S-1805/Ag/Au Hybrid Transparent Electrodes for ITO-free Flexible Organic Photovoltaics

We fabricated an S-1805/Ag/Au hybrid transparent electrode based on 4.4 nm ultrathin Au film, which exhibited a high transparency(T=78% at 550 nm), a low sheet resistance(R_s=70 Ω/sq), and an extremely smooth surface(roughness=0.37 nm). The three-dimensional(3D) island growth mode of 4.4 nm Au film was resisted by the chemical bonding effect of the nonconductive S-1805 film and the wetting behavior of 0.6 nm Ag layer. The S-1805/Ag/Au hybrid transparent electrodes were used as the replacement of ITO anodes in flexible organic photovoltaics(OPVs), and the S-1805/Ag/Au-based OPVs resulted in the similar power conversion efficiency compared to ITO-based devices. High flexibility and mechanical robustness were demonstrated in the ITO-free OPVs without obvious degeneration in device performance after over 2000 repeated bending cycles.