Nanohybrids with switchable multicolour emission for anticounterfeiting

Dual-mode and multimode excited fluorescent materials have shown huge value in the anti-counterfeiting field. Herein, a mechanical mixing and ball milling method was used to design nanohybrids of Tm/Yb:NaYF4 upconversion phosphor (UCP) + CsPbX3 (X = Cl/Br/I) quantum dot (QD) glasses, which display a multimode excitation characteristic. Mechanistic investigation reveals that the multimode excitation characteristic stems from radiation photon reabsorption and the no-radiation Forster resonance energy transfer from the Tm/Yb:NaYF4 UCP to the CsPbX3 QDs, in which the upconversion luminescence of the CsPbBr3 QDs can be sensitized by the Tm/Yb:NaYF4 UCP. Notably, the red upconversion luminescence of Tm3+ ions can be enhanced by CsPbX3 QDs through the no-radiation Forster resonance energy transfer process. Attractively, the nanohybrids can emit polychromatic luminescence from 417 nm to 696 nm under UV light and emit bluish purple or red luminescence under 980 nm excitation. A practical anti-counterfeiting application was successfully realized based on this material with superior photostability, which proves that the multimode excited nanohybrids have great potential application in the anticounterfeiting field.

Automated summary

Dual-mode and multimode excited nanohybrids of Tm/Yb:NaYF4 upconversion phosphor (UCP) + CsPbX3 (X = Cl/Br/I) quantum dot (QD) glasses were designed using a mechanical mixing and ball milling method. The nanohybrids exhibit a multimode excitation characteristic due to radiation photon reabsorption and no-radiation Förster resonance energy transfer. These nanohybrids can emit polychromatic luminescence from 417 nm to 696 nm under UV light and bluish purple or red luminescence under 980 nm excitation. Practical anti-counterfeiting applications based on these nanohybrids with superior photostability have been successfully realized, demonstrating their great potential in the anti-counterfeiting field.