Wetting-Induced Fabrication of Graphene Hybrid with Conducting Polymers for High-Performance Flexible Transparent Electrodes

Graphene has attracted extensive attention for the supply of electrically conductive, optically transparent, and mechanical robust electrodes for flexible optoelectrical devices, as an alternative to commercial indium tin oxide, due to its superior mechanical, electrical, and optical properties. However, conventional chemical vapor deposition is impeded by harsh conditions and complicated processes, and it is still a challenge to fabricate high-performance graphene transparent electrode in a facile and scalable solution-processable route. Herein, a wetting-induced scalable solution-processable approach to fabricate graphene hybrid with conductive ionogel and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), i.e., graphene/ionogel@PEDOT:PSS (G/Ionogel@PEDOT:PSS), for high-performance flexible transparent electrode (FTE) is reported, achieving a low sheet resistance of 30 Ω sq-1 and a high transmittance of 88% at 550 nm. The as-fabricated trinary hybrid FTE as both transparent electrode and electrochromic layer is applied to a compact indium tin oxide (ITO)-free three-layered flexible electrochromic device, showing fast switching response, good electrochromic contrast, and reliable stability. Our work enables a scalable solution-processable approach for the generation of graphene-based FTE and functional devices.