Silver chalcogenide colloidal quantum dots for NIR-to-MWIR photodetection

Infrared (IR) photodetectors are key components in modern optoelectronics, empowering applications across telecommunications, medical imaging, environmental monitoring, defense, and consumer electronics. Colloidal quantum dots (CQDs) have become promising semiconductors in response to growing demand for straightforward, affordable, high-performance, and environment-friendly infrared photo-sensing technologies. The growing attention in CQD-based IR photodetectors is because of their solution processability, spectral tunability, and compatibility with silicon-based platforms. Conventional-CQDs based on Pb, Hg, and Cd exhibit excellent performance, but pose usage/disposal challenges in everyday life as well as serious environmental and health risks. At this critical juncture, binary (Ag₂X; X = S, Se, Te) and ternary (AgBiX₂) silver chalcogenide CQDs have gained attention as RoHS-compliant substitutes. For near-to-mid IR detection, silver chalcogenide CQDs offer tunable bandgaps with strong absorption coefficients and favorable optoelectronic characteristics. Review highlights advance in Ag₂X and AgMX₂ CQDs IR photodetectors, examining their integration into photodetectors device-architecture based on their optoelectronic properties. Role of controlled stoichiometry, surface passivation, and interface-engineering in enhancing photodetector performance is emphasized. With global market for CQDs IR photodetectors projected to achieve milestones, this work presents thorough overview of CQD IR photodetectors, encompassing recent advancements, prevailing challenges, and prospective directions for future development.