Chirality Inducing Polar Photovoltage in a 2D Lead-Free Double Perovskite toward Self-Powered X-ray Detection

Lead-free halide double perovskites (HDPs) have sparkedbroad interestin developing green photodetectors; however, self-poweredX-ray detectors in this family remain elusive. Here, by exploitingthe chirality-induced polar photovoltaic effect in a chiral-polar2D HDP, (R-MPA)(4)AgBiI8 (1, R-MPA = R-beta-methylphenethylammonium),we successfully realized self-powered X-ray detection. The significantspontaneous electric polarization in 1 gives it a largepolar photovoltage of 0.36 V, which drives the separation and transportof X-ray-generated carriers, thus acquiring the capability of self-powereddetection. Consequently, X-ray detectors based on high-quality singlecrystals of 1 exhibit a high sensitivity of 46.3 mu CGy(-1) cm(-2) and an ultralow detectionlimit of 85 nGy s(-1) at zero bias. The sensitivitycan be further increased to 949.6 mu C Gy(-1) cm(-2) at 50 V bias, outperforming all current 2D HDP detectors.Our work is the first to demonstrate self-powered X-ray detectionin single-phase lead-free HDPs, enlightening future design of greenself-powered radiation detectors.

Automated summary

In this study, self-powered X-ray detection was successfully realized in a chiral-polar 2D lead-free halide double perovskite material, (R-MPA)(4)AgBiI8. The material displayed significant spontaneous electric polarization, resulting in a large polar photovoltage of 0.36 V, which facilitated the separation and transport of X-ray-generated carriers for self-powered detection. X-ray detectors based on high-quality single crystals of this material exhibited high sensitivity (46.3 mu CGy(-1) cm(-2)) and ultralow detection limit (85 nGy s(-1) at zero bias), outperforming current 2D lead-free halide double perovskite detectors. This work provides insights for the future design of green self-powered radiation detectors.