Engineered Unidirectional Scattering in Metal Wire Networks for Ultrahigh Glass-Like Transparency

Abstract

Wavelength-scale objects usually diffuse incident light into all directions, thereby resulting in a low transmittance accompanied by a thick haze. The degradation of visibility remains a more challenging problem for metal nanostructures due to the excitation of localized surface plasmon resonances, which impedes their practical use in display applications. Here, we report a broadband, polarization- and angle-independent near-unity transmittance from a network of submicron Ag wires via the suppression of backward scattering. Electromagnetic simulations on a single Ag wire predicted that a conformal, dielectric shell suppresses backward scattering while only boosting the zeroth-order forward scattering. A facile oxidation process on electrospun Ag wires produced Ag/Ag2O core/shell wires randomly dispersed on a glass substrate. Measurements of spatially (1.5 x 1.5 cm(2)) and spectrally (lambda = 480-880 nm) averaged transmittance revealed that Ag/Ag2O wires (with an Ag filling ratio of 3.4%) recorded a transmittance of approximately 99%, relative to a bare glass substrate. A dark-field microscope equipped with a spectrometer quantified the level of the suppressed backward scattering in Ag/Ag2O wires. The scattering engineering technique presented herein will be essential to developing metal particle or wire embedded dielectric films that act as high-transmittance specular surfaces.