Trans-spatial Structure Additive Passivated Sn(II) for High-efficiency CsSnI3 Perovskite Solar Cells Fabricated in Humid Air

Black crystalline gamma-CsSnI3 is an ideal light absorption material to replace lead-based perovskite due to its low biotoxicity and excellent photoelectric properties. However, CsSnI3 is usually prepared in a low humidity inert atmosphere because of its oxidation in air. The severe preparation environment, on the other hand, will surely raise the economic cost of mass production. Therefore, a kind of additive engineering is proposed to introduce (1R, 2R)-(-)-1,2-diaminocyclohexane (transDACH), a small nitrogen-containing ligand with trans-spatial structure, into the perovskite layer, which can stabilize Sn2+ in the preparation process, allowing for the preparation of efficient and stable perovskite solar cells under high humidity conditions. The forward scan maximum power conversion efficiency (PCE) of the CsSnI3-transDACH device reaches 5.49%, the highest for hole-free carbon-based CsSnI3 PSCs prepared in humid air conditions. Furthermore, the transDACH-modified devices retain 73.7% of their original PCEs after 160 hours of storage in ambient air conditions.