Strain induced stabilization of high symmetry phase in MAPbBr3 perovskite

Abstract

Structural phase transitions in organic inorganic metal halide perovskites are driven via the rearrangement of methylammonium cation and distortion in the PbX6 octahedra. Suppression of the structural phase transition in these systems is known to be seen with cation or anion tuning. Along with the compositional tuning, the behavior of strain present in the system can also lead to stabilization of single phase in these systems. In the present investigation, two different samples of CH3NH3PbBr3 perovskite were studied and it is observed that structural phase transition is absent for one of the samples while it is present in the other sample. The non-observance of structural phase transition and stabilization of single phase have been attributed to the perceived tensile strain in the system, contrary to the compressive strain observed in the system showing structural phase transitions. Extended x-ray absorption fine structure measurements revealed an increase in bond lengths in the sample where structural phase transitions are suppressed, compared to the sample exhibiting such transitions. This observation is further supported by theoretical calculations. The stabilization of the cubic phase can enhance device performance and increase overall environmental stability, making these systems more effective for practical applications.