Thiophene-Diketopyrrolopyrrole-Based Quinoidal Small Molecules as Solution-Processable and Air-Stable Organic Semiconductors: Tuning of the Length and Branching Position of the Alkyl Side Chain toward

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• 作者：Chao Wang ; Yunke Qin ; Yuanhui Sun ; Ying-Shi Guan ; Wei Xu ; Daoben Zhu
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2015
• 出版时间：July 29, 2015
• 年：2015
• 卷：7
• 期：29
• 页码：15978-15987
• 全文大小：578K
• ISSN：1944-8252

文摘

A series of thiophene-diketopyrrolopyrrole-based quinoidal small molecules (TDPPQ-2鈥?b>TDPPQ-5) bearing branched alkyl chains with different side-chain lengths and varied branching positions are synthesized. Field-effect transistor (FET) measurement combined with thin-film characterization is utilized to systematically probe the influence of the side-chain length and branching position on the film microstructure, molecular packing, and, hence, charge-transport property. All of these TDPPQ derivatives show air-stable n-channel transporting behavior in spin-coated FET devices, which exhibit no significant decrease in mobility even after being stored in air for 2 months. Most notably, TDPPQ-3 exhibits an outstanding n-channel semiconducting property with electron mobilities up to 0.72 cm² V^鈥? s^鈥?, which is an unprecedented value for spin-coated DPP-based n-type semiconducting small molecules. A balance of high crystallinity, satisfactory thickness uniformity and continuity, and strong intermolecular interaction accounts for the superior charge-transport characteristics of TDPPQ-3 films. Our study demonstrates that tuning the length and branching position of alkyl side chains of semiconducting molecules is a powerful strategy for achieving high FET performance.