Thermally activated delayed fluorescence and room-temperature phosphorescence in naphthyl appended carbazole-quinoline conjugates, and their mechanical regulation

The influences of naphthyl and/or phenyl rings at the 2,4-positions of the quinolinyl fragments in carbazole-quinoline conjugates are studied. The centric phase of one of the conjugates (β- CQNN ) revealed both thermally activated delayed fluorescence (TADF) and room-temperature phosphorescence (RTP), while prompt fluorescence and RTP were observed in the non-centric phase (α- CQNN ) that can regenerate the emission features of β- CQNN via mechanical grinding. This unique observation is explained by the modulation of the higher-lying triplet (T 2 ) energy level caused by conformational change. We report the first mechanical regulation of thermally activated delayed fluorescence and room-temperature phosphorescence. This study paves the way to design new responsive dual-light emitters.