A novel emitter compound having the formula Os(L1)(L2)(L3) and a novel method of making such compounds are disclosed. In the formula Os(L1)(L2)(L3), each of L1, L2, and L3 is independently a bidentate ligand. The method includes (a) reacting a precursor of ligand L1 with an osmium precursor to form a first intermediate product that has the ligand L1 coordinated to the osmium, wherein the osmium precursor has the formula OsHx(PR3)y, wherein x is an integer from 2 to 6 and y is an integer from 2 to 5, and R is selected from the group consisting of aryl, alkyl and cycloalkyl; (b) reacting the first intermediate product with a reducing agent to form a Os(II) second intermediate product; (c) reacting the second intermediate product with a coordinating solvent to form a third intermediate product; and (d) reacting a mixture of ligands L2 and L3 with said third intermediate product.