Sieryk M. Processes of molecular organization in semiconductor films on the monomethyne, merocyanine and squaraine dyes

Thesis is devoted to the study of the regularities of the molecular organization of conjugated polymethine type compounds in solid state by comparing data of optical spectroscopy and simulation, determining the structure of molecular aggregates depending on the chemical structure of the molecule, the nature of the substrate, and other factors such as the substrate temperature, film thickness, and the possibility of controlled formation of molecular layers of the selected organic compounds. In the framework of the thesis, a technical solution was developed for depositing thin films of organic compounds of polymethine type of weak temperature resistance to avoid their decomposition during the formation of a film. The spectral properties of ultrathin films of compounds in the process of their formation were investigated, spectral features of molecular complexes, conditions of origin and development of aggregation of molecules were analyzed. Quantum-chemical calculations of the molecular geometry of individual molecules as well as the energies of electronic transitions are performed, the energy of their formation is determined. The simulation of the processes of adsorption of compounds on substrates of different types was carried out, the principle of formation of molecular layers, the energy of their interaction with the surface was determined. The possibility of controlled formation of molecular layers in the process of film deposition via temperature changes of substrates is established. The methods of quantum-chemical analysis have shown the dependence of the conformation of the molecules of the selected compounds and the structure of their molecular dimers, depending on the chemical composition, environment and conditions of the film formation. It is shown that the conformation of a molecule may depend on interaction with the substrate and intermolecular interaction in the aggregate. It was found that the magnitude of the dipole moment for this type of compounds is the determining factor in the formation of the structure of the aggregate. The role of other factors in the formation and rearrangement of the structure of the aggregate, such as the temperature and nature of the substrate, decreases with increasing dipole moment of the molecule.