Browsing by Author "Dincalp, H"
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Item Perylene Diimide-Based Dimeric Electron Acceptors with Molecular Conformations for Perovskite Solar CellsSaltan, GM; Yesil, T; Ötken, AA; Zafer, C; Dincalp, HThis paper reports five novel PDI dimer type electron transport materials (ETMs) employing o-indoloquinoxaline (o-Iq), m-indoloquinoxaline (m-Iq), and cibalackrot (Ci) groups as the core building blocks and presents the twisted structures of PDI dimers coded as PDI-NHR-o-Iq, PDI-o-Iq, PDI-NHR-m-Iq, PDI-m-Iq and PDI-NHR-Ci dyes (see Scheme 1 and 2). We have systematically compared their photophysical, electrochemical, and optoelectronic properties with respect to the reference dye (2PDI-NHR), which is directly connected of two PDI planes. Their calculated HOMO-LUMO energy levels are sufficient for charge transfer to the perovskite material so that structure-photovoltaic performance relationship of synthesized ETM dyes can be evaluated. When the binding position of indoloquinoxaline group between PDI rings are changed from o- to m- positions, most of the photophysical and electrochemical properties of PDI dimer are dramatically changed, finally improving the photovoltaic performances. Indoloquinoxaline and cibalackrot subunits covalently attached to perylene diimide dimers decorated with long-alkyl chains used as ETM are coated on the MAPbI2Br perovskite surface to manufacture solar cells. Attaching groups improve the charge transfer capability of the material depending on their molecular conformation, which plays important role in adjusting the energy level between the perovskite material and the ETL. imageItem Fabrication and electrical characterization of Al/diazo compound containing polyoxy chain/p-Si device structureBirel, O; Kavasoglu, N; Kavasoglu, AS; Dincalp, H; Metin, BDiazo-compounds are important class of chemical compounds in terms of optical and electronic properties which make them potentially attractive for device applications. Diazo compound containing polyoxy chain has been deposited on p-Si. Current-voltage characteristics of Al/diazo compound containing polyoxy chain/p-Si structure present rectifying behaviour. The Schottky barrier height (SBH), diode factor (n), reverse saturation current (I-o), interface state density (N-ss) of Al/diazo compound containing polyoxy chain/p-Si structure have been calculated from experimental forward bias current-voltage data measured in the temperature range 100-320 K and capacitance-voltage data measured at room temperature and 1 MHz. The calculated values of SBH have ranged from 0.041 and 0.151 eV for the high and low temperature regions. Diode factor values fluctuate between the values 14 and 18 with temperature. Such a high diode factors stem from disordered interface layer in a junction structure as stated by Brotzmann et al. [M. Brotzmann, U. Vetter, H. Hofsass, J. Appl. Phys. 106 (2009) 063704]. The calculated values of saturation current have ranged from 3 x 10(-11) A to 2.79 x 10(-7) A and interface state density have ranged from 5 x 10(11) eV(-1) cm(-2) and 4 x 10(13) eV(-1) cm(-2) as temperature increases. Results show that Al/diazo compound containing polyoxy chain/p-Si structure is a valuable candidate for device applications in terms of low reverse saturation current and low interface state density. (C) 2012 Elsevier B.V. All rights reserved.Item Enhanced performance of ultra-thin polyaniline supercapacitor via aniline blue-WS SAMs with rich nucleation siteKiymaz, D; Kiymaz, A; Dincalp, H; Zafer, CWe report the ultrathin supercapacitor's superior performance via the vertically aligned one-dimensional polyaniline structure (1D PANI) growth on the fluorine-doped tin oxide (FTO) substrate. FTO electrodes were treated by the molecular-self assembly, and the effects of different self assembled monolayers (SAMs) on both the evolution of PANI and electrochemical performance were examined. We obtained 809.09 F g(-1) specific capacitance from similar to 120 nm thick PANI (at 20 mV s(-1) scan rate of cyclic voltammetry) via aniline blue water soluble SAMs modification. The supercapacitor's internal dynamics were clarified by a new equivalent circuit model developed from the Graham model. Through the new model, accurate information about double-layer capacitance, percolation capacitance, and bulk capacitance, which composes the electrode's capacitive performance, could be obtained. This work provided novel knowledge to develop PANI deposition and hence to achieve greater capacitances.Item Highly Soluble Polyoxyethylene-Perylene diimide: Optical, Electrochemical and Photovoltaic StudiesBirel, OH; Zafer, C; Dincalp, H; Aydin, B; Can, MThe synthesis and optical properties of a new dye molecule [PERKAT] were reported. The molecular structure of PERKAT was characterized by FT-IR and H-1 NMR. Optical properties of PERKAT were investigated by UV-Vis absorption, fluorescence spectroscopy. The effect of the solvent polarity on the spectral characteristics has been investigated in five common organic solvents of different polarity. PERKAT is highly soluble in common organic solvents such as chloroform, dichloromethane due to the polyoxyethylene chains. The fluorescence quantum yields of PERKAT in all solvents is very low (10(-2) -10(-3)). Cyclic Voltammetry (CV) analysis was performed to determine the HOMO and LUMO energy levels of the PERKAT. PERKAT was used as electron acceptor material in organic solar cell.Item Charge transport kinetics in flower like α-MnO2 nano-sheet and α-MnO2 nanowire based supercapacitorsKiymaz, D; Kiymaz, A; Tekoglu, S; Mayr, F; Dincalp, H; Zafer, CIn a supercapacitor, determining the cells' internal dynamics and limiting factors on the efficiency is essential for device designs. In this context, electrochemical impedance spectroscopy is a powerful tool in investigating device kinetics. This study explained the performance improvement in nanostructured MnO2 electrodes from a diffusion perspective. Firstly, we reported morphological features of flower-like nanosheet MnO2 and nanowire MnO2 with identical crystal structure (alpha-MnO2 phase) and capacitance-voltage properties. Then, the factors limiting the bias voltage-dependent capacitance efficiency were explained via electrochemical impedance spectroscopy by setting up a three-electrode system. Both resistance and capacitance vs. frequency plots provided important information on ion diffusion and charge transfer mechanisms.Item Spectral properties and G-quadruplex DNA binding selectivities of a series of unsymmetrical perylene diimidesDincalp, H; Avcibasi, N; Icli, SA series of new unsymmetrical perylene diimides have been synthesized to investigate their binding selectivities to G-quadruplex DNA structure, a unique four-stranded DNA motif, which is significant to the regulation of telomerase activity. The structures of the perylene diimides have been characterized by IR spectrophotometer, H-1 NMR, C-13 NMR, MS, TGA and time-resolved instruments. Spectrochemical behaviors have been investigated by visible absorption and fluorescence emission spectra. The spectral characterization of the compounds has been investigated in five common organic solvents of different polarity and in water (in 170 mM phosphate buffer at pH 6). Marked red shifts of absorbance and fluorescence emission bands of the compounds in aqueous solution are compared with the other organic solutions. The fluorescence quantum yields are determined low in more polar solvents and also calculated to be about less than about 0.05 in aqueous solution because of the aggregation effects. Photodegradation rate constants (k(p)) of the synthesized compounds have been compared under xenon lamp irradiation in acetonitrile solution. Binding abilities of the synthesized perylene diimides to different form of DNA strands have been investigated by visible absorption and fluorescence spectroscopy in the phosphate buffer solutions. Also, pH-dependent aggregation and G-quadruplex DNA binding selectivity of these ligands have been compared. Among these ligands, N-(2,6-diisopropylphenyl)-N'-(4-pyridyl)-perylene-3,4,9,10-tetracarboxylic diimide (PYPER) has been found to be the most selective interactive ligand for G-quadruplex formed in the G4'-DNA structure. PYPER has shown a significant selectivity to G4'-DNA which is comprised of d(TTAGGG) repeats, known as human telomeres, in the phosphate buffer at pH 6. The absorption maximum of the PYPER/G4'-DNA complex has given bathochromic shift of 7 nm with respect to the absorption maximum of DNA-free solution of PYPER in phosphate buffer at pH 6. Fluorescence quenching experiments between PYPER and G4'-DNA show that PYPER demonstrates about a 9.3-fold selectivity for binding to G4'-DNA versus ds-DNA base pairs with the bimolecular rate constant of 0.95 x 10(12) M-1 s(-1). (c) 2006 Elsevier B.V. All rights reserved.Item Conformational control of morphology for perylene diimide dimer as electron transporting material at perovskite surfaceÖtken, AA; Saltan, GM; Yesil, T; Zafer, C; Dincalp, HSynthesis of core-twisted perylene diimide (PDI) dimers attached with thiophene linkers (PDI-NHR-Th(1-4)) and their electron transporting ability at perovskite surface were studied. Synthesized dyes showed a high-lying lowest unoccupied molecular orbital (LUMO) energy levels between -3.68 and -3.71 eV, which were compatible with the conduction band of CH3NH3PbI2Br (-3.60 eV). Herein, we have investigated the role of the different substituted positions of PDI monomers to thiophene linkage from its (2,5)-, (3,4)-, (2,4)-, or (2,3)-positions in modulating the morphology of PDI dimer, aggregation behavior for charge transfer properties, optical shifts in ground and excited states, and recombination resistances at the interfaces of p-i-n devices. Conformational changes of PDI dimers attaching to different positions of thiophene linkers are found to affect not only photo-pysical dynamics of excited states of the dyes, but also charge transport kinetics at the perovskite interfaces, changing the photovoltaic performance.Item Metabolic comparison of radiolabeled aniline- and phenol-phthaleins with 131IAvcibasi, U; Avcibasi, N; Ünak, T; Ünak, P; Müftüler, FZ; Yidirim, Y; Dincalp, H; Gümüser, FG; Dursun, ERThe metabolic comparison of aniline- and phenol-phthaleins radiolabeled with (131)I ((131)I-APH and (131)I-PPH, respectively) has been investigated in this study. To compare the metabolic behavior of these phthaleins and their glucuronide conjugates radiolabeled with (131)I, scintigraphic and biodistributional techniques were applied using male Albino rabbits. The results obtained have shown that these compounds were successfully radioiodinated with a radioiodination yield of about 100%. Maximum uptakes of (131)I-APH and (131)I-PPH, which were metabolized as N- and O-glucuronides, were observed within 2 h in the bladder and in the small intestine, respectively. In the case of verification of considerably up taking of these compounds also by tumors developed in the small intestine and in the bladder tissues, these results can be expected to be encouraging to test these compounds, which will be radiolabeled with other radioiodines such as (125)I, (121)I and (124)I as imaging and therapeutic agents in nuclear medical applications. (C) 2008 Elsevier Inc. All rights reserved.Item Highly conjugated isoindigo and quinoxaline dyes as sunlight photosensitizers for onium salt-photoinitiated cationic polymerization of epoxy resinsErcan, BT; Gultekin, SS; Yesil, T; Dincalp, H; Koyuncu, S; Yagci, Y; Zafer, CIn this study, photoinitiated cationic polymerization of epoxy resins by photoinduced electron transfer reactions using four new chromophoric dyes, namely (3E)-1,1 '-bis(2-ethylhexyl)-6,6 '-dipyren-1-yl-3,3 '-biindole-2,2 '(1H,1 ' H)-dione (ISOIV), (3 ' E)-1,1 '''-diethyl-1 ',1 ''-bis(2-ethylhexyl)-1H,1 ''' H-5,6 ':3 ',3 '':6 '',5 '''-quaterindole-2 ',2 ''(1 ' H,1 '' H)-dione (ISOV), (3E)-6,6 '-bis(9-ethyl-9H-carbazole-3-yl)-1-[(2R)-2-ethylhexyl]-1 '-[(2S)-2-ethylhexyl]-3,3 '-biindole-2,2 '(1H,1 ' H)-dione (ISOVIII) and 3,3 '-(6-bromokinoksalin-2,3-diyl)bis(9-ethyl-9H-carbazole) (TPDC6), and diphenyliodonium hexafluorophosphate (Ph2I+PF6-; DPI) under sunlight is reported. Upon irradiation, photoexcited dye forms an exciplex with DPI. Electron transfer reactions within the exciplex result in the formation of ionic species capable of initiating ring-opening polymerization of an epoxy resin. It is shown that among the investigated dyes, ISOVIII and TPDC6 exhibited higher initiation efficiency in accordance with their stronger electron-donating nature due to the presence of carbazole groups. (c) 2021 Society of Industrial Chemistry.Item New perylene derivative dyes for dye-sensitized solar cellsZafer, C; Kus, M; Turkmen, G; Dincalp, H; Demic, S; Kuban, B; Teoman, Y; Icli, SWe have studied the influence of the spacer alkyl chain length of perylenemonoimide (PMI) dyes on the device performance in dye-sensitized solar cells (DSSCs). We observed that the dyes with longer and brunched alkyl chains exhibit higher efficiencies in DSSCs. In line with these statements we now report the highest efficiency obtained under standard conditions for a perylene imide derivative with PMI-DA1 that performs 300 mV open circuit voltage, 9.79 mA/cm(2) short-circuit current and 1.61% overall conversion efficiency. (c) 2006 Published by Elsevier B.V.