Ultra-narrowband organic room-temperature phosphorescence achieved by boosting low-frequency vibronic coupling
2026-08-26
We pioneered a strategy based on low‐frequency vibronic coupling to design narrowband room‐temperature phosphorescent (RTP) materials. Here we select coronene derivative (CoDe) system and report that attaching aroyl group to the coronene core disrupts its intrinsic symmetry and introduces abundant low‐frequency vibrational modes, thereby affording efficient room‐temperature phosphorescence with a full width at half maximum (FWHM) of approximately 25 nm or narrower. In CoDe systems functionalized with additional thioether groups, ultra-narrowband organic phosphorescence materials with exceptionally small FWHM (9.6 nm), high afterglow efficiency (50%), and long phosphorescence lifetimes (1.5 s) are achieved in host matrices under ambient conditions. Mechanistic studies reveal that this spectral narrowing relates to the selective amplification of low‐frequency vibronic coupling through a moderate heavy‐atom effect provided by the thioether groups. Equally crucial would be the suppression of excited‐state relaxation and spectral broadening via relatively strong noncovalent interactions between the thioether groups and the host matrices (sulfur bonding interactions) at room temperature.