  Optical properties of core-shell-shell Au@SiO2@Au nanostructures and their
solar energy harvesting applications are theoretically investigated using Mie
theory and heat transfer equations. The theoretical analysis associated with
size-dependent modification of the bulk gold dielectric function agrees well
with previous experimental results. We use the appropriate absorption
cross-section to determine the solar energy absorption efficiency of the
nano-heterostructures, which is strongly structure-dependent, and to predict
the time-dependent temperature increase of the nanoshell solution under
simulated solar irradiation. Comparisons to prior temperature measurements and
theoretical evaluation of the solar power conversion efficiency are discussed
to provide new insights into underlying mechanisms. Our approach would
accelerate materials and structure testing in solar energy harvesting.
