A method for preparing a light emitting device comprising: disposing an electron-injection layer comprising a metal oxide on a cathode, disposing a first layer adjacent the electron-injection layer, the first layer comprising a small molecule material with a bandgap of at least about 3 eV capable of blocking holes, forming an emissive layer comprising quantum dots capable of emitting blue light upon excitation at a surface of the first layer opposite the electron-injection layer; disposing a second layer comprising a material capable of transporting holes and blocking electrons with a bandgap of at least about 3 eV adjacent a surface of the emissive layer opposite the first layer, and disposing an anode over the second layer. A light-emitting device is also disclosed.