A new kind of a liquid crystal cell has been made by using a standard sandwich configuration with one of the ITO electrodes, covered by a thin layer of tungsten trioxide deposited by r.f. sputtering in a reactive atmosphere of Ar and O-2 gas. In this kind of cell the optical polarisation switching of the cell (observed under a crossed polarizer microscope) occurs only for one of the two directions of the a.c, applied field, while in the usual liquid crystal cells the electro-optic response does not depend on the sign of field. The inhibiting switching configuration corresponds to the anodic polarisation of tungsten trioxide film in which the de-intercalation of cations occurs. Preliminary impedance measurements reveal an ionic diffusion process in such devices (Warburg impedance behavior). These preliminary results suggest speculations about a reverse internal electric field, which is responsible for the increased threshold of optical switching in one direction only of the applied field. (C) 1999 Elsevier Science Ltd. All rights reserved.
A new kind of a liquid crystal cell has been made by using a standard sandwich con®guration with one of the ITO electrodes, covered by a thin layer of tungsten trioxide deposited by r.f. sputtering in a reactive atmosphere of Ar and O2 gas. In this kind of cell the optical polarisation switching of the cell (observed under a crossed polarizer microscope) occurs only for one of the two directions of the a.c. applied ®eld, while in the usual liquid crystal cells the electro-optic response does not depend on the sign of ®eld. The inhibiting switching con®guration corresponds to the anodic polarisation of tungsten trioxide ®lm in which the de-intercalation of cations occurs. Preliminary impedance measurements reveal an ionic diusion process in such devices (Warburg impedance behavior). These preliminary results suggest speculations about a reverse internal electric ®eld, which is responsible for the increased threshold of optical switching in one direction only of the applied field.
Insertion of thin films of WO3 in liquid crystal cells
SCARAMUZZA, Nicola;STRANGI, Giuseppe;VERSACE, Consolato Carlo;
1999
Abstract
A new kind of a liquid crystal cell has been made by using a standard sandwich configuration with one of the ITO electrodes, covered by a thin layer of tungsten trioxide deposited by r.f. sputtering in a reactive atmosphere of Ar and O-2 gas. In this kind of cell the optical polarisation switching of the cell (observed under a crossed polarizer microscope) occurs only for one of the two directions of the a.c, applied field, while in the usual liquid crystal cells the electro-optic response does not depend on the sign of field. The inhibiting switching configuration corresponds to the anodic polarisation of tungsten trioxide film in which the de-intercalation of cations occurs. Preliminary impedance measurements reveal an ionic diffusion process in such devices (Warburg impedance behavior). These preliminary results suggest speculations about a reverse internal electric field, which is responsible for the increased threshold of optical switching in one direction only of the applied field. (C) 1999 Elsevier Science Ltd. All rights reserved.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
