Theoretical study of a molecular resonant tunneling diode

Density functional theory calculations are performed to explain the electri cal behavior of a pi-conjugated oligo(phenylene ethynylene) resembling a re sonant tunneling diode. Results of this theoretical study are compatible wi th the assumptions that electron transport occurs through the lowest unoccu pied molecular orbital, that the conduction barrier is determined by the mo lecule chemical potential, and that the molecule becomes charged as the ext ernal potential increases. We are able to explain the nonlinear character o f the current-voltage characteristic of the molecule and its temperature de pendence. The intrinsic controlled-amplification feature of these molecules is indicated.