Ionogel/Copper Grid Composites for High-Performance, Ultra-Stable Flexible Transparent Electrodes

Production of high-performance and stable low-cost copper (Cu)-based flexible transparent electrodes (FTEs) is urgently needed for the development of new-generation flexible optoelectronic devices, but it still remains challenging. Herein, we developed a facile approach to fabricate high-performance, ultra-stable Cu grid (CuG)-based FTEs by UV lithography-assisted electroless deposition of patterned Cu on flexible polyethylene terephthalate (PET), which is then encapsulated by a thin poly(1-vinyl-3-ethylimidazolium bis(trifluoromethanesulfonyl)imide) (P[VEIM][NTf2]) ionogel layer to improve the mechanical flexibility and stability. The as-prepared composite FTE (ionogel/CuG@PET) exhibits a sheet resistance of 10.9 Ω sq–1 and optical transmittance of 90% at 550 nm. Introduction of the thin uniform P[VEIM][NTf2] ionogel nanofilm by virtue of the superwettability of the Cu layer endows the electrode with excellent mechanical flexibility and stability. This new high-performance Cu-based FTE should be an attractive alternative to indium tin oxide for practical optoelectrical applications.