Component Distribution Regulation in Sn‐Pb Perovskite Solar Cells through Selective Molecular Interaction

Abstract Tin‐lead (Sn‐Pb) perovskite solar cells (PSCs) with near‐ideal bandgap still lag behind the pure lead PSCs. Disordered heterojunctions caused by inhomogeneous Sn/Pb ratio in the binary perovskite film induce large recombination loss. Here, an Sn‐Pb perovskite film is reported with homogeneous component and energy distribution by introducing hydrazine sulfate (HS) in Sn perovskite precursor. HS can form hydrogen bond network and coordinate with FASnI₃ thus no longer bond with Pb²⁺, which reduces the crystallization rate of tin perovskite to the level of lead analog. The strong bonding between SO₄²⁻ and Sn²⁺ can also suppress its oxidation. As a result, the Sn‐Pb PSCs with HS exhibit a significantly improved V_OC of 0.91 V along with a high efficiency of 23.17%. Meanwhile, the hydrogen bond interaction network, strong bonding between Sn²⁺ and sulfate ion also improve the thermal, storage, and air stability of resulting devices.