Viologen Unlocks Photogenerated Carrier Confinement in Low-Dimensional Perovskites for High-Stability and High-Gain X‑ray Detection

The simultaneous attainment of high-photoelectric performance
and
stability has long been a challenge for hybrid perovskites, which
are typically characterized by the low stability of three-dimensional
perovskites and the poor photoelectric performance of low-dimensional
perovskites. Here, we present a novel perovskite assembly strategy
aimed at enhancing both the photoelectric gain and stability for X-ray
detection. This strategy employs a viologen as a cation, leveraging
its strong electrostatic interaction, low LUMO, and capability for
photogenerated charge separation and transport to enhance stability,
reduce the band gap, and unlock photogenerated carrier barriers while
integrating the benefits of low-dimensional perovskites. The obtained
zero-dimensional viologen perovskite exhibits exceptional comprehensive
performance, including high X-ray detection performance (in vacuum),
low X-ray dose rate resolution, inhibited ion migration, low dark
current drift and noise current, and remarkable chemical and long-term
stability (sustained in air with 50–75% relative humidity for
1 year, followed by 60 h of UV irradiation at 80 °C).