Macroporous silicon as an absorber for thin heterojunction solar cells

Abstract

Meso- and macroporous silicon is widely studied for several applications in photovoltaic devices. We investigate macroporous silicon as an absorber for thin-film silicon solar cells. Here we review the progress of our work. We demonstrate the separation of 85 × 85 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> -sized macroporous silicon layer from a monocrystalline n-type Cz silicon wafer. The measured optical absorption of a 26 μm thick macroporous silicon layer allows for a short-circuit current density of 37.6 mA cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> . We measure an effective carrier lifetime of up to (38.8 ± 3.9) μs for (33 ± 2) μm thick surface passivated macroporous silicon layer. We use an analytical model to determine average surface recombination velocity S= (10 ± 2) cm s <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> for the MacPSi layer. We prepare macroporous silicon heterojunction solar cells with an energy-conversion efficiency of 7.2 %.