Direct Observation of Reversible Transformation of CH3NH3PbI3 and NH4PbI3 Induced by Polar Gaseous Molecules

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• 作者：Weixin Huang ; Joseph S. Manser ; Subha Sadhu ; Prashant V. KamatSylwia Ptasinska
• 刊名：The Journal of Physical Chemistry Letters
• 出版年：2016
• 出版时间：December 15, 2016
• 年：2016
• 卷：7
• 期：24
• 页码：5068-5073
• 全文大小：477K
• ISSN：1948-7185

文摘

Despite its competitive photovoltaic efficiency, the structural transformations of the prototypical hybrid perovskite, methylammonium lead iodide, are facilitated by interactions with polar molecules. Changes in optical and electronic properties upon exposure to ammonia potentially can enable the use of hybrid perovskites in gas-sensing applications. We investigated the effects of ammonia on CH₃NH₃PbI₃ by exposing perovskite films to a wide range of vapor pressures. Spectroscopic analyses indicated that ammonium cations replaced the methylammonium cations in the perovskite crystal, thereby resulting in the formation of NH₄PbI₃. The transformation of CH₃NH₃PbI₃ to NH₄PbI₃ caused distinct changes in the morphology of the film and its crystalline structure; however, the introduction of CH₃NH₂ gas reversed these changes. An in-depth understanding of the reversible chemical and structural alterations resulting from exposure to polar molecules can advance the development of hybrid perovskite sensors and provide insight into mechanisms by which perovskites convert due to interactions with polar molecules.