Viologen\nUnlocks Photogenerated Carrier Confinement\nin Low-Dimensional Perovskites for High-Stability and High-Gain X‑ray\nDetection

The simultaneous attainment of high-photoelectric performance\nand\nstability has long been a challenge for hybrid perovskites, which\nare typically characterized by the low stability of three-dimensional\nperovskites and the poor photoelectric performance of low-dimensional\nperovskites. Here, we present a novel perovskite assembly strategy\naimed at enhancing both the photoelectric gain and stability for X-ray\ndetection. This strategy employs a viologen as a cation, leveraging\nits strong electrostatic interaction, low LUMO, and capability for\nphotogenerated charge separation and transport to enhance stability,\nreduce the band gap, and unlock photogenerated carrier barriers while\nintegrating the benefits of low-dimensional perovskites. The obtained\nzero-dimensional viologen perovskite exhibits exceptional comprehensive\nperformance, including high X-ray detection performance (in vacuum),\nlow X-ray dose rate resolution, inhibited ion migration, low dark\ncurrent drift and noise current, and remarkable chemical and long-term\nstability (sustained in air with 50–75% relative humidity for\n1 year, followed by 60 h of UV irradiation at 80 °C).