1,4-Bis(triphenylsilyl)benzene, known as UGH-2, is one of the well-known TADF host materials for blue-emitting dopants (such as FIrPic) in highly-efficient blue PhOLEDs. This is due to its wide energy gap (4.4 eV) and high triplet energy (ET = 3.5 eV).
With a very deep HOMO energy level (HOMO = 7.2 eV), UGH-2 also works as an electron-transport (ETL) and hole-blocking layer (HBL) material.