Browsing by Author "Akbayrak, Merve"

Filter results by typing the first few letters
Now showing 1 - 2 of 2
  • No Thumbnail Available
    Item
    Effect of Thiophene Units on the Properties of Donor Acceptor Type Monomers and Polymers Bearing Thiophene-Benzothiadiazole- Scaffolds
    (2016) Cansu-Ergun, Emine G.; Akbayrak, Merve; Akdag, Akin; Onal, Ahmet M.; 0000-0002-0058-905X; 0000-0003-3283-2146; 0000-0002-3941-4345; 0000-0003-0644-7180; 0000-0003-3283-2146; A-7063-2010; N-5377-2016; I-7385-2017; AAS-5007-2020; HCG-9312-2022
    In this article, a series of benzothiadiazole and thiophene based donor-acceptor-donor (D-A-D) type monomers and their corresponding polymers, via potential cycling, were reported. Effect of increasing number of thiophene units in the electron rich donor segment on the electrochemical and photophysical properties of the monomers and their corresponding polymers were reported. Electrochemical and optical properties were determined by cyclic voltammetry, UV-Vis and emission spectrometry. Monomers with one, two and three thiophene units on both sides of benzothiadiazole (TBz, T2Bz, T3Bz) exhibited better conjugation and intramolecular charge transfer with increasing thiophene length. On the other hand, the inverse trend was observed in their corresponding polymers (PTBz, PT2Bz, PT3Bz). Blue shift of the absorption edge in polymer thin films resulted in wider optical bandgap (from 1.70 eV to 1.99 eV) with increasing donor/ acceptor ratio on the polymer chain. Based on our experimental and theoretical studies, molecular weight or branching on these polymers together with degree of stiffness and conformational degree of freedom might be an explanation for these controversial observations. (C) 2016 The Electrochemical Society. All rights reserved.
  • No Thumbnail Available
    Item
    Hunting Black Color via Absorption Engineering: EDOT and Thiophene-Benzothiadiazole Based Black-To-Transmissive Copolymer and Its Electrochromic Device Application
    (2022) Ergun, Emine Gul Cansu; Akbayrak, Merve
    Neutral state black electrochromics are prominent materials for smart applications such as displays, car rear views, e-papers etc. This work has aimed to obtain a neutral state black electrochromic polymer, by tuning the optical absorbance to whole visible region. Two monomers, 4,7-bis(5-(thiophen-2-yl)thiophen-2-yl)benzo[c] [1,2,5]thiadiazole (TTBTT) and 3,4-ethylenedioxythiophene (EDOT), were selected according to their complementary absorbance behaviors, and they were combined in the same polymer backbone via electrochemical copolymerization technique. Copolymerization was performed using three different monomer feed ratios (2:1, 1:1 and 1:2 (EDOT: TTBTT)). Even though all the copolymers exhibited dark to transmissive colors from neutral to oxidized states, changing the monomer feed resulted in different optical contrast, switching response and color hues for each copolymer. The higher optical contrast (from 17% to 27%) and faster switching response (from 3.6 s to 1.8 s) were recorded as EDOT unit increase in the copolymer chain. A dual type electrochromic device was also constructed using the copolymer and the resulting device was successfully changed its color from black to transmissive.