Determination of defect states in semiconductor nanocrystals by cyclic voltammetry

Colloidal, monodisperse CdSe nanocrystals were homogeneously dispersed in an ionic liquid and investigated by means of cyclic voltammetry. Almost all known defect states in semiconductor nanocrystal were quantitatively measured with this nonoptical method (including nonradiative defect states). Variation of the illumination and temperature resulted in excitation of defect-trapped electrons into the conducting band. Thus, we succeeded for the first time to con-elate defect states in nanocrystals with those in the corresponding bulk crystals.