Mapping fast evolution of transient surface photovoltage dynamics using G-Mode Kelvin probe force microscopy

TL;DR

This paper introduces a G-Mode Kelvin probe force microscopy technique to map rapid surface photovoltage dynamics in hybrid perovskite films, revealing how structural inhomogeneities influence optoelectronic behavior at microsecond and nanoscale levels.

Contribution

The authors develop a novel time-resolved KPFM method with high temporal and spatial resolution, enabling detailed mapping of SPV dynamics in complex materials.

Findings

Concurrent spatial and ultra-fast temporal SPV variations observed.

Structural inhomogeneities linked to heterogenous SPV behavior.

Unsupervised clustering effectively analyzes complex SPV datasets.

Abstract

Optoelectronic phenomena in materials such as organic/inorganic hybrid perovskites depend on a complex interplay between light induced carrier generation and fast (electronic) and slower (ionic) processes, all of which are known to be strongly affected by structural inhomogeneities such as interfaces and grain boundaries. Here, we develop a time resolved Kelvin probe force microscopy (KPFM) approach, based on the G-Mode SPM platform, allowing quantification of surface photovoltage (SPV) with microsecond temporal and nanoscale spatial resolution. We demonstrate the approach on methylammonium lead bromide (MAPbBr3) thin films and further highlight the usefulness of unsupervised clustering methods to quickly discern spatial variability in the information rich SPV dataset. Using this technique, we observe concurrent spatial and ultra-fast temporal variations in the SPV generated across the thin film, indicating that structure is likely responsible for the heterogenous behavior.