US Patent 7947974 OLED device with hole-transport and electron-transport materials

An OLED device including an anode, a hole transporting layer (HTL), a light-emitting layer (LEL) comprising a host molecule and a light-emitting molecule, an electron transporting layer (ETL) and an cathode and wherein: (i) the HTL comprises a hole transporting material (HTM) having an oxidation potential that is at least 0.2 V less positive than the oxidation potential of the predominant material in the ETL and does not contain any bonds having an energy less than 105 kcal/mol; and (ii) the ETL comprises an electron transporting material (ETM) having a reduction potential (RPetm) relative to the reduction potential of the predominant material in the HTL (RPhtm) that meets the requirement of RPetm>(RPhtm−0.05). The OLED Device provides improvements in features including efficiency.