ORGANIC ELECTROLUMINESCENT ELEMENT

PROBLEM TO BE SOLVED: To enhance age-based stability by using a ternary alloy composed of the combination of specific metal having a different work function for the cathode of an organic EL element to prevent the oxidation of the cathode. SOLUTION: A compound 1 expressed by the following chemical structure is deposited by vacuum evaporation on a cleaned glass plate with an ITO electrode to obtain a hole injection layer having a film thickness, for instance, of 50nm. Thereon, Mg for a metal element A, Al for a metal element B and Zn for a metal element C are simultaneously evaporated from the respective evaporation sources, and a cathode comprising an alloy of Mg:Al:Zn=10:1:1 having a film thickness of 200nm is formed by common evaporation. The positive hole injection layer, a light emitting layer and the cathode are deposited by evaporation under the conditions that vacuum is 10 torr and the temperature of a substrate is a room temperature. By an organic EL element formed, for instance, yellow green luminescence having luminescent brightness of 220cd/m is obtained at a DC voltage of 5V, and luminous efficiency is 2.11m/W. Therefore, the oxidation of a cathode can be prevented to enhance stability with lapse of time.