Candidate photoferroic absorber materials for thin-film solar cells from naturally occurring minerals: enargite, stephanite, and bournonite

Abstract

To build on the success of other mineral systems employed in solar cells, including kesterites (Cu₂ZnSnS₄) and herzenbergite (SnS), as well as mineral-inspired systems such as lead halide perovskites (CH₃NH₃PbI₃), we have searched for photoactive minerals with the additional constraint that a polar crystal structure is adopted. Macroscopic electric fields provide a driving force to separate electrons and holes in semiconductor devices, while spontaneous lattice polarisation in polar semiconductors can facilitate microscopic photo-carrier separation to enhance carrier stability and lifetimes. We identify enargite (Cu₃AsS₄), stephanite (Ag₅SbS₄), and bournonite (CuPbSbS₃) as candidate materials and explore their chemical bonding and physical properties using a first-principles quantum mechanical approach.