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

Abstract

In this paper the electroluminescene of highly efficient blue dopant EBDP was in vestigated. 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′-bipheny1-4-4′-diamine (NPB)/2-t-butyl-9,10-di-(2-naphthyl)anth racene(TBADN):EBDP/tris(8-hydroxyquinoline) aluminum(Alq3)/LiF/Al and ITO/CuPc/NPB/TBADN:EBDP: 4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7-tetramethylj ulolidyl-9-enyl)-4H-pyran/Alq3/LiF/Al were studied by using EBDP as b lue dopant. For the blue device, the maximum luminance was 26961cd/m2 , and its maximum efficiency was 8.29cd/A. The luminance at a current density 20 mA/cm2 was 1597cd/m2. For the white device, the maximum lu minance 32291cd/m2 and maximum efficiency 8.31cd/A,the luminance of 1 413cd/m2 at a current density 20mA/cm2 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.