Influence of alkyl chain length on the solid-state properties and transistor performance of BN-substituted tetrathienonaphthalenes
作者:Xiao-Ye Wang、Fang-Dong Zhuang、Xu Zhou、Dong-Chu Yang、Jie-Yu Wang、Jian Pei
DOI:10.1039/c4tc01369g
日期:——
Flexible side chains have not drawn much attention in the development of organic semiconductors compared to the conjugated backbone counterparts. In this work, a series of BN-substituted tetrathienonaphthalenes (BN-TTNs) with methyl to hexyl side chains were synthesized to systematically investigate the influence of alkyl chain length on the solid-state properties and transistor performance. The intrinsic electronic properties of the π-conjugated backbone were not affected by different alkyl chains, but the solid-state properties, such as molecular packing structures, energy levels, thin-film morphologies, and transistor performance, were significantly influenced. Among the six compounds, BN-TTN-C3 exhibited the highest hole mobility of 0.15 cm2 V−1 s−1, whereas BN-TTN-C2 and BN-TTN-C4 did not show any field-effect mobility. This unprecedented difference of device performance was mainly caused by different thin-film morphologies. An odd–even effect of alkyl side chains on the thin-film morphology was observed for the first time, which further greatly influenced the device performance. This pronounced influence of alkyl chain length on the device performance indicates that alkyl chains play a vital role in organic electronics and should be paid more attention in future development of organic semiconductors.
与共轭主链相比,灵活的侧链在有机半导体的发展中并未受到太多关注。在本研究中,合成了一系列用BN取代的四硫茴香烃(BN-TTNs),侧链从甲基到己基,以系统地研究烷基链长度对固态性质和晶体管性能的影响。不同的烷基链对π-共轭主链的本征电子特性没有影响,但固态性质,如分子堆积结构、能量等级、薄膜形态和晶体管性能,受到了显著影响。在六个化合物中,BN-TTN-C3展现出了最高的载流子迁移率,为0.15 cm² V⁻¹ s⁻¹,而BN-TTN-C2和BN-TTN-C4则没有表现出任何场效应迁移率。这种前所未有的器件性能差异主要源于不同的薄膜形态。首次观察到了烷基侧链对薄膜形态的奇偶效应,这进一步显著影响了器件性能。烷基链长度对器件性能的显著影响表明,烷基链在有机电子学中发挥着重要作用,未来在有机半导体的发展中应给予更多关注。