One-Step, Solvothermal Synthesis of Graphene-CdS and Graphene-ZnS Quantum Dot Nanocomposites and Their Interesting Photovoltaic Properties

The synthesis of graphene-semiconductor nanocomposites has attracted increasing attention due to their interesting optoelectronic properties. However the synthesis of such nanocomposites, with decorated particles well dispersed on graphene, is still a great challenge. This work reports a facile, one-step, solvothermal method for the synthesis of graphene-CdS and graphene-ZnS quantum dot nanocomposites directly from graphene oxide, with CdS and ZnS very well dispersed on the graphene nanosheets. Photoluminescence measurements showed that the integration of CdS and ZnS with graphene significantly decreases their photoluminescence. Transient photovoltage studies revealed that the graphene-CdS nanocomposite exhibits a very unexpected strong positive photovoltaic response, while separate samples of graphene and CdS quantum dots (QDs) of a similar size do not show any photovoltaic response.