Temperature-Driven Phase Transition of a Fused Dithienobenzothiadiazole–Tetrathiophene Based Semiconducting Copolymer

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• 作者：Mingyuan Pei ; Jun Huang ; Mi Jang ; Ji-Hoon Kim ; Minjung Lee ; Junwu Chen ; Do Hoon Hwang ; Hoichang Yang
• 刊名：Journal of Physical Chemistry C
• 出版年：2016
• 出版时间：January 21, 2016
• 年：2016
• 卷：120
• 期：2
• 页码：903-910
• 全文大小：541K
• ISSN：1932-7455

文摘

A high-molecular-weight donor–acceptor (D–A) copolymer, pDTfBT-4T, poly(5,8-di[3-octyldodecanthiopen-5-yl]dithieno[3′,2′:3,4:2″,3″:5,6]benzo[1,2-c][1,2,5]-thiadiazole-alt-2,2′-bithiophene), including alternating dithieno[3′,2′:3,4;2″,3″:5,6]benzo[1,2-c][1,2,5]thiadiazole (DTfBT) and 3-octyldodecyltetrathiophene (4T) was synthesized by a Stille coupling polymerization. We found that pDTfBT-4T had a molecular number-average weight of 276 kg mol^–1 and formed unexpectedly strong interchain aggregates in dilute solutions at room temperature, which was similar to those in as-spun thin solid films. pDTfBT-4T thin films were spun-cast from a warm dilute chlorobenzene solution on hydrophobic polymer-treated SiO₂ dielectrics. Some were shortly annealed at various temperatures (T) for 10 min to improve π-overlapped structures as charge-carrier transport paths. The ordered domains of pDTfBT-4T in the annealed films could be tuned from one-dimensional nanorods to two-dimensional nanosheets with an increasing in T, which also provided enhanced crystal orientation. Optimizing the conjugated structures of pDTfBT-4T in the annealed films, the polymer based OFETs yielded a hole mobility up to 1.45 cm² V^–1 s^–1 as well as negligible hysteresis and excellent negative bias stability.