Reflecting metagrating-enhanced thin-film organic light emitting devices

Abstract

Organic light emitting diodes can achieve close to unitary internal quantum efficiency; however, their external quantum efficiency is much lower due to losses within the device. Gradient metasurfaces and metagratings can be utilized to achieve substantial electromagnetic field manipulation and enhancement of the local density of photonic states, thereby improving the external quantum efficiency of organic light emitting devices. In this work, we show how suitably designed reflecting plasmonic metagratings can be potentially incorporated into a top-emitting organic light emitting device, resulting in large enhancement of light emissivity by effectively coupling out the light trapped in the waveguide modes. We describe how both periodic and quasiperiodic metagratings can be used to improve device performance. Electromagnetic simulations and measurements show that our metagratings greatly enhance the electromagnetic field intensity in the light emission layer, leading to increased emission normal to the plane of the layers (by up to a factor of 4.8) and suppression of light trapping typically lost into waveguide modes.