High efficiency OLEDs based on anthracene derivatives: The impact of electron donating and withdrawing group on the performance of OLED
High efficiency OLEDs based on anthracene derivatives: The impact of electron donating and withdrawing group on the performance of OLED
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DOI：
10.1016/j.orgel.2015.11.026
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发表时间：
2016-03-01
影响因子：
3.2
通讯作者：
Monkman, Andrew P.
中科院分区：
文献类型：
--
作者：
Aydemir, Murat;Haykir, Gulcin;Monkman, Andrew P.
合成了具有给电子或吸电子性质的侧基的新的定义明确的大体积蒽衍生物8a-d。该化合物含有取代的蒽作为中心核，在9-和10-位连接2-（4-（2-吡啶基）-苯基）乙烯基和4-R-苯基[R：H（a），OMe（B）和CF 3（c），N（Ph）（2）（d）]基团。研究了给电子基团、吸电子基团和中性基团对分子的几何物理、电荷转移（CT）、三重态转移（TT）和三重态-三重态湮灭（TTA）性质的影响。在此基础上，我们选择了最有前景的分子（8d），并在很低的电流效率下获得了EQE达到7%的高效率荧光OLED。低电流密度下的值意味着三重态融合（TF）贡献为45%，非常接近当仅单线态衰变通道对TTA开放时的最大理论值50%，然而我们认为在这种情况下TTA和TADF都有助于三重态收获以产生高EQE值，并且这种混合三重态收获通过膜的异质性而产生。在高电流密度下，实现了20000 cd/m（2）的亮度，这部分归因于材料结晶。(C)2015 Elsevier B.V.版权所有。
New well-defined bulky anthracene derivatives with side groups having electron donating or withdrawing properties 8a-d were synthesized. The compounds contain substituted anthracene as the central core attaching 2-(4-(2-pyridinyl)-phenyl)vinyl and 4-R-phenyl [R:H (a), OMe (b) and CF3 (c), N(Ph)(2) (d)] groups at 9- and 10-positions. The impact of electron donating, withdrawing and neutral groups and their influence on the molecules photophysical, charge transfer (CT), triplet transfer (TT) and triplet-triplet annihilation (TTA) properties has been investigated. Based on the photophysical studies the most promising molecule (8d) has been selected and high efficiency fluorescent OLEDs with EQE at very low current efficiency reaching 7% were obtained. The value at low current density implies a Triplet Fusion (TF) contribution of 45%, very close to the maximum theoretical value of 50% when only the singlet decay channel is open to TTA, however we believe that in this case both TTA and TADF contribute to the triplet harvesting to yield high EQE values, and this mixed triplet harvesting arises through the heterogeneity of the films. At high current density a brightness of 20000 cd/m(2) was achieved and it is assigned partially to the material crystallisation. (C) 2015 Elsevier B.V. All rights reserved.