Strengthened counter electrode of electroluminescent devices

Abstract

The present invention provides an electroluminescent device comprising a substrate ( 1 ) and stacked thereon in the order of mention a first transparent electrode ( 2 ), an electroluminescent stack ( 3 ), and a second electrode ( 4 ). Furthermore, the electroluminescent device comprises at least one additional hard layer ( 5 ) that is located underneath the second electrode and/or on top of the second electrode and that has a hardness larger than the hardness of the second electrode. Methods for the production of such electroluminescent devices are likewise provided.

1 . An electroluminescent device comprising:
 a substrate;   a first transparent electrode disposed on the substrate;   an electroluminescent stack disposed on at least a portion of the first transparent electrode;   a second electrode disposed on at least a portion of the electroluminescent stack; and   at least one hard layer disposed in direct contact with at least a portion of the second electrode   wherein the hard layer has a hardness larger than the hardness of the second electrode.   
     
     
         2 . The electroluminescent device according to  claim 1 , wherein at least a portion of the at least one additional hard layer is disposed between the second electrode and the electroluminescent stack. 
     
     
         3 . The electroluminescent device according to  claim 1 , wherein at least a portion of the at least one additional hard layer is not in contact with the electroluminescent stack. 
     
     
         4 . The electroluminescent device according to  claim 1 , wherein the thickness of the at least one hard layer is ≧5 nm and ≦50 um. 
     
     
         5 . The electroluminescent device according to  claim 1 , wherein the at least one hard layer comprises at least one semiconducting metal oxide. 
     
     
         6 . The electroluminescent device according to  claim 1 , wherein the at least one hard layer, is a conductive layer. 
     
     
         7 . The electroluminescent device according to  claim 1 , wherein the at least one hard layer is a non-conductive layer. 
     
     
         8 . The electroluminescent device according to  claim 6 , further comprising a conductive layer disposed on the hard layer. 
     
     
         9 . The electroluminescent device according to  claim 1 , further comprising a cover,
 wherein the cover comprises a contact;   wherein the contact is electrically connected to the second electrode.)   
     
     
         10 . The electroluminescent device according to  claim 8 , wherein the contact comprises at least one of a conductive glue, a mechanical contacting means, a conductive spring, a conductive post or a conductive spacer. 
     
     
         11 . The electroluminescent device according to  claim 1 , further comprising an encapsulating conductive layer, wherein the encapsulating conductive layer encapsulates the hard layer. 
     
     
         12 . The electroluminescent device according to  claim 1 , further comprising:
 a contact directly connected to a top surface of the encapsulating conductive layer, wherein the area of direct connection between the contact and the encapsulating conductive layer is substantially smaller than the area of a top surface of the second electrode.   
     
     
         13 . The electroluminescent device according to  claim 1 , wherein the area of direct contact between the encapsulating conductive layer and the second electrode is smaller than the area of direct contact between the at least one hard layer and the second electrode. 
     
     
         14 . The electroluminescent device according to  claim 1 , wherein the at least one hard layer is comprised of a semiconducting metal oxide. 
     
     
         15 . The electroluminescent device according to  claim 14 , wherein the semiconducting metal oxide is selected from the group consisting of MoO 3 , WO 3 , V 2 O 2 . 
     
     
         16 . The electroluminescent device according to  claim 1 , wherein the contact provides an electrical connection between the cover and the at least one hard layer. 
     
     
         17 . The electroluminescent device according  claim 1  wherein the hard layer is selected from the group consisting of a hard metal and a metal alloy. 
     
     
         18 . The electroluminescent device according  claim 1  wherein the hard layer is comprises at least one material selected from the group consisting of oxides, nitrides and fluorides.