Synthesis and characterization of thermally crosslinkable hole‐transporting polymers for PLEDs |
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| Authors: | Sang‐Mi Park Kyoung‐Soo Yook Woo‐Hyung Lee Yongtaek Hong Jun‐Yeob Lee In‐Nam Kang |
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| Affiliation: | 1. Department of Chemistry, The Catholic University of Korea, , Bucheon, Gyeonggi‐do, 420–743 Korea;2. Department of Polymer Science and Engineering, Dankook University, , Yongin, Korea;3. Department of Electrical Engineering and Computer Science, Seoul National University, , Seoul, 151–744 Korea |
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| Abstract: | Two new thermally crosslinkable hole‐transporting polymers, X‐PTPA and X‐PCz, were synthesized via Yamamoto coupling reactions. The number‐averaged molecular weights (Mn) of X‐PTPA and X‐PCz were found to be 45,000 and 48,000, respectively, and therewith, polydispersity indices were of 1.8 and 1.7, respectively. Thermally crosslinked X‐PTPA and X‐PCz exhibit excellent solvent resistance and stable optoelectronic properties. The UV–visible maximum absorption peaks of X‐PTPA and X‐PCz in the thin film state are at 389 and 322 nm, respectively. The HOMO levels of X‐PTPA and X‐PCz are estimated to be ?5.27 and ?5.39 eV, respectively. Multilayered devices (ITO/crosslinked X‐PTPA or X‐PCz/SY‐PPV/LiF/Al) were fabricated with SY (SuperYellow) as the emitting layer. The maximum efficiency of the multilayered device with a crosslinked X‐PTPA layer is approximately three times higher than that of the device without a crosslinked X‐PTPA layer and much higher than that of the crosslinked X‐PCz device. This result can be explained by the observations that crosslinked X‐PTPA produces increased electron accumulation within the emitter, SY, and also efficient exciton formation due to improved charge balance. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 5111–5117 |
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| Keywords: | charge transport conjugated polymers functionalization of polymers heteroatom‐containing polymers light‐emitting diodes (LED) |
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