Extremely efficient electrochemiluminescence systems based on tris(2-phenylpyridine)iridium(iii)

Abstract

Electron transfer generation of the excited tris(2-phenylpyridine)iridium(III) ³*Ir(ppy)₃ has been studied in acetonitrile–dioxane (1 ∶ 1) solutions containing 0.1 M (n-C₄H₉)₄NPF₆ as the supporting electrolyte. A triple-potential-step technique was used to create electrochemiluminescence (ECL) emission by annihilation of the electrochemically generated ions Ir(ppy)₃⁺ + Ir(ppy)₃⁻ (single ECL system) as well as Ir(ppy)₃⁺ + A⁻ (mixed ECL systems with the radical anions of aromatic nitriles and ketones). Very high ECL emission efficiencies (up to 0.67, close to the excited ³*Ir(ppy)₃ luminescence yield of 0.75) have been found.