A compound comprising a ligand LA of Formula I: as well as, devices and formulations containing the compound of Formula 1 are disclosed. In the compounds, having a ligand La of Formula I: wherein R1 represents mono, or di-substitution, or no substitution; wherein R2 represents di, tri, or tetra-substitution; wherein R is selected from hydrogen, deuterium, alkyl, cycloalkyl, and combinations thereof; wherein R1 and R2 are each independently selected from hydrogen, deuterium, alkyl, cycloalkyl, aryl, and combinations thereof; wherein at least one pair of adjacent R2 substitutions are joined to form a fused ring; wherein the ligand LA is coordinated to a metal M; and wherein the ligand LA is optionally linked with other ligands to comprise a tridentate, tetradentate, pentadentate or hexadentate ligand.