Silicon wafer texturing additive, texturing liquid and use method of texturing liquid
By using a velvet-making liquid made of a specific composition of velvet-making additive and an alkali solution, the silicon wafer is fleece-making additives in the prior art to corrosion on the silicon wafer, protecting the PSG layer, and improving the performance of BC batteries.
Patent Information
- Application Number
- CN202411671995.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-21
- Publication Date
- 2025-02-28
AI Technical Summary
The existing velvet-making additives have a large amount of corrosion to the silicon wafer, resulting in the destruction of the PSG layer on the first doped type area on the back, affecting the formation of the PN junction, resulting in the reduction of the BC battery's minor sub-life and opening voltage, and thus reducing the photoelectric conversion efficiency.
The composition of a velvet-making additive is provided, including a nucleation agent, a nucleation enhancer, a surfactant, a protective agent and a protective enhancer. By mixing it with an alkali solution to make a velvet-making liquid, the surface of the silicon wafer is fleece to ensure that the PSG layer on the back of the silicon wafer is not damaged.
After the silicon wafer is fleece-making liquid made of this velvet additive, the second doped area on the front and back of the silicon wafer is uniform and has a low reflectivity. At the same time, the PSG layer in the first doped area on the back of the silicon wafer is protected, which improves the sub-span life and opening pressure of the BC battery, which is conducive to improving the photoelectric conversion efficiency of the battery.
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Figure CN119529844A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the field of photovoltaic technology, in particular to a silicon wafer texturing additive, a texturing liquid and a use method thereof. Background Art
[0002] Back contact solar cells (BC cells for short) are an important development direction of solar cells. They have attracted wide attention for their unique design and significant performance advantages. The BC cells currently under study are textured after alkaline polishing and diffusion. Before textured, the structure is generally a polished morphology on the front side and a first doping type region and a second doping type region on the back side. The first doping type region and the second doping type region are arranged alternately, and the difference between the first doping type region and the second doping type region is that the second doping type region has been laser modified to make the PSG layer relatively loose. After textured, both the front polished surface and the second doping type region on the back side of the BC cell structure need to form a velvet morphology, and the PSG layer in the first doping type region needs to be protected from damage.
[0003] At present, the corrosion of traditional texturing additives on silicon wafers causes damage to the PSG layer in the first doping type area, affecting the formation of the PN junction, and cannot meet the current requirements of BC batteries for texturing technology. The damage to the PSG layer in the first doping type area causes the minority carrier lifetime and opening voltage of the BC battery to decrease, indirectly leading to a 0.2~0.3% reduction in the battery's photoelectric conversion efficiency; and the battery failure caused by this reason accounts for about 3% of the entire BC battery failure. Summary of the invention
[0004] Purpose of the invention: To provide a silicon wafer texturing additive, a texturing liquid and a method of using the same to solve the above-mentioned problems existing in the prior art.
[0005] In a first aspect, the present invention provides a texturing additive, which comprises the following components by weight: 0.05-0.5wt% of a nucleating agent, 0.1-3.0wt% of a nucleating enhancer, 0.2-4.0wt% of a surfactant, 0.2-3.0wt% of a protective agent, 0.5-6.0wt% of a protective enhancer, and the remainder deionized water.
[0006] In one embodiment, the nucleating agent is at least one selected from carboxymethyl starch, hydroxypropyl starch, and sodium carboxymethyl starch.
[0007] In one embodiment, the nucleation enhancer is at least one selected from butynol ether propane sulfonate and butynediol sulfopropyl ether sodium salt.
[0008] In one embodiment, the surfactant is at least one selected from sodium dodecylbenzene sulfonate and sodium polystyrene sulfonate.
[0009] In one embodiment, the protective agent is at least one selected from poly-L-leucine, polyglutamic acid, polyepoxysuccinic acid, polyaspartic acid, and polylysine.
[0010] In one embodiment, the protection enhancer is phosphonobutanetricarboxylic acid.
[0011] In a second aspect, the present invention provides a texturing liquid, which is prepared by adding the texturing additive as described above into an alkaline solution and mixing them uniformly, wherein the mass ratio of the texturing additive to the alkaline solution is 0.5-2.0:100.
[0012] In one embodiment, the alkaline solution is selected from NaOH solution and KOH solution.
[0013] In one embodiment, the mass concentration of NaOH is 1.5% to 4.0%.
[0014] In one embodiment, the mass concentration of KOH is 1.5% to 4.0%.
[0015] In a third aspect, the present invention provides a texturing method, wherein the texturing liquid as described above is used to texturize the surface of a silicon wafer, wherein the texturing step is: immersing the cleaned silicon wafer in the texturing liquid, and performing surface texturing at 65 to 75°C for 300 to 500 seconds.
[0016] In summary, the beneficial effect of the present invention is that after the silicon wafer is textured using the texturing liquid made from the texturing additive of the present invention, the texture structure of the second doped regions on the front and back sides of the silicon wafer is uniform and the reflectivity is low, while the PSG layer of the first doped region on the back side of the silicon wafer is not damaged, thereby improving the minority carrier lifetime and opening voltage of the BC battery, which is beneficial to improving the photoelectric conversion efficiency of the battery. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Figure 1 This is the front morphology of the silicon wafer before texturing; Figure 2 This is the back morphology of the silicon wafer before texturing; Figure 3 This is a front morphology image of the silicon wafer after texturing in Example 1 of the present invention; Figure 4 This is a back surface topography image of the silicon wafer after texturing in Example 1 of the present invention; Figure 5 This is a front morphology image of the silicon wafer after texturing in Example 2 of the present invention; Figure 6 This is a back surface topography image of the silicon wafer after texturing in Example 2 of the present invention; Figure 7 This is a front morphology image of the silicon wafer after texturing in Comparative Example 1 of the present invention; Figure 8 This is a back morphology image of the silicon wafer after texturing in Comparative Example 1 of the present invention. Specific embodiments
[0018] In the following description, a large number of specific details are provided to provide a more thorough understanding of the present invention. However, it is apparent to those skilled in the art that the present invention can be implemented without one or more of these details. In other examples, in order to avoid confusion with the present invention, some technical features well known in the art are not described. Example 1
[0019] The texturing additive disclosed in this embodiment comprises the following components by weight: 0.5wt% hydroxypropyl starch, 0.3wt% butynol ether propane sulfonate, 0.5wt% sodium dodecylbenzene sulfonate, 1wt% polyepoxysuccinic acid, 1.5wt% phosphonobutanetricarboxylic acid, and the balance is deionized water.
[0020] The texturing additive of the above-mentioned Example 1 and NaOH solution (the mass concentration of NaOH is 2%) are stirred and evenly mixed in a mass ratio of 1:100 to prepare a texturing liquid, and then the texturing liquid is used to texturize the surface of the silicon wafer. The texturing process is: immerse the cleaned silicon wafer in the texturing liquid and perform texturing at 68°C for 360s to complete the texturing of the silicon wafer.
[0021] Before texturing, the thickness of the PSG layer in the first doped area on the back of the silicon wafer was 107.97nm. After texturing, the thickness of the PSG layer in the first doped area on the back of the silicon wafer was 40.6nm. The morphology of the front side of the silicon wafer is shown in Figure 1. Figure 3 , the back side of the morphology can be seen Figure 4 . Example 2
[0022] The texturing additive disclosed in this embodiment comprises the following components by weight: 0.3 wt % carboxymethyl starch, 1 wt % butynol ether propane sulfonate, 1 wt % sodium dodecylbenzene sulfonate, 1.5 wt % polyaspartic acid, 2 wt % phosphonobutanetricarboxylic acid, and the balance is deionized water.
[0023] The texturing additive of the above-mentioned Example 2 and NaOH solution (the mass concentration of NaOH is 2%) are stirred and evenly mixed in a mass ratio of 1:100 to prepare a texturing liquid, and then the texturing liquid is used to texturize the surface of the silicon wafer. The texturing process is: immerse the cleaned silicon wafer in the texturing liquid and perform texturing at 73°C for 450s to complete the texturing of the silicon wafer.
[0024] Before texturing, the thickness of the PSG layer in the first doped area on the back of the silicon wafer was 107.56nm. After texturing, the thickness of the PSG layer in the first doped area on the back of the silicon wafer was 38.07nm. The morphology of the front side of the silicon wafer is shown in Figure 2. Figure 5 , the back side of the morphology can be seen Figure 6 .
[0025] Comparative Example 1 The texturing additive (product model: HJ21) produced by Changzhou Shichuang Energy Co., Ltd. and NaOH solution (mass concentration of NaOH: 2%) are stirred and evenly mixed in a mass ratio of 1:100 to form a texturing liquid, which is then used to texturize the surface of the silicon wafer. The texturing process is as follows: the cleaned silicon wafer is immersed in the texturing liquid and texturized at 68°C for 420 seconds to complete the texturing of the silicon wafer.
[0026] Before texturing, the thickness of the PSG layer in the first doped area on the back of the silicon wafer was 107.64nm. After texturing, the thickness of the PSG layer in the first doped area on the back of the silicon wafer was 0.2nm. The morphology of the front side of the silicon wafer is shown in Figure 1. Figure 7 , the back side of the morphology can be seen Figure 8 .
[0027] The difference between the comparative example 1 and the embodiments 1 and 2 is that the texturing additive in the comparative example 1 is different, and the rest is the same.
[0028] Note: The silicon wafers used in the texturing process involved in the embodiments and comparative examples are all single crystal silicon wafers that have been pre-cleaned, and the length, width and thickness of the silicon wafers are the same.
[0029] Embodiment 1 Combination Figures 3 to 4 The texturing results show that: after the silicon wafer is texturized in Example 1, the thickness of the PSG layer in the first doping area on the back of the silicon wafer is 40.6 nm, and the PSG layer in the first doping area is not damaged; Figures 5 to 6 The texturing results show that after the silicon wafer is texturized in Example 2, the thickness of the PSG layer in the first doping area on the back of the silicon wafer is 38.07 nm, and the PSG layer in the first doping area is not damaged; Figures 7 to 8 It can be seen from the texturing results that after the silicon wafer in Comparative Example 1 is texturized, the thickness of the PSG layer in the first doped area on the back of the silicon wafer is only 0.2nm, the PSG layer in the first doped area is damaged, and a velvet structure appears in the first doped area, indicating that the texturing liquid made from the texturing additive of the present invention is used to texturize the silicon wafer, which can make the second doped areas on the front and back of the silicon wafer obtain a uniform velvet surface, and effectively protect the PSG layer in the first doped area on the back of the silicon wafer, thereby improving the minority carrier lifetime and opening voltage of the BC battery, which is beneficial to improving the photoelectric conversion efficiency of the battery.
[0030] The preferred embodiment of the present invention is described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the specific details in the above embodiment. Within the technical concept of the present invention, various equivalent transformations can be made to the technical scheme of the present invention, and these equivalent transformations all belong to the protection scope of the present invention.
Claims
1. A texturing additive, characterized in that: The texturing additive comprises the following components by weight: Nucleating agent 0.05-0.5wt%, nucleating reinforcing agent 0.1-3.0wt%, surfactant 0.2-4.0wt%, protective agent 0.2-3.0wt%, protective reinforcing agent 0.5-6.0wt%, and deionized water as the balance.
2. The texturing additive according to claim 1, characterized in that: The nucleating agent is at least one selected from carboxymethyl starch, hydroxypropyl starch, and sodium carboxymethyl starch.
3. The texturing additive according to claim 1, characterized in that: The nucleation enhancer is at least one selected from butynol ether propane sulfonate and butynediol sulfopropyl ether sodium salt.
4. The texturing additive according to claim 1, characterized in that: The surfactant is at least one selected from sodium dodecylbenzene sulfonate and sodium polystyrene sulfonate.
5. The texturing additive according to claim 1, characterized in that: The protective agent is at least one selected from poly-L-leucine, polyglutamic acid, polyepoxysuccinic acid, polyaspartic acid, and polylysine.
6. The texturing additive according to claim 1, characterized in that: The protection enhancer is phosphonobutanetricarboxylic acid.
7. A texturing liquid, characterized in that: The texturing liquid is prepared by adding the texturing additive described in any one of claims 1 to 6 into an alkaline solution and mixing them uniformly, wherein the mass ratio of the texturing additive to the alkaline solution is 0.5-2.0:
100.
8. The texturing liquid according to claim 7, characterized in that: The alkaline solution is selected from one of NaOH solution and KOH solution.
9. The texturing liquid according to claim 8, characterized in that: The mass concentration of NaOH is 1.5% to 4.0%, and the mass concentration of KOH is 1.5% to 4.0%.
10. A texturing method, characterized in that: The method uses the texturing liquid described in any one of claims 7 to 9 to texturize the surface of the silicon wafer, wherein the texturizing step is: immersing the cleaned silicon wafer in the texturizing liquid and performing surface texturing at 65 to 75° C. for 300 to 500 seconds.