Optical Studies of the Methylene Blue-Semiconductor Nanocrystals Hybrid System

The methylene blue-semiconductor nanocrystals system was studied by absorption and fluorescence correlation spectroscopy, as well as integrated and time-resolved photoluminescence measurements. These studies point to the adsorption of methylene blue molecules on NC surface, with partial dimerization of the dye. Quantum dot luminescence quenching was observed with increasing dye concentration. Examination of band offsets for this system and lifetime measurements suggest that efficient charge transfer is responsible for the quenching. Surface functionalization of nanocrystals may reduce the extent of dye dimerization, thereby improving the charge transfer between CdTe nanocrystals and methylene blue.