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Three distinct types of poly­(3-hexylthiophene) (P3HT)-based crystals were developed using unseeded and seeded protocols. First, unseeded flat fibrillar and scrolled half-ring-like crystals were prepared by isothermal crystallization of homo-P3HT and P3HT-b-poly­(ethylene glycol) (PEG) block copolymers. Anisotropic accumulation of grafted coily PEG blocks on the opposite surfaces of P3HT half-rings having extended backbones reflected scrolling, and their subsequent crystallization also further intensified this scrolling. The PEGs assembled into lamellae on both sides of P3HT half-rings with dissimilar crystalline features, i.e., the outer PEG lamella was thicker (17.4 nm) and wider (23.1 nm) compared to the inner one (15.0 and 18.1 nm). Furthermore, the crystallinity of PEG coily blocks accumulated on the P3HT crystals did not change the extended state of P3HT backbones (17.5 nm) and also the thickness of half-rings (11.0 nm). Second, with seeding homogeneous P3HT7000-b-PEG5000 solution using homo-PEG5000 tiny crystals, the cubic PEG single crystals were sandwiched between grafted regioregular P3HT chains (>99%). The appearance of (020)P3HT and (100)P3HT spots for tethered P3HTs beside (120)PEG prisms demonstrated flat-on orderly tethered P3HT backbones on the PEG single crystalline substrate. Via conjunction between block copolymer and homopolymer single crystals in channel (PEG)/wire (P3HT-covered PEG)/channel (PEG) epitaxials, the P3HT rigid brushes were found to be extended (17.35 nm) on lamellar PEG substrate (6.15 nm). Third, when homogenized P3HT7000-b-PEG5000 solutions were seeded by homo-P3HT7000 tiny crystals, the edge-on orientated fibrillar P3HT single crystals were acquired. Although the thickness (20–22 nm) and length (60–63 μm) of P3HT7000-b-PEG5000 fibrillar single crystals resembled those of homo-P3HT7000 ones, their backbone lamination in the c axis were significantly different (2 versus 21); because the P3HT backbones were not capable of laminating from the coily block sides.

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Highly uniform and conductive single crystals of poly(3‐hexylthiophene) (P3HT)‐based homo and block copolymers with the end coily blocks of polystyrene, poly(methyl methacrylate), and poly(ethylene glycol) are developed using self‐seeding method from varied quality solvents. Edge‐on and flat‐on orientations are detected depending on the thickness and width of single crystals. Coily blocks are excluded from the P3HT crystalline structures, leading to brush‐like or hairy regions on surface of grown single crystals in the longitude of P3HT chains. The larger single crystals possessing flat‐on orientation are obtained from weaker solvents at higher seeding temperatures. The longer P3HT chains are folded, however, the shorter backbones are laminated on each other. The highest backbone lamination occurs for homo‐P3HT7150 (Mn of P3HT = 7150 g mol−1) single crystals grown at 20 °C from anisole, the weakest employed solvent. In contract, highly ordered and folded hairy single crystals are acquired from better solvents and high molecular weight P3HTs. In these conditions, the crystallographic features of the hairy block copolymer single crystals are similar to those of nonhairy homo‐P3HT ones. The coily brush‐covered P3HT48 800 single crystals have more foldings compared to the homo‐P3HT48 800 ones, whereas only two laminated backbones in shorter P3HT blocks are detected.

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