Three Structural Isomers of Dinaphthothieno[3,2-<i>b</i>]thiophenes: Elucidation of Physicochemical Properties, Crystal Structures, and Field-Effect Transistor Characteristics
作者:Tatsuya Yamamoto、Shoji Shinamura、Eigo Miyazaki、Kazuo Takimiya
DOI:10.1246/bcsj.20090230
日期:2010.2.15
In order to gain an insight into the relationship between the molecular structure and the semiconductor characteristics of highly π-extended heteroarene-based organic semiconductors, three structural isomers of dinaphthothieno[3,2-b]thiophenes with C2h symmetry were investigated. Of these, two isomers, dinaphtho[2,1-b:2′,1′-f ]thieno[3,2-b]thiophene (2) and dinaphtho[1,2-b:1′,2′-f ]thieno[3,2-b]thiophene (3), were newly synthesized, characterized, and utilized as active semiconducting layers in organic field-effect transistors (FETs). Detailed investigation of the physicochemical properties of 2 and 3, together with another isomer, dinaphtho[2,3-b:2′,3′-f ]thieno[3,2-b]thiophene (1), indicated that the electronic structures of the three isomers are fairly different from each other despite having the same molecular formula and the same aromatic constituents. Comparison of the molecular arrangements in the crystals elucidated by X-ray structural analysis implied that the molecular shape and the thus-induced favorable intermolecular interactions play important roles in determining the entire molecular arrangement. The characteristics of 2- and 3-based FETs with maximum field-effect mobilities (μFET s) of 10−3–10−2 cm2 V−1 s−1 were inferior to those of 1-based FETs with μFET s up to 3.0 cm2 V−1 s−1. The inferior characteristics of 2- and 3-based devices were due to film morphology as elucidated by atomic force microscopy (AFM) and supported by theoretical calculations of electronic structure in the solid state. Together, the results indicate that the molecular structure and shape, even for similar heteroarenes with the same molecular formula and symmetry, are important parameters to determine the solid-state properties of organic semiconductors.
为了深入了解高π延伸杂芳烃基有机半导体的分子结构与半导体特性之间的关系,研究了具有 C2h 对称性的二萘并[3,2-b]噻吩的三种结构异构体。其中,两种异构体,二萘并[2,1-b:2′,1′-f ]噻吩并[3,2-b]噻吩(2)和二萘并[1,2-b:1′,2′-f]噻吩[3,2-b]噻吩(3)进行了新的合成、表征,并将其用作有机场效应晶体管(FET)中的活性半导体层。对 2 和 3 以及另一种异构体二萘并[2,3-b:2′,3′-f ]噻吩并[3,2-b]噻吩(1)的理化性质进行的详细研究表明,尽管这三种异构体具有相同的分子式和相同的芳香成分,但它们之间的电子结构却有相当大的差异。通过 X 射线结构分析阐明的晶体中分子排列的比较表明,分子形状和由此引起的有利的分子间相互作用在决定整个分子排列中起着重要作用。2 基和 3 基场效应晶体管的最大场效应迁移率(μFET s)为 10-3-10-2 cm2 V-1 s-1,其特性不如 1 基场效应晶体管(μFET s 高达 3.0 cm2 V-1 s-1)。原子力显微镜(AFM)阐明了 2 基和 3 基器件的劣质特性与薄膜形态有关,固态电子结构的理论计算也支持了这一点。这些结果表明,即使是分子式和对称性相同的类似杂环戊烯,其分子结构和形状也是决定有机半导体固态特性的重要参数。