Perovskite solar cells to date are made of polycrystalline films which contain a high density of defects. Imperfection passivation to reduce non-radiative recombination and suppress ion migration could improve device efficiency and device stability.

Stability through oxysalts: The stability of organic-inorganic perovskite solar cells is limited by degradation from oxygen and water. Yang et al. show that in situ reaction of perovskites with sulfate or phosphate ions can create thin, strongly bonded lead oxysalt layers that protect defect sites. This layer also boosts charge carrier lifetimes that lead to a power conversion efficiency of more than 20%. Encapsulated devices maintained about 97% of this efficiency with simulated solar irradiation for nearly 2 months at a realistic operation temperature of 65°C. Science , this issue p. 473