Copolyfluorenes containing pendant bipolar carbazole and 1,2,4‐triazole groups: Synthesis,characterization, and optoelectronic applications |
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| Authors: | Chia‐Shing Wu Yun Chen |
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| Institution: | 1. Department of Chemical Engineering, National Cheng Kung University, Tainan, Taiwan;2. Research Center for Energy Technology and Strategy, National Cheng Kung University, Tainan, Taiwan |
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| Abstract: | Three novel copolyfluorenes ( P1 ‐ P3 ) containing pendant bipolar groups (2.5–7.7 mol %), directly linked hole‐transporting carbazole and electron‐transporting aromatic 1,2,4‐triazole, were synthesized by the Suzuki coupling reaction and applied to enhance emission efficiency of polymer light‐emitting diodes based on conventional MEH‐PPV. The bipolar groups not only suppress undesirable green emission of polyfluorene under thermal annealing, but also promote electron‐ and hole‐affinity of the resulting copolyfluorenes. Blending the bipolar copolyfluorenes with MEH‐PPV results in significant enhancement of device performance ITO/PEDOT:PSS/MEH‐PPV+ P1 , P2 or P3 /Ca(50 nm)/Al(100 nm)]. The maximum luminance and luminance efficiency were enhanced from 3230 cd/m2 and 0.29 cd/A of MEH‐PPV‐only device to 15,690 cd/m2 and 0.81 cd/A (blend device with MEH‐PPV/ P3 = 94/6 containing about 0.46 wt % of pendant bipolar residues), respectively. Our results demonstrate the efficacy of the bipolar copolyfluorenes in enhancing emission efficiency of MEH‐PPV. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 |
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| Keywords: | bipolar carbazole conjugated polymers light‐emitting diodes (LED) luminescence polyfluorene triazole |
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