| All inorganic cesium lead halide（CsPbX3,X=Cl,Br or I）perovskite nanocrystals（PNCs）,as a novel colloidal nanocrystals,have excellent photoelectric properties,including high photo-luminescence quantum yield（PLQY）,narrow full width at half-maximum（FWHM）and adjustable color in the whole visible and infrared regions.At the same time,it has unique carrier separation characteristics,high charge carrier mobility and long carrier diffusion length.Based on these excellent properties,CsPbX3PNCshas been widely studied and applied in the fields of solar cells,light-emitting diodes（LEDs）,photodetectors（PDs）,lasers and photocatalysis.However,the CsPbX3 PNCsstill suffer from structural instability against moisture,oxygen,heat,and light interference,their application in the analytical detection of target substances in aqueous solutions is rarely studied.Recently,a method to synthesize perovskites with high water stability using an aqueous emulsion method has been reported,but the synthesis method is complicated and difficult to operate.Therefore,how to further explore the synthesis method of water-soluble perovskites,and at the same time apply water-soluble perovskites to the analysis and detection of substances in aqueous solutions,has received extensive attention from researchers.In this paper,water-soluble cesium lead halide perovskite nanocrystals are taken as the research object.On the one hand,to simplify the synthesis method of water-soluble cesium lead halide perovskite by aqueous emulsion method,and to improve the stability and luminescence of the perovskite synthesized by this method.performance.On the other hand,the special luminescence properties of water-soluble cesium-lead bromide perovskite and bromoiodocesium-lead hybrid perovskite were used to explore its application in the analysis and detection of substances in aqueous solution.Based on the above purposes,water-soluble cesium-lead bromide perovskites and bromoiodocesium-lead hybrid perovskites were synthesized and applied to the analysis and detection of heavy metal ions and biological small molecules.The specific research contents are as follows:1.This paper,we synthesized water-soluble cesium lead bromide perovskite nanocrystals emitting strong green fluorescence by referring to the water-phase emulsion method reported in the literature through appropriate modification.The maximum emission wavelength of this PNCslocated at 525 nm,with a very narrow half-peak width.The UV-vis absorption spectrum has obvious characteristic absorption peak at 510 nm.Since folic acid（FA）can quenched the fluorescence of the PNCs,and the fluorescence intensity of the PNCsshows a linear decrease when the concentration of FA is in the range of 10-800μM.Based on this phenomenon,a fast,highly selective and visual quantitative method was developed for the detection of FA in aqueous solution using this PNCsas fluorescent probe.The detection limit of the method was 1.695μM.2.In this paper,CsPbBr3/Cs4PbBr6 PNCswas synthesized by water-phase emulsion method,and then a series of bromo-iodide,cesium and lead hybrid perovskite nanocrystals（CsPb（Br/I）3 PNCs）which emitting from green to red fluorescence were synthesized by anion exchange method.The relationship between the maximum emission wavelength of the PNCsand the concentration of KI was investigated.Then,the interaction between CsPb（Br/I）3 PNCsand biomolecules was further explored.It was found that ascorbic acid（Vc）can enhance the fluorescence of CsPb（Br/I）3 PNCs,and using CsPb（Br/I）3 PNCswith large emission wavelength as the fluorescent probe has better selectivity to Vc.CsPb（Br/I）3 PNCswith a maximum emission wavelength of about635 nm was selected as a fluorescence probe for linear detection of Vc.When the concentration of Vc was in the range of 0.01 to 50μM,the fluorescence intensity of CsPb（Br/I）3 PNCswas linearly enhanced.Based on this phenomenon,a fast and selective method for Vc detection was established.3.In this paper,CsPb（Br/I）3 PNCswas synthesized with reference to the synthesis method in 2.Next,we used this PNCsas fluorescence probe to explore the interaction between the PNCsand metal ions in aqueous solution.It was found that Hg2+can quench the fluorescence of the PNCsand make its maximum emission wavelength blue shift.Then,the quantitative linear and visual dual-signal detection of Hg2+by the PNCswith different emission wavelengths（551 nm,591 nm and 617 nm）was further studied.The results showed that the fluorescence quenching rate（I0/I）and emission wavelength displacement（Δλ）had a good linear relationship with the concentration of Hg2+.The linear range of perovskites with different emission wavelengths is different.In particular,591nm and 617 nm probes have excellent visual detection effect for Hg2+at low concentration,which can achieve fast visual quantitative detection of within the ultra-small concentration range. |
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