Phosphorescent material

1. A luminescent organometallic complex composition of matter, the composition comprising

at least one transition metal, M, that produces phosphorescent emission at room temperature;

at least one first monoanionic bidentate ligand coordinated through a nitrogen on a heteroaromatic ring and a carbon which is part of an aromatic group; and

at least one second ligand, coordinated through a carbon atom on an aromatic group and having Formula III

Ar[—(CH 2 ) m —Y] p   Formula III

wherein

Ar is an aromatic group,

Y is a group having a heteroatom capable of coordinating to metal M,

m is an integer from 1 through 20,

p is an integer from 1 through 5,

and further wherein one or more of the hydrogens in (CH 2 ) m can be replaced with D or F, wherein Y is selected from NR 2 2 , OR 2 , SR 2 , and PR 3 2 , wherein

R 2 is the same or different at each occurrence and is H or C n H 2n+1 ; and

R 3 is the same or different at each occurrence and is selected from H, R 2 , and Ar.

2. The composition of claim 1 , wherein M is iridium, the first ligand is phenylpyridine with substituents, the second ligand is α,α′-diphenylphosphino-m-xylene.

3. The composition of claim 1 , wherein Ar is phenyl, m is 1, Y is P(Ar) 2 , and p is 1 or 2.

4. A luminescent organometallic complex composition of matter, the composition comprising

iridium;

at least one first ligand which is a phenylpyridine with substituents;

at least one second hydride ligand; and

two diarylbenzylphosphine ligands.

5. A luminescent organometallic complex composition of matter selected from:

where Ph is phenyl and Bz is benzyl.