Abstract
Consistently arranging molecules within single-walled carbon nanotube (SWCNT) templates shows promise for creating advanced 1D heterostructures, but diameter variations in raw SWCNTs pose a significant challenge. In this work, a precise synthesis of C(70) fullerene-filled SWCNTs (C(70)@SWCNTs) is achieved through vapor-phase filling followed by polymer sorting. As the SWCNT diameter increases, C(70) molecules first stack in a single chain, then form unusual configurations, including staggered double chains and double helices-configurations not observed in bulk C(70) crystals. SWCNT deformation, which is often overlooked in previous theoretical works, is found to significantly alter the C(70) stacking configuration. C(70)-SWCNT electronic interactions, particularly charge transfer, allow selective extraction of C(70)@SWCNTs with narrowly distributed diameters and good semiconducting purity. The sorted C(70)@SWCNTs have diameters of 1.3-1.4 nm, corresponding to C(70)-SWCNT distances of ca. 0.34 nm, where the strongest electronic interactions occur. An on/off current ratio of 10⁴ is achieved in their field-effect transistors. The synthesis and separation strategy sheds light on the preparation and application of 1D heterostructures.