The rate of electron transfer is determined by the overlap between the density of states (DOS) associated with the redox species and the electrode surface. As the DOS is high at the Fermi level in metal electrodes, oxidation and reduction process can readily take place as the electrode potential is biased with respect to the formal redox potential. On the other hand, the DOS is effectively zero in semiconductor materials for energies located within the band gap. Our work demonstrates that by controlling the band edge energies of CdTe nanocrystals (q-dots) assembled at blocked electrodes, the preferential transfer of electrons or holes to the redox species can be promoted.
This behaviour, commonly referred to as electrochemical rectification, is an essential step in the design of novel photovoltaic and optoelectronic devices.

This work was carried out in the group of Prof. David J. Fermín.

References:

• G. Kissling;
  Diploma thesis.