Photonics / Fotonik

Permanent URI for this collectionhttps://hdl.handle.net/11147/2590

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Author: search.filters.author.Diker, HalideSubject: search.filters.subject.Graphene oxide

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Now showing 1 - 3 of 3
  • Article
    Citation - WoS: 6
    Citation - Scopus: 6
    Photocatalytic Activity of Dye-Sensitized and Non-Sensitized Go-Tio2 Nanocomposites Under Simulated and Direct Sunlight
    (Wiley-Blackwell, 2022) İlhan, Hatice; Durmaz Çaycı, Gamze Belkis; Aksoy, Erkan; Diker, Halide; Varlıklı, Canan
    Graphene oxide (GO), amine-modified graphene oxide (mGO), and N-TiO2 composites were synthesized by low-temperature hydrothermal method and characterized by using X-ray diffraction, X-ray photoelectron spectroscopy, FTIR, and BET analysis techniques. The films of synthesized TiO2, mGO:TiO2, N-TiO2, GO:TiO2, GO:N-TiO2, and commercially available P25 were prepared by doctor blade method. These films and their perylene-3,4,9,10-tetracarboxy tetrabutylester (PTE)-sensitized forms were employed as photocatalysts for the photodegradation of rhodamine-B (RhB) under Xe lamp and direct sunlight irradiations. Independent from the irradiation source, the photocatalytic order of the non-sensitized films were GO:N-TiO2 > GO:TiO2 > N-TiO2 > mGO:TiO2 > TiO2 > P25, but seven and 15 folds of increments were detected under direct sunlight irradiation. PTE-sensitized catalyst films exhibited more than two folds of increase in the photocatalytic rate constants compared to their non-sensitized counterparts under Xe lamp irradiation. Under direct sunlight irradiation no matter which photocatalyst was used, the photocatalytic activity of these films was enhanced seven folds. Reusability tests revealed no significant changes in the photocatalytic rate constants obtained with both the non-sensitized and sensitized films.
  • 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.
  • Article
    Citation - WoS: 19
    Citation - Scopus: 20
    Controlling the Distribution of Oxygen Functionalities on Go and Utilization of Pedot:pss-Go Composite as Hole Injection Layer of a Solution Processed Blue Oled
    (Elsevier Ltd., 2017) Diker, Halide; Durmaz, Gamze Belkis; Bozkurt, Hakan; Yeşil, Fatih; Varlıklı, Canan
    Graphene oxide (GO) was synthesis by Tour method. Particle size distribution effects of raw graphite on the resulting structural, morphological, optical and electrical properties of GO samples and their poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) composites are studied for the graphite particle distributions of <150, 45–75 and 25–45 μm. It is determined that particle size of raw graphite have an impact on oxidation degree, the chemical nature of oxygen functional groups on GO and it also affects the lateral size of obtained GO. PEDOT:PSS-GO composites are utilized as hole injection layer (HIL) in a solution process blue organic light emitting diode. Presence of GO caused negative differential resistance (NDR) and NDR intensity was decreased with the decrease in lateral size of GO, increase in the graphite particle size and carboxyl% of obtained GO. All PEDOT:PSS-GO composite based devices presented better performance than the bare PEDOT:PSS based reference device. The maximum luminous and external quantum efficiency values of the device that contain HIL of PEDOT:PSS-GO(150) were more than 40% and 50% higher than that of the reference, respectively. Two folds of increase in these performance values were able to be reached with the concentration optimization of GO/150 in PEDOT:PSS.