Light trapping efficiency in thin-film silicon photovoltaic cells with a photonic pattern

We present a theoretical study of amorphous and crystalline thin-film solar cells with a periodic pattern on a sub-micron scale realized in the silicon layer and filled with silicon dioxide right below a properly designed antireflection coating. The study and optimization of the PV structure as a function of all the photonic crystals parameters allows to identify the different roles of the periodic pattern and of the etching depth in determining an increase of the absorption. By patterning thin-film silicon solar cells with a periodic etching in addition to an antireflection coating, we found an increase of the short-circuit current up to 36.5% for crystalline silicon. These results demonstrate the advantage of a wavelength-scale, photonic-crystal based approach.