LAUSR

Abstract An organic small molecule-based thin film on an indium-tin oxide (ITO) electrode was fabricated by anodic coupling of a novel thiophene unit-capping organic small molecule (L), and characterized by ultraviolet-visible absorption spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, cyclic voltammetry, electrochemical impedance spectroscopy, and photoelectrochemical measurements. The n cycles of anodic potential scanning produced red-colored electrodeposited films of Film(dimer-Ln) in minutes with visible light harvesting characteristics akin to those previously observed for ruthenium polypyridyl complex star dye-based films that were much more costly and difficultly accessible. Film(dimer-Ln) films were found to exhibit surface-controlled thiophene unit associated redox behaviors and significant cathodic photocurrent generation properties. As irradiated with white light at 100 mW cm−2 and biased at a zero potential, a Film(dimer-L2)-modified ITO electrod exhibited a high photo-to-current conversion efficiency of 0.90% at 450 nm, and a photocurrent density of 13.6 μA cm−2 in an N2-saturated electrolyte solution, which was greatly boosted by ~7 folds to 108.8 μA cm−2 in an O2-saturated electrolyte solution. The resulting modified electrodes offer great prospects for a wide range of applications ranging from photoelectric conversion to light detection devices to photoelectrocatalytic O2 reduction and sensing.