Integration of a 2-D Periodic Nanopattern Into Thin-Film Polycrystalline Silicon Solar Cells by Nanoimprint Lithography

The integration of 2-D periodic nanopattern defined by nanoimprint lithography and dry etching into aluminum-induced crystallization-based polycrystalline silicon thin-film solar cells is investigated experimentally. Compared with the unpatterned cell, an increase of 6% in the light absorption has been achieved thanks to the nanopattern, which, in turn, increased the short-circuit current from 20.6 to 23.8 mA/cm2. The efficiency, on the other hand, has limitedly increased from 6.4% to 6.7%. We show using the transfer length method that the surface topography modification caused by the nanopattern has increased the sheet resistance of the antireflection coating (ARC) layer as well as the contact resistance between the ARC layer and the emitter front contacts. This, in turn, resulted in increased series resistance of the nanopatterned cell, which has translated into a decreased fill factor, explaining the limited increase in the efficiency.