Phosphine Oxide Based Electron Transporting and Hole Blocking Materials for Blue Electrophosphorescent Organic Light Emitting Devices

We report the design, synthesis, thermal, and photophysical properties of two phosphine oxide based electron transport/hole blocking materials, 2,6-bis(4-(diphenylphosphoryl)phenyl)pyridine (BM-A11) and 2,4-bis(4-(diphenyl-phosphoryl)phenyl)pyridine (BM-A10), for blue electrophosphorescent organic light emitting devices (OLEDs). The use of these materials in blue OLEDs with iridium(III) bis[(4,6-difluorophenyl)-pyridinato- N, C 2 ′]picolinate (Firpic) as the phosphor was demonstrated. Using the dual host device architecture with BM-A10 as the electron transport material (ETM) yields a maximum external quantum efficiency (EQE) of 8.9% with a power efficiency of 21.5 lm/W (4.0 V and 35 cd/m 2 ). When BM-A11 is used as the ETM, the maximum EQE and power efficiency improves to 14.9% and 48.4 lm/W, respectively (3.0 V and 40 cd/m 2 ).