Transfer Printing of Solution‐Processed 3D ZnO Nanostructures with Ultra‐High Yield for Flexible Metasurface Color Filter

Abstract

AbstractThis work describes a facile thermal transfer printing process for solution‐processed high‐quality ZnO nanostructures. Nanostructures are synthesized through patterned solution growth and transfer‐printed onto a polymer substrate with an inverted configuration. Thus, the shape of the solution‐processed ZnO nanostructures can be regulated to have diversified forms, clearly defined edges, and improved surface profiles. To further demonstrate the scalability of such transfer printing process, a metasurface color filter with 300 µm × 500 µm “windmill” pattern is designed and more than 300 000 nanorod units included. After the structures are transferred, the color filter can be gradually tuned by O2 plasma treatment. Moreover, the uneven height of as‐synthesized nanorods with different diameters can be evenly rescaled, implying a precise control over the vertical dimension. Lastly, an ultra‐high transfer accuracy is validated with a lateral displacement of less than 7 nm. The presented work demonstrates a facile and low‐cost transfer printing route toward ZnO‐based metasurfaces on flexible substrates.