Although metal halide perovskites have advanced rapidly in photoelectrical detection, studies on perovskite-based photon-counting detector remain scarce. This study reports an efficient perovskite photon-counting detector achieved through defects passivation of the perovskite photosensitive layer. Urea, a Lewis base, was introduced as an additive during the two-step fabrication of MAPbI 3 films, forming a complex (MAI·PbI 2 ·O=C(NH 2 ) 2 ) that slowed the reaction rate and promoted complete reaction between MAI and PbI 2 . Compared to conventional perovskite films, the optimized MAPbI 3 film exhibits enhanced crystallinity, with enlarged grain size from 254.8 to 908.1 nm, and reduced defect density from 9.08×10 15 cm 3 to 3.89×10 15 cm 3 . The resulting MAPbI 3 photodiode detector demonstrates satisfactory performance, achieving a responsivity of 0.4 A/W and a sensitivity of 2.39×10 13 Jones under 17.02 μW/cm 2 illumination. Furthermore, a photon-counting system integrated with the MAPbI 3 photodetector was able to detect low light levels down to 2.01×10 3 photons per mm 2 , with a photoresponse three times higher than that of silicon-based photon-counting detector.
Luo et al. (Sun,) studied this question.