Nanocomposites and Nanomaterials

Synthesis and optical properties of mesomorphic glasses with core-shell semiconductor nanoparticles.
Mirnaya T.1, Yaremchuk G.1, Klimusheva G.2
1 V.I.Vernadskii Institute of General and Inorganic Chemistry of the NAS of Ukraine, Prospekt Palladina, 32-34, Kyiv-03142, Ukraine. 
E-mail:yaremchuk@ionc.kiev.ua 
2 Institute of Physics of the NAS of Ukraine, Prospect Nauki, 46, Kyiv-03039, Ukraine.

An extensive experimental material of our studies on the synthesis, optical and nonlinear optical properties of mesomorphic composites with heteronanoparticles of metal chalcogenides of the core / shell type (CdSe/CdS, CdSe/ZnS, CdSe/PbS, CdSe/ZnSe, CdSe/PbSe, ZnSe/PbSe) is systematized. Optical nanocomposites based on caprilates of cadmium, zinc and lead with these nanoparticles were obtained and the possibility of fine-tuning their optical properties by changing the composition of the liquid crystal matrix and synthesis conditions was shown. The synthesis of semiconductor nanoparticles in ionic liquid crystals of metal alkanoates allows one to obtain nanoparticles, the size of which, depending on the ionic potential of the matrix, can vary from 1 nm to 5 nm [1].
Nanocomposites with core - shell  semiconductor nanoparticles have promise in creating novel nonlinear optical materials, light-emitting diodes on the new generation, highly efficient luminescent marks etc.
The synthesis of nanoparticles was carried out in liquid crystal systems using various methods, namely sequential methods (fusion of composites with mononanoparticles) and parallel (co-precipitation / reduction) synthesis.
Using electron microscopy and optical spectroscopy, the formation of semiconductor-semiconductor core-shell heterostructures for nanoparticles has been established.
It was shown that nanocomposites with heteronanoparticles are characterized by a more intense exciton fluorescence band than composites with individual nanoparticles. Using the Z-scan method, it was found that optical heteronanocomposites have a fast nonlinear optical response and relatively high values of the third-order nonlinear optical susceptibility.

1.	Klimusheva G., Mirnaya T. and Garbovskiy Yu. Versatile nonlinear-optical materials based on mesomorphic metal alkanoates: design, properties, and applications // Liquid Crystals Reviews.- 2015.- 3, No.1.- P.28-57.