Ag Nanowires via Solution Process and Localized Reduction of Ag Ions for Next-Generation Transparent Conductive Electrodes

Metal nanowires are promising next-generation transparent conductive electrodes for application in optoelectronic devices in the field of printed electronics. Because metal nanowire networks have high contact resistance, welding at the junction between nanowires via heat treatment must be performed to improve the conductivity of the network. However, in the annealing step of metal nanowire production, problems such as thermal breakdown due to Rayleigh instability frequently occur. In addition, the conductivity of metal nanowires can be improved via the use of conductive nanomaterials. However, many coating materials can also reduce the transmittance. In this study, we describe a method for locally reducing Ag ions at the surfaces or junctions of Ag nanowires through Joule heating without optical loss. Herein, an organometallic precursor solution containing Ag ions functionalized with amino groups (-NH₂) is selectively adhered onto the metal. The attached Ag ions were reduced without any reducing agent, and the electrode conductivity was enhanced via lowering of contact resistance between the Ag nanowires without optical loss. The localized reduced (LR) AgNW electrode exhibited a sheet resistance of 14.4 ω/sq and a transmittance of 93.04%, which are improved compared to those reported in previous studies. The LR-AgNW could be easily transferred to a flexible plastic film substrate, which was successfully embedded and applied to a light-emitting device that exhibited steady light-emitting performance even when bent. The flexible LR-AgNW film is expected to be useful in various optoelectronic devices such as solar cells, organic light-emitting diodes, touch screens, and wearable devices.