Advances in organic materials for chiral luminescence-based OLEDs

Emitters incorporating circularly polarized luminescence (CPL)-based organic light-emitting diodes (CP-OLEDs) are highly desirable in the pursuit of new optoelectronic applications such as 3D displays and optical data storage. In particular, emitters possessing circularly polarized thermally activated delayed fluorescence (CP-TADF) are able to achieve high efficiency in OLEDs. By further endowing multi-resonance thermally activated delayed fluorescence (MR-TADF, a subclass of TADF) with circularly polarized properties, MR-CP-OLEDs can obtain narrow emission bandwidths and may help to realize the holy grail of ultra-small bandwidth. Accordingly, this review covers the recent progress and evolution of CP-TADF emitters, their upgraded features and corresponding device technologies, as well as the challenges encountered in practical CP-OLEDs.