Azasiline-based thermally activated delayed fluorescence emitters for blue organic light emitting diodes

Recently, the azasiline unit was introduced as a donor in thermally activated delayed fluorescence (TADF) emitters to realize efficient blue fluorescence from organic light emitting diodes (OLEDs). Utilizing the azasiline unit DTPPDDA in the formation of donor-connector-acceptor (D-C-A) materials resulted in deep blue emission with a Commission Internationale de l'Eclairage (CIE) coordinate of (0.151, 0.087), close to the blue standard of the National Television System Committee (NTSC) of (0.140, 0.080) with 4.7% External Quantum Efficiency (EQE). In the donor-acceptor-donor (D-A-D) type materials of BDAPM and SPDDA, carbonyl and sulfone units were used as the acceptors, respectively. The sulfonyl unit contributed to a large twist of the molecular structure while the carbonyl unit led to a small twist of the molecular structure. As a result, the blue fluorescent OLEDs containing BDAPM and SPDDA demonstrated 11.4% and 2.3% EQEs with CIE Y-values of 0.310 and 0.107, respectively.