A near-infrared light emitting device can include semiconductor nanocrystals that emit at wavelengths beyond 1 um. The semiconductor nanocrystals can include a core and an overcoating on a surface of the core. Light-emitting devices can be used, for example, in displays (e.g., flat-panel displays), screens (e.g., computer screens), and other items that require illumination. The materials used for the devices can have an energy gap corresponding to near-infrared, visible, or near-ultraviolet light.