Excitation wavelength-dependent room temperature phosphorescence based on dual confinement of an organic-inorganic matrix for dynamic information encryption.

In the digital age of today, the importance of information encryption is increasingly recognized globally. Emerging room temperature phosphorescence (RTP) materials have stood out in the information encryption field. However, the majority of RTP materials have complicated synthesis processes, high costs, environmental problems, and potential bio-toxicity, which limit their wide application. Here, carbon dots (CDs) prepared from simple molecular chromophores, with the dual synergy of layered double hydroxides (LDHs) and polyvinyl alcohol (PVA), not only acquired RTP properties but also exhibited excitation wavelength-dependent characteristics. The mechanism shows that the two-dimensional template of inorganic LDHs can orderly arrange CDs. The organic PVA with abundant hydroxyl groups can be closely connected to guest molecules through hydrogen bonds. The resulting CDs-LDHs@PVA composite film demonstrates a RTP lifetime of 205 ms and a RTP quantum yield of 5.04%, and has broad application prospects in the field of optical anti-counterfeiting.