Optical properties of semiconductor nanocrystals with degenerate valence band

The energy spectrum and wave functions of holes in CdSe and CdS nanocrystals have been calculated. It is shown that in CdS nanocrystals the lowest quantum size level (QSL) of holes has p-type symmetry and optical transitions between this state and the lowest QSL of electrons are forbidden. The radiative lifetimes in CdSe nanocrystals are estimated to be of the order of 23 ns. The real structure of the valence bands have been shown to increase the electron-hole pair — polar phonons coupling with decreasing nanocrystal size.