Interfacial Engineering\nthrough Chloride-Functionalized\nSelf-Assembled Monolayers for High-Performance Perovskite Solar Cells

The family of organic–inorganic hybrid perovskite\n(OIHPs)\nmaterials is one of the most promising for very high-efficiency photovoltaic\nsolar cell application. In the present work, the effect of a series\nof self-assembled monolayers placed at the TiO₂–perovskite\njunction, on the functioning of triple cation perovskite solar cells\nhas been investigated. We show that employing 4-chlorobenzoic acid\nleads to the marked boosting of the solar cell performances. The starting\npristine cell had a power conversion efficiency (PCE) of 20.3% and\nthe chemical engineering permitted to reach a PCE up to 21.35%. Our\nexperimental study completed by density functional theory calculations\nand modeling show that this progress is due to the reduction of interfacial\nstates, to the improvement of the quality of the OIHP material and\nto the structural continuity between TiO₂ and the OIHP.\nEspecially, we demonstrate that the interfacial chemical interactions\nare important to consider in the design of highly efficient devices.