NIR triggered NaYF4:Yb3+,Tm3+@NaYF4/CsPb(Br1-x/Ix)3 composite for up-converted white-light emission and dual-model anti-counterfeiting applications

Assembling nanomaterials from two classes with exceptional control at the nanoscale can lead to new nanohybrids with novel properties. Here, we report the tunable up-conversion luminescence properties of CsPb(Br1-x/Ix)3 perovskite nanocrystals (PeNCs) sensitized by NaYF4:Yb,[email protected]4 up-conversion nanoparticles (UCNPs) at 980 nm excitation. The up-conversion luminescence of NaYF4:Yb3+,Tm3+@NaYF4/CsPb(Br1-x/Ix)3 composite demonstrates that the radiative photon reabsorption process is accountable for the UC energy transfer from excited levels of Tm3+-based UCNPs to PeNCs. The long-lived Tm3+ states feed PeNCs carriers with intrinsic lifetimes extending from nanoseconds to microseconds. By varying the UCNPs/PeNCs concentration ratio, the NaYF4:Yb3+,Tm3+@NaYF4/CsPb(Br0.55I0.45)3 composite generates UC white light emission. The near-infrared excited white light-emitting devices are more compatible with human tissues than blue light-excited ones. Therefore, the prototype of UC white light-emitting diode is developed by coupling the UCNPs/PeNCs composite coated glass plate onto a commercial 940 nm-light-emitting diode chip. To overcome the counterfeiting risk that arises in the case of a single fluorescence mode, we developed a simple dual-model strategy based on manipulation of UC and down-conversion luminescence in anti-counterfeiting under 980 nm and 365 nm excitation, which makes it difficult to encrypt the information. In addition, the UCNPs/PeNCs composite exhibited better photostability under near-infrared illumination, retaining 85% of initial photoluminescence intensity, solving the problem of photo-instability.