Photoluminescence and electroluminescence mechanism on a novel complex Eu(o-BBA)3(phen)

A novel rare-earth complex of europium ion with 2-benzoylbenzoic acid and 1,10-phenathroline (Eu(o-BBA)3(phen), o-BBA=2-benzoylbenzoic acid, phen=1,10-phenathroline) was synthesized, and used as a luminescent material for the first time. The Eu complex was blended with poly(N-vinylcarbazole) (PVK) and spin coated into films (noted as PVK:Eu films). Monolayer devices with the structure ITO/PVK:Eu/Al were fabricated and they emitted red light, which was characteristic of Eu3+ emission. The results showed that the mechanism for photoluminescence (PL) and electroluminescent (EL) was different. The PL was considered to be caused because of energy transfer and direct excitation of Eu(o-BBA)3(phen), while EL was mainly due to charge trapping.