Atomic-scale insights into the ion-diffusion induced degradation for silicon heterojunction solar cells

俞健^1*, 白宇¹, 罗红¹, 张一民², 刘文柱³, 孟胜⁴

¹ 西南石油大学新能源与材料学院

² 郑州大学物理学院/教育部材料物理重点实验室

³ 中国科学院上海微系统与信息技术研究所

⁴ 中国科学院物理研究所

^*E-mail: jianyu@swpu.edu.cn

Abstract

Metal-based halogen compounds, represented by MgF₂, are widely used in many advanced photovoltaic technologies, not only playing a key role in passivating contacts, but also acting as an excellent anti-reflective layer. However, we found the MgF₂ layer for silicon solar cells was a double-edged sword during the damp-heat (DH) stability test, resulting in a sharp reduction in E_ff of 53.5 rel.% after only 200 h. The interaction between MgF₂ in ionic form and water leads to corrosion of the Si surface, resulting in lattice defects in the c-Si and severely deteriorated a-Si:H/c-Si(n) interface. We employ SiO₂ thin films, which efficiently suppress degradation, ensuring long-term stable operation of solar cells in DH environments.