Controlling selenization equilibrium enables high-quality Cu2ZnSn(S, Se)4 absorbers for efficient solar cells

• Published in: arXiv.org
• Main Authors: Xu, Xiao, Zhou, Jiazheng, Kang, Yin, Wang, Jinlin, Lou, Licheng, Jiao, Menghan, Bowen, Zhang, Li, Dongmei, Shi, Jiangjian, Wu, Huijue, Luo, Yanhong, Meng, Qingbo
• Format: Paper Journal Article
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 04.03.2023
• Subjects: Absorbers; Chemical potential; Competitive materials; Energy conversion efficiency; Evolution; Optimization; Photovoltaic cells; Physics - Materials Science; Precursors; Selenium; Solar cells; Strategy; Vapor phases
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2303.02368

Cu2ZnSn(S, Se)4 (CZTSSe) is one of most competitive photovoltaic materials for its earth-abundant reserves, environmental friendliness, and high stability.The quality of CZTSSe absorber determines the power-conversion efficiency (PCE) of CZTSSe solar cells. The absorber's quality lies on post-selenization process, which is the reaction of Cu-Zn-Sn precursor and selenium vapor. And the post-selenization is dependent on various factors (e.g. temperature, precursor composition, reaction atmosphere, etc).However, synergistic regulation of these factors cannot be realized under a widely-used single-temperature zone selenization condition.Here, in our dual-temperature zone selenization scheme, a solid-liquid and solid-gas (solid precursor and liquid/gas phase Se) synergistic reaction strategy has been developed to precisely regulate the selenization. Pre-deposited excess liquid Se provides high Se chemical potential to drive a direct and fast formation of the CZTSSe phase, significantly reducing the amount of binary and ternary compounds within phase evolution. And organics removal can be accomplished via a synergistic optimization of Se condensation and subsequent volatilization. We achieve a high-performance CZTSSe solar cell with a remarkable PCE of 13.6%, and the highest large-area PCE of 12.0% (over 1cm2). Our strategy will provide a new idea for further improving efficiency of CZTSSe solar cells via phase evolution regulation, and also for other complicated multi-compound synthesis.