We study inverted core-shell nanocrystals NCs, in which a core of a wide-gap semiconductor ZnSe is overcoated with a shell of a narrower gap material CdSe. Depending on the core radius and the shell thickness, these NCs can exhibit either type-I or type-II behavior. We show that these heterostructures can be used to significantly increase the absorption cross sections and simultaneously decrease the efficiency of Auger recombination compared to monocomponent CdSe NCs emitting at the same wavelength. These properties enhance the lasing performance of inverted core-shell structures and allow, in particular, efficient amplified spontaneous emission in the range of blue colors. © 2006 American Institute of Physics.