Recent progress in non-photolithographic patterning of polymer thin films

Patterned polymer thin films are essential components in many devices and applications owing to the multi-functionality, flexibility, lightweight and cost-efficiency. Unfortunately, conventional photolithography needs the use of developers and strippers which contain solvents and reagents that may dissolve, swell or degrade the polymer thin film substrates. Alternatively, non-photolithographic strategies provide alternative options and avoid the complicated optical systems, offering versatile routes for fabricating polymeric micro- and nanostructures. In this review, we summarize the recent progress in non-photolithographic patterning methods including soft lithography, nanoimprint lithography, direct writing, self-assembly of block copolymers, area-selective vapor phase deposition and instability induced patterning. These patterning approaches have been applied to various applications such as chromic devices, polymer light-emitting diodes, sensors, transistors, and protein and cellular engineering and many other scenarios. Finally, the subsisting challenges and future research directions of non-photolithographic patterning approaches are highlighted from the aspect of resolution, reliability and scalability.