Molecular Orientations and Photoconductivity in LB Films

Abstract

Abstract N-Docosylquinolium-TCNQ was synthesized and the π-A isotherm of the molecule was obtained. The TCNQ anion radical is particulary interesting because it gives a good electrical conductivity as for the organic materials. The π-A isotherm of the N-docosylquinolium-TCNQ exhibited a break at the surface pressure of 30mN/m. The limiting area per molecule calculated at the surface pressure of 30mN/m is 68A2 and that at 45mN/m was 32A2. The orientation and arrangement of the TCNQ anion radical fabricated on a glass surface at each surface pressure were studied with polarization technique. The LB film layered at 30mN/m shows dichroic behavior with respect to the direction of dipping. The photoconductivities of the quinolium-TCNQ LB films fabricated at 30 and 45mN/m were 3.9×10−9S/cm and 2.84 × 10−8S/cm, respectively. The difference in photoconductivity may result from the molecular orientations which are deduced on the ground of the optical properties and polarization results.