Yazar "Doyranli, Ceylan" seçeneğine göre listele

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    A novel interface layer for inverted perovskite solar cells fabricated in ambient air under high humidity conditions
    (Pergamon-Elsevier Science Ltd, 2020) Choi, Fatma Pinar Gokdemir; Alishah, Hamed Moeini; Bozar, Sinem; Doyranli, Ceylan; Koyuncu, Sermet; San, Nevim; Kahveci, Cihangir
    A novel benzotriazol based small molecule (2-hexyl-4,7-bis(5'-hexyl-2,2'-bithien-5-yl)-2H-1,2,3-benzotriazole) BTBT was synthesized by Suzuki coupling reaction and was successfully employed in planar inverted perovskite solar cells with ITO/BTBT/PEDOT:PSS/CH3NH3PbI3-xCl(x)/PCBM/Al configuration. Fabrication processes, including the spin coating of the perovskite layer, were performed in ambient air, under high humidity conditions (>60%). BTBT/PEDOT:PSS bilayer notably improved the power conversion efficiencies (PCE) from 9.65% to 11.6%, which corresponds to an increase of 20%.
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    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, Sermet
    In 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.
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    Effect of thiophene linker addition to fluorene-benzotriazole polymers with the purpose of achieving white emission in OLEDs
    (Royal Soc Chemistry, 2020) Kok, Cansu; Doyranli, Ceylan; Canimkurbey, Betul; Mucur, Selin Piravadili; Koyuncu, Sermet
    With the purpose of obtaining white emission from single layer organic light emitting diodes (OLEDs), fluorene benzotriazole based polymers with double bond subunits (namely TP2 and SP3 with and without thiophene linker, respectively) were synthesized by a Suzuki cross-coupling polymerization reaction. SP3 and TP2 were used as an emissive layer of the OLED devices due to their outstanding solubility in organic solvents, photoluminescence intensity and morphological suitability for fine thin film-forming capability. The optical, electrochemical, light emission and electroluminescence characteristics, Density Functional Theory (DFT) calculations and admittance spectroscopic analysis of OLEDs based on SP3 and TP2 were realized in detail to understand the effects of thiophene linker addition as a donor unit to the main chain of fluorene benzotriazole based polymers. As a result, TP2 emitted a bright yellow emission with a maximum brightness of 243 cd m(-2) at 40 mA cm(-2), and a maximum current efficiency of 1.38 cd A(-1) with more broad electroluminescence characteristics than SP3 polymer without the thiophene linker. SP3 emitted a greenish yellow emission with a maximum brightness of 1001 cd m(-2) at 845 mA cm(-2), and a maximum current efficiency of 0.33 cd A(-1). Carrier transport properties, charge carrier transit time and the equivalent circuit modelling studies were obtained through admittance spectroscopy. An equivalent circuit model with a combination of two resistors and one capacitor explained the charge conduction mechanism of SP3 and TP2 based OLEDs. SP3 and TP2 OLED devices represented typical p-type transporting characteristics with mobilities of 0.073 and 0.017 cm(2) V-1 s(-1), respectively with simplified device configuration. All the results indicate that thiophene addition to the main chain of fluorene benzotriazole based polymers with double bond subunits lead to a promising candidate for white emissive materials used in single layer white OLEDs.
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    Solution processable neutral state colourless electrochromic devices: effect of the layer thickness on the electrochromic performance
    (Royal Soc Chemistry, 2016) Tahtali, Gurhan; Has, Zeynep; Doyranli, Ceylan; Varlikli, Canan; Koyuncu, Sermet
    In this study, a neutral state colourless electrochromic device fabricated through a solution process is introduced. The device contains indium doped transparent oxide coated glass as the transparent conductive electrode, poly(N-(2-ethylhexyl) carbazol-3,6-diyl) (PCbz) as the anodically colouring material, poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) as the ion storage layer and a lithium perchlorate based conducting gel electrolyte. A maximum optical contrast (Delta T%) of 58% at 800 nm is achieved by optimizing the film thickness of both the organic layers. The device that has layers of 220 nm PCbz and 120 nm PEDOT: PSS thickness revealed a high coloration efficiency (1246 cm(2) C-1) and colouring and bleaching response times of 5.6 s and 2.3 s, respectively.
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    Tetra-Carbazole based electroactive donor-acceptor dyes: Effect of the phenyl bridging unit on the electrochromic performance
    (Elsevier Sci Ltd, 2022) Doyranli, Ceylan; Altinisik, Sinem; Ozdemir, Mucahit; Koyuncu, Sermet
    In this study, a new Donor-Acceptor-Donor (D-A-D) electroactive molecules (HCQM1 and HCQM2) containing 9H-carbazole and 9-phenyl-9H-carbazole as donor along with quinoxaline (HQ) as acceptor were synthesized and then coated on Indium Tin Oxide/Glass (ITO/Glass) surface by the electrochemical oxidation process. The HOMO-LUMO band gap values obtained by electrochemical oxidation and reduction onsets were calculated as 2.64 and 2.68 eV, respectively. On the other hand, UV-Vis absorption measurements showed that the charge transfer band of HCQM1 was detected at 500 nm with 50 nm red shift upon compared with the HCQM2. According to AFM results, it is seen that the roughness of the poly(HCQM2) film is higher than the poly(HCQM1) film. Finally, the polymer film of HCQM2 showed multi-electrochromic color change (yellow, green, and dark blue) upon the oxidation process. When the electrochromic performance of the HCQM1 and HCQM2 polymer films was compared, it was discovered that the HCQM2 with phenylene spacer unit has better stability and a higher percentage transmittance change (& UDelta;T%) between neutral and oxidized states.
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    Thiol-ene-clickable and emissive carbazole-based polymer networks with tunable colors
    (Elsevier Science Bv, 2016) Doyranli, Ceylan; Buyukcelebi, Sumeyra; Koyuncu, Sermet; Usluer, Ozlem; Kus, Mahmut; Koyuncu, Fatma Baycan
    Band gap tuning and processability of organic materials are significant topics for both scientific research and commercial applications. In this study, we synthesized a series of main chain cross-linkable polymers by thiol-ene click chemistry from N-allyl carbazole and different heterocycles via conventional Suzuki coupling polymerization reaction. The emission color of polymers could be successfully tuned from blue to red by attaching different benzazole-acceptor moieties to the carbazole donor unit. We also investigated the effects of cross-linking with respect to the amount of pentaerythritol tetrakis(3-mercaptopropionate) cross-linker on the optical, electrochemical, and surface morphological properties of the polymer films. The results showed that these polymers can be used as emissive active layers in solution-processable multilayer organic light-emitting diodes. (C) 2016 Published by Elsevier B.V.
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    Triphenylamine-based organic small-molecule interlayer materials for inverted perovskite solar cells
    (Elsevier, 2022) Doyranli, Ceylan; Choi, Fatma Pinar Gokdemir; Alishah, Hamed Moeini; Koyuncu, Sermet; Gunes, Serap; San, Nevim
    In this report, two novel donor-acceptor-donor type triphenylamine-quinoxaline-based (QC-TPA and QC-TPAOMe) small organic molecules have been synthesized by the Suzuki coupling reaction as hole transport materials (HTMs) and successfully utilized in the NiOx/perovskite interface. All device fabrication steps with ITO/NiOx/QC-TPA or QC-TPAOMe/CH3NH3PbI3/PCBM/BCP/Ag configurations were performed in ambient air over 55% relative humidity, except for thermal evaporation of metal contacts. Modifications of the NiOx/ perovskite interface with QC-TPA and QC-TPAOMe molecules can improve FF and JSC by enhancing hole extraction and reducing energy losses. Consequently, the power conversion efficiency (PCE) boosted from 10.03% to 14.46% and 13.21% with surface modifications of NiOx with QC-TPA and QC-TPAOMe, respectively.