側鏈含Carbazole及/或Benzothiadiazole衍生物之乙烯共聚高分子：合成與光電性質

Abstract

Phosphorescent organic light-emitting devices based on polymers have recently been widely studied owing to its high efficiency. The research in this essay also focuses on this topic with the particular concentration on the synthesis, characterization and investigation of opto-electronic properties of the new carbazole-based vinyl copolymers. Two new vinyl copolymers poly(9-(4-vinylphenyl)-9H-carbazole-co-4-phenyl-7-(4-vinylphenyl)benzo[c][1,2,5]thiadiazole) (P1) and poly(9-(4-vinylphenyl)-9H-carbazole-co-3,6-bis(9,9-dip-tolyl-9H-fluoren-2-yl)-9-(4-vinylphenyl)-9H-carbazole) (P2) containing pendant carbabazole derivatives with or without fluorene segments and/or pendant benzothiadiazole derivative have been synthesized by free radical polymerization reaction and characterized by 1H NMR, FT-IR, GPC and elemental analysis (EA). Thermal properties were determined by TGA and DSC. Optical and electrochemical properties were investigated by UV-Vis, PL spectroscopy and cyclic voltammetry. Chapter 3 presents the characterization, optical and electrochemical properties of P1. The P1 exhibited good thermal stability with glass transition temperature (Tg) at 132oC and decomposition temperature (Td) (at 5% weight loss) at 396oC. The PL spectrum of P1 showed emission band peaking at position 499 nm which completely overlap with emission band of benzothiadiazole derivative. The high triplet energy 2.65 eV and reasonable HOMO, LUMO energy levels -5.59, -3.06 eV suggest this polymer can be applied as the host material for green or red electrophosphorescence. Chapter 4 presents the characterization, optical and electrochemical properties of P2. The P2 also revealed good thermal stability with Tg at 130oC and Td at 401oC. The PL spectrum of P2 displayed at similar position as monomer containing fluorene at 385 and 402 nm. This polymer demonstrated high triplet energy (2.46 eV) and high HOMO energy level (-5.28 eV), which attain characteristics to be a host material for phosphorescent polymer light-emitting devices. Besides, the reasonable HOMO energy level (due to the presence of pendant carbazole units) also makes it a promising candidate of hole-transporting layer.