Improving the bending resistance of double-layer printed flexible OLEDs with PEDOT: PSS-PEO composite HIL films

Abstract Flexible organic light-emitting diodes (OLEDs) are expected to have excellent device performance and mechanical robustness in many areas, such as wearable electronics and display devices. For the traditional materials of OLED anode, indium tin oxide (ITO) is undoubtedly the most mature transparent conductive electrode available. However, the brittle and rigid nature of ITO severely limit the development of flexible OLED (FOLED). In this work, a solution blending film consisting of poly (3,4 ethylenedioxythiophene): poly (styrene sulfonate) (PEDOT: PSS) and poly (ethylene oxide) (PEO) was used as a hybrid hole injection layer, where PEO polymer in the composite films can greatly improve the bending resistance of device. The printed FOLEDs doped with PEO exhibit impressive mechanical durability, maintaining 80.4% of its maximum external quantum efficiency after 1000 bends at a radius of curvature of 10 mm, compared to 46.3% for the counterpart without PEO doping.