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 C₂ 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.