Titanium dioxide/silver (TiO2/Ag) composite films were prepared by incorporating Ag in pores of mesoporous TiO2films using a photoreduction method. The Ag nanoparticle sizes were in a range of 4.36–38.56 nm. The TiO2/Ag composite films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The TiO2and TiO2/Ag composite films were then sensitized by immersing in a 0.3 mM N719 dye solution and fabricated for conventional dye-sensitized solar cells (DSCs).J-Vcharacteristics of the TiO2/Ag DSCs showed that the Ag nanoparticle size of 19.16 nm resulted in the short circuit current density and efficiency of 8.12 mA/cm2and 4.76%.
Novel TiO2/MgO/Ag composite electrodes were applied as working electrodes of dye-sensitized solar cells (DSSCs). The TiO2/MgO/Ag composite films were prepared by dip coating method for MgO thin films and photoreduction method for Ag nanoparticles. The MgO film thicknesses and the Ag nanoparticle sizes were in ranges of 0.08–0.46 nm and 4.4–38.6 nm, respectively. The TiO2/MgO/Ag composite films were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The TiO2/MgO/Ag composite electrodes were sensitized by immersing in a 0.3 mM of N719 dye solution and fabricated for conventional DSSCs.J-Vcharacteristics of the TiO2/MgO/Ag DSSCs showed that the MgO film thickness of 0.1 nm and the Ag nanoparticle size of 4.4 nm resulted in maximum short circuit current density and efficiency of 8.6 mA/cm2and 5.2%, respectively. Electrochemical Impedance Spectroscopy showed that such values of short circuit current density and efficiency were optimal values obtained from plasmon energy transfer by 4.4 nm Ag nanoparticles and recombination barrier by the ultrathin MgO film.
Dye sensitized solar cells (DSSCs) consist of photoanodes (dye adsorbed porous semiconductor film), electrolytes and counter electrodes. Nanostructured materials play important parts in both the photoanodes and the counter electrodes, while dyes are there to absorb photons and generate electron-hole pairs and electrolytes are there to transfer electrons from the photoanodes to the counter electrodes. In this study, to enhance light absorption and minimize electron-hole recombination, Ag nanoparticles and MgO nanolayer were coated on TiO2, respectively. To enable a long lifetime, i.e. avoiding liquid electrolyte leakage, quasi-solid-state (QSS) DSSCs were fabricated. PtSn nanoparticles were prepared by a simple chemical reduction method on graphene oxide (GO) to compare with conventional Pt catalyst on FTO substrates as counter electrodes. An average efficiency of the QSS DSSCs with PtSn/GO co-catalysts was found to outperform that of the QSS DSSCs with conventional Pt catalyst. A mixed microstructure of the PtSn/GO co-catalyst was observed. Although, PtSn2 and Pt2Sn3 phases were suggested by XRD, in a small region observed by EDX-STEM, it was found that C, O and Si were distributed uniformly on the graphene oxide film. Pt was also distributed uniformly, but the signal was low so there were only a few X-Ray counts across the image. There was no sign of Pt being concentrated in the particles. However, Sn was found to be concentrated in the particles without any other elements.
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