Nano-arrayed OLEDs: enhanced outcoupling efficiency and suppressed efficiency roll-off

Abstract

Organic light-emitting diodes (OLEDs) with an enhanced outcoupling efficiency and a suppressed efficiency roll-off were fabricated by inserting a nanosize pixel-defining layer (nPDL) that defines the OLED emission region as an array of nanoholes. The outcoupling efficiency of the nano-arrayed OLEDs was increased through the reduced surface plasmon polariton loss caused by the wavy diffraction grating at the metal-organic interface, and their efficiency roll-off was suppressed through the diffusive exciton outside the exciton-formation zone. As a result, the nano-arrayed OLEDs exhibited enhancements of 148.7% in the power efficiency and 137.0% in the external quantum efficiency at 1000 cd m(-2) compared with a reference device. Furthermore, the critical current density (J(0)) where the external quantum efficiency decreased to half of its initial value was improved by a factor of 2.5.