The hybrid organic-inorganic lead halide perovskite materials have emerged as
remarkable materials for photovoltaic applications. Their strengths include
good electric transport properties in spite of the disorder inherent in them.
Motivated by this observation, we analyze the effects of disorder on the energy
eigenstates of a tight-binding model of these materials. In particular, we
analyze the spatial extension of the energy eigenstates, which is quantified by
the inverse participation ratio. This parameter exhibits a tendency, and
possibly a phase transition, to localization as the on-site energy disorder
strength is increased. However, we argue that the disorder in the lead halide
perovskites corresponds to a point in the regime of highly delocalized states.
Our results also suggest that the electronic states of mixed-halide materials
tend to be more localized than those of pure materials, which suggests a weaker
tendency to form extended bonding states in the mixed-halide materials and is
therefore not favourable for halide mixing.Comment: 24 pages (preprint), 11 figure
