  Metal halide perovskites (MHPs) are low-temperature processable hybrid
semiconductor materials with exceptional performances that are revolutionizing
the field of optoelectronic devices. Despite their great potential, commercial
deployment is hindered by MHPs lack of stability and durability, mainly
attributed to ions migration and chemical interactions with the device
electrodes. To address these issues, 2D layered MHPs have been investigated as
possible device interlayers or active material substitutes to reduce ion
migration and improve stability. Here we consider the 2D perovskite PEA2PbBr4
that was recently discussed as very promising candidate for X-ray direct
detection. While the increased resilience of PEA2PbBr4 detectors have already
been reported, the physical mechanisms responsible for such improvement
compared to the standard "3D" perovskites are not still fully understood. To
unravel the charge transport process in PEA2PbBr4 crystals thought to underly
the device better performance, we adapted an investigation technique previously
used on highly resistive inorganic semiconductors, called photo induced current
transient spectroscopy (PICTS). We demonstrate that PICTS can detect three
distinct trap states (T1, T2, and T3) with different activation energies, and
that the trap states evolution upon X-ray exposure can explain PEA2PbBr4
superior radiation tolerance and reduced aging effects. Overall, our results
provide essential insights into the stability and electrical characteristics of
2D perovskites and their potential application as reliable and direct X-ray
detectors.
