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Keywords:

  • transparent electrodes;
  • organic solar cells;
  • PEDOT:PSS;
  • stretchable/flexible electrodes

Abstract

Highly conductive and transparent poly-(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS) films, incorporating a fluorosurfactant as an additive, have been prepared for stretchable and transparent electrodes. The fluorosurfactant-treated PEDOT:PSS films show a 35% improvement in sheet resistance (Rs) compared to untreated films. In addition, the fluorosurfactant renders PEDOT:PSS solutions amenable for deposition on hydrophobic surfaces, including pre-deposited, annealed films of PEDOT:PSS (enabling the deposition of thick, highly conductive, multilayer films) and stretchable poly(dimethylsiloxane) (PDMS) substrates (enabling stretchable electronics). Four-layer PEDOT:PSS films have an Rs of 46 Ω per square with 82% transmittance (at 550 nm). These films, deposited on a pre-strained PDMS substrate and buckled, are shown to be reversibly stretchable, with no change to Rs, during the course of over 5000 cycles of 0 to 10% strain. Using the multilayer PEDOT:PSS films as anodes, indium tin oxide (ITO)-free organic photovoltaics are prepared and shown to have power conversion efficiencies comparable to that of devices with ITO as the anode. These results show that these highly conductive PEDOT:PSS films can not only be used as transparent electrodes in novel devices (where ITO cannot be used), such as stretchable OPVs, but also have the potential to replace ITO in conventional devices.