High-Performance Circular Polarization Multiple-Resonance TADF Molecules with Enhanced Long-Range Charge Transfer Based on Chiral Paracyclophane.

Circularly polarized multiple-resonance thermally activated delayed fluorescence (CP-MR-TADF) materials have received widespread attention in recent years, but it remains a formidable challenge to design high-performance CP-MR-TADF emitters concurrently exhibiting high quantum efficiency, narrowband emission, and high dissymmetry factor (g). Here, we perform an in-depth theoretical investigation on the CP-MR-TADF materials based on [2.2] paracyclophane (pCp) derivatives. The MR-based materials with enhanced long-range charge transfer (LRCT) characteristics upon excitation show increased g values owing to the coaxial dominated transition components of the transition electric dipole moment (TEDM) and the transition magnetic dipole moment (TMDM) but inevitably result in the loss of narrowband emission performance. Furthermore, the newly designed molecules by fusing the peripheral benzene units of MR cores within the planar chiral pCp bridge maintain narrowband emissions and exhibit increased g values on the order of 1 × 10-3. These findings with rich physical insights on the structure-performance relation of chiral paracyclophane-based molecules should provide important clues for designing high-performance chiral materials.