| Perovskite is an emerging class of semiconductor materials that holds significant promise for applications in third-generation solar cells,luminescence,X-ray detection,etc.Perovskite quantum dots have outstanding optical properties,such as very high quantum yield,tunable emission and narrow half-peak width,which can be widely used in fluorescence detection,medical analysis and other fields.Rhodamine B is widely used in food dyeing,colored glass,and laser materials due to its good stability and high-cost performance.With industrial discharge,it is widely present in industrial wastewater,which poses a severe hazard to human health and the ecological environment.The traditional detection methods are cumbersome in operation,high in cost,and low in sensitivity.The fluorescence detection method based on quantum dots has the advantages of easy operation,low detection limit,and good selectivity and has been applied to monitor various target substances.The luminescence efficiency of perovskite quantum dots is higher than that of conventional quantum dots,and its fluorescence half-peak width is narrower,and it can also modulate its fluorescence emission peak by changing its composition,so it has significant advantages in fluorescence detection.However,perovskite quantum dots have solid ionic properties.They are prone to structural distortion and degradation in polar solvents such as water,leading to fluorescence quenching,which limits their application for fluorescence detection in aqueous solutions.Therefore,it is essential to study how to obtain perovskite quantum dots with high stability and tunable luminescence peaks through surface modification and composition modulation to expand their applications in fluorescence detection.In this work,an all-inorganic perovskite quantum dot was synthesized by a ligand-assisted reprecipitation method,and the surface modification of the synthesized perovskite quantum dots was performed by using different silicon sources to make them stably dispersed in polar solvents.The fluorescence properties were tuned by changing the synthesis temperature and halogen ratio methods.The encapsulation of the perovskite quantum dots by polymer was achieved by the electrostatic spinning method,and the polymer gave the quantum dots hydrophobic and soft properties.The nanofibers membranes containing perovskite quantum dots sensitively detected the rhodamine B content in an aqueous solution,and this method is characterized by good selectivity,low detection limit and recyclability.The main studies are as follows:（1）Perovskite CsPbBr3 quantum dots were synthesized by using ligand-assisted reprecipitation method with oleic acid and oleylamine as ligands,and CsPbBr3@Si O2 composite quantum dots were synthesized by using（3-aminopropyl）triethoxysilane（APTES）,tetraethyl orthosilicate（TEOS）,and tetramethoxysilane（TMOS）as silicon sources,respectively.The morphological characteristics and fluorescence properties were studied by using various characterization tools to determine the best silicon source TMOS,through which the surface modification was carried out to obtain highly stable conforming quantum dots,which have a fluorescence quantum yield of 85.5%silicon oxide coated quantum dots have good stability in water,oxygen and polar solvents,and also maintain good stability in UV light,which can still be irradiated in UV light for two months after The initial intensity of 63.50%was maintained after two months of UV irradiation.（2）Using TMOS as the silicon source,the low-temperature synthesis of CsPbBr3@Si O2 by varying the synthesis temperature in the range of 0℃～40℃and the synthesis of Cs Pb X3@Si O2by varying the ratio of halogen Cl and Br,the modulation of the luminescence peaks of the perovskite quantum dots was achieved,and the performance analysis was performed by using the characterization method.The luminescence peak positions of the temperature-controlled synthesized composite CsPbBr3@Si O2 quantum dots were 476 nm,503 nm,515 nm,522 nm,and 533 nm at temperatures from 0℃to 40℃,and the corresponding half-peak widths were27.81 nm,23.52 nm,18.50 nm,19.85 nm,and 28.30 nm,respectively;by changing the halogen ratio the composite quantum dots were synthesized,the luminescence peak positions were 520nm,508 nm,493 nm,460 nm,431 nm,411 nm,400 nm,corresponding to the half-peak widths of 18.50 nm,19.56 nm,47.46 nm,17.43 nm when the percentage of Cl element was 0%,10%,30%,50%,70%,90%and 100%,respectively,The luminescence was regulated from the green to the blue region,and the synthesized Cs Pb X3@Si O2 could be stably dispersed in water with good stability.（3）The luminescence peak of Cs Pb X3/PVDF fibers could be achieved by adjusting the composition of Cs Pb X3 QDs or the luminescence band gap,where the luminescence peak of Cs Pb Cl3/PVDF fibers was at 429 nm and that of CsPbBr3/PVDF fibers was at 520 nm.The fluorescence quantum yield of the prepared CsPbBr3/PVDF was as high as 78.20%.The peak fluorescence intensity of the synthesized CsPbBr3/PVDF composite structure remained above 78%of the initial intensity after 20 days of water immersion due to the hydrophobicity imparted by PVDF to the perovskite quantum dots.The low concentration and selective detection of rhodamine B can be achieved by electrostatic spinning Cs Pb X3/PVDF nanofibers membranes,and the fluorescence intensity of the nanofibers membrane and rhodamine B showed linear variation with high fit when the concentration of rhodamine B was in the range of 1～5μg/m L.Moreover,the nanofibers membrane was durable and recyclable as a fluorescence detection material,and it could still maintain the initial fluorescence value after 10 washing cycles of water62%,showing its great potential for fluorescence detection applications. |
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