Effects of Charge Balance and Exciton Confinement on the Operational Lifetime of Blue Phosphorescent Organic Light-Emitting Diodes

For 15 years, the rapid degradation of luminance over time has rendered blue phosphorescent light emitting diodes (PHOLEDs) too short-lived for many practical applications. To date, studies have concentrated on the degradation of the emitting materials, yet not the many other parts of these devices. The authors develop a method to measure charge and exciton leakage directly over time, and find that these effects are n00exo00ext responsible for PHOLED degradation---an important revelation that shifts our attention toward the actual sources of failure.