(a) The photoinduced decomposition reaction of AnSO under 400 nm. (b) The process for product authentication by a smartphone app based on the color changes with time. (c) Comparison of testing results between two patches with one incorrect and another correct. Reversible reactions based on photoinduced isomerization of (d) SP and (e) DAE. (f) Dynamic changes with different UV irradiation durations of a QR code image composed of cellulose-based trichromatic materials under 365 nm and visible light. (g) The reversible color change loop of the fluorescent rainbow over time. (h) Information readout of the reassembled and encrypted fluorescent pattern with four kinds of hydrogels under 254 nm UV light. (i) Four umbrella-shape fluorescence patterns composed of DSA-2SP as the anticounterfeiting label displayed under the corresponding input. (j) The dual decryption process of the dynamic fluorescent anticounterfeiting QR code printed with liquid crystal nanoparticle-based ink. Reproduced with permissions: (a) from [74
], Copyright 2016, Wiley-VCH; (d, e) from [73
], Copyright 2012, The Royal Society of Chemistry; (f, g) from [28
], Copyright 2017, Wiley-VCH; (i) from [79
], Copyright 2017, American Chemical Society; (j) from [80
], Copyright 2019, Wiley-VCH.