Synthesis, Morphology, and Field-Effect Transistor Characteristics of Crystalline Diblock Copolymers Consisted of Poly(3-hexylthiophene) and Syndiotactic Polypropylene

Abstract

We report the synthesis, morphology, and the field effect transistor (FET) characteristics of the crystalline diblock copolymers of poly(3-hexylthiophene) and syndiotactic polypropylene (P3HT-b-sPP). Four diblock copolymers with various sPP block lengths, P3HT16K-b-sPP3K (P1), P3HT16K-b-sPP6K (P2), P3HT16K-b-sPP9K (P3), and P3HT16K-b-sPP14K (P4), were prepared by the click coupling of N3-capped sPP and ethynyl-capped P3HT. The stereoregular crystalline block sPP developed different types of molecular stacking structures and led the P3HT domains to pack lamellar edge-on structure with improved charge transporting characteristics, as evidenced by the grazing incidence wide-angle X-ray scattering (GIWAXS), atomic force microscopy (AFM), and transmission electron microscopy (TEM). The FET hole mobilities of P1–P3 thin films were 4.15 × 10–3, 4.16 × 10–2, and 3.95 × 10–3 cm2 V–1 s–1, respectively, which were up to 1 order of magnitude higher than that of the parent P3HT thin film (1.43 × 10–3 cm2 V–1 s–1). The crystalline-stereoregular crystalline diblock P3HT-b-sPP demonstrates that using the lattice matching concept could well clarify the molecular stacking structure of conjugated polymer segments in order to further improve the performance of organic electron devices.