Tuning the pore size of ZnO nano-grids via time-dependent solvent annealing

Via a block copolymer-assisted sol-gel synthesis route, zinc oxide (ZnO) thin films are obtained with a nanogrid-like morphology. During annealing of the hybrid ZnO films, the templating polymer undergoes structural rearrangements. Solvent annealing is done using tetrahydrofuran (THF) vapor and hence used as a tool to tune the pore size of the final grid-like films. A calcination step is performed to remove the polymer template and to study the effect of solvent annealing on the final ZnO nano-grid film. The surface structures of the films are investigated via scanning electron microscopy (SEM) and atomic force microscopy (AFM). In addition, the evolution in the structural length scales in the film volume is probed using grazing incidence small angle X-ray scattering (GISAXS).