Thin film tandem photovoltaic cell from II-IV-V chalcopyrites

Using quasiparticle self-consistent GW (QSGW) theory, we analyze materials properties of the II-IV-V family of chalcopyrite semiconductors consisting of compounds and alloys based on (Mg,Zn,Cd)(Si,Ge,Sn)(P,As)(2), and show how they may offer excellent opportunities for the development of tandem thin-film solar cells. The constituent elements are abundant and nearly lattice-matched compounds can be found with near optimum band gaps. We show the close connection to band structures of other fourfold coordinated compounds that have led to the highest efficiency devices, and suggest potentially optimum alloys for tandem thin-film cells.