Study On The Synthesis Of Quantum Dots By Microfluidic Method

With the development of materials science and engineering,nanomaterials with specific functions have shown high potential in applications of biochemistry,photoelectric materials and green energy.Functional nanomaterials can be prepared by emulsion,vapor deposition,dispersion and other methods,and the morphology and structure of nanoparticles are important factors that determine the properties of the materials.Microfluidic technology provides the reaction in micron level reactors and has the characteristics of continuous phase flow and microscale production.Compared with traditional kettle reactors,it can effectively improve heat transfer and mass transfer efficiency of reactants,speed up reaction speed,improve product uniformity,and ensure accurate control of the reaction process.The advantages of microfluidic technology in heterogeneous reactant mixing and continuous preparation are conducive to the study of nucleation and growth process of nanomaterials.Therefore,microfluidic technology is considered as an effective platform for mechanism research and large-scale preparation of nanomaterials.In this work,we investigated the effects of microfluidic reactions on the controlled synthesis of the size,morphology and structure of semiconductor nanocrystals,and investigated the mechanism of microfluidic-induced growth of nanocrystals.First,we report the facile synthesis of quantum-confined CsPbBr₃ nanowires(NWs)by using a continuous-flow microfluidic reactor.The optimized reaction temperature is around 50?,and one“synthesis run”by microfluidics requires only ten minutes.The study reveals that the formation of CsPbBr₃ NWs takes place by a hybrid growth mechanism of seed-mediated growth and oriented attachment growth.This microfluidic approach benefits the alignment of the short quantum-confined NWs and promotes their oriented attachment to form long NWs,while conventional flask synthesis results in large and irregular nanorods under the same reaction conditions.This work not only provides a new synthetic path for the preparation of Cs Pb X₃ NWs,but also sheds light on the fundamental study of Cs Pb X₃ NWs.Secondly,we report the synthesis of CdSe/CdS and CdSe/Zn S core-shell heterojunction quantum dots by using a continuous-flow microfluidic reactor.The study reveals with the increase of temperature,the growth rate of crystal shell was accelerated,and the luminescence peak gradually shifted to red.Compared with the traditional vessel stirring process,the microfluidic reactor provides a more stable and controllable reaction environment.The prepared CdSe/CdS quantum dot display well-ordered morphology and high fluorescence quantum efficiency.The improved optical performance of QDs benefits the design and manufacture of QDs based white-light LEDs.