Photoluminescent Intensity Modulation Of Lanthanide Doped Inorganic Photochromic Materials

Lanthanide doped inorganic photoluminescent materials,whose photoluminescent intensity can be modulated under the stimulation of light,electric-field,magnetic-field and heat,have great potential applications in detection,sensing,anti-counterfeiting,biological probes and other fields.Among these external stimuli,light stimulation has advantages in esasy-accessibility and controlling-convenience.It is an ideal stimulus method.Photochromic materials can respond to light stimulation in at least one direction,and have been used in optical storage,optical switches and other fields.Lanthanide doped inorganic photochromic materials have excellent luminescence and photochromic properties,and their photoluminescent intensity can be modulated based on photochromic reaction.This material will have very broad prospects in the field of optoelectronics.Two kinds of lanthanide-doped inorganic photochromic materials,Er³⁺/Yb³⁺-doped K_0.5Na_0.5NbO₃ferroelectric ceramics and Sr₂SnO₄ doped with different lanthanide ions,were studied.Photochromic phenomena were found in Er³⁺/Yb³⁺-doped K_0.5Na_0.5NbO₃.The color of Er³⁺/Yb³⁺-doped K_0.5Na_0.5NbO₃ changed to gray under visible light stimulation.Furthermore,based on photochromic reaction,the photoluminescent intensity can be modulated.Under light stimulation,the up-conversion luminescence decreases by up to 96%.Based on photochromic reaction,up-conversion luminescence can be reversibly modulated by alternating light and thermal stimulation or light and electric stimulation.Among these two methods,the combination of light and electric field stimulation is a new modulation method in photochromic luminescent modulation materials.It is expected to combine ferroelectric memory of ferroelectrics with optical storage of photochromic photoluminescent modulation materials in K_0.5Na_0.5NbO₃ to achieve multi-dimensional high-density storage.By doping different lanthanide ions(Eu³⁺,Er³⁺,Tm³⁺,Ho³⁺and Pr³⁺)into Sr₂SnO₄,we found that lanthanide ion doping has an important relationship with photochromism of Sr₂SnO₄,and we studied the photochromism mechanism of lanthanide doped Sr₂SnO₄.Among the different lanthanide ions doped Sr₂SnO₄,only Sr₂SnO₄:Eu³⁺and Sr₂SnO₄:xEr³⁺exhibit photochromism.And Sr₂SnO₄:xEr³⁺is a new photochromic material.Under the stimulation of ultraviolet light,Sr₂SnO₄:Eu³⁺and Sr₂SnO₄:xEr³⁺can change from white to purple and pink,respectively,and then they can return to the original color under the stimulation of visible light.Based on photochromic reaction,photoluminescent intensity modulation controlled by ultraviolet and visible light has been realized in these two materials.