High-quality colloidal photonic crystals obtained by optimizing growth parameters in a vertical deposition technique

High-quality polystyrene colloidal crystals were fabricated from aqueous solutions with a vertical deposition technique. The role of sphere size, volume fraction, relative humidity (RH), evaporation temperature and the final drying conditions on the film quality were investigated. We found that all those parameters must be taken into account in order to achieve highest quality for a given particle size. With particles of 300 nm in diameter, the optimal conditions were found to be a 0.1-0.2% volume fraction, an RH between 80% and 90%, an evaporation temperature near 60degreesC and a quasi-equilibrium drying process. (C) 2004 Elsevier B.V. All rights reserved.