Controlled Synthesis Of Size-Tunable And Nearly Monodisperse Inp Nanocrystals

Nanomaterials with the size range from one nanometer to one hundred nanometers in at least one dimension preforms remarkable size-dependent properties.Semiconductor quantum dots(QDs)as one of the most representative nanomaterials with their sizes in quantum confinement regime show somewhat distinct size-dependent chemical and physical properties.As for,?-VI quantum dots such as cadmium selenide(Cd Se)have been widely commercialized.QDs behave size-tunable emission and intrinsically high color purity,which vender them to be the most ideal materials in display industry.More than that,the next generation display technology,active-motivated quantum dots light-emission diode(Q-LED),has rapid development.Cd Se-based quantum dots(QDs)are the only system that can be synthesized with nearly ideal optical properties in the entire quantum-confined size regime.However,Cd is of considerable environmental concerns for general public,and In P QDs are regarded as the most promising Cd/Pb-free alternatives.Since In P QDs have similar bandgap and photoluminence peak position with Cd Se QDs,their emission can cover the whole visible spectra.Hence,In P QDs are recognized as the most promising alternative to Cd-based materials.While the synthetic chemistry of In P QDs and Cd Se QDs started in almost the same time,the progress in synthesis of In P QDs lags much behind.The thesis aims to uncover the some key points dictating the synthesis of indium phosphide quantum dots and propose new synthetic strategy to achieve the synthetic control of indium phosphide nanocrystals.Here we reviewed the reaction mechanism of tri-n-octylphosphine(TOP)in the synthesis of In P QDs.Then we demonstrated that TOP has strong interaction to indium fatty acid salts.After formation of the In-TOP complex between indium fatty acid salts and TOP,bonding between carboxylate groups and In ions becomes much weaker and likely switches from bidentate to monodentate.We achieved controlled synthesis employing In-TOP coordination compound as precursor reacting with tris(trimethylsilyl)phosphine((TMS)₃P).Further,In P clusters in different size range were synthesized.After some qualitative experiments,we concluded that in the presence of TOP,the chemical properties of In P clusters intrinsically changed.The TOP-cluster proforms extrmely stable at?0^oC but proper activity at elevated temperature.Employing In P cluster as single precursor,we reduce the reactivity of anion precursor in the synthesis of In P QDs and successfully synthesiz high quality In P QDs using a hot-injection approach.Since fixation of anion precursor in the clusters,the volatilization of(TMS)₃P can be avoided in the synthesis of In P QDs which usually proceeds at elevated temperature.Therefore,the conversion(TMS)₃P should be 100%in this strategy.We manifested that injecting In P TOP-cluster at elevated temperature facilitates the formation of monodisperse In P QDs through the so-called self-focusing of size distribution.Then,refering to the layer-by-layer growth in synthesizing Cd Se QDs,we employed that In P TOP-cluster as single precursor to extend the size range of In P QDs with their absorption peak covering most part of visible window(between?480-660 nm).