Temperature-Dependent Coupling in Hybrid Structures of Nanoparticle Layers Linked by Organic Molecules

Temperature-dependent photoluminescence (PL) measurements were used to probe how the nature of the organic linker changes the electronic coupling between two different sizes of nanoparticles (NPs) in hybrid bilayer assemblies that are adsorbed on GaAs and on quartz. While at room temperature, it was found that the conjugated linker, 1,4-benzenedimethanethiol (BDT), couples between the NPs better than a saturated alkyl linker of the same order of length; at 80 K, the coupling via the BDT linker is lower and equal to that found for the saturated hydrocarbon. The PL quenching mechanism that explains all of the observations is exciton energy transfer between the NPs by the Dexter mechanism. The GaAs was found to interact strongly with the NP assemblies and to quench their PL very efficiently as compared to the same assemblies adsorbed on quartz; however, the substrate does not affect the mechanism of energy transfer between the NPs.