Luminescent Chiral Exciplexes with Sky-Blue and Green Circularly Polarized-Thermally Activated Delayed Fluorescence

Luminescent exciplexes based on a chiral electron donor and achiral acceptors are reported as a new approach to design circularly polarized (CP) and thermally activated delayed fluorescence (TADF) emitters. This strategy results in rather high CP luminescence (CPL) values with g(lum) up to 7x10(-3), one order of magnitude higher in comparison to the CPL signal recorded for the chiral donor alone (g(lum) similar to 7x10(-4)). This increase occurs concomitantly with a CPL sign inversion, as a result of the strong charge-transfer emission character, as experimentally and theoretically rationalized by using a covalent chiral donor-acceptor model. Interestingly, blue, green-yellow and red chiral luminescent exciplexes can be obtained by modifying with the electron accepting character of the achiral unit while keeping the same chiral donor unit. These results bring new (inter)molecular guidelines to obtain simply and efficiently multi-color CP-TADF emitters.

Automated summary

A new approach using luminescent exciplexes based on a chiral electron donor and achiral acceptors has been reported for designing circularly polarized and thermally activated delayed fluorescence emitters. High CP luminescence values were achieved with a CPL signal inversion, showing promise for multi-color CP-TADF emitters.