The Polymer Society of Korea

Abstract

Extended shortwave infrared (eSWIR) photodetectors are vital for applications such as LiDAR, night vision, and gas sensing. Colloidal quantum dots (CQDs) offer a promising platform due to their solution processability and tunable bandgaps. However, most eSWIR CQDs contain toxic elements like Hg or Pb, violating RoHS standards. They also often require cryogenic cooling and exhibit slow response. Here, we report a fast, room-temperature-operable eSWIR photodetectors using RoHS-compliant silver telluride (Ag₂Te) CQDs. The low effective mass of Ag₂Te enables rapid carrier transport, while a thiol-based ligand exchange reduces surface traps and enhances mobility. Efficient charge extraction is further achieved by integrating the CQDs into a vertically structured photodiode with optimized energy level alignment. The resulting device exhibits a fall time of 72 ns at 298 K, representing the fastest response among CQD-based eSWIR photodetectors, including those containing restricted elements.