Browsing by Author "Yavuz, H. I."

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    Effect of Au nano-particles on TiO2 nanorod electrode in dye-sensitized solar cells
    (Elsevier, 2012-05-26) Ghaffari, M.; Cosar, M. B.; Yavuz, H. I.; Ozenbas, M.; Okyay, Ali Kemal
    Au nano particles (NPs) were deposited on vertically grown TiO2 nanorod arrays on FTO substrate by hydrothermal process. Metal nanoparticles were loaded onto the surface of TiO2 nanorods via photochemical reduction process under ultraviolet irradiation. X-ray diffraction (XRD), electron microscopy (FESEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) analysis were used to characterize the as-prepared Au/TiO2 nanorod composites. Current density-voltage (I-V) measurements were obtained from a two-electrode sandwich type cell. The presence of Au nanoparticles can help the electron-hole separation by attracting photoelectrons. Addition of Au nanoparticles to the TiO2 nanorod significantly increased the fill factor and J(SC) (short circuit current density). The application of Au NPs TiO2 nanorods in improving the performance of DSSCs is promising.
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    Enhanced Performance of Nanowire-Based All-TiO2 Solar Cells using Subnanometer-Thick Atomic Layer Deposited ZnO Embedded Layer
    (Pergamon Press, 2015) Ghobadi, A.; Yavuz, H. I.; Ulusoy, T. G.; Icli, K. C.; Ozenbas, M.; Okyay, Ali Kemal
    In this paper, the effect of angstrom-thick atomic layer deposited (ALD) ZnO embedded layer on photovoltaic (PV) performance of Nanowire-Based All-TiO2 solar cells has been systematically investigated. Our results indicate that by varying the thickness of ZnO layer the efficiency of the solar cell can be significantly changed. It is shown that the efficiency has its maximum for optimal thickness of 1 ALD cycle in which this ultrathin ZnO layer improves device performance through passivation of surface traps without hampering injection efficiency of photogenerated electrons. The mechanisms contributing to this unprecedented change in PV performance of the cell have been scrutinized and discussed.