The fabrication of efficient and bright red light-emitting organic electrol
uminescent devices based on Eu-complex, having narrow spectral width, is ac
hieved by enhancing the electron injection process through the use of LiF/M
g cathode. Devices with external quantum efficiency exceeding 1% and light
output higher than 320 cd/m(2) are presented. While the external quantum ef
ficiency at 100 cd/m(2) is comparable, the luminous efficiency is 2.6 times
higher than that of the recent state-of-the-art devices based on the phosp
horescent dye PtOEP.