Browsing by Author "Peksöz, Ahmet"
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Item Analytical information on the asphaltenes from a few standard characterization techniques(Taylor & Francis, 2011-01) Peksöz, Ahmet; Akay, Sertan Kemal; Kaya, Yunus; Ovalıoǧlu, Hüseyin; Kaynak, Gökay; Yalçıner, Aytaç; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Kimya Anabilim Dalı.; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Anabilim Dalı.; AAG-9772-2021; R-7260-2016; 23100976500; 24801954600; 35181446100; 24460278400; 12042075600; 14055078800The asphaltene has been obtained from asphalt cement with penetration grade 60, which is extracted from crude Libya petroleum. The elemental composition and some structural properties of the asphaltene samples are determined by various methods, such as SEM, infrared spectroscopy, and X-ray analysis. Some experiments are performed on (1)H dynamic nuclear polarization (DNP) in a number of asphaltene suspensions in organic solvents. The frequency dependence of the DNP enhancement under conditions of weak EPR saturation in a low magnetic field is obtained and interpreted as the EPR line shape of some free radicals present in the samples.Item Asfalten - çözgen ortamlarında moleküller arası spin-spin etkileşmeleri(Uludağ Üniversitesi, 2013) Keser, Gökhan; Peksöz, Ahmet; Uludağ Üniversitesi/Fen Bilimleri Enstitüsü/Fizik Anabilim Dalı.Substitue edilmiş toluene süspansiyonlarında MC800 asfaltenleri ile 1H protonları arasında dinamik nükleer polarizasyon etkisi, 44,0 MHz’lik bir elektron uyarma frekansında ve oda sıcaklığında incelendi. Asfaltenler İran kaynaklı MC800 sıvı asfaltından elde edildi. Bu teknikte, difüzyona uğrayan çözgen moleküllerindeki çekirdek spinleri ile asfalten misellerinde bulunan çiftlenmemiş elektron spinleri manyetik olarak etkileşirler. Sinyal büyümesi, etkileşmenin dipolar ve skaler kısmı arasındaki rekabete bağlıdır. Bu etkileşmelerde, tüm süspansiyonlar için dipolar kısım baskındır. Çekirdek-elektron çiftlenme parametresi ρ, toluene, 2-fluorotoluene, 2-nitrotoluene, 2-chlorotoluene, 2-bromotoluene ve 2-iodotoluene ortamları için sırasıyla 0,047, 0,035, 0,028, 0,027, 0,023 ve 0,017 olarak bulundu. Daha yüksek nihai sinyal büyümesine ya da çekirdek-elektron etkileşme parametresine sahip çözgenler, asfalteni daha etkin bir şekilde çözerler. Toluene molekülünde meta pozisyonuna gelen substituentlerin F>NO2>Cl>Br>I sıralamasına göre nihai NMR sinyal büyümelerini değiştirdiği sonucuna varıldı. MC800 asfaltenin moleküler yapısının tayinine yönelik IR spektroskopik incelemeleri, Thermo Nicolet FT-IR-6700 spekrometresi ile 400-4000 cm-1 dalga boyu aralığında ATR tekniği kullanılarak gerçekleştirildi. MC800 asfalteninin içerdiği fonksiyonel gruplar: 3449 cm-1’de N–H soğurma piki, 3100 cm-1’de O–H grubu, 2946 cm-1’de –CH3 eğilme titreşimleri, 2926 cm-1’de –CH2 gerilme titreşimleri, 1597 cm-1’de C=C gerilme titreşimleri, 1030 cm-1’de C2S=O, 721, 744, 806 ve 856 cm-1’de aromatik düzlem dışı eğilmeler olarak belirlendi. MC800 asfalten partiküllerinin yüzey morfolojileri elektron mikroskobu çalışmaları ile incelendi. Ayrıca sisteme entegre enerji dağılımlı x-ışınları detektörü ile asfalten parçacıklarının yüzey elemental analizi yapıldı. MC800 asfalten parçacıkları üzerinde üç ana bileşen belirlendi: O (%50,38), C (%44,32) ve S (%4,60).Item The asphaltene coating effect on GMI response in Fe 4.3Co 68.2Si 12.5B 15 amorphous microwires(Taylor and Francis, 2013-09-17) Peksöz, Ahmet; Çaylak, Osman; Taysioğlu, Aslı Ayten; Derebaşı, Naim; Kaynak, Gökay; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Anabilim Dalı.; AAI-2254-2021; AAG-9772-2021; 23100976500; 18036806100; 18038658800; 11540936300; 12042075600The asphaltene was extracted from asphalt cement with penetration grade 60, which is extracted from crude Libya petroleum. The asphalt cement was taken from Tupra Refinery in Izmit-Turkey. The asphalt cement was dissolved in 10 times excess volume of benzene, precipitated in a further 10 times excess volume of petroleum ether with a boiling range of 40-60 degrees C (i.e., 1 part asphalt cement, 10 parts benzene, and 100 parts petroleum ether). The resultant precipitate was collected by filtration and dried. The asphaltene so obtained was dark brown semi-solids. The percentage of asphaltene in the asphalt cement was 30% by weight. Fe4.3Co68.2Si12.5B15 amorphous microwires, with a diameter of 120 m and 12 cm long, were coated with these paramagnetic asphaltene molecules. The giant magneto-impedance effect was experimentally measured on uncoated and asphaltene coated Co-rich amorphous wires. In the asphaltene coated sample, a very high value of the giant magneto-impedance effect ratio up to 42% was achieved at 4.0 MHz. As far as is known, such a giant magneto-impedance enhancement is reported for the first time by an asphaltene coating process.Item The characterization of asphaltene behavior in some aromatic solvents by dynamic nuclear polarization technique(Elsevier, 2010-12) Almaz, Ekrem; Peksöz, Ahmet; Yalçıner, Aytaç; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; AAG-9772-2021; 23100976500; 14055078800Dynamic nuclear polarization (DNP) studies of asphaltene/some hydrocarbons solutions were performed at 1.53 mT. The low field EPR spectrum of Asphaltene/Mesitylene sample was recorded. The DNP parameters such as enhancement factor, nuclear-electron coupling constant, saturation factor, leakage factor, the parameter for the relative importance of scalar and translational dipolar interaction and the total spin-lattice relaxation rate were determined. The effect of irradiation with neutrons from the Ra-Be source to the DNP parameters was investigated. Dissolved molecular oxygen effect on the enhancement factor for each sample was examined experimentally. We also make some interpretations depending on the results obtained for the interactions between nuclei of the solvent and electrons delocalized on the asphaltene.Item Characterization of non-vacuum CuInxGa1 − xSe2 thin films prepared by low-cost sequential electrodeposition technique(Elsevier, 2017-04-02) Yıldırım, Hasan; Peksöz, Ahmet; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; 0000-0001-6552-1112; A-8113-2016; AAG-9772-2021; 57222249173; 23100976500Copper indium gallium diselenide (CuInxGa1 - Se-x(2)) thin films were grown on indiumtin oxide coated glass substrate by a sequential electrodeposition technique. The deposition bath consisted of an aqueous solution of 10 mM CuCl2, 10 mM InCl3, 20 mM GaCl3, 20 mM H2SeO3 as precursors, and 200 mM LiCl. The pH of the solution was adjusted to 1.7 by adding HCl. Cu, In, Cu, Ga, Cu, Se components were deposited sequentially. Cu/In/Cu/Ga/Cu/Se stacked layers were annealed at 250, 350, 450 and 550 degrees C for 30 min. X-ray diffraction (XRD) studies showed the produced CIGS thin films had polycrystalline structure. From scanning electron microscopy studies, it was found that CIGS thin films exhibited different surface appearances depending on annealing temperature. Energy dispersive x-rays analysis showed that elemental ratio of Se decreased from 46.99 to 14.84 (%) with increasing of annealing temperature. Optical band gap of the CIGS films varied between 1.41 and 2.19 eV. Thicknesses and refractive indices of the produced CIGS thin films were calculated by fitting spectroscopic ellipsometric data (psi and triangle) by using Cauchy model. Deposited CIGS thin films were p-type semiconductor with carrier concentration of -10(16) cm(-3).Item CuIn1-xGaxSe2 tabanlı fotovoltaik ince filmlerinin üretilmesi ve karakterizasyonu(Uludağ Üniversitesi, 2017-02-28) Yıldırım, Hasan; Peksöz, Ahmet; Uludağ Üniversitesi/Fen Bilimleri Enstitüsü/Fizik Anabilim Dalı.Bakır indiyum galyum diselenid (CuInxGa1-xSe2) ince filmlerinnin ardışık elektrodepozisyonu ITO kaplı cam alttaşlar üzerine sulu çözeltilerde potansiyostatik yöntemle gerçekleştirilmiştir. Cu–Ga–S (CGS) and Cu–In–S (CIS) öncü ince filmlerinin ITO alttaşlar üzerine elektrodepozisyon mekanizmaları da dönüşümlü voltammetri yöntemi ile araştırılmıştır. Dönüşümlü voltammetri çalışmaları tekli Cu, Ga, S, In ve Se sistemleri, ikili Cu–S, G–S ve Cu–Ga sistemleri, üçlü Cu–Ga–S ve Cu–In–S sistemleri için yapılmıştır. Cu–Ga–S öncü filmlerinin birlikte depozisyonunda GaCl3 konsantrasyonun etkisi detaylı olarak incelenmiştir. En yüksek Ga elemental bileşen oranına sahip CGS öncü filmi 20 mM GaCl3 içeren çözeltiden depozite edilmiştir. Bu film 1,7 eV enerji bant aralığına ve 2,32x1016 cm-3 taşıyıcı konsantrasyonuna sahiptir. En uygun depozisyon potansiyelinin belirlenmesi amacıyla Cu–In–S öncü ince filmlerinin birlikte elektrodepozisyonu farklı potansiyellerde gerçekleştirilmiştir. Taramalı elektron mikroskobu (SEM) ve enerji dağılımlı x-ışını (EDX) analizleri -0,9 V'ta depozite edilen CIS öncü filminin %15,82 Cu, %41,45 In ve %42,73 S ile en iyi elemental bileşim oranına ve yaklaşık 0,4 μm tanecik boyutları ile düzgün yüzey yapısına sahir olduğunu göstermiştir. Cu/In/Cu/Ga/Cu/Se katmanlı yapıları farklı sıcaklıklarda (250 °C – 550 °C) tavlanmışlardır. Taramalı elektron mikroskobu analizlerinden CIGS ince filmlerin tavlama sıcaklıklarına bağlı olarak farklı yüzey özelliklerine sahip oldukları görülmüştür. EDX analizleri, tavlama sıcaklığı arttıkça CIGS ince filmlerdeki Se elemental bileşen oranının %46,99'dan %14,84'e düştüğünü göstermiştir. XRD analizlerine göre 550 °C'de tavlanan CIGS ince filmin sitokiyometrik CuGa0,6In0,4Se2 fazına sahip olduğu görülmüştür. CIGS ince filmlerin enerji bant aralıkları 1,41 eV ile 2,19 eV arasında değişim göstermektedir. Depozite edilen CIGS filmleri ~1016 cm-3 taşıyıcı konsantrasyonuna sahiptirler. Hall etkisi ölçümleri CGS, CGS ve CIGS filmlerinin p–tipi yarıiletken özelliklere sahip olduklarını göstermiştir.Item Depozisyon potansiyelinin cuInTe ince filmlerinin fiziksel özelliklerine etkisi(Bursa Uludağ Üniversitesi, 2020) Keser, Gökhan; Peksöz, Ahmet; Bursa Uludağ Üniversitesi/Fen Bilimleri Enstitüsü/Fizik Anabilim Dalı.; 0000-0003-2382-6027Bakır indiyum tellürit (CIT) kalkopirit bileşikleri, suda çözünebilen Cu, In ve Te moleküler kaynaklarını içeren sulu bir elektrolitten indiyum kalay oksit kaplı cam alttaşlar üzerine elektrokimyasal olarak büyütüldü. Bakır, indiyum ve tellür kaynakları olarak CuSO4·5H2O, InCl3 ve Na2TeO3 kullanıldı. CIT ince filmlerinin kaplanma mekanizmaları döngüsel voltammetri (CV) çalışmaları ile açıklanmıştır. Ayrıca kaplanma potansiyelinin CIT ince filmlerinin elektrik, optik ve yapısal özellikleri üzerindeki etkisi çalışılmıştır. Elektro depozit edilmiş CIT filmlerinin enerji bandı 0,97 ile 1,83 eV aralığındadır. -0,5, -0,6, -0,7 ve -0,8 V’ta üretilen CIT filmlerinin stokiyometrisi CuInTe2’ye yakındır. Üretilen CIT filmlerinin çoklu kristal yapıda olduğunu ve CuInTe2’nin sırasıyla 2θ ~ 25°, 41° ve 49°’de (1 1 2), (2 0 4) ve (1 1 6) yönelimlerine karşılık gelen ana kalkopirit fazı olduğu bulunmuştur. Hall-Etkisi ölçümleri, üretilen CIT ince filmlerinin, 2,8x10 ve 2,8x10 17 18 alıcı konsantrasyon aralığına ve üretilen tüm filmlerin p-tipi yarı iletken karaktere sahip olduğunu göstermiştir. 20,4 - 60,2 cm -3 cm /Vs aralığındaki mobilite değişimi CIT filmlerin 2,19 ile 0,59 aralığındaki farklı Cu/In oranları ile açıklanabilir. Filmlerin özdirenci 0,011 - 0,036 Ωcm arasındadır. Bu sonuçlar literatürle çok iyi bir uyum göstermektedir.Item Determination and analysis of dispersive optical constants of some organic thin films(Natl Inst Optoelectronics, 2010-04) Kaya, Yunus; Peksöz, Ahmet; İrez, Gazi; Kaynak, Gökay; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Kimya Bölümü.; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; AAG-9772-2021; 35181446100; 23100976500; 6602755323; 12042075600The optical behaviour of the complexes of (2E)-3-aza-1-(hydroxyimino)-2,4-diphenylpent-2-ene (HL) was investigated by optical reflectance and transmittance measurements. The optical constants (refractive index, n; extinction coefficient, k and dielectric constant, e) of some organic thin films were determined using reflectance and transmittance spectra. The optical absorption studies show that the transition is direct with band gap energy values, which are calculated. Analysis of the basis absorption spectra was also carried out to determine optical band gap (E-g) and Urbach parameter (E-o). The analysis of the optical absorption data revealed optical direct transition with band gaps of 3.7-3.9 eV. A surface observation of these thin films was also carried out by an Atomic Force Microscope.Item DNP sensitivity of F-19-NMR signals in hexafluorobenzene depending on polarizing agent type(Wiley, 2016-06-01) Peksöz, Ahmet; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; AAG-9772-2021; 23100976500Low field dynamic nuclear polarization or low field magnetic double resonance technique enables enhanced nuclear magnetic resonance signals to be detected without increasing the strength of the polarizing field. The study reports that the dynamic nuclear polarization of F-19 nuclei in hexafluorobenzene solutions doped with nitroxide, BDPA, MC800 asphaltene and MC30 asphaltene free radicals at 15 G. The F-19 nuclei in all solutions gave positive DNP enhancements changing between 3.42 and 189.54, corresponding to predominantly scalar interactions with the unpaired electrons in the radicals. DNP sensitivity of F-19 nuclei in hexafluorobenzene was observed to be changed significantly depending on the radical type. Nitroxide was found to have the best DNP performance among the polarizing agents.Item Dynamic nuclear polarization in highly fluorinated solutions(Taylor & Francis, 2010) Ovalıoğlu, Hüseyin; Peksöz, Ahmet; Kırımlı, Handan Engin; Yalçıner, Aytaç; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; AAG-9772-2021; 24460278400; 23100976500; 24460574700; 14055078800The Overhauser effect type dynamic nuclear polarization experiments were performed to study solutions of the stable free radical alpha,gamma-Bisdiphenylene-beta-phenyl allyl complex with benzene (1:1) in some highly fluorinated aliphatic and aromatic solvents. In solutions examined in this study, it occurs mainly the Overhauser effect, which normally arises due to both dipolar and scalar interactions between the unpaired electrons of the free radical molecules and fluorine nuclei of solvent molecules. 1-Iodotridecafluorohexane, N-Methyl-bis-trifluoroacetamide, Octafluorotoluene and Hexafluorobenzene were used as the solvents. The experiments were performed at a low field double resonance NMR spectrometer, which operates at 1.53 mT. The NMR enhancements depend on competition between intermolecular magnetic interactions. It was studied to investigate variation of EPR spectra with four different temperatures. It was found as temperature increases, peak points of EPR spectra decreases.Item Dynamic nuclear polarization in some aliphatic and aromatic solutions as studied by fluorine-electron double resonance(Taylor & Francis, 2008-01) Çimenoǧlu, Mehmet Akif; Peksöz, Ahmet; Yalçıner, Aytaç; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; AAG-9772-2021; 23100976500; 14055078800Dynamic nuclear polarization experiments were performed to study the solutions of the stable free radical alpha,gamma-Bisdiphenylene-beta-phenyl allyl complex with benzene (1:1) in some highly fluorinated aliphatic and aromatic solvents. In solutions examined in this study, the Overhauser effect, which normally arises due to both dipolar and scalar interactions between the unpaired electrons of the free radical molecules and fluorine nuclei of solvent molecules occurs mainly. 1-Iodotridecafluorohexane, 2,2,3,4,4,4-Hexafluoro-1-butanol, N-methyl-bis-trifluoroacetamide, hexafluoroacetylacetone, octafluorotoluene, and hexafluorobenzene were used as the solvents. The experiments were performed at a low field double resonance NMR spectrometer, which operates at 1.53 mT. The NMR enhancements depend on competition between intermolecular magnetic interactions. The measurements were performed at four different temperatures to test the dipolar and the scalar part of the coupling between the fluorine nucleus (F-19) and the unpaired electron. It was found that the dipolar interactions are more effective for the aliphatic solvents, while the scalar interactions are more effective for the aromatics. The nuclear-electron coupling parameter varies between 0.018 and 0.157 in all aliphatic solvents and between -0.063 and -0.035 in aromatic solvents.Item Effect of Ga content on the properties of CuGaS precursor thin films produced by electrochemical Co-deposition(Springer, 2016-12-27) Yıldırım, Hasan; Peksöz, Ahmet; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; 0000-0001-6552-1112; A-8113-2016; AAG-9772-2021; 57222249173; 23100976500Cu-Ga-S ternary thin films were produced by one-step co-electrochemical deposition from an aqueous deposition bath consisting CuCl2, GaCl3 and Na2S2O3 as precursor, and LiCl. The pH of the deposition solution was adjusted to 2.0 adding HCl. Cyclic voltammogram studies were performed in detail prior to the film growth. The best deposition potential was determined to be -0.4 V from the standpoint of the film homogeneity, doping all elements in the bath and avoidance of the immediate atomic aggregation. The chronoamperometry technique was applied to the deposition solution at -0.4 V for 30 min. The effect of Ga content on the film characteristics was investigated. Optical band gap of the films was found to be in 1.6-2.2 eV range. It was concluded that energy band gap of the thin films decreased, as Ga content increased. All deposited films exhibited p-type semiconductor behavior.Item The effect of sample age on dynamic nuclear polarization parameters in asphalt suspensions(Taylor & Francis, 2011) Kırımlı, Handan Engin; Peksöz, Ahmet; Ovalıoǧlu, Hüseyin; Yalçıner, Aytaç; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Anabilim Dalı.; AAG-9772-2021; AAI-6732-2021; 24460574700; 23100976500; 24460278400; 14055078800The Overhauser effect type dynamic nuclear polarization was used to study some colloidal suspensions with benzene, toluene, ethylbenzene, mesitylene, tetralin, and chlorobenzene solvent media of asphaltene obtained from MC-30 liquid asphalt in a weak magnetic field of 1.437 mT at room temperature. For each sample of solvent medium, the samples were prepared in three different asphaltene concentrations. The samples were held for ten years and then dynamic nuclear polarization parameters were found via dynamic nuclear polarization experiments that were performed again. Thus, the effect of sample age to dynamic nuclear polarization parameters was investigated. The results were discussed.Item Efficiency enhancement of electrochromic performance in NiO thin film via Cu doping for energy-saving potential(Pergamon-Elsevier Science, 2019-02-01) Fırat, Yunus Emre; Peksöz, Ahmet; Bursa Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; 0000-0003-0510-6640; AAK-5283-2021; AAG-9772-2021; 57188820368; 23100976500Construction of low-cost and high-efficiency electrochromic electrodes with high color contrast and fast response time in electrochromic applications have led to a proliferation of studies in metal oxides. This research study presents a comprehensive overview of the electrochemical synthesis of nanoporous Cu-doped nickel oxide films on ITO-coated glass substrate and its electrochromic behavior in alkaline medium. X-ray diffraction analysis and scanning electron microscopy are used to determine the phase and morphology of the produced films. The films indicate uniform and good adhesion to the substrate. The electrochromic behavior of the deposited films is tested by means of cyclic voltammetry, chronocoulometry, repeating chronoamperometry, and electrochemical impedance spectroscopy measurements. The color change from dark brown to transparent appears reversibly well suitable under sequential potential from -0.2 to +1.0 V. After the Cu atoms incorporate into the host NiO matrix, noticeably enhancements are observed in optical modulation (57.1% at 550 nm), coloration efficiency (13.78 cm(2)/C) and response time (t(b) = 2.26 s and t(c) = 1.77 s) compared to its as-prepared NiO films. Energy level diagrams including fermi level, valance band edge and conduction band edge positions are presented based on the Mott-Schottky approximation and Tauc's method using absorbance data for the NiO and Cu:NiO films. The negative slope of the Mott-Schottky plot shows p-type conductivity for the films, and acceptor density is found as 4.44 x 10(19) cm(-3) and 5.41 x 10(19) cm(-3) for the NiO and Cu:NiO films, respectively. An equivalent electronic circuit is fitted using the measured Nyquist data of the NiO or Cu:NiO semiconductor/electrolyte system, and the calculated values of the circuit elements show significant sensitivity to the Cu doping. Therefore, our results make a major contribution to the research on energy-saving smart windows by demonstrating analyses in detail.Item Efficiently two-stage synthesis and characterization of CuSe/Polypyrrole composite thin films(Elsevier, 2017-08-10) Fırat, Yunus Emre; Peksöz, Ahmet; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; 0000-0003-0510-6640; AAG-9772-2021; 57188820368; 23100976500A novel CuSe/PPy composite thin film was fabricated easily via electrodeposition method on ITO substrate in two stages. In order to determine deposition potentials, the electrochemical response of Cu and Se elements, and monomer were analyzed by cyclic voltammetry, and then chronoamperometry technique was used to synthesis of the conductive metal/polymer chalcogenide films. The morphology, electrical and optical properties of the films are presented in detail. SEM studies indicate that the Cu and Se nanoparticles are uniformly coated on ITO surface together with PPy. EDX analyses show that Cu and Se components are successfully electrodeposited into PPy polymer matrix. FTIR studies also confirm that PPy is synthesized and the CuSe nanoparticles are successfully loaded into PPy. The optical energy band gap (E-g) of the PPy thin films decreases from 1.78 to 1.44 eV with the addition of CuSe nanoparticles. Halleffect measurements reveal that both films exhibit semiconducting behavior, and the addition of CuSe into the PPy matrix plays an important role in the enhancement of electrical properties. The results show that the produced CuSe/PPy nanocomposite film can be considered a promising material for solar cell applications and the two stage synthesis method used for this composite film may be applied to other metal/polymer chalcogenides due to the low-cost, large-scale and easy fabrication.Item Electrical, structural and morphological properties of Ni/n-Si contacts(Natl Inst Optoelectronics, 2009-05) Ertürk, Kadir; Özer, Mehmet; Akay, Sertan Kemal; Peksöz, Ahmet; Kaynak, Gökay; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; R-7260-2016; AAG-9772-2021; 9742545600; 24801954600; 23100976500; 12042075600This paper presents structural, morphological and electrical properties of Ni/n-Si contacts formed by electro-deposition technique. Ni film is deposited on n-type Si (100) substrate using 2 mol/L Nickel Sulphamate, 0.5 mol/L Boric Acid solutions. The morphological properties are investigated by using energy dispersive X-Ray analysis and scanning electron microscopy imaging to perform local distribution of Ni. Electrical measurements have been done at room temperature to investigate the Schottky barrier height.Item Electrochemical properties of al doped polypyrrole composite polymer: mott-schottky approximation and density functional theory(Electrochemical Society, 2019-04-29) Emre Fırat; Safi; Tokgöz, Seyit Rıza; Peksöz, Ahmet; Zaki, Safi; Yunus, Emre Fırat; Bursa Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Atom ve Molekül Fiziği Bölümü.; 0000-0001-9135-1508; IXW-9711-2023; HRA-2244-2023; AAG-9772-2021; 57211276138; 23100976500; 57214446678; 57188820368Polypyrrole and Al doped polyprrole thin films were synthesized by electrochemical deposition method. FTIR spectroscopic studies confirm the formation of PPy and Al:PPy thin films. From the FESEM crosssectional images, film thickness were measured as 393.9 and 425.0 nm for the PPy and Al doped PPy thin film, respectively. Electrochemical properties of the deposited polymers are studied by Mott-Schottky analysis and electrochemical impedance spectroscopy. The calculated acceptor concentration is 5.03 x 10(18) m(-3) and 5.14 x 10(18) m(-3) for PPy and Al:PPy thin film, respectively. EIS analysis are performed to find out the effect of aluminum doping on PPy matrix. An equivalent circuit model is fitted to the EIS data to understand the behavior of coating/electrolyte interface and to determine the values of the circuit elements. Time-dependent self-consistent field and density functional theory based on CAM-B3LYP level with 6-311G(d,p) basis set are used to compute electronic properties such as HOMO and LUMO energies, ionization potential, electron affinity, electronegativity, hardness, softness. Electronic energy levels of the synthesized polymers are represented using the results of Mott-Schottky studies, and the frontier energy levels are also illustrated in this energy diagram to give more detailed explanation.Item Electrochemical synthesis of polyaniline/inorganic salt binary nanofiber thin films for electrochromic applications(Springer, 2016-10-24) Fırat, Yunus Emre; Peksöz, Ahmet; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; 0000-0003-0510-6640; AAG-9772-2021; AAK-5283-2021; 57188820368; 23100976500Polyaniline conductive polymer thin films without or with LiClO4 inorganic salt were coated by electrochemical deposition method on ITO surface. Electrochromic stability test, electrochemical behavior, coloring performance, optical properties and surface formations of the produced films were studied in detail. The deposited films were found to have a good stability. Electrochemical analysis showed that the conductivity of LiClO4 doped PANI film was higher than that of the PANI. Oxidation and reduction peaks, and potentials differed significantly depending on the content of the electrolytes. SEM studies demonstrated that the surface of each film consisted of completely nanofibers. Addition of LiClO4 to the deposition electrolyte decreased substantially the diameter of these nanofibers. PANI film with LiClO4 exhibited four colors, while pure PANI film had three different colors. The EDX results obtained from the surface of LiClO4 doped PANI material indicated that PANI and LiClO4 could be successfully linked to form PANI/LiClO4 binary thin film.Publication Electrochemically characterized energy storage properties of Ni foam/poly (EGDMA-Co-VPCA)/SWCNT composite electrode produced by surface polimerization method(Elsevier, 2021-05-21) Yıldırım, Hasan; Tokgöz, Seyit Rıza; Peksöz, Ahmet; Kara, Ali; Yıldırım, Hasan; TOKGÖZ, SEYİT RIZA; PEKSÖZ, AHMET; KARA, ALİ; Bursa Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; Bursa Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Kimya Bölümü.; 0000-0001-6552-1112; 0000-0003-4050-4222; 0000-0001-9135-1508; 0000-0003-2457-6314; AHB-9353-2022; HRA-2244-2023; IXW-9711-2023; A-8113-2016Poly (EGDMA-co-VPCA)/SWCNT composite film is successfully synthesized on Ni foam substrate by surface polymerization technique. Energy storage properties of Ni foam/poly (EGDMA-co-VPCA)/ SWCNT composite electrode are investigated via cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy. The as-prepared Ni foam/poly (EGDMA-co-VPCA)/ SWCNT composite electrode exhibits high specific capacitance of 100 F/g at 5 A/g, high power density of 3285.0 W/kg at 8.5 Wh/kg energy density, capacitive retention of 77.7% after 5000 charge-discharge cycles and excellent chemical stability.Publication Electrochemically growth and characterization of CuInTe₂ chalcopyrite thin films(Springer, 2020-07-28) Keser, Gökhan; Peksöz, Ahmet; Keser, Gökhan; PEKSÖZ, AHMET; Bursa Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; Bursa Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü/Güneş Pili Laboratuvarı.; 0000-0003-2382-6027; AAG-9772-2021; FZX-9393-2022Copper indium tellurite (CIT) chalcopyrite compounds were electrochemically grown from an aqueous electrolyte including water-soluble Cu, In, and Te molecular sources onto indium thin oxide-coated glass substrates. CuSO4 center dot 5H(2)O, InCl3, and Na2TeO3 were used as copper, indium, and tellurium sources, respectively. Deposition mechanisms of the CIT thin films are explained by cyclic voltammetry (CV) studies. It is also noted that the effect of deposition potential on the electrical, optical, and structural facilities of the electrodeposited CIT thin films. Energy bandgap of the electrodeposited CIT films is in the range of 0.97-1.83 eV. Stoichiometry of the CIT films deposited at - 0.5, - 0.6, - 0.7, and - 0.8 V is near to CuInTe2. We report that the produced CIT films is polycrystalline nature, and CuInTe(2)is a major chalcopyrite phase corresponding to (1 1 2), (2 0 4), and (1 1 6) directions at 2 theta similar to 25 degrees, 41 degrees, and 49 degrees, respectively. Hall-effect measurements show that the produced CIT thin films have p-type semiconducting conductivity with the acceptor concentration range of 2.8 x 10(17) and 2.8 x 10(18) cm(-3). The variation of the mobility within 20.4-60.2 cm(2)/V s can be explained by the variation of Cu/In ratio within 2.19-0.59. The resistivity of the films is found to vary within 0.011-0.036 Omega cm, which is in good agreement with the literature data.
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