Absolute Electrochemiluminescence Efficiency Quantification Strategy Exemplified with Ru(bpy)₃²⁺ in the Annihilation Pathway

Abstract

This work presents a thorough guide to procedures for absolute electrochemiluminescence (ECL) quantum efficiency (Φ_ECL) measurements, which if employed effectively should raise the research impact of ECL studies for any luminophore. Absolute measurements are not currently employed in ECL research. Instead, ECL efficiencies have been determined relative to Ru(bpy)₃²⁺ under similar conditions, regardless of whether the conditions are favorable for Ru(bpy)₃²⁺ emissions or not. In fact, the most cited Ru(bpy)₃²⁺ Φ_ECL is from the pioneering work by the Bard research group in 1973 by means of a rotating ring-disk electrode revolving at 52 rotations per second measured with a silicon photodiode. Our presented technique uses a common disk electrode, spectrometer, and photomultiplier tube to measure the Φ_ECL. The more common light detection hardware and electrodes combined with an in-depth calculation walkthrough will provide ECL researchers the necessary tools to implement Φ_ECL measurement procedures in their own laboratories. Following a facile instrument setup and calculation, a systematic study of Ru(bpy)₃²⁺ Φ_ECL finds comparable results to those performed by Bard and co-workers.