Charge‐Transport Behavior in Aligned Carbon Nanotubes: A Quantum‐Chemical Investigation

Abstract

AbstractCorrelated quantum‐chemical calculations are applied to analyze the amplitude of the electronic‐transfer integrals that describe charge transport in interacting carbon nanotubes (CNTs) by investigating the influences of: i) the relative positions of the CNTs, ii) the size of the CNTs, and iii) their chemical impurities. Our results indicate that the mobility of the charge carrier is extremely sensitive to the molecular packing and the presence of chemical impurities. The largest splitting for the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels is in the case of perfectly cofacial conformations where hexagons face hexagons in the dimer structure. We found that the diameter of the CNT determines the type of transporting carrier: for CNTs with large diameters hole transport dominates, while for thin CNTs electron transport dominates. In general, the carrier mobility for the perfect CNTs (n ≥ 3) is less pronounced than that of C60 due to their relatively small strain. B‐ and N‐doped CNTs exhibit considerably larger mobilities owing to the possibility of metallic behavior. These results provide a plausible explanation for the high mobility found experimentally in a field‐effect transistor (FET) made from a large‐area, well‐aligned CNT array. In addition, these hole‐rich and electron‐rich dopants imply potential applications in nanoelectronics.