Aromatic-imide-based TADF enantiomers for efficient circularly polarized electroluminescence

Abstract

Recently, much attention has been paid to circularly polarized organic light-emitting diodes (CP-OLEDs) based on thermally activated delayed fluorescence (TADF) enantiomers. In this paper, we designed and synthesized a pair of aromatic-imide-based TADF enantiomers, namely R/S-OBN-AICz, using chiral perturbation strategy. The chiral emitters concurrently demonstrated efficient TADF and aggregation-induced emission (AIE) properties, together with a small singlet–triplet energy gap (ΔE_ST) of 0.08 eV and a high photoluminescence quantum yield (PLQY) of 81%. Moreover, the TADF enantiomers exhibited clear circularly polarized luminescence (CPL) activities with dissymmetry factor (|g_PL|) values of up to 2.6 × 10⁻³ in toluene solution. Finally, the TADF enantiomers were utilized as emitters to fabricate CP-OLEDs, which achieved clear circularly polarized electroluminescence (CPEL) signals, a high maximum external quantum efficiency (EQE_max) of 19.0% and a high maximum luminance (L_max) of 24 790 cd m⁻².