Highly photosensitive vertical photodetectors based on CsPbBr3 and PbS quantum dot layered heterojunction

Abstract

To overcome existing limitations in sensitivity and cost of state-of-the-art systems, new-style device structures and composite material systems are needed with low-cost fabrication and high performance. Vertical field effect photodetectors are fabricated with Au/Ag nanowires as the transparent source electrode and with vertically stacked layers of CsPbBr3 and lead sulfide quantum dots, which formed heterojunctions. The built-in electric field in the layered heterojunction aids the separation of photoinduced excitons, while the short channel enables efficient carrier transport across the active region. Both of these benefits enable a high photo performance and fast photoresponse. This vertical phototransistors exhibit a wide response spectrum from 400 to 2100 nm, a high photoresponsivity of more than 9 × 108 AW−1, and a high detectivity of up to 2 × 1017 Jones (cm Hz1/2 W−1) under infrared illumination. Additionally, this vertical phototransistor had a response time of 3 μs. The solution –based fabrication process and excellent device performances strongly underscore vertical architecture combined with the layered heterojunction as a promising approach for future photodetection field.