 790℃, 800℃, or any value between 750℃ and 800℃; the sintering time can be 30s, 40s, 50s, 60s, or any value between 30s and 60s.

[0072] In one optional embodiment, the thickness of the alumina passivation layer is 6-15 nm.

[0073] Optionally, the thickness of the alumina passivation layer can be 6nm, 9nm, 12nm, 15nm, or any value between 6 and 15nm.

[0074] In one alternative embodiment, the thickness of the first silicon nitride layer is 75-90 nm.

[0075] Optionally, the thickness of the first silicon nitride layer can be 75nm, 80nm, 85nm, 90nm, or any value between 75-90nm.

[0076] In one alternative embodiment, the thickness of the second silicon nitride layer is 72-82 nm.

[0077] Optionally, the thickness of the second silicon nitride layer can be 72nm, 73nm, 74nm, 75nm, 76nm, 77nm, 78nm, 79nm, 80nm, 81nm, 82nm, or any value between 72nm and 82nm.

[0078] Secondly, this application provides a PERC half-cell battery, which is prepared according to the PERC half-cell battery preparation method described above.

[0079] Thirdly, this application also provides a photovoltaic system including the aforementioned PERC half-cell battery.

[0080] The implementation schemes of this application will be described in detail below with reference to specific embodiments. However, those skilled in the art will understand that the following embodiments are only for illustrating this application and should not be regarded as limiting the scope of this application. Unless otherwise specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments used without specified manufacturers are all conventional products that can be purchased commercially.

[0081] Example 1

[0082] This embodiment provides a PERC half-cell battery, and the specific preparation steps are as follows:

[0083] (1) Wet texturing: The N+ layer of the silicon wafer 100 is wet texturized using a texturing solution. The texturing solution, by volume, comprises 16 parts of 40% concentrated NaOH, 3.5 parts of texturing additive, and 450 parts of pure water. The texturing additive consists of 3% isotridecyl ether, 2% acrylamide, 3% quaternary ammonium salt, 2% disodium tetraacetate, 4% alkyl glycoside, and 0.5% sodium benzoate, with the remainder being water. The reflectance of the texturized surface after treatment is 9.5%.

[0084] (2) Phosphorus diffusion: The silicon wafer was subjected to phosphorus diffusion deposition for 15 min at a temperature of 790℃, a pressure of 70 mbar, a nitrogen flow rate of 650 sccm / min carrying phosphorus oxychloride, and an oxygen flow rate of 600 sccm / min. Then, the temperature was increased to 860℃, the pressure was 100 mbar, and the nitrogen flow rate was 2200 sccm / min for another 20 min. After the phosphorus diffusion treatment, the thickness of the phosphorus silicate glass on the front side of the silicon wafer was greater than or equal to 35 nm.

[0085] (3) Removal of phosphosilicate glass: Remove the phosphosilicate glass in the N+ layer direction of the silicon wafer by chain pickling of the N+ layer direction of the silicon wafer with 12% by mass of hydrofluoric acid for 130s to obtain the pretreated silicon wafer.

[0086] (4) Laser cutting of half wafers: Laser cutting is used to cut silicon wafers of the same size with left and right sides symmetrical along the central axis of the silicon wafer; the laser power is 12W, the spot width is 40um, the cutting temperature is 60℃, the cleaving method is thermal laser cleaving, and two half-cell batteries are obtained.

[0087] (5) Alkali polishing: Polish the N+ layer direction and the cut surface, with a back reflectivity >35%, using 15L NaOH, 3.0L additives, 450L water, at a temperature of 77℃ for 150s. The additives include 4% surfactant, 2% defoamer, 3% sodium polystyrene sulfonate, 2% sodium citrate, 3% sodium dodecyl sulfonate and sodium benzoate, with the remainder being water. After polishing, the phosphorus silicate glass in the P+ layer direction is cleaned using 120L HF and 480L water for 150s.

[0088] (6) Alumina passivation layer 103 was generated in the N+ layer direction: pressure 2000 mtorr, radio frequency power 9000 W, trimethylaluminum 65 sccm / min, nitrous oxide 6000 sccm / min, reaction time 160 s, and the thickness of the resulting alumina passivation layer 103 was 10 nm.

[0089] (7) Forming the first silicon nitride layer 102 in the N+ layer direction: Silicon nitride deposition was performed with a silane flow rate of 1450 sccm / min, an ammonia flow rate of 10600 sccm / min, a pressure of 1650 mtorr, and a time of 920 s. The thickness of the first silicon nitride layer 102 obtained was 82 nm.

[0090] (8) Formation of a second silicon nitride layer in the P+ layer direction: Silicon nitride deposition was performed with a silane flow rate of 1550 sccm / min, an ammonia flow rate of 9600 sccm / min, a pressure of 1600 mtorr, and a time of 850 s. The thickness of the resulting second silicon nitride layer 104 was 77 nm.

[0091] (9) Printing and Sintering: Silver paste grid lines are printed on the half-cell as the positive electrode and aluminum paste grid lines as the back electrode for current conduction. Then, sintering is performed at 780℃ for 45 seconds. This yields a PERC half-cell. The structure of the fabricated PERC half-cell is as follows: Figure 1 As shown, a physical image of the fabricated Pere half-cell battery is as follows. Figure 2 As shown.

[0092] Example 2

[0093] This embodiment provides a PERC half-cell battery, and the specific preparation steps are as follows:

[0094] (1) Wet texturing: The N+ layer of the silicon wafer 100 is wet texturized using a texturing solution. The texturing solution, by volume, comprises 16 parts of 40% concentrated NaOH, 3.5 parts of texturing additive, and 450 parts of pure water. The texturing additive consists of 3% isotridecyl ether, 2% acrylamide, 2% quaternary ammonium salt, 2.5% disodium tetraacetate, 3% alkyl glycoside, and 0.3% sodium benzoate, with the remainder being water. The reflectance of the texturized surface after treatment is 9.5%.

[0095] (2) Phosphorus diffusion: The silicon wafer was subjected to phosphorus diffusion deposition for 15 min at a temperature of 790℃, a pressure of 70 mbar, a nitrogen flow rate of 650 sccm / min carrying phosphorus oxychloride, and an oxygen flow rate of 600 sccm / min. Then, the temperature was increased to 860℃, the pressure was 100 mbar, and the nitrogen flow rate was 2200 sccm / min for another 20 min. After the phosphorus diffusion treatment, the thickness of the phosphorus silicate glass on the front side of the silicon wafer was greater than or equal to 35 nm.

[0096] (3) Removal of phosphosilicate glass: Remove the phosphosilicate glass in the N+ layer direction of the silicon wafer by chain pickling of the N+ layer direction of the silicon wafer with 12% by mass of hydrofluoric acid for 130s to obtain the pretreated silicon wafer.

[0097] (4) Laser cutting of half wafers: Laser cutting is used to cut silicon wafers of the same size that are symmetrical on the left and right along the central axis of the silicon wafer; the laser power is 12W, the spot width is 40μm, the temperature during cutting is 60℃, and the cleaving method is thermal laser cleaving, resulting in two half-cell batteries.

[0098] (5) Alkali polishing: Polish the N+ layer direction and the cut surface, with a back reflectivity >35%, using 18L NaOH, 2.8L additives, 450L water, at a temperature of 80℃ for 150s. The additives include 4% surfactant, 2% defoamer, 3% sodium polystyrene sulfonate, 2% sodium citrate, 3% sodium dodecyl sulfonate and sodium benzoate, with the remainder being water. After polishing, the phosphorus silicate glass in the P+ layer direction is cleaned using 120L HF and 480L water for 150s.

[0099] (6) Alumina passivation layer 103 was generated in the N+ layer direction: pressure 2200 mtorr, radio frequency power 10000 W, trimethylaluminum 80 sccm / min, nitrous oxide 6500 sccm / min, reaction time 160 s, and the thickness of the resulting alumina passivation layer was 15 nm.

[0100] (7) Forming the first silicon nitride layer 102 in the N+ layer direction: Silicon nitride deposition was performed with a silane flow rate of 1750 sccm / min, an ammonia flow rate of 11500 sccm / min, a pressure of 1750 mtorr, and a time of 910 s. The thickness of the first silicon nitride layer 102 obtained was 88 nm.

[0101] (8) Formation of a second silicon nitride layer 104 in the P+ layer direction: Silicon nitride deposition was performed with a silane flow rate of 1650 sccm / min, an ammonia flow rate of 11000 sccm / min, a pressure of 1700 mtorr, and a time of 850 s. The thickness of the resulting second silicon nitride layer 104 was 81 nm.

[0102] (9) Printing and sintering: Print corresponding silver paste grid lines as positive electrodes and aluminum paste grid lines as back electrodes on the half cell for current conduction, and then sinter at a temperature of 780℃ for 50s. PERC half cell is obtained.

[0103] Example 3

[0104] This embodiment provides a PERC half-cell battery, and the specific preparation steps are as follows:

[0105] (1) Wet texturing: The N+ layer of the silicon wafer 100 is wet texturized using a texturing solution. The texturing solution, by volume, comprises 16 parts of 40% concentrated NaOH, 3.5 parts of texturing additive, and 450 parts of pure water. The texturing additive consists of 3% isotridecyl ether, 2% acrylamide, 3% quaternary ammonium salt, 2% disodium tetraacetate, 4% alkyl glycoside, and 0.5% sodium benzoate, with the remainder being water. The reflectance of the texturized surface after treatment is 9.5%.

[0106] (2) Phosphorus diffusion: The silicon wafer was subjected to phosphorus diffusion deposition for 15 min at a temperature of 790℃, a pressure of 70 mbar, a nitrogen flow rate of 650 sccm / min carrying phosphorus oxychloride, and an oxygen flow rate of 600 sccm / min. Then, the temperature was increased to 860℃, the pressure was 100 mbar, and the nitrogen flow rate was 2200 sccm / min for another 20 min. After the phosphorus diffusion treatment, the thickness of the phosphorus silicate glass on the front side of the silicon wafer was greater than or equal to 35 nm.

[0107] (3) Removal of phosphosilicate glass: Remove the phosphosilicate glass in the N+ layer direction of the silicon wafer by chain pickling of the N+ layer direction of the silicon wafer with 12% by mass of hydrofluoric acid for 130s to obtain the pretreated silicon wafer.

[0108] (4) Laser cutting of half wafers: Laser cutting is used to cut silicon wafers of the same size with left and right sides symmetrical along the central axis of the silicon wafer; the laser power is 12W, the spot width is 40um, the cutting temperature is 60℃, the cleaving method is thermal laser cleaving, and two half-cell batteries are obtained.

[0109] (5) Alkali polishing: Polish the N+ layer direction and the cut surface, with a back reflectivity >35%, using 13L NaOH, 3.5L additives, 450L water, at a temperature of 75℃ for 150S. The additives include 4% surfactant, 2% defoamer, 3% sodium polystyrene sulfonate, 2% sodium citrate, 3% sodium dodecyl sulfonate and sodium benzoate, with the remainder being water. After polishing, the phosphorus silicate glass in the P+ layer direction is cleaned using 120L HF and 480L water for 150S.

[0110] (6) Alumina passivation layer 103 was generated in the N+ layer direction: pressure 1700 mtorr, radio frequency power 8000 W, trimethylaluminum 55 sccm / min, nitrous oxide 5000 sccm / min, reaction time 160 s, and the thickness of the resulting alumina passivation layer was 6 nm.

[0111] (7) Forming the first silicon nitride layer 102 in the N+ layer direction: Silicon nitride deposition was performed with a silane flow rate of 1300 sccm / min, an ammonia flow rate of 9000 sccm / min, a pressure of 1550 mtorr, and a time of 900 s. The thickness of the first silicon nitride layer 102 obtained was 75 nm.

[0112] (8) Formation of a second silicon nitride layer in the P+ layer direction: Silicon nitride deposition was performed with a silane flow rate of 1350 sccm / min, an ammonia flow rate of 8600 sccm / min, a pressure of 1550 mtorr, and a time of 830 s. The thickness of the resulting second silicon nitride layer 102 was 72 nm.

[0113] (9) Printing and sintering: Print corresponding silver paste grid lines as positive electrodes and aluminum paste grid lines as back electrodes on the half cell for current conduction, and then sinter at a temperature of 780℃ for 40s. PERC half cell is obtained.

[0114] Comparative Example 1

[0115] This comparative example provides a conventional PERC half-cell cell, which is a solar cell that is cut into half along the central axis after the finished product is manufactured. The specific preparation steps are as follows:

[0116] (1) Wet texturing: The N+ layer of the silicon wafer is wet texturized using a texturing solution. The texturing solution, by volume, comprises 16 parts of 40% concentrated NaOH, 3.5 parts of texturing additive, and 450 parts of pure water. The texturing additive consists of 3% isotridecyl ether, 2% acrylamide, 1% quaternary ammonium salt, 3% disodium tetraacetate, 3% alkyl glycoside, and 0.5% sodium benzoate, with the remainder being water. The reflectance of the texturized surface after treatment is 9.5%.

[0117] (2) Phosphorus diffusion: The silicon wafer was subjected to phosphorus diffusion deposition for 15 min at a temperature of 790℃, a pressure of 70 mbar, a nitrogen flow rate of 650 sccm / min carrying phosphorus oxychloride, and an oxygen flow rate of 600 sccm / min. Then, the temperature was increased to 860℃, the pressure was 100 mbar, and the nitrogen flow rate was 2200 sccm / min for another 20 min. After the phosphorus diffusion treatment, the thickness of the phosphorus silicate glass on the front side of the silicon wafer was greater than or equal to 35 nm.

[0118] (3) Removal of phosphosilicate glass: Remove the phosphosilicate glass in the N+ layer direction of the silicon wafer by chain pickling of the N+ layer direction of the silicon wafer with 12% by mass of hydrofluoric acid for 130s to obtain the pretreated silicon wafer.

[0119] (4) Alkali polishing: Polish the N+ layer direction and the cut surface, with a back reflectivity >35%, using 15L NaOH, 3.0L additives, 450L water, at a temperature of 77℃ for 150s. The additives include 4% surfactant, 1.5% defoamer, 3% sodium polystyrene sulfonate, 2% sodium citrate, 3% sodium dodecyl sulfonate and sodium benzoate, with the remainder being water. After polishing, the phosphorus silicate glass in the P+ layer direction is cleaned using 120L HF and 480L water for 150s.

[0120] (5) Alumina passivation layer is generated in the N+ layer direction: pressure 2000 mtorr, radio frequency power 9000 W, trimethylaluminum 65 sccm / min, nitrous oxide 6000 sccm / min, reaction time 160 s, and the thickness of the resulting alumina passivation layer is 10 nm.

[0121] (6) Formation of the first silicon nitride layer in the N+ layer direction: Silicon nitride deposition was performed with a silane flow rate of 1450 sccm / min, an ammonia flow rate of 10600 sccm / min, a pressure of 1650 mtorr, and a time of 920 s. The thickness of the first silicon nitride obtained was 82 nm.

[0122] (7) Formation of a second silicon nitride layer in the P+ layer direction: Silicon nitride deposition was performed with a silane flow rate of 1550 sccm / min, an ammonia flow rate of 9600 sccm / min, a pressure of 1600 mtorr, and a time of 850 s. The thickness of the resulting second silicon nitride layer was 77 nm.

[0123] (8) Printing and sintering: Print corresponding silver paste grid lines as positive electrodes and aluminum paste grid lines as back electrodes on the half cell for current conduction, and then sinter at a temperature of 780℃ for 45s. PERC half cell is obtained.

[0124] (9) Laser cutting of half cells: The finished product obtained after sintering is laser-cut along the central axis into symmetrical battery cells of the same size; the laser power is 12W, the spot width is 40um, the cutting temperature is 60℃, and the splitting method is thermal laser splitting to obtain two half cells.

[0125] Comparative Example 2

[0126] This comparative example provides a PERC half-cell battery, and the specific preparation steps are as follows:

[0127] (1) Wet texturing: The N+ layer of the silicon wafer is wet texturized using a texturing solution. The texturing solution, by volume, comprises 16 parts of 40% concentrated NaOH, 3.5 parts of texturing additive, and 450 parts of pure water. The texturing additive consists of 2% isotridecyl ether, 1% acrylamide, 2% quaternary ammonium salt, 3% disodium tetraacetate, 3% alkyl glycoside, and 0.4% sodium benzoate, with the balance being water. The reflectance of the texturized surface after treatment is 9.5%.

[0128] (2) Phosphorus diffusion: The silicon wafer was subjected to phosphorus diffusion deposition for 15 min at a temperature of 790℃, a pressure of 70 mbar, a nitrogen flow rate of 650 sccm / min carrying phosphorus oxychloride, and an oxygen flow rate of 600 sccm / min. Then, the temperature was increased to 860℃, the pressure was 100 mbar, and the nitrogen flow rate was 2200 sccm / min for another 20 min. After the phosphorus diffusion treatment, the thickness of the phosphorus silicate glass on the front side of the silicon wafer was greater than or equal to 35 nm.

[0129] (3) Removal of phosphosilicate glass: Remove the phosphosilicate glass in the N+ layer direction of the silicon wafer by chain pickling of the N+ layer direction of the silicon wafer with 12% by mass of hydrofluoric acid for 130s to obtain the pretreated silicon wafer.

[0130] (4) Alkali polishing: Polish the N+ layer direction and the cut surface, with a back reflectivity >35%. Use 15L NaOH, 3.0L additives, 450L water, at a temperature of 77℃ for 150s. The additives include 3% surfactant, 2% defoamer, 4.5% sodium polystyrene sulfonate, 2.5% sodium citrate, 5% sodium dodecyl sulfonate and sodium benzoate, and the remainder is water. After polishing, clean the phosphosilicate glass in the P+ layer direction using 120L HF and 480L water for 150s.

[0131] (5) Laser cutting of half wafers: Laser cutting is used to cut silicon wafers of the same size with left and right sides symmetrical along the central axis of the silicon wafer; the laser power is 12W, the spot width is 40um, the cutting temperature is 60℃, the cleaving method is thermal laser cleaving, and two half-cell batteries are obtained.

[0132] (6) Alumina passivation layer is generated in the N+ layer direction: pressure 2000 mtorr, radio frequency power 9000 W, trimethylaluminum 65 sccm / min, nitrous oxide 6000 sccm / min, reaction time 160 s, and the thickness of the resulting alumina passivation layer is 10 nm.

[0133] (7) Formation of the first silicon nitride layer in the N+ layer direction: Silicon nitride deposition was performed with a silane flow rate of 1450 sccm / min, an ammonia flow rate of 10600 sccm / min, a pressure of 1650 mtorr, and a time of 920 s. The thickness of the first silicon nitride obtained was 82 nm.

[0134] (8) Formation of a second silicon nitride layer in the P+ layer direction: Silicon nitride deposition was performed with a silane flow rate of 1550 sccm / min, an ammonia flow rate of 9600 sccm / min, a pressure of 1600 mtorr, and a time of 850 s. The thickness of the resulting second silicon nitride layer was 77 nm.

[0135] (9) Printing and sintering: Print corresponding silver paste grid lines as positive electrodes and aluminum paste grid lines as back electrodes on the half cell for current conduction, and then sinter at a temperature of 780℃ for 45s. PERC half cell is obtained.

[0136] Comparative Example 3

[0137] This comparative example provides a PERC half-cell battery, and the specific preparation steps are as follows:

[0138] (1) Wet texturing: The N+ layer of the silicon wafer is wet texturized using a texturing solution. The texturing solution, by volume, comprises 16 parts of 40% concentrated NaOH, 3.5 parts of texturing additive, and 450 parts of pure water. The texturing additive consists of 2% isotridecyl ether, 0.5% acrylamide, 1-3% quaternary ammonium salt, 1-3% disodium tetraacetate, 4% alkyl glycoside, and 0.5% sodium benzoate, with the remainder being water. The reflectance of the texturized surface after treatment is 9.5%.

[0139] (2) Phosphorus diffusion: The silicon wafer was subjected to phosphorus diffusion deposition for 15 min at a temperature of 790℃, a pressure of 70 mbar, a nitrogen flow rate of 650 sccm / min carrying phosphorus oxychloride, and an oxygen flow rate of 600 sccm / min. Then, the temperature was increased to 860℃, the pressure was 100 mbar, and the nitrogen flow rate was 2200 sccm / min for another 20 min. After the phosphorus diffusion treatment, the thickness of the phosphorus silicate glass on the front side of the silicon wafer was greater than or equal to 35 nm.

[0140] (3) Removal of phosphosilicate glass: Remove the phosphosilicate glass in the N+ layer direction of the silicon wafer by chain pickling of the N+ layer direction of the silicon wafer with 12% by mass of hydrofluoric acid for 130s to obtain the pretreated silicon wafer.

[0141] (4) Alkali polishing: Polish the N+ layer direction and the cut surface, with a back reflectivity >35%, using 15L NaOH, 3.0L additives, 450L water, at a temperature of 77℃ for 150s. The additives include 5% surfactant, 1% defoamer, 4.5% sodium polystyrene sulfonate, 2% sodium citrate, 3% sodium dodecyl sulfonate and sodium benzoate, with the remainder being water. After polishing, the phosphorus silicate glass in the P+ layer direction is cleaned using 120L HF and 480L water for 150s.

[0142] (5) Alumina passivation layer is generated in the N+ layer direction: pressure 2000 mtorr, radio frequency power 9000 W, trimethylaluminum 65 sccm / min, nitrous oxide 6000 sccm / min, reaction time 160 s, and the thickness of the resulting alumina passivation layer is 10 nm.

[0143] (6) Laser cutting of half wafers: Laser cutting is used to cut silicon wafers of the same size that are symmetrical on the left and right along the central axis of the silicon wafer; the laser power is 12W, the spot width is 40um, the cutting temperature is 60℃, the cleaving method is thermal laser cleaving, and two half-cell batteries are obtained.

[0144] (7) Formation of the first silicon nitride layer in the N+ layer direction: Silicon nitride deposition was performed with a silane flow rate of 1450 sccm / min, an ammonia flow rate of 10600 sccm / min, a pressure of 1650 mtorr, and a time of 920 s. The thickness of the first silicon nitride obtained was 82 nm.

[0145] (8) Formation of a second silicon nitride layer in the P+ layer direction: Silicon nitride deposition was performed with a silane flow rate of 1550 sccm / min, an ammonia flow rate of 9600 sccm / min, a pressure of 1600 mtorr, and a time of 850 s. The thickness of the resulting second silicon nitride layer was 77 nm.

[0146] (9) Printing and sintering: Print corresponding silver paste grid lines as positive electrodes and aluminum paste grid lines as back electrodes on the half cell for current conduction, and then sinter at a temperature of 780℃ for 45s. PERC half cell is obtained.

[0147] The electrical properties of the PERC half-cell batteries prepared in Examples 1-3 and Comparative Examples 1-3 are shown in Table 1:

[0148] Table 1. Electrical performance of PERC half-cell batteries prepared in the examples and comparative examples.

[0149]

[0150]

[0151] As shown in Table 1, Example 1 showed a 0.24% efficiency improvement compared to Comparative Example 1, mainly due to improved pressure and filling, demonstrating that the laser-cut damaged surface was significantly improved after alkaline polishing and passivation with alumina and silicon nitride. Comparative Example 2, because laser cutting was performed after alkaline polishing, could not polish the cut surface to repair mechanical damage; and Comparative Example 3, because laser cutting was performed after alumina, prevented alumina passivation; both resulted in poor passivation effects. Examples 2 and 3 had the same process flow, but the thicknesses of alumina and silicon nitride differed, leading to different passivation effects and light reflection effects on the front surface, resulting in minor differences in efficiency.

[0152] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

[0153] Furthermore, those skilled in the art will understand that although some embodiments herein include certain features included in other embodiments but not others, combinations of features from different embodiments are intended to be within the scope of this application and form different embodiments. For example, in the foregoing claims, any of the claimed embodiments can be used in any combination. The information disclosed in this background section is intended only to enhance the understanding of the general background of this application and should not be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

Claims

1. A method for preparing a PERC half-cell battery, characterized in that, include: The silicon wafer is pre-processed to obtain a pre-processed silicon wafer, and then the pre-processed silicon wafer is cut to obtain two half-cells. Finally, the half-cells are post-processed to obtain a PERC half-cell. The pretreatment includes wet texturing and phosphorus diffusion in the N+ layer direction of the silicon wafer; The post-processing includes alkaline polishing of the N+ layer direction, P+ layer direction, and cut surface of the half-cell.

2. The method for preparing a PERC half-cell battery according to claim 1, characterized in that, The cutting is laser cutting, performed along the central axis of the silicon wafer.

3. The method for preparing a PERC half-cell battery according to claim 2, characterized in that, At least one of the following conditions must be met: a. The error between the laser cutting line and the central axis of the silicon wafer does not exceed 100 μm; b. During the laser cutting process, the laser power is 8-15W, the spot width is 30-60μm, and the cutting temperature is 50-70℃; c. The cleaving method after laser cutting is thermal laser cleaving.

4. The method for preparing a PERC half-cell battery according to claim 1, characterized in that, At least one of the following conditions must be met: d. The silicon wafer is wet-textured using a texturing solution at 70-85°C for 80-150 seconds. The texturing solution comprises, by volume, 15-20 parts of 40% concentrated NaOH, 2-5 parts of texturing additives, and 400-500 parts of water. The texturing additives include 2-3% tridecyl ether, 0.5-2% acrylamide, 1-3% quaternary ammonium salt, 1-3% disodium tetraacetate, 3-4% alkyl glycoside, 0.3-0.5% sodium benzoate, with the balance being water. e. During the phosphorus diffusion process, phosphorus diffusion deposition is first carried out at a temperature of 770-795℃, a pressure of 60-120 mbar, a nitrogen flow rate carrying phosphorus oxychloride of 600-800 sccm / min, and an oxygen flow rate of 500-700 sccm / min for 10-20 min; then, the temperature is increased to 850-880℃, a pressure of 70-150 mbar, and a nitrogen flow rate of 2000-3000 sccm / min for 15-25 min.

5. The method for preparing a PERC half-cell battery according to claim 4, characterized in that, After the phosphorus diffusion, the silicon wafer needs to be chain-washed in the N+ layer direction with hydrofluoric acid at a mass fraction of 6-15% for 100-200 seconds to remove the phosphorus-silicon glass.

6. The method for preparing a PERC half-cell battery according to any one of claims 1-5, characterized in that, The post-processing further includes cleaning the phosphorosilicate glass in the P+ layer direction after alkaline polishing, performing a first reaction in the N+ layer direction of the half-cell to generate an aluminum oxide passivation layer, obtaining a first intermediate morphology; then performing a second reaction in the N+ layer direction of the first intermediate morphology to generate a first silicon nitride layer, obtaining a second intermediate morphology; then performing a third reaction in the P+ layer direction of the second intermediate morphology to generate a second silicon nitride layer, obtaining a third intermediate morphology; then printing a positive electrode and a back electrode on the third intermediate morphology, and sintering to obtain the PERC half-cell.

7. The method for preparing a PERC half-cell battery according to claim 6, characterized in that, At least one of the following conditions must be met: f. Alkaline polishing is performed using a polishing solution at a temperature of 70-80°C for 120-240 seconds. The polishing solution comprises 12-20 L of NaOH, 2-5 L of additives, and 400-500 L of water. The additives include 3-5% surfactant, 1-2% defoamer, 2-4.5% sodium polystyrene sulfonate, 2-2.5% sodium citrate, 3-5% sodium dodecyl sulfonate and sodium benzoate, with the remainder being water. The surfactant includes sodium polyoxyethylene ether sulfate, and the defoamer includes polyacrylamide or polyvinylpyrrolidone. g. The phosphorosilicate glass in the P+ layer direction is cleaned with a cleaning solution for 120-180 seconds; the cleaning solution includes 100-150L of HF and 450-500L of water. h. The reaction conditions for the first reaction are: pressure 1600-2200 mtorr, radio frequency power 7000-10000 W, trimethylaluminum flow rate 40-80 sccm / min, nitrous oxide flow rate 4000-7000 sccm / min, and time 80-200 s; i. The reaction conditions for the second reaction are: silane flow rate 200-1800 sccm / min, ammonia flow rate 8500-12000 sccm / min, pressure 1500-1800 mtorr, and time 700-1100 s; j. The reaction conditions for the third reaction are: silane flow rate 1200-1800 sccm / min, ammonia flow rate 8500-12000 sccm / min, pressure 1500-1800 mtorr, and time 700-1000 s; k. The sintering temperature is 750-800℃ and the time is 30-60s.

8. The method for preparing a PERC half-cell battery according to claim 6, characterized in that, At least one of the following conditions must be met:

1. The thickness of the alumina passivation layer is 6-15 nm; m. The thickness of the first silicon nitride layer is 75-90 nm; n. The thickness of the second silicon nitride layer is 72-82 nm.

9. A PERC half-cell battery, characterized in that, The PERC half-cell battery is prepared according to any one of claims 1-8.

10. A photovoltaic system, characterized in that, Includes the PERC half-cell battery as described in claim 9.

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