Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Synthesis, Characterization, Crystal Structure, Electrochemical and Photoluminescence Properties, Dft and Molecular Docking Studies, and Antimicrobial Activities of Two Mononuclear Nickel (II) Complexes With Pyrazole-Derived Ligands(Elsevier, 2025) Amin, Mina A.; Diker, Halide; Sahin, Onur; Varlikli, Canan; Soliman, Ahmed A.Two octahedral nickel complexes; [Ni(fdtp)2(DMF)2] (1) and [Ni(dcdtp)2(DMF)2] (2), based on 4-((3-fluorophenyl)diazenyl)-3-(trifluoromethyl)-1H-pyrazol-5-ol (fdtp) and 4-((2,4-dichlorophenyl)diazenyl)-3-(trifluoromethyl)-1H-pyrazol-5-ol (dcdtp) were synthesized. The complexes were characterized spectroscopically (FTIR, UV-Vis, Photoluminescence), Mass spectrometry, elemental analyses, electrochemically, thermally, and through Single-crystal X-ray investigations. The formation of the complexes was confirmed by the existence of Ni-O and Ni-N vibrations at bonds were observed as weak bands at 526-497 and 470-438 cm-1. According to the thermogravimetric analyses, the complexes were thermally stable and had relatively high activation energies (585.81 and 730.07 kJ mol-1 for 1, and 2, respectively). Cyclic voltammograms showed that the anodic potential region of 1 and 2 exhibited two irreversible oxidation peaks at 1.34 V &1.55 V and 1.41 V & 1.63 V, respectively, attributed to metal-localized oxidation. The complexes showed enhanced antibacterial activities compared to free ligands and comparable to the standard. The inhibition zones exhibited via 1 were about 21.7, 19.3, and 26.7 mm versus Escherichia coli (E. coli), Staphylococcus aureus (S. Aureus), and Bacillus Subtits (B. Subtits), respectively. Docking studies supported the antibacterial investigations; the binding energies of the complexes were -8.81 and -9.69 kcal/mol for 1 and 2 respectively, against E. coli (PDB ID: 6F86).Article Citation - WoS: 2Citation - Scopus: 2New Copper and Cobalt Complexes Based on a Fluorinated Pyrazole Derivative, Synthesis, Characterization and Antibacterial Activity(Wiley, 2025) Amin, Mina A.; Diker, Halide; Sahin, Onur; Varlikli, Canan; Soliman, Ahmed A.Two copper and cobalt complexes based on 3-(trifluoromethyl)-4-((3-(trifluoromethyl)phenyl)diazenyl)-1H-pyrazol-5-ol (Httdp) have been prepared and characterized using different physicochemical techniques. The crystal structure of the copper complex has been proven to be a square pyramidal, and the cobalt complex has an octahedral structure. DFT calculations of the complexes were performed, and the energy gaps between the HOMO-LUMO of the complexes (-3.38676 to -3.18138 eV) and the Cu (II) complex reflect a higher relative stability compared with Httdp and the Co (II) complex. The antibacterial activities of the two complexes were evaluated. The Co (II) complex demonstrated the highest antibacterial activity against various bacteria compared with Httdp and the Cu (II) complex. The mean inhibition zones exhibited by the Co (II) complex showed the highest activities toward the Gram-negative bacterial strains with mean inhibition zones of 30.3 +/- 0.6 (Staphylococcus aureus) and 25.7 +/- 0.6 (Bacillus subtilis) mm. Docking studies were carried out using S. aureus tyrosyl-tRNA synthetase (PDB ID: 1JIJ) to assess the antimicrobial activities, proving that the complexes were efficient for the protein.Article Improving the Device Stability by Controlling the Morphology of Quantum Dot Emissive Layer Via a Coating Process in Blue Qleds(Wiley-v C H verlag Gmbh, 2024) Diker, Halide; Ozguler, Sahika; Unluturk, Secil Sevim; Ozcelik, Serdar; Varlikli, CananBlue light-emitting CdSe@ZnS/ZnS quantum dot (QD) nanoparticles (NPs) were synthesized and their photophysical properties in both solution and film phases were investigated. The morphological properties of films prepared by different coating methods i. e. single layer coating from low to high concentrations of QD solutions and layer-by-layer (multilayer) coating within constant low QD solution concentration, were also examined in detail. Varying the concentration (1-10 mg/mL) and the number of layers (from 1-16) did not essentially affect the photophysical properties of QD films, although it resulted in a direct increment in QD film thickness. The concentration and layer-dependent films were used as an emissive layer (EML) in QD light-emitting diodes (QLEDs). Although the "6 mg/ml(-1) Layer" QD EML-based device exhibited relatively high device efficiency compared to the "1 mg/ml(-10) Layers" based one at working voltage region, it had similar to 2-fold higher efficiency roll-off at high voltage region. The performance differences for both devices with the same QD EML thickness were attributed to the morphological variations for the QD layer in terms of surface roughness, void density, aggregates/clusters, and trap sites that were directly related to the charge injection balance and Auger recombination.Article Citation - WoS: 14Citation - Scopus: 14Dispersion Stability of Amine Modified Graphene Oxides and Their Utilization in Solution Processed Blue Oled(Elsevier Ltd., 2020) Diker, Halide; Bozkurt, Hakan; Varlıklı, CananGraphene oxide (GO) was modified with amine derivatives which contain short (SACA) and long (LACA) alkyl chains. SACAs were n-propylamine, dipropylamine, propanolamine and LACAs were 2-ethylhexylamine, di-hexylamine, dioctylamine, and 1,12-diaminododecane and modified GOs (mGOs) were named as nPRYLA-GO, DPRYLA-GO, PRPOHA-GO, 2EHA-GO, DHA-GO, DOA-GO, and DADOD-GO, respectively. Amine modification resulted in approximately 2-folds of decrement in d-spacing of GO (8.36 angstrom). The C:O ratio, N% and d-spacing values were increased as the alkyl chain length of amine source increased. Except for PRPOHA-GO, all of the mGOs were thermally stable until 100 degrees C. All mGOs were dispersed in dimethylformamide (DMF), ethylene glycol (EG) and isopropyl alcohol (iPA). Regardless of their structural differences, all of the mGOs formed stable dispersions in DMF, whereas SACA-mGOs and LACA-mGOs were compatible with EG and iPA, respectively. DMF, EG and iPA dispersions of DOA-GO, 2EHA-GO, nPRYLA-GO and PRPOHA-GO were doped in Al4083 and prepared composites were utilized as hole transport layer in solution processed blue OLEDs. Ground state energy levels of Al4083:DOA-GO, Al4083:EG, Al4083:PRPOHA-GO, Al4083:2EHA-GO and Al4083:nPRYLA-GO extracted from their X-ray photoelectron spectra were 0.49 eV, 0.67 eV, 0.91 eV, 0.98 eV and 1.00 eV below the work function of ITO, respectively. Among all Al4083:mGOs, the best device performance was obtained with the device that contains Al4083:DOA-GO (in EG), which presented 1.6, 1.7 and 1.5 fold enhancements in current, power and external quantum efficiencies, respectively, compared to those of Al4083:EG based device.Article Citation - WoS: 8Citation - Scopus: 8Reducing the Efficiency Roll Off and Applied Potential-Induced Color Shifts in Cdse@zns/Zns-based Light-Emitting Diodes(American Chemical Society, 2020) Özgüler, Şahika; Diker, Halide; Ünlütürk, Seçil Sevim; Özçelik, Serdar; Varlıklı, CananGreen light-emitting CdSe@ZnS/ZnS (QD) nano-particles were synthesized; the photophysical and morphological properties of their films, which were prepared by spin coating from six different concentrations, corresponding to absorbance values of 0.6, 1.1, 1.6, 2.1, 2.8, and 4.0, were determined. Increasing the absorbance value from 0.6 to 4.0 did not change the photophysical properties of QD films to a large extent, whereas it resulted in an increment in QD film thickness from 20 to 110 nm. The films were utilized as an emissive layer in QD light-emitting diodes with poly(9-vinylcarbazole) (PVK), PVK:2-(4-biphenyllyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (PBD), and PVK:1,3-bis[(4-tert-butylphenyl)-1,3,4-oxadiazolyl]-phenylene (OXD-7) hole-transport layers (HTLs). The presence of PBD or OXD-7 in PVK reduced the efficiency values but played a positive role in the color purity and efficiency roll off. The maximum color temperature and electroluminescence wavelength shifts obtained with applied potential were 109, 50, and 50 K and 11, 5, and 5 nm for pure-PVK, PVK:PBD, and PVK:OXD-7-based devices, respectively. Hole mobility, capacitance (at 10(3) Hz), and charge-transfer efficiency values were 9.0 x 10(-7), 6.8 x 10(-7), and 4.2 x 10(-7) cm(2) V s(-1), 1.7, 1, and 1 nF, and 6.90%, 15.50%, and 16.10% for pure-PVK, PVK:PBD, and PVK:OXD-7-based devices, respectively. Enhanced color purity and lowered efficiency roll off obtained with PVK:PBD and PVK:OXD-7 HTLs were attributed to decreased capacitance, increased charge-transfer efficiency, and reduced Joule heating.Article Citation - WoS: 5Citation - Scopus: 6Contribution of O-2 Plasma Treatment and Amine Modified Gos on Film Properties of Conductive Pedot:pss: Application in Indium Tin Oxide Free Solution Processed Blue Oled(Elsevier, 2019) Diker, Halide; Yeşil, Fatih; Varlıklı, CananPrimary (n-propyl amine, n-PRYLA), secondary (dipropyl amine, DPRYLA) and alcohol (propanol amine, PRPOHA) amine derivatives were used as amine sources in graphene oxide (GO) modification and obtained samples were named as nPRYLA-GO, DPRYLA-GO and PRPOHA-GO, respectively. Modified graphene oxide (mGO) derivatives were doped in poly (3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PH1000) and O-2 plasma treatment (70W, 3 min) was applied on the spin casted films. PH1000:mGO films presented high optical transparency values (> 90%) and low resistivity (177-183 Q/sq). The roughness values were increased especially when the hydrophobic alkyl chain containing DPRYLA-GO and nPRYLA-GO were doped in PH1000. Prepared films were utilized as anode in solution processed blue organic light emitting diode. PH1000:PRPOHA-GO anode presented more than 30 nm of decrement in full with at half maximum and 1.6, 1.5 and 1.9 fold enhancements in current, power and external quantum efficiency values, compared to those of ITO anode, respectively.Article Citation - WoS: 28Citation - Scopus: 29Enhancing the Efficiency of Mixed Halide Mesoporous Perovskite Solar Cells by Introducing Amine Modified Graphene Oxide Buffer Layer(Elsevier, 2020) Şahin, Çiğdem; Diker, Halide; Sygkridou, Dimitra; Varlıklı, Canan; Stathatos, EliasIn this study, graphene oxide (GO) was synthesized via Tour method and then modified with two different amine sources that contained different branched alkyl chains. The GO and modified GOs (mGOs) with dihexylamine (DHA) and 2-ethylhexylamine (2EHA) as amine sources were used respectively as buffer layers in mixed halide mesoporous perovskite solar cells (PSCs) in order to examine whether they could improve their performance. GO and mGO samples were characterized by several techniques such as X-Ray Diffraction, X-Ray photoelectron spectroscopy (XPS), Raman analysis and thermal gravimetric analysis (TGA). The preparation of the CH3NH3PbI3-xClx perovskite solution was performed using standard Schlenk techniques under argon atmosphere to attain a homogeneous coverage of the perovskite film. The solar cells with the additional layer of mGO derivatives between perovskite and hole transporting layer showed an improved overall performance compared to the reference devices which was attributed to the enhanced charge carrier transport via the mGOs. In particular, 10% increase to the overall performance of the solar cells was monitored in devices where 2-ethylhexylamine (2EHA) modified GO was used, compared to standard cell without buffer layer. (C) 2019 Elsevier Ltd. All rights reserved.Article Citation - WoS: 29Citation - Scopus: 32Enhanced Capacitive Behaviour of Graphene Based Electrochemical Double Layer Capacitors by Etheric Substitution on Ionic Liquids(Elsevier, 2020) Siyahjani, Shirin; Öner, Saliha; Diker, Halide; Gültekin, Burak; Varlıklı, CananIn this study, we report the effect of etheric substituents in imidazolium and ammonium based ionic liquids (IL) on the performance of electrochemical double layer capacitors (EDLC) consisted of gel polymer electrolyte (GPE) and reduced graphene oxide (RGO) electrode. GPEs contain poly (vinylidene fluoride-hexafluompropylene) (PVDF-HFP) and the ILs. Ammonium and imidazolium based ionic liquids (ILs) differ by their length of etheric groups and etheric group contents, respectively. According to the cyclic voltammetry, galvanostatic chargedischarge and electrochemical impedance spectroscopy measurements, longer etheric group substituted {N-methyl-2- (2-methoxyethoxy)-N,N-bis [2- (2-methoxyethoxy)ethyl] ethan-1-aminium bis(tri-fluoromethanesulfonyl)imide (AMEt-TFSI) and ether substituted (3-allyl-1-[2-(2-methoxyethoxy)ethyl]-1H-imidazole-3-ium bis(trifluommethanesulfonyeimide (AL3IL-TFSI), tender specific capacitances of 250 Fg(-1) and 238 Fg(-1) and energy density values of 61.36 wh kg(-1) and 61.56 wh kg(-1), respectively.Conference Object Citation - WoS: 3Citation - Scopus: 2Fabrication and Characterization of a Solution Processed Flexible Thermal Sensor by Using Chemically Synthesized Go and Rgo(Institute of Electrical and Electronics Engineers Inc., 2019) Bozkurt, Hakan; Diker, Halide; Varlıklı, CananGraphene oxide (GO) was reduced by ascorbic acid which is an environmental-friendly reductant and obtained sample was named as reduced GO (rGO). Stable dispersions of GO and rGO were prepared in N,N-Dimethylformamide (DMF). Compared to GO sample, rGO was determined to have more thermal stability, smaller sheet size and lower surface energy. GO and rGO dispersions were drop-casted on aluminum (Al) coated acetate substrate and used as thermal sensor. Fabricated sensors were tested from 25 °C to 150 °C. The sensors fabricated with GO, were not stabile against driven temperature changes. However, rGO ones, presented no thermal hysteresis effect after the first heating step. This sensor (Al/rGO/Al) acted like an NTC (Negative Temperature Coefficient) thermistor. The resistance of the rGO sensor was changed between 42 k? to 25 k? depending on the test temperature range (25 °C to 150 °C). Average beta value was calculated as 519.7649 K. © 2019 IEEE.Article Citation - WoS: 19Citation - Scopus: 20Controlling the Distribution of Oxygen Functionalities on Go and Utilization of Pedot:pss-Go Composite as Hole Injection Layer of a Solution Processed Blue Oled(Elsevier Ltd., 2017) Diker, Halide; Durmaz, Gamze Belkis; Bozkurt, Hakan; Yeşil, Fatih; Varlıklı, CananGraphene oxide (GO) was synthesis by Tour method. Particle size distribution effects of raw graphite on the resulting structural, morphological, optical and electrical properties of GO samples and their poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) composites are studied for the graphite particle distributions of <150, 45–75 and 25–45 μm. It is determined that particle size of raw graphite have an impact on oxidation degree, the chemical nature of oxygen functional groups on GO and it also affects the lateral size of obtained GO. PEDOT:PSS-GO composites are utilized as hole injection layer (HIL) in a solution process blue organic light emitting diode. Presence of GO caused negative differential resistance (NDR) and NDR intensity was decreased with the decrease in lateral size of GO, increase in the graphite particle size and carboxyl% of obtained GO. All PEDOT:PSS-GO composite based devices presented better performance than the bare PEDOT:PSS based reference device. The maximum luminous and external quantum efficiency values of the device that contain HIL of PEDOT:PSS-GO(150) were more than 40% and 50% higher than that of the reference, respectively. Two folds of increase in these performance values were able to be reached with the concentration optimization of GO/150 in PEDOT:PSS.