Investigation of novel PCBM analogs containing thienyl groups for organic photovoltaic devices

Novel [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) analogs containing benzo[b]thiophene and thieno[3,2-b]thiophene were used as electron acceptors in bulk heterojunction thin layer organic photovoltaic devices. The solubility of the novel methanofullerenes in dichloromethane significantly varied, and es-TThCBM, which was 1.4 times as soluble as PCBM, exhibited maximum solubility. The morphology of the thin films prepared from the mixtures of these methanofullerenes with regioregular poly(3-hexylthiophene) (P3HT) was investigated by XRD, AFM, and UV–vis absorption spectroscopy. Devices containing the novel methanofullerenes exhibited nearly the same performance as those containing PCBM.