Preparation And Fluorescence Properties Of SiO₂ Coated Inorganic Perovskite Quantum Dot

In recent years,with the continuous growth of energy demand,the gradual decrease of traditional energy sources and the increasingly serious problem of environmental pollution,the global attention to new energy materials has been increasing.As a new type of energy material,chalcogenide has received widespread attention and research in the field of optoelectronics,and its excellent optoelectronic properties and adjustable band gap bring broad prospects for the application of solar cells,light-emitting diodes and other optoelectronic devices.Among them,metal halide chalcogenides have great potential for application in photovoltaic,photovoltaic and photocatalytic applications due to their superior light absorption,high carrier mobility and long-range stability.However,despite their obvious performance advantages,metal halide chalcogenides still face a few challenges in practical applications.For example,environmental stability,toxicity issues and exchange reactions of halogen ions.To overcome these challenges while enhancing the stability and optoelectronic properties of metal halide chalcogenide materials,the modification of metal halide chalcogenide surfaces using an extremely hermetic and completely transparent silica as a coating is an excellent solution.In this paper,Cs Pb Br₃@Si O₂ quantum dots（QDs）with a core-shell structure were synthesised using（3-aminopropyl）triethoxysilane as a synthetic precursor to silica coating by thermal injection in a single step without transfer,The method is simple,inexpensive,and highly productive.The samples obtained by this method were characterised by X-ray diffraction,transmission electron microscopy,high-resolution transmission electron microscopy and energy dispersive X-ray spectroscopy,which demonstrated that Cs Pb Br₃@Si O₂ QDs with a core-shell structure were successfully prepared with good crystallinity.The Cs Pb Br₃ QDs and Cs Pb Br₃@Si O₂ QDs were tested for fluorescence lifetime.The results were fitted with a double exponential function,showing that the core-shell structure of Cs Pb Br₃@Si O₂ QDs has a longer fluorescence lifetime due to the silica coating which effectively passivates the surface defects of Cs Pb Br₃ QDs and reduces their non-radiative jump probability.In addition,the variable temperature fluorescence spectra of the synthesized samples from 80-400 K revealed that Cs Pb Br₃@Si O₂ QDs have higher exciton binding energy,lower non-uniform spreading and lower electron-phonon coupling coefficient compared with Cs Pb Br₃ QDs,indicating that the silica coating can make Cs Pb Br₃ QDs have lower electron loss,more The Cs Pb Br₃ QDs have excellent optical properties such as lower electron loss and more stable lattice structure.The Cs Pb Br₃ QDs and Cs Pb Br₃@Si O₂ QDs were made into the same size electrode material,and cyclic voltammetry,constant current charge/discharge and AC impedance analysis tests were carried out on both.Comparison of the test images shows that both Cs Pb Br₃and Cs Pb Br₃@Si O₂ electrodes exhibit significant redox reactions,but the Cs Pb Br₃@Si O₂electrode has a larger cyclic voltammetric integration area,longer charge/discharge times and lower impedance,demonstrating that the silica coating gives the Cs Pb Br₃ QDs superior capacitive performance.The results of the fluorescence lifetime of Cs Pb Br₃@Si O₂ QDs and the results of the variable temperature fluorescence analysis were clearly and visually demonstrated by electrochemical tests.