Yazar "Baltakesmez, A." seçeneğine göre listele

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    Effects of the PENTACENE as doping material on the power conversion efficiency of P3HT:PCBM based ternary organic solar cells
    (Elsevier, 2021) Caldiran, Z.; Erkem, U.; Baltakesmez, A.; Biber, M.
    In organic solar cells (OSCs), changing the device geometry and the photophysical properties of the active layer is an effective way to change the power conversion efficiency (PCE). For this purpose, both the buffer layer was coated between the active layer and the metal and the organic material was doped to the active layer to obtain the ternary structure. In this study, for the fabrication of bulk-heterojunction (BHJ) organic solar cell, the PEDOT:PSS layer was coated on chemically cleaned ITO coated glass substrates by the spin coating method. Subsequently, the P3HT:PCBM blend as an active layer was coated on top of PEDOT:PSS in the glove box using the same method. Finally, aluminum (Al) was coated using thermal evaporation and ITO/PEDOT:PSS/P3HT: PCBM/Al organic solar cells structure as reference device were obtained. Then, PENTACENE material with an organic semiconductor property was doped into P3HT:PCBM blend and ITO/PEDOT:PSS/P3HT:PCBM:PENTACENE/Al bulk heterojunction organic solar cell structure was obtained using the same method. In addition, the effects of OSC on PCE were investigated by coating the 2 nm lithium fluoride layer between the Al and the active layer. For devices, dark and light current density-voltage (J-V) measurements were performed under 100 mW/ cm2 in the glove box, and device parameters were calculated by the J-V curve. It was observed that the reference device showed photovoltaic properties under light and its PCE was 0.64%. When the experimental findings obtained were examined, both the LiF buffer layer and PENTACENE doping material improved the ternary OSC device performance and increased the PCE from 0.64% to 2.65%, according to the reference device. As a result of the doping, the mobility of the carrier increased with the increase of photon absorption and the presence of the buffer layer increased the carrier injection. Changing device properties can be explained with these results.
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    Interpretation of the I-V, C-V and G/?-V characteristics of the Au/ZnS/n-GaAs/In structure depending on annealing temperature
    (Elsevier, 2021) Baltakesmez, A.; Guzeldir, B.; Saglam, M.; Biber, M.
    The Zinc Sulphide (ZnS) thin film, which is included in the Au/n-GaAs/In diode as the interface layer, was grown on the n-GaAs semiconductor substrate by the spray pyrolysis method. First, to reveal some structural, surface and optical properties of the ZnS thin film, XRD, SEM and absorption measurements were taken. It was determined that the ZnS thin film completely covering the surface of the n-GaAs semiconductor substrate has a hexagonal structure and a forbidden energy range of 3.83 eV. Later, the current-voltage (I?V), the capacitancevoltage (C?V) and the conductance-voltage (G/?-V) measurements of the Au/ZnS/n-GaAs/In structure were taken at room temperature, and various important parameters of the structure were calculated with different methods. In order to reveal the effects of annealing temperature on the I?V, C?V and G/?-V measurements of Au/ ZnS/n-GaAs/In structure, the device was annealed at 100, 200 and 300 ?C respectively for 5 min in nitrogen gas environment. The characteristic parameters were calculated again and the results were interpreted comparatively. At the same time, with the help of the C?V and G/?-V characteristics, the dependence on applied bias voltage and frequency of the parameters such as dielectric constant, dielectric loss, loss tangent, ac electrical conductivity and real and imaginary part of electric modulus of the diode have been revealed. After thermal annealing at 200 ?C, it has been determined that the ideality factor, turn-on voltage and leakage current values are at minimum level and the barrier height and rectification ratio values are at maximum level. In other words, it has been revealed that the optimum thermal annealing temperature for this device is 200 ?C.
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    Inverted planar perovskite solar cells based on Al doped ZnO substrate
    (Elsevier Science Bv, 2018) Baltakesmez, A.; Biber, M.; Tuzemen, S.
    In this study, we present an inverted hybrid perovskite solar cell using Al doped Zinc Oxide (AZO) transparent metal oxide as substrate and anode electrode. Obtained results revealed that the AZO substrates prepared by RF magnetron sputtering with the optimal growth parameters have electrical and optical properties similar to properties of commercial Indium Tin Oxide (ITO), resistivity around 0.5 m Omega cm and transparency around 85%. Hybrid perovskite thin films were coated onto the PEDOT:PSS/AZO and PEDOT:PSS/ITO substrates. The morphological, structural and optical properties of the perovskite films were comparatively studied by SEM, XRD, and UV-visible spectroscopy. Besides, inverted planar perovskite solar cells were fabricated on AZO and on ITO substrates by single solution coating. The champion cell exhibited short-circuit current of 22.26 mA/cm(2), an open-circuit voltage of 0.87 V, and a fill factor of 0.51, led to a power conversion efficiency (PCE) 9.88% which is obtained by cell based on AZO substrate. The PCE value is comparable to efficiency of cell based on ITO, 12.82%. (c) 2017 The Egyptian Society of Radiation Sciences and Applications. Production and hosting by Elsevier B.V.