Achieving excitation wavelength-power-dependent colorful luminescence via multiplexing of dual lanthanides in fluorine oxide particles for multilevel anticounterfeiting.

The optical characteristics of multimode luminescent materials like multimode luminescence (photoluminescence, afterglow, thermoluminescence) and a multi-excitation source (light, thermal, mechanical force) play crucial roles in optical data storage and readout, document security and anticounterfeiting. A higher level of advanced anticounterfeiting may rely on multimode anticounterfeiting materials that can realize multicolor luminescence. Here, a highly integrated multimode and multicolor YOF:Er,Eu material is developed through multiplexing of dual lanthanides in fluorine oxide particles. In photoluminescence and photoluminescence/up-conversion luminescence modes, the material YOF:Er,Eu has the characteristic of excitation wavelength and power dependence. In the photoluminescence mode, under excitation at 254 nm and 365 nm, YOF:Er and YOF:Eu showed bright red and green emissions, respectively. In the photoluminescence/up-conversion mode, under the increased excitation power from 0.2 to 2.0 W cm, the color of luminescence emission can be finely tuned from red to orange, yellow and green. Taking this unique excitation wavelength-power-dependent luminescence property into account, a multilevel anticounterfeiting device with the Lily pattern was designed. The device readily integrates the advantages of the excitation wavelength-dependent photoluminescence emissions and excitation power-dependent photoluminescence emissions in one overall device. These findings offer unique insight for designing highly integrated multimode, multicolor luminescence materials and advanced anticounterfeiting technology toward a wide variety of applications, particularly multilevel anticounterfeiting devices.