The interest in conjugated polymers has been two-fold. A rich variety of intriguing physical phenomena, combined with its immense technological implications in the area of molecular electronics, sensors etc. has inspired the researchers all over the globe. The work presented in this thesis is focussed on one of the most widely studied conjugated polymers, namely polyaniline (PANI), which is well known for its high conductivity and remarkable stability in the proton-doped form. The thesis is divided into two chapters and each chapter is further divided into several parts. In the first chapter, we take a look at some novel systems based on PANI that exhibit interesting electrical and optical properties. To begin with, we report the synthesis and characterization (Part I, Chapter 3) a new class of highly conducting polyaniline doped with electron deficient Lewis acids, namely the boron trihalides (BX3, X = F, Cl, and Br). We discuss the various attributes of this interesting class of materials that set it apart from the conventional proton-doped PANI systems. It is known that the conductivity in doped PANI is greatly influenced by the presence of structural disorder. Previous studies have associated the conductivity in doped PANI with the partial crystallinity that is achieved upon proton doping. At the same time, the amorphous regions that have a high degree of disorder were believed to suppress the metallic nature in these doped systems. In view of this "higher-crystallinity-higher-conductivity" picture, it is interesting to note that the BX3 doped PANI remain absolutely amorphous despite being more conducting than previously known samples. Through our investigation, we have been able to address some of the most important and long-standing questions pertaining to the nature of the charge carriers and the role of disorder in doped PANI. A detailed study of the transport properties in Part II, Chapter 3 helps us to understand the mechanism of charge transfer in these novel systems. With the help of our results, we establish that the present systems do not belong to the family of quasi one-dimensional conductors, in stark contrast to the conventional proton-doped samples. Instead, our systems are best described as granular metals, where the conduction mechanism is controlled by the size of the conducting grains and the nature of the grain boundaries. Through a comprehensive study of the magnetic properties based on d. c. magnetic susceptibility and EPR spectroscopy, we further establish that the intrinsic conductivity of these samples are much higher than the previously known systems. By studying the interaction of the mobile charge carriers and the localized spins in the systems, we have established that our samples are far less disordered, and therefore qualify as superior systems when compared to the more conventional proton-doped PANI. One of the serious disadvantages of the conventional protonated PANI lies in its thermal instability. On heating above 75 ±C in air, the polymer backbone undergoes an irreversible aerial oxidation that disrupts the extended conjugated structure. This is marked by a rapid drop in conductivity by a few orders of magnitude. BF3-doped PANI, which has the highest conductivity sample among the present series of samples, exhibits a remarkable thermal stability in air (Part III, Chapter 3). Upon heating, the conductivity initially increases and then reaches a saturation value. The polymer can be heated at temperatures as high as 225 ±C, without any signs of degradation. With the help of temperature dependent conductivity, XPS and FTIR spectroscopy we have tried to understand this unexpected phenomenon. In Part IV, Chapter 3, we report the synthesis and characterization of a novel class of functionalized PANI that exhibit an intense deep-blue photoluminescence. A de- tailed characterization based on absorption, photoluminescence, XPS, NMR and FTIR spectroscopy has been carried out to study the chemical state of this new class of light- emitting polymers. Further, we note that the synthetic procedure followed in this work can provide a very general route to the synthesis of diversely useful derivatives of PANI. In Chapter 4, we have investigated the microscopic origin of conductivity in doped PANI. Among the several factors that can influence the conductivity of doped polymers, one is the microstructural order. To understand this better, we carried out a detailed investigation, based on scanning tunneling microscopy (STM) and spectroscopy (STS) of undoped and doped PANI films (Part I, Chapter 4). We have shown for the ¯rst time that solution processed thin films of undoped PANI has an abundance of PANI anorods self organized over very large areas. Further, we observe that this ordered orphology is Preface vii very sensitive to the choice of dopants and the doping procedure. We have shown that the morphological order can greatly influence the electronic structure and therefore the properties of these systems. To understand the role of dopant-polymer interaction in controlling the conductivity of doped PANI, we carried out x-ray photoelectron spectroscopy (XPS) studies on a large number of partially and fully doped samples (Part II, Chapter 4). We find an interesting trend in the higher binding energy feature and the asymmetry of the N and C 1s spectra, which correlates directly with the respective conductivities of different samples. The analysis of these spectra brings out interesting facts about the chemical state and the electronic structure of these samples. In summary, we have reported new PANI based systems with improved electrical and interesting optical properties, and have studied various factors that influence the properties of these as well as some of conventional doped PANI systems.

<p>All conducting polymers are potentially electrochromic, owing to the injection of charge carriers that changes their electronic structure and results in a shift of their optical absorption towards higher wavelengths. PEDOT-PSS and PEDOT-S are very promising materials in terms of electrochromic properties, due to the good contrast existing between their doped and undoped forms. However this contrast has to be enhanced in order to design more efficient electrochromic devices, and new solutions should thus be found in order to solve this issue.</p><p>Surface plasmons are described as electromagnetic waves propagating along the surface between a dielectric and a metal. Coupled to an incident radiation, they create an energy loss in the light transmitted and reflected by the interface. When the metallic surface is periodically corrugated, this absorption phenomenon due to plasmonic resonance occurs at a specific wavelength that depends on several parameters, such as the incidence angle, the dielectric constants of the two media and the grating period. By coating metallic gratings with electrochromic polymers, we may thus be able to trigger a plasmonic absorption at a given wavelength and shift it upon reduction or oxidation of the material.</p><p>Electrochromic devices consisting of PEDOT-PSS or PEDOT-S spin-deposited on gold and silver gratings were investigated by UV-visible reflectance measurements. The periodically corrugated structures were reproduced from commercial gratings by soft nanolithography and were analyzed by AFM. Some electrochromic cells exhibited new colors or a high shift of the plasmonic resonance upon redox switching of the polymer film. Depending on the step and the nature of the grating employed, this shift could reach 20 nm in the case of PEDOT-PSS and more than 100 nm for PEDOT-S. A theoretical model was found to predict the wavelength of plasmonic excitation and the orientation of the shift.</p>

Thesis (D.M.A.)--University of Illinois at Urbana-Champaign, 2007. / Includes abstract. Vita. Source: Dissertation Abstracts International, Volume: 69-02, Section: A, page: 0433. Adviser: Chester L. Alwes. Includes bibliographical references (leaves 137-144) and discography (leaves 127-130). Available on microfilm from Pro Quest Information and Learning.

The electrical conductivity of transparent conducting oxides is well exploited in front surface electrodes for solar cells where high transmission is also important. Fluorine doped tin oxide (SnO2: F) is the most popular choice of front contacts for CdTe solar cells. In this thesis, Cd2SnO4 and Zn2SnO4 thin films are investigated focusing on their electrical and optical properties and used them in solar cells. Processing for these materials is optimized for optimum solar cell performance. Cd2SnO4 thin films are deposited by co-sputtering of CdO and SnO2 targets in Ar ambient at room temperature. Then films are subjected to high temperature annealing in He ambient. The films crystallize in inverse spinel structure. The average transmission of a Cd2SnO4 thin film with a thickness of 2500[angstrom] obtained in this study is 92%. The lowest resistivity obtained in this work for a Cd2SnO4 film with a thickness of 2500[angstrom] is 5.4 X10-4 cm. The effect of stoichiometry on structure, optical and electrical properties of Cd2SnO4 is studied by varying the amount of CdO and SnO2 in the Cd2SnO4 film. Zinc stannate thin films are deposited by co-sputtering of ZnO and SnO2 targets in Ar ambient at both room temperature and elevated temperatures. As deposited and high temperature annealed Zn2SnO4 thin films are highly resistive. The average transmission of a Zn2SnO4 thin film with a thickness of 2000[angstrom] and annealed at 600ʻC in He has been 94%. Zn2SnO4 thin films are incorporated as a buffer layers into CdTe solar cells. SnO2: F is used as a front contact in CdTe solar cells in conjunction with high resistive Zn2SnO4 buffer layer.The best SnO2:F /zinc stannate cell device performance for room temperature deposited zinc stannate film resulted for the device with Zn/Sn =2.1. It has an efficiency of 12.43% with VOC = 810mV, FF = 66.6% and JSC = 23.1 mA.

Presently there are deep concerns over the environmental consequences and the consumption of non-renewable energy sources, with the accelerated greenhouse effect, triggered enormous interest in the use of renewable energy sources e.g., solar, hydropower, wind and geothermal. However the intermittent nature of harvesting renewable energy sources has recently gained considerable attention in the alternative reliable, cost effective, and environmentally friendly energy storage devices. The supercapacitor and lithium ion batteries are considered more efficient electrical energy storage devices than conventional energy storage systems. Both devices have many useful and important applications; they could be an excellent source for high power and high energy density, especially in portable electronic devices and Electrical Vehicles (EVs) or Hybrid Electrical Vehicles (HEVs). In order to make the efficient usage of these stationary energy storage devices, state of the art research on new and advanced electrode materials is highly needed. The aim of this dissertation is to investigate the scope of graphene/metal oxide-conducting polymer nanocomposites electrodes for light weight, high power density and wider voltage window supercapacitor devices. The facile chemical polymerization approach was used to synthesize the aromatic and heterocyclic conducting polymer nanocomposites. For aromatic nanocomposites, several materials were synthesized includes ZnO-PANI, ZnO/G-PANI,RuO2-PANI and G-PANI. Subsequently these materials have been characterized by physical, structural techniques e.g Raman Spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), Xray-Diffraction (XRD), Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy (TEM). In addition to material characterization the prepared material was also characterized by electrochemical measurements using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and chrono potentiometry for supercapacitor electrodes. Since graphene is a two-dimensional single-atom-thick sp2 hybridized carbon structure due to its extraordinary characteristic, high electrical conductivity, chemical stability and large theoretical surface area (over 2600 m2 g−1) has gained immense interest in the future generation of renewable energy devices. Therefore, among all aromatic based nanocomposites, the Graphene-Polyaniline (G-PANI) rendered promisingly high specific capacitance around 440 F/g with the excellent cyclic stability. The higher specific capacitance of G-PANI might be due to the high conductivity and superior electrochemical properties of graphene in G-PANI nanocomposites. However, besides the G-PANI, other aromatic nanocomposites e.g., RuO2-PANI, ZnO-PANI and G/ZnO-PANI also showed the potential of low cost and flexible supercapacitor electrodes with the reasonably good specific capacitance as 360 F/g, 300 F/g, and 275 F/g. We have further investigated the role of conductivity by adding different amount of graphene in G-PANI nanocomposites to optimize device performance with the specific capacitance and columbic efficiency of 440 F/g and 90% respectively.Further the other important parameters, relate with the electrode thickness, type of electrolytes, concentration of electrolytes and the effect of the solvent has also been studied to achieve the overall performance and reliability of the device. Moreover, in order to have the comprehensive study of conducting polymer besides the aromatic conducting polymer the heterocyclic polymers e.g., polythiophene and poly (3, 4-ethylenedioxythiophenes) (PEDOT) nanocomposites were studied at length to evaluate their role for the cost effective, large surface area and flexible green energy storage devices and has shown great prospects for commercial application. Therefore, G-Cps nanocomposites have proved to be a promising electrode material choice to facilitate the ionic diffusion and contact of the electrolytes to improve the specific capacitance and performance of the device.

Conducting metallopolymers have been investigated for a variety of applications due to their ability to take advantage of both the mechanical processability of the polymer material, as well as the optical and electronic properties of the metal. Our project goal is to design, synthesize and characterize novel iridium(III)-containing conducting metallopolymers for use as the active layer in polymer light-emitting diodes. We have utilized thiophene functionalized ligands that can be readily electropolymerized into conducting polymer thin films and can be easily incorporated into a device structure. Iridium(III) was chosen as the metal center due to its promising photophysical properties, as similar complexes have demonstrated high luminescent quantum yields and short phosphorescent lifetimes. The coordination environment around the metal can be altered synthetically to tune the emission wavelength across the visible spectrum. The synthetic control over the polymer backbone, as well as the iridium(III) ligand environment, allowed us to independently vary each component, which has provided a variety of materials. The materials are characterized through 1H and 13C NMR, mass spectrometry, elemental analysis, electrochemistry, X-Ray diffraction and X-Ray Photoelectron Spectroscopy. The photophysical properties of the materials are studied through UVvii Visible absorption spectroscopy, UV-Vis-NIR spectroelectrochemistry and steadystate/ time-resolved emission spectroscopy. / text

Tidigare forskning inom intensivvårdsområdet har visat att ej adekvat utförd munvård kan leda till allvarliga livshotande sjukdomar. Det är av därför av vikt att munvård utförs enligt gällande rekommendationer och följer evidensbaserad forskning. Syftet var att identifiera intensivvårdssjuksköterskans beskrivning av tillvägagångssätt, delaktighet och dokumentation vid utförande av munvård hos patienter inneliggande på IVA. En kvantitativ ansats valdes med målsättning att göra en undersökning med hjälp av enkätfrågor. Inklusionskriterier var specialistutbildade sjuksköterskor inom intensivvård som tjänstgjorde på tre intensivvårdsavdelningar i västra Sverige under aktuell studieperiod. Sammanlagt distribuerades 182 enkäter och 103 svar erhölls vilket gav en svarsfrekvens på 60 %. Resultatet visade att munvård var en prioriterad omvårdnadsåtgärd på avdelningarna och tillvägagångssättet följde till stor del fastställda riktlinjer. Det framkom att i begreppet munvård ingick huvudsakligen inspektion av munhålan, mekanisk rengöring, fuktning av slemhinna och läppar, inspektion av tänder och tandkött samt sugning av munhåla och svalg. De verktyg som huvudsakligen användes var tandborste, muntork eller liknande samt antibakteriellt medel. Ett signifikant samband förekom vad gäller sjuksköterskans delaktighet vid utförande av munvård hos intuberade patienter jämfört med övriga patienter (p=0,02). Detta ansågs vara en mer komplex omvårdnadsåtgärd vilken krävde samarbete med övriga medarbetare. Munvård delegerades ofta till undersköterskor men det är dock sjuksköterskans uppgift att leda och ansvara för omvårdnaden.  Dokumentation vad gäller munvård utfördes i de flesta fall på en observationskurva. Ett mindre antal sjuksköterskor angav att dokumentation även utfördes i datajournal. Ett flertal sjuksköterskor angav att dokumentation dessutom utfördes på interna checklistor. Det framkom att flera sjuksköterskor dokumenterade i datajournal enbart vid avvikelser eller om komplikationer tillstött. / Previous studies in the intensive care areas have shown that inadequate oral care may predispose patients to life-threatening diseases and conditions. The role of oral hygiene in maintaining the health of patients in the ICU is indisputable and therefore the importance of oral care evidence-based clinical recommendations. The purpose of this study was to identify the intensive care nurses description of the conducting, participation and documentation of oral care performed by nurses on patients in ICUs. A quantitative study with a describing design has been used which is based on the statistical analysis of data collected by structured questionnaires. The inclusion criteria were nurses working in three ICUs located in West Sweden during the study period. One hundred eighty-two questionnaires were distributed and replies were received from 103 nurses which gave a response rate of 60%. The result showed that the oral care conducted followed the evidence-based clinical recommendations and was given a high priority. The majority of the nurses performed an oral assessment before beginning oral care which included inspection of the oral cavity and inspection of teeth and gum. Oropharyngeal suction and moisturizing of lips and the mucosal membrane was also included. The most common used equipment was toothbrushes and foam swabs. Chlorhexidine was the most common solution used. A significant correlation was observed regarding nurse participation when conducting oral care for an intubated patient compared to other patients (p=0,02). Intubated patients were considered having more complex oral care needs which were associated with the demand of more than one person providing oral care. In practice, nurses frequently delegate the conducting of oral hygiene to nursing assistants, but the law clearly describes the role of the nurse as responsible and the leader of care practices. Oral care was in most cases documented on the unit’s flow sheet. A fewer number of nurses commented on that oral care was documented in the electronical clinical journal. A considerable   number of nurses also indicated that oral care in addition was documented on the unit’s internal checklists. It appeared that several nurses used the electronical clinical journal in cases only when abnormalities or complications had occurred.

A novel lithographic fabrication method is used to fabricate nanopillars arrays of anisotropic Ag and TCO electrodes. Optical and electrical properties of the electrodes including bandgap, free carrier concentration, resistivity and surface plasmon frequency of different electrodes can be tuned by adjusting the dimensions and geometry of the pillars. Given the ability to tune the nonlocal responses of the plasmonic field enhancements, we attempt to determine the nature of the effective refractive index profile within the visible wavelength region for multi-layer hybrid nanostructures. Knowledge of the effective optical constants of the obtained structure is critical for various applications. nanopillars of TCO\Ag core shell structures have been successfully fabricated. The Maxwell-Garnett mixing law has been used to determine the optical constants of the nanostructure based on spectroscopic ellipsometry measurements. Simulated reflection spectra indicate a down shift in the Brewster angle of the pillars resulting from the reduction in the effective refractive index of the nanostructure. Two plasmonic resonances were observed, with one in the visible region and the other in the IR region. Plasmon hybridization model is used to describe the behavior of metal and metal oxide core shell nanostructured electrodes. Different charge density distributions around the pillars determine the plasma frequency which depends on the core and surrounding media dielectric constants. Finite Difference Time Domain (FDTD) simulation of different structures agree well with experiment and help us to understand electric field behavior at different structures with different geometries and dielectric constants. Plasmonic Ag nanopillar arrays are effective substrates for surface enhanced Raman spectroscopy (SERS). An enhancement factor up to 6 orders of magnitude is obtained. Monolayers of C60 is deposited on the Ag nanopillars and the interface of C60/Ag is studied which is important in optoelectronic devices. Electron delocalization between C60 and Ag is confirmed.

Many organic electronic and bioelectronics devices rely on mixed (electronic and ionic) transport within a single organic layer. Although electronic transport in these materials is relatively well understood, a fundamental understanding of ion transport is missing. I developed a simple analytical model that describes ion transport in a planar junction between an electrolyte and a conducting polymer film. The model leads to predictions of the temporal evolution of drift length of ions and current. These predictions are validated by numerical simulations and by using realistic parameters, I show that the analytical model can be used to obtain the ion mobility in the film. Furthermore, I developed an experimental method which allows the application of the analytical model and leads to a straightforward estimation of the ion drift mobilities in conducting polymers. PEDOT:PSS was found to support efficient transport of common ions, consistent with extensive swelling of the film in water. Crosslinking the film decreased its swelling and the ion mobility. Understanding the high correlation of hydration and ionic conductivity enables us to engineer materials with high and defined ion mobilities. As an example tuning of ion mobility by adjusting the relative ratio of the hydroscopic phase to PEDOT:TOS is presented. Finally I performed electrochemical impedance spectroscopy during a moving front experiment, in order to give a physical interpretation of the impedance spectra at a conducting polymer/electrolyte junction.

No description available.