Burak Y . Kadem - Academia.edu (original) (raw)

Papers by Burak Y . Kadem

A novel pressure sensor, PVA:PEDOT:PSS: carbon-based nanocomposites has been characterized by dif... more A novel pressure sensor, PVA:PEDOT:PSS: carbon-based nanocomposites has been characterized by different physical analyses and measurements. Through SEM and optical images, we notice that carbon-based materials to the PVA/PEDOT: PSS solutions change the shape of the surface and its mechanical characteristics in addition to the change of resistance and be the highest possible at carbon black (7.98 x 10-1). XRD results show that the PVA/PEDOT:PSS: MWCNTs composite has the highest value of the strain (s=-0.0753) and the lowest value for grain size (G = 1.03456 nm). The adhesion properties, the casted drops solutions have high adhesion properties.

In this paper, AC and DC electrical properties of organic solar cells based on P3HT:PCBM active l... more In this paper, AC and DC electrical properties of organic solar cells based on P3HT:PCBM active layer have been investigated. The performance of such solar cell has demonstrated the efficiency of 2.31% corresponding with short-circuit current density of 6.08 mA • cm −2 , open circuit voltage of 0.64 V and fill factor of 60%. The equivalent circuit and the properties of the supposed interfaces between the layers in the P3HT:PCBM-based solar cell have been estimated. AC properties have demonstrated series capacitance increasing with increasing frequencies, which means series capacitance saves charges and parallel capacitance has decreased with increasing of frequency work as discharge part of charges stored in series capacitance. Also, equivalent series and parallel resistances have demonstrated a decrease from 7 Ω and 120 kΩ at low frequency to 1 Ω and 43 kΩ at high frequencies, respectively.

The present work is a detailed study of the poly(3,4-ethylenedioxyt hiophene):poly(styrenesulfona... more The present work is a detailed study of the poly(3,4-ethylenedioxyt hiophene):poly(styrenesulfonate) PEDOT:PSS films, were made to undergo different treatments to examine how they affected morphology, conductivity, transmittance, as well as the relative effect of the way the organic photovoltaic devices performed. This was done by using the PCPDTBT:PC 71 BM:SWCNTs and PCPDTBT:PC 61 BM mixtures. The process involves using DMSO and EG solvents for doping PEDOT:PSS and separately exposing the films to the vapour of ammonium hydroxide (NH4OH) solvent. After doping solvent was added to the PEDOT:PSS solution, , the conductivity and transmittance of PEDOT:PSS experienced a substantial increment, after which solvent treatment was performed by subjecting these films to NH4OH solvent. When devices were doped using PCPDTBT:PC 71 BM:SWCNTs or PCPDTBT:PC 61 BM with power conversion efficiency, The optimal organic photovoltaic devices achieved a 3.68% as compared to 2.20% for pristine PV devices or 2.67% instead of 1.51% for pristine devices, respectively. The solvent treatment played a significant part in enhancing conductivity in PEDOT:PSS films.

Introduction Photocurrent devices, essential for converting light into electrical current, are co... more Introduction Photocurrent devices, essential for converting light into electrical current, are considered significant in light-toenergy conversion processes. Among the various photocurrent technologies, thin film structures have been recognized as attractive options for achieving highperformance and cost-effective solutions [1]. Remarkably, thin films like titanium dioxide (TiO 2) and zinc oxide (ZnO) have gained value due to their lightweight, cost-effectiveness, and uses in multiple applications [2,3]. Furthermore, heterojunctions like ZnO/TiO 2 have shown a good chance of enhancing photo-conversion efficiency [4]. In addition, studying the thin films' time-dependent properties will lead to a possible advancement of photocurrent devices. The solgel method, a widely recognized technique for fabricating thin film structures, allows for meticulous

In the present work, novel composite thin films are investigated and applied as active layers in ... more In the present work, novel composite thin films are investigated and applied as active layers in organic solar cells with improved performance. The novel composite materials are based on blends of poly(3-hexylthiophene-2,5diyl) (P3HT) with phenyl-C61-butyric acid methyl ester (PCBM) with the addition of symmetrically substituted zinc(II) phthalocyanine derivative bearing eight polyoxyethylene substituents (ZnPc-0py) or pyrene containing asymmetric zinc phthalocyanine (ZnPc-1py). The study of these novel composites in organic solar cells was carried out in two stages; firstly P3HT:ZnPc-0py and P3HT:ZnPc-1py were used as sensitizer layers between the active layer and PEDOT:PSS which has resulted in a declined power conversion efficiency compared to a P3HT:PCBM reference device. In the second stage ZnPc-0py and ZnPc-1py derivatives were used separately as a component in ternary blends within a mixture of poly(3-hexylthiophene-2,5-diyl) (P3HT) and [6,6]-phenyl C61 butyric acid methyl ester (PCBM) (P3HT-PCBM in the ratio of 1:1) as an OSC active layer P3HT:PCBM. The photovoltaic characteristics of thin films of these blends have been investigated and optimum performance of ternary OSC devices has been identified. A ternary organic solar cell comprising P3HT:PCBM:ZnPc-1py as the active layer has demonstrated a power conversion efficiency as high as 2.96%, with fill factor of 57%, short circuit current density of 8.14 mAcm −2 and open circuit voltage of 0.64 V.

Thin films of P3HT (3-hexylthiophene-2,5-diyl):PCBM(phenyl-C61-Butyric-Acid-Methyl Ester) and P3H... more Thin films of P3HT (3-hexylthiophene-2,5-diyl):PCBM(phenyl-C61-Butyric-Acid-Methyl Ester) and P3HT:PCBM and P3HT:ICBA (indene-C 60 bisadduct) blends with different volume ratios (1:1, 1:2 and 1:3) were successfully prepared using a spin coating technique. Atomic force microscopy (AFM) along with X-ray diffraction (XRD) were utilized to examine the morphological and the crystal structural characterization of the prepared thin films. The capacitance-voltage (C-V) and conductance-voltage (G-V) characteristics were evaluated at a fixed frequency with rang of applied voltage from (−2 up to 2 V). The Mott-Schottky analysis was applied to C-V measurements of P3HT: PCBM, ICBA bulk heterojunction solar cells. The doping densities and built-in voltages were determined as significant implications to understand the physics of these devices. The potential difference between the Fermi level and the bottom of the HOMO level in the p-type organic semiconductor as well as the barrier height were determined. The capacitance-frequency (C-F) and conductance-frequency (G-F) were measured in the range of 0 Hz to 100 MHz at room temperature and then, the number of the interface states due to the depletion was determined.

Polyvinyl alcohol (PVA) has been prepared as a films with different volume ratios of titanium dio... more Polyvinyl alcohol (PVA) has been prepared as a films with different volume ratios of titanium dioxide (TiO2). Atomic force microscope (AFM) was used to test morphology and grain size of the specimen surfaces. The results revealed that the surface roughness of specimen decreased with increasing the ratio of TiO2 whereas the grain size was increased. The stress-strain curves for TiO2/PVA composite films with 0%, 0.02%, 0.03%, and 0.04% TiO2 content are characterized. The mechanical performance of the TiO2/PVA composite films was clearly affected according to loaded TiO2 contrast to that of the pure film. Furthermore, the titanium dioxide (TiO2)/polyvinyl alcohol (PVA) composite samples examined as a shielding material of gamma ray. linear attenuation coefficient was measured by using the Cesium-137 (Cs-137) and gamma-ray photons 662 keV as a radioactive source. It was shown that the efficiency of shielding material increased with increasing the loaded amount of TiO2.

Simple method has been used to determine the absence of heavy metals in an aqueous solution. Fluo... more Simple method has been used to determine the absence of heavy metals in an aqueous solution. Fluorescein was used as the base colorimetric materialThis was doped with CuCl 2 and the final solution showeda clear change in color. This change was correlated with the change in both pH and electrical conductivity of the solution. The optical property as an obvious change of the spectra was observed. Therefore, this simple method could be proposed as a method to detectheavy metals in any solution.

Your article is protected by copyright and all rights are held exclusively by Springer Nature B.V... more Your article is protected by copyright and all rights are held exclusively by Springer Nature B.V.. This e-offprint is for personal use only and shall not be self-archived in electronic repositories. If you wish to self-archive your article, please use the accepted manuscript version for posting on your own website. You may further deposit the accepted manuscript version in any repository, provided it is only made publicly available 12 months after official publication or later and provided acknowledgement is given to the original source of publication and a link is inserted to the published article on Springer's website. The link must be accompanied by the following text: "The final publication is available at link.springer.com".

Your article is protected by copyright and all rights are held exclusively by Springer Science+Bu... more Your article is protected by copyright and all rights are held exclusively by Springer Science+Business Media, LLC, part of Springer Nature. This e-offprint is for personal use only and shall not be self-archived in electronic repositories. If you wish to selfarchive your article, please use the accepted manuscript version for posting on your own website. You may further deposit the accepted manuscript version in any repository, provided it is only made publicly available 12 months after official publication or later and provided acknowledgement is given to the original source of publication and a link is inserted to the published article on Springer's website. The link must be accompanied by the following text: "The final publication is available at link.springer.com".

In this work, the structural features and sensor response toward ammonia of a three dimensional (... more In this work, the structural features and sensor response toward ammonia of a three dimensional (3D) SWCNTs material covalently functionalised with 1,6-diethynylpyrene were studied. The target SWCNTs hybrid material was prepared by the reaction of azido substituted SWCNTs with 1,6-diethynylpyrene containing double terminal alkyne groups via the azide-alkyne Huisgen cycloaddition (Click) reaction. The structure of the 1,6-diethynylpyrene compound was determined by different spectroscopic methods such as FT-IR, 1 H NMR, MALDI-TOF mass and UV-vis, while its SWCNT-Pyrene 3D hybrid material was characterized by FT-IR, Raman, UV-vis spectroscopies and thermogravimetric analysis. The morphology of the hybrid films was investigated by scanning electron microscope (SEM) and transmission electron microscope (TEM). The sensing performance of the SWCNT-Pyrene 3D hybrid material was studied against low-concentrations of NH 3 in the range of 0.1-40 ppm by measuring changes in the films' conductivity at different levels of relative humidity. The reversible electrical sensor response toward ammonia was observed both in the case of SWCNT and SWCNT-Pyrene 3D hybrid films, however the response values of SWCNT-Pyrene 3D hybrid film were higher than those of SWCNT.

Thin films of fluorinated chromium phthalocyanine were prepared using spin coating techniques and... more Thin films of fluorinated chromium phthalocyanine were prepared using spin coating techniques and annealed at 100, 200, 300, and 400 • C. The prepared films were investigated using UV-Visible absorption spectroscopy, Raman spectroscopy, and atomic force microscopy. The band gap characteristics were evaluated to study the difference electronic transitions between the prepared thin films under different annealing temperatures. Films were exposed to ammonia vapor in a concentration range of 40-100 ppm to demonstrate the gas sensing activity of prepared devices. Resistance versus voltage behavior was investigated upon the exposure of ammonia gas and the samples show an increase in the resistance towards the existence of ammonia molecules. The dependency of the sensors on time was studied to evaluate the response and recovery time, which were found to be 10 and 13 s respectively.

The synthesis and characterization of new hybrid materials based on reduced graphene oxide (rGO) ... more The synthesis and characterization of new hybrid materials based on reduced graphene oxide (rGO) or single walled carbon nanotubes (SWCNTs) covalently functionalized by 4,4'-difluoro-8-(4-propynyloxy)phenyl-1,3,5,7-tetramethyl-4-bora-3a,4a-diaza-s-indacene (BODIPY) (2) or 7-(prop-2-yn-1-yloxy)-3-(3',4',5'-trimethoxyphenyl)-coumarin (4) as light harvesting groups have been described. The organic solar cell performances of these novel nanomaterials in P3HT:PCBM blends were investigated. These covalently bonded hybrid materials (reduced graphene oxide:BODIPY (GB), reduced graphene oxide:Coumarin (GC), SWCNTs:BODIPY (CB) and SWCNTs:Coumarin (CC)) were prepared by an azide-alkyne Huisgen cycloaddition (click) reaction between the azide bearing SWCNTs or rGO and terminal ethynyl functionalized BODIPY (2) or coumarin (4) derivatives. The formation of novel nanomaterials was confirmed by FT-IR, UV-Vis and Raman spectroscopies and thermogravimetric analysis. The best performance on P3HT:PCBM organic solar cells was produced by SWCNTs:Coumarin (CC) hybrids which were coated on an indium tin oxide coated polyethylene terephthalate film (ITO-PET). The reference device based on the P3HT:PCBM blend without CC showed a power conversion efficiency (PCE) of 1.16%, an FF of 35% and a short-circuit current density (J sc) of 5.51 mA cm −2. The reference device with CC hybrids within the P3HT:PCBM blend increased the values significantly to 1.62% for PCE, 40% for FF and 6.8 mA cm −2 for J sc. † Electronic supplementary information (ESI) available. See

Zink oxide thin films were prepared using different wet-processing techniques to study the morpho... more Zink oxide thin films were prepared using different wet-processing techniques to study the morphological and optoelectronic properties. Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) have been utilized to study the effect of technique and preparation procedure on the morphology of the films. The spin coated ZnO layers have exhibited ripple-shaped morphological features. Using the growth process with ZnCl 2 and Al(NO 3) 3 doping at different time has shown a change in surface morphology. UVeVisible absorption spectroscopy was used to understand the absorption behaviour and so to calculate the energy gap (E g) for the films produced. It has been revealed that E g of the ZnO thin film increases with the increasing of the number of layers spun onto the substrate. ZnCl 2 doping has no quite big change in E g values, however, Al(NO 3) 3 has resulted in a higher E g value.

The study shows how the solution processed bulk-heterojunction solar cells can exhibit better per... more The study shows how the solution processed bulk-heterojunction solar cells can exhibit better performance on the basis of a low-bandgap polymer combined with a fullerene derivative. Co-solution is used to blend the dopant single-walled carbon nanotubes (SWCNTs) with poly (3-hexyl thiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) at 0% to 1% concentrations. We use Carrier mobility measures to show that an increase in doping concentration causes an increase in hole conductivity and mobility. This was shown in the XRD studies and established through the absorbance spectra that shows the specific 600 nm shoulder. The study demonstrates that it is possible to improve the open circuit voltage and short circuit current of the relevant solar cells by doping at a concentration of 0.5%, which leads to increased power conversion efficiencies. The improvement in performance is explained with respect to trap filling because of the higher carrier density and lower recombination that is associated with better mobility.

Simple method has been used to determine the absence of heavy metals in an aqueous solution. Rhod... more Simple method has been used to determine the absence of heavy metals in an aqueous solution. Rhodamine is used as the base colorimetric material, this has been doped with CuCl2, CrCl2, NiCl2 and the final solution has shown a clear change in the color. This change is correlated with a clear change in both pH and electrical conductivity of the solution and in the optical property where an obvious change in the spectra has been observed. Therefore, the simple method could be proposed as a function of determining the heavy metal in solution.

Surface properties, crystallinity and optical properties of anodised titanium in mixture of βglyc... more Surface properties, crystallinity and optical properties of anodised titanium in mixture of βglycerophosphate (β-GP) and calcium acetate (CA)