Carbon Dots/Graphene Hybrids for UV Photodetectors

The intrinsical poor optical absorption and short carrier lifetime of graphene have restricted its practical application of photodetectors. Carbon dots (CDs) have received much attention due to their fascinating optical properties, environmentally-friendly nature, small size and superiority of a large optical absorptivity. Thus, in this work, hybrid photodetector of graphene and CDs has been proposed for the deep-UV photodetection, in which CDs integrated with graphene to form a planar hybrid structure. An inverse photoelectricity response was observed after illumination, which means the decline of conductivity under irradiation. The mechanism for this behavior is attributed to the built-in electric field generated across the interface between graphene layer and CDs layer, which separates the photogenerated electrons and holes, and promotes the holes to graphene layer and electrons to CDs layer. Our result demonstrates that the integration of graphene and CDs shows better optical absorption and wavelength selectivity. Together with the mechanism, it paves a step for practical applications of quantum dots sensitized graphene-based photodetectors.