Increasing the efficiency and minimizing the negative effects of innovative technologies on ecology, simplifying production methods and maintaining a competitive price-quality ratio - these are just some of the general objectives of researchers and engineers in the context of the continuous evolution of the society. Thus, the combination of two semiconductor materials in tandem photovoltaic (PV) structures has become a current and quite promising solution in order to further develop the renewable energy sector. The efficiency of such structures is increased, because the in the PV conversion are involved two junctions with optimal efficiency in its sensitivity region. In this project, as junctions with the wide band-gap (E_g), functional in the short wave region, those based on kesterite type compounds, which have reached an efficiency of up to 12.6%, ware used. Such materials are represented by quaternary compounds with the general formula Cu(Ag)₂A^IIB^IVX₄, where A=Zn, Cd; В^IV=Si, Ge, Sn and X = S, Se, which form a wide class of compounds with related structures. These are semiconductors with a direct band-gap, with a high absorbtion coefficient (> 10⁴ cm^-1) and a tunable E_g between 1.0 and 2.5 eV. On the other hand, the component with E_g of 1.1 eV (the secondary junction in tandem structure) it will be the junction formed by depositing on the silicon (Si) substrate of a thin layer of indium tin oxide (ITO). The silicon wafer will also serve as a support for the tandem structure. In order to appreciate the potential of the use of solar energy in our country, and to study the influence of the optical properties of the atmosphere on the incident solar radiation on the earth’s surface, the station for measurements of solar radiation, which is endowed with the most modern electronic equipment and radiometric sensors, was used. Also, the development of nanostructures in chalcogenide glasses and azopolymers thin films with specific polarization properties, as well as new methods and technologies for micro- and nano-patterning of diffraction optical elements (DOE) in these materials will expand the applications of them in fields of nanotechnology, photonics and biomedicine. These will be used in all optical recording media, imaging, photonic application and sensors. Thus, the main purpose of this project was to obtain new materials and develop new high-performance technologies for PV and photonics for the benefit of society.