High initial conductivity and oxidation resistance of copper nanowire films <i>via</i> depositing oxalic acid

Transparent conductive films based on copper nanowires (Cu NWs) have attracted extensive attention due to their cost-effectiveness. However, the inferior conductivity of Cu NWs compared to silver nanowires (Ag NWs) and the significant room temperature oxidation behavior have limited their widespread application and versatility. In this study, we present OA-Cu NW flexible transparent conductive films (FTCFs), which exhibit higher initial electrical performance and room temperature oxidation resistance. Initially, we synthesized high-purity Cu NWs and established a uniformly distributed Cu NW network on a PET substrate. Subsequently, post-treatment was carried out using a 0.1 M oxalic acid (OA) solution to immobilize oxalic acid on the Cu NWs. The resulting OA-Cu NW FTCFs show improved electrical properties compared to the original Cu NW FTCFs, with an optimal enhancement of 25%. The film demonstrated excellent room temperature oxidation resistance, showing minimal sheet resistance growth after 70 days of air exposure. Furthermore, the OA-Cu NW FTCFs exhibited good flexibility, as indicated by minimal changes in optoelectronic performance after a rigorous bend test of 10 000 cycles. The OA treatment not only effectively enhanced the performance of Cu NW FTCFs, but also circumvented high energy consumption and the selection of rare metal materials, thereby reducing the overall cost. As a result, the potential for large-scale production and application of Cu NW films is enhanced.