Abstract
White phosphorescent polymer light emitting diodes (WPhPLEDs) with a glass/ITO/ PEDOT:PSS/PVK:FCNIrpic:Ir(mppy)3:Ir(piq)3/TPBI/LiF/Al structure were fabricated to investigate the effects of the doping concentration of Ir(piq)3 emission materials. The PVK, FCNIrpic, Ir(mppy)3 and Ir(piq)3 organic materials as the host and guest emission materials were spin coated at various concentrations of Ir(piq)3 ranging from 0.1 to 0.4 wt%. With increasing the concentration of Ir(piq)3 from 0.1 to 0.3 wt%, the luminance was increased clearly. However, the luminance was decreased by 6400 cd/m2 when the Ir(piq)3 doping concentration reached 0.4 wt%. The drop in luminance is caused by the quenching effect at a high doping concentration. The maximum luminance and current efficiency were 9486 cd/m2 and 2.23 cd/A, respectively for WPhPLED with 0.3 wt% of Ir(piq)3. The average CIE color coordinates for the WPhPLED with 0.2 wt% of Ir(piq)3 were about (x=0.32, y=0.33) at 12V, showing a good white emission color.
Acknowledgment
The present research was conducted by the research fund of Dankook University in 2012.