Design and Synthesis of Novel Triarylamine-Based Functional Polymeric Materials for Optoelectronic Applications

This study has been separated into six chapters. Chapter 1 is general introduction of triarylamine-based polymeric materials for fluorescent, electrofluorochromic and resistive memory devices. In Chapter 2, three novel high fluorescent polyimides (PIs) were readily synthesized, which the photoluminescence (PL) intensity of the solid film and the nanofiber fabricated by solution casting and electrospinning methods revealed high quantum yields of up to 32% and 35%, respectively. Furthermore, in order to investigate the fluorescent transition mechanisms of the PIs, a series of model compounds corresponding to the repeat units of PIs were also synthesized, and density functional theory calculation results were also used to support the deduction. In Chapter 3, we prepared four series of triphenylamine(TPA)-based luminogens with various functional groups (diphthalimide, tetracarboxylic acid, diphthalic anhydride, and simple TPA) and substituted groups (-H, -Br, -CHO, and -CN), and corresponding fluorescent polyimides (PIs) from triarylamine-based dianhydride monomers with various aromatic and aliphatic diamine monomers were also synthesized. In the solution state, the introduction of strong capability of electron acceptor such as formyl and cyano group in the luminogens could induce high fluorescence due to hybridized local and charge transfer transition. However, aggregated molecules containing pendant electron-accepting group in solid state revealed quenching fluorescence behavior due to intermolecular interaction and energy transfers. In Chapter 4, novel electrochromism (EC) and photoluminescence (PL)-active poly(4-cyanotriphenylamine) (CN-PTPA) was prepared by oxidative coupling polymerization from 4-cyanotriphenylamine (CN-TPA) using FeCl3 as an oxidant. The EFC devices of CN-PTPA exhibited excellent reversibility over 9000 sec, rapid response time less than 0.4 sec over the oxidation process, and the highest PL contrast ratio (Ioff/Ion) of 242 between fluorescent neutral state and non-fluorescent oxidized state. In addition, by introducing Heptyl viologen (HV) into the electrolyte as charge balance agent, the obtained EFC devices not only could reduce the oxidative potential but also the recovery time from oxidized to neutral states, thus the performance could be further enhanced than ever. In Chapter 5, a series of poly(triphneylamine)s (CN-PTPA, 2CN-PTPA, 3CN-PTPA, and NO2-PTPA) with pendent acceptors (cyano, dicyanovinyl, tricyanovinyl, and nitro) have been readily synthesized by oxidative coupling polymerization. The tunable memory properties of the ITO/polymer/Al sandwiched memory devices including DRAM, SRAM, and WORM could be achieved by introducing substituent acceptors with different extent of electronic delocalization and electron-withdrawing intensity into the poly(triphenylamine)s. Chapter 6 is conclusions. The basic characterization, photoluminescent, electrochemical, electrofluorochromic and memory behaviors of these triarylamine-based polymers were investigated and compared. Thus, these triarylamine-based polymers could be a candidate for not only light-emitting materials, electrofluorochromic and memory devices but also for widely modern optoelectronic device due to their good thinfilm forming ability, good thermal stability, good electrical, electrochemical and photophyscial properties.