Quantum Efficiency of Electrochemiluminescence Generation by Tris(2,2’-bipyridine)ruthenium(II) and Tri-n-propylamine Revisited from a Kinetic Reaction Model

Graphical Electrochemiluminescence quantum efficiency (ECL-QE) : ECL-QE of Ru(bpy) 3 2+ /TPrA system was calculated in terms of a kinetic reaction model, which could reveal the root cause of ECL-QE change and could potentially be used as a criterion of selecting efficient luminophores and analytical conditions. Electrochemiluminescence quantum efficiency (ECL-QE) is an important parameter to evaluate the energy conversion ability of luminophores and analytical sensitivity of corresponding ECL systems. Herein, taking tris(2,2’-bipyridine)ruthenium(II) (Ru(bpy) 3 2+ ) and tri- n -propylamine (TPrA) coreactant system as an example, the ECL-QE was evaluated in terms of a kinetic reaction model, in which Ru(bpy) 3 3+ was considered to be the key intermediate in a reaction scheme consisting of competitive oxidative reduction and catalytic reaction routes. It was calculated as the product of electrochemical excitation efficiency ( η ex ) and light emission efficiency (i. e., photoluminescence quantum yield, PLQY). We used finite element simulations to examine the variation of η ex with the electrode material, applied potential, concentration and distance from the electrode surface. η ex was found to be largely determined by the electrochemical oxidation rate of TPrA that varied by several orders of magnitude with the electrode material. The estimation of ECL-QE helped in selecting the appropriate conditions for efficient ECL generation and sensitive analysis.