Performance enhancement of large-area graphene–polymer flexible transparent conductive films fabricated by ultrasonic substrate vibration-assisted rod coating

The graphene/PEDOT:PSS composite thin films (GCFs) are promising candidates for transparent conductive electrodes in low-cost flexible thin-film devices, which can be applied in portable and flexible electronic devices such as organic light-emitting diodes and organic solar cells. In this work, to improve the film characteristics, we impose ultrasonic vibration on the substrate, and therefore the wet coating, during the rod-coating preparation process of the GCFs, and study the effect of vibration power. The 5 × 5 cm² thin films prepared on flexible polyethylene terephthalate with ultrasonic vibration imposed on the substrate of wet films demonstrate improved conductivity and reduced thickness. Ninefold enhancement in charge carrier concentration is observed when ultrasonic vibration is applied. The improved performance is ascribed to the eliminated pores in films, and rearrangement of graphene in the polymer network, brought about by nanometer-scale-amplitude ultrasonic vibrations. The electrical property of flexible films is demonstrated to be stable after multiple cycles of bending.