  Hybrid-halide perovskite (HHP) films exhibit exceptional photo-electric
properties. These materials are utilized for highly efficient solar cells and
photoconductive technologies. Both ion migration and polarization have been
proposed as the source of enhanced photoelectric activity, but the exact origin
of these advantageous device properties has remained elusive. Here, we combined
microscale and device-scale characterization to demonstrate that
polarization-assisted conductivity governs photoconductivity in thin HHP films.
Conductive atomic force microscopy under light and variable temperature
conditions showed that the photocurrent is directional and is suppressed at the
tetragonal-to-cubic transformation. It was revealed that polarization-based
conductivity is enhanced by light, whereas dark conductivity is dominated by
non-directional ion migration, as was confirmed by large-scale device
measurements. Following the non-volatile memory nature of polarization domains,
photoconductive memristive behavior was demonstrated. Understanding the origin
of photoelectric activity in HHP allows designing devices with enhanced
functionality and lays the grounds for photoelectric memristive devices.
