Metal nanowire (NW) networks have the highest performance of any solution-coatable alternative to ITO, but there is as yet no published process for producing NW films with optoelectronic performance that exceeds that of ITO. Here, we demonstrate a process for the synthesis and purification of Ag NWs that, when coated from an ink to create a transparent conducting film, exhibit properties that exceed that of ITO. The diameter, and thus optoelectronic performance, of Ag NWs produced by a polyol synthesis can be controlled by adjusting the concentration of bromide. Ag NWs with diameters of 20 nm and aspect ratios up to 2000 were obtained by adding 2.2 mM NaBr to a Ag NW synthesis, but these NWs were contaminated by nanoparticles. Selective precipitation was used to purify the NWs, resulting in a transmittance improvement as large as 4%. At 130.0 Ω sq(-1), the transmittance of the purified Ag NW film was 99.1%.
Keywords: selective precipitation; silver nanowires; sodium bromide; transparent conductor.