Titania (TiO(2)) nanotubular arrays provide an exciting material for dye sensitizing solar cells (DSSC) because of their large surface area, lower recombination losses, and fast charge transport properties along the nanotubes. In this paper, design of a next generation DSSC using a TiO(2) nanotubular membrane is discussed. A single step, green process is developed to produce stable large area, free-standing TiO(2) nanotubular films (in a short time, 30-60 min) by anodizing Ti using an organic electrolyte, containing disodium salt of ethylene diaminetetraacetic acid (Na(2)[H(2)EDTA]) as complexing agent, and subsequent drying. Transparent, crack-free TiO(2) films, 20-41 microm thick containing ordered hexagonal TiO(2) nanotubes are achieved by this process. Films having a geometrical area up to 16.5 cm(2) with pore openings of 182 nm have been obtained. These films have been etched to form membranes which provide an exciting prospect for front side illuminated DSSC with good mass and photon transport properties as well as wettability. A photovoltaic efficiency of 2.7% is achieved using a front side illuminated DSSC compared to 1.77% using back side illumination.

The Zn 1-x Ni x O (0 ! x ! 0.1) systems were synthesized by a solid-state reaction technique at 700 8C for 7 h. The X-ray diffraction (XRD) pattern reveals the presence of secondary peaks due to NiO in Ni overdoped (>0.03) ZnO matrix. The compositional mapping on 5% Ni-doped ZnO on an electron probe microstructural analyzer (EPMA) indicates the segregation of oxides of Ni on the bulk surface. The ZnO samples doped with 3 and 5% Ni exhibit room-temperature ferromagnetism (RTFM). But, 7 and 10% Ni-doped ZnO samples do not exhibit ferromagnetism. Possibly, the enhanced antiferromagnetic interaction between neighboring Ni-Ni ions suppresses the ferromagnetic ordering, at higher doping concentrations of Ni, resulting in a rapid decrease in magnetic moments.

Most of the semiconductor materials are diamagnetic by nature and therefore cannot take active part in the operation of the magneto electronic devices. In order to enable them to be useful for such devices a recent effort has been made to develop diluted magnetic semiconductors (DMS) in which small quantity of magnetic ion is introduced into normal semiconductors. The first known such DMS are II-VI and III-V semiconductors diluted with magnetic ions like Mn, Fe, Co, Ni, etc. Most of these DMS exhibit very high electron and hole mobility and thus useful for high speed electronic devices. The recent DMS materials reported are (CdMn)Te, (GaMn)As, (GaMn)Sb, ZnMn(or Co)O, TiMn(or Co)O etc. They have been produced as thin films by MBE and other methods. This paper will discuss the details of the growth and properties of the DMS materials and some of their applications.

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