PHOSPHORESCENT INK

A phosphorescent ink comprises a first solvent, a stabiliser and a first phosphorescent metal complex wherein the first phosphorescent metal complex comprises at least one aryl-imidazole or heteroaryl-imidazole ligand that may be unsubstituted or substituted with one or more substituents and wherein the solvent is selected from: linear, branched or cyclic ethers comprising one or more O-CH2 units; solvents comprising a CH2-C(R6)H-CH2 unit wherein R6 is an organic residue and the two CH2 groups may be linked by a divalent group: bicyclic, partially or fully saturated solvents; solvents of formula R8-CR7═CR7-CH2-R8 wherein each R7 is independently H or C1-10 alkyl and R8 in each occurrence is independently an organic residue; and solvents comprising a benzyl group. The stabiliser may be an antioxidant. The ink may be used to form an organic light-emitting device.