“…It relies on the sequential pulsing of individual precursors which react with the material surface in a self-terminating way, thus allowing strict control of the amount (a monolayer) deposited. ,− Over the past decade, ultrathin layers of ALD Al 2 O 3 , ZnO, SnO 2 , and TiO 2 have been used in various PSC architectures to passivate the metal oxide electrode (to suppress interfacial recombination), − between perovskite and a charge transport layer (to decrease interfacial reaction), ,− as cathode buffer layer to protect the perovskite during deposition of the top electrode and reduce interfacial charge recombination, , to produce a pinhole-free electron transport layer for reduced interfacial recombination loss, − or as an overall encapsulation layer for PSCs to protect them from moisture/environment-based degradation. , More recently, AlO x encapsulation by ALD has been reported to improve stability toward exposure to air, irradiation, heat, and water for fully inorganic CsPbBr 3 nanocrystals. − AlO x has been used for infilling and interface engineering of CsPbBr 3 nanocrystal emission layers in LEDs as well. The introduction of Al 2 O 3 /ZnO ALD layers significantly improves the tolerance of CsPbBr 3 PNC thin films to polar solvents (ethanol) during deposition of electron transport layer and increases the operation lifetime. , …”