Fig 1

a) Schematic illustration of the preparation process for FA-CDs and FA-CDs#CA, and photographs of the FA-CDs#CA powder under both daylight and ultraviolet (UV) light (365 nm). b) The X-ray diffraction patterns of FA-CDs, pristine CA, and FA-CDs#CA. c) Photographs of the FA-CDs#CA powder, captured at various time after removal of the irradiation source under different temperatures (excitation wavelength (λexc.), 365 nm)."

Fig 2

(a–c) TEM images of FA-CDs#CA composite, (b) is a magnified TEM image region of (a) marked in red, (c) is a magnified high-resolution TEM image region of (b) marked in green. d–f) The dark-field SEM image (d) and the energy-dispersive spectra (e–f) of FA-CDs#CA. g–i) The energy-dispersive elemental mappings of C K (g), N K (h), and O K (i) corresponding to the SEM image in (d)."

Fig 3

a) The excitation-afterglow mapping of the FA-CDs#CA powder at ambient conditions. b) The afterglow emission spectra of FA-CDs#CA (powder) at different temperatures (λexc. = 365 nm). c) The afterglow color of FA-CDs#CA in the CIE-1931 color coordinates at different temperatures. d) The temperature-dependent DF decay spectra of FA-CDs#CA at different temperatures (λexc. = 365 nm, λem = 470 nm). e-h) Time-resolved afterglow emission spectra of FA-CDs#CA at e) 77 K, f) 298.15 K, g) 323.15 K and h) 473.15 K (λexc. = 365 nm). i) DF decay rates of FA-CDs#CA as a function of temperature and fitting curve based on Eq. (2)."

Fig 4

a) Schematic illustration of the formation of FA-CDs#CA through covalently fixation and co-crystallization processes. b) Proposed emission mechanism for the decrease in ΔEST and the activation of dual-mode emission (DF and Phos) from FA-CDs#CA. Abbreviations of excitation (EX), intersystem crossing (ISC), reversed ISC (RISC), delayed fluorescence (DF), and phosphorescence (Phos) are used."

Fig 5

a–d) Demonstration of stimulation-response TRA anti-counterfeiting and information encryption systems utilizing FA-CDs#CA and FA-CDs#amylum phosphors. e) The variation in afterglow colour of FA-CDs#CA within the temperature range of 298.15 to 473.15 K (with a variation of 20 K)."