Local Structure & Dynamics of the Organic Cation in Photovoltaic Hybrid Perovskites under Pressure

Methylammonium lead iodide (MAPI) is one the most promising materials for photovoltaics. Notwithstanding the above, access to the its phase diagram and the underlying structural and dynamical properties has not been a trivial task. Building upon our recent study on TOSCA at ambient pressure [J Phys Chem Lett 7 (2016) 4701], this proposal seeks to extend this work along the pressure axis using the upgraded TOSCA, in order to probe the local structure and underlying motions of the organic cation. Given the soft nature of the material, phase transitions occur at relatively low pressures ca. 0.3-0.4 GPa, yet their precise nature remains a matter of debate. In combination with computational modelling, a detailed study over this pressure range and across the phase transition associated with cation ordering at low temperatures would pave the way for a detailed atomistic model of the material.

甲胺铅碘（Methylammonium lead iodide, MAPI）是最具应用前景的光伏材料之一。尽管如此，获取该材料的相图及其内在结构与动力学特性却绝非易事。本提案基于我们近期在常压下针对TOSCA开展的研究[J Phys Chem Lett 7 (2016) 4701]，计划借助升级后的TOSCA沿压力维度拓展此前的工作，以探究该有机阳离子的局域结构与本征运动模式。鉴于该材料的柔软特性，其相变多发生于约0.3-0.4 GPa的较低压力区间，但其精确本质仍存在争议。结合计算建模手段，对该压力区间及低温下与阳离子有序化相关的相变展开详尽研究，将为构建该材料的精细原子级模型奠定基础。