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Effect of Side Chain Alkyl Length on the Electroluminescence Characteristics of Carbazole‐Based Light Emitting Polymers
Author(s) -
Chao ChingShiun,
Whang WhaTzong,
Hung ChinHsien
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(20011001)202:14<2864::aid-macp2864>3.0.co;2-d
Subject(s) - carbazole , electroluminescence , side chain , wittig reaction , alkyl , polymer , copolymer , steric effects , materials science , photochemistry , polymer chemistry , chemistry , organic chemistry , nanotechnology , layer (electronics) , composite material
Three carbazole‐based copolymers with different long side chains were synthesized using the Wittig reaction. These three copolymers and model compound were characterized by nuclear magnetic resonance (NMR) spectroscopy to determine the cis / trans ratio. The cis / trans ratios decrease with the side chain length due to the variation in the degree of steric hindrance in the Wittig reaction. They affect the electroluminescence (EL) characteristics of the carbazole‐based light emitting polymers. As the length of the side chain increases the wavelength of the emitted light increases proportionally whereas a decrease in the threshold voltages, 5.2, 4.8, 2.5 V was observed. However, EL intensity at same applied voltage increases with the length of the side chain. The energy levels of these three copolymers were also investigated to account for the phenomenon. Key words: carbazole, cis ‐ trans ratio and electroluminescence.