Study On Synthesis,Photoelectric Properties Of Water-soluble Lead Halide Perovskite Nanocrystallines And Its Biological Imaging Application

Lead halide perovskite,especially nano-scale lead halide perovskite,has exhibits outstanding optical and electronic properties comepared with traditional semiconductor nanomaterias,such as broad spectral tenability,extremely narrow full width at half maxima,high photoluminescence quantum yields?PLQYs?,and high light absorption coefficient.In recent years,it has become one of the hottest topics in the field of chemistry and materials.Great progress has been made in the investigation of perovskite materials,including their structure,composition,synthesis and properties.Based on their excellent optical and electrical properties,lead halide perovskite have been widely applied photoelectronics,such as solar cells,light-emitting diodes,backlight display,lasers,and also made them show great application prospect in the field of biological analysis.However,the poor stability of lead halide perovskite is a great challenge both for its photoelectric applications and for its biological analysis applications.Lead halide perovskite is a typical ionic crystal,its internal atoms and between its surface and ligand are bound in the form of ionic bonds.Therefore,its crystal structure degrades rapidly under the conditions of polar solvents?such as water,ethanol?,air,light and heat treatment,leading to fluorescence quenching and the release of highly toxic lead ions,which seriously limits its practical application.Therefore,it is of great significance to improve the stability of lead halide perovskite in deeper practical application and to realize its commercialization.The specific research contents are summarized as follows:1.Ultra-stable and hydrophilic CsPbBr₃/mPEG-NH₂ nanocrystals with enhanced aqueous fluorescence for cell imagingA highly biocompatible functional polymer,methoxypolyethylene glycol amine?mPEG-NH₂?,was chosen as the capping agent for successful synthesis of mPEG-NH₂-capped CsPbBr₃ nanocrystals?CsPbBr₃/mPEG-NH₂ NCs?.The obtained NCs were demonstrated to be superior with their water resistance,water solubility,single particle dispersion,thermal stability and biocompatibility.Contrary to previous studies,the fluorescence intensity of product was significantly enhanced after dispersing in water for a period of time.Correspondingly,the PLQYs increased from the initial 16%to 41%a week later.The water solubility of product has been greatly improved duo to the hydrophilic properties of mPEG-NH₂.At the same time,the relative PL intensity of CsPbBr₃/mPEG-NH₂ NCs could maintain 80%of its original value after heated to 100?C.Benefited from their excellent water resistance,superior water solubility and high biocompatibility,the CsPbBr₃/mPEG-NH₂ NCs could be directly used as luminescence probes for cells imaging.2.Highly Stable CsPbBr₃/APTES-Oxide Nanocomposites:Anchoring Perovskite Quantum Dots on Oxide via Covalent Interactionwe successfully synthesized?3-amino-propyl?-triethoxysilane?APTES?capped CsPbX₃ quantum dots?CsPbX₃/APTES QDs?using APTES as the capping ligand by precipitation-dissolution method under ambient conditions.Then,the CsPbBr₃/APTES-SiO₂ nanocomposites were prepared via using CsPbBr₃/APTES QDs as silylating reagent to anchor onto the surface of SiO₂ have been prepared for the first time.The as-prepared CsPbBr₃/APTES QDs with a PLQYs of 40.22%excellent stability in ethanol as a result of the strong steric hindrance and hydrolysis properties of APTES,which prevent ethanol from reaching and reacting with the core of QDs.Interesingly,compared to CsPbBr₃/APTES QDs,CsPbBr₃/APTES-SiO₂nanocomposites not only retain almost all the PLQYs of the original QDs,but also exhibited better resistance to ethanol and greatly improved thermal stability.Moreover,the universality of this strategy is proved by using the same method to fabricate CsPbBr₃/APTES-TiO₂ nanocomposites.