Benzotriazole-Functionalized Ionic Liquid and Superwettability-Assisted Transfer Enable Air-Stable, Large-Area Copper...

Copper nanowires (CuNWs) are promising for flexible transparent electrodes but suffer from lack of effective strategies to inhibit the oxidation-induced conductivity degradation, especially during large-area electrode preparation. Herein, a benzotriazole-functionalized ionic liquid ([BTAMMIM]TFSI) is introduced as an antioxidant layer to protect the CuNWs networks. Remarkably, the sheet resistance of the protected electrodes increases by only 0.54% compared to bare CuNWs after 60-day air exposure. Density functional theory (DFT) calculations and experiments reveal that the benzotriazole-functionalized cations and [TFSI] anions synergistically coordinate with copper, enabling exceptional oxidation resistance. By integrating with superwettability-assisted interfacial transfer strategy, large-area CuNWs@[BTAMMIM]TFSI composite electrodes (40 × 25 cm²) are fabricated with 37.2 Ω sq^-1 sheet resistance and 88.2% transmittance (550 nm). The electrodes maintain performance under acidic/alkaline conditions (pH 3/13) and high humidity (85% RH) at 85 °C. A demonstrated flexible smart window exhibits high transmittance modulation (6.1%-68.2%), fast response (< 0.2 s) and long-term stability, highlighting their potential in flexible optoelectronics.