Chemically Welding Silver Nanowires toward Transferable and Flexible Transparent Electrodes in Heaters and Double-Sided Perovskite Solar Cells

Silver nanowires (AgNWs) are important materials for flexible transparent electrodes (FTEs). However, the loose stacking of nanowire junctions greatly affects the electric conductivity across adjacent nanowires. Soldering can effectively reduce the wire-wire contact resistance of AgNWs by epitaxially depositing nanosolders at the junctions, but the process normally needs to be performed with high energy consumption. In this work, we proposed a simple room-temperature method to achieve precise welding of junctions by adjusting the wettability of the soldered precursor solution on the surfaces of AgNWs. The nanoscale welding at nanowire cross junctions forms efficient conductive networks. Furthermore, reduced graphene oxide (rGO) was used to improve the stability of FTEs by wrapping the rGO around the AgNW surface. The obtained FTE shows a figure-of-merit (FoM) of up to 439.3 (6.5 Ω/sq at a transmittance of 88%) and has significant bending stability and environmental and acidic stability. A flexible transparent heater was successfully constructed, which could reach up to 160 °C within a short response time (43 s) and exhibit excellent switching stability. When laminating this FTE onto half perovskite solar cells as the top electrodes, the obtained double-side devices achieved power conversion efficiencies as high as 16.15% and 13.91% from each side, pointing out a convenient method for fabricating double-sided photovoltaic devices.