Asymmetric nematic liquid crystal cells containing lead zirconium titanate (PZT) films

Abstract

Interest in thin films of PZT (lead zirconium titanate PbZr0.47Ti0.53O3) has increased because of their potential applications. For instance, the insertion of PZT in asymmetric nematic liquid crystal cells induces a rectified electro-optical response similar to that observed in such cells because of the insertion of metal oxide layers with ionic conductivity. In the present work several PZT films have been investigated, obtained by different thermal treatments after sol-gel synthesis and spin coating deposition. The observed rectifying effect, due to the insertion of PZT films in asymmetric liquid crystal cells, has been attributed to the presence of an internal field made from the reorientation of nanodomains of PZT. The presence of such internal fields is demonstrated and an estimation of it is given. Moreover, asymmetric nematic liquid crystal cells made with PZT films show considerable improvements in both contrast and response time.

Thermal induced changes of lead zirconium titanate films and their consequences for liquid crystal devices applications

“…Due to their good optical properties, PZT thin films have been used recently as electrodes in asymmetric nematic liquid crystal (ANLC) cells, where they induce a polarity-sensitive electro-optical response of the liquid crystal layers [5]. Such effect has been previously obtained by inserting thin films of metal oxides like WO3 and V2O5 , well-known for their applications to electrochromism in ANLC cells.…”

“…Besides the recognition of the effect produced by the insertion of PZT films on the electrooptical response of ANLC cells, previously reported [5], a further research step is carried out here to have some correlation between the amount of the effect and the differences among the PZT films, due to their thermal history, with the aim to optimize the application of these films to liquid crystal devices.…”

“…In the case of inserted PZT films a different mechanism has been invoked: the internal field producing the electro-optical rectified response should be related to the polarization of ferroelectric PZT [5].…”

Anomalous conductivity in PZT thin film deposited on copper substrate electrode

“…The details of the synthesis can be found elsewhere [3]. To obtain thin films, a spin coater, supplied by CaLCTec s.r.l.…”

“…Thin films of lead zirconate titanate are of great scientific and technological interest, especially during the last decade, because of their application in non volatile memories, sensors and, more recently, in asymmetric nematic liquid crystal cells [1][2][3]. Moreover, the problems associated with the applications of ferroelectrics such as:…”