Patent ID: 8115382
Filing Date: 2012-02-14
Classification: H01L,Y10S

Abstract:
1. A light-emitting element comprising: a first electrode; a first layer formed over the first electrode, wherein the first layer comprises a first organic compound and a second organic compound; a light-emitting layer formed over the first layer; a second layer formed over the light-emitting layer, wherein the second layer comprises a third organic compound and a fourth organic compound; and a second electrode formed over the second layer, wherein a weight percent of the first organic compound is higher than a weight percent of the second organic-compound, wherein a weight percent of the third organic compound is higher than a weight percent of the fourth organic compound, wherein the first organic compound has a hole transporting property, wherein the second organic compound has an electron transporting property, wherein the third organic compound has an electron transporting property, wherein the fourth organic compound has an electron trapping property, and wherein a lowest unoccupied molecular orbital level of the fourth organic compound is lower than a lowest unoccupied molecular orbital level of the third organic compound by 0.3 eV or more.