Nanostructured alumina as a cathode of organic light-emitting devices

We propose a new cathode for organic light-emitting devices based on anodic porous alumina films. In these films, the bottom part of alumina layer, placed between the aluminium and pore space, is removed. The usage of porous alumina cathode results in more inhomogeneous electric field and, as a consequence, in more intensive auto-electron emission and higher cathode efficiency. Luminescent organic molecules are adsorbed at the walls of cylindrical pores. Extended surface of this matrix allows significant increase of luminophors concentration without noticeable luminescence quenching. These organic electroluminescent devices can be easily manufactured and they are more efficient and stable as compared with the usual layered structures. We have developed an organic electroluminescence structure consisting of aluminium, porous alumina doped with amorphous naphthalimide derivative, and ITO layers. A bright green electroluminescence has been observed from the fabricated structure. (C) 2002 Published by Elsevier Science B.V.