Blue light-emitting diodes based on coronene-doped polymers

The photoluminescent (PL) and electroluminescent (EL) properties of coronen e crystalline film, as well as the electrochemical oxidation behavior, were investigated. It was found that coronene can be used as a good hole-transp orting and light-emitting material. Coronene was doped into the hole-transp orting polymer poly (N-vinylcarbazole) (PVK), the obtained blends were used as emitting layers for the fabrication of blue light-emitting diodes (LEDs ). The double-layer device using 2,5-bis (5'-tert-butyl-2-benzoxazolyl) thi ophene (BBOT) as an electro-transporting layer exhibited better performance than single-layer device made of blend only. The working parameters of dou ble-layer device include the turn-on voltage of 3.7 V, maximum brightness o f 1700 cd/m(2), peak emission wavelength at 453 nm, and external efficiency of 0.8%. (C) 1999 Elsevier Science S.A. All rights reserved.