Self-assembled growing ultrathin Ag@NiO core-shell nanowires for stable freestanding transparent conductive colorless polyimide nanomembranes

Among the alternatives to indium tin oxide, silver nanowire (Ag NW) networks have received widespread attention for their superior optoelectronic properties. However, the rapid degradation of Ag under ambient conditions essentially limits its practical application. In this paper, we innovatively propose the synthesis of ultrathin Ag@NiO core-shell nanowires by a simple and low-cost solution method to enhance the thermal, electrical and chemical stability of NWs. The Ni2+ and Ag atoms undergo a redox reaction in the presence of water, and a reasonable mechanism of NiO formation is proposed. The Ag@NiO NW networks show low sheet resistance of 12.1 Ω/sq. and high transmittance of 84.8%. The encapsulation of the NiO shell can significantly improve their resistance to heat (85 °C) and humidity (85%) for 96 h, and NaCl solution for 200 min, while their resistance remains similar to the original values. The stable free-standing transparent conductive nanomembrane (FTCNM), consisting of an Ag@NiO NW nanowire network embedded in an ultrathin colorless polyimide, is fabricated by all-solution-process, which is perfectly conformal with human skin. We also present a skin-attachable capacitive nanomembrane sensor based on the FTCNM, the sensor shows remarkable pressure-sensing capability.