Yazar "Ozel, Faruk." seçeneğine göre listele

Listeleniyor 1 - 7 / 7
  • Küçük Resim
    Öğe
    The Au/Cu2WSe4/p-Si photodiode: Electrical and morphological characterization
    (ELSEVIER SCIENCE SA, 2019) Kocyigit, Adem.; Yıldırım, Murat.; Sarılmaz, Adem.; Ozel, Faruk.
    Cu2WSe4 nanosheets were synthesized by the hot-injection method and put as interfacial layers between Au metal and p-Si by spin coating technique to investigate their photoresponse and capacitor properties via I-V and C-V measurements, respectively. The XRD were operated to confirm crystalline structure of the Cu2WSe4. The TEM image revealed that the crystalline nanosheet structures of the Cu2WSe4. The I-V measurements were performed under dark and light illumination in the range 20 mW-100 mW light intensities with 20 mW interval. In addition, some diode parameters such as ideality factor, barrier height and series resistance were extracted via a various method and discussed in the details. The C-V measurements were employed for various frequency and voltages. The C-V characteristics of the device confirmed the strong dependence on the frequency and voltage. The results imparted that Au/Cu2WSe4/p-Si can be employed for photodiode, photodetector and capacitor applications. (C) 2018 Elsevier B.V. All rights reserved.
  • Küçük Resim
    Öğe
    The C-V characteristics of the Cu2WSe4/p-Si heterojunction depending on wide range temperature
    (SPRINGER, 2019) Koçyiğit, Adem.; Küçükçelebi, Hayreddin.; Sarılmaz, Adem.; Ozel, Faruk.; Yıldırım, Murat.
    Cu2WSe4 nanosheets were synthesized by hot-injection method and employed as interfacial layers between the p-Si and Au metal via spin coating technique. The capacitance-voltage (C-V) and conductance-voltage (G-V) measurements were performed on the Cu2WSe4/p-Si heterojunction device depending on wide range temperatures from 80 to 400K by 40 K steps. The device exhibited decreasing capacitance behavior with increasing temperature at the inversion region because of the interface states and series resistance. The conductance values increased with increasing temperature owing to increasing free charge carriers. The series resistance (R-s) and interface states density (N-ss) were extracted from C-V and G-V measurements and discussed in the details. The results highlighted that the electrical parameters are a strong function of the voltage and temperature. The Au/Cu2WSe4/p-Si device can be employed for controllable capacitor applications.
  • Küçük Resim
    Öğe
    Donor-pi-acceptor dye-sensitized photoelectrochemical and photocatalytic hydrogen evolution by using Cu2WS4 co-catalyst
    (PERGAMON-ELSEVIER SCIENCE LTD, 2019) Patir, Imren Hatay.; Aslan, Emre.; Yanalak, Gizem.; Karaman, Merve.; Sarilmaz, Adem.; Can, Mumin.; Can, Mustafa.; Ozel, Faruk.
    Photoelectrochemical and photocatalytic hydrogen evolution reaction (HER) have been investigated by using metal free donor-acceptor (D-A) and donor-pi-acceptor (D-pi-A) dyes, which are abbreviated as MC-32 and MC-048, respectively, sensitized TiO2 as a photo-catalyst with or without Cu2WS4 co-catalyst. This co-catalyst is synthesized by a low-cost and simple hot injection method, under visible light illumination. The photoactivities of these dyes have been clarified according to their structural, optical and electrochemical properties. Photocatalytic activities have been slightly increased when added the Cu2WS4 co-catalyst (dye/TiO2/Cu2WS4). This catalytic activity is also compared to that of noble metal Pt (dye/TiO2/Pt). It has been found that 121 mu molg(-1)h(-1), 179 mu molg(-1)h(-1), 348 mu molg(-1)h(-1), 212 mu molg(-1)h(-1), 422 mu molg(-1)h(-1) and 1139 mu molg(-1)h(-1) hydrogen have been evolved by using MC-32/TiO2, MC-32/TiO2/Cu2WS4, MC-32/TiO2/Pt, MC-048/TiO2, MC-048/TiO2/Cu2WS4 and MC-048/TiO2/Pt, respectively. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
  • Küçük Resim
    Öğe
    The effect of the triangular and spherical shaped CuSbS2 structure on the electrical properties of Au/CuSbS2/p-Si photodiode
    (SPRINGER, 2019) Yıldırım, Murat.; Kocyigit, Adem.; Sarılmaz, Adem.; Ozel, Faruk.
    CuSbS2 (Chalcostibite) crystals were synthesized by the hot-injection method as triangular and spherical shaped structures. The crystals were inserted by spin coating technique as interfacial layers between Au metal and p-Si to investigate their electrical and photoresponse properties via I-V measurements under various light intensities. The XRD measurements were performed to show the crystalline structure of the spherical and triangular CuSbS2. The TEM images confirmed the triangular and spherical particle structures of the CuSbS2 crystals. The I-V measurements were performed under dark, 20-100mW light intensities with 20mW interval for spherical and triangular CuSbS2 photodiodes. In addition, diode parameters were extracted and discussed in the details. The results highlighted that triangular and spherical shaped structures have good photoresponse to the illumination and can be employed in the photodiode and photodetector applications.
  • Küçük Resim
    Öğe
    The investigation of novel D-pi-A type dyes (MK-3 and MK-4) for visible light driven photochemical hydrogen evolution
    (ELSEVIER SCI LTD, 2019) Aslan, Emre.; Karaman, Merve.; Yanalak, Gizem.; Can, Mustafa.; Ozel, Faruk.; Patir, Imren Hatay.
    Two novel donor-n-acceptor (D-pi-A) semiconductor organic dyes have been synthesized for the photochemical hydrogen evolution reaction (HER) to sensitize TiO2 for the first time. The molecular structures of D-pi-A semiconductor organic dyes, which are entitled as MK-3 and MK-4, have been characterized by NMR spectroscopy method; and also electrochemical and optical properties have been investigated by cyclic voltammetry and UV-Vis absorption techniques, respectively. Amount of dye loading on TiO2 surface has been investigated by EDX method. The HER activities have been explored in the presence of triethanolamine (TEOA) as a electron donor reagent under sunlight (solar simulator illumination limited by cut-off filter lambda >= 420 nm) in the absence and presence of co-catalysts (Pt and Cu2WS4). Transient photocurrent densities of MK-3/TiO2 and MK-4/TiO2 electrodes have been reached to 110 mu A cm(-1) and 275 mu A cm(-1), respectively. The photocatalytic HER activities have been relatively enhanced in the presence of the Pt or Cu2WS4 co-catalysts (dye/TiO2/Cu2WS4 or dye/TiO2/Pt) when compared to only dye/TiO2. The HER rates have been found as 427, 1277, 675, 682, 1027 and 795 mu molg(-1) h(-1) for the MK-3/TiO2, MK-3/TiO2 /Pt, MK-3/TiO2/Cu2WS4, MK-4/TiO2, MK-4/TiO2/Pt and MK4/TiO2/Cu2WS4 , respectively. The differences of photochemical activities of MK-3/TiO2 and MK-4/TiO2 have been stated taking into account dye molecule structures. Moreover, the HER mechanism have been described by using electrochemical band energy levels of dyes, TiO2 and Cu2WS4 co-catalyst.
  • Küçük Resim
    Öğe
    Synthesis of novel tetrazine based D-pi-A organic dyes for photoelectrochemical and photocatalytic hydrogen evolution
    (ELSEVIER SCIENCE SA, 2020) Aslan, Emre.; Karaman, Merve.; Yanalak, Gizem.; Bilgili, Hakan.; Can, Mustafa.; Ozel, Faruk.; Patir, Imren Hatay.
    Two novel donor-pi-acceptor (D-pi-A) dyes, called as MK-2 and MK-8, are synthesized. Their structural, optical and electrochemical properties are investigated by NMR, absorption/photoluminescence spectroscopies and cyclic voltammetry techniques, respectively. Photocatalytic and photoelectrochemical hydrogen evolution properties of these D-pi-A dyes are explored by using triethanolamine (TEOA) as a sacrificial electron donor under anaerobic conditions and visible light irradiation with or without co-catalysts (Cu2WS4 and Pt) for the first time. Photoelectrochemical and photocatalytic hydrogen evolution reaction (HER) activities of these dyes are studied by using TiO2 coated FTO electrodes and powdered TiO2 (Degussa P25), respectively. Photoelectrochemical response of MK-2/TiO2 and MK-8/TiO2 are figured out in the order of 180 mu A cm(-1) and 80 A cm(-1). The photocatalytic hydrogen evolution amounts of MK-2/TiO2, MK-2/TiO2/Cu2WS4, MK-2/TiO2/Pt, MK-8/TiO2, MK-8/TiO2/Cu2WS4 and MK-8/TiO2/Pt are turned out to be 565, 920, 1828, 374, 522 and 1260 mu molg(-1) h(-1), respectively. Dye/TiO2 photocatalysts are displayed good stability in the both photochemical HER experiments. The alteration in the HER activities of MK-2 and MK-8 is explained by molecule structures of dyes. The proposed mechanism of photocatalytic hydrogen evolution is clarified by using electrochemical band levels of each constituent.
  • Küçük Resim
    Öğe
    Ternary CuCo2S4 thiospinel nanocrystal-coated photodiode with improved photoresponsivity and acceptance angles for optoelectronic applications
    (SPRINGER, 2020) Yildirim, Murat.; Kocyigit, Adem.; Sarilmaz, Adem.; Ozel, Sultan Suleyman.; Kus, Mahmut.; Ozel, Faruk.
    Ternary-structured thiospinels have attracted great attention in recent years for energy applications due to their attractive characteristics such as simple production, earth-abundant components and non-toxic nature. In this work, copper cobalt sulfide (CuCo2S4 or carrollite) thiospinel nanocrystals were synthesized by a hot-injection method, and detailed electrical and optoelectronic characterizations were performed in a Schottky device. The synthesized nanocrystals were used as an interfacial layer between the Au metal and p-Si semiconductor to obtain an Au/CuCo2S4/p-Si device. The structural and morphological characterizations confirmed the crystallinity, nanostructure and composition of the CuCo2S4 nanocrystals. The I-V and C-V measurements were employed to characterize the Au/CuCo2S4/p-Si device for various illumination intensities. The obtained device exhibited good rectifying and photodiode properties as well as good photocapacitance. The Au/CuCo2S4/p-Si device can be used and improved for optoelectronic applications.