Kai A. I. Zhang, Youtian Tao, Chuluo Yang
Nov 14, 2008
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Chemistry of Materials
Abstract
Three new carbazole copolymers, poly(9-(2,5-diarene-[1,3,4]oxadiazole)-carbazole-alt-9-(2-ethylhexyl)-carbazole-3,6-diyl)s (P1), poly(9-(2,5-diarene-[1,3,4]oxadiazole)-2, 7-carbazole-alt-9-(2-ethylhexyl)-3, 6-carbazole-diyl)s (P2), and poly(9-(2,5-diarene-[1,3,4]oxadiazole)-carbazole-alt-9-(2-ethylhexyl)-carbazole-2,7-diyl)s (P3), were synthesized by the Suzuki coupling reaction. The copolymers were characterized by 1H NMR, 13C NMR, and elements analysis, and their molecular weights were estimated using gel permeation chromatography. The TGA and DSC results revealed their good thermal stability with high glass-transition temperatures (Tg) at 211 °C (P1), 194 °C (P2), and 208 °C (P3), respectively. The copolymers exhibited blue emission with significantly improved fluorescence quantum efficiencies compared to their analogous polymers. The triplet energies of P1, P2, and P3 were determined to be 2.52, 2.42, and 2.32 eV, respectively, from their phosphorescent spectra at 77 K. The HOMO/LUMO levels of the car...