Charge Transfer and Gap States in Semiconducting Nanopeapods: a Theoretical Study

The electronic structures of nanopeapods that consist of a semiconducting nanotube and various fullerenes, such as C60, C82, La@C60, and La@C82 are investigated using a first-principles method. For all the systems studied, molecular states originating from fullerenes are found within the energy gap of the semiconducting nanotube, often resulting in effective hole doping of nanotubes as the Fermi level shifts. In the case where C60 and La@C60 are encapsulated, a rigid band model considering the work function of each constituent explains the band structure of the full system. The charge redistribution in nanopeapods with C82 and La@C82, on the other hand, leads to a rigid shift of fullerene bands.