Graphene and graphene oxide-coated polyamide monofilament yarns for fiber-shaped flexible electrodes

In this study, polyamide monofilament yarn of 3000 tex was coated with graphene oxide (GO) nanomaterial using dip-coating method. The graphene oxide layer was then reduced with green chemical reduction method, resulting in a reduced graphene oxide-coated monofilament yarn. The properties of the graphene oxide and reduced graphene oxide-coated polyamide monofilament yarns were characterized by performing physical, electrical, optical, and morphological investigations. The lowest sheet resistance was measured from seven-layer graphene-coated polyamide monofilament yarn as 3.09 k?/sq. Moreover, it was measured that 90° and 180° bent seven-layer graphene-coated polyamide monofilament yarns had 3.57 and 3.81 k?/sq sheet resistance, respectively. Additionally, while PA monofilament yarn has 73.5% transmittance at 550 nm; seven-layer GO and seven-layer graphene have 18.8 and 4.5%, respectively, as expected. On the other hand, the contact angle increased with the reduction of graphene oxide layer on monofilament yarn. The fabricated graphene-coated polyamide monofilament yarns can be used in electrotextiles, solar cells, sensors, and OLEDs as fiber-shaped flexible electrodes. © 2018, © 2018 The Textile Institute.2015–02–004This work was supported by Bursa Technical University Scientific Research Project (BAP) [grant number 2015–02–004]

Properties of Biodegradable PVA/Sepiolite-Based Nanocomposite Fiber Mats

In this study, poly(vinyl alcohol) (PVA) nanocomposite fiber mats with sepiolite were prepared via electrospinning technique. The measurements of fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), contact angle, scanning electron microscopy (SEM), and atomic force microscopy (AFM) were used for the characterization. The effect of polymer/sepiolite ratio and heat treatment on the properties of samples was investigated. The heat treatment which decreased the solubility of nanofibers and the addition of sepiolite resulted in a decrease in nanofiber diameter, contact angle with water, and water drop spreading rate on the material, and also resulted in an increase in water drop spreading rate inside the material. (C) 2014 Society of Plastics Engineer

Characterization of organic solar cells using semiconducting polymers with different bandgaps

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 Isc significantly, and when combined with P3HT, a higher Voc was obtained. © 2019 Walter de Gruyter GmbH, Berlin/Boston 2019

Optical modeling of fiber organic photovoltaic structures using a transmission line method

An optical model has been developed and evaluated for the calculation of the external quantum efficiency of cylindrical fiber photovoltaic structures. The model is based on the transmission line theory and has been applied on single and bulk heterojunction fiber-photovoltaic cells. Using this model, optimum design characteristics have been proposed for both configurations, and comparison with experimental results has been assessed. (C) 2017 Optical Society of Americ