In this article, we current the luminescent anti-counterfeiting varnish modified with NaErF4:Tm3+@NaYF4 UCNPs to guard paper or other surfaces. This get the job done displays the effect of co-doping the NaErF4 Main with Tm3+ ions in the Main@shell NaErF4:Tm3+@NaYF4 UCNPs and the improvement of UC depth. The energy trapping facilities https://rafaellmjgd.topbloghub.com/20045271/little-known-facts-about-anti-counterfeit-solution