Photoferroelectric and Photopiezoelectric Properties of Organometal Halide Perovskites

TL;DR

This study uses density functional theory to analyze the piezoelectric and photoferroelectric properties of organometal-halide perovskites, revealing how molecular ordering and structural transitions influence their piezoelectric response.

Contribution

It provides a detailed theoretical analysis of the factors affecting piezoelectricity in OMHPs, highlighting the roles of atomic substitution and structural transitions, which is novel in this context.

Findings

Piezoelectric coefficient depends on molecular ordering.

Light enhances piezoelectricity via structural transition.

Displacement of B-site cation dominates piezoelectric response.

Abstract

Piezoelectrics play a critical role in various applications. The permanent dipole associated with the molecular cations in organometal-halide perovskites (OMHPs) may lead to spontaneous polarization and thus piezoelectricity. Here, we explore the piezoelectric properties of OMHPs with density functional theory. We find that the piezoelectric coefficient depends sensitively on the molecular ordering, and that the experimentally observed light-enhanced piezoelectricity is due to to a non-polar to polar structural transition. By comparing OMHPs with different atomic substitutions in the $ABX_3$ architecture, we find that the displacement of the $B$-site cation contributes to nearly all the piezoelectric response, and that the competition between $A$-$X$ hydrogen bond and $B$-$X$ metal-halide bond in OMHPs controls the piezoelectric properties. These results highlight the potential of the OMHP architecture for designing new functional photoferroelectrics and photopiezoelectrics.