Ultrafast Singlet Fission and Efficient Carrier Transport in a Lamellar Assembly of Bis[(trialkoxyphenyl)ethynyl]pentacene
Ultrafast Singlet Fission and Efficient Carrier Transport in a Lamellar Assembly of Bis[(trialkoxyphenyl)ethynyl]pentacene
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双[(三烷氧基苯基)乙炔基]并五苯层状组装中的超快单线态裂变和高效载流子传输
DOI：
10.1021/acs.jpcc.2c00864
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发表时间：
2022
期刊：
影响因子：
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通讯作者：
Hasobe Taku
中科院分区：
文献类型：
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作者：
Sakai Hayato;Yoshino Keisuke;Shoji Yoshiaki;Kajitani Takashi;Pu Jiang;Fukushima Takanori;Takenobu Taishi;Tkachenko Nikolai V.;Hasobe Taku
合成了在并五苯的6-和13-位上带有不同烷基链长（OCnH 2n +1;n= 6，12，16）的3，4，5-三烷氧基苯乙炔基的并五苯衍生物（PcCn），研究了链长对自组装、光学和电学性质的影响.当将PcCn的环己烷溶液快速注入异丙醇中时，PcC 6和PcC 12分别进行了可控的自组装，得到了球形和纤维状的纳米物体，而PcC 16由于其溶解性差而不能进行这种自组装.粉末X射线衍射（PXRD）分析表明，PcC 12在环己烷中呈层状结构，并五苯发色团之间发生有效重叠，导致吸收光谱特征明显展宽和红移.相比之下，基于PXRD分析，PcC 6纳米颗粒的基本组装模式的特征在于二维六方结构。虽然观察到纳米颗粒的3.35 μ m的较短的核-核分离，但从吸收性质判断，参与PcC 6组装的并五苯发色团彼此没有有效地相互作用。有趣的是，飞秒瞬态吸收光谱表明球形组装体中的PcC 6倾向于经历单重激发态的失活，而纤维状组装体中的PcC 12则表现出超快的分子间单重态裂变（表观速率常数kSF ≥ 1012 s-1）。采用PcC 120作为有源层和离子凝胶作为栅极材料制备的场效应晶体管（FET）表现出ap型行为，载流子迁移率高达2.4 × 10- 4cm-2 V-1 s-1，尽管纤维材料中纳米导电畴不连续地聚集成一个整体不利于FET的应用。通过这项研究，我们证明了侧链长度的适当设计使并五苯发色团能够组装成有利于表现出光学和电子性质的排列。
Pentacene derivatives carrying 3,4,5-trialkoxyphenylethynyl groups with different alkyl chain lengths (OCnH2n+1;n= 6, 12, 16) at the 6- and 13-positions of pentacene (denoted as PcCn) were newly synthesized to examine chain-length effects on self-assembly, optical, and electronic properties. Upon fast injection of a cyclohexane solution of PcCninto isopropyl alcohol, PcC6and PcC12underwent controlled self-assembly to give rise to spherical and fibrous nano-objects, respectively, while this self-assembly procedure could not be applied to PcC16because of its poor solubility. Powder X-ray diffraction (PXRD) analysis showed that the nanofiber of PcC12consists of a lamellar structure, where an effective overlap between the pentacene chromophores occur, resulting in significantly broadened and red-shifted absorption spectral features, compared with those observed for molecularly dispersed PcC12in cyclohexane. In contrast, based on PXRD analysis, the fundamental assembly pattern of the nanoparticle of PcC6was characterized by a two-dimensional hexagonal structure. Although a shorter core-to-core separation of 3.35 Å was observed for the nanoparticle, judging from the absorption properties, the pentacene chromophores involved in the PcC6assembly do not effectively interact with each other. Interestingly, femtosecond transient absorption spectroscopy indicated that PcC6in the spherical assembly tends to undergo deactivation of the singlet excited state, while PcC12in the fibrous assembly shows ultrafast intermolecular singlet fission (apparent rate constantkSF≥ 1012s–1). A field-effect transistor (FET) fabricated using the nanofiber of PcC12and an ion gel as the active layer and gate materials, respectively, exhibited ap-type behavior with a carrier mobility as high as 2.4 × 10–4cm2V–1s–1, despite the fact that fibrous materials, where nanoscale conducting domains discontinuously aggregate as an entity, are not favorable for FET applications. Through this study, we demonstrate that a proper design of the side-chain length enables a pentacene chromophore to assemble into an arrangement beneficial for exhibiting optical and electronic properties.