A high-efficiency (12.5%) kesterite solar cell realized by crystallization growth kinetics control over aqueous solution based Cu2ZnSn(S,Se)4

Abstract

Crystallization growth plays a crucial role in influencing the film quality and final photoelectric conversion performance of a kesterite Cu₂ZnSn(S,Se)₄ (CZTSSe) solar cell. Herein, an exploration of a two-step selenization strategy to control the growth kinetics of an aqueous solution derived CZTSSe film for high solar cell efficiency is reported. By synergistically exploiting the benefits of high and low temperature selenization in facilitating the CZTSSe phase formation, introducing beneficial point defect states, configuring the interfacial energy band structure, and sustaining excellent surface microstructure, a total-area cell efficiency of 12.5% has been achieved. These results demonstrate the significance of controlling the crystallization growth of CZTSSe to improve the device performance. The high cell performance achieved here is comparable to that of hydrazine or dimethyl sulfoxide solution-based cells and thus would help facilitate the development of CZTSSe solar cells toward more diversified film fabrication technologies.