White Organic Light-emitting Diode Using Nano-double Ultrathin Carrier-trapping Materials in Performance Stability

The structure of indium tin oxide (ITO) (100 nm)/molybdenum trioxide (MoO 3 ) (15 nm)/ N,N0-bis-(1-naphthyl)-N,N0-biphenyl-1,10-biphenyl-4,40-diamine (NPB) (40 nm)/4,4'-bis(2,2diphenylvinyl)-1,1'-biphenyl (DPVBi) (10 nm)/5,6,11,12-tetraphenylnaphthacene (rubrene) (0.2 nm)/DPVBi (24 nm)/rubrene (0.2 nm)/DPVBi (6 nm)/4,7-diphenyl-1,10-phenanthroline (BPhen):cesium carbonate (Cs 2 Co 3 ) (10 nm)/Mg:Ag (6 nm)/Al (120 nm) white organic lightemitting diode (WOLED) with high color purity and stability was fabricated. The function of the multiple-ultrathin material (MUTM), such as rubrene, is as the yellow light-emitting layer and trapping layer. The results show that the MUTM has excellent carrier capture effect, resulting in high color stability of the device at different applied voltages. The Commission Internationale De L'Eclairage (CIE) coordinate of this device at 3-7 V shows a few displacements and a very slight variation of (0.01, 0.01). The maximum brightness of 9986 cd/m 2 and CIE coordinates of (0.346, 0.339) are obtained at 7 V. The enhanced performance of the device may result from the direct charge trapping in MUTM, and it can be found in the electroluminescence (EL) process.