“Trivalent dopants on ZnO semiconductor obtained by mechanical milling”

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

Corfú, Grecia

Simposio; XIV International Symposium on Metastable and Nanocrystalline Materials (ISMANAM07); 2007

The last years there has been a growing interest in the development of cheap hybrid organic/inorganic photovoltaic cells consisting of a wide band gap semiconductor and conjugated polymer as sensitize. In this study we present a contribution to the development of  zinc oxide nanoparticles  which optical and electrical properties has been modified by the Al and In presence acting as small quantities of dopant. The aim of this study is to improve the compatibility of both compounds present in the bulk heterojunction in blend films based photovoltaic solar cells. It is known that in these hybrid solar cells better electron transport within the oxide semiconductor is a product of both its higher homogeneity composition and an internal electric field that can assist carrier collection by separating injected electrons from the surrounding polymer and sweeping them towards the collecting electrode. The nano sized powder of zinc oxide compounds 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 oxides (In2O3, Al2O3) or the pure metal (In, Al). Parameters such as initial concentrations, atmosphere and milling times were varied. Different phases were obtained according to the initial conditions (precursor used, atmosphere, etc.) and the enthalpies of phase’s formation. We have performed structural and optical characterization of ZnO-doped powders by X-ray diffraction, positron annihilation spectroscopy, scanning electron microscopy and optical reflection spectroscopy. The results are compared with undoped ZnO nanocrystalline powders prepared in a similar way. The knowledge obtained can be of use to give direction to the improvement of the performance of hybrid organic/inorganic solar cells.