Insight into the Interface Engineering of a SnO₂/FAPbI₃ Perovskite Using Lead Halide as an Interlayer: A...

The interfacial properties of the perovskite photovoltaic layer and electron transport layer (ETL) are critical to minimize energy losses of perovskite solar cells (PSCs) induced by interfacial recombination. Herein, the interface engineering of the SnO₂/FAPbI₃ perovskite using PbX₂ (X = Cl, Br, or I) as an interlayer is extensively studied using first-principles calculations. The results reveal that the thickness of the PbI₂ interlayer needs to be finely controlled, which may limit charge transport if there is a large amount of PbI₂ precipitation at the interface. The high lattice mismatch of the PbBr₂ with the SnO₂/FAPbI₃ interface makes PbBr₂ an unfavorable passivation material. Due to the strong coupling of the PbCl₂ with both SnO₂ and FAPbI₃, an efficient electron transport pathway could be built after applying PbCl₂ as an interlayer. Meanwhile, the PbCl₂ interlayer could also effectively passivate interface defects, therefore lowering the energy losses of PSCs.