High-performance flexible transparent conductive films based on copper nanowires with electroplating welded junctions

Abstract

In pondering of new promising transparent conductors to replace the cost rising indium tin oxide (ITO), Cu nanowire (CuNW) films have been widely concerned, but both the adhesion and thermostability of CuNWs are very poor. In this paper, highly reliable copper nanowire transparent films on flexible polyethylene terephthalate (PET) substrates, with synchronously enhanced adhesion, improved thermostability and reduced resistivity, are prepared via electroplating welding at room temperature. The sheet resistance of the flexible welded CuNW films reduces from ~200 to ~30 Ω/sq at the transmittance of ~83%. Meanwhile, the sheet resistance does not show significant change after bending and taping test, suggesting a good adhesion of welded CuNW films to the PET substrate. Moreover, the flexible welded CuNW films show good stability to resist long-term storage and high temperature (150 °C). The thermal performance of the flexible welded CuNW films as visible transparent heaters via Joule heating is also assessed. Rapid response times (~30 s) at a low bias voltage (5.5 V) and good thermal resistance characteristics are found using measured thermal imaging data and thermochromic paint printed on top of the transparent heater. This simple, low-cost, and scalable CuNW electroplating welding technique provides an innovative approach for the preparation of next-generation flexible transparent electrodes for future optoelectronic devices.