Researchers at the University of Warwick in the UK designed an environmentally friendly perovskite solar cell in which lead is substituted for tin with reportedly undiminished rates of performance but at cheaper cost and with lower toxicity.

The team stated that tin-based perovskites are much more stable than previously thought, and also render solar power cheaper, safer and possibly even more commercially attractive. "The device structure can be greatly simplified without compromising performance, which leads to the important advantage of reduced fabrication cost" the scientists say.

According to the researchers, perovskite PV devices that do not require a hole-selective interfacial layer are around 10 times more efficient than devices with the same architecture based on methylammonium lead iodide perovskite. The highest efficiency to date for a CsSnl3 PV cell is 3.56%. "We have shown that the improved performance and tolerance to pinholes in the perovskite film stems from n-doping of the fullerene electron-transport layer by SnCl2, and that the stability of unencapsulated CsSnI3 is improved by at least an order of magnitude as compared to lead-based PPV," said the paper.

The team believes that these findings justify an intensive research effort into tin perovskite PVs, focused on improving η to a level comparable to that of lead perovskite PVs.