Growth of ZnO Nanorods and Their Applications for Liquid Crystal Devices

Abstract

Different morphologies of ZnO nanorods were synthesized by using the two-step hydrothermal method, and they were applied to liquid crystal (LC) alignment films. The morphology of the ZnO nanorods, including length, diameter, and density, were controlled by the growth time, which ranged from 16 to 26 min. The morphology and the chemical features both contributed to the surface wettability of the ZnO nanorods. The LC pretilt angle on the ZnO nanorods was successfully controlled from homeotropic (similar to 89.0 degrees) to homogeneous (similar to 1.7 degrees) alignments, as the contact angle of water on ZnO nanorods was changed from 93 to 28 with the growth time. The analysis of Xray diffraction and X-ray photoelectron spectroscopy showed that the crystallite size of ZnO nanorods increased with the growth time, while the oxygen vacancy decreased. The ZnO nanorods grown on the ITO glass substrate also improve the transmission of LCDs due to the antireflection effect.