  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.
