Hybrid organic–inorganic perovskites
are exceedingly interesting
candidates for new solar energy technologies for both ground-based
and space applications. However, their large-scale production is hampered
by the lack of long-term stability, mostly associated with ion migration.
The specific role of noncovalent bonds in contributing to the stability
remains elusive, and in certain cases controversial. Here, we perform
an investigation on a large perovskite chemical space via a combination
of first-principles calculations for the bond strengths and the recently
developed sure independent screening and sparsifying operator (SISSO)
algorithm. The latter is used to formulate mathematical descriptors
that, by highlighting the importance of specific noncovalent molecular
bonds, can guide the design of perovskites with suppressed ion migration.
The results unveil the distinct nature of different noncovalent interactions,
with remarkable differences compared to previous arguments and interpretations
in the literature on the basis of smaller chemical spaces. In particular,
we clarify the origin of the higher stability offered by formamidinium
compared to methylammonium, which shows to be different from previous
arguments in the literature, and the reasons for the improved stability
given by the halogen F and explain the exceptional case of overall
stronger bonds for guanidiunium. Within the stability boundaries given
by the Goldschmidt factor, the found descriptors give an all-in-one
picture of noncovalent interactions which provide more stable configurations,
also including interactions other than H bonds. Such descriptors are
more informative than previously used quantities and can be used as
a universal input to better inform new machine learning studies.