Yazar "Tonga, Murat" seçeneğine göre listele

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    A narrow range multielectrochromism from 2,5-di-(2-thienyl)-1H-pyrrole polymer bearing pendant perylenediimide moiety
    (Elsevier Sci Ltd, 2015) Sefer, Emre; Bilgili, Hakan; Gultekin, Burak; Tonga, Murat; Koyuncu, Sermet
    A new 2,5-di-(2-thienyl)-1H-pyrrole (SNS) moiety containing perylenediimide (PDI) acceptor as pendant side chain has been synthesized for an electroactive monomer and then directly deposited onto ITO/glass surface via electrochemical polymerization process. The observed electronic interaction only at the excited state due to the presence of phenylene spacer between SNS-donor and PDI-acceptor moiety leads to efficient fluorescence quenching. This charge separation behavior was also proved by theoretical DFT calculations. Thin films of the polymer electropolymerized onto transparent electrode exhibited ambipolar multi-electrochromic behavior including purple, violet-red-khaki-blue colors in both anodic and cathodic regime only between -1.2 and 1.0 V. We further demonstrated that this polymer film has a high contrast ratio (Delta T = 45% at 900 nm), a faster response (0.5 s), high coloration efficiency (254 cm(2) C-1) and retained its performance by 92% even after 5000 cycles. (C) 2014 Elsevier Ltd. All rights reserved.
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    Öğe
    A Novel Near-IR Effective Pyrene-Based Donor-Acceptor Electrochrome
    (Wiley-V C H Verlag Gmbh, 2015) Sefer, Emre; Hacioglu, Serife O.; Tonga, Murat; Toppare, Levent; Cirpan, Ali; Koyuncu, Sermet
    In this work, a novel donor-acceptor electrochromic monomer (3HTP), containing a pyrene subunit connected to a quinoxaline acceptor bridge, is synthesized. The corresponding polymer, poly-(3HTP), is directly deposited onto an indium tin oxide (ITO)/glass surface via an electrochemical process. Atomic force microscopy (AFM) images reveal that the electrochemically deposited poly-(3HTP) has a smooth surface due to self-assembly of the planar pyrene subunit. Electrochemical and optical properties are investigated via cyclic voltammetry and UV-vis absorption measurements. The polymer film shows a multielectrochromic feature at both anodic and cathodic regimes. Poly-(3HTP) exhibits a strong near-infrared (NIR) absorption at the oxidized state with an optical contrast of 88% (at 1800 nm), a very fast response time of 0.5 s and fast switching times, and long-term stability. Density functional theory calculations reveal that the molecule has a high planarity, and the NIR absorption arises from a strong intramolecular charge transfer from the polymer backbone to the planar pyrene subunit.
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    Öğe
    Toward Purple-to-Green-to-Transmissive-to-Black Color Switching in Polymeric Electrochrome
    (Amer Chemical Soc, 2014) Karabiyik, Elif; Sefer, Emre; Koyuncu, Fatma Baycan; Tonga, Murat; Ozdemir, Eyup; Koyuncu, Sermet
    A novel 3,4-ethylenedioxythiophene (EDOT)-based donoracceptor electroactive monomer (HCQE) bearing carbazole subunit is synthesized, and then the corresponding polymer, poly(HCQE), is directly deposited onto ITO/glass surface via electrochemical process. Spectroelectrochemical studies demonstrate that poly(HCQE) is capable of showing both n- and p-doping processes. Hence, this low band polymer serves the multielectrochromic feature at three separate states (-0.4 to -2.0 V, -0.4 to 1.2 V, and 1.2 to 2.0 V) with a highly unique near colorless and colored states, fast switching times, redox switching stability, and exceptional transmittance change. To the best of our knowledge, this is the first report of a neutral state green multielectrochromic polymer exhibiting successive switching of colored-to-bleached-to-colored in three distinct regimes.