Electrodeposited\nSilver Nanowire Transparent Conducting\nElectrodes for Thin-Film Solar Cells

Abstract

Silver\nnanowire (AgNW) networks have demonstrated high optical\nand electrical properties, even better than those of indium tin oxide\nthin films, and are expected to be a next-generation transparent conducting\nelectrode (TCE). Enhanced electrical and optical properties are achieved\nwhen the diameter of the AgNWs in the network is fairly small, that\nis, typically less than 30 nm. However, when AgNWs with such small\ndiameters are used in the network, stability issues arise. One method\nto resolve the stability issues is to increase the diameter of the\nAgNWs, but the use of AgNWs with large diameters has the disadvantage\nof causing a rough surface morphology. In this work, we resolve all\nof the aforementioned issues with AgNW TCEs by the electrodeposition\nof Ag onto as-spin-coated thin AgNW TCEs. The electrodeposition of\nAg offers many advantages, including the precise adjustment of the\nAgNW diameter and wire-to-wire welding to improve the junction conductance\nwhile minimizing the increase in protrusion height because of the\noverlap of AgNWs upon increasing the diameter. In addition, Ag electrodeposition\non AgNW TCEs can provide higher conductance than that of as-spin-coated\nAgNW TCEs at the same transparency because of the reduced junction\nresistance, which generates a superior figure of merit. We applied\nthe electrodeposited (ED) AgNW network to a Cu­(In,Ga)­Se₂ thin-film solar cell and compared the device performance to a device\nwith a standard sputtered transparent conducting oxide (TCO). The\ncell fabricated by the electrodeposition method showed nearly equal\nperformance to that of a cell with the sputtered TCO. We expect that\nED AgNW networks can be used as high-performance and robust TCEs for\nvarious optoelectronic applications.