Apparatus and methods for a nano-patterning process to fabricate nanostructures. A roller type mold is used to continuously imprint nanostructures onto a flexible web or a rigid substrate. The process includes a coating and an imprinting module, which rotate the web synchronously. Liquid resist materials are used for imprinting and the patterns are set by thermal or UV curing. The process is used to produce bilayer metal wire-grid polarizers, organic solar cells, and organic light emitting diodes.