Carbon Dots For Energy Conversion Applications

Quantum dots (QDs), generally referring to semiconductor nanocrystals that display the quantum confinement effect, have been widely pursued for many energy conversion applications. More recently, carbon dots (CDots), which are small carbon nanoparticles with various surface passivation schemes, have been found to possess optical properties and photoinduced redox characteristics resembling those of conventional semiconductor QDs and thus are amenable to some of the same uses in energy conversions. Among the various carbon nanomaterials, fullerenes have been extensively investigated for their use as critical components in optoelectronic devices and systems. Carbon nanoparticles, representing a largely ignored nanoscale carbon allotrope, are in fact more effective in some of the same functions, which are materialized and much enhanced upon the surface passivation of the nanoparticles in CDots. In this perspective article on CDots for energy conversion applications, the optical properties and redox characteristics of CDots, including the related mechanistic framework and its relationship to the use of CDots as potent photocatalysts for the conversion of CO2 into small organic molecules, are highlighted. Also highlighted are results from representative studies using CDots in light-emitting diodes and various solar cells to demonstrate their excellent potential for a wide range of roles in optoelectronic devices and systems. Issues and opportunities in the further development of the CDots platform and related technologies are discussed.