Efficient structural color from pigment-loaded nanostructures

TL;DR

This paper demonstrates that embedding pigment in nanostructures enhances bright structural color efficiency and reduces iridescence, enabling vivid non-iridescent colors with fewer layers than traditional methods.

Contribution

The study introduces a novel pigment-loading technique in multilayer nanostructures to produce bright, non-iridescent structural colors more efficiently than existing approaches.

Findings

Achieved peak reflectance over 0.8 at 550 nm with only 10 layers.

Pigment loading reduces the number of layers needed compared to pigment-free structures.

Numerical simulations suggest expanded non-iridescent color range in photonic glasses.

Abstract

Color can originate from wavelength-dependence in the absorption of pigments or the scattering of nanostructures. While synthetic colors are dominated by the former, vivid structural colors found in nature have inspired much research on the latter. However, many of the most vibrant colors in nature involve the interactions of structure and pigment. Here, we demonstrate that pigment can be exploited to efficiently create bright structural color at wavelengths outside its absorption band. We created pigment-enhanced Bragg reflectors by sequentially spin-coating layers of poly-vinyl alcohol (PVA) and polystyrene (PS) loaded with $\beta$-carotene (BC). With only 10 double layers, we acheived a peak reflectance over $0.8$ at 550 nm and normal incidence. A pigment-free multilayer made of the same materials would require 25 double layers to achieve the same reflectance. Further, pigment loading suppressed the Bragg reflector's characteristic iridescence. Using numerical simulations, we further show that similar pigment loadings could significantly expand the gamut of non-iridescent colors addressable by photonic glasses.