LAUSR

Organic light‐emitting diodes (OLEDs) that can simultaneously achieve narrowband emission, high efficiency, and circularly polarized luminescence remain a formidable challenge. In this study, a simple strategy is developed to address this challenge. A chiral exciplex‐forming co‐host is first designed by employing a chiral donor and an achiral acceptor molecule. The chiral exciplex host enables an achiral green multiple‐resonance thermally activated delayed fluorescence emitter to achieve high‐performance circularly polarized electroluminescence (CP‐EL) with a high external quantum efficiency of 33.2%, large electroluminescence dissymmetry factor of 2.8 × 10−3, and a small full‐width at half‐maximum of 42 nm. This work provides a general approach for realizing CP‐EL using easily available achiral emitters and can significantly extend the scope of circularly polarized OLEDs.