Deciphering the degradation mechanism of the lead-free all inorganic perovskite Cs2SnI6

Journal Article · 14 February 2019 · npj Materials Degradation

DOI: https://doi.org/10.1038/s41529-019-0068-3 · OSTI ID:1619701

Zhu, Weiguang; Xin, Guoqing; Scott, Spencer M.; Xu, Wenqian; Yao, Tiankai; Gong, Bowen; Wang, Yachun; Li, Mingxin; Lian, Jie

Abstract Organic-inorganic perovskite materials are revolutionizing photovoltaics with high power conversion efficiencies, but experience significant environmental degradation and instability. In this work, the phase stability and decomposition mechanisms of lead-free all inorganic Cs ₂ SnI ₆ perovskite upon water and moisture exposure were systematically investigated via in situ synchrotron X-ray diffraction, environmental SEM, and micro-Raman spectroscopy. A critical relative humidity (80%) is identified below which Cs ₂ SnI ₆ perovskite is stable without decomposition. Under higher humidity or aqueous environment, Cs ₂ SnI ₆ perovskite decomposes into SnI ₄ and CsI through etch pits formation and stepwave propagation, leading to rapid crystal dissolution. A partial reversibility of the Cs ₂ SnI ₆ perovskite upon dissolution and re-precipitation with subsequent dehydration was identified, suggesting a self-healing capability of Cs ₂ SnI ₆ and thus enhanced air stability. Mechanistic understanding of the Cs ₂ SnI ₆ degradation behavior can be a vital step towards developing new perovskites with enhanced environmental stability and materials performance.

• Sponsoring Organization: USDOE
• Grant/Contract Number: NONE; SC0016584; AC02-06CH11357
• OSTI ID: 1619701
• Journal Information: npj Materials Degradation, Journal Name: npj Materials Degradation Journal Issue: 1 Vol. 3; ISSN 2397-2106
• Publisher: Nature Publishing GroupCopyright Statement
• Country of Publication: United Kingdom
• Language: English