White Organic Light-Emitting Diodes Using Red-Fluorescent and Blue-Phosphorescent Emitters with Inducer Layer

We investigated the electroluminescent characteristics of new structural white organic light-emitting diodes (WOLEDs) including a double emitting layer with iridium(III) bis[(4,6-di-fluorophenyl)-pyridinato-N,C2] picolinate (FIrpic) and 4-(dicyanomethy lene)-2-t-butyl-6(1,1,7,7-tetramethyliul-olidyl-9-enyl)-4H-pyran (DCJTB) as blue phosphorrescent dopant and red fluorescent dopant according to changing thickness of pure N,N '-dicarbazoly-3,5-benzene (mCP) as inducer layer. The optimized WOLED device with structure of indium tin oxide (ITO)/N,N '-bis(1-naphy1)-N,N '-dipheny1-1,1'-bipheny1-4-4'-diamine (NPB) (70 nm)/mCP doped with 10% FIrpic (20 nm)/mCP (3 nm)/tris(8-hydroxyquinolino)aluminum (Alq3) doped with 0.4% DCJTB (8 nm)/Alq3 (30 nm)/lithium quinolate (Liq) (2 nm)/aluminum (Al) (100 nm) shows the Commission Internationale de l'Eclairage, International Commission on Illumination (CIEx,y) coordinates of (0.34, 0.38) at a current density of 56.8 mA/cm2 and only varied within ±(0.01,0.02) over the brightness range from 10 to 6000 cd/m2.