IBC solar cell and preparation method thereof
In the preparation process of IBC solar cells, laser patterning and wet etching technology are used to control the thickness and density of the tunneled oxide layer, and fleece processing is carried out on the front, which solves the problems of easy corrosion and complex process of the tunneled oxide layer, and achieves efficient passivation and simplification of the process, and improves the conversion efficiency of the solar cell.
Patent Information
- Application Number
- CN202411637587.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-15
- Publication Date
- 2025-03-25
AI Technical Summary
In the conventional IBC solar cell preparation process, the tunneling oxide layer has poor acid and alkali resistance, which leads to the tunneling oxide layer in the isolation area being easily corroded, making it difficult to control thickness and density, affecting passivation performance, and the process is complex and not suitable for large-scale production.
After laser patterning and wet etching are formed, a tunnel oxide layer is formed in the isolation region to control its thickness and density, and then a boron-doped polysilicon layer and a phosphorus doped polysilicon layer are formed on the back of the silicon wafer to produce a front fleece to optimize the surface passivation structure and light trap structure.
It effectively improves the density and functional stability of the tunneled oxide layer, enhances the passivation effect on the back, improves the conversion efficiency of solar cells, and simplifies the process, which is suitable for large-scale production.
Smart Images
Figure CN119698129A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of solar cells, and in particular to an IBC solar cell and a preparation method thereof. Background Art
[0002] At present, the photovoltaic industry is gradually entering the N-type era. IBC (Interdigitated back contact) solar cells use N-type cell technology, which has high conversion efficiency, low series resistance, simplified interconnection technology and good appearance, and has broad application prospects.
[0003] However, in the conventional IBC solar cell preparation process, a tunneling oxide layer is prepared on the back of the silicon wafer, and then laser windowing and RCA cleaning are performed to form an isolation area. However, due to the poor acid and alkali resistance of the tunneling oxide layer, the tunneling oxide layer in the isolation area is easily corroded, making it difficult to control the thickness of the tunneling oxide layer and affecting its density, which in turn affects the passivation performance. In addition, the traditional preparation process is relatively complicated and difficult to apply to large-scale production.
[0004] Therefore, there is an urgent need for a method for preparing an IBC solar cell that can control the thickness of the tunneling oxide layer, improve the density of the tunneling oxide layer, and has a simple process. Summary of the invention
[0005] Based on this, it is necessary to provide an IBC solar cell and a preparation method thereof to address the above problems. The preparation method provided by the present invention can effectively control the thickness of the tunneling oxide layer and improve the density of the tunneling oxide layer, thereby improving the passivation effect of the solar cell, and the preparation method of the present invention has a simple process and is suitable for large-scale production.
[0006] The present invention provides a method for preparing an IBC solar cell, comprising:
[0007] S1, double-sided polishing of silicon wafer;
[0008] S2, forming a first tunneling oxide layer and a boron-doped polysilicon layer in sequence on the back side of the silicon wafer;
[0009] S3, performing a first laser patterning on the back side of the silicon wafer to remove the borosilicate glass layer in the N region and the isolation region, and performing a first wet etching to remove the first tunneling oxide layer and the boron-doped polysilicon layer in the N region and the isolation region;
[0010] S4, forming a second tunneling oxide layer and a phosphorus-doped polysilicon layer in sequence on the back side of the silicon wafer;
[0011] S5, performing a second wet etching on the front side of the silicon wafer to remove all the layers of the front side plating;
[0012] S6, texturing the front side of the silicon wafer so that a velvet structure is formed on the front side of the silicon wafer;
[0013] S7, performing a second laser patterning on the back side of the silicon wafer to remove the phosphorus silicon glass layer in the P region and the isolation region, and performing a third wet etching to etch the P region to the boron-doped polysilicon layer, the N region to the phosphorus-doped polysilicon layer, and the isolation region to the silicon wafer;
[0014] S8, growing a third tunneling oxide layer in the isolation region on the back side of the silicon wafer;
[0015] S9, forming a passivation layer and an anti-reflection layer on both sides of the silicon wafer in sequence;
[0016] S10. Prepare a positive electrode and a negative electrode on the back side of the silicon wafer.
[0017] In one embodiment, the thickness of the first tunnel oxide layer and the second tunnel oxide layer are independently selected from 1 nm to 3 nm;
[0018] And / or, the thickness of the third tunnel oxide layer is 1 nm to 5 nm.
[0019] In one embodiment, the thickness of the third tunnel oxide layer is greater than or equal to the thickness of the first tunnel oxide layer.
[0020] In one embodiment, the thickness of the first tunnel oxide layer is greater than or equal to the thickness of the second tunnel oxide layer.
[0021] In one of the embodiments, the thickness of the boron-doped polysilicon layer is 200 nm to 350 nm;
[0022] And / or, the thickness of the phosphorus-doped polysilicon layer is 100 nm to 250 nm.
[0023] In one embodiment, the thickness of the boron-doped polysilicon layer is greater than or equal to the thickness of the phosphorus-doped polysilicon layer.
[0024] In one embodiment, the process of sequentially forming a passivation layer and an anti-reflection layer on both sides of a silicon wafer includes the following steps:
[0025] forming the passivation layer on both sides of the silicon wafer;
[0026] forming a back anti-reflection layer on the back side of the silicon wafer;
[0027] A front anti-reflection layer is formed on the front side of the silicon wafer, and the front anti-reflection layer includes a first silicon nitride layer, a second silicon nitride layer, a third silicon nitride layer, a first silicon oxynitride layer, a second silicon oxynitride layer, a silicon oxide layer and a magnesium fluoride layer stacked from inside to outside.
[0028] In one embodiment, the refractive index of each layer in the front anti-reflection layer decreases from the inside to the outside.
[0029] In one embodiment, the refractive index of the first silicon nitride layer is 2.2-2.3, and the thickness is 20nm-30nm;
[0030] And / or, the refractive index of the second silicon nitride layer is 2.1-2.2, and the thickness is 20nm-30nm;
[0031] And / or, the refractive index of the third silicon nitride layer is 2.0-2.1, and the thickness is 15nm-25nm;
[0032] And / or, the first silicon oxynitride layer has a refractive index of 1.8 to 2.0 and a thickness of 5 nm to 15 nm;
[0033] And / or, the refractive index of the second silicon oxynitride layer is 1.6 to 1.8, and the thickness is 3 nm to 10 nm;
[0034] And / or, the silicon oxide layer has a refractive index of 1.4 to 1.6 and a thickness of 5 nm to 15 nm;
[0035] And / or, the magnesium fluoride layer has a refractive index of 1.2 to 1.4 and a thickness of 2 nm to 10 nm.
[0036] The preparation method of the above-mentioned IBC solar cell, on the one hand, forms an isolation area through laser patterning and wet etching and then forms a tunneling oxide layer in the isolation area, effectively controls the thickness of the tunneling oxide layer in the isolation area, improves the density and functional stability of the tunneling oxide layer, thereby improving the passivation effect of the back side, and further improves the conversion efficiency of the solar cell; on the other hand, after forming a boron-doped polysilicon layer and a phosphorus-doped polysilicon layer on the back side of the silicon wafer, the front side is texturized, which not only effectively optimizes the surface passivation structure and light trapping structure, improves the density of the front passivation layer, reduces the front surface recombination loss, thereby improving the conversion efficiency of the solar cell, but also helps to simplify the process and is suitable for large-scale production.
[0037] The present invention also provides an IBC solar cell prepared by the preparation method as described above.
[0038] The above-mentioned IBC solar cell has a compact structure and is easy to maintain, and has excellent cell conversion efficiency. BRIEF DESCRIPTION OF THE DRAWINGS
[0039] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.
[0040] Figure 1 A schematic diagram of the structure of an IBC solar cell prepared according to one embodiment of the present invention;
[0041] Figure 2 This is a schematic diagram of the IBC solar cell structure obtained in step S3 in one embodiment of the present invention;
[0042] Figure 3 This is a schematic diagram of the IBC solar cell structure obtained in step S6 in one embodiment of the present invention;
[0043] Figure 4 This is a schematic diagram of the IBC solar cell structure obtained in step S7 in one embodiment of the present invention;
[0044] Figure 5 FIG. 1 is a schematic diagram of the IBC solar cell structure obtained in step S8 in one embodiment of the present invention.
[0045] Figure numerals: 1-silicon wafer; 21-first tunneling oxide layer; 22-second tunneling oxide layer; 23-third tunneling oxide layer; 3-boron-doped polysilicon layer; 4-boron silicon glass layer; 5-phosphorus-doped polysilicon layer; 6-phosphorus silicon glass layer; 7-passivation layer; 8-back anti-reflection layer; 9-front anti-reflection layer; 91-first silicon nitride layer; 92-second silicon nitride layer; 93-third silicon nitride layer; 94-first silicon oxynitride layer; 95-second silicon oxynitride layer; 96-silicon oxide layer; 97-magnesium fluoride layer; 10-positive electrode; 11-negative electrode. DETAILED DESCRIPTION
[0046] For ease of understanding of the present invention, the present invention will be described in more detail below. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the embodiments or examples described herein. On the contrary, the purpose of providing these embodiments or examples is to make the understanding of the disclosure of the present invention more thorough and comprehensive.
[0047] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific implementation methods or embodiments, and are not intended to limit the present invention. The optional scope of the term "and / or" used herein includes any one of two or more related listed items, and also includes any and all combinations of related listed items, and the combinations include any two related listed items, any more related listed items, or all related listed items.
[0048] like Figure 1 As shown, an IBC solar cell is prepared in one embodiment of the present invention, and its preparation method comprises the following steps:
[0049] S1, double-sided polishing of silicon wafer 1;
[0050] S2, forming a first tunneling oxide layer 21 and a boron-doped polysilicon layer 3 in sequence on the back side of the silicon wafer 1;
[0051] S3, performing a first laser patterning on the back side of the silicon wafer 1 to remove the borosilicate glass layer 4 in the N region and the isolation region, and performing a first wet etching to remove the first tunneling oxide layer 21 and the boron-doped polysilicon layer 3 in the N region and the isolation region;
[0052] S4, forming a second tunneling oxide layer 22 and a phosphorus-doped polysilicon layer 5 in sequence on the back side of the silicon wafer 1;
[0053] S5, performing a second wet etching on the front side of the silicon wafer 1 to remove all the layers plated on the front side;
[0054] S6, performing texturing on the front side of the silicon wafer 1 so that a velvet structure is formed on the front side of the silicon wafer;
[0055] S7, performing a second laser patterning on the back side of the silicon wafer 1 to remove the phosphorus-silicon glass layer 6 in the P region and the isolation region, and performing a third wet etching to etch the P region to the boron-doped polysilicon layer 3, the N region to the phosphorus-doped polysilicon layer 5, and the isolation region to the silicon wafer 1;
[0056] S8, growing a third tunneling oxide layer 23 in the isolation region on the back side of the silicon wafer 1;
[0057] S9, forming a passivation layer 7 and an anti-reflection layer on both sides of the silicon wafer 1 in sequence;
[0058] S10 , preparing a positive electrode 10 and a negative electrode 11 on the back side of the silicon wafer 1 .
[0059] The preparation method of the above-mentioned IBC solar cell, on the one hand, forms an isolation area through laser patterning and wet etching and then forms a tunneling oxide layer in the isolation area, effectively controls the thickness of the tunneling oxide layer in the isolation area, improves the density and functional stability of the tunneling oxide layer, thereby improving the passivation effect of the back side, and further improves the conversion efficiency of the solar cell; on the other hand, after forming a boron-doped polysilicon layer and a phosphorus-doped polysilicon layer on the back side of the silicon wafer, the front side is texturized, which not only effectively optimizes the surface passivation structure and light trapping structure, improves the density of the front passivation layer, reduces the front surface recombination loss, thereby improving the conversion efficiency of the solar cell, but also helps to simplify the process and is suitable for large-scale production.
[0060] It can be understood that the back side of the silicon wafer 1 includes an N region, a P region and an isolation region, wherein the gap between the N region and the P region is the isolation region; the silicon wafer 1 is preferably an N-type silicon wafer.
[0061] In step S1, the double sides of the silicon wafer are polished by the existing method in the art, and the present invention has no special limitation on this. For example, the double sides of the silicon wafer 1 with a thickness of 100 μm to 180 μm are polished by an acid solution or an alkaline solution, so that both sides of the silicon wafer 1 are thinned by 5 μm to 10 μm.
[0062] In one embodiment, in step S2, a low pressure chemical vapor deposition (LPCVD) process or a plasma enhanced chemical vapor deposition (PECVD) process is used to prepare the first tunnel oxide layer 21 and the boron-doped polysilicon layer 3, which is beneficial to improving the controllability and flexibility of the process, improving the deposition uniformity and consistency, and optimizing the film properties. It avoids the limitations of the injection energy and dose of the traditional ion implantation method, which is beneficial to reducing the equipment operating cost and improving the production capacity.
[0063] It should be noted that the LPCVD process and PECVD process of the present invention both adopt conventional methods in the art. The present invention has no special restrictions on deposition time, deposition temperature, gas flow rate, advancement time, advancement temperature, etc. Those skilled in the art can make choices based on product quality and actual needs.
[0064] In one embodiment, the thickness of the first tunnel oxide layer 21 is 1 nm to 3 nm, including but not limited to any value among 1 nm, 1.2 nm, 1.5 nm, 2 nm, 2.5 nm, and 3 nm, or a range between any two values.
[0065] In one embodiment, the boron-doped polysilicon layer 3 has a thickness of 200 nm to 350 nm, including but not limited to any value among 200 nm, 220 nm, 230 nm, 250 nm, 280 nm, 300 nm, 320 nm, and 350 nm, or a range between any two values.
[0066] It should be noted that the present invention has no special limitation on the doping concentration of the boron-doped polysilicon layer 3 .
[0067] In one embodiment, a borosilicate glass layer 4 is formed on the surface of the boron-doped polysilicon layer 3 , and the thickness of the borosilicate glass layer 4 is 30 nm to 60 nm.
[0068] like Figure 2 As shown, it is a schematic diagram of the solar cell structure obtained in step S3 in one embodiment of the present invention. In step S3, the borosilicate glass layer 4 in the N region and the isolation region is first removed by a first laser patterning, and then the first tunneling oxide layer 21 and the boron-doped polysilicon layer 3 in the N region and the isolation region are removed by a first wet etching, while the P region is not corroded under the protection of the borosilicate glass layer 4.
[0069] It should be noted that the two laser patterning processes and three wet etching processes of the present invention all adopt existing methods in the art, and the present invention has no special limitation on this.
[0070] In one embodiment, in step S4, the second tunnel oxide layer 22 and the phosphorus-doped polysilicon layer 5 are prepared by a low pressure chemical vapor deposition (LPCVD) process or a plasma enhanced chemical vapor deposition (PECVD) process.
[0071] In one embodiment, the thickness of the second tunnel oxide layer 22 is 1 nm to 3 nm, including but not limited to any value among 1 nm, 1.2 nm, 1.5 nm, 2 nm, 2.5 nm, and 3 nm, or a range between any two values.
[0072] Preferably, the thickness of the first tunneling oxide layer 21 is greater than or equal to the thickness of the second tunneling oxide layer 22, which is beneficial to improving the passivation performance of the manufactured IBC solar cell and improving the cell conversion efficiency.
[0073] In one embodiment, the phosphorus-doped polysilicon layer 5 has a thickness of 100 nm to 250 nm, including but not limited to any value among 100 nm, 120 nm, 130 nm, 150 nm, 180 nm, 200 nm, 220 nm, and 250 nm or a range between any two values.
[0074] Preferably, the thickness of the boron-doped polysilicon layer 3 is greater than the thickness of the phosphorus-doped polysilicon layer 5, which is beneficial to improving the contact performance of the manufactured IBC solar cell and improving the cell conversion efficiency.
[0075] It should be noted that the present invention has no special limitation on the doping concentration of the phosphorus-doped polysilicon layer 5 .
[0076] In one embodiment, a phosphosilicate glass layer 6 is formed on the surface of the phosphorus-doped polysilicon layer 5 , and the thickness of the phosphosilicate glass layer 6 is 20 nm to 50 nm.
[0077] In step S5 and step S6, all the layers of the front side coating are removed by a second wet etching, and then the front side is textured, which not only effectively optimizes the surface passivation structure and light trapping structure, improves the density of the front side passivation layer, reduces the front surface recombination loss, thereby improving the conversion efficiency of the solar cell, but also helps to simplify the process and is suitable for large-scale production. Figure 3 , which is a schematic diagram of a solar cell structure obtained in step S6 in one embodiment of the present invention, wherein a pyramid velvet surface is formed on the front side of the silicon wafer 1 .
[0078] It can be understood that during the second wet etching, the layers removed include the phosphosilicate glass layer 6 coated on the front and side surfaces, the phosphorus-doped polysilicon layer 5, the second tunneling oxide layer 22, the borosilicate glass layer 4, the boron-doped polysilicon layer 3 and the first tunneling oxide layer 21.
[0079] Specifically, the second wet etching adopts a wet chain method, and the texturing adopts a wet tank method.
[0080] In step S7, the phosphosilicate glass layer 6 in the P region and the isolation region is removed by a second laser patterning, and then the second tunneling oxide layer 22 and the phosphorus-doped polysilicon layer 5 in the P region and the isolation region are first removed by a third wet etching, and then the borosilicate glass layer 4 in the P region and the phosphosilicate glass layer 6 in the N region are removed. Figure 4 As shown, it is a schematic diagram of the solar cell structure obtained in step S7 in one embodiment of the present invention. On the back side of the silicon wafer 1, the P region is etched to the boron-doped polysilicon layer 3, the N region is etched to the phosphorus-doped polysilicon layer 5, and the isolation region is etched to the silicon wafer 1.
[0081] like Figure 5 As shown, it is a schematic diagram of the solar cell structure prepared in step S8 in one embodiment of the present invention. In step S8, a third tunneling oxide layer 23 is formed on the silicon substrate in the isolation area, and the thickness of the third tunneling oxide layer 23 is effectively controlled, and the density and functional stability of the third tunneling oxide layer 23 are improved, thereby improving the passivation effect on the back side, and further improving the conversion efficiency of the solar cell.
[0082] In one embodiment, the third tunnel oxide layer 23 is formed by ultraviolet laser etching or thermal oxidation.
[0083] In one embodiment, the thickness of the third tunnel oxide layer 23 is 1 nm to 5 nm, including but not limited to any point value among 1 nm, 1.5 nm, 2 nm, 2.5 nm, 3 nm, 3.5 nm, 4 nm, 4.5 nm, and 5 nm, or a range value between any two of them.
[0084] Preferably, the thickness of the third tunnel oxide layer 23 is greater than or equal to the thickness of the first tunnel oxide layer 21 .
[0085] More preferably, the thickness of the third tunnel oxide layer 23 is greater than or equal to the thickness of the first tunnel oxide layer 21, and the thickness of the first tunnel oxide layer 21 is greater than or equal to the thickness of the second tunnel oxide layer 22, which is beneficial to further reduce recombination, improve passivation effect, and thus improve battery conversion efficiency.
[0086] In one embodiment, step S9 includes the following steps:
[0087] S91, forming the passivation layer 7 on both sides of the silicon wafer 1;
[0088] S92, forming a back anti-reflection layer 8 on the back side of the silicon wafer;
[0089] S93, forming a front anti-reflection layer 9 on the front side of the silicon wafer 1, wherein the front anti-reflection layer 9 includes a first silicon nitride layer 91, a second silicon nitride layer 92, a third silicon nitride layer 93, a first silicon oxynitride layer 94, a second silicon oxynitride layer 95, a silicon oxide layer 96 and a magnesium fluoride layer 97 which are stacked from the inside to the outside.
[0090] In step S9, a multilayer anti-reflection layer with good optical performance is prepared on the front side, and a magnesium fluoride layer 97 with a wide transparent band is used as the outermost reflective film, which is not only beneficial to improving the chemical stability and thermal stability of the solar cell, but also realizes multiple refractions of the incident light in the film layer, avoiding the incident light directly incident on the high-refractive index silicon nitride to cause large-angle refraction and lead to light loss, and solves the problem of optical mismatch caused by the large refractive index difference between the existing single-layer silicon nitride film layer on the front side and the semiconductor medium film layer, which can reduce the overall reflectivity of the front side of the solar cell, reduce light loss, increase light absorption, and improve the conversion efficiency of the IBC solar cell.
[0091] It can be understood that the order of step S92 and step S93 can be interchanged; the present invention has no special restrictions on the thickness and material of the passivation layer 7 and the back anti-reflection layer 8. For example, the passivation layer 7 is an aluminum oxide layer with a thickness of 2nm to 5nm, and the material of the back anti-reflection layer 8 is selected from silicon nitride with a thickness of 60nm to 120nm.
[0092] In one embodiment, the refractive index of each layer in the front anti-reflection layer decreases from the inside to the outside.
[0093] Specifically, a multi-layer anti-reflection layer is prepared on the front side by radio frequency-generated plasma reaction, and the refractive index gradient of the three-layer silicon nitride layer is achieved by controlling the ammonia / silane gas flow ratio.
[0094] Preferably, the first silicon nitride layer has a refractive index of 2.2 to 2.3 and a thickness of 20 nm to 30 nm.
[0095] Preferably, the refractive index of the second silicon nitride layer is 2.1-2.2, and the thickness is 20nm-30nm.
[0096] Preferably, the third silicon nitride layer has a refractive index of 2.0 to 2.1 and a thickness of 15 nm to 25 nm.
[0097] Preferably, the first silicon oxynitride layer has a refractive index of 1.8 to 2.0 and a thickness of 5 nm to 15 nm.
[0098] Preferably, the second silicon oxynitride layer has a refractive index of 1.6 to 1.8 and a thickness of 3 nm to 10 nm.
[0099] Preferably, the silicon oxide layer has a refractive index of 1.4 to 1.6 and a thickness of 5 nm to 15 nm.
[0100] Preferably, the magnesium fluoride layer has a refractive index of 1.2 to 1.4 and a thickness of 2 nm to 10 nm.
[0101] The present invention also provides an IBC solar cell prepared by the preparation method as described above.
[0102] The back isolation region of the above-mentioned IBC solar cell has a tunneling oxide layer, which is conducive to the selective passage of carriers, effectively reduces the dangling bond recombination rate on the surface of the silicon wafer, plays a good passivation role, reduces the risk of leakage, and is conducive to improving the surface passivation and optical properties of the IBC solar cell at the same time, thereby improving the battery conversion efficiency and stability. In summary, the IBC solar cell of the present invention has a compact structure and is easy to maintain, has excellent battery conversion efficiency, and has a wide range of application prospects.
[0103] The IBC solar cell and its preparation method will be further described below through the following specific examples. However, those skilled in the art will understand that the following examples are only used to illustrate the present invention and should not be considered to limit the scope of the present invention. If no specific conditions are specified in the examples, the conventional conditions or the conditions recommended by the manufacturer are followed. The reagents or instruments used without indicating the manufacturer are all conventional products that can be purchased commercially.
[0104] Example 1
[0105] S1, double-sided polishing of silicon wafer;
[0106] S2, forming a 3nm first tunnel oxide layer and a 350nm boron-doped polysilicon layer on the back side of the silicon wafer in sequence by an LPCVD deposition process;
[0107] S3, performing a first laser patterning on the back side of the silicon wafer to remove the borosilicate glass layer in the N region and the isolation region, and performing a first wet etching to remove the first tunneling oxide layer and the boron-doped polysilicon layer in the N region and the isolation region;
[0108] S4, forming a 3nm second tunnel oxide layer and a 250nm phosphorus-doped polysilicon layer on the back side of the silicon wafer in sequence by an LPCVD deposition process;
[0109] S5, performing a second wet etching on the front side of the silicon wafer to remove all the layers of the front side plating;
[0110] S6, texturing the front side of the silicon wafer so that a velvet structure is formed on the front side of the silicon wafer;
[0111] S7, performing a second laser patterning on the back side of the silicon wafer to remove the phosphorus silicon glass layer in the P region and the isolation region, and performing a third wet etching to etch the P region to the boron-doped polysilicon layer, the N region to the phosphorus-doped polysilicon layer, and the isolation region to the silicon wafer;
[0112] S8, growing a 3 nm third tunnel oxide layer in the isolation region on the back side of the silicon wafer by thermal oxidation;
[0113] S9, forming a 5nm aluminum oxide layer on both sides of the silicon wafer by a PECVD deposition process, forming an 80nm silicon nitride layer on the back side of the silicon wafer, and sequentially forming a first silicon nitride layer (refractive index 2.3, thickness 30nm), a second silicon nitride layer (refractive index 2.2, thickness 25nm), a third silicon nitride layer (refractive index 2.1, thickness 20nm), a first silicon oxynitride layer (refractive index 2.0, thickness 15nm), a second silicon oxynitride layer (refractive index 1.8, thickness 10nm), a silicon oxide layer (refractive index 1.6, thickness 10nm) and a magnesium fluoride layer (refractive index 1.4, thickness 10nm) on the front side of the silicon wafer;
[0114] S10. Prepare a positive electrode and a negative electrode on the back side of the silicon wafer.
[0115] Example 2
[0116] The difference between Example 2 and Example 1 is that, in step S2, a 2nm first tunneling oxide layer and a 250nm boron-doped polysilicon layer are formed in sequence on the back side of the silicon wafer through a PECVD deposition process; in step S4, a 1nm second tunneling oxide layer and a 250nm phosphorus-doped polysilicon layer are formed in sequence on the back side of the silicon wafer through an LPCVD deposition process; in step S8, a 5nm third tunneling oxide layer is grown in the isolation area on the back side of the silicon wafer through ultraviolet laser etching.
[0117] In step S9, a first silicon nitride layer (refractive index 2.2, thickness 20nm), a second silicon nitride layer (refractive index 2.1, thickness 20nm), a third silicon nitride layer (refractive index 2.0, thickness 15nm), a first silicon oxynitride layer (refractive index 1.8, thickness 5nm), a second silicon oxynitride layer (refractive index 1.6, thickness 3nm), a silicon oxide layer (refractive index 1.4, thickness 5nm) and a magnesium fluoride layer (refractive index 1.2, thickness 5nm) are formed in sequence on the front side of the silicon wafer.
[0118] Example 3
[0119] The difference between Example 3 and Example 1 is that in step S9, a 3 nm aluminum oxide layer and a 100 nm silicon nitride layer are sequentially formed on both sides of the silicon wafer.
[0120] The performance of the IBC solar cells prepared in Examples 1 to 3 was tested using a Halm tester to measure the open circuit voltage (Voc), short circuit current density (Jsc), fill factor (FF) and conversion efficiency (Eta). All test results are shown in Table 1.
[0121] Table 1
[0122] Voc(mV) <![CDATA[Jsc(mA / cm 2 )]]> FF(%) Eta(%) Example 1 735 43.01 80.66 25.8 Example 2 732 42.85 80.15 25.5 Example 3 728 42.75 79.98 25.02
[0123] According to the results in Table 1, the IBC solar cell prepared by the present invention has a high cell conversion efficiency, and has a high open circuit voltage and short circuit current density, and a low fill factor. In summary, the preparation method provided by the present invention can effectively control the thickness of the tunneling oxide layer and improve the density of the tunneling oxide layer, thereby improving the passivation effect of the solar cell, and the preparation method of the present invention has a simple process and is suitable for large-scale production; the prepared IBC solar cell has excellent conversion efficiency and has broad application prospects.
[0124] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0125] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.
Claims
1. A method for preparing an IBC solar cell, characterized in that: The preparation method comprises: S1, double-sided polishing of silicon wafer; S2, forming a first tunneling oxide layer and a boron-doped polysilicon layer in sequence on the back side of the silicon wafer; S3, performing a first laser patterning on the back side of the silicon wafer to remove the borosilicate glass layer in the N region and the isolation region, and performing a first wet etching to remove the first tunneling oxide layer and the boron-doped polysilicon layer in the N region and the isolation region; S4, forming a second tunneling oxide layer and a phosphorus-doped polysilicon layer in sequence on the back side of the silicon wafer; S5, performing a second wet etching on the front side of the silicon wafer to remove all the layers of the front side plating; S6, texturing the front side of the silicon wafer so that a velvet structure is formed on the front side of the silicon wafer; S7, performing a second laser patterning on the back side of the silicon wafer to remove the phosphorus silicon glass layer in the P region and the isolation region, and performing a third wet etching to etch the P region to the boron-doped polysilicon layer, the N region to the phosphorus-doped polysilicon layer, and the isolation region to the silicon wafer; S8, growing a third tunneling oxide layer in the isolation region on the back side of the silicon wafer; S9, forming a passivation layer and an anti-reflection layer on both sides of the silicon wafer in sequence; S10. Prepare a positive electrode and a negative electrode on the back side of the silicon wafer.
2. The method for preparing an IBC solar cell according to claim 1, characterized in that: The thickness of the first tunnel oxide layer and the second tunnel oxide layer are independently selected from 1 nm to 3 nm; And / or, the thickness of the third tunnel oxide layer is 1 nm to 5 nm.
3. The method for preparing an IBC solar cell according to claim 1, characterized in that: The thickness of the third tunnel oxide layer is greater than or equal to the thickness of the first tunnel oxide layer.
4. The method for preparing an IBC solar cell according to claim 1, characterized in that: The thickness of the first tunnel oxide layer is greater than or equal to the thickness of the second tunnel oxide layer.
5. The method for preparing an IBC solar cell according to claim 1, characterized in that: The thickness of the boron-doped polysilicon layer is 200nm to 350nm; And / or, the thickness of the phosphorus-doped polysilicon layer is 100 nm to 250 nm.
6. The method for preparing an IBC solar cell according to claim 1, characterized in that: The thickness of the boron-doped polysilicon layer is greater than or equal to the thickness of the phosphorus-doped polysilicon layer.
7. The method for preparing an IBC solar cell according to claim 1, characterized in that: The process of sequentially forming a passivation layer and an anti-reflection layer on both sides of a silicon wafer includes the following steps: forming the passivation layer on both sides of the silicon wafer; forming a back anti-reflection layer on the back side of the silicon wafer; A front anti-reflection layer is formed on the front side of the silicon wafer, and the front anti-reflection layer includes a first silicon nitride layer, a second silicon nitride layer, a third silicon nitride layer, a first silicon oxynitride layer, a second silicon oxynitride layer, a silicon oxide layer and a magnesium fluoride layer stacked from inside to outside.
8. The method for preparing an IBC solar cell according to claim 7, characterized in that: The refractive index of each layer in the front anti-reflection layer decreases from the inside to the outside.
9. The method for preparing an IBC solar cell according to claim 8, characterized in that: The refractive index of the first silicon nitride layer is 2.2 to 2.3, and the thickness is 20 nm to 30 nm; And / or, the refractive index of the second silicon nitride layer is 2.1-2.2, and the thickness is 20nm-30nm; And / or, the refractive index of the third silicon nitride layer is 2.0-2.1, and the thickness is 15nm-25nm; And / or, the first silicon oxynitride layer has a refractive index of 1.8 to 2.0 and a thickness of 5 nm to 15 nm; And / or, the refractive index of the second silicon oxynitride layer is 1.6 to 1.8, and the thickness is 3 nm to 10 nm; And / or, the silicon oxide layer has a refractive index of 1.4 to 1.6 and a thickness of 5 nm to 15 nm; And / or, the magnesium fluoride layer has a refractive index of 1.2 to 1.4 and a thickness of 2 nm to 10 nm.
10. An IBC solar cell prepared according to the preparation method according to any one of claims 1 to 9.