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Article Citation - WoS: 14Citation - Scopus: 12Electrochemical Synthesis of New Conjugated Polymers Based on Carbazole and Furan Units(Elsevier Science Sa, 2015) Oguzturk, H. Esra; Tirkes, Seha; Onal, Ahmet M.In this study, synthesis of four new monomers; 3,6-di(2-furyl)-9H-carbazole (M1), 3,6-di(2-furyl)-9-ethyl-carbazole (M2), 2,7-di(2-furyl)-9-H-carbazole (M3), 2,7-di(2-furyl)-9-(tridecan-7-yl)-9H-carbazole (M4), was achieved via Stifle cross-coupling reaction. The monomers were electrochemically polymerized, via repetitive cycling in acetonitrile-tetrabutylammonium hexafluorophosphate electrolytic medium. Optical and electrochemical properties of the monomers and their corresponding polymers were investigated and it was found that optical properties show slight variations depending on the connectivity between the carbazole and furan moieties. However, all the monomers synthesized in this work exhibited an irreversible oxidation peak at around 1.0 V. Electrochemically obtained polymer films, on the other hand, exhibited quasi-reversible redox behavior due to doping/dedoping of the polymers which was accompanied by a reversible electrochromic behavior. Their band gap values (E-g) were elucidated utilizing spectroelectrochemical data and it was found that polymers obtained from 2,7-substituted carbazole derivatives have slightly lower band gap values. Furthermore, scanning electron micrographs were used for morphological examinations. (C) 2015 Elsevier B.V. All rights reserved.Article Citation - WoS: 24Citation - Scopus: 25A Novel Conducting Polymer Based on Terthienyl System Bearing Strong Electron-Withdrawing Substituents and Its Electrochromic Device Application(Elsevier Science Sa, 2008) Asil, Demet; Cihaner, Atilla; Algi, Fatih; Onal, Ahmet M.A novel conducting polymer bearing strong electron-withdrawing substituents (EWS) directly attached to the 3,4-positions of the thiophene ring was synthesized by electrochemical polymerization of diethyl 2,5-di(thiophen-2-yl)thiophene-3,4-dicarboxylate (SSS-Diester). The polymer (PSSS-Diester) was characterized by cyclic voltammetry, FT-IR and UV-vis spectroscopy. The polymer has a reversible redox process and demonstrates a stable electrochromic behavior: reddish orange in the neutral state, brown in the intermediate state and green in the oxidized state. Optical density and response time of the dual-type electrochromic device based on PSSS-Diester were found to be 0.23 and 0.6 s at 623 nm, respectively. It is also noteworthy that the device shows good environmental and redox stability (i.e. 94% of the optical activity of the device retained after 500th switch). (c) 2008 Elsevier B.V. All rights reserved.Article Citation - WoS: 26Citation - Scopus: 30Electrochemical Polymerization of 9-Fluorenecarboxylic Acid and Its Electrochromic Device Application(Elsevier Science Sa, 2008) Bezgin, Buket; Cihaner, Atilla; Onal, Ahmet M.Poly(9-fluorenecarboxylic acid) (PFCA) was synthesized by electrochemical oxidation of 9-fluorenecarboxylic acid (FCA) using a mixture of nitromethane and boron trifluoride diethyl etherate as the solvent and tetrabutylammonium tetrafluoroborate as the supporting electrolyte. An insoluble and conducting brownish-orange film was deposited on the electrode surface, both during repetitive cycling and constant potential electrolysis at 1.15 V. Characterization of the polymer film has been carried out using Fourier Transform Infrared spectroscopy technique and thermal behavior was studied via thermal gravimetric analysis. Structural analysis showed that the polymerization of FCA occurred at 2,7-position. Spectroelectrochemical behavior of the polymer film on indium tin oxide working electrode was studied by recording the electronic absorption spectra, in-situ, in monomer-free electrolytic solution at different potentials and it is found that the PFCA film can be reversibly cycled between 0.0 V and 1.2 V Furthermore, a dual type electrochromic device based on PFCA was constructed and its spectroelectrochemical properties were investigated. The electrochromic device exhibits color change from transparent to dark blue with a good open circuit memory. (c) 2008 Elsevier B.V. All rights reserved.Article Citation - WoS: 16Citation - Scopus: 16Synthesis and electropolymerization of thieno[3,4-c]pyrrole-4,6-dione based donor-acceptor-donor type monomers(Elsevier Science Sa, 2020) Cakal, Deniz; Cihaner, Atilla; Onal, Ahmet M.Two monomers containing thieno [3,4-c]pyrrole-4,6-dione (TP) acceptor units, namely 5-(2-ethylhexyl)-1,3-di (furan2-yl)-4H-thieno [3,4-c]pyrrole-4,6(5H)-dione (FTPF) and 5-(2-ethylhexyl)-1,3-di (selenophen-2-yl)-4H-thieno[3,4-c] pyrrole-4,6(5H)-dione (STPS), were synthesized via donor-acceptor-donor approach. Under the same template structure, the effect of heteroatom of the donor unit on redox and optical properties of the monomers and their corresponding polymers obtained via electrochemical method (PFTPF and PSTPS) were investigated. The results were also compared to their thiophene analogues 5-(2- ethylhexyl)-1,3-di (thiophen-2-yl)-4H-thieno[3,4-c]pyrrole-4,6(5H)-dione (TTPT) as the monomer and PTTPT as the polymer. Three monomers exhibited dual absorption bands one at high energy region due to the pi-pi* transition and the other one at low energy region which might be attributed to intramolecular charge transfer (ICT). An increase in ICT and a decrease both in the band gap and quantum yield was observed with increasing size of the heteroatomof the donor units. The oxidation potentials of the monomers and that of their corresponding polymer films were found to follow the order of decreasing aromatization energy from thiophene to furan (i.e thiophene > selenophene > furan). Also, heavy-atom substitution (PSTPS) effect showed itself by narrowing the optical band gap of the neutral state electrochromic polymer films: 1.90 eV for PFTPF, 1.82 eV for PTTPT and 1.76 eV for PSTPS.Article Citation - WoS: 25Citation - Scopus: 26Electrochemical Synthesis of Poly(3-Bromo and Its Device Application(Elsevier Science Sa, 2007) Cihaner, Atilla; Onal, Ahmet M.A functionalized thiophene containing both an electron withdrawing and an electron donating group, 3-bromo-4-methoxythiophene (BrMeOTh) was succesfully polymerized in acetonitrile containing 0.1 M tetrabutylammonium tetrafluoroborate (TBABF4) electrolyte via electrochemical oxidation of the corresponding monomer. BrMeOTh exhibits a lower oxidation potential (1.68 V vs Ag/AgCl) than thiophene (2.05 V vs Ag/AgCl). Spectroelectrochemical properties of poly(3-bromo-4-methoxythiophene) (PBrMeOTh) was investigated in situ recording the electronic absorption spectra of the polymer film coated on indium-tin oxide (ITO) at various potentials. The maximum transmittance difference between the oxidized and reduced states was measured as 39.2% and the time required to attain 90% of the total transmittance difference was found to be 1.2 s. Both cyclic voltammetric and spectroelectrochemical studies showed that the polymer exhibit a lower oxidation potential, a relatively narrow band gap, a stable conducting state and a higher degree of electrochemical reversibility. It is also found that, as synthesized PBrMeOTh films possess a linear structure along the polymer backbone. Moreover, dual type electrochromic device of PBrMeOTh with poly(3,4-diethylenedioxythiohene) (PEDOT) was constructed and its spectroelectrochemical, electrochromic switching and open circuit stability were investigated. Dual electrochromic device showed a good optical contrast and distinctive color changes with the ability of good switching times (1.1 s) under atmospheric pressure. (c) 2006 Elsevier B.V. All rights reserved.Article Citation - WoS: 2Citation - Scopus: 2D-A Type Conjugated Polymers in Dual Electrochromic Devices Tuning From Green To Blue Colors(Elsevier Science Sa, 2023) Ozkut, Merve Icli; Onal, Ahmet M.; Cihaner, AtillaIn this study, the electrochemical and electro-optical properties of four different dual electrochromic devices were unraveled. In all devices, soluble donor-acceptor-donor (D-A-D) type conjugated electrochromic polymers based on didecyl substituted 3,4-propylenedioxythiophene and heterodiazole analogs were used, and they were coated on ITO electrochemically for the construction of the electrochromic devices. Because all D-A-D polymers and PEDOT are colorful in their neutral states and colorless in their oxidized states, it is possible to observe one -to-one colors of pure two polymers in their electrochromic devices rather than a mixture of colors. It was observed that devices changed their colors from the tunes of green to blue under applied external voltage. Switching times, coloration efficiencies and stabilities of the electrochromic devices were calculated as ranging from 1.0 to 6.0 s, 133-544 cm2/C and 54-91 %, respectively, after 5000 cycles. The P(PSeP-C10)-P(PNP-C10) device showed the highest coloration efficiency (544 cm2/C) as well as the best optical and electrochemical stabilities among the electrochromic devices after 5000 cycles (91 % and 92 %, respectively).
