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Öğe 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, AliIn 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.Öğe A photovoltaic textile design with a stainless steel mesh fabric(Sage Publications Inc, 2022) Borazan, Ismail; Bedeloğlu, Ayşe; Demir, AliSolar 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.Öğe Characterization of organic solar cells using semiconducting polymers with different bandgaps(Walter De Gruyter Gmbh, 2019) Borazan, Ismail; Altin, Yasin; Demir, Ali; Bedeloğlu, AyşePolymer-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.Öğe Enhancing filtration performance with layered and bimodal nanofiber structures(İdris Karagöz, 2024) Toptaş, Ali; Kılıç, Ali; Demir, AliParticulate matter (PM) must be removed from the air because it is a serious threat to human health. Micro and/or nanoporous nonwoven fabrics are commonly used to filter these particles. In our study, the filtration performances of nanofibrous mats, which were obtained by combining fibers produced by two different production methods in a layered and bimodal manner, were evaluated. Fibrous layers produced by the meltblown (MB) method were obtained with similar fiber diameters and different thicknesses by different feeding speeds. Bimodal structures obtained by adding fibers with an average diameter of 225 nanometers produced by the solution blowing (SB) method into fibers with an average diameter of around 800 nm obtained at 1, 5 and 10 rpm screw rotating/feeding speeds had higher filtration performance than the samples without SB nanofibers. Then, among the 4 samples with an average basis weight of 15 gsm, the sample MB only without (electro-blown nanofiber); the EB sample contains only EB nanofibers; the sample (L) containing 4 gsm EB nanofibers and the 4-layer sample (4L) containing 4 gsm EB nanofibers (138 nm) were compared. The 4L sample had the highest quality factor (0.0353) with a filtration efficiency of %96.01 and a pressure drop of 135 Pa. Although the filtration efficiency increased in all samples with the subsequent corona treatment, the highest value (99.34%) was obtained from the 4L sample.Öğe 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, AliThe 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.Öğe Polimer Esaslı Esnek Organik Fotovoltaik Liflerin Geliştirilmesi ve Özelliklerinin İyileştirilmesi(2016) Bedeloğlu, Ayşe; Demir, Ali; Borazan, İsmail; Altın, Yasin; Canlı, Nimet Yılmaz; Taş, Mahmut; Cin, Zeynep İşlekBu projede, ülkemizin sahip olduğu yüksek güneş enerjisi potansiyelini kullanabilecek; hem dünyanın hem de ülkemizin en önemli konularından birisi olan enerji ihtiyacını karşılamaya aday olabilecek verimli, ince, esnek, hafif, taşınabilir, ucuz ve her türlü yüzeye uygulanabilir polimer esaslı organik fotovoltaik liflerin (lif formunda fotovoltaik yapılar) geliştirilmesi ve özelliklerinin iyileştirilerek verimli hale getirilmesi amaçlanmıştır. Ayrıca bu lifler, kumaş içerisine yerleştirilerek bir tekstil uygulaması da gerçekleştirilmiştir. Yüksek elektron hareketliliğine (mobilitesine) sahip elektron seçici ZnO ince filmleri çözelti esaslı yöntemlerle, bu çalışmada düşük sıcaklıklarda kaplanmıştır. Gümüş nanotel, karbon nanotüp ve grafen malzemelerinin esnek elektrot geliştirmek için kullanıldığı projede, fotovoltaik yapıyı oluşturacak elektrotlar ve diğer katmanlar farklı kaplama teknikleri (ağırlıklı olarak çözelti esaslı) ve biriktirme teknikleri kullanılarak ve iki farklı yapısal tasarımda (tek lif halinde ve sarmal yapıda iki lif olarak) üretilmiştir. Daha önce fotovoltaik lif yapılarında hiç kullanılmamış indirgenmiş grafen oksit, bu çalışmada, oksidasyonu engellemesi amacıyla kullanılmıştır. Düşük bant aralıklı ve daha kararlı yarı-iletken polimer, daha yüksek güç dönüşüm verimi elde edilmesi amacıyla aktif tabakada kullanılacaktır. Ayrıca, bu malzemeler, daha fazla ışık yakalayarak daha yüksek verim sağlaması için geniş bant aralıklı polimerlerle kombine edilerek de kullanılmıştır. Sonuç olarak, üretilen ince-esnek fotovoltaik lifler, çok çeşitli yüzeylere uygulanabilecek, düşük maliyetli, yüksek sıcaklık gerektirmeyen ve kolay yöntemlerle üretilebilmiştir.Öğe 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, AyşeNovel 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.Öğe The Effect of Acid Treatment of PEDOT:PSS Anode for Organic Solar Cells(Ieee, 2015) Borazan, Ismail; Bedeloğlu, Ayşe; Demir, Ali; Carroll, DavidThe 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.
