Shortwave Infrared Light Detection and Ranging Using Silver Telluride Quantum Dots.

Shortwave infrared (SWIR) light, characterized as the "eye-safe" window, is considered extremely promising in various technological fields and particularly valuable for imaging and light detection and ranging (LiDAR) applications. Silver telluride (AgTe) colloidal quantum dots (CQDs), featuring RoHS-compliance, solution-processability, and CMOS compatibility, emerge as a potential contender for SWIR optoelectronics. Yet, further improvements in dark current, response speed, and linear dynamic range (LDR) are essential for meeting the rigorous demands of sensing and LiDAR applications. Here, it is shown that post-synthesis surface engineering and doping control significantly improve the dark current, response speed, and LDR of Ag₂Te CQD photodiodes, achieving a low dark current of 450 nA cm at -0.5 V, an LDR exceeding 150 dB, and a rapid response speed of ≈25 ns. A proof-of-concept LiDAR demonstration in the SWIR using a practical nanosecond diode laser achieves decimetre-level resolution at a distance exceeding 10 m. This work represents a key step in advancing SWIR CQDs toward consumer electronics and automotive markets.