A composition including a first compound is disclosed, wherein the first compound is capable of functioning as a phosphorescent emitter in an organic light emitting device at room temperature; wherein the first compound has at least one aromatic ring and at least one substituent R; wherein each of the at least one R is an organic group having at least one X—F bond; wherein each X is independently selected from the group consisting of Si, and Ge; and wherein each of the at least one R is directly bonded to one of the aromatic rings.