Electron Transfer Dynamics at p-GaAs/Liquid Interfaces

The rates of photoinduced electron transfer from sulfide-passivated p-GaAs to outer-sphere redox acceptors (ferricenium and cobalticinium) in acetonitrile have been measured using time-correlated single-photon-counting of photoluminescence decay. The characteristic time scales for electron transfer were found to be very fast, manifested by electron transfer velocities ranging from 2 × 10⁵ to 10⁶ cm/s at 1 mM concentrations. These rates are 4-5 orders of magnitude faster than predicted by other workers.