Low-Cost Solution-Processed MoS2 Quantum Dots-Based Deep UV Photodetector for Monitoring Disinfection

Deep UV radiation is commonly used as a disinfectant with an appropriate dose for better efficacy. However, continuous monitoring of UV radiation is required to have appropriate dose exposure for proper disinfection. This article reports a low-cost solution-processed fabrication method of the UV photodetector (PD) with a device geometry of Al/MoS ₂ quantum dots (QDs)/Al on Si/SiO ₂ substrate, which is sensitive to deep UV radiations ~275 nm, commonly used for water and surfaces disinfection technologies. Colloidal MoS ₂ QDs with an average size of 1.99 nm have been synthesized by an inexpensive hydrothermal method. The surface ligand of MoS ₂ QDs has been replaced by a shorter ligand 1, 2-ethanedithiol (EDT) to reduce dot-to-dot distance. The fabricated device shows high responsivity (21.62 mA/W), external quantum efficiency (EQE) (9.74%), and detectivity ( $3.57\times 10$ ¹⁰ Jones) under the deep UV irradiation of ~275 nm. The PD has a good photoresponse speed of rise and decay times of 173 and 92 ms, respectively.