An organic light-emitting device comprises an anode, a cathode, a light-emitting layer between the anode and the cathode and a hole transporting layer between the anode and the light-emitting layer. The hole transporting layer comprises a hole-transporting material having a triplet energy level, and a triplet-quenching unit having a triplet energy level that is lower than the triplet energy level of the hole-transporting material. The triplet quenching unit is selected from the group consisting of polyaromatic hydrocarbons such as 2,6-anthracenes, 9,10-anthracenes and derivatives thereof; anthanthrenes and derivatives thereof; distyryl aryls and derivatives thereof such as distyrylbenzenes, distyrylbiphenyls, stilbenes, fulvenes, dibenzofulvenes, perylenes, linear polyenes (from 2 to 6 alkenes) and cyclic polyenes, each of which may optionally be substituted with one or more substituents.