Photothermal Stability Of Silica-coated CsPbBr₃ Perovskite Nanocrystals

In recent years,due to the many outstanding advantages of halide perovskite materials in optics,it has been widely used in various optical converter devices,but due to its poor stability in the external environment such as water,high temperature,oxygen and ultraviolet light,it is easy to decompose and even fluorescence quenching,which seriously hinders its practical application and commercial development.The CsPbBr₃/SiO₂ composites are prepared by a two-step synthesis method.In the first step,CsPbBr₃ PNCs are synthesized according to the solvothermal method.In the second step,at room temperature,tetramethoxysilane(TMOS)is added as a single-molecule precursor,and then ammonia is added to hydrolyze and condense to form silica,and CsPbBr₃ PNCs are coated to form composites.The elemental composition and the groups contained in the synthesized composites were analyzed,and the successful preparation of the composites of silica-coated CsPbBr₃ PNCs is confirmed.Compared with pure CsPbBr₃ PNCs,the CsPbBr₃/SiO₂ composites exhibit a narrower bandwidth(20.2±0.26 nm)and exhibit superior color purity,which provides a higher degree of color accuracy for PNC-based lighting and displays.During the heating process,the emission wavelength(518 nm)of the CsPbBr₃/SiO₂composites does not shift significantly,which indicates that it has relatively stable optical properties.To study the kinetics of carrier recombination,time-resolved PL measurements are performed on CsPbBr₃ PNCs and CsPbBr₃/SiO₂ composites.The CsPbBr₃/SiO₂composites exhibit relatively long average lifetimes,which can be attributed to the passivation of the surface dangling bonds of CsPbBr₃ PNCs reduced by silica,thereby inhibiting the nonradiative recombination pathway.In addition,the CsPbBr₃/SiO₂composites have high exciton binding energy and average optical phonon energy,which means that the excitons have high stability and relatively weak exciton recombination nonradiative transitions.The silica-coated CsPbBr₃ PNCs not only maintain the unique optical properties of pure CsPbBr₃ PNCs,but also have significantly enhanced stability in high temperature,hyperthermia,and polar solvents.Through the successful preparation of composite materials and related research,it was found that halide perovskite composites have great potential for development in lighting,display and other optoelectronic devices.