Abstract:

Core-shell structures based on semiconductor and oxide materials present especial interest for biological and industrial applications. Among these materials, ZnO and TiO2 are not expensive, abundant in nature, and with large applications in sensors and dye sensitized solar cells (DSSC). Zinc oxide can be produced in the form of a variety of structures at low temperatures (<150°C), which is an important advantage for the deposition on flexible plastic supports. The technology for obtaining core-shell ZnO/TiO2 structures, including the ZnO core with various morphologies (spherical nanoparticles, nanowires, nanorods, nanotetrapods, dendrite structures) will be developed in this project. The dimensions of structures will de controlled by the parameters applied in electrochemical technologies, chemical bath deposition, successive ionic layer adsorption and reaction (SILAR). Hydrothermal and SILAR technologies will de elaborated for obtaining ZnO, ZrO2, MgO shells for structures with TiO2 core. These structures will be optimized from the point of view of charge carrier transport and surface reactivity through the production of the core with optimized conductibility and the shell with passivated surface. The energy band engineering will be applied for this purpose. Technological conditions will be elaborated for the production of shells with uniform composition and thickness assuring an efficient electron injection from the sensitizer and a maximum suppression of the electron-hole recombination, which will result in the increase of the short circuit current, open circuit voltage, efficiency and stability of the produced devices. Core shell structures on the basis of the above mentioned materials will be produced and tested as radiation and gas sensors as well as photoelectrodes in dye sensitized solar cells.