Carbon Optically Transparent Electrodes for Electrogenerated Chemiluminescence

This study investigates pyrolyzed photoresist film (PPF)-based carbon optically transparent electrodes (C-OTEs) for use in electrogenerated chemiluminescence (ECL) studies. Oxidative-reductive ECL is obtained with a well-characterized ECL system, C8S3 J-aggregates with 2-(dibutylamino)ethanol (DBAE) as coreactant. Simultaneous cyclic voltammograms (CVs) and ECL transients are obtained for three thicknesses of PPFs and compared to nontransparent glassy carbon (GC) and the conventional transparent electrode indium tin oxide (ITO) in both front face and transmission electrode cell geometries. Despite positive potential shifts in oxidation and ECL peaks, attributed to the internal resistance of the PPFs that result from their nanoscale thickness, the PPFs display similar ECL activity to GC, including the low oxidation potential (LOP) observed for amine coreactants on hydrophobic electrodes. Reductive-oxidative ECL was obtained using the well-studied ECL luminophore Ru(bpy)(3)(2+), where the C-OTEs outperformed ITO because of electrochemical instability of ITO at very negative potentials. The C-OTEs are promising electrodes for ECL applications because they yield higher ECE, than ITO in both oxidative-reductive and reductive-oxidative ECL modes, are more stable in alkaline solutions, display a wide potential window of stability, and have tunable transparency for more efficient detection of ECL.