Recent advances in synthetic methods and applications of colloidal silver chalcogenide quantum dots

Narrow bandgap colloidal semiconductor nanocrystals have attracted increasing attention in recent years and studies have demonstrated their significant applications in optics, electronics, biomedicine, materials science, and other areas. During the past decade, many studies have investigated colloidal silver chalcogenide (Ag2X, X=S, Se, Te) quantum dots (QDs) due to their numerous advantages, such as near-infrared (NIR) emission, ultralow toxicity, high photo-/colloidal stability, low cost, and facile synthesis. Compared with conventional NIR QDs (which contain heavy metal elements such as Cd, Hg, or Pb), NIR emissive Ag2X QDs avoid the intrinsic hazard of heavy metal ions and they have ultralow toxicity in biomedical applications. However, no previous review has summarized the synthetic methods and applications of Ag2X QDs in a systematic manner. In this review, we discuss previously reported synthetic methods and the advantages of directly synthesized and surface functionalized Ag2X QDs, as well as reporting their potential applications in bioimaging, chemo-/bio-detection, QD-sensitized solar cells, and photocatalysis, as well as antimicrobials and thermoelectric materials. Recent methods for synthesizing Ag2X QDs are discussed in detail. The unique optoelectronic properties of Ag2X QDs and their assemblies make these QDs excellent materials for a broad range of applications, and thus their assemblies and properties are highlighted. Finally, we suggest the future exploration of highly efficient synthetic methods and the potential application fields of Ag2X QDs. (C) 2015 Elsevier B.V. All rights reserved.