An electroluminescent device includes a first electrode and a second electrode facing each other, and an emissive layer disposed between the first electrode and the second electrode and including the quantum dots. The quantum dots include a semiconductor nanocrystal core including indium (In) and phosphorous (P), a first semiconductor nanocrystal shell disposed on the semiconductor nanocrystal core, the first semiconductor nanocrystal shell including zinc and selenium, and a second semiconductor nanocrystal shell disposed on the first semiconductor nanocrystal shell, the second semiconductor nanocrystal shell including zinc and sulfur, wherein the quantum dots do not include cadmium. The electroluminescent device has an external quantum efficiency of greater than or equal to about 9% and a maximum brightness of greater than or equal to about 10,000 candelas per square meter (cd/m2).