Different mechanisms for hole and electron transfer along identical molecular bridges: the importance of the initial state delocalization.
We report measurements of hole and electron transfer along identical oligo-p-phenylene molecular bridges of increasing length. Although the injection barriers for hole and electron transfer are similar, we observed striking differences in the distance dependence and absolute magnitude of the rates of these two processes. Electron transfer is characterized by an almost distance-independent, fast charge-transfer rate. Hole transfer presents a much slower rate that decreases significantly with the length of the bridge. Time-dependent density functional calculations show that the observed differences can be explained by the delocalization of the respective initial excitation. The evaluation of the initial state is therefore essential when comparing charge-transfer rates between different donor-bridge-acceptor systems.
Department of Chemical Engineering, Delft University of Technology , Julianalaan 136, Delft 2629 BL, The Netherlands.
Natalie
N
Gorczak
Simge
S
Tarkuç
Nicolas
N
Renaud
Arjan J
AJ
Houtepen
Rienk
R
Eelkema
Laurens D A
LD
Siebbeles
Ferdinand C
FC
Grozema
D004583:Electrons; D007700:Kinetics; D010084:Oxidation-Reduction; D013057:Spectrum Analysis