Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 6Citation - Scopus: 6Photocatalytic 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, CananGraphene 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: 19Citation - Scopus: 19Navigating Cie Space for Efficient Tadf Downconversion Woleds(Elsevier Ltd., 2020) Aksoy, Erkan; Danos, Andrew; Varlıklı, Canan; Monkman, Andrew P.High efficiency orange and green emitting perylene dyes have been synthesized and dispersed in an inert polymer host to form an optical downconversion layer. To avoid dye aggregation and allow controlled colour tuning, this layer was deposited in multiple low-concentration spin-coating steps, directly on top of a high performance blue thermally activated delayed fluorescence (TADF) organic light emitting diode (OLED). The orange downconversion layer partially absorbs the blue OLED emission, while emitting a complementary orange to give white light. However, as energy transfer between the TADF and perylene downconverter is based on emission and reabsorption, absorptive filtering of the blue OLED emission band necessitates the inclusion of an additional green-emitting perylene top-layer to achieve optimal white balance. The optimised white OLED fabricated in this way displayed excellent white colour balance (CIE x, y; 0.33, 0.33) with perfect stability, good colour rendering (CRI 80), and a high maximum efficiency (maximum EQE 17.2%) with minimal losses compared to the base blue OLED. This approach is widely applicable for generating white emission from any kind of blue OLED, and is compatible with a wide range of downconverting dyes and host materials.Conference Object Citation - WoS: 9Citation - Scopus: 11White Led Light Production Using Dibromoperylene Derivatives in Down Conversion of Energy(Canadian Science Publishing, 2018) Aksoy, Erkan; Demir, Nuriye; Varlıklı, CananPerylene derivatives of N,N′-bis(2,6-diisopropylphenyl)-1,6(7)-dibromoperylene-3,4,9,10-tetracarboxylic diimide (DBrPDI) and 1,7-dibromo perylene-3,4,9,10-tetracarboxylic acid butyl ester (DBrPTE) were synthesized, and their structural and optical characterizations were explored. Both DBrPDI and DBrPTE, which were utilized as wavelength converters on a GaN/InGaN based blue LED, were singlet sensitizers and had molar absorptivity constants around 104 Lmol-1cm-1. The blue LED that was used had Commission internationale de l'eclairage (CIE) coordinates of x, y = 0.13, 0.06; power and luminous efficiencies of 2.7 lm/W and 6.6 cd/A @5 mA, respectively. Because the fluorescence quantum yield of DBrPDI was much higher than that of DBrPTE, a meaningful white light efficiency was obtained with the diimide derivative. The use of DBrPDI resulted in white light with CIE coordinates of x, y = 0.34, 0.29 and luminous efficiency of 6.35 cd/A @5 mA, respectively. Using DBrPDI in a resin matrix resulted in more than three orders of magnitude increase in the luminous efficiency value (23.0 cd/A @5 mA) while the CIE coordinates remained the same. Whenever the applied current reached 20 mA, a CRI value of Ra = 90 was obtained.