Selective Sorting of Semiconducting C₇₀@Single-Walled Carbon Nanotube Heterostructures with Narrow Diameter...

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 C₇₀ fullerene-filled SWCNTs (C₇₀@SWCNTs) is achieved through vapor-phase filling followed by polymer sorting. As the SWCNT diameter increases, C₇₀ molecules first stack in a single chain, then form unusual configurations, including staggered double chains and double helices-configurations not observed in bulk C₇₀ crystals. SWCNT deformation, which is often overlooked in previous theoretical works, is found to significantly alter the C₇₀ stacking configuration. C₇₀-SWCNT electronic interactions, particularly charge transfer, allow selective extraction of C₇₀@SWCNTs with narrowly distributed diameters and good semiconducting purity. The sorted C₇₀@SWCNTs have diameters of 1.3-1.4 nm, corresponding to C₇₀-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.