Measuring temperature and heat flux is important for regulating any physical, chemical, and biological processes. Traditional thermopiles can provide accurate and stable temperature reading but they are based on brittle inorganic materials with low Seebeck coefficient, and are difficult to manufacture over large areas. Recently, polymer electrolytes have been proposed for thermoelectric applications because of their giant ionic Seebeck coefficient, high flexibility and ease of manufacturing. However, the materials reported to date have positive Seebeck coefficients, hampering the design of ultra-sensitive ionic thermopiles. Here we report an “ambipolar” ionic polymer gel with giant negative ionic Seebeck coefficient. The latter can be tuned from negative to positive by adjusting the gel composition. We show that the ion-polymer matrix interaction is crucial to control the sign and magnitude of the ionic Seebeck coefficient. The ambipolar gel can be easily screen printed, enabling large-area device manufacturing at low cost.

The technical application of screen and stencil printing has been state of the art for decades. As part of the subtractive production process of printed circuit boards, for instance, screen and stencil printing play an important role. With the end of the 20th century, another field has opened up with organic electronics. Since then, more and more functional layers have been produced using printing methods. Printed electronics devices offer properties that give almost every freedom to the creativity of product development. Flexibility, low weight, use of non-toxic materials, simple disposal and an enormous number of units due to the production process are some of the prominent keywords associated with this field.

Screen printing is a widely used process in printed electronics, as this process is very flexible with regard to the materials that can be used. In addition, a minimum resolution of approximately 30 µm is sufficiently high. The ink film thickness, which can be controlled over a wide range, is an extremely important advantage of the process. Depending on the viscosity, layer thicknesses of several hundred nanometres up to several hundred micrometres can be realised.

The conversion and storage of energy became an increasingly important topic in recent years. Since regenerative energy sources, such as photovoltaics or wind energy, often supply energy intermittently, appropriate storage systems must be available. This applies to large installations for the power supply of society, but also in the context of autarkic sensors, such as those used in the Internet of Things or domestic/industrial automation. A combination of micro-energy converters and energy storage devices is an adequate concept for providing energy for such applications.

In this thesis the above mentioned keywords are addressed and the feasibility of printed thermoelectric energy converters and supercapacitors as energy storage devices are investigated. The efficiency of thermoelectric generators (TEG) is low, but in industrial environments, for example, a large amount of unused low temperature heat energy can be found. If the production costs of TEGs are low, conversion of this unused heat energy can contribute to increasing system efficiency.

Additionally, printing of supercapacitor energy storage devices increases the usability of the TEG. It is appropriate to use both components as complementary parts in an energy system.

Den tekniska tillämpningen av skärm- och stencilutskrift har varit toppmoderna i årtionden. Som en del av den subtraktiva produktionsprocessen av tryckta kretskort spelar exempelvis skärm- och stencilutskrift en viktig roll. I slutet av 1900-talet har ett annat fält öppnat med organisk elektronik. Sedan dess har allt fler funktionella lager producerats med hjälp av tryckmetoder. Tryckta elektronikanordningar erbjuder egenskaper som ger nästan all frihet till kreativiteten i produktutvecklingen. Flexibilitet, låg vikt, användning av giftfria material, enkelt bortskaffande och ett enormt antal enheter på grund av produktionsprocessen är några av de framträdande nyckelord som hör till detta område.

Skärmtryck är en allmänt använd process i tryckt elektronik, eftersom processen är mycket flexibel med avseende på material som kan användas. Dessutom är en minsta upplösning på cirka 30 µm tillräckligt bra. Bläckfilmens tjocklek, som kan styras över ett brett område, är en extremt viktig fördel med processen. Beroende på viskositeten kan skikttjockleken på flera hundra nanometer upp till flera hundra mikrometer realiseras.

Energikonvertering och lagring har blivit ett allt viktigare ämne de senaste åren. Eftersom regenerativa energikällor, såsom fotovoltaik eller vindkraft, ofta levererar energi intermittent, måste lämpliga lagringssystem vara tillgängliga. Detta gäller stora installationer för samhällets strömförsörjning, men också inom ramen för autarkiska sensorer, som de som används i saker av saker eller inhemsk / industriell automation. En kombination av mikroenergiomvandlare och energilagringsenheter är ett lämpligt koncept för att tillhandahålla energi för sådana applikationer.

I denna avhandling behandlas ovan nämnda nyckelord. Genomförbarhet av tryckta termoelektriska energiomvandlare och superkapacitorer som energilagringsenheter undersöks. Effektiviteten hos termoelektriska generatorer (TEG) är låg, men i industriella miljöer kan exempelvis en stor mängd oanvänd låg temperatur värmeenergi hittas. Om produktionskostnaderna för TEG är låga kan konvertering av denna oanvända värmeenergi bidra till ökad systemeffektivitet. Dessutom ökar utskrift av superkapacitorer användbarheten hos TEG. Det är lämpligt att använda båda komponenterna.

Potentially important parameters of printed flexible batteries based on the primary zinc -manganese dioxide (Zn/MnO₂) system were investigated using a fractional factorial design of experiments (DOE). A novel hydrogel electrolyte made of lactic acid and cornstarch proved functionality. Using this kind of hydrogel, it is important to impede unwanted sidereactions with the zinc electrode. Accurate control of the electrode mass is absolutely necessary, since the mass of deposited MnO₂ and the mass ratio of MnO₂:Zn determines the capacity of the cells. With optimised parameter settings the capacity of printed cells was increased to over 100 mAh, which is equivalent to an area- related specific capacity of about 7.3 mAh/cm². This is within the range of the commercially available button cells, which were supplied with the same discharge conditions between 125 and 155 mAh. By means of electrochemical impedance spectroscopy (EIS) the cells were examined immediately after assembly. Within three hours the cell could be identified as in principle working or defect. As such, precious measurement time can be saved by selecting promising cells prior to characterisation.

Energy harvesting - the conversion of ambient energy into electrical energy - is a frequently used term nowadays. Several conversion principles are available, e.g., photovoltaics, wind power and water power. Lesser-known are thermoelectric generators (TEG) although they were already studied actively during and after the world wars in the 20th century (Caltech Material Science, n. d.). In this work, the authors present a mathematical model for the calculation of input or output parameters of printed thermoelectric generators. The model is strongly related to existing models (Freunek et al., 2009; Rowe, 1995; Glatz et al., 2006) for conventionally produced TEGs as well as for printed TEGs. Thermal effects as investtigated by Freunek et al. (2009; 2010) could be included. In order to demonstrate the benefit of the model, two examples of calculations are presented. The parameters of the materials are derived from existing printing inks reported elsewhere (Chen et al., 2011; Wuesten and Potje-Kamloth, 2008; Zhang et al., 2010; Liu et al., 2011; Bubnova et al., 2011). The printing settings are chosen based on feasibility and convenience.

It is very important to control the thickness of the ink deposit in screen printing of functional pastes – especially in the field of printed electronics. In general, it is the height of the conductive tracks that can be altered in order to control the ohmic resistance since the specific resistance of the deployed material, the base area and the length of the printed structure are pre-defined. The aim of this investigation is to detect the most significant parameters that influence the ink film deposition in order to establish a dry ink film layer on the substrate which ranges between 80 to 100 microns.

Printed thermoelectric generators (TEG) combine the advantages of screen printing with the uncomplicated assembly and reliability of thermoelectric devices. Successively printed layers on top of each other are needed for a completed device in a vertical stack setup. One of the challenging layers is the insulating mask which provides cavities for the thermoelectric legs. By governing the thickness of this insulating mask the overall thickness of the TEG is determined, too. The spatial separation is a necessity for reasonable energy conversion efficiency.

Thermoelectric generators (TEG) convert thermal energy into electricity, directly [1]. The sophisticated and therefore expensive ways of producing such TEGs presently prevent the technology to enter new markets other than space missions or the combustion systems of cars [2]. A promising approach to reduce the costs per Watt is to print the TEG structures on flexible substrates to be able to affix the flexible TEG directly on the heat source or sink. This report describes the process of assembling a fully printed TEG especially the issues that arise when printing the intermediate insulating layers in a so called vertical layout of a TEG. As the layer thicknesses all are rather thick screen and stencil printing were used. When the cavities in the insulating layer are subsequently filled with the thermoelectric leg materials the electrical contact between the top and the bottom conductors of the TEG are established. However, the cavities must be filled properly to ensure a good electrical contact. For this reason, the flow behaviour of the thermoelectric materials must be optimized for printing.