Suppression of phase transitions in mixed cation halide perovskites MA/EAPbI3

The main goal of this project is to determine temperature-induced deformations of the inorganic structure and phase transformations in organic-inorganic perovskites MA1-xEAxPbI3 (x from 0 up to 0.5), where MA and EA stand for small organic molecules: methylammonium and ethylammonium, respectively. Cation engineering is one of the routes to control the structure and properties of halide perovskites to enhance optoelectronic performance and stability. MAPbI3 and its modifications are extensively investigated organic-inorganic semiconductors for effective and affordable solar cells. Mixing of molecular cations brings significant changes in phase diagrams. We expect suppression of the phase transitions, enhanced disorder, and stabilization of the high symmetry phases which have the highest technological importance. The research is a part of a larger project that, by using the multi-technique approach, aims to determine (x, T) phase diagram and molecular cation dynamics of MA1-xEAxPbI3.

本项目的核心目标为探究MA₁₋ₓEAₓPbI₃型有机-无机钙钛矿（organic-inorganic perovskites）在温度诱导下的无机结构热致形变与相转变行为，其中x的取值范围为0至0.5；MA与EA分别指代两种小分子有机阳离子：甲胺基（methylammonium）与乙胺基（ethylammonium）。阳离子工程是调控卤化物钙钛矿（halide perovskites）的结构与性能、提升其光电性能与稳定性的重要途径之一。MAPbI₃及其改性体系是当前被广泛研究的有机-无机半导体材料，可用于制备高效且低成本的太阳能电池。混合分子阳离子会对相图产生显著影响。本研究预期可抑制相转变、增强体系无序度，并稳定具备最高技术价值的高对称相。本研究隶属于一项更大规模的科研项目，该项目采用多技术联用手段，旨在明确MA₁₋ₓEAₓPbI₃的(x, T)相图与分子阳离子动力学行为。