Blue‐light‐emitting polyfluorene functionalized with triphenylamine and cyanophenylfluorene bipolar side chains |
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| Authors: | Ying Lin Teng‐Ling Ye Yu Chen Dong‐Ge Ma Zhi‐Kuan Chen Yan‐Feng Dai Yong‐Xi Li |
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| Affiliation: | 1. Key Laboratory for Advanced Materials, Institute of Applied Chemistry, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China;2. State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China;3. Synthesis and Integration, Institute of Materials Research and Engineering, 3 Research Link, Singapore 117602, Singapore |
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| Abstract: | A new bipolar conjugated polyfluorene copolymer with triphenylamine and cyanophenylfluorene as side chains, poly{[9,9‐di(triphenylamine)fluorene]‐[9,9‐dihexyl‐fluorene]‐[2,7‐bis(4′‐cyanophenyl)‐9,9′‐spirobifluorene]} ( PTHCF ), was synthesized for studying the polymer backbone emission. Its absolute weight‐average molecular weight was determined as 4.85 × 104 by using gel permeation chromatography with a multiangle light scattering detector. In contrast to the electronic absorption spectrum in dilute solution, the absorbance of PTHCF in thin film was slightly blue shifted. By comparison of the solution and thin‐film photoluminescence (PL) spectra, a red shift of Δλ = 8–9 nm was observed in the thin‐film PL spectrum. The HOMO and LUMO energy levels of the resulting polymer were electrochemically estimated as ?5.68 and ?2.80 eV, respectively. Under the electric‐field intensity of 4.8 × 105 V cm?1, the obtained hole and electron mobilities were 2.41 × 10?4 and 1.40 × 10?4 cm2 V?1 s?1, respectively. An electroluminescence device with configuration of ITO/PEDOT:PSS/ PTHCF 70%+PBD30%/CsF/Ca/Al exhibited a deep‐blue emission as a result of excitons formed by the charges migrating along the full‐fluorene main chain. The incorporation of the bipolar side chains into the polymer structure prevented the intermolecular interaction of the fluorene moieties, balance charge injection/transport, and thereby improve the polymer backbone emission. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010 |
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| Keywords: | backbone emission bipolar side chains charge transfer copolymerization cyanophenylfluorene light‐emitting diodes (LEDs) PLED polyfluorene synthesis triphenylamine UV– vis spectroscopy |
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