Graphoepitaxy of Block-Copolymer Self-Assembly Integrated with Single-Step ZnO Nanoimprinting

A highly efficient, ultralarge‐area nanaolithography that integrates block‐copolymer lithography with single‐step ZnO nanoimprinting is introduced. The UV‐assisted imprinting of a photosensitive sol–gel precursor creates large‐area ZnO topographic patterns with various pattern shapes in a single‐step process. This straightforward approach provides a smooth line edge and high thermal stability of the imprinted ZnO pattern; these properties are greatly advantageous for further graphoepitaxial block‐copolymer assembly. According to the ZnO pattern shape and depth, the orientation and lateral ordering of self‐assembled cylindrical nanodomains in block‐copolymer thin films could be directed in a variety of ways. Significantly, the subtle tunability of ZnO trench depth enabled by nanoimprinting, generated complex hierarchical nanopatterns, where surface‐parallel and surface‐perpendicular nanocylinder arrays are alternately arranged. The stability of this complex morphology is confirmed by self‐consistent field theory (SCFT) calculations. The highly ordered graphoepitaxial nanoscale assembly achieved on transparent semiconducting ZnO substrates offers enormous potential for photonics and optoelectronics. ZnO topographic patterns with various pattern shapes formed by a single‐step nanoimprinting process can serve as templates for graphoepitaxial block‐copolymer assembly, generating complex hierarchical nanopatterns where surface‐parallel and surface‐perpendicular nanocylinder arrays are alternately arranged.