DIELECTRIC-DISPERSION MEASUREMENTS OF CDSE NANOCRYSTAL COLLOIDS - OBSERVATION OF A PERMANENT DIPOLE-MOMENT

We measure the dielectric dispersion of CdSe nanocrystal colloids and show the existence of large dipole moments of 25 and 47 debye for 34 a nd 46 Angstrom diameter nanocrystals, respectively. The magnitude is c onsistent with the expected spontaneous polarization of the bulk wurtz ite CdSe lattice and implies a potential drop of approximate to 0.25 V across the nanocrystal. This effect, which is intrinsic to the wurtzi te structure but has been largely overlooked, should be incorporated i n the description of the quantum confined electronic states.