Modulation of Aggregation‐Induced Emission and Electroluminescence of Silole Derivatives by a Covalent Bonding Pattern |
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Authors: | Han Nie Bin Chen Changyun Quan Dr Jian Zhou Prof Huayu Qiu Dr Rongrong Hu Prof Shi‐Jian Su Prof Anjun Qin Prof Zujin Zhao Prof Ben Zhong Tang |
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Institution: | 1. Guangdong Innovative Research Team, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou 510640 (P.R. China);2. College of Material, Chemistry and Chemical Engineering, Hangzhou Normal University, Hangzhou 310036 (P.R. China);3. Department of Chemistry, Division of Biomedical Engineering, Division of Life Science, The Hong Kong University of Science & Technology, Kowloon, Hong Kong (P.R. China) |
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Abstract: | The deciphering of structure–property relationships is of high importance to rational design of functional molecules and to explore their potential applications. In this work, a series of silole derivatives substituted with benzob]thiophene (BT) at the 2,5‐positions of the silole ring are synthesized and characterized. The experimental investigation reveals that the covalent bonding through the 2‐position of BT (2‐BT) with silole ring allows a better conjugation of the backbone than that achieved though the 5‐position of BT (5‐BT), and results in totally different emission behaviors. The silole derivatives with 5‐BT groups are weakly fluorescent in solutions, but are induced to emit intensely in aggregates, presenting excellent aggregation‐induced emission (AIE) characteristics. Those with 2‐BT groups can fluoresce more strongly in solutions, but no obvious emission enhancements are found in aggregates, suggesting they are not AIE‐active. Theoretical calculations disclose that the good conjugation lowers the rotational motions of BT groups, which enables the molecules to emit more efficiently in solutions. But the well‐conjugated planar backbone is prone to form strong intermoelcular interactions in aggregates, which decreases the emission efficiency. Non‐doped organic light‐emitting diodes (OLEDs) are fabricated by using these siloles as emitters. AIE‐active silole derivatives show much better elecroluminescence properties than those without the AIE characterisic, demonstrating the advantage of AIE‐active emitters in OLED applications. |
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Keywords: | aggregation conjugation density functional calculations luminescence structure– property relationships |
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