An organic light-emitting device includes a first electrode, a second electrode facing the first electrode, and an emission layer disposed between the first electrode and the second electrode; an electron transport region disposed between the emission layer and the second electrode; and a hole transport region disposed between the first electrode and the emission layer, wherein the electron transport region comprises at least one of an electron transport material represented by Formula 1 below; and the hole transport region comprises at least one of a hole transport material represented by Formula 2 or 3 below: