CATANIA, Italy -- STMicroelectronics is working on a research program intended to reduce the cost of generating electricity from solar power.
Semiconductor materials are already well known as photovoltaics and in the past much research has gone into increasing the efficiency of energy conversion but this has added to the cost of manufacture such that the large-scale and long-term cost of solar energy is ten times that of nuclear energy and burning fossil fuels.
The ST research team, based in Catania and Naples, Italy, is therefore trying to develop solar cells that may have lower efficiencies, say 10 percent instead of 15 to 20 percent, but that are much cheaper to manufacture.
"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," said Salvo Coffa, who heads the ST research group that is developing the solar cell technology, in a statement.
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. The Graetzel cell includes 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," said 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-nanometers. ST plans to use the Fullerene allotrope of carbon (C60) as the electron-acceptor material and an organic copper compound as the electron-donor.
"In addition to ensuring that our own industrial activities have minimal impact on the environment, we are developing many new technologies that we hope will bring substantial ecological benefits," said Coffa.