Yazar "Aydogan, Sakir" seçeneğine göre listele

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    A comparative study on the effect of monodisperse Au and Ag nanoparticles on the performance of organic photovoltaic devices
    (Elsevier, 2021) Kacus, Hatice; Metin, Onder; Sevim, Melike; Biber, Mehmet; Baltakesmez, Ali; Aydogan, Sakir
    The monodisperse Au (similar to 5 nm) and Ag (similar to 3 nm) nanoparticles used in this study were obtained using surfactant-assistant solvothermal methods and characterized by XRD TEM and SEM. Then, these nanoparticles were embedded into the P3HT:PCBM photoactive layer at different ratios and the effects of the nanoparticles on the performance of the organic solar cells have been studied by varying the loading percent of the NPs in the range of 0.5-2 wt%. The best solar cell composition was determined to be 1 wt% for Au NPs and 0.5 wt% for Ag NPs. Optical absorption spectrum of P3HT:PCBM, P3HT:PCBM:AuNPs and P3HT:PCBM:AgNPs active layers were obtained using UV-visible spectroscopy. The J-V plots of ITO/PEDOT:PSS/P3HT:PCBM/LiF/Al solar cells having 1.10(-6) m(2) OSC area and with different Au NPs and Ag NPs loading ratios in the P3HT:PCBM were obtained under air mass (AM) 1.5G illumination. Open circuit voltage, short-circuit current density, fill factor, and power conversion efficiency of the OSC were calculated. The highest PCE values were obtained as 3.35% for Au NPs and as 3.50% for Ag NPs doped devices. This increase in PCEs was explained by a plasmonic effect that stems from the metallic NPs.
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    Improving the performance of the organic solar cell and the inorganic heterojunction devices using monodisperse Fe3O4 nanoparticles
    (Elsevier Gmbh, Urban & Fischer Verlag, 2017) Caldiran, Zakir; Biber, Mehmet; Metin, Onder; Aydogan, Sakir
    8 nm Fe3O4 nanoparticles (NPs) were successfully doped into poly(3hexylthiophene):phenyl-C-61-butyric acid methyl ester (P3HT:PCBM) to fabricate ITO/PEDOT:PSS/P3HT:PCBM:Fe3O4/AI solar cell along with a heterojunction device of Fe3O4/p-GaAs by depositing them on p-GaAs substrates. The experimental results revealed that the presence of Fe3O4 nanoparticles (NPs) in the ITO/PEDOT:PSS/P3HT:PCBM/A1 solar cell improved its performance with respect to the one without Fe3O4. For example, power conversion efficiency was increased from 1.09% to 2.22% when doping 5 wt% of Fe3O4 NPs to P3HT:PCBM. This was attributed to increase of the light absorption in the presence of Fe3O4 NPs doping. Furthermore, the analysis of the current-voltage (I-V), capacitance-voltage (C-V) and capacitance-frequency (C-f) characteristics of the Fe3O4/p-GaAs heterojunction have been studied successfully. The experimental barrier height Ob and ideality factor n were determined as 0.80 eV and 1.53, respectively, from the experimental I-V plots. In addition, the value of the Phi(b) obtained from the C-V characteristics was 0.95 eV (f= 500 kHz). The mismatch between barrier heights obtained from both measurements was explained by the two techniques are based on different nature. The interface state density of the Fe3O4/p-GaAs heterojunction was determined from 5.16 x 10(14) cm(-2)eV(-1) to 1.34 x 10(15) cm(-2)eV(-1). (C) 2017 Elsevier GmbH. All rights reserved.
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    The influence of annealing temperature and time on the efficiency of pentacene: PTCDI organic solar cells
    (Elsevier Science Bv, 2017) Biber, Mehmet; Aydogan, Sakir; Caldiran, Zakir; Cakmak, Bulent; Karacali, Tevhit; Turut, Abdulmecit
    In this study, fabrication of a polycyclic aromatic hydrocarbon/Perylene Tetracarboxylic Di-Imide (PTCDI), donor/acceptor solar cells are presented using physical vapour deposition technique in a 1000 class glove box. An ITO/PEDOT:PSS/Pentacene/PTCDI/Al (ITO = Indium Tin Oxide and PEDOT:PSS = poly(3,4-ethylene dioxythiophene) polystyrene sulfonate) solar cell has been obtained and the power conversion efficiency, PCE (eta) of about 0.33% has been obtained under simulated solar illumination of 300 W/m(2). Furthermore, the effects of annealing temperatures (at 100 and 150 degrees C) and of annealing (at 100 degrees C) times for 5 and 10 min. on the power conversion efficiency, eta of the solar cells have also been investigated. In general, it has been seen that the thermal annealing deteriorated the characteristics parameters of Pentacene/PTCDI solar cell such that both fill factor, FF and eta decreased after annealing and with increase of annealing time. Atomic force microscopy (AFM) images showed that the phase segregation and grain size increased and the surface roughness of Pentacene film decreased and these effects reduced the eta value. The eta values of the solar cell have been determined as 0.33%, 0.12% and 0.06% for pre-annealing, annealing at 100 and 150 degrees C, respectively. (C) 2017 Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license
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    Investigation of electrical properties of Ni/Crystal Violet (C25H30CIN3)/n-Si/Al diode as a function of temperature
    (Elsevier Science Sa, 2018) Deniz, Ali Riza; Caldiran, Zakir; Biber, Mehmet; Incekara, Umit; Aydogan, Sakir
    In this study, Crystal Violet material was used for interface layer of Schottky diode applications. Firtly, chemical cleaning process have been made for boron doped n-Si crystals. After, Al metal was coated on the one surface of crystals by thermal evaporation and crystal violet materials were coated on other surface of crystals with spin coating method (coating parameters; 800 rpm for 60 s). Lastly, Ni metal was coated on Crystal Violet by sputtering. So, we obtained the Ni/Crystal Violet/n-Si/Al Schottky type diode. After the fabrication process of diode, the current-voltage (I-V) and capacity-voltage (C-V) measurements of Ni/Crystal Violet/n-Si/Al Schottky type diode were taken for various temperatures. The some basic diode parameters such as ideality factor (n), barrier height (Phi(b)) and series resistance (Rs) of Ni/Crystal Violet/n-Si/Al were calculated from I-V measurements using different methods (Thermionic Emission, Cheung and Norde functions). Also, diode parameters such as Fermi energy level, diffusion potential, carrier concentration and barrier height were calculated from the C-V measurements of diode as a function of temperature. (C) 2018 Elsevier B.V. All rights reserved.
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    On thermal and optical sensor applications of chitosan molecule in the Co/Chitosan/p-Si hybrid heterojunction design
    (Springer, 2021) Kacus, Hatice; Aydogan, Sakir; Incekara, Umit; Yilmaz, Mehmet; Biber, Mehmet
    Co/Chitosan/p-Si/Al and Co/p-Si devices were made and barrier height and ideality factor values of both devices were determined at room temperature (dark conditions). After the chitosan interlayer was found to improve the device, the thermal and photosensivity properties of the Co/Chitosan/p-Si/Al device were investigated in detail. The current-voltage measurements of Co/Chitosan/p-Si/Al heterojunction were performed in temperature range of 100-460 K and illumination intensity range of 100-400 mW/cm(2). It was seen that the device parameters such as barrier height, ideality factor, series resistance and interface states density were strongly dependent on temperature. Furthermore, the capacitance-voltage (C-V) characteristics of the device were investigated at various frequencies at room temperature. The responsivity (R), detectivity (D*) and rectification ratio (RR) values of the Co/Chitosan/p-Si/Al heterojunction were found to be as a function of illumination intensity. The experimental results show that the fabricated device with chitosan thin film interlayer can be used in various optoelectronic applications, especially applications in low temperature switching devices, energy generation, photodiode and photodetector.
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    Phenol red based hybrid photodiode for optical detector applications
    (Pergamon-Elsevier Science Ltd, 2020) Kacus, Hatice; Sahin, Yilmaz; Aydogan, Sakir; Incekara, Umit; Yilmaz, Mehmet; Biber, Mehmet
    In this study, the phenol red (PR) dye film has been deposited on n-type silicon wafer and SEM, XRD measurements of the film have taken. Then, the PR/n-Si photodiode has been fabricated and (dark) electrical and photoresponse characterization has been analysed. The current-Voltage (I-V) measurements have been carried out at varied light power ranging from 100 mW/cm 2 to 400 mW/cm(2). Rectification ratios (RR) have been determined as a function of illumination intensities and they are determined as 115.47 for 100 mW/cm(2) and 30.26 for 400 100 mW/cm(2), respectively. The ideality factor and the barrier height of the Co/PR/n-Si photodiode have been determined as 2.80 and 0.52 eV, respectively in dark. Therefore, it has been seen that the PR/n-Si photodiode performances are strongly dependent on the incident optical power. Namely, the current density has increased remarkably with the power of light at the same reverse bias voltage and this behavior is explained by strong capability of converting a light signal into an electrical for the PR/n-Si photodiode device. Responsivity (R) and detectivity (D*) of the PR/n-Si photodiode are also plotted as a function of illumination intensities for reverse biases and it is found that both parameters are dependent on the illumination intensity. Finally, the capacitance-voltage (C-V) characteristics of the device have been carried out at various frequencies. Obtained experimental results indicate that the PR dye can be used in various optoelectronic applications.
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    Role of the Au and Ag nanoparticles on organic solar cells based on P3HT:PCBM active layer
    (Springer Heidelberg, 2020) Kacus, Hatice; Biber, Mehmet; Aydogan, Sakir
    In this article, P3HT:PCBM blend active layer was incorporated with Au and Ag nanoparticles (NPs) for different concentration to investigate the effects of the NPs on the performance organic solar cells (OSCs) with ITO/PEDOT:PSS/P3HT:PCBM:NPs/LiF/Al design. The active layer was analyzed by AFM, SEM and XRD measurements. Optical energy gap of P3HT:PCBM (undoped) and P3HT:PCBM (doped) active layers were obtained using UV-visible spectroscopy for different concentrations. The photovoltaic current density-voltage measurements were carried out under air mass (AM) 1.5G solar simulation. The OSC whose active layer undoped, gave the J(sc) of 17.09 mA/cm(2), V-oc of 0.48 V, FF of 45%, and PCE of 2.11%. Whereas, the highest values of PCE were calculated as 3.11% for doped with Au NPs (1.5 wt%) and as 3.20% for Ag NPs (0.5 wt%), respectively. In summary, Au and Ag NPs created strong local electric field enhancements and caused to a surface plasmonic effect in the active layer for some concentrations and improved the device's PCE.