Tailored Lattice “Tape” to Confine Tensile Interface for 11.08%‐Efficiency All‐Inorganic CsPbBr(3) Perovskite Solar Cell with an Ultrahigh Voltage of 1.702 V

The crystal distortion such as lattice strain and defect located at the surfaces and grain boundaries induced by soft perovskite lattice highly determines the charge extraction‐transfer dynamics and recombination to cause an inferior efficiency of perovskite solar cells (PSCs). Herein, the authors propose a strategy to significantly reduce the superficial lattice tensile strain by means of incorporating an inorganic 2D Cl‐terminated Ti(3)C(2) (Ti(3)C(2)Cl (x) ) MXene into the bulk and surface of CsPbBr(3) film. Arising from the strong interaction between Cl atoms in Ti(3)C(2)Cl (x) and the under‐coordinated Pb(2+) in CsPbBr(3) lattice, the expanded perovskite lattice is compressed and confined to act as a lattice “tape”, in which the Pb—Cl bond plays a role of “glue” and the 2D Ti(3)C(2) immobilizes the lattice. Finally, the defective surface is healed and a champion efficiency as high as 11.08% with an ultrahigh open‐circuit voltage up to 1.702 V is achieved on the best all‐inorganic CsPbBr(3) PSC, which is so far the highest efficiency record for this kind of PSCs. Furthermore, the unencapsulated device demonstrates nearly unchanged performance under 80% relative humidity over 100 days and 85 °C over 30 days.