Realization of high efficiency orange and white organic light emitting diodes by introducing an ultra-thin undoped orange emitting layer

Abstract

In this paper, we report on high efficiency orange and white organic light emitting diodes (OLEDs) by introducing an ultra-thin undoped orange emitting layer (less than 1 nm) adjacent to the electron-transporting layer. The orange OLEDs showed a high external quantum efficiency (EQE) of 16.4% at 1000 cd/m2, and the resulting four-color white OLEDs emitted an EQE of 15.5% and a maximum color render index (CRI) of 87 at luminance of 1000 cd/m2. Further analysis on the EQE of the white OLEDs makes us confident that this design has the possibility to realize 100% internal quantum efficiency (IQE) by using much more highly efficient phosphorescent emitters.