An electroluminescent device comprising a first electrode; a hole transport layer disposed on the first electrode; an emission layer disposed on the hole transport layer and comprising a plurality of light emitting particles; an electron transport layer disposed on the emission layer and comprising a metal oxide particle-organic polymer composite comprising a plurality of metal oxide particles and an organic polymer; and a second electrode disposed on the electron transport layer, wherein the organic polymer is present in the metal oxide particle-organic polymer composition in an amount of about 7 weight percent to about 30 weight percent based on a total weight of the electron transport layer.