High efficiency white organic light-emitting diodes

The light emitting diodes with the structure of ITO/m-MTDATA(20 nm)/NPB(10 nm)/CBP BCzVBi (x, nm, 10%)/CBP(3 nm)/CBP: Ir(ppy)3: DCJTB(10 nm, 8 and 1%)/Bphen(30 nm)/Cs2CO3: Ag2O (2 nm, 20%)/Al (100 nm) employing phosphorescence sensitization and fluorescence doping, were manufactured. The performance of the devices was studied by adjusting the thickness of fluorescence dopant layer (x = 15, 20, 25, and 30). The best performance was achieved when its thickness was 25 nm. The device has the maximum luminance of 20260 cd/m2 at applied voltage of 14 V and the maximum current efficiency of 11.70 cd/A at 7 V. The device displays a continuous change of color from yellow to white. The CIE coordinates change from (0.49, 0.48) to (0.32, 0.39) when the driving voltage is varied from 5 to 15 V.