Improved turn-on times of light-emitting electrochemical cells

Electroluminescent devices from ionic transition metal complexes (iTMCs) are attractive candidates for display and lighting applications. A major limitation of application of iTMC devices is their turn-on times, which range from minutes to hours at 3V. We report novel ruthenium and iridium complexes with pendant triethylammonium groups bonded to the ligands with methylene units of various lengths. These materials lead to devices with turn-on times at 3V as short as 2.5min for the iridium complexes and as low as 5s for the ruthenium complexes.