Determining absolute electrochemiluminescence efficiencies of two iridium complexes

Abstract

This work reports absolute electrochemiluminescence (ECL) quantum efficiencies (QEs) of two iridium(III) complexes, fac-Ir(ppy)3 (Ir-1) and [Ir(ppy)2(dtbubpy)]+ ([Ir-2]+) in annihilation and coreactant pathways. With potentiodynamic scans and potential pulsing, ECL mechanisms were investigated by means of ECL-voltage curves, ECL-time curves and ECL spectroscopy. It was demonstrated that the radical stability and reactivity are the two main factors affecting ECL efficiencies in various processes, while intermediate charges have little effect. Considering the difference of such radical behaviors between [Ru(bpy)3]2+ and other luminophores, absolute ECL QEs are more applicable compared with the ones relative to [Ru(bpy)3]2+ as a standard.