What the Inheritance of IV–VI and II–VI Semiconductors Teaches Us for the Quest of Heavy Metal-Free Nanocrystals Dedicated to Infrared Detection

After displays, short- and mid-wave infrared (IR) sensing is seen as the next frontier for optoelectronic applications of colloidal semiconductor nanocrystals (NCs). Considerable research efforts have focused on two material platforms: lead (Pb) and mercury (Hg) chalcogenides. Although impressive progresses have brought this technology to the development of focal plane arrays, the presence of heavy metals is often recognized as a critical barrier to broader commercial adoption. This challenge has generated a push toward new synthetic pathways enabling greener IR-active NC materials. However, in practice, each material platform tends to create parallel, independent fields, thus mitigating the benefits of already established developments. In this perspective, we discuss how the Pb/Hg-based IR sensor legacy can benefit the emergence of III-V and silver chalcogenide platforms by offering genuine and critical discussions about the limitation of each kind of material. Finally, we propose some development strategies for the emergence of next generation greener NC-based IR imagers.