PEDOT:PSS/SWCNTs as a Transparent Electrode for Organic Photovoltaic Devices

We have fabricated a flexible organic solar cells, with an active layer of poly(3-hexylthiophene) (P3HT) blended with Fullerene derivative [6,6]-phenyl–C61–butyric acid methyl ester (PCBM) which was deposited by spin coating. The poly(3,4-ethylene dioxythiophene) poly(4-styrenesulfonate) (PEDOT:PSS), doped with ethylene glycol (EG) and single wall carbon nanotubes (SWCNTs), is heavily doped and therefore used as conductive transparent electrode rather than electron blocking layer. Likewise, we have deposited a layer of PEDOT:PSS/SWCNTs by spin coating. This layer is coated onto polyethylene terephthalate (PET) substrates. We have also compared the photovoltaic characteristics of the two different structures with PEDOT:PSS/SWCNTs or PEDOT:PSS/SWCNTs/PEDOT:PSS photoanode. Both structures show significant photovoltaic behavior. However, the power conversion efficiency has been scaled up from 1.02% to 1.93% resulting from the use of second layer of PEDOT:PSS.