Giant current amplification induced by ion migration in perovskite single crystal photodetectors

Abstract

Single crystals of organic–inorganic hybrid perovskites have become attractive candidates for application in photodetection and high-energy radiation detection based on a unique solution growth method with a large interacting cross-section with electromagnetic waves in different energy regimes and high drift mobilities through optically induced polarization. However, inevitable ion migration often represents a technical difficulty in controlling the detection performance. This work reports giant current amplification induced by ion migration in the MAPbI₃ single crystal photodetectors with a lateral geometry of Au/MAPbI₃/C₆₀/BCP/Ag based on light soaking studies. Upon light soaking, a stabilized device can demonstrate a giant amplification factor reaching 600 at −2 V under weak light illumination (1 mW cm⁻²). The time-dependent current profile shows a slow response during amplification under light soaking. This indicates that optically activated ions are driven away from working areas to the respective electrodes, leading to the reduction of dark current by decreasing bulk defects. Simultaneously, the accumulation of iodine anions and methylammonium cations at Ag and Au contacts can trigger the counter charge injection, largely amplifying the total electrical current and leading to giant current amplification in perovskite single crystal photodetectors.