Cuprous Oxide Cubic Particles with Strong and Tunable Mie Resonances for Use as Nanoantennas

The ability of plasmonic metal nanostructures (PMNs), such as silver and gold nanoparticles, to manipulate and concentrate electromagnetic fields at the nanoscale is the foundation for wide range of applications, including nanoscale optics, solar energy harvesting, and photocatalysis. However, there are inherent problems associated with plasmonic metals, such as high Ohmic losses and poorer compatibility with the conventional complementary metal–oxide–semiconductor (CMOS) microfabrication processes. These limitations inhibit the broader use of PMNs in practical applications. Herein, we report submicrometer cuprous oxide (Cu2O) cubic particles can exhibit strong electric and magnetic Mie resonances with extinction/scattering cross sections comparable to or slightly exceeding those of Ag particles. Using size- and shape-controlling particle synthesis techniques, optical spectroscopy, and finite-difference time-domain simulations, we show that the Mie resonance wavelengths are size- and shape-dependent and tunable in the visible to near-infrared regions. Therefore, submicrometer Cu2O cubic particles may potentially emerge as high-performance alternatives to PMNs. The strong electric and magnetic Mie-resonance-mediated nanoantenna attribute of the Cu2O cubic particles can be potentially used in a wide range of applications, including nanoscale optics, surface-enhanced Raman spectroscopy, surface-enhanced infrared absorption spectroscopy, photocatalysis, and photovoltaics.