Poly[(2-alkoxy-5-methyl-1,3-phenylene vinylene)-alt-(phenylene vinylene)] derivatives with different contents ofcis- andtrans-olefins: The effect of the olefin bond geometry and conjugation length on luminescence (original) (raw)

Journal of Polymer Science Part A: Polymer Chemistry, 2003

Abstract

Poly[(2-alkyloxy-5-methyl-1,3-phenylenevinylene)-alt-(1,3-phenylenevinylene)]s (8) and poly[(2-alkyloxy-5-methyl-1,3-phenylenevinylene)-alt-(1,4-phenylenevinylene)]s (10) were synthesized by the Wittig reaction to provide materials containing 45–62% cis-vinylene bonds. The optical characteristics of 8 and 10 were compared with those of their respective isomers, 3 and 4, the cis-vinylene contents of which were significantly lower (9–16%). Although a greater fraction of cis-CHCH linkages caused the absorption maximum (λmax) of 8 and 10 to be slightly blueshifted (by ∼3–6 nm) from that of 3 and 4, the impact of the vinylene bond geometry appeared to be negligible on their fluorescence spectra. The fluorescence quantum efficiencies of 8 and 10 were estimated to be approximately 0.25 and 0.72, respectively. Both 8 (λmax ≈ 445 or 462 nm) and 10 (λmax ≈ 480 or 506 nm) were electroluminescent, showing effective color tuning by the controlled insertion of m-phenylene moieties. The external electroluminescence quantum efficiencies were determined to be 4.26 × 10−3% for 8 and 0.63% for 10. The cis/trans-vinylene bond ratio had a great impact on the electroluminescence device performance of 8 but a much smaller impact on the performance of 10. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 303–316, 2004

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