Ultralow dark current infrared photodetector based on SnTe quantum dots beyond 2 μm at room temperature

Quantum dots (QDs) are promising materials used for room temperature mid-infrared (MIR) photodetector due to their solution processing, compatibility with silicon and tunability of band structure. Up to now, HgTe QDs is the most widely studied material for MIR detection. However, photodetectors assembled with HgTe QDs usually work under cryogenic cooling to improve photoelectric performance, greatly limiting their application at room temperature. Here, less-toxic SnTe QDs were controllably synthesized with high crystallinity and uniformity. Through proper ligand exchange and annealing treatment, the photoconductive device assembled with SnTe QDs demonstrated ultralow dark current and broadband photo-electric response from visible light to 2 μm at room temperature. In addition, the visible and near infrared photo-electric performance of the SnTe QDs device were well maintained even standing 15 d in air. This excellent performance was due to the effective protection of the ligand on surface of the QDs and the effective transport of photo-carriers between the SnTe interparticles. It would provide a new idea for environmentally friendly mid-IR photodetectors working at room temperature.