Current perovskite cells rely on lead as a key ingredient. Dr Ross Hatton, Professor Richard Walton and colleagues managed to replaced the lead with tin and simplifying the device structure without compromising performance, which offers the important advantage of reduced fabrication cost.
“It is hoped that this work will help to stimulate an intensive international research effort into lead-free perovskite solar cells, like that which has resulted in the astonishingly rapid advancement of lead perovskite solar cells," said Hatton.
The CsSnI3 perovskite solar cells have a stability around 10 times greater than devices with the same tin-based architecture using methylammonium lead iodide perovskite, and the highest efficiency to date for a CsSnI 3 photovoltaic at 3.56%, although this compares to over 20% efficiency for lead-based perovskite cells. The efficiency results from a high device fill factor, achieved by co-depositing the perovskite precursors with SnCl 2. This avoids the need for an electron-blocking layer or an additional processing step to minimize the pinhole density in the perovskite film and raises the prospect that this class of lead-free perovskite photovoltaic may yet prove viable for applications.