Cerium oxide as an efficient electron extraction layer for p-i-n structured perovskite solar cells.

Cerium oxide, solution processed at a low temperature (∼100 °C), was successfully employed as an electron extraction layer on top of a perovskite. The CeOx layer shows good charge selectivity and increases light reflection from an Ag electrode. Besides this, the CeOx layer not only protects the perovskite from water, but also acts as a dense diffusion barrier to prevent the corrosion of the metal electrode.