Patent ID: 7745019

Claim:
A light emitting device comprising a light emitting element comprising: a first electrode; a first layer comprising an organic compound and an inorganic compound over the first electrode; and a second layer comprising a first, second and third regions over the first layer, wherein the second region is formed between the first region and the third region, wherein each of the first, second and third regions comprises a material having a high light emitting property and a material having a high carrier transporting property, wherein a concentration of the material having a high carrier transporting property is higher than a concentration of the material having a high light emitting property in the first and third regions, wherein a concentration of the material having a high light emitting property is higher than a concentration of the material having a high carrier transporting property in the second region, and wherein the concentration of the material having a high light emitting property periodically changes in the second layer.