Giant thermopower effects from molecular physisorption on carbon nanotubes

Results are presented of in situ studies of the thermoelectric power and four-probe resistance of single-walled carbon nanotube films during the adsorption of cyclic hydrocarbons C6H2n (n=3-6). The size of the change in these transport parameters is found to be related to the pi electron population of the molecule, suggesting the coupling between these pi electrons and those in the nanotube wall may be responsible for the observed effects. A transport model for the SWNT film behavior is presented, incorporating the effects of a new scattering channel associated with the adsorbed molecules.