Tension gradient-driven rapid self-assembly method of large-area colloidal crystal film and its application in multifunctional structural color displays

Liquid-air interface self-assembly (such as the classic L-B method) is the most popular way to form high-quality colloidal crystal monolayers, yet still limited by sophisticated equipment, time-consuming processes and small preparation area. Here, a tension gradient-driven nanoparticle self-assembly method is proposed to realize the high-efficiency and low-cost fabrication of large-area (25 x 18 cm(2)) colloidal crystal film. The periodic nanoparticle structures composed of various particles with different materials and diameters can be easily obtained in a short time and transferred to various substrates under this self-assembly method. And the preparation area is one to two orders of magnitude higher than the conventional self-assembly method. The simulation results align well with experiments, indicating that the Marangoni effect induced by tension gradient is the main driving force for self-assembly. The influence of various self-assembly parameters is investigated. Inspired by amber, a periodic particle/PDMS/nano-silica particles composite film is further designed to form a large-area durable structural color display. The structural color of the composite film is surprisingly different from that of the periodic particle which was mainly due to the unique semi-coated structure. The composite film has outstanding super-hydrophobic and self-cleaning performance with a broad impact on durable structural color displays/sensors, anti-counterfeiting and other aspects.