A novel ionic liquid crystal (ILC) system (C18IMCNBr) with a liquid crystal alignment used as an electrolyte for a dye-sensitized solar cell (DSSC) showed the higher short-circuit current density (Jsc) and the higher light-to-electricity conversion efficiency than the system using the non- alignment liquid crystalline ionic liquid (C18IMCNBr),due to the higher conductivity of liquid crystal alignment. The larger Jsc and efficiency value of liquid crystal alignment supported that the higher conductivity of liquid crystal alignment is attributed to the enhancement of the exchange reaction between iodide species. As a result of formation of the two-dimensional electron conductive pathways organized by the localized I3- and I- at liquid crystal alignment layers, the concentration of polyiodide species exemplified by Im- (m =5,7, ...) was higher in alignment C18IMCNBr. However, in the two-dimensional electron conductive pathways of C18IMCNBr, more collision frequencies between iodide species (I-,I3-, and Im-) could be achieved than that in the three-dimensional space of C18IMCNBr, which could lead to the promotion of the exchange reaction between iodide species, the contribution of a two-dimensional structure of the conductive pathway through the increase of collision frequency between iodide species was proposed.

The study proposed a high efficient dye sensitize solar cell (DSSC) by embedding liquid crystal in liquid electrolyte. When liquid crystal molecules was disperse in the liquid electrolyte, the light-scattering occur due to refractive index mismatching by randomly oriented liquid crystal droplets. The light-scattering allows solar light have longer optical path length within the solar cell and therefore enhances light-trapping efficiency of N719 dye. The experiment results reveal that the DSSC with the liquid crystal concentration of 20 wt% have best electric conversion efficiency. Moreover, the study also introduces chloseteric liquid crystal to the liquid electrolyte of a DSSC and compare with nematic liquid crystal embedded DSSC. The cholesteric liquid crystal with periodic helical structure in the liquid electrolyte provides not only light-scattering but also selective reflection. Compared with nematic liquid crystal embedded DSSC, the cholesteric liquid crystal embeded DSSC has a more large light-trapping efficiency due to combined effects of light scattering and selective reflection. Besides, when the reflective band (480~580nm) of cholesteric liquid crystal is matched to the absorption spectrum of N719 dye, the DSSC has better photoexcitation of dye and photovoltaic performance.

Alternative energy sources such as solar energy have attracted an extensive interest in the petroleum shortage era. Among solar cells, dye-sensitized solar cell (DSSC) attracts the attention of widespread research teams because of the easy-production process, low cost, and good photon-to-electron conversion efficiency. In this study, both UV and acid solution such as HCl are used to improve the efficiency of DSSC. The UV illumination can eliminate organic contaminates on TiO2 by photocatalysis and enhance the adsorption of dye molecules. Meanwhile, the coordination mode between TiO2 and dye could be changed and lower the electron transportation. If the HCl solution is used after UV illumination, the coordination mode can be preserved. Moreover, H+ from HCl can attract the COO¡Ð anchoring group of dye by electrostatic force. It further increases the adsorption of dye and improves the DSSC efficiency. The coordination mode was measured by Fourier-transform infrared spectrometer (FTIR). The internal resistance was measured by electrical impedance spectroscopy (EIS). The chemical properties were characterized by X-ray photoelectron spectroscopy (XPS). The light absorbance was measured by ultraviolet-visible spectroscopy (UV-Vis). The morphology was observed by field emission scanning electron microscope (FE-SEM). The performance of the cells was measured by a semiconductor device analyzer. In our results, the conversion efficiency was improved from 6.29% of untreated one to 6.71 and 7.39% for UV and UV + HCl treated ones.

In this research, gel-state and quasi-solid state dye-sensitized solar cells (DSSCs) were fabricated with polydimethylbenzimidazole(PDMBI) as the polymer electrolyte. These devices are stable under room light in air, even without encapsulation. The energy conversion efficiency of gel-state cells was drastically increased around 200% after the device worked. We propose that appropriately aggregated PDMBI in electrolyte layer could provide pathways which would facilitate the diffusion of ion through the electrolyte. Moreover, this arrangement induces it an ion exchange reaction which could lead to the promotion of the diffusion rate between iodide species. An optimized device performs well with a power conversion efficiency of 4.98% under air-mass 1.5 global (AM 1.5G) illumination. For the fabrication of quasi-solid state dye-sensitized solar cells, we immersed a few liquid electrolyte to improve electrical contact between TiO2 porous layer and PDMBI layer. The quasi-solid state cell efficiency fabricated with PDMBI as electrolyte was 2.26%. Furthermore, our device architecture is performing well because of the good band alignment among TiO2, dye, and PDMBI. In this research, we have successfully demonstrated gel-state and quasi-solid state dye-sensitized solar cells comprising PDMBI as electrolyte.

A set of three through-bond energy transfer cassettes based on BODIPY as a donor and cyanine dyes as acceptors has been prepared via Sonogashira couplings, and their photophysical properties were examined. These cassettes fluoresce around 600 to 800 nm and are resolved by approximately 100 nm. This property is an important factor for multiplexing study in cellular imaging. Several useful fluorescent probes such as 5- and 6-carboxyfluorescein, water-soluble BODIPY, and water-soluble Nile Blue dyes, have also been synthesized and their photophysical properties studied. We have also attempted to develop a method for protein mono-labeling via a solidphase approach. The labeling of protein with one fluorescent dye facilitates quantification and single molecule imaging in biological applications. Various solidsupports such as PEGA, CPG, and BSA-coated CPG, were tested. Photolabile and chemically cleavable linkers were prepared to connect solid-supports and fluorophores. Unfortunately, our approach to the fluorescent mono-labeling of native proteins did not give us any conclusive results.

The laser-induced molecular reorientation effect of guest-host dye-doped liquid crystals in isotropic phase has been studied by measuring the signals of optical Kerr effect using pulsed frequency-doubling Nd:YAG laser as a pumping source. The critical behavior near the isotropic-nematic transition has been observed when the temperature approaches to the phase transition of liquid crystal. The relaxation time constant is about several hundreds of ns as the temperature is far above the clearing point of liquid crystals and that is longer than 1500 ns as the temperature is close to the clearing point of liquid crystals. According to Landau¡¦s second phase transition theory, the interaction between liquid crystal molecules will be increased and the nonlinearity effect of liquid crystal will be enhanced when the temperature is near the clearing point of liquid crystal. The relaxation time constant of molecular reorientation is a function of viscosity and temperature of liquid crystal, the relationship can be fitted as£b0*exp(f/T)*(1/T-T*),where £b0 is the viscosity coefficient and T* is the clearing point of the sample. The optical Kerr signal is found to be proportional to the energy density of pumping source. The optical Kerr signal can be sustained as long as 20£gs when the energy density of pumping source reaches to 1J/cm sq. The enhancement of molecular reorientation effect is also observed by increasing the concentration of dye.

Xenobiotic compounds, which are exclusively man made, are produced in large quantities every year and released to the environment. Besides, anaerobic sludge digestion offers advantage in co-treatment of hazardous substances produced by the industry. The performance of the digesters can be monitored by modeling efforts. In this study, Anaerobic Digestion Model No.1 (ADM1) was calibrated, and validated for full-scale digester, lab-scale digester, and lab-scale digester seeded with totally different anaerobic biomass than that of full-scale digester. The model xenobiotic compound, a mono azo dye RO107, was co-treated with sewage sludge in an anaerobic digester. High removal efficiencies as 98% was found for azo dye at standard operating conditions of anaerobic digesters. The digester performance was not effected from azo dye or its reduction products. The dye reduction mechanism was modeled by biochemical mechanism due to unspecific enzymes and by chemical mechanism due to sulfide reduction. Some of the dye metabolites were suggested to be degraded by aerobic biotreatment. The anaerobic reduction metabolites of RO107 were identified as 2-(4-aminophenylsulfonyl) ethanol and 2,5-diamino-4-formamidobenzenesulfonic acid, and sulfanilic acid.

Wide band gap metal oxides have recently become one of the most investigated materials in surface science. Among these metal oxides especially TiO2 attracts great interest, because of its wide range applications, low cost, biocompatibility and ease of analysis by all experimental techniques. The usage of TiO2 as a component in solar cell technology is one of the most investigated applications of TiO2 . The wide band gap of TiO2 renders it inecient for isolated use in solar cells. TiO2 surface are therefore coated with a dye in order to increase eciency. This type of solar cells are called dye sensitized solar cells . The eciency of dye sensitized solar cells is directly related with the absorbed light portion of the entire solar spectrum by the dye molecule. Inspite of the early dyes, recent dye molcules, which are called wider wavelength response dye molecules, can absorb a larger portion of entire solar spectrum. Thus, the eciency of dye sensitized solar cells is increased by a considerably amount. In this thesis the electronic structure of organic rings, which are the fundamental components of the dye molecules, adsorbed on anatase (001) surface is analyzed using density functionaltheory. The main goal is to obtain a trend in the electronic structure of the system as a function of increasing ring number. Electronic structure analysis is conducted through band structure and density of states calculations. Results are presented and discussed in the framework of dye sensitized solar cells theory.

Environmental regulations have imposed limitations on a wide variety of organic and inorganic pollutants in industrial textile wastewaters. There are several degradation methods used in literature studies. Among these methods ozonation is one of the most considered way to degrade refractory chemicals in textile wastewaters. In recent years, catalytic ozonation as being one of the advanced oxidation processes (AOPs), is applied to reduce the ozone consumption and to increase the Chemical Oxygen Demand (COD) and Total Organic Carbon (TOC) removals. Ozonation and catalytic ozonation of single and mixed dye solutions have been examined both in a semi-batch reactor and also in a three phase fluidized bed reactor. The dyes that are used in this study are Basic Blue 41 (BB-41), Basic Yellow 28 (BY-28) and Basic Red 18.1 (BR-18.1), these dyes are obtained from AKSA A.S. (Yalova, Istanbul) textile plant. In order to measure the concentration of each dye in the mixed dye solution, &ldquo / absorbance vs. concentration&rdquo / calibration correlations were developed. The effect of inlet dye concentration, inlet gas and liquid flow rates, pH, catalyst type [perflorooctyl alumina (PFOA) and alumina] and catalyst dosage were determined experimentally. Catalyst characterization analyses were done in order to determine the maximum number of times that the catalyst can be used and it was found to be 3 times. Gas washing bottle experiments are conducted to find the v amount of ozone required to oxidize one mole of each dye used in the study. Oxidation of BB-41, BR-18.1 and BY-28 dyes were investigated in a semi-batch reactor as single dye solutions by sole and catalytic ozonation with alumina and PFOA catalyst particles. The highest TOC and COD removals being 58.3% and 62.9%, respectively, were obtained at pH of 10 for BB-41 and 55.2% and 58.8%, respectively, for BR-18.1 with alumina catalyst. On the other hand, for BY-28 PFOA catalyst yielded highest TOC and COD reductions being 61.3% and 66.9%, respectively, at pH of 4. Minimum fluidization velocity (uL,min), the hold-up values of gas, liquid and solid phases, the dispersion coefficients (DL), and volumetric ozone-water mass transfer coefficients (kLa) were estimated at various gas and liquid flow rates in order to observe the effect of liquid mixing in the reactor on ozonation process. While PFOA catalyst was found to be effective in oxidizing BY-28 in acidic conditions (pH=4), BR-18.1 and BB-41 are degraded in alkaline medium (pH=10) with alumina catalyst better compared to acidic conditions. For catalytic ozonation reactions in fluidized bed reactor, the highest dye removals in mixed dye solution were observed for BY- 28 being 99.29% for gas flow rate (QG) of 340 L/h, liquid flow rate (QL) of 150 L/h and pH=4, initial dye concentration being 30 mg/L of each dye with PFOA catalyst, while for BR-18.1 and BB-41 being 95.39% and 97.95% respectively for QG = 340 L/h, QL = 150 L/h and pH=10, initial dye concentration being 30 mg/L of each dye with alumina catalyst. The highest TOC and COD reductions, 25.2% and 32.4%, respectively, were achieved in the catalytic ozonation of the mixed dye using PFOA as the catalyst at a pH of 4 and at a gas to liquid flow rate ratio of 2.26 (QG = 340 L/h, QL = 150 L/h). Highest dye removals were obtained at the same gas and liquid flow rates as those of the highest TOC and COD reductions in the experiments. Empirical TOC removal equations were obtained as a function of inlet TOC concentration, solution pH, gas and liquid flow rates.

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