Organic electroluminescence device

Abstract

An organic electroluminescence device includes an anode, an emitting layer, an electron-transporting region, and a cathode, the anode, the emitting layer, the electron-transporting region, and the cathode being stacked in this order, the emitting layer including a host material, and a dopant material that emits fluorescence having a main peak wavelength of 550 nm or less, the electron-transporting region including a barrier layer that is adjacent to the emitting layer, and the barrier layer including a barrier material that includes an electron-transporting structural part, and a triplet barrier structural part that includes a fused polycyclic aromatic hydrocarbon compound, and satisfies the relationship “ETb>ETh” (where, ETh is the triplet energy of the host material, and ETb is the triplet energy of the barrier material).

The invention claimed is: 
     
       1. An organic electroluminescence device comprising:
 an anode, an emitting layer, an electron-transporting region, and a cathode, sequentially; wherein 
 the emitting layer comprises a host material and a dopant material that emits fluorescence having a main peak wavelength of 550 nm or less, 
 the electron-transporting region comprises a barrier layer that is directly adjacent to the emitting layer, 
 the barrier layer comprises a barrier material that comprises an electron-transporting structural portion and a triplet barrier structural portion that comprises a fused polycyclic aromatic hydrocarbon moiety selected from rings shown by the following formulas (6), (7) and (10): 
 
       
         
           
           
               
               
           
         
         wherein Ar 2 , Ar 3 , Ar 4 , Ar 8  and Ar 9  independently represent a hydrocarbon structure having 4 to 16 ring carbon atoms, which forms a ring fused to the adjacent ring, 
         E T   h  is the triplet energy level of the host material, E T   b  is the triplet energy level of the barrier material, and 
         E T   b  and E T   h  satisfy the following formula (1),
   E T   b >E T   h    (1)
 
 
         wherein the electron-transporting structural portion comprises one or more partial structures shown by the following formula, 
       
       
         
           
           
               
               
           
         
       
       and X 1  and X 2  independently represent a carbon atom or a nitrogen atom. 
     
     
       2. The organic electroluminescence device of  claim 1 , wherein E T   d  is the triplet energy level of the dopant material, and E T   d  and E T   h  satisfy the following formula (2),
   E T   d >E T   h    (2).
 
 
     
     
       3. The organic electroluminescence device of  claim 1 , wherein an affinity of the host material is Af h , an affinity of the barrier material is Af b , and Af h  and Af b  satisfy the following formula (3),
   Af h −Af h >0 eV   (3).
 
 
     
     
       4. The organic electroluminescence device of  claim 1 , wherein an ionization potential of the host material is Ip h , an ionization potential of the dopant material is Ip d , and Ip d  and Ip h  satisfy the following formula (4),
   Ip d −Ip h<0.2  eV   (4).
 
 
     
     
       5. The organic electroluminescence device of  claim 1 , wherein the barrier material has an electron mobility of 10 −6  cm 2 /Vs or more. 
     
     
       6. The organic electroluminescence device of  claim 1 , wherein the barrier layer comprises a donor that reduces the barrier material. 
     
     
       7. The organic electroluminescence device of  claim 1 , wherein luminous intensity due to singlet excitons that are formed by collision between triplet excitons within the emitting layer accounts for 30% or more of total luminous intensity. 
     
     
       8. The organic electroluminescence device of  claim 1 , wherein the electron-transporting structural portion comprises one or more rings selected from rings shown by the following formulas, 
       
         
           
           
               
               
           
         
         X 11  to X 15  and X 21  to X 26  independently represent a carbon atom or a nitrogen atom, at least one of X 11  to X 15  represent a nitrogen atom, and at least one of X 21  to X 26  represent a nitrogen atom. 
       
     
     
       9. The organic electroluminescence device of  claim 1 , wherein the electron-transporting structural portion comprises one or more rings selected from rings shown by the following formulas, 
       
         
           
           
               
               
           
         
       
       
        
       
     
     
       10. The organic electroluminescence device of  claim 1 , wherein the electron-transporting structural portion comprises one or more rings selected from rings shown by the following formulas, 
       
         
           
           
               
               
           
         
       
       
        
       
     
     
       11. The organic electroluminescence device of  claim 1 , wherein the triplet barrier structural portion is selected from rings shown by the following formulas, 
       
         
           
           
               
               
           
         
         and Ar 1  to Ar 9  independently represent a hydrocarbon structure having 4 to 16 ring carbon atoms, which forms a ring fused to the adjacent ring. 
       
     
     
       12. The organic electroluminescence device of  claim 1 , comprising at least two emitting layers between the anode and the cathode, and further comprising a carrier-generating layer between the two emitting layers. 
     
     
       13. An organic electroluminescence device comprising:
 an anode, a plurality of emitting layers, an electron-transporting region, and a cathode, sequentially; wherein   the organic electroluminescence device further comprises a carrier barrier layer between at least two emitting layers among the plurality of emitting layers,   an emitting layer among the plurality of emitting layers that is adjacent to the electron-transporting region comprises a host material and a dopant material that emits fluorescence having a main peak wavelength of 550 nm or less,   the electron-transporting region comprises a barrier layer that is adjacent to the emitting layer,   the barrier layer comprises a barrier material that comprises an electron-transporting structural portion and a triplet barrier structural portion that comprises a fused polycyclic aromatic hydrocarbon moiety, E T   h  is the triplet energy level of the host material, E T   b  is the triplet energy level of the barrier material, and E T   b  and E T   h  satisfy the following formula (1),
   E T   b >E T   h    (1).
 
   
     
     
       14. The organic electroluminescence device of  claim 13 , wherein E T   d  is the triplet energy level of the dopant material, and E T   d  and E T   h  satisfy the following expression (2),
   E T   d >E T   h    (2).
   
     
     
       15. An organic electroluminescence device comprising:
 an anode, an emitting layer, an electron-transporting region, and a cathode, sequentially; wherein   the emitting layer comprises a host material and a dopant material that emits fluorescence having a main peak wavelength of 550 nm or less,   the electron-transporting region comprises a barrier layer that is adjacent to the emitting layer,   the barrier layer comprises a barrier material that comprises an electron-transporting structural portion and a triplet barrier structural portion that comprises a fused polycyclic aromatic hydrocarbon moiety,   E T   h  is the triplet energy level of the host material, E T   b  is the triplet energy level of the barrier material, and   E T   b  and E T   h  satisfy the following formula (1),
   E T   b >E T   h    (1),
 
   wherein an affinity of the host material is Af h , an affinity of the barrier material is Af b , and Af h  and Af b  satisfy the following formula (3),
   Af h −Af b >0 eV   (3).
 
   
     
     
       16. An organic electroluminescence device comprising:
 an anode, an emitting layer, an electron-transporting region, and a cathode, sequentially; wherein   the emitting layer comprises a host material and a dopant material that emits fluorescence having a main peak wavelength of 550 nm or less,   the electron-transporting region comprises a barrier layer that is adjacent to the emitting layer,   the barrier layer comprises a barrier material that comprises an electron-transporting structural portion and a triplet barrier structural portion that comprises a fused polycyclic aromatic hydrocarbon moiety,   E T   h  is the triplet energy level of the host material, E T   b  is the triplet energy level of the barrier material, and   E T   b  and E T   h  satisfy the following formula (1),
   E T   b >E T   h    (1),
 
   wherein an ionization potential of the host material is Ip h , an ionization potential of the dopant material is Ip d , and Ip d  and Ip h  satisfy the following formula (4),
   Ip d −Ip h <0.2 eV   (4).
 
   
     
     
       17. The organic electroluminescence device of claim 1, wherein the triplet barrier structural portion is selected from rings shown by the following formula (6), 
       
         
           
           
               
               
           
         
         wherein Ar 2  represents a hydrocarbon structure having 4 to 16 ring carbon atoms, which forms a ring fused to the adjacent ring.  
       
     
     
       18. The organic electroluminescence device of claim 17, wherein the ring shown by formula (6) has a skeleton selected from the group consisting of the following formulas: 
       
         
           
           
               
               
           
         
        
       
     
     
       19. The organic electroluminescence device of claim 1, wherein the triplet barrier structural portion is selected from rings shown by the following formula (7), 
       
         
           
           
               
               
           
         
         wherein Ar 3  and Ar 4  independently represent a hydrocarbon structure having 4 to 16 ring carbon atoms, which forms a ring fused to the adjacent ring.  
       
     
     
       20. The organic electroluminescence device of claim 19, wherein the ring shown by formula (7) has a skeleton selected from the group consisting of the following formulas: 
       
         
           
           
               
               
           
         
        
       
     
     
       21. The organic electroluminescence device of claim 1, wherein the triplet barrier structural portion is selected from rings shown by the following formula (10), 
       
         
           
           
               
               
           
         
         wherein Ar 8  and Ar 9  independently represent a hydrocarbon structure having 4 to 16 ring carbon atoms, which forms a ring fused to the adjacent ring.  
       
     
     
       22. The organic electroluminescence device of claim 21, wherein the ring shown by formula (10) has a skeleton selected from the group consisting of the following formulas: 
       
         
           
           
               
               
           
         
        
       
     
     
       23. The organic electroluminescence device of claim 22, wherein the ring shown by the formula (10) has the skeleton represented by the following formula: 
       
         
           
           
               
               
           
         
        
       
     
     
       24. The organic electroluminescence device of claim 1, wherein the host material is selected from the group consisting of an anthracene derivative and a pyrene derivative.  
     
     
       25. The organic electroluminescence device of claim 24, wherein the anthracene derivative is represented by the following formula: 
       
         
           
           
               
               
           
         
         Ar 11  and Ar 12  independently represent a substituted or unsubstituted aryl group having 6 to 50 ring carbon atom, or a substituted or unsubstituted heterocyclic group having 5 to 50 atoms that form a ring, and 
         R 101  to R 108  independently represent a group selected from a hydrogen atom, a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms, a substituted or unsubstituted heterocyclic group having 5 to 50 ring atoms, a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 50 ring carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 50 carbon atoms, a substituted or unsubstituted aralkyl group having 7 to 50 carbon atoms, a substituted or unsubstituted aryloxy group having 6 to 50 ring carbon atoms, a substituted or unsubstituted arylthio group having 6 to 50 ring carbon atoms, a substituted or unsubstituted alkoxycarbonyl group having 2 to 50 carbon atoms, a substituted or unsubstituted silyl group, a carboxyl group, a halogen atom, a cyano group, a nitro group, and a hydroxyl group; and 
       
       the pyrene derivative is represented by the following formula: 
       
         
           
           
               
               
           
         
         R a  represents a hydrogen atom or a substituent, where plural R a s may be the same or different, 
         Ar a  represents a substituted or unsubstituted aromatic hydrocarbon group having 6 to 50 ring carbon atoms, or a substituted or unsubstituted heterocyclic group having 5 to 50 ring atoms, where plural Ar a s may be the same or different, 
         L 1  represents a single bond, a substituted or unsubstituted divalent aromatic hydrocarbon group having 6 to 30 ring carbon atoms, or a substituted or unsubstituted divalent aromatic hydrocarbon group having 5 to 30 ring atoms, 
         a is an integer from 1 to 10, 
         p is an integer from 1 to 6, and 
         q is an integer from 0 to 10.  
       
     
     
       26. The organic electroluminescence device of claim 1, wherein the dopant material is selected from the group consisting of a diaminochrysene derivative, a diaminopyrene derivative, a styrylamine derivative, an amino-substituted fused fluorene derivative, a diaminoanthracene derivative, a boron-containing compound that is substituted with an electron-withdrawing group, a fluorene derivative that does not include an amino group, a fused fluorene derivative that does not include an amino group, a fluoranthene derivative that does not include an amino group, a benzofluoranthene derivative that does not include an amino group, and a pyrene derivative that does not include an amino group.  
     
     
       27. The organic electroluminescence device of claim 24, wherein the host material is the anthracene derivative, and the dopant material is selected from the group consisting of a diaminopyrene derivative, a diaminochrysene derivative, a styrylamine derivative, a boron-containing compound that is substituted with an electron-withdrawing group and a benzofluoranthene derivative that does not include an amino group.  
     
     
       28. The organic electroluminescence device according to claim 1, wherein the electron-transporting structural portion include a monocyclic structure or a fused polycyclic structure that includes one or more rings shown by the following formula: 
       
         
           
           
               
               
           
         
         wherein X 21  to X 26  independently represent a carbon atom or a nitrogen atom, provided that at least one of X 21  to X 26  represent a nitrogen atom.  
       
     
     
       29. The organic electroluminescence device according to claim 1, wherein the electron-transporting structural portion includes one or more rings selected from the rings shown by the following formulae: 
       
         
           
           
               
               
           
         
        
       
     
     
       30. The organic electroluminescence device according to claim 1, wherein the electron-transporting structural portion includes one or more rings shown by the following formula: 
       
         
           
           
               
               
           
         
        
       
     
     
       31. The organic electroluminescence device according to claim 1, wherein the electron-transporting structural portion includes a ring shown by the following formula: 
       
         
           
           
               
               
           
         
        
       
     
     
       32. The organic electroluminescence device according to claim 1, wherein the triplet barrier structural portion is a ring shown by the following formula: 
       
         
           
           
               
               
           
         
         the electron-transporting structural portion includes one or more rings shown by the following formula: 
       
       
         
           
           
               
               
           
         
        
       
     
     
       33. An organic electroluminescence device comprising:
 an anode, an emitting layer, an electron-transporting region, and a cathode, sequentially; wherein   the emitting layer comprises a host material and a dopant material that emits fluorescence having a main peak wavelength of 550 nm or less,   the electron-transporting region comprises a barrier layer that is adjacent to the emitting layer,   the barrier layer comprises a barrier material that comprises an electron-transporting structural portion and a triplet barrier structural portion that comprises a fused polycyclic aromatic hydrocarbon moiety selected from rings shown by the following formula (10),   
       
         
           
           
               
               
           
         
          wherein Ar 8  and Ar 9  independently represent a hydrocarbon structure having 4 to 16 ring carbon atoms, which forms a ring fused to the adjacent ring, 
         E T   h  is the triplet energy level of the host material, E T   b  is the triplet energy level of the barrier material, and E T   b  and E T   h  satisfy the following formula (1),
   E T   b >E T   h    (1)
 
 
         wherein the electron-transporting structural portion comprises one or more partial structures shown by the following formula, 
       
       
         
           
           
               
               
           
         
         and X 1  and X 2  independently represent a carbon atom or a nitrogen atom, 
         provided that layers between the emitting layer and the cathode do not comprise a compound having a ring which has partial structures shown by the following formulae (6) and (7) 
       
       
         
           
           
               
               
           
         
         wherein Ar 2 , Ar 3 , and Ar 4  independently represent a hydrocarbon structure having 4 to 16 ring carbon atoms, which forms a ring fused to the adjacent ring.  
       
     
     
       34. The organic electroluminescence device of claim 33, wherein E T   d  is the triplet energy level of the dopant material, and E T   d  and E T   h  satisfy the following formula (2),
   E T   d >E T   h    (2). 
   
     
     
       35. The organic electroluminescence device of claim 33, wherein an affinity of the host material is Af h , an affinity of the barrier material is Af b,  and Af h  and Af b  satisfy the following formula (3),
   Af h −Af b >0 eV   (3). 
   
     
     
       36. The organic electroluminescence device of claim 33, wherein an ionization potential of the host material is Ip h , an ionization potential of the dopant material is Ip d , and Ip d  and Ip h  satisfy the following formula (4),
   Ip d −Ip h <0.2 eV   (4). 
   
     
     
       37. The organic electroluminescence device of claim 33, wherein the barrier material has an electron mobility of 10 −6  cm 2 /Vs or more.  
     
     
       38. The organic electroluminescence device of claim 33, wherein the barrier layer comprises a donor that reduces the barrier material.  
     
     
       39. The organic electroluminescence device of claim 33, wherein luminous intensity due to singlet excitons that are formed by collision between triplet excitons within the emitting layer accounts for 30% or more of total luminous intensity.  
     
     
       40. The organic electroluminescence device of claim 33, wherein the electron-transporting structural portion comprises one or more rings selected from rings shown by the following formulas, 
       
         
           
           
               
               
           
         
         X 11  to X 15  and X 21  to X 26  independently represent a carbon atom or a nitrogen atom, at least one of X 11  to X 15  represent a nitrogen atom, and at least one of X 21  to X 26  represent a nitrogen atom.  
       
     
     
       41. The organic electroluminescence device of claim 33, comprising at least two emitting layers between the anode and the cathode, and further comprising a carrier-generating layer between the two emitting layers.  
     
     
       42. The organic electroluminescence device of claim 33, wherein the dopant material is selected from the group consisting of a diaminochrysene derivative, a diaminopyrene derivative, a styrylamine derivative, an amino-substituted fused fluorene derivative, a diaminoanthracene derivative, a boron-containing compound that is substituted with an electron-withdrawing group, a fluorene derivative that does not include an amino group, a fused fluorene derivative that does not include an amino group, a fluoranthene derivative that does not include an amino group, a benzofluoranthene derivative that does not include an amino group, and a pyrene derivative that does not include an amino group.  
     
     
       43. The organic electroluminescence device of claim 33, wherein the host material is the anthracene derivative, and the dopant material is selected from the group consisting of a diaminopyrene derivative, a diaminochrysene derivative, a styrylamine derivative, a boron-containing compound that is substituted with an electron-withdrawing group and a benzofluoranthene derivative that does not include an amino group.  
     
     
       44. The organic electroluminescence device according to claim 33, wherein the electron-transporting structural portion include a monocyclic structure or a fused polycyclic structure that includes one or more rings shown by the following formula: 
       
         
           
           
               
               
           
         
         wherein X 21  to X 26  independently represent a carbon atom or a nitrogen atom, provided that at least one of X 21  to X 26  represent a nitrogen atom.  
       
     
     
       45. The organic electroluminescence device according to claim 33, wherein the electron-transporting structural portion includes one or more rings selected from the rings shown by the following formulae: 
       
         
           
           
               
               
           
         
        
       
     
     
       46. The organic electroluminescence device according to claim 33, wherein the electron-transporting structural portion includes one or more rings shown by the following formula: 
       
         
           
           
               
               
           
         
        
       
     
     
       47. The organic electroluminescence device according to claim 33, wherein the electron-transporting structural portion includes a ring shown by the following formula: 
       
         
           
           
               
               
           
         
        
       
     
     
       48. The organic electroluminescence device according to claim 33, wherein the triplet barrier structural portion is a ring shown by the following formula: 
       
         
           
           
               
               
           
         
         the electron-transporting structural portion includes one or more rings shown by the following formula: