Molecular ferroelectric contributions to anomalous hysteresis in hybrid perovskite solar cells

TL;DR

This paper models the molecular orientation disorder in hybrid perovskite CH3NH3PbI3, linking ferroelectric domain structures to hysteresis in solar cell current-voltage behavior, with implications for device performance.

Contribution

It introduces a classical Hamiltonian model informed by ab-initio dynamics to describe molecular dipole domains and their effects on ferroelectric properties in perovskites.

Findings

Rich twinned domain structures vary with temperature and electric field.

Internal fields from polar domains may cause hysteresis in solar cell response.

Variations in electron-hole recombination linked to domain configurations.

Abstract

We report a model describing the molecular orientation disorder in CH3NH3PbI3, solving a classical Hamiltonian parametrised with electronic structure calculations, with the nature of the motions informed by ab-initio molecular dynamics. We investigate the temperature and static electric field dependence of the equilibrium ferroelectric (molecular) domain structure and resulting polarisability. A rich domain structure of twinned molecular dipoles is observed, strongly varying as a function of temperature and applied electric field. We propose that the internal electrical fields associated with microscopic polarisation domains contribute to hysteretic anomalies in the current--voltage response of hybrid organic-inorganic perovskite solar cells due to variations in electron-hole recombination in the bulk.