Suspended-Template Electric-Assisted Nanoimprinting for Hierarchical Micro-Nanostructures on a Fragile Substrate

Coating hierarchical micro-nanostructures on the surface of optoelectronic devices has been demonstrated to improve the overall performance. However, fabricating desired structures on a fragile optoelectronic device substrate is still challenging. A suspended-template electric-assisted nanoimprinting technique is proposed herein to controllably fabricate hierarchical micro-nanostructures on a fragile substrate. The suspension design of the template ensures that it conveniently deforms to fully fit the surface fluctuation of the substrate. The deformation of template and the filling of liquid polymer in the micro/nanocavities of the template are both driven by the powerful surface/interface force generated by an electric field applied between the template and substrate surface, thus protecting the fragile substrate from squeezing damage. Different morphologies of hierarchical micro-nanostructures are fabricated by changing the electric field. Based on suspended-template electric-assisted nanoimprinting, the environmentally adaptable fully covering hierarchical micro-nanostructures are encapsulated on the surface of flip-film light-emitting diode chips, thus significantly enhancing their light management in complex environments.