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

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.