Ferroelectric domains in methylammonium lead iodide perovskite thin-films

TL;DR

This study investigates the ferroelectric properties of methylammonium lead iodide perovskite thin films using Piezoresponse Force Microscopy, revealing nanoscale ferroelectric domains and their influence on charge extraction.

Contribution

First direct imaging and characterization of ferroelectric domains in methylammonium lead iodide perovskite thin films using PFM techniques.

Findings

Identified 90 nm wide ferroelectric domains in the material.

Observed alternating charge carrier extraction patterns related to domain polarization.

Confirmed piezoelectric nature of the ferroelectric domains.

Abstract

We explore the ferroic properties of methylammonium lead iodide perovskite solar cells by Piezoresponse Force Microscopy (PFM). In vertical and horizontal PFM imaging, we find domains of alternating polarization with a width of 90 nm which we identify as polarized ferroelectric domains. High-resolution photo-conductive atomic force micrographs under illumination also show alternating charge carrier extraction patterns which we attribute to the local vertical polarization components within the ferroelectric domains. The correlation of the sample properties with Atomic Force and Kelvin Probe Force Micrographs evidence the piezo-electric nature of the domains.