Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection

Permanent URI for this collectionhttps://hdl.handle.net/11147/7148

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Author: search.filters.author.Diker, HalideSubject: search.filters.subject.Amine modified graphene oxide

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  • Article
    Citation - WoS: 14
    Citation - Scopus: 14
    Dispersion Stability of Amine Modified Graphene Oxides and Their Utilization in Solution Processed Blue Oled
    (Elsevier Ltd., 2020) Diker, Halide; Bozkurt, Hakan; Varlıklı, Canan
    Graphene oxide (GO) was modified with amine derivatives which contain short (SACA) and long (LACA) alkyl chains. SACAs were n-propylamine, dipropylamine, propanolamine and LACAs were 2-ethylhexylamine, di-hexylamine, dioctylamine, and 1,12-diaminododecane and modified GOs (mGOs) were named as nPRYLA-GO, DPRYLA-GO, PRPOHA-GO, 2EHA-GO, DHA-GO, DOA-GO, and DADOD-GO, respectively. Amine modification resulted in approximately 2-folds of decrement in d-spacing of GO (8.36 angstrom). The C:O ratio, N% and d-spacing values were increased as the alkyl chain length of amine source increased. Except for PRPOHA-GO, all of the mGOs were thermally stable until 100 degrees C. All mGOs were dispersed in dimethylformamide (DMF), ethylene glycol (EG) and isopropyl alcohol (iPA). Regardless of their structural differences, all of the mGOs formed stable dispersions in DMF, whereas SACA-mGOs and LACA-mGOs were compatible with EG and iPA, respectively. DMF, EG and iPA dispersions of DOA-GO, 2EHA-GO, nPRYLA-GO and PRPOHA-GO were doped in Al4083 and prepared composites were utilized as hole transport layer in solution processed blue OLEDs. Ground state energy levels of Al4083:DOA-GO, Al4083:EG, Al4083:PRPOHA-GO, Al4083:2EHA-GO and Al4083:nPRYLA-GO extracted from their X-ray photoelectron spectra were 0.49 eV, 0.67 eV, 0.91 eV, 0.98 eV and 1.00 eV below the work function of ITO, respectively. Among all Al4083:mGOs, the best device performance was obtained with the device that contains Al4083:DOA-GO (in EG), which presented 1.6, 1.7 and 1.5 fold enhancements in current, power and external quantum efficiencies, respectively, compared to those of Al4083:EG based device.
  • Article
    Citation - WoS: 28
    Citation - Scopus: 29
    Enhancing the Efficiency of Mixed Halide Mesoporous Perovskite Solar Cells by Introducing Amine Modified Graphene Oxide Buffer Layer
    (Elsevier, 2020) Şahin, Çiğdem; Diker, Halide; Sygkridou, Dimitra; Varlıklı, Canan; Stathatos, Elias
    In this study, graphene oxide (GO) was synthesized via Tour method and then modified with two different amine sources that contained different branched alkyl chains. The GO and modified GOs (mGOs) with dihexylamine (DHA) and 2-ethylhexylamine (2EHA) as amine sources were used respectively as buffer layers in mixed halide mesoporous perovskite solar cells (PSCs) in order to examine whether they could improve their performance. GO and mGO samples were characterized by several techniques such as X-Ray Diffraction, X-Ray photoelectron spectroscopy (XPS), Raman analysis and thermal gravimetric analysis (TGA). The preparation of the CH3NH3PbI3-xClx perovskite solution was performed using standard Schlenk techniques under argon atmosphere to attain a homogeneous coverage of the perovskite film. The solar cells with the additional layer of mGO derivatives between perovskite and hole transporting layer showed an improved overall performance compared to the reference devices which was attributed to the enhanced charge carrier transport via the mGOs. In particular, 10% increase to the overall performance of the solar cells was monitored in devices where 2-ethylhexylamine (2EHA) modified GO was used, compared to standard cell without buffer layer. (C) 2019 Elsevier Ltd. All rights reserved.