242 / 2023-04-19 09:26:37

Synthesis of Edge-shared Octahedral MAPbBr3 via Pressure- and Temperature-induced Multiple-stage Processes

halide perovskites,amorphization,high temperature and high pressure,phase transition

高压物理与材料科学 > 功能材料-海报

Organic-inorganic halide perovskites possess flexible structures with tunable optical properties at high pressure, but the pressure-induced amorphization limits the understanding and exploration of the structure-property relationships. Herein, we report an edge-shared octahedral MAPbBr₃ via multiple-stage transformation of the traditional corner-shared 3D perovskite at high-pressure and high-temperature (P-T) conditions. In situ synchrotron X-ray diffraction reveals that upon heating at 8.7 GPa, the amorphized MAPbBr₃ transforms to a high P-T structure above 654 K via multiple-stage crystallization. The high P-T phase is determined to be a monoclinic P2/m structure with layered edge-shared Pb-Br octahedra, which can be quenched to RT at high pressure, but converts back to the initial cubic perovskite structure below 0.7 GPa under decompression. The Raman and optical measurements demonstrate that the high P-T phase has similar vibrational behavior and tunable optical properties to those of the pressure-induced amorphous phase, indicating the similarity in the local structure with the edge-shared PbBr₆ octahedral frame and the MA organic cations between the high P-T phase and the amorphous state. The present results demonstrate the structural diversity and interconversion in MAPbBr₃ by overcoming the large kinetic barrier derived from the anisotropic organic cations and disordering arrangement of the Pb-Br octahedra, providing new insight into the understanding of structural transitions and amorphization of halide perovskites.