Distinctive Enhanced and Tunable Plasmon Resonant Absorption from Controllable Au@Cu2O Nanoparticles: Experimental and Theoretical Modeling

Aiming to explore cooperative interactions between plasmonic metal and semiconductor nanostructures as well as their special plasmon resonant properties, we synthesized Au@Cu2O core–shell nanoparticles to demonstrate the dramatic influence of dielectric shell both experimentally and theoretically. The extinction spectra of Au@Cu2O nanoparticles with controllable shell thickness from a few layers to over 20 nm show not only a tunable red shift of resonant peak but also distinctive enhanced absorption intensity and peak splitting. We then built an analytical model based on an approximate Mie's theory to interpret their optical features. From this model, we found that the overall optical cross section and absorption portion of Au@Cu2O are dramatically enlarged. It has been shown that the proper dielectric shell-coated plasmonic nanoparticles could be very promising, especially for the applications that need effective enhancement of the plasmon resonant absorption.