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

Band gap photoluminescence (PL) of single-walled carbon nanotubes (SWCNTs) encapsulating C 60 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 ( d t ) and the “2 n + m ” family type {type I [mod(2 n + m, 3) = 1] and type II [mod(2 n + m, 3) = 2]}. This behavior can be explained by the strain-induced band gap shifts due to the C 60 insertion and the hybridization between the electronic states of SWCNTs and C 60 . The present results provide significant insights into band gap engineering of SWCNTs in future nanodevices.