Temporal dynamics of photonic stop-band in volatile solvent infiltrated opals

Abstract The effect of the infiltration of volatile solvents in photonic crystals is experimentally studied. Silica particles were synthesized and the opal structures were fabricated by self-assembly technique. Solutions containing various concentrations of methanol in ethanol were infiltrated in the opals and its effect on the temporal dynamics of the photonic stop-band during the evaporation process are studied. The recovery time of the solvent infiltrated opals is found to depend on the vapour pressure of the infiltrated solvent. The fabricated opal structures exhibit recovery time of ~2.8 s and 1.5 s for ethanol and methanol solvents respectively, with good repeatability. A model is proposed to understand the behaviour of volatile solvents in opals, and the observations made in the reflectance spectra are ascribed to the formation of saturated, funicular and pendular states. A comparative study of volatile solvents such as acetone, methanol, ethanol and 2-propanol is also performed and the effect of evaporation rates on the photonic stop-band is studied.