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ABSTRACT:In the present article, we report the chemical synthesis and characterization of poly(aniline-co-fluoroaniline) [poly(An-FAn)]. The copolymerization of aniline and 2-fluoroaniline was carried out by chemical method in acidic medium. The characterization of poly(aniline-co-fluoroaniline) was done using FTIR, UV-visible spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron micrography (SEM), and a four-points-probe conductivity method. X-ray diffraction (XRD) and SEM characterization reveal crystalline nature of doped copolymer compared to undoped copolymer. The observed decrease in the conductivity of the copolymer relative to polyaniline is attributed to the incorporation of the fluoro moieties into the polyaniline chain. The chemically synthesized copolymer shows good solubility in common organic solvents, and is, therefore, technological useful.

The anchoring mechanism of N719 dye molecules on oxalic acid treated TiO 2 (OA-TiO 2) electrodes has been investigated using extended X-ray absorption fine structure (EXAFS) measurements, Fourier transform infrared spectroscopy (FTIR), UV-Vis spectroscopy and X-ray photoelectron spectroscopy (XPS). The FTIR spectroscopy of OA-TiO 2 electrodes revealed that the oxalic acid dissociates at the TiO 2 surface and binds through bidentate chelating and/or bidentate bridging. Analyses of EXAFS, FTIR, UV-Vis and XPS measurements of N719 dye loaded onto OA-TiO 2 revealed that the binding of N719 molecules takes place via interaction between Ru atom of the dye and Oof bidentate bridged oxalate ions at TiO 2 surface. This mechanism is quite different to the binding of N719 onto untreated TiO 2 (WO-TiO 2) surface, where-COOH and SCN groups of the dye directly bind to TiO 2 surface. The analyses of UV-Vis data show that the amount of N719 dye loading is much higher onto OA-TiO 2 surface as compared to the native TiO 2 surface. In addition, the incident photon to current conversion efficiency (IPCE) measurements show that presence of oxalate ions between dye and TiO 2 surface favors efficient electron transfer, and therefore, improvement in device efficiency. The dye sensitized solar cells fabricated using N719 dye sensitized onto OA-TiO 2 showed an efficiency of ~4.6%, which is significantly higher than that based on WO-TiO 2 electrode (~3.2%).

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