US Patent 7955719 Tandem OLED device with intermediate connector

A tandem OLED device including an anode; a cathode; at least two electroluminescent units disposed between the anode and the cathode, wherein each of the electroluminescent units includes at least one hole-transporting layer and one organic light-emitting layer; and an intermediate connector disposed between adjacent electroluminescent units, wherein the intermediate connector includes an n-doped organic layer and an electron-accepting layer, the electron-accepting layer being disposed closer to the cathode than the n-doped organic layer, and wherein the n-doped organic layer includes an alkali metal and an organic alkali metal complex.