A light emitting device includes: a first electrode and a second electrode with a surface facing the first electrode; an emission layer disposed between the first electrode and the second electrode and including a quantum dot (e.g., a plurality of quantum dots); and an electron auxiliary layer disposed between the emission layer and the second electrode. The electron auxiliary layer includes a first layer including a first metal oxide, and a second layer disposed on the first layer and including a second metal oxide. A roughness of an interface between the second layer and the second electrode is less than about 10 nm as determined by an electron microscopy analysis. An absolute value of a difference between a conduction band edge energy level of the second layer and a work function of the second electrode may be less than or equal to about 0.5 eV, and a conduction band edge energy level of the first layer may be less than the conduction band edge energy level of the second layer.