Solution-Processed Solar-Blind Ultraviolet Photodetectors Based on ZnS Quantum Dots

ZnS quantum dots (QDs)-based solar-blind ultraviolet photodetectors were fabricated by a solution-based process without annealing. The cubic ZnS QDs have an average particle size of ~2.29 nm, measured by transmission electron microscopy; the bandgap was found to be 4.11 eV (~3.68 eV for bulk cubic ZnS), determined by photoluminescence excitation measurement. The photodetector shows a cutoff at 300 nm; for shorter wavelengths, the responsivity is found to increase linearly from 300 to 254 nm; a photosensitivity of 8, responsivity of 1.60 mA/W, and detectivity of 5.51×10
⁹
cm·Hz
^1/2
·W
^-1
were obtained at 254 nm, when operated at a bias voltage of 15 V.