Thienoacenes represent an intriguing class of organic semiconducting molecules with potential applications in organic electronics. Some of thienoacenes have been reported with high charge carrier mobility in organic field-effect transistors (OFET). OFETs based on naphtho[2,1-b:3,4-b’]dithiophene (NDT) exhibited moderate device performance and low-band gap donor-acceptor copolymers based on NDT showed a promising solar power conversion efficiency. In this thesis, four novel series of thienoacenes based on naphtho[2,1-b:3,4-b’]dithiophene backbone were designed and synthesized for OFET applications. Firstly, a novel series of p-type semiconducting naphthodithieno[3,2-b]thiophene derivatives (NDTT-n) composed of six-fused aromatic rings were designed and synthesized (Figure 1). The OFETs based on NDTT-10, and NDTT-12 fabricated by vacuum deposition showed a hole mobility of 0.22 and 0.13 cm2/(Vs), respectively with Ion/Ioff above 107 after annealing at 80 oC. Secondly, the derivatives of NDT fused with benzene rings at the flanks of thiophene, namely NBBT-n (Figure 2) were also designed and synthesized. OFETs based on NBBTF-10 fabricated by vacuum deposition exhibited a hole mobility of 0.35 cm2/(Vs) with a current on/off ratio of 106 107 after annealing at 160 oC. Further extension of π-conjugation of NDTT by incorporating with fused thiophenes leading to a new NBTBT-n series was also developed (Figure 3). The OFETs fabricated by NBTBT-10 showed the hole mobility up to 0.25 cm2/(Vs) with a current on/off ratio of 105 106 after annealing at 220 oC. Lastly, two dimensionally π-extended, butterfly-shaped thienoacenes (Figure 4) were also synthesized. The OFETs based on SMB-10 fabricated by spin-coating showed the best performance in this series with an average mobility of 0.027 cm2/(Vs) for five devices and the highest mobility of 0.038 cm2/(Vs) with a current on/off ratio of 106 107 by from chloroform. Key words: organic semiconducting molecules, organic field-effect transistor, thienoacene, charge carrier mobility.

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The study of the new materials potentially usable for organic photovoltaic and electronics are getting very important from the point of ecological and financial view. Organic electronic devices are getting more and more popular and it is only up to us to search for the new ones that are able to improve their physical properties. The aim of this thesis is to search for materials like have been mentioned above which have very good semiconducting properties. Solutions of pure materials and its mixtures with different concentrations of fullerene have been investigated by ultra-violet spectroscopy, classical fluorescence and time resolved spectrometry. Mainly, were studied the influence of the central atom and side substituents for the optical and electronical properties of our materials of interest. With adding fullerene was observed quenching phenomena of the fluorescence, because all these new materials show usually high photoluminescence. Based on the given results, the most suitable materials had been chosen to provide trial of making organic solar cell, and therefore investigated by the mean of electric measurements (direct current).

When designing novel materials for organic photovoltaic (OPV) applications, it is important to consider the significance of structural design on both the chemical and physical properties of the resulting material. The designed targets should promote efficient charge transport along a planar backbone, be solution processable and ideally, both the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) should be able to be easily tuned via synthetic modifications. Using a concise synthetic route, a variety of novel semiconducting polymers and small molecules based on 2,6-di(aryl)benzo[1,2-b:4,5-b']difuran (BDF), an electron donating unit, have been developed and characterized. This benzodifuran moiety is of particular interest in this work as it is able to be synthesized in concise, high yielding steps and the core structure has the potential to be readily modified. Chapters Two through Four will demonstrate the power of fine-tuning this molecular species and how a facile synthetic route lends itself to the application specific design and development of BDF polymers and small molecules. The field of organic electronics primarily focusses on polymers and small molecules; however, each of these categories of materials have intrinsic drawbacks. Polymers are generally difficult to solubilize and the batch-to-batch consistency (involving parameters such as molecular weight and material uniformity) is almost impossible to control. Small molecules, while being very uniform and having a defined molecular structure, are difficult to deposit as uniform device films since they are typically not solution processed and are, instead, thermally evaporated onto a substrate. As a result of these key issues, a material of intermediate size and length, namely oligomers, which combine the benefits of small molecules and polymers is highly desired. Towards the realization of this goal, the Chapter Five of this work will share various flow reactor designs specifically geared towards modified flow platforms that allow for the synthesis of oligomeric materials. / 2022-02-08T00:00:00Z

Sustainable energy has taken center stage in materials research and global markets, which has encouraged an explosion in related materials development. Practical implementations of sustainable energy solutions rely upon high-performance and cost-effective materials for energy harvesting and storage. Organic electronics, a class of materials composed principally of carbon, are regarded as promising candidates in this respect. Carbon, when arranged with atomic precision and warped carefully into desirable conformations, can generate exceptionally inexpensive and high-performance materials. These materials can then be readily integrated into solar cells, capacitors, and transistors. This dissertation explores our progress in the field of high-performance organic electronics in the context of these practical devices, and aims to establish simple design principles for the future development of contorted organic electronics. Of principal importance to this thesis is the conclusion that localized molecular contortion seems to bestow unique and somewhat unexpected properties upon extended systems. Therefore, a key theme underlying our work herein is the idea that for specific applications, contorted or extended graphene nanoribbons can be shown to be superior to planar organics. This advantage has allowed us to report exceptionally high performance metrics in the fields of energy harvesting and storage. Chapter 1 comprises an overview of the entire body of work contained within this dissertation, in a highly condensed format. This includes in-depth specific background on the innovations of prior researchers who have enabled our present work. Chapter 2 details the elongation of the small graphene fragment perylene into long, electronically active, and ambient-stable nanoribbons. This chapter is assembled from three research manuscripts investigating the employment of these nanoribbons as electron transporting materials in photovoltaics and one set of preliminary results on their incorporation as potential surface arrays for chip technologies. Chapter 3 examines the expansion of our perylene-based nanoribbons into large single-molecule three-dimensional nanostructures up to 5 nm in wingspan. These structures, by consequence of their three-dimensional geometry and contorted nature, exhibit curious enhancements over their one-dimensional counterparts. Such enhancements, namely in photovoltaic efficiency and electron transport behavior, are investigated over the course of two research manuscripts. Chapter 4 explores the idea of organic energy storage through the lens of pseudocapacitance, and further expands the perylene toolbox by developing high-capacitance and highly stable polymer structures. These ideas ultimately culminate in the final subchapter, wherein our most recent work on contorted, semi-two-dimensional capacitive polymers is disclosed. The exceptionally strong and potentially economically viable results of our most recent energy storage architecture are enabled entirely by our understanding of molecular contortion. Namely, contortion’s unique ability to manifest long-range electronic conjugation concomitant with the prevention of aggregation, thus improving surface area for ion diffusion and bulk processability. In consideration of the impact these nanoscale ideas could have on the global scale, it is our belief that ideas concerning contortion within the context of organic electronics will continue to generate high-performance energy storing and harvesting materials. Our explorations towards such solutions have garnered substantial interest in the materials community thus far, and this dissertation seeks to add to that growing body of literature by inspiring numerous new twisted architectures.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第21785号 / 工博第4602号 / 新制||工||1717(附属図書館) / 京都大学大学院工学研究科物質エネルギー化学専攻 / (主査)教授 村田 靖次郎, 教授 大江 浩一, 教授 中村 正治 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

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<p>  </p> <p>Recently, there has been significant increase in research and development in the field of organic electronics. This is mainly because organic electronic devices can be flexible, lightweight, and processed from solution using low-cost manufacturing techniques. Typically, these devices have utilized conjugated polymers as their active layer components. This approach has been successful, but the use of conjugated polymers comes with limitations. To address these limitations and expand the field of organic electronics, this work studies a novel class of macromolecules, radical polymers. Unlike their conjugated polymer counterparts, radical polymers are comprised of a non-conjugated backbone with stable open-shell groups at their pendant sites. By studying the structure-property relationships of these radical polymers, this work developed novel polymer systems for a variety of organic electronic applications. Furthermore, these studies can be applied to future radical polymer systems yet to be discovered. Ultimately, this work served as a template for expanding the field of organic electronics. </p>

Indium tin oxide is a transparent conductive oxide electrode which is widely used for organic electronics. Morphology of ITO plays an important role in the performance of organic electronics. To understand the influence of the substrate morphology in device performance, a controllable route for producing periodic and aperiodic roughness of ITO surfaces are necessary. In this thesis, this was attempted by using various approaches to forming ITO nanostructures. Initially, ITO was deposited by a traditional sputtering procedure. However, the roughness distribution of the sputtered ITO resulted in a s Gaussian distribution, unsuitable to further studies of roughness. ITO nanostructures can also be formed by depositing ITO nanoparticles on an ITO sub- strates. Using acetate and chloride precursors, ITO films were produced from solution and formed into nanoparticles using the reverse micelles deposition approach. The acetate route (InAc+SnCl2+ethanol), was the most successful prior to the nanoparticle formation, showing high quality ITO with bixbyte crystal structure and Sn percentages of 20%, low enough to form a conductive film. Nanoparticles were fabricated with diblock copolymer reverse micelles(PS-b-P2VP). Reverse micelles were found to act as a nano reactor, restricting the size of nanoparticles by having hydrophilic reactants undergo chemical reactions inside the micelles. However, nanoparticles from the reverse micelles revealed Sn percentages much above 20%. This was attributed to the solubility difference of the precursors leading to displacing or preventing of pre- cursor loading into the reverse micelles. The change of the stirring time, the micelles concentration, the sequence of precursors loading, and the weight of precursors were not found to affect the Sn concentration; moreover, large variations in Sn concentrations were observed. From quantitative nano mechanical testing of the micelles, a maximum load amount for the precursors was observed, confirming that the high concentration of Sn was likely due to the solubility differences between the precursors and their ability to penetrate the micelle. By manipulating the nanoparticles distribution through spin coating speeds, micelles concentration, and deposited volume, several degrees of order were obtained, though hexagonal packing was not observed. In general, even though Sn concentration were found to be above 20%, nanoparticles were successfully fabricated with reverse micelles, confirming that the reverse micelle technique is a good strategy for future studies of roughness. / Thesis / Master of Applied Science (MASc)

Electronic devices are used for tasks such as keeping people connected, figuring out the contents of a package or detecting impurities in the air. The use of electronic sensors in short life cycle products has also begun to increase with the field of smart packaging. For example, RFID tags are used everyday in sorting facilities to identify packages and then discarded when the packaging is thrown away. Every year the world generates millions of tons of E-waste and most of it is exported, incinerated, or put in landfills. To mitigate the impact of electronics on the environment, it is essential that the next generation of disposable electronic devices are fabricated using environmentally friendly materials. For these materials to be considered for high throughput fabrication they need to be solution processable and biodegradable, all while having the necessary mechanical and electrical properties. This thesis focuses on the development of novel environmentally friendly dielectrics that can be used in capacitors and thin film transistors. A common environmentally friendly and biodegradable material used as a polymer dielectric is poly(vinyl alcohol) (PVA). Although PVA has a high capacitance it also has its drawbacks. Being mostly processed from aqueous solutions it is hard to form uniform thin films of PVA and it is sensitive to moisture which changes its capacitance. PVA is also a polar material which can cause charge trapping at the semiconductor/dielectric interface when used as a dielectric in the fabrication of organic thin film transistors (OTFTs). In this thesis we use different strategies such as blending dielectrics and stacking them to help improve the performance of PVA as a dielectric in OTFTs. In the first study, I demonstrate how low weight percentages of cellulose nanocrystals can be used to increase the viscosity of PVA without negatively impacting its dielectric properties. This led to better film uniformity and a larger number of functioning OTFTs. The second study focused on using a toluene diisocyanate terminated polycaprolactone (TPCL) polymer as a low-k barrier between PVA and the semiconductor. The TPCL led to an increase in OTFT performance and a large reduction in moisture sensitivity. For the third study, I improved the shelf life of the TPCL materials by replacing the toluene diisocyanate end units with UV crosslinking end units. The UV end units were protected unlike the TPCL end units allowing the polymer to remain stable under ambient conditions. The UV-PCL demonstrates similar resistance to moisture and dielectric properties to TPCL while being more stable and easier to use in traditional printing processes. My last study, investigates the use of a poly(lactic acid) (PLA) layer as a third layer in the TPCL/PVA/PLA dielectric system. The PLA layer acted as an intermediate between the substrate and PVA increasing the adhesion of PVA. Further the PLA layer improved OTFT performance and allowed for n-type single walled carbon nanotube transistors under ambient conditions. Finally, this work has demonstrated ways to improve the performance of PVA so that it can be used as an environmentally friendly dielectric in thin film, flexible and printed electronic applications.