Luminescent Properties Of A Gallium Germanate Persistent Luminescent Phosphor And The Application For Dynamic Anticounterfeiting

In recent years,with the increasing number of counterfeit products and information disclosure cases,anticounterfeiting and information protection have become a close concern in many fields.Traditional anticounterfeiting technology has the disadvantage of low anticounterfeiting strength and being easily replicated.Subsequently,researchers have developed luminous printing anticounterfeiting technology based on carbon dots,semiconductor quantum dots,metal organic framework?MOF?,rare earth elements doping and organic dyes.Compared with the traditional anticounterfeiting technology,the anticounterfeiting reliability has been improved,However,since the anticounterfeiting process is static,the security strength is yet to be improved.In contrast to the traditional static anticounterfeiting technology,dynamic anticounterfeiting technology can realize different displaying colors or patterns under single or different stimuli and conditions with specifically designed luminescentsigns,thusrealizedynamicanticounterfeitingprocess.The anticounterfeiting process is dynamic and has the specificity of material design,so it is safe and more stable.Due to the characteristics of continuous luminescence in dark conditions,persistent luminescent?PersL?materials have been widely studied and applied in the fields of special lighting,optical storage and military engineering.However,there has been rare applications in the field of dynamic anticounterfeiting technology.The research keystone of this thesis is to develop PersL materials that can be applied in dynamic anticounterfeiting technology.We chose Sr₂Ga₂GeO₇ as the matrix material,which has the advantages of low phonon energy,good chemical stability and abundant traps.The Sr₂Ga₂GeO₇:Tb³⁺PersL phosphor synthesized by high temperature solid phase method presents green photoluminescent and PersL color.More interestingly,with the changing of Tb³⁺doping concentration,the PersL lifetime is different correspondingly.Based on this feature,luminescent patterns for dynamic display can be designed.Luminescent labels made with the Sr₂Ga₂GeO₇:Tb³⁺PersL phosphors have promising potentials for using in dynamic anticounterfeiting.Although the adjustment of the PersL lifetime has been achieved by adjusting the doping concentration of Tb³⁺in Sr₂Ga₂GeO₇:Tb³⁺,thereby realizing the dynamic change of the luminescent pattern.However,the luminescent color of the phosphor is single so that the anticounterfeiting strength of the corresponding anticounterfeiting products is yet to be improved.To solve this problem,we synthesized Sr₂Ga₂GeO₇:Pr³⁺phosphor.By adjusting the concentration of Pr³⁺,the adjustment of the PersL color and lifetime was realized.The luminescent labels made with such single-ion-doped multicolor PersL phosphor show unique and excellent dynamic anti-counterfeiting performance.