Organic electroluminescent device with stabilizing cathode capping layer
AssigneeEastman Kodak Company
InventorsJon E. Littman, Michael Scozzafava
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Abstract
An organic electroluminescent device is disclosed which is protected from dark spot formation. The device is comprised of, in sequence, a support, an anode, an organic electroluminescent medium, and a cathode containing a plurality of metals other than alkali metals. The cathode is comprised of a capping layer containing at least one alkaline earth or rare earth metal and, interposed between the capping layer and the organic electroluminescent medium, an electron injecting layer containing at least one metal having a work function of less than 4.0, but exhibiting a higher work function than the alkaline earth or rare earth metals in the capping layer.
Claims11
An organic electroluminescent device comprised of, in sequence, a support, an anode, an organic electroluminescent medium, and a cathode containing a plurality of metals other than alkali metals,
- characterized in that said cathode is comprised of
- a capping layer containing at least one alkaline earth metal having a work function of less than 3.5 eV or rare earth metal having a work function of less than 3.5 eV and
- interposed between said capping layer and said organic electroluminescent medium, an electron injecting layer containing at least one metal having a work function of less than 4.0, but exhibiting a higher work function than said alkaline earth or rare earth metals in said capping layer.
Dependencies are inferred from the claim text.