Hybrid quantum dot-tin disulfide field-effect transistors with improved photocurrent and spectral responsivity

We report an improved photosensitivity in few-layer tin disulfide (SnS₂) field-effect transistors (FETs) following doping with CdSe/ZnS core/shell quantum dots (QDs). The hybrid QD-SnS₂ FET devices achieve more than 500% increase in the photocurrent response compared with the starting SnS₂-only FET device and a spectral responsivity reaching over 650 A/W at 400 nm wavelength. The negligible electrical conductance in a control QD-only FET device suggests that the energy transfer between QDs and SnS₂ is the main mechanism responsible for the sensitization effect, which is consistent with the strong spectral overlap between QD photoluminescence and SnS₂ optical absorption as well as the large nominal donor-acceptor interspacing between QD core and SnS₂. We also find enhanced charge carrier mobility in hybrid QD-SnS₂ FETs which we attribute to a reduced contact Schottky barrier width due to an elevated background charge carrier density.