  We optimize multilayered anti-reflective coatings for photovoltaic devices,
using modern evolutionary algorithms. We apply a rigorous methodology to show
that a given structure, which is particularly regular, emerge spontaneously in
a very systematical way for a very broad range of conditions. The very
regularity of the structure allows for a thorough physical analysis of how the
designs operate. This allows to understand that the central part is a photonic
crystal utilized as a buffer for light, and that the external layers have the
purpose of reducing the impedance mismatch between the outer media and the
Bloch mode supported by the photonic crystal. This shows how optimization can
suggest new design rules and be considered as a source of inspiration. Finally,
we fabricate these structures with easily deployable techniques.
