title: A Physicochemical Approach Toward Extending Conjugation and the Ordering of Solution-Processable Semiconducting Polymers.
abstract: Poly(3-hexylthiophene)s (P3HTs) were synthesized with a well-controlled molecular weight (Mw) and degree of regioregularity; additionally, π-conjugated P3HT structures in both solutions and films were systematically investigated. Conjugated P3HT phases in spin-cast films significantly changed from ordered nanorods, -fibrils, and -ribbons to less-ordered granules, depending on the conformation of the P3HT chains in solutions. The chain conformations could be physicochemically adjusted by modifying chain lengths (from 5 to 45 kDa), solvents, and ultrasonication. Highly extended conformations of the P3HT in ultrasound-treated solutions yielded longer degree of conjugation both the intra- and intermolecularly. When toluene was used as a marginal solvent, ultrasonicated 0.1 wt % 29 kDa P3HT solutions could be used to yield highly ordered aggregates in spin-cast films, including nanoribbons or nanosheets, with field-effect mobility (μFET) up to ∼0.1 cm(2) V(-1) s(-1) being measured for organic field-effect transistors (OFETs). However, ultrasonicated chloroform systems with good P3HT solubility (for P3HT Mw ≥ 20 kDa) yielded featureless conducting layers even at 0.4 wt % P3HT content. However, these film-based OFETs yielded μFET values up to 0.04 cm(2) V(-1) s(-1), which were much greater than 0.004 cm(2) V(-1) s(-1) for the nonultrasonicated systems.
authors.affiliation: Department of Applied Organic Materials Engineering, Inha University , Incheon 22212, Republic of Korea.
authors.forename: Minjung
authors.initials: M
authors.lastname: Lee
authors.affiliation: Center for Materials Architecturing, Korea Institute of Science and Technology , Seoul 02792, Republic of Korea.
authors.forename: Hyeonyeol
authors.initials: H
authors.lastname: Jeon
authors.affiliation: Department of Applied Organic Materials Engineering, Inha University , Incheon 22212, Republic of Korea.
authors.forename: Mi
authors.initials: M
authors.lastname: Jang
authors.affiliation: Department of Applied Organic Materials Engineering, Inha University , Incheon 22212, Republic of Korea.
authors.forename: Hoichang
authors.initials: H
authors.lastname: Yang
keywords: conjugation; nanoribbon; organic field-effect transistor; poly(3-hexylthiophene); self-assembly; ultrasonication