Azasiline-based Host Materials for Thermally Activated Delayed Fluorescent Organic Light-Emitting Diodes

Silicon-based organic functional materials always display unique functional properties. Two azasiline-modified host materials, namely 2SiPh and 2SiPy, have been successfully designed and synthesized. The triplet energy levels of 2SiPh and 2SiPy are as high as 3.2 eV. Green thermally activated delayed fluorescent organic light-emitting diodes (OLEDs) with 4CzIPN as the emitter have been fabricated based on 2SiPh and 2SiPy, leading to a maximum external quantum efficiency (EQE) of 16.6% and 8.2%, respectively. Most importantly, the sky-blue OLEDs with HDT-1 as the emitter based on 2SiPh and 2SiPy achieved high EQEs of 15.3 % and 17.5 %, respectively.