Wearing an organic "coat" on nanocrystals of LaF3:Eu3+ to generate dynamic luminescence for optical anti-counterfeit.

A new luminescent material for optical anti-counterfeit was developed by wearing organic Tb (III) complex on nanocrystals of LaF 3 :Eu3+. [Display omitted] • Tb (III) complex was coated on the surface of LaF 3 :Eu3+ nanocrystals. • The prepared core–shell materials exhibited a dynamic luminescence responding to temperature. • The dynamic multicolor emissions show higher security level in anti-counterfeiting. • Temperature-dependent luminescence was used as additional authentication information. Nowadays, the continuous emergence of various fake and inferior products has caused a huge impact on high quality products. For protecting the interests of consumers and enterprises from the fake, the development of anti-counterfeiting technology is particularly significant. Here, temperature-dependent luminescence was used here as additional authentication information to improve the anti-counterfeiting level. In this work, a new luminescent material for optical anti-counterfeit was developed by wearing organic Tb (III) complex on nanocrystals of LaF 3 :Eu3+. The prepared core–shell materials exhibited a dynamic luminescence responding to temperature, mainly due to the energy transfer of hfa → Tb3+ and hfa → Tb3+→Eu3+, and the energy back transfer from the emitting level of the Tb3+ to the excited triplet state of the hfa ligand. The dynamic multicolor emissions show higher security level in anti-counterfeiting. We believe that our research results will provide some guidance for the development of temperature-dependent luminescent materials in anti-counterfeiting applications. [ABSTRACT FROM AUTHOR]