Two-photon excited circularly polarized luminescence of hetero[9]helicene with multiresonant thermally activated delayed fluorescence

Circularly polarized luminescence (CPL) imaging of biomolecules using designed chiral probes holds significant promise for biochemical and analytical applications. In this work, we report two chiral hetero[9]helicene multi-resonant thermally activated delayed fluorescent (MR-TADF) organic molecules DDCzBPh and DDCzBPy , consisting of two annulated MR-TADF units to a central naphthyl or quinoxanyl group, respectively, which exhibit simultaneously strong CPL, two-photon absorption, high photoluminescence quantum yields, and long-lived delayed fluorescence. We demonstrate two-photon-excited CPL of TADF emitters, with their circularly polarized brightness of 0.2 GM, demonstrating their potential for CPL biological imaging.