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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 Electrospinning of PVDF nanofibers incorporated cellulose nanocrystals with improved properties(Springer, 2023) Aydemir, Deniz; Sozen, Eser; Borazan, Ismail; Gunduz, Gokhan; Ceylan, Esra; Gulsoy, Sezgin Koray; Bardak, TimucinPolyvinylidene fluoride (PVDF) nanofibers with cellulose nanocrystals (CNCs) were produced with the electrospinning technique at the CNC loading rates of 0.25, 0.50, 0.75, and 1 wt%. CNCs were obtained with acid hydrolysis of microcrystalline cellulose with 64 wt% sulfuric acid. The material properties of CNCs have been studied with scanning electron microscopy (SEM), transmission electron microscopy, atomic force microscopy, X-ray diffraction (XRD), thermal analysis (TGA), ultraviolet (UV-Vis) spectroscopy, and fourier transform infrared spectroscopy. The PVDF nanofibers with CNCs were produced by the electrospinning technique. The material characterization of neat PVDF and the PVDF-CNC nanofibers were investigated with XRD, TGA, FT-IR, and morphological properties with SEM. The morphological results showed that CNCs were observed as needle-shaped rods and lengths for CNCs were generally in the range of 25-50 nm and 150-300 nm. The crystallinity and crystal size of CNCs were calculated as 75% and 4.8 nm, respectively. CNCs showed the decomposition stages at 100-250 degrees C and 300-375 degrees C for the evaporation of the water and decomposition reactions of cellulose, respectively. CNCs exhibited a weak absorbance at 265 nm according to the UV-Vis. As seen in the results of the nanofibers, it was found that CNCs generally decreased the diameters of the nanofibers obtained with the electrospinning when the loading rates of CNCs were raised. The presence of CNCs generally improved the thermal stability of the nanofibers. XRD results showed that crystallinity generally increased with adding CNCs. In FT-IR spectra, any difference was not detected among the PVDF-CNC nanofiber spectra.Öğe Electrospinning of PVDF nanofibers incorporated cellulose nanocrystals with improved properties (vol 30, pg 885, 2023)(Springer, 2023) Aydemir, Deniz; Sozen, Eser; Borazan, Ismail; Gunduz, Gokhan; Ceylan, Esra; Gulsoy, Sezgin Koray; Bardak, Timucin[Abstract Not Available]Öğe Enhanced Piezoelectric Performance of Poly(Vinylidene Fluoride) Nanocomposites with Synthesized Zinc Oxide Nanowires and Branched Carbon Nanotubes via Melt Mixing Process(Wiley-V C H Verlag Gmbh, 2025) Kaplan, Muesluem; Alp, Emre; Borazan, Ismail; Krause, Beate; Poetschke, PetraThis study presents the development of high-performance poly(vinylidene fluoride) (PVDF) based piezoelectric nanocomposites incorporating branched carbon nanotubes (bCNTs) and zinc oxide nanowires (ZnO NWs) through a scalable melt mixing process. ZnONWs with uniform morphology (mean diameter: 36.5 nm) are successfully synthesized and characterized. FTIR analysis confirms that incorporating bCNTs into PVDF significantly enhances the beta-phase content, while adding ZnO NWs (1-10 wt.%) resulted in progressive intensification of beta-phase characteristic peaks, with higher ZnO content showing stronger electroactive phase formation. The optimized composition (PVDF/0.5 wt.% bCNTs/5 wt.% ZnO NWs) demonstrates superior piezoelectric performance with a power density of 5.62 mu W cm-2, voltage output of 1.55 V, and current output of 14.48 mu A. Moreover, the composite exhibits excellent mechanical properties with a tensile strength of 48 MPa and maintains stable performance under cyclic loading. The enhanced performance is attributed to the synergistic effect between bCNTs and ZnO NWs, optimal beta-phase formation, and efficient charge transfer pathways. This study demonstrates the potential of melt-mixed PVDF nanocomposites for practical energy harvesting applications.Öğe Functional Properties of Electrospun Polymer Mats Coated With SWCNTs by a Simultaneous Electrospraying Process(John Wiley and Sons Inc, 2026) Krause, Beate; Staudinger, Ulrike; Lötsch, Julia; Fischer, Dieter; Göbel, Michael Wilhelm; Borazan, IsmailAn one-step procedure of simultaneous electrospraying and electrospinning is employed to produce fiber mats of a poly(vinylidene fluoride) (PVDF)/thermoplastic polyurethane (TPU) blend and polylactide (PLA) coated with singlewalled carbon nanotubes (SWCNTs). Thermoelectric investigation of the mats yielded Seebeck coefficients of 21–27 µV·K?1 that are almost independent of the SWCNT content and the polymer type. Control measurements using SWCNT buckypapers reveals that the thermoelectric properties of the SWCNTs is mostly determined by n-type doping effect of the solvents and additives used for electrospraying; the polymer nanofibers act mostly as porous mechanical support. Gas sensing experiments using PVDF/TPU and PLA-based electrospun mats containing 0.25 wt% SWCNTs exposed to saturated acetone vapor demonstrate a significant sensor response (change in resistance) for both polymers. Sensor recovery is more effective in the PLA-based mats compared to the PVDF-based one. In cyclic tests with short exposure times, both mats show highly stable and reproducible sensing behavior. The sensing mechanism is primarily driven by interactions between the solvent molecules and the SWCNTs (charge transfer) rather than by interactions with the polymer matrix (e.g., polymer swelling). © 2026 The Author(s). Macromolecular Materials and Engineering published by Wiley-VCH GmbH.Öğe Investigation of continuous PAN nanofiber yarn produced with polymer additives(Taylor & Francis Ltd, 2023) Borazan, IsmailNanofiber yarns were produced by electrospinning technique from polyacrylonitrile (PAN), thermoplastic polyurethane (TPU) added and polyvinylidene fluoride (PVDF) added PAN polymer solutions. The effects of the other polymers as additive to PAN nanofiber yarn are investigated. SEM, stress-strain characterizations were carried out. A sample plain fabric was woven from PAN nanofiber yarns to show that nanofiber yarns are feasible and can be integrated into conventional textile structures. Addition of the other polymers has increased the Young modulus by 40%, whereas TPU addition has increased the tenacity by 50% but TPU + PVDF addition has decreased the tenacity by half of only PAN. Breaking elongation was slightly decreased by the addition of TPU and PVDF polymers.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 Self-standing piezoelectric nanogenerator fabrics from ZnO-doped PVDF nanofiber yarns(John Wiley and Sons Inc, 2024) Borazan, Ismail; Çelik Bedeloğlu, AyşeToday a wide variety of wearable electronics are in our daily lives and their uses are increasing. The development of portable, flexible, lightweight, cost-effective, and stable devices that produce sustainable energy with renewable approaches in the field of wearable electronics, as in every field, is one of the important issues of today. According to their volume and weight, the use of nanofibers with high surface area in energy-generating devices may bring them advantages such as lightness and higher energy density. Therefore, in recent years, researchers have focused on the development of nanofiber-based nanogenerators that produce energy using mechanical energy in a sustainable and renewable way. In this paper, self-standing piezoelectric nanogenerator (PENG) fabrics were obtained by developing flexible composite poly(vinylidene fluoride) (PVDF) nanofiber yarns doped with zinc oxide (ZnO) nanoparticles at different rates to provide higher power output. It has been characterized from electromechanical, structural, and morphological aspects. The most successful self-standing PENG fabric obtained (at 5% ZnO loading) doubled the energy output of the fabric made from pure PVDF nanofiber yarn and provided a peak total power of 81 ?W and a power density of 30 ?W/cm2. The present results open up the field for the development of PVDF/ZnO-based nanomats and their use in sensors and actuators in the healthcare and engineering industries. © 2023 The Authors. Journal of Applied Polymer Science published by Wiley Periodicals LLC.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.
