Optically tunable and reconfigurable azobenzene photonic crystal

The generation of three-dimensional (3D) nanoporous materials with methods that allow control of the shape and size is an important issue owing to its numerous applications to the areas of material sciences and nanophotonics. However, the methods typically used for fabricating nanoporous structures, such as self-assembly, direct writing, and interference lithography, cannot modify the structural morphologies much over a large area at the same time. In this work, we prepare azobenzene-based oligomer films with controllable pore sizes and shapes by means of directional photofluidization lithography. This strategy by using the photo-reconfiguration of oligomers enables an unprecedented degree of precise manipulation of structural features and the generation of hierarchical porosity in a three-dimensionally interconnected network.