Browsing by Author "Ugur, Ali"

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Electrical and Photoelectrical Characterization of an Organic-Inorganic Heterojunction Based on Quinoline Yellow Dye
(Elsevier Sci Ltd, 2015) Ugur, Ali; Imer, Arife Gencer; Ocak, Yusuf Selim
An organic-inorganic contact was fabricated by forming a thin film of quinoline yellow dye (QY) on a p-Si wafer and evaporating Al metal on the film. The current-voltage (I-V) and capacitance-voltage (C-V) measurements of Al/QY/p-Si heterostructure were applied in dark and room temperature to calculate the characteristic parameters of diode like ideality factor, barrier height and series resistance. Ideality factor and barrier height values were found as 1.23 and 0.87 eV from I-V data, respectively. The series resistance value of the device was determined as 1.8k Omega by using modified Norde function. The C-V measurements were carried out at different frequencies and it was seen that capacitance value decreased with increasing frequency. Interface state density distribution was calculated by means of I-V measurement. In addition the optical absorption of thin QY film on glass was measured and optical band gap of the film was found as 2.73 eV. Furthermore, I-V measurements of Al/QY/p-Si/Al were taken under illumination between 40 and 100 mW/cm(2). It was observed that reverse bias current of the device increased with light intensity. Thus, the heterojunction had a strong response to the light and it can be suitable for electrical and optoelectronic applications like a photodiode. (C) 2015 Elsevier Ltd. All rights reserved.
Enhancement in the Photovoltaic Efficiency of Dye-Sensitized Solar Cell by Doping Tio2 With Mil-101 Mof Structure
(Elsevier Sci Ltd, 2022) Ugur, Ali; Imer, Arife Gencer; Gulcan, Mehmet
In this work, pure and MIL-101 doped TiO2 films on fluorine doped tinoxide (FTO) were prepared by sol-gel method for dye sensitized solar cell (DSSC) fabrication. MIL-101 metal-organic framework (MOF) structure was synthesized by hydrothermal method and it was used as dopant in TiO2 to enhance an efficiency of DSSC device for the first time. The surface morphology of pure and MIL-101 doped TiO2 films were characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX), the crystallite size and structural properties of these films were studied by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) techniques, respectively. Ultraviolet-visible spectroscopy (UV-Vis) measurement presents the change in an optical characteristic and the band gap of the film with MIL-101 incorporation owing to its high surface area. The efficiency enhancement in DSSC device with MIL-101 doping was analyzed via current-voltage (I-V) measurement under various power of solar simulator. The results confirm that power conversion efficiency (PCE) can enhance with MIL-101 doping into TiO2. The power conversion efficiency of MIL101@DSSC is 8.687% under 100 mW/cm(2) illumination power, which is 1.85 times greater than PCE of undoped DSSC (4.689%). The enhancing efficiency of MIL-101@DSSC can be associated with the energy band alignment, improvement in photoelectron trapping, and increase in dye adsorption owing to pore structure of MIL-101.
Improved Efficiency in Dye Sensitized Solar Cell (Dssc) by Nano-Mil Impregnated Photoanode
(Walter de Gruyter Gmbh, 2022) Ugur, Ali; Imer, Arife Gencer; Kaya, Esra; Karatas, Yasar; Gulcan, Mehmet
In the present work, MIL-101 nanoparticles (nano-MIL-101(Cr)) metal-organic framework (MOF) structure was synthesized by hydrothermal method, and characterized via Fourier transform infrared, X-ray diffraction, and scanning electron microscopy techniques. The optoelectronic application of MOFs was investigated for the first time. For this purpose, the dye-sensitized solar cells (DSSCs) consisting of the synthesized nano-MIL-101(Cr) impregnated photoanode (PA) was fabricated, and photovoltaic, photoelectric properties of them were investigated under different illumination intensities, and the obtained results were compared with reference one. The DSSC fabricated by impregnated PA showed better photovoltaic properties than reference one. It is obtained the power conversion efficiency (PCE) of about 0.828 and fill factor (ff) of 0.656 for the fabricated DSSC based on nano-MIL-101(Cr) impregnated PA under illumination power of 100 mW/cm(2) by AM1.5 G solar simulator. For the reference DSSC, PCE, and ff is about 0.468 and 0.28, respectively. The PCE of the fabricated device based on nano-MIL-101(Cr) is similar to 77% greater than the reference one. The improvement in the efficiency is because of good electrocatalytic activity, large pores, and high surface area of nano-MIL-101(Cr). The nano-MIL-101(Cr) can be used in organo-optoelectronic device fabrication to obtain better performance.
The Investigation of the Fundamental Electrical Parameters of Ag/N-si Hybrid Structure Based on Functional Organic Dye
(Elsevier, 2021) Mahmood, Othman Haji; Imer, Arife Gencer; Ugur, Ali; Korkut, Abdulkadir
The electrical parameters of Ag/n-Si contact and the hybrid structure has been investigated due to their possible usage in optoelectronic device applications. In this study, the hybrid structure was fabricated using the brilliant blue film as an organic interlayer formed via spin coating method. The electrical parameters of both devices have been determined and compared using the current-voltage (I-V) and capacitance-voltage (C-V) measurements at room temperature. The experimental results confirmed that the barrier height of hybrid structure is considerably affected; and its performance and quality can be modified/controlled by the functional interfacial organic layer. (c) 2021 Elsevier Ltd. Selection and peer-review under responsibility of the scientific committee of the International Congress on Semiconductor Materials and Devices, ICSMD2018.
The Photodetection Characteristics of a Brilliant Blue-Fcf Implemented Device for Organic-Based Optoelectronic Applications
(Pergamon-elsevier Science Ltd, 2024) Mahmood, Othman Haji; Ugur, Ali; Imer, Arife Gencer
The optical properties of sol-gel-based brilliant blue-FCF (BB-FCF) thin film are analyzed for photodetection applications. The effect of the presence of the BB-FCF interface on the microelectronic characteristics of the designated Cu/BB-FCF/n-Si device is elucidated by comparing to its reference Cu/n-Si device. The systematic investigation of photodetection properties of the integrated device is performed between the 20-100 mW/cm(2) illumination intensities. First, the optical features of spin-coated BB-FCF thin film are investigated by UV-Vis measurements, and the absorbance of the film is elucidated by the efficient optical absorption in the wavelength of similar to 350-700 nm with the calculated optical indirect band gap of 1.72 eV. Next, the frequency-dependent capacitive behavior, charge transport mechanism, and the electronic parameters of both the rectifying Cu/n-Si and the implemented Cu/BB-FCF/n-Si devices like the ideality factor, the barrier height, and series resistance are estimated using the Thermionic emission and Norde's function methods. Subsequently, the photodetection properties of the engineered device with a BB-FCF functional dye interface are studied under a solar simulator with different power intensities. The effect of the illumination intensity and applied reverse bias voltage on the figures of merit, including photoresponsivity, photodetectivity, response speed, and linear dynamic property, are analyzed under an illumination of 20-100 mW/cm(2). The designated device with a BB-FCF interface has achieved significant and fast, stable on/off switching sensitivities, with 524 ms and 629 ms rising and falling times, respectively. Therefore, the prepared BB-FCF-based device has good and stable photoresponse performance, and the Cu/BB-FCF/n-Si architecture device may be a strong candidate for photonic and optoelectronic device applications, particularly in rapidly developing organic material-based device technology.
Physical Properties of Ultrasonically Spray Deposited Yttrium-Doped Sno2 Nanostructured Films: Supported by Dft Study
(Springer Heidelberg, 2021) Kaya, Esra; Ugur, Ali; Imer, Arife Gencer; Aycibin, Murat; Ocak, Yusuf Selim
The physical properties of ultrasonically spray deposited Yttrium (Y) doped tin dioxide (SnO2) are experimentally and theoretically investigated. The different diagnostics techniques such as X-ray diffraction (XRD), UV-Vis, scanning electron microscopy (SEM) and Hall effect measurements were performed to analyze the influence of yttrium doping ratio on the structural, optical and electrical properties of Y-doped SnO2 nanostructured films. Additionally, density functional theory (DFT) is applied to calculate and check the energy gap, lattice parameters and optical properties of SnO2 with different Y doping ratios. Super cell of Y-doped SnO2 was formed using Wien2k, and analyzed to physical properties of un-doped and Y doped stoichiometry with different ratios. Theoretical results are in agreement with the experimental results and the literature reports. Experimental results show that the optical band gap of fabricated sample increases with the increasing the Y doping amount in the tin dioxide film. The same tendency of energy band gap is observed with DFT calculation for Y-doped SnO2 compound. Theoretical results also show that the lattice parameter is nearly the same for pure and Y-doped SnO2 case, attributed to a change in the stoichiometry owing to metal doping. XRD results reveal that the all fabricated films are polycrystalline in the tetragonal Bravais lattice of tin dioxide(,) and the crystallite size, the crystalline orientation are affected by the Y doping level. The nanosized grains of the produced films are manipulated with increasing the Y dopant confirmed by the SEM. Y doped nanostructured films show the higher optical transmittance about 90% in ultra-violet region. Optical band gap gets widen from 3.689 to 3.810 eV with increasing the dopant amount. From Hall effect results, lower resistivity, higher carrier concentration and high enough mobility have been achieved by Y doping for the sample 5 at% Y:SnO2 based TCO film. The obtained results declared that Yttrium doping has an important effect on the optoelectronic properties, in particular, transparency and conductivity of SnO2 nanostructured film.