Photonics Breakthroughs 2024: Advances in Heavy-Metal-Free Quantum Dot Shortwave Infrared Photodetectors and Image Sensors: The Case of Ag2Te QDs

Shortwave infrared (SWIR) light holds promising applications spanning consumer electronics, industrial automation, and biomedical imaging. The detection of shortwave infrared light lays in the centre of SWIR applications. Conventional SWIR
detectors rely on epitaxial semiconductors, which are costly and limited by low manufacturing throughput. Colloidal quantum dots (CQDs) have been developed to unravel these issues and comparable device performances have been achieved after decades’ efforts. While CQDs can offer low-cost alternatives once highvolume maturity level is reached, their widespread adoption in consumer electronics market has been hindered also by concerns on the use of lead/mercury-based materials. Recent advances in heavy-metal-free CQDs, such as silver chalcogenides (Ag2Te) and III-V semiconductors (InAs, InSb), have demonstrated performance metrics, which, in some cases, rival heavy-metal based counterparts. Progress in synthesis, surface passivation, and device engineering have enabled high detectivity (>10¹² Jones), broad spectral tunability (1000–2000 nm), monolithic integration with silicon readout circuits and proof of concept demonstration in image sensor and LIDAR use cases. These breakthroughs position heavy-metal-free CQDs as an environmentally compliant, scalable
solution for next-generation SWIR technologies.