HF treatment to enhance front-surface passivation and firing stability of silicon large-area back-contact solar cells

IF 6.3 2区材料科学 Q2 ENERGY & FUELS

Solar Energy Materials and Solar Cells Pub Date : 2025-05-10 DOI:10.1016/j.solmat.2025.113694

Tianjie Zhang , Tao Lin , Zibo Zhou , Dawei Liu , Tai Chen , Jianan Xie , Sirui Liu , Junbao Liu , Tao Wang

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Abstract

Back-contact solar cells, free from front-surface grid lines, maximize optical absorption and are recognized for their high efficiency potential among crystalline silicon cells. While the TOPCon (tunnel oxide passivated contact) structure achieves extremely low surface recombination and has demonstrated record efficiencies exceeding 26 %, its application to the front surface of back-contact cells introduces significant optical parasitic absorption. To address these challenges and reduce recombination on front textured surfaces, the passivation characteristics of three different structures—a sole SiNx:H dielectric layer, a SiO₂/SiNx:H stack, and an n⁺-FSF/SiO₂/SiNx:H stack—were investigated and compared using industrial-scale equipment. We observed that increasing the oxidation temperature and time for thermally grown SiO₂ layers capped with SiNx:H reduced iVoc and increased J₀, enlarging the difference in these values before and after co-firing. Combined with HF thinning behavior, it was concluded that the surface oxygen exchange zone of the SiO₂ layer (thickness ∼4.7 nm) significantly impacts front-surface passivation and firing stability. HF dip treatment significantly enhanced passivation, achieving a higher iVoc (738.98 mV) and a lower J₀ (2.51 fA/cm²) with an effective surface recombination velocity (S_eff) of 0.41 cm/s at a fixed injection level of 1 × 10¹⁵ cm⁻³, comparable to the lowest values reported for TOPCon structures capped with SiNx:H on textured surfaces. These findings provide a practical solution to enhance front-surface passivation and firing stability for back-contact solar cell manufacturing.

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高频处理提高硅大面积背接触太阳能电池前表面钝化和烧成稳定性

背接触式太阳能电池不受前表面网格线的影响，最大限度地提高了光吸收，并因其在晶体硅电池中的高效率潜力而得到认可。虽然TOPCon（隧道氧化物钝化接触）结构实现了极低的表面复合，并证明了超过26%的效率，但将其应用于后接触电池的前表面会引入明显的光寄生吸收。为了解决这些问题并减少前纹理表面的复合，研究了三种不同结构（单一SiNx:H介电层、SiO2/SiNx:H堆叠和n+-FSF/SiO2/SiNx:H堆叠）的钝化特性，并在工业规模的设备上进行了比较。我们观察到，随着氧化温度和氧化时间的增加，覆盖SiNx:H的热生长SiO2层的iVoc降低，J0增加，共烧前后这些值的差异扩大。结合HF减薄行为，得出SiO2层（厚度~ 4.7 nm）的表面氧交换区显著影响前表面钝化和烧成稳定性的结论。HF浸镀处理显著增强了钝化效果，在1 × 1015 cm−3的固定注入水平下，实现了更高的iVoc （738.98 mV）和更低的J0 (2.51 fA/cm2)，有效表面复合速度（Seff）为0.41 cm/s，与在纹理表面上覆盖SiNx:H的TOPCon结构的最低值相当。这些发现为提高后接触式太阳能电池制造的前表面钝化和燃烧稳定性提供了实用的解决方案。

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来源期刊

Solar Energy Materials and Solar Cells 工程技术-材料科学：综合

CiteScore

12.60

自引率

11.60%

发文量

513

审稿时长

47 days

期刊介绍： Solar Energy Materials & Solar Cells is intended as a vehicle for the dissemination of research results on materials science and technology related to photovoltaic, photothermal and photoelectrochemical solar energy conversion. Materials science is taken in the broadest possible sense and encompasses physics, chemistry, optics, materials fabrication and analysis for all types of materials.