Nanotechnology Now - News Story: Simplifying the fabrication of nitrogen-doped titania coatings could benefit solar cell industry

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November 7th, 2007

Simplifying the fabrication of nitrogen-doped titania coatings could benefit solar cell industry

Abstract:
Titanium oxide (TiO2, titania) - due to its versatile optical, electrical and photochemical properties, its relative abundance and low cost, and its non-toxicity - is an important ceramic material with numerous applications as pigments; powders for catalytic or photocatalytic applications; colloids and thin films for photovoltaic, electrochromic, photochromic, electroluminescence devices and sensors; components for antireflecting coatings; or porous membranes for ultrafiltration. Nanocrystalline titania has become a prominent material for dye-sensitized solar cells (DSSCs, also known as 'Grätzel cells' after their inventor), which are photoelectrochemical cells that use photo-sensitization of wide-band-gap mesoporous oxide semiconductors. One major problem with the use of titania in solar cells is that its bandgap does not match that of visible light and titania therefore can only absorb 3-4% of the energy from sunlight. Grätzel cells decrease the bandgap of titania by using dye-absorbed TiO2 nanocrystals as one of the electrodes, resulting in a higher solar energy conversion of 10% or more. Other methods use doping and indeed the application of nitrogen-doped titania as photocatalyst has received increasing attention over the last years because N-doping is found to be particularly effective in decreasing the bandgap of anatase (many of the properties of titania depend on the structure of the TiO2 phase - mainly anatase, brookite and rutile). In order for photocatalysis-based applications to become commercially viable, it will be critical to design low-cost, reproducible, synthetic methods that yield controlled, reproducible, and easy-to-handle nanomaterials processed as coatings with high surface area and high porosity. Researchers in France and Spain now describe for the first time nanostructured coatings that fulfill all these requirements.

Source:
nanowerk.com

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