Blue and white organic light emitting diodes based on a new stilbene derivative dopant

In this paper the electroluminescene of highly efficient blue dopant EBDP was investigated. The blue and white organic light emitting diodes with the structure: indium-tin oxide (ITO)/ copper phthalocyanine (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/Alq(3)/LiF/Al were studied by using EBDP as blue dopant. For the blue device, the maximum luminance was 26961 cd/m(2), and its maximum efficiency was 8.29 cd/A. The luminance at a current density 20 mA/cm(2) was 1597 cd/m(2). For the white device, the maximum luminance 32291 cd/m(2) and maximum efficiency 8.31 cd/A, 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 results from the large steric hindrance due to a non-planar structure of the fluorescence dye EBDP.