Crystalline silicon BC battery texturing additive and texturing method thereof
By optimizing the composition and process of texturing additives, the corrosion control problem of the micro-region structure on the back of BC batteries was solved, achieving precise corrosion of the gap area and protection of the doped layer, thus improving battery performance and yield.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-06
- Publication Date
- 2026-03-13
AI Technical Summary
Existing texturing additives cannot precisely control the complex micro-region structure on the back of crystalline silicon BC cells, resulting in uncontrolled corrosion depth in the gap area and easy corrosion damage to the N-Poly/P-Poly doped surface, affecting cell performance and yield.
By employing texturing additives containing defoamers, strong nucleating agents, surfactants, accelerators, stabilizers, and strong protectants, and controlling the alkaline reaction, precise etching of the gap region and protection of the N-Poly/P-Poly doped layer are achieved.
Precise corrosion control of the gap region was achieved, ensuring the electrical performance of the back structure and improving carrier collection efficiency and battery performance.
Smart Images
Figure CN121665729A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of crystalline silicon batteries, specifically to a texturing additive for crystalline silicon BC batteries and a texturing method thereof. Background Technology
[0002] Crystalline silicon solar cells are the mainstream technology in the photovoltaic industry. Their core technology lies in significantly reducing sunlight reflection from the silicon surface through a light-trapping structure, or "textured surface." For conventional cells, fabricating a uniform pyramidal textured structure on the front side of the silicon wafer effectively increases the optical path, improves short-circuit current, and ultimately enhances photoelectric conversion efficiency. This texturing process typically relies on an alkaline solution to anisotropically etch the silicon lattice, supplemented by texturing additives to optimize the reaction process and control the morphology, size, and uniformity of the pyramids.
[0003] In recent years, back-contact (BC) battery technology, due to its precise arrangement of both positive and negative electrodes on the back of the battery, completely eliminates the light-shielding loss of the front-side metal grid lines. This not only achieves higher theoretical conversion efficiency but also gives the module an aesthetically pleasing all-black appearance, making it a key development direction for next-generation high-efficiency battery technology. However, the unique structure of BC batteries also brings unprecedented manufacturing challenges. The back side needs to be patterned using processes such as lasers to form alternating N-type and P-type doped regions (i.e., N-Poly and P-Poly regions), as well as micro-grooves (often called gap regions) for insulation. In the final battery structure, this gap region on the back side also needs to be etched to form an effective textured surface to passivate the interface, while the main textured surface on the front side needs to maintain excellent uniformity.
[0004] Existing conventional texturing additives and processes are primarily designed for single-sided or double-sided homojunction solar cells, focusing on forming a uniform textured surface on a flat or pre-treated silicon surface. However, when applied to the complex structure of BC (Browser-Based Cell) cells, these technologies reveal significant shortcomings: they lack the ability to selectively etch and protect specific areas on the back side. Specifically, while texturing the front side, the alkaline texturing solution inevitably penetrates and acts on the gap region and the sensitive N-Poly and P-Poly surfaces on the back side. Existing additive systems cannot precisely control the corrosion kinetics of the gap region, resulting in inconsistent corrosion depths and difficulty in stably forming the desired 2-5 micrometer textured morphology. More seriously, they cannot effectively protect the N-Poly and P-Poly doped layers, which are extremely sensitive to alkaline solutions, thus damaging these critical electrical functional regions. This severely degrades the cell's parallel resistance and carrier collection efficiency, ultimately becoming one of the key bottlenecks restricting the yield and performance improvement of BC cells in mass production. Summary of the Invention
[0005] To address the aforementioned technical problems, this invention provides a texturing additive for crystalline silicon BC batteries. This additive solves the problems of uncontrolled corrosion depth in the gap region, easy corrosion damage to the N-Poly / P-Poly doped surface, and consequently, decreased battery performance and low yield caused by the lack of precise control over the complex micro-region structure on the back of BC batteries in conventional texturing techniques.
[0006] A texturing additive for crystalline silicon BC batteries, comprising the following components by weight percentage:
[0007] The composition includes: defoamer 0.1-5%, strong nucleating agent 0.2-2.0%, surfactant 0.2-0.8%, accelerator 0.1-0.5%, stabilizer 0.01-0.5%, strong protective agent 0.3-0.5%, and the balance being deionized water.
[0008] Preferably, the defoaming agent is one or more of gum arabic, sodium alginate, gelatin, chitosan, hyaluronic acid, and rhamnolipid.
[0009] The strong nucleating agent is one or a combination of sodium phosphopolycarboxylate, sodium polymethacrylate, and sodium diisobutylnaphthalenesulfonate.
[0010] Preferably, the surfactant is one or a combination of sodium dodecyl diphenyl ether disulfonate, Tween 20, and octylphenol polyoxyethylene ether.
[0011] Preferably, the accelerator is one or a combination of 3-chloronitrobenzene, p-chloronitrobenzene, and 2,3-dichloronitrobenzene.
[0012] Preferably, the stabilizer is one or a combination of maleic acid, benzenemethylsuccinic acid, and phthalic anhydride;
[0013] The strong protective agent is one or a combination of two of polyether silane and sodium molybdate.
[0014] A texturing method using the texturing additive for crystalline silicon BC cells as described above includes the following steps:
[0015] S1: Place the monocrystalline silicon wafer in an alkaline polishing bath with an alkali concentration of 1-2% and a temperature of 78-82℃ for 2-3 minutes for pretreatment to remove the damaged layer;
[0016] S2: Place the silicon wafer treated in S1 into a hydrogen peroxide bath with an alkali concentration of 0.2-0.3%, a hydrogen peroxide concentration of 2-3%, and a temperature of 60-70℃ for 2-3 minutes to clean it.
[0017] S3: Place the silicon wafers treated in S2 into a pure water bath and rinse for 2-3 minutes;
[0018] S4: Place the silicon wafer treated in S3 into a texturing tank for texturing for 7-8 minutes. The texturing solution consists of the texturing additive at a concentration of 0.5-1.2% and an alkaline solution at a concentration of 0.5-1%. The temperature of the texturing tank is 70-75℃.
[0019] S5: Wash and dry the silicon wafers after S4 treatment.
[0020] Preferably, the alkaline solutions in S1 and S4 are independently selected from sodium hydroxide or potassium hydroxide solutions.
[0021] Preferably, the drying temperature in step S5 is 80-100℃ and the drying time is 8-13 minutes.
[0022] Preferably, after drying in step S5, the texturing method further includes step S6: detecting the gap depth, n-poly and p-poly surface morphology, frontal reflectivity, and texturing uniformity of the texturized silicon wafer.
[0023] A crystalline silicon BC cell is prepared using the texturing method described above.
[0024] Compared with the prior art, the present invention has the following beneficial effects:
[0025] By introducing accelerators and stabilizers and leveraging their synergistic effect, precise and controllable etching of the gap area formed by laser grooving on the back of the battery is achieved. The accelerator strongly adsorbs onto the silicon surface, accelerating the etching of the gap area by the alkaline solution, ensuring the formation of the necessary 2-5 micrometer etching depth and generating a textured surface structure. The stabilizer, through adsorption and film formation, effectively buffers and slows down the reaction rate, acting like a "brake" and "guiding system" for the etching process. This precisely controls the etching depth within the target range, avoiding the risk of leakage due to excessive etching or PN junction failure due to insufficient etching.
[0026] By combining a strong protective agent with an optimized process, efficient texturing on the front side is achieved while effectively protecting the N-Poly and P-Poly doped layers on the back side from alkaline damage. The strong protective agent forms a dense protective film on the doped polycrystalline silicon surface, selectively blocking the attack of hydroxyl ions, thus perfectly maintaining the electrical performance of the back field structure. This ensures the carrier collection efficiency of the back contact cell core, laying a solid foundation for the cell to achieve high open-circuit voltage and fill factor. Attached Figure Description
[0027] Figure 1 This is the frontal zeta morphology of the BC fabrication process of the present invention.
[0028] Figure 2 The morphology of n-pol and p-poly Zeta on the front and back sides of the BC texturing process of this invention is shown.
[0029] Figure 3 This shows the Zeta morphology of the back gap, n-pol, and p-poly after BC texturing in Example 1 of the present invention.
[0030] Figure 4 This is the frontal morphology after BC texturing in Embodiment 1 of the present invention.
[0031] Figure 5 This shows the Zeta morphology of the back gap, n-pol, and p-poly after BC texturing in Example 2 of the present invention.
[0032] Figure 6 This is the frontal morphology after BC texturing in Embodiment 2 of the present invention.
[0033] Figure 7 This is the Zeta morphology of the back gap, n-pol, and p-poly of the BC-textured material in Comparative Example 1 of this invention.
[0034] Figure 8 This is the frontal morphology of BC after texturing in Comparative Example 1 of the present invention. Detailed Implementation
[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0036] Example 1:
[0037] This embodiment provides a BC battery texturing additive, which comprises the following components by weight percentage: sodium alginate 2%, sodium polymethacrylate 0.2%, sodium dodecyl diphenyl ether disulfonate 0.3%, 3-chloronitrobenzene 0.2%, maleic acid 0.1%, polyether silane 0.4%, and the balance being deionized water.
[0038] The texturing method for BC battery texturing additives follows these steps: Monocrystalline silicon wafers are placed in an alkaline polishing bath with a sodium hydroxide concentration of 2% at 80°C for 2 minutes; after polishing, the wafers are rinsed in a hydrogen peroxide bath with a sodium hydroxide concentration of 0.2% and a hydrogen peroxide concentration of 2% at 65°C for 2 minutes; after polishing, the wafers are rinsed in pure water for 2 minutes; after polishing, the wafers are placed in a texturing bath with a texturing solution containing a texturing additive concentration of 0.5% and a sodium hydroxide solution concentration of 0.5%, at a texturing bath temperature of 74°C for 7 minutes; after texturing, the wafers are rinsed with water for 2 minutes and then dried in an 80°C drying oven for 10 minutes. The dried texturized wafers are then tested using Zeta assay to measure gap depth and observe n-poly and p-poly morphology, D8 reflectance is tested, and SEM scans are used to check the uniformity of the texturized surface on the front side.
[0039] Example 2:
[0040] This embodiment provides a BC battery texturing additive, which comprises the following components by weight percentage: 3% chitosan, 1% sodium diisobutylnaphthalene sulfonate, 0.6% sodium dodecyl diphenyl ether disulfonate, 0.4% 2,3-dichloronitrobenzene, 0.2% benzenemethylene succinic acid, 0.3% sodium molybdate, and the balance being deionized water.
[0041] The texturing method for BC battery texturing additives follows these steps: Monocrystalline silicon wafers are placed in an alkaline polishing bath with a sodium hydroxide concentration of 2% at 80°C for 2 minutes; after polishing, the wafers are rinsed in a hydrogen peroxide bath with a sodium hydroxide concentration of 0.2% and a hydrogen peroxide concentration of 2% at 65°C for 2 minutes; after polishing, the wafers are rinsed in pure water for 2 minutes; after polishing, the wafers are placed in a texturing bath with a texturing solution containing a texturing additive concentration of 0.5% and a sodium hydroxide solution concentration of 0.5%, at a texturing bath temperature of 73°C for 8 minutes; after texturing, the wafers are rinsed with water for 2 minutes and then dried in an 80°C drying oven for 10 minutes. The dried texturized wafers are then tested using Zeta assay to measure gap depth and observe n-poly and p-poly morphology, D8 reflectance is tested, and SEM scans are used to check the uniformity of the textured surface on the front side.
[0042] Comparative Example 1:
[0043] This comparative example provides a BC battery texturing additive, which comprises the following components by weight percentage: 3% chitosan, 0.5% sodium phosphopolycarboxylate, 0.4% Tween 20, 0.2% benzenemethyl succinic acid, 0.5% sodium molybdate, and the balance being deionized water.
[0044] The texturing method for BC battery texturing additives follows these steps: Monocrystalline silicon wafers are placed in an alkaline polishing bath with a sodium hydroxide concentration of 2% at 80°C for 2 minutes; after polishing, the wafers are rinsed in a hydrogen peroxide bath with a sodium hydroxide concentration of 0.2% and a hydrogen peroxide concentration of 2% at 65°C for 2 minutes; after polishing, the wafers are rinsed in pure water for 2 minutes; after polishing, the wafers are placed in a texturing bath with a texturing solution containing a texturing additive concentration of 0.5% and a sodium hydroxide solution concentration of 0.8%, at 75°C for 8 minutes; after texturing, the wafers are rinsed with water for 2 minutes and then dried in an 80°C drying oven for 10 minutes. The dried texturized wafers are then tested using Zeta assay to measure gap depth and observe n-poly and p-poly morphology, D8 reflectance is tested, and SEM scans are used to check the uniformity of the textured surface on the front side.
[0045] The gap depth, reflectivity, and textured surface size data of the silicon wafers prepared in Examples 1, 2, and 1 are shown in the table below:
[0046] Group gap (μm) Reflectivity (%) Surface size (μm) Example 1 3.2 9.2 1.65 Example 2 4.0 9.3 1.66 Comparative Example 1 0.9 9.5 1.64
[0047] The difference between Comparative Example 1 and Examples 1 and 2 is that the flocking additive in Comparative Example 1 does not contain an accelerator; otherwise, they are the same. Example 1, in conjunction with the attached... Figure 3 and attached Figure 4 It can be seen that the sheet texturized with BC texturing additive containing the accelerator 3-chloronitrobenzene in Example 1 has a gap etching depth of 3.2 micrometers, a frontal reflectivity of 9.2, a texturing size of 1.65, uniform pyramid shape, and the p-poly and n-poly surfaces are not damaged; Example 2, combined with the attached... Figure 5 and attached Figure 6 As can be seen, the wafer in Example 2, texturized with the BC texturing additive containing accelerators 2 and 3-dichloronitrobenzene, has a gap etching depth of 4.0 micrometers, a frontal reflectivity of 9.3, a textured surface size of 1.66, and a uniform pyramid shape. Furthermore, the p-poly and n-poly surfaces remain intact. In contrast, the wafer in Comparative Example 1, texturized with the BC texturing additive without accelerators, has a gap etching depth of only 0.9 micrometers, a frontal reflectivity of 9.5, a textured surface size of 1.64, and a uniform pyramid shape. However, the phosphorus silicate glass on the p-poly surface is not completely removed. Because there is no etching depth in the gap between the p-poly and n-poly surfaces, an effective PN junction cannot be formed, severely impacting the photoelectric conversion efficiency. The comparison between Example 1, Example 2, and Comparative Example 1 demonstrates that the accelerator introduced in the optimized BC texturing additive of this invention can effectively control the gap etching depth.
[0048] Example 3:
[0049] This embodiment provides a BC battery texturing additive, which comprises the following components by weight percentage: 1.5% gum arabic, 0.8% sodium phosphopolycarboxylate, 0.4% Tween 20, 0.3% p-chloronitrobenzene, 0.05% phthalic anhydride, 0.35% polyether silane, and the balance being deionized water.
[0050] The texturing method for BC battery texturing additives follows these steps: Monocrystalline silicon wafers are placed in an alkaline polishing bath with a potassium hydroxide concentration of 1.5% at a temperature of 79°C for 2.5 minutes; after polishing, the wafers are cleaned in a hydrogen peroxide bath with a potassium hydroxide concentration of 0.25%, a hydrogen peroxide concentration of 2.5%, and a temperature of 68°C for 2.5 minutes; after cleaning, the wafers are cleaned in a pure water bath for 2.5 minutes; subsequently, they are placed in a texturing bath with a texturing additive concentration of 0.8% and a potassium hydroxide concentration of 0.8%, at a temperature of 72°C for 7.5 minutes; after texturing, the wafers are washed with water for 2.5 minutes and then dried in an 85°C drying oven for 9 minutes.
[0051] Example 4
[0052] This embodiment provides a BC battery texturing additive, which comprises the following components by weight percentage: 0.5% gelatin, 1.2% sodium polymethacrylate, 0.5% octylphenol polyoxyethylene ether, 0.1% 3-chloronitrobenzene, 0.4% benzenemethylene succinic acid, 0.45% sodium molybdate, and the balance being deionized water.
[0053] The texturing method for BC battery texturing additives follows these steps: Monocrystalline silicon wafers are placed in an alkaline polishing bath with a sodium hydroxide concentration of 1% at a temperature of 81°C for 2 minutes; after polishing, the wafers are cleaned in a hydrogen peroxide bath with a sodium hydroxide concentration of 0.3% and a hydrogen peroxide concentration of 3% at a temperature of 62°C for 3 minutes; after cleaning, the wafers are cleaned in a pure water bath for 2 minutes; subsequently, they are placed in a texturing bath with a texturing additive concentration of 1.0%, a sodium hydroxide concentration of 0.6%, a texturing bath temperature of 75°C, and a texturing time of 7 minutes; after texturing, the wafers are washed with water for 3 minutes and then dried in a 90°C drying oven for 8 minutes.
[0054] Example 5
[0055] This embodiment provides a BC battery texturing additive, which comprises the following components by weight percentage: 4% rhamnolipid, 0.3% sodium diisobutylnaphthalene sulfonate, 0.7% sodium dodecyl diphenyl ether disulfonate, 0.5% 2,3-dichloronitrobenzene, 0.02% maleic acid, 0.5% polyether silane, and the balance being deionized water.
[0056] The texturing method for BC battery texturing additives follows these steps: Monocrystalline silicon wafers are placed in an alkaline polishing bath with a potassium hydroxide concentration of 2% at a temperature of 78°C for 3 minutes; after polishing, the wafers are cleaned in a hydrogen peroxide bath with a potassium hydroxide concentration of 0.2%, a hydrogen peroxide concentration of 2%, and a temperature of 70°C for 2 minutes; after cleaning, the wafers are cleaned in a pure water bath for 3 minutes; subsequently, they are placed in a texturing bath with a texturing additive concentration of 1.2%, a potassium hydroxide concentration of 1.0%, a texturing bath temperature of 70°C, and a texturing time of 8 minutes; after texturing, the wafers are washed with water for 2 minutes and then dried in a 100°C drying oven for 8 minutes.
[0057] Example 6
[0058] This embodiment provides a BC battery texturing additive, which comprises the following components by weight percentage: 0.1% hyaluronic acid, 1.5% sodium phosphopolycarboxylate, 0.2% Tween 20, 0.4% p-chloronitrobenzene, 0.5% phthalic anhydride, 0.3% sodium molybdate, and the balance being deionized water.
[0059] The texturing method for BC battery texturing additives follows these steps: Monocrystalline silicon wafers are placed in an alkaline polishing bath with a sodium hydroxide concentration of 1.8% at a temperature of 82°C for 2 minutes; after polishing, the wafers are cleaned in a hydrogen peroxide bath with a sodium hydroxide concentration of 0.28% and a hydrogen peroxide concentration of 2.8% at a temperature of 64°C for 2.2 minutes; after cleaning, the wafers are cleaned in a pure water bath for 2.2 minutes; subsequently, they are placed in a texturing bath with a texturing additive concentration of 0.7% and a sodium hydroxide concentration of 0.7%, at a temperature of 71°C for 7.8 minutes; after texturing, the wafers are washed with water for 2.8 minutes and then dried in an 88°C drying oven for 11 minutes.
[0060] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various equivalent transformations can be made to the technical solutions of the present invention, and all such equivalent transformations fall within the protection scope of the present invention.
Claims
1. A texturing additive for crystalline silicon BC batteries, characterized in that, By weight percentage, it includes the following components: The composition includes: defoamer 0.1-5%, strong nucleating agent 0.2-2.0%, surfactant 0.2-0.8%, accelerator 0.1-0.5%, stabilizer 0.01-0.5%, strong protective agent 0.3-0.5%, and the balance being deionized water.
2. The texturing additive for crystalline silicon BC batteries according to claim 1, characterized in that, The defoaming agent is one or more of gum arabic, sodium alginate, gelatin, chitosan, hyaluronic acid, and rhamnolipid; The strong nucleating agent is one or a combination of sodium phosphopolycarboxylate, sodium polymethacrylate, and sodium diisobutylnaphthalenesulfonate.
3. The texturing additive for crystalline silicon BC batteries according to claim 1, characterized in that, The surfactant is one or more of sodium dodecyl diphenyl ether disulfonate, Tween 20, and octylphenol polyoxyethylene ether.
4. The texturing additive for crystalline silicon BC batteries according to claim 1, characterized in that, The accelerator is one or a combination of 3-chloronitrobenzene, p-chloronitrobenzene, and 2,3-dichloronitrobenzene.
5. The texturing additive for crystalline silicon BC batteries according to claim 1, characterized in that, The stabilizer is one or more of maleic acid, benzenemethylsuccinic acid, and phthalic anhydride; The strong protective agent is one or a combination of two of polyether silane and sodium molybdate.
6. A texturing method using the texturing additive for crystalline silicon BC cells as described in any one of claims 1-5, characterized in that, Includes the following steps: S1: Place the monocrystalline silicon wafer in an alkaline polishing bath with an alkali concentration of 1-2% and a temperature of 78-82℃ for 2-3 minutes for pretreatment to remove the damaged layer; S2: Place the silicon wafer treated in S1 into a hydrogen peroxide bath with an alkali concentration of 0.2-0.3%, a hydrogen peroxide concentration of 2-3%, and a temperature of 60-70℃ for 2-3 minutes to clean it. S3: Place the silicon wafers treated in S2 into a pure water bath and rinse for 2-3 minutes; S4: Place the silicon wafer treated in S3 into a texturing tank for texturing for 7-8 minutes. The texturing solution consists of the texturing additive at a concentration of 0.5-1.2% and an alkaline solution at a concentration of 0.5-1%. The temperature of the texturing tank is 70-75℃. S5: Wash and dry the silicon wafers after S4 treatment.
7. The flocking method according to claim 6, characterized in that, The alkaline solutions in S1 and S4 are independently selected from sodium hydroxide or potassium hydroxide solutions.
8. The flocking method according to claim 6, characterized in that, The drying temperature in S5 is 80-100℃, and the drying time is 8-13 minutes.
9. The flocking method according to claim 6, characterized in that, The texturing method, after drying in step S5, further includes step S6: detecting the gap depth, n-poly and p-poly surface morphology, frontal reflectivity, and texturing uniformity of the texturized silicon wafer.
10. A crystalline silicon BC battery, characterized in that, It is prepared using the flocking method as described in any one of claims 6-9.