Optical and electrical properties of polyamic acid alkylamine salts (PAAS) Langmuir-Blodgett (LB) films

It is important to investigate the molecular arrangement and the orientational distribution in the study of LB films. Polarized UV/visible spectra make it possible to reveal the arrangement and the orientational distribution. It is clarified that the PAAS LB films have specific directions in the molecular arrangement and the orientational distribution, which are different in intensity corresponding to the surface pressure. Unpolarized UV/visible absorption spectra reveal that the surface pressure is proportional to the film thickness and is related to the molecular orientation. Current-Voltage (I-V) measurements provide that the current decreases as the surface pressure increases and there are certain phenomena called switching phenomena. Switching effect indicates that the current flows in high conductivity during on-state and suddenly decreases into low conductivity during off-state.