Dibenzooxasiline-Derived n-Type Host for High Efficiency and Long-Lifetime Blue Phosphorescent Organic Light-Emitting Diodes

Dibenzooxasiline-derived compounds, 2,4-bis(10,10-diphenyl-10H-dibenzo[b,e][1,4]oxasilin-2-yl)-6-phenyl-1,3,5-triazine (mOSiTrz) and 9-(4,6-bis(10,10-diphenyl-10H-dibenzo[b,e][1,4]oxasilin-2-yl)-1,3,5-triazin-2-yl)-9H-carbazole (mOSiCzTrz), are developed as high-triplet-energy n-type hosts for blue phosphorescent organic light-emitting diodes (PhOLEDs). They are used as n-type hosts in a mixed host to assist positive-polaron dispersion in the p–n mixed host to achieve high efficiency and long device lifetime. The dibenzooxasiline-based n-type hosts are mixed with a p-type 9-(3-(triphenylsilyl)phenyl)-9H-3,9′-bicarbazole host and performed better than n-type hosts built on a conventional tetraphenylsilane moiety. The external quantum efficiency of the blue PhOLEDs with the mOSiTrz and mOSiCzTrz hosts is over 20%, and their device lifetimes are extended 1.5- and 4-fold, respectively, relative to the well-known 2-phenyl-4,6-bis(3-(triphenylsilyl)phenyl)-1,3,5-triazine device due to the enhanced positive-polaron transport and dispersion abilities of the mOSiTrz and mOSiCzTrz hosts assisted by the dibenzooxasiline group.