Patent ID: 7563518

Claim:
An OLED device comprising a cathode, an electron- transporting layer (ETL), a light-emitting layer (LEL) containing a fluorescent light-emitting material, a hole-transporting layer (HTL), and an anode, in that order, wherein the ETL comprises a mixture of compounds, including a first compound and at least one second compound, and wherein there is present a hole blocking layer (HBL) adjacent to the LEL on the cathode side, wherein the first compound is present in an amount of 50% to 90% by volume and is represented by Formula (2): wherein: R 1 and R 4 represent the same substituent and neither are hydrogen; R 2 R 3 represent hydrogen; Ar 1 and Ar 4 represent the same aromatic group; and Ar 2 and Ar 3 represent the same aromatic group.