Theory of electron current rectification, switching, and a role of defects in molecular devices

Abstract

Devices for nano- and molecular-sized electronics may allow for an efficient current rectification and switching. A few molecular scale devices are reviewed here on the basis of first-principles and model approaches. Current rectification by molecular quantum dots can produce the rectification ratio ≲100. Current switching due to conformational changes in the molecules is slow, on the order of a few kHz. Fast switching (∼1 THz) may be achieved, at least in principle, in a molecular quantum dot with attractive carrier-carrier interactions due to strong coupling with vibrational excitations. The observed switching in many cases is extrinsic, caused by changes in molecule-electrode geometry or metallic filament formation through the film.