PURPOSE: To provide an organic thin film EL(electroluminescence) element the luminescent threshold value voltage of which is lowered, and the brightness reduction of which is little.
CONSTITUTION: An anode 2, a hole transportation layer 3 made of triphenylamine dimer, a luminescent layer 4 made of luminescent material aluminum qhinolinoleic complex, cathodes 6a, 6b of two layers structure are successively laminated on a glass substrate 1 so as to form an organic EL element. The cathode 6a is made of europium (Eu) and the cathode 6b is made of aluminum (Al). Since the adhesion strength of the europium to the luminescent layer 4 is strong, the luminescent life of the organic EL element is improved, but since the work function is rather low, it is easy to oxidize. Therefore, the aluminum which has the high work function and hardly oxidize is laminated on the cathode 6a so that the cathode 6b functions as the oxidization prevention protective coat of the cathode 6a.
AZUMA YOJI
YOKOMIZO HIROHIKO
SUZUKI OSAMU
NISSHIN SPINNING
Next Patent: ORGANIC THIN FILM LUMINESCENT ELEMENT