And dye-based cells, having no rigid parts, can bend, and are mechanically robust compared with the silicon sort.

ECONOMIST: A new type of cell may bring ��solar�� energy indoors

Besides being tweakable to match the spectrum of a light-bulb, dye-based cells also work well in dim or diffuse light of the sort often found indoors.

ECONOMIST: A new type of cell may bring ��solar�� energy indoors

This makes dye-based cells more flexible than silicon ones.

ECONOMIST: A new type of cell may bring ��solar�� energy indoors

In the case of dye-based cells, which were invented at the Federal Polytechnic School of Lausanne, in Switzerland, in the 1990s, the light is first captured by molecules of a photosensitive dye.

ECONOMIST: A new type of cell may bring ��solar�� energy indoors

Using this technique doubled the efficiency of Dr Kamat's cell from 5% to 10% at ultraviolet wavelengths and he reckons it would create similar increases in efficiency in both plastic and dye-based cells.

ECONOMIST: Improved devices may make better use of sunlight

Eventually, says Mr Burt, the ability of dye-based cells to produce useful quantities of power even in dim and diffuse light could see them used outside, perhaps on rooftops in cloudier parts of the world a market at present dominated by traditional, silicon-based cells, even though they are not well-suited to the purpose.

ECONOMIST: A new type of cell may bring ��solar�� energy indoors