The dissertation is devoted to the determination, stabilization, and improvement of optical and scintillation properties of halide perovskite nanocrystals CsPbX3 (Х= Cl, Br, I) in polymer composite materials for further practical application. New chemical approaches have been developed to create nano-structured composite materials with luminescence (370-510 nm) based on CsPbX3 and various polymers, the optimal concentrations of nanocrystals in composites have been determined.
The first chapter shows the analysis of literary sources, which show the need for more detailed research on the stabilization of CsPbX3 (Х= Cl, Br, I) nanocrystals in polymer materials and the determination of their luminescent and scintillation properties. For this purpose, such basic tasks as the development of the method of obtaining CsPbX3 nanocrystals, the adaptation of the methods of embedding of nanocrystals into polymers, the determination of optimal concentrations, the study of the luminescent properties of materials, the estimation of the influence of external factors on the stability of nanocrystals, and the determination of the scintillation parameters of composite materials were defined.
In the second chapter adapted and developed methods of obtaining nanocrystals and composite materials are described, and the regularities of embedding nanocrystals into polymers are determined. The behavior of polymeric materials in such solvents as water, toluene, and chloroform was revealed. The conducted experi-ment showed that chloroform damages the polymer structure, therefore it is not suitable for the production of composite materials.
In the third section colloidal solutions of CsPbCl3, CsPbBrCl2, CsPbClBr2, CsP-bBr3, CsPbIBr2, CsPbBrI2 nanocrystals with intense luminescence, which has max-ima at 406 nm, 435 nm, 488 nm, 512 nm, 530 nm, and 534 nm, were obtained. Measurements of optical properties showed that the stability of luminescence changes due to agglomeration, degradation, deposition, and leaching of nanocrystals. Agglomeration causes a shift of the luminescence maximum to the red range, and precipitation and degradation decrease the intensity due to a decrease in the number of crystals in the solution.
In the fourth chapter optimal concentrations of perovskite nanocrystals in composite materials are determined experimentally. The influence of external factors, such as light and temperature, on the optical properties of nanocrystals in composite materials was determined. It was found that the use of polyacrylate as a basis for composite materials improves the stability of nanocrystals, preventing degradation and oxidation, which contributes to the preservation of their optical characteristics for a long time. The results of the experiments emphasize the importance of taking into account the composition of composite materials and environmental conditions for the practical application of nanocrystals.
