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

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-(49-triphenylsilanylbiphenyl-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(2phenylpyridine) iridium [Ir( ppy) 3] as the emitting layer showed a maximum external quantum efficiency (eta(ext)) of 17.5% with a maximum power efficiency ( eta(p)) of 47.8 lm W 21, which are much higher than those of devices using bathcuproine ( BCP) ( eta(ext) = 14.5%, eta(p) = 40.0 lm W 21) and 4-biphenyloxolate aluminium(III) bis(2-methyl-8-quinolinato)-4-phenylphenolate (BAlq) (eta(ext) = 8.1%, eta(p) = 14.2 lm W-1) as hole-blocking layers.