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Öğe A New Donor-Acceptor Double-Cable Carbazole Polymer with Perylene Bisimide Pendant Group: Synthesis, Electrochemical, and Photovoltaic Properties(John Wiley & Sons Inc, 2009) Koyuncu, Sermet; Zafer, Ceylan; Koyuncu, Fatma Baycan; Aydin, Banu; Can, Mustafa; Sefer, Emre; Ozdemir, EyupWe report here electrochemical synthesis of novel soluble donor-acceptor (D-A) polymer with suitably functionalized perylenetetracarboxylic diimide dye derivative covalently linked to carbazole moiety (Cbz-PDI). The band gap, E, was measured using UV-Vis spectroscopy and compared with that obtained by cyclic voltammetry (CV). Efficient intramolecular electron transfer from carbazole-donor to perynediimide-acceptor leads to remarkable fluorescence quenching of the perylene core. Furthermore, spectroelectrochemical property and surface morphology of the polymer film were investigated. Characteristic monoanion and dianion radical bands on the UV-Vis absorption spectra attributed to the electrochemical reduction of the neutral polymer were observed. During the reduction process, red color of the film turned into blue and violet, respectively. Finally, the photovoltaic performance of the D-A double-cable polymer was checked and nearly 0.1% electrical conversion efficiency is obtained under simulated AM 1.5 solar light with 100 mW/cm(2) radiation power. (C) 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6280-6291, 2009Öğe Anticancer activity of Turkish marine extracts: a purple sponge extract induces apoptosis with multitarget kinase inhibition activity(Springer, 2020) Ciftci, Halil, I; Can, Mustafa; Ellakwa, Doha E.; Suner, Salih C.; Ibrahim, Mohamed A.; Oral, Ayhan; Sekeroglu, NazimMarine natural products have drawn a great deal of attention as a vital source of new drugs for the last five decades. However, marine organisms in the seas surrounding Turkey (the Black Sea, the Aegean Sea and the Mediterranean Sea) haven't been yet extensively explored. In the present study, three marine organisms (Dysidea avara, Microcosmus sabatieri and Echinaster sepositus) were sampled from the Dardanelles (Turkish Straits System, Western Turkey) by scientific divers, transferred to the laboratory and then were extracted with 70% ethanol. The extracts were tested for their cytotoxic effect against K562, KMS-12PE, A549, and A375 cancer cell lines. The sponge extract elicited the most promising cytotoxic activity, thus it was further evaluated against H929, MCF-7, HeLa, and HCT116 cancer cells. Most of the designated cells showed a considerable sensitivity for the sponge extract particularly H929, K562, KMS-12PE and HeLa cells with IC50 less than 10 mu g/mL. On the contrary, the other two extracts exhibited no cytotoxic activity on all cells at 100 mu g/mL concentration. The sponge extract was tested for its capacity to induce apoptosis in cancer cells and to inhibit a panel of tyrosine kinases showing remarkable results. The outcome of this study represents a platform for discovery of new chemotherapeutic agents of marine natural origin.Öğe Dopant Free Donor-Acceptor Type Polymer Hole Transport Materials for Efficient and Stable Perovskite Solar Cells(Amer Chemical Soc, 2024) Akin Kara, Duygu; Turgut, Sevdiye Basak; Cirak, Dilek; Karaman, Merve; Can, Mustafa; Koyuncu, Sermet; Gultekin, BurakA new donor-acceptor type polymers containing benzothiadiazole (HB1) and benzoselenidiazole (HB2) as acceptor units were prepared or use as hole transport layers in perovskite solar cells (PSCs). It was observed that the electrochemical HOMO-LUMO band gap narrowed from 2.74 to 1.88 depending on the variation in the acceptor unit. In addition, the charge-transfer band at 580 nm undergoes a 30 nm red-shift and broadens to the near-infrared region. HB1 and HB2 were introduced as dopant-free HTMs to replace the commonly used 2,2 ',7,7 '-tetrakis[N,N-di(4-methoxyphenyl)amino]-9-9 '-spirobifluorene (spiro-OMeTAD) in planar heterojunction n-i-p type of PSCs. Compared with HB2, HB1 exhibited better film morphology and mobility, resulting in improved charge-carrier extraction and transport. Dopant-free HB1 devices fabricated using the Cs0.05FA0.79MA0.16-Pb (IxBr1-x)3 triple cation perovskite displayed a champion power conversion efficiency of 11.69% under one sun illumination (100 mW cm(-2)) which is higher than the efficiency of HB2-based devices. The inflated performance was attributed to the reduced charge recombination and improved conductivity. In addition, these new HTMs exhibited higher hydrophobicity and thermal stability than their doped spiro-OMeTAD counterpart, making it possible to achieve good stability.Öğe Effect of a pi-bridging unit in triphenylamine-benzothiadiazole based donor acceptor chromophores for dye-sensitized solar cells(Pergamon-Elsevier Science Ltd, 2014) Yigit, Mesude Zeliha; Bilgili, Hakan; Sefer, Emre; Demic, Serafettin; Zafer, Ceylan; Can, Mustafa; Koyuncu, SermetTwo new metal free sensitizers based on triphenylamine-benzothiadiazole were synthesized and used in dye sensitized solar cells (DSSCs). Electrochemical and optical properties of the dyes were studied by cyclic voltammetry, UV-vis absorption and fluorescence spectroscopy. A red shift was observed by the attachment of a thiophene (MZ-259) instead of a phenylene (MZ-255) bridge. The reverse effect was observed in the electrochemical properties because of the more electron-donating thiophene incorporated into the cyanoacrylic acid as an anchoring-acceptor unit in this system resulted in a higher LUMO level. The charge distribution of the dyes was also proved by DFT calculations using the Spartan10 program with the parameters of B3LYP and 6-31G** basis set. Finally the photovoltaic performances were investigated under standard AM 1.5 illumination with a power of 100 mW/cm(2) using an ionic liquid based electrolyte. The power conversion efficiencies, eta, were increased from 3.16% to 3.81% by using thiophene instead of phenylene as a pi-bridge unit. (C) 2014 Elsevier Ltd. All rights reserved.Öğe Effect of the planar center moiety for a donor-acceptor polymeric electrochrome(Elsevier Sci Ltd, 2017) Doyranli, Ceylan; Colak, Betul; Lacinel, Gozde; Can, Mustafa; Koyuncu, Fatma Baycan; Koyuncu, SermetIn this work, phenanthrene centered donor-acceptor monomer; 5,10-bis(4-hexyl-2-thienyl)phenantro [9,10-c][1,2,5]thiodiazole; MES16 was synthesized and then its electrochromic application of corresponding polymer was carried out. 4,7-di(thiophen-2-yl)-2,1,3-benzothiadiazole (TST) was also synthesized as a standard molecule to determine the effect of the planar phenanthrene center on electrochromic performance. Electrochemical properties were elucidated by cyclic voltammetry and then HOMO-LUMO band gaps were calculated by using their oxidation and reduction onset potentials. Finally, electrochromic properties of poly-(MES16) and poly-(TST) were investigated via spectro-electrochemical measurements. DFT calculations exhibit that poly-(MES16) has a high planarity and an intramolecular charge transfer from the polymer backbone-donor to thiadiazole-acceptor subunit. Because of high solid state it it interactions of the poly-(MES16), a good quality film was obtained corresponding to self assembly property planar phenantrene center. Owing to this property, electrochromic performance of poly-(MES16) such as response time, stability and Delta T% were better than the standard poly-(TST). (C) 2016 Elsevier Ltd. All rights reserved.Öğe Electrochemical and optical properties of biphenyl bridged-dicarbazole oligomer films: Electropolymerization and electrochromism(Pergamon-Elsevier Science Ltd, 2009) Koyuncu, Sermet; Gultekin, Burak; Zafer, Ceylan; Bilgili, Hakan; Can, Mustafa; Demic, Serafettin; Kaya, İsmet4,4'-Di(N-carbazoyl)biphenyl monomer (CBP) was synthesized and coated onto ITO-glass surface by electrochemical oxidative polymerization. Its CV shows two distinct one-electron and stepwise oxidation processes occurred at 1.29 and 1.61 V. By using this property, the monomer was electrochemically polymerized separately at these oxidation states and thus, two different oligomer films were obtained afterwards. Their spectro-electrochemical and electrochromic properties were also investigated. Switching ability of the oligomers was evaluated by kinetic studies upon measuring the percent transmittance (%T) at their maximum contrast point, indicating that these oligomers were found to be suitable material for electrochromic devices. (C) 2009 Elsevier Ltd. All rights reserved.Öğe Electrochromic and electroluminescent devices based on a novel branched quasi-dendric fluorene-carbazole-2,5-bis(2-thienyl)-1H-pyrrole system(Royal Soc Chemistry, 2011) Koyuncu, Sermet; Usluer, Ozlem; Can, Mustafa; Demic, Serafettin; Icli, Siddik; Sariciftci, Niyazi SerdarWe report here the synthesis of a novel branched quasi-dendric system, 9,9'-(9,9'-dihexylfluorene-2,7-diyl)bis[3,6-bis(2,5-bis(2-thienyl) pyrrol-1-yl)carbazole], (FCSNS), in four steps, followed by coating onto an ITO-coated glass surface by an electropolymerization process to give a very stable cross-linked polymeric film (poly-FCSNS). The yellowish-green color of this film in its neutral state changed reversibly to black upon oxidation. An electrochromic device, assembled in the sandwich configuration [ITO/anodically coloring polymer (poly-FCSNS)//gel electrolyte//cathodically coloring polymer/(PEDOT)/ITO], exhibited a relatively short response time (about 1 s), a high redox stability, and a high coloration efficiency (1624 cm(2) C-1). In addition to electrochromic studies, organic light-emitting diode (OLED) work was also carried out using FCSNS. A multilayer OLED having a configuration of ITO/PEDOT:PSS/FCSNS/Alq(3)/LiF : Al was fabricated, and it showed a turn-on voltage of approximately 6 V and exhibited a bright green emission with a luminance of 3700 cd m(-2). The maximum luminous efficiency was found to be 2.0 cd A(-1) at 14 V and 11.75 mA cm(-2). The emitted light from the OLED device is green, and has the color coordinates of (x, y) (0.33, 0.54) according to CIE. Electrochemical and optical properties were also studied by using cyclic voltammetry, UV-Vis absorption and fluorescence spectroscopy, respectively.Öğe Fenantren Merkezli Multi Fonksiyonel Donor-Akseptör Tipi Makro Moleku?llerin Sentezi ve Opto-elektronik Uygulamaları(2016) Koyuncu, Sermet; Zafer, Ceylan; Koyuncu, Fatma Baycan; Can, MustafaBu projede, merkezde du?zlemsel yapıda fenantren moleku?lu? içeren farklı absorbsiyon ve emisyon bandlarına sahip bir dizi elektroaktif makromoleku?l ve polimer (AKD-X ve MGCX) sentezlenmiştir. Sentezlenen çıkış bileşikleri ve nihayi u?ru?nlerin kimyasal yapıları, FT-IR ve 1H-NMR analizleriyle aydınlatılmıştır. AKD-X ve MGC-X elektroaktif moleku?llerin optik özellikleri UV-Vis ve UV-floresas ölçu?mleriyle, elektrokimyasal özellikleri ise döngu?sel voltametri ölçu?mleriyle incelenmiştir. Elde edilen verilerden optik ve elektrokimyasal HOMOLUMO band boşluğu değerleri hesaplanmış, ayrıca temel hal ve uyarılmış haldeki yu?k dağılımları DFT hesaplamalarıyla belirlenmiştir. Elektroaktif özellikteki AKD-X moleku?llerinin Organik boya sensörlu? gu?neş hu?cresi (DSSC) uygulamalarında, MGC-X polimerleri ise elektrokromik uygulamalarda kullanılabileceği elde edilen sonuçlarla ortaya konulmuştur.Öğe One-step preparation of binder-free nickel-containing graphene foam electrode for supercapacitors(Wiley, 2024) Gultekin, Sirin Siyahjani; Karimi, Aziz Ahmad; Can, Mustafa; Demic, SerafettinIn this study, a nickel hydroxide (Ni(OH)2)-modified reduced graphene oxide (rGO) foam electrode for supercapacitor application is presented. The electrode was prepared without using a binder through a one-step process with three different ratios (NirGO1, NirGO2, and NirGo3). To compare the supercapacitor performance of the obtained graphene foam electrodes, rGO and rGO:carbon black (CB) standard electrodes with PVDF-HFP binder were also prepared. All electrodes were then characterized structurally (XPS, EDS, RAMAN, XRD, and FT-IR) and morphologically (SEM). Structural characterizations demonstrated that the Ni-containing electrodes were in alpha-Ni(OH)2:rGO structure. In addition, NirGO3 exhibited a specific capacitance of 800 F g-1 which is relatively the highest performance between the foam electrodes, while rGO:CB presented a specific capacitance of 900 F g-1. The results demonstrated that with the method proposed for electrode development, it was possible to obtain comparable results with the standard electrode rGO:CB. imageÖğe Push-pull type material having spirobifluorene as ?-spacer for dye sensitized solar cells(Pergamon-Elsevier Science Ltd, 2016) Can, Mustafa; Bilgili, Hakan; Demirak, Kadir; Gultekin, Burak; Koyuncu, Sermet; Kus, Mahmut; Zafer, CeylanTwo organic dyes for dye-sensitized solar cells (DSSC) based on spirobifluorene were synthesized and characterized. Electrochemical, spectroscopic and photovoltaic properties of the dyes have been investigated. Hexyloxy substituted triarylamine was used as electron donating moiety in the molecule while spirobifluorene and cyanoacrylic acid were used as pi-bridge and acceptor groups, respectively. MK162-sensitized solar cells exhibited a short-circuit current (I-SC) of 4,92 mA cm(-2), an open-circuit voltage (V-OC) of 520 mV and a fill factor (FF) of 0.59, resulting an overall power conversion efficiency of 1,52 where the reference cell, Z907 was yielded an overall conversion efficiency of 4.08% efficiency with 620 mV of V-OC and 14.51 mA cm(-2) of Isc under standard AM 1.5 illumination. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
