Fabrication of large-area, close-packed, monolayer colloidal crystals via a hybrid method of spin coating and peeling-draining

Large-area, close-packed, monolayer colloidal crystals can be used as templates in the preparation of micro/nano films. This work proposes a hybrid method of spin coating and peeling-draining for the production of large-area, close-packed, monolayer colloidal crystals. First, large-area monolayer polystyrene (PS) colloidal crystals were obtained through spin coating. Then, the colloidal crystal film was peeled from surface of the intermediate spin-coated silicon wafer and transferred to another substrate using a customized experimental device. Oxygen plasma treatment was utilized to modify the wettability of the silicon wafer, increase the uniformity of spin coating, and reduce the adhesion work of peeling. The key process parameters, such as the duration of oxygen plasma treatment, spin speed, peeling speed, and drop rate of water surface, of the proposed method were thoroughly analyzed and optimized. Three-inch, wafer-scale, large-area, close-packed monolayer colloidal crystals were obtained using the proposed method, which combines the advantages of spin coating and gas-liquid interface self-assembly and offers a stable and controllable approach to the fabrication of monolayer PS colloidal crystals.