A phosphorus-containing passivator, a perovskite solar cell, a photovoltaic module, a photovoltaic system, and an electric apparatus are provided. The phosphorus-containing passivator includes an ionic compound, the ionic compound includes a cationic group, and the cationic group has a structure represented by formula (I): A-L-B (I); where A represents an organophosphorus group with lone pair electrons, B represents a positively charged organophosphorus salt group, and L represents a linking group between the organophosphorus group and the organophosphorus salt group. The lone pair electrons of the organophosphorus group can form strong PPb coordination bonds with under-coordinated lead ions in the bulk phase and/or at the upper and lower interfaces of a perovskite light-absorbing layer, passivating low-coordinated lead ion defects; the organophosphorus salt group can form low-dimensional perovskite at the upper and lower interfaces of a perovskite layer, passivating the interfaces of the perovskite layer and suppressing ion migration.