Chiral Co-Assembly with Narrowband Multi-Resonance Characteristics for High-Performance Circularly Polarized Organic...

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.