Intercalation Electrode and Grain Reconstruction Induce Significant Sensitivity Enhancement for Perovskite X-ray Detectors.

Organic-inorganic hybrid perovskites have been recognized as potential candidates in direct X-ray detectors and have triggered tremendous interest in the past years. The blade coating method meets the requirements of large area and low cost for perovskite X-ray detectors, while the low compactness resulting from solvent evaporation limits the charge collection efficiency (CCE) and device sensitivity. Most of the reports are focused on the melioration of perovskite films to increase device sensitivity; there are still problems of low CCE. Herein, we introduce an intercalation-electrode device structure and achieve a ∼20-fold sensitivity enhancement. Carrier distribution throughout the thick films is simulated, and the electrode intercalating site can be optimized according to the mobility-lifetime factor to achieve the highest CCE. A methylamine thiocyanate (MASCN) additive-assisted coating strategy is developed, and pinhole free thick films with regrown particles are obtained without frequently used hot/soft pressing. A sensitivity level of ∼10 μC Gy cm as well as a detection limit of 77 nGy s is achieved under low bias, which is among the best performance for polycrystalline perovskite direct X-ray detectors. This work provides a universal device structure design to overcome carrier loss through a long transport distance and enhances the CCE for ultrahigh sensitivity.