Das unerwünschte Aufwachsen oder Anhaften von Eis an z.B. Windenergieanlagen und Wärmetauschern kann zum Funktionsverlust oder zur temporären Stilllegung der gesamten technischen Anlage führen. Bekannte Abwehrmechanismen sind das aktive Beheizen der Oberflächen oder der Einsatz von Enteisungschemikalien. Um den Verbrauch der hierfür benötigten elektrischen Energie oder Enteisungsmittel zu minimieren, werden in zunehmendem Maß passive Oberflächenbeschichtungen zur Gefrierverzögerung und Adhäsionsminimierung entwickelt. Der Einsatz pyroelektrischer Materialien bietet einen Lösungsansatz, der über bisher bekannte Abwehrstrategien hinausgeht. Es wird angenommen, dass pyroelektrisch generierte Oberflächenladungen während der Abkühlung entweder förderlich oder verzögernd auf die Eiskeimbildung wirken können. Dünne Schichten aus pyroelektrischem Poly-(Vinylidenfluorid - co - Trifluorethylen) haben wegen ihrer leichten Verarbeitbarkeit, hohen Flexibilität und pyroelektrischen Eigenschaften Interesse an ihrer Anwendung als funktionelle Beschichtung geweckt. Für eine industrielle Anwendung von P(VDF-TrFE) ist jedoch ein vertieftes Verständnis darüber erforderlich, wie sich der Beschichtungsprozess auf die resultierende Kristallinität, kristallographische Orientierung und Rauheit auswirkt. Die Morphologie teilkristalliner P(VDF-TrFE)-Beschichtungen wurde in dieser Arbeit in Abhängigkeit der Beschichtungsmethode, des Lösungsmittels, der Schichtdicke und der Wärmebehandlung mithilfe von Röntgenweitwinkelstreuung, Röntgenreflektometrie und Infrarot-Reflexions-Absorptions-Spektroskopie untersucht. Mit Hilfe von Rasterkraftmikroskopie- und Kontaktwinkel-Messungen wurden die resultierende Topographie und Rauheit der Schichten überprüft. Auf Grundlage der Ergebnisse dieser Messungen kann die dominierende edge-on Orientierung der P(VDF-TrFE)-Polymerketten entweder mit einem transkristallin-artigen Mechanismus oder Konfinement-Effekten erklärt werden. An den P(VDF-TrFE)-Dünnschichten wurde eine Vielzahl von Vereisungsexperimenten mit aufliegenden Wassertropfen durchgeführt, um den Einfluss der verschiedenen Schichtparameter wie Polarisierungsrichtung, Schichtdicke, verwendetes Lösungsmittel, Beschichtungstechnologie, Substrat und Wärmebehandlung auf die erreichbare Gefrierverzögerung unabhängig voneinander zu ermitteln. Die Rauheit der Schichten sowie substratspezifische Entnetzungserscheinungen veränderten hierbei signifikant die Verteilung der Gefriertemperaturen von Wassertropfen in Kontakt mit den P(VDF-TrFE)-Dünnschichten. Im Gegensatz dazu wurde kein signifikanter Einfluss der Dicke, Morphologie oder des pyroelektrischen Effekts auf die erreichbare Gefrierverzögerung gefunden. Es kann demnach geschlussfolgert werden, dass die heterogene Eiskeimbildung stärker durch lokale Rauheiten im nm-Bereich beeinflusst wird als durch integrale Eigenschaften wie beispielsweise Oberflächenladungen. Die Eisadhäsion auf P(VDF-TrFE) wird hauptsächlich durch Rauheiten im µm-Bereich, die Umgebungstemperatur und den Ionengehalt der flüssigen Phase bestimmt. Auch hier konnte kein signifikanter Einfluss geladener Oberflächen auf die Haftfestigkeit von Eis ausfindig gemacht werden. Statistische Tests ergaben, dass die Verteilung der Gefriertemperaturen unabhängiger Tropfen auf Oberflächen einem Spezialfall der Extremwertstatistik, der so genannten Gumbel-Verteilung, entspricht. Dies ermöglicht die Definition neuartiger Temperaturkennwerte für die Weiterentwicklung und Prüfung von Anti-Eis-Oberflächen.:Inhaltsverzeichnis 1. Einleitung und Motivation 2. Stand der Forschung 2.1. Pyroelektrika 2.1.1. Der pyroelektrische Effekt 2.1.2. Pyroelektrische Werkstoffe 2.1.3. Stabilität pyroelektrischer Materialien in wässrigen Medien 2.1.4. PVDF und P(VDF-TrFE) 2.2. Elektrochemische Doppelschicht 2.2.1. Aufbau und Modelle 2.2.2. Ursachen für Ladungen an Grenzflächen 2.2.3. Isoelektrischer Punkt und Ladungsnullpunkt 2.2.4. Orientierung von Wassermolekülen in der EDL 2.3. Vereisung 2.3.1. Wasser und Eis 2.3.2. Anti-Eis Strategien 2.3.3. Gefrierverzögerung 2.3.4. Eisadhäsion 2.4. Pyroelektrika in wässrigen Medien 2.4.1. Charakterisierungsmöglichkeiten 2.4.2. Anwendungsfelder 3. Materialien und Methoden 3.1. Materialien 3.2. Herstellung pyroelektrischer Beschichtungen 3.3. Schichtcharakterisierung 3.4. Vereisungsneigung 3.5. Statistische Methoden 4. Ergebnisse 4.1. Charakterisierung der P(VDF-TrFE) Beschichtungen 4.1.1. Schichtdicke (Ellipsometrie) und mechanische Eigenschaften 4.1.2. Morphologie (DSC, GIWAXS, XRR, IRRAS) 4.1.3. Elektrische Eigenschaften 4.1.4. Topographie (AFM und Kontaktwinkel) 4.2. Vereisungsneigung von P(VDF-TrFE) 4.2.1. Gefrierverzögerung 4.2.2. Eisadhäsion 4.3. Vergleichsmessungen auf poliertem Aluminium 4.3.1. Kontaktwinkel 4.3.2. Gefrierverzögerung 4.3.3. Eisadhäsion 5. Diskussion 5.1. Schichtherstellung, -charakterisierung und -eignung 5.1.1. Schichtdicke 5.1.2. Eignung der Charakterisierungsmethoden 5.1.3. Vergleich von Dip- und Spin-Coating 5.1.4. Eignung von P(VDF-TrFE) für Anti-Eis-Beschichtungen 5.2. Anti-Eis-Eigenschaften 5.2.1. Erreichbare Gefrierverzögerung 5.2.2. Eisadhäsion 6. Zusammenfassung und Ausblick Literaturverzeichnis Abbildungsverzeichnis Tabellenverzeichnis Symbol- und Abkürzungsverzeichnis Veröffentlichungen Anhang / Active de-icing of technical surfaces, such as for wind turbines and heat exchangers, currently requires the usage of heat or chemicals. Passive coating strategies that either postpone the freezing of covering water droplets or lower the ice adhesion strength would be beneficial in order to save costs and energy. One hypothesis is that pyroelectric active materials can either delay or promote heterogeneous ice nucleation because of the surface charges generated when these materials are subject to a temperature change. Pyroelectric poly-(vinylidene fluoride - co - trifluoroethylene) P(VDF-TrFE) thin films have created interest in their application because of their easy processibility, high flexibility and ferroelectric properties. The industrial application of P(VDF-TrFE) requires an understanding of the deposition process of films and in particular the resulting crystallinity, crystallographic orientation and roughness. In this work it has been proposed that an interface-mediated crystallization process occurs when P(VDF-TrFE) thin films are deposited from a solvent, resulting in a dominantly edge-on orientation caused either by a transcrystallinity mechanism or confinement effect. The morphology of the semi-crystalline thin film was studied as a function of the deposition method, solvent, film thickness and annealing temperature by grazing incidence wide-angle X-ray scattering, X-ray reflectometry and infrared reflection absorption spectroscopy. Atomic force microscopy measurements were used to examine the resulting topography and contact angle measurements to additionally verify the low roughness of the coatings. Freezing experiments with water droplets subjected to a cooling rate of 1K/min were made on P(VDF-TrFE) coatings in order to separate the effect of the different film parameters such as the poling direction, film thickness, used solvent, deposition process, underlying substrate and annealing temperature on the achievable supercooling. The topography and substrate-specific dewetting effects significantly changed the distribution of freezing temperatures of water droplets in contact with the P(VDF-TrFE) thin films. In contrast, no significant effect of the thickness, morphology or pyroelectric effect of the as-prepared domain-state on the freezing temperatures was found. Statistical tests revealed that the distribution of freezing temperatures of individual droplets deposited on surfaces match a special case of extreme-value statistics, the so-called Gumbel-distribution. This allows for the definition of novel parameters for the development and testing of anti-icing surfaces. The adhesion strength of ice to P(VDF-TrFE) is mainly determined by the topography, temperature and ion-content of the liquid phase. In contrast, surface charges do not significantly influence the ice adhesion strength.:Inhaltsverzeichnis 1. Einleitung und Motivation 2. Stand der Forschung 2.1. Pyroelektrika 2.1.1. Der pyroelektrische Effekt 2.1.2. Pyroelektrische Werkstoffe 2.1.3. Stabilität pyroelektrischer Materialien in wässrigen Medien 2.1.4. PVDF und P(VDF-TrFE) 2.2. Elektrochemische Doppelschicht 2.2.1. Aufbau und Modelle 2.2.2. Ursachen für Ladungen an Grenzflächen 2.2.3. Isoelektrischer Punkt und Ladungsnullpunkt 2.2.4. Orientierung von Wassermolekülen in der EDL 2.3. Vereisung 2.3.1. Wasser und Eis 2.3.2. Anti-Eis Strategien 2.3.3. Gefrierverzögerung 2.3.4. Eisadhäsion 2.4. Pyroelektrika in wässrigen Medien 2.4.1. Charakterisierungsmöglichkeiten 2.4.2. Anwendungsfelder 3. Materialien und Methoden 3.1. Materialien 3.2. Herstellung pyroelektrischer Beschichtungen 3.3. Schichtcharakterisierung 3.4. Vereisungsneigung 3.5. Statistische Methoden 4. Ergebnisse 4.1. Charakterisierung der P(VDF-TrFE) Beschichtungen 4.1.1. Schichtdicke (Ellipsometrie) und mechanische Eigenschaften 4.1.2. Morphologie (DSC, GIWAXS, XRR, IRRAS) 4.1.3. Elektrische Eigenschaften 4.1.4. Topographie (AFM und Kontaktwinkel) 4.2. Vereisungsneigung von P(VDF-TrFE) 4.2.1. Gefrierverzögerung 4.2.2. Eisadhäsion 4.3. Vergleichsmessungen auf poliertem Aluminium 4.3.1. Kontaktwinkel 4.3.2. Gefrierverzögerung 4.3.3. Eisadhäsion 5. Diskussion 5.1. Schichtherstellung, -charakterisierung und -eignung 5.1.1. Schichtdicke 5.1.2. Eignung der Charakterisierungsmethoden 5.1.3. Vergleich von Dip- und Spin-Coating 5.1.4. Eignung von P(VDF-TrFE) für Anti-Eis-Beschichtungen 5.2. Anti-Eis-Eigenschaften 5.2.1. Erreichbare Gefrierverzögerung 5.2.2. Eisadhäsion 6. Zusammenfassung und Ausblick Literaturverzeichnis Abbildungsverzeichnis Tabellenverzeichnis Symbol- und Abkürzungsverzeichnis Veröffentlichungen Anhang

The ferro-, pyro- and piezoelectric properties of poly(vinylidene fluoride-co-trifluoroethylene) P(VDF-TrFE) have created interest with regard to its application in aqueous and ambient surroundings for sensors, functional coatings, and in the field of life sciences. P(VDF-TrFE) thin films are usually applied via spin-coating, but dip-coating will be advantageous especially for irregularly shaped substrates. The morphology of dip- and spin-coated semi-crystalline thin films is studied as a function of both the film thickness and the annealing temperature. The characterization of the films is carried out by grazing incidence wide-angle X-ray scattering (GIWAXS), X-ray reflectometry (XRR), and infrared reflection absorption spectroscopy (IRRAS). Atomic force microscopy measurements (AFM) are used to examine the resulting topography. It is found that both spin- and dip-coated thin films crystallize in the desired edge-on orientation, but the overall crystallinity after dip-coating is decreased compared to the spin-coated films of comparable thickness and the resulting roughness is increased. The higher roughness is most probably caused by the slower evaporation of the solvents and a secondary crystallization process at the air-polymer interface.

This thesis presents actuators used in autonomous microsystems. Characteristic for all actuators presented is the low drive voltage and the low power consumption. Different motion mechanisms have been studied and applied in various locomotion modules for microrobots. High resolution movement of a monolithic piezoceramic PZT rotational arm module, using a quasi-static motion mechanism, was demonstrated in a 10x10x20 mm3 autonomous robot. The rotational arm comprises multilayer PZT bimorphs and is fabricated by a wet-building technology. The multilayer approach enables operation of the modules at the low drive voltages provided by the robot electronics. In addition a locomotion module has been designed and fabricated based on the above principles. A three-legged locomotion module with piezoceramic unimorphs, moving by tapping the legs against the floor, has been investigated. Characteristics such as low power consumption, high velocities, low drive voltages and a high weight carrying capability were demonstrated using a resonant motion mechanism. Highly miniaturized three-legged locomotion modules were developed for a 3x3x3 mm3 autonomous microrobot. The modules comprise a multilayer structure of the electroactive copolymer P(VDF-TrFE) on a flexible printed circuit board (FPC) substrate. A novel multilayer fabrication process suitable for mass production was used. It is based on sequential deposition of spun cast copolymer with evaporated aluminum electrodes. Reactive ion etching is used to microstructure the copolymer and the FPC. The mechanical deformability of the FPC is exploited when folding the 2D FPC-multilayer assembly into 3D locomotion modules. Locomotion was demonstrated by moving a glass slider corresponding to the robot weight. A modular building technology for microsystems is presented. It uses surface mounting technology and conductive adhesives to assemble modules on a double-sided FPC. Complex geometries were achieved by subsequent folding the FPC. The feasibility of the technology was demonstrated by assembly of the 3x3x3 mm3 autonomous microrobots.

Chip scale refrigeration system is critical for the development of electronics with the rapid increase of power consumption and substantial reduction of device size, resulting in an emergent demand on novel cooling technologies with a high efficiency for the thermal management. In this thesis, active refrigeration devices based on Stirling cycle and an electrocaloric material, are designed and investigated to achieve a high cooling performance. Firstly, a new Stirling micro-refrigeration system composed of arrays of silicon MEMS cooling elements is designed and evaluated. The cooling elements are fabricated in a stacked array on a silicon wafer. A regenerator is placed between the compression (hot side) and expansion (cold side) diaphragms, which are driven electrostatically. Under operating conditions, the hot and cold diaphragms oscillate sinusoidally and out of phase such that heat is extracted to the expansion space and released from the compression space. A first-order of thermodynamic analysis is performed to study the effect of geometric parameters. Losses due to regenerator non-idealities and chamber heat transfer limitation are estimated. A multiphysics computational approach for analyzing the system performance that considers compressible flow and heat transfer with a large deformable mesh is demonstrated. The optimal regenerator porosity for the best system COP (coefficient of performance) is identified. To overcome the computational complexity brought about by the fine pillar structure in the regenerator, a porous medium model is used to allow for modeling of a full element. The analysis indicates the work recovery of the system and the diaphragm actuation are main challenges for this cooler design.The pressure drop and friction factor of gas flow across circular silicon micro pillar arrays fabricated by deep reactive ion etch (DRIE) process are investigated. A new correlation that considers the coupled effect of pillar spacing and aspect ratio, is proposed to predict the friction factor in a Reynolds v number range of 1-100. Silicon pillars with large artificial roughness amplitudes is also fabricated, and the effect of the roughness is studied in the laminar flow region. The significant reduction of pressure drop and friction factor indicates that a large artificial roughness could be built for pillar arrays in the regenerator to enhance the micro-cooler efficiency. The second option is to develop a fluid-based refrigeration system using an electrocaloric material poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) [P(VDF-TrFE-CFE)] terpolymer. Each cooling element includes two diaphragm actuators fabricated in the plane of a silicon wafer, which drive a heat transfer fluid back and forth across terpolymer layers that are placed between them. Finite element simulations with an assumption of sinusoidal diaphrahm motions are conducted to explore the system performance detailedly, including the effects of the applied electric field, geometric dimensions, operating frequency and externally-applied temperature span. Multiphysics modeling coupled with solid-fluid interaction, heat transfer, electrostatics, porous medium and moving mesh technique is successfully performed to verify the thermal modeling feasibility. The electrocaloric effect in thin films of P(VDF-TrFE-CFE) terpolymer is directly measured by infrared imaging at ambient conditions. At an electric field of 90 V/μm, an adiabatic temperature change of 5.2 °C is obtained and the material performance is stable over a long testing period. These results suggest that application of this terpolymer is promising for micro-scale refrigeration.

Orientador: Dante Luis Chinaglia / Banca: Gerson Santarine / Banca: Valtencir Zucolloto / Resumo: As novas tecnologias para a construção de telas e displays têm permitido reduzir o consumo de energia, o peso e a espessura, como também melhorar a eficiência e flexibilidade se comparado aos antigos monitores de CRTs e até mesmo aos atuais displays de cristal líquido. Dentre estas novas tecnologias destacam-se as que utilizam materiais orgânicos (OLED) ou orgânicos poliméricos (PLED) não somente por suas possibilidades de aplicações industriais, mas também por permitirem o desenvolvimento das ciências básica e aplicada. Seguindo uma linha alternativa, propomos, neste trabalho, um novo compósito híbrido, resultante da combinação de uma fase polimérica e uma fase inorgânica, que, do nosso ponto de vista também poderá contribuir para o desenvolvimento dessa nova geração de displays e telas. Este compósito é formado pela blenda de um polímero condutor dopado, a PANI (polianilina) ou POMA (poli(o-metóxi anilina)), e um polímero isolante, o P(VDF-TrFE) poli(vinilideno-co-trifluoretileno), na qual micro partículas de Zn2SiO4:Mn (SZF) foram adicionadas. Para o desenvolvimento desse novo compósito, estudamos cada um de seus elementos constituintes, notadamente quanto ao seu modo de preparo, características morfológicas e propriedades elétricas. Como resultado final, obtivemos dispositivos constituídos de uma única camada do compósito híbrido depositado por espalhamento sobre um substrato de ITO/FTO, acrescido, ainda, de um eletrodo de alumínio depositado por evaporação. Para a caracterização destes dispositivos foram realizadas medidas de condutividade elétrica, luminescência (L) e fotoluminescência (PL). Os compósitos PANI/P(VDF-TrFE)/SZF 05/95/80 e POMA/P(VDF-TrFE)/SZF 25/75/80 com condutividade elétrica da ordem de 10-3 S/m foram os que melhor se adequaram para a construção dos dispositivos. Os espectros de L e PL apresentaram um pico em ? = 538... (Resumo completo, clicar acesso eletrônico abaixo). / Abstract: New technologies recently applied to the fabrication of organic screens and displays have allowed the manufacture of lighter, thinner monitors in comparison to either the conventional cathodic rays tube (CRTs) or the liquid crystal displays (LCDs). In addition, displays based on organic materials (the so-called organic light emitting displays (OLEDs and the polymeric light emitting displays - PLEDs) may exhibit improved efficiency and flexibility. The organic displays have attracted attention of a number of research groups aimed at investigating the potential applications of these new devices in the electronic industry. In this study, a new hybrid composite comprising an inorganic phase dispersed in a polymeric matrix was investigated as a possible candidate material for displays fabrication. The continuous, organic phase was a blend containing a conducting polymer, viz. polyaniline (PANI) or its derivative poly(o-methoxyaniline) (POMA) and an insulating polymer, P(VDF-TrFE) (Poly(viny1idene fluoride- trifluorethylene)). Micro particles of Zn2SiO4:Mn (SZF) was added to the polymeric phase as the luminescent, active material. Luminescent devices were fabricating using a conventional trilayer architecture in which a thin film of the hybrid composite was deposited between two conducting electrodes. As the anode electrode we used either Indium-TinOxide (ITO) or Fluorine-Tin-Oxide (FTO)-covered glass plates. Evaporated aluminum was used as the cathode electrode. The material/device characterization was carried out using electric conductivity, luminescence (L) and photoluminescence (PL) measurements. PANI/P(VDFTrFE)/ SZF (05/95)/80 and POMA/P(VDF-TrFE)/SZF (25/75)/80 composites compositions presented the best performance, with electric conductivity of ca. 10-3 S/m. Luminescence and photoluminescence measurements revealed that both devices exhibited an emission band centered at 538 nm... (Complete abstract, click electronic address below). / Mestre

Esta tese tem por objetivo o desenvolvimento de metodologias eficientes e de baixo custo para ajustar as propriedades elétricas de OFETs de canal p e de canal n, a fim de possibilitar a fabricação do circuito complementar orgânico, semelhante a uma estrutura CMOS. O desempenho do circuito complementar fabricado foi otimizado, e também foi confeccionado por impressão um OFETs de canal operando em baixas tensões. Para a fabricação do CMOS orgânico foi proposto um método baseado na seleção adequada do solvente da camada dielétrica para ajustar o desempenho elétrico dos OFETs de canal p e de canal n. Os solventes, MEK, nBA e DMSO foram selecionados para a dissolução do PMMA por apresentarem diferenças nos valores de momento de dipolo, de ponto de ebulição e de graus de ortogonalidade em relação as camadas semicondutoras de P3HT e de P(NDI2OD-T2) dos OFETs. A análise dos resultados dos OFETs de canal p e de canal n demonstrou que a metodologia proposta é adequada tanto para o ajuste das propriedades elétricas destes dispositivos quanto para a otimização do desempenho dos mesmos. Os melhores desempenhos elétricos para os OFETs de canal p e de canal n foram obtidos quando utilizados o DMSO e o MEK como solventes do PMMA, respectivamente, devido à perfeita ortogonalidade destes solventes em relação às camadas semicondutoras. Os OFETs de canal p que utilizaram o DMSO e os OFETs de canal n que utilizaram o nBA foram os que apresentaram desempenhos elétricos semelhantes, sendo portanto aplicados na fabricação do CMOS. Valores de ganho entre 6,8 e 7,8 e de margem de ruído entre 28,3 V e 34,5 V foram obtidos para inversores complementares fabricados nesta etapa do trabalho. OFETs de canal p utilizando uma blenda de PTAA: diF TES ADT como camada semicondutora, o PEDOT:PSS como eletrodos dreno/fonte e o P(VDF-TrFE-CFE) como camada dielétrica também foram fabricados neste trabalho. A técnica de blade-coating foi utilizada para a deposição dos eletrodos dreno/fonte e da camada semicondutora, ao passo que a técnica de spray-coating foi utilizada para a deposição da camada dielétrica. Da análise dos resultados foi possível inferir que a utilização de um dielétrico com elevada constante dielétrica (K), como o P(VDF-TrFE-CFE), possibilita o funcionamento dos transistores a baixas tensões (≤ 8 V), porém com valores de mobilidade reduzidos devido à elevada desordem dipolar na interface provocada por este dielétrico. Para minimizar esses efeitos, uma fina camada de um polímero fluorado foi depositada entre a camada semicondutora e a dielétrica pela técnica de blade-coating, constituindo assim uma bicamada dielétrica nos OFETs. Dos resultados das medidas elétricas dos OFETs constituídos pela bicamada dielétrica foi observada permanência do funcionamento destes dispositivos a tensões inferiores a 8 V com desempenho elétricos superiores a resultados já publicados na literatura. Por fim, inversores lógicos unipolares com transistores de carga foram fabricados com os OFETs que utilizaram a bicamada dielétrica, sendo obtidos valores de ganho entre 1,2 e 1,6 e de margem de ruído entre 56% e 68,5% de ½ VDD. / This thesis aimed to develop an efficient and low cost method to adjust the electrical properties of p- and n-channel OFETs to allow us to build an organic CMOS and the optimization of printed p-channel OFETs to work at low voltages. We proposed a method to fabricate the organic CMOS, based on the careful selection of dielectric solvent, which was adjusted to obtain the best performance of p- and n-channel OFETs. The dielectric solvents as MEK, nBA and DMSO were selected to dissolve the PMMA dielectric polymer due their different physical properties as dipole moment and boiling point and because they showed slightly different degrees of orthogonality to the P3HT and P(NDI2OD-T2) semiconductor layers of the OFETs. The results showed that the careful selection of the dielectric solvent not only allows to tune the electrical characteristics of the p- and n-channel OFETs, but also to improve the performance of these devices. The best performances were achieved when DMSO and MEK were used as dielectric solvents of the p and n-channel OFETs, respectively, as result of the perfectly orthogonality of these solvents to the semiconductor layers. P-channel OFETs using DMSO and n-channel OFETs using nBA showed similar electrical characteristics and thus, they were used to construct the organic CMOS. The organic complementary inverters showed high gain and noise margin values in the range of 6,8 to 7,8 and 28,3 V to 34,5 V, respectively. Printed p-channel OFETs were also fabricated, in which the blend PTAA:diF TES ADT was used as semiconductor channel, PEDOT:PSS as the drain/source electrodes and P(VDF-TrFE-CFE) as the dielectric layer. The blade-coating technique was used to deposit the source/drain electrodes and the semiconductor layer, while the spray-coating technique was used to deposit the dielectric layer. It was observed that using high-k dielectric as P(VDF-TrFE-CFE) enable to reduce the operating voltage of the OFETs (≤8 V), however, this high-k dielectric also reduced the field effect mobility due the dipolar disorder at the semiconductor/dielectric interface. To minimize the dipolar issue at the interface, we inserted a thin fluoropolymer dielectric layer by blade-coating between the semiconductor and the high-k dielectric layers, thus constituting a dielectric bilayer on the OFETs. From the electrical measurements of the OFETs with the dielectric bilayer, it was observed that the devices were still working at 8 V and they also showed better performance in comparison to results already published. Finally, organic unipolar inverters with load transistors were fabricated using the p-channel OFETs with the dielectric bilayer and they showed reasonable performance, with gain and noise margin in the range of 1,2 to 1,6 and 56% e 68,5% of ½ VDD, respectively.

Esta tese tem por objetivo o desenvolvimento de metodologias eficientes e de baixo custo para ajustar as propriedades elétricas de OFETs de canal p e de canal n, a fim de possibilitar a fabricação do circuito complementar orgânico, semelhante a uma estrutura CMOS. O desempenho do circuito complementar fabricado foi otimizado, e também foi confeccionado por impressão um OFETs de canal operando em baixas tensões. Para a fabricação do CMOS orgânico foi proposto um método baseado na seleção adequada do solvente da camada dielétrica para ajustar o desempenho elétrico dos OFETs de canal p e de canal n. Os solventes, MEK, nBA e DMSO foram selecionados para a dissolução do PMMA por apresentarem diferenças nos valores de momento de dipolo, de ponto de ebulição e de graus de ortogonalidade em relação as camadas semicondutoras de P3HT e de P(NDI2OD-T2) dos OFETs. A análise dos resultados dos OFETs de canal p e de canal n demonstrou que a metodologia proposta é adequada tanto para o ajuste das propriedades elétricas destes dispositivos quanto para a otimização do desempenho dos mesmos. Os melhores desempenhos elétricos para os OFETs de canal p e de canal n foram obtidos quando utilizados o DMSO e o MEK como solventes do PMMA, respectivamente, devido à perfeita ortogonalidade destes solventes em relação às camadas semicondutoras. Os OFETs de canal p que utilizaram o DMSO e os OFETs de canal n que utilizaram o nBA foram os que apresentaram desempenhos elétricos semelhantes, sendo portanto aplicados na fabricação do CMOS. Valores de ganho entre 6,8 e 7,8 e de margem de ruído entre 28,3 V e 34,5 V foram obtidos para inversores complementares fabricados nesta etapa do trabalho. OFETs de canal p utilizando uma blenda de PTAA: diF TES ADT como camada semicondutora, o PEDOT:PSS como eletrodos dreno/fonte e o P(VDF-TrFE-CFE) como camada dielétrica também foram fabricados neste trabalho. A técnica de blade-coating foi utilizada para a deposição dos eletrodos dreno/fonte e da camada semicondutora, ao passo que a técnica de spray-coating foi utilizada para a deposição da camada dielétrica. Da análise dos resultados foi possível inferir que a utilização de um dielétrico com elevada constante dielétrica (K), como o P(VDF-TrFE-CFE), possibilita o funcionamento dos transistores a baixas tensões (≤ 8 V), porém com valores de mobilidade reduzidos devido à elevada desordem dipolar na interface provocada por este dielétrico. Para minimizar esses efeitos, uma fina camada de um polímero fluorado foi depositada entre a camada semicondutora e a dielétrica pela técnica de blade-coating, constituindo assim uma bicamada dielétrica nos OFETs. Dos resultados das medidas elétricas dos OFETs constituídos pela bicamada dielétrica foi observada permanência do funcionamento destes dispositivos a tensões inferiores a 8 V com desempenho elétricos superiores a resultados já publicados na literatura. Por fim, inversores lógicos unipolares com transistores de carga foram fabricados com os OFETs que utilizaram a bicamada dielétrica, sendo obtidos valores de ganho entre 1,2 e 1,6 e de margem de ruído entre 56% e 68,5% de ½ VDD. / This thesis aimed to develop an efficient and low cost method to adjust the electrical properties of p- and n-channel OFETs to allow us to build an organic CMOS and the optimization of printed p-channel OFETs to work at low voltages. We proposed a method to fabricate the organic CMOS, based on the careful selection of dielectric solvent, which was adjusted to obtain the best performance of p- and n-channel OFETs. The dielectric solvents as MEK, nBA and DMSO were selected to dissolve the PMMA dielectric polymer due their different physical properties as dipole moment and boiling point and because they showed slightly different degrees of orthogonality to the P3HT and P(NDI2OD-T2) semiconductor layers of the OFETs. The results showed that the careful selection of the dielectric solvent not only allows to tune the electrical characteristics of the p- and n-channel OFETs, but also to improve the performance of these devices. The best performances were achieved when DMSO and MEK were used as dielectric solvents of the p and n-channel OFETs, respectively, as result of the perfectly orthogonality of these solvents to the semiconductor layers. P-channel OFETs using DMSO and n-channel OFETs using nBA showed similar electrical characteristics and thus, they were used to construct the organic CMOS. The organic complementary inverters showed high gain and noise margin values in the range of 6,8 to 7,8 and 28,3 V to 34,5 V, respectively. Printed p-channel OFETs were also fabricated, in which the blend PTAA:diF TES ADT was used as semiconductor channel, PEDOT:PSS as the drain/source electrodes and P(VDF-TrFE-CFE) as the dielectric layer. The blade-coating technique was used to deposit the source/drain electrodes and the semiconductor layer, while the spray-coating technique was used to deposit the dielectric layer. It was observed that using high-k dielectric as P(VDF-TrFE-CFE) enable to reduce the operating voltage of the OFETs (≤8 V), however, this high-k dielectric also reduced the field effect mobility due the dipolar disorder at the semiconductor/dielectric interface. To minimize the dipolar issue at the interface, we inserted a thin fluoropolymer dielectric layer by blade-coating between the semiconductor and the high-k dielectric layers, thus constituting a dielectric bilayer on the OFETs. From the electrical measurements of the OFETs with the dielectric bilayer, it was observed that the devices were still working at 8 V and they also showed better performance in comparison to results already published. Finally, organic unipolar inverters with load transistors were fabricated using the p-channel OFETs with the dielectric bilayer and they showed reasonable performance, with gain and noise margin in the range of 1,2 to 1,6 and 56% e 68,5% of ½ VDD, respectively.

Die vorliegende Arbeit beschreibt die Entwicklung von Sensoren in einer neuen, großserienfähigen Technologie. Mit dem Mehrkomponentenmikrospritzgießverfahren werden mechanische Sensorstrukturen aus (faserverstärktem) Kunststoff an polymere piezoelektrische Wandler angebunden. Die hergestellten Aufnehmer können über die Weiterverarbeitung mit Hybridtechnologien für die Strukturintegration eingesetzt werden. Diese Dissertation stellt Entwurfsmethoden und Modelle zur Vorausberechnung der neuartigen Sensoren bereit, die zur Qualifizierung der neuen Technologie benötigt werden. Dazu werden bekannte Modellierungsansätze angewandt und wesentliche Erweiterungen für die praktische Nutzung erarbeitet. Entwurfsrelevante technologieabhängige Kenngrößen, wie die elastischen Eigenschaften der verarbeiteten Werkstoffe und die geometrischen Dimensionen der hergestellten Sensorstrukturen werden untersucht und deren Einfluss auf den Entwurfsprozessdargelegt. Die hergestellten Sensoren werden in ihrer Grundfunktion messtechnisch charakterisiert und die System- und Strukturintegration vorgestellt. / The presented work describes the development of sensors in a novel technology approach feasible for large-scale production. By using the multicomponent microinjection molding process, mechanical sensor structures out of (fiber-reinforced) polymers are joined with piezoelectric polymer transducers. The fabricated sensors can be processed further with hybrid manufacturing technologies and adapted for structure integration. This thesis introduces design methods and models for the preliminary calculation of the novel sensors, which are required for a technology qualification. Therefore, existing modelling approaches adapted and essentially extended for practical use. Design relevant parameters related to the technology like the elastic properties of the applied materials or the geometric dimensions of the manufactured sensor structures are characterized and the system and structure integration of the sensors is presented.

Made available in DSpace on 2014-06-11T19:25:31Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-12-18Bitstream added on 2014-06-13T20:53:29Z : No. of bitstreams: 1 biscuola_ma_me_rcla.pdf: 2829290 bytes, checksum: 4f1c3c8a080dce0360b3e6c8d278b78c (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / As novas tecnologias para a construção de telas e displays têm permitido reduzir o consumo de energia, o peso e a espessura, como também melhorar a eficiência e flexibilidade se comparado aos antigos monitores de CRTs e até mesmo aos atuais displays de cristal líquido. Dentre estas novas tecnologias destacam-se as que utilizam materiais orgânicos (OLED) ou orgânicos poliméricos (PLED) não somente por suas possibilidades de aplicações industriais, mas também por permitirem o desenvolvimento das ciências básica e aplicada. Seguindo uma linha alternativa, propomos, neste trabalho, um novo compósito híbrido, resultante da combinação de uma fase polimérica e uma fase inorgânica, que, do nosso ponto de vista também poderá contribuir para o desenvolvimento dessa nova geração de displays e telas. Este compósito é formado pela blenda de um polímero condutor dopado, a PANI (polianilina) ou POMA (poli(o-metóxi anilina)), e um polímero isolante, o P(VDF-TrFE) poli(vinilideno-co-trifluoretileno), na qual micro partículas de Zn2SiO4:Mn (SZF) foram adicionadas. Para o desenvolvimento desse novo compósito, estudamos cada um de seus elementos constituintes, notadamente quanto ao seu modo de preparo, características morfológicas e propriedades elétricas. Como resultado final, obtivemos dispositivos constituídos de uma única camada do compósito híbrido depositado por espalhamento sobre um substrato de ITO/FTO, acrescido, ainda, de um eletrodo de alumínio depositado por evaporação. Para a caracterização destes dispositivos foram realizadas medidas de condutividade elétrica, luminescência (L) e fotoluminescência (PL). Os compósitos PANI/P(VDF-TrFE)/SZF 05/95/80 e POMA/P(VDF-TrFE)/SZF 25/75/80 com condutividade elétrica da ordem de 10-3 S/m foram os que melhor se adequaram para a construção dos dispositivos. Os espectros de L e PL apresentaram um pico em ? = 538... . / New technologies recently applied to the fabrication of organic screens and displays have allowed the manufacture of lighter, thinner monitors in comparison to either the conventional cathodic rays tube (CRTs) or the liquid crystal displays (LCDs). In addition, displays based on organic materials (the so-called organic light emitting displays (OLEDs and the polymeric light emitting displays - PLEDs) may exhibit improved efficiency and flexibility. The organic displays have attracted attention of a number of research groups aimed at investigating the potential applications of these new devices in the electronic industry. In this study, a new hybrid composite comprising an inorganic phase dispersed in a polymeric matrix was investigated as a possible candidate material for displays fabrication. The continuous, organic phase was a blend containing a conducting polymer, viz. polyaniline (PANI) or its derivative poly(o-methoxyaniline) (POMA) and an insulating polymer, P(VDF-TrFE) (Poly(viny1idene fluoride- trifluorethylene)). Micro particles of Zn2SiO4:Mn (SZF) was added to the polymeric phase as the luminescent, active material. Luminescent devices were fabricating using a conventional trilayer architecture in which a thin film of the hybrid composite was deposited between two conducting electrodes. As the anode electrode we used either Indium-TinOxide (ITO) or Fluorine-Tin-Oxide (FTO)-covered glass plates. Evaporated aluminum was used as the cathode electrode. The material/device characterization was carried out using electric conductivity, luminescence (L) and photoluminescence (PL) measurements. PANI/P(VDFTrFE)/ SZF (05/95)/80 and POMA/P(VDF-TrFE)/SZF (25/75)/80 composites compositions presented the best performance, with electric conductivity of ca. 10-3 S/m. Luminescence and photoluminescence measurements revealed that both devices exhibited an emission band centered at 538 nm... (Complete abstract, click electronic address below).

Energy efficiency is a vital key component when designing and miniaturizing self sustained microsystems. The smaller the system, the smaller is the possibility to store enough stored energy for a long and continuous operational time. To move such a system in an energy efficient way, a piezoelectrical locomotion module consisting of four resonating cantilevers has been designed, manufactured and evaluated in this work. The combination of a suitable substrate, a multilayered piezoelectric material to reduce the voltage, and a resonating drive mechanism resulted in a low power demand. A manufacturing process for multilayer cantilever actuators made of P(VDF-TrFE) with aluminum electrodes on a substrate of flexible printed circuit board (FPC), has been developed. An important step in this process was the development of an etch recipe for dry etching the multilayer actuators in an inductive plasma equipment. Formulas for the quasi static tip deflection and resonance frequency of a multilayered cantilever, have been derived. Through theses, it was found that the multilayered structures should be deposited on the polymer side of the FPC in order to maximize the tip deflection. Both a large and a miniaturized locomotion module were manufactured and connected by wires to verify that the three legged motion principal worked to move the structures forward and backward, and turn it right and left. By touching and adding load, to a fourth miniaturized cantilever, its ability to act as a contact sensor and carry object was verified. The presented locomotion module is part of a multifunctional microsystem, intended to be energy efficient and powered by a solar panel with a total volume of less than 25 mm3 and weight 65 mg. The whole system, consisting of a solar cell, an infra red communication module, an integrated circuit for control, three capacitors for power regulating, the locomotion module and an FPC connecting the different modules, was surface mounted using a state of the art industrial facility. Two fully assembled systems could be programmed both through a test connector and through optical sensors in the multifunctional solar cell. One of these was folded together to the final configuration of a robot. However, the entire system could not be tested under full autonomous operating conditions. On the other hand, using wires, the locomotion module could be operated and used to move the entire system from a peak-to-peak voltage of 3.0 V.