NMP 2008

	Seongho Choi
	ADVISOR: Dan Frisbie Chemical Engineering and Materials Science University of Minnesota

Resistance of Molecules: The case of polymer chains

Seongho Choi, BongSoo Kim, C. Daniel Frisbie

An important property of a wire is its electrical resistance per unit length. We have measured the resistance and current-voltage characteristics of conjugated molecular wires ranging in length from 1 to 7 nm, connected between metal electrodes. We observe for the first time the theoretically predicted change in DC transport from tunneling to hopping as a function of systematically controlled wire length. We also demonstrate that site-specific disruption of conjugation in the wires greatly increases resistance in the hopping regime but has only a small effect in the tunneling regime. These nanoscale transport measurements elucidate the role of molecular length and bond architecture on molecular conductivity and open opportunities for greater understanding of electrical transport in conjugated polymer films.