Simple, solar-powered water desalination (Part 2)

The promising halide perovskite materials for solar energy conversion show high efficiencies, but this comes at a cost: The best perovskite materials incorporate toxic lead which poses a hazard to the environment. To replace lead by less toxic elements is not easy since lead-free perovskites show lower stability and poor efficiencies. Now, an international collaboration has engineered a new hybrid perovskite material with promising efficiency and stability.
Among the new materials for solar cells, the halide perovskites are considered particularly promising. Within a few years, the efficiency of such perovskite solar cells raised from a few percents to over 25 %. Unfortunately, the best perovskite solar cells contain toxic lead, which poses a hazard to the environment. However, it is surprisingly challenging to replace the lead with less toxic elements. One of the best alternatives is tin. Halogenide perovskites with tin instead of lead should show excellent optical properties, but in practice, their efficiencies are mediocre and decrease rapidly. And this rapid "aging" is their main disadvantage: the tin cations in the perovskite structure react very quickly with oxygen from the environment so that their efficiency drops.
Now, an international cooperation led by Antonio Abate, HZB, and Zhao-Kui Wang, Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, China, has achieved a breakthrough that opens up a path to non-toxic perovskite-based solar cells that provides stable performance over a long period. They also use tin instead of lead but have created a two-dimensional structure by inserting organic groups within the material, which leads to so-called 2D Ruddlesden-Popper phases. "We use phenylethylammonium chloride (PEACl) as an additive to the perovskite layers.