Pigment-Free Multicolor Drawing Using Colloidal Dispersions

Abstract

Structural color (SC) is a color that comes from periodic nanostructures making constructive interference at certain wavelengths. Colloids are popular building blocks for the periodicity in SC materials, and many studies have been conducted to form their patterns. However, the patterning takes a long time and complex procedures along with complicated conditions like wettability and controlled solvent evaporation. Here, we suggest direct-writing of SC patterns with highly concentrated colloidal dispersion, which enables their unprecedentedly customizable production. The high particle fraction imparts high viscosity and strong repulsive property to the dispersion so that the ink becomes printable at high speeds and resolution and final patterns become highly crystalline. Also, we can also freely control color chroma, substrate, and mechanical properties of the patterns. This strategy customizes SC patterns that serve as anti-counterfeiting, sensors, and next-generation designs.