Tuning the Charge-Transfer Property of PbS-Quantum Dot/TiO2-Nanobelt Nanohybrids via Quantum Confinement

A newly designed photoactive nanohybrid structure based on the combination of near-infrared PbS quantum dots (QDs) as light harvester and one-dimensional TiO 2 nanobelts (NBs) to guide the flow of photogenerated charge carriers is reported. Efficient electron transfer from photoexcited PbS QDs to TiO 2 NBs has been demonstrated to occur in the developed PbS-QD/TiO 2 -NB nanohybrids, and the charge-transfer property can be tuned through the size quantization effect of PbS QDs. Moreover, the use of TiO 2 NBs instead of TiO 2 NPs permits a larger critical size of PbS QDs capable of injecting electrons into TiO 2 NBs, which, in turn, markedly extends the “effective” absorption of the PbS-QD/TiO 2 -NB nanohybrids to a longer wavelength region up to 1400 nm. Such an extension of the “effective” absorption is a major asset for improving the overall photoconversion efficiency of PbS-QD/TiO 2 -NB nanohybrids-based photovoltaic devices.