IONIC-CONDUCTION AND PHOTOISOMERIZATION IN AZOBENZENE LANGMUIR-BLODGETT-FILMS ADSORBING CYANINE DYES

Azobenzene (At) Langmuir-Blodgett (LB) films adsorbing cyanine dyes (N K-3) were deposited and the electrical properties were investigated in detail. The current vs electric held characteristics suggested ionic hopping conduction, and the transient current properties showed curren t peaks due to migration of mobile ions. The thermally stimulated curr ents (TSCs) were also due to the ionic space charge polarization, that is, displacement of mobile ions over long distances in the LB films. These results indicated that the electrical properties of the Az LB de vices are strongly dependent on the mobile ions in the devices. In add ition, the TSC and the short-circuit photocurrent properties due to th e dyes were also changed by isomerization of the Az molecules. The res ults showed that the ionic space charge polarization and the aggregate s of the dyes were affected by the isomerization.