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Characterization of tungsten trioxide thin film deposited by spin coating and the effect on their insertion in liquid crystal cells

Abstract:

The asymmetric insertion of oxide layers having mixed conduction properties (ionic and electronic) in liquid crystal cells induce various kinds of electro-optical response of the liquid crystals, and this behaviour has been related to the structural differences of the inserted films. In this work, is reported a structural study of such oxide films deposited on indium tin oxide (ITO) covered glasses. To have further confirmations of the model and a better understanding of the basic mechanism underlying the rectification effect and the connections with the structural and electrical properties of the films, WO 3 layers have been studied before and after thermal. Moreover the gelification via spin-coating, has been implemented and the optimization test of various relevant parameters have been performed. The chemical, structural and optical evolution has been extensively investigated as a function of the thermal annealing treatment, by performing vibrational spectroscopy analysis (micro-Raman and IR) impedance spectroscopy characterization and spectroscopic ellipsometry, before testing the films into the NLC cells.