Device Postannealing Enabling over 12% Efficient Solution‐Processed Cu2ZnSnS4 Solar Cells with Cd2+ Substitution. Issue 32 (1st July 2020)

• Record Type: Journal Article
• Authors: Su, Zhenghua; Liang, Guangxing; Fan, Ping; Luo, Jingting; Zheng, Zhuanghao; Xie, Zhigao; Wang, Wei; Chen, Shuo; Hu, Juguang; Wei, Yadong; Yan, Chang; Huang, Jialiang; Hao, Xiaojing; Liu, Fangyang
• Is Part Of: Advanced materials. Volume 32:Issue 32(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-07-01
• Subjects: Cu2ZnSnS4 -- indium tin oxide -- kesterite -- postannealing; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adma.202000121
• Languages: English
• ISSNs: 0935-9648

Abstract

Abstract: Kesterite Cu2 ZnSnS4 is a promising photovoltaic material containing low‐cost, earth‐abundant, and stable semiconductor elements. However, the highest power conversion efficiency of thin‐film solar cells based on Cu2 ZnSnS4 is only about 11% due to low open‐circuit voltage and fill factor mainly caused by antisite defects and unfavorable heterojunction interface. In this work, a postannealing procedure is proposed to complete a Cd‐alloyed Cu2 ZnSnS4 device. The postannealing to complete the device significantly enhances the performance of the indium tin oxide and promotes the moderate interdiffusion of elements between the layers in the device. As a result of the diffusion of Cu, Zn, In, and Sn, the interfacial electron and hole densities are improved, leading to the achievement of a suitable band alignment for carrier transport. The postannealing also reduces the interface traps and deep‐level defects, contributing to decreased nonradiative recombination. Therefore, the open‐circuit voltage and fill factor are both improved, and an efficiency over 12% for pure sulfide‐based kesterite thin‐film solar cells is obtained. Abstract : A method of device annealing including an indium tin oxide (ITO) layer is proposed, acheiving an efficiency of 12.6% for Cd‐alloyed Cu2 ZnSnS4 thin‐film solar cells. The V OC is increased by the reduction of both interface traps and deep‐level defects, and fill factor enhancement is based on the favorable band alignment (conduction band offset) and ITO improvement after postannealing.