Electroluminescence of co-ligated aluminum complex of α-pyridoin and 8-hydroxyquinoline

Most of organic light-emitting diodes (OLEDs) are based on tris(8-hydroxyquinolate)aluminum (Alq3), since the Alq3 has excellent abilities of electron transport and light emission. We have attempted to employ 8-hydroxyquinoline as co-ligand for enhancement of electron transport abilities so that the electroluminescent (EL) devices do not need additional electron transport layer. The aluminum complex (PAlQ) of 8-hydroxyquinoline and α-pyridoin was synthesized. The structure of the PAlQ was elucidated by FT-IR, UV–Vis and XPS. The PAlQ complex showed thermal stability up to 350 °C under nitrogen flow by TGA. The photoluminescence (PL) of the thin film was measured from cast film of the Al complex on quartz substrate. The EL devices were fabricated by vacuum deposition. The devices having the structure of ITO/TPD/PAlQ/Al were studied, where N,N-bis(3-methylphenyl)-N,N′-diphenyl-benzidine (TPD) was used as a hole transporting layer.