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Öğe 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, SakirThe 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.Öğe Determination of albedo parameters of the organometallic halide perovskite films(Pergamon-Elsevier Science Ltd, 2020) Yilmaz, Demet; Baltakesmez, Ali; Uzunoglu, Zeynep; Biber, MehmetIn this work, albedo number, energy and dose of the perovskite films were determined by the gamma ray spectrometry. The MAPbBr(3-x)Cl(x), MAPbBr(3-x)I(x), MAPbl(3-x)Cl(x) and MAPbl(3) thin films were coated on the Pedot:PSS/ITO substrates by static spin coating technique. The structural properties of the films were determined with field emission scanning electron microscopy (FE-SEM) images and X-ray diffraction (XRD) patterns. Albedo parameters of perovskite films were carried out by using a high purity germanium detector with a resolution of 182 eV at 5.9 keV and 59.54 keV gamma-rays emitted from a radioactive source of Am-241 (59.54 keV). In XRF experiments, the scattering angle was set 168 degrees. XRD patterns show that perovskite structure has forming tetragonal with high crystallinity. Also, the perovskite layer has compact and high coverage capability and uniform surface feature in terms of FE-SEM morphology. It is observed that albedo parameters are dependent on the density, the mean atomic number and the average band gap energy of perovskite films. Also, high energy radiation scattering from the perovskite films appears to be enhanced significantly with the MABr treatment.Öğe Improved perovskite film quality and solar cell performances using dual single solution coating(Aip Publishing, 2017) Baltakesmez, Ali; Biber, Mehmet; Tuzemen, SebahattinIn this study, we present high quality perovskite CH3NH3PbI3-xClx thin films prepared by a combination of static and dynamic coating approaches, named dual single solution coating. Static coating, dynamic coating and the combination of these are comparatively studied. Scanning electron microscopy, X-ray diffraction, atomic force microscopy, UV-visible spectroscopy, and photoluminescence techniques are used for the determination of morphological, structural, and optical properties of thin films prepared using different coating approaches and deposition temperatures. All the coating approaches are repeated at room temperature and with hot deposition. The high quality and density CH3NH3PbI3-xClx films with full surface coverage are obtained using thedual single solution coating, particularly with hot-deposition. The perovskite solar cells prepared by the dual coating approach with hot deposition have better values for all the performance parameters in comparison to the other coating approaches, resulting in high efficiencies. The best device has a short circuit current of 22.03 mA/cm(2), an open circuit voltage of 0.91V, a fill factor of 0.73, and a power conversion efficiency of 14.68% from short-circuit to forward bias, and 22.39 mA/cm(2), 0.91 V, 75% and 15.32% for the vice-versa, respectively. Published by AIP Publishing.Öğe 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, Sakir8 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.Öğe 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, AbdulmecitIn 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 licenseÖğe Interface application of NiPt alloy nanoparticles decorated rGO nanocomposite to eliminate of contact problem between metal and inorganic/organic semiconductor(Elsevier Science Sa, 2021) Baltakesmez, Ali; Sevim, Melike; Guzeldir, Betul; Aykac, Cengiz; Biber, MehmetIn this study, synthesis of monodisperse NiPt alloy NPs, preparation of rGO, decoration of the NPs onto the rGO and interface application of the NiPt/rGO nanocomposite material were presented. Morphological and structural analysis showed that Ni70Pt30 NPs having particle size of 2.2 +/- 0.4 nm were obtained and de-corated onto the rGO. The I-D/I-G intensity ratio of the rGO was determined to be 1.02. On the other hand, the Ni70Pt30/rGO nanocomposite was used as interface layer in junctions of the Al/lnP and P3HT:PCBM/Al. In the Al/lnP as inorganic metal-semiconductor junction, the interface layer caused an increase in rectification ratio of up to 10(3). Moreover, the ideality factor and barrier height enhanced from 1.47 and 0.49 eV to 1.24 and 0.67 eV at 300 K. It is attributed to eliminate of metal diffusion in lnP and passivation of pinning Fermi level. Additionally, the Ni70Pt30/rGO nanocomposite layer was used fabrication of the P3HT:PCBM solar cell to eliminate of S-shaped J-V curve. The reference solar cell having S-shaped J-V curve showed 6.081 mA/cm(2) short circuit current density, 0.572 V open circuit voltage, 31.4% fill-factor and then 1.092% power conversion efficiency. The presence of the interface layer has caused an increase in the fill-factor value of more than 30%, while the PCE value increased by 15%. The best cell has 1.244% power conversion efficiency with 5.554 mA/cm(2) short circuit current density, 0.544 V open circuit voltage, 41.2% fill-factor. (C) 2021 Elsevier B.V. All rights reserved.Öğe 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, SakirIn 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.Öğe 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, MehmetCo/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.Öğe Optimizing quality of lead-free perovskite thin film with anti-solvent engineering and co-doping SnBr2/SnF2; its solar cell performance(Elsevier, 2020) Baltakesmez, Ali; Guezeldir, Betuel; Alkan, Yunus; Saglam, Mustafa; Biber, MehmetLead-free perovskite film is crucial for non-toxicity device applications and tin-based perovskite is one of most promising non-toxic perovskites. In this study, Br and F doping and anti-solvent washing process were investigated for suitable MASnI3 perovskite film. The structural, morphological and optical analyses showed the only Br or F doping is not enough to obtain of tin-based perovskite films having high crystallinity, surface coverage and absorbance properties. The Br and F co-doping (1 M(MAI):0.6 M(SnI2):0.2 M(SnBr2):0.2 M(SnF2)) has caused significantly decrease in morphological defects and increase crystallinity. Moreover, addition to the co-doping, void-free film morphology has been obtained by anti-solvent washing process: toluene:chloroform (1:1 vol%). Thus, oxidation of Sn2+ to Sn4+ was successfully suppressed. The optimized Sn-based perovskite film has band gap energy of 1.31 eV and atomic ratio determined to be 1.00:0.15:0.03 from the EDS and 1.00:0.16:0.07 from the XPS for I:Br:F, which indicates I-rich stoichiometric content. The solar cell application has been also performed in device structure of ITO/PEDOT:PSS (60 nm)/perovskite (272 nm)/PCBM (70 nm)/Al (100 nm). The best solar cells prepared using the co-doped perovskite films without and with anti-solvent washing process have PCE values of 2.25% with Jsc 14.9 mA/cm(2), Voc 0.42 V and FF 36% and 4.45% with Jsc 17.8 mA/cm(2), Voc 0.48 V and FF 52%, respectively.Öğe 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, MehmetIn 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.Öğe Photo-sensor characteristics of tannic acid (C76H52O46)/n-Si hybrid bio-photodiode for visible and UV lights detection(Elsevier Sci Ltd, 2022) Yildirim, Fatma; Orhan, Zeynep; Taskin, Mesut; Incekara, Umit; Biber, Mehmet; Aydogan, S.We present the electo-optical characterization of tannic acid (TA)/n-Si heterojunction for visible and UV lights (365 nm and 395 nm). The TA was deposited on n-Si by spin coating. The morphological and structural analyses of TA film were carried out by Scanning Electron Microscopy (SEM) and Energy-dispersive X-ray (EDX) analyses, respectively. The electro-optical performance of the TA/n-Si bio-photodiode were investigated by I-V measurements for 10 mW/cm(2), 15 mW/cm(2), 20 mW/cm(2) and 30 mW/cm(2) visible light intensities in addition to UV light. Light-dependent the responsivity, ON/OFF ratio, detectivity, shunt resistance and series resistance were calculated. Maximum values of responsivity, detectivity and ON/OFF ratio were determined as 11.9 mA/W (-1.5 V), 3.2 x 109 Jones (at-0.42 V) and 194 (30 mW/cm2) (AM 1.5 G), at-2 V respectively. Whereas, they were determined to be 0.1 A/W, 4 x 109 Jones and 14977, respectively for UV light. Furthermore, the dielectric properties of the TA/n-Si heterostructure also were investigated from the dark Capacitance/Conductance-Voltage measurements. It was seen that both real and imaginary parts of the dielectric constants was frequency dependent. Experimental results show that the TA/n-Si device with a high rectification ratio of 2263 is a potential candidate for detecting visible and UV lights.Öğe Review of the fundamental issues in new generation high efficiency perovskite solar cells(Elsevier, 2019) Baltakesmez, Ali; Biber, Mehmet; Tuzemen, SebahattinThis is a mini review of the fundamental issues in producing high efficiency solar cells. We have raised many important issues that limit the power conversion efficiency, and introduced the solutions in particular to perovskite solar cell structures. We supposedly estimate very high efficiencies over detailed balance or Schockley-Quessier limit up to 50 %, having applications such as tandem cells, light concentration, inter-band activities with deep levels, photon upconversion and quantum dots together with some unique processing systems. (C) 2019 Elsevier Ltd. All rights reserved.Öğe 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, SakirIn 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.
