Organic photovoltaic devices based on graphene as an electron-acceptor material and P3OT as a donor material

We present the fabrication and performance studies of organic photovoltaic (OPV) devices with bulk heterojunction (BHJ) structure that use organic solution-processable functionalized graphene (SPFGraphene) as an electron-acceptor material and poly(3-octylthiophene) (P3OT) as a donor material. The structural configuration of the device is ITO/PEDOT:PSS/P3OT:PCBM-SPFGraphene/LiF/Al. After mixing graphene into the device, the performance enhanced significantly. Given illumination at 100 mW/cm(2) AM1.5 and P3OT/PCBM (1:1) mixture with 9 wt% of SPFGraphene, we recorded the best performances. The open-circuit voltage (V-oc) is 0.67 V. The short-circuit current density (J(sc)) is 4.6 mA/cm(2). The FF is 0.37. And the power conversion efficiency is 1.14%. In the P3OT:PCBM-SPFGraphene composite, the SPFGraphene acts as exciton dissociation sites and provides the transport pathway of LUMO-graphene-Al. Adding SPFGraphene into P3OT produces an appropriate energetic distance between the HOMO and the LUMO of the donor/acceptor, which leads to a high open-circuit voltage. Besides, doping SPFGraphene provides a higher exciton dissociation volume mobility of carrier transport, which leads to a large short-circuit current density. (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim