Exploring the Direction of Charge Transfer in Porphyrin – PbSe Quantum Dot Hybrids

摘要

The binding interaction of amine, thiol and carboxylic acid functionalized porphyrins to PbSe semiconductor quantum dots (QDs) has been studied by focusing on absorption and fluorescence of porphyrins in presence of PbSe QDs and absorption and fluorescence of PbSe QDs in presence of porphyrins. Only tetra-carboxylic acid functionalized porphyrins appear to have significant binding to QDs. Fluorescence life time measurements show that the binding is dynamic rather than static, opposed to the case of metallic gold nanoparticles previously studied. QDs appear to reduce in size by dissolution, when they are exposed for longer times to porphyrins containing carboxylic acid functional groups. Transient absorption spectroscopy shows that charge transfer occurs uni-directional from porphyrins to QDs as expected and not the other way round.