Photonics / Fotonik
Permanent URI for this collectionhttps://hdl.handle.net/11147/2590
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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: 16Citation - Scopus: 16Silylethynyl substitution for preventing aggregate formation in perylene diimides(American Chemical Society, 2021) Aksoy, Erkan; Danos, Andrew; Li, Chunyong; Monkman, Andrew P.; Varlıklı, CananEthynylene-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.Article Citation - WoS: 2Citation - Scopus: 31-Octanol Is a Functional Impurity Modifying Particle Size and Photophysical Properties of Colloidal Zncdsse/Zns Nanocrystals(American Chemical Society, 2021) Sevim Ünlütürk, Seçil; Çağır, Ali; Varlıklı, Canan; Özçelik, SerdarImpurities in trioctylphophine (TOP) strongly affect nanocrystal synthesis. 1-Octanol among other contaminants in TOP is identified for the first time as a functional impurity by H-1 NMR. The deliberate addition of 1-octanol into trioctylphosphine reduced particle size and modified photophysical properties of ZnCdSSe/ZnS colloidal nanocrystals. NMR analysis furthermore revealed that 1-octanol is bonded to the nanocrystal surfaces. The ratio of integrals for the O-CH2 protons of 1-octanol, which is the lowest compared to the other ligands, suggests that 1-octanol plays a critical role to tune the particle size of nanocrystals. The increased amount of 1-octanol added into TOP reduces the particle size from 9.8 to 7.2 nm, causing a progressive blue shift in the UV-vis and PL spectra but leaving the alloy composition unaffected. The rate of nonradiative processes is enhanced with the amount of 1-octanol added into TOP, correlating with higher dislocation density observed in the nanocrystals. As a conclusion, 1-octanol is proposed as a functional impurity that varies particle size and nonradiative photophysical processes in the ZnCdSSe/ZnS colloidal nanocrystals.Article Citation - WoS: 5Citation - Scopus: 6Contribution of O-2 Plasma Treatment and Amine Modified Gos on Film Properties of Conductive Pedot:pss: Application in Indium Tin Oxide Free Solution Processed Blue Oled(Elsevier, 2019) Diker, Halide; Yeşil, Fatih; Varlıklı, CananPrimary (n-propyl amine, n-PRYLA), secondary (dipropyl amine, DPRYLA) and alcohol (propanol amine, PRPOHA) amine derivatives were used as amine sources in graphene oxide (GO) modification and obtained samples were named as nPRYLA-GO, DPRYLA-GO and PRPOHA-GO, respectively. Modified graphene oxide (mGO) derivatives were doped in poly (3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PH1000) and O-2 plasma treatment (70W, 3 min) was applied on the spin casted films. PH1000:mGO films presented high optical transparency values (> 90%) and low resistivity (177-183 Q/sq). The roughness values were increased especially when the hydrophobic alkyl chain containing DPRYLA-GO and nPRYLA-GO were doped in PH1000. Prepared films were utilized as anode in solution processed blue organic light emitting diode. PH1000:PRPOHA-GO anode presented more than 30 nm of decrement in full with at half maximum and 1.6, 1.5 and 1.9 fold enhancements in current, power and external quantum efficiency values, compared to those of ITO anode, respectively.