Improvement of Efficiency and Brightness of Red Organic Light-Emitting Devices Using Double-Quantum-Well Configuration

We present red double-quantum-well organic light-emitting devices (DQW-OLEDs), in which N,N-bis-(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyo-4,4'-diamine (NPB) is used as potential barriers and hole transport layer, 4-(dicyanome-thylene)-2-t-butyl-6-(1,1,7,7-thtramethyljulolidyl-9-enyl)-4H-pyran (DCJTB) doped tris (8-hydroxyquinoline) aluminium (Alq₃) as potential wells and emitter, undoped Alq₃ as electron transport layer, respectively. The turn-on voltage is about 4 V. The maximum brightness and electroluminescent (EL) efficiency of the DQW device can reach 5916 cd m^-2 at 16 V and 2.85 cd A^-1 at 7 V, respectively. In addition, the EL efficiency of the DQW device is relatively independent of the drive voltage in the range from 5 V to 16 V.