Unusual Photoelectrochemical Properties of Electropolymerized Films of a Triphenylamine-Containing Organic Small Molecule.

The electropolymerized films of poly(L)n on an indium-tin oxide (ITO) electrode was prepared by anodic electrooxidation of a dichloromethane solution of a triphenylamine-carrying organic molecule L and were characterized/studied by ultraviolet-visible absorption spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, electrochemical impedance spectroscopy, cyclic voltammetry, and photoelectrochemical measurements. Poly(L)n films were found to show surface-controlled TPA•+1/0 associated quasi-reversible redox and exceptionally high photocurrent generation properties. At a zero external bias potential and under 100 mW/cm2 white light irradiation, a photoelectrochemical device composed of a poly(L)1-modified ITO as the working electode, a platinum disk counter electrode, and saturated calomel electrode reference electrode in a 0.1 M Na2SO4 aqueous solution exhibited a significant cathode photocurrent density of 2.2 μA/cm2, which could be switched to be anodic and outperform most previously reported molecule-based modified ITO electrodes under similar experimental conditions. The results indicate that poly(L)n films offer a number of future perspectives ranging from organic photovoltaic to photoelectrochemical catalysis and sensing.