Integration of graphene electrode on cylindrical substrates by thin film rolling method

Abstract

1) a thin film is floated on water surface, 2) the floating thin film is contacted with a cylindrical substrate, and 3) the cylindrical substrate is rotated, then the thin film is rolled up on the substrate through van der Waals interactions. In order to investigate transfer mechanism, the adhesion forces between cylindrical substrate-film and film-water were quantitatively calculated by surface energy measurement and theoretical models. Moreover, a thin film rolling equipment was developed for precise control of substrate diameters and the number of rotations. As an application, the electroactive actuator was designed by integrating the graphene-gold composite electrode on nafion tube using thin film rolling method. In addition, we evaluated the flexibility and stretchability of graphene-gold electrode integrated devices, and investigated the effects of graphene on mechanical reliability. Furthermore, thin film laminated free-standing tubes, and rolling super-capacitors were demonstrated. The proposed thin film rolling method enables facile and cost-competitive transfer of thin films on cylindrical substrates. Therefore, we strongly believe that this method can be adopted to various research areas and opens up new markets.

The adoption of polymer substrates is inevitable in future electronic devices which require large deformable properties, such as wearable, stretchable, and flexible. Accordingly, various thin film deposition and transfer technologies have been studied in recent years. However, almost the whole previous technologies were limited to 2D planar substrate applications, and not suitable for utilizing 3D curved or cylindrical substrates. Here, we demonstrated a thin film rolling method that can transfer thin films on 3D cylindrical substrates. The thin film rolling method can be accomplished easily by following procedures