Photophysical Properties of Au-CdTe Hybrid Nanostructures of Varying Sizes and Shapes

We design well-defined metal-semiconductor nanostructures using thiol-functionalized CdTe quantum dots (QDs)/quantum rods (QRs) with bovine serum albumin (BSA) protein-conjugated Au nanoparticles (NPs)/nanorods (NRs) in aqueous solution. The main focus of this article is to address the impacts of size and shape on the photophysical properties, including radiative and nonradiative decay processes and energy transfers, of Au-CdTe hybrid nanostructures. The red shifting of the plasmonic band and the strong photoluminescence (PL) quenching reveal a strong interaction between plasmons and excitons in these Au-CdTe hybrid nanostructures. The PL quenching of CdTe QDs varies from 40 to 86?% by changing the size and shape of the Au NPs. The radiative as well as the nonradiative decay rates of the CdTe QDs/QRs are found to be affected in the presence of both Au NPs and NRs. A significant change in the nonradiative decay rate from 4.72x106 to 3.92x1010 s-1 is obtained for Au NR-conjugated CdTe QDs. It is seen that the sizes and shapes of the Au NPs have a pronounced effect on the distance-dependent energy transfer. Such metal-semiconductor hybrid nanostructures should have great potentials for nonlinear optical properties, photovoltaic devices, and chemical sensors.