Predicting the electronic structure of weakly interacting hybrid systems: The example of nanosized peapod structures

Abstract

We provide a simple scheme for predicting the electronic structure of van der Waals bound systems, based on the mere knowledge of the electronic structure of the subunits. We demonstrate this with the example of nanopeapods, consisting of polythiophene encapsulated in single-wall carbon nanotubes. Using density functional theory we disentangle the contributions to the level alignment. The main contribution is shown to be given by the ionization potential of the polymer inside the host, which in turn is determined by the curvature of the tube. Only a small correction arises from charge redistributions within the domains of the constituents. Polarization effects turn out to be minor due to the cylindrical geometry of the peapods and their dielectric characteristics. Our findings open the possibility of designing optoelectronic properties of such complex materials.