Ultrasensitive Hybrid MoS₂-ZnCdSe Quantum Dot Photodetectors with High Gain

Recently, two-dimensional (2D) materials, especially transition-metal dichalcogenides (TMDCs), have attracted extensive interest owing to their potential applications in optoelectronics. Here, we demonstrate a hybrid 2D-zero-dimensional (0D) photodetector, which consists of a single-layer or few-layer molybdenum disulfide (MoS₂) thin film and a thin layer of core/shell zinc cadmium selenide/zinc sulfide (ZnCdSe/ZnS) colloidal quantum dots (QDs). It is worth mentioning that the photoresponsivity of the hybrid 2D-0D photodetector is 3 orders of magnitude larger than the TMDC photodetector (from 10 to 10⁴ A W^-1). The detectivity of the hybrid structure detector is up to 10¹² Jones, and the gain is up to 10⁵. Due to an effective energy transfer from the photoexcited QD sensitizing layer to MoS₂ films, light absorption is enhanced and more excitons are generated. Thus, this hybrid 2D-0D photodetector takes advantage of high charge mobility in the MoS₂ layer and efficient photon absorption/exciton generation in the QDs, which suggests their promising applications in the development of TMDC-based optoelectronic devices.