As the potential applications of carbon nanotubes in the field of electroluminescence, elements yttrium and europium were introduced to modify the emission properties of double-walled carbon nanotubes (DWNTs) to obtain higher efficacy and other properties. The light emission spectrum of the Y-Eu-doped DWNT filament is suppressed in the near-infrared range, while enhanced in the mid-infrared range. The doped DWNT filament can reach higher efficacy than that of the pure DWNT filament at the same input power and can work stably as long as 5000 h at 12 V. These filaments could be useful for the light sources with special functions, such as infrared light sources operated at low input power.
