Direct synthesis of II–VI compound nanocrystals in polymer matrix

Abstract

The production of II -VI semiconductor compound -polymer matrix nanocomposites by a direct in-situ thermolysis process is described. Metal-thiolate precursor molecules embedded in a polymer matrix decompose by a thermal annealing and the nucleation of semiconductor nanocrystals occurs. It is shown that the nucleation of nanoparticles and the formation of the nanocomposite can be also achieved by laser beam irradiation; this opens the way towards a "lithographic" in-situ nanocomposite production process. A possible growth and nanocomposite formation mechanism, describing the structural and chemical transformation of the precursor molecules, their decomposition and the formation of the nanoparticles, is presented.

Time and Temperature Dependence of CdS Nanoparticles Grown in a Polystyrene Matrix

“…The synthesis of the Cd bis(thiolate) single-source precursor and CdS/polystyrene nanocomposite formation was done using quite standard procedures [10]. Single-source precursors are promising candidates for the generation of nanocomposite materials, because the stoichiometry and the homogeneous distribution of the products inside the polymer matrix are quite easy to control.…”

“…The synthesis of the precursor from dodecanethiol [HS-(CH 2 ) 11 -CH 3 ] and cadmium nitrate [Cd(NO 3 ) 2 ] was performed as reported in [10]. An amount of Cd(NO) 3 and dodecanethiol was solubilized separately in absolute ethanol at a final concentration of 0.1 M and 0.2 M, respectively.…”

“…Therefore, a possible approach to overcome these drawbacks is to grow the QDs directly inside the polymer [9], when the QDs formation is achieved by means of thermal decomposition of the precursor itself. The synthesis of CdS QDs using the thermolytical growth procedure from a singlesource precursor presents some advantages in respect to other common synthetic methods [9][10][11]: the precursor is easy to prepare and stable under normal conditions, its synthesis does not request any highly dangerous or expensive products and the metal and the chalcogenide atoms are in the correct stoichiometric ratio. Another interesting advantage of the combination between thermolytical process and in situ QDs synthesis is the space-selective formation of the nanocrystals using an external laser source [12][13][14][15].…”

Nanostructured Materials Preparation via Condensation Ways

“…The products that are formed are insoluble in common organic solvents as they are inorganic polymers. Thermolysis of zinc, cadmium and nickel dodecanethiolates at 573 K with coordinating trioctylphosphine oxide as the solvent or without a solvent afforded ZnS and CdS nanocrystals with nanoparticle size of 1.5-3.0 nm coated by solvent molecules [413,414] and NiS nanoparticles shaped as plates and rods [415]. Particles with similar size are formed in the thermolysis of AgSC 12 H 25 Àn [416] while in the case of Bi(SC 12 H 25 Àn) 3 , either layered nanostructures [417] or spheres and hexagonal plates are formed [418] as well as Ag(I), Cu(I) and Pb (II) alkanoates [419].…”

Synthesis of CdS/TiO2 nanocomposites by using cadmium thiolate derivatives as unimolecular precursors

“…In this work, we report on a direct in situ synthesis of the nanocomposite – CdS NCs in mesoporous nanocrystalline anatase TiO 2 matrix – based on an innovative unimolecular precursor for CdS, containing both the metal and the non‐metal part: [Cd(SBz) 2 ]MI, where MI is 1‐methylimidazole. In previous works we demonstrated the suitability of cadmium thiolate as a unimolecular precursor for the synthesis of nanometric metal sulfide in a polymer matrix 15 as well as in a mesoporous TiO 2 film 16. Due to their polymeric structure, usually this kind of precursor has a low volatility and is insoluble in typical organic solvents.…”