Planar Chiral Thermally Activated Delayed Fluorescence Materials Based on Di2.2paracyclophane for Circularly Polarized Electroluminescence

Abstract In this study, featuring di2.2paracyclophane (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 di2.2paracyclophane 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 di2.2paracyclophane 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.