Preparation And Properties Of Metal Arsenide And Phosphide Colloidal Nanocrystals

Semiconductor nanocrystals have attract attention of many scientists around theworld due to their unique optical properties in the past three decades, due to thedevelopment of nanocrystals synthetic chemistry, semiconductor quantum dots havemade tremendous progress in size, morphology and optical properties of control,growth kinetics of nanocrystals and surface ligand kinetics of nanocrystals, thesurface modification of semiconductor nanocrystals, bandgap engineering and so on.Various semiconductornanocrystals (NCs)(e.g., II VI, IV VI and III V) have abroad application potential in the field of photoelectron and biomedical applicationssuch as in vivo biological imaging, lighting, and optoelectronic devices.Among thesetypes of NCs, tremendous efforts have been made to develop hot-injection synthetictechniques for producing high quality II VI NCs such as highly luminescent CdX (X=S, Se and Te) NCs in the visible spectral region. The II VI NCs becomecommercially available at large scale by the use of stable precursors, such as cadmiumoxide/salts and chalcogen (S, Se and Te) powders, as the replacement for CdMe2andH2X or TMS-X (X=S, Se and Te). In comparison, the colloidal synthesis of metalarsenide and phosphide NCs such as II-V Cd3As2and Cd3P2NCs has laggedsubstantially behind that of their II VI analogues. Up to now, there is limited researchon the colloidal synthesis of metal arsenide and phosphide NCs. In many literatures,TMS-As and TMS-P were used as anion precursors to react with metal salts to prepare arsenide or phosphide containing NCs. However, the precursors, TMS-As andTMS-P which are not only expensive but also lack stability. With respect to materialeconomy and operative convenience comparing to the current workhorse of CdSeNCs, the development of an alternative approach to more controllable preparation ofhigh quality metal arsenide and phosphide NCs with tunable size is of greatimportance.1. The Gas-liquid systerm were established，H3As (or H3P) generated from thereaction between Mg3As2(or Ca3P2) and HCl was used as the arsenic/phosphorsource，the gas was bubbled into Cd(OA)2solution toprepare Cd3As or Cd3P magic–size clusters. In order to study the necessary conditions and the optimum conditionfor the preparation of magic–size clusters，and to deepen the understanding ofpreparation system by adjusting the reaction parameters. With the help of the activereaction precursors，the Cd3As/ZnS and Cd3P/ZnS core/shell NCs were formation toImprove the fluorescent efficiency and stability of the materials.2. The size-tunable and shape-cotrolled Cd3As2NCs were prepared by usingCd3As MSCs as single-source precursor by using hot-injection synthetic techniques.The study on growth process of Cd3As2NCs reveals the fact that size of NCs isdetermined by the reaction temperature. The Characterization of photoelectricresponse behavior indicated the application potential of Cd3As2NCs in the field ofphotovoltaic. Thin-film solar cell device were set up by using Cd3As2NCs asphotoabsortion material, after testing, the solar cell device we build has aphotoelectric conversion efficiency of3.75%.3. The size-tunable and shape-cotrolled Cd3P2NCs were prepared by usingCd3P MSCs as single-source precursor with hot-injection synthetic techniques. Thereaction mechanism of Cd3P2NCs growth has been studied systematically. InP andInAs magic-size clusters were prepared based on the method mentioned earlier inthis papper, the clusters were used to prepare InP and InAs NCs as single-sourceprecursor. The structure and characterization of the composition and opticalproperties have been taken, the ZnS shell NCs were used to improve the fluorescent efficiency and stability of the InAs and InP NCs.4. Metal arsenide and phosphide NCs such as MoP and Ni2P NCs weresuccessfully prepared by using generated H3As and H3P as arsenic and phosphorussource by aid of the gas-liquid two phase synthetic method. The morphology, size,structure and composition of the resulting these NCs have been characterzed. The asprepared MoP and Ni2P NCs have been characterized as electrocatalysts for thehydrogen-evolution reaction (HER), the testing efforts is outstanding. At extent work,the Cu based metal arsenide semiconductor Cu3CdSnAs3NCs with variouscompostion and shapes were also prepared by current synthetic technique. To sudy theoptoelectronic of these NCs, a thin-film solar cell device was set up by usingCu3CdSnAs3NCs as photoabsortion material. Experimental result indicated that aconversion efficiency can reach up to3.38%，indicating its potential application in thefield of photovoltaic.