Carrier transfer and luminescence characteristics of concentration-dependent phosphorescent Ir(ppy)3 doped CBP film.

Abstract: The carrier transfer and luminescence characteristic of concentration-dependent tris(2-phenylpyridine) iridium (Ir(ppy)3) doped in 4,4′-bis(carbazol-9-yl)-biphenyl (CBP) film of 40nm have been investigated. Based on the charge-only devices with different concentration of Ir(ppy)3:CBP, we have found that an increasing dopant concentration can facilitate hole transfer, whereas suppress electrons transfer reversely. The ratio of Ir(ppy)3 in CBP plays a significant role in energy transfer process. Results have shown that excess Ir(ppy)3 possessed a shortened fluorescence lifetime, indicating a concentration quenching effect in Ir(ppy)3:CBP film. The performance of the device decreased rapidly with increasing of doping concentration of Ir(ppy)3 in CBP. A high efficiency of 65.2cd/A with low efficiency roll-off phosphorescent OLED was achieved, in which 10wt%Ir(ppy)3 in CBP was light-emitting layer. [Copyright &y& Elsevier]