Novel Thermally Activated Delayed Fluorescence Materials–Thioxanthone Derivatives and Their Applications for Highly Efficient OLEDs

Thermally activated delayed fluorescence emitters with small energy gap between the triplet and singlet (ΔEST ), TXO-PhCz and TXO-TPA, have been successfully synthesized by combining a hole-transporting TPA/PhCz moiety and an electron-transporting TXO moiety. Both compounds display efficient solid-state luminescence with an efficient up-conversion of the triplet to singlet. OLEDs based on them exhibt high performance up to 21.5%, which is among the best reported for OLEDs.