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A Novel Bipolar Electroluminescent Poly(arylene ethynylene) Consisting of Carbazole and Diethynylthiophene Units
Author(s) -
Zhan Xiaowei,
Liu Yunqi,
Zhu Daoben,
Jiang Xuezhong,
Jen Alex K.Y.
Publication year - 2001
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/1521-3935(20010701)202:11<2341::aid-macp2341>3.0.co;2-b
Subject(s) - carbazole , electroluminescence , materials science , arylene , thermal stability , moiety , photochemistry , homo/lumo , cyclic voltammetry , polymer chemistry , polymer , thermal decomposition , layer (electronics) , chemistry , molecule , electrode , organic chemistry , aryl , composite material , alkyl , electrochemistry
A novel bipolar conjugated copolymer poly[(2, 5‐diethynylthienylene)‐ alt ‐ co ‐(9‐hexyl‐3,6‐carbazole)] (PCT) bearing electron‐affinitive moiety of 2,5‐diethynylthiophene and hole‐transport moiety of carbazole was synthesized via a Pd‐catalyzed coupling reaction. The polymer possesses a weight average molecular weight of 23 000 with a polydispersity index of 2.5. PCT exhibits good thermal stability with a glass‐transition temperature of 103°C and an onset decomposition temperature of 338°C. The HOMO and LUMO energy levels of PCT were determined to be –5.36 and –2.46 eV, respectively, using cyclic voltammetry. Single‐layer and multilayer light‐emitting diodes emit yellow light (peak at ≈ 580 nm). Double‐layer electroluminescent device with the structure of ITO/copper phthalocyanine/PCT/Ca/Ag has an external quantum efficiency of 0.01%, higher than that of three‐layer device with the structure of ITO/copper phthalocyanine/PCT/Alq 3 /Al, indicating that the electron injection is the limiting factor for the performance of PCT in polymer light‐emitting diodes.