Patent ID: 8518557

Claim:
An organic light emitting device suitable for white electroluminescent emission comprising an emissive layer, wherein the device contains only one emissive layer, the emissive layer consisting essentially of a light emitting material, or consisting essentially of a light emitting material which resides as a guest in a host material, wherein the light emitting material consists essentially of a neutral complex comprising orthometalated ligands comprising imidazole moieties which are not condensed to a further aromatic ring and an ancillary ligand of the β-diketonate type wherein the neutral complex is represented by formula (I): wherein: M represents a transition metal of atomic number of at least 40; Y is a group selected from the group consisting of —CH═CH—, —CR═CH—, —CR═CR—, N—H, N—R 1 , O, S, and Se; R is the same or different at each occurrence and is —F, —Cl, —Br, —NO 2 , —CN; or a straight-chain or branched or cyclic alkyl or alkoxy group or dialkylamino group having from 1 to 20 carbon atoms, in each of which one or more nonadjacent —CH 2 — groups may be replaced by —O—, —S—, —NR 1 —, or —CONR 2 —, and in each of which one or more hydrogen atoms may be replaced by F; an aryl or heteroaryl group having from 4 to 14 carbon atoms which may be substituted by one or more non aromatic radicals; and a plurality of substituents R, either on the same ring or on the two different rings, may in turn together form a further mono- or polycyclic ring system, optionally aromatic; R 1 , R 2 , the same or different from each other and at each occurrence, are independently H or an aliphatic or aromatic hydrocarbon radical having from 1 to 20 carbon atoms; R A and R B , equal to or different from each other and at each occurrence are independently selected from the group consisting of —F, —Cl, —Br, —NO 2 , —CN; and a straight-chain or branched or cyclic alkyl or alkoxy group having from 1 to 20 carbon atoms, in each of which one or more nonadjacent —CH 2 — groups may be replaced by —O—, —S—, —NR 1 —, or —CONR 2 —, and in each of which one or more hydrogen atoms may be replaced by F; an aryl or heteroaryl group having from 4 to 14 carbon atoms which may be substituted by one or more nonaromatic radicals; R D and R E , equal to or different from each other and at each occurrence, are independently selected from the group consisting of C 1 -C 6 alkyl or aryl, fluoro- or perfluoro-alkyl or aryl groups; R c is independently selected from C1-C6 alkyl or aryl groups; a is an integer from 0 to 4; b is an integer from 0 to 2.