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

The high-quality CH3NH3PbI3 film morphology (a) 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 MoOX 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 MoOX 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'-tetralds(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%.