Patent ID: 8241467

Claim:
A method of making a cathode structure for an OLED provided over organic layers, comprising: a) evaporating a first cathode layer over and in continuous contact with the organic layers, such layer including a metal or metal alloy whose work function is less than 4.0 eV, or a material including an electron-injecting dopant and a reactive metal; b) depositing by evaporation at least one buffer layer of an inorganic material over and in contact with the first cathode layer to from a buffer structure with the first cathode layer, such buffer layer including an elemental heavy metal or a metal oxide,wherein the elemental heavy metal includes Ag ,Au, Bi, Cd, Cu, Ni, Pd, Sb, Zn or alloys thereof; and c) sputtering a second cathode layer of an elemental metal or a mixture of elemental metals provided over the buffer structure; such that the at least one buffer layer prevents damage to the first cathode layer and organic layers during sputtering of the second cathode layer.