In situ polymerization of ethylenedioxythiophene from sulfonated carbon nanotube templates: Toward high efficiency ITO-free solar cells

Sulfonated carbon nanotubes (SCNTs) act as secondary polymerization templates for in situ preparation of poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS). It essentially reduces the content of insulating PSS, instead of pre- or post-solvent processing, for a highly conductive PEDOT:PSS:SCNT composite electrode. The PEDOT:PSS:SCNT was characterized with regard to its composition, conformation, stability, morphology, optoelectronic devices, and work function behavior. The PEDOT:PSS:SCNT films with a low work function (4.4 eV) and remarkable optoelectronic properties (over 3500 S cm^-1, ∼83% transmittance at a 70 nm thickness film) were suitably integrated as a cathode in organic solar cells (OSCs) with a power conversion efficiency (PCE) of 9.91% and perovskite solar cells (PSCs) with a PCE of 13.31%.