Effect of Interlayer on White Phosphorescent Organic Light-emitting Devices

We demonstrated a novel white electrophosphorescent organic light emitting diodes (PHOLEDs), which structure was ITO/NPB (35 nm)/MCP (5 nm)/Firpic: MCP 10 wt% (15 nm)/ Ir (MDQ)2(acac): TPBI X wt% (2 nm)/Firpic:TPBI 10 wt% (10 nm)/TPBI (40 nm)/LiF (1 nm)/Al (100 nm). The luminescent properties were studied by inserting different doping concentration of the red emitting layer (Ir(MDQ)2(acac):TPBI) located between the double blue-emitting layers (D-BEML) to adjust the distribution of carriers and excitons. The results showed that the optimum performance of OLED was achieved when the doping concentration of Ir(MDQ)2(acac): TPBI red emitting layer is 5 wt%. Combining the D-BEML and the red emitting layer, we achieved a WOLEDs with peak efficiencies of 11.90 cd/A and CIE coordinates of (0.333, 0.334).