Circularly polarized thermally activated delayed fluorescence OLEDs with nearly BT.2020 red emission

Abstract

Thermally activated delayed fluorescence (TADF) materials with saturated red emission anda large x CIE coordinate hold significant potential for application in high-efficiency, high-contrast and wide-gamut display techniques. Recently, circularly polarized organic light-emitting diodes (CP-OLEDs) have attracted increasing attention for the enhancement of electroluminescence (EL) performance via minimizing the light loss caused by the integrated polarizer. However, the efficient red CP-OLEDs have been rarely reported by now. In this work, a simple approach to CP-OLEDs towards BT.2020 red emission was applied via the integration of polycyclic aromatic chromophore and chiral octahydrobinaphthol, which consequently resulted in the intense circularly polarized luminescence (CPL), long-wavelength emission and excellent photoluminescence quantum yields (PLQY). The CP-OLEDs based on (R)-OBN-3CN demonstrated the state-of-the-art EL performance with the maximum external quantum efficiencies (EQEmax) of 19.7 % at 646 nm and the dissymmetry factor (gEL) of −1.1 × 10−3. Furthermore, CP-OLEDs doped with 12 wt% (R/S)-OBN-3CN exhibited efficient red electroluminescence with the CIE coordinates of (0.70, 0.30), which was very close to the saturated red emission specified in BT.2020.