Mohammad-Reza Zamani-Meymian

Refractive index changes in lithium niobate crystals by high-energy particle radiation

Irradiation of lithium niobate crystals with 41 MeV 3He ions causes strong changes of the ordinary and extraordinary refractive indexes. We present a detailed study of this effect. Small fluence of irradiation already yields refractive index changes about 5×10−4; the highest values reach 3×10−3. These index modulations are stable up to 100°C and can be erased thermally, for which temperatures up to 500°C are required. A direct correlation between the refractive index changes and the produced lattice vacancies is found.

Self-Assembled ZnO Nanosheet-Based Spherical Structure as Photoanode in Dye-Sensitized Solar Cells

High surface area and enhanced light scattering of ZnO nanosheet aggregates have made them a promising active layer candidate material for fabrication of nanostructure dye-sensitized solar cells. Here, we propose a facile preparation method of such ZnO nanosheet structures, and in order to verify their applicability as photoanode material for dye-sensitized solar cells, we employ morphological, optical, structural and electrical measurements. The results reveal the high surface area available for dye molecules for enhancing adsorption, high light scattering and competitive power conversion efficiencies compared to the works in literature. Finally, the device is optimized with respect to the photoanode thickness. The favorable features shown here can extend the application of the structure to other types of sensitization-based perovskite and quantum dot solar cells.