Plasma Cleaning and Self-Limited Welding of Silver Nanowire Films for Flexible Transparent Conductors

Silver nanowire (Ag NW) films are the promising next-generation flexible, transparent conductors, but their transport properties are greatly deteriorated by the insulating polyvinylpyrrolidone (PVP) layer wrapping on the Ag NWs. Herein, we report a plasma treatment strategy to completely remove the PVP layer and meanwhile limitedly weld the Ag NW film at the NW/NW junctions to improve the film's carrier transport properties while not affecting its transparency. Particularly, we found that the dual functions of the removal of the PVP layer and self-limited welding can be achieved for a series of commonly used plasmas, e.g., O-2 plasma, H-2-Ar plasma (1:9 in volume), and N-2 plasma. Theoretical simulations reveal that the self-limited welding is caused by the focusing of light (emitted during plasma generation) at the NW/NW junctions, which thermally activates silver atoms and drives recrystallization therein. With a cleaned surface and welded nature, the plasma-treated Ag NW film shows largely improved conductivity and high flexibility, greatly facilitating its application as a high-performance flexible transparent heater (cycling stability, >40 cycles of heating/cooling; temperature rising rate, 112 degrees C within 30 s at 8 V). Moreover, the plasma-treated Ag NW can also serve as a basic electrode for a stacked electron-only device of Ag NW film/8-hydroxyquinoline/Ag electrode, improving its current collection efficiency by 5.47 times. These results suggest that plasma treatment can greatly benefit the applications of Ag NW film.