| It is a new way to develop new materials and deal with the environmental energy crisis by using new materials to convert the energy in the environment into electric energy,and using these"instant energy"to form a functional system.In this paper,a new idea of designing a self-powered functional material system based on PVDF flexible piezoelectric thin film material is proposed.The energy in the living environment is converted into"real-time electric energy",and its application for real-time power supply,mechanoluminescence and sensitive detection is realized.Firstly,according to the strategy of enhancing both photothermal and pyroelectric conversion at the same time,a high-performance photothermal pyroelectric power generation material(rGO-PEI/PVDF)was designed and prepared,by using the polyethylene imine(PEI)modified graphene oxide(rGO-PEI)as the photothermal layer and the polarized PVDF(?phase about 91.4%)as the pyroelectric layer.The results of density functional theory(DFT)calculation show that the modification of GO by PEI enhances the light absorption performance of the material(better than that of commercial graphene),which is beneficial to the photothermal conversion;The output power of the typical rGO-PEI/PVDF is 21.3 mW/m~2 at 25 mHz,better than that previously reported.Furthermore,all-weather power generation and instant power supply applications can be realized,through simple"wearable"design of materials.Secondly,based on the concept of self-polarization,an efficient ZnS/self-polarized PVDF-HFP self-powered luminescent material was designed and prepared by water phase separation,by adopting zinc sulfide electroluminescent powder and PVDF-HFP piezoelectric material as raw materials.The results of DFT calculation and experimental evidence show that the S-H hydrogen bond formed between ZnS particles and PVDF-HFP can promote the self-polarized process of PVDF-HFP(the?phase is up to 84%).The luminescent intensity of the self-powered material has a good linear relationship and adjustability with pressure,vibration frequency and ultrasonic power.It has potential applications in the fields of flexible display,complex pattern luminescent display,information anti-counterfeiting and so on.Thirdly,by using the piezoelectric dielectric integrated thin film construction strategy,the films(rGO-PEI/PVDF-HFP)with both piezoelectric and in-situ energy storage were prepared,by selecting the PEI modified GO as the filler(rGO-PEI)and PVDF-HFP as the matrix.High-performance dielectric films can be prepared(the dielectric constant can reach 121 when the rGO-PEI is 10 wt%)by optimizing the filler content,which can convert mechanical deformation into electrical energy and store it in situ(about 1 min).Furthermore,self-powered Raman enhanced substrate materials can be prepared,by coupling the typical functional films with silver nanowire.The prepared substrate can realize double-enhancement of Raman signal(about 10 times)under finger pressing,and can be used for in-situ,on site and rapid detection of pesticide residues on the surface of fruits and vegetables.Fourthly,by adopting the construction strategy of triboelectric dielectric integrated film,on the basis of high dielectric film of rGO-PEI/PVDF-HFP,self-powered Raman enhanced substrate materials based on triboelectricity were designed and prepared,by combining the in-situ formation of binary micro-nanostructures of gold and silver.The substrate generates electricity after friction and can store the electric energy in situ for nearly one minute,which provides enough time for Raman detection.Thereby after simple friction,the substrate can achieve the double-enhanced Raman signal(about 3times)of dye molecules.It is found by FDTD and DFT that the mechanism of double enhancement of Raman signal belongs to physical enhancement.Finally,the ability of the substrate to detect the Raman signal of pollutants in the oxidation environment is demonstrated. |
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