Effect of Solvents on the Quantum Efficiency of Rubrene Electrogenerated Chemiluminescence

Abstract

A simple and precise method for measuring the efficiency of electrogenerated chemiluminescence (e.g.c.l.) in terms of photons/(Faradaic electron)(Φ_coul) is described and applied to rubrene e.g.c.l. A symmetrical square wave potential having a frequency of 20–1000 Hz was employed to produce the e.g.c.l. The electrogenerated ion radicals were shown to be completely stable at these frequencies; consequently, Φ_coul was determined in the absence of side reactions. Change of solvent from N,N-dimethylformamide (DMF) to equivolume benzene-DMF resulted in an increase in Φ_coul from 0.67 to 1.21% at 20 Hz. Φ_coul decreased with increasing frequency. Varying the electrolyte (tetra-n-butylammonium perchlorate, TBAP) concentration did not affect Φ_coul.