摘要/Abstract
萘二酰亚胺类共轭分子是一类经典且被广泛研究的有机半导体材料. 在本工作中, 通过亲芳核取代反应将手性环己二胺引入萘二酰亚胺的两端合成了光学纯化合物(I-R, I-S), 内消旋化合物(I-R,S), 以及经I-R和I-S等物质的量共混得到的外消旋混合物(I-rac), 并对这些化合物的紫外-可见吸收光谱、圆二色谱及电化学性质进行了研究. 光学纯(I-R, I-S)和消旋体(I-R,S, I-rac)材料在溶液状态下的光谱吸收完全一致, 但其薄膜吸收存在差异, 消旋体薄膜的最大吸收峰较光学纯材料红移了约5 nm, 这表明它们的聚集态结构有所不同. 以这些化合物或混合物为活性层制备的有机场效应晶体管(OFET)在氮气条件下均表现出p型半导体特征. 其中, 内消旋体(I-R,S)和外消旋体(I-rac) OFET器件的空穴迁移率分别为0.074和0.075 cm2•V–1•s–1, 均高于光学纯材料I-R和I-S的器件性能(空穴迁移率约为0.04 cm2•V–1•s–1). 研究结果表明, 手性诱导分子组装产生不同的聚集态结构, 从而对材料的器件性能产生一定影响, 这为萘二酰亚胺类有机功能分子的发展提供了新思路.
关键词: 萘二酰亚胺, 手性, 聚集态结构, 有机场效应晶体管
Naphthalene diimides (NDI)-based conjugated molecules were a class of typical and widely studied organic semiconducting materials. The optically pure compounds (I-R and I-S) and mesomer (I-R,S) by SNAr reactions between tetraboromo-NDI and 1,2-diaminocyclohexane were designed and synthesized, moreover, the racemic mixture (I-rac) was obtained by mixing I-R and I-S equimolarly. The UV-vis absorption spectroscopy, cyclic voltammetry, and circular dichroism of four materials were studied. The UV-Vis absorptions in solution were consistent, while the absorptions in film were slightly different between the optically pure compounds and the mesomer or raceme, indicating the different aggregate structures. Accordingly, the organic field-effect transistors (OFET) by using these materials as the active layer were prepared. They all exhibited p-type organic semiconducting characteristics under nitrogen conditions. Meanwhile, mesomer (I-R,S) and raceme (I-rac) showed better OFET device performance (hole mobility: about 0.075 cm2•V–1•s–1) than that of the optically pure compounds I-R and I-S (hole mobility: about 0.04 cm2•V–1•s–1). The atomic force microscopy (AFM) studies demonstrated that thin films of mesomer (I-R,S) and raceme (I-rac) annealed at 100 ℃ showed larger form size of microstructures with fewer grain boundaries, which was consistent with the enhanced device performance after thermal annealing. This paper proved that the chirality influenced the molecule self-assembly, packing structure and the resulting device performance.
Key words: naphthalene diimides, chirality, aggregate structure, organic field-effect transistors
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