Versatile Molybdenum Isopropoxide for Efficient Mesoporous Perovskite Solar Cells: Simultaneously Optimized Morphology and Interfacial Engineering

The high-quality CH₃NH₃PbI₃ film morphology and delicate interfacial modification are critical to achieve high-performance perovskite solar cells (PSCs). Here, we report a facile and efficient method to optimize the morphology and interface of a perovskite solar cell by molybdenum isopropoxide (Mo-IPA) solution treatment during the fabrication process of the perovskite film. After simply being treated with Mo-IPA, both highly crystalline perovskite film and MoO_X interfacial layer could be simultaneously achieved. The Mo-IPA treatment can induce a denser and more uniform morphology of CH₃NH₃PbI₃ with larger crystals size than pure isopropyl alcohol (IPA) treatment. At the same time, the formation of MoO_X can effectively elevate the valence band maximum (VBM) of the perovskite, as a result to favor a better energy alignment with 2,2′,7,7′-tetrakis­(N,N-di-p-methoxyphenylamine)­9,9′-spirobifluorene (Spiro-MeOTAD) hole transport layer (HTL) for efficient hole extraction. With those excellent properties obtained, the photovoltaic performance of the PSCs was remarkably increased from 10.8% to 12.0%.