Progress in Printable Colloidal Photonic Crystals

Printable colloidal photonic crystals (CPCs) with unique photonic bandgaps and elaborate shapes have attracted significant interest due to their characteristics, such as simplicity of fabrication, adjustable structural colors, photobleaching resistance, and stimulus-responsiveness. In this review, strategies for printing CPC patterns, including direct use of CPCs as inks, region-selective modification on responsive (solvent, force, and temperature) CPC papers, and printing combined with lithography, are first summarized. Second, based on the advantages of CPC printing technology, their applications in color displays, coatings, sensors, anticounterfeiting labels, and information storage, are discussed in detail. Finally, the current challenges and outlook regarding CPC printing technology are proposed.