Impact of Precisely Localized Defects on the Chain Folding Behavior and Charge Mobility of Conjugated Polymers

Abstract

Conjugated polymers are promising materials for organic electronic devices because oftheir solution processability, mechanical flexibility, and tunable electronic structure. However, their charge transport is strongly influenced by hierarchical morphology, where chain conformation, nanoscale aggregation, and mesoscale connectivity together determine electronic performance. This dissertation explores how precise defect engineering can regulate the intrinsic morphology and charge transport of conjugated polymers. First, the kinetics of catalyst-transfer polymerization for several thiophene monomers with different side chain identities are quantitatively analyzed. Determining monomer reactivity ratios and rate constants provides guidance for controlling comonomer distribution and enables more predictable placement of structural defects along polymer chains. Using this synthetic control, defect-engineered polythiophenes with precisely positioned side chain modifications are synthesized to study the effects of precisely localized defects on chain conformation and morphology features. The results show that localized defects with different bulkiness and chemical nature can determine chain folding, crystalline homogeneity, and charge mobility, demonstrating how precise defect placement can tune morphology and electronic properties in conjugated polymers.