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Öğe Electrical Characterizations of Schottky Diodes on ITO Modified by Aromatic SAMs(Polish Acad Sciences Inst Physics, 2013) Havare, A. K.; Okur, S.; Yagmurcukardes, N. T.; Can, M.; Aydin, H.; Seker, M.; Demic, S.In order to understand the electronic properties of the organic Schottky diode, ITO/TPD/Aland ITO/SAM/TPD/Al organic Schottky devices were fabricated to obtain current voltage characteristics. From the slopes and y-axis intercepts of the plots, the values of the ideality factor, barrier heights of the ITO/SAM/TPD/Al diode were determined as 2.03 and 0.56 eV, respectively. The surface characterizations of modified and unmodified ITO were performed via atomic force microscopy. DOT: 10.12693/APhysPolA.123.456Öğe Electrical Characterizations of Schottky Diodes on ITO Modified by Aromatic SAMs(Polish Acad Sciences Inst Physics, 2013) Havare, A. K.; Okur, S.; Yagmurcukardes, N. T.; Can, M.; Aydin, H.; Seker, M.; Demic, S.In order to understand the electronic properties of the organic Schottky diode, ITO/TPD/Aland ITO/SAM/TPD/Al organic Schottky devices were fabricated to obtain current voltage characteristics. From the slopes and y-axis intercepts of the plots, the values of the ideality factor, barrier heights of the ITO/SAM/TPD/Al diode were determined as 2.03 and 0.56 eV, respectively. The surface characterizations of modified and unmodified ITO were performed via atomic force microscopy. DOT: 10.12693/APhysPolA.123.456Öğe Investigation of the Electrical Parameters of the Organic Diode Modified with 4-[(3-Methylphenyl)(phenyl)amino] Benzoic Acid(Electrochemical Soc Inc, 2016) Havare, A. Kemal; Can, M.; Yagmurcukardes, N.; Yigit, M. Z.; Aydin, H.; Okur, S.; Demic, S.; Icli, S.4-[(3-Methylphenyl)(phenyl)amino]benzoic acid (MPPBA) self-assembled monolayer (SAM) molecules as hole injection is formed on p and n type Si and on indium-tin oxide (ITO) electrodes to investigate the effect on the electrical parameters of hole only organic device. The hole mobility improvement of organic device was attributed to an intermediate energy level formed between hole transport materials (HTL) (N,N'-Bis(naphthalen-1-yl)-N,N'-bis(phenyl)benzidine -NPB) and ITO when forming an ultrathin MPPBA layer, leading to increase of carrier mobility of the device. Space charge limited current (SCLC) technique is used to estimate the mobility of the NPB formed at the interface metal/organic Ohmic contact. The hole mobility of ITO/NPB/Al and ITO/MPPBA/NPB/Al devices were obtained as 1.80 x 10(-6) and 1.76 x 10(-3) cm(2)/Vs, at 1350 E (V/cm)(1/2) applied electric field, respectively. SAM modified devices has lower barrier height values. The electronic characteristic parameters of the ITO/(with or without MPPBA)/NPB/Al, Au/n-Si(or p-Si)/(with or without MPPBA)/Au contacts were calculated using current-voltage (I-V) measurements by Schottky type carrier injection. (C) The Author(s) 2016. Published by ECS.Öğe Spectrophotochemical and electrochemical characterization of perylene derivatives adsorbed on nanoporous metaloxide films(Edp Sciences S A, 2007) Kus, M.; Demic, S.; Zafer, C.; Saygili, G.; Bilgili, H.; Icli, S.Electrochemistry of perylene imide and anhydride derivatives adsorbed on semiconductor TiO2 (NT) and insulator Al2O3 (NA) metal oxide films were presented. Adsorption rates on metal oxide surface are observed to be strongly depending on molecular structure. Monoanhydride-monoimide derivatives show two reversible reductions in solution and one reversible reduction in films. Color change from red to blue and violet is observed indicating the formation of monoanion and dianion radicals. Spectroelectrochemical measurements support this interpretation. The color reversal is quite stable in NA films in comparison with NT films.Öğe Structural and Vibrational Spectroscopy Investigation of the 5-[(diphenyl) amino] Isophthalic Acid Molecule(Amer Inst Physics, 2014) Kurt, M.; Sas, E. Babur; Can, M.; Okur, S.; Icli, S.; Demic, S.; Simos, TE; Kalogiratou, Z; Monovasilis, TThe molecular structure and vibrations of 5-(diphenyl) amino] isophthalic acid (DPIFA) were investigated by different spectroscopic techniques (such as infrared and Raman). FT-IR, FT-Raman and dispersive Raman spectra were recorded in the solid phase. HOMO-LUMO analyses were performed. The theoretical calculations for the molecular structure and spectroscopic studies were performed with DFT (B3LYP) and 6-311G (d,p) basis set calculations using the Gaussian 09 program. After optimizing the geometry of the molecule, vibration wavenumbers and fundamental vibrations wavenumbers were assigned on the basis of the potential energy distribution (PED) of the vibrational modes calculated with VEDA 4 program. The results of theoretical calculations for the spectra of the title compound were compared with the observed spectra.Öğe Structural investigation of a self-assembled monolayer material 5-[(3-methylphenyl) (phenyl) amino] isophthalic acid for organic light-emitting devices(Pergamon-Elsevier Science Ltd, 2014) Sas, E. Babur; Kurt, M.; Can, M.; Okur, S.; Icli, S.; Demic, S.The molecular structure and vibrations of 5-[(3-methylphenyl) (phenyl) amino] isophthalic acid (MePIFA) were investigated by infrared and Raman spectroscopies, UV-Vis, H-1 and C-13 NMR spectroscopic techniques and NBO analysis. FT-IR, FT-Raman and dispersive Raman spectra were recorded in the solid phase. H-1 and C-13 NMR spectra and UV-Vis spectrum were recorded in DMSO solution. HOMO-LUMO analysis and molecular electrostatic potential (MEP) analysis were performed. The theoretical calculations for the molecular structure and spectroscopies were performed with DFT (B3LYP) and 6-311G(d,p) basis set calculations using the Gaussian 09 program. After the geometry of the molecule was optimized, vibration wavenumbers and fundamental vibration wavenumbers were assigned on the basis of the potential energy distribution (PED) of the vibrational modes calculated with VEDA 4 program. The total (TDOS), partial (PDOS) density of state and overlap population density of state (OPDOS) diagrams analysis were made using GaussSum 2.2 program. The results of theoretical calculations for the spectra of the title compound were compared with the observed spectra. (C) 2014 Elsevier B.V. All rights reserved.Öğe Synthesis and Raman spectroscopic investigation of a new self-assembly monolayer material 4-[N-phenyl-N-(3-methylphenyl)-amino]-benzoic acid for organic light-emitting devices(Wiley-Blackwell, 2011) Kurt, M.; Okur, S.; Demic, S.; Karpagam, J.; Sundaraganesan, N.We have synthesized 4-[N-phenyl-N-(3-methylphenyl)-amino]-benzoic acid (4-[PBA]) and investigated its molecular vibrations by infrared and Raman spectroscopies as well as by calculations based on the density functional theory (DFT) approach. The Fourier transform (FT) Raman, dispersive Raman and FT-IR spectra of 4-[PBA] were recorded in the solid phase. We analyzed the optimized geometric structure and energies of 4-[PBA] in the ground state. Stability of the molecule arising from hyperconjugative interactions and charge delocalization was studied using natural bond orbital analysis. The results show that change in electron density in the sigma* and pi* antibonding orbitals and E-2 energies confirm the occurrence of intramolecular charge transfer within the molecule. Theoretical calculations were performed at the DFT level using the Gaussian 09 program. Selected experimental bands were assigned and characterized on the basis of the scaled theoretical wavenumbers by their total energy distribution. The good agreement between the experimental and theoretical spectra allowed positive assignment of the observed vibrational absorption bands. Finally, the calculation results were applied to simulate the Raman and IR spectra of the title compound, which show agreement with the observed spectra. Copyright (C) 2011 John Wiley & Sons, Ltd.Öğe Synthesis and spectroscopic characterization on 4-(2,5-di-2-thienyl-1H-pyrrol-1-yl) benzoic acid: A DFT approach(Pergamon-Elsevier Science Ltd, 2016) Kurt, M.; Sas, E. Babur; Can, M.; Okur, S.; Icli, S.; Demic, S.; Karabacak, M.; Jayavarthanan, T.; Sundaraganesan, N.A complete structural and vibrational analysis of the 4-(2,5-di-2-thienyl-1H-pyrrol-1-yl) benzoic acid (TPBA), was carried out by ab initio calculations, at the density functional theory (DFT) method. Molecular geometry, vibrational wavenumbers and gauge including atomic orbital (CIAO) C-13 NMR and H-1 NMR chemical shift values of (TPBA), in the ground state have been calculated by using ab initio density functional theory (DFT/B3LYP) method with 6-311G(d,p) as basis set for the first time. Comparison of the observed fundamental vibrational modes of (TPBA) and calculated results by DFT/B3LYP method indicates that B3LYP level of theory giving yield good results for quantum chemical studies. Vibrational wavenumbers obtained by the DFT/B3LYP method are in good agreement with the experimental data. The study was complemented with a natural bond orbital (NBO) analysis, to evaluate the significance of hyperconjugative interactions and electrostatic effects on such molecular structure. By using TD-DFF method, electronic absorption spectra of the title compound have been predicted and a good agreement with the TD-DFF method and the experimental one is determined. In addition, the molecular electrostatic potential (MEP), frontier molecular orbitals analysis and thermodynamic properties of TPBA were investigated using theoretical calculations. (C) 2015 Elsevier B.V. All rights reserved.Öğe Synthesis of two tri-arylamine derivatives as sensitizers in dye-sensitized solar cells: Electron injection studies and photovoltaic characterization(Elsevier Science Sa, 2014) Can, M.; Yigit, M. Z.; Seintis, K.; Karageorgopoulos, D.; Demic, S.; Icli, S.; Giannetas, V.; Fakis, M.; Stathatos, E.Two organic sensitizers with the structure donor-pi-acceptor, having tri-arylamine as electron donor, cyano-acetic acid as electron acceptor and a phenyl or thiophene ring as pi-bridge, are synthesized. The synthetic procedure, the photophysical and electrochemical properties of both dyes are described in detail. In particular, cyclic voltammetry and spectroscopic measurements were performed while the energy gap between highest occupied and lowest unoccupied molecular orbital for both dyes was calculated. Besides, electron injection dynamics on a series of titanium dioxide nanostructured films sensitized with the two dyes were investigated with time resolved fluorescence spectroscopy using femtosecond temporal resolution, while nanostructured alumina films were used as reference. The photovoltaic performances of both dyes in quasi-solid state dye sensitized solar cells were also investigated. A maximum overall conversion efficiency of 3.8% was monitored for two micrometer thin titanium dioxide films and quasi-solid state electrolyte. The performances of the solar cells are explained in terms of photophysical properties and electron injection dynamics of both dyes. (C) 2013 Elsevier B.V. All rights reserved.
