CdSe-graphene oxide light-harvesting assembly: size-dependent electron transfer and light energy conversion aspects.

Excited-state interaction between CdSe quantum dots (QDs) of different sizes (2.3, 3.2, and 4.2 nm diameter) and graphene oxide (GO) was probed by depositing them as films on conducting glass electrodes. The emission of smaller CdSe QDs (2.3 nm) was quenched by GO three times faster than that of larger QDs (4.2 nm). Electrophoretic deposition allowed us to sequentially deposit single or multiple layers of different sized QDs and GO assemblies on conducting glass electrodes and to modulate the photoresponse in photoelectrochemical solar cells. Superior photoconversion efficiency through the incorporation of GO was attributed to improved charge separation in the composite assembly.