Chiral Single Molecule with Biphenyl Component Exhibiting Both TADF and RTP Emissions Enables Highly Efficient CP‐OLEDs

Abstract Chiral single molecules that exhibit both thermally activated delayed fluorescence (TADF) and room temperature phosphorescence (RTP) pose significant challenges, primarily due to their competitive luminescence mechanisms and the scarcity of studies on their applications in circularly polarized organic light‐emitting diodes (CP‐OLEDs). In this work, we develop a novel chiral emitter, CP‐D3, with an axially chiral biphenyl segment selected as the chiral center. As a result, CP‐D3 successfully exhibits both TADF and RTP properties with a high photoluminescence (PL) efficiency of 91%. The high dissymmetry factors ( g CPPL ) of −7.98 × 10 −3 and +7.47 × 10 −3 are obtained for ( R/S )‐CP‐D3, respectively. Notably, the CP‐D3‐based CP‐OLEDs achieve a maximum external quantum efficiency (EQE max ) of 32.44%, which represents the highest value among chiral luminance materials based on an axially chiral biphenyl component. The g CPEL is recorded as −8.13 × 10 −4 /+5.92 × 10 −4 for ( R / S )‐CP‐D3‐based CP‐OLEDs. This work presents the first report on a chiral single‐molecule emitter incorporating an axially chiral biphenyl component, which exhibits simultaneous TADF and RTP emissions and enables highly efficient CP‐OLEDs.