Photoinduced Charge Transfer Dynamics Of Perovskite Quantum Dots

All-inorganic perovskite quantum dots are characterized by a series of excellent photoelectric properties,such as high quantum yield,tunable emission wavelength and high electron and hole mobility.It has great application value in display,light-emitting diodes,solar cells,photodetectors and micro/nano lasers.At present,the preparation of these materials is usually limited to heating,organic solvents and other reaction conditions.Synthetic methods with environmental protection,convenient and adjustable components and ability to mass production are absent.In addition,excellent photoelectric properties of perovskite quantum dots contribute to their application in photocatalytic reaction as photosensitizers/catalysts.However,research in this field is extremely rare.In order to solve above problems,a novel solvent-free mechanochemical method was developed in this study.Through ball-milling for initial raw materials with different ratios,a series of high-quality perovskite quantum dots with tunable emission wavelengths were obtained as convenient as a heap of Lego blocks.Moreover,the photoexcited charge transfer between perovskite quantum dots and triethylamine was studied using time-resolved fluorescence spectroscopy.It was expected to expand its application in photocatalysis.The research work was divided into two parts:1.With mechanochemical method,cesium lead halide perovskite quantum dots with high quality,tunable components and emission wavelengths were successfully synthesized by changing the ratio of the initial components.The effects of ball-milling rate,ball-milling time,ball-to-powder weight ratio and ligand on the synthesis of quantum dots were investigated and optimized.The results showed that perovskite could not be produced at a too low ball-milling rate.Long ball-milling time resulted in not obvious changes in the size of quantum dots.Ball-to-powder weight ratio presented no apparent effect on the shape and size of quantum dots.The shape of the products was greatly affected by the type and quantity of ligands added.2.The charge transfer of the prepared inorganic perovskite quantum dots after optical excitation was investigated by time-resolved spectroscopy.Fluorescence lifetime test showed that triethylamine molecules could quench the fluorescence of CsPbBr₃ quantum dots,which belonged to dynamic quenching with a hole transfer rateis1.1¹.2×10¹⁰M^-1s^-1.Ultravioletphotoelectronspectroscopyand electrochemical methods also confirmed the charge transfer between quantum dots and organic molecules.A deep understanding of this process will effectively expand the application of perovskite quantum dots as a novel photoelectric material in photocatalysis and optoelectronic devices.