Chemistry / Kimya

Permanent URI for this collectionhttps://hdl.handle.net/11147/4072

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Access Right: Open AccessAuthor: search.filters.author.Varlıklı, Canan

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  • Article
    Citation - WoS: 7
    Citation - Scopus: 7
    An Ultraviolet Photodetector With an Active Layer Composed of Solution Processed Polyfluorene:zn0.71cd0.29s Hybrid Nanomaterials
    (Elsevier Ltd., 2014) Sevim, Seçil; Memişoğlu, Görkem; Özçelik, Serdar; Doğan, Leyla Eral; Taşçıoğlu, Didem; Varlıklı, Canan; 04.01. Department of Chemistry; 04.04. Department of Photonics; 04. Faculty of Science; 01. Izmir Institute of Technology
    An ultraviolet photodetector with an active layer of solution processed polymer:quantum dot hybrid is introduced. Poly[9,9-di-(2-ethylhexyl)-fluorenyl- 2,7-diyl] represents the polymer and Zn0.71Cd0.29S is the quantum dot used for the device. Photophysical studies showed that an electron transfer from the polymer to the ternary quantum dot is thermodynamically favored. Quenching experiments performed between the polymer and quantum dot indicates the formation of a non-fluorescent complex with an association constant of 4.6 × 104 M-1. The device structure of ITO/PEDOT:PSS/ADS231BE: 50 wt% Zn0.71Cd0.29S/Al yielded a photoresponsivity value of 324 mA/W at -4 V under 1 mW/cm2 illumination at 365 nm at room temperature and this value is further increased to 380 mA/W as a result of annealing at 75 °C.
  • Article
    Citation - WoS: 32
    Citation - Scopus: 32
    Optical and Electrochemical Properties of Polyether Derivatives of Perylenediimides Adsorbed on Nanocrystalline Metal Oxide Films
    (Elsevier Ltd., 2013) Kuş, Mahmut; Varlıklı, Canan; Özçelik, Serdar; Varlıklı, Canan; Demiç, Şerafettin; Özçelik, Serdar; İçli, Sıddık; 04.01. Department of Chemistry; 04.04. Department of Photonics; 04. Faculty of Science; 01. Izmir Institute of Technology
    We report optical and electrochemical properties of polyether derivatives of perylenediimides (PDIs) thin films formed in various materials (semiconductor, insulator, amorphous and self-assembly). Perylenediimides adsorbed on nanocrystalline TiO2(NT) nanocrystalline alumina (NA), amorphous silicon (PS) and neat self-assemblied (SA) films were prepared and characterized based on spectroscopic, electrochemical, spectro-electrochemical techniques. The absorption and fluorescence spectra of PDIs in chloroform exhibit vibronic features. The fluorescence quantum yields (Uf) of PDIs with end amino substituents in chloroform solutions are over 0.95, while the quantum yield of triethoxyphenyl substituted PDIUfvalue is 0.024 in solution. Optical spectroscopy proves that PDIs in metal oxide thin films form aggregated type complexes. An electrochromism, a color change from red to blue/violet, is observed on metal oxide films, that indicates existence of mono and dianion forms of PDIs. Reversibility of electrochemical reductions in NT film depends on the scanning rate. However, electrochromism in NA films is stable and reversibility is independent from scanning rate. Stable mono and diaionic species are formed on NA films. SA films show broad absorption peaks during the voltammetric scan. On the other hand, the first reduction onset potentials of PDIs are almost equal to the onset potential of capacitive current of TiO2which lead to low efficiency in dye-sensitized solar cells.
  • Article
    Citation - WoS: 8
    Citation - Scopus: 8
    Highly Efficient Orange–red Electroluminescence From a Single Layer Meh-Ppv Hybrid Pled
    (Elsevier Ltd., 2012) Saygılı, Gamze; Ünal, Gülçin; Varlıklı, Canan; Özçelik, Serdar; 04.01. Department of Chemistry; 04.04. Department of Photonics; 04. Faculty of Science; 01. Izmir Institute of Technology
    In this study, poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] end capped with polyhedral oligomeric silsesquioxanes (MEH-PPV-POSS): cadmium sulfide selenide quantum dots (CdS0.75Se0.25 QDs) nanocomposites based OLEDs were fabricated. By the addition of CdS0.75Se0.25QDs into the polymer active layer, a considerable enhancement was observed in terms of hole and electron injection in devices. Additionally, the presence of QDs reduced the interchain interaction of polymer that resulted in narrower electroluminescence (EL) spectrum. The device structure of ITO/PEDOT: PSS/MEH-PPV-POSS: 25 wt% CdS0.75Se0.25/Ca (40 nm)/Al demonstrated the best performance with a brightness of 8672 cd/m 2 at 10 V, current efficiency of 2.5 cd/A at 8 V, and an EQE of 0.55% at 150 mA/cm2 .