Light-Emitting Element and Light-Emitting Device

Abstract

It is an object of the present invention to provide a light-emitting element having a layer containing a light-emitting material and a transparent conductive film between a pair of electrodes, in which electric erosion of the transparent conductive film and metal can be prevented, and also to provide a light-emitting device using the light-emitting element. According to one feature of the invention, a light-emitting element includes a first layer 102 containing a light-emitting material, a second layer 103 containing a material having a donor level, a third layer 104 including a transparent conductive film, and a fourth layer 105 containing a hole-transporting medium between a first electrode 101 and a second electrode 106 , in which the first layer 102 , the second layer 103 , the third layer 104 , the fourth layer 105 , and the second electrode 106 are provided sequentially, in which the second electrode 106 has a layer containing metal.

What is claimed is: 
     
         1 . (canceled) 
     
     
         2 . A light-emitting device comprising:
 an electrode;   a first layer over the electrode, the first layer comprising a light-emitting material;   a second layer over and in contact with the first layer, the second layer comprising an organic compound doped with an electron-supplying material;   a transparent conductive layer over and in contact with the second layer; and   a third layer over the transparent conductive layer, the third layer comprising a carrier transporting medium,   wherein each of the second layer and the transparent conductive layer has a single layer structure.   
     
     
         3 . The light-emitting device according to  claim 2 , wherein the organic compound is an electron-transporting material. 
     
     
         4 . The light-emitting device according to  claim 2 , wherein the electron-supplying material is selected from an alkali metal, an alkali-earth metal, and a rare-earth metal. 
     
     
         5 . The light-emitting device according to  claim 2 , wherein the carrier transporting medium is a hole-transporting medium. 
     
     
         6 . The light-emitting device according to  claim 2 , wherein the transparent conductive layer comprises a material selected from the group consisting of tin oxide, indium oxide, zinc oxide, zinc oxide containing gallium, and molybdenum oxide. 
     
     
         7 . An electronic device comprising the light-emitting device according to  claim 2 . 
     
     
         8 . A light-emitting device comprising:
 an electrode;   a first layer over the electrode, the first layer comprising a light-emitting material;   a second layer over and in contact with the first layer, the second layer comprising a first organic compound doped with an electron-supplying material;   a transparent conductive layer over and in contact with the second layer; and   a third layer over the transparent conductive layer, the third layer comprising a carrier transporting material containing a second organic compound,   wherein each of the second layer and the transparent conductive layer has a single layer structure.   
     
     
         9 . The light-emitting device according to  claim 8 , wherein the first organic compound is an electron-transporting material. 
     
     
         10 . The light-emitting device according to  claim 8 , wherein the electron-supplying material is selected from an alkali metal, an alkali-earth metal, and a rare-earth metal. 
     
     
         11 . The light-emitting device according to  claim 8 , wherein the carrier transporting material is a hole-transporting material. 
     
     
         12 . The light-emitting device according to  claim 8 , wherein the second organic compound is doped with a metal oxide selected from molybdenum oxide, vanadium oxide, and rhenium oxide. 
     
     
         13 . The light-emitting device according to  claim 8 , wherein the transparent conductive layer comprises a material selected from the group consisting of tin oxide, indium oxide, zinc oxide, zinc oxide containing gallium, and molybdenum oxide. 
     
     
         14 . An electronic device comprising the light-emitting device according to  claim 8 . 
     
     
         15 . A light-emitting device comprising:
 an electrode;   a first layer over the electrode, the first layer comprising a light-emitting material;   a second layer over and in contact with the first layer, the second layer comprising a first organic compound doped with an electron-supplying material;   a transparent conductive layer over and in contact with the second layer;   a third layer over the transparent conductive layer, the third layer comprising a carrier transporting material containing a second organic compound; and   a conductive layer over the third layer,   wherein each of the second layer and the transparent conductive layer has a single layer structure.   
     
     
         16 . The light-emitting device according to  claim 15 , wherein the first organic compound is an electron-transporting material. 
     
     
         17 . The light-emitting device according to  claim 15 , wherein the electron-supplying material is selected from an alkali metal, an alkali-earth metal, and a rare-earth metal. 
     
     
         18 . The light-emitting device according to  claim 15 , wherein the carrier transporting material is a hole-transporting material. 
     
     
         19 . The light-emitting device according to  claim 15 , wherein the second organic compound is doped with a metal oxide selected from molybdenum oxide, vanadium oxide, and rhenium oxide. 
     
     
         20 . The light-emitting device according to  claim 15 , wherein the transparent conductive layer comprises a material selected from the group consisting of tin oxide, indium oxide, zinc oxide, zinc oxide containing gallium, and molybdenum oxide. 
     
     
         21 . The light-emitting device according to  claim 15 ,
 wherein the electrode is an anode, and   wherein the conductive layer is a cathode.   
     
     
         22 . An electronic devices comprising the light-emitting device according to  claim 15 .