A population of nanocrystals comprising a core comprising a first semiconductor material comprising one or more elements of Group IIIA of the Periodic Table of Elements and one or more elements of Group VA of the Periodic Table of Elements, and a shell disposed over at least a portion of a surface of the core, the shell comprising one or more additional semiconductor materials, wherein the population is capable of emitting light having a photoluminescence quantum efficiency of at least about 30% upon excitation, and wherein the one or more additional semiconductor materials include ZnS.