Browsing by Author "Cihaner, Atilla"

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[1,2,5]thiadiazolo[3,4-G]quinoxaline Acceptor-Based Donor-Acceptor Polymers: Effect of Strength and Size of Donors on the Band Gap
(Wiley, 2017) Gokce, Gurcan; Karabay, Baris; Cihaner, Atilla; Ozkut, Merve Icli
Electrochromic polymers based on [1,2,5]thiadiazolo[3,4-g]quinoxaline acceptor and thiophene, 3,4-ethylenedioxythiophene and 3,3-didecyl-3,4-proylenedioxythiophene donors, namely poly(6,7-diphenyl-4,9-di(thiophen-2-yl)-[1,2,5]thiadiazolo[3,4-g]quinoxaline) (P1), poly(4-(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-9-(2,3-dihydrothieno[3,4-b][1,4]dioxin-7-yl)-6,7-diphenyl-[1,2,5]thiadiazolo[3,4-g]quinoxaline) (P2), and poly(4-(3,3-didecyl-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepin-6-yl)-9-(3,3-didecyl-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepin-8-yl)-6,7-diphenyl-[1,2,5]thiadiazolo[3,4-g]quinoxaline) (P3), respectively, were electrochemically and/or chemically synthesized and characterized. Electrochemical and optical properties of the polymers were then investigated. The results, which were obtained electrochemically and optically, indicate that the polymers bearing the same acceptor and different donor units have a band gap range of 0.59-1.24 eV depending on the strength and size of the donor units and band gap determination method. A significant finding in this study was the phenomenon that when the acceptor is physically huge, the general rule that a weak donor would have a high band gap whereas a strong donor would have low band gap can be broken due to the torsional angles/steric hindrances involved with physically large donor molecules. (c) 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 3483-3493
Acid/ Base Doped/ Dedoped Low Band Gap Polymer
(Amer Chemical Soc, 2016) Karabay, Baris; Gokce, Gurcan; Cihaner, Atilla; Icli Ozkut, Merve
Donor-Acceptor Polymer Electrochromes With Cyan Color: Effect of Alkyl Chain Length on Doping Processes
(Elsevier, 2012) Celikbilek, Ozden; Icli-Ozkut, Merve; Algi, Fatih; Onal, Ahmet M.; Cihaner, Atilla
A new series of donor-acceptor-donor (D-A-D) type compounds consisting of dialkyl substituted 3,4-propylenedioxythiophene and benzothiadiazole units were synthesized and polymerized chemically and electrochemically to investigate the effect of alkyl chain length on the doping process of the conjugated polymers. It was found that the alkyl chain length plays a key role on both doping processes and the solubility of the polymer. It is also noteworthy that this new series of D-A-D electrochromes transmits or reflects the cyan color of the Cyan-Magenta-Yellow (CMY) color space in the neutral state which can be switched to transmissive grey when oxidized. (C) 2011 Elsevier B.V. All rights reserved.
Electrochemical and Optical Characterization of a Multielectrochromic Copolymer Based on 3,4-Ethylenedioxythiophene and Functionalized Dithienylpyrrole Derivative
(Pergamon-elsevier Science Ltd, 2019) Tutuncu, Esra; Ozkut, Merve Icli; Balci, Burcu; Berk, Hasan; Cihaner, Atilla
A novel conjugated copolymer, namely poly(3,4-ethylenedioxythiophene-co-1-(3,5-bis(trifluoromethyl)phenyl)-2,5-di(thiophen-2-yl)-1H-pyrrole) (P(EDOT-co-1)) was synthesized via electropolymerization method from a mixture of 3,4-ethylenedioxythiophene and 1-(3,5-bis(trifluoromethyl)phenyl)-2,5-di(thiophen-2-yl)-1H-pyrrole comonomers. The corresponding copolymer has an optical band gap of 1.7 eV and 41% optical contrast at 525 nm with a coloration efficiency of 258 cm(2)/C and 1.4 s switching time. The copolymer has a multi-electrochromic behavior: It has dark purple, purple, gray, green and cyan colors at different oxidation states. Electrochemical stability of P(EDOT-co-1) copolymer was also investigated and it was observed that the copolymer retained 86% of its stability under ambient conditions in the presence of oxygen (without purging the electrolyte solution with any inert gas) according to the current density and 83% according to the deposited charge even after 1000 redox cycles.
An Electrochromic Polymer Based on Cyclopenta[2,1-B;3,4 Effect of a Single Atom Alteration on the Electrochemical and Optical Properties of the Polymer Backbone
(Elsevier Science Sa, 2020) Tutuncu, Esra; Varlik, Bengisu; Kesimal, Busra; Cihaner, Atilla; Ozkut, Merve Icli
An electrochromic polymer, namely "poly(2,6-(3,3-didecyl-3,4-dihydro-2H-thieno [3,4-b] [1,4]dioxepin-6-yl)-4,4-dioctyl-4H-cyclopenta[2,1-b;3,4-b']dithiophene)" (P1), was electrochemically synthesized successfully, and its electrochemical and optical properties were investigated. The band gap of the polymer P1 was calculated as 1.77 eV with -5.45 eV Highest Occupied Molecular Orbital (HOMO) and -3.68 eV Lowest Unoccupied Molecular Orbital (LUMO) energy levels. The polymer P1 is bluish purple when neutralized and highly transparent greenish purple when oxidized. This color change was observed around 1.4 s between its redox states and optical contrast ratio was found to be as 49 % and 53 % with 234 cm(2)/C and 239 cm(2)/C coloration efficiencies at 590 nm and 634 nm, respectively. Moreover, the properties of this polymer were compared to its analogues and also during this comparison the effect of alteration of a single atom in the pendant unit was tried to be understood.
From Narrow To Narrower: a Very Low Band Gap [1,2,5]thiadiazolo[3,4-G]quinoxaline Donor-Acceptor Type Electrochromic Polymer
(Electrochemical Soc inc, 2017) Gokce, Gurcan; Karabay, Baris; Cihaner, Atilla; Ozkut, Merve Icli
The development of low bandgap polymers (or zero bandgap polymers) is still one of the main goals of scientists and many viable paths have been formulated in order to accomplish this. In this study, a donor-acceptor-donor type electrochromic polymer based on [1,2,5]thiadiazolo[3,4-g]quinoxaline acceptor and selenophene donor units with extremely low bandgap (ranging from 0.21 to 0.60 eV depending on bandgap determination method) is synthesized and characterized electrochemically, optically and colorimetrically. Electrochemical and optical studies showed that the polymer film was susceptible to both n- and p-type doping and has a mustard color in its neutral state, and upon oxidation its color changed to brown, and upon reduction the color is light purple. (C) 2017 The Electrochemical Society. All rights reserved.
Furan and Benzochalcogenodiazole Based Multichromic Polymers Via a Donor-Acceptor Approach
(Royal Soc Chemistry, 2013) Icli-Ozkut, Merve; Ipek, Halil; Karabay, Baris; Cihaner, Atilla; Onal, Ahmet M.
Two new furan and benzochalcogenodiazole based monomers, namely 4,7-di(furan-2-yl) benzo[c][1,2,5]-selenadiazole (FSeF) and 4,7-di(furan-2-yl) benzo[c][1,2,5]thiadiazole (FSF), were designed and synthesized via a donor-acceptor-donor approach. The monomers were electrochemically polymerized via potentiodynamic or potentiostatic methods. The monomers and their polymers exhibited lower oxidation potentials (1.16 V and 1.06 V for monomers; 0.93 V and 0.80 V for polymers vs. Ag/AgCl) and red shifts of the whole dual-band absorption spectra upon moving from S to Se. Intramolecular charge transfer properties of the monomers and the polymers were demonstrated by using electroanalytical and optical methods. Also, the polymers PFSeF and PFSF were multicolored at different redox states and have low band gaps of 1.43 eV and 1.61 eV, respectively.
A Low Band Gap Polymer Based on Selenophene and Benzobis (Thiadiazole)
(Pergamon-elsevier Science Ltd, 2017) Abdulrazzaq, Mohammed; Ozkut, Merve Icli; Gokce, Gurcan; Ertan, Salih; Tutuncu, Esra; Cihaner, Atilla
A new derivative of benzobis(thiadiazole) based donor-acceptor-donor type monomers, namely 4,7-di (selenophen-2-yl)benzo[1,2-c;4,5-c']bis[1,2,5]thiadiazole (SeBTSe), was synthesized and its polymerization was carried out successfully via electrochemical polymerization in an electrolyte solution of 0.1 M tetrabutylammonium hexafluorophosphate dissolved in dichloromethane. The monomer SeBTSe is a deep red chromophore and it has four redox states: one oxidation, one neutral and two reduction states. The electrochemical behaviour of the corresponding polymer called PSeBTSe was studied by cyclic and differential pulse voltammetry. There is a good agreement between electrochemical (0.62-0.66 eV) and optical (0.63 eV) bandgaps of the polymer. Like the monomer, the ambipolar polymer has four redox states and electrochromic properties: gray beige at neutral state, smoky azurite at oxidized state, beige at first reduced state and dark beige at second reduced state. (C) 2017 Elsevier Ltd. All rights reserved.
Members of Cmy Color Space: Cyan and Magenta Colored Polymers Based on Oxadiazole Acceptor Unit
(Amer Chemical Soc, 2012) Ozkut, Merve Icli; Algi, Melek Pamuk; Oztas, Zahide; Algi, Fatih; Onal, Ahmet M.; Cihaner, Atilla
In this study, three novel oxadiazole-based polymers were synthesized and their electrochemical and optical properties were investigated. The polymers were found to have both p- and n-type doping properties accompanied by electrochromic response. Two polymer films exhibit cyan and magenta colors, which constitute two legs of CMY color spaces, in their neutral states and they are soluble in common-organic solvents. According to the color mixing theory, all colors in the visible spectrum including black color can be obtained by using these polymers with a yellow colored electrochromic polymer. Among these polymers, the polymer bearing propyledioxythiophene donor units has some superior properties like high stability (it retains 94% of its electroactivity after 2000 cycles), solubility, and high coloration efficiency (230 cm(2)/C), whereas as expected ethylenedioxythiophene containing one has the lowest band gap as 1.08 eV.
Substituent and Heteroatom Effects on the Electrochromic Properties of Similar Systems
(Wiley-blackwell, 2012) Icli-Ozkut, Merve; Mersini, Jetmire; Onal, Ahmet M.; Cihaner, Atilla
Electrochromic polymers called poly(3,4-dihydro-3,3-bis ((naphthalen-1-yl)methyl)-2H-thieno[3,4-b][1,4]dioxepine) (PProDOT-Np-2), poly(3,3-dibenzyl-3,4-dihydro-2H-selenopheno[3,4-b][1,4]dioxepine), and poly(3,3-dibenzyl-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepine) were synthesized electrochemically and the effect of substituents and heteroatoms on the electrochromic properties were investigated for the similar systems. All polymers show electrochromism from a colored state when neutralized to transmissive when oxidized. Although, increasing bulky size (PProDOT-Np-2) causes lower coloration efficiency (CE) as well as lower optical contrast, the replacement of S atom by Se atom resulted in a lower band gap polymer with a higher CE than its thiophene analog. (c) 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 50: 615- 621, 2012
Synthesis and Electropolymerization of a Donor-Acceptor Trimeric Monomer Containing 3,4-Propylenedioxythiophene and Dithienosilole Units
(Pergamon-elsevier Science Ltd, 2019) Tutuncu, Esra; Cihaner, Atilla; Ozkut, Merve Icli
A new dithienosilole and 3,4-propylenedioxythiophene based monomer, namely 2,6-bis(3,3-di-decyl-3,4-dihydro-2H-thieno[3,4-b] [1,4]dioxepin-6-yl)-4,4-dioctyl-4H-silolo[3,2-b:4,5-b']dithiophene, was synthesized via palladium catalyzed Stille Coupling Reaction and then polymerized electrochemically in an electrolyte solution of 0.1 M lithium perchlorate dissolved in a mixture of dichloromethane and acetonitrile (1:1, v:v). Due to the presence of long alkyl chains on donor and acceptor units, the corresponding polymer was soluble in common organic solvents like tetrahydrofuran, toluene, hexane and dichloromethane. Polymer has both fluorescent and electrochromic properties. Fluorescent polymer emits a reddish pink at 585 nm when excited at 480 nm and the quantum yield was found as 14%. On the other hand, the electrochromic polymer film changed its color from purple to transmissive cyan with 0.65 s switching time upon moving from neutral state to oxidized state and the film has a coloration efficiency of 501 cm(2)/C as well as 60% optical contrast. The optical band gap of the polymer was also calculated as 1.83 eV with a maximum wavelength at 577 nm.