Counter electrode corrosion mechanism in Sn-contained perovskite solar cells

In the recently researched Sn-contained perovskite solar cells (PSCs), limited work is focused on corrosion of a metal electrode, which is recognized as the obstacle of efficient and stable devices. Here, it is found that a pure Sn based PSC shows the most serious and quick corrosion of an Ag electrode, compared with Pb and Sn–Pb PSCs. I2, SnOX, and AgI are the main products of the aged Ag electrode in Sn based PSCs, which greatly differed from Pb and Sn–Pb PSCs. Oxidation of FASnI3 under O2/H2O produces aggressive I2, together with gaseous FA and diffusive I−, degrading the PVK film and Ag electrode greatly. This work highlights the corrosion velocity and mechanism of Ag electrodes in Sn-contained PSCs, which may help to find out possible solutions to circumvent the instable issue.