title: Kinetic pathway for interfacial electron transfer from a semiconductor to a molecule.
abstract: Molecular approaches to solar-energy conversion require a kinetic optimization of light-induced electron-transfer reactions. At molecular-semiconductor interfaces, this optimization has previously been accomplished through control of the distance between the semiconductor donor and the molecular acceptor and/or the free energy that accompanies electron transfer. Here we show that a kinetic pathway for electron transfer from a semiconductor to a molecular acceptor also exists and provides an alternative method for the control of interfacial kinetics. The pathway was identified by the rational design of molecules in which the distance and the driving force were held near parity and only the geometric torsion about a xylyl- or phenylthiophene bridge was varied. Electronic coupling through the phenyl bridge was a factor of ten greater than that through the xylyl bridge. Comparative studies revealed a significant bridge dependence for electron transfer that could not be rationalized by a change in distance or driving force. Instead, the data indicate an interfacial electron-transfer pathway that utilizes the aromatic bridge orbitals.
authors.affiliation: Department of Chemistry, The University of North Carolina at Chapel Hill, Murray Hall 2202B, Chapel Hill, North Carolina 27599-3290, USA.
authors.forename: Ke
authors.initials: K
authors.lastname: Hu
authors.affiliation: Departments of Chemistry and Chemical &Biological Engineering, The University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T1Z1, Canada.
authors.forename: Amber D
authors.initials: AD
authors.lastname: Blair
authors.affiliation: Department of Chemistry, The University of North Carolina at Chapel Hill, Murray Hall 2202B, Chapel Hill, North Carolina 27599-3290, USA.
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Piechota
authors.affiliation: Departments of Chemistry and Chemical &Biological Engineering, The University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T1Z1, Canada.
authors.forename: Phil A
authors.initials: PA
authors.lastname: Schauer
authors.affiliation: Department of Chemistry, The University of North Carolina at Chapel Hill, Murray Hall 2202B, Chapel Hill, North Carolina 27599-3290, USA.
authors.forename: Renato N
authors.initials: RN
authors.lastname: Sampaio
authors.affiliation: Departments of Chemistry and Chemical &Biological Engineering, The University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T1Z1, Canada.
authors.forename: Fraser G L
authors.initials: FG
authors.lastname: Parlane
authors.affiliation: Department of Chemistry, The University of North Carolina at Chapel Hill, Murray Hall 2202B, Chapel Hill, North Carolina 27599-3290, USA.
authors.forename: Gerald J
authors.initials: GJ
authors.lastname: Meyer
authors.affiliation: Departments of Chemistry and Chemical &Biological Engineering, The University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T1Z1, Canada.
authors.forename: Curtis P
authors.initials: CP
authors.lastname: Berlinguette