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).