abstract: In this thesis, an approach to develop low-frequency accelerometer based on molecular electronic transducers (MET) in an electrochemical cell is presented. Molecular electronic transducers are a class of inertial sensors which are based on an electrochemical mechanism. Motion sensors based on MET technology consist of an electrochemical cell that can be used to detect the movement of liquid electrolyte between electrodes by converting it to an output current. Seismometers based on MET technology are attractive for planetary applications due to their high sensitivity, low noise, small size and independence on the direction of sensitivity axis. In addition, the fact that MET based sensors have a liquid inertial mass with no moving parts makes them rugged and shock tolerant (basic survivability has been demonstrated to >20 kG). A Zn-Cu electrochemical cell (Galvanic cell) was applied in the low-frequency accelerometer. Experimental results show that external vibrations (range from 18 to 70 Hz) were successfully detected by this accelerometer as reactions Zn→〖Zn〗^(2+)+2e^- occurs around the anode and 〖Cu〗^(2+)+2e^-→Cu around the cathode. Accordingly, the sensitivity of this MET device design is to achieve 10.4 V/G at 18 Hz. And the sources of noise have been analyzed. / Dissertation/Thesis / Masters Thesis Electrical Engineering 2015

This thesis explores a rigorous approach to model the behaviour of an electrochemical cell. A simple planar electrochemical cell consisting of stainless steel electrodes separated by a sulfuric acid electrolyte layer is modeled from first principles. The model is a dynamic model and is valid under constant temperature conditions. The dynamic model is based on the Poisson-Nernst-Planck electrodiffusion theory and physical attributes such as the impact of nonlinear polarization, the stoichiometric reactions of the electrolyte and changes to the transport coefficients are investigated in stages. The system of partial differential equations has been solved using a finite element software package. The simulation results are compared with experimental results and discrepancies are discussed. The results suggest that the existing theory is not adequate in explaining the physics in the immediate vicinity of the electrode/electrolyte interface even though the general experimental and simulation results are in qualitative agreement with each other.

This thesis explores a rigorous approach to model the behaviour of an electrochemical cell. A simple planar electrochemical cell consisting of stainless steel electrodes separated by a sulfuric acid electrolyte layer is modeled from first principles. The model is a dynamic model and is valid under constant temperature conditions. The dynamic model is based on the Poisson-Nernst-Planck electrodiffusion theory and physical attributes such as the impact of nonlinear polarization, the stoichiometric reactions of the electrolyte and changes to the transport coefficients are investigated in stages. The system of partial differential equations has been solved using a finite element software package. The simulation results are compared with experimental results and discrepancies are discussed. The results suggest that the existing theory is not adequate in explaining the physics in the immediate vicinity of the electrode/electrolyte interface even though the general experimental and simulation results are in qualitative agreement with each other.

The aim of this thesis is to enhance the extracellular electron transfer rates (exoelectrogenesis) in cyanobacteria, to be utilised for photo-bioelectricity generation in biophotovoltaics (electrochemical cell). An initial cross comparison of the cyanobacterium Synechococcus elongatus PCC7942 against other exoelectrogenic cultures showed a hindered exoelectrogenic capacity. Nonetheless, in mediatorless biophotovoltaics, it outperformed the microalgae Chlorella vulgaris. Furthermore, the performance of S. elongatus PCC7942 was improved by constructing a more efficient design (lower internal resistance), which was fabricated with carbon fibres and nitrocellulose membrane, both inexpensive materials. To strategically obtain higher exoelectrogenic rates, S. elongatus PCC7942 was conditioned by iron limitation and CO2 enrichment. Both strategies are novel in improving cyanobacteria exoelectrogenesis. Iron limitation induced unprecedented rates of extracellular ferricyanide reduction (24-fold), with the reaction occurring favourably around neutral pH, different to the cultural alkaline pH. Iron limited cultures grown in 5% and 20% CO2 showed increased exoelectrogenic rates in an earlier stage of growth in comparison to air grown cultures. Conveniently, the cultural pH under enriched CO2 was around neutral pH. Enhanced photo-bioelectricity generation in ferricyanide mediated biophotovoltaics was demonstrated. Power generation was six times higher with iron limited cultures at neutral pH than with iron sufficient cultures at alkaline pH. The enhanced performance was also observed in mediatorless biophotovoltaics, especially in the dark phase. Exoelectrogenesis was mainly driven by photosynthetic activity. However, rates in the dark were also improved and in the long term it appeared that the exoelectrogenic activity under illumination tended to that seen in the dark. Proteins participating in iron uptake by an alleged reductive mechanism were overexpressed (2-fold). However, oxidoreductases in the outer membrane remain to be identified. Furthermore, electroactive regions in biofilms of S. elongatus PCC7942 were established using cyclic voltammetry. Double step potential chronoamperometry was also successfully tested in the biofilms. Thus, the electrochemical characterisation of S. elongatus PCC7942 was demonstrated, implying that the strategies presented in this thesis could be used to screen for cyanobacteria and/or electrode materials to further develop systems for photo-bioelectricity generation.

No description available.

En la presente tesis doctoral se han desarrollado dispositivos electroquímicos de estado sólido para la detección selectiva de hidrocarburos en los gases de escape de coches. Diversos materiales fueron empleados para ello. También se llevó a cabo la activación catalítica del electrodo de trabajo para mejorar la reacción electroquímica del analito objetivo. El etileno fue seleccionado como el analito objetivo para cuantificar la cantidad total de hidrocarburos ya que es uno de los hidrocarburos más abundantes en un gas de escape. Pero el dispositivo no solo debe proporcionar una respuesta selectiva al etileno, sino que también debe tener una baja sensibilidad cruzada a otros compuestos también abundantes en un gas de escape como monóxido de carbono, agua, dióxido de nitrógeno, etc. El dispositivo consiste en un sensor potenciométrico de estado sólido en el que óxido de zirconio estabilizado con 8% de óxido de itrio (8YSZ) es empleado como electrolito. Dos electrodos son impresos en la superficie de cada cara. Primero, diversos óxidos fueron empleados como electrodo de trabajo utilizando a su vez platino como electrodo de referencia a 550ºC. Muchos de los materiales fueron descartados por su falta de selectividad al etileno, su alta sensibilidad cruzada al monóxido de carbono o por su respuesta no estable. Finalmente, Fe0.7Cr1.3O3 mezclado con 8YSZ fue seleccionado como el material más prometedor dada su buena selectividad al etileno con baja sensibilidad cruzada al monóxido de carbono. Esta configuración fue expuesta a agua como a fenantreno y metilnaftaleno. Esto produjo un aumento de la sensibilidad cruzada del dispositivo al monóxido de carbono, motivo por el que el sensor no sea adecuado para los objetivos de esta tesis. La estrategia adoptada consistió en actuar sobre el electrodo de referencia. El Platino, empleado habitualmente en la bibliografía como electrodo de referencia, fue cambiado por un conductor mixto iónico-electrónico activo al oxigeno: La0.8Sr0.2MnO3 mezclado con 8YSZ (LSM/8YSZ). Desgraciadamente, esto provocó un aumento de la sensibilidad cruzada al monóxido de carbono. Diversas nanopartículas fueron añadidas en el electrodo de trabajo para mejorar la actividad catalítica y aumentar la reacción electroquímica al etileno. Níquel, titanio y aluminio (especialmente la combinación de los dos últimos con níquel) dieron la mejor respuesta: el sensor era selectivo al etileno con baja sensibilidad cruzada al monóxido de carbono, agua y fenantreno. El efecto del espesor del electrolito en la respuesta del sensor también fue evaluado en un rango de 0.1 a 1.2 mm. Aunque no había una gran diferencia en la respuesta, la sensibilidad cruzada al monóxido de carbono era menor en el caso del dispositivo más fino. Otras alternativas al 8YSZ como electrolito también fueron evaluadas para trabajar a menores temperaturas (400 a 550ºC): oxido de cerio dopado con gadolinio (CGO) y óxido de zirconio estabilizado con un 10% de óxido de escandio (ScSZ). El dispositivo basado en ScSZ mostró un buen comportamiento a etileno a bajas temperaturas y en condiciones secas pero la adición de agua provocaba un aumento de la sensibilidad cruzada al monóxido de carbono. Una vez infiltrado el electrodo de trabajo con níquel, ambos dispositivos mostraron un buen comportamiento a bajas temperaturas en condiciones secas para concentraciones de etileno inferiores a 100 ppm, aunque la mejor respuesta fue obtenida a 550ºC. Ambos dispositivos mostraron una respuesta selectiva al etileno con baja sensibilidad cruzada al monóxido de carbono, agua y fenantreno. Se estudió también el efecto de mezclar el electrodo de trabajo con un conductor iónico (8YSZ). Se mezcló La0.87Sr0.13CrO3 (LSC) con 8YSZ sin observarse un cambio en la respuesta comparado con el electrodo solo. Además la mejor configuración Fe0.7Cr1.3O3/8YSZ//8YSZ//LSM/8YSZ (infiltrado con níquel) fue expuesto a dioxide de nitr / The present thesis is focused on the development of solid-state electrochemical devices for the selective detection of hydrocarbons in car exhaust gases. For this purpose, several materials were tested as electrodes and electrolytes. Catalytic activation of the working electrode has also been taken into account to boost the electrochemical reaction of the target analyte. Ethylene is one of the most abundant hydrocarbons in an exhaust gas and was selected as the target analyte to quantify the total amount of hydrocarbons. Not only the device has to be selective to ethylene but it must also have a low cross-sensitivity toward other pollutants abundant in an exhaust gas such as carbon monoxide, water, other hydrocarbons, nitrogen dioxide, etc. Thus, a solid-state potentiometric sensor was selected based on 8% Ytria-stabilized Zirconia (8YSZ) as electrolyte. Two electrodes were screen-printed on top of each face. First, several metal oxides were tested as working electrode with platinum (Pt) as reference electrode at 550ºC. Most of the materials were discarded because of their lack of selectivity to ethylene, high cross-sensitivity toward carbon monoxide or problems regarding stability. Fe0.7Cr1.3O3 mixed with 8YSZ was finally selected as the most promising material because of its selective response to ethylene with relatively low cross-sensitivity toward carbon monoxide. This sensor configuration was then exposed to water and phenanthrene and methylnaphthalene. This led to an increase of the cross-sensitivity of the device toward carbon monoxide making the device not suitable for the purposes of the present thesis. The approach to improve the sensor performance was to modify the reference electrode. Platinum, usually employed in literature as reference electrode, was exchanged for a mixed ionic-electronic conductor active to oxygen: La0.8Sr0.2MnO3 mixed with 8YSZ (LSM/8YSZ). Unfortunately, this increases the device activity toward carbon monoxide increasing its cross-sensitivity. Several nanoparticles were added onto the working electrode to improve the catalytic activity and boost the electrochemical reaction of ethylene. Nickel, titanium and aluminum (the last two elements combined with nickel) provided the best performance: selectivity to ethylene with low cross-sensitivity toward carbon monoxide, water and phenanthrene. The effect of the electrolyte thickness was also checked in the range from 0.1 to 1.2 mm. Although there was not a huge difference between them, the cross-sensitivity toward carbon monoxide was slightly lower for the thinnest sensor. Other alternatives to 8YSZ electrolyte were tested at lower working temperatures (400 to 550ºC) with the same electrodes materials: gadolinium-doped cerium oxide (CGO) and 10% scandia-stabilized Zirconia (ScSZ). ScsZ-based device showed a good performance in dry conditions but the addition of water decreased its suitability. Once improved the catalytic activity of the working electrode, both devices showed a good performance at lower temperature in dry conditions for ethylene concentration above 100 ppm but the best response was achieved at 550ºC. Both devices were selective to ethylene with low cross-sensitivity toward carbon monoxide, water and phenanthrene. The effect of mixing the working electrode with an ionic conductor (8YSZ) was also tested by mixing La0.87Sr0.13CrO3 (LSC) with 8YSZ and no change in response was observed when compared to the bare electrode. Finally, the best sensor configuration Fe0.7Cr1.3O3/8YSZ//8YSZ//LSM/8YSZ (after infiltration with nickel) was exposed to nitrogen dioxide to check the cross-sensitivity. The response was still selective to ethylene even with the addition of nitrogen dioxide plus water. / En la present tesi doctoral s'han desenvolupat dispositius electroquímics d'estat sòlid per a la detecció selectiva d' hidrocarburs als gasos d'escapament dels automòbils. Diversos materials van ser empleats per a tal fi. També es va dur a terme l'activació catalítica de l'elèctrode de treball per a millorar la reacció electroquímica al anàlit objectiu. L' etilè va ser seleccionat com anàlit objectiu per a quantificar la quantitat total d' hidrocarburs, ja que és un dels hidrocarburs més abundants en un gas d'escapament. Però el dispositiu no ha de ser tan sols selectiu a l'etilè, sinó que també deu proporcionar una baixa sensibilitat creuada a altres elements força abundants en un gas d'escapament com són el monòxid de carboni, l'aigua, el diòxid de nitrogen, etc. Així, el dispositiu consisteix en un sensor potenciomètric d'estat sòlid en el que l'òxid de zirconi estabilitzat amb un 8% d'òxid d'itri (8YSZ) és empleat como a electròlit. Els elèctrodes van impresos a cadascuna de les superfícies del dispositiu. Primer, diversos òxids es van emprar com a elèctrode de treball fent servir platí com elèctrode de referència a 550ºC. Molts dels materials van ser descartats per motiu de la seva manca de selectivitat al etilè, la seva alta sensibilitat creuada al monòxid de carboni o perquè la resposta no era estable. Finalment, el Fe0.7Cr1.3O3 mesclat amb 8YSZ va ser seleccionat com el material més prometedor atès a la selectivitat a l'etilè i la baixa sensibilitat creuada al monòxid de carboni. Aquesta configuració és doncs exposada tant a l'aigua com al fenantrè i al metilnaftalè. Això va produir un increment de la sensibilitat creuada al monòxid de carboni, fent que el dispositiu no resulti idoni per als objectius de la present tesi. Es va adoptar com a estratègia modificar l'elèctrode de referència. Platí, empleat sovintment com a elèctrode de referència a la bibliografia, va ser canviat per un conductor mixt iònic-electrònic actiu a l'oxigen: La0.8Sr0.2MnO3 mesclat amb 8YSZ (LSM/8YSZ). Malauradament, això va provocar l'augment de la sensibilitat creuada al monòxid de carboni. Diverses nanopartícules van ser afegides al elèctrode de treball per tal de millorar la seva activitat catalítica i així augmentar la reacció electroquímica de l'etilè. Níquel, titani i alumini (especialment la combinació dels dos darrers amb níquel) van donar la millor resposta: el sensor era selectiu a l¿etilè amb una baixa sensibilitat creuada al monòxid de carboni, l'aigua i al fenantrè. L'efecte del espessor del electròlit a la resposta del sensor també va ser avaluada en un rang de 0.1 a 1.2 mm. Malgrat que no hi ha una gran diferència en la resposta, la sensibilitat creuada al monòxid de carboni és menor en el cas del dispositiu més prim. Altres alternatives al 8YSZ com a electròlit van ser també avaluades per tal de treballar a temperatures menors (400 a 550ºC): òxid de ceri dopat amb gadolini (CGO) i òxid de zirconi estabilitzat amb un 10% d'òxid d'escandi (ScSZ). El dispositiu basat en ScSZ va mostrar un bon comportament a l'etilè a baixes temperatures en condiciones seques, però la adició d'aigua provocava un augment de la sensibilitat creuada al monòxid de carboni. Una vegada que l'elèctrode de treball es infiltrat amb níquel, ambdós dispositius mostraren un bon comportament a baixes temperatures en condicions seques per a concentracions d'etilè menors de 100 ppm, encara que la millor resposta fou obtinguda a 550ºC. La resposta era selectiva a l'etilè amb una baixa sensibilitat creuada al monòxid de carboni, l'aigua i el fenantrè. Es va comprovar també l'efecte de mesclar l'elèctrode de treball amb un conductor iònic (8YSZ). Es va mesclar La0.87Sr0.13CrO3 (LSC) amb 8YSZ sense observa cap canví en la resposta comparada amb l'electrode sense 8YSZ. la millor configuració Fe0.7Cr1.3O3/8YSZ//8YSZ//LSM/8YSZ (infiltrado con níquel) fou exposada / Toldra Reig, F. (2018). Development of electrochemical devices for hydrocarbon sensing purposes in car exhaust gases [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/110968

Recentemente foi demonstrado que a técnica de ressonância magnética nuclear no domínio do tempo (RMN-DT) é uma importante ferramenta analítica que é passível de ser acoplada com a eletroquímica (EQ-RMN). No entanto, como foi demonstrado nesse presente trabalho, a técnica de RMN não é passiva, ou seja, ela atua sobre as reações eletroquímicas aumentando a velocidade das reações realizadas in situ quando essas são limitadas por transporte de massas e/ou transferência de cargas. Essa alteração da taxa de reação é ocasionada por um fenômeno conhecido por magnetoeletrólise, que tem como principal resultante a força de Lorentz, que é o produto vetorial entre o campo magnético e o fluxo de íons gerado durante a eletrólise. O efeito do campo magnético sobre diferentes sistemas eletroquímicos foi comprovado na presença de campo magnético de equipamentos de RMN de baixa e alta resolução. Além do foco dado para a magnetoeletrólise durante o acoplamento EQ-RMN, novas células eletroquímicas foram miniaturizadas para a utilização com a RMN a partir de um método simples, rápido e robusto. Também foram feitas medições de velocimetria utilizando a técnica de imagem por spin eco com as quais foi possível visualizar e quantificar o efeito do campo magnético atuando sobre a reação de eletrodeposição de cobre realizada in situ. Esse trabalho foi o primeiro a utilizar o campo magnético do espectrômetro de RMN para estudar a magnetoeletrólise. Além disso, esse trabalho de doutorado foi o primeiro a utilizar um espectrômetro de RMN de bancada de alta resolução para o acoplamento com a eletroquímica. / Recently it was demonstrated that time domain Magnetic Nuclear Resonance (TD-NMR) is an important analytical technique which can be coupled to electrochemistry (EC-NMR). However, it was demonstrated in this work that NMR is not a passive technique, in other words it affects the electrochemical reactions performed in situ by increasing the reaction rate of mass transport and/or charge transfer limited reactions. This change in the reaction rate is caused by a phenomenon known as magnetoeletrolysis, it has as main resultant the Lorentz force, which is the vectorial product between the magnetic field vector and the ion flow produced during the electrolysis. The magnetic field effect on different electrochemical systems has been shown in the presence of magnetic fields of low and high resolution NMR spectrometers. In addition to the focus given to magnetoelectrolysis during the EC-NMR coupling, novel electrochemical cells were miniaturized for coupling with NMR by using a simple, rapid and robust method. Velocimetry measurements were also made using the spin-echo imaging technique with which it was possible to visualize and quantify the effect of the magnetic field acting on the in situ copper electrodeposition reaction. This work was the first to use the magnetic field of the NMR spectrometer to study magnetoelectrolysis. In addition, this doctoral thesis was the first to use a bench-top high resolution NMR spectrometer for coupling with electrochemistry.

Recentemente foi demonstrado que a técnica de ressonância magnética nuclear no domínio do tempo (RMN-DT) é uma importante ferramenta analítica que é passível de ser acoplada com a eletroquímica (EQ-RMN). No entanto, como foi demonstrado nesse presente trabalho, a técnica de RMN não é passiva, ou seja, ela atua sobre as reações eletroquímicas aumentando a velocidade das reações realizadas in situ quando essas são limitadas por transporte de massas e/ou transferência de cargas. Essa alteração da taxa de reação é ocasionada por um fenômeno conhecido por magnetoeletrólise, que tem como principal resultante a força de Lorentz, que é o produto vetorial entre o campo magnético e o fluxo de íons gerado durante a eletrólise. O efeito do campo magnético sobre diferentes sistemas eletroquímicos foi comprovado na presença de campo magnético de equipamentos de RMN de baixa e alta resolução. Além do foco dado para a magnetoeletrólise durante o acoplamento EQ-RMN, novas células eletroquímicas foram miniaturizadas para a utilização com a RMN a partir de um método simples, rápido e robusto. Também foram feitas medições de velocimetria utilizando a técnica de imagem por spin eco com as quais foi possível visualizar e quantificar o efeito do campo magnético atuando sobre a reação de eletrodeposição de cobre realizada in situ. Esse trabalho foi o primeiro a utilizar o campo magnético do espectrômetro de RMN para estudar a magnetoeletrólise. Além disso, esse trabalho de doutorado foi o primeiro a utilizar um espectrômetro de RMN de bancada de alta resolução para o acoplamento com a eletroquímica. / Recently it was demonstrated that time domain Magnetic Nuclear Resonance (TD-NMR) is an important analytical technique which can be coupled to electrochemistry (EC-NMR). However, it was demonstrated in this work that NMR is not a passive technique, in other words it affects the electrochemical reactions performed in situ by increasing the reaction rate of mass transport and/or charge transfer limited reactions. This change in the reaction rate is caused by a phenomenon known as magnetoeletrolysis, it has as main resultant the Lorentz force, which is the vectorial product between the magnetic field vector and the ion flow produced during the electrolysis. The magnetic field effect on different electrochemical systems has been shown in the presence of magnetic fields of low and high resolution NMR spectrometers. In addition to the focus given to magnetoelectrolysis during the EC-NMR coupling, novel electrochemical cells were miniaturized for coupling with NMR by using a simple, rapid and robust method. Velocimetry measurements were also made using the spin-echo imaging technique with which it was possible to visualize and quantify the effect of the magnetic field acting on the in situ copper electrodeposition reaction. This work was the first to use the magnetic field of the NMR spectrometer to study magnetoelectrolysis. In addition, this doctoral thesis was the first to use a bench-top high resolution NMR spectrometer for coupling with electrochemistry.

Glödlampan, en gång symbolen för mänsklig uppfinningsförmåga, är idag på väg att försvinna. Lysdioder och lågenergilampor har istället tagit över då dessa har betydligt längre livstid och högre effektivitet. Den tidigare så hyllade glödlampan anses numera vara en miljöbov, och förbud och restriktioner mot den blir allt vanligare. Trots detta så är de nya alternativen bara att betrakta som provisoriska steg på vägen mot en ideal ljuskälla, som idag tyvärr inte existerar. Lågenergilampor innehåller exempelvis kvicksilver, och utgör därmed ett direkt hot mot en användares hälsa. Både lysdioder och lågenergilampor består även av höga halter av andra tungmetaller, och är väldigt komplicerade att tillverka. Återvinning är därför ett måste, och en fullödig energibesparingsanalys måste ta hänsyn till den betydande energin som går åt vid tillverkningen. Till viss del kan detta lösas genom att göra komponenterna små och ljusstarka, men för att göra en sådan belysning angenäm används istället utrymmeskrävande och ofta energislukande lampskärmar. Lysdioder och lågenergilampor är helt enkelt bra, men långt ifrån perfekta.All elektronisk utrustning är idag beroende av metaller och inorganiska halvledare, vilket gör återvinning viktig och tillverkning komplicerad. Detta är kanske på väg att ändras då även organiska material, t.ex. plast, har visat sig kunna ha elektroniska egenskaper. Idag är organisk elektronik ett hett forskningsområde där material med liknande egenskaper som plast, fast med funktionella elektroniska egenskaper, undersöks och appliceras. Något som gör organiska material extra intressanta är att många kan lösas upp i vätskor, vilket möjliggör för skapandet av bläck. Detta leder i sin tur till möjligheter för användandet av storskaliga trycktekniker, t.ex. tidningspressar och bläckstråleskrivare, vilka leder till en stor kostnadsreduktion och förenklad tillverkning av lysande komponenter. Idag har plast redan ersatt många andra material i en mängd olika tillämpningar. Plastflaskor är vanligare än glasflaskor, och ylletröjor konkurerar idag med kläder gjorda av fleece och andra syntetiska fibrer. Med ljusemitterande plast finns det helt klart en möjlighet att en liknande utveckling kan ske även för lampor.Den här avhandlingen fokuserar på den fortsatta utvecklingen av den ljusemitterande elektrokemiska cellen (LEC), som 1995 uppfanns av Pei et al. LEC-tekniken använder sig av organiska halvledare för att konvertera elektrisk ström till ljus, men även en elektrolyt som möjliggör elektrokemisk dopning. Detta förbättrar den organiska halvledarens elektroniska egenskaper signifikant, vilket leder till mindre resistans och högre effektivitet hos den färdiga lysande komponenten.Visionen för denna och besläktade tekniker har sedan länge varit förverkligandet av en lysande tapet. Den här avhandlingen har försökt närma sig denna vision genom att visa hur en LEC kan uppnå hög effektivitet och lång livslängd, och samtidigt tillverkas i luft med storskaliga produktionsmetoder. Orsaker till en tidigare begränsad livslängd har identifierats och minimerats med hjälp av nya komponentstrukturer och materialformuleringar. En inkapslingsmetod presenteras också, vilken skyddar komponenten från syre och vatten som annars lätt reagerar med det dopade organiska materialet. Detta resulterar i en signifikant förbättring av livslängden.Genom att använda slot-die bestrykning och sprayning, båda kompatibla med rulle-till-rulle tillverkning, har möjligheter för storskalig produktion demonstrerats. Slutligen har en speciell metod för spraymålning av stora lysande ytor utvecklats. / The incandescent light bulb, once the very symbol for human ingenuity, is now being replaced by the next generation of lighting technologies such as the compact fluorescent lamp (CFL) and the light emitting diode (LED). The higher efficiencies and longer operational lifetimes of these new sources of illumination have led to the demise of the classic traditional bulb. However, it should be pointed out that the light sources that are taking over are better, but not perfect. The complex high-voltage electronic circuits and health hazardous materials required for their operation make them far from a sustainable eco-friendly option. Their fabrication is also complex, making the final product expensive. A new path forward might be through the use of plastics or other organic materials. Though not traditionally seen as electronically active, some organic materials do behave like inorganic semiconductors and substantial conductivity can be achieved by doping. Since plastics can be easily molded into complex shapes, or made into an ink using a solvent, it is expected that organic materials could revolutionize how we fabricate electronic devices in the future, and possibly replace inorganic crystals in the same way as plastics have replaced glass and wool for food storage and clothes. This thesis has focused on the light-emitting electrochemical cell (LEC), which was invented by Pei et al. in 1995. It employs organic semiconductors that can convert electricity to light, but also an electrolyte that further enhances the electronic properties of the semiconductor by allowing it to be electrochemically doped. This allows light-emitting films to be driven by a low-voltage source at a high efficiency. Unfortunately, the electrolyte has been shown to facilitate rapid degradation of the device under operation, which has historically severely limited the operational lifetime. Realizing the predicted high efficiency has also proven difficult. The purpose of this thesis is to bridge the gap between the LEC and the CFL. This is done by demonstrating efficient devices and improved operational lifetimes. Possible degradation mechanisms are identified and minimized using novel device architectures and optimized active layer compositions. An encapsulation method is presented, and shown to increase the LEC stability significantly by protecting it from ambient oxygen and water. The thesis further focuses on up-scaled fabrication under ambient air conditions, proving that light-emitting devices are compatible with solution-based and cost-efficient printing. This is achieved by a roll-to-roll compatible slot-die coating and a novel spray-depositing technique that alleviates problems stemming from dust particles and phase separation. A practical ambient air fabrication and a subsequent operation of light-emitting electrochemical cells with high efficiency are thus shown possible.

Advantages of electrochemical wastewater treatment over conventional wastewater treatment include its smaller footprint, modularity, and ability to meet increasingly stringent government regulations. A power supply that can be packaged with an electrochemical stack could make electrochemical wastewater treatment more cost-effective and scalable. For this application, the series and series-parallel resonant converters are suitable power converter candidates. With an output current specification of 100A, the series-parallel resonant converter (SPRC) is superior due to its simpler output stage. The thesis presents the design of a 500W SPRC for a wastewater treatment cell stack. A rudimentary cell model is derived experimentally. The closed loop analysis, controller design and simulation results are presented. The output voltage and current are estimated using sensed quantities extracted from the high voltage, low current primary side. Low voltage experimental results verify the operation of the power stage and voltage estimation circuitry in open loop pulsed operation.