Absorption cross sections and Auger recombination lifetimes in inverted core-shell nanocrystals: Implications for lasing performance

Abstract

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.