Optimizing blue iridium complex and orange-red osmium complex doping concentrations to improve phosphorescent white organic light emitting diodes

Abstract

The effect of the phosphor doping concentration on the optoelectronic characteristics of white phosphorescence organic light emitting diodes (PHOLEDs) was studied. A high efficiency white PHOLED was achieved using the unique efficiency properties of the red-emitting Osmium complex ([fptz = 3-trifluoromethyl-5-(2-pyridyl)-1,2,4-triazole, PPh2Me = phosphineligand]; Os(fptz) 2(PPh 2Me) 2) combined with a well known efficient blue-emitting Iridium complex (bis[(4,6-difluorophenyl)-pyridinate-N,C2′; FIrpic]). The results demonstrate that with 2 wt% Os(fptz) 2(PPh 2Me) 2 co-doped into the blue-emitting layer (10 wt% FIrpic doped into the host), the device can achieve a luminance efficiency of up to 40.4 cd/A (25.6 lm/W) with a good corresponding CIE coordinate (0.39, 0.40). The doping concentrations of the red-emitting and blue-emitting phosphors were adjusted to obtain a pure white light with a CIE coordinate of (0.368, 0.366). A high efficiency white PHOLED was achieved by optimizing the doping concentration of the red-emitting and blue-emitting complexes.