Multifunctional molecule interface engineering enables the development of efficient and stable inorganic CsPbI₃...

A multifunctional molecule, methyl 3-formyl-4-hydroxybenzoate (MHBA), was applied as an interface modification layer for inverted inorganic CsPbI₃ solar cells. The MHBA enabled strong interactions with undercoordinated species, effectively passivating interfacial defects and stabilizing the surface lattice of CsPbI₃ films. Consequently, an enhanced PCE of 21.11% was achieved with a remarkably improved V_oc of 1.211 V and retained ∼91% of the initial PCE after ∼1000 h of storage under an N₂ atmosphere at 25 °C in the dark without encapsulation.