Exploring Full Potential of Conducting Polymers for Enhancing Light Out-Coupling of OLEDs

Intriguingly, the conducting polymer PEDOT:PSS widely used in organic optoelectronics possesses a low optical refractive index (n) of ~1.5, significantly lower than those of ITO (n~1.8-2.1) and typical organic layers in OLEDs (n~1.7-1.8) and well matching that of typical OLED substrates (n~1.5 for general glass and plastic substrates). By well using the low-index property of PEDOT:PSS, various OLED structures having enhanced optical out-coupling and external quantum efficiencies can be implemented, giving an OLED external quantum efficiency of up to 62%.