Copper nanowires as alternative flexible transparent electrodes for organic solar cells

Abstract

Copper nanowires (CuNWs) were synthesized using hydrothermal method and deposited onto flexible polymer substrates to make films acting as electrodes for organic solar cells (OSCs). Substrates used were polycarbonate (PC), polyethylene naphthalate (PEN), polyethersulfone (PES), and polyethylene terephthalate (PET). Aluminium and gallium doped ZnO nanoflakes (AZO and GZO-NFs) were coated onto CuNWs to act as a protective layer against oxidation. X-ray diffraction (XRD) confirmed formation of CuNWs, AZO and GZO-NFs. Scanning electron microscope (SEM) showed long and smooth CuNWs with average diameter of 112.82 ± 1.2 nm and length of over 50 μm. PET substrate showed ~88.64% light transmittance, while PC showed ~87.93%, PES (~85.78%) and PEN (~81.78%). Upon coating CuNWs, transmittance was slightly low indicating minimum influence on the electrodes’ light transmission. From atomic force microscopy (AFM) results, CuNWs on PEN substrate showed lower roughness value of ~46.35 nm. Tensile strength results showed that PET substrate would be the optimal choice due to better flexibility and mechanical strength.