Direct formation of random wrinkle on emission surface for improved light out coupling and stable angular spectrum of white organic light emitting diodes

Abstract To enhance the light out coupling and stabilize the angular spectrum of white organic light emitting diodes (WOLEDs), we formed a randomly distributed corrugation directly on the external glass surface. Using a metallic master, which was prepared using laser ablation, we have imprinted the corrugation pattern directly on the glass surface. Our method yields 32% increase in the external quantum efficiency, widened luminance distribution and low angular spectra variation. Considering WOLED as a lighting source, this feature is particularly appealing. Besides the implications of the spectrally stable efficient WOLEDs through random corrugation, our work suggests a new structural approach for various light applications in which efficiency and spectral stability matter.