FYI,

"STMicroelectronics Announces Advanced R&D Program Targeting Low Cost
Solar Cells"
STMicroelectronics Press Release
http://www.st.com/stonline/press/news/year2003/t1355h.htm

: STMicroelectronics (NYSE: STM), one of the world's leading
: manufacturers of semiconductor devices, today released details of an
: advanced research program that it hopes will substantially reduce
: the cost of generating electricity from solar power. The research
: team, based in Catania and Naples, Italy, is focusing on applying
: ST's expertise in nanotechnology to the development of new solar
: cell technologies that will eventually be able to compete
: commercially with conventional electricity generation methods such
: as burning fossil fuels or nuclear reactors.

: However, existing solar cell technologies are mainly based on
: semiconductor materials such as silicon and therefore involve high
: material* costs. Consequently, although the "fuel" for a
: solar-powered generator is free sunlight, the overall cost of
: solar-generated electricity (amortized over the lifetime of the
: solar cell, typically 20 years) is around ten times higher than the
: cost of electricity generated by burning fossil fuels.

: Semiconductor-based solar cells have the highest efficiency (defined
: as the electrical energy produced for a given input of solar energy)
: but there is little that can be done to either increase the
: efficiency or reduce the manufacturing cost. ST is therefore
: pursuing alternative approaches in which the aim is to produce solar
: cells that may have lower efficiencies (e.g. 10% instead of 15-20%)
: but are much cheaper to manufacture.

: "Although there is much support around the world for the principle
: of generating electricity from solar power, existing solar cell
: technologies are too expensive to be used on an industrial scale.
: The ability to produce low cost, high efficiency solar cells would
: dramatically change the picture and revolutionize the field of solar
: energy generation, allowing it to compete more effectively with
: fossil fuel sources," says Dr. Salvo Coffa, who heads the ST
: research group that is developing the new solar cell technology.

: The ST team is following two approaches. One of these, invented in
: 1990 by Professor Michael Graetzel of the Swiss Federal Institute of
: Technology, uses a similar principle to photosynthesis. In a
: conventional solar cell, a single material such as silicon performs
: all three of the essential functions, which are absorbing sunlight
: (converting photons into electrons and holes), withstanding the
: electric field needed to separate electrons and holes, and
: conducting the free carriers (electrons and holes) to the collecting
: contacts of the cell. To perform these three tasks simultaneously
: with high efficiency, the semiconductor material must be of very
: high purity, which is the main reason why silicon-based solar cells
: are too costly to compete with conventional means of producing
: electric power.

: In contrast, the Graetzel cell, known as the Dye-Sensitized Solar
: Cell (DSSC), mimics the mechanism that plants use to convert
: sunlight into energy, where each function is performed by different
: substances. The DSSC cell uses an organic dye (photosensitizer) to
: absorb the light and create electron-hole pairs, a nanoporous (high
: surface area) metal oxide layer to transport the electrons, and a
: hole-transporting material, which is typically a liquid electrolyte.

: "One of the most exciting avenues we are exploring is the
: replacement of the liquid electrolytes that are mostly used today
: for the hole-transport function by conductive polymers. This could
: lead to further reductions in cost per Watt, which is the key to
: making solar energy commercially viable," says Coffa.

: The ST team is also developing low cost solar cells using a full
: organic approach, in which a mixture of electron-acceptor and
: electron-donor organic materials is sandwiched between two
: electrodes. The nanostructure of this blend is crucial for the cell
: performance because the electron-donor and electron-acceptor
: materials have to be in an intimate contact at distances below
: 10 nm. ST plans to use Fullerene (C60) as the electron-acceptor
: material and an organic copper compound as the electron-donor.

Caution, this appears to be PR spin rather than a real break through,
but worth watching.

Mark Reiff