Optimizing the Ratio of Sn4+ and Sn2+ in Cu2ZnSn(S, Se)4 Precursor Solution via Air Environment for Highly Efficient Solar Cells. Issue 11 (15th September 2021)

• Record Type: Journal Article
• Authors: Liang, Guang-Xing; Yu, Zi-Xuan; Xie, Zhi-Gao; He, Yang; Lin, Jin-Hong; Chen, Shuo; Zheng, Zhuang-Hao; Luo, Jing-Ting; Fan, Ping; Su, Zheng-Hua; Ma, Hong-Li; Zhang, Xiang-Hua
• Is Part Of: Solar RRL. Volume 5:Issue 11(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-09-15
• Subjects: Cu2ZnSn(S, Se)4 -- deep-level defects -- interface recombination -- precursor solutions -- solar cells; Solar energy -- Periodicals; Photovoltaic power generation -- Periodicals; Solar energy -- Research -- Periodicals; Photovoltaic power generation -- Research -- Periodicals; Periodicals; 333.7923
• DOI: 10.1002/solr.202100574
• Languages: English
• ISSNs: 2367-198X

Abstract

Abstract : The use of different Sn valence states (such as Sn 4+ and Sn 2+ ) in the Cu2 ZnSn(S, Se)4 (CZTSSe) precursor solution is especially important for the quality of the subsequent growth of the CZTSSe films. The latest study has found that replacing SnCl2 ·2H2 O with anhydrous SnCl4 can remarkably improve the performance of CZTSSe solar cells, but it needs to be operated in the glovebox. Herein, for the precursor solution, SnCl4 ·5H2 O powder is used instead of anhydrous SnCl4 in air environment, and the proportion of Sn 4+ and Sn 2+ precursor solutions is further systematically studied. When the ratio of Sn 4+ to Sn 2+ is 1:1, a uniform, compact, and noncracking CZTSSe thin film is obtained, effectively alleviating the interface recombination and reducing the concentration of deep‐level defects. In particular, the concentration of CuZn antisite defects is decreased by an order of magnitude, and the carrier recombination and band tail effect are alleviated. When J SC is maintained, V OC and FF are considerably improved. Finally, CZTSSe thin‐film solar cells are fabricated with an efficiency of over 11%. Herein, the feasibility of controlling the ratio of Sn 4+ to Sn 2+ in the CZTSSe precursor solution for higher efficiency of CZTSSe thin‐film solar cells is demonstrated. Abstract : Anhydrous SnCl4 is substituted with SnCl4 ·5H2 O to prepare a Sn 4+ precursor solution in air and two solutions containing Sn 4+ and Sn 2+ are mixed as the final precursor solution, rendering a feasible scheme to obtain denser films and avoid film cracking. When the ratio of Sn 4+ to Sn 2+ is 1:1, the best efficiency of 11.1% for CZTSSe solar cells is obtained.