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Abstract Herein, we report a general strategy for achieving ultra‐pure green emissions by suppressing the shoulder peaks in the emission spectra of conventional polycyclic aromatic hydrocarbons (PAHs). Through precise synthetic fusion of multi‐resonance (MR) fragments with conventional PAH, extended π‐conjugation lengths, increased molecular rigidity, and reduced vibrational frequency could be simultaneously realized. The proof‐of‐concept emitters exhibited ultra‐pure green emissions with dominant peaks at ca. 521 nm, photoluminescence quantum yields that are greater than 99 %, a small full‐width‐at‐half‐maximum of 23 nm, and CIE coordinates of (0.16, 0.77). The bottom‐emitting organic light‐emitting diode (OLED) exhibited a record‐high CIEy value of 0.74 and a high maximum external quantum efficiency of 30.5 %. The top‐emitting OLED not only achieved a BT.2020 green color (CIE: 0.17, 0.78) for the first time but also showed superior performance among all green OLED devices, with a current efficiency of 220 cd A − .
Zhang et al. (Fri,) studied this question.