High color rendering index and chromatic stability of top‐emitting white organic light‐emitting diodes capped with a supplementary green color conversion layer

Abstract We have demonstrated high color rendering index (CRI) and chromatic stability of top‐emitting white organic light‐emitting diodes (TEWOLEDs) by capping a supplementary green color conversion layer (CCL) on the cathode of single blue emitter based TEWOLEDs. By employing CCLs, blue photon energy is absorbed and converted to green emission efficiently, resulting in an improvement of CRI from 72 to 86. We attribute the increased high CRI to the broadening of the out‐coupled spectrum and an appropriate intensity match among the three primary colors. Meanwhile, the TEWOLEDs show extremely high chromatic stability. The results indicate that this method provides a new avenue to improve the CRI of TEWOLEDs. magnified image (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)