Microfluidic Crystal Engineering of 蟺-Conjugated Polymers

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• 作者：Gang Wang ; Nils Persson ; Ping-Hsun Chu ; Nabil Kleinhenz ; Boyi Fu ; Mincheol Chang ; Nabankur Deb ; Yimin Mao ; Hongzhi Wang ; Martha A. Grover ; Elsa Reichmanis
• 刊名：ACS Nano
• 出版年：2015
• 出版时间：August 25, 2015
• 年：2015
• 卷：9
• 期：8
• 页码：8220-8230
• 全文大小：829K
• ISSN：1936-086X

文摘

Very few studies have reported oriented crystallization of conjugated polymers directly in solution. Here, solution crystallization of conjugated polymers in a microfluidic system is found to produce tightly 蟺-stacked fibers with commensurate improved charge transport characteristics. For poly(3-hexylthiophene) (P3HT) films, processing under flow caused exciton bandwidth to decrease from 140 to 25 meV, 蟺鈥撓€ stacking distance to decrease from 3.93 to 3.72 脜 and hole mobility to increase from an average of 0.013 to 0.16 cm² V^鈥? s^鈥?, vs films spin-coated from pristine, untreated solutions. Variation of the flow rate affected thin-film structure and properties, with an intermediate flow rate of 0.25 m s^鈥? yielding the optimal 蟺鈥撓€ stacking distance and mobility. The flow process included sequential cooling followed by low-dose ultraviolet irradiation that promoted growth of conjugated polymer fibers. Image analysis coupled with mechanistic interpretation supports the supposition that 鈥渢ie chains鈥?provide for charge transport pathways between nanoaggregated structures. The 鈥渕icrofluidic flow enhanced semiconducting polymer crystal engineering鈥?was also successfully applied to a representative electron transport polymer and a nonhalogenated solvent. The process can be applied as a general strategy and is expected to facilitate the fabrication of high-performance electrically active polymer devices.