PEDOT:PSS: CuNW-based transparent composite electrodes for high-performance and flexible organic photovoltaics under indoor lighting

Highly efficient and mechanically resilient transparent electrodes for indoor organic photovoltaics (OPVs) have attracted significant interest based on the emergence of the internet of things. In this study, transparent composite electrodes (TCEs) were fabricated by blending copper nanowires (CuNWs) with the conductive polymer poly (3, 4-ethylenedioxythiophene): poly (styrene-sulfonic acid) (PEDOT:PSS, PH1000). The optimized PEDOT:PSS: CuNW-based TCEs exhibited a high transmittance of approximately 90% at a wavelength of 460 nm, excellent flexibility with a change in resistance < 1.0%, and a smooth surface morphology with a root-mean-squared roughness value of 1.85 nm. As a result, the TCE-based flexible OPVs demonstrated an outstanding power conversion efficiency (PCE) of 17.6% ± 0.2% under 1000-lx light-emitting diode illumination, which is approximately 25% higher than that of OPVs with a reference indium-tin-oxide (ITO) electrode. Additionally, they exhibited exceptional mechanical durability while retaining 85% of their original PCE after bending 500 times with a bending radius of 3.8 mm. These results suggest that the excellent optoelectronic properties of the proposed TCEs should make them promising alternatives to costly ITO electrodes, thereby improving the economic feasibility and stability of indoor OPVs.