Chiral Nematic Liquid Crystal Films for High‐Performance Circularly Polarized Organic Light‐Emitting Diodes

Abstract Circularly polarized organic light‐emitting diodes (CP‐OLEDs) have emerged as promising candidates for energy‐efficient displays and eye‐healthy lighting technologies. However, CP‐OLEDs obtained from conventional chiral luminescent materials face critical limitations, including insufficient electroluminescence dissymmetry factors ( g EL ), low external quantum efficiencies (EQEs), and broad emission bandwidths, which collectively impede their practical application. Herein, we proposed a strategy utilizing co‐assembled chiral nematic liquid crystal (N*‐LC) films as emitting layers (EMLs) to fabricate high‐performance CP‐OLEDs. Firstly, chiral inducers ( P/M ‐THH ) were incorporated into the N‐LC ( 2PFP ) host. Subsequent thermal annealing yielded intrinsically luminescent N*‐LCs films exhibiting intense circularly polarized luminescence (CPL) with | g lum | up to 1.33. Introducing the achiral energy acceptor BCz‐BN at optimal concentrations enabled efficient Förster resonance energy transfer (FRET) (Φ ET = 99%), producing ternary co‐assembled N*‐LCs films. These films retained the nematic order while inheriting the narrowband emission and high photoluminescence (PL) quantum yield of BCz‐BN . This approach achieves unprecedented CP‐OLED performance, delivering the highest reported combination of key metrics to date: a | g EL | value of 0.61, a maximum EQE of 9.0%, and narrowband electroluminescence with a full width at half maximum (FWHM) of 32 nm. These findings establish a novel pathway for fabricating high‐performance CP‐OLEDs and open up a new avenue for exploring the chiral optoelectronic application.