Ag nanowires: large-scale synthesis via a trace-salt-assisted solvothermal process and application in transparent electrodes

Ag nanowire (AgNW) films are receiving increasing attention as new transparent conductive films poised to replace indium tine oxide materials. However, coating of AgNW surfaces with polyvinylpyrrolidone (PVP) and other impurities during synthesis causes large contact resistance between the wires leading to low conductivities in the absence of additional treatments to fuse the overlapped AgNWs together. In the present work, we demonstrated a simple method to synthesize AgNWs by the reduction of AgNO₃ using PVP as the reducing agent assisted by trace amounts of salts in ethanol. The shape and yield of the AgNWs depended significantly on the concentrations of these trace salts and on reaction temperatures. The silver nanowires were about 5–20 μm in length and showed a uniform diameter of about 70 nm. A detailed growth mechanism of the AgNWs has been proposed on the basis of the observations recorded by varying these synthesis parameters. Further, the AgNWs were used to form a transparent film, which without any additional treatments showed a sheet resistance of 10.4 Ω/sq and a transmittance of 81.9 % at 550 nm. The performance of the films was attributed to the trace amounts of residual impurities on the surface of the AgNWs and to the special V-shaped morphology of the wires prepared with the solvothermal process.