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İstanbul Teknik Üniversitesi / Fen Bilimleri Enstitüsü / Kimya Anabilim Dalı

2,6-ditiyofen-2-il-3,5-bis(4-(tiyofen-2-il)fenil)ditiyeno(3,2-b;2',3'-d)tiyofen sentezi ve elektrokromik özelliklerinin incelenmesi

Synthesis and electrochromic properties of 2,6-(thiophen-2-yl)-3,5-bis(4-(thiophen-2-yl)phenyl)dithieno(3,2-b;2',3'-d)thiophene

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Özet:

Endüstriyel uygulamalar ve bilimsel çalışmalarda konjuge polimerler ilgi odağıdır Ditiyenotiyofenler, tiyofen halkalarında bulunan kükürt atomları sayesinde iyi elektron vericidirler Dithienothiophenes (DTT) ve DTT türevleri malzemeler, elektrokromik cihazlar, enerji depolama, organik alan etkili transistörler, fotovoltaik aygıtlar, yarı iletkenler ve organik alan etkili transistörler gibi alanlarda elektronik ve optoelektronik gibi alanlarda umut verici özellikleri sergiliyor Bu çalışmada, DTT Th4DTT türevi, sentezlendi ve bu malzeme elektrokimyasal uygulandı Th4DTT, Fouriertransforminfrared (FTIR), nükleer manyetik rezonans (NMR) spektrometrisi, hızlı bombardımanı kütle spektroskopisi (FAB-MS), veya yüksek çözünürlüklü kütle spektroskopisi (HR-MS), ultraviyole ve görünür alan spektroskopisiyle (UV-VIS) karakterize edildi ...

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Summary:

Conjugated polymers have been drawing great attention due to their important applications in industry Dithienotiopenes (DTT) have three sulfur atoms which make them rich in sulfur and good electron donors Dithienothiophenes (DTT) and their derivatives are exhibiting promising properties applicable to electronics and optoelectronics such as electrochromic devices, energy storage, organic field effect transistors, photovoltaic devices and semiconductors In this work, a DTT derivative Th4DTT was synthesized and its electropolymerization was performed Th4DTTwas characterized by Fourier transform infrared (FTIR), ultraviolet?visible (UV?VIS) spectroscopy, nuclear magnetic resonance (NMR) spectrometry, fast bombardment mass spectrometry (FAB-MS) and high resolution mass spectroscopy (HR-MS) The solution of 1 (0 3g, 5 93mmol) was dissolved in DMF (250ml) at room temperature and covered The solution was stirred until it became 00C in ice bath NBS (0 316g, 1 77mmol) was added in dark environment It was left stirring for 4 hours After 4 hours it was allowed to warm to room temperature The solution was poured into water Stools were taken by filtration The product 2 was purified with crystallization in toluene (Yellow powder, 0 346g, 88%) To the mixture of Pd0(PPh3)4 (%5), K2CO3 (2ml, 2M) and 4,4,5,5-tetramethyl-2-(thiophen-2-yl)-1,3,2-dioxaborolane 3 (0 569g, 2 71mmol) dissolved in THF (150 ml) and stirred for 0 5 h at room temperature under nitrogen atmosphere 4 (0 3g, 0 451mmol) was added to mixture and the mixture was stirred for 2 days at 60 0C It was then cooled to room temperature, filtered through celite The organic layer was extracted with dichloromethane and dried over Na2SO4 The solvent was evaporated under reduced pressure (Orange powder, 0 226g, 75%) The electroactivities of the monomer and the polymer were studied by CV Into a three component CV cell was placed two Pt wires, as counter and working electrodes, and Ag/AgCl as a reference electrode along with TBABF4 (0 1 M) mixture as a supporting electrolyte in DCM The electropolymerization of Th4DTT on ITO was performed in TBABF4 (0 1 M) in DCM solution under the constant potential of +1 5 V, for which the charge was optimized as 20 mC A mixture of TBABF4:PMMA:PC:ACN was prepared with a weight ratio of 3:7:20:70 TBABF4 and PMMA are dissolved in ACN The mixture was stirring and heating until it became homogeneous PC was added to plasticize the solution Stirring and heating were continued until a gel was obtained Th4DTT and EDOT were separately prepared via electropolymerization on ITO The gel electrolyte was spread between the two layers for the preparation of the ECD The electropolymerization of Th4DTT on ITO was performed in TBABF4 (0 1 M) in DCM solution under the constant potential of +1 5 V (2 5x10-2C) The PEDOT layer was constructed by electropolymerization of EDOT (0 01 M in ACN) in 0 1 M TBABF4 in ACN under the constant potential of 1 4 V (1 9x10-2C) Th4DTT was electropolymerized in a cyclic voltammetry cell, using Pt wires as counter and working electrodes and Ag/AgCl as a reference electrode The oxidation and reduction potentials of the polymer were determined to be 1 37 and 0 89 A linear change in the cyclic voltammetry of the monomer-free polymer was observed at various scan rates i e 50, 100, 150, 200 and 250 mV/s P(Th4DTT) electrochemically coated on ITO cleaned with a monomer free solution to remove the unreacted monomers The ITO was placed in a cuvette for a UV? VIS measurement The changes in the absorbance were from 0 to +1 7 V The neutral form of the polymer had two absorption peaks at 335 and 426 nm When applied voltage increases, reduction were observed in the neutral state?s peaks and a new bipolaron peak appeared at 721 and 1051 nm The color of the polymer changed from orange to green then blue as the bathochromic shift took place Electrochromic materials ability to change color sharply and rapid switching between oxidized and neutral states are important The switching time is the time taken from the highest transmittance value to the lowest The switching experiments were performed at four different and fixed wavelengths 721 nm from 0 to 1 5 V The switching time was found to be 5 s for each wavelength and the optical contrast was 31% at 731 nm The configuration of the ECD can be represented as ITO/P(Th4DTT)||gel electrolyte||PEDOT/ITO While constructing the ECD, anodically coloring P(Th4DTT) was kept in its neutral form and cathodically coloring PEDOT was in its oxidized state The color of P(Th4DTT) at 0 0 V was observed to be orange and the color of PEDOT layer was a transparent blue When 0 V was applied, the color of the ECD was observed to be brown As the potential was increased up to 1 2 V, the color of the ECD turned to green When 1 8 V applied, the color of ECD turned to dark blue Chronoabsorptometry technique was used to perform the switching time measurements The wavelength of the measurement was found to be 611 nm The switching potentials were applied from 0 V to 1 8 V and the optical contrast (% ?T) was found to be 28% The switching time was determined to be 10s An ECD?s stability gives information about the lifetime of the device Tests indicated that the ECD had a good stability with a continuous redox switching under applied potential range between 0 0 and 1 8 V even after 500 cycles ...

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