Viewing-angle independence of white emission from microcavity top-emitting organic light-emitting devices with periodically and gradually changed cavity length

We demonstrate a broad-bandwidth and viewing-angle independent white emission from top-emitting organic light-emitting devices (TOLEDs) by integrating a microstructured cavity with a periodically and gradually changed cavity length. The results indicate that the microstructured cavity can resolve the viewing angle-dependence effect persisted in the conventional planar TOLEDs. The viewing-angle independence in both broad-band emission spectra and Commision Internationale de L'Eclairage coordinates are obtained. Moreover, the microstructured white TOLEDs show comparable luminance and current efficiency to that of the planar TOLEDs. (C) 2013 Elsevier B. V. All rights reserved.