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Öğe Annealing effects of photoanode on dye sensitized solar cell performance(Taylor & Francis Ltd, 2021) Ozkacar, Tugce; Taran, Songul; Gokcen, Muharrem; Orhan, ErsinPhotoanode annealing effects on dye sensitized solar cell (DSSC) performance were investigated. Four different temperatures (300, 400, 500 and 600 degrees C) were used to annealing of the photoanodes. Morphologic properties of the photoanodes were investigated by a field emission scanning electron microscope (FESEM) and atomic force microscope (AFM). The photovoltaic properties of these DSSCs were obtained for these temperatures using a solar simulator for two different type electrolyte with different redox concentration and additive. Also, the series and charge transfer resistances were obtained from the electrochemical impedance spectroscopy (EIS) Nyquist plots of DSSCs.Öğe Effect of the photoanode fabrication condition, electrolyte type and illumination type on dye-sensitized solar cells performance(Indian Acad Sciences, 2021) Orhan, Ersin; Gokcen, Muharrem; Taran, SongulThe combination of the photoanode fabrication condition, electrolyte type and light source effect on dye-sensitized solar cell (DSSC) performance were investigated. Three different photoanodes (C-1, C-2 and C-3) were used with different fabrication conditions with two different redox concentration electrolytes (30 and 50 mM) for each photoanode. For these six different combinations, DSSC performances were obtained for 12 different situations using two different light sources, AM 1.5 simulated and ultraviolet (UV-365 nm) illumination. It was obtained that the HI30 electrolyte has higher efficiency for UV illumination and the AN50 electrolyte has higher efficiency for AM1.5 simulated illumination. It was also obtained that the C-2 cell with double layer immersed in dye solution has higher efficiency for both two illumination types and two electrolytes.Öğe Electrical property investigation of the Au/n-Si and Au/PVA plus benzimidazole Co complex/n-Si diodes under ultraviolet illumination(Springer, 2021) Gokcen, Muharrem; Taran, Songul; Orhan, ErsinPolyvinyl alcohol (PVA) was doped using the di[1-(2-ethoxyethyl)-5-nitrobenzimidazole] cobalt dichloride and this polymeric composite was used as an interface in Au/n-Si diodes. The basic electrical properties of these fabricated Au/n-Si (MS) and Au/PVA+Co complex/n-Si (MPS) diodes were examined measuring voltage-dependent current (I(V)) data in various ultraviolet illumination intensities and room temperature. Electrical parameters of the MS and MPS diodes were calculated by thermionic emission, Norde, and Card & Rhoderick method. It was found that the ideality factor (n) values of the MS diode increased from 6.7 to 13.4 while the MPS ones increased from 3.4 to 7.5 with increasing illumination. Also, the photo-responsivity (PR) of MPS diode was obtained for P = 50 mW/cm(2) (365 nm UV) as 0.29 A/W at - 5.00 V and 4.01 mA/W at 0 V.Öğe Fabrication and photoanode performance of ZnO nanoflowers in ZnO-based dye-sensitized solar cells(Elsevier, 2022) Biçer, Mustafa; Gokcen, Muharrem; Orhan, ErsinZnO photoanodes consisting of nanoflowers were successfully synthesized on FTO substrates in two steps using the seed layer-hydrothermal method. To control the morphological and photovoltaic properties of ZnO thin films, three types of photoanodes were fabricated in the presence of NH3 (C1), NH3-PEG (C2) and NH3-PVA (C3). The morphological and structural properties of the produced photoanodes were investigated by scanning electron microscope (SEM) and X-ray diffraction (XRD). Using these photoanodes, six different types of dye sensitized solar cell (DSSC) were obtained with Ruthenium Dye (Z907) and two different electrolytes. Photovoltaic (PV) and electrochemical impedance spectroscopy (EIS) characterization of DSSCs were performed. The maximum energy conversion efficiencies of these photoanodes in the presence of NH3, NH3-PEG and NH3-PVA were obtained as 1.57, 0.70 and 1.61, respectively, for the same type of electrolyte (AN50) under 100 mW/cm2 illumination.Öğe High photo-responsivity Au/polyvinyl alcohol (PVA)+di[1-(2-ethoxyethyl)-5-nitrobenzimidazole] copper dichloride/n-Si UV photodiode(Elsevier Science Sa, 2020) Gokcen, Muharrem; Orhan, Ersin; Taran, SongulAu/n-Si metal/semiconductor (MS) type diode was transformed into a metal/polymer/semiconductor (MPS) type diode by polyvinyl alcohol (PVA)+benzimidazole Cu complex interfacial layer to achieve better photodiode properties. Au/PVA + benzimidazole Cu complex/n-Si MPS diode's electronic and photo-responsivity (PR) properties were investigated by current-voltage (I-V) measurements under various ultraviolet (UV) (365 nm wavelength) illumination intensities (from 50 to 250 mW/cm(2)) and at room temperature. It was found that the difference between the dark and high UV illumination I(V) plots of the MPS diode exceeds 10(5) times. Thus, this higher response to UV illumination has caused the reverse region current of the diode exceeds the forward region current since the first UV illumination level (50 mW/cm(2)). This ensures both the MPS diode has a very high PR value and allows that the diode working direction can be adjusted with UV exposure. The remarkably high PR values were obtained for P = 100 mW/cm(2) as 11.01 A/W at -4.84 V, and 2.14 mA/W at 0 V. Also, main electronic parameters of the MPS diode were calculated by thermionic emission, Ohm law, Cheung&Cheung and Card&Rhoderick methods. The series resistance (Rs) values calculated for each Cheung&Cheung function are compatible each other and there is an acceptable coherence with obtained values by ohmic approach. For the surface states density (N-ss) of the MPS diode obtained for each UV illumination, it was found that they are higher than the dark ones and they shifted to lower energy region. (c) 2020 Elsevier B.V. All rights reserved.Öğe Synthesis and characterization of novel benzimidazole cobalt and copper complexes and applying in Au/PVA/n-Si diode(Elsevier, 2020) Gokcen, Muharrem; Orhan, Ersin; Taran, SongulA new stable solid di[1-(2-ethoxyethyl)-5-nitrobenzimidazole] cobalt dichloride (2) and di[1-(2-ethoxyethyl)-5nitrobenzimidazole] copper dichloride (3) were prepared by the combination of 1-(2-ethoxyethyl)-5-nitrobenzimidazole (1) with metal salts (CoCl2 center dot 6H(2)O and CuCl2 center dot H2O). Synthesized di[1-(2-ethoxyethyl)-5-nitrobenzimidazole] cobalt dichloride (2) and di[1-(2-ethoxyethyl)-5-nitrobenzimidazole] copper dichloride (3) were identified by H-1 NMR and C-13 NMR spectroscopic techniques and elemental analysis. Poly vinyl alcohol (PVA) polymer with and without novel benzimidazole cobalt and copper complexes dopant interfacial layers were used in Au/n-Si diodes. The basic electrical properties of these fabricated four diodes were examined using currentvoltage (I-V) measurements in dark and room temperature. The n and I0 values of all MPS diodes are smaller than the MS diode and the Phi(B0) values are greater.Öğe Synthesis of benzimidazole moiety heteroleptic ruthenium complex and use as sensitizer in dye-sensitized solar cells(Springer Heidelberg, 2021) Orhan, Ersin; Gokcen, Muharrem; Taran, SongulThe new benzimidazole functional heteroleptic ruthenium complex dye (BRD) was prepared for dye-sensitized solar cells (DSSCs). The compound was identified by various spectroscopic techniques and photovoltaic performances of this BRD DSSC were investigated and compared with Z907 (cis-diisothiocyanato-(2,2 '-bipyridyl-4,4 '-dicarboxylic acid)-(2,2 '-bipyridyl-4,4 '-dinonyl) ruthenium(II)) DSSCs. It was found that [Ruthenium (4,4 '-dicarboxylic acid-2,2 '-bipyridine) (1-(2-ethoxyethyl)-2-(pyridine-2-yl)benzimidazole) (NCS)(2)] (2) has a thermal stability below 300 degrees C. Two different electrolytes were used to get the effect on photovoltaic parameters. The photovoltaic measurements of the BRD and Z907 DSSCs were carried out under 100 mW/cm(2) (AM1.5) illumination. Short-circuit current density (J(sc)) values were obtained as 8.20 and 7.32 mA/cm(2) for AN50 and HI30 electrolytes, respectively. The photovoltaic efficiencies were obtained as 3.03% and 2.82% for AN50 and HI30 electrolytes, respectively.Öğe ULTRAVIOLET ILLUMINATION RESPONSIVITY OF THE Au/n-Si DIODES WITH AND WITHOUT POLY (LINOLENIC ACID)-G-POLY (CAPROLACTONE)-G-POLY (T-BUTYL ACRYLATE) INTERFACIAL LAYER(World Scientific Publ Co Pte Ltd, 2020) Gursel, Umit; Taran, Songul; Gokcen, Muharrem; Ari, Yurdagul; Alli, AbdulkadirAu/n-Si (MS) and Au/Poly (linolenic acid)-g-poly (caprolactone)-g-poly (t-butyl acrylate) (PLilPCLPtBA)/n-Si (MPS) diodes were fabricated to investigate the electrical and responsivity effects of interfacial layer on the diodes under ultra violet (UV) illumination. Electrospinning method was used for coating of the PLilPCLPtBA polymer layer on n-Si single crystal as nanofibers. Surface formation and nanofiber characteristics of the polymer layer were investigated by an electron microscope. The current-voltage (I-V) measurements of the MS and MPS diodes were carried out in dark and under UV (365 nm) illumination conditions at room temperature. Basic electrical parameters of the diodes; such as reverse bias saturation current (I-0), zero bias barrier height (Phi(B0)), ideality factor (n), series resistance (R-s) and interface state density (N-ss) were extracted from the experimental I-V measurements by thermionic emission and Norde equations. Also, power law of the photocurrents (I-pc) and responsivity (R) behavior were obtained and given comparatively.
