Helically Chiral Donor–Acceptor Double Hetero[4]helicenes with Circularly Polarized Thermally Activated Delayed Fluorescence

Although helically chiral heterohelicenes are widely adopted in chiroptical studies, those with circularly polarized thermally activated delayed fluorescence (CP-TADF), which are highly valuable for circularly polarized organic light-emitting diodes (CP-OLEDs), are rarely realized. Moreover, the core skeletons of known CP-TADF heterohelicenes are limited to the p- and n-doped structures with multiresonance effect. In this study, a new type of helically chiral CP-TADF heterohelicenes featuring a fused donor-acceptor core skeleton is successfully designed and constructed. Enantiomers possessing high configurational stability are achieved and separated, and they efficiently emit CP light with dissymmetry factors reaching 3.1 x 10(-3) in doped films. Owing to the excellent photophysical properties, a high-performance CP-OLED with the maximum external quantum efficiency of up to 20.0% and an electroluminescence dissymmetry factor reaching 2.9 x 10(-3) is obtained. This new type of CP-TADF heterohelicenes provides a large space for the development of high-performance CP-TADF materials for various applications.