Chiral Co‐Assembly with Narrowband Multi‐Resonance Characteristics for High‐Performance Circularly Polarized Organic Light‐Emitting Diodes

Abstract A promising kind of ternary chiral co‐assemblies with high PLQY, large dissymmetry factor (g_lum), and narrowband multi‐resonance characteristics are achieved by codoped‐thermal annealing treatments of achiral luminescent polymer F8BT, chiral inducers R/S‐5011, and achiral FRET acceptor DBN‐ICZ. The optimized co‐assemblies (F8BT)_0.9‐(R/S‐5011)_0.1‐(DBN‐ICZ)_0.005 display narrowband yellow emission with full‐width half maximum (FWHM) of 37 nm, PLQY of 79%, and intense CPL signals with |g_lum| of up to 0.26. Meaningfully, solution‐processed CP‐OLEDs by using those ternary chiral co‐assemblies as emitting layer are successfully fabricated, which display yellow circularly polarized electroluminescence (CPEL) with EQE_max of 4.6% and g_EL of up to 0.16. The corresponding Q‐factor could reach up to 7.36 × 10⁻³, which is the highest of all the reported CP‐OLEDs. Moreover, the devices also exhibit excellent comprehensive device performance with low V_on of 7.0 V, high L_max of about 25 000 cd m⁻², extremely low efficiency roll‐off with EQE of 4.3% at 10 000 cd m⁻², as well as narrowband EL with FWHM of only 39 nm. The proposed ternary co‐assembly strategy in fabricating CP‐OLED provides the possibility to achieve high comprehensive device performance such as balancing high EQE and large g_EL value, as well as narrowband emission, high brightness and low efficiency roll‐off simultaneously.