Copper Nanowires as Fully Transparent Conductive Electrodes

Abstract

In pondering of new promising transparent conductors to replace the cost rising tin-doped indium oxide (ITO), metal nanowires have been widely concerned. Herein, we demonstrate an approach for successful synthesis of long and fine Cu nanowires (NWs) through a novel catalytic scheme involving nickel ions. Such Cu NWs in high aspect ratio (diameter of 16.2 ± 2 nm and length up to 40 μm) provide long distance for electron transport and, meanwhile, large space for light transmission. Transparent electrodes fabricated using the Cu NW ink achieve a low sheet resistance of 1.4 Ohm/sq at 14% transmittance and a high transparency of 93.1% at 51.5 Ohm/sq. The flexibility and stability were tested with 100-timebending by 180°and no resistance change occurred. Ohmic contact was achieved to the p- and n-GaN on blue light emitting diode chip and bright electroluminescence from the front face confirmed the excellent transparency.

The Roles of Hydrazine and Ethylenediamine in Wet Synthesis of Cu Nanowire

“…It was smaller than that was obtained in Ref. [12] and [14], however, we believe that this number can still be increased using a correct ratio of hydrazine and EDA.…”

“…However, this process might still be considered as a long time one. A further study was carried by another group using hydrazine as the reductor but by replacing ethylenediamine with oleylamine solution through a Ni(acac) 2 catalytic formation process in searching the effective process [14]. Using ethylenediamine tetraacetic acid (EDTA) as capping agent and Na OH together with supercritical water, the synthesis of CuNW was carried successfully from a precursor copper sulfate [8].…”

Nanomaterial-based stretchable and transparent electrodes

“…In this regard, Cu nanowires (CuNWs) have been considered a promising alternative due to their remarkable intrinsic conductivity (only 6% less than that of Ag) and low cost (100 times cheaper than Ag) [35][36][37]. Figure 2(a) shows that the fundamental characteristics of CuNWs have reached the level of those of AgNWs [37,38]. In addition, Ag atoms easily move under a high current density through the phenomenon known as electromigration, whereas Cu has higher resistance against electromigration than Ag, as shown in Figure 2(b).…”

Deformable and Transparent Ionic and Electronic Conductors for Soft Energy Devices

“…Cu NW networks have exhibited comparable conductivity and transparency to Ag NWs, e.g., 51.5 Ω sq −1 at 93.1% T [123] and 100 Ω sq −1 at 95% T. [124] Ultralong Cu nanofibers [86] and NWs [87] were introduced in a manner similar to Ag NWs for better conductance with fewer junctions. Cu nanofibers with a high aspect ratio (≈100 000) were fabricated and achieved a low sheet resistance of 50 Ω sq −1 at 90% T (Figure 3g).…”