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    Characterization of organic solar cells using semiconducting polymers with different bandgaps
    (Walter De Gruyter Gmbh, 2019) Borazan, Ismail; Altin, Yasin; Demir, Ali; Bedeloğlu, Ayşe
    Polymer-based organic solar cells are of great interest as they can be produced with low-cost techniques and also have many interesting features such as flexibility, graded transparency, easy integration, and lightness. However, conventional wide bandgap polymers used for the light-absorbing layer significantly affect the power conversion efficiency of organic solar cells because they collect sunlight in a given spectrum range and due to their limited stability. Therefore, in this study, polymers with different bandgaps were used, which could allow for the production of more stable and efficient organic solar cells: P3HT as the wide bandgap polymer, and PTB7 and PCDTBT as low bandgap polymers. These polymers with different bandgaps were combined with PCBM to obtain increased efficiency and optimum photoactive layer in the organic solar cell. The obtained devices were characterized by measuring optical, photoelectrical, and morphological properties. Solar cells using the PTB7 and PCDTBT polymers had more rough surfaces than the reference cell using P3HT. The use of low-bandgap polymers improved I-sc significantly, and when combined with P3HT, a higher V-oc was obtained.
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    A comparative approach to enhance the electrical performance of PEDOT:PSS as transparent electrode for organic solar cells
    (Sage Publications Ltd, 2020) Borazan, Ismail; Bedeloğlu, Ayşe; Demir, Ali
    In this article, the improvement in electrical performance of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) as the transparent electrode doped with different additives (ethylene glycol (EG), isopropyl alcohol) or treatment of sulfuric acid was enhanced that organic solar cells (OSCs) were produced by using poly(3-hexylthiophene-2,5-diyl):[6,6]-phenyl C-61 butyric acid methyl ester. OSCs were fabricated by the doped or treated PEDOT:PSS films as transparent electrodes. The photoelectrical measurements were carried out and the effects of doping or treatment were compared. As a result, EG-added PEDOT:PSS electrode showed the best power conversion efficiency value of 1.87% among the PEDOT:PSS anodes.
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    The Effect of Acid Treatment of PEDOT:PSS Anode for Organic Solar Cells
    (Ieee, 2015) Borazan, Ismail; Bedeloğlu, Ayşe; Demir, Ali; Carroll, David
    The goal of this paper is to develop and investigate the properties of PEDOT:PSS layer, which was treated with different acids and solvents including formic acid, sulfuric acid, and hydrochloric acid, methanol, acetone, and dichlorobenzene:methanol, to substitute ITO anode in organic solar cells. Organic solar cells structures were constructed with three different bottom electrodes:ITO, pure PEDOT:PSS and treated PEDOT:PSS. Two point probe method was used to measure resistance of pedot:pss layer were carried out and the best chosen method was employed to make an organic solar cell device.
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    Manufacturing and morphology of poly(epsilon-caprolactone) based microfibre webs for biomedical applications through airbrush technique
    (Natl Inst Science Communication-Niscair, 2017) Bedeloğlu, Ayşe; Bhullar, Sukhwinder Kaur; Borazan, Ismail; Cin, Zeynep Islek; Demir, Ali
    The objective of this study is to fabricate poly(epsilon-caprolactone) (PCL)-based micro/nano fibrous structures by using different types of solvents and nozzle sizes and to investigate the morphology of fabricated airbrushed structures for future biomedical applications. It is observed from the morphology and diameter of micro/nanofibres structures based on nozzle size, concentration of PCL and solvents, that these airbrushed biocompatible and biodegradable webs offer a potential in the medical field requiring direct, rapid and conformable applications.
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    A photovoltaic textile design with a stainless steel mesh fabric
    (Sage Publications Inc, 2022) Borazan, Ismail; Bedeloğlu, Ayşe; Demir, Ali
    Solar energy is one of the most popular energy sources among the other renewable energies. Photovoltaic technology is a clean way to generate electricity from sunlight. Flexible photovoltaics enable portable electronic devices to power at off-grid conditions. Stainless steel mesh fabric was used as a substrate and electrode allowing the light to reach the photoactive layer. The photoactive layer and hole transport layer were deposited by the means of dip-coating like in the textile industry. The metal back electrode was evaporated in a thermal evaporator under vacuum. Promising results were obtained from photovoltaic measurements. About 0.69% power conversion efficiency was obtained from textile-based solar cells in this study. The textile-based metal fabric enables a flexible photovoltaic structure that can be integrated on non-planar surfaces to generate electricity, and also mesh structure allows the light to reach the photoactive layer.
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    Solution-processed transparent conducting electrodes with graphene, silver nanowires and PEDOT:PSS as alternative to ITO
    (Elsevier Science Sa, 2016) Altin, Yasin; Tas, Mahmut; Borazan, Ismail; Demir, Ali; Bedeloğlu, Ayşe
    Novel transparent electrodes, including graphene, silver nanowires (AgNWs) and poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) serving as the low-cost and flexible alternative to indium tin oxide (ITO) are of interest to the organic electronic industry in recent years. In this paper, transparent, flexible and conductive nanocomposite electrodes were fabricated by using different combinations of graphene, AgNWs, PEDOT:PSS materials via spin coating technique. Optical, morphological and electrical properties of solution-processed electrodes were characterized. Transparent conductive electrode (TCE) based on PEDOT:PSS/AgNW/graphene construction exhibited 216.67 Omega/sq sheet resistance with-83% transparency. Additionally, after 100 cycles of bending, the sheet resistance of PEDOT:PSS/AgNW/graphene electrode on the flexible polyethylene terephthalate (PET) substrate was found to be about 223 Omega/sq, while conventional ITO-coated PET substrate exhibited 83,050 Omega/sq resistance, which was about 400 times more than that of resistance before bending. Optical and electrical measurements showed that obtained nanocomposite electrodes may be promising alternatives to ITO to be used in flexible optoelectronic devices. (C) 2016 Elsevier B.V. All rights reserved.