City researchers develop 18 dye molecules for solar cells
At first glance, the colourful powders in narrow glass containers seem ordinary. But when exposed to sunlight, the black, brown, yellow and red powders have the ability to convert sunlight into electricity.
Researchers at the Institute of Chemical Technology (ICT), Matunga, have developed 18 synthetic dye molecules, which can be used to make indigenous dye-sensitised solar cells (DSC) that absorb solar energy.
At present, silicon - the second most abundant element in the Earth's crust after oxygen - is used to make solar cells. However, silicon has to be refined to 99.9999% purity to be used as semiconductor material in solar cells that makes the cells very expensive.
On the other hand, synthetic dyes are between Rs300 and Rs1,000 cheaper than silicon, thus bringing down the cost of both the solar cell and the electricity produced.
For instance, while energy from silicon-based solar cells costs between $.30 and $.40 per watt (Rs 14.70 and Rs 19.60), electricity generated by the low cost DSC would cost $.01 or 49 paise per watt. "Colours absorb and emit sunlight. Based on this principle, we developed dye molecules that can be used in solar cells, which can also withstand light for longer periods of time without getting decomposed," said professor G Shankarling, associate professor, department of dyestuff technology, ICT.
"The beauty of DSC is that unlike silicon solar cells that need direct sunlight, these cells can accumulate energy, when indoors, that can light electric devices such as lamps or to power a fan in the house," Shankarling said.
Described as the third generation solar technology, the research assumes significance for a developing country such as India with a hot climate, which has a huge demand for power that will be met with an energy mix comprising fossil fuels and renewable energy such as solar and wind.
"As against textile dyes, solar cell dyes need purity to avoid instability and decomposition. Different colours have different light absorption values. For example, though we know black soaks up maximum light, we don't know if black dye will absorb maximum sunlight," said Shankarling, adding that the dyes have to be checked for effectiveness on solar cells by an external agency.
At present, the varied coloured dyes with different chemical compositions have been sent to the Indian Institute of Technology - Bombay and the National Chemistry Laboratory at Pune to be checked for their efficacy when applied on the solar cell.