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

Electron transfer generation of the excited tris(2-phenylpyridine) iridium(III) Ir-3*(ppy)(3) has been studied in acetonitrile-dioxane (1:1) solutions containing 0.1 M (n-C4H9)(4)NPF6 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 Ir-3*(ppy)(3) luminescence yield of 0.75) have been found.