Two-color size-tunable (1100-1600 nm) quantum dot nanocrystal electroluminescent devices

Light-emitting structures containing PbS nanocrystals of two different sizes were fabricated and investigated. They demonstrate light emission in two distinct infrared frequency bands, or alternatively across a wide frequency band, each in the spectral region 1.1-1.6 /spl mu/m. For two-color structures the relative intensity of peaks can be varied in a wide interval depending on the conditions of excitation. The intensity of electroluminescence reached values corresponding to internal efficiency up to 3.1%.