Three-dimensional high-rate electropolymerized thin film with exceptionally high photocurrent based on a triphenylamine-containing ruthenium complex

Abstract

A novel ruthenium complex capped with three triphenylamine units was synthesized and was high-rate anodically electropolymerized to form dense thin films of 33-nm thickness/per potential cycle on indium-tin oxide (ITO) electrodes. The films were studied by UV–vis absorption and X-ray photoelectron spectroscopy, atomic force microscopy, scanning electron microscopy, X-ray diffraction, cyclic voltammetry and photoelectrochemical measurements. Electrical conductivity of an electropolymerized film has also been measured by two-probe method. The results revealed that even the monolayer metallopolymeric thin films presented surface-controlled RuIII/II and TPA+1/0 associated redox behaviours and exceptionally strong photocurrent generation properties. As irradiated with white light at 100 mW/cm2, a monolayer film-modified ITO electrode without an applied bias voltage in 0.1 M Na2SO4 aqueous solution showed a significant cathodic photocurrent of 10.7 μA cm−2, which compares favorably with those previously reported for indium-tin oxide electrodes modified by Ru(II) complex-based electrostatically self-assembled and solvent-casting films under similar experimental conditions. The mechanism of the cathodic photocurrent generation mechanism is discussed.