Optical transitions in charged CdSe quantum dots

Using a many-body approach based on single-particle pseudopotential wave functions, we calculate the dependence of the optical transitions in CdSe nanocrystals on the presence of ``spectator'' electrons or holes. We find that (i) as a result of the different localization of the electron and hole wave functions, the absorption lines shift by as much as 22meV/unitcharge when electrons or holes are loaded into the quantum dot. (ii) The lowest emission line is significantly red shifted with respect to the lowest allowed absorption line. (iii) Trapping of a ``spectator'' hole in a surface state is predicted to lead to dramatic changes in the absorption spectrum, including the appearance of new transitions.