Tailored nano-pillar structures on surfaces: Facile formation and multifunctional properties

Nano-pillar structured surfaces have prized for exceptional optoelectronic properties and biocompatibility but commonly complex, expensive, and inflexible in production. A systematic investigation of the formation, mechanisms, and properties of nanostructures induced by nano-capillaries remains unexplored. Through this study, the facile formation of nano-pillared surfaces induced by designable nano-capillaries on AAO template demonstrated significant improvements in antibacterial effect, spectral structural color and anti-reflection characteristics. Reverse molding of nano-pillar arrays with aspect ratios of up to 1.2 on polydimethylsiloxane (PDMS) films yielded a super-hydrophobic surface of 150° contact angle (CA). Through the utilization of computational fluid mechanics model, a direct correlation was demonstrated between the aspect ratio of nano-pillars and the viscosity of PDMS. The nano-pillared surfaces had remarkable antibacterial rates of 91 % for Escherichia coli and 89 % for Staphylococcus aureus. In addition, the structured surfaces exhibited color spanning from light blue to light red by tuning nano-pillars dimensions, incident light angle, and/or adding reflective metallic coating, which offered unique visualization effects for anti-counterfeiting. Moreover, the superior light-trapping and anti-reflection of the nano-pillared surface significantly increased the power conversion efficiency (PCE) 19 % from the base performance of the polysilicon solar cells.