Preparation Of CsPb₂Br₅/CsPbBr₃ Composite Materials And Research On Metal Ion Sensing

Cs-Pb-Br halide perovskite has been widely used in luminescent devices,solar cells,light detectors and lasers due to its advantages of strong fluorescence emission,narrow half-peak width and high fluorescence quantum yield.At present,CsPbBr₃ is the most studied perovskite halide in Cs-Pb-Br system,with excellent fluorescence characteristics and a clear fluorescence mechanism.However,CsPbBr₃ is an ionic compound whose structure is easily destroyed in the aqueous phase.How to improve the stability of CsPbBr₃ is one of the urgent need to address the problem.Therefore,the researchers turned their attention to other materials in the Cs-Pb-Br halide perovskite system.CsPb₂Br₅ was featured in the perovskite field due to its higher chemical stability and excellent photoelectric performance.However,the commonly used methods for the synthesis of perovskite often choose toluene,hexane and N,N-dimethylformamide?DMF?and other organic reagents,which are relatively toxic and volatile to the body and the environment.?1?CsPb₂Br₅/CsPbBr₃ composites were prepared and their properties were characterized.Ultra-pure water and absolute ethanol were selected as solvents,and Pb-MOF was used as the lead source,and cesium bromide?CsBr?was used as the cesium source.The CsPb₂Br₅/CsPbBr₃composites with high fluorescence intensity were prepared by ultrasonic radiation method.Due to their straightforward synthesis process and environmentally friendly synthetic methods for commercial mass production.The reaction mechanism of CsPb₂Br₅/CsPbBr₃ composites was analyzed and their fluorescence mechanism was determined.At the same time,the water phase stability and thermal stability of the composites indicate that the CsPb₂Br₅/CsPbBr₃ composites have good structural stability.These excellent properties make the composites have a wider application prospect in terms of optoelectronics.?2?The CsPb₂Br₅/CsPbBr₃ composites were used as fluorescent probes,which were applied to the detection of common metal ions in aqueous solution,and their fluorescence sensing mechanism were analyzed.Among them,CsPb₂Br₅/CsPbBr₃ composites have obvious fluorescence quenching effect on Fe³⁺,the detection range is 0.5×10^-4-10×10^-4 M,the linear fitting correlation coefficient is 0.99174.Fe³⁺interacts with the ligands on the surface of the composites to increase its surface defects,inhibit radiation-free transitions,and finally cause fluorescence quenching.At the same time,the CsPb₂Br₅/CsPbBr₃ composites have a fluorescence enhancement effect on K⁺with a detection range of 1×10^-9-100×10^-9 M,a linear fitting correlation coefficient of 0.99878.Its fluorescence enhancement mechanism is that K⁺can passivate the surface of perovskite materials,significantly reduce light-induced ion migration,improve its stability and enhance fluorescence intensity.