However, all reported Se solar cells have metallic back contacts. To demonstrate the potential feasibility of Se as a wide-bandgap absorber for tandems, herein, bifacial single-junction selenium solar cells with device areas above 0.4 cm2 are reported. When illuminating through the n-type contact, the bifacial cell power conversion efficiency (PCE) is 5.2%, similar to a standard monofacial cell. The efficiency is lower (2.7%) when illuminating through the p-type contact, which is attributed to low carrier diffusion lengths and lifetimes in selenium. This suggests the necessity to invert the typical single-junction device structure when incorporating it into a tandem device.
Tomas H. Youngman, Rasmus Nielsen, Andrea Crovetto, Brian Seger, Ole Hansen, Ib Chorkendorff, Peter C. K. Vesborg
Solar RRL, Volume 5, Issue 7, 2100111
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