Tin sulfide is an attractive absorber material for low-cost thin-film solar cells. Despite the ideal physical properties of bulk SnS, the photovoltaic conversion efficiencies achieved in devices to date have been no greater than 2. Assessment of the valence band energy of the stable orthorhombic phase of SnS reveals a low ionisation potential (4.7 eV) in comparison to typical absorber materials (CdTe, CuInSe2, and Cu2ZnSnS4). A band mis-alignment is therefore predicted with commonly used back contact and buffer layers. Alternative configurations are proposed that should improve device performance.
Bibliographical noteFunding Information:
We thank Gilles Dennler for useful discussions and acknowledge membership of the UK's HPC Materials Chemistry Consortium, which was funded by EPSRC grant EP/F067496. A.W. acknowledges support from the Royal Society for a University Research Fellowship, and L.A.B was funded by EPSRC (Grant No. EP/G03768X/1).