Fabrication parameters affecting the structural color of colloidal films: A combined numerical investigation

Abstract

Colloidal assembly formed by drying of suspensions is expected to be applied to optical materials using their structural color resulting from the microstructure. We combine two numerical simulation techniques to investigate how the fabrication conditions of the self-assembled colloidal films affect their structural color. We first perform Langevin dynamics simulations to form colloidal films with various microstructures depending on the several fabrication parameters and then perform the finite-difference time-domain simulations of electromagnetic field analysis to calculate the structural color intensity of the obtained microstructures. To improve the structural color intensity, we show that the surface tension of the solvent should be sufficiently large so that capillary interactions exceed the interparticle adhesion by van der Waals force and furthermore that under this condition the smaller drying rate is favorable. This study suggests a guideline to design the fabrication process of colloidal films generating structural color.