Additive-Modulated Evolution of HC(NH2)2PbI3 Black Polymorph for Mesoscopic Perovskite Solar Cells

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• 作者：Zaiwei Wang ; Yuanyuan Zhou ; Shuping Pang ; Zewen Xiao ; Jiliang Zhang ; Wenqiang Chai ; Hongxia Xu ; Zhihong Liu ; Nitin P. Padture ; Guanglei Cui
• 刊名：Chemistry of Materials
• 出版年：2015
• 出版时间：October 27, 2015
• 年：2015
• 卷：27
• 期：20
• 页码：7149-7155
• 全文大小：434K
• ISSN：1520-5002

文摘

Formamidinium lead triiodide (HC(NH₂)₂PbI₃ or FAPbI₃) is gaining increasing interest in the field of mesoscopic perovskite solar cells (PSCs) for its broader light absorption compared with the more widely studied CH₃NH₃PbI₃ (MAPbI₃). Because FAPbI₃ has two polymorphs (鈥渂lack鈥?伪-FAPbI₃ and 鈥測ellow鈥?未-FAPbI₃) at ambient temperature, where 伪-FAPbI₃ is the desirable photoactive perovskite phase, it becomes particularly important to suppress the formation of the nonperovskite 未-FAPbI₃ for achieving high efficiency in FAPbI₃-based mesoscopic PSCs. In this study, we demonstrate that the judicious use of low-volatility additives in the precursor solution assists in the evolution of 伪-FAPbI₃ through the formation of non-未-FAPbI₃ intermediate phases, which then convert to 伪-FAPbI₃ during thermal annealing. The underlying mechanism involved in the additive-modulated evolution of 伪-FAPbI₃ upon mesoporous TiO₂ substrates is elucidated, which suggests guidelines for developing protocols for the fabrication efficient FAPbI₃-based mesoscopic PSCs.