“…The unique properties of organic–inorganic hybrid halide perovskite materials, such as their high light absorption coefficient, carrier mobility, structural tunability, and defect tolerance, , contribute to the high power conversion efficiency (PCE) of perovskite solar cells (PSCs). − However, hybrid perovskites usually suffer from intrinsic and environmental instability, − and the presence of defects further accelerates their degradation and phase transition. − These defects, mainly organic cation and halide anion vacancies, usually accumulate at grain boundaries or on the surface of solution processed perovskites, which act as the nonradiative recombination centers , leading to PCE loss and instability of corresponding devices. , Therefore, researchers have developed different strategies to address the issue, such as modulation of grain size and orientation, , and passivation of bulk and/or surface defects by cations, anions or low-dimensional perovskites. − …”