Environmentally benign nanocrystals: challenges and future directions

Colloidal semiconductor nanocrystals, referred to as quantum dots (QDs), have unique and superb photophysical properties, promising a variety of applications ranging from optoelectronics and energy harvesting to agriculture. The last decade witnessed a tremendous advance in QDs and their successful debut in displays, and now, QDs are equipped with environmental benignity to expand their territory to everyday life. From this perspective, the current research status and future perspective of environmentally benign QDs as building blocks for light-generating and light-harvesting applications are provided. Also provided is an overview of the progress made in the chemistry (colloidal synthesis, surface chemistry, and heterostructuring) and in their photophysical and electrical properties from the viewpoint of their use in light-emitting or light-harvesting applications. Grounded on the current status of heavy-metal-free QDs compared with cutting-edge technologies, the perspective of environmentally benign QDs for practical use and future research directions is discussed.