Heavy metal-free colloidal quantum dots: preparation and application in infrared photodetectors

The development of infrared photodetectors is increasingly moving towards the realization of large-scale, cost-effective integrated systems. Currently, silicon (Si), indium gallium arsenide (InGaAs), and mercury cadmium telluride (HgCdTe) dominate infrared photodetectors, but due to the ever-increasing performance requirements and the complexity of emerging application scenarios, a new generation of detector technologies is imperative. Colloidal quantum dots (CQDs), which are compatible with existing silicon-based microelectronics, with low manufacturing costs and simplified processing, are ideal alternatives. Hg- or Pb-based infrared photodetectors have been widely studied owing to their excellent performance. Nevertheless, the presence of heavy metal elements greatly limits the application scenarios of the detectors. Therefore, heavy metal-free (HMF) CQD-based infrared photodetectors solve the above problem from the source. In this work, the latest advancements in the synthesis of HMF CQDs and a brief overview of the development of HMF CQD-based infrared photodetectors are given. Within the context of this field, we summarize the possible forward-looking directions and obstacles.