Organic Molecule and Inorganic Salt Synergistic‐Modified SnO 2 for Efficient Perovskite Solar Cells

Element doping and interface modification strategy are effective methods to regulate the electrical properties of SnO 2 electron transport material, SnO 2 /perovskite (PVK) interface, and PVK crystal growth. Herein, rubidium fluoride (RbF) is introduced into SnO 2 colloidal dispersion, and then an ultra‐thin layer of 4‐carboxy‐3‐fluorobenzoboric acid (FBCA) is applied to the SnO 2 layer surface. This synergistic modification strategy can improve the electrical conductivity of the electron transport layer, increase the chemical connection of the buried interface, improve the crystallization and grain growth of PVK, and thus promote the performance and stability of devices. The results show that the PVK solar cells (PSCs) with the synergistic‐modified SnO 2 electron transport material (M‐SnO 2 ) obtain an optimum power conversion efficiency of 21.92% and the unencapsulated PSCs sustain 91% and 87% of the original value, which stored in a nitrogen atmosphere and ambient atmosphere (25 ± 5 °C, 30–50% relative humidity) more than 1000 h, respectively.