Phosphorescent organic light emitting devices

Abstract

An organic light emitting device structure having an organic light emitting device (OLED) over a substrate, where the OLED has, for example, an anode, a hole transporting layer (HTL), a first electron transporting layer (ETL) that is doped with a phosphorescent material, a second electron transporting layer (ETL), and a cathode. The OLEDs of the present invention are directed, in particular, to devices that include an emissive layer comprised of an electron transporting host material having a triplet excited state energy level that is higher than the emissive triplet excited state energy level of the phosphorescent dopant material.

1. An organic light emitting device comprising an anode, a cathode and an emissive layer, wherein the emissive layer is located between the anode and the cathode and the emissive layer comprises an electron transporting host material doped with a phosphorescent dopant material,
 wherein the phosphorescent dopant material is an organometallic complex having the formula selected from L 3   M and L   2   MX, wherein    
   M is a third row transition metal;    
   L is a monoanionic bidentate ligand that is coordinated to M with an sp   2    hybridized carbon and a heteroatom of the ligand L; and    
   X is a monoanionic bidentate ligand;   
 and wherein the phosphorescent dopant material has a HOMO energy less than the ionization potential of the electron transporting host material and a LUMO energy level lower than a LUMO energy level of the electron transporting host material. 
 
     
     
       2. The organic light emitting device of  claim 1 , wherein the phosphorescent dopant material has a LUMO energy level lower than a LUMO energy level of the electron transporting host material. 
     
     
       3. The organic light emitting device of  claim 1 , wherein the electron transporting host material comprises an aryl-substituted oxadiazole. 
     
     
       4. The organic light emitting device of  claim 3 , wherein the aryl-substituted oxadiazole comprises a compound represented by 
                 
 
     
     
       5. The organic light emitting device of  claim 1 , wherein the electron transporting host material comprises an aryl-substituted triazole. 
     
     
       6. The organic light emitting device of  claim 5 , wherein the aryl-substituted triazole comprises 3-phenyl-4-(1′-naphthyl)-5-phenyl-1,2,4-triazole. 
     
     
       7. The organic light emitting device of  claim 1 , wherein the electron transporting host material comprises an aryl-substituted phenanthroline. 
     
     
       8. The organic light emitting device of  claim 7 , wherein the aryl-substituted phenanthroline comprises 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline. 
     
     
       9. The organic light emitting device of  claim 1 , wherein the electron transporting host material comprises a benzoxazole or benzothiazole compound having the chemical structure: 
                 
 
       where X and Y are independently O, S;
 M represents a metal;  
 n is a integer from 1 to 3; and  
 R 1  to R 8  are, independently, a hydrogen atom, an aryl group or an alkyl group.  
 
     
     
       10. The organic light emitting device of  claim 1 , wherein the electron transporting material comprises a zinc benzoxazole compound having the chemical structure: 
                 
 
     
     
       11. The organic light emitting device of  claim 1 , wherein the phosphorescent dopant material comprises fac-tris (2-phenylpyridine)-iridium. 
     
     
       12. An organic light emitting device comprising:
 a substrate;  
 an anode layer over said substrate;  
 a hole transporting layer over said anode layer;  
 a first electron transporting layer over said hole transporting layer, wherein said first electron transporting layer comprises an electron transporting host material doped with a phosphorescent dopant material,  
 wherein the phosphorescent dopant material is an organometallic complex having the formula selected from L 3   M and L   2   MX, wherein    
   M is a third row transition metal;    
   L is a monoanionic bidentate ligand that is coordinated to M with an sp   2    hybridized carbon and a heteroatom of the ligand L; and    
   X is a monoanionic bidentate ligand;    
   and  wherein the phosphorescent dopant material has a HOMO energy less than the ionization potential of the electron transporting host material and a LUMO energy level lower than a LUMO energy level of the electron transporting host material;  
 a second electron transporting layer over said first electron transporting layer; and  
 a cathode layer over said second electron transporting layer.  
 
     
     
       13. The organic light emitting device of  claim 12 , wherein the phosphorescent dopant material has a LUMO energy level lower than a LUMO energy level of the electron transporting host material. 
     
     
       14. The organic light emitting device of  claim 12 , wherein the electron transporting host material comprises an aryl-substituted oxadiazole. 
     
     
       15. The organic light emitting device of  claim 14 , wherein the aryl-substituted oxadiazole comprises a compound represented by 
                 
 
     
     
       16. The organic light emitting device of  claim 12 , wherein the electron transporting host material comprises an aryl-substituted triazole. 
     
     
       17. The organic light emitting device of  claim 16 , wherein the aryl-substituted triazole comprises 3-phenyl-4-(1′-naphthyl)-5-phenyl-1,2,4-triazole. 
     
     
       18. The organic light emitting device of  claim 12 , wherein the electron transporting host material comprises an aryl-substituted phenanthroline. 
     
     
       19. The organic light emitting device of  claim 18 , wherein the aryl-substituted phenanthroline comprises 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline. 
     
     
       20. The organic light emitting device of  claim 12 , wherein the electron transporting host material comprises a benzoxazole or benzothiazole compound having the chemical structure: 
                 
 
       where X and Y are independently O, S;
 M represents a metal;  
 n is a integer from 1 to 3; and  
 R 1  to R 8  are, independently, a hydrogen atom, an aryl group or an alkyl group.  
 
     
     
       21. The organic light emitting device of  claim 12 , wherein the electron transporting material comprises a zinc benzoxazole compound having the chemical structure: 
                 
 
     
     
       22. The organic light emitting device of  claim 12 , wherein the phosphorescent dopant material comprises fac-tris (2-phenylpyridine)-iridium. 
     
     
       23. The organic light emitting device of  claim 1 , wherein the organometallic complex has the formula L 3   M.   
     
     
       24. The organic light emitting device of  claim 1 , wherein the organometallic complex has the formula L 2   MX.   
     
     
       25. The organic light emitting device of any of claims  1  and  23 -   24 , wherein M is Ir.   
     
     
       26. The organic light emitting device of  claim 12 , wherein the organometallic complex has the formula L 3   M.   
     
     
       27. The organic light emitting device of  claim 12 , wherein the organometallic complex has the formula L 2   MX.   
     
     
       28. The organic light emitting device of any of claims  12  and  26 -   27 , wherein M is Ir.