The Construction Of Piezoelectric Trap-controlled Stress Luminescence And The Study Of Multi-mode Luminescence Coupling

Mechanoluminescence materials can release the absorbed energy in the form of light when stimulated by external mechanical stress?impact,friction,tension,compression,etc.?,and realize the mechanical to light energy conversion.Since mechanoluminescence materials can convert the stress distribution of stressed object into an image and enable people to observe the external stress stimulus of this object,mechanoluminescence materials have made significant progress in artificial intelligence skin,stress sensor,urban infrastructure management,and bio-imaging.In addition,since the emission color?wavelength?,lifetime,and excitation mode of the mechanoluminescence materials are good information encryption methods,they play a vital role in data communication and information security.However,there are still some problems that hinder the further development of mechanoluminescence materials.For example,in the case of a single irradiation,when these materials are subjected to continuous external mechanical stress stimulation,their mechanoluminescence intensity usually shows a very strong attenuation shortly.The continuous ultraviolet radiation will excite photoluminescence of phosphors simultaneously,which reduces the signal-to-noise ratio and complicates the operation process in potential applications.Therefore,it is still a significant challenge to realize non-decayingMechanoluminescenceintrap-controlledreproducible Mechanoluminescence materials from the aspects of not only proposing feasible solutions but also advancing practical applications.Additionally,conventional mechanoluminescence materials generally display unicolor,unitemporal,and unimodal?occasionally bimodal?emission,resulting in lower coding levels.The encoding mode is easily counterfeited by certain substitutes,while physical mixing of different materials suffers from uneven dispersion and performance mismatch.Therefore,there is an urgent need to realize multicolor,multitemporal and multimodal in a single material.In view of the above two problems,this paper mainly studies from the following two aspects:1)According to the three elements of piezoelectric-based trap controlled mechanoluminescence materials,piezoelectric matrix,trap center and luminescence center,materials with non-centrosymmetric structures are selected from the long afterglow materials.The luminescence center and trap center of the materials were used to realize mechanoluminescence,thereby obtaining a new reproducible mechanoluminescence material Li₂MgGeO₄:Mn²⁺.The performance characterization shows that the irradiated Li₂MgGeO₄:Mn²⁺can emit bright green light when subjected to external mechanical stress stimulation when the mechanoluminescence intensity of Li₂MgGeO₄:Mn²⁺shows no obvious attenuation in a short time.Investigation of trap properties suggests that the unique non-decaying mechanoluminescence behavior should arise from the deep traps existing in Li₂MgGeO₄:Mn²⁺,which provide electron replenishment for shallow traps that release small numbers of electrons during short-term cyclic friction.These results are expected to provide a reference for ultimate achievement of long-term non-decaying mechanoluminescence in such materials.2)For the first time,the superior integration of colorful?red-orange-yellow-green?,bitemporal?fluorescent and delayed?,and four-modal?thermo-mechano-motivated and upconverted/downshifted?emissions in NaNbO₃:Pr³⁺,Er³⁺via optical multiplexing of piezoelectric-based dual-lanthanide dopants is demonstrated.In addition,the as-prepared versatile NaNbO₃:Pr³⁺,Er³⁺luminescent microparticles are embedded into polymer films to achieve waterproof,flexible/wearable and highly stretchable features.And further use the simple and commonly available tools?including the LED of a smartphone,pen writing,cooling-heating stimuli,and ultraviolet/near-infrared lamps?to demonstrate its potential applications in the field of anti-counterfeiting and information coding.These results offer new ideas for the design,development,and application of highly integrated stimuli-responsive luminescent materials.