Study on Phase Formation Mechanism of Non- and Near-Stoichiometric Cu2ZnSn(S,Se)4 Film Prepared by Selenization of Cu鈥揝n鈥揨n鈥揝 Precursors

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• 作者：Xuesong Yin ; Chunhua Tang ; Linfeng Sun ; Zexiang Shen ; Hao Gong
• 刊名：Chemistry of Materials
• 出版年：2014
• 出版时间：March 25, 2014
• 年：2014
• 卷：26
• 期：6
• 页码：2005-2014
• 全文大小：664K
• 年卷期：v.26,no.6(March 25, 2014)
• ISSN：1520-5002

文摘

The appearance of impurity phases in a Cu₂ZnSnS₄ (CZTS) layer is a big problem and challenge for high-performance CZTS photovoltaic devices. In spite of some experimental observations of secondary impurity phases, their growth mechanisms are not well established, especially in an S and Se coupled Cu₂ZnSn(S,Se)₄ (CZTSSe) system. This work carried out a systematic experimental study on the formation of secondary phases in CZTSSe, i.e., Cu_xSe and SnSe on the top surface and ZnS at the bottom. Interestingly, a clear reaction pathway for the formation of uniform CZTSSe film was revealed through a temperature dependent annealing of a near-stoichiometric sample. A further reaction thermodynamic analysis was applied to explore the fundamentals of the secondary phase formation mechanisms. Besides, a diagrammatic CZTSSe film growth model was proposed to illustrate the detailed phase development procedures during selenization of a sulfur-contained precursor. A deeper insight in the formation of CZTSSe film can not only provide a better understanding of the experimental phenomena but also guide possible improvement routes of the film formation strategy to achieve a more promising absorber of a thin film solar cell.