Highly efficient styrylamine-doped blue and white organic electroluminescent devices

摘要

We have developed highly efficient blue and white organic electroluminescent devices based on a blue fluorescent styrylamine dopant EBDP. The blue and white organic light emitting diodes (OLEDs) with the structures: Indium-tin oxide (ITO)/copper phthalo-cyanme(CuPc)/N,N'-bis-(1-naphenyl)-N,N'-biphenyl-1,1'-biphenyl-4,4'-diamine(NPB)/2-t-butyl-9,10-di-(2-naphthyl)anthracene(TBADN): EBDP/tris(8-hydroxyquinoline)aluminum(Alq_3)/LiF/Al and ITO/CuPc/NPB/TBADN:EBDP: 4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB)/Alq_3/LiF/Al were studied by using EBDP as blue dopant. For the blue device, the maximum luminance and maximum efficiency were 26961 cd/m~2 and 8.29 cd/A, respectively, the luminance at a current density 20 mA/cm~2 was 1597 cd/m~2. For the white device, the maximum luminance of 32,291 cd/m~2, maximum efficiency 8.31 cd/A and the luminance of 1413 cd/m~2 at a current density 20 mA/cm~2 were obtained. The slow decrease of efficiency with the increase of current density indicates weak exciton-exciton annihilation, which is resulted from the large steric hindrance due to the non-planar structure of the fluorescence dye EBDP.