Yazar "Ozel, Faruk" seçeneğine göre listele

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    Advancing perovskite solar cells: Inorganic CCTS hole-transporting material for enhanced efficiency and stability
    (Elsevier, 2025) Sari, Fahriye; Ozel, Sultan Suleyman; Sarilmaz, Adem; Ozel, Faruk; Kus, Mahmut; Ersoz, Mustafa
    One of the most effective methods for generating renewable energy is the efficient conversion of photons into electrical energy using environmentally sustainable materials. In recent years, the integration of chalcogenide materials, which exhibit graphene-like semiconducting properties and high charge carrier mobility, into perovskite solar cells (PSCs) has garnered significant attention for enhancing the performance, stability, and ecofriendly nature of these devices. In this study, Cu2CoSnS4 (CCTS) nanocrystals were synthesized and utilized as a fully inorganic hole transport layer (HTL) in inverted PSCs. Devices incorporating 6 vol% CCTS achieved a power conversion efficiency (PCE) of 10.07 %, and retained 93 % of their initial efficiency after 720 h under inert storage conditions, without encapsulation. This demonstrates a notable improvement in stability compared to conventional PEDOT: PSS-based devices. The optimized CCTS HTL provided better energy level alignment, reduced moisture ingress, and enhanced charge transport. These findings indicate that CCTS is a promising inorganic HTL candidate for efficient and stable PSCs.
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    Inorganic CNTS as a potential hole-transport material for extremely stable and effective perovskite solar cells
    (Pergamon-Elsevier Science Ltd, 2025) Sari, Fahriye; Ozel, Sultan Suleyman; Ozel, Faruk; Bersani, Massimo; Kus, Mahmut
    In view of these distinctive properties, chalcogenide materials have attracted attention in response to the growing need for sustainable energy sources, with a particular focus on the efficient utilization of solar energy. One of the principal challenges associated with PSCslies in addressing the fill factor (FF) deficit and resolving stability concerns. Band alignment and resistance at the interface further reduce the fill factor, thereby limiting device performance. This research demonstrates that Cu2NiSnS4 (CNTS) can serve as an effective hole transport material for perovskite solar cells, offering an enhanced stability. In this study, kesterite-based CNTS is utilized as a hole-selective interlayer in inverted CH3NH3PbI3 perovskite solar cells (PSCs) on ITO/CNTS substrates. CNTS was selected due to its numerous advantages, including the abundance of their constituent elements in nature, non-toxicity, cost-effectiveness, appropriate band gap and absorption coefficient for photovoltaic (PV) applications, as well as their tunable band gap properties. Deposition of CNTS onto ITO glass alters the substrate's work function, resulting in open-circuit voltages exceeding 1.0 V. Solar cells on ITO substrates without a metal oxide layer demonstrated an exceptional power conversion efficiency (PCE) of 10.6 %. This highlights the potential of PSCs for high performance with a single selective contact. Our findings reveal that these cells retain over 93 % of their initial efficiency after 720 h, demonstrating improved stability. Replacing p-type organic materials with inorganic counterparts offers a promising avenue for further research.
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    The Frequency-Dependent Electrical Properties and Fabrication of Diode
    (Gazi Univ, 2025) Sevgili, Omer; Orak, Ikram; Ozel, Sultan Suleyman; Ozel, Faruk
    The fabrication of Al/NiO/p-Si Schottky diode (SD) was formed using a thermal evaporation system. The structural analyze of NiO using an interfacial layer was conducted using a Scanning Electron Microscope (SEM) and the SEM cross-section revealed a thickness of 0.0345 mu m for NiO interfacial layer. The capacitance-voltage (C-V) and conductance-voltage (G/omega-V) measurements of the fabricated SD were performed in the 50 kHz to 5 MHz frequency range and in the-3 V to +3 V range. The Nicollian-Brews method was employed to calculate the series resistance (Rs), while the high-low frequency capacitance method (CHF-CLF) was used to calculate the surface states (Nss). The value of the Nss was determined to be in the order of 1012 eV-1cm-2. These findings suggest that NiO is a promising alternative to conventional insulating layers in electronic devices.
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    The performance of Ag2S/X (X: Co and Ni) nanocrystals as counter electrodes in dye-sensitized solar cells
    (Pergamon-Elsevier Science Ltd, 2025) Ozel, Sultan Suleyman; Bulucu, Esen Dagasan; Sarilmaz, Adem; Ozel, Faruk
    In the present study, Silver sulfide (Ag2S)-based nanocrystals (NCs) were synthesized by employing a facile hot injection method. These NCs are utilized as counter electrodes on dye-sensitized solar cells (DSSCs), representing a smart approach that utilizes these NCs as catalysts instead of platinum (Pt) for the first time. The study provides a comparative analysis of the performance of Ag2S-based counter electrodes (CEs) in DSSCs technologies the traditionally compared Pt-based electrodes under identical conditions. The findings showed that the Ag2S-based DSSCs exhibited a power conversion efficiency (eta) that was approximately 5.2 % higher than that of the platinum-based DSSCs. Consequently, the results of this study demonstrate that Ag2S-based NCs possess the potential to function as novel counter electrode materials for low-cost, Pt-free solar cells. Moreover, the results of this study bear considerable implications for the development of cost-effective and sustainable solar energy solutions. The advent of Ag2S-based NCs signifies a significant milestone in the quest for sustainable and efficient energy solutions. This study also invites further exploration into other potential material combinations and synthesis methods that could enhance the properties and performance of DSSCs.
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    The role of NiO in isotype heterojunction photodiodes
    (Iop Publishing Ltd, 2025) Sevgili, Omer; Orak, Ikram; Ozel, Sultan Suleyman; Ozel, Faruk
    This study presents a structural analysis of NiO and the fabrication of Al/NiO/p-Si isotype heterojunction photodiode (PD) as well as an investigation of the photo-response and photovoltaic (PV) properties of the PD in the various illumination intensities. The series resistance (RS) value of the Al/NiO/p-Si was calculated to be 0.11 k Omega using Ohm's Law at 2 V. This result corroborates the assertion that RS is the pivotal parameter for attaining optimal performance in a PD. The NiO has made a notable improvement to the electrical parameters such as ideality factor, barrier height, and series resistance. The spectral responsivity R value of the PD was calculated as 1.59 A W-1 at -2 V. The Al/NiO/p-Si exhibited a short-circuit current density (JSC) of 60.38 mAcm-2, an open-circuit voltage (VOC) of 149.0 mV, a fill factor (FF) of 27.67%, and a power conversion efficiency (PCE) of 2.49%. In view of the experimental results, it can be concluded that NiO represents a promising material for the optimization of heterojunction photodiode applications.