Observation of Photoinduced Charge Transfer in Novel Luminescent CdSe Quantum Dot-CePO4:Tb Metal Oxide Nanowire Composite Heterostructures

We report on the synthesis, structural characterization, and intrinsic charge transfer processes associated with novel luminescent zero-dimensional (0D) CdSe nanocrystal-one-dimensional (1D) CePO4:Tb nanowire composite heterostructures. Specifically, similar to 4 nm CdSe quantum dots (QDs) have been successfully anchored onto high-aspect ratio CePO4:Tb nanowires, measuring similar to 65 nm in diameter and similar to 2 mu m in length. Composite formation was confirmed by high-resolution transmission microscopy, energy-dispersive X-ray spectroscopy mapping, and confocal microscopy. Photoluminescence (PL) spectra, emission decay, and optical absorption of these nanoscale heterostructures were collected and compared with those of single, discrete CdSe QDs and CePO4:Tb nanowires. We show that our composite heterostructure evinces both PL quenching and a shorter average lifetime as compared with unbound CdSe QDs and CePO4:Tb nanowires. We propose that a photoinduced 0D-1D charge transfer process occurs between CdSe and CePO4:Tb and that it represents the predominant mechanism, accounting for the observed PL quenching and shorter lifetimes noted in our composite heterostructures. Data are additionally explained in the context of the inherent energy level alignments of both CdSe QDs and CePO4:Tb nanowires.