Design, Development And Application Exploration Of Trap-controlled Optical Materials That Can Be Displayed Differentially In Bright And Dark Dual Fields

The trap-mediated optical display materials have excellent rechargeable and photophysical properties.Under external stimulus,the"capture"and"release"process of the internal electrons and holes can generate specific optical signals to realize the transmission of information.Visually readable codes with encryption function play an integral role in the field of information security and anti-counterfeiting encryption.However,the traditional optical display materials and coding methods are difficult to enable codes to be visually read,time-dependent dynamically displayed and differently encrypted in bright and dark fields,greatly reduce its practical value in intelligent anti-counterfeiting systems that require flexible editing and high encryption complexity.In view of the above problems,this paper mainly conducts in-depth research through the innovation of material design and coding methods and the expansion of application scenario and optical functions.First,using the first-proposed material design strategy that couples oxygen vacancy engineering,piezoelectric lattice selection,and activator doping,a lanthanide ion-doped optical display material La_1.95Ti₂O₇:Pr³⁺is successfully developed that integrates color change?>18 hours for bright field?and persistent luminescence?>6 hours for dark field?.More importantly,different external stimuli can selectively release electrons in traps related to color change or persistent luminescence,thermal and photo-stimuli can simultaneously eliminate color change and afterglow and produce corresponding stimulus luminescence,while mechano-stimulation can only eliminate afterglow luminescence but not color change.Based on this characteristic,a coding method combining mechano-,thermo-and photo-stimulus is designed and the developed material were used to initially prove the feasibility of dual-field optical information visual reading,time-dependent display and differential encryption.At the same time,an electron selective delamination model based on the depth of the trap is established to explain the inherent mechanism of the color change and luminescence response to multiple stimuli.This result makes multi-level encryption of optical information based on single-component materials possible and opens a new path for the design of ultra-highly integrated smart optical display materials.In addition,inspired by the characteristics of the developed new optical display material La_1.95Ti₂O₇:Pr³⁺,it is embedded in soft-based thermoplastic polyurethane and hard-based optical epoxy resin respectively,which is used as an optical indicator for multi-stimulus response,to prepare flexible composite films and rigid composite cylinder,and use the developed new coding method which based on multi-stimulus response performance to simultaneously realize the dual-field coding's to be time-dependent displayed,flexible edited and differently encrypted in flexible film and composite cylinder.The optical properties of the material are also expanded through dual lanthanide doping of Pr³⁺and Er³⁺into La_1.95Ti₂O₇,including multicolored?red,orange,yellow,and green?and bitemporal?fluorescent and long-lived?photoluminescence?including downshifted and upconverted emissions?.It demonstrates the wide application prospects of this material in the fields of information storage and encryption,multi-dimensional anti-counterfeiting,optoelectronic display and optical fingerprint authentication.