Figure 2.

Photophysical properties of PCDs with 365 nm excitation light. a) The PL emission peak shift of SSFPCDs in aqueous solutions with concentration from 0.1 to 50 mg mL⁻¹. Peak normalized TRES of SSFPCDs aqueous solution with concentration of b) 0.8, c) 6.5, and d) 16.5 mg mL⁻¹ with the decay time on 0, 3, 6, 9, 12, 15, 18, 21, 24, and 27 ns at room temperature. e) Peak normalized TRES of SSFPCDs powder with the decay time on 0, 2, 4, 6, 8, 10, 12, 14, 16, and 18 ns at room temperature. f) Energy levels and fluorescent mechanism of SSFPCDs aqueous solutions and SSFPCDs powder. g) Fluorescence lifetimes of the 16.5 mg mL⁻¹ SSFPCDs aqueous solutions at different wavelengths. h) Temperature‐dependent emission spectra of the 16.5 mg mL⁻¹ SSFPCDs aqueous solutions. i) Temperature‐dependent emission spectra of the SSFPCDs powder.