  The increase of cell efficiency resulting from using a diffraction grating as
a back reflector is investigated. An enhancement coefficient is introduced as a
figure of merit that accounts for the ability of the rear grating to increase
the generation of electric carriers. According to results in this paper, a
diffraction-grating-like relief on the rear face of the photovoltaic cell may
reduce the intensity of the specular reflection while favouring the intensity
of high-angle rays. In this way, the path-length of reflected rays increases,
and so does the efficiency of the cell.
