Nanocomposites and nanomaterials

Optical properties of CdTe/CdS QDs in different matrices 
Vorontsov D.S., Khalavka Yu.B., Okrepka G.M. 
Institute of biology, chemistry and bioresources, Yuriy Fedkovych Chernivtsi National University, Kotsjubynskyi St., 2,Chernivtsi-58012, Ukraine 
E-mail: levvoron1@gmail.com

The nanoparticles of the semiconductors are widely known and have many applications due to strong photoluminescence and high “tune” of color. But QDs show a photoluminescence only under high-energy illumination, like UV light, so their photostability (PS) is a key factor for their practical application. Because of many of equipment that can use nanoparticles (e.g. solar battery, concentrators, lasers) requires solid state composites, a search of a matrix that can give to encapsulated QDs high PS and finding of a method of its increasing are important problems of nanochemistry. 
In this work, we report about CdTe/CdS QDs incorporated in different matrices: KH2PO4 (also known as KDP), KBr, BaSO4[1], CaCO3[2]. The KDP:CdTe/CdS and KBr:CdTe/CdS monocrystals were synthesized by the method of slow solvent evaporation from the mixture of a saturated solution of a salt and colloid of CdTe/CdS. BaSO4:CdTe/CdS and CaCO3:CdTe/CdS were obtained by the method of a co-precipitation, and were ground and pressed into the pills. 
Thus, the optical properties of the composites were investigated. It was shown, that matrix of KDP preserved the best PS of incorporated CdTe/CdS nanoparticles. To prove that air oxygen plays a key role in a photooxidation of the nanoparticles we covered all composites with a hermetic hydrophobic shell of the polymer. Was represent that after this the PS of all composites, exclude KDP:CdTe/CdS increase dramatically that is a confirmation of a role of air oxygen.
So, KDP matrix is the best matrix for encapsulation of CdTe/CdS QDs in comparison with other matrices due to their interfacial incorporation, in any occasion, QDs are protected by a matrix which predetermines high photostability of QDs. The key role of oxygen air in a process of photooxidation of nanoparticles was confirmed, as well.

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2.	Zhang Y. et al. High luminescent aqueous CdZnTe QDs incorporated in CaCO3 for excellent color-rendering WLEDs // J. Alloys Compd.–2017.–712.– P. 543-548