Fabrication of Photoresponsive Nano-Organized Polymer Assemblies

Abstract

We describe here fabrication of organized polymer assemblies where the vectrial photoinduced electron transfer can be controlled by the spatial molecular arrangement by LB technique. The hetero-deposited redox polymer Langmuir-Blodgett (LB) films consisting of poly(N-dodecylacrylamide-co-ferrocenylmethylacrylate)(Fc copolymer) and poly(N-dodecy-lacrylamide-co-(4-(acryloylmethyl)-4′-methyl-2,2′-bipyridine)-bis(2,2′-bipyridine) ruthenium diperchlorate)) (Ru copolymer) were investigated by cyclic voltammetry and the steady state photocurrent measurement. Two kinds of the hetero-deposited structures are constructed by varying with the deposition order of these redox polymer monolayers using the LB technique. The cyclic voltammograms of the hetero-deposited redox polymer LB films show current rectifying and charge storage properties. On light irradiation, the anodic photocurrent is observed at the hetero-deposited redox polymer LB films consisting of Ru copolymer LB film as an inner layer and Fc copolymer LB film as an outer layer on the ITO (Fc/Ru/ITO) electrodes, whereas cathodic one is observed at the reverse layered structure (Ru/Fc/ITO) electrodes. The direction of photocurrent flow is controlled by the deposition order of the redox polymer LB films on ITO electrode. The magnitude of photocurrent depends on electrode potential, light intensity, sacrifier concentration, and irradiation wavelength. The mechanism for photocurrent generation is discussed.