Disordered Nano‐Hemisphere Molybdenum Trioxide for Enhanced Light Out‐Coupling in Organic Light‐Emitting Diodes

Abstract

A 2D‐array scattering layer composed of disordered, wavelength‐sized molybdenum trioxide (MoO3) nano‐hemispheres that are introduced into existing organic light‐emitting diodes (OLEDs) can maximize light out‐coupling. This MoO3 nano‐hemisphere scattering layer (M‐NSL) obtained by in situ annealing‐spraying is investigated in depth based on considerations of larger refractive index, higher transparency, and internal light scattering. With the simulation of finite‐difference time‐domain, M‐NSL can effectively reduce the optical loss among the structural layers caused by the mismatch of refractive indexes is observed and induce strong diffuse transmission, which reduces the total internal reflection in the substrate, thus improving light out‐coupling. The power efficiency and external quantum efficiency of the device with M‐NSL demonstrated performance metrics of 139.5 lm W−1 power efficiency and 47.5% external quantum efficiency at 1000 cd m−2, which increased by 82.4% and 64.5%, respectively, compared with the control device without M‐NSL. Potentially, the scheme will be easy to implement and incorporate into existing semiconductor device technologies, and it can be used separately or in conjunction with other methods to mitigate the critical angle loss in OLEDs.