Laser Induced Lamer Growth Of Uniform PbS Quantum Dots

Because of the significant quantum size effect, PbS quantum dots has a series ofnew physical and chemical properties which are completely different from bodymaterial, such as wideband strong absorption, the quantum confinement effect andexcellent optical performance. It has a wide range of applications, such asoptoelectronic devices and biological detection, etc. A large number of methods havebeen developed to synthesize uniform PbS QDs, wherein the laser method hasgradually become a research hotspot due to its simple operation, environmentalprotection, short experimental period, etc.In this paper, we propose a new preparation method of uniform PbS quantum dotsbased on laser induced LaMer growth–nanosecond laser induced localsupersaturation method to prepare uniform PbS quantum dots. The influencing factorsof PbS QDs size and morphology are examined by comparing the differenttechnologies (heating, millisecond laser, nanosecond laser) to process PbS materialand the different reaction conditions, such as irradiation time, cooling condition, laserparameters. The morphology and phase of the obtained PbS quantum dots arecharacterized by XRD, TEM, PL, ABS, DLS and other testing methods, the formationmechanism of PbS quantum dots prepared by the method is also discussed, that is theirradiation of each initial PbS nanocube in oleic acid by each laser pulse will createlocalized high degree of supersaturation of monomers, which initiates―burstnucleation‖and leads to the separation of nucleation and growth in the homogeneousnucleation process.Then uniform PbS QDs would be produced with the growthmodification of oleic acid. Our strategy towards uniform QDs could be generalized toa wide range of material systems, i.e., chalcogenides.In summary, we report on the realization of uniform crystallization ofnanoparticles by using nanosecond laser irradiation, i.e., a physical method, based onthe LaMer model. More importantly, abundant natural minerals, such as galena, couldalso be adopted as starting materials for laser irradiation in preparing uniform QDs,which paves a way to the most environmentally friendly and convenient massproduction of high-quality uniform QDs.