Quantifying the saturation of structural color from thin film polymeric photonic crystals

A range of color quantification methods are developed and applied to characterize the structural color of thin film photonic crystals known as polymer opals. Order is progressively induced within these engineered nanostructures, and three-dimensional reflectivity measurements allow for the ã€scattering cone' to be located and analyzed. Reported are observations that demonstrate how the chromatic properties of resultant structural color change as functions of both viewing angle and sample ordering. These measurements are mapped to a CIE 1931 color space, from which chromaticity metrics are readily extracted. The hue of structural coloration is shown to tune towards longer wavelengths by progressively improved structural order, and an improvement in color saturation can be observed as order is induced. In understanding how structural color can be quantified and manipulated, large-area photonic structures have potential for application as coatings and sensors, as well as smart fabrics and many other optical devices.