Organic electroluminescence element

Abstract

An organic electroluminescence element comprising: an anode layer, a cathode layer, and an organic luminescence layer therebetween, the organic luminescence layer having a carbazole derivative with a glass-transition temperature of 110° C. or higher, and a phosphorescent dopant. This structure makes it possible to provide an organic electroluminescence element which can make use of the triplet exciton state of the carbazole derivative even at room temperature and which has a practical life and superior heat-resistance.

What is claimed is: 
     
         1 . An organic electroluminescence element comprising:
 an anode layer,   a cathode layer, and   an organic luminescence layer therebetween, the organic luminescence layer having a carbazole derivative with a glass-transition temperature of 110° C. or higher, and a phosphorescent dopant.   
     
     
         2 . The organic electroluminescence element according to  claim 1 , wherein the carbazole derivative is at least one of compounds represented by the following general formulae (1) to (4): 
       
         
           
           
               
               
           
         
         wherein Ar 1  is a substituted or non-substituted aryl group having 6 to 50 nucleus carbon atoms; Ar 2  to Ar 7  are each independently a substituted or non-substituted aryl or arylene group having 6 to 50 nucleus carbon atoms; Ar 2  and Ar 3 , Ar 4  and Ar 5 , or Ar 6  and Ar 7  may be connected to each other through a single bond or through O, S or [substituted] or non-substituted alkylene as a connecting group; and each of repetition numbers m and n is an integer of 0 to 36 
       
       
         
           
           
               
               
           
         
         wherein R 1  to R 6  are each independently a hydrogen or halogen atom, an alkyl, aralkyl, aryl, cycloalkyl, fluoroalkyl, amino, nitro, cyano, hydroxy, or alkoxy group; R 7  and R 8  are each independently a hydrogen atom, an alkyl, aralkyl, aryl, or cycloalkyl group; X 1  and X 2  are each independently a hydrogen atom, an alkyl, aralkyl, aryl, or cycloalkyl group; Y is a single bond, an alkyl, alkylene, cycloalkyl, aryl, or aralkyl chain; a repetition number p is an integer of 1 to 3. 
       
       
         
           
           
               
               
           
         
         wherein Ar 8  to Ar 11  are each independently an aryl group having 6 to 50 nucleus carbon atoms which may be substituted with an alkyl, alkoxy or aryl group; Ar 8  and Ar 9 , or Ar 10  and Ar 11  may be connected to each other through a single bond or through O, S or substituted or non-substituted alkylene as a connecting group; and R 9  is an alkyl or alkoxy group, or a substituted or non-substituted aryl group having 6 to 18 nucleus carbon atoms. 
       
       
         
           
           
               
               
           
         
         wherein Z is a trivalent nitrogen atom or an aromatic group; Ar 12  to Ar 14  are each independently a group represented by the following general formula (5) or an aryl group having 6 to 50 nucleus carbon atoms; and at least two of Ar 12  to Ar 14  are groups represented by the following general formula (5): 
       
       
         
           
           
               
               
           
         
         wherein R 10  to R 21  are each independently an aryl group having 6 to 50 nucleus carbon atoms which may be substituted with an alkyl, alkoxy group having 1 to 6 carbon atoms, or a phenyl group; and groups adjacent to each other may form a cyclic structure; and a repetition number q is an integer of 0 to 3. 
       
     
     
         3 . The organic electroluminescence element according to  claim 1 , wherein the carbazole derivative has at least two carbazole skeletons. 
     
     
         4 . The organic electroluminescence element according to  claim 1 , wherein relationship of E1>E2 is satisfied in which E1 represents triplet energy of the carbazole derivative and E2 represents triplet energy of the phosphorescent dopant. 
     
     
         5 . The organic electroluminescence element according to  claim 1 , wherein triplet energy E1 of the carbazole derivative is a value of 21,000 cm −1  or more. 
     
     
         6 . The organic electroluminescence element according to  claim 1 , wherein the carbazole derivative has cyclic structure whose triplet energy is a value of 21,000 cm −1  or more, and the cyclic structure contains an aromatic ring, a hetero ring, or combination thereof. 
     
     
         7 . The organic electroluminescence element according to  claim 1 , wherein the phosphorescent dopant is a metal complex comprising at least one metal selected from the group consisting of Ir, Ru, Pd, Pt, Os and Re. 
     
     
         8 . The organic electroluminescence element according to  claim 7 , wherein at least one ligand of the metal complex has at least one skeleton selected from the group consisting of phenylpyridine, bipyridyl and phenanthroline skeletons. 
     
     
         9 . The organic electroluminescence element according to  claim 1 , wherein a blend amount of the phosphorescent dopant is 0.1 to 30 parts by weight per 100 parts of the carbazole derivative. 
     
     
         10 . The organic electroluminescence element according to  claim 1 , wherein a hole barrier layer, an electron injection layer, or combination thereof is arranged between the anode layer and the cathode layer, and the hole barrier layer and the electron injection layer comprise an alkali metal.