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Updated: February 6, 2012 19:10 IST

Solar cells moving down the roof

T. Nandakumar
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K. Kalyanasundaram, senior scientist at the Swiss Federal Institute of Technology, Lausanne, Switzerland, with a modern solar panel. Photo: S. Mahinsha
K. Kalyanasundaram, senior scientist at the Swiss Federal Institute of Technology, Lausanne, Switzerland, with a modern solar panel. Photo: S. Mahinsha

Dye-sensitised cells lend on-the-go flexibility

A backpack that powers your mobile phone, MP3 player or laptop on the go, tinted windows that continuously generate electricity from sunlight, solar modules that can be patched on to shamianas and awnings, and building facades that produce power from the sun — all these would have seemed far-fetched ideas until a few years ago.

But recent advances in thin film technology have resulted in revolutionary concepts and products. Today, it is possible to have roofing materials, wall panels, foldable sheets, backpacks, and windows featuring lightweight, flexible solar cells.

Research laboratories across the world are vying to develop cheaper, more efficient solar modules for different applications. The dye-sensitised solar cells (DSSCs) represent one of the promising frontier areas of research.

Based on a photo-electro-chemical system, the DSSCs are basically titanium dioxide semiconductor nanocrystals coated with organic dye and sandwiched between glass panels or embedded in plastic along with an electrolyte. Substantially cheaper than conventional silicon solar panels, they can be printed on flexible surfaces and work more efficiently in ambient light conditions.

“The increasing global demand for energy and the rising level of greenhouse gas emissions have driven the need to find clean, renewable sources of power. DSSCs have emerged as a promising alternative,” says K. Kalyanasundaram, senior scientist at the Swiss Federal Institute of Technology, Lausanne, Switzerland, one of the laboratories working at the cutting edge of technology in solar cells.

Talking to The Hindu on a recent visit to the city to participate in a national symposium organised by the Chemical Research Society of India (CRSI), he explained how chemical research across the globe had led to the development of new dye-sensitised cells with the capacity to generate more electricity. The DSSCs absorbed sunlight through the coloured molecules in the dyes and converted it into electricity, a process akin to plant photosynthesis.

“DSSCs have the potential to redefine the concept of green buildings. They could lead to the development of tinted windows or claddings for buildings that continuously produce electricity from the sun. With that kind of advance, we would have entire buildings generating power, rather than just the rooftops. It is possible to adjust the transparency of DSSCs integrated into a window or roof. You can even have multicolour options for better visual appeal,” he said, holding up a flexible, paper-thin DSSC module embedded in plastic.

“Unlike silicon solar panels that are heavy and opaque, DSSC modules do not need heavy fabrication for use as roof or facade. They are flexible yet robust. Being translucent, they permit sunlight to enter the building.”

Dr. Kalyanasundaram said the DSSCs were increasingly relevant at a time when countries were offering heavy subsidies for solar equipment to power buildings. “They make more sense in a country like India with good exposure to sunlight almost round the year. The development of better dyes and electrolytes could see them gaining more market acceptance,” he said.

In 2010, a company based in Hong Kong launched the first DSSC-based consumer product, backpacks fitted with solar panels for on-the-go recharging of portable devices.



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