Silane- and triazine-containing hole and exciton blocking material for high-efficiency phosphorescent organic light emitting diodes

Abstract

One of the important factors for high efficiency phosphorescent organic light-emitting devices is to confine triplet excitons within the emitting layer. We synthesized and characterized a new hole blocking material containing silane and triazine moieties, 2,4-diphenyl-6-(4-triphenylsilanyl-biphenyl-4-yl)-1,3,5-triazine (DTBT). Electrophosphorescent devices fabricated using the material as the hole-blocking layer and N,N-dicarbazolyl-4,4-biphenyl (CBP) doped with fac-tris(2-phenylpyridine)iridium [Ir(ppy)3] as the emitting layer showed a maximum external quantum efficiency (ext) of 17.5% with a maximum power efficiency (p) of 47.8 lm W–1, which are much higher than those of devices using bathcuproine (BCP) (ext = 14.5%, p = 40.0 lm W–1) and 4-biphenyloxolate aluminium(III) bis(2-methyl-8-quinolinato)-4-phenylphenolate (BAlq) (ext = 8.1%, p = 14.2 lm W–1) as hole-blocking layers.