A Chiral Dual-Core Carbonyl/Amine MR-TADF Emitter for Organic Light-Emitting Devices

Abstract

Chiral multiresonance thermally activated delayed fluorescence (MR-TADF) emitters capable of simultaneously achieving efficient circularly polarized luminescence (CPL) and narrowband emission remain challenging. Herein, we report a pair of chiral carbonyl/amine-based CP-MR-TADF emitters, (R/S)-CONBO, constructed by linking two carbonyl/amine MR-TADF cores with a hydrogenated BINOL-derived chiral scaffold through nonconjugated oxygen bridges. The sterically hindered sp3-hybridized oxygen linkages effectively suppress excessive π-conjugation extension and maintain the intrinsic transitional character of the MR framework (i.e. short-range charge-transfer). As a result, (R/S)-CONBO exhibits bright sky-blue emission in toluene solution, where the emission maximum is located at 486 nm and the corresponding full-width-at-half-maximum is only 37 nm. The enantiomers present oppositely signed circular dichroism and CPL responses, with the luminescence dissymmetry (g) factor reaching the 10–3 level. OLED devices based on (R/S)-CONBO achieve sky-blue electroluminescence centered at 492 nm, with the emission bandwidth limited to 42 nm, and reach a maximum external quantum efficiency of up to 11.8%. This work demonstrates an effective molecular design strategy for integrating chirality into carbonyl/amine MR-TADF systems while preserving narrowband emission characteristics, providing insights into the development of high-color-purity chiral OLED materials.