Simultaneously enhanced performances of flexible CuNW networks by covering ATO layer for polymer solar cells

Solution-synthesized copper nanowires (CuNWs) have been proposed to replace indium tin oxide (ITO) as transparent conductive electrodes (TCEs) due to the abundance of Cu and low production cost. However, there has to date been no way to simultaneously improve the transparency, conductivity, adhesiveness, chemical and thermal stabilities of CuNWs that critically limit their applications. In this work, we introduce a Sb doped SnO2 (ATO) covering layer to simultaneously improve the performances of CuNWs on polyethylene terephthalate (PET) substrate. The CuNWs form a random percolating network protected by ATO layer. The unique structural features of our ATO/CuNWs composite films allow for a novel TCE with outstanding conductivity (sheet resistance: 9.6 Ω/sq), high transmittance (>85% at 550 nm), strong adhesiveness, unprecedented excellent chemical and thermal stability, as well as flexibility, these performances are far superior to other CuNW based TCEs and comparable with the expensive silver NW based TCEs. Moreover, the composites show a good stability to resist long-term storage, flushing damage, and ultrasonication. Polymer solar cells (PSCs) using ATO/CuNWs based TCEs exhibit a power conversion efficiency (PCE) of 6.39%, which is higher than that of PSCs using ITO (5.87%), which illustrate a promising alternative to traditional TCEs for flexible electronic devices.