Scientists from Daegu Gyeongbuk Institute of Science and Technology (DGIST) have discovered a new way to make solar panels more eco-friendly and sustainable.
Thin-film solar panels generally consist of expensive rare-earth elements like indium and gallium, or highly toxic metals like cadmium.
Bronze (Cu-Sn) and brass (Cu-Zn) could offer a better alternative as they are both abundantly available and eco-friendly too.
A major obstacle however hindering their adoption is that they have a low practical efficiency compared to their theoretical potential.
This is because of the formation of various defects in the materials, such as ‘point’ defect, ‘surface’ defect, and ‘volume’ defect during ‘annealing’ – or the process of heating and cooling to make a CZTSSe film.
These defects undermine the current flow, resulting in loss of electricity generated.
Now a team of scientists led by DGIST’s Dr. Jin-Kyu Kang and Dr. Dae-Hwan Kim, have discovered a novel way to overcome such hurdles.
The scientists had to first find a way to synthesize the best quality CZTSSe (copper, zinc, tin, sulfur, and selenium) thin films.
They played around with the annealing profile, which has a strong effect on the grain size of CZTSSe thin film: the longer the annealing time and higher annealing temperature, the larger the grains, and the lesser the electricity loss.
However, as the annealing temperature and time increase, there is a change in the properties of the CZTSSe thin film due to decomposition.
To bypass this issue, the team used a special ‘liquid-assisted method,’ which allowed the grains of CZTSSe to grow at a faster rate.
This meant that the grains could grow large even at low temperatures, preventing the change in the properties of the CZTSSe thin film.
Shedding light on their low-cost, environment-friendly approach, Dr Kim said that: “Our technology has diverse applications, including in electronic devices, household goods, buildings, and vehicles.”
“The best part is that CZTS solar cells are free of the current drawbacks of toxic and rare metals. We can install everywhere we want!”
Image and content: DGIST