Planar Chiral Multiple Resonance Thermally Activated Delayed Fluorescence Materials for Efficient Circularly Polarized Electroluminescence

Chiral boron/nitrogen doped multiple resonance thermally activated delayed fluorescence (MR-TADF) emitters are promising for highly efficient and color-pure circularly polarized organic light-emitting diodes (CP-OLEDs). Herein, we report two pairs of MR-TADF materials (Czp-tBuCzB, Czp-POAB) based on planar chiral paracyclophane with photoluminescence quantum yields of up to 98 %. The enantiomers showed symmetric circularly polarized photoluminescence spectra with dissymmetry factors |g(PL)| of up to 1.6x10(-3) in doped films. Meanwhile, the sky-blue CP-OLEDs with (R/S)-Czp-tBuCzB showed an external quantum efficiency of 32.1 % with the narrowest full-width at half-maximum of 24 nm among the reported CP-OLEDs, while the devices with (R/S)-Czp-POAB displayed the first nearly pure green CP electroluminescence with |g(EL)| factors at the 10(-3) level. These results demonstrate the incorporation of planar chirality into MR-TADF emitter is a reliable strategy for constructing of efficient CP-OLEDs.

Automated summary

Chiral boron/nitrogen doped multiple resonance thermally activated delayed fluorescence (MR-TADF) emitters based on planar chiral paracyclophane exhibit high photoluminescence quantum yields and symmetric circularly polarized photoluminescence spectra in doped films. The sky-blue CP-OLEDs with (R/S)-Czp-tBuCzB show high external quantum efficiency and narrowest full-width at half-maximum among reported CP-OLEDs, while the devices with (R/S)-Czp-POAB display nearly pure green CP electroluminescence. These findings demonstrate the reliable strategy of incorporating planar chirality into MR-TADF emitters for efficient CP-OLEDs construction.