Titanium oxide (TiO2) films have been actively investigated as many applications because of the mechanical and chemical durability, high refractive index and high transparency. In catalytic and electrochemical applications, it has been utilized as a stable semiconductor electrode for the conversion of solar energy into chemical or electrical energy. Uniform TiO2 films were deposited on conductive glass substrate (ITO/glass) by liquid phase deposition (LPD) with the aqueous solutions of ammonium hexafluoro-titanate and boric acid. Niobium oxide powder and Hydrofluoric acid which add deionized water were used to be Niobium doping solution. Undoped LPD-TiO2 has hydroxyl related defects and Li+ ions will be trapped to degrade the electrochromic durability. For niobium doping, the electrochromic characteristics were enhanced. Niobium doping in TiO2 can reduce hydroxyl related defects. The electrochromic durability was enhanced from 5¡Ñ103 to 1¡Ñ104 times. The transparency ratio was enhanced from 61 % to 70 % at the wavelength of 550 nm. In our experiment, TiO2 films morphology and thickness was characterized by scanning electron microscopy (SEM), structure was characterized by X-ray diffraction (XRD) and surface roughness was measured by atomic force microscopy (AFM), chemical properties was characterized by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR), optical properties was characterized by spectrophotometer (MP-100), and electrochromic characterized by cyclic voltammetry (CHI627C).

The microstructural, electrochemical and optical properties of sol-gel derived tungsten oxide electrochromic coatings have been investigated. Coatings were formed by spinning of tungsten metal based aqueous sol on glass with native ITO layer. Three sol formulations / acetylated peroxotungstic acid (APTA), peroxotungstic acid (PTA) and titanium-doped peroxotungstic acid (Ti-PTA) were employed to obtain 200-300 nm thick multi-layered coatings. Material and electrochromic characterization of the coatings have been performed by DSC, XRD, SEM, cyclic voltammetry and UV-Vis spectroscopy. The electrochromic performance of the WO3 coatings was influenced by calcination temperature, by sol chemistry and by the adsorbed water content. For all sol formulations the coatings calcined at 250 &deg / C were amorphous and have shown better performance compared to crystalline counterparts calcined at 400 &deg / C. High calcination temperature also leads to formation of WO3 nanocrystals for APTA and PTA derived coatings, titanium doping retards crystallization. Presence of acetic acid as in APTA sol improved the electrochromic and electrochemical performance. This was related to removal of organics- acetic acid and peroxo ligands- during calcination, which results in an open W-O network providing more ion insertion sites. The water adsorption affected the electrochromic performance in different ways for the coatings calcined at 250 &deg / C and 400 &ordm / C. The amorphous coatings with limited structural water removal and excessive hydroxyl groups tend to crystallize by condensation of W-OH groups upon storage in open atmosphere, therefore exhibiting degrading electrochromic activity with aging. Conversely, hydroxyl groups enhanced Li+ ion insertion for the stable crystalline coatings calcined at 400 &deg / C.

The building sector is a one of modern society’s biggest users of energy. In turn, a building’s windows have a significant impact on its energy usage. Electrochromic windows have a thin film on one of the panes, designed to variably change the tint of the window. Thereby the solar heat gain, needed internal lighting and building energy utilization are varied. This thesis uses the simulation software IDA ICE 4.5 to simulate control scenarios for electrochromic windows. The goal is to examine how well this software can simulate the windows as well as to explore the potential of creating custom control algorithms for the windows. The impact of the control scenarios on the energy consumption of a building is then analyzed. The reference case for the simulations is a regular window with blinds, where the blinds are controlled with a built-in algorithm. The simulated control scenarios for the electrochromic windows were; the built-in algorithm, always off, always on, operative temperature, workplane illuminance, and light levels at the façade and window. In the simulation results the energy usage was slightly lowered with the electrochromic windows using the built-in control compared to the reference case. The custom algorithm that uses the light levels at the façade and window was designed to improve upon the built-in algorithm with additional adjustable settings. However, this custom algorithm produced similar results to the built-in algorithm and the majority of the additional settings had little impact on the energy usage. The other custom designed algorithms measured workplane illuminance and operative temperature to control the shading. These showed an overall decrease in the energy usage compared to the reference case. The IDA ICE software has potential for further simulations of a building’s energy usage while using electrochromic windows. Further investigation is needed to determine if the simulation resolution is high enough to accurately depict the effect these settings might have on the energy usage.

Living polytetrahydrofuran (PTHF) was terminated with sodium thiophenemethonate to yield a polymer with thiophene groups at one (PTHF1) and both ends (PTHF2). Copolymerizations of PTHF1 and PTHF2 insulating polymers with pyrrole and thiophene were achieved in water-p-toluene sulfonic acid (PTSA) and acetonitrile (AN)-tetrabutylammonium tetrafluoroborate (TBAFB) solvent-electrolyte couples via constant potential electrolysis. Characterization of the samples were performed by Nuclear Magnetic Resonance Spectroscopy (NMR), cyclic voltammetry (CV), Fourier Transform Infrared Spectroscopy (FT-IR), Thermal Analyses (TGA), (DSC) and Scanning Electron Microscopy (SEM). Electrical conductivities were measured by four-probe technique. PTHF1/PTh and PTHF2/PTh films which were deposited on ITO-glass in dichloromethane-TBAFB solvent-electrolyte couple found out to be anodically coloring copolymers that electrochemically switch between an oxidized blue and reduced red state exhibiting electrochromic behavior. Spectroelectrochemical Analysis (SEC) was run in UV-VIS region to reach a better understanding of the band structures of PTHF1/PTh and PTHF2/PTh electrochromic copolymers. Optoelectrochemical analyses were introduced as a new method for the characterization of copolymers.

Electrochromic films undergo a colour change when small ions and electrons are inserted into them, under the influence of an applied electric field. These films are also known as ion-intercalation electrodes, and may be incorporated into glazing structures more commonly known as 'smart windows'. Smart windows are that which may be used to control the amount of heat and light entering a building and may therefore be used to minimise the energy consumption associated with heating, cooling and lighting. The commercial success of smart windows, requires that they operate reproducibly at temperatures up to approximately 70ºC, for many tens of thousands of colouring and bleaching cycles. An understanding of the underlying kinetic processes over a wide temperature range is therefore needed, in order to determine suitable control strategies and switching conditions capable of fulfilling these requirements. The research detailed in this thesis has involved an investigation into the kinetic behaviour of ion-intercalation electrodes, and simulation of the electrical response as a means of developing a tool for predicting and then optimising electrochromic switching. More specifically, the electrical and optical properties of electrochromic thin films of WO3/TiO2 have been studied over a wide temperature range, appropriate for the operation of electrochromic windows. The magnitude of the voltages required for coloration and bleaching significantly reduces as temperature increases. Some irreversibility was observed at high temperature, as well as a reduction in coloration efficiency. Further investigation revealed that self-bleaching and irreversibility effects were caused by the presence of water, and this problem was exacerbated at high temperature. Post-experiment chemical analysis of a film sample revealed that some trapping of the inserted ions had occurred, however the amount of ions remaining in the film was much smaller than expected. The results suggested that a large quantity of the lithium ions injected into the film were lost to the electrolyte after many cycles, possibly accompanied by some film dissolution. Experimental work carried out in a dry-box showed that films may be cycled reversibly in a very dry environment, and the optical properties were independent of temperature under these conditions. Unfortunately, the conditions which led to reversible cycling and good electrochromic memory, also resulted in very long response times for film bleaching. This result implies that a good electrochromic memory and a fast response are mutually competitive aims. Data from high temperature experiments was simulated with a mathematical model and the mobility of lithium ions inside the electrochromic films was estimated in the process. The estimated diffusion coefficients agreed well with published values, and exhibited an Arrhenius dependence on temperature. Activation energies for diffusion were calculated and the results were very reasonable. Some deviation from ideal Arrhenius behaviour was observed for the estimated diffusion coefficients at high temperature. It is likely that the rate limiting mechanism changes from diffusive motion of ions at low temperature, to charge transfer at high temperature.

Thesis (Ph.D.)--Tufts University, 1996. / Adviser: Terry E. Haas. Submitted to the Dept. of Chemistry. Includes bibliographical references. Access restricted to members of the Tufts University community. Also available via the World Wide Web;

Thesis (Ph.D.)--Tufts University, 2003. / Adviser: Ronald B. Goldner. Submitted to the Dept. of Electrical and Computer Engineering. Includes bibliographical references. Access restricted to members of the Tufts University community. Also available via the World Wide Web;

This thesis is dedicated to developing novel photofunctional molecular materials for the applications in chemical sensing, bioimaging and electrochromic. To begin with, a brief introduction of photofunctional molecular materials and an overview of their applications in chemical sensing, bioimaging and electrochromic were presented in Chapter 1. In chapter 2, we have synthesized a series of water-soluble phosphorescent cationic iridium(III) solvato complexes (1-7) as multicolor cellular probes for imaging in living cells. All of these complexes can be dissolved in PBS. The emission of complexes can be tuned from green to red by changing the chemical structure of cyclomedtalating ligands. All complexes exhibit low cytotoxicity to living cells and exhibit cell membrane permeability and specific staining of cytoplasm. They enter the cells by the mechanism of energy-independent passive diffusion mechanisms. More importantly, complex 7 can act as a two-photon phosphorescent cellular probe, and fluorescence lifetime imaging microscopy is successfully applied for bioimaging in the presence of short-lived background fluorescence. We developed two excellent optical probes for CO2 detection in Chapter 3. The first one for the CO2 detection is a phosphorescent probe based on an iridium(III) complex with 2-phenylimidazo-[4,5-f][1,10]phenanthroline. After bubbling CO2 into the detection solution, the quenched phosphorescence by the addition of CH3COO can be recovered. Photobleaching experiment demonstrates that this phosphorescent CO2 probe shows higher photostability than some of the reported organic probes. More importantly, the time-resolved PL experiment demonstrates that this probe can be used to detect CO2 in the presence of strong background fluorescence, which improves the sensitivity and signal-to-noise ratio of the sensor in complicated media. The second one is a water-soluble fluorescent probe based on tetraphenylethene derivative. After bubbling CO2 into the detection solution, remarkable color change and fluorescence enhancement could be observed. The response of this probe to CO2 in aqueous solution is fast and the detection limit is about 2.4 × 106 M. To emphasize the practical application of this probe, a porous film was successfully fabricated by mixing the dye with sodium carboxymethyl cellulose in water, which can serve as an efficient CO2 gas sensor. More importantly, this probe exhibits low cytotoxicity towards live cells and has the ability to monitor the external CO2 concentration changes of living cells. Chapter 4 focused on the development of novel soft salt based phosphorescent probe. This type of probe consists of two oppositely charged ionic complexes with two distinguishable emission colors, which makes it a perfect candidate as a ratiometric probe. The emission color of 10 changes from blue to red with increasing pH value. 10 is cell-permeable and exhibits low cytotoxicity, and it has been successfully applied for ratiometric pH imaging with the use of confocal microscopy, demonstrating its great potential for intracellular environment monitoring. Furthermore, phosphorescence lifetime imaging experiments can detect intracellular pH variations by photoluminescence lifetime measurements, which allowed for eliminating background fluorescence and selecting long-lived phosphorescence images. Quantitative measurement of intracellular pH fluctuations caused by oxidative stress has been successfully carried out for 10 based on the pH-dependent calibration curve. A series of cationic Zn(II) complexes has been designed and synthesized in chapter 5. The photophysical properties of these Zn(II) complexes are affected by the counterions. By altering the counterions, the emission peak can be changed from 549 nm to 622 nm. Interestingly, the CIE coordinate and the emission colors can be simply tuned by adjusting the concentration of 11d in the polyether. Under an electric field of about 15 V applied onto the electrodes, the emission color of the solution of 11b-11d near the cathode changed its original emission color to sky blue. Based on this interesting electrochromic fluorescence of 11d, a quasi-solid information recording device has been successfully designed. Furthermore, data encryption has been realized by combining 1d with BODIPY, and information decoding processed has been accomplished, for the first time, by employing TPA excitation techniques, in which the large TPA cross section of 11d is differentiated from small TPA cross section of common organic dyes. Finally, Chapters 6 and 7 present the concluding remarksand the experimental details of the work described in Chapters 25

Os polímeros naturais e macromoléculas, como polissacarídeos, gelatina e DNA têm atraído recentemente a atenção significativa da comunidade científica por suas propriedades estruturais e elétricas. O ácido desoxiribonucleico (DNA) possui propriedades eletrolíticas que aumentam quando dissolvido em água, isso ocorre devido à presença de átomos facilmente ionizáveis, tais como prótons e/ou íons sódio. Membranas ionicamente condutoras à base de DNA plastificadas com glicerol/ polietileno glicol (PEG) e contendo polímeros condutores, tais como, PEDOT:PSS (poli (3,4- etilenodioxitiofeno)): poli(estireno sulfonato), POEA (poli (o - etoxianilina)) ou o corante electrocrômico Azul da Prússia (AzP) foram preparadas, caracterizadas e aplicadas em dispositivos electrocrômicos. Os resultados demonstraram que o DNA pode ser plastificado com glicerol, resultando numa membrana transparente com boa condutividade iônica. A caracterização das amostras foi realizada através de medidas de condutividade iônica em função da temperatura, análise termogravimétrica - TGA, análise estrutural por difração de raios-X, microscopia eletrônica - MEV e análise espectroscópica no UV - Vis. Os valores de condutividade iônica à temperatura ambiente foram em gama de 10-4 a 10-5S/cm e aumentam linearmente com o aumento da temperatura, seguindo a relação de Arrhenius. Os valores de condutividade iônica para as membranas dopadas variaram, dependendo do polímero ou corante adicionado, da ordem de 10-5S/cm para as amostras à base de DNA puro a 10-4S/cm para as amostras contendo POEA, PEDOT ou AzP, em temperatura ambiente. Observou-se que as amostras apresentam boa estabilidade térmica, até 170°C, com transparência variável, dependendo da espécie adicionada. Os resultados de raios-X evidenciaram uma estrutura semicristalina das membranas obtidas. Finalmente, as membranas foram aplicadas em pequenos dispositivos electrocrômicos (ECD) e mostraram uma mudança de transmissão de até 10 % de colorido para estados descoloridos. Os dispositivos montados foram caracterizados através de medidas de voltametria e cronocoulometria para os potenciais de (-2,0 e +1,8; e -3,5 e +3,0)V. Os resultados da preparação e caracterização de janelas eletrocrômicas revelaram melhor valor de densidade de carga de 2,8 mC/cm2 para a janela contendo eletrólito a base de DNA-PEDOT. Todos os resultados obtidos mostraram que as membranas à base de DNA são condutoras ionicamente, têm boa transparência e adesão a propriedades do aço e vidro e são materiais promissores para serem aplicadas em dispositivos eletrocrômicos. / Natural polymers and macromolecules such as polysaccharides, gelatin, and DNA have recently attracted significant attention from the scientific community for their interesting structural and electrical properties. Deoxyribonucleic acid (DNA) has electrolytic properties that are enhanced when dissolved in water due to the presence easily ionizable atoms such as proton and/or sodium. Ionically conductive membranes based on DNA plasticized with glycerol and DNA containing conducting polymers, such as, either PEDOT (poly(3,4-ethylenedioxythiophene)), POEA (poly (o-ethoxyaniline)) or electrochromic dye Prussian Blue (PB) were prepared, characterized and applied in electrochromic devices. It has been shown that DNA can be plasticized with glycerol, resulting in a transparent membrane with good ionic conductivity. The characterization of the samples was performed by ionic conductivity measurements as a function of temperature, TGA thermal analysis, and structural analysis by X-ray diffraction, microscopic by SEM and UV-Vis spectroscopic analysis. The ionic conductivity values at room temperature were in range of 10-4 to 10-5S/cm and increases linearly with increasing temperature, following the Arrhenius relationship. The ionic conductivity values for the studied doped membranes varied, depending on the added polymer or dye, from order 10-5S/cm for the pure DNA-based samples to 10-4S/cm for the samples containing PEDOT or PB, at room temperature. It was observed that the samples exhibit a good thermal stability up to 170ºC, with variable transparency, depending on the added molecule. The X-ray results evidenced a semicrystalline structure of the obtained membranes. Finally, the membranes were applied in small electrochromic devices (ECDs) and have shown an up to 10% transmission change from colored to bleached states. The inserted/extracted charges were of 2,8 mC/cm2 after applying potential of -2.0/+1.8V and -3.5/+3.0V on ECD with DNA-PEDOT electrolyte. All obtained results showed that DNA-based ionically conducting membranes have good transparency and adhesion to glass and steel properties and are very promising materials to be applied in electrochromic devices.

Este trabalho apresenta os resultados do preparo e caracterização de janelas eletrocrômicas (ECD) contendo filmes finos de WO3 como camada eletrocrômica, CeO2-TiO2 como contra-eletrodo e eletrólitos a base de polímeros naturais plastificados. Os filmes finos de CeO2-TiO2 e WO3 foram preparados pelo processo sol-gel e usados para montagem de dispositivos (janelas) eletrocrômicas com variados eletrólitos poliméricos. Os filmes finos e as janelas foram caracterizados através de medidas de densidade de carga, voltametria cíclica e transmitância. Os filmes de CeO2-TiO2 e WO3 apresentaram respectivamente, valores de densidade de carga de 11,8 e 27,8 mC/cm2, e razão de carga anódica/catódica de 0,98 e 0,85. As análises voltamétricas dos filmes finos revelaram picos característicos dos processos de oxidação e redução e as análises espectroscópicas a transmitância de 80 e 78 %, respectivamente. Foram preparadas e caracterizadas janelas com eletrólitos a base de gelatina com ácido acético; gelatina com LiI/I2; gelatina com agar; gelatina com líquidos iônicos; gelatina com líquidos iônicos e triflato de európio; poli(vinil butirato) (PVB) com LiI/I2; PVB com LiClO4; agar com LiClO4; agar com líquidos iônicos; DNA; DNA com LiClO4; DNA-cloreto de hexadeciltrimetilamônio (DNA-CTMA) com azul da Prússia; DNA com PEDOT:PSS (poli(3,4-etilenodioxitiofeno):poli(sulfonato de estireno)); DNA-CTMA com PEDOT:PSS. Os melhores resultados de densidade de carga de 5,4 e 6,0 mC/cm2 foram obtidas para os dispositivos com eletrólitos de gelatina com agar e agar com LiClO4. A razão de carga anódica/catódica desses dispositivos foi de 0,98 e 0,99. Os voltamogramas cíclicos das amostras estudadas revelaram picos anódicos e catódicos referentes à extração e inserção de íons lítio e elétrons no filme de WO3. As análises de transmitância em 550 nm entre o estado colorido e descolorido das janelas mostrou os valores de 28% para a janela contendo eletrólito a base de PVB com LiI/I2. Além disso, também foi verificada a estabilidade dos dispositivos revelando a duração entre 100 a 400 ciclos cronoamperometricos, dependendo do eletrólito usado. Os resultados obtidos mostram que as janelas estudadas são potenciais candidatas às aplicações práticas. / This work presents the results of the preparation and characterization of electrochromic windows (ECD) containing thin films of WO3 as electrochromic layer, CeO2-TiO2 as the counter electrode and natural polymer-based electrolytes. Thin films of CeO2-TiO2 and WO3 were prepared by the sol-gel process and used to assembly the electrochromic devices (windows) with different polymer electrolytes. The thin films and windows samples were characterized by charge density, cyclic voltammetry and transmittance measurements. CeO2-TiO2 and WO3 thin films revealed charge density values of 11.8 and 27.8 mC/cm2, and anodic/cathodic charge relation of 0.98 and 0.85, respectively. The cyclic voltammograms revealed the peaks characteristic of the processes of oxidation and reduction and the spectroscopic analysis the transmittance of 80 and 78%, respectively. Electrochromic windows were assembled with electrolytes based on gelatin with acetic acid; gelatina with LiI/I2, gelatin with agar, gelatin with ionic liquids, gelatin with ionic liquids and europium triflate, PVB (poly (vinyl butyrate)) with LiI/I2; PVB with LiClO4; agar with LiClO4, agar with ionic liquids; DNA, DNA with LiClO4; DNA-CTMA (hexadecyltrimethylammonium chloride) with Prussian Blue; DNA with PEDOT:PSS (poly (3,4-ethylenedioxythiophene) poly(styrene sulfonate) ) and DNA-CTMA with PEDOT: PSS. The best results of charge density of 5.4 and 6.0 mC/cm2 and anodic/cathodic charge relations of 0.98 and 0.99 were obtained for the samples containing electrolytes based on gelatin with agar and agar with LiClO4, respectively. The cyclic voltammograms of the electrochromic windows showed cathodic and anodic peaks related to the insertion and extraction of lithium ions and electrons in the film of WO3. The transmittance measurements at 550 nm revealed 28% between the colored and discolored state of the windows with PVB-LiI/I2 electrolyte. Moreover, the stability measurements showed that the ECD remain their transmittance difference during of 100 to 400 of chronoaperometric cycling, depending on the electrolyte used. The obtained results indicate the possibility of use the naturalmacromolecules-based electrolytes in practical electrochromic windows.