Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 5Citation - Scopus: 4The Effect of Annealing Temperature on the Optical Properties of a Ruthenium Complex Thin Film(Elsevier Ltd., 2016) Ocakoğlu, Kasım; Okur, Salih; Aydın, Hasan; Emen, Fatih MehmetThe stability of the optical parameters of a ruthenium polypyridyl complex (Ru-PC K314) film under varying annealing temperatures between 278 K and 673 K was investigated. The ruthenium polypyridyl complex thin film was prepared on a quartz substrate by drop casting technique. The transmission of the film was recorded by using Ultraviolet/Visible/Near Infrared spectrophotometer and the optical band gap energy of the as-deposited film was determined around 2.20 eV. The optical parameters such as refractive index, extinction coefficient, and dielectric constant of the film were determined and the annealing effect on these parameters was investigated. The results show that Ru PC K314 film is quite stable up to 595 K, and the rate of the optical band gap energy change was found to be 5.23 × 10- 5 eV/K. Furthermore, the thermal analysis studies were carried out in the range 298-673 K. The Differential Thermal Analysis/Thermal Gravimmetry/Differantial Thermal Gravimmetry curves show that the decomposition is incomplete in the temperature range 298-673 K. Ru-PC K314 is thermally stable up to 387 K. The decomposition starts at 387 K with elimination of functional groups such as CO2, CO molecules and SO3H group was eliminated between 614 K and 666 K.Article Citation - WoS: 1Citation - Scopus: 1Improvement of Anode/Htl Interface Properties Using Self-Assembled Monolayer in Organic Electronic Devices(Polish Academy of Sciences, 2013) Yaman, M.; Yağmurcukardeş, Nesli; Havare, A. Kemal; Aydın, H.; Ocakoğlu, Kasım; Okur, SalihFabrication and characterization of highly effcient organic light-emitting diode with surface modification of indium tin oxide anodes by using self-assembled monolayer technique have been studied. Four different self-assembled molecules, K-28 ruthenium complex, octadecylamine hydrochloride, octadecyltrichlorosilane and mercaptohexdecanoic acid are used to modify ITO surface to improve the interface properties. Space charge limited currents measurements have been used to evaluate carrier mobility under steady state current. The results show that the surface properties such as the stability of ITO anode layer have significant effects on charge injection in organic light-emitting diode devices.Article Citation - WoS: 5Citation - Scopus: 6New Approach for Consideration of Adsorption/Desorption Data(Elsevier Ltd., 2011) Baleanu, Mihaela Cristina; Nigmatullin, Raoul R.; Okur, Salih; Ocakoğlu, KasımIn this paper we proposed a new approach to modify the Langmuir model by considering nonlinear effects such as diffusion of water molecules in/out of an adsorbing film for humidity adsorption and desorption kinetics. The model was tested on the humidity adsorption and desorption data of a spin coated 50. nm thick Ruthenium polypridyl complex (Ru-PC K314) film, measured under relative humidity between 11% and 97% using by Quartz Crystal Microbalance (QCM) technique. © 2011 Elsevier B.V.Article Citation - WoS: 36Citation - Scopus: 37Humidity Sensing Properties of Novel Ruthenium Polypyridyl Complex(Elsevier Ltd., 2010) Ocakoğlu, Kasım; Okur, SalihWe report the characterization of novel ruthenium polypyridyl complex (Ru-PC) based sensor film with a thickness of 50 nm coated on a quartz substrate using a spin coating method for humidity detection. The resulting complex [Ru(L1)2(L2)] was synthesized in a one-pot reaction starting from [RuCl2(p-cymene)]2, where the ligands (L1 = 4,7-diphenyl-1,10-phenanthroline-disulfonic acid disodium salt and L2 = 4,4′-dicarboxy-2,2′-bipyridine) were characterized by NMR, mass spectrometry (MALDI), elemental analysis and UV-vis spectroscopy. The humidity adsorption and desorption kinetics of the ruthenium complex were investigated using the Quartz Crystal Microbalance (QCM) technique. The Langmuir model was used to determine adsorption and desorption rates and Gibbs free energy over the 11-97% relative humidity range. Our experimental results show that Ru-PC films have a great potential for humidity sensing applications at standard conditions (i.e. room temperature). © 2010 Elsevier B.V. All rights reserved.Article Citation - WoS: 19Citation - Scopus: 19Systematic Tuning the Hydrodynamic Diameter of Uniformed Fluorescent Silica Nanoparticles(American Chemical Society, 2011) Durgun, Gülay; Ocakoğlu, Kasım; Özçelik, SerdarWe report a facile method for systematic tuning the hydrodynamic diameter of uniformed fluorescent silica particles in the size range from 12 to 465 nm. Dynamic light scattering and electron microscopy studies demonstrate that the hydrodynamic size distribution of the silica particles is uniform. We show that the initial amounts of ethanol and ammonia are essential to tune the size of these particles. The hydrodynamic diameter of such a particle increases as the amount of ammonia is increased. On the other hand, an increase in the amount of ethanol leads to the formation of smaller particles. Higher initial amount of ethanol yield an increase in the concentration of ethoxide ions and a decrease in the concentration of hydroxide ions. Such control over the concentration of hydroxide ion, which is responsible for the formation of siloxane bonds, causes a controlled-growth of the silica particles, resulting in precise tuning the hydrodynamic size. We confirm that a linear relationship exists between size and brightness of particles, demonstrating that the amount of dye molecules in such particles can be regulated by the presented method. We prove that the silica network provides protection for dye molecules encapsulated in particles against solvents, fluorescence quenchers, and unfavorable pH of environments. Moreover, the fluorescent silica particles with the size of 12, 50 and 250 nm were found to not be cytotoxic against the epithelial cell lines of MCF7 and PC3 even when the dosage levels up to 1.0 mg/ml and incubation periods up to 72 hours were applied.