Advancing Organic Electronics with Naphthodithiophene-based Materials

Abstract

Bent naphthodithiophenes (NDTs) represent an emerging class of π-extended heteroaromatic frameworks that exhibit tunable electronic properties, structural rigidity, and photostability, making them promising scaffolds for organic electronic materials. This dissertation investigates the synthesis, structural behavior, and photophysical properties of isomeric bent NDTs and their small molecule derivatives. Chapter one explores the history and development of organic electronic materials to contextualize the design and application of NDT-based chromophores. In chapter two, the photophysical properties of isomeric α- and β-NDT end-capped push-pull fluorophores is evaluated to determine the influence of remote substituents. The α(OHex)R₂ series was found to exhibit efficient conjugation between aryl end-caps and the NDT core, whereas the β(Oi-Pent)R₂ series showed limited communication unless strong electron-withdrawing substituents are introduced. Chapter three introduces imine-functionalized symmetric α-NDT derivatives with push-pull systems, developed to probe existence intramolecular N···S interactions, poised to enforce rigidity and enhanced photophysical properties. Spectroscopic, crystallographic, and computational analyses reveal that these interactions stabilize the chromophores while electron-withdrawing groups enhance photophysical responses. In chapter four, asymmetric α-NDT monoimines are synthesized to generate V-shaped donor–π–acceptor systems with enhanced intramolecular charge transfer mechanism (ICT) exhibiting narrow optical bandgaps (2.68–2.72 eV) with broad absorbance and emission spectra. In chapter five, β-NDT diimines with push-pull systems that exhibit shallow conformational landscapes and weak photoluminescence due to torsional flexibility are synthesized. Finally, chapter six summarizes the structure–property relationships identified and outlines future directions for developing NDT-based architectures with improved rigidity and extended conjugation for organic electronic applications.