Oligothiophene-functionalized CdSe nanocrystals: preparation and electrochemical properties

The preparation of new molecular hybrids consisting of CdSe semiconductor nanocrystals, surface-functionalized with conductive and electrochemically active oligothiophene ligands, is described. Specially synthesized aniline-terminated oligoalkylthiophenes containing one, two, or four thiophene units were used for the grafting on CdSe nanocrystals, previously surface-functionalized with 4-formyldithiobenzoate. The electrochemical activity of both the inorganic and the organic parts of the hybrid was investigated by cyclic voltammetry. The oxidative doping of the organic part of the hybrid is irreversible, contrary to the case of the “free” non-grafted ligand which shows reversible doping. Furthermore, the electrochemical doping of the surface ligands, occurring at lower potentials than the oxidation of the nanocrystals, perturbs the latter process via charging of the ligands followed by slow relaxation processes.