Filtreler
Synthesis, characterizatıon and application of new organic electroactive molecules for photovoltiıc devices

Doktora Tezi | 2017 | İzmir Katip Çelebi Üniversitesi Fen Bilimleri Enstitüsü

PEDOT:PSS is with its acidic property solves the indium atoms from ITO and indium atoms diffuses in active layer in an organic solar cell. This event causes an decreasing in solar cell efficiency. In the same strategy, SAM molecules can be used as hole injection layer. On the other hand MoO3 can be used as anode buffer layer. In this thesis it is wanted to make SAM molecules have to not absorb visible range of solar spectrum for the efficient harvesting of solar energy by donor molecule. Otherwise the HOMO level of SAM molecule have to be between work function of ITO and HOMO level of donor molecule. In this way SAM molecules which . . .don’t absorb the visible range of solar spectrum and with the suitable HOMO levels were designed, and applied on organic solar cell. On the other hand, while the series resistance in the solar cells to be formed with the synthesized molecules decreases according to the standard, parallel resistance increase is aimed. DSSCs were proposed instead of silicon solar cells with their easy production and low cost fabrication. The photosensitizer which is liable for the visible and near-infrared utilization of the solar light, is one of the basic components of the DSSCs. Metal free organic dyes can be thought as an alternative for the solar energy to electricity conversion in DSSCs. One of the important parameter for the dye is harvesting solar energy efficiently. If the dye absorbs all solar spectrum more energy could be harvested. Furthermore, the energy levels of dye has to be suitable with TiO2 and hole transport material. On the basis of this we designed two metal free organic dyes for DSSC, absorbing uv-visible range of solar spectrum and having proper HOMO-LUMO levels, were designed, and applied on dye sensitized solar cell Daha fazlası Daha az

Synthesis and application of the iridium semiconductor complexes for organic light emitting diodes

Doktora Tezi | 2017 | İzmir Katip Çelebi Üniversitesi Fen Bilimleri Enstitüsü

Organic light emitting diodes (OLEDs) is a multi-disciplinary research area. Due to the possibility of being produced in different designs and low costs, studies on the research and development of energy efficient structures have increased. These expectations have increased so much that research on new types of molecules and device designs is increasing with the expectation that OLEDs will be more efficient than all available light sources and that almost 100% of the energy used can be converted to light. Transition metal complexes, especially Iridium(III) complexes, which make them phosphorescent due to their high quantum yield and . . . broad emission colors, have been the most widely used emission material for OLED applications. Because the materials with this property provide both singlet and triplet transitions, all excited states contribute to light emission, so the theoretical internal quantum yield of these complexes can reach 100%. In this work, 4 spiro-based ligands were synthesized by Suzuki cross-linking methodology and 8 novel Ir(III) complexes were synthesized with these ligands. The synthesized molecules were characterized by 1HNMR, 13CNMR, UV-Vis, photoluminescence (PL) and cyclic voltammetry (CV) techniques. Ir(III) complexes have been prepared functionalized as two series. The photophysical properties of the functionalization have been examined to determine the effect on the emission. It was determined that complexes with solution phase emission studies had green and orange emissions ranging from 510 to 578 nm with the effect of functionalized electron donating group (EDG) and electron withdrawing group (EWG) groups. These results showed that substituent groups are effective on the emission of complexes. The results from cyclic voltammograms show that EDG and EWG groups and complexes have different energy band intervals (Eg value). Some of the synthesized iridium complexes were made with a light emitting device (single active layer OLED, light emitting electrochemical cell, LEC device). It has been observed that these devices can operate at low voltages. LEC devices were prepared in the ITO/PEDOT:PSS/Ir(III)complex/Ag configuration. It was determined that the prepared LEC devices started to radiate at on average of 5.5 V and the highest luminance value (in C2 complex) was measured as 1107 cd/m2 Daha fazlası Daha az

Synthesis of imidazole derivatives and their binderless immobilization to fabric to load antibacterial properties

Mutlu, Nurgül

Yüksek Lisans | 2017 | İzmir Katip Çelebi Üniversitesi Fen Bilimleri Enstitüsü

The compounds bonded with functional groups in textile materials carry the economical support material property. The complex and/or organic compounds with the desired properties can be immobilized into the textile materials by using the reactivity of hydroxyl groups of cellulose and the NH2 groups in wool. Most of commercially purchased silver salts show a rapid release of silver in water because of their ionic structure. For this reason, they exhibit high antibacterial activity but the short-term. N-heterocyclic carbene (NHC) complexes have the long-term antibacterial effects by releasing the silver ion into solution gradually. Rec . . .ently, the studies on the reactions about catalytic activities of silver NHC compounds have also increased. It is aimed to synthesize the light resistant, antibacterial and catalytic effective complex and also to immobilize this complex into the fabric by considering the light sensitivity of silver compounds. In the light of this information, synthesis, physical properties, and antimicrobial activities of imidazole based 1,3-disubstitue imidazolium silver (I) complexes have been targeted. The structure of synthesized compounds was determined by FTIR, NMR. The light stability of the complexes and antibacterial effectivities was investigated, then the complexes which are stable to light and exhibit antibacterial effectivity was immobilized to wool fibers with functional groups of the complexes. The immibolization was created with chemical bonding between the wool fabric and the synthesized compounds. The metal content of the immobilized complexes was analyzed by ICP and their surface characterization was identified by SEM. After the measurements of antibacterial effectivity and washing durability of immobilized complexes, color changing which is a general problem of silver compounds was measured using spectrophotometer. The antibacterial effectivities of the modified fibers were investigated by quantitative method at pre-washing and after sequence washings Daha fazlası Daha az

Using alcohol as a carrier producing polyanionic cellulose (PAC) polymer from solid textile waste

Karakuş, Hüseyin

Yüksek Lisans | 2016 | İzmir Katip Çelebi Üniversitesi Fen Bilimleri Enstitüsü

Cellulose is the most abundant organic polymer on earth. It is naturally regenerated by forests and cotton plantations with a speed of 10 billion metric tons per year regularly. Not only its natural reproduction makes it ecologically beneficial but also its biological degradability makes cellulose an ‘eco-friendly material’. Applications of cellulose is limited due to its insolubility in water. Contrarily, its water-soluble derivatives, especially cellulose ethers, are found in nearly all the products we are using in our daily life. Although cellulose is the main raw material for producing cellulose ethers, its commercial productio . . .n stopped with the shutdown of ‘Turkish Cellulose and Paper Factories’ (SEKA) in 2006. Turkish cellulose ether producers are forced to import all the cellulose they are using in their production. In 2009, 425 thousand tons of household textiles waste and 458.5 thousand tons of industrial textile waste was generated in Turkey. Most of these wastes are made of cotton yarn which has 90% cellulose content. This study aimed to use this type of textile waste as raw material for the production of polyanionic cellulose polymer (PAC), so that they would be returned back to the economy with higher values. This study is carried out as a project by The Scientific and Technological Research Council of Turkey (TÜBİTAK) and Ugur Seluloz Kimya A.S. under the 1507 - SME RDI (Research, Development & Innovation) Grant Programme. In this waste recovery process, solid textile waste is used as raw material and the alcoholic (ethyl alcohol) medium is used to increase the quality of the PAC products in order to meet the criteria of PAC LV (low viscosity) and PAC HV (high viscosity) standards introduced by American Petroleum Institute (API). The most important outcome of this study was to produce PAC-LV and PAC-HV polymers in API standards from textile waste without using any imported cellulose. This production method not only prevents the import but also enables the use of natural wastes so that the added value of the product increases. Quality of synthesized products (PAC-LV and PAC-HV) are verified by Turkish Petroleum (TP) Research Laboratories Daha fazlası Daha az

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