Simultaneous promotion of efficiency and lifetime of organic phosphorescence for self-referenced temperature sensing

A group of fluorine-substituted organic phosphors with outstanding room-temperature phosphorescence (RTP) features were synthesized and characterized. Systematic study reveals that the variation of substituent position with fluorine can fine-tune RTP property through regulation of molecular packing. The new luminogen (namely p-DFFM) endows maximum RTP efficiency and lifetime with unique π-π slipping arrangement in crystals, which is different from the reported intermolecular π-π stacking arrangement. More importantly, p-DFFM enjoys outstanding thermoresponsive property in crystals and doped films. Their phosphorescence lifetime increases linearly with lowering temperature from 50 to –10 °C. Such characteristic thermoresponsive property of p-DFFM is unambiguously revealed, which is attributed to thermal expansion mechanism. It is noteworthy that a novel method based on persistent phosphorescence lifetime and image analysis (PLIA) for visual and self-referenced temperature sensing is further developed for practical applications.