Polarization of Colloidal CdSe Quantum Dots

The e ects of the polarization of colloidal CdSe QDs on the optical transitions are discussed based on systematic studies of a colloidal CdSe-based QDs system as a function of the net QDs' polarity/polarization and of the solvent's polarity. The polarization of the QD/ligand complexes makes them water-soluble after appropriate cleaning processes. The polarization of the bare CdSe QDs is reasonably thought to originate from dangling bonds at the surfaces of the dots. Passivation of the Se dangling bond by hydrogen generated from ultraviolet irradiation of the CdSe QDs in water is clearly observed to cause a spectral blueshift and a photoluminescence enhancement.