Electroluminescent devices including organic eil layer

1. An OLED device comprising a cathode, an anode, and having therebetween a light emitting layer (LEL) comprising a phosphorescent emitting compound disposed in a host comprising a mixture of at least one electron transporting co-host represented by

wherein:

m is an integer from 0 to 5;

each x is an integer from 0 to 4;

y is an integer from 0 to 3;

R 2 and R 3 are independently selected from hydrogen; alkyl of from 1 to 24 carbon atoms, aryl or hetero-atom substituted aryl of from 5 to 20 carbon atoms, halo, or atoms necessary to complete a fused aromatic ring;

and at least one hole transporting co-host represented by

wherein there is present an electron transporting layer contiguous to the LEL on the cathode side and

wherein there is present an electron-injection layer (EIL) containing a heteroaromatic compound contiguous to the cathode;

wherein the electron transporting layer comprises an aromatic hydrocarbon material selected from:

an anthracene represented by:

wherein

Ar 9 and Ar 10 independently represent an aryl group;

v 1 , v 2 , v 3 , v 4 , v 5 , v 6 , v 7 , and v 8 independently represent hydrogen or a substituent; and

a fluoranthene represented by:

wherein

each R 1 is independently selected from alkyl, aryl, and heteroaryl groups;

R 2 through R 7 are independently selected from H, alkyl, phenyl, cyano and alkoxy groups; and

n is an integer selected from 0 to 4;

wherein the electron-injection layer comprises a heteroaromatic compound selected from:

wherein

each R 5 is independently selected from hydrogen, alkyl, aryl groups and at least one of R 5 is aryl or substituted aryl; and

wherein

M is Li;

R 8 and R 9 are independently selected substituent groups, provided adjacent substituents may combine to form ring groups;

h and i are independently integers from 0 to 3; and

j is an integer from 1 to 6.