  Instability of hybrid organic-inorganic halide perovskites hinders their
development for photovoltaic applications. First-principle calculations are
used for evaluation of a decomposition reaction enthalpy of hybrid halide
perovskites, which is linked to experimentally observed degradation of device
characteristics. However, simple criteria for predicting stability of halide
perovskites are lacking since Goldschmidt's tolerance and octahedral
geometrical factors do not fully capture formability of those perovskites. In
this paper, we extend the Born-Haber cycle to partition the reaction enthalpy
of various perovskite structures into lattice, ionization, and molecularization
energy components. The analysis of various contributions to the reaction
enthalpy points to an ionization energy of a molecule and a cage as an
additional criterion for predicting chemical trends in stability of hybrid
halide perovskites. Prospects of finding new perovskite structures with
improved chemical stability aimed for photovoltaic applications are discussed.
