A high productivity and speedy synthesis process for copper nanowires via an ethylenediamine-mediated method

Generally, there are two well-known synthetic approaches for copper nanowires (Cu NWs): ethylenediamine (EDA)-mediated synthesis and alkylamine-mediated synthesis. The alkylamine-mediated synthesis produces very high ratio nanowires but requires a special environment and long reaction times, while the EDA-mediated synthesis can be carried out under normal conditions and requires from 30 min to 1 h. However, the Cu NWs produced by this method have an average aspect ratio lower than 500 and are produced in low yield. In this paper, we present a modified EDA-mediated synthesis to improve the yield and reduce the synthesis time. In previous reported EDA-mediated synthesis, sodium hydroxide (NaOH) was used as a pH adjusting element and the reaction was performed at high temperature. By replacing NaOH with potassium hydroxide (KOH) and cooling down the temperature of reaction to room temperature, the synthesis time was reduced to 15 min as well as the productivity of high aspect ratio Cu NWs was increased notably to 80%. Furthermore, the transparent electrodes which were fabricated based on the as-synthesized Cu NWs, exhibited high performance, such as 23.5 X/sq of sheet resistance and 81% of transmittance at k = 550 nm.