Insights into Backscattering Suppression in Solar Cells from the Helicity-Preservation Point of View

The efficiency of a solar cell depends on many factors, including the amount of light that is reflected from the solar-cell stack, and hence immediately lost for energy conversion. Arrays of dielectric nanoparticles have been proposed as antireflective coatings, their low profile being particularly suited to ultrathin solar cells, where traditional etching is impractical. This work studies the physics of back-reflection from the point of view of symmetries and conservation laws, and ties antireflection performance to two conditions: a high enough degree of discrete rotational symmetry of the array, and the suppression of crosstalk between the two helicities of the electromagnetic field.