Diameter-Dependent Band Gap Modification of Single-Walled Carbon Nanotubes by Encapsulated Fullerenes

Abstract

Band gap photoluminescence (PL) of single-walled carbon nanotubes (SWCNTs) encapsulating C60 fullerenes (nanopeapods) is examined over a wide range of diameters (∼1.25−1.55 nm). The encapsulated fullerenes induce characteristic PL peak shifts that strongly depend on the tube diameter (dt) and the “2n + m” family type {type I [mod(2n + m, 3) = 1] and type II [mod(2n + m, 3) = 2]}. This behavior can be explained by the strain-induced band gap shifts due to the C60 insertion and the hybridization between the electronic states of SWCNTs and C60. The present results provide significant insights into band gap engineering of SWCNTs in future nanodevices.