RESUMO
We investigated the interaction of an intense laser radiation with colloidal solutions containing CdSe/ZnS core shell quantum dots (QDs; mean size 3.4 nm), fullerene C(60), and Perylene. These materials would give rise to the photoinduced electron transfer and charge separation on the QDs and thus the optical limiting effect. Results confirm the intended aim, obtained by means of intermediate metastable products of reversible photochemical reactions, i.e., ion radicals of hybrid systems containing semiconductor nanoparticles.
RESUMO
The passivation influence by ligands coverage with trioctylphosphine oxide (TOPO) and TOPO including colloidal CdSe/ZnS quantum dots (QDs) on optical properties of the semiconductor heterostructure, namely an array of InP nanowires (NWs) with InAsP nanoinsertion grown by Au-assisted molecular beam epitaxy on Si (111) substrates, was investigated. A significant dependence of the photoluminescence (PL) dynamics of the InAsP insertions on the ligand type was shown, which was associated with the changes in the excitation translation channels in the heterostructure. This change was caused by a different interaction of the ligand shells with the surface of InP NWs, which led to the formation of different interfacial low-energy states at the NW-ligand boundary, such as surface-localized antibonding orbitals and hybridized states that were energetically close to the radiating state and participate in the transfer of excitation. It was shown that the quenching of excited states associated with the capture of excitation to interfacial low-energy traps was compensated by the increasing role of the "reverse transfer" mechanism. As a result, the effectiveness of TOPO-CdSe/ZnS QDs as a novel surface passivation coating was demonstrated.