Chiral sulfoximine-based TADF emitter for circularly polarized luminescence and highly efficient OLEDs

• The first example of CP-TADF emitter based on heteroatom-based central chirality was presented. • The stereogenetic sulfur center rendered the emitter obvious chiroptical activity. • The emitter displayed close-to-unity Ф PL in film state owing to the presence of multiple intra-/intermolecular interactions. • Impressive EQE of 28.5% was achieved in corresponding OLED. This work describes the first example of circularly polarized thermally activated delayed fluorescent (CP-TADF) materials containing heteroatomic stereocenter. A pair of central chiral enantiomers, namely ( R )-FAC-SIC and ( S )-FAC-SIC, were assembled by sulfoximine-based acceptor and acridan-based donor in a highly twisted manner. The assymetric sulfur atom served as a chiral source, enabling the emitters with distinct circular dichroism (CD) and circularly polarized luminescence (CPL) signals. Benefited from the close-lying excited-state energy levels and multiple intra-/intermolecular interactions in film state, the enantiomers possessed highly efficient TADF emission with almost unit quantum yield ( Ф PL ). Consequently, the corresponding device showed excellent maximum external quantum efficiency (EQE max ) of 28.5%, current efficiency (CE max ) of 85.6 cd A -1 , and power efficiency (PE max ) of 84.0 lm W -1 . We believe the introduction of heteroatom-based central chirality would significantly broaden the design scope of high-performance CP-TADF emitters.