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    Exploring the role of rare earth elements doped TiO2 based photoanodes on the performance of dye-sensitized solar cells
    (Springer, 2026) Caliskan, Berrak; Sayan, Enes; Igman, Erdal
    This study investigates the synthesis and characterization of rare earth elements (REEs) doped TiO2 thin films based photoanodes for use in dye-sensitized solar cells (DSSCs). For this purpose, TiO2 films were doped with Ho & sup3;(+), La & sup3;(+), Er & sup3;(+), and Yb & sup3;(+) ions to enhance photoelectrochemical properties. Characterization techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-Vis spectroscopy, BET surface area analysis, and X-ray photoelectron spectroscopy (XPS) were employed for the structural, morphological, and optical characterization of the synthesized photoanodes and CEs. REEs doping improved the surface morphology and optical properties of TiO2, in particular, it increased photon absorption in the visible light range. La & sup3;(+) and Ho & sup3;(+) significantly improved photovoltaic performance, achieving power conversion efficiencies of 3.78% and 2.87%, respectively, compared to that of pure TiO2. These enhancements indicate improved charge transport and light harvesting due to incorporation of REEs. Additionally, replacing the conventional platinum counter electrode (CE) with reduced graphene oxide (rGO) further enhanced performance, offering a low-cost and efficient alternative. The study highlights the combined benefits of REEs doping and rGO integration in improving DSSCs efficiency. These findings contribute to the development of more sustainable, cost-effective solar energy technologies and underline the potential of REEs-doped TiO2 films and rGO electrodes in advancing next-generation photovoltaic devices.
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    Exploring the ımpact of metal doping and alternative electrodes on the performance of dye-sensitized solar cells
    (Springer, 2026) Caliskan, Berrak; Sayan, Enes; Igman, Erdal
    This study explores the synthesis and characterization of metal-doped TiO2 thin films for applications in dye-sensitized solar cells (DSSCs). Titanium dioxide (TiO2) films were doped with various metal ions such as Ag+, Zn2+, Fe3+, and Co2+, to enhance the photoelectrochemical properties of the photoanode. The films were characterized using various techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-Vis spectroscopy, and X-ray photoelectron spectroscopy (XPS). The doping process was found to influence the morphology, surface area, and optical properties of the TiO2 films, resulting in enhanced light absorption, particularly in the visible range. The effects of metal doping on the performance of the DSSCs were evaluated, showing that Co2+ and Ag+ doping resulted in improved efficiency compared to undoped TiO2, with the Co2+-doped TiO2 achieving the highest power conversion efficiency of 2.85%. Additionally, the incorporation of reduced graphene oxide (rGO) as a counter electrode demonstrated a significant enhancement in DSSC performance, even surpassing traditional platinum-based counter electrodes. The results suggest that metal doping and rGO incorporation offer promising strategies for improving DSSC efficiency. This study highlights the potential of metal-doped TiO2 photoanodes and rGO counter electrodes in advancing the development of cost-effective, high-performance DSSCs for sustainable solar energy applications.
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    Graphene/polyaniline nanocomposite as platinum-free counter electrode material for dye-sensitized solar cell: its fabrication and photovoltaic performance
    (Springer, 2020) Bayram, Ozkan; Igman, Erdal; Guney, Harun; Demir, Zeynep; Yurtcan, Mustafa Tolga; Cirak, Cagri; Hasar, Ugur Cem
    In this study, it was aimed to produce graphene/polyaniline nanocomposite thin films as counter electrode materials by PECVD system and to determine the photovoltaic performances of these counter electrodes in dye-sensitized solar cells (DSSCs). Graphene/polyaniline counter electrode (GPCE) material was produced in two different steps. Firstly, a single-layer and multilayer graphene thin films were produced on the fluorine-doped tinoxide (FTO) substrates. Then, polyaniline (PANI) thin films were grown on each graphene thin films using plasma polymerization technique, and eventually the production of the graphene/PANI nanocomposite was completed. The fabricated graphene/PANI nanocomposites were used in place of platinum (Pt)-counter electrode which is widely used in DSSCs and the photovoltaic performance of these counter electrodes was investigated. The DSSCs consisted of titanium dioxide (TiO2) nanotube photoanode, N719 dye, iodolyte liquid electrolyte, and graphene/PANI nanocomposite counter electrode. I-V measurements were carried out in order to calculated photoconversion efficiency (PCE) and it was found that the these efficiency of GPCEs changed between 0.56 and 1.36% according to the number of graphene layers. The photovoltaic performance of DSSC, consisting of TiO2 nanotube photoanode and Pt-counter electrode was 1.1%.
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    Photovoltaic performance of non-covalent functionalized single-layer graphene in dye-sensitized solar cells (DSSCs)
    (Springer, 2021) Igman, Erdal; Bayram, Ozkan; Mavi, Ahmet; Hasar, Ugur Cem; Simsek, Onder
    In this study, it was aimed to fabricate new effective alternative counter electrodes (CEs) in dye-sensitized solar cells (DSSCs). For this purpose, firstly, single-layer graphene (SLG) thin films were grown by chemical vapor deposition (CVD) method. Then, these films were separately functionalized with 1,8-cineole (ppCin/SLG), D-Limonene (ppLim/SLG) and Thiophene (ppTh/SLG) by plasma polymerization. Number of layers in CVD-grown graphene determined by Raman, transmission electron microscope (TEM) and ultraviolet-visible (UV-Vis) spectroscopy. Chemical structures of plasma polymerised (pp) thin films were investigated by Fourier transform infrared (FTIR) spectroscopy. Photovoltaic parameters of DSSCs were calculated, and electrocatalytic properties of CEs were investigated by electrochemical impedance spectroscopy (EIS). Polymer functionalization greatly enhanced the electrical conductivity and electrocatalytic activity properties of graphene compared to that of SLG. The efficiencies of DSSCs with ppCin/SLG and ppLim/SLG CEs were 1.10% and 1.02%, respectively. As a result, the cell efficiencies of ppCin/SLG and ppLim/SLG could be as alternative materials to platinum (Pt) counter electrode.