Suppression of viewing angle dependence of TEOLED devices with internal nano-wrinkle structure

摘要： In order to suppress the viewing angle dependence of top emission organic emitting diodes (TEOLEDs) with strong microcavity effect, we introduced randomly distributed nano-wrinkle structure beneath highly reflective anode. By applying such nano-wrinkle pattern, viewing angle dependence and color shift could be improved compared with that without nano-structure [e.g. Δ(u’, v’): 0.077 → 0.025]. However, current efficiency reduced more than half. To compensate this problem, we additionally introduced index matching epoxy filler between encapsulation glass and TEOLED device. By this approach, current efficiency drop of device with nano-wrinkle structure could be improved. For example, the efficiency dropped by 7.7% when we filled the epoxy filler between capping layer and glass lid while, it decreased by 30.8% if we don’t use epoxy filler. We found that index matching helps to extract more light confined inside TEOLED, so device performance degradation could be minimized. In addition, when we attached a circular polarizer film to these devices, depolarization was observed in most cases, but we were able to achieve a perfect black state from the devices with nano-wrinkle structure underneath reflective anode.