Organic Light-Emitting Device An organic light-emitting device (100) comprising an anode (103); a cathode (109); a light-emitting layer (107) between the anode and the cathode; and a hole-transporting layer (105) between the anode and the cathode, wherein the light-emitting layer comprises a light-emitting compound of formula (I) and the hole-transporting layer comprises a hole-transporting material having a HOMO level that is no more than 5.1 e V from vacuum level: N N ML x R 2 (R) m (R) n y (I) wherein: R in each occurrence is independently a substituent; R 2 is H or a substituent; m is 0, 1 or 2; n is 0, 1, 2, 3 or 4; M is a transition metal; L is a ligand; y is at least 1; and x is 0 or a positive integer.