Researchers from the University of New South Wales (UNSW), Australia, have achieved the highest efficiency rating for a full-sized thin-film solar cell using a competing thin-film technology known as CZTS. This invention takes us a step closer towards fulfilling the dream of ‘zero-energy’ buildings, which generate as much power as they consume.
Such buildings are not yet a reality mainly because of two reasons: the cost of thin-film solar cells and the fact that these films are made from scarce and highly toxic materials such as CdTe (cadmium-telluride) and CIGS (copper-indium-gallium-selenide). On the contrary, CZTS cells are made from non-toxic abundant materials such as copper, zinc, tin and sulphur.
“In addition to its elements being more commonplace and environmentally benign, we are interested in these higher bandgap CZTS cells for two reasons,” said Martin Green, professor at UNSW. “They can be deposited directly onto materials as thin layers 50 times thinner than a human hair, so there is no need to manufacture silicon ‘wafer’ cells and interconnect them separately,” he said. He also added that CZTS respond better than silicon to blue wavelengths of light and thus can be stacked on top of silicon cells to improve their overall performance.