Hybrid Silver Mesh Electrode for ITO-Free Flexible Polymer Solar Cells

Abstract

Herein, we demonstrate a tailored poly(3,4-ethylenedioxythiophene) PEDOT polymer-coated silver (Ag) mesh electrode on a flexible polyethylene terephthalate (PET) substrate. By introducing this highly conductive polymer, the existing problems of Ag mesh-type transparent conductive electrodes, such as high pitch, roughness, current inhomogeneity and adhesion problems between Ag mesh grid and PEDOT polymer or PET substrate, were successfully solved, resulting in excellent electron spreading from the discrete Ag mesh onto the entire surface without sacrificing sheet conductivity and optical transparency. Based on this hybrid anode, we demonstrate highly efficient flexible polymer solar cells (PSCs) with a high fill factor of 67.11 %, resulting in a power conversion efficiency (PCE) of 6.9 % based on a PTB7:PC71BM bulk heterojunction device. Furthermore, the PSC device with the Ag mesh electrode also exhibits good mechanical bending stability, as indicated by a 70% retention of the initial PCE after 500 bending cycles compared with the PSC device with a PET/indium tin oxide (ITO) electrode, which retained 0% of the initial PCE after 300 bending cycles.