Phonon Mode Transformation Across the Orthohombic–Tetragonal Phase Transition in a Lead Iodide Perovskite CH3NH3PbI3: A Terahertz Time-Domain Spectroscopy Approach

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• 作者：Chan La-o-vorakiat ; Huanxin Xia ; Jeannette Kadro ; Teddy Salim ; Daming Zhao ; Towfiq Ahmed ; Yeng Ming Lam ; Jian-Xin Zhu ; Rudolph A. Marcus ; Maria-Elisabeth Michel-Beyerle ; Elbert E. M. Chia
• 刊名：The Journal of Physical Chemistry Letters
• 出版年：2016
• 出版时间：January 7, 2016
• 年：2016
• 卷：7
• 期：1
• 页码：1-6
• 全文大小：433K
• ISSN：1948-7185

文摘

We study the temperature-dependent phonon modes of the organometallic lead iodide perovskite CH₃NH₃PbI₃ thin film across the terahertz (0.5–3 THz) and temperature (20–300 K) ranges. These modes are related to the vibration of the Pb–I bonds. We found that two phonon modes in the tetragonal phase at room temperature split into four modes in the low-temperature orthorhombic phase. By use of the Lorentz model fitting, we analyze the critical behavior of this phase transition. The carrier mobility values calculated from the low-temperature phonon mode frequencies, via two theoretical approaches, are found to agree reasonably with the experimental value (～2000 cm² V^–1 s^–1) from a previous time-resolved THz spectroscopy work. Thus, we have established a possible link between terahertz phonon modes and the transport properties of perovskite-based solar cells.