Research / 2021 / Article / Fig 8

Review Article

Afterglow Carbon Dots: From Fundamentals to Applications

Figure 8

(a) Photographs of CDs@molten salt upon turn-on and turn-off of the excitation at wavelengths of 356 and 395 nm, respectively (adapted and copyright permission [80], Royal Society of Chemistry). (b) Photographs of CDs@nanoclay under excitation on and off at wavelengths of 254, 302, and 365 nm, respectively (c) Afterglow decay profiles of CDs@clay at emission wavelengths of 450, 477, and 517 nm. (f) CIE coordinate diagram showing the change in afterglow color output of CDs@clay upon changing temperature from 298 to 513 K (under excitation at 365 nm). (g) Reversibility of afterglow transition from cyan (at 517 nm) to blue (at 450 nm) upon alternative change of temperature in the window (adapted and copyright permission [84] (b–g), Royal Society of Chemistry). (h) Afterglow luminescence profiles of CDs@SiO2 as a function of measurement temperatures (excitation at 365 nm). (i) Normalized RTP and TADF emission intensity as a function of temperature (excitation at 365 nm). Inset: typical afterglow color output originating from RTP (green) and TADF (blue) (adapted and copyright permission [97] (h, i), Royal Society of Chemistry). (j) Schematic energy level diagrams showing the generation of a new triplet state () as a result of the aggregation of CDs. (k) RTP emission profiles of a THF dispersion of TA-CDs with the addition of different volumes of water. Inset: the dependence of RTP intensity on the added water content (%) in the CD mixture. (c) TEM image of CDs in a mixture of THF:H2O (1 : 9 %). Inset: enlarged TEM of an aggregate comprising CDs (adapted and copyright permission [40] (j–l), Wiley-VCH Verlag GmbH & Co. KGaA). (m) Phosphorescence profiles of CDs@MP in a mixture of HCl/ethanol with different contents of ethanol (%). Insets: photographs of CDs@MP mixtures under daylight and UV light (365 nm) (adapted and copyright permission [52], American Chemical Society).