The objectives of the proposed research are to model, optimize, and control variable frequency microwave (VFM) curing of polymer dielectrics. With an increasing demand for new materials and improved material properties, there is a corresponding demand for new material processing techniques that lead to comparable or better material properties than conventional methods. Presently, conventional thermal processing steps can take several hours. A new thermal processing technique known as variable frequency microwave curing can perform the same processing steps in minutes without compromising the intrinsic material properties. Current limitations in VFM processing include uncertain process characterization methods, lack of reliable temperature measuring techniques, and the lack of control over the various processes occurring in the VFM chamber. Therefore, the proposed research addressed these challenges by: (1) development of accurate empirical process models using statistical experimental design and neural networks; (2) recipe synthesis using genetic algorithms; (3) implementation of an acoustic temperature sensor for VFM process monitoring; and (4) implementation of neural control strategies for VFM processing. and #8194;

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In this thesis, new all-printed capacitors are developed for the applications of energy storage, filter, and resonant circuits by using new dielectric material and an advanced technology. The innovative devices provide satisficing electrical performances with high breakdown voltages and capacitance densities. The main body of this thesis is divided in three parts. The first part is to introduce the fundamental background of printing technologies, electrical capacitors and printable materials. Among all the printing technologies, direct writing family is the most advantageous in the small-scale and fast production of printed electronics due to the properties of masterless processing, digital control, and print-on-demand. Both inkjet printing and ultrasonic fluid dispensing applied in this work are grouped into the direct writing family. A cross-linkable dielectric material poly(methyl methacrylate)84/(4-benzoylphenyl methacrylate)16 [P(MMA84/BPMA16)] exhibits the optimized chemical and mechanical stabilities in comparison with uncross-linked poly(methyl methacrylate) (PMMA). Poly(vinylidene fluoride-co-trifluoro ethylene) [P(VDF-TrFE)] exhibits a high dielectric constant of 16. The great advantages of both polymeric dielectrics make them ideal for printed electronics. The second part is devoted to the preparation of printed thin-film capacitors by providing four different layouts and architectures for multiple electronic applications. The printing setup, process setting and steps are summarized in detail. The following part which is the major content of this thesis is divided into two aspects: in the first aspect, the intriguing new form of continuous solution dispensing technology, ultrasonic fluid dispensing, is demonstrated as an alternative printing technology for the commonly applied ones. In comparison with the widely-used inkjet printing, continuous solution dispensing is the most advantageous in thin-film capacitor processing with metal nanoparticle and polymer dielectric inks. It enables precise pattern transfers with low surface roughness, small feature size (as small as 5 μm), and accurate positioning (5 μm resolution). Most importantly, problems due to discrete droplets and nozzle clogging in inkjet printing are avoided in continuous solution dispensing. All the inks applied for printed capacitors in this work are printed successfully with this innovating technology. Direct printing on demand and rapid switching among different inks are some other attributes of this printing technology that enable high throughput. The second aspect of this part is to characterize and evaluate the fabricated capacitors. The measured values include capacitor dimension, dielectric strength, capacitance density, energy density, charge/discharge behavior and so on. In summary, this work provides not only the use of the advantageous materials P(MMA84/BPMA16) and P(VDF-TrFE) in high-performance capacitors, but also paves the way of developing thin-film capacitors with a new continuous solution dispensing technology which makes the low-cost and high-quality manufacture of printed devices possible.

Tato diplomová práce zkoumá flexibilní materiál k produkci elektřiny založený na piezoelektrickém polymeru Polyvinylidenfluorid (PVDF). Inkorporací piezoaktivní keramiky lze vlastnosti piezoelektrického polymeru PVDF významně zlepšit a převést na užitečnou elektrickou energii. PVDF byl vytvořen elektrostatickým zvlákňováním do vláken o tloušťce 1,5-0,3 µm a poté studován různými analytickými metodami. Tato práce nabízí popis elektrostatického zvlákňování, přípravu vzorků a teoretický úvod do analytických metod, kterým byly vzorky podrobeny. Morfologie a distribuce nanostrukturované keramiky do polymerní matrice PVDF byla pozorována použitím skenovací elektronové mikroskopie (SEM) a energiově disperzní spektroskopie (EDX). Pro tvorbu fáze a podrobné fázové složení byly vzorky charakterizovány infračervenou spektroskopií s Fourierovou transformací (FTIR). Práce také obsahuje analýzu s použitím Ramanovy spektroskopie, metody používané k identifikaci a porovnání chemických sloučenin. Elektrické vlastnosti byly studovány dielektrickou spektroskopií a je poskytnuta korelace se složením. Jednotlivé komponenty dotovaných vláken jsou charakterizovány a vyhodnocovány v souvislosti s jejich budoucím využitím v senzorech.

In this thesis, new all-printed capacitors are developed for the applications of energy storage, filter, and resonant circuits by using new dielectric material and an advanced technology. The innovative devices provide satisficing electrical performances with high breakdown voltages and capacitance densities. The main body of this thesis is divided in three parts. The first part is to introduce the fundamental background of printing technologies, electrical capacitors and printable materials. Among all the printing technologies, direct writing family is the most advantageous in the small-scale and fast production of printed electronics due to the properties of masterless processing, digital control, and print-on-demand. Both inkjet printing and ultrasonic fluid dispensing applied in this work are grouped into the direct writing family. A cross-linkable dielectric material poly(methyl methacrylate)84/(4-benzoylphenyl methacrylate)16 [P(MMA84/BPMA16)] exhibits the optimized chemical and mechanical stabilities in comparison with uncross-linked poly(methyl methacrylate) (PMMA). Poly(vinylidene fluoride-co-trifluoro ethylene) [P(VDF-TrFE)] exhibits a high dielectric constant of 16. The great advantages of both polymeric dielectrics make them ideal for printed electronics. The second part is devoted to the preparation of printed thin-film capacitors by providing four different layouts and architectures for multiple electronic applications. The printing setup, process setting and steps are summarized in detail. The following part which is the major content of this thesis is divided into two aspects: in the first aspect, the intriguing new form of continuous solution dispensing technology, ultrasonic fluid dispensing, is demonstrated as an alternative printing technology for the commonly applied ones. In comparison with the widely-used inkjet printing, continuous solution dispensing is the most advantageous in thin-film capacitor processing with metal nanoparticle and polymer dielectric inks. It enables precise pattern transfers with low surface roughness, small feature size (as small as 5 μm), and accurate positioning (5 μm resolution). Most importantly, problems due to discrete droplets and nozzle clogging in inkjet printing are avoided in continuous solution dispensing. All the inks applied for printed capacitors in this work are printed successfully with this innovating technology. Direct printing on demand and rapid switching among different inks are some other attributes of this printing technology that enable high throughput. The second aspect of this part is to characterize and evaluate the fabricated capacitors. The measured values include capacitor dimension, dielectric strength, capacitance density, energy density, charge/discharge behavior and so on. In summary, this work provides not only the use of the advantageous materials P(MMA84/BPMA16) and P(VDF-TrFE) in high-performance capacitors, but also paves the way of developing thin-film capacitors with a new continuous solution dispensing technology which makes the low-cost and high-quality manufacture of printed devices possible.

Organic field-effect transistors (OFETs) are essential devices for the realization of novel electronic applications based on organic materials. Recent years have brought tremendous improvements regarding the organic semiconductor (OSC) with charge carrier mobilities around 10 cm²/Vs. Yet, several challenges are needed to be addressed in order to enable technologies of the future that are based on high-performance organic transistors. In this work, C8-BTBT, a high-mobility material that has gained increasing interest in the last few years, is used to prepare films with state-of-the art charge-carrier mobility and above. For this purpose, the solution-shearing method—a meniscus-guided technique that is capable to produce highly aligned, crystalline films—is applied. Based on these charge-transport layers with an estimated intrinsic mobility of up to 12 cm²/Vs, several strategies towards their exploitation for high-performance organic transistors are investigated. Among the relevant parameter, channel length, contact resistance and gate dielectric capacitance are the three aspects that are addressed. The solution-shearing method is further applied to the realization of solution-deposited polymer dielectrics. High-capacitance films with maximum values of about 280 nF/cm² are fabricated and used to produce low-voltage OFETs that can operate at -1V. In order to increase the devices’ transconductance, a novel patterning methodology to achieve sub-micrometre channel lengths is investigated. Using this technique, working devices with a channel length of 500 nm are shown. The compatibility of this process with the solution-shearing method for the fabrication of high-performance semiconducting and gate dielectric films is one of its major advantages. One of the limiting device parameters is the contact resistance as is clearly observable by the restricted current scaling that is observed for lower channel length. Hence, the interface of OSC and source/drain contacts is investigated. Even though an ultimate solution for very low contact resistance remains to be developed, important aspects for its further enhancement are deduced in this work. As an important first experimental result, this thesis describes a short-channel device architecture that is compatible with solution-shearing of high-performance films with its full potential yet to be explored in future work. / Organische Feld-Effekt Transistoren (OFETs) sind grundlegende Bestandteile für die Entwicklung neuerartiger Technologien auf der Basis von organischen Halbleitermaterialien. Insbesondere während der letzten Jahre haben diese Materialien einschlägige Verbesserungen erfahren und erreichen heute Ladungsträgermobilitäten um die 10 cm²/Vs. Um dies für die Umsetzung neuartiger Technologien zu nutzen, müssen jedoch noch einige Herausforderungen überwunden werden. Diese Arbeit leistet einen Beitrag in diese Richtung. Unter Anwendung eines der wohl populärsten Halbleitermaterialien der letzen Jahre mit der chemischen Bezeichnung C8-BTBT, wird die Herstellung von hochqualitativen Halbleiterfilmen mittels Flüssigprozessierung gezeigt. Mit der sogenannten „Solution-Shearing“ Methode – eine Abscheidetechnik, die über die Kontrolle eines trocknenden Meniskus hochkristalline und ausgerichtete Schichten erzeugen kann – ist es möglich Dünnschichtbauelemente mit abgeschätzten, intrinsischen Ladungsträgermobilitäten von bis zu 12 cm²/Vs zu erzeugen. Um diese hoch-qualitativen Filme für die Herstellung von leistungsfähigen Transistoren zu nutzen, werden mehrere relevante Parameter betrachtet, darunter die Kanallänge, der Kontaktwiderstand und das Gate-Dielektrikum. Im Speziellen wird die Abscheidung des Dielektrikums mittels der „Solution-Shearing“ Methode untersucht. Es kann gezeigt werden, dass dies für die Herstellung von qualitativ hochwertigen Filmen mit Kapazitäten bis zu 280 nF/cm² genutzt werden kann. Angewendet in OFETs erlauben diese Schichten den Betrieb bei sehr geringen Spannungen von -1V. Um die Transkonduktanz der Transistoren zu erhöhen wird zudem eine mit der „Solution-Shearing“ Methode kompatible Source/Drain-Strukturierungsmethode untersucht. Diese ermöglicht Kanallängen unter einem Mikrometer und konnte hier für die Herstellung von funktionierenden Transistoren mit einer Kanallänge bis zu nur 500 nm angewendet werden. Eine der limitierenden Transistorkenngrößen ist der Kontaktwiderstand, wie durch die abweichende Skalierung des Stromes mit verringerter Kanallänge deutlich wird. Aus diesem Grund wurde auch die Grenzfläche zwischen Halbleiter und Source/Drain-Kontakten näher untersucht. Allerdings verbleibt die Entwicklung einer effektiven Methode zur Reduzierung des Kontaktwiderstandes ein Projekt für zukünftige Untersuchungen, auch wenn die vorliegende Arbeit einige wichtige Anhaltpunkte für mögliche Strategien liefert. Als wichtiges erstes Resultat liefert die vorliegende Arbeit eine Beschreibung zur Herstellung funktionsfähiger Kurzkanal-OFETs mittels „Solution-Shearing“, deren volles Potential aber in der Zukunft weiter untersucht werden muss.