The development and implementation of biosensors as an integral and growing part of our modern world has prompted the push for precision health as the next step in medicine. Adapted from aircraft engine monitoring, where an array of sensors is used to build a digital twin to preemptively predict problems, precision health requires an increase in molecular monitoring. Organic thin-film transistors (OTFTs), as sensitive, low-cost, and adaptable devices are well suited to meet this need. Phthalocyanines (Pcs), as an organic semiconducting layer for OTFTs, are easily synthesized and highly tunable small molecules which can be deposited through both solution and physical vapor deposition techniques, enhancing their utility. This work presents Pc-based OTFTs for cannabinoid sensing and chemotyping to meet the quality control needs of a growing Canadian and International cannabis industry, and to broadly demonstrate the sensitivity and selectivity attainable with Pc-based OTFTs incorporating molecular analyte sensors. Spectroelectrochemistry is established as a screening technique for Pc-based OTFT sensors and, in combination with thin-film characterization, is used to propose a mechanism for Pc-cannabinoid interactions and OTFT cannabinoid sensitivity with and without a cannabinoid-sensitive chromophore. Thin-film morphologies and polymorphs, pre- and post-analyte exposure, are demonstrated as key drivers of Pc-based OTFT sensing responses and are further explored through controlled deposition conditions and post deposition annealing techniques. Through material screening and thin-film engineering, part-per-billion cannabinoid sensitivity is achieved with Pc-based OTFTs. This report documents several strategies for sensitizing Pc-based OTFT sensors to organic analytes, and the results herein serve as a basis for continued development of Pc-based OTFT biosensors.

Advanced optical technologies profoundly impact countless aspects of modern life. At the heart of these technologies is the manipulation of light using optical materials. Currently, optical technologies are created using naturally occurring materials. However, a new and exciting approach is to use nanomaterials for technology development. Nanomaterials are artificially constructed material systems with precisely engineered nanostructures. Many technological revolutions await the development of new nanoscale fabrication methods that must provide the ability to control, enhance, and engineer the optical properties of these artificial constructs. This thesis responds to the challenges of nanofabrication by examining glancing angle deposition (GLAD) and improving its optical-nanomaterial fabrication capabilities. GLAD is a bottom-up nanotechnology fabrication method, recognized for its flexibility and precision. The GLAD technique provides the ability to controllably fabricate high-surface-area porous materials, to create structurally induced optical-anisotropy in isotropic materials, and to tailor the refractive index of a single material. These three advantages allow GLAD to assemble optical nanomaterials into a range of complex one-dimensional photonic crystals (PCs). This thesis improves upon previous GLAD optical results in a number of important areas. Multiple optical measurement and modeling techniques were developed for GLAD-fabricated TiO2 nanomaterials. The successful characterization of these nanomaterials was extended to engineer PC structures with great precision and a superior degree of control. The high surface area of basic PC structures was exploited to fabricate an optimized colourimetric sensor with excellent performance. This colourimetric sensor required no power source and no read-out system other than the human eye, making it a highly attractive sensing approach. Incorporating engineered defects into GLAD-fabricated PCs established a new level of design sophistication. Several PC defect structures were examined in detail, including spacing layers and index profile phase-shifts. Remarkable control over defect properties was achieved and intriguing polarization-sensitive optical effects were investigated in anisotropic defect layers. The success of these results demonstrates the precision and flexibilty of the GLAD technique in fabricating optical nanomaterials and advanced photonic devices. / Micro-Electro-Mechanical Systems (MEMS) and Nanosystems

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Silicon phthalocyanines (R₂-SiPcs) are an emerging class of high-performance n-type or ambipolar organic semiconductors which have found application in organic electronic devices, including organic thin-film transistors (OTFTs), organic photovoltaics (OPVs) and organic light-emitting diodes (OLEDs). Owing to their tetravalent silicon metal centre, R₂-SiPcs can be substituted with a range of axial ligands including phenols, carboxylic acids, and silanes to tune their intermolecular interactions, optical properties, electronic properties and solubility. While early reports of R₂-SiPcs have demonstrated promising results, the relationship between their structure and performance in OTFTs is poorly understood. Additionally, many OTFTs with R₂-SiPcs as semiconductor only demonstrate n-type behaviour under inert atmospheres due to their shallow lowest unoccupied orbital level below -4.1 eV making them susceptible to electron trapping by moisture and oxygen. This thesis presents developments in both the understanding of how R₂-SiPc structure influences performance, device engineering and exploration of these materials in ammonia sensors. First, I develop of structure-property relationships for a catalogue of fifteen R₂-SiPcs integrated into OTFTs including eleven materials used in OTFTs for the first time. I then explore the influence of dielectric surface chemistry on the texture of R₂-SiPc films and their resulting performance in OTFTs using silane self-assembled monolayers and para-sexiphenyl to understand the weak epitaxial growth behaviour of this class of materials. Next, I report eight novel peripherally fluorinated and axially substituted silicon phthalocyanines (R₂-FₓSiPcs) to investigate the influence of peripheral and axial fluorination on air-stable electron transport and determine the threshold for achieving air-stable n-type OTFTs. Finally, I integrate R₂-FₓSiPcs into organic heterojunction ammonia gas sensors to understand the influence of peripheral fluorination on the majority charge carrier in this device architecture.