Characterization of Tungsten Trioxide Thin Film Deposited by Spin Coating and the Effect on Their Insertion in Liquid Crystal Cells

The asymmetric insertion of oxide layers having mixed conduction properties(ionic and electronic) in liquid crystal cells induce various kinds of electro-opticalresponse of the liquid crystals, and this behaviour has been related to the structuraldifferences of the inserted films. In this work, is reported a structural study ofsuch oxide films deposited on indium tin oxide (ITO) covered glasses. To havefurther confirmations of the model and a better understanding of the basic mechanismunderlying the rectification effect and the connections with the structuraland electrical properties of the films, WO3 layers have been studied before andafter thermal. Moreover the gelification via spin-coating, has been implementedand the optimization test of various relevant parameters have been performed.The chemical, structural and optical evolution has been extensively investigatedas a function of the thermal annealing treatment, by performing vibrational spectroscopyanalysis (micro-Raman and IR) impedance spectroscopy characterizationand spectroscopic ellipsometry, before testing the films into the NLC cells.