Photonics / Fotonik

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

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Access Right: Closed AccessAuthor: search.filters.author.Aksoy, Erkan

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  • 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: 16
    Citation - Scopus: 16
    Silylethynyl substitution for preventing aggregate formation in perylene diimides
    (American Chemical Society, 2021) Aksoy, Erkan; Danos, Andrew; Li, Chunyong; Monkman, Andrew P.; Varlıklı, Canan
    Ethynylene-bridged perylene diimides (PDIs) with different sized silane groups have been synthesized as a steric blocking group to prevent the formation of non-radiative trap sites, for example, strong H-aggregates and other dimers or excimers. Excited singlet-state exciton dynamics were investigated by time-resolved photoluminescence and ultrafast pump-probe transient absorption spectroscopy. The spectra of the excimer or dimer aggregates formed by the PDIs at high concentrations were also determined. Although the photophysical properties of the bare and shielded PDIs are identical at micromolar concentrations, more shielded PDI2 and PDI3 exhibited resistance to aggregation, retaining higher photoluminescence quantum yield even at 10 mM concentration and in neat films. The PDIs also exhibited high photostability (1 h of continuous excitation), as well as electrochemical stability (multiple cycles with cyclic voltammetry). Prevention of dimer/aggregate formation in this manner will extend the uses of PDIs to a variety of high concentration photonics and optoelectronic applications, such as organic light-emitting diodes, organic photovoltaics, and luminescent solar concentrators.