Planar Chiral Thermally Activated Delayed Fluorescence Materials Based on Di[2.2]paracyclophane for Circularly Polarized Electroluminescence

Abstract In this study, featuring di[2.2]paracyclophane (DpCp) amine derivatives as electron donors and 4‐(4,6‐diphenyl‐1,3,5‐triazin‐2‐yl)phenyl (Trz) as the electron acceptor, four thermally activated delayed fluorescence (TADF) molecules are disclosed. The C 2 symmetric molecules, DpCpN‐Trz and DpCpCz‐Trz, bearing a chair‐like planar chiral di[2.2]paracyclophane moiety, are obtained as optically pure enantiomers ( R/S )‐ C ‐DpCpN‐Trz and ( R/S )‐ C ‐DpCpCz‐Trz. And the compounds B ‐DpCpN‐Trz and B ‐DpCpCz‐Trz with a bridge‐like di[2.2]paracyclophane skeleton are meso ‐compounds, thus without optically activity. All emitters show blue emissions peaking from 464 to 485 nm, accompanied by high photoluminescence quantum efficiency (up to 93%). The enantiomers ( R/S )‐ C ‐DpCpN‐Trz and ( R/S )‐ C ‐DpCpCz‐Trz exhibit symmetric circularly polarized photoluminescence spectra with dissymmetry factors (| g PL |) ranging from 3.8 × 10 −4 to 6.7 × 10 −4 in toluene and films. The organic light‐emitting diodes (OLEDs) fabricated with these emitters achieve maximum external quantum efficiencies of up to 19.5%. Notably, the circularly polarized OLEDs (CP‐OLEDs) with ( R/S )‐ C ‐DpCpN‐Trz and ( R/S )‐ C ‐DpCpCz‐Trz demonstrate | g EL | factors of up to 7.6 × 10 −4 . This study demonstrates a feasible way to design TADF materials and enantiomers by incorporating DpCp derivatives for CP‐OLEDs.