Enhanced photoelectric performance of CdSe by graphene quantum dot modification

Abstract

CdSe/graphene quantum dots (GQDs) composites with varying contents of GQDs were prepared via a facile solvothermal process. The as-prepared CdSe, GQDs and CdSe/GQDs composites were investigated, and the results indicate that GQDs exhibit a transverse dimension of 10–15 nm and a topographic height of 1–2 nm. GQDs attached CdSe composites present well-defined lattice fringes with the interlamellar spacing of 0.34 and 0.21 nm ascribed to the (002), (220) crystal facets of GQDs and cubic CdSe, respectively. The performances of CdSe/GQDs composites were investigated by photocurrent-time measurements and electrochemical impedance spectra. The GQDs content plays a crucial part in promoting the photoelectric performance of CdSe/GQDs composites. With an increase of GQDs from 0.3 wt% to 1.2 wt%, the charge-transfer resistance reaches a minimum at a content of 0.9 wt% and displays a higher photocurrent density of 1.65 × 10−5 A cm−2, which is 13 times more than that of pristine CdSe.