A new, highly luminescent terbium complex (see Figure) is investigated here as a material for organic light-emitting diodes (OLEDs). It is demonstrated that device efficiencies of over 2.6 lm/W are possible-the highest yet reported for a lanthanide-based OLED. This indicates that lanthanide-based materials are a viable alternative to Alq- and PPV-based polymers for use in commercial OLED displays.