Physical Strategy to Determine Absolute Electrochemiluminescence Quantum Efficiencies of Coreactant Systems Using a Photon-Counting Photomultiplier Device

In this work, using a photon-counting device, we outline our physical strategy to determine absolute electrochemiluminescence (or electrogenerated chemiluminescence, ECL) quantum efficiencies of coreactant systems in comparison with those in annihilation pathways. This absolute method addresses many of the issues with existing relative ECL efficiency measurements, including inconsistencies stemming from nonstandardized experimental conditions and incompatible luminophore systems. The absolute efficiency of the Ru(bpy)32+/tri-n-propylamine (TPrA) ECL coreactant system taken as an example was found to be 10.0 ± 1.1% for the first time using 10 Hz potential stepping at a TPrA concentration of 10 mM, which quantifies a 3-fold enhancement in efficiency compared to that in the annihilation pathway. Our physical and analytical technique is anticipated to be an immediate and impactful methodology in the expanding field of ECL research.