Atomic Layer-Deposited Aluminum Oxide Hinders Iodide Migration and Stabilizes Perovskite Solar Cells

Iodide migration causes degradation of the perovskite solar cells. Here, we observe the direct migration of iodide into the hole-transport layer in a device. We demonstrate that ultrathin room temperature atomic layer-deposited Al2O3 on the perovskite surface very effectively hinders the migration. The perovskite-Al2O3 interface enables charge transfer across the Al2O3 layer in the solar cells, without causing any drastic changes in the properties of the perovskite absorber. Furthermore, it helps to preserve the initial properties of the perovskite film during exposure to light and air under real operating conditions, and thus, improves the stability of the solar cells. The ultrathin Al2O3 layer deposited at room temperature significantly increases the lifetime of the perovskite solar cells, and we hope this may be a step toward the mass production of stable devices. [Display omitted] Room temperature deposition of Al2O3 layer does not affect perovskite chemistryThin Al2O3 layer limits migration of iodide into Spiro-MeOTAD layerThe Al2O3 layer increases the stability of the perovskite deviceDirect observation of iodide flow in perovskite solar cells Atomic layer-deposited Al2O3 thin film has been used to inhibit the self-degradation of perovskite solar cell devices. Das et al. report the room temperature deposition of Al2O3 onto perovskite to limit the flow of iodide under solar cell working conditions. This has the 2-fold benefit of protecting both the perovskite and hole transporting SpiroMeOTAD layers.