Zhulai D. Nonlinear-optical and photo-electric effects in new nanocomposites of anisotropic glasses of metal-alkanoates with semiconductor and metallic nanoparticles

The thesis is devoted to the study of structural, dielectric, photoelectric, optical and nonlinear optical properties of nanocomposites based on ionic liquid crystals (ILC) of metal-alkanoates with semiconductors (CdS, CdSe), metal (Ag, Au) and hybrid (core/shell) nanoparticles (NPs). Metal-alkanoates have a general structural chemical formula CnH2n+1(COO)-1kMe+k, where Me - is the metal cation. ILC metal-alkanoates in the thermotropic smectic phase can act as nanoreactors for chemical synthesis of different types of NPs. The technology of chemical synthesis of NPs directly in the matrix of ILC indicates that the matrix as a stabilizer of NPs, resulting in to a small sizes dispersion of NPs. Scanning electron microscope and transmission electron microscope images of new nanocomposites were obtained for the first time. The structural characterization of new nanocomposites of metal-alkanoates has been carried out, the sizes of various types of NPs and their size dispersion have been determined depending on the type of NPs and the metal alkanoate species that make up the matrix. The properties of optical absorption and its mechanisms for nanocomposites with various types of NPs are established. The electrical and photoelectric properties of nanocomposites are investigated as a function of temperature and frequency, and the mechanisms of electrical conductivity are established. The main type of electrical conductivity in all nanocomposites with different types of NPs is ionic conductivity, which has an activation character. Anisotropy of electrical, photoelectric and dielectric characteristics in nanocomposites is revealed, in which charge transfer is carried out mainly along cation-anion layers of a metal-alkanoate matrix. The short-circuit current in nanocomposites and the photovoltaic effect are investigated. The characteristics of the high-speed nonlinear-optical response of nanocomposites during pulsed laser excitation (nanosecond pulses) are determined, mechanisms of nonlinear-optical response in nanocomposites with various types of NPs are established. The results obtained in the work are important both in fundamental science and in the application of ILC metal-alkanoate. They can effectively replace already known elements and devices such as solar cells, optical amplifiers, virtually unlimited varieties of sensors, etc. Also, new devices can be created on their basis.