Responsivity Surge in MAPbI₃:PC₆₁BM/Au/ZnO Sandwich‐Structured Photodetector

Abstract The low gain in the presence of a single transverse external electric field limits the application of metal‐semiconductor‐metal (MSM) photodetectors. Here, a longitudinal built‐in electric field by spin‐coating CH₃NH₃PbI₃:PC₆₁BM on the electrode region of an Au/ZnO MSM photodetector, which constitutes a vertically crossed composite electric field with a transverse external electric field, is constructed. In this case, the transverse electric field collects the electrons, and the longitudinal electric field separates them. Based on this novel electric field structure, carrier multiplication at lower voltage conditions is achieved. Compared to the low voltage, there is a significant amplification effect when the voltage reaches 7 V. The responsivity is increased ≈270 times for UV–vis wavelengths, escalating from ≈0.02 to ≈5.4 A W⁻¹. This study provides a novel carrier transport control scheme for high‐gain perovskite‐based photodetectors.