Liquid-crystal-electrochromic-material interface: A p-n-like electro-opticjunction - art. no. 011708

A liquid crystal (LC) cell has been made by using a standard sandwich confi guration with one of the indium tin oxide (ITO) electrodes covered by a thi n layer of tungsten trioxide (WO3). In this kind of cell optical polarizati on switching (observed under a crossed polarizer microscope) occurs for onl y one of the two polarities of an ac external applied electric field, while in the usual liquid crystal cells the electro-optic response does not depe nd on the sign of the field. The inhibiting switching configuration corresp onds to anodic polarization of the tungsten trioxide film in which the dein tercalation of cations occurs. Here we present the time behavior of charge and discharge for both the anodic and cathodic currents. A model based on c harge carrier exchange between the ITO-WO3 and WO3-LC interfaces and also e lectrochemical processes is reported. Our model is also capable of explaini ng the electric and electro-optic asymmetric responses of the cell. Numeric al calculations confirm the model.