The biphenyl molecule as a model transistor.
We study transport and charge control in a gated 4,4'-biphenyl diradical molecular transistor using self-consistent density-functional calculations. We track both electron-like and hole-like conduction and relate it to the field dependence of current-carrying pi-derived states. Owing to the coupling between the two benzene rings, the pi-states become segregated into extended, current-carrying states and localized states. Under application of the source/drain field, along the axis of the molecule, the localized pi-states become split, while the extended states become polarized and screen the field. The localized states act like isolated islands within the molecule--while they make a substantial contribution to the density of states, they make only a small contribution to transport.
Solomon
Paul M
PM
IBM Thomas J. Watson Research Center, Yorktown Heights, New York 10598, USA. solomonp@us.ibm.com
Lang
Norton D
ND
D001713:Biphenyl Compounds / Q000737:chemistry*; D003198:Computer Simulation; D017076:Computer-Aided Design; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008956:Models, Chemical; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure; D036103:Nanotechnology / Q000295:instrumentation* / Q000379:methods; D014173:Transistors, Electronic
D001713:Biphenyl Compounds; C010574:biphenyl