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, ∼4 nm CdSe quantum dots (QDs) have been successfully anchored onto high-aspect ratio CePO₄:Tb nanowires, measuring ∼65 nm in diameter and ∼2 μm 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.