Effect of ZnO dispersion in optical and structural of nematic liquid crystal

Abstract

Incorporation of zinc oxide (ZnO) semiconductor particles in liquid crystal technology is advantageous due to its unique optical properties especially in ultraviolet region. In this paper, optical and film morphology of nematic liquid crystal films, 4′-(hexyloxy)-4-biphenylcarbonitrile (6OCB) were analyzed using UV-Vis absorption spectroscopy, z-scan measurement, Raman spectroscopy and X-ray powder diffraction. As expected, dramatic change of absorption in both ultraviolet and visible region were observed upon additional weightage of ZnO particles into the 6OCB mixture. Z-scan measurement obtained under 532 nm CW laser line was used to study nonlinear refractive index, n2 of the material. This ZnO particles incorporation in 6OCB mixture show self-defocusing property with thermal effects as one of its origin of nonlinear absorption occurring at 532 nm. Prominent diffraction peaks of 15°, 29°, 31°, 35° and 47° were measured from rubbed films of 6OCB doped ZnO films which indicated 6OCB and ZnO lattice crystal structures. Microscopic formations of 6OCB molecules is highly dependent with the proximity to the ZnO particle as analyzed by Raman vibrational analysis. These findings can be used to suggest optical and electrical improvement to the liquid crystal film in optoelectronics application as electro-optic modulator and optical switch.