Efficient blue/white phosphorescent organic light-emitting diodes based on a silicon-based host material via a direct carbon–nitrogen bond
A new host material BCz–Si for blue and white phosphorescent organic light-emitting devices was designed and synthesized. The introduction of the triphenylsilyl moiety into the BCz unit can efficiently tune the HOMO/LUMO energy levels and maintain high triplet energy. Its carrier mobility, thermal, photophysical, and electrochemical properties were also systematically investigated. The high triplet energy of BCz–Si ensures efficient energy transfer from the host to the triplet emitter FIrpic. The blue device using BCz–Si as a host material achieved a maximum quantum efficiency of 21.0%, corresponding to a current efficiency and power efficiency as high as 46.5 cd A−1 and 45.8 lm W−1, respectively; meanwhile, high efficiency white phosphorescent OLEDs hosted by BCz–Si were also fabricated with a maximum external quantum efficiency of 24.6%, 70.5 cd A−1 for two-color based and 21.5%, 50.1 cd A−1 for three color based devices.