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

Guo, Chen-Hao; Zhang, Yuewei; Zhao, Wen-Long; Tan, Ke-Ke; Feng, Liheng; Duan, Lian; Chen, Chuan-Feng; Li, Meng · Adv Mater · 2024

basic_science · Level V

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Abstract

A promising kind of ternary chiral co-assemblies with high PLQY, large dissymmetry factor (g<sub>lum</sub>), 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)<sub>0.9</sub>-(R/S-5011)<sub>0.1</sub>-(DBN-ICZ)<sub>0.005</sub> display narrowband yellow emission with full-width half maximum (FWHM) of 37 nm, PLQY of 79%, and intense CPL signals with |g<sub>lum</sub>| 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<sub>max</sub> of 4.6% and g<sub>EL</sub> of up to 0.16. The corresponding Q-factor could reach up to 7.36 × 10<sup>-3</sup>, which is the highest of all the reported CP-OLEDs. Moreover, the devices also exhibit excellent comprehensive device performance with low V<sub>on</sub> of 7.0 V, high L<sub>max</sub> of about 25 000 cd m<sup>-2</sup>, extremely low efficiency roll-off with EQE of 4.3% at 10 000 cd m<sup>-2</sup>, 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<sub>EL</sub> value, as well as narrowband emission, high brightness and low efficiency roll-off simultaneously.