Zinc oxide doping graphene oxide composites by brush coating for uniformly one-side formation thin films

We investigated the alignment properties of liquid crystals (LC) on a brush-coated composite film made of graphene oxide and zinc oxide (GO-ZnO). The GO-ZnO composites were prepared using a sol-gel solution process, and the resulting solution was brush-coated onto indium tin oxide (ITO) glass. During the annealing process, an anisotropic roughened surface was created; however, the crystallinity analysis of GO-ZnO indicated that the brushed coating did not affect the crystalline structure significantly. The LC molecules exhibited stable alignment characteristics owing to the aligned surface roughness and hydrophilic properties of GO-ZnO, resulting in a homogeneously aligned structure. Residual DC measurements showed similar levels as the conventional rubbed polyimide cells, and a switching voltage of 1.7 V was observed. Brush coating is a cost-effective and simple deposition/alignment process, making it crucial in terms of cost-efficiency and process simplicity.