Trapped‐Electron‐Induced Hole Injection in Perovskite Photodetector with Controllable Gain

Abstract

AbstractPerovskite is an excellent photosensitive material but it exhibits a shortcoming in providing photoconductive gain for layered photodetectors due to lacking of trap states. Here, the perovskite photodetectors are fabricated with controllable photoconductive gain by designing a trapped‐electron‐induced hole injection structure of [6,6]‐phenyl‐C61‐butyric acid methyl ester (PCBM):2,3,5,6‐tetrafluoro‐7,7,8,8‐tetracyanoquinodimethane (F4‐TCNQ)/Bathocuproine/Au. The deep trap states provided by F4‐TCNQ can capture the photogenerated electrons from perovskite, which makes the hole injection barrier thin enough to be tunneled through, allowing the hole injection and forming a gain. Meanwhile, the gain is controllable by adjusting the electron trapping and hole transport capacities of PCBM:F4‐TCNQ dual‐functional layer, concomitantly realizing the transition of device from photovoltaic to photoconductive. Thus fabricated device achieves a higher external quantum efficiency of 6 × 104% at a lower bias of −1 V, and simultaneously maintains the rectifying behavior in dark, providing the detectivity of about 1 × 1015 Jones.