Orientational transition of p-pentyl-p'-cyano-biphenyls triggered by conformational change of surface azobenzene monolayer

We examined the orientational transition process of p-pentyl-p'-cyano-biphenyl (5CB) molecules in liquid crystal (LC) cells triggered by the conformational change of the surface azobenzene monolayer on polyimide (PI) Langmuir-Blodgett (LB) films, by measuring the optical transmittance and the electrical capacitance at the same time. The experimental results were analyzed using a continuum theory describing the free energy of LC cells. The transmittance and the capacitance of the LC cells with 1-layer PI LB films changed reversibly by the alternating irradiation of ultra-violet (UV) and visible light.