Diverse High‐Performance Circularly Polarized Organic Light‐Emitting Diodes Based on Chiral Host Molecules via Chiral Energy Transfer Process

ABSTRACT The circularly polarized organic light‐emitting diodes (CP‐OLEDs) are of great significance in advanced optoelectronic applications, as they can directly emit circularly polarized electroluminescence (CPEL). Although various CPEL systems have been realized using special chiral emitters, their practical application is often hindered by complex synthesis and tedious enantiomer separation. Therefore, generating CPEL directly from readily available achiral luminescent materials is highly desirable. Herein, two pairs of chiral materials, ( R / S )‐ mCP‐CN and ( R / S )‐ tmCP‐CN , with excellent thermal stability, high singlet/triplet energy levels, obvious CPL properties, and bipolar carrier transport features are designed and synthesized. By employing them as hosts and achiral multiple‐resonance thermally activated delayed fluorescence (MR‐TADF) emitter as the guest, the corresponding CP‐OLEDs achieve good electroluminescence dissymmetry factors (g EL ) of 1.37–2.37 × 10 −3 , small full‐width at half‐maximums of 29–31 nm, and high external quantum efficiencies (EQE) of 34.8%–36.7% with ultra‐low roll‐off (EQEs of 25.1%–25.8% at 5000 cd m −2 ). Furthermore, the CP‐OLEDs fabricated with commercially available achiral phosphorescence and conventional donor‐acceptor (D‐A) TADF materials also generate intense g EL values on the order of 10 −3 , along with outstanding EQEs of 22.8%–38.9%, demonstrating a simple and universal strategy for achieving CPEL using available achiral emitters and significantly extending the scope of CP‐OLEDs.