Doped ZnO powders studied by positron annihilation spectroscopy

L. C. DAMONTE; V.DONDERIS; J.OROZCO; M.A.HERNÁNDEZ-FENOLLOSA

Puerto Iguazú, Argentina

Simposio; XIX Latin American Symposium on Solid State Physics; 2008

Inorganic semiconductors, like TiO$_{2}$ and more recently ZnO, have been used as basic component of solid state dye sensitized solar cells (SDSC) combined with the adequate polymer. In this new kind of devices, interfacial processes are fundamental for conversion efficiencies and an optimal performance of the cell. Moreover, the complete knowledge of impurities and defects present in such inorganic semiconductors is important in order to reach the desire optical and electronic properties. With this aim we initialize a study on zinc oxide nanoparticles which have been modified by the In presence acting as small quantities of dopant. The nano sized doped-ZnO powders were prepared by mechanically milling which has been proved to be an effective and simple technique to produce nanocrystalline powders and the possibility of obtain large quantities of materials. The starting materials were the metal oxide In$_{2}$O$_{3}$ or the pure metal In. Parameters such as initial concentrations, atmosphere and milling times were varied. Different techniques were used to characterize their structural an optical properties: X-ray diffraction, positron annihilation spectroscopy (PALS), scanning electron microscopy and optical reflection spectroscopy. PALS proved to be a well suited probe to characterize the cation substitution in the ZnO oxide lattice. The knowledge obtained can contribute to the improvement of the performance of hybrid organic/inorganic solar cells.