Evaluating the application of grating structure in an OLED for light extraction

摘要

The periodical microstructure, such as a grating, is thought to be able to enhance the extraction of light in the OLED. The emitting efficiency of OLEDs with gratings was studied, including applying grating in the interface of ITO/Glass, PPV/PEDOT, or both. Taking the coherent effect of the grating into account only, contrary to expected, the results do not show significant enhancement of light extraction. As known, the gratings do help coupling the guided light out the waveguide. However, its whole all effect is not sufficient large to result in an obvious increasing of the extraction efficiency. The significant enhancement reported in literatures might be contributed to the light diffusion, an incoherent process, of the microstructure. Thus, to enhance the light extraction, the periodicity of the microstructure could not be an important factor, if not at all. This could help to significantly relief the difficulty of forming microstructure to extract light in an OLED.