Highly Conductive PEDOT:PSS Electrode with Optimized Solvent and Thermal Post‐Treatment for ITO‐Free Organic Solar Cells

TLDR

PEDOT:PSS films can serve as stand‑alone electrodes for organic solar cells, and their performance has been improved by a solvent post‑treatment method. Solvent treatment reduces insulating PSS in the PEDOT:PSS layer, and pre‑heating the electrodes further enhances power‑conversion efficiency to match that of ITO electrodes. The optimized PEDOT:PSS electrodes exhibit conductivities up to 1418 S cm⁻¹, enable fabrication of ITO‑free ZnPc:C₆₀ solar cells on glass and PET, and achieve power‑conversion efficiencies comparable to ITO devices, demonstrating their promise for flexible, high‑efficiency OSCs.

Abstract

Abstract Highly conductive poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) films as stand‐alone electrodes for organic solar cells have been optimized using a solvent post‐treatment method. The treated PEDOT:PSS films show enhanced conductivities up to 1418 S cm −1 , accompanied by structural and chemical changes. The effect of the solvent treatment on PEDOT:PSS has been investigated in detail and is shown to cause a reduction of insulating PSS in the conductive polymer layer. Using these optimized electrodes, ITO‐free, small molecule organic solar cells with a zinc phthalocyanine (ZnPc):fullerene C 60 bulk heterojunction have been produced on glass and PET substrates. The system was further improved by pre‐heating the PEDOT:PSS electrodes, which enhanced the power conversion efficiency to the values obtained for solar cells on ITO electrodes. The results show that optimized PEDOT:PSS with solvent and thermal post‐treatment can be a very promising electrode material for highly efficient flexible ITO‐free organic solar cells.