Highly efficient tin perovskite solar cells achieved in a wide oxygen concentration range

Tin perovskite solar cells (TPSCs) as one of the most promising candidates for lead-free PSCs have large potential to be industrialized in the future. However, TPSCs have often been fabricated at an extremely low oxygen concentration to avoid oxidation from Sn2+ to Sn4+, which is not applicable to their large scale production. In this work, we construct a carbonylate antioxidant capping layer atop the perovskite surface via a solvent engineering method to prevent oxygen permeation into the perovskite layer during the fabrication process of the device to enlarge the oxygen region from 0.1 ppm to 100 ppm. Meanwhile, a pinhole-free perovskite film with a large grain size, reduced Sn4+ defects and long carrier recombination lifetime was fabricated. As a result, high-performance TPSCs could be achieved in a wide range of oxygen concentration with a power conversion efficiency (PCE) of 9.47% at 0.1 ppm oxygen and 9.03% at 100 ppm oxygen, respectively; the device was stable, maintaining over 93% of its initial PCE after operating at the maximum power point under continuous light soaking (AM 1.5G, 100 mW cm−2) for 600 hours.