Development of N-alkyl-substituted bis (pyrrolo [3,4 -d])tetrathiafulvalenes as organic semiconductors for solution-processible field-effect transistors
Development of N-alkyl-substituted bis (pyrrolo [3,4 -d])tetrathiafulvalenes as organic semiconductors for solution-processible field-effect transistors
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DOI：
10.1021/cm070956
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发表时间：
2007-09
影响因子：
8.6
通讯作者：
I. Doi;E. Miyazaki;K. Takimiya;Y. Kunugi
中科院分区：
文献类型：
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作者：
I. Doi;E. Miyazaki;K. Takimiya;Y. Kunugi
合成了一系列 N-烷基取代的双（吡咯并[3,4-d]）四硫富瓦烯（PyTTF，烷基 = 正丁基、正辛基、正十二烷基、正十六烷基和正二十烷基，3-7）作为高溶解度的四硫富瓦烯 (TTF) 衍生物。它们的固态结构通过 X 射线衍射进行了表征，并评估了它们作为可溶液加工有机场效应晶体管 (OFET) 器件的半导体的适用性。虽然TTF衍生物的溶解度随着烷基的引入而增强，但是非常长的烷基，例如正二十烷基，可能由于非常长的烷基之间的分子间疏水相互作用而降低了溶解度。固态结构也受到烷基长度的影响；具有正十二烷基或更长烷基的分子5-7在块状单晶和旋涂薄膜中都倾向于呈现二维(2-D)分子有序性。相比之下，具有短正丁基和正辛基的3和4在固态下不呈现二维相互作用结构。与 PyTTF 衍生物的固态结构一致，溶液处理的 OFET 的场效应晶体管 (FET) 特性明显取决于烷基的长度。与相对较差的半导体层（μ FET = ∼10 -5 cm 2 V -1 s -1 或无可再现场效应）的旋涂薄膜 3 和 4 相比，由 5-7 旋涂薄膜组成的 OFET 器件表现出典型的 p 沟道 FET 特性，即空穴迁移率 ∼ 10 -2 cm 2 V -1 s -1 和电流开/关比为 ∼10 4.结果表明，π-共轭核与长烷基的适当组合可以提供适用于可溶液加工的 OFET 的可溶有机半导体。
A series of N-alkyl-substituted bis(pyrrolo[3,4-d])tetrathiafulvalenes (PyTTFs, alkyl = n-butyl, n-octyl, n-dodecyl, n-cetyl, and n-icosyl, 3-7) were synthesized as highly soluble tetrathiafulvalene (TTF) derivatives. Their solid-state structures were characterized by X-ray diffraction, and their suitability for use as semiconductors for solution-processible organic field-effect transistor (OFET) devices was evaluated. Whereas the solubility of the TTF derivatives was enhanced with the introduction of alkyl groups, very long alkyl groups, such as the n-icosyl group, reduced the solubility probably due to intermolecular hydrophobic interactions between the very long alkyl groups. The solid-state structure was also influenced by the length of the alkyl groups; molecules 5-7 having n-dodecyl or longer alkyl groups tended to assume two-dimensional (2-D) molecular ordering both in the bulk single crystals and in the spin-coated thin films. In contrast, 3 and 4, having short n-butyl and n-octyl groups, did not take on a 2-D interactive structure in the solid state. Consistent with the solid-state structure of the PyTTF derivatives, field-effect transistor (FET) characteristics of the solution-processed OFETs markedly depended on the length of the alkyl groups. In contrast to spin-coated thin films of 3 and 4, which were relatively inferior semiconducting layers (μ FET = ∼10 -5 cm 2 V -1 s -1 or no reproducible field effect), OFET devices consisting of spin-coated thin films of 5-7 showed typical p-channel FET characteristics, namely, hole mobilities of ∼ 10 -2 cm 2 V -1 s -1 and current on/off ratios of ∼10 4 . The results indicate that an appropriate combination of a π-conjugated core with long alkyl groups could provide soluble organic semiconductors that are applicable to solution-processible OFETs.