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Study of Photovoltaic Characteristics of Prepared Titanium Oxide-reduced Graphene Oxide Nanocomposite as Photoanode of Solar Cells

Nouri, Esmaiel | 2017

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 49531 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Mohammadi, Mohammad Reza
  7. Abstract:
  8. In the present study, TiO2-reduced graphene oxide (T-RGO) nanocomposites were synthesized via various in-situ and ex-situ methods, then their photovoltaic performance was examined as photoanode and mesoporous layers in dye-sensitized Solar Cells (DSSCs) and perovskite Solar Cells (PSCs), respectively. Graphene oxide (GO) was prepared using Hummer’s method with some modifications. Both thermal and hydrothermal processes were used to reduce GO. Structural and optical characterization was analytically demonstrated by subjecting of the obtained materials by several techniques, including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman, thermogravimetric analysis (TGA), UV-visible absorbance, N2 adsorption-desorption, atomic force microscopy (AFM), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM). The results indicate that disruption of the GO layers and a relatively high degree of reduction to graphene sheets was obtained by in-situ approach. UV-Vis spectroscopy revealed that the presence of RGO induced an important band gap narrowing and visible light absorption, particularly in the case of in-situ process, indicating chemical bonding between TiO2 nanoparticles and graphene sheets. Interestingly, despite the fact that in-situ prepared photoanode had the highest specific surface it demonstrated the lowest capacity of N719 dye adsorption. In-situ doping of titania with RGO had the most marked beneficial effects on the photovoltaic performance of DSSC and PSC devices, yielding the highest IPCE, Jsc, Voc and η values. This was mainly attributed to the role of RGO in the titania films to enhanced electron lifetime and suppress electron-hole recombination by facilitating electron transport. The impact of RGO content on optical and photovoltaic properties of T/RGO nanocomposites and their made-up devices are also studied, suggesting an optimal RGO content of 0.4 and 0.2 wt.% in DSSCs and PSCs, respectively. At high contents of RGO, the cell-performance would be limited by the reduced incident light intensity to the absorber due to lower transmittance and blurring the T/RGO layer. Finally, GO and GO-Li was used as hole and electron transporting materials, respectively, in inverted PSCs. Maximum power conversion efficiency of 10.2% was achieved
  9. Keywords:
  10. Graphene Oxide ; Dye Sensitized Solar Cells ; Solvothermal Method ; Photoanode Electrode ; Perovskite-Based Solar Cell ; Titanium Oxide-Reduced Graphene Oxide Nanocomposite ; Charge Recombination

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