New Earth-Abundant Thin Film Solar Cells Based on Chalcogenides

At the end of 2017 roughly 1.8% of the worldwide electricity came from solar photovoltaics (PV), which is foreseen to have a key role in all major future energy scenarios with an installed capacity around 5 TW by 2050. Despite silicon solar cells currently rule the PV market, the extremely more versatile thin film-based devices (mainly Cu(In,Ga)Se₂ and CdTe ones) have almost matched them in performance and present room for improvement. The low availability of some elements in the present commercially available PV technologies and the recent strong fall of silicon module price below 1 $/W_p focused the attention of the scientific community on cheap earth-abundant materials. In this framework, thin film solar cells based on Cu₂ZnSnS₄ (CZTS) and the related sulfur selenium alloy Cu₂ZnSn(S,Se)₄ (CZTSSe) were strongly investigated in the last 10 years. More recently, chalcogenide PV absorbers potentially able to face TW range applications better than CZTS and CZTSSe due to the higher abundance of their constituting elements are getting considerable attention. They are based on both MY₂ (where M = Fe, Cu, Sn and Y = S and/or Se) and Cu₂XSnY₄ (where X = Fe, Mn, Ni, Ba, Co, Cd and Y = S and/or Se) chalcogenides. In this work, an extensive review of emerging earth-abundant thin film solar cells based on both MY₂ and Cu₂XSnY₄ species is given, along with some considerations on the abundance and annual production of their constituting elements.