Forskningsinstitutet RISE, Research Institutes of Sweden, har ettprojekt som kallas IoT Low Energy och syftar till att utvecklalågenergisensorer i kombination med artificiell intelligens. Måletmed detta kandidatarbete var att ta fram digitala designunderlagpå en kapsling av elektronik åt ett system bestående av ensensornod och en central enhet. Sensornoden kopplas sammanmed en kraftmätande skosula, där registrerade data sedan skickastrådlöst till den centrala enheten som i sin tur är sammankoppladmed en smarttelefon där uppmätt data kan avläsas. Detta hargenomförts via metoder såsom riskanalys, funktionsanalys,kravspecifikation samt urval från en klassisk designprocess i formav handgjorda skisser, brainstorming, omvärldsanalys och digitalaskisser. Processen har skett parallellt med framtagningen avelektroniken hos RISE, vilket har gett frihet i hur systemet harkunnat designats. Givna mått på elektroniken tillhandahölls medmöjlighet att utforma den efter designen på kapslingen. Arbetetsyftade ej till att ta fram en färdig produkt, utan de slutgiltigadigitala designunderlagen består av renderade CAD-modeller istudiomiljö samt foton på systemet i verklig miljö. / RISE, the Research Institutes of Sweden, has a project called IoTLow Energy which aims to develop low energy sensors incombination with artificial intelligence. The aim of this thesis wasto produce a digital design for an encapsulation of electronics for asystem consisting of a sensor node and a central unit. The sensornode is connected to a force measuring shoe sole, where registereddata can be sent wirelessly to the central unit, which is connectedto a smartphone where measured data can be read. This has beendone through methods such as risk analysis, function analysis,technical specification and a selection from a classic design processas handmade sketches, brainstorming, analysis of the surroundingworld and digital sketches. The process has taken place in parallelwith the project at RISE, which has offered freedom in how thesystem could be designed. The dimensions of the electronic wereprovided by RISE, with the possibility to construct it according tothe design of the encapsulations. The work did not aim to producea finished product, but the final digital design documents consistof rendered CAD models in a studio environment and photos ofthe system in a real environment.

Two major projects involving the use of solution processed blended semiconductors for organic field effect transistors (OFET) were explored. The first incorporated unsorted single walled carbon nanotubes (SWCNTs) into a diketopyrrolopyrrole-quarterthiophene (DPP-QT) semiconductor to enhance the mobility of the OFET. 2 wt % SWCNT was found to be the optimal blend ratio, nearly doubling the device mobility (0.6 to 0.98 cm^2/V·s). Beyond this ratio, the metallic content of the SWCNT’s dropped the on/off ratio below acceptable levels. When source drain metals who’s work function poorly matched that of the DPP-QT semiconductors highest occupied molecular orbital (HOMO) were used, the SWCNT could dramatically reduce the charge injection ratio with best results achieved for Al, dropping the contact resistance from 10^5 to 45 MΩ. The second project explored the addition of small molecule additives into a UV-sensitive semiconductor 2,7-dipentyl[1]benzothieno[3,2-b][1] benzothiophene (C5-BTBT) mixed with a polymethyl methacrylate (PMMA) polymer binder. We generated a C5-BTBT based phototransistor sensitive to UV-A light. The HOMO and lowest unoccupied molecular orbital (LUMO) of C5-BTBT and the various additives were measured and discovered to play a critical role in how the device operates. We discovered if an additive has a LUMO lower in energy than C5-BTBT, it can act as a charge trap for a photogenerated electron. Electron deficient additives were found to retain a trapped electron for an extended period of time, allowing the device to remain in a high current state for an extended period of time (>1 hour). This provides an opportunity for the device to be used as an optical memory system or photoswitch. The best system could detect UV-A with a Pill > 10^5 and a photoresponsivity of 40 A/W at a Pinc of 0.0427 mW/cm^2. / Thesis / Doctor of Philosophy (PhD) / An emerging field of electronics is the use of organic materials that can be solution processed, to reduce manufacturing costs and make new and interesting products. Here we used unsorted carbon nanotubes blended into the semiconductor layer of a transistor, providing a bridge for the energy mismatch between the electrodes and the semiconductor. This allowed us the freedom to choose different metals to act as our electrodes when making electronic devices. Additionally through the correct choice of semiconductor, we added device functionality, making it responsive to UV-A light. This produced a device that could act as a UV-A sensor, logic switch or memory device. These devices are air stable and solution processable, a necessity if they are to be used in real world applications.

The increasing demand for digitalization has spurred the need for novel and sustainable designs of electronic devices like sensors. Advanced additive print technologies, organic inks, and bio-based substrates in device fabrication exhibit promising potential for reducing energy and raw material consumption, thereby alleviating environmental impacts. One such innovation is the novel method of laser graphitization in designing devices like printed humidity sensors. This study focuses on evaluating the environmental impacts of implementing this novel technique in the field of printed electronics. In particular, the thesis conducts a cradle-to-gate life cycle assessment (LCA) of producing a resistive-type humidity sensor from a forest-based wood ink using laser graphitization. The sensor is based on the design that was demonstrated in the lab facilities at the Research Institutes of Sweden (RISE), Norrköping. The assessment is at a lab-scale production of making 1mm2 area of a laser-induced graphitized (LIG) sensor, excluding usage, disposal, or recycling phases. The results highlight impacts from electricity usage as the primary contributor to the overall environmental impacts, across the production process, followed by the impacts from material usage. The impact share distribution from these two hotspots identifies opportunities in the process that need to be prioritized for immediate actions. Sensitivity analyses varying the sensor layer thickness and the electricity mix of the laboratory facilities reveal insightful impact trends. The results from scenario analyses show the LIG sensor to have much lower environmental impacts than that of a sensor with silver electrodes and carbon-based sensing ink. They also show potential for achieving economies of scale from the mass production of LIG sensors. The data inventory for the processes and components of the sensor stands as a crucial part of this study, relying heavily on literature, assumptions, and proxy data. While these may reveal some uncertainties and limitations, the study nonetheless, serves as an important reference for future research concerning similar databases and a cradle-to-grave LCA of the sensor. / Den ökade efterfrågan för digitalisering har skapat behov av nya och hållbara designs av elektroniska enheter som sensorer. Avancerade lager printteknologier, organiskt bläck och biobaserat substrat i enhetstillverkning visar lovande potential för att reducera energi och rå materielkonsumtion och därmed minskning av miljöpåverkan. En sådan innovation är den nya metoden av lasergrafitisering i designenheter som printad fuktighetssensor. Denna studie har som fokus att utvärdera miljöpåverkan av ny teknik inom området tryckt elektronik. I synnerhet ska avhandlingen göra en livscykelanalys (LCA), från råvaruutvinning till slutprodukt av att producera en resistent fuktsensor från ett skogsbaserat träbläck genom lasergrafitisering. Sensorn är baserad på en design som var demonstrerad i en labbanläggning hos forskningsinstitutet RISE i Norrköping. Forskningen är analysen av laboratorieskalad produktion av 1mm2 lasergrafitiserad sensoryta, exklusive användning, bortskaffande och återvinningsfaser. Resultaten lyfter fram påverkan från elektronisk användning som den primära bidragaren till övergripande miljöpåverkan över hela produktionsprocessen, följd av påverkan från materiell användning. Påverkan från dessa två hotspots uppmärksamgör möjligheter i processen som är av prioritet för omedelbart åtgärdande. Känslighetsanalyser av de varierande sensorskiktens tjockhet och elektronisk mix i laboratoriums faciliteten, påvisar insiktsfulla påverkanstrender. Resultaten från scenarioanalyser visar att LIG sensorer har mycket lägre miljöpåverkan än sensorer med silverelektroner och kolbaserat avläsningsbläck. De visar också potential för att uppnå ekonomisk skalbarhet för massproducering av LIG-sensorer. Datalagring för processerna och komponenterna av sensorn står som kritisk del av studien, med en tung tillit på litteratur, antaganden och proxydata. Då dessa faktorer kan påvisa några osäkerheter och begränsningar så bidrar studien ändå som en viktig referens för framtida forskning berörande liknande databaser och en LCA från råvaruutvinning till sluthanteringsfasen av sensorn.

Tesis por compendio / [ES] La integración de electrónica en los tejidos para obtener nuevas funcionalidades es una de las apuestas de futuro de la industria textil y de la moda. Al estar compuestos parcialmente por tejido, los textiles electrónicos proporcionan a los usuarios un mayor confort, durabilidad y ligereza que otros dispositivos, manteniendo al mismo tiempo las propiedades electrónicas. No obstante, conseguir estas nuevas funcionalidades, a un coste asequible y asegurando la flexibilidad y ligereza propias de los tejidos, sigue siendo un reto para el sector. El área de la electrónica impresa ha permitido el desarrollo de una electrónica flexible combinando métodos de impresión tradicionales con el uso de tintas electrónicas. La técnica de impresión flexográfica destaca entre las demás por ofrecer altas velocidades de fabricación, calidad y alta productividad a bajo coste. En el ámbito textil, sin embargo, su incorporación es todavía muy reciente y no hay suficientes estudios para su aplicación. En este contexto, esta tesis doctoral tiene como objetivo fundamental estudiar la novedosa aplicación de la técnica de la flexografía sobre materiales textiles. Para ello, se ha tomado como base los actuales conocimientos de la autora en el área de la electrónica impresa textil empleando la tecnología serigráfica. Con este fin, durante el desarrollo de la tesis se realiza, en primer lugar, el estudio de los parámetros necesarios para la aplicación de dicha tecnología en diferentes substratos. Del estudio se obtienen diferentes valores adecuados para la impresión mediante flexografía según si el sustrato se trata de un tejido, un no-tejido, un sustrato polimérico o un papel siliconado. En segundo lugar, se definen los protocolos que permiten la integración de tintas con características eléctricas en las telas empleando la tecnología flexográfica. Por un lado, se estudia el impacto de los parámetros estructurales de un tejido de calada en la conductividad de la tinta impresa y, por otro lado, la influencia del material de la trama en la conductividad de elementos conductores-resistivos. Para ello, se realiza una impresión controlada sobre tejidos de calada utilizando la misma tinta conductora de plata y se analizan las propiedades físicas y eléctricas de las muestras resultantes. Se concluye que, cuanto mayor sea la densidad del textil, menor es la conductividad final de la impresión, y que el algodón es el material menos recomendable para la impresión electrónica mediante la técnica de la flexografía. Finalmente, se trabaja en el objetivo de desarrollar un sistema de medición de temperatura continuo mediante impresión electrónica sobre sustratos flexibles y elásticos mediante serigrafía para su traslación a flexografía. Se consigue desarrollar con éxito un sistema robusto, de bajo consumo y confortable para los pacientes que permite la adquisición de los datos de temperatura de forma continua. / [CAT] La integració d'electrònica en els teixits per a obtenir noves funcionalitats és una de les apostes de futur de la indústria tèxtil i de la moda. A l'estar compostos parcialment per teixit, els tèxtils electrònics proporcionen als usuaris un major confort, durabilitat i lleugeresa que altres dispositius, mentre mantenen les mateixes propietats electròniques. No obstant això, aconseguir aquestes noves funcionalitats, a un cost assequible i mantenint la flexibilitat i lleugeresa pròpies dels teixits, continua sent un repte per al sector. L'àrea de l'electrònica impresa ha permès el desenvolupament d'una electrònica flexible combinant mètodes d'impressió tradicionals amb l'ús de tintes electròniques. La tècnica d'impressió flexogràfica destaca entre les altres per oferir altes velocitats de fabricació, qualitat i alta productivitat a baix cost. En l'àmbit tèxtil, no obstant això, la seua incorporació és encara molt recent i no hi ha suficients estudis per a la seua aplicació. En este context, esta tesi doctoral té com a objectiu fonamental estudiar la nova aplicació de la tècnica de la flexografia sobre materials tèxtils. Per a això, s'ha pres com a base els actuals coneixements de l'autora en l'àrea de l'electrònica impresa tèxtil emprant la tecnologia serigràfica. Amb este fi, durant el desenrotllament de la tesi es realitza, en primer lloc, l'estudi dels paràmetres necessaris per a l'aplicació de la dita tecnologia en diferents substrats. De l'estudi s'obtenen diferents valors adequats per a la impressió per mitjà de flexografia segons si el substrat es tracta d'un teixit, un no-teixit, un substrat polimèric o un paper siliconat. En segon lloc, es defineixen els protocols que permeten la integració de tintes amb característiques elèctriques en les te les emprant la tecnologia flexogràfica. D'una banda, s'estudia l'impacte dels paràmetres estructurals d'un teixit de calada en la conductivitat de la tinta impresa i, d'altra banda, la influència del material de la trama en la conductivitat d'elements conductors-resistius. Per a això, es realitza una impressió controlada sobre teixits de calada utilitzant la mateixa tinta conductora de plata i s'analitzen les propietats físiques i elèctriques de les mostres resultants. Es conclou que, quant major siga la densitat del tèxtil, menor és la conductivitat final de la impressió, i que el cotó és el material menys recomanable per a la impressió electrònica per mitjà de la tècnica de la flexografia. Finalment, es treballa en l'objectiu de desenrotllar un sistema de mesurament de temperatura continu per mitjà d'impressió electrònica sobre substrats flexibles i elàstics per mitjà de serigrafia per a la seua translació a flexografia. S'aconsegueix desenrotllar amb èxit un sistema robust, de baix consum i confortable per als pacients que permet l'adquisició de les dades de temperatura de forma contínua. / [EN] Electronics' integration into textiles to obtain new functionalities is one of the bets for the future of the textile and fashion industry. Electronic textiles provide users greater comfort, durability, and lightness than other devices as they are partially made of fabric, while maintaining the same electronic properties. However, achieving these new functionalities, maintaining the flexibility and flexibility typical of the fabrics with at affordable cost, continues to be a challenge for the sector. The area of printed electronics has allowed the development of flexible electronics by combining traditional printing methods with the use of electronic inks. The flexographic printing technique stands out among the others for offering high manufacturing speeds, quality, and high productivity at low cost. In the textile field, however, its incorporation is still very recent and there are not enough studies for its application. In this context, this doctoral thesis fundamental objective is to study the novel application of the flexography technique on textile materials. For this, the current knowledge of the author about printed textile electronics using serigraphic technology has been taken as a basis. To this end, for the development of the thesis, in the first place the study of the necessary parameters for the application of this technology in different substrates has been carried out. Different suitable values for flexographic printing have been obtained from the study regarding whether the substrate is a fabric, a non-woven, a polymeric substrate or a silicone-coated paper. Secondly, the protocols that allow the integration of electrical inks with fabrics using flexographic technology have been defined. On the one hand, the impact of the structural parameters of a woven fabric on the conductivity of the printed ink has been studied. On the other hand, also the influence of the weft material on the conductivity of conductive-resistive elements was also studied. To do this, a controlled impression has been made on woven fabrics using the same conductive silver ink. Then both physical and electrical properties of the resulting samples have been analysed. It has been concluded that the higher the density of the textile, the lower final conductivity of the print is. Also, it has been defined that cotton is the least recommended material for electronic printing when using the flexography technique. Finally, towards the objective of developing a continuous temperature measurement system by electronic printing on flexible and elastic substrates, work has been carried out using screen printing for its translation into flexography. It has been possible to successfully develop a robust, low-consumption and comfortable system for patients that allows the continuous acquisition of temperature data. / Rodes Carbonell, AM. (2022). Dispositivos electrónicos impresos sobre sustratos textiles mediante la técnica de flexografía [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/189164 / Compendio

We report on the detailed electrical investigation of all-inkjet-printed thin-film transistor (TFT) arrays focusing on TFT failures and their origins. The TFT arrays were manufactured on flexible polymer substrates in ambient condition without the need for cleanroom environment or inert atmosphere and at a maximum temperature of 150 °C. Alternative manufacturing processes for electronic devices such as inkjet printing suffer from lower accuracy compared to traditional microelectronic manufacturing methods. Furthermore, usually printing methods do not allow the manufacturing of electronic devices with high yield (high number of functional devices). In general, the manufacturing yield is much lower compared to the established conventional manufacturing methods based on lithography. Thus, the focus of this contribution is set on a comprehensive analysis of defective TFTs printed by inkjet technology. Based on root cause analysis, we present the defects by developing failure categories and discuss the reasons for the defects. This procedure identifies failure origins and allows the optimization of the manufacturing resulting finally to a yield improvement.

Les dispositifs thermoélectriques, légers et flexibles, peuvent être particulièrement intéressants aujourd’hui dans le contexte de l’émergence de l’informatique ubiquitaire, ainsi que de la crise environnementale liée à la consommation d’énergie électrique. Cependant, beaucoup de problèmes doivent encore être résolus pour rendre les dispositifs de récupération de chaleur commercialement viables. Dans cette thèse nous avons élaboré une méthode de conception et de fabrication par impression jet d’encre de générateurs flexibles à base de semi-conducteurs organiques et hybrides. En premier lieu, les travaux ont été consacrés au développement de matériaux thermoélectriques efficaces, stables et synthétisés par voie liquide. Les stratégies d’optimisation employées reposent sur la modulation de la concentration de porteurs de charge et le contrôle de la morphologie microscopique du matériau. En second lieu, nous avons effectué un travail de conception et de modélisation de dispositifs thermoélectriques ainsi que de leurs paramètres géométriques en utilisant des outils numériques. La modélisation numérique a été réalisée par la méthode des éléments finis 3D et par couplage d’effets physiques multidimensionnels. L’aboutissement de notre projet a été la formulation des matériaux en encres pour la fabrication de générateurs thermoélectriques par la technique de dépôt par impression jet d’encre. Différentes structures et architectures ont été expérimentalement caractérisées et systématiquement comparées aux évaluations numériques. Ainsi, nous présentons une approche intégrale de conception et de fabrication de dispositifs thermoélectriques opérant à des températures proches de l’ambiant. / Flexible lightweight printed thermoelectric devices can become particularly interesting with the advent of ubiquitous sensing and within the context of current energy and environmental issues. However, major drawbacks of state of the art thermoelectric materials must be addressed to make waste heat recovery devices commercially feasible. In this PhD thesis, we’ve elaborated and described a method to fabricate optimized, fully inkjetprinted flexible thermoelectric generators based on organic and hybrid semiconductors. This research project can be divided into three stages: First is the development of effective, stable and solution-processed p-type and n-type thermoelectric materials. Our effort in optimizing thermoelectric materials were based on modulation of charge carrier concentration and on control of morphology. Second, design and modeling of thermoelectric devices and their geometric parameters using numerical simulation methods. Numerical simulations were based on a 3D-finite element analysis and simulation software for coupled physical problems to model and design thermoelectric devices. Finally, formulation of materials into ink in order to produce thermoelectric generators by inkjet printing deposition. Various structures and architectures were experimentally characterized and systematically compared to numerical evaluations. Hence, we produced an extensive study on designing and producing thermoelectric devices operating at near ambient temperature and conditions.

Inkjet printing has emerged from a digital graphic arts printing technology to become a versatile tool for the patterned deposition of functional materials. This thesis contributes to the research in the area of functional inkjet printing by focusing on two different topics: (i) inkjet printing of colloidal suspensions to study the principles of deposit formation and to develop deposits with photonic properties based on self-assembly, and (ii) the development of a reliable manufacturing process for all-inkjet-printed thin-film transistors, highlighting the importance of selection of materials and inks, print pattern generation, and the interplay between ink, substrate and printing conditions. (i) Colloidal suspensions containing nanospheres were applied as ink formulation in order to study the fundamental processes of layer formation and to develop structures with periodically arranged nanospheres allowing the modulation of electromagnetic waves. Evaporation-driven self-assembly was found to be the main driver for the formation of the final deposit morphology. Fine-tuning of inkjet process parameters allows the deposition of highly ordered structures of nanospheres to be arranged as monolayer, multilayer or even three-dimensional assemblies with a microscopic spherical shape. (ii) This thesis demonstrates the development of a manufacturing process for thin-film transistors based on inkjet printing. The knowledge obtained from the study with the colloidal nanospheres is used to generate homogeneous and continuous thin films that are stacked well-aligned to each other to form transistors. Industrial printheads were applied in the manufacturing process, allowing for the up-scaling of the manufacturing by printing of several thousands of devices, and thus the possibility to study the process yield as a function of printing parameters. The discrete droplet-by-droplet nature of the inkjet printing process imposes challenges on the control of printed patterns. Inkjet printing of electronic devices requires a detailed understanding about the process and all of the parameters that influence morphological or functional characteristics of the deposits, such as the selection of appropriate inks and materials, the orientation of the print pattern layout to the deposition process and the reliability of the inkjet process.

Cílem této práce je vývoj světelného zdroje založeného na technologii tlustostěnného elektroluminiscenčního panelu napájeného střídavým napětím (ACPEL). V současné době se jedná se o jedinou technologii založenou na metodách materiálového tisku vhodnou pro přípravu velkoplošných, flexibilních a vzorovaných zdrojů světla. Důraz je v této práci kladen na představení, prozkoumání a odstranění typických problémů, které jsou spojovány s touto technologií. Tyto problémy jsou omezený odstín barvy emitovaného světla a dlouhodobá stabilita elektroluminiscenčního prvku, který je vystaven vlivům prostředí. Rešeršní část dizertační práce je zaměřena na představení a identifikaci depozičních technik, vhodných pro reprodukovatelnou přípravu ACPEL panelů. Dalším cílem je identifikace fyzikálních parametrů, vhodných pro charakterizaci velkoplošných zdrojů světla. Praktickým cílem práce je nalezení vhodné metodologie pro popis a charakterizaci panelů, jakožto plošných světelných zdrojů. Fotometrická veličina jas L a spotřeba elektrické energie P byly vyhodnoceny jako vhodné parametry, určující aplikaci ACPEL panelů. Na modrém panelu bylo dosaženo maximální hodnoty jasu L = 133 cd•m2 při napětí Upp = 500 V a frekvenci f = 1000 Hz. Hodnoty spotřeby elektrické energie, vztažené na jednotkovou plochu panelů zkoumaných v této práci, jsou (7±3) mW. Tyto dosažené hodnoty dělají ze světelných zdrojů založených na ACPEL technologii zajímavé kandidáty pro různé aplikace. Vlivu rostoucí amplitudy a frekvence budícího napětí na dlouhodobou stabilitu panelů je důležitým cílem této práce. Pro popis stability byly zavedeny parametry L50 and L75. Bylo zjištěno, že rostoucí frekvence budícího napětí zkracuje životnost panelů. Laminovaný panel napájený napětím s přibližně trojnásobně vyšší frekvencí vykazoval přibližně třetinové hodnoty parametrů L50 a L75. Nejvyšších hodnot stabilitních parametrů dosahoval panel enkapsulován mezi skleněné pláty – přibližně sedminásobnou hodnotu oproti laminovanému panelu s trojnásobnou frekvencí. Optimální stability panelů lze dosáhnout při nastavení frekvence v rozmezí 400–800 Hz a zapouzdřením mezi sklo. Úzká paleta odstínů barev emitovaného světla je jeden z typických problémů, který dále zkoumán v dizertační práci. Tato práce zkoumá nadějnou metodu, přídavek vhodného materiálu pro konverzi barvy (CCM). Nový derivát diketopyrrolopyrrolu (DPP), absorbující v modré oblasti, byl přidán k modrému fosforu a byl pozorován sedminásobný narůst hodnot absolutního spektrálního ozáření v oblasti vlnových délek odpovídajících maximální emisi CCM materiálu. Jednoduchost přípravy vyvinutých zdrojů světla spolu s velmi nízkou spotřebou a vysokou dobou života dělají z ACPEL panelů zajímavé kandidáty pro podsvícení prvků například v automobilovém průmyslu, pro dekorativní osvětlení, pro „branding“ – zvýraznění reklamních značek.

Topic of the thesis is the production of unipolar digital circuits by means of mass-printing technologies. For this purpose accumulation-mode and depletion-mode field-effect transistors have been used. To realize depletion-mode field-effect transistors charges are injected and stored in the gate-dielectric. Consequently, the charge transport on the semiconductor-dielectric interface is influenced and the threshold voltage can be controlled. To inject charges into the dielectric different technologies have been used and will be discussed in terms of their process parameters. Finally, fully-printed digital circuits with enhanced performance are introduced. / Gegenstand der vorliegenden Arbeit ist die drucktechnische Herstellung von unipolaren digitalen Schaltungen durch eine Kombination von organischen Feldeekttransistoren vom Anreicherungs- und Verarmungstyp. Zur Realisierung von Transistoren vom Verarmungstyp werden Überschussladung in den Gate- Isolator eingebracht und gespeichert, wodurch der Ladungstransport im Transistorkanal insbesondere die Schwellspannung beeinflusst wird. Es werden verschiedene Aufladungstechnologien und deren Prozessparameter diskutiert. Abschließend werden vollständig mit Massendruckverfahren prozessierte, digitale Schaltungen mit verbesserter Signalübertragungscharakteristik vorgestellt.

Inkjet printing has emerged from a digital graphic arts printing technology to become a versatile tool for the patterned deposition of functional materials. This thesis contributes to the research in the area of functional inkjet printing by focusing on two different topics: (i) inkjet printing of colloidal suspensions to study the principles of deposit formation and to develop deposits with photonic properties based on self-assembly, and (ii) the development of a reliable manufacturing process for all-inkjet-printed thin-film transistors, highlighting the importance of selection of materials and inks, print pattern generation, and the interplay between ink, substrate and printing conditions. (i) Colloidal suspensions containing nanospheres were applied as ink formulation in order to study the fundamental processes of layer formation and to develop structures with periodically arranged nanospheres allowing the modulation of electromagnetic waves. Evaporation-driven self-assembly was found to be the main driver for the formation of the final deposit morphology. Fine-tuning of inkjet process parameters allows the deposition of highly ordered structures of nanospheres to be arranged as monolayer, multilayer or even three-dimensional assemblies with a microscopic spherical shape. (ii) This thesis demonstrates the development of a manufacturing process for thin-film transistors based on inkjet printing. The knowledge obtained from the study with the colloidal nanospheres is used to generate homogeneous and continuous thin films that are stacked well-aligned to each other to form transistors. Industrial printheads were applied in the manufacturing process, allowing for the up-scaling of the manufacturing by printing of several thousands of devices, and thus the possibility to study the process yield as a function of printing parameters. The discrete droplet-by-droplet nature of the inkjet printing process imposes challenges on the control of printed patterns. Inkjet printing of electronic devices requires a detailed understanding about the process and all of the parameters that influence morphological or functional characteristics of the deposits, such as the selection of appropriate inks and materials, the orientation of the print pattern layout to the deposition process and the reliability of the inkjet process.:Bibliography II Abstract III Preface and acknowledgements IV On the major results and novelty of the thesis VII Table of contents VIII List of abbreviations and symbols X List of figures XII List of tables XX 1 Introduction 1 2 Fundamentals 6 2.1 Inkjet printing – an overview 6 2.2 Piezoelectric inkjet technology and a historical overview of inkjet printing 10 2.3 Pattern and film formation in inkjet printing under the scheme of self-assembly 20 2.4 Inkjet printing of colloidal nanospheres 27 2.5 Spherical colloidal assemblies 29 2.6 All-inkjet-printed thin film transistors 31 3 Experimental section 35 3.1 Inkjet printing systems and accessories 35 3.2 Inks and substrates 38 3.3 Print patterns 43 3.4 Post-processing 46 3.5 Optical, morphological and functional characterization 47 4 Inkjet printing of colloidal nanospheres: Evaporation-driven self-assembly based on ink-substrate interaction 49 4.1 Single droplet deposit morphology: Interaction of substrate and ink 49 4.2 Optical properties of inkjet-printed single droplet monolayers and multilayers 54 5 Inkjet printing of colloidal nanospheres: Evaporation-driven self-assembly of SCAs independent on substrate properties 58 5.1 Inkjet printing of spherical colloidal assemblies and their identification 58 5.2 Fine-tuning of the waveform applied to the printhead 60 5.3 Interaction of substrate and ink 66 5.4 Structures, morphologies and materials of SCAs 68 5.5 Optical properties of SCAs 76 6 Inkjet printing of TFTs: Process development and process reliability 80 6.1 Influence of print layout design 80 6.2 Selection of materials and inks 91 6.3 Manufacturing workflow and electrical TFT parameters 108 6.4 Manufacturing yields and failure origins 113 7 Summary and conclusion 124 References 127 Documentation of authorship and contribution of third persons 149 List of publications 151 APPENDIX A Formation of colloidal hemispheres on hydrophobic PTFE substrates 161 APPENDIX B Inkjet-printed higher-order cluster with N < 100 using BL280 162 APPENDIX C Inkjet-printed SCAs based on BS305 with similar sizes and inkjet-printed SCA based on PSC221 163 APPENDIX D Microreflectance spectra of SCAs and the processing of the spectra using the Savitzky-Golay filter with a second-order polynomial and a moving window of 100 data points 164 APPENDIX E Waveform, drop ejection and photographs of the printed patterns of Sun Chemical EMD5603 and UTDots UTDAgIJ1 165 APPENDIX F Smoothening of profiles obtained by profilometry of EMD5603 and UTDAgIJ1 and dependency of print resolution of layer height 166 APPENDIX G Percentage of area increase based on a 4 mm x 4 mm digital print pattern using the ink Harima NPS-JL and influence of print resolution and post-treatment temperature on sheets resistance 168 APPENDIX H Cross-sectional view of a TFT stack printed with the dielectric Sun Chemical EMD6415 that shows high layer thickness due to ink contraction after the deposition as presented in Figure 46 169 APPENDIX I Influence of printing parameters on the dielectric layer applied in the TFT 170 APPENDIX J Reduction of channel length by decreasing the S-D electrode channel length in the print pattern layout 171