inorganic solar cells used today are also quite bulky. Initial costs also seem to be a major deterrent in the spread of solar energy. A us-Austrian team led by 2001 Nobel laureate Alan Heeger has gone some way in mending matters.

In 2005, the team had come up with a new plastic polymer photovoltaic cell, thin and pliable as photographic film. But the efficiency of this cell was low: it could convert only 3.5 per cent of the solar energy into electrical energy, way below the 10 per cent achieved by the crystalline silicone cells then in vogue. New research by the team published in the March 19 issue of Journal of the American Chemical Society shows that adding a class of chemicals called alkanedithiols improves the conversion rates of the plastic cells to 5 per cent. This is still way below commercial viability. But silicone cells cost us $350 per square metre and Heeger's team hope to scale down the costs of their organic solar cells as low as us $30 in the near future.