Amorphous photonic structures exhibit interesting optical properties such as non-iridescent angle-independent structural colors and isotropic photonic band gaps. Here, we demonstrate colloidal assemblies of engineered amorphous photonic materials, using pigmentary α-Fe2O3/SiO2 core/shell nanoparticles, exhibiting non- iridescent and tunable colors. The observed colors result from combination of colloidal particle arrangements, giving arises to the structural colors, along with the inherent pigmentary color of the α-Fe2O3/SiO2 nanoparticles. Colloidal particle assemblies of α-Fe2O3/SiO2 core/shell nanoparticles, and therefore the resulting colors, can be manipulated by shell thickness, particle concentration and external electrical stimuli. α-Fe2O3/SiO2 nanoparticles based amorphous photonic structures exhibit short-range order on a length scale comparable to optical wavelengths and are weakly correlated to each other, as confirmed by ultra-small-angle X-ray scattering measurements. Dynamic tunability of α-Fe2O3/SiO2 nanomaterials in the visible wavelengths is demonstrated using electrophoretic deposition process with a noticeable difference between transmitted and reflected colors.

Tunable amorphous photonic materials with pigmentary colloidal nanostructures

255th National Meeting (2018)

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