  Recently, an aziridinium lead iodide perovskite was proposed as a possible
solar cell absorber material. We investigated the stability of this material
using a density-functional theory with an emphasis on the ring strain
associated with the three-membered aziridinium cation. It is shown that the
aziridinium ring is prone to opening within the PbI$_3$ environment. When
exposed to moisture, aziridinium lead iodide can readily react with water. The
resultant product will not likely be a stoichiometric lead halide perovskite
structure.
