Ag₂Te Quantum Dots: Emerging Heavy Metal-Free Chalcogenides for Near and Shortwave Infrared Photodetectors

With the rapid proliferation of the Internet of Things (IoT), wearable electronics, and machine vision technologies, the escalating demand for miniaturized, energy-efficient, and cost-effective solutions has imposed stringent constraints on the size, weight, power consumption, and cost (SWaP-C) of infrared (IR) detectors. In this context, silver telluride (Ag2Te) quantum dots (QDs) have emerged as promising alternatives to conventional heavy-metal- and rare-element-based QDs, owing to their lower toxicity, economic viability, and highly tunable optoelectronic characteristics. Recent progress in colloidal synthesis has enabled precise control over composition, morphology, and surface chemistry, facilitating synthesis protocols and efficient ligand passivation strategies. These advances have extended the absorption range of Ag2Te QDs from the near-infrared (NIR) to the short-wave infrared (SWIR) regime, with competitive performance metrics such as responsivity and detectivity comparable to those of state-of-the-art lead- and mercury-based systems. This review provides a comprehensive overview from fundamentals to recent developments in Ag2Te QDs, with emphasis on crystal structure, synthesis techniques, ligand and surface engineering, and device integration. Additionally, it outlines current limitations and future research directions, offering insights into the potential of Ag2Te QDs for scalable, low-toxicity, and high-performance infrared optoelectronics.