Design synthesis and device applications of charge transport in discotics

Abstract

Discotic liquid crystals (DLCs) are garnering attention as a promising class of one-dimensional newlineorganic semiconductors due to their unique structural and electronic properties. Despite the newlineconsiderable promise that DLCs offer, the exploration of their application as hole transport layers newline(HTLs) remains limited. To date, there is only a single reported study investigating the use of DLCs newlinein this context. This lack of extensive research highlights a substantial gap in understanding and newlineutilizing DLCs for HTL applications. This detailed study will provide insights into the alignment, newlinepacking, and interaction of DLC molecules, which are critical factors influencing their newlineperformance as HTLs. To address this gap and facilitate broader acceptance and application of newlineDLCs in photovoltaics technology, it is imperative to conduct a thorough investigation of their newlinesupramolecular morphology at the nanoscale. newlineThe primary objective of this thesis is to synthesize novel DLCs using diverse methodologies and newlinethoroughly characterize them with a focus on their potential applications. We initially focused on newlinesynthesizing chiral supramolecular columnar assemblies by employing hydrogen bonding to a newlinefluorescent core (heptazine) through two distinct strategies. One approach provided us with the newlineinsight needed to successfully synthesize fluorescent chiral DLCs. Subsequently, we synthesized newlineunsymmetrical thiophene-fused phenazine (TFP) based-DLCs that exhibited significantly reduced newlinepolarization voltage (~ 0 V) due to the asymmetric contribution of their frontier orbitals. These newlineDLCs exhibited outstanding hole-transporting properties without the need for additives, as well as newlineautonomous healing properties, surpassing spiro-based systems. Next, we synthesized newlineTetrathiafulvalene (TTF)-based DLC which has a very low oxidation potential, making it easily newlineoxidizable by iodine vapor. A stable diradical dication was synthesized with room-temperature newlineDLC properties, demonstrating excellent conductivity and structural conformation changes upon newlineoxi