Au-Cu2O Core-Shell Nanoparticles: A Hybrid Metal-Semiconductor Heteronanostructure with Geometrically Tunable Optical Properties

Metal-semiconductor hybrid heteronanostnictures may exhibit not only a combination of properties from the disparate components but also further enhanced property tunability and new synergistic properties that arise from the interactions between the metal and semiconductor components. Here we demonstrate that the Au-Cu2O hybrid core-shell nanoparticles not only combine the optical signatures of Cu2O nanoshells and the plasmonic properties of Au nanoparticles but exhibit further enhanced and expanded plasmonic tunability as well due to the dielectric properties of the Cu2O shells surrounding the Au cores. We have developed a robust wet chemistry approach through which we can fine-control several important geometrical parameters of the Au-Cu2O core-shell nanoparticles, such as Cu2O shell thickness, size of the Au core, and the spacing between the core and shell, to systematically and selectively fine-tune the synergistic light absorption and scattering properties of the particles over a broad spectral range across the visible and near-infrared regions. We have further performed Mie scattering theory calculations to theoretically interpret the correlation between the geometrical parameters and optical characteristics of the Au-Cu2O hybrid nanoparticles. Such optical tunability achieved through the fine-control over core and shell geometries is believed to be important to the optimization of the overall performance of hybrid heteronanostructure-based materials and/or devices for photonic, electronic, and optoelectronic applications.