Efficiency limitations of thermally evaporated thin-film SnS solar cells

Thin-film solar cells with SnS as absorber material were prepared by thermal evaporation of SnS. The cells were built in a superstrate configuration using Al : ZnO coated glass as front contact with an intrinsic ZnO buffer layer and/or CdS window layer and a gold back contact. The IV-characteristics and external quantum efficiency of the devices were determined. The best CdS/SnS solar cell showed a conversion efficiency of 1.6%, a short circuit current density of 19 mA cm(-2) and an open circuit voltage of 217 mV. Moreover, band alignments at the interfaces AZO/SnS, CdS/SnS and SnS/Au were determined with in situ x-ray photoelectron spectroscopy to correlate the open circuit voltage limitations of the investigated solar cell device structures.