Computational screening of chalcogenides for intermediate band solar cells surpassing the Shockley-Queisser limit

Intermediate band solar cells offer a promising avenue to surpass the Shockley–Queisser limit of ∼ 30 % that constrains conventional single-junction devices, with the potential to approach an efficiency limit of ∼ 45 % in terrestrial environments by incorporating a metallic band within the valence-conduction gap. Yet, their practical realization is challenged by difficulties in developing suitable intermediate band (IB) materials. Current approaches, which involve adding inclusions or utilizing highly mismatched alloys, often degrade material quality or present significant technological hurdles. A possible solution that remains underexplored, is to identify crystalline materials that inherently possess an IB and fine-tune their properties. In this work, thousands of crystalline chalcogenides are analyzed using a detailed balance model to quantitatively evaluate their expected efficacy as IB materials. Notably, orthorhombic VB 1 VIA 2 and IA 4 VIA 6 compounds, such as Ta 1 Se 2 and Cs 4 S 6 , are projected to achieve maximum efficiencies exceeding 35%, that is, surpassing the Shockley–Queisser limit. The interplay of IB filling and chemical substitution on the properties of these systems is analyzed, to unravel the impact on performance. This study not only identifies new material candidates for IB solar cells, but also provides insights into efficiency-property relations, hence advancing the understanding of these systems.