Controlled carbon-nanotube junctions self-assembled from graphene nanoribbons.

Although considerable progress has taken place in the area of carbon nanotube (CNT) junction synthesis, properties, and applications, major obstacles still remain in controlled synthesis, posing significant limitations for the development of new CNT-based applications. Existing approaches for synthesizing CNT junctions do not produce CNT junctions with good controllability or favorable selectivity and yield. Here, we report a new approach for synthesizing CNT junctions based on a self-assembling process from two tailored graphene nanoribbons (GNRs). CNT junctions with two, three, and four terminals, starting from GNRs either with perfect or irregular tailoring, are synthesized. The functionality of these selfassembled CNT junctions for nanoelectronics is then confirmed using charge-transport simulations. Based on state-of-the-art experimental capability, this approach with identified scalability down to the atomic scale and screening-free selectivity is practically realizable and desirable for individually controlling both the chirality and shape of CNT junctions, thereby dramatically improving their effectiveness and further expanding their application repertoire. Existing approaches for synthesizing CNT junctions primarily inherit from that of CNTs and intrinsically bear some shortcomings. As a result, the scientific community desires a new approach capable of precisely controlling the synthesis of CNT junctions. Geometrically, the synthesis of CNTs can be ‘‘imagined’’ as a rolling process of a narrow graphene ribbon. The appearance and manipulation of GNRs make the imaginary ‘‘rolling-up’’ process promising. The literature thus farhas demonstrated the ability to realize single ormultilayers of freestanding GNRs with well-defined nanoscale width (as