<p>   Organic electronics has been a highly researched field owing to the low cost, biocompatibility, mechanical flexibility, and superior performance relative to their inorganic counterparts in some applications. Significant advancement has been achieved across various device platforms including organic light-emitting diodes (OLEDs), organic field effect transistors (OFETs), and organic solar cells, for instance. Recently, soft materials that can conduct both charge and ions simultaneously (i.e., organic mixed conductors) have been a major catalyst in the fields of biosensors and energy storage. Extensive research efforts in the organic electronics field are being invested to establish the relevant structure-property relationships to design and develop higher performing organic mixed conductors. Simultaneously, these materials are utilized in developing prototype biosensors with the aim of superior performance, lower cost, and better patient comfort and outcomes than currently available technologies. Following suit, this dissertation is dedicated to furthering organic electronics on both fundamental and applied fronts. Specifically, this work examines a novel class of redox-active macromolecules, radical polymers, as the organic electrochemical transistor (OECT) active layer. In addition, wearable ocular biosensors utilizing soft materials to realize design innovation are presented.</p> <p>   For the first part of the present dissertation, radical polymer-based blends are evaluated for mixed electron and ion conduction in OECTs. Traditional macromolecular design motifs for OECT active layer materials have been a closed-shell macromolecular backbone for electron conduction with charge-neutral hydrophilic side chains (e.g., triethylene glycol) for ion conduction. When poly(4-glycidyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl) (PTEO) is blended with poly(3-hexylthiophene) (P3HT), 2,2,6,6-tetramethylpiperidin-N-oxy (TEMPO) radicals in PTEO act as an independent voltage regulator that modulates the ionic and hence electronic transport of the OECT devices. Electrochemical analysis of the blend films reveals that the ionic transport and hence electrochemical doping of the P3HT phase occur when the applied bias matches the onset oxidation potential of TEMPO radicals in PTEO even though that of P3HT is lower than that of TEMPO oxidation. By optimizing the blend ratio, figure-of-merit (i.e., μC*) values over 150 F V–1 cm–1 s–1 at loadings as low as 5% PTEO (by weight) are achieved, placing the performance on the same order as top-performing conjugated polymers despite the mediocre performance of pristine P3HT (<10 F V–1 cm–1 s–1). These findings suggest that introduction of open-shell moieties in the OECT active layer as a secondary redox-active species may significantly improve OECT performance metrics and offer a new paradigm for future macromolecular designs.</p> <p>   In the second part of the dissertation, novel design strategies for wearable ocular electroretinography (ERG) sensors are presented. Typically, wearable sensors are custom-made contact lenses fabricated in a bottom-up fashion where the pre-fabricated sensor component is either embedded in the contact lens body or sandwiched between two. The present work instead utilizes commercially available contact lenses, and the corneal electrode is integrated via electropolymerization of poly(3,4-ethylenedioxythiophene):iron(III) p-toluenesulfonate (PEDOT:Tos) on the lens surface. Electrochemical analysis of the PEDOT:Tos reveals that the measured impedance is several orders of magnitude lower than that of noble metals (e.g., Au) used as the working electrode in commercial electrodes. The mechanical and chemical stability along with the soft form factor of the present design strategy enables high-fidelity recording of ERG signals in human subjects without the need for topical anesthesia.</p> <p>   Following the similar strategy, a new seamless wearable ocular sensor integration strategy utilizing polydopamine (PDA) conformal coating is demonstrated. In this work, we utilize its strong adhesive property originating from the van der Waals interactions between catechol moieties of PDA and various hydrophilic functional groups (e.g., hydroxy, ether, etc.) already present in commercial contact lens materials. The facile integration demonstrates high peeling strength (> 55 J m-2), chemical and mechanical stability. A series of <em>in vivo</em> assessments demonstrates high accuracy, reliability, and user comfort of the fabricated wearable sensor in both animal and human subjects. The findings suggest that the PDA-assisted integration strategy may be applied in designing various future-generation wearable ocular electrophysiological sensors.</p>

A eletrônica orgânica, isto é, aquela baseada em compostos orgânicos principalmente por átomos de Carbono, Hidrogênio, Nitrogênio, etc., vem mostrado um notável desenvolvimento nos últimos anos, pois tem aberto novas aplicações e novos mercados na área da eletrônica. Displays flexíveis e de alta resolução feitos a partir de polímeros conjugados emissores de luz - PLEDs (Polymer Light-Emitting Diodes)- são umas das aplicações tecnológicas que já estão em estágio avançado de desenvolvimento. Dispositivos fotovoltaicos, assim como os transistores por efeito de campo, são duas conquistas recentes dessa nova área de pesquisa científica e tecnológica. Esses dispositivos formarão a próxima geração da industria eletrônica: a da eletrônica orgânica. Por outro lado, essa é uma área onde há muita pesquisa fundamental a ser realizada. O estudo das propriedades elétricas de filmes poliméricos ultrafinos é um dos ramos da eletrônica orgânica que necessita de muita investigação científica. Para muitas aplicações é necessário conhecer precisamente o valor da mobilidade dos portadores de carga, e quando os filmes são de espessura de algumas dezenas de nanômetros, essa determinação torna-se dificultosa. A técnica Tempo de Vôo (TOF) muito usada para a obtenção da mobilidade de portadores em filmes finos, é limitada quando a condutividade elétrica do filme é relativamente elevada e quando o filme se torna muito fino. Há cerca de dez anos apareceram os primeiros resultados de medidas de mobilidade em filmes ultrafinos e mais condutores, obtidos pela técnica CELIV. Nesta dissertação de mestrado, implementamos a técnica Photo-CELIV no Grupo de Polímeros Bernhard Gross e a aplicamos no estudos do polímero Poli[(9,9-dioctil-fluorenil-2,7-diil)-co-(1,4-benzo-{2,1-3}-tiadiazol)], F8BT. Tal material é um dos protagonistas da eletrônica orgânica atual e vem sendo muito aplicado em diodos emissores de luz, fotovoltaicos e em transistores por efeito de campo. / Organic electronics is the technology based on organic compounds, i.e, made by carbon, hydrogen, nitrogen, etc., and has shown a great development in the last years, opening new applications and new markets. Flat and light panels having high-resolution image is one application that is in an advanced stage, and is composed by pixels of OLEDS (organic light-emitting diodes). Photovoltaic devices and organic thin film transistors (OTFTs), are other two very promising technologies in the organic world. This technology is opened the flexible electronics of large areas. Despite this great technological development, this still area requires a lot of fundamental studies, as the electrical properties of ultra-thin organic films. For electronic and optoelectronic device applications it is necessary, for example, to know the value of the carrier mobility, which is not easy to obtain in ultra-thin films (from dozens to hundreds of nanometers). The technique Time-of-Flight is extensively used to measure carrier mobility of thin films, but its is limited to materials having conductivity relatively low, and thickness not smaller than 1 micrometer. The first direct measurements of carrier mobility in ultra-thin films appeared circa 10 years ago, by a new technique called CELIV. The goal of this work was to build the Photo-Celiv technique in the Group of Polymer Bernhard Gross, and to apply it to study electrical properties of the polymer Poli[(9,9-dioctil-fluorenil-2,7-diil)-co-(1,4-benzo-{2,1-3}-tiadiazol)], F8BT, which has been used with success as active material for organic photovoltaics and organic transistors.

While mixed ionic-electronic conductors (MIECs) show promise in a number of different device structures, their successful application has been inhibited by difficulties with characterization. The simultaneous influence of both ionic and electronic systems often foils attempts to quantify material parameters important for rational device design. In many cases, even general models of MIEC function can prove uncertain or controversial. This dissertation addresses the broader issue of ambiguity in MIEC characterization by exploring near-infrared absorbance as a method of gaining further insight into these systems. In combination with a traditional suite of techniques, this method enables determination of parameters not otherwise accessible. The determination of a concentration-dependant carrier mobility in an MIEC material will be demonstrated, and MIEC conduction in the unipolar regime will be broadly described as a system of electrochemically-supported charge injection. This model will be subsequently expanded to describe an unusual and previously unreported phenomenon of rectification when MIECs are interfaced with otherwise appropriate semiconducting contacts. A model labeled as extracting-electrode space-charge limited current will be described and experimentally demonstrated. Finally, the unique photovoltaic properties of an ionic heterojunction system comprising two MIECs will be examined. The results will be used to gain insight into the role of ionic asymmetry in the behavior of MIEC interfaces. This dissertation contains coauthored, previously published, and unpublished work.

No description available.

Projects were undertaken investigating the functionalisation of polyaromatic cores (chrysene, pyrene and perylene) for use in organic electronics and aqueous graphene stabilisation. In each case an iridium-catalysed aromatic C-H borylation formed a key synthetic step, allowing access to unique substitution patterns. The development of strategies for the orthogonal and asymmetric functionalisation of polyaromatic hydrocarbons was explored. In a key synthetic step 4,10-dichlorochrysene was regioselectively borylated in high yields at the 2,8-positions though C-H activation chemistry. The subsequent application of sequential palladium-catalysed Suzuki and Kumada coupling reactions to this intermediate enabled the synthesis of a series of chrysene derivatives with a unique orthogonal "A2B2" 2,8- and 4,10-substitution pattern. In addition the application of a trifluoromethylation at the borylated 2,8-positions enabled the synthesis of a donor-acceptor chrysene derivative. The effect of these substitution patterns on the photophysical and electrochemical properties of these derivatives was investigated and their potential use as organic semiconducting materials evaluated. In particular the synthesised chrysene derivatives displayed broadened UV-vis absorption spectra, redshifted fluorescence spectra, increased HOMO levels and decreased band gaps. In an extension of these aromatic substitution methodologies, pyrene and perylene aromatic cores were functionalised to perform as stabilisers for aqueous graphene dispersions, investigating asymmetric motifs that may maximise performance. A series of amphiphilic pyrene- and perylene-based alkylsulfonic acid salts were synthesised via their intermediate hydroxyalkyl derivatives. In addition the application of the previously explored aromatic C-H borylation allowed access to 7- and 5,8,11- asymmetrically substituted pyrene and perylene derivatives. Through collaboration, initial steps have been undertaken to compare and evaluate these novel stabilisers for their ability exfoliate graphite to graphene in aqueous solution.

Wong, Man Keung. / "November 2010." / Thesis (M.Phil.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references. / Abstracts in English and Chinese. / Abstract --- p.i / Table of contents --- p.iii / List of Figures --- p.vi / List of Tables --- p.ix / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Background --- p.1 / Chapter 1.2 --- History of organic photovoltaic cells --- p.2 / Chapter 1.2.1 --- Single layer organic photovoltaic cells --- p.2 / Chapter 1.2.2 --- Bilayer organic photovoltaic cells --- p.3 / Chapter 1.2.3 --- Bulk Heterojunction organic photovoltaic cells --- p.6 / Chapter 1.3 --- Device physics of organic photovoltaic cells --- p.9 / Chapter 1.4 --- Device fabrication and characterization --- p.12 / Chapter 1.5 --- Thesis outline --- p.14 / Chapter Chapter 2 --- Instrumentation --- p.18 / Chapter 2.1 --- Keithley 236 source measure unit --- p.18 / Chapter 2.2 --- CHI 660C electrochemical instrument --- p.18 / Chapter 2.3 --- Tensor Alpha Step 500 Profilometer --- p.19 / Chapter 2.4 --- Fourier Transform Infrared (FTIR) spectroscopy --- p.20 / Chapter 2.5 --- Thermogravimetric Analysis --- p.22 / Chapter 2.6 --- X-ray Diffraction --- p.23 / Chapter 2.7 --- Scanning electron microscopy --- p.24 / Chapter 2.8 --- Atomic force microscopy --- p.26 / Chapter Chapter 3 --- Surface functionalization of Carbon Nanotube --- p.28 / Chapter 3.1 --- Introduction --- p.28 / Chapter 3.2 --- Oxidative treatment --- p.28 / Chapter 3.2.1 --- Experimental procedures --- p.28 / Chapter 3.2.2 --- Characterization --- p.29 / Chapter 3.3 --- Hydrothermal treatment --- p.35 / Chapter 3.3.1 --- Experimental procedures --- p.35 / Chapter 3.3.1.1 --- Synthesis of MWCNTols --- p.35 / Chapter 3.3.1.2 --- Synthesis of MWCNT-PEDOT --- p.36 / Chapter 3.3.2 --- Characterization --- p.37 / Chapter 3.4 --- Summary --- p.42 / Chapter Chapter 4 --- P3HT/f-CNT/PCBM Composites for Organic Photovoltaic Cells --- p.45 / Chapter 4.1 --- Introduction --- p.45 / Chapter 4.2 --- Fabrication procedures --- p.48 / Chapter 4.3 --- IV characteristics of organic photovoltaic cells --- p.51 / Chapter Chapter 5 --- Vertically aligned poly(3-hexylthiophene) nanobrushes of high aspect ratio for photoelectrochemical solar cells --- p.60 / Chapter 5.1 --- Introduction --- p.60 / Chapter 5.2 --- Sample preparation --- p.63 / Chapter 5.3 --- IV characteristics of P3HT nanobrushes --- p.65 / Chapter 5.4 --- AFM and XRD analysis --- p.66 / Chapter 5.5 --- Summary --- p.71 / Chapter Chapter 6 --- Conclusions --- p.74 / Chapter 6.1 --- Conclusions --- p.74

A eletrônica orgânica, isto é, aquela baseada em compostos orgânicos principalmente por átomos de Carbono, Hidrogênio, Nitrogênio, etc., vem mostrado um notável desenvolvimento nos últimos anos, pois tem aberto novas aplicações e novos mercados na área da eletrônica. Displays flexíveis e de alta resolução feitos a partir de polímeros conjugados emissores de luz - PLEDs (Polymer Light-Emitting Diodes)- são umas das aplicações tecnológicas que já estão em estágio avançado de desenvolvimento. Dispositivos fotovoltaicos, assim como os transistores por efeito de campo, são duas conquistas recentes dessa nova área de pesquisa científica e tecnológica. Esses dispositivos formarão a próxima geração da industria eletrônica: a da eletrônica orgânica. Por outro lado, essa é uma área onde há muita pesquisa fundamental a ser realizada. O estudo das propriedades elétricas de filmes poliméricos ultrafinos é um dos ramos da eletrônica orgânica que necessita de muita investigação científica. Para muitas aplicações é necessário conhecer precisamente o valor da mobilidade dos portadores de carga, e quando os filmes são de espessura de algumas dezenas de nanômetros, essa determinação torna-se dificultosa. A técnica Tempo de Vôo (TOF) muito usada para a obtenção da mobilidade de portadores em filmes finos, é limitada quando a condutividade elétrica do filme é relativamente elevada e quando o filme se torna muito fino. Há cerca de dez anos apareceram os primeiros resultados de medidas de mobilidade em filmes ultrafinos e mais condutores, obtidos pela técnica CELIV. Nesta dissertação de mestrado, implementamos a técnica Photo-CELIV no Grupo de Polímeros Bernhard Gross e a aplicamos no estudos do polímero Poli[(9,9-dioctil-fluorenil-2,7-diil)-co-(1,4-benzo-{2,1-3}-tiadiazol)], F8BT. Tal material é um dos protagonistas da eletrônica orgânica atual e vem sendo muito aplicado em diodos emissores de luz, fotovoltaicos e em transistores por efeito de campo. / Organic electronics is the technology based on organic compounds, i.e, made by carbon, hydrogen, nitrogen, etc., and has shown a great development in the last years, opening new applications and new markets. Flat and light panels having high-resolution image is one application that is in an advanced stage, and is composed by pixels of OLEDS (organic light-emitting diodes). Photovoltaic devices and organic thin film transistors (OTFTs), are other two very promising technologies in the organic world. This technology is opened the flexible electronics of large areas. Despite this great technological development, this still area requires a lot of fundamental studies, as the electrical properties of ultra-thin organic films. For electronic and optoelectronic device applications it is necessary, for example, to know the value of the carrier mobility, which is not easy to obtain in ultra-thin films (from dozens to hundreds of nanometers). The technique Time-of-Flight is extensively used to measure carrier mobility of thin films, but its is limited to materials having conductivity relatively low, and thickness not smaller than 1 micrometer. The first direct measurements of carrier mobility in ultra-thin films appeared circa 10 years ago, by a new technique called CELIV. The goal of this work was to build the Photo-Celiv technique in the Group of Polymer Bernhard Gross, and to apply it to study electrical properties of the polymer Poli[(9,9-dioctil-fluorenil-2,7-diil)-co-(1,4-benzo-{2,1-3}-tiadiazol)], F8BT, which has been used with success as active material for organic photovoltaics and organic transistors.

Wu, Chin Kong. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (p. 122-131). / Abstract also in Chinese. / ABSTRACT (English) --- p.i / ABSTRACT (Chinese) --- p.iii / ACKNOWLEDGMENTS --- p.v / TABLE OF CONTENTS --- p.vi / Chapter CHAPTER 1 --- Introduction --- p.1 / Chapter 1.1 --- Organic light-emitting- diode (OLED) --- p.2 / Chapter 1.2 --- Organic photovoltaics --- p.5 / Chapter 1.3 --- Organic field-effect transistor --- p.10 / Chapter CHAPTER 2 --- Properties of organic semiconductor --- p.17 / Chapter 2.1 --- Organic semiconductors --- p.17 / Chapter 2.2 --- Electronic structure of organic semiconductors --- p.18 / Chapter 2.3 --- Disorder and traps in organic semiconductors --- p.19 / Chapter 2.4 --- Charge carriers transport in organic semiconductors --- p.20 / Chapter 2.4.1 --- Polaron model --- p.21 / Chapter 2.4.2 --- Scher-Montroll model --- p.21 / Chapter 2.4.3 --- Gaussian disorder model --- p.23 / Chapter 2.5 --- Metal/organic interfaces --- p.25 / Chapter CHAPTER 3 --- Experimental details --- p.28 / Chapter 3.1 --- Sample preparation --- p.28 / Chapter 3.1.1 --- Organic semiconductors used in this thesis --- p.28 / Chapter 3.1.2 --- Cleaning of substrate --- p.29 / Chapter 3.1.3 --- Deposition of organic layer --- p.29 / Chapter 3.1.4 --- Deposition of metal --- p.31 / Chapter 3.2 --- Electrical characterization methods --- p.32 / Chapter 3.2.1 --- Current density 一 voltage (J-V) measurement --- p.32 / Chapter 3.2.2 --- Dark Injection Space-Charge-Limited (DI-SCL) transient current measurement --- p.38 / Chapter 3.2.3 --- Temperature varied J-V measurement --- p.43 / Chapter 3.2.4 --- Admittance spectroscopy --- p.44 / Chapter CHAPTER 4 --- Charge transport properties in single-organic-layer devices --- p.51 / Chapter 4.1 --- Experimental scheme --- p.51 / Chapter 4.2 --- Experimental results and discussion --- p.53 / Chapter 4.2.1 --- J-V measurements --- p.53 / Chapter 4.2.1.1 --- MTDATA --- p.53 / Chapter 4.2.1.2 --- NPB --- p.59 / Chapter 4.2.2 --- DI-SCL transient current measurement --- p.64 / Chapter 4.2.3 --- Admittance spectroscopy --- p.68 / Chapter 4.2.3.1 --- MTDATA --- p.68 / Chapter 4.2.3.2 --- NPB --- p.75 / Chapter 4.3 --- Conclusion --- p.79 / Chapter CHAPTER 5 --- Charge transport properties in double-organic-layer devices with organic-organic heterojunction --- p.81 / Chapter 5.1 --- Introduction --- p.81 / Chapter 5.2 --- Experimental scheme --- p.82 / Chapter 5.3 --- Experimental results and discussion --- p.84 / Chapter 5.3.1 --- ITO/MTDATA/NPB/A1 device --- p.84 / Chapter 5.3.2 --- ITO/MTDATA/Alq3/LiF/Al device --- p.105 / Chapter 5.4 --- Conclusion --- p.115 / Chapter CHAPTER 6 --- Conclusions and future work --- p.101 / Chapter 6.1 --- Conclusions --- p.118 / Chapter 6.2 --- Future work --- p.120 / REFERENCES --- p.122

Les trois dernières décennies ont vu l’émergence de l’électronique organique ainsi que son établissement en tant que domaine scientifique interdisciplinaire et dans notre vie quotidienne. On dénombre actuellement deux défis scientifiques majeurs dans ce domaine. Le premier est de s’attacher à augmenter l’efficacité des dispositifs par l’utilisation de nouveaux matériaux, plutôt le deuxième consiste en l’intégration de fonctionnalités multiples un seul dispositif. Atteindre ces objectifs nécessite la compréhension des mécanismes fondamentaux de la physico-chimie, gouvernants les propriétés de base de l’électronique organique tels l’injection ou le transfert de charge et le transport. Ces travaux de thèse rapport le développement de systèmes complexes, auto assemblés, dont les propriétés électriques et optiques au sein de dispositifs organo-électroniques peuvent être modulées en réponse aux stimuli extérieurs. Ce but a été obtenu par le développement des briques élémentaires et par l’étude de leurs propriétés physico-chimiques afin de modéliser tous les mécanismes impliqués. / In the last three decades Organic Electronics emerged and established itself as an interdisciplinary field of science and as part of our daily life. Presently, the greatest scientific challenges in this field of research are two: the former relies on the improvement of devices efficiency which can be accomplished by using new materials, whereas the latter consist in the integration of multiple functionalities in a single device. To accomplish these goals one needs to develop a deep understanding on the fundamental physical-chemistry ruling the properties which are on the basis of organic electronics such as charge injection, charge transfer and transport. This PhD project reports the developing of efficient multicomponent electroactive self-assembled systems whose electro- and optical properties can be modulated, in devices, as a response to multiple external and independent stimuli. This goal has been achieved by engineering of the proper building blocks and the study of the the physico-chemical properties to be able to model all the mechanisms involved.

The discipline of organic electronics encompasses the design and synthesis of molecules for use in organic field effect transistors, organic photovoltaics, organic photodetectors, single molecule electronics, sensors, and many more. The rationale for studying organic electronic materials is compelling: organics have the potential to be low cost, processable, and flexible complements to silicon technologies to combat some of the most pressing environmental issues. Organic molecules that transport carriers are used as the active layer in many device applications. Molecules that possess energy levels that allow for electron or hole transport are typically π-conjugated materials. There has been swift progress on the design and synthesis of π-conjugated materials that possess a large density of high energy electrons such as acenes. Yet there has been less growth on materials with low energy vacant orbitals to accept an electron. Fullerenes are the ubiquitous acceptor materials used in organic electronics. Over the past few years, there have been several groups, including our own, that have synthesized non-fullerene materials for use in organic field effect transistors and solar cells. In particular, the Nuckolls laboratory has pioneered the design and synthesis of a class of molecules called contorted aromatics and studied these molecules in range of organic electronic applications. Conjugated macrocycles are one sub-class of the contorted aromatic family. This Thesis describes a body of research on the design, synthesis, and application of a new class of electronic materials made from conjugated macrocycles. Each of the macrocycles comprises perylenediimide cores wound together with various electronic linkers. The perylenediimide building block endows each macrocycle with the ability to transport electrons, while the synthetic flexibility to install different linkers allows us to create macrocycles with different electronic and physical properties. We use these materials in organic photovoltaics, field effect transistors, sensors, and photodetectors. The macrocycles possess vivid colors, absorb in the visible range of the solar spectrum, and are an exemplary class of materials to study how rigidity and strain affect device performance. We find that the strained and rigid macrocyclic framework affords each macrocycle with the ability to absorb lower energy visible light with respect to acyclic counterparts and the macrocycles outperform in photovoltaic applications. Rigidity was an important concept in our organic photodetector study: we found rigidity was one of the reasons our macrocycles outperformed both fullerenes and acyclic controls. The macrocycles all possess intramolecular cavities, and our recent studies focused on using this nanospace for sensing applications. Each of the studies described in this Thesis will demonstrate how macrocyclization is a design technique to enhance organic electronic performance.