No description available.

In this study, P3HT and PCBM were used as donor and acceptor materials for polymer solar cells. The standard device was constructed of ITO / PEDOT:PSS / P3HT:PCBM / Al and the power conversion efficiency of 2% was achieved under AM1.5G 100mW/cm2 illumination. In order to increase the hole transporting ability, we used PEDOT nanorods with high conductivity as an anode interlayer between the PEDOT:PSS and the P3HT:PCBM layer, with a configuration of ITO / PEDOT:PSS / PEDOT nanorods / P3HT:PCBM / Al. According to experimental results. PEDOT nanorods dispersed well on the PEDOT:PSS surface through the spin-coating process. As the concentration of PEDOT nanorods 1wt% casting film, the conductivity of anode buffer layer raised about two times and the power conversion efficiency of device reached 2.63%. The short-circuit current and the power conversion efficiency of the polymer solar cell containing 1wt% PEDOT nanorods were obtained about 170% and 30% increasement, respectively. In conclusion, it is quite useful to apply the PEDOT nanorods into polymer solar cells as an interlayer. The improvement in the short-circuit current which resulted in an enhancement of the power conversion efficiency originated from the increased conductivity of the buffer layer.

Organic solar cells have emerged as an important cheap photovoltaic technology. In this thesis work, a study of P3HT:PCBM heterojunction solar cells was presented. By incorporation of photo-active film slow growth, PEDOT:PSS (Poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate)) de-water treatment and application of highly conductive PEDOT:PSS (HC-PEDOT), a maximum PCE (power conversion efficiency) of 4% was achieved. Inkjet printing technique was on the other hand introduced into fabrication process. The morphological, electrical and optical properties of printed HC-PEDOT were investigated. Fine silver girds with well-designed pattern, combining with a transparent thin film of HC-PEDOT, was inkjet-printed to form the anode of solar cells. A functional device with printed anode and printed photo-active layer was demonstrated, showing the possibility of realizing fully printed organic solar cells.

<p>Organic solar cells have emerged as an important cheap photovoltaic technology. In this thesis work, a study of P3HT:PCBM heterojunction solar cells was presented. By incorporation of photo-active film slow growth, PEDOT:PSS (Poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate)) de-water treatment and application of highly conductive PEDOT:PSS (HC-PEDOT), a maximum PCE (power conversion efficiency) of 4% was achieved.</p><p>Inkjet printing technique was on the other hand introduced into fabrication process. The morphological, electrical and optical properties of printed HC-PEDOT were investigated. Fine silver girds with well-designed pattern, combining with a transparent thin film of HC-PEDOT, was inkjet-printed to form the anode of solar cells. A functional device with printed anode and printed photo-active layer was demonstrated, showing the possibility of realizing fully printed organic solar cells.</p><p> </p>

Li-ion batteries are currently the most efficient technology available for electrochemical energy storage. The technology has revolutionized the portable electronics market and is becoming a corner stone for large scale applications, such as electric vehicles. It is therefore important to develop materials in which the energy storage relies on abundant redox active species, such as iron. In this thesis, new iron based electrode materials for positive electrodes in Li-ion batteries were investigated. Lithium iron pyrophosphate (Li2FeP2O7) and two polymorphs of lithium iron sulphate fluoride (LiFeSO4F) were studied. For Li2FeP2O7, preferred oxidation of iron with different coordination numbers within the crystal structure was studied, and six-coordinated iron was found to be oxidized preferentially at lower potentials compared to five‑coordinated iron. Electrochemical cycling resulted in structural changes of Li2FeP2O7 through an increased Li-Fe mixing in the compound, forming a metastable state during battery operation. For tavorite LiFeSO4F, the influence of the amount of a conductive polymer (poly(3,4-ethylenedioxythiophene), or PEDOT) was studied. All the different amounts of PEDOT coating reduced the polarization significantly, but the trade-off between functionality and weight added also has to be considered. Additionally, the effect of densifying the electrodes to different degrees is reported, and was found to have a significant influence on the battery performance. Also triplite LiFeSO4F was coated with PEODT, and it was found that the electrochemical performance improved, but not to the same extent as for tavorite LiFeSO4F. The faster solid state transport of Li-ions in tavorite type LiFeSO4F possibly accounts for the difference in electrochemical performance. Together, the results presented herein should be of importance for developing new iron based materials for Li-ion batteries. / Av de idag tillgängliga teknologierna för elektrokemisk energilagring så har litium-jonbatterier de bästa egenskaperna när det gäller energiförluster och energilagringskapacitet. De har revolutionerat marknaden för portabel elektronik (telefoner, laptops etc.), och blir mer och mer viktiga för storskaliga tillämpningar såsom elbilar. För den typen av applikationer måste teknologin baseras på vanligt förekommande material och grundämnen, t.ex. järn. I den här avhandlingen har järnbaserade material för den positiva elektroden hos litium-jonbatterier studerats. Olika aspekter som påverkar spänningen och effektiviteten hos elektroderna har undersökts. Ett exempel på det är hur olika omgivningar kring järnatomerna i en förening påverkar spänningen hos ett batteri. För föreningen litiumjärnpyrofosfat visade det sig att sex närmaste grannar ger lägre spänning än fem närmaste grannar till järn. Dessutom har förändringar i föreningens struktur studerats då den används i ett batteri. Den här typen av grundforskning är viktig för förståelsen av nya elektrodmaterial i Li-jonbatterier. Ur en mer praktisk synvinkel så har elektroder baserade på en annan järnförening, litiumjärnsulfatfluorid, utvecklats. Ledningsförmågan hos dessa elektroder har förbättrats genom att belägga föreningen med ett ledande skikt, samt att mekaniskt pressa samman elektroderna genom mangling. Båda metoderna är viktiga för att tillverka välfungerande elektroder. Föreningen litiumjärnsulfatfluorid förekommer i två olika former, och en jämförelse av hur elektriskt ledande beläggningar påverkar de bägge materialen har också gjorts i den här avhandlingen. Tillsammans visar resultaten från de olika studierna på hur man kan arbeta och tänka kring utvecklingen av nya material för litium-jonbatterier.

Organic electrode materials, as sustainable and environmental benign alternatives to inorganic electrode materials, show great promise for achieving cheap, light, versatile and disposable devices for electrical energy storage applications. Conducting redox polymers (CRPs) are a new class of organic electrode materials where the charge storage capacity is provided by the redox chemistry of functional pendent groups and electronic conductivity is provided by the doped conducting polymer backbone, enabling the production of energy storage devices with high charge storage capacity and high power capability. This pendant-conducting polymer backbone combination can solve two of the main problems associated with organic molecule-based electrode materials, i.e. the dissolution of the active material and the sluggish charge transport within the material. In this thesis, diethyl terephthalate and polythiophenes were utilized as the pendant and the backbone, respectively. The choice of pendant-conducting polymer backbone combination was based on potential match between the two moieties, i.e. the redox reaction of terephthalate pendent groups and the n-doping of polythiophene backbone occur in the same potential region. The resulting CRPs exhibited fast charge transport within the polymer films and low activation energies involved charge propagation through these materials. In the design of these CRPs an unconjugated link between the pendant and the backbone was found to be advantageous in terms of the polymerizability of the monomers and for the preservation of individual redox activity of the pendants and the polymer chain in CRPs. The functionalized materials were specifically designed as anode materials for energy storage applications and, although insufficient cycling stability was observed, the work presented in this thesis demonstrates that the combination of redox active functional groups with conducting polymers, forming CRPs, shows promise for the development of organic matter-based electrical energy storage materials.

The human brain is an extraordinarily complex organ. The process of neurotransmission gives rise to sensory experience, cognition, and decision-making. Many common diseases of the brain are incurable and their symptoms are poorly treated. To better understand the underlying molecular problems in disease states, sensitive, selective, and rapid measurements of biomolecules are needed. Given the complexity of making biological measurements in vitro or in vivo, inquiring scientists must choose measurement tools wisely. While traditional electrode materials have been used to great success, conducting polymers such as PEDOT are an excellent way to modify or improve existing measurement tools. The chemical, spatial, and temporal resolution of in vivo and in vitro measurements can be improved, all while increasing the longevity of the sensor. Compared to existing electrode materials, PEDOT is amenable to a larger variety of substrates, easier to process, inexpensive, and has excellent electrochemical behavior for the detection of neurotransmitters. We have demonstrated the utility of PEDOT by fabricating and characterizing the first device for the separation of biogenic amines, and the first device for high-throughput measurements of exocytosis from single PC12 cells. These devices will allow scientists to inexpensively and rapidly study the effects of pharmacological challenges to model systems in disease states. A PEDOT and Nafion composite polymer coating has been developed for microelectrodes, granting increased sensitivity and selectivity towards dopamine. These improvements resulted in the first in vivo electrochemical measurements of dopamine transients without administration of a reuptake inhibitor. Lastly, we have expanded the chemistry of polythiophenes by developing the synthesis of oligo-EDOT:Nafion nanoparticles. These nanoparticles are easily prepared, inexpensive, and enable quantiative spectroscopic interrogations of water content in organic solvents.

Organic conducting polymer, poly(3,4-ethylene dioxythiophene)-poly(styrene sulfonate) (PEDOT:PSS), is widely recognized for its electro-actuation mechanism and is used in flexible electronics. Its high potential as actuator is based on a strong coupling between chemical, mechanical and electrical properties which directly depends on external stimuli. There is no model today to describe the interplay between moisture absorption, mechanical expansion and electrical stimulus. Elucidating the role of each component in the effective actuation properties is needed to further optimize and tailor such materials. The objective of this thesis is to develop a macroscopic model to describe water sorption kinetics of the PEDOT:PSS film. We used gravimetric analysis of pure PEDOT:PSS film of three different thicknesses to investigate absorption kinetics over a broad range of temperatures and relative humidity. Our results revealed that the moisture uptake of PEDOT:PSS film does not follow Fickian diffusion law due to the retained amount of water after desorption process. We used an existing diffusionreaction model to describe this behavior, and COMSOL Multiphysics and MATLAB software programs to implement it. We observed that the generic model we used in our work could predict polymer behavior with 95% accuracy. However, our model was not able to properly represent the data at very high relative humidity at low temperature, which was attributed to the excessive swelling of the film. Also, we examined a relation between the moisture content of PEDOT:PSS and its mechanical strain and electrical conductivity. The results presented here are the first step towards a general multiphysics electro-thermo-mechanical description of PEDOT:PSS based actuators.

No description available.

L’électrochromisme est le changement réversible de couleur d’un matériau lors de son oxydation ou de sa réduction électrochimique. Cette thèse porte sur l’étude d’électrolytes à base de liquide ionique (BMIPF6 et BMITFSI), de sel de lithium (LiTFSI) et de polymère (PMMA) et sur la préparation de systèmes électrochromes à base de ces électrolytes et du PEDOT, du Bleu de Prusse ou d'InHCF comme matériaux électrochromes. La conduction ionique mesurée par EIS, les analyses thermo gravimétriques, les spectroscopies IR et Raman et la mesure des coefficients de diffusion informent sur les interactions entre les espèces dans l'électrolyte. Les matériaux électrochromes (PEDOT, BP, InHCF) sont ensuite étudiés dans un électrolyte modèle LiTFSI 0.03 / BMITFSI 0.97. Enfin, des systèmes électrochromiques flexibles sont réalisés et leur propriétés de coloration et de cyclage étudiées. / Electrochromism is the reversible colour change of a material upon electrochemical oxidation or reduction. This thesis will focus on the study of ionic liquid (BMIPF6 and BMITFSI), lithium salt (LiTFSI) and polymer (PMMA) based electrolytes and on the preparation of electrochromic devices with PEDOT, Prussian Blue or one of its analogues InHCF, as electrochromic materials. The measurement of ionic conductivity by EIS, thermo-gravimetric analysis, IR and Raman spectroscopy and measurement of diffusion coefficients of these electrolytes highlight the interactions between the different species of the electrolyte. Electrochromic materials (PEDOT, BP, InHCF) are then studied in a model electrolyte (LiTFSI 0.03 / 0.97 BMITFSI), their electrochromic properties are detailed. Finally, flexible electrochromic devices are made and their properties of colouration and cycling are presented.