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    Effect of UV exposure of ITO/PEDOT:PSS substrates on the performance of inverted-type perovskite solar cells
    (Springer, 2020) Alishah, Hamed Moeini; Kazici, Mehmet; Ongul, Fatih; Bozar, Sinem; Rodop, Macide Canturk; Kahveci, Cihangir; Arvas, Melih Besir
    We have fabricated inverted-type perovskite solar cells employing CH3NH3PbI3-xClx perovskite in the form of ITO/PEDOT:PSS/Perovskite/PCBM/Al. The effects of UV radiation on ITO/PEDOT:PSS substrates have been investigated for perovskite solar cells. ITO/PEDOT:PSS substrates were exposed to UV radiation for 5 to 15 min. The perovskite solar cells fabricated on UV-irradiated ITO/PEDOT:PSS substrates exhibited better performance as compared to those fabricated on substrates employing non-treated PEDOT:PSS. We used photovoltaic characterization, UV-VIS absorption, sheet resistance, X-ray diffraction (XRD), scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR), and external quantum efficiency (EQE) characterization techniques to investigate the effect of UV irradiation of ITO/PEDOT:PSS substrates on the performance of perovskite solar cells. The devices fabricated on ITO/PEDOT:PSS (UV irradiated for 10 min) exhibited the best device performance of all. We achieved a 9% increase in the overall power conversion efficiency for the devices fabricated on substrates exposed to UV radiation.
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    Effects of different formulation PEDOT:PSS hole transport layers on photovoltaic performance of organic solar cells
    (John Wiley and Sons, August 2017) Ongul, Fatih; Yuksel, Sureyya Aydin; Kazici, Mehmet; Bozar, Sinem; Gunbatti, Anil; Gunes, Serap
    In this study, the effects of the various types of PEDOT:PSS with different conductivities on the photovoltaic parameters of organic solar cells were investigated. The performances of five various commercially available PEDOT:PSS with formulations such as FET, PT2, PH1000, PH500 and PH were compared. It was observed that the device employing PH1000 as an interlayer between ITO and the active layer exhibited the highest photovoltaic performance as compared to other devices with FET, PT2, PH500 and PH.
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    Influences of CdSe NCs on the photovoltaic parameters of BHJ organic solar cells
    (Pergamon-Elsevier Science Ltd, 2018) Ongul, Fatih; Yuksel, Sureyya Aydin; Allahverdi, Cagdas; Bozar, Sinem; Kazici, Mehmet; Gunes, Serap
    In this study, the high quality CdSe nanocrystals (NCs) capped with stearic acid were synthesized in a solvent and then purified four times by using the precipitation and redissolution process. The average size of the synthesized CdSe NCs was determined similar to 3.0 nm via transmission electron microscopy (TEM) measurement and their corresponding optical band edge energy was also calculated as similar to 2.1 eV using ultraviolet-visible (UV-Vis) absorption spectroscopy. The bulk heterojunction (BHJ) hybrid solar cells based on a ternary system including P3HT, PCBM and CdSe NCs at different weight concentrations (0 wt%, 0.1 wt%, 0.5 wt%, 1 wt% and 2 wt%) were fabricated by spin-casting process. The effect of the concentration of CdSe NCs on the photovoltaic parameters of these BHJ organic solar cells was investigated. The surface morphology of the photoactive layer modified by the incorporation of CdSe NCs into P3HT:PCBM matrix was observed with scanning electron microscopy (SEM). It was shown that when the concentration of CdSe NCs increases above 0.1 wt% in this ternary system, the photovoltaic performance of the devices significantly decreases. The power conversion efficiency of the organic photovoltaic (OPV) device was enhanced similar to 20% by incorporating CdSe NCs with 0.1 wt% with respect to those without CdSe NCs. (C) 2017 Elsevier B.V. All rights reserved.
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    Metal-free polymer/MWCNT composite fiber as an efficient counter electrode in fiber shape dye-sensitized solar cells
    (Iop Publishing Ltd, 2016) Ali, Abid; Shah, Syed Mujtaba; Bozar, Sinem; Kazici, Mehmet; Keskin, Bahadir; Kaleli, Murat; Akyurekli, Salih
    Highly aligned multiwall carbon nanotubes (MWCNT) as fiber were modified with a conducting polymer via a simple dip coating method. Modified MWCNT exhibited admirable improvement in electrocatalytic activity for the reduction of tri-iodide in dye sensitized solar cells. Scanning electron microscopy images confirm the successful deposition of polymer on MWCNT. Cyclic voltammetry, square wave voltammetry and electrochemical impedance spectroscopy studies were carried out to investigate the inner mechanism for the charge transfer behaviour. Results from bare and modified electrodes revealed that the MWCNT/(poly (3,4-ethylene dioxythiophene): poly(styrene sulfonate) (PEDOT:PSS) composite electrode is much better at catalysing the I-3(-)/I- redox couple compared to the pristine fiber electrode. The photoelectric conversion efficiency of 5.03% for the modified MWCNT electrodes was comparable with that of the conventional Pt-based electrode. The scientific results of this study reveal that MWCNT/PEDOT: PSS may be a better choice for the replacement of cost intensive electrode materials such as platinum. Good performance even after bending up to 90 degrees and in-series connection to enhance the output voltage were also successfully achieved, highlighting the practical application of this novel device.
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    Super aligned carbon nanotubes for interfacial modification of hole transport layer in polymer solar cells
    (Elsevier, 2023) Ali, Abid; Kazici, Mehmet; Bozar, Sinem; Asghar, Muhammad Adeel; Alwadai, Norah; Kahveci, Cihangir; Iqbal, Munawar
    This work presents a facile and innovative method for the insertion of super aligned carbon nanotubes (CNTs) as sheets over and within poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) as an efficient hole transport layer (HTL) in the inverted type polymer solar cell. CNTs sheets drawn from the vertically grown CNTs arrays were extracted via a sharp-edge blade and were directly transferred to the surface of PEDOT:PSS followed by the deposition of thermally evaporated silver electrode. All the characteristic photovoltaic parameters of the device have been improved with the insertion of special patterened CNTs sheets as compared to the standards device (without CNTs sheets). Power conversion efficiency (PCE) improved from 2.14% to 3.69% with the increased short circuit current density from 9.12 mAcm(-2) to 11.58 mAcm(-2) and fill factor from 0.48 to 0.58, respectively. Scanning electron microscopy (SEM) images revealed the successful insertion of CNTs without any destructive impact on the integrity of CNTs structure. Moreover, the performance and stability of the device have also been optimized by increasing the thickness of CNTs sheets. Electrochemical impedance spectroscopy (EIS) showed the reduction in charge transfer resistance on replacement of CNTs sheets-modified PEDOT:PSS as HTL as compared to simple PEDOT:PSS, which may be attributed to the creation of ordered steps which provided cascade routes for the better charge (holes) collection. Facile modification of the anode materials with improved device performance for designing of new device architecture will help scale-up production of low-cost, stable, and efficient polymer solar cells.
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    Theoretical and experimental investigations of the 2-(4-chlorophenyl)-3-{[5-(2-cyano-2-phenylethenyl)]furan-2-yl}acrylonitrile molecule as a potential acceptor in organic solar cells
    (Iop Publishing Ltd, 2016) Kazici, Mehmet; Bozar, Sinem; Yuksel, Sureyya Aydin; Ongul, Fatih; Gokce, Halil; Gunes, Serap; Goreci, Cigdem Yorur
    A novel soluble asymmetric acrylonitrile derivative, 2-(4-Chlorophenyl)-3-{[5-(2-cyano-2-phenylethenyl)]furan-2-yl}acrylonitrile (CPCPFA, 3) was synthesized in three steps by Knoevenagel condensation. The structure of the CPCPFA was characterized using UV-vis, FTIR, H-1 NMR, C-13 NMR, and LC-MS. CPCPFA was evaluated as an electron acceptor in bulk heterojunction organic solar cells. Its optical and electronic properties as well as photovoltaic performance were investigated.
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    Zn Phthalocyanine Derivatives for Solution-Processed Small Molecule Organic Solar Cells
    (Wiley-V C H Verlag Gmbh, 2018) Sari, Fatma Aslihan; Kazici, Mehmet; Harputlu, Ersan; Bozar, Sinem; Koyun, Ozge; Sahin, Yucel; Ugur, Naz
    Zinc phthalocyanine derivatives, 1 and 2, having either electron donating octyl-thiol group or electron accepting octyl-sulfonyl groups have been synthesized to serve as new electron donor components for bulk heterojunction (BHJ) solar cells. BHJ solar cells, in which the active layer consist of zinc phthalocyanine (ZnPc) as an electron donor and a soluble fullerene derivative, namely PCBM, as an electron acceptor component were produced and characterized. The device consisting of octylthiol-ZnPc:PCBM (1:4) gave power-conversion efficiencies of 0.42%. On the other hand, the device having octyl-sulfonyl substituted ZnPc gave very low efficiency due to both low Voc and Jsc values.