| Semiconductor nanocrystals are drawing many researchers large interest because of their quantum confinement effect and unique optical properties which make semiconductor nanocrystals widely used in photoelectric devices,bio-labeling,solar cells,catalysis and so on.In the past thirty years,II-VI group nanocrystals have been systematicly and comprehensively researched.However,the large-scal application of II-VI group nanocrystals is restricted,because cadmiun or mercury is toxic heavy mental.Indium phosphide?In P?semiconductor nanocrystals is one of the most bright nanocrystals in thoes semiconductor nanocrystals,which is size-tunable in the visible and near-infrared window and cadmiun-free and low toxicity.For those,In P has been identified as an ideal candidate to replace II-VI group nanocrystals.Generally,the mostcommonphosphorusprecursortosynthetizeInPnanocrystalsis tris?trimethylsiyl?phosphine?P?SiMe3?3?.However,P?SiMe3?3 is expensive and poor stability.According to the newly researches,tris?dimethylamino?phosphine?P[N?CH3?2]3?is an economic,safe and efficient phosphorus precursor which can match with P?SiMe3?3 at optical properties for InP nanocrystals.In this paper,we systematicly research the synthesis and optical properties of InP nanocrystals.InP nanocrystals are synthesized by high temperature thermal injection with a new type of phosphorus precursor:P[N?CH3?2]3 which is safe and economical.Besides,we research the parameters of the reaction such as the concentration of Oleylamine?OLA?and the ratio of precursors to determine the optimal value of each reaction parameter.According this,we have a better understanding of the role of various reaction parameters in the synthesis of InP nanocrystals with new phosphorus sources.On the basis of the research on parameters,the size of In P nanocrystals can be adjusted by means of temperature regulation,so we synthesize high quality InP nanocrystals by gradually speeding temperature control,realized the adjustable size from 460 nm to 620 nm of In P nanocrystals.We also expande the emission range of InP nanocrystals and enhance the thermal stability and chemical stability of nanocrystals by doping Ag ions into InP nanocrystals.In this paper,we successfully synthesize Ag:InP nanocrystals by the method of growth doping.By adjusting the size of In P nanocrystals,we realize size-turnable emission range of Ag:InP nanocrystals from 640 nm to 1000 nm.We also study the influence of doping concentration and doping temperature for the fluorescence quantum efficiency of Ag:In P nanocrystals.With the increase of Ag+doping concentration,the fluorescence quantum efficiency of Ag:In P nanocrystals increases first and then decreases;with the increase of Ag+doping temperature,the fluorescence quantum efficiency of Ag:In P nanocrystals increases first and then decreases.When the doping concentration of Ag ion is 5%and the doping temperature is 160?,the photoluminescence properties of the nanocrystal is optimal and the fluorescence efficiency can reach 8%.In order to improve the fluorescence quantum efficiency and stability of Ag:InP nanocrystals,the ZnS shells are coated on the surface of Ag:In P nanocrystals.By this,Ag:In P nanocrystal fluorescence quantum efficiency is increased from 8%to 45%,whoes stability is improved obviously.So Ag:InP/ZnS nanocrystals can be widely used in medical imaging and bio-labeling. |
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