Understanding the enhancement of responsitivity in perovskite/organic semiconductor bilayer-structured photodetectors

Responsitivity is an important figure of merit for photodetectors. Here we demonstrated a simple yet efficient way to enhance the responsitivity of methylammonium lead iodide (MAPbI₃)-based photodetectors by utilizing organic semiconductors (OSCs) to form MAPbI₃/OSC bilayer structures. These bilayer photodetectors are fabricated with a facile and low-cost spin-coating method, yet the responsitivity can be more than one order of magnitude higher than that of pristine MAPbI₃ photodetectors. More importantly, the physics behind the enhancement of responsitivity was analyzed and revealed by inspecting the physical processes in terms of light absorption, exciton dissociation and charge transport. The results indicate that the responsitivity enhancement is mainly attributable to the more efficient exciton dissociation and hole transport processes in the bilayer photodetectors.