When Sai Santosh Kumar Raavi was growing up in Andhra Pradesh, his grandmother used to send him to the shops to buy kumkum in large amounts during festival time. He would return with the bright red powder and his hands would be red for days to follow, no matter how much he tried to wash it off. Now a physics professor at IIT-Hyderabad, he’s nodded to a unique quality of kumkum dye to create an organic solar cell which is low-cost to make and also better for the environment as the creation of the product doesn’t leave such a heavy carbon footprint.
The publication of this development ‘Low cost ‘green’ dye sensitized solar cells based on New Fuchsin dye with aqueous electrolyte and platinum-free counter electrodes’ in the July issue of Solar Energy Journal made viral headlines internationally. In the past few weeks, Santosh and his then-PhD student 30-year-old Dr Ramesh Kokal definitely drew eyes, with the curiosity their project accumulated.
They worked tirelessly on the development of this specific solar cell while adhering to the very parameters they required. Ramesh says, that ideally, he wanted to make this the answer to the solar challenge of making the process more organic.
- One has to ready the kumkum dye in a specific way for this scientific novelty. Santosh explains, “Naturally when dealing with kumkum, we add the dye into the turmeric sticks, and mill it, not just mix.”
- He says Professor M Deepa from the chemistry department was instrumental in developing the right dye to make it optimal for implementation in the solar cell.
“Kumkum is really inexpensive, off-the-shelf and, to be honest, at the start of this, the trials weren’t working well. We tried for three years! The best we wanted to achieve was to have some photo-action, meaning ‘are we able to convert the solar energy into light?’” he elaborates, “Dye-sensitised technology, though, isn’t new; the first paper of this came in 1992; the best efficiency available to date is 13.5%. The dyes we use in the best in the best devices are organic but they’re expensive. The most standard one is the lithium-based dye which costs $450 per gram. What we use for a ‘five millimetre by five millimetre’ (the size of the prototype) is in milligrams and kumkum is what, ₹25 per 100 grams? We can make it scalable for sure. We wanted to look at it from an economics-perspective.”
Santosh makes it clear that the official name for the dye is New Fuchsin, while kumkum dye is the derivative.
Another inexpensive material for the completed solar cell is a conductive carbon fabric which Ramesh was very specific about using. “These materials are available in the mass market,” he points out, “but we needed to be very specific about the properties.” This determination led him to finding a thin ribbon-like fabric which is sandwiched between glass and the dye-sensitised solar cell.
Santosh adds that there is no move to patent this; he wants this to be available to as many people as possible so they may build upon it. If this expands, there’s a chance lesser privileged societies will look at solar power completely differently. After all, this has made us look at kumkum dye differently too.
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