IN A rare feat, an Integrated PhD student from IISER Pune, Abhishek Swarnkar, has got his research paper published in the prestigious international journal Science while working with a group of international researchers at the National Renewable Energy Laboratory, USA. The researcher who was selected for the Bhaskara Advanced Solar Energy Fellowship from the Department of Science and Technology (DST) and Indo-US Science and Technology Forum (IUSSTF) in 2014, was able to go to NERL, US in November 2015 where he presented his idea for research on developing unique material for solar cells, which was approved and a team was built for this purpose. The paper that got published on October 7 (Friday) in Science shows Swarnkar as one of the lead authors.
Stating that solar cells have always been sought after for decades now as electrical devices that convert light to electricity, scientists at IISER explained that the overall goal in solar cell research has been to produce low-cost, high-efficiency options. “Currently silicone-based solar cells are available but they are extremely expensive. The cost often depends on the type of semiconducting material that a solar cell is made of and the processings involved in the manufacturing process. Hence, research had been going on to make it cost effective,” said Swarnkar.
In the race to get cost-effective materials, the front runners have been materials with perovskite structure, usually hybrid organic-inorganic lead or tin halide based materials but these materials are not suitable for commercialisation. This is because even though the materials are efficient at 22 per cent, they are not durable. Speaking to The Indian Express, the PhD student explains that even though the scientific community was able to remove the organic element and introdium cesium to develop a completely inorganic material but it was thermally unstable.
“To explain in layman terms, the scientific community was developing bigger size crystals which made the product undesirable. What we did was reduced the size and developed nanocrystals. The material is now all-inorganic in nature and the small size makes the material stable,” said Swarnkar. The team was also able to prepare a long-range charge conducting film using this material which demonstrates that the material could be amenable to be used to develop an opto-electronic device. Scientists at IISER added that under ambient conditions, this perovskite quantum dot solar cell shows light to current conversion efficiency of 10.77 per cent and an open circuit voltage (equivalent to e.m.f. of a battery) of 1.23 V. The same device can also be work as an LED with low turn-on voltage and tunable emission.