RECEPTOR-DOPED ORGANIC TRANSISTORS: TRANSDUCING ANION BINDING FROM MIXED IONIC-ELECTRONIC TRANSPORT

Organic semiconductors based on π-conjugated polymers show remarkable properties such as high tolerance to structural defects, low processing temperature requirements, biocompatibility, ease of fabrication, and tunable properties. Conjugated polymers integrated into device arrays can exhibit collective properties sensitive to minor perturbations in the surrounding media. However, these devices rely on serendipitous sensitivity to the analyte of interest, and strategies for specific detection remain a considerable change. There remains a compelling, global need for technologies to monitor phosphate due to its prevalence in agricultural runoff, leading to fish kills and economic decline for commercial and recreational fisheries. The strong hydration energies of phosphate anions, the propensity to oligomerize, and the complexity of seawater have collectively limited the progress of chromatographic, spectrophotometric, potentiometric, and in-situ sensing technologies towards phosphate detection. Despite the key challenges in the chemical recognition of anions in highly competitive aqueous environments, there have been notable strides involving supramolecular chemistries. The affinity of the receptors to their target analyte has progressed in leaps and bounds over the last two decades with new, exotic interactions involving the hydrophobic effect, metal‒anion coordination complexes, electroneutral host molecules with C‒H hydrogen bonding motifs, to name a few. This dissertation explores the utility of polarized C‒H hydrogen-bonding recognition sites in soft condensed matter electronic materials. Chapter I introduces a brief historical survey of conjugated polymers, the fundamental concepts and mechanisms behind optoelectronic sensing technologies, and the intrinsic properties found in conjugated polymer semiconductors that make them excellent candidate materials for chemical sensing applications. Chapter II establishes the experimental protocols and methods used to extract relevant device parameters to detect changes in the material properties. Chapter III-IV explores the integration and utility of charge-neutral, shape-persistent macrocycles and how the receptor influences the charge transport, morphology, analyte sensitivity/selectivity, and storage/electrochemical stability. Overall, a facile, label-free approach was achieved for real-time aqueous measurements. The combination of semiconducting polymers with next-generation receptors offers manifold opportunities for designing novel active layers that can be applied within emerging OFET-based diagnostic, healthcare, environmental monitoring, and bioelectronics platforms