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

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 SO₄ ^2- 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.