Researchers at the University of Helsinki are developing thin films for perovskite solar cells, and matching ALD processes.
Doctoral Researcher Georgi Popov focuses on perovskites and atomic layer deposition (ALD). In 2019, He and his colleagues identified suitable chemicals and were able to design a reaction that enabled them to create a metal iodide coating through deposition for the first time. The researchers were able to demonstrate that this can actually be done through atomic layer deposition. The first successful trial was carried out with lead iodide, which was then processed into CCH₃NH₃PbI₃ perovskite through a further reaction. Later on, the researchers also developed ALD processes for caesium iodide and CsPbI₃ perovskite.
Coatings produced through atomic layer deposition are used in roughly 30% of silicon-based solar panels. The ALD group headed by Professor Mikko Ritala at the University of Helsinki has achieved promising results in terms of the technique’s adaptability to perovskite solar cells. The advantage of coatings produced by atomic layer deposition is that they form a uniform and comprehensive layer even on rough surfaces.
“If at some point we start making tandem solar cells, which combine a silicon cell and a perovskite cell, we know how to make that perovskite. We are developing the recipes and the chemistry used to grow perovskite,” Popov says.
While the work currently being carried out is basic research, developing recipes and experimenting with small surface areas, the technique is applicable to large-scale production. “The current plants manufacturing solar cells in China and elsewhere are able to adjust their equipment to produce ALD-coated solar cells,” says Popov.
