Indium Tin Oxide-Free Small Molecule Organic Solar Cells Using Single-Walled Carbon Nanotube Electrodes

We demonstrated single-walled carbon nanotubes (SWNTs) electrode-based small molecule organic solar cells (OSCs) using diketopyrrolopyrrole donor, DPP(TBFu)(2) as an electron donor with [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) as an electron acceptor. SWNT films with 60% transmittance (at 550 nm) were dry-transferred onto glass substrates to replace conventional indium tin oxide (ITO) electrodes. In order to improve the conductivity of the SWNT electrodes, MoOX thermal doping was applied followed by spin coating of poly(3,4-ethylenedioxythiophene): polystyrenesulfonate (PEDOT:PSS) to enhance doping and electrode blocking function. The indium-free devices showed a power conversion efficiency (PCE) of 1.00% while ITO-based devices showed a PCE of 3.79%. (C) The Author(s) 2017. Published by ECS.