High-pressure study of hybrid organic-inorganic perovskites and double perovskites

Abstract

Hybrid and double perovskite have been of great attraction for optoelectronic devices. However, exploring a feasible method to enhance their optical abilities remains a considerable challenge. Here, the researcher reports the pressure-induced phase transition as an effective way to modify optoelectronic properties. The researcher successfully synthesized the hybrid perovskite (MAPbI3) and the double perovskite (Cs2TiBr6) by the inverse temperature crystallization (ITC) and solution method, respectively. the researcher studied the pressure dependence phase transition and photoluminescence (PL) by placing the sample into diamond anvil cells (DACs) through Raman spectroscopy. The first principles method was used to support the idea. The researcher observed at least 3 phase transition of MAPbI3 under hydrostatic compression up to 5.34 GPa. The transformation from dynamic to static phases occurs at 3.26 GPa. The static phase shows the disappearance of organic CH3NH3 vibration. The researcher also observed the structural deformation of Cs2TiBr6 by a similar method. However, Cs2TiBr6 exhibit a distinct phase transition under high pressure of 11.9 GPa. New Raman peaks of octahedral TiBr6 indicate high interaction and indicate the evolution from alpha phase to beta phase. Subsequently, the emission undergoes a red shift and a significant broadening under further pressure up to 12.6 GPa.