Improving efficiency roll-off in phosphorescent OLEDs by modifying the exciton lifetime.

Studies on phosphorescent organic light emitting devices (PhOLEDs) with phosphorescent emitter, fac-tris (2-phenylpyridine) iridium (Ir(ppy)(3)), show that the lifetime of triplet exciton is modified by surface plasmon coupling of Au nanoparticles (NPs). Interactions between the triplet exciton and gold (Au) nanoparticles (NPs) lead to a decrease in the exciton lifetime and result in the spontaneous emission decay rate of triplet exciton faster as the distance between the phosphorescent material and the Au NPs becomes smaller. This interaction reduces the efficiency roll-off of Au NPs containing device. These results provide new guides for device design to improve efficiency performance.