There is an urgent need to develop next-generation information
storage and display materials to protect confidential information.
Herein, we introduce the vat photopolymerization (VP) 3D printing
technology with low-intensity visible light to fabricate two kinds
of new fluorescent hydrogel-based information carriers in a green
and efficient way. One of them affords the characteristics of time-dependent
multicolor fluorescence and reversible photochromism, and the other
features multifactor modulation character and temperature-dependent
photoluminescence when doped with lanthanide ions. A 3D code-producing
array constructed from these hydrogels is able to render dynamic information
transformations on a time scale by controlling UV exposure and heating
treatment. More importantly, a cryptographic matrix composed of these
hydrogels makes the encrypted information only identifiable at a specific
time in accordance with the sequence of photochromism; meanwhile,
the information can self-erase after being read according to the fading
behaviors upon exposure to air. The related works are still rare in
the field of information encryption and decryption. We expect the
VP 3D printing technology to guide the future intelligent manufacturing
for fluorescent hydrogels; additionally, we hope that these two fluorescent
hydrogels can serve as a new avenue for the future development of
information storage and display materials.