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    Evropiyum (Eu+3) katkılı TiO2 ince filmlerin sentezi karakterizasyonu ve boya duyarlı güneş pilinde foto-anot olarak kullanımı
    (Selçuk Üniversitesi Fen Bilimleri Enstitüsü, 2018) Arslan, Hanife; Gülveren, Berna
    In this thesis study, pure and Europium (Eu3+) (0.5% M and 1% M)-doped titanium dioxide (TiO2) pastes with different concentrations have been synthesized by sol-gel method and used to produce a photo-anode component in dye sensitized solar cells (DSSCs). The structural, the morphological and the optical properties of photo-anodes have been determined by characterization measurements such as X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), ultraviolet (UV) spectroscopy. Then, these photo-anodes were combined with a platinum (Pt)-coated photocathode and an iodine-based electrolyte to produce pure and Eu3+ doped DSSCs. The XRD results of doped films have been compared with the values of pure one and it has been observed that all the patterns have matched with anatase phase of TiO2 for all samples. Futhermore, doping has caused a decarease in the intensity of the paterns and broadening the diffraction peaks. Inclusion of Eu+3 ions in the TiO2 structure has been confirmed with XPS analysis results. The photovoltaic performances of the DSSCs have been determined with the incident photon conversion efficiency (IPCE) and current density (J) - voltage (V) measurements. Photovoltaic parameters such as open circuit voltage (Voc), short circuit current density, (Jsc), fill factor (FF) and efficiency (?) have been calculated by using current density (J) -voltage (V) curves. The obtained results indicated that the DSSC which was produced by using 1% Eu3+ doped TiO2 photoanode compounent has the highest efficiency value (?=11.31%) as compared with the results of other samples. The efficiency value of 1% Eu3+ doped DSSC is 27.2% over the value measured for the pure sample and doping with Eu3+ has improved the photovoltaic performance of the cells remarcablely.
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    Facile synthesis of cobalt-doped zinc oxide thin films for highly efficient visible light photocatalysts
    (ELSEVIER SCIENCE BV, 2016) Yildirim, Ozlem Altintas; Arslan, Hanife; Sonmezoglu, Savas
    Cobalt-doped zinc oxide (Co:ZnO) thin films with dopant contents ranging from 0 to 5 at.% were prepared using the sol-gel method, and their structural, morphological, optical, and photocatalytic properties were characterized. The effect of the dopant content on the photocatalytic properties of the films was investigated by examining the degradation behavior of methylene blue (MB) under visible light irradiation, and a detailed investigation of their photocatalytic activities was performed by determining the apparent quantum yields (AQYs). Co2+ ions were observed to be substitutionally incorporated into Zn2+ sites in the ZnO crystal, leading to lattice parameter constriction and band gap narrowing due to the photoinduced carriers produced under the visible light irradiation. Thus, the light absorption range of the Co:ZnO films was improved compared with that of the undoped ZnO film, and the Co:ZnO films exhibited highly efficient photocatalytic activity (similar to 92% decomposition of MB after 60-min visible light irradiation for the 3 at.% Co:ZnO film). The AQYs of the Co:ZnO films were greatly enhanced under visible light irradiation compared with that of the undoped ZnO thin film, demonstrating the effect of the Co doping level on the photocatalytic activity of the films. (C) 2016 Elsevier B.V. All rights reserved.