Surface Defect\nClipping Strategy Enables High-Efficiency\nInorganic Perovskite Solar Cells with Ultralow <i>V</i><sub>OC</sub> Deficit

Recent developments in perovskite-silicon tandem solar\ncells (TSCs)\nhave been quite remarkable. Inorganic perovskite solar cells (IPSCs)\nare gradually emerging as the top cells in the tandem device. However,\nIPSCs generally suffer from a severe open-circuit voltage (<i>V</i><sub>OC</sub>) deficit, limiting their efficiency gains\nand application in TSCs. Here, we developed a surface defect clipping\nstrategy using pyridyl-2,6-dicarboxamide (PD) in a methanol solution.\nThe proper polarity of the methanol solution will clip the upper surface\nof the inorganic perovskite film and provide a corresponding path\nfor penetration of the PD solution. In addition, PD efficiently in\nsitu passivate uncoordinated Pb<sup>2+</sup>. After the annealing,\ndense perovskite films were formed on the upper surface of the inorganic\nperovskite. The crystallization dynamics of inorganic perovskites\nnear the surface is regulated, and nonradiative recombination is effectively\nsuppressed. Eventually, a record <i>V</i><sub>OC</sub> of\n1.259 V (1.71 eV) is achieved based on inverted IPSCs, and the <i>V</i><sub>OC</sub> deficit is only 450 mV. More importantly,\nunencapsulated IPSC devices show significantly enhanced thermal and\nhumidity stability.