Linearly polarized electroluminescence from ionic iridium complex-based metallomesogens: the effect of aliphatic-chain on their photophysical properties
Linearly polarized electroluminescence from ionic iridium complex-based metallomesogens: the effect of aliphatic-chain on their photophysical properties
复制标题
基于离子铱配合物的金属介晶的线性偏振电致发光：脂肪链对其光物理性质的影响
DOI：
10.1039/c7tc05421a
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
Yafei Wang
中科院分区：
文献类型：
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作者：
Xiugang Wu;Guohua Xie;Christopher P. Cabry;Xiaoyu Xu;Stephen J. Cowling;Duncan W. Bruce;Weiguo Zhu;Etienne Baranoff;Yafei Wang
直接偏振的有机发光二极管（OLED）具有显著提高效率和降低液晶显示器（LCD）的成本以及其它应用的潜力。然而，荧光液晶目前用于实现这一点，而磷光发光体将进一步提高效率。为此，本文设计并制备了具有不同脂肪链取代基的离子型铱配合物金属介晶7a和7 b。这两种铱配合物显示近晶相的差示扫描量热法，偏光显微镜和X-射线衍射证明。铱配合物在溶液和固体状态下都有深红色的荧光发射，配合物7a在THF-水混合溶剂中有明显的聚集诱导荧光（AIE）行为。制备了以配合物7a和7 b为发光体的非掺杂偏振OLED，并获得了偏振比为4的直接线偏振电致发光，这是金属介晶基磷光OLED的最高偏振比。重要的是，核心复合物和介晶侧基之间的连接基的选择是实现电致发光和AIE的独特偏振的关键。这些结果是朝着开发能够有效地产生偏振电致发光的磷光OLED迈出的第一步。
Directly polarized organic light emitting diodes (OLEDs) have the potential to significantly improve the efficiency and reduce the cost of liquid-crystal displays (LCDs) among other applications. However, fluorescent liquid crystals are currently used to achieve this, while phosphorescent emitters would further improve efficiency. To this end, the metallomesogens based on ionic iridium complexes bearing different aliphatic chains substituent, named 7a and 7b, were designed and prepared in this contribution. Both iridium complexes showed smectic mesophase evidenced by differential scanning calorimetry, polarized optical microscopy and X-ray diffraction. Deep-red emission was observed for the iridium complexes in solution and solid state, and complex 7a clearly presented aggregation-induced emission (AIE) behavior in THF–water solvent mixture. Non-doped polarized OLEDs employing complex 7a or 7b as emitter were fabricated and direct linearly polarized electroluminescence with a polarization ratio of 4 was achieved, which is the highest ratio reported for metallomesogens-based phosphorescent OLEDs. Importantly, the choice of linker between the core complex and mesogenic pendent groups is key to achieve distinctive polarization of electroluminescence and AIE. These results are a first step towards the development phosphorescent OLEDs able to efficiently produce polarized electroluminescence.