According to one or more embodiments, an organic light-emitting device comprises: a first electrode; a second electrode facing the first electrode; an emission layer between the first electrode and the second electrode; a hole transport region between the first electrode and the emission layer; and an electron transport region between the emission layer and the second electrode. The emission layer comprises a first compound represented by Formula 1, and at least one selected from the hole transport region and the electron transport region comprises a second compound represented by Formula 2A or 2B: