Upconversion Luminescence Properties And Applications Of Rare Earth Ion-doped Tungstate Photonic Crystals

Reversible up-conversion luminescence modulation has broad application prospects in optical switches,fingerprint collection,anti-counterfeiting,optical storage devices and temperature sensors.This series of achievements has further enhanced people's enthusiasm for rare earth ion doping upconversion luminescence modulation.Therefore,this work mainly focuses on the regulation mechanism of electrochromic effect/negative expansion effect on the upconversion luminescence of rare earth ion-doped tungstate photonic crystals,and experiments have shown that it has good performance in optical storage,temperature sensors and other fields.Studies have found that photochromic and thermochromic can be used to modify up-conversion luminescence.However,the reversible upconversion luminescence modulation induced by electrochromism has not been reported yet.Here,WO₃:Yb³⁺,Er³⁺inverse opal was prepared by the template method,and its electrochromic properties were studied.It was observed that the color of WO₃:Yb³⁺,Er³⁺inverse opal changed from light yellow to blue under the stimulation of negative bias voltage.The color can be restored under the stimulation of positive bias voltage.It is the first time to observe the reversible up-conversion luminescence modulation of WO₃:Yb³⁺,Er³⁺inverse opal induced by electrochromism,with a high degree of modulation(100%).In addition,it is stimulated by alternating between negative and positive bias voltages.The reversibly modulated up-conversion luminescence exhibits good repeatability and stability.This result opens up a new channel for the up-conversion luminescence of modulated materials and shows its application potential in switching,anti-counterfeiting and optical storage devices.For example,the writing and reading of optical data can be obtained in electrochromic WO₃:Yb³⁺,Er³⁺inverse opal,which has potential application prospects in optical storage.The thermal enhancement and quenching of the upconversion luminescence of rare earth ions can be realized in negative expansion and positive expansion matrix respectively,which is the advantage of temperature sensing applications.In this paper,negative expansion Y₂W₃O₁₂:Yb³⁺,Er³⁺inverse opals and positive thermal expansion Ti O₂:Yb³⁺,Er³⁺inverse opals were prepared.The temperature dependence of the upconversion luminescence indicates that the green and red upconversion luminescence of Y₂W₃O₁₂:Yb³⁺,Er³⁺inverse opal increases with increasing temperature,while the upconversion luminescence of Ti O₂:Yb³⁺,Er³⁺inverse opal decreases with 980nm laser excitation.By using the upconversion luminescence intensity ratio of negative thermal expansion Y₂W₃O₁₂:Yb³⁺,Er³⁺inverse opal and positive thermal expansion Ti O₂:Yb³⁺,Er³⁺inverse opal,a new type of upconversion luminescence temperature sensor was obtained.We believe that the negative/positive expansion of this Ti O₂ coated Y₂W₃O₁₂:Yb³⁺,Er³⁺inverse opal can produce a new generation of temperature sensor devices.