Device including quantum dots and method for making same

A light emitting device including an emissive layer comprising electroluminescent quantum dots disposed between an anode and a cathode,

• a first layer comprising an electron injection and transport material comprising nanoparticles of a first inorganic semiconductor material, the first layer being disposed between the layer comprising quantum dots and the cathode, wherein the first layer and the cathode form an ohmic contact during operation of the device,
• wherein the first inorganic semiconductor material includes at least one of zinc oxide, a titanium oxide, a niobium oxide, an indium tin oxide, copper oxide, nickel oxide, vanadium oxide, chromium oxide, indium oxide, tin oxide, gallium oxide, manganese oxide, iron oxide, cobalt oxide, aluminum oxide, thallium oxide, silicon oxide, germanium oxide, lead oxide, zirconium oxide, molybdenum oxide, hafnium oxide, tantalum oxide, tungsten oxide, cadmium oxide, iridium oxide, rhodium oxide, ruthenium oxide, and osmium oxide,
• wherein the electroluminescent quantum dots comprise a core comprising a first semiconductor material and an outer shell surrounding the core, the outer shell comprising a second semiconductor material, wherein the absolute value of the difference between Econduction band edge of the first semiconductor material included in the quantum dot core and Econduction band edge of the second semiconductor material included in the outer shell of the quantum dot is less than the absolute value of the difference between E valence band edge of the first semiconductor material and Evalence band edge of the second semiconductor material, wherein the differences are calculated based on the Econduction band edge and Evalence band edge values for bulk forms of the first and second semiconductor materials measured relative to vacuum level with an energy level=0 eV,
• wherein the quantum dots emit light when voltage is applied across the anode and cathode, and wherein the device has a peak EQE of at least 18% when measured over a voltage range from 1 V to 10 V.