Regulation of hydrothermal reaction kinetics with sodium sulfide for certified 10.7% efficiency Sb2(S,Se)3 solar cells
Chen Qian, Kaiwen Sun, Jialiang Huang, Junjie Yang, Jialin Cong, Mingrui He, Zhen Li, ZC Feng, Xu Liu, Rongfeng Tang, Martin Green, Tao Chen, Xiaojing Hao
Abstract
Abstract Antimony chalcogenide (Sb 2 (S,Se) 3 ) is a promising candidate for next-generation photovoltaic materials due to its optoelectronic properties, high absorption coefficient and material availability. Hydrothermal deposition has advanced the technology, but there is a limited understanding of the underlying reaction mechanisms, often resulting in non-ideal valence band maximum gradient across the absorber thickness and high concentration of deep-level defects. Here we introduce sodium sulfide as an additive in the precursor solution to control reaction kinetics. This strategy enables a more uniform depth-dependent elemental distribution, flattens the unfavourable valence band maximum gradient across the depth and suppresses the formation of deep-level defects. We demonstrate an improvement in Sb 2 (S,Se) 3 material quality, achieving a power conversion efficiency of 11.02%, with a certified value of 10.7 ± 0.37%. This work advances the efficiency for Sb 2 (S,Se) 3 solar cells and provides insights to optimize the hydrothermal synthesis for this technology.