Fabrication of tough photonic crystal patterns with vivid structural colors by direct handwriting

Patterned photonic crystals (PCs) have attracted considerable attention due to their great potential in practical applications. Direct writing is an important and convenient method to fabricate patterned PCs. However, due to the limited interaction among spheres and the evaporation of ink, the obtained patterns usually suffer from poor structure strength, and non-uniform and unstable structural colors. In this work, an in situ embedding and locking strategy for fabricating tough PC patterns in one step was demonstrated. With properly dried polymer films as "paper" and dispersions of CdS spheres as "inks" to write on the "paper", the self-assembly of CdS spheres and locking of the PC structure can be achieved simultaneously, which gives rise to tough composite patterned PCs with uniform, stable and permanent structural colors. Based on this simple method, tough PC patterns can be easily and quickly created by direct hand writing or drawing without special treatment, equipment, masks or templates. The vivid structural colors of the tough PC patterns and this simple method show great potential for practical applications.