| abstract |
An organic light emitting device having an emissive layer comprising an organometallic compound, wherein the organometallic compound is comprised of: na metal having an atomic number of at least 72; nat least one mono-anionic, bidentate, carbon coordination ligand bound to the metal; and nat least one ligand bound to the metal that is not mono-anionic, not bidentate and/or not a carbon coordination ligand, nwherein the at least one mono-anionic, bidentate, carbon-coordination ligand is substituted with at least one of an electron donating substituent and an electron withdrawing substituent; and nwherein the mono-anionic, bidentate, carbon-coordination ligand is selected from the group consisting of:n n nwherein R, R 1 , R 2 , R 3 and R 4 are, independently, hydrogen, halogen, alkyl or aryl. |